CN101375482B - Power supply system - Google Patents

Power supply system Download PDF

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Publication number
CN101375482B
CN101375482B CN2007800037127A CN200780003712A CN101375482B CN 101375482 B CN101375482 B CN 101375482B CN 2007800037127 A CN2007800037127 A CN 2007800037127A CN 200780003712 A CN200780003712 A CN 200780003712A CN 101375482 B CN101375482 B CN 101375482B
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power
output
storage battery
battery
voltage
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CN2007800037127A
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CN101375482A (en
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山田和夫
松井亮二
八木有百实
吉见直辉
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Sharp Corp
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Sharp Corp
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Priority claimed from JP2006120659A external-priority patent/JP5175451B2/en
Priority claimed from JP2006222676A external-priority patent/JP5028049B2/en
Priority claimed from JP2006257424A external-priority patent/JP5028056B2/en
Application filed by Sharp Corp filed Critical Sharp Corp
Priority claimed from PCT/JP2007/051187 external-priority patent/WO2007086472A1/en
Publication of CN101375482A publication Critical patent/CN101375482A/en
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    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E10/00—Energy generation through renewable energy sources
    • Y02E10/50—Photovoltaic [PV] energy
    • Y02E10/56—Power conversion systems, e.g. maximum power point trackers

Abstract

A power supplying system that smoothes a solar photovoltaic power generation output to enable a time shift. A power supplying system has a DC power supply string comprising a parallel combination of a DC power supply and a storage battery and also has a DC/AC power converting apparatus that connects the DC power supply string to a power system or a load. A switch, which is connected between the DC power supply and the storage battery, is used to selectively supply an output power of the DC power supply or a combined output power of the DC power supply and storage battery to the DC/AC power converting apparatus. In this way, a solar photovoltaic power generation output is smoothed to enable a time shift.

Description

Power-supply system
Technical field
The present invention relates to power-supply system, it comprises DC power supply string, in this DC power supply string parallel connection be used for exporting from direct current (DC) power supply and storage battery such as the DC power of electric organs such as solar cell, wind turbine generator and fuel cell; More specifically, relate to a kind of power-supply system, the variable power of its level and smooth DC power supply, and the power output of DC power supply carried out time shift.
The invention still further relates to a kind of power-supply system, the power output of its conversion DC power supply under the situation that does not need complicated control, the generation quantity of power of this DC power supply is bigger according to environmental change.The invention still further relates to a kind of power-supply system, thereby its gross power that can excessively not use a storage battery of a plurality of storage batterys and obtain each storage battery through balanced each cell voltage provides maximum power.
Background technology
Can perhaps make its reverse flow to commercial power with offering electrical load by the power output that generates such as electric organs such as solar cell, wind turbine generator and fuel cells.But; In the prior art; The output of solar cell, wind turbine generator or fuel cell etc. is stored in the storage battery; And in power governor, change, and therefore need the transfer power of power-limiting adjuster, run off to avoid the power from the storage battery to the commercial power with the storage battery power concentration.The transfer power restriction of power governor has caused the generated output of restriction solar cell, wind turbine generator or fuel cell; And as a result of can't obtain the maximum output of solar cell, wind turbine generator or fuel cell thus, and can't make the power that is generated export reverse flow fully.
In order to solve this type of problem; The power storage electro-optical system that Japan's publication is 2002-171674 number is equipped with the photoelectric power adjuster; It has the first power transfer parts; These first power transfer parts and be connected solar cell and electric power system between electric power system carry out co-operation, and have the second power transfer parts that are connected between the power storage parts and the first power transfer parts.Load is connected between power governor and the electric power system; And arrange to have control assembly; Be used for through being connected the received power detection part between load and the electric power system; Control the second power transfer parts, thereby received power can not become less than preset power from power storage parts power output the time.
According to Japanese publication 2002-171674 number; Regulate the output of storage battery through the second power transfer parts; And, discharge the power at midnight of storage in advance simultaneously efficiently when during to electric power system reverse flow power, stopping output from storage battery by photovoltaic power generation.
In Japanese publication 2002-34175 number; A kind of method is disclosed; Be used for carrying out the MPPT maximum power point tracking control operation, with the maximum power of acquisition from solar cell, and parallelly connected solar cell and storage battery; And carry out the storage battery joint operation, and the handover operation that need not bother.According to this system, when the generation quantity of power of solar cell is obviously hanged down, can export the power of storage battery.
In Japanese publication 6-266458 number, a kind of technology is disclosed, be used for farthest utilizing the generating capacity of solar cell, effectively utilize insolation, and extending battery life.
System in Japanese publication 2002-34175 number and the Japanese publication 6-266458 number is proposed; Thereby on maximum power, operate photovoltaic power generation; And farthest obtain to generate power, and these systems mainly focus on carrying out MPPT maximum power point tracking no matter insolation changes the variable power ground that causes.
Japan's publication relates to a kind of optoelectronic device 2001-224142 number; It carries out the storage battery joint operation, this operation comprise by solar cell and and a plurality of strings of constituting of secondary cell, and the only operation of solar cell; And do not have the trouble handover operation; Preferably, be charge in batteries in the daytime, and as much as possible storage battery maintained full-charge state to prepare autonomous operation.With utilizing Figure 31 to describe the equipment in Japanese publication 2001-224142 number.
Shown in figure 31, each the string 120a, the 120b that comprise solar cell 121a, 121b and secondary cell 122a, 122b respectively comprise converter 125a, 125b.When sunlight fully shines in the daytime, the generation power output of solar cell 121a and 121b is offered converter 125a and 125b.If shine upon deficiency, then to converter 125a and 125b power is provided from secondary cell 122a and 122b.According to the power demand of load 126, operate each converter 125a, 125b, so that necessary power to be provided.Because for each string has all been arranged converter 125a, 125b, so the input voltage of converter 125a, 125b, promptly the voltage of solar cell 121a, 121b and secondary cell 122a, 122b is provided with for each string independently.
To secondary cell 122a, 122b charging the time; Preset in secondary cell 122a, 122b one side and be used for the switch of bypass anti-return diode 124a, 124b; And connect the by-pass switch of wanting storage batteries when enough when shining upon, to charge from solar cell 121a, 121b.
Figure 32 shows another example of conventional power-supply system.Between secondary cell 122a, 122b and converter 125, arrange DC/DC transducer 127a, 127b, thereby the discharge power of control secondary cell 122a, 122b is to match the input voltage of converter 125.In other words; Need be provided with to such an extent that equate with the output voltage of solar cell 121b solar cell 121a; But,, progressively raise and perhaps progressively reduce secondary cell 122a and secondary cell 122b voltage predetermined input voltage with coupling converter 125 through DC/DC transducer 127a and 127b.According to this type of control, all storage batterys will have identical voltage, and therefore can be to a battery overdischarge.
To secondary cell 122a, 122b charging the time, preset the switch of bypass DC/DC transducer 127a, 127b, and want the by-pass switch of storage batteries, with from rechargeable solar battery when shining upon connection when enough.
Therefore, power-supply system generally adopts the DC/AC power converter, is connected to electrical load or electric power system with the electric organ (for example solar cell and wind turbine generator or fuel cell) that will use natural energy.But, the conversion efficiency when the DC/AC power converter can reduce low output as everybody knows.
Thus, shown in figure 33, conventional power-supply system has the output of a plurality of solar cell 131a, 131b and 131c, thereby it is connected at terminal box 132 places and compiles.After this, through converter 133a, 133b and the 133c of a plurality of parallel connections, connect load 134 or business system power 135, and control the operation of converter 133a, 133b and 133c through control unit 136.
The system that is used for controlling converter be used for the domestic solar battery system, or have several MW can battery system to the large-sized solar of tens kW levels.
In Japanese publication 6-266458 number, system shown in Figure 33 is disclosed as following technology: a plurality of little output converters that are connected in parallel, and when the generation quantity of power of solar cell hour, reduce the number of work converter.
Japan's publication discloses following technology 2000-305633 number: according to pre-defined rule, for example according to the order of the little power output amount of each converter, or according to the order of little operating time, or randomly, the converter that selection will be operated.
Japan's publication discloses a kind of power-supply system 2004-146791 number; Comprise a plurality of DC power supply strings; Be used for being stored in the generation power output of a plurality of DC power supplys that comprise solar cell, fuel cell or the like in each storage battery, with power output as required.
Summary of the invention
Japan's publication discloses a kind of system 2004-146791 number, and it fills power at midnight basically, and discharges power in the daytime, wherein when utilizing photovoltaic power generation when charging (at autonomous operation time) to carry out charge and discharge through the power transfer parts.Thus, need improve the conversion efficiency of this system largely.Even because conversion loss is also arranged, so it is not suitable for being used for frequently charge and discharge repeatedly for the effective conversion circuit.Therefore, it is not suitable for smoothly having the energy of more high-power variation, for example natural energy.
Japan's publication 2002-34175 number supposition is exported from storage battery when the output decline of solar cell, and is provided with the output voltage of storage battery to such an extent that be significantly less than maximum power point voltage thus.Thus, if when the generation quantity of power of solar cell is sufficient the power of output storage battery, then solar cell can be with the efficient work of non-constant.
Additional have most of system of conventional storage battery to have the additional storage battery that is used for emergency, be that the frequency of this type of charge in batteries is lower from solar cell, and efficient is not too important thus.But, be necessary for battery system charges and discharges continually, smoothly to have the output of the photovoltaic power generation of more high-power variation consistently.In charging and discharge equipment, voltage is changed twice, promptly in when charging and when discharging, and thus total conversion efficiency be conversion efficiency square.For example, in when charging or the conversion efficiency when discharging be that through carrying out charge and discharge, total conversion efficiency is 0.97 * 0.97=94% in 97% the conversion equipment.
The circuit that comprises conversion equipment generally needs basic current, and wherein ifs circuit is to be bordering on rated capacity work, and then efficient is gratifying, and trickle power transfer can cause not satisfied efficient.Therefore, when the output of in storage battery, filling with photovoltaic power generation, if insolation weak (for example at dawn or before sunset), then the output of photovoltaic power generation is less, and therefore consumed power only makes conversion equipment work, and efficient can descend.
In prior art example shown in Figure 31,, and in prior art example shown in Figure 32, between storage battery and converter, arrange DC/DC transducer 127a, 127b for each string is arranged converter 125a, 125b.Realization work is set to target on the maximum power point of solar cell, and with the generation power of maximization solar cell, but the number of assembly can increase, and system becomes expensive.
In Japanese publication 6-165513 number and Japanese publication 2000-305633 number; When the generation quantity of power of solar cell hour; The number of minimizing work converter, and according to the order of little power output amount, or according to the order of little operating time, or select converter randomly.Thus, need to detect solar cell output, and need utilize this type of complicacy that detects output control.The configuration of this control unit and control become complicated thus.Control appliance need about when the generation quantity of power of solar cell become big estimating rapidly, and need Advanced Control.Because converter is switched in the variation according to the generation quantity of power of solar cell, often change in the bigger solar cell so generate quantity of power therein, it is big that the number of handover operation becomes, and need the commutation circuit of high reliability.In addition, because output is according to the generation quantity of power variation of solar cell, so can force load and business system power to be worked astatically.The maximum output of system is confirmed by the generation quantity of power of solar cell, and uncontrollable maximum power.
According to Japanese publication 2004-146791 number, need to arrange the output voltage adjustment component so that use from the peak power output of each solar cell string with different capacity generative capacity with, as peak power output.If the voltage of each storage battery can be balanced through the output voltage adjustment component, then can obtain output, and can export the overall power of each storage battery from each storage battery.If but can't balanced each battery tension, then can obtain output, and can't obtain output from the storage battery of low-voltage from high-tension storage battery.Thus, can't obtain the overall power of each storage battery.In addition, because obtain output, so the frequency of utilization of storage battery has deflection from high-tension storage battery.
Consider above problem, the invention provides a kind of power-supply system, its smoothly photovoltaic power generation output, and enable to carry out time shift.
The present invention also provides a kind of power-supply system, and it is the complicacy control of required power converting unit not.The present invention also provides a kind of power-supply system, and it can control maximum power.
The present invention also provides a kind of power-supply system, its through obtaining each storage battery overall power and prevent excessively to use a storage battery, maximum power is provided.
In order to overcome the above problems, power-supply system of the present invention comprises: DC power supply string wherein is parallel-connected to the DC power supply with storage battery; The DC/AC power converter is used for the DC power supply is series-connected to electric power system or load; And switch, be connected between DC power supply and the storage battery, be used for switching the power output of DC power supply or the associating power output of DC power supply and storage battery, and offer the DC/AC power converter.The power output of level and smooth thus photovoltaic power generation, and time shift becomes possibility.
In order to overcome the above problems, power-supply system of the present invention comprises: the solar cell string wherein is parallel-connected to solar cell with storage battery; The DC/AC power converter is used for solar cell is series-connected to commercial power or load; The battery status detecting unit is used for detecting the state of storage battery; Export detecting unit, be used for detecting the power output of DC/AC power converter; And output control unit, be used for according to the battery condition of battery status detection and the power output of output detection, control DC/AC power converter.Because control DC/AC power converter, so utilize not expensive system to obtain output smoothing and time shift.
In order to overcome the above problems, a plurality of power-supply devices that power-supply system of the present invention will comprise DC power supply string (wherein memory cell being parallel-connected to the DC power supply) and DC/AC power converter are parallel-connected to commercial power system or load.Thus, in the present invention, eliminated complicated control, and can reduce the number of times of operation change over switch, this is because a plurality of power-supply devices are parallel-connected to electric power system or load.Through storing memory cell into, can realize time shift from the power output of DC power supply.
In order to overcome the above problems, in power-supply system of the present invention, a plurality of DC power supply strings wherein are parallel-connected to the DC power supply with storage battery; The DC/AC power converter is used for said a plurality of DC power supplys are series-connected to electric power system or load; And the storage battery control unit, be used for controlling the DC/AC power converter, thereby make each battery tension become equal basically.Obtain the overall power of each storage battery thus, and maximum power can be provided.A storage battery can be excessively do not used, and the life-span of system can be prolonged thus.
According to the present invention, can the distinctive output of balanced natural energy resources change.In addition, according to the present invention, can realize high efficiency charge/discharge, and not have the conversion loss of circuit.Can time shift be carried out in the output of solar cell and wind turbine generator, and when utilizing easily and effectively, it taken out.When being charge in batteries, need not carry out MPPT maximum power point tracking, thus can simplified system.According to the present invention; Because make the power of photovoltaic power generation directly be charge in batteries; So do not deposit power consumption as the circuit in passing through the prior art of circuit charge/discharge; Can be independent of the amplitude ground of the quantity of power that is generated thus, with substantially invariable charge exchange power.
According to the present invention, when connecting a plurality of solar cell string, can utilize a power controller to carry out equilibrium and control.Usually; In large-scale power-supply system, if storage battery and solar cell are connected in parallel, storage battery and solar cell compensate each other; And the control circuit that is used for collective's output is necessary; But in the present invention, this is undertaken by a DC/AC conversion equipment, and need not be used for controlling the conventional control unit of collective's output.
According to the present invention, utilize not expensive system to realize level and smooth output and time shift.Because the discharging current of storage battery can excessively not flow, thus can realize the stable of system, and can prolong the life-span of system, because there is not overcurrent to flow to battery.
System configuration is simple, and can reduce equipment investment, because can a plurality of solar cells be series-connected to a converter, and without the DC/DC transducer.
In addition, after system start-up, the present invention is updated periodically the batteries of high-voltage value, and increases to the storage battery that contribution is done in discharge, and can in the time of minimum, system be brought into stable state reliably thus.
Through in each storage battery, switch being installed, during shining upon, be charge in batteries, and can alleviate the charging variable condition of storage battery from solar cell.Because pass through open circuit/closed switch by storage battery at night, storage battery is not discharged, thus can reduce the variation of the battery tension when starting in the morning, and can more stablize the startup of easily carrying out system.
According to the present invention, can reduce complicacy control, and can reduce the number of operations of commutation circuit power-supply system.The power that the DC power supply generates can and be supplied to by time shift.Through the maximum power that obtains in memory cell, to store, can control the peak power output amount.
According to the present invention, can obtain the overall power of each storage battery.Prevented particular battery of excessive use.In addition, the present invention does not need complicated control, and can realize power-supply system of the present invention by very simple circuit thus.
