CN110212580B - Island control method and system suitable for solar energy storage power generation system - Google Patents
Island control method and system suitable for solar energy storage power generation system Download PDFInfo
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J3/00—Circuit arrangements for ac mains or ac distribution networks
- H02J3/28—Arrangements for balancing of the load in a network by storage of energy
- H02J3/32—Arrangements for balancing of the load in a network by storage of energy using batteries with converting means
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J3/00—Circuit arrangements for ac mains or ac distribution networks
- H02J3/38—Arrangements for parallely feeding a single network by two or more generators, converters or transformers
- H02J3/388—Islanding, i.e. disconnection of local power supply from the network
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- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
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Abstract
Firstly, obtaining the inversion output power and the load power of an inverter, then, adjusting the inversion output power according to the preset logic, the inversion output power and the load power so as to enable the load end voltage to be abnormal along with the adjustment of the inversion output power when the island occurs, and finally, disconnecting a commercial power relay when detecting that the load end voltage is abnormal so as to realize the disconnection of the commercial power and the solar power generation system. According to the energy positive feedback mode, when the mains supply is lost, the voltage of the load end is quickly avalanche to trigger the abnormal protection disconnection of the power grid and the connection between the power grid, the influence of the wide working mains supply frequency range and the large mains supply voltage fluctuation of the solar energy storage power generation system is avoided, and the island control of the solar energy storage power generation system is realized.
Description
Technical Field
The invention relates to the field of power electronics, in particular to an island control method and system suitable for a solar energy storage power generation system.
Background
The solar grid-connected power generation system converts solar energy into electric energy, and directly transmits the electric energy to a power grid through a grid-connected inverter without energy storage of a storage battery. The grid connection is that the grid connection is connected to a public power grid, namely that solar power generation, a household power grid and the public power grid are connected together, and the grid connection is a power generation system which can only operate by depending on the existing power grid. The solar energy power generation system mainly comprises a solar cell panel and an inverter, wherein the solar cell panel directly converts 220V alternating current generated by the inverter into power for household appliances, and when the generated energy of solar energy exceeds the electric quantity used by the household appliances, redundant power is transmitted to a public power grid; and when the generated energy of the solar energy cannot meet the use requirement of the household appliances, the generated energy is automatically supplemented from the power grid.
When the load is matched with the solar inverter, the inverter cannot judge that the power grid is lost and cuts off the inverter from the power grid, so that an isolated system is formed to supply power to the load, and an isolated island is formed. The islanding effect means that when the power grid is interrupted due to an electrical fault, a natural factor or misoperation, the photovoltaic power generation system of each user side does not timely detect the power failure state and is separated from the commercial power grid, the photovoltaic power generation system continuously keeps transmitting electric energy to the power grid, meanwhile, an independent self-sufficient power supply islanding which cannot be controlled by the public power grid is formed with a load, and the formed system is called an islanding system.
In order to solve the problem that the islanding causes great potential danger to power supply systems and maintenance personnel, the traditional islanding control comprises an active islanding control system and a passive islanding control system.
According to the passive island detection method, after the island detection characteristic quantity is selected, the island detection characteristic quantity is not disturbed, island identification is carried out by analyzing the transient steady state change of the detection characteristic quantity before and after the island occurs, and adverse effects on power quality caused by the use of the island detection method are avoided. The passive detection method does not need to be implanted into a control strategy of the distributed power generation system, and has good adaptability to various distributed power generation systems with different topological structures and control strategies. Passive island detection utilizes electric quantity such as high frequency/low frequency, high pressure/low pressure to judge whether the island appears, because of among the solar energy storage power generation system, the frequency and voltage of commercial power input is very wide, consequently with passive island detection be applied to solar energy storage power generation system in, there is the detection blind area, easily the hourglass to examine.