Description of drawings
Fig. 1 is the block diagram according to the power-supply system of first embodiment of the invention;
Fig. 2 is the power-supply system allocation plan according to comprising of first embodiment of the invention of a plurality of solar cell strings;
Fig. 3 is for showing the view according to the relation of the output voltage of the solar module of first embodiment of the invention and power output;
Fig. 4 is that demonstration is according to the charging capacity of the battery module of first embodiment of the invention and the view of the relation between the charging;
Fig. 5 is the view of description according to the control method of the output of paying attention to level and smooth solar module of first embodiment of the invention;
Fig. 6 is the view of description according to the control method of the charging current of the control solar module of first embodiment of the invention;
Fig. 7 is the view of the control method of the power-supply system of describing first embodiment of the invention, and for when the explanatory diagram of controlling when during the special time width, keeping constant output;
Fig. 8 is the view of the control method of the power-supply system of description first embodiment of the invention, and controls with flowing smoothly and the explanatory diagram of output along big insolation variation for working as;
Fig. 9 is the block diagram of power-supply system of the example 2-1 of second embodiment of the invention;
Figure 10 is the charging capacity of the solar module of demonstration second embodiment of the invention and the view of the relation between the charging;
Figure 11 is the view of the darg data of demonstration second embodiment of the invention;
Figure 12 is the view of the relation of the generation quantity of power of the solar module that shows insolation intensity, second embodiment of the invention and efficient;
Figure 13 is the view of the darg data of demonstration second embodiment of the invention;
Figure 14 is the view of the relation of the generation quantity of power of the solar module that shows insolation intensity, second embodiment of the invention and efficient;
Figure 15 A is the block diagram of the example 2-3 of second embodiment of the invention;
Figure 15 B is the first control circuit figure of the example 2-3 of second embodiment of the invention;
Figure 15 C is the second control circuit figure of the example 2-3 of second embodiment of the invention;
Figure 16 is the view of the relation of voltage E and the electric current I of the storage battery of describing second embodiment of the invention with frame format;
Figure 17 A is the block diagram of the example 2-4 of second embodiment of the invention;
Figure 17 B is the first control circuit figure of the example 2-4 of second embodiment of the invention;
Figure 17 C is the second control circuit figure of the example 2-4 of second embodiment of the invention;
Figure 18 is for describing the view according to the control method of the power-supply system of second embodiment of the invention, and for when the explanatory diagram of controlling when thinking that the special time width is kept constant output;
Figure 19 is the block diagram according to the power-supply system of third embodiment of the invention;
Figure 20 is the block diagram according to an example of third embodiment of the invention;
Figure 21 is the control algolithm of third embodiment of the invention;
Figure 22 is the sequential chart of the control of description third embodiment of the invention;
Figure 23 is the sequential chart of another control of description third embodiment of the invention;
Figure 24 is the block diagram according to the power-supply system of fourth embodiment of the invention-1;
Figure 25 is the block diagram according to the power-supply system of fourth embodiment of the invention-2;
Figure 26 is the flow chart of fourth embodiment of the invention-2;
Figure 27 is described in the voltage of each storage battery of passing in time in the fourth embodiment of the invention-3 and the block diagram of electric current;
Figure 28 is described in the voltage of each storage battery of passing in time in the fourth embodiment of the invention-3 and the view of electric current;
Figure 29 is the flow chart of fourth embodiment of the invention-3;
Figure 30 is the view that is described in the output current of each DC power supply string in the fourth embodiment of the invention-3;
Figure 31 is the allocation plan of prior art first power-supply system;
Figure 32 is the allocation plan of prior art second source system; And
Figure 33 is the allocation plan of prior art the 3rd power-supply system.
Description of reference numerals
1 solar cell string
2 are connected to electric power system
The 3DC/AC conversion equipment
11 solar modules
12 battery modules
13 switches
14 current sensors
15 anti-return diodes
16 nodes
17 connecting lines
18 holding wires
19 voltage detection units
20 anti-return diodes
Embodiment
The first embodiment of the present invention and second embodiment relate generally to the variable power that is used for level and smooth electric organ and enable the power-supply system to power output the carrying out time shift that generates.
The third embodiment of the present invention relates generally to that be used under the situation that does not need complicated control will be to from the power-supply system of carrying out power transfer according to the generation power output of the bigger DC power supply of environmental change.
In addition, the fourth embodiment of the present invention relates generally to the storage battery that is used for obtaining the overall power of each storage battery, prevents in each of a plurality of DC power supply strings, to arrange simultaneously by the power-supply system of using with the deflection mode.
Next coming in order are described first to the 4th embodiment of the present invention.
(first embodiment)
The power-supply system of first embodiment comprises: DC power supply string wherein is parallel-connected to the DC power supply with storage battery; The DC/AC power converter is used for the DC power supply is series-connected to electric power system or load; And the switch between DC power supply and storage battery.Switch the power output of DC power supply or the associating power output of DC power supply and storage battery through switch, and offer the DC/AC power converter.The power output of level and smooth thus DC power supply, and time shift becomes possibility.
The DC power supply is typically solar cell, but also can be wind turbine generator or fuel cell.It also can be the equipment of combined solar battery and wind turbine generator, solar cell and fuel cell or wind turbine generator and fuel cell.
To be that solar cell is described first embodiment with the DC power supply.Therefore, be the solar cell string with DC power supply string descriptor.
Preferably, storage battery possesses the charging capacity of the power output of at least 0.3 hour DC power supply of storage generation.Preferably, arrange the charging capacity of the power output that 0.5 hour DC power supply of storage generates, and the charging capacity of the power output that generates of the DC power supply of further storing a hour.Obtain the capacitance balance of storage battery and solar cell thus, and as a result of, can utilize originally just outfit to charging in the current limit function of solar cell or discharging.
Preferably, solar cell comprises the solar cell device of excellent in temperature characteristic.Thus, when the operating voltage range of solar cell was fixed on the voltage of storage battery, it can be set to the suitable voltage scope near maximum power.
Preferably, the solar cell device of excellent in temperature characteristic is a Thinfilm solar cell component.The Thinfilm solar cell component excellent in temperature characteristic, and can be set to the suitable voltage scope.Preferably, battery module is not for having owing to lacking the battery that charging can make cycle degradation and memory effect.Thus can the voltage range setting is narrower.Particularly, lithium ion battery is preferred, because the charge/discharge curve is more smooth, and cycle degradation and memory effect when not having partial charging/discharge.
Like hope ground, the maximum power point voltage of exporting when storage battery is set to respect to receive on predetermined temperature at the solar cell that constitutes the DC power supply predetermined insolation amount (Vpmax), can obtain to be greater than or equal to 60% and be less than or equal to the voltage range of 100% power.Voltage range narrows down thus, and the level and smooth power output of solar cell.
Preferably, through the anti-return element, solar cell is directly connected to storage battery.Because storage battery is directly charged and obstructed overvoltage conversion equipment by the generation power of solar cell, so eliminated the conversion loss that voltage conversion apparatus causes thus.Thus, can high efficiency smoothly export.Storage battery directly is connected with solar cell, and when the insolation amount hour, for example morning or evening or cloudy day or rainy day, utilize little charging electricity value to charge, and can obtain the effect that CV charges thus.
The DC power supply also comprises time monitoring unit, voltage detection unit or current detecting unit, and as hoping ground, when satisfying predetermined condition for one in time monitoring unit, voltage detection unit or the current detecting unit, diverter switch.The suitable voltage scope is set thus.
Said predetermined condition is i) when the detection electrorheological of the detection voltage of voltage detection unit or current detecting unit must be greater than or equal to predetermined value; Begin output (switch and connect); When perhaps being less than or equal to predetermined value, stop output (switch and end) when becoming; Ii), begin output (switching is connected) or stop output (switch and end) according to the scheduled time of time monitoring unit; Iii) when the detection electrorheological of the detection voltage of voltage detection unit or current detecting unit must be greater than or equal to predetermined value, and according to scheduled time of time monitoring unit, begin output (switch and connect) or stop output (switch by); And iv) when the detection electrorheological of the detection voltage of voltage detection unit or current detecting unit must be less than or equal to predetermined value, and according to scheduled time of time monitoring unit, begin output (switch and connect) or stop output (switch by).The time of magnitude of voltage, current value and time shift of level and smooth photovoltaic power generation output of being used for can be set arbitrarily then.
Like hope ground, control DC power supply string is to export preset power from the DC/AC conversion equipment.Can control the output of solar cell thus.When switch is opened a way, obtaining the output of solar cell, like hope ground, according to maximum power point tracing method operation solar cell.Can obtain maximum power from solar cell then, and not limited by storage battery.
Like hope ground, DC power supply string and a plurality of DC/AC conversion equipment are connected in parallel, and as hope ground, arrangement anti-return element in each DC power supply string.A plurality of DC power supply strings can connect in the ball bearing made using configuration, and can obtain very large power-supply system.
Below will describe each building block of first embodiment of the invention in detail.To be that solar cell is described first embodiment with the DC power supply, but the DC power supply can be wind turbine generator or fuel cell.
Fig. 1 shows the block diagram of first embodiment of the invention, and wherein power-supply system comprises: solar cell string 1 and DC/AC conversion equipment 2, and be connected to electric power system 3.Electric power system is so-called commercial power system, and through selling electric power by power-supply system of the present invention to the unnecessary power of this electric power system reverse flow.Power-supply system can be connected to the load of non-electricity system 3.Load is: the street lamp under the communal facility situation, traffic lights, indicating device, direction plate or the like; Motor under factory's situation, power apparatus, air-conditioning, illumination apparatus or the like; Office equipment under office's situation, for example personal computer and photocopier, air-conditioning, illumination apparatus or the like; Shopper window under the situation of shop, air-conditioning, illumination apparatus or the like; And the TV under the home background, refrigerator, washing machine, air-conditioning, dust catcher or the like.
DC/AC conversion equipment 2 is so-called converter, and it converts direct current into interchange, and can be any method use, for example utilize the method for high-frequency insulation transformer and carry out PWM control and utilize the transformer insulated method of commercial frequency.The DC/AC conversion equipment that is arranged in each solar cell string can or can be difference for same type.
Solar cell string 1 is made up of following: solar module 11, battery module 12, switch 13, current sensor 14 and anti-return diode 15.Through anti-return diode 15, solar module 11 is connected to node 16, and battery module 12 is connected to node 16 through switch 12.Node 16 is connected to current sensor 14.Switch 13 comprises connection/cutoff switch or the like, wherein when switch 13 is connected, obtains the output of uniting of solar module 11 and battery module 12.When switch 13 ends, only obtain output from solar module 11.
Current sensor 14 is inserted into the outlet side of solar cell string 1, and detects output current.Connecting line 17 indication ground wires are used for solar module 11 and battery module 12 are connected to DC/AC conversion equipment 2.Holding wire 18 is a connecting line, is used for charge/discharge state to DC/AC conversion equipment 2 notice battery modules 12.Voltage detection unit 19 is arranged in the battery module, and detection output is sent out to DC/AC conversion equipment 2 through holding wire 18.Voltage detection unit 19 can be arranged at the outside of battery module; If perhaps solar cell string 1 is single; Then do not need special arrangements voltage detection unit 19, and can detect voltage (because voltage is identical) in the connecting portion office of DC/AC conversion equipment 2.
In DC/AC conversion equipment 2 porch, electric current is a solar module 11 and the combination of the electric current of battery module 12, and voltage detection unit 19 must be in the exit of storage battery thus, even solar cell string 1 is single also like this.
Fig. 2 shows the power-supply system allocation plan of a plurality of solar cell strings 1 of the connection among first embodiment.As shown in Figure 2, a plurality of solar cell strings 1 are connected in parallel through anti-return diode 20, and are connected to electric power system 3 through DC/AC conversion equipment 2.For with Fig. 1 in identical part indicate identical Reference numeral.
Holding wire 18 be used for exchanging the voltage detection unit 19 that in battery module 12, comprises information of voltage, capacity counter about the information of charged state, rub-out signal or the like when breaking down.Can use common communication protocol, for example RS-232C and RS-485.
The details of each part of Fig. 1 and power-supply system according to first embodiment of the invention shown in Figure 2 is described now.
< solar module >
The solar module that in first embodiment, uses can for: through connecting the crystal type solar module that a plurality of crystal type solar battery cells form; Wherein comprise the solar module that is processed the unit that is connected in series through the thin-film solar cells that on substrate of glass, forms Si semiconductor or synthesized semiconductor such as methods such as CVD thereby utilize; Perhaps utilize the solar module of the solar cell (wherein piling up crystallized silicon or amorphous silicon) of tandem structure.
Normal power source system keeps track maximum power point, its temperature according to insolation condition and solar module changes, thereby and the quiescent potential Be Controlled make the power of output become maximum.But in first embodiment, the voltage of controlling the feasible battery module that connects becomes the quiescent potential of solar module.Thus, the quiescent potential with solar module is restricted to the wherein voltage range of battery module work.
Fig. 3 shows the power output P of solar module and the relation of output voltage V, and the P-V curve A of solar module is as shown in the figure.In the P-V curve A, the operating voltage range that battery module 12 is set is for arriving in the scope of SOC 80% at SOC 20%.The charged state of SOC (charged state) indication battery module, wherein SOC 100% is complete charged state, SOC 0% is the discharge final state.
Percentage with respect to maximum power point voltage (Pmax) in the scope of SOC 20% to SOC 80% shows that on the longitudinal axis of right side wherein from the curve B of display efficiency, efficient is in 92% to 100% scope.
Usually, the sexual intercourse of solar cell display line, wherein output decline and maximum power working point have negative slope (temperature coefficient) with respect to temperature when the module temperature rises.Usually, in silicon metal, temperature coefficient be approximately-0.45 to-0.5%/℃.In comprising the thin-film solar cells of amorphous silicon, temperature coefficient be approximately-0.17 to-0.2%/℃.People are developing the solar cell that wherein amorphous silicon and silicon metal pile up, perhaps synthesized semiconductor solar cell of GaAs or the like or the like, and it is dropped into actual the use, wherein temperature coefficient is suppressed to-0.2 to-0.3%/℃.
The operating voltage of solar module is temperature influence hardly.Therefore, like hope, the solar module of first embodiment selects output voltage to change the solar cell to temperature-insensitive and excellent in temperature characteristic.The temperature coefficient of solar module is less than or equal to-0.42%/℃, and as hope ground select temperature coefficient more preferably be less than or equal to-0.3%/℃ solar module.Obtain high system effectiveness thus.This depends on the type of the accumulator equipment that will connect, but the varying width that account temperature changes the accumulator equipment operating voltage cause be about 20 to 30% and the serviceability temperature width of solar module be to calculate under the about 60 ℃ situation.
Particularly, lithium ion battery has the variation of the charging voltage that very little temperature causes, and when selecting lithium ion battery to be used for the accumulator equipment of battery module, especially preferably the excellent solar cell of combination temp coefficient.
< setting of voltage range >
In first embodiment of the invention, voltage range refers to the voltage range when for the battery module charge/discharge, and wherein the upper voltage limit value of charging is charging termination voltage, and the lower voltage limit value of discharge is discharge termination voltage.Fig. 4 shows the relation between charging capacity and the charging, wherein charges like charging curve C indicatedly, and discharges like discharge curve D indicatedly.Voltage range in the time of can arbitrarily charge/discharge being set; But in this manual; When describing battery module in the situation that SOC20% uses in the scope of SOC 80%, charging termination voltage is the voltage of SOC 80%, and discharge termination voltage is the voltage of SOC 20%.As a result, the battery Free Region is the center 60% of SOC.
Therefore if motionless under the state near charging fully, even do not use, lithium ion battery also can be degenerated, and when use lithium ion battery during as accumulator equipment, preferably according to the cyclophysis of battery, utilizes the power of power core.
For example, be 1000mW/m with respect to working as the insolation amount 2And the generation power of the maximum power point voltage of the solar module when temperature is 25 ℃ (Vpmax), the lower limit of voltage range is more than or equal to the work piezoelectric voltage that under identical insolation condition and temperature conditions, obtains to be greater than or equal to 60% power above that.Preferably, it more preferably is greater than or equal to 70% more than or equal to the work piezoelectric voltage that obtains to be greater than or equal to 65% power above that, is preferably more than or equals 75%.Be most preferably 100%.The situation of specifying insolation amount and temperature has been described here, but the maximum power point voltage that target can be exported when when solar cell being predetermined temperature and predetermined insolation amount.25 ℃ situation has been described, but the insolation amount and the temperature that can the most frequently be worth according to the information setting in actual installation place or the like.
Can realize voltage through type and number, the type of storage battery tandem and the charged state of number and use therein of suitable selection solar cell tandem.
Use the situation of lithium ion battery with describing as accumulator equipment through the SOC that selects to use.Use the every unit of lithium ion battery of cobalt oxide to have the capacity to the 4.2V voltage range at 3.0V at the plus end place.Therefore, when using SOC 0% to 100%, the lower limit of voltage range is 3.0V * tandem number.When with lower limit when high-voltage side moves, when using SOC 50% to 100%, the higher limit of voltage range is 3.7V * tandem number.
As stated, in first embodiment of the invention, confirm the working point of battery module by the voltage of the battery module that will connect.Thus, the battery module that connect perhaps passes through to the output discharge of the power governor that is connected, thus its change in voltage by the power charging that solar module generated.But,,, can't obtain sufficient power so, then compare with the maximum power electrical voltage point if the voltage range that departs from aforesaid voltage range is set because cell voltage can't acute variation.Thus, solar cell continues on inefficient operating voltage, to generate power, and can't improve system effectiveness.
In addition, above-mentioned voltage range preferably is set in the set determined voltage range of SOC scope, to comprise 60 ℃ and 1000mW/m 2On maximum power point voltage.
If there is the insolation amount that makes solar cell fully generate power, then the temperature of solar module often is high, and through above-mentioned setting, on various insolation amounts and solar module temperature, all has efficient photovoltaic power generation.
Voltage range can be fixed, and perhaps settings can change according to degenerate state of insolation amount, weather conditions, solar cell device or the like successively.
When according to insolation condition and weather conditions variation, can be the suitable period through insolation data and air themperature data sementation according to the past, voltage range is set.For example, in air themperature low winter, voltage range is set for high, because the temperature step-down of solar module.In air themperature high summer, it is low that voltage range is set.In addition, at spring and fall, the intermediate voltage scope in winter and summer is set.Thus, when considering that the insolation condition is provided with, in the stable zone of insolation, can lower limit be set to more than or equal to 80%.
In order further to improve the efficient of the power-supply system of first embodiment under the stable condition of insolation,, select the wherein less accumulator equipment of change in voltage of charge/discharge like hope ground.The wherein less accumulator equipment of the change in voltage of charge/discharge is below described in the battery module.
Along with the degeneration of storage battery, internal resistance increases, and can be provided with in advance thus, thereby in above-mentioned scope, improves charging termination voltage with step-by-step system, and reduces discharge termination voltage.For this reason, can arrange switch, thereby can utilize means of communication or the like, be updated in the settings that is provided with in the Control Software.
< switch >
Said switch can be connected the switch that ends, perhaps electron field effect semiconductor switch, for example MOSFET and 1GBT for mechanical system control.Control switch is to work in the predetermined work voltage range.
<battery module >
The battery module that in first embodiment of the invention, uses is connected with one or more accumulator equipment, and (if necessary) protective circuit.Secondary cell (for example lithium ion battery, nickel hydroxide battery and lead accumulator), double-layer capacitor that utilizes chemical reaction or the like can be used for accumulator equipment.As stated, be preferably wherein and in narrow voltage range, can obtain jumbo battery as much as possible, and be preferably the secondary cell that utilizes chemical reaction.Therein, more preferably in the charge/discharge reaction, do not relate to the battery system of side reaction basically, because the power efficiency of charge/discharge is higher.Its exemplary is a lithium ion battery.
In addition; The lead accumulator that is conventionally used as accumulator equipment may cause degradation in capacity when continued absence charges, perhaps in nickel hydroxide battery or the like; When recharge in preset range/discharge; Can see memory effect or the like, wherein fully not obtain capacity, lack the cycle degradation of charging, memory effect or the like but lithium ion battery does not have; And the temperature dependency of not charging termination voltage, it is suitable for the battery as the battery module that constitutes first embodiment of the invention thus.
With respect to lithium ion battery, people have proposed various materials and have been used for plus end material and negative terminal material, and all these can use.Therein, the especially preferred LiFePO that is to use 4The lithium ion battery that is used for plus end is because the charge/discharge curve is smooth.
Protective circuit comprise each unit of anti-overcharge circuit, the anti-accumulator equipment of putting discharge circuit, anti-overcurrent circuit, being connected in series voltage monitoring circuit, be used for regulating the balancing circuitry or the like of the voltage of each unit.
< solar cell string >
In first embodiment of the invention, the solar cell string refers to the string that wherein solar module and battery module are connected in parallel.More specifically, the solar cell string comprises switch 13, current sensor 14 and anti-return diode 15, like Fig. 1 and shown in Figure 2.In this case, solar module is installed in the strong place of sunlight, for example roof or roof.Battery module can be installed on the part of solar cell shelf, perhaps under the cool place, on the part of the tandem box of collection solar module circuit, perhaps avoids the place of wind and rain, and is for example indoor.Through electrical connecting wires, it is right to form respectively to connect battery module and a plurality of solar cell string (thereby its voltage range that is connected battery module becomes above-mentioned voltage range).
< charge control method >
In first embodiment of the invention, the smoothly output of DC/AC conversion equipment, and, can control charging to battery module through controlling the output of DC/AC conversion equipment.That is, obtain charge power through the output that deducts the DC/AC conversion equipment the photoelectric power that generates from solar module.According to this type of output control, the generation power output of level and smooth solar module, and the control of can charging.
Can be constant output from the output of DC/AC conversion equipment control, absorbing variable power, constant thereby the output that perhaps can control the DC/AC conversion equipment becomes charging current from solar module.
Pay attention to the level and smooth control method of exporting with utilizing Fig. 5 to describe.This figure shows the output F of generation power E, the DC/AC conversion equipment of specific one day 16:00 and the solar module between the 17:00, to the charge power G and SOC (charged state) H of battery module.Along with nearly evening around, the insolation amount descends, and generates power E and descend gradually, but control is constant from the output F of DC/AC conversion equipment.Thus, no matter the insolation amount descends, all obtain constant output.Simultaneously, may descend gradually to the charge power G of battery module, can accomplish two controls simultaneously thus.This type of control is very effective, and this is when in for the ending phase of battery module charging, using this type of control, constant current/constant-potential charge similar effects of often using in the charging control of acquisition and battery module.
Usually; When charging fully near battery, carry out the control of constriction charge power through charge control apparatus, but in the power-supply system of first embodiment of the invention; When charging fully; Do not need the control of constriction charge power, and only utilize the output control of DC/AC conversion equipment, the control of can charging simultaneously.
With the situation of utilizing Fig. 6 description control charging current.This figure show specific one day 10:00 and the solar module between the 11:00 generation power I, DC/AC conversion equipment output J and to the charge power K of battery module.The scale on Fig. 6 left side shows the generation power I of solar module.The scale on Fig. 6 the right shows charge power K.The generation power I of solar module is along with the variation acute variation of insolation amount.But, do not carry out the needed control of following, and export according to the big FLOW CONTROL of insolation amount.Thus, the level and smooth output J of DC/AC conversion equipment.In addition, charge power K changes, but simultaneously controlled, thereby always is lower than or equals firm power (0.5Kw+4%).In battery control, make that the control that is not greater than or equal to specified charge power is important for extending battery life.This type of control is generally carried out by special charging equipment, but in first embodiment, from the output of DC/AC conversion equipment, carries out the control of charge power through smoothly simultaneously.
< about the balance of capacity >
If it is W1 (Wh) that solar module is output as the memory capacity of P1 (W) and battery module, then its balance is preferably P1 * 0.3hrs＜W1.In other words, battery module preferably has the charging capacity of the power output of storing solar module generation in 0.3 hour at least.Utilize the battery capacity of this kind degree, the balanced output of the time interval that can be careful.In the charging control of normal storage battery, the restriction electric current makes big electric current can not flow to storage battery.
But solar module has by the number of solar battery cell, internal resistance, connection resistances or the like maximum current that confirm, that can flow to equipment, and solar module is for originally having the power supply of current limit function.The current limit circuit that does not need the general necessary charging interval, this is because of the balance between the memory capacity of the output of having adjusted solar module and battery module.Therefore, capacitance balance is extremely important.In addition, also from this type of viewpoint, the minimum value of charging current is preferably above-mentioned lower limit, but be more preferably P1 * 0.5hrs, and most preferred be P1 * 1hr.
Normal accumulator equipment is designed such that: if flowing into, electric current is about 3C (in three hours, being full of the electric current of battery capacity), and then can safety.From the viewpoint of safety, derived and concerned P1 * 0.3hrs＜W1.Accumulator equipment is allowed the charging current (in a hour, being full of the electric current of battery capacity) of about 1C, as charging current that can sharp influencing characterisitic.Thus, be preferably minimum value P1 * 1hr, this is the characteristic that can not reduce accumulator equipment because can use accumulator equipment.
Realizing that when of the present invention, even bigger, the maximum of charging current can not throw into question yet, but is preferably P1 * 10hrs, and from the viewpoint of work ratio of equipment size, cost, equipment or the like, more preferably P1 * 5hrs.If memory capacity is enough, then can obtain with the level and smooth output of the careful time interval and to power carry out time shift long power displacement (equilibrium) both, be preferred thus.
< to the description of the output control of output predetermined volumes >
Control general power-supply system to export all power that it can be exported, follow the maximum power point of the solar cell that on predetermined insolation amount, keeps simultaneously.
In independent type, control output capacity according to the load capacity of the equipment that is connected to the DC/AC conversion equipment.Output in this case is defined as the load capacity of equipment, and the power that can not effectively utilize photoelectricity to generate thus.
In first embodiment of the invention, do not carry out this type of control of prior art, and during the special time width, carry out control shown in Figure 7, to keep constant output.Replacedly, carrying out control shown in Figure 8 flows level and smooth and output with what change along big insolation.When claiming that solar module and battery module are connected in series, connecting the power that makes photoelectricity generate can be with respect to directly charging and discharge of storage battery.In Fig. 7 and Fig. 8, (a) charged state of demonstration battery module (b) shows the insolation amount, (c) shows the output of solar cell string.
Like Fig. 7 and shown in Figure 8; Can be through adjustment output width or output variable; Be controlled to the amount of charge/discharge of battery module; Thereby battery module moves along the direction of charging fully gradually, perhaps move along discharge termination direction gradually, perhaps periodically for charging → discharge fully terminate neighbouring → near charging → discharge terminates fully.
The curve B of Fig. 3 shows that the module temperature when solar module is that 60 ℃ and insolation intensity are 90mW/m 2The time operation.In this case, with respect to the maximum power point in the set voltage range, the voltage that obtains 92% power above that obtains on it to charge in voltage range of voltage of 100% power and discharge.Therefore, through at first initial period charge and near fully the charging regional enterprising line output level and smooth, further improved system effectiveness.
With respect to the output variable of constant output and time width, can consider according to the definite method of battery charging state, select method of prepattern or the like with reference to the insolation amount of weather information and measurement respectively.
< to the description of conversion handover operation >
The solar cell string of first embodiment of the invention comprises: time monitoring unit, voltage detection unit or current detecting unit, and when predetermined condition is satisfied in the output of time monitoring unit, voltage detection unit or current detecting unit, diverter switch.The time monitoring unit is so-called clock, and is arranged in the DC/AC conversion equipment.Said predetermined condition is i) when the detection electrorheological of the detection voltage of voltage detection unit or current detecting unit must be greater than or equal to predetermined value; Begin output (switch and connect); When perhaps being less than or equal to predetermined value, stop output (switch and end) when becoming; Ii), begin output (switching is connected) or stop output (switch and end) according to the scheduled time of time monitoring unit; Iii) when the detection electrorheological of the detection voltage of voltage detection unit or current detecting unit must be greater than or equal to predetermined value, and according to scheduled time of time monitoring unit, begin output (switch and connect) or stop output (switch by); And iv) when the detection electrorheological of the detection voltage of voltage detection unit or current detecting unit must be less than or equal to predetermined value, and according to scheduled time of time monitoring unit, begin output (switch and connect) or stop output (switch by).The time of magnitude of voltage, current value and time shift of level and smooth photovoltaic power generation output of being used for can be set arbitrarily then.
Promptly; In first embodiment of the invention; Be connected to the voltage of the battery module 12 of solar cell string through detection; Connect, open a way or diverter switch 13, and can battery separated a period of time after the charging fully, can be in maximum with the generation power that only uses solar cell in the rate point-tracking method; After this battery module can be connected once more through after the scheduled time, and the joint Power of solar module and battery module can be used for the constant time.Can detect electric current, with change over switch from the solar cell string.
For example; When as shown in Figure 2 a plurality of solar cell connection in series-parallel are connected to a DC/AC conversion equipment and descend or the output that gets into shady and cool and some solar cell string when descending in the insolation amount of some solar cell string of firm power control period, avoided when under extreme case, become the state that can not generate power output to ask only to focus on the specific solar cell string.
The solar cell string of first embodiment of the invention comprises battery module; And also required quantity of power can be provided even without insolation thus; If but output is switched to only solar module when flow constant electric current or bigger electric current, if require the power of the ability that is greater than or equal to, then voltage descends; This is because be limited from the power of solar module, encourages the output from the storage battery in another solar cell string thus.
If through the proper communication means send from the outside signal with switch transition to open circuit solar cell and battery system; Then switch can be changed; Thereby, only obtain the output of solar cell from the DC/AC conversion equipment, and operate with MPPT maximum power point tracking as required through this signal.
[example 1-1]
< system configuration >
Fig. 1 is the view of an example of configuration of the power-supply system of example 1-1.Solar module 11 is by following configuration: what have maximum power point voltage Vpm=51V and Isc=2A, 85W takes advantage of three 12 thin film crystallization solar battery panels arranging by four.Battery module 12 has following configuration, and wherein the series connection of the lithium ion battery of 5.7Ah is 48, and disposes the circuit part that comprises protective circuit and power counter.The solar cell string 1 of this type of configuration is connected in parallel through anti-return element 15, arranges anti-return diode 15 to make the power of battery module 12 can not be back to solar module 11.Protective circuit is by following configuration: the commercial voltage monitoring IC that gets, FET, Controlled CPU or the like, and have the function of when detecting electric voltage exception or the like open circuit and protection battery.The power counter is the circuit that power monitoring IC or the like is installed, and is used for monitoring the charge/discharge power of accumulator equipment, and can the charged state of battery be outputed to the outside.Anti-return element 15 is made up of diode.
The on/off solar module is connected between battery module 12 and the node 16 with the switch that is connected 13 of battery module.The current sensor 14 of the electric current of node 16 through being used for measuring the solar cell string is connected to DC/AC conversion equipment 2.Field-effect transistor (MOS TFT) is used for switch 13.Current sensor 14 for example connects shunt resistance, and measures the voltage at its two ends, uses Hall element or the like., perhaps break off to be connected to solar module by control circuit (not shown) control switch 13 from solar module.
As above the solar cell string 1 of configuration is connected to DC/AC conversion equipment 2, and passes through the output of DC/AC conversion equipment 2, is connected to electric power system 3.
The state of storage battery can detect through the holding wire 18 from battery module 12.Holding wire 18 is used for voltage and SOC (charged state) signal of providing to DC/AC conversion equipment 2 by storage battery or the like, and is used for confirming the output from DC/AC conversion equipment 2.
< operating voltage range of storage battery >
Voltage range when whole power of the lithium ion battery of charge/discharge configuration battery module 12 is that 202V is to 144V; And in the scope of SOC 20% to SOC 80%, (wherein in example 1-1,20% excised up and down), and used 60% of entire capacity.In this case, the lower voltage limit when discharge is 174V, and the upper voltage limit when charging is 199V.
At 1000mW/m 2And 25 ℃ of maximum power point voltages (Vpm) of going up solar modules are 204V, and to generate power in this case be 85W.Under the same conditions, on the PV curve, be respectively 78.2W (92%) and 83.7W (92%) in the lower voltage limit 174V and the power output on the upper voltage limit 199V of battery.
< control method of output >
In example 1-1, under following condition, export control.SOC in the following description (C) is shown as percentage, and the capacity that wherein reality is used as above (60% capacity of accumulator equipment) is defined as 100, to promote the understanding to digital value.In other words SOC 20%=SOC (C) 0%, and SOC 80%=SOC (C) 100%.
(1), then stops output if be lower than or equal SOC (C) 70%.
(2) advance to when equaling or equaling SOC (C) 70% solar cell start of string 100W output when charging.
(3) advance to when equaling or equaling SOC (C) 70% when charging, the increase for per 10% increases 100W with the output of solar cell string.
(4) advance to when equaling or equaling SOC (C) 70% when charging, the minimizing for per 10% reduces 100W with the output of solar cell string.
(5) advance to when equaling or equaling SOC (C) 70% and in 15 minutes, take place surpassing 10% variation when charging, the output of solar cell string is increased or reduce 200W.
(6) at the 16:18 place (accomplished by 600W at the 10:00 place 70% charged state) carries out 600W output (approximately 1C discharge).
< conclusion >
The darg data that in Fig. 7, shown the system of example 1-1.Can find out that insolation changes violent, and the output of solar cell alters a great deal, but from the output of DC/AC conversion equipment by level and smooth.In other words, insolation amount shown in Figure 7 increases to 8:00 from about 6:45, but the charged state of storage battery is less than SOC (C) 70%.Thus, according to above-mentioned condition (1), the solar cell string of example 1 is output as 0W, shown in " a " among Fig. 7.But after 8:00, the SOC of storage battery (C) surpasses 70%.Thus, according to above-mentioned condition (2), the output of solar cell string output 100W is shown in " b " among Fig. 7.The insolation amount further increases, and the SOC of battery (C) increase by 10% becomes SOC (C) 80%.Because this 10% increase took place in 15 minutes, so according to above-mentioned condition (5), from the output increase 200W of solar cell string, shown in " c " among Fig. 7.This continued charging, and SOC (C) becomes 90%.This is in 10% increase took place in 15 minutes, so according to above-mentioned condition (5), from the output increase 200W of solar cell string, shown in " d " among Fig. 7.