The active island detection method is to introduce a certain regular disturbance signal (such as current amplitude, frequency and phase) to the output of a photovoltaic inverter to judge whether an island effect occurs. When the power grid normally works and the photovoltaic inverter operates in a grid-connected mode, due to the clamping effect of the power grid, the introduced disturbance signals can hardly change the power grid; when the grid is broken down, when the photovoltaic inverter operates in an isolated island mode, introduced disturbance quantity can be accumulated continuously, and once the disturbance quantity exceeds an allowable range, an isolated island effect can be detected. Active island detection, which is currently and commonly used, is to judge an island by changing the frequency of the output of an inverter in a scrambling mode, a phase shifting mode and other modes. Because of in the solar energy storage power generation system, the frequency voltage of commercial power input is very wide, consequently with active island detection application in the solar energy storage power generation system, detection time is longer, produces the island easily or produces the phase shift and lead to the product to damage after the commercial power resumes. Therefore, for the solar energy storage power generation system, the working mains supply frequency range of the solar energy storage power generation system is wider, and the mains supply voltage fluctuation is larger, so that the traditional island control system cannot meet the requirement of the solar energy storage power generation system.
An island control technology suitable for a solar grid-connected power generation system is urgently needed.
Disclosure of Invention
The invention mainly solves the technical problems that the solar energy storage power generation system has wider working mains supply frequency range and larger mains supply voltage fluctuation, and an island control scheme which can be suitable for the solar energy storage power generation system is required to be provided in island control of the solar energy storage power generation system which is inapplicable to active island detection and passive island detection.
According to a first aspect, an embodiment provides an island control method suitable for a solar energy storage power generation system, including:
acquiring the inversion output power and the load power of an inverter;
adjusting the inversion output power according to preset logic, the inversion output power and the load power so as to enable the load terminal voltage to be abnormal along with the adjustment of the inversion output power when an island occurs;
and when the voltage at the load end is detected to be abnormal, the mains supply relay is disconnected, and the mains supply is separated from the solar power generation system.
In another embodiment, the adjusting the inverter output power according to the preset logic, the inverter output power and the load power to make the load terminal voltage abnormal along with the adjustment of the inverter output power when the islanding occurs includes:
according to preset logic, the inversion output power and the load power, reducing the current inversion output power cycle by cycle so that the load terminal voltage is reduced along with the reduction of the inversion output power when an island occurs, wherein the preset logic comprises that the current inversion output power is smaller than the current load power;
and detecting that the voltage of the load end is reduced along with the reduction of the inversion output power, wherein the voltage of the load end is smaller than a preset normal commercial power threshold value until the voltage of the load end is abnormal.
In another embodiment, further comprising:
and adjusting the inverter to be converted into an off-grid mode, so as to supply power to a load end.
In another embodiment, the preset logic further comprises: the current inversion output power is smaller than the current load power, and a value obtained by subtracting the inversion output power from the load power is within a preset range, wherein the preset range comprises a maximum value and a minimum value.
In another embodiment, further comprising:
when the value obtained by subtracting the inversion output power from the load power is judged to be smaller than the minimum value, detecting whether the load end voltage is smaller than the preset normal commercial power threshold value;
judging whether the inverter works at the maximum solar power point or not when the value obtained by subtracting the inversion output power from the load power is not less than the maximum value;
when the inverter is judged to work at the maximum solar power point, detecting whether the voltage of the load end is smaller than the preset normal commercial power threshold value;
when the inverter does not work at the maximum solar power point, judging whether the value obtained by subtracting the inverter output power from the load power is larger than the minimum value or not;
when the value obtained by subtracting the inversion output power from the load power is larger than the minimum value, detecting whether the load end voltage is smaller than the preset normal commercial power threshold value;
when the value obtained by subtracting the inversion output power from the load power is judged to be not less than the minimum value, the inversion output power is increased;
and when the load end voltage is not less than the preset normal commercial power threshold value, the inverter is in a grid-connected combined load mode.