Then, the insolation amount reduces, and the SOC of storage battery (C) reduces 10%, and according to above-mentioned condition (4), will reduce 100W from the output of solar cell string, shown in " e " among Fig. 7.Corresponding to the variation of insolation amount and SOC (C), the output of solar cell string increases and reduces, shown in " f ", " g ", " h ", " i ", " j " and " k " among Fig. 7.
According to above-mentioned condition (6), from starting to actual generation power that begins to output to (time zone of " a ") and the generation power during insolation by the time zone of time shift after 16:18.
Therefore,, can smoothly export through control according to above-mentioned condition, and can be with generating in the time zone of power time shift after 16:18.
In this case, with respect to when the generation power that is consumed when controlling fully with the maximum amount of power that obtained, the actual quantity of power that obtains was 97% (having got rid of the charge/discharge loss of storage battery).This equates the efficient 98.5% (0.985 * 0.985=0.97 back and forth) that stepping raising and stepping reduce in the circuit when smoothly exporting through circuit, so efficient is very high.
Therefore, can high efficiency obtain time shift according to the first example 1-1 to the level and smooth and power of output.
(example 1-2)
In example 1-2,, wherein only changed control method according to operating with the similar system of example 1-1.
Operating condition is following.
(1) charging is until charging fully.
(2) when reaching when charging fully accumulator equipment is exported discretely, and control method becomes MPPT maximum power point tracking.
(3) in 14:00 (a hour), carry out 300W output at 12:00.
Operating result is as shown in Figure 8.Can find out that from the result generation power in morning is displaced to 12:00 to 14:00.Can easily switch according to circumstances and easily export the only generation power of solar cell, and carry out smoothly with output with the output addition of the output of solar cell and battery module and to it to electric power system through MPPT maximum power point tracking.
In addition, when controlling with maximum amount of power fully, with respect to the generation power that is consumed, the actual quantity of power that obtains was 96.3% (having got rid of the charge/discharge loss of storage battery) in example (only charge/discharge period).This equates the efficient 98% (0.98 * 0.98=0.96 back and forth) that stepping raising and stepping reduce in the circuit when smoothly exporting through circuit, efficient that thus can be very high realizes time shift.
(second embodiment)
Power-supply system according to second embodiment of the invention comprises: the solar cell string wherein is connected in parallel storage battery and solar cell; The DC/AC power converter is used for solar cell to be series-connected to electric power system or load; The battery status detecting unit is used for detecting the state of storage battery; Export detecting unit, be used for detecting the power output of DC/AC power converter; And output control unit, be used for according to the state of the storage battery of battery status detection and the power output control DC/AC power converter of output detection.Utilize not expensive system, the level and smooth or time shift of exporting is become possibility, control because judge the state of storage battery and the power output of DC/AC power converter.Because excessive electric current can not flow to storage battery, thus the life-span of storage battery postponed, and can reach the stable of system.
In below the battery status detection one or more: the voltage of storage battery, charged state (SOC) and the charged state of unit interval (SOC) pace of change.In addition; The present invention comprises data storage cell or communication unit; Be used for receiving external data; Wherein data storage cell or communication unit obtain one or more information in following: the prediction insolation amount of past insolation data, average air temperature data, weather forecast or predict the temperature data of air themperature or the like, solar cell, the predicted temperature characteristic of solar cell and the degradation information of storage battery, and output control unit is according to relevant information control DC/AC power converter.
In a second embodiment, storage battery comprises a plurality of storage batterys; And the battery status detecting unit comprises: the voltage comparing unit is used for serial number according to the high cell voltage of battery status detection; Batteries generates parts, is used for generating batteries according to the order that the height of voltage comparing unit is numbered; And the first start-up control parts, be used for controlling the DC/AC power converter, make the overall power output that the power output of DC/AC power converter becomes and allows less than from batteries when power-supply system starts.
Thus; If power-supply system is large-scale; Even then first specification is identical; When the installation site that depends on solar cell or ambient temperature produced the solar cell of solar cell and little output of big output, perhaps when the installment state that depends on storage battery or ambient temperature produce the storage battery of storage battery and little output of big output, power supply of the present invention used in order according to the high output voltage of storage battery; And the storage battery of satisfactory charged state can at first be contributed for output thus, and can balanced all solar cells and storage battery.
In a second embodiment, storage battery comprises a plurality of storage batterys; And the battery status detecting unit comprises: the SOC comparing unit is used for serial number according to the big charged state (SOC) of the storage battery of battery status detection; The SOC batteries generates parts, is used for generating the SOC batteries according to the order of the big charged state (SOC) of SOC comparing unit numbering; And the second start-up control parts, be used for controlling the DC/AC power converter, make the overall power output that the power output of DC/AC power converter becomes and allows less than from the SOC batteries when power-supply system starts.
Thus, if power-supply system is large-scale, even then first specification is identical, the installation site or the ambient temperature that depend on storage battery also can produce the storage battery of big output and the storage battery of little output.But the present invention can balanced all storage batterys, and this is because using in order according to big charged state (SOC) of storage battery.
The solar cell string comprises many (n) individual solar cell string, and wherein searching for k the sun that meets the following conditions can battery strings
(E1-Ei)/r＜ΔImax
Wherein r is the internal resistance of storage battery; Δ Imax is the distance of the output current and the absolute maximum rated Imax of storage battery, and η is the efficient of DC/AC power converter, SB1, SB2 ... SBn is by each storage battery of high-tension order when power-supply system starts; E1, E2 ... En is the electromotive force of each storage battery, I1, I2 ... In is an electric current; And the control power output makes the output P of DC/AC power converter become following relational expression
P＜(E1-r×Imax)×(Imax+I2max+...+Ikmax)×η
(Iimax＝Imax×(Ei-(E1-r×Imax))/(EI-r×Imax)，i＝2，3...，k)。Obtain not flow out the output of overcurrent thus from storage battery.In addition, begin, periodically monitor the voltage of each storage battery, and when k increases,, increase the output acceptable value of DC/AC conversion equipment corresponding to the increase of k from starting power-supply system.Because after system start-up, be updated periodically the batteries of high-voltage value, and may increase to the storage battery that discharge is contributed, so can in the time of minimum, bring system into stable state reliably.
Above-mentioned DC power supply string comprises the charge switch that is used for each storage battery, is used for: when shining upon, when the charge volume of storage battery is hour, connect this charge switch and utilize solar cell to be charge in batteries; And,, thus, can easily carry out charging to the storage battery of little charge volume by this charge switch when storage battery when to have filled electricity and electric voltage be high.
Arrange open circuit/closed switch, be used for each storage battery and system are separated, wherein suppress discharging naturally of storage battery, and can reduce the variation of battery state of charge, this is to be disconnected because of storage battery when system stops at night or the like.
Below describe each part of second embodiment of the invention in detail.
Similar with first embodiment, it is the situation of solar cell that second embodiment has also described the DC power supply, but also is applicable to such as electric organs such as wind turbine generator and fuel cells.In a second embodiment; < solar module >, < voltage range setting >, <battery module >, < solar cell string >, < charge control method >, < about capacitance balance>and < to the description of the output control of output predetermined volumes>are identical with first embodiment, omit description thus here.
In a second embodiment, the capacitance balance output P1 (W) that is preferably solar battery array is preferably P1 * 0.3hrs＜W1＜P1 * 5hrs with the balance of the battery capacity W1 (Wh) of battery module.More preferably P1 * 0.5hrs＜W1 most preferably is P1 * 1hrs＜W1.
Second embodiment has described the situation that is not arranged in the switch of arranging among first embodiment, but can arrange switch similarly with first embodiment, and can carry out similar control.
< voltage comparing unit, batteries generate parts, start-up control parts, SOC comparing unit, SOC batteries generation parts >
Each of these parts all is arranged in the control unit of second embodiment, utilizes RAM perhaps to number for storage battery according to the order of high SOC according to high-tension order as the temporary information memory cell, and according to the order generation group that begins from senior group.Like hope ground, confirm senior group through the condition 1 of following description, but replacedly, specifically do not limit numbering, and numbering can be set in advance, for example whole storage battery half the or 1/3.When starting, the start-up control parts are controlled to utilize senior group battery pack to supply power to power converter.
(example 2-1)
< system configuration >
Fig. 9 is the block diagram according to an example of the configuration of the power-supply system of example 2-1.Solar module 21 is by taking advantage of 3 12 thin film crystallization solar battery panels (Vpm=51V and Isc=2A, 85W) configurations of arranging by four, and output 1kW.Battery module 22 has following configuration, and wherein the series connection of the lithium ion battery of 9.5Ah is 48, and disposes the circuit part that comprises protective circuit and power counter.
Solar module 21 is parallel-connected to DC/AC conversion equipment 25 with battery module 22 through anti-return element 23, arranges anti-return diode 15 to make the power of storage battery can not be back to solar module 11.The current sensor 24 that is used for measuring the electric current of solar cell string is connected between battery module 22 and the DC/AC conversion equipment 25.Through the holding wire 26 from battery module 22, DC/AC conversion equipment 25 can detect the state of storage battery.
Battery module 22 comprises battery status detecting unit 22-1, and in below detecting at least one: the voltage of storage battery, charged state (SOC) or the charged state of unit interval (SOC) pace of change.
Solar cell string 40 comprises data storage cell 22-2 or communication unit 22-3; Be used for receiving external data; Wherein data storage cell 22-2 or communication unit 22-3 obtain one or more information in following: the prediction insolation amount of past insolation data, average air temperature data, weather forecast or predict the temperature data of air themperature or the like, solar cell, the predicted temperature characteristic of solar cell and the degradation information of storage battery, and output control unit is according to relevant information control DC/AC power converter.
Though do not show that DC/AC conversion equipment 25 comprises the output detecting unit in inside, be used for detecting the power output amount of DC/AC conversion equipment 25.The battery condition that output control unit detects according to battery status detecting unit 22-1, or export the power output amount of the DC/AC conversion equipment 25 of detection, control DC/AC conversion equipment 25.
Then, as above the solar cell string 30 of configuration is connected to DC/AC conversion equipment 25, and is connected to electric power system or load through the output of DC/AC conversion equipment 25.
< operating voltage range of storage battery >
Voltage range when whole power of charge/discharge lithium ion battery be 202V to 144V, but be SOC (charged state) 20% to SOC 80%, wherein in example 2-1,20% excised up and down, and the use entire capacity 60%.In this case, the lower voltage limit when discharge is 174V, and the upper voltage limit when charging is 199V.
The power output P and the output voltage V of the solar module of example 2-1 are as shown in Figure 3, and the operating voltage range of battery module is SOC 20% to SOC 80%.
The charging capacity of example 2-1 and the relation of charging make shown in the charge in batteries charging curve C shown in figure 10, and discharge is shown in discharge curve D.In this type of charge/discharge curve; Upper voltage limit value when charging termination voltage is set to charge; And the lower voltage limit value when discharge termination voltage is set to discharge, and the voltage range from charging termination voltage to discharge termination voltage can be set arbitrarily.In example 2-1, the core between SOC 20% and the SOC 80% 60% is a voltage range.
Therefore, at 1000mW/m 2And 25 ℃ of maximum power point voltages (Vpm) of going up solar modules are 204V, and to generate power in this case be 85W.Under the same conditions, the power output on lower voltage limit 174V and upper voltage limit 199V is respectively 78.2W (92%) and 83.7W (98.5%).
< control method of output >
In example 2-1, under following condition, export control.SOC is writing a Chinese character in simplified form of charged state, and is represented as the percentage of the capacity (60% capacity of accumulator equipment) with respect to the actual use that as above in example 2-1, defines.
(1) when being lower than SOC 10%, stops output.
(2) be greater than or equal to SOC 10% and less than 20% o'clock, DC/AC conversion equipment 25 carries out 200W output.
(3) be greater than or equal to SOC 20% and less than 40% o'clock, DC/AC conversion equipment 25 carries out 300W output.
(4) be greater than or equal to SOC 40% and less than 95% o'clock, DC/AC conversion equipment 25 carries out 700W output.
(5) when being greater than or equal to SOC 95%, DC/AC conversion equipment 25 carries out 1000W output.
(6) at 17:00, DC/AC conversion equipment 25 carries out 500W output.
But, in case after condition changed, condition 20 minutes was constant.
< conclusion >
The darg data that in Figure 11, shown the system of example 2-1.Can find out; The output of solar cell alters a great deal and mainly changes with insolation variation (showing that it has violent change curve significantly); But the output quilt from the DC/AC conversion equipment is level and smooth; And the generation power peak during a day can be displaced to after the 17:00, shown in linearity curve.
Figure 12 show percent; On this ratio, obtain to generate power; It is with respect to maximum power point power, obtains through the generation quantity of power that is connected with reality on the voltage of battery in the generation quantity of power on the maximum power point of relatively more each generating from insolation intensity and module temperature computation.In the figure, the efficient on one day overall power is 99%.
Can find out from example 2-1, can high efficiency realize the time shift of the level and smooth and power of output.
(example 2-2)
The system configuration of example 2-2 is identical with example 2-1's, is 15Ah but the solar-electricity tankage is 3kW and battery capacity, control method wherein only is set, and controls as follows.
< control method of output >
(1) from the charge volume of the SOC of battery and confirm the integrated value of output, calculate the generation quantity of power of 30 minutes in the past photovoltaic power generation.
(2) the generation quantity of power from being calculated, the average generation quantity of power of calculating per minute is as the output of next minute.
< conclusion >
Shown in figure 13, on postponing in 30 minutes, can obtain more level and smooth output.Figure 14 show percent; On this ratio, obtain to generate power; It is with respect to maximum power point power, and the generation quantity of power that is connected with reality from the generation quantity of power on the maximum power point of insolation intensity and module temperature computation through relatively more each generating on the voltage of battery obtains.Efficient on one day overall power is 97.8%.
Can measure the insolation amount; And can calculate the generation quantity of power of photovoltaic power generation through this insolation amount; At that time in system of the present invention; Can calculate generation quantity of power in the past through the SOC of battery and the output variable of system control itself, and can under the situation of not measuring insolation, obtain level and smooth output.
The SOC of measurement after the process set time is corresponding to the overall power consumption of the amount of charge/discharge that arrives battery of measuring the set time.Controlled output is the output of being confirmed by system itself basically, and its amount can be learnt under situation about need not measure.Therefore, measurement that can be relatively easy accurately obtains the generation quantity of power of level and smooth necessary past photovoltaic power generation, and the high precision measuring instrument that does not need supervision insolation necessary in the prior art to change.
In example 2-1 and example 2-2; Output through charged state (SOC) and DC/AC conversion equipment 25 comes power controlling; But can utilize storage battery voltage, past insolation data, average air temperature data, weather forecast prediction insolation amount or predict that the temperature data of air themperature or the like, solar cell, the predicted temperature characteristic of solar cell and the degradation information of storage battery come power controlling
(example 2-3)
Figure 15 A is the block diagram of example 2-3.
Solar cell 21, storage battery 22, converter 25 and identical among 30 configuration and Fig. 9 shown in the example 2-1 of going here and there, but difference is to connect a plurality of strings, and anti-return diode 28 is connected to each string 30.This example 2-3 has following configuration, and wherein voltmeter 22-4 is attached to the storage battery of each string, and the output voltage values of each storage battery is monitored through holding wire 26 by the control unit 29 of converter 25.
In Figure 15 A, the number of string is two, but can be many for more, and inferior shows a plurality of strings.In the following description, n is the number of string, and r is the internal resistance of storage battery, and E0 is the voltage that is provided with of storage battery, and I0 is the electric current that is provided with of storage battery, and Δ imax leaves to the current distance of maximum rated current Imax for the electric current that is provided with from storage battery.When n * (during E0-r * I0) * I0 * η=Pmax, promptly when the storage battery of all strings is being provided with voltage/be provided with and is exporting on the electric current, the maximum output of output, wherein η is the efficient of power converter, and Pmax be maximum output.
(example 2-3)
Figure 15 A is the block diagram of example 2-3.
Solar cell 21, storage battery 22, converter 25 and identical among 30 configuration and Fig. 9 shown in the example 2-1 of going here and there, but difference is to connect a plurality of strings, and anti-return diode 28 is connected to each string 30.This example 2-3 has following configuration, and wherein voltmeter 22-4 is attached to the storage battery of each string, and the output voltage values of each storage battery is monitored through holding wire 26 by the control unit 29 of converter 25.
In Figure 15 A, the number of string is two, but can be many for more, and inferior shows a plurality of strings.In the following description, n is the number of string, and r is the internal resistance of storage battery, and E0 is the voltage that is provided with of storage battery, and I0 is the electric current that is provided with of storage battery, and Δ imax leaves to the current distance of maximum rated current Imax for the electric current that is provided with from storage battery.When n * (during E0-r * I0) * I0 * η=Pmax, promptly when the storage battery of all strings is being provided with voltage/be provided with and is exporting on the electric current, the maximum output of output, wherein η is the efficient of power converter, and Pmax be maximum output.
When system stability and all storage batterys are in similar charged state following time; This condition satisfies; When but the voltage of storage battery changes according to the charged state of storage battery when in system start-up; Restriction output as follows, this is because when attempting to export Pmax, can extract too many electric current from high-tension storage battery.
When system start-up, at first measure the voltage of the storage battery of each string, and according to the order that begins from i=2, whether satisfy condition for the voltage Ei search of each storage battery
(E1-Ei)/r＜Δ Imax... (condition 1),
Wherein, SB1, SB2 ... SBn is the storage battery by high-tension order, E1, E2 ... En is the electromotive force of each storage battery, I1, I2 ... In is an electric current.
For example, Figure 16 is the view of the relation of voltage E and the electric current I of describing storage battery with frame format.As i=2 and (E1-Ei)/during r＜Δ Imax; Even when SB1 and SB2 attempt to flow out electric current simultaneously, can increase from the electric current of SB1, and the voltage drop meeting that internal resistance r causes becomes big; This is because the voltage E1 of SB1 is too high with respect to other storage batterys; Even and the voltage decline of merging point S, dropping at voltage before the voltage E2 of SB2, I1 surpasses Imax and becomes overcurrent.In other words, can only obtain electric current from SB1, output is limited to the P of a string＜(E1-r * Imax) * Imax * η thus.
If (E1-E2)/and r＜Δ Imax, then electric current I 2 also can flow out from SB2.When I1 was Imax, I2 became
I2max＝Imax×(E2-(E1-r×Imax))/(E1-r×Imax)
And can output to thus
P＜(E1-r×Imax)×(Imax+I2max)×η。
Similarly, if satisfy condition 1 to i=k, then can output to
P＜(E1-r * Imax) * (Imax+I2max+...+Ikmax) * η ... (condition 2),
(wherein, Ikmax=Imax * (Ek-(E1-r * Imax))/(E1-r * Imax)).
Thus, through the output of control converter, can start-up system and do not flow out overcurrent from each storage battery.
With the same in the above-mentioned explanation, measure the voltage of storage battery, and through controlling to condition 2 balanced storage batterys by 1 the storage battery of satisfying condition.Through in the second control circuit shown in the first control circuit shown in Figure 15 B and Figure 15 C, arranging voltage comparing unit 29-1, batteries generation parts 29-2 and start-up control parts 29-3 and operating this type of each parts, can realize this type of control.
In above-mentioned example 2-3, measure the voltage of storage battery; But can measure the SOC of storage battery; And can be the storage battery numbering according to the order of big SOC; Can generate the SOC batteries that belongs to big SOC group, and the SOC batteries can make the population value of the output of power converter less than the output of SOC batteries permission.Through arranging SOC comparing unit, SOC storage battery to generate parts and start-up control parts, can realize this type of control.
Described the voltage or the SOC that measure storage battery here, and be the storage battery numbering in proper order, but voltage or SOC through the measurement storage battery, and 1 organized into groups storage battery, can obtain similar result according to whether satisfying condition according to height.
Therefore, in case when start-up system, the voltage of discharge storage battery progressively reduces.In electro-optical system of the present invention, in control circuit 29, arrange timer, periodically monitor the voltage of each storage battery from starting beginning, and as the above-mentioned condition of hope ground inspection.Passed through the set time if timer measures, then when k increases, increased the output of power converter with it, thereby finally made all storage battery outputs.
(example 2-4)
Figure 17 A is the block diagram of example 2-4.Be to have added anti-return diode 32 and be used for the charge switch 33 of bypass anti-return diode 32 with the difference of example 2-1 shown in Figure 9 for each storage battery.Other configurations are identical.Example 2-4 repeatedly arranges each parts with the subscript demonstration.
According to this type of configuration, when in the normal sun insolation electromotive force of solar cell fully and storage battery be charged as dummy status the time, connect charge switch 33 be that storage battery 22 charges directly from solar cell 21.If, then carry out the maximum power point control, and only operate solar cell by charge switch 33.
In addition, through (for example at night) and the storage battery that separates all strings can reduce the nature discharge capacity, and when system start-up, can alleviate the variable condition of charge volume by charge switch 33 when system stops.
Block diagram arrangement shown in Figure 17 A has anti-return diode 32 and charge switch 33, but can omit anti-return diode 32, and only disposes open circuit/closed switch.When deploy switch only,, also carry out similar operation, and can obtain similar effects with example 2-2 even arranged such as switches such as FET and 1GBT.
As another control example of the present invention, follow control or different with maximum power point corresponding to the power output control of load capacity, keep constant output thereby can control during the special time width.In Figure 18, (a) charged state of demonstration battery module; (b) show the insolation amount; (c) output of demonstration solar cell string.
Shown in figure 18; Through adjustment output width and output variable; Can be controlled to the amount of charge/discharge of battery module; Thereby battery module moves along the direction of charging fully gradually, perhaps move along discharge termination direction gradually, perhaps periodically for charging → discharge fully terminate neighbouring → near charging → discharge terminates fully.
In other words; Can find out from operating result shown in Figure 180; Generation power output time through between morning, obtaining according to MPPT maximum power point tracking operation is displaced to 12:00 to 14:00 and discharge, and is displaced to 17:00 to the 8:00 of tomorrow and be charge in batteries through operating the generation power output time that obtains according to MPPT maximum power point tracking at 14:00 during the 17:00.
The control method of output of paying attention to level and smooth example 2-4 is as shown in Figure 5.
Control to the charging current of example 2-4 is as shown in Figure 6.
(the 3rd embodiment)
Even third embodiment of the invention relates to the system of when low output, also supplying power with high efficiency, and need be to the complicacy control of DC/AC power converter.
Power-supply system according to third embodiment of the invention has a plurality of power-supply devices that comprise DC power supply string and DC/AC conversion equipment that are parallel-connected to electric power system or load.
The DC power supply refers to from obtaining DC power such as electric organs such as solar cell, wind turbine generator or fuel cells.The DC/AC power converter is so-called converter; It converts direct current into interchange; And can any method use; For example utilize the method for high-frequency insulation transformer and carry out PWM control and utilize the transformer insulated method of commercial frequency, the DC/AC conversion equipment that wherein is arranged in each power string can or can be difference for same type.The DC power of cell stores DC power supply output, and by the storage battery representative, but in addition, only need storage power and allow to obtain power, as in the hydrogen storage system type that with power transfer is hydrogen and storage hydrogen.
Therefore, through arranging to connect the memory cell of one or more DC power supply at least, the present invention can absorb rapid variation; And stable output; In addition, the senior complicated control of DC/AC power converter become there is no need, and can reduce the work number of times of change over switch thus.Power from the DC power supply can promptly through the power of storage DC power supply output in memory cell, can offer load or system with it by time shift being different from time place's output of output time.Can be according to from the output of the peak power output of power-supply system or load or maximum amount of power that system asked, through obtaining the maximum power of in memory cell, storing, control peak power output amount.
In power-supply system of the present invention, the DC power supply is preferably the equipment that is used for exporting from such as the DC power of electric organs such as solar cell, wind turbine generator, fuel cell or its combination.Thus, can use various power supplys, and can combination in any use as the DC power supply.
Like hope ground, power-supply system of the present invention has all been arranged memory cell in each DC power supply.Through arranging memory cell, further reduce and stablized variation, and as a result of from the power output amount of DC power supply, the senior complicated control of DC/AC power converter is become there is no need.Because the more power amount can be stored in the memory cell, thus can increase by the quantity of power of time shift, and can increase the peak power output amount.
In the present invention, the power transfer control unit is confirmed the output of power-supply system through the switch control to the DC/AC power converter.In this case, the power transfer control unit detects the quantity of power of each power string, and the output valve that can confirm power-supply system of the present invention is as its population value.Replacedly, can export from the quantity of power of load or system request.
Thus, according to the present invention, can export sum total such as the output of DC power supplys such as optoelectronic device, wind turbine generator and fuel cell and the power in memory cell, stored.
In the 3rd embodiment, the power transfer control unit starts DC/AC power converter arbitrarily according to determined output valve.Because the power transfer control unit starts DC/AC power converter arbitrarily according to determined output valve, so can high conversion efficiency operation DC/AC conversion equipment.
Power-supply system of the present invention also comprises DC power supply output variable detection part; Be used for detecting the power output amount of DC power supply; Wherein as hoping ground, the power output amount that the power transfer control unit detects according to DC power supply output variable detection part, control DC/AC power converter.The power that thus, can use the DC power supply to generate effectively.
Power-supply system of the present invention also comprises the memory space detection part, is used for the memory space of detection of stored unit, wherein as hope ground, the memory space that the power transfer control unit detects according to the memory space detection part, control DC/AC power converter.Thus, can use the power of storing in the memory cell effectively.
Power-supply system of the present invention also comprises power output amount detection part, is used for detecting the power output amount of power-supply system, wherein as hoping ground, the quantity of power that the power transfer control unit detects according to power output amount detection part, control DC/AC power converter.Thus, can be according to the present invention the power output amount of power-supply system, the control store amount.
In power-supply system of the present invention, control unit periodically starts each DC/AC power converter successively.Through this type of startup, can operate each DC/AC power converter equably.
< configuration of power-supply system >
Shown in figure 19; According to the power-supply system of third embodiment of the invention by following configuration: a plurality of power connection in series-parallel are connected, comprise a plurality of DC power supply 41a, 41b, 41c and be used for changing DC/ AC conversion equipment 42a, 42b, 42c from the DC power of each DC power supply 41a, 41b, 41c.In addition, also arranging has: power transfer control unit 43 is used for controlling DC/ AC conversion equipment 42a, 42b, 42c according to the power output amount of DC power supply; And be connected respectively to DC power supply 41a, 41b, the memory cell 44a of 41c, 44b, 44c.The output of DC/ AC power converter 42a, 42b, 42c is collected into a place, and is connected to commercial electricity 47 or electric power system through load 45 or switch 46.In Figure 19, in each DC power supply, all arranged memory cell, but can perhaps arrange memory cell in a plurality of power supplys at least one.
DC power supply 41 generates power from obtaining DC such as electric organs such as solar cell, wind turbine generator or fuel cells.Under the situation of large-scale DC power supply, the specifications and characteristics of each DC power supply is obviously different, and in solar cell and wind turbine generator, depends on installation site, direction and inclination angle, and output power value is different.Figure 19 shows three DC power supply 41a, 41b, 41c; And three DC/ AC power converter 42a, 42b, 42c; But number is arbitrarily, and can be two or can be many for more, and each DC power supply 41 can be identical with each DC/AC power converter 42; Can have identical performance, perhaps can be different.The DC power supply can be any different combinations, for example solar cell, wind turbine generator or fuel cell.Do not need in DC power supply 41a, 41b, 41c, to arrange respectively memory cell 44a, 44b, 44c, and memory cell can be perhaps more at least one.
DC/ AC power converter 42a, 42b, 42c are so-called converter, and it converts direct current into interchange.The DC/AC power converter can any method use; For example utilize the method for high-frequency insulation transformer and carry out PWM control and utilize the transformer insulated method of commercial frequency, each DC/AC power converter can or can be difference for same type.
Except that the power output amount control according to DC power supply 41, power transfer control unit 43 can also be according to the memory space of memory cell 44, the output of power-supply system or the value control that control unit self is confirmed.
Power-supply system shown in Figure 19 is the system that comprises power transfer control unit 43; Power transfer control unit 43 control DC/AC power converters 42; But can adopt following method; Wherein do not arrange power transfer control unit 43, and among the DC/ AC conversion equipment 42a, 42b, 42c one or all the DC/AC power converters relative to each other control other DC/AC power converters.In Figure 19, shown the situation of these class methods, and can be similar to the situation operation of arranging power transfer control unit 43 with connecting line.
The DC power of memory cell 44 storage DC power supplys 41 outputs, and use storage battery typically.In addition, can adopt the hydrogen storage system of following type, it is stored the hydrogen that generates, and obtains power through hydrogen combusted as required through the Current Decomposition water from 41 outputs of DC power supply.44 needs of memory cell are arranged at least one DC power supply 41, and preferred being arranged in each DC power supply 41.
Power-supply system shown in Figure 19 does not have to arrange to have the switch of memory cell 44 and the node of DC power supply 41, but can arrange to be similar to the switch among first embodiment, and can with the same this type of switch of controlling in first embodiment.
Will be with respect to having solar cell is described the 3rd embodiment with the block diagram of Figure 20 as the embodiment of DC power supply power-supply system.Figure 20 is a kind of example of the 3rd embodiment, and the invention is not restricted to Figure 20.The block diagram of Figure 20 shows wherein and is similar to ground among first embodiment and arranges the view of switch.
Solar module 51 shown in Figure 20 is a thin-film micro crystalline solar cells panel, has maximum power point voltage Vpm=51V, maximum short circuit current Isc=2A and output 85W.Solar battery array 50 has 12 configurations, and wherein solar module 51 is taken advantage of three connections by four.Therefore, maximum is output as 1020W.Figure 20 shows three solar battery arrays.
Battery module 52 has following configuration, and wherein the series connection of the lithium ion battery of 5.7Ah is 48, and disposes the circuit part that comprises protective circuit and power counter.
Will be identical respectively in the memory capacity of generation quantity of power and three battery modules 52 of three solar battery arrays of supposition, still not necessarily must be identical but can describe present embodiment under the condition of different.Because depending on the installation site, solar battery array has different light incomes, so the quantity of power that generates maybe be different.
Be arranged in protective circuit in the battery module 52 by known monitoring IC, FET, Controlled CPU or the like configuration, and the function that has when detect electric voltage exception or the like open circuit and protect storage battery.In other words, protective circuit comprise each unit of anti-overcharge circuit, the anti-accumulator equipment of putting discharge circuit, anti-overcurrent circuit, being connected in series voltage monitoring circuit, be used for regulating the balancing circuitry or the like of the voltage of each unit.
The power counter uses power monitoring IC, and has the function of the charge/discharge power of monitoring storage battery, and can the charged state of storage battery be outputed to the outside.
Through anti-return element 53, the solar battery array 50 of above-mentioned configuration is parallel-connected to battery module 52, anti-return element 53 comprises the diode of arrangement like this, makes the power of battery module 52 can not be back to solar module 51.
Switch 55 is connected between the node 54 and battery module 52 of be connected in parallel solar battery array 50 and battery module 52, and through current sensor 56 and anti-return diode 57 node 54 is connected to DC/AC conversion equipment 60.
Connecting line 59 is a ground wire, is used for solar battery array 50 and battery module 52 are connected to DC/AC conversion equipment 60.
Field-effect transistor (MOS TFT) is used for switch 55.Through the control circuit (not shown), switch 55 is controlled, and so that battery module 52 is connected to solar battery array 50, perhaps breaks off from solar battery array 50.The details of switch 55 will be described later on.
Shunt resistor or the like is connected to current sensor 56, and the voltage at current sensor 56 its two ends of measurement, and current sensor 56 can use Hall element or the like.
Wherein a plurality of power connection in series-parallel that are connected with DC/AC conversion equipment 60 of solar battery array 50 merge, and are connected to load 64.Replacedly, it is connected to electric power system 66 through switch 65, flows (output such as solar cell etc. disperse the generation power of power supply to electric power system) to allow backward power.
Ampere meter 61 is arranged at output with voltmeter 62, detecting the voltage and current that merges a plurality of DC/AC conversion equipments 60, and testing result is offered outgoing management unit 67.Outgoing management unit 67 comprises that memory cell 68 is with the storage data.
Through holding wire 69, the signal of the magnitude of voltage of battery module 52, memory space, SOC (charged state) or the like is offered DC/AC conversion equipment 60, and use this signal to confirm the output of DC/AC conversion equipment 60.This signal is provided for outgoing management unit 67, and is used the control signal as DC/AC conversion equipment 60.
Use the holding wire 70 that connects holding wire 69 and outgoing management unit 67 as connecting line; Offering outgoing management unit 67 such as signals such as magnitude of voltage, memory space, SOC; And outgoing management unit 67 instruction manipulations/stop the signal of DC/AC conversion equipment 60 are provided, of later on.
In above-mentioned configuration, solar battery array 50 generally is installed in the strong place of sunlight, for example roof or roof.Battery module 52 and DC/AC conversion equipment 60 leave in be arranged under the solar cell shelf or the structure near solar battery array 50 in.Distance between solar battery array 50 and battery module 52 or the DC/AC conversion equipment 60 is longer thus, and need design the consideration connection resistances thus.
In above-mentioned configuration, like hope ground, solar module 51 serviceability temperature excellents and can be set to the element of appropriate voltage scope, for example thin-film solar cells.The solar cell of non-crystal silicon solar cell or tandem structure be can use, crystallized silicon and amorphous silicon wherein piled up.
Like hope ground, battery module 52 is not for having owing to the cycle degradation that lacks charging and the battery of memory effect.Lithium ion battery is suitable for this type of battery apparatus, wherein is preferably lithium ion battery, because can be corresponding to solar cell that the voltage range setting is narrower, the charge/discharge curve be more smooth, and does not have cycle degradation and memory effect in the partial charging.