According to a second aspect, an embodiment provides an island control system suitable for a solar energy storage power generation system, including: the system comprises a load detection module, a mains supply relay connected with the mains supply module, a solar power generation system for realizing solar power supply, an inversion detection module connected with the solar power generation system and a control module respectively connected with the inversion detection module, the load detection module and the mains supply relay;
the inversion detection module is used for detecting the output voltage and current of an inverter in the solar module so as to provide the output voltage and current for the control module to calculate inversion output power;
the load detection module is used for detecting the output voltage and current of the load so as to provide the output voltage and current for the control module to calculate the load power;
the control module is used for adjusting the inversion output power according to preset logic, the inversion output power and the load power so as to enable the load end voltage to be abnormal along with the adjustment of the inversion output power when an island occurs, and outputting a control instruction when the load end voltage is detected to be abnormal;
and the commercial power relay is used for receiving a control instruction of the control module to disconnect the commercial power from the solar power generation system.
According to a third aspect, an embodiment provides a computer-readable storage medium, which includes a program, where the program is executable by a processor to implement the islanding control method for a solar energy storage power generation system as described in any above.
The beneficial effect of this application:
the application provides a be applicable to solar energy storage power generation system's island control method, at first, acquire the contravariant output power and the load power of dc-to-ac converter, then, according to predetermined logic contravariant output power with load power adjusts contravariant output power to make the load terminal voltage along with the regulation of contravariant output power appears unusually when the island takes place, and finally, when detecting load terminal voltage anomaly, with commercial power relay disconnection, realize commercial power and solar electric system's cut-off. Under the condition of combined load, when commercial power is lost, energy required by the load is provided only by solar energy through an inversion link, at the moment, inversion output power is the same as load power, then the inversion output power and the load power of an inverter are adjusted according to preset logic, the inversion output power is obtained, the load power changes along with the inversion output power, when an island occurs, the load end voltage is abnormal along with the adjustment of the inversion output power, finally, when the load end voltage is detected to be abnormal, a commercial power relay is disconnected, the commercial power is separated from a solar power generation system, namely, according to an energy positive feedback mode, the load end voltage is quickly avalanche, the abnormal protection disconnection of the power grid and the connection of the power grid are triggered, the island control of the solar energy storage power generation system is realized without the influence of wide working commercial power frequency range and large commercial power voltage fluctuation of the solar energy storage power generation system.
The invention provides an island control system suitable for a solar energy storage power generation system, which comprises: the system comprises a load detection module, a mains supply relay connected with the mains supply module, a solar power generation system for realizing solar power supply, an inversion detection module connected with the solar power generation system and a control module respectively connected with the inversion detection module, the load detection module and the mains supply relay; the inversion detection module is used for detecting the output voltage and current of an inverter in the solar module so as to provide the output voltage and current for the control module to calculate inversion output power; the load detection module is used for detecting the output voltage and current of the load so as to provide the output voltage and current for the control module to calculate the load power; the control module is used for adjusting the inversion output power according to preset logic, the inversion output power and the load power so as to enable the voltage of the load end to be abnormal along with the adjustment of the inversion output power when an island occurs, and outputting a control instruction when the voltage of the load end is detected to be abnormal; and the commercial power relay is used for receiving a control instruction of the control module to disconnect the commercial power from the solar power generation system. According to the energy positive feedback mode, the load terminal voltage is quickly avalanche to trigger the abnormal protection disconnection of the power grid and the connection between the power grid, the influence of the wide working mains supply frequency range and the large mains supply voltage fluctuation of the solar energy storage power generation system is avoided, and the island control of the solar energy storage power generation system is realized.