The voltage range of battery module 52 is set to following voltage range; On this voltage range; On predetermined insolation and temperature,, can obtain 60% to 100% power with respect to the maximum power point voltage (Vpmax) of solar cell when being scheduled to insolation and temperature.Output that thus can the level and smooth solar cell of narrow voltage range.
General solar cell system has the working point by insolation condition and maximum power point tracing method control; It is according to the variations in temperature of solar cell device; But in the present invention, operation makes the voltage of battery module 52 become the quiescent potential of solar battery array 50.The quiescent potential of solar battery array 50 can be limited to the wherein voltage range of battery module 52 work.
As shown in Figure 3, the operating voltage range of battery module 52 is the scope of SOC 20% to SOC 80% in the P-V curve of solar battery array.Percentage with respect to the maximum power point voltage (Vpmax) of SOC 20% to SOC 80% scope is 92% to 100%, and is as shown in Figure 3.
Usually, when the temperature of solar module 51 rose, output trended towards descending, and representes that the temperature coefficient of its slope is designated as negative.For example, the temperature coefficient of silicon metal be-0.45 to-0.5%/℃.
On the other hand, the operating voltage of battery module 52 is temperature influence hardly, and therefore like what hope, the solar module 51 that uses is in the present invention selected the solar cell of excellent in temperature characteristic.For example, like hope, temperature coefficient is less than or equal to-0.42%/℃, and further be less than or equal to-0.3%/℃.Thus, as stated, wherein temperature coefficient be-0.17 to-0.2%/℃ thin-film solar cells be suitable for the solar cell of little temperature coefficient, wherein can obtain high system effectiveness through utilizing this thin-film solar cells.
< setting of voltage range >
In the present invention, for the voltage range of battery module 52 charge/discharges is the scope of SOC 20% to SOC80%, as shown in Figure 4.
Therefore if motionless under the state near charging fully, even do not use, lithium ion battery also can be degenerated, and when use lithium ion battery during as accumulator equipment, preferably according to the cyclophysis of battery, utilizes the power of battery core.
The type of type that can be through suitable selection solar module 51 tandems and number, battery module 52 tandems and number and realize above-mentioned voltage in the charged state of using.Above-mentioned voltage range can be fixed, and perhaps can change settings successively according to degenerate state of insolation amount or weather conditions, accumulator equipment or the like.
When changing above-mentioned voltage, can through suitably being segmented into the suitable period, voltage range be set according to past insolation data and air themperature data according to insolation condition and weather conditions.
For example, in air themperature low winter, voltage range is set for high, because the temperature step-down of solar module.In air themperature high summer, it is low that voltage range is set.In addition, at spring and fall, the intermediate voltage scope in winter and summer is set.Thus, when considering that the insolation condition is provided with, in the stable zone of insolation, can lower limit be set to more than or equal to 80%.
In addition, along with the degeneration of battery module 52, internal resistance increases, and can be provided with in advance thus, thereby in above-mentioned scope, improves charging termination voltage with step-by-step system, and reduces discharge termination voltage.For this reason, can arrange switch, thereby can utilize means of communication or the like, be updated in the settings that is provided with in the Control Software.
< charge control method >
In the present invention, the output of level and smooth DC/AC conversion equipment 60, and, can control charging to battery module 52 through the output of control from DC/AC conversion equipment 60.That is the value that, obtains through the output that deducts DC/AC conversion equipment 60 quantity of power that generates from solar battery array 50 becomes charge power.According to this type of output control, the generation power output of level and smooth solar battery array 50, and the control of can charging.
The output of DC/AC conversion equipment 60 control can be constant output, and is absorbing the variable power from solar battery array 50, constant thereby the output that perhaps can control DC/AC conversion equipment 60 becomes charging current.
Control method such as above Fig. 5 of paying attention to level and smooth output are said.Situation such as above Fig. 6 of control charging current are said.
< about the balance of capacity >
The output P1 (W) of solar battery array and the memory capacity W1 (Wh) of battery module are preferably P1 * 1hr＜W1.If the battery capacity of this kind degree is provided, then the output equilibrium in the careful time interval becomes possibility.More preferably, it is P1 * 0.5hrs, is most preferably P1 * 0.3hrs.The charging current (in one hour, being full of the electric current of battery capacity) that general accumulator equipment is allowed about 1C, and therefore be preferred, if because minimum value is P1 * 1hr, then can enlarge the selection of accumulator equipment widely.
Realizing that when of the present invention, even bigger, the maximum capacity of battery module 52 can not throw into question yet, but is preferably P1 * 10hrs, and from the viewpoint of work ratio of equipment size, cost, equipment or the like, more preferably P1 * 5hrs.If memory capacity is enough, then can obtain with the level and smooth output of the careful time interval and to power carry out time shift long power displacement (equilibrium) both, be preferred thus.
< to the description of conversion handover operation >
In the 3rd embodiment; Detection is connected to the voltage of the battery module 52 of solar cell string; And switch 55 connects or breaks off; And after the charging solar battery array 50 is being separated a period of time fully thus, and following the generation power that only uses solar cell in the rate point-tracking method in maximum.After this when the generation power of solar cell descends, connect battery module 52 once more, and can utilize the joint Power of solar battery array 50 and battery module 52.
In the 3rd embodiment, detect electric current from solar battery array 50, and diverter switch 55.Therefore; If each solar cell connection in series-parallel connects; Shown in figure 20; And descending or get in the insolation amount of some solar battery array of firm power control period shady and coolly makes the output of some solar battery array descend, and under extreme case because fault generates power becomes impossiblely, then avoid exporting and ask only to focus on the specific solar cell array.
In the 3rd embodiment, the solar cell string comprises battery module, and also required quantity of power can be provided even without insolation thus.But; If output is switched to only solar battery array 50 when the constant memory space of consumption is perhaps bigger; If require the power of the ability that is greater than or equal to; Then voltage descends, but this is limited because of can this power of power being provided from solar battery array 50, encourages the output from the storage battery 52 in another solar cell string thus.
Break off solar battery array 50 and storage battery 52 if send signal shift switch 15 from the outside, then can in MPPT maximum power point tracking, operate solar battery array 50 through the proper communication means.
< control algolithm >
The power-supply system of the 3rd embodiment shown in Figure 19 or Figure 20 is operated according to following operative algorithm.
Power-supply system of the present invention utilizes relevant insolation intensity constantly to derive the power that will export as input variable according to pre-defined algorithm (utilizing the function of variable).Shown in the table 1 of Figure 21, this algorithm carries out the control of volume amount corresponding to insolation intensity.This algorithm stores is in the memory cell 68 of outgoing management unit 67, and the output power value of being asked that is calculated by outgoing management unit 67 is sent to each DC/AC converter by the form with the signal of telecommunication.
In the table 1 of Figure 21, " the volume amount control 1 " that is shown as instruction mode refer to when insolation intensity be 0 to 0.3kW/m 2The time only operate the instruction of a DC/AC converter.In this case, to by the DC/AC converter 20 of instruction manipulation ask to be output as (insolation intensity) * (the generation power of a solar battery array) * 3.
" volume amount control 2 " is 0.3 to 0.6kW/m for working as insolation intensity 2The instruction of two DC/AC converters of time operation.In this case, to by the DC/AC converter 20 of instruction manipulation ask to be output as (insolation intensity) * (the generation power of a solar battery array) * 1.5.
" amount operation in full " is 0.6 to 1.0kW/m for working as insolation intensity 2Time operation is arranged in the instruction of all the DC/AC converters 60 in each solar battery array 50 respectively.In this case, to each by the DC/AC converter 20 of instruction manipulation ask to be output as (insolation intensity) * (the generation power of a solar battery array) * 1.
" operation of volume amount " will be described with object lesson.
The insolation intensity that obtains wherein to get into each solar battery array 50 when current sensor 56 is corresponding to about 1.0kW/m 2When the detection of (sunlight intensity under the fine gratifying situation of Japan) is exported; Outgoing management module 67 is according to the algorithm of table 1 shown in Figure 21; Select " amount operation in full " for instruction mode, and output startup/operational order is given all DC/ AC converter 60a, 60b, 60c.Each solar battery array 50 shows the maximum power generative capacity, and is battery module 52 chargings thus, and simultaneously through DC/ AC converter 60a, 60b, 60c, backward power makes maximum power flow to electric power system 66.Replacedly, each solar battery array 50 provides power to load 64.
In this description, insolation intensity is detected by current sensor 56, but can be detected by the ampere meter 62 or the voltmeter 63 of the position that is arranged in a plurality of DC/AC converters 60 merging.This is identical in the following description.
When insolation intensity continued, aforesaid operations continued.In other words, each solar battery array 50 shows the maximum power generative capacity, and is battery module 52 chargings thus, and simultaneously through DC/ AC converter 60a, 60b, 60c, backward power makes maximum power flow to electric power system 66.Replacedly, each solar battery array 50 provides power to load 64.
When the detection output from current sensor 56 detects insolation intensity is 0.1kW/m 2The time, outgoing management module 67 is read " volume amount control 1 " from the algorithm of Figure 21.Outgoing management module 67 is through holding wire 69,70; Read out in the magnitude of voltage that detects in the voltage detection unit 71 that is arranged in each battery module 52; And it is compared, in all battery module 52a, 52b, 52c, to select the battery module of indication maximum voltage value.
For example hypothesis has been selected battery module 52a.The DC/AC converter 60a that is connected to relevant battery module 52a is activated the conversion operations with instruction DC/AC.Provide halt instruction (t1 that sees Figure 22 is to t2) to other DC/AC converters 60b, 60c.
Be three times of the power that in solar battery array 50a, generates basically to the request power output of DC/AC converter 60a.Request output Power Calculation formula is (insolation intensity (kW/m 2)) * (the generation power of a solar battery array) * 3.Therefore, 0.1 * 1.02 * 3=0.306kW.
In this case, under the situation of the power that in having only solar battery array 50a, generates, the power output of being asked shows not enough, and the quantity of power that is lacked thus obtains from battery module 12a.DC/AC converter 60a is operated when height is exported thus, and on high conversion efficiency, operates.
Simultaneously, DC/AC converter 60b, 60c shut-down operation, and be output as corresponding battery module 52b, 52c charging through solar battery array 50b, 50c.In this case, fill with charging current with little charging current.
If the insolation Strength Changes is little after 5 minutes, and 0 to 0.3kW/m 2Scope in, then outgoing management module 67 in all battery module 52a, 52b, 52c, select the indication maximum voltage value battery module.Promptly in formerly 5 minutes, selected battery module 52a, and consumed its memory space, so the battery module of the magnitude of voltage bigger than battery module 52a is indicated in search.
In this case, if the bigger magnitude of voltage of battery module 52b indication then sends startup/operational order to the DC/AC converter 60b that is connected to relevant battery module 52b.Send halt instruction to DC/AC converter 60a.Continuation is sent halt instruction to DC/AC converter 60c.(t2 that sees Figure 22 is to t3).
When during to DC/AC converter 60b handover operation, being instructed the DC/AC converter 60a that stops to reduce voltage gradually from DC/AC converter 60a, and DC/AC converter 60b boosted voltage gradually, thereby can realize continuous switching.
Thus, this time, the power output of asking same as described above is sent to DC/AC converter 60b, and the generation power of solar battery array 50b and export to electric power system 66 through DC/AC converter 60b from the discharge power of battery module 52b.
When insolation intensity after three minutes is increased to 0.5kW/m 2The time; Detect this situation from the detection output of current sensor 56; And outgoing management module 67 detects " volume amount control 2 " immediately, and in all battery module 52a, 52b, 52c, selects two battery modules of indication maximum voltage value and second largest magnitude of voltage.Send startup/operational order to the converter that is connected to these two battery modules.In this case, select DC/AC converter 60a and DC/AC converter 60c, and send startup/operational order to it.Send halt instruction (t3 that sees Figure 22 is to t4) to DC/AC converter 60b.
In this case, giving the request power output of each converter is 0.5 * 1.02 * 1.5=0.765kW, and adds up to 1.53kW.
Through operating power system in the above described manner, when the generation quantity of power of insolation intensity decreases and solar battery array descended, the number of the converter that can operate was suppressed to minimum value.Compare with the routine operation method, this has advantage, promptly can reduce the energy of the operation that is used to safeguard converter, in the routine operation method, even when low insolation, also operate all converters.
< vague generalization operative algorithm >
Can be in the following manner with above-mentioned operative algorithm vague generalization of the present invention.
At first, precondition is following.
The number of-solar battery array (number of=converter): n
-insolation intensity: less than 1/n (kW/m 2)
Below under this type of condition with the operative algorithm vague generalization.
A) in n converter, only start/be operationally connected to the converter x of battery module, and stop the operation of other (n-1) individual converters with maximum voltage value.
B) power output of being asked to the converter x that is started is for n times (that is, from the battery module that be connected to associated solar array obtain (n-1) doubly power) of relevant insolation intensity by a generation quantity of power that solar battery array generated.
C) every one set time of mistake, the definite again converter that will operate in outgoing management unit.That is, at operation converter x after one set time, the memory space of all battery modules relatively once more, and the converter y that is connected to the battery module of indication maximum voltage value begins startup/operation.Send the instruction of shut-down operation to converter x.
D) when switching converter, reduce the power output of converter x by fixed slope in several seconds, and in the identical time by the power output of fixed slope increase from converter y, be not interrupted thereby power output can not become.
E) if surpassing threshold value through insolation Strength Changes before the set time, then the outgoing management unit is confirmed immediately once more, and resends instruction to each converter.
Operative algorithm with following precondition is following.
The number of-solar battery array (number of=converter): n
-insolation intensity is to 2/n (kW/m less than 1/n 2)
A) in a constant n converter, only start/be operationally connected to converter x, the y of two battery modules, and stop the operation of other (n-2) individual converters with maximum voltage value and second largest magnitude of voltage.
B) power output of being asked to the converter x that is started, y is for n/2 times (that is, from the battery module that be connected to associated solar array obtain (n/2-1) doubly power) of relevant insolation intensity by a generation quantity of power that solar battery array generated.
C) every one set time of mistake, the definite again converter that will operate in outgoing management unit.That is, at operation converter x, y after one set time, the magnitude of voltage of all battery modules relatively once more, and the converter za that is connected to two battery modules with maximum voltage value and second largest magnitude of voltage begins startup/operation.Send the instruction of shut-down operation to converter x, y.
D) when switching converter, reduce the power output of converter x, y by fixed slope in several seconds, and in the identical time by the power output of fixed slope increase from converter za, be not interrupted thereby power output can not become.
E) if surpassing threshold value through insolation Strength Changes before the set time, then the outgoing management unit is confirmed immediately once more, and resends instruction to each converter.
In another example of the 3rd embodiment, under the situation that the output of supposition solar battery array and the power in battery module, stored equate basically, each solar cell string of starting by sequence.That is, start by sequence DC/AC converter 60a to 60c, shown in the sequential chart of Figure 23 according to equal spacing.Through confirming the order and the time interval in advance, transducer and control become unnecessary, and can utilize easy each DC/AC converter of algorithm controls.Therefore, outgoing management unit 67 can be eliminated, and only boot sequence need be in the DC/AC converter, confirmed.
As another example of the 3rd embodiment, when being applied to large-scale power-supply system, the solar battery array area that becomes is bigger, and can't obtain identical output from each solar battery array thus.For example, because direction and inclination angle that solar battery array is perhaps installed in the installation site exist in solar battery array that generates a large amount of power morning and the solar battery array that generates a large amount of power between the lights.Need use the solar battery array of different area inevitably.Thus, the output of each solar battery array and the quantity of power of in battery module, storing are different.In addition, if prediction cloudy day tomorrow or rainy, then could be according to each power-supply system of this PREDICTIVE CONTROL.
In other words, with respect to the solar cell string that is included in the solar battery array that generates a large amount of power morning, control storing a large amount of power in the morning, and discharge a large amount of power between the lights.With respect to being included in the solar cell string that generates at dusk the solar battery array of a large amount of power, controlling storing a large amount of power between the lights, and discharge a large amount of power in the morning.
Similarly, if prediction cloudy day tomorrow or rainy then can be that the discharge of today is less, and make discharge tomorrow bigger.
(the 4th embodiment)
Power-supply system according to fourth embodiment of the invention comprises: a plurality of DC power supply strings wherein are parallel-connected to the DC power supply with storage battery; The DC/AC power converter is used for a plurality of DC power supplys are series-connected to electric power system or load; And the storage battery control unit, be used for controlling the DC/AC power converter, thereby make each battery tension become equal basically.
Because the voltage through aiming at each storage battery can not have deflection from the electric current of each DC power supply string acquisition same amount, so power converter can be from this power-supply system request maximum power.
In the power-supply system of the 4th embodiment,, be charge in batteries/discharge with the scheduled current like hope ground.
The 4th embodiment also comprises the battery current detecting unit, is used for detecting the output current of each storage battery.Through arranging the battery current detecting unit, can aim at the voltage of each storage battery, and can obtain the electric current of same amount and not have deflection from each DC power supply string thus, and power converter can be from this power-supply system request maximum power.Because just detect and control the power request and the battery current of DC/AC power converter, so can utilize very simple control circuit to realize this control or target of the present invention.
Preferably; Power-supply system of the present invention has the storage battery control unit; It is controlled and makes for example on each scheduled time, perhaps according to fixed distance, perhaps when battery tension reaches predetermined voltage; Before DC/AC power converter power output, it is equal basically that each battery tension becomes.According to this type of control, when the power-supply system power output, the output of each storage battery is equal basically, and thus the overall power of each storage battery can be provided.
In example, preferably, power-supply system of the present invention has the DC power supply for solar cell or fuel cell.Thus, can use the generation power output of solar cell or fuel cell effectively.Similarly, also can use the DC power supply that obtains through the AC power supplies of changing power electric generator, wind turbine generator or the like.
In example, preferably, power-supply system of the present invention connects each DC power supply through the anti-return diode.Utilize simple circuit just can prevent overcharging thus to the storage battery in each DC power supply string, arranged.
In addition, according to another viewpoint, (this power-supply system comprises a plurality of DC power supply strings to power-supply system, and it has DC power supply and storage battery; And the DC/AC power converter, be used for converting the DC of a plurality of DC power supply strings output into AC output) control method comprise: first handles, and the voltage of controlling each storage battery makes it equal basically; And second handle, from DC/AC power converter power output.Can obtain the overall power of each storage battery then.
The control method of power-supply system of the present invention also comprises: the 3rd handles, wherein when the output of DC power supply not simultaneously, the minimum DC power supply output variable charging of each storage battery to aim at, and export remaining DC power supply output variable to power converter.In other words; In the 3rd handles; When the output that connects n+1 DC power supply string and each DC power supply not simultaneously; Control make the DC/AC power converter always ask to be greater than or equal to (I1-Ia)+(I2-Ia)+... power output (In-Ia), wherein Ia is a minimum current, and I1, I2 ... In is the electric current of the residue DC power supply of DC power supply.
Thus, export from obtain to generate power such as DC power supplys such as solar cell or fuel cells, and can be aligned to the charge volume of each storage battery.
Preferably, when in first handles, having the voltage of basic each storage battery that equates, the control method of power-supply system of the present invention increases the power output of power converter gradually.When carrying out this type of control, can make battery tension identical through the little electric current that flows.
Preferably, when in first handles, having the voltage of basic each storage battery that equates, whether each storage battery of control method inspection of power-supply system of the present invention is all at the identical electric current of output.
(the 4th embodiment-1)
The 4th embodiment-1 is following electrical voltage system, and it enables to obtain from this power-supply system the overall power of each storage battery, and prevents excessively to use a storage battery.
Shown in figure 24, the power-supply system of fourth embodiment of the invention disposes DC power supply string 81 through DC power supply 71a and storage battery 72a are connected in parallel, and a plurality of DC power supply strings 81 are parallel-connected to DC/AC power converter 82.Figure 24 shows the situation that three DC power supply strings 81 is connected to DC/AC power converter 82, but does not limit the number of DC power supply string, and can or can be three or more for two.A plurality of with each part of inferior indication in Figure 24 to indicate.
DC/AC power converter 82 is connected to system's tie point 83, and the power-supply system of the 4th embodiment is sold power output to system's tie point 83.Replacedly, though do not show, can power be provided to load.Storage battery control unit 84 is connected to DC/AC power converter 82, and controls DC/AC conversion equipment 82 with being described below.
Anti-return diode 73 is connected than the node S of DC power supply 71 and storage battery 72 more on the side near the DC power supply.Anti-return diode 74 is connected between the node T and node S of each DC power supply string.Diode 73 prevents that electric current from flowing into DC power supply 71, and diode 74 prevents the Power Exchange between each DC power supply string.On the outlet side of storage battery, connect the parts (for example electric current fuse) or the circuit breaker 75 that are used to guarantee storage battery safety, to allow the electric current in the storage battery safe range.
DC power supply 71 is the DC power supply that obtains from solar cell, fuel cell or the like, but can be for being the DC power supply that DC power obtains through power transfer that wind turbine generator or power electric generator are obtained.In the 4th embodiment, solar cell is described.
System's tie point 83 shows and absorbs through operating the part of the power that power-supply system of the present invention generates, and can be storage battery, as long as can absorb power output.Can the power that in storage battery, charges be offered load subsequently.
Storage battery 72 as in DC power supply string, arranging can use polytype storage battery, for example excide battery, lithium ion battery, nickel-based battery or the like.In this enforcement, lithium ion battery is described.Can storage battery be replaced with double-layer capacitor or superconduction power storage devices.
In Figure 24, between storage battery 72 and node S, do not arrange switch, but can with the same switch of arranging in first embodiment, and with the same this switch of controlling in first embodiment.
The power-supply system of the 4th embodiment-1 can be for being installed in the Miniature Power Unit system in the general family house; Perhaps can be the medium-sized or large-scale power-supply system on the roof that is installed in apartment, factory, communal facility or the like, but power-supply system of the present invention need be a plurality of DC power supply strings.Therefore, solar cell is divided at least two zones, and for each cut zone arrangement storage battery, to dispose a plurality of DC power supply strings.Through a plurality of solar cell string locations or the solar battery cell group of being connected in series, dispose solar cell.
The power-supply system type of the 4th embodiment is identical with the solar module of first to the 3rd embodiment.The battery module of the 4th embodiment-1 is identical with the battery module of first to the 3rd embodiment.
In the following description; In the 4th embodiment-1,, need the inhibition of the output current value of storage battery be lower than or equal 5A from the system safety aspect; And the specified 300W that is output as of each solar cell; And the use zone of battery tension is between 40V and 60V, but explains that these digital values are in order to explain, rather than will limit scope of the present invention.In the following description, show that the current value of each storage battery and magnitude of voltage are beneficial to describe, but in the 4th embodiment-1, need not detect these current values and magnitude of voltage, and therefore need not arrange current sensor or voltage sensor.
In circuit shown in Figure 24, the voltage of storage battery 72a, 72b, 72c is all aimed on 40V.After this, solar cell 71a, 71b, 71c carry out photovoltaic power generation and think each charge in batteries.But solar cell 71a is hidden in the shade of black clouds, and generates power output decline.Solar cell 71c is hidden in the shade, and does not generate power.As a result, storage battery 72a becomes 50V, and storage battery 72b becomes 45V, and storage battery 72c becomes 40V, and the variation of the voltage of each storage battery has taken place.The reason of the variation of the voltage of each storage battery not only is the variation of insolation amount, but also is that the installation direction of each solar cell, the area of each solar cell, the power of each solar cell generate the charge characteristic of performance and each storage battery.
After this, under the situation of the change in voltage of each storage battery, when power converter 82 proposes power request, from high-tension storage battery power output.Because in native system, do not monitor each cell voltage and battery current,, can ask 5A or higher scarcely so export under the worst case (each cell voltage alters a great deal) of whole 5A from a string in hypothesis.In native system, electric current is big more, and the correction change in voltage is rapid more, and 5A is preferred thus.In this case, storage battery 72a has ceiling voltage, and thus from storage battery 72a power output.Other storage batterys 72b, 72c can't contribute to output, and this is because voltage ratio storage battery 72a is fully low.Power-supply system is merely able in the allow current scope of storage battery 72a, supply power thus.
In order to solve the variation of each above-mentioned battery tension, in the power-supply system of the 4th embodiment-1,84 requests of storage battery control unit are from power converter 82 output 5A.Storage battery 72a has than other storage batterys 72b, voltage that 72c is high, and flows out electric current from storage battery 72a thus.If the internal resistance of storage battery 72a is 1 Ω, the voltage of storage battery 72a is owing to the internal resistance amount descends, and the actual 45V that becomes.Thus, voltage becomes and equals the voltage of storage battery 72b from the teeth outwards.After this, along with the carrying out of discharge, also from storage battery 72b power output.In a period of time, discharging current is obviously bigger in storage battery 72a, and storage battery 72a is more than storage battery 72b discharge thus, and voltage descends also very fast.Therefore, the voltage of node T drops to 40V, and also begins to discharge from storage battery 72c.Become moment of 40V at the voltage of node T, the discharging current of storage battery 72a is 3A, and the discharging current of storage battery 72b is 2A.Storage battery 72a when not having the discharge polarization, the voltage of 72b are respectively 43V, 42V, and on this time point, the voltage differences of two storage batterys reduces to 1V from 5V.
Similarly; Even if power converter 82 continues request 5A after the voltage of node T becomes 40V; Then power converter 82 operations make that the voltage between the storage battery is aimed at, and wherein as the result who continues this generic operation, each storage battery discharges according to 1.7A; This moment, node T became 37V, thereby voltage is aimed at fully.At first ask to begin from control unit 84, exactly passed through one hour from power converter 82 output 5A.
In native system, under the situation of not monitoring each battery tension and battery current,, can aim at each battery tension through the power on the electric current of a string of power converter 82 request periodically safety quickly.
Therefore; Utilize the voltage of node T to explain that the reason of the voltage of each storage battery is: because on roof or roof, solar cell is installed; And that storage battery is installed in is indoor, thus solar cell be connected through connecting line with storage battery, and therefore voltage since the resistance of connecting line descend.
As stated, can aim at the voltage of three storage batterys.Simultaneously, 82 of power converters request power output, and 84 of storage battery control units send the output request to power converter 82, wherein through making each storage battery output, make the voltage autoregistration, and do not need other special controls thus.In this case; Scheduled current is that power converter is only asked can flow scarcely and is greater than or equal to the electric current of electric current of allow current in each string; And be 5A in the 4th embodiment-1, but can be for any ampere, as long as it is less than or equal to 5A.Because this operating period power converter 82 requested power outputed to system's tie point to sell electric power, so the power of in storage battery, storing can not wasted.Electric power is different with selling, and can replace system's tie point and arrange storage battery, thereby power storage is in storage battery, to be used as power supply, as the part of power-supply system of the present invention.
After this; After the voltage of three storage batterys is aimed at; When selling electric power to the system tie point or when load is filed a request, can obtaining output safely, repressed maximum current under the situation of the safety of considering each power supply string is also like this even control unit makes power converter 82 outputs; For example from each power supply string 5A, and maximum current 15A altogether.
At the DC power supply is under the situation of solar cell, when reaching the scheduled time, for example,, for a set time, operates the power-supply system of the 4th embodiment-1, thereby can aim at the voltage of each storage battery perhaps in one day the morning after the sunset.Replacedly, can be before power-supply system power output of the present invention, control is to aim at the voltage of each storage battery.Can in control unit, arrange timer, thereby when having passed through predetermined time interval when (for example a set time or per three hours), in each DC power supply string, the output of the generation power of solar cell can be different.Thus, under the voltage of supposing storage battery becomes inconsistent situation, can carry out aforesaid operations.Preferably, know the frequency of actual generation systems change in voltage, thus can predict how long above-mentioned control need be carried out and frequency how.
In the 4th embodiment-1; Along with solar cell generates power; Be charge in batteries, and give system tie point or load through power converter as supply of electric power with the generation power output of solar cell, this will describe in the 4th embodiment-2 and the 4th embodiment-3.
(the 4th embodiment-2)
Figure 25 shows the power-supply system of the 4th embodiment-2.The 4th embodiment-2 is to have arranged current sensor 76a, 76b, 76c with the difference at configuration section of Figure 24; Be used for detecting the charging current or the discharging current of each storage battery, detect output, and the result is sent to storage battery control unit 84 by current detecting unit 85 monitoring; And arranged voltage sensor 77; Be used for detecting the voltage of the node T of each DC power supply string, detect output, and the result is sent to storage battery control unit 84 by voltage detection unit 86 monitoring.Other are identical with the 4th embodiment's-1 shown in Figure 24.Figure 25 does not show that being used on the outlet side of storage battery 72 guarantees the electric current fuse or the circuit breaker 75 of the safety of storage battery, and is complicated to prevent accompanying drawing, but can be connected similarly with Figure 24.Consider the safety of system, need the current output value of storage battery be suppressed be lower than or equal 10A.
In circuit shown in Figure 25, the voltage of storage battery 72a, 72b, 72c all is aligned on the 50V at this moment.Strictly say, in the 4th embodiment-2, also on node T, measure the battery tension of each DC power supply string, but for convenience's sake, describe each battery tension.After this; Solar cell 71a, 71b, 71c are each storage battery 72a, 72b, 72c charging, but the output of the generation power of solar cell 71a, 71c descends, and the result; Storage battery 72a becomes 60V; Storage battery 72b becomes 55V, and storage battery 72c becomes 59V, and the change in voltage of each storage battery.Replacedly, take place because the variation that the individual difference of the performance of each solar cell and each storage battery causes.The voltage of detection node T on the highest battery tension, and detect 60V thus at that point.
Because 60V is arrived as 40V in the zone of using of storage battery, so when the voltage that detects node T was 60V, control unit 84 proposed the power request of 2A to power converter 82.Replacedly, before power converter output, perhaps for the scheduled time or fixed intervals, control unit 84 proposes the power request of 2A to power converter 82.
Electric current flows out from storage battery 72a then, but because the internal resistance of storage battery 72a is 1 Ω, descends so voltage is measured by this, and the actual 58V that becomes.Thus, the height of this voltage ratio storage battery 72b, 72c, and have only storage battery 72a output.Then, control unit 84 increases the power request amount of power converters 82, thereby the voltage of storage battery 72a becomes and equals the voltage of storage battery 72b.Control unit 84 also increases the power request amount of power converter 82, thereby the voltage of storage battery 72b, 72c becomes and equals the voltage of storage battery 72a.When three storage battery 72a, 72b, 72c become identical from the teeth outwards, can be from three storage battery 72a, 72b, 72c output current.
Because can aim at the voltage of three storage batterys as described above, can reduce the power output of power converter 82.When the electrorheological of three storage batterys gets when identical, control unit 84 shut-down operation power converters 82, and power-supply system waits for, until having proposed the power output request.
Describe above explanation in detail with utilizing flow chart shown in Figure 26.Promptly; In power-supply system; When the output that connects n+1 power supply string and DC power supply not simultaneously; The 3rd processing is provided: control make power conversion device always ask to be greater than or equal to (I1-Ia)+(I2-Ia)+... quantity of power (In-Ia), wherein Ia is a minimum current, and I1, I2 ... In is the residual current of DC power supply.The 3rd processing can be provided as required.
When in detecting three storage battery 72a, 72b, 72c one becomes 60V (when the voltage of node T is detected as 60V); When the output current mistake standard of three storage battery 72a, 72b, 72c is greater than or equal to a predetermined value; When reaching the scheduled time; Before the power-supply system power output, perhaps when reaching predetermined time interval, control unit 24 at first detects electric current I 1, I2, the I3 that flows out from each storage battery.The maximum current of supposing detection is that Imax and minimum current are Imin, confirms then whether Imax is greater than or equal to 10A (step S 1).If Imax is greater than or equal to 10A, then reduce the request power (step S2) of power converter, and processing turns back to step S1.If Imax less than 10A, then handles and advances to step S3.
Determine whether to export Imin (step S3) then.If export Imin, then reduce the request power (step S4) of power converter, and processing turns back to step S3.If do not export Imin, then handle and advance to step S5.
Whether inspection electric current I 1, I2, I3 identical (step S5).Because be difficult to accurately obtain I1=I2=I3, so a scope preferably is provided, for example the difference between Imax and the Imin is in 10%.If I1=I2=I3 (value is actual to be zero) then stops to flow.If do not satisfy I1=I2=I3, then increase the request power (step S6) of power converter, and processing turns back to step S1.
In the 4th embodiment-2; In three storage battery 72a, 72b, 72c one approach zero and the state of discharge under, power controlling conversion equipment 82, still; If added generation power output from solar cell; Then arrange to be used to detect the detecting unit of associating output, wherein monitor the output of uniting of each string, and unite output in minimum and approach to control under the zero state.That is, definite benchmark of step S3 is not set to Imin, but the minimum value of uniting output is set to approach zero value.Thus, storage battery power use amount is suppressed to minimum, and can the fastest mode aims at the voltage of each storage battery.This is because of from the point of string output, can suppose that it is the identical voltage with on node T that its crosstalk is pressed in surperficial going up.Scheduled current refers to Imin operation approaching zero on it but is not zero electric current that perhaps Imax operates the electric current near allow current on it.
With describing the voltage and the electric current of above-mentioned each storage battery of passage in time.
Figure 27 is used for describing the voltage of each storage battery of passing in time and the block diagram of electric current, has shown that wherein two DC power supply strings are to simplify description.Figure 28 shows the voltage and the change in current of each storage battery of when from power converter request power, passing in time.Suppose that each solar cell carries out constant output.Originally the storage battery of higher cell voltage is 72a, and lower be 72b.
When power converter request power, at first the storage battery 72a from higher cell voltage exports.If the power converter requested power can't be covered by the solar cell 71a of higher cell voltage, then also from the storage battery 72a discharging power of low voltage.About solar cell 71a and storage battery 72b, according to the power request amount of power converter and the voltage differences between the storage battery 72a, confirm power is discharged to power converter, still make this power be storage battery 72b charging.In Figure 28,, the power of solar cell 71b is filled accumulators 72b in the regional A of very first time T1.In Figure 28, for these actual conditions of storage battery 72b charging through following indication: the electric current of storage battery 72b is under the S of the charge and discharge boundary line of battery current.
In regional A, continue above-mentioned state, wherein when the area B of entering from time T 1 to time T2, battery tension is aimed at from the teeth outwards.This is following state, if wherein when cell voltage is aimed at from the teeth outwards power converter stop power request, then voltage once more since polarization disperse.In area B, the current difference of storage battery 72a and storage battery 72b is in saturation condition, even wherein from power converter request more power, it is bigger that this current difference can not become yet.But current difference still exists, and wherein the voltage differences of two storage batterys becomes littler according to current difference, and the electrorheological of two storage batterys of finally flowing through gets identically, and its voltage also becomes identical, and reaches the zone C of indication after time T 2.In zone C, obtain following state, wherein the voltage of two storage batterys is aimed at by reality.
That is, change,, then we can say the variation of each storage battery is corrected with prestissimo if then state is in the area B if in each storage battery, exist.The condition that is present in the area B comprises as precondition: power converter is being asked power fully.If power converter is not being asked power fully, then less to the polarization of the discharge side of storage battery 72a, and do not aim at battery tension from the teeth outwards.When aiming at battery tension from the teeth outwards to attempt pressure through the request power that increases power converter; Change in voltage is bigger; It is too big that the discharging current of storage battery 72a becomes, and storage battery possibly become overcurrent thus, and circuit may burn and be cut off; Fuse may blow, and can not guarantee the safety of system.For reason given above, if can't aim at battery tension from the teeth outwards, then need the power controlling conversion equipment big as much as possible, and degree can not make above-mentioned state take place with request.
As stated, the 4th embodiment-2 variation of can prestissimo aiming at each storage battery.In addition, can aim at each battery tension rapidly, this is because the request power of power converter is less, and can to make the discharge power of storage battery be little.In the description of present embodiment, do not describe the situation of the request power of minimize power conversion equipment, but can come the request power of minimize power conversion equipment through measuring and control the output of solar cell.
(the 4th embodiment-3)
To utilize Figure 25 to describe the 4th embodiment-3.In the 4th embodiment-3; Realized following method: the transducer 73a, 73b, the 73c that are used for detecting the electric current of storage battery through utilization; When the generation quantity of power of solar cell not simultaneously, charge in batteries at utmost, is prevented the variation of the voltage of storage battery simultaneously in advance.In the 4th embodiment-3, with in the 4th embodiment-1 and the 4th embodiment-2, describe the same, after the aligning battery tension, supply power by power-supply system.In addition, in the 4th embodiment-3, realize following method as follows: when the generation quantity of power of solar cell not simultaneously, charge in batteries at utmost, is prevented the variation of the voltage of storage battery simultaneously in advance.
Figure 29 shows the flow chart of the 4th embodiment-3, and it has described the processing of charging, even the generation quantity of power of solar cell is different, battery tension does not change yet.In the following description, show that the current value of solar cell is explained to simplify, but in the 4th embodiment-3, need not detect this type of current value, and need not arrange current sensor thus.
Figure 30 shows the solar cell output current of three DC power supply strings.The solar cell output current of string S1 is 4A, and string S2 is 2A with the solar cell output current of string S3.
If with the same each battery tension of aiming in the processing of the 4th embodiment-1 and the 4th embodiment-2, then the output of the solar cell of each string all is exported to each storage battery, and goes here and there the storage battery of S1 thus and fill 2A more than the storage battery of other strings.In this case, in the charged state of storage battery, produced difference.
To in Figure 29, describe according to above.At step S11, in this case, confirm whether the voltage of node T is complete charging voltage.If charging voltage, then this flow chart stops.If not complete charging voltage, then calculate X at step S12, and with its value substitution X1.X is output current I1, I2, the maximum of I3 and the value of the difference between the minimum value of storage battery 72a, 72b, 72c.About electric current X1, on the output current I1 of solar cell 71a, maximum current is 4A, and is last at output current I2, the I3 of solar cell 71b, 71c, and minimum current is 2A, and difference X1 is 2A.
At step S13, confirm X1=X2.Like hope ground, X2 is zero for initial value.Because X1 is current is 2A, and X2 is zero, so this processing advances to step S15, and increases the request power of power converter.If increase 1A, then export, and A shown in Figure 30 is offered power converter to the power of the output area of B from the string of big solar cell output.
At step S16, with X1 substitution X2.The data of electric current X1 (2A) are stored among the X2 thus.
This processing turns back to first step S11 then, and whether the voltage of definite node T is complete charging voltage.If not charging fully, then this processing advances to step S12, calculates X once more, and with its value substitution X1.About electric current X1, on the output current I1 of solar cell 71a, maximum current is 3A, and is last at output current I2, the I3 of solar cell 71b, 71c, and minimum current is 2A, and difference X1 is 1A.
At step S13, confirm X1=X2.Because X1 is current is 1A, and X2 is 2A, so this processing advances to step S15, and increases the request power of power converter.If further increase 1A, then export, and A shown in Figure 30 is offered power converter to the power of the output area of C from the string of big solar cell output.
At step S16, with X1 substitution X2.The data of electric current X1 (1A) are stored among the X2 thus.
This processing turns back to first step S11 then, and whether the voltage of definite node T is complete charging voltage.If not charging fully, then this processing advances to step S12, calculates X once more, and with its value substitution X1.About electric current X1, on the output current I1 of 1A solar cell, maximum current is 2A, and last at 2A, the output current I2 of 3A solar cell, I3, minimum current is 2A, and difference X1 is zero.
At step S13, confirm X1=X2.Because X1 is current is zero, and X2 is 1A, so this processing advances to step S15, and increases the request power of power converter.If increase 1A again,,, and equally export by 1/3 thus so solar cell output is in a C (2A) in each string because on current point, export 2A from big solar cell string.As a result, A shown in Figure 30 is offered power converter to the power of the output area of D.
At step S16, with X1 substitution X2.The data of electric current X1 (1A) are stored among the X2 thus.
This processing turns back to first step S11 then, and whether the voltage of definite node T is complete charging voltage.If not charging fully, then this processing advances to step S12, calculates X once more, and with its value substitution X1.About electric current X1, maximum current I1=I2=I3=5/3A, and difference X1 is zero.
At step S13, confirm X1=X2.Because X1 is current is zero, and X2 also is zero, so this processing advances to step S14, and reduces the request power of power converter.
At step S16, with X1 substitution X2.The data of electric current X1 (1A) are stored among the X2 thus.Then, this processing turns back to first step S11, and repeats this flow chart.
In above description, described the behavior under perfect condition, but in fact, when in step S13, confirming X1=X2, tolerance band need be set.
In native system, control makes that basically battery tension does not change, but the following possibility of physical presence: and because moment insolation changes or the like, voltage will have slight variation.In this case, though X should the zone of vanishing in (in Figure 30 under the C), X can vanishing yet.If the output of power converter is maintained in the scope of the present invention's description, then X moves near zero direction.But the variable quantity of the unit interval of this closing speed is less.
In the relatively short time interval, the change in current that generation causes owing to local insolation changes and the output of power converter change.Utilize this difference, when X on duty changed, the variation that can confirm X was because local insolation changes or the output of power converter changes, still because the change in voltage of each storage battery.
In the flow chart of Figure 29, through the acceleration mode transition, can confirm the optimal value of tolerance band, and be provided with the variable quantity of the request power of power converter enough big, just can ignore because storage battery changes the variation of the X that causes.
Preferably, the X that changes owing to storage battery is set to be less than or equal to 1/5 of X that the output adjustment owing to power converter changes, more preferably is less than or equal to 1/20 for being less than or equal to 1/10, being most preferably.If be set to be less than or equal to 1/5, then can utilize error range definite X1=X2 in step S13 of 20%.
According to above processing, even the output of solar cell changes, also can be aligned to the charge power of each storage battery, and can charging be proceeded at utmost, suppress the change in voltage between each storage battery simultaneously.In other words; When connecting n+1 DC power supply string, power converter always ask to be greater than or equal to (I1-Ia)+(I2-Ia)+... quantity of power (In-Ia), wherein Ia is a minimum current; And I1, I2 ... In is the residual current of DC power supply; Thereby the current value of each storage battery is all unified on Ia, and can charging be proceeded at utmost, the change in voltage between each storage battery suppressed simultaneously.
It should be appreciated by those skilled in the art that the present invention can realize by many other concrete forms, and can not break away from spirit of the present invention or scope.Therefore, the details that the invention is not restricted to here provide, and can in the scope of claims and equivalent, make amendment.

Claims (20)

1. power-supply system comprises:
DC power supply string wherein is parallel-connected to the DC power supply with storage battery;
The DC/AC power converter is used for the DC power supply is series-connected to electric power system or load; And
Switch is connected between DC power supply and the storage battery, and be used for switching the power output of DC power supply or the associating power output of DC power supply and storage battery, and offer the DC/AC power converter,
Wherein the DC power supply further comprises time monitoring unit, voltage detection unit or current detecting unit;
When satisfying predetermined condition for one in time monitoring unit, voltage detection unit or the current detecting unit, switch said switch, and
Wherein, said predetermined condition is:
I) when the detection electrorheological of the detection voltage of voltage detection unit or current detecting unit must be greater than or equal to predetermined value; Begin output; Perhaps when the detection electrorheological of the detection voltage of voltage detection unit or current detecting unit must be less than this predetermined value, stop output; Ii), begin output or stop output according to the scheduled time of time monitoring unit; Iii) when the detection electrorheological of the detection voltage of voltage detection unit or current detecting unit must be greater than or equal to said predetermined value, and, begin output or stop output according to said scheduled time of time monitoring unit; And iv) when the detection electrorheological of the detection voltage of voltage detection unit or current detecting unit must be less than or equal to said predetermined value, and, begin output or stop output according to said scheduled time of time monitoring unit.
2. power-supply system as claimed in claim 1, wherein the DC power supply is a solar cell, and DC power supply string is the solar cell string.
3. power-supply system as claimed in claim 2, wherein storage battery has the charging capacity of at least 0.3 hour the power output that solar cell generated of storage.
4. power-supply system as claimed in claim 2; Wherein storage battery is set to the maximum power point voltage (Vpmax) exported with respect to when solar cell is received predetermined insolation amount on predetermined temperature, can obtain to be greater than or equal to 60% and be less than or equal to the voltage range of 100% power.
5. power-supply system comprises:
The solar cell string wherein is parallel-connected to solar cell with storage battery;
The DC/AC power converter is used for solar cell is series-connected to electric power system or load;
The battery status detecting unit is used for detecting the state of storage battery;
Export detecting unit, be used for detecting the power output of DC/AC power converter; And
Output control unit is used for according to the battery condition of battery status detection and the power output of output detection, and the power output of control DC/AC power converter flows to storage battery to prevent overcurrent.
6. power-supply system as claimed in claim 5, one or more in wherein below the battery status detection: the charged state pace of change of the voltage of storage battery, charged state and unit interval.
7. power-supply system as claimed in claim 5 also comprises data storage cell or communication unit, is used for receiving external data, wherein
Data storage cell or communication unit obtain one or more data in following: the prediction insolation amount of past insolation data, average air temperature data, weather forecast or predict the temperature data of air themperature, solar cell, the predicted temperature characteristic of solar cell and the degradation information of storage battery; And
Output control unit is according to said one or more Data Control DC/AC power converter.
8. power-supply system as claimed in claim 5, wherein
Storage battery comprises a plurality of storage batterys; And
The battery status detecting unit comprises: the voltage comparing unit is used for serial number according to the high battery tension of battery status detection; Batteries generates parts, is used for generating batteries according to the order that the high battery tension of voltage comparing unit is numbered; And the first start-up control parts, be used for controlling the DC/AC power converter, make the overall power output that the power output of DC/AC power converter becomes and allows less than from batteries when power-supply system starts.
9. power-supply system as claimed in claim 5, wherein
Storage battery comprises a plurality of storage batterys; And
The battery status detecting unit comprises: the charged state comparing unit is used for serial number according to the big charged state of the storage battery of battery status detection; The charged state batteries generates parts, is used for generating the charged state batteries according to the order of the big charged state of charged state comparing unit numbering; And the second start-up control parts, be used for controlling the DC/AC power converter, make the overall power output that the power output of DC/AC power converter becomes and allows less than from the charged state batteries when power-supply system starts.
10. power-supply system as claimed in claim 5, wherein the solar cell string comprises a plurality of solar cell strings, wherein searches for k the solar cell string that meets the following conditions
(E1-Ei)/r＜ΔImax，
Wherein r is the internal resistance of storage battery; Δ Imax is the distance of the output current and the absolute maximum rated Imax of storage battery; η is the efficient of DC/AC power converter; SB1, SB2 ... SBn be when power-supply system starts by each storage battery of the order of high battery tension, E1, E2 ... En is the electromotive force of each storage battery, I1, I2 ... In is an electric current; And
The control power output makes the power output P of DC/AC power converter become following relational expression
P＜(E1-r×Imax)×(Imax+I2max+...+Ikmax)×η
(Iimax＝Imax×(Ei-(E1-r×Imax))/(E1-r×Imax)，i＝2，3...，k)，
Wherein n is the quantity of solar cell string, and k is smaller or equal to n.
11. power-supply system as claimed in claim 10 wherein begins from starting power-supply system, periodically monitors the voltage of each storage battery, and when k increases, corresponding to the increase of k, increases the output acceptable value of DC/AC power converter.
12. power-supply system as claimed in claim 5; Wherein the solar cell string comprises the charge switch that is used for each storage battery; Be used for: when shining upon,, connect this charge switch and utilize the solar cell of forming the DC power supply to be charge in batteries when the charge volume of storage battery is hour.
13. power-supply system as claimed in claim 2; Comprise a plurality of power-supply devices that comprise DC power supply string and DC/AC power converter that are parallel to electric power system or load; Also comprise: the power transfer control unit is used for controlling the DC/AC power converter according to the power output of DC power supply.
14. power-supply system as claimed in claim 13 also comprises: the memory space detection part is used for the memory space of detection of stored unit, the memory space that detects according to the memory space detection part of power transfer control unit wherein, control DC/AC power converter.
15. power-supply system as claimed in claim 13; Also comprise: power output amount detection part; Be used for detecting the power output amount of power-supply system, wherein the power transfer control unit is controlled the DC/AC conversion equipment according to the power output amount of power output amount detection part detection.
16. a power-supply system comprises:
A plurality of DC power supply strings wherein are parallel-connected to the DC power supply with storage battery;
The DC/AC power converter is used for said a plurality of DC power supplys are series-connected to electric power system or load;
The storage battery control unit is used for controlling the DC/AC power converter, thereby makes each battery tension become equal basically;
The battery status detecting unit is used for detecting the state of storage battery;
Export detecting unit, be used for detecting the power output of DC/AC power converter; And
Output control unit is used for according to the battery condition of battery status detection and the power output of output detection, and the power output of control DC/AC power converter flows to storage battery to prevent overcurrent.
17. power-supply system as claimed in claim 16 also comprises:
The battery current detecting unit is used for detecting the output current of each storage battery; Wherein
Through the battery current detecting unit, control storage battery control unit, thus make each battery tension become equal basically.
18. power-supply system as claimed in claim 16; Wherein the storage battery control unit control make before DC/AC power converter power output, on each scheduled time or according to fixed distance, or when battery tension reached predetermined voltage, it is equal basically that each battery tension becomes.
19. the control method of a power-supply system, this power-supply system comprises: a plurality of DC power supply strings wherein are parallel-connected to the DC power supply with storage battery; And the DC/AC power converter, be used for said a plurality of DC power supplys are series-connected to electric power system or load, said method comprising the steps of:
First handles, and detects the state of storage battery;
Second handles, and detects the power output of DC/AC power converter; And
The 3rd handles, and according to the battery condition of battery status detection and the power output of output detection, the power output of control DC/AC power converter flows to storage battery to prevent overcurrent;
The reason everywhere, the voltage of controlling each storage battery makes it equal basically;
The 5th handles, from DC/AC power converter power output.
20. the control method of power-supply system as claimed in claim 19; Also comprise: the 3rd handles; Wherein when the output that connects n+1 DC power supply string and each DC power supply not simultaneously; Control make the DC/AC power converter always ask to be greater than or equal to (I1-Ia)+(I2-Ia)+... power output (In-Ia), wherein Ia is a minimum current, and I1, I2 ... In is the electric current of the residue DC power supply of DC power supply.
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