Drawings
Fig. 1 is a schematic diagram of an island control system suitable for a solar energy storage power generation system according to a first embodiment of the present invention;
fig. 2 is a schematic diagram of another island control system suitable for a solar energy storage power generation system according to a first embodiment of the present invention;
fig. 3 is a schematic flow chart of an island control method applicable to a solar energy storage power generation system according to a second embodiment of the present invention;
fig. 4 is a schematic flow chart of another island control method suitable for a solar energy storage power generation system according to a second embodiment of the present invention;
fig. 5 is a schematic flow chart of another island control method suitable for a solar energy storage power generation system according to a second embodiment of the present invention.
Detailed Description
The present invention will be described in further detail with reference to the following detailed description and accompanying drawings. Wherein like elements in different embodiments are numbered with like associated elements. In the following description, numerous details are set forth in order to provide a better understanding of the present application. However, those skilled in the art will readily recognize that some of the features may be omitted or replaced with other elements, materials, methods in different instances. In some instances, certain operations related to the present application have not been shown or described in detail in order to avoid obscuring the core of the present application from excessive description, and it is not necessary for those skilled in the art to describe these operations in detail, so that they may be fully understood from the description in the specification and the general knowledge in the art.
Furthermore, the features, operations, or characteristics described in the specification may be combined in any suitable manner to form various embodiments. Also, the various steps or actions in the method descriptions may be transposed or transposed in order, as will be apparent to one of ordinary skill in the art. Thus, the various sequences in the specification and drawings are for the purpose of describing certain embodiments only and are not intended to imply a required sequence unless otherwise indicated where such sequence must be followed.
The numbering of the components as such, e.g., "first", "second", etc., is used herein only to distinguish the objects as described, and does not have any sequential or technical meaning. The term "connected" and "coupled" when used in this application, unless otherwise indicated, includes both direct and indirect connections (couplings).
Example one
Referring to fig. 1, fig. 1 is a schematic diagram of an island control system suitable for a solar energy storage power generation system according to an embodiment of the present invention.
The utility model provides an island control system suitable for solar energy storage power generation system, including load detection module 01, commercial power module 02, with utility power relay 03 that commercial power module 02 connects, be used for realizing solar energy power supply's solar power generation system 04, with the contravariant detection module 05 that solar power generation system 04 connects and respectively with contravariant detection module 05 load detection module 01 control module 06 that utility power relay 03 connects, the following concrete description.
The inversion detection module 05 is configured to detect an output voltage and a current of an inverter in the solar module, so as to provide the detected output voltage and current to the control module 06 for calculating an inversion output power;
the load detection module 01 is configured to detect an output voltage and a current of the load 07, so as to provide the output voltage and the current to the control module 06 for calculating a load power;
the control module 06 is configured to adjust the inverter output power according to preset logic, the inverter output power, and the load power, so that when an island occurs, a load end voltage becomes abnormal along with adjustment of the inverter output power, and when the load end voltage is detected to be abnormal, a control instruction is output;
and the mains supply relay 03 is used for receiving a control instruction of the control module 06 to disconnect the mains supply from the solar power generation system 04.
In the embodiment of the invention, the solar energy storage power generation system converts solar energy into electric energy, and the electric energy is directly transmitted to the electric solar power generation system 04 network through the energy storage inverter without energy storage of a storage battery.
In the embodiment of the present invention, the solar power generation system 04 generally includes a solar panel, an inverter, and an ac power distribution cabinet. The solar panel is a core part in the solar power generation system 04, and the solar panel is used for converting solar light energy into electric energy and outputting direct current to be stored in the storage battery. Photovoltaic power generation depends on a solar cell module, utilizes the electronic characteristics of a semiconductor material, when sunlight irradiates on a semiconductor PN junction, as a P-N junction barrier region generates a stronger built-in electrostatic field, unbalanced electrons and holes generated in the barrier region or unbalanced electrons and holes generated outside the barrier region but diffused into the barrier region respectively move in opposite directions under the action of the built-in electrostatic field and leave the barrier region, so that the potential of the P region is increased, the potential of the N region is reduced, voltage and current are generated in an external circuit, and light energy is converted into electric energy. The inverter is a dc/ac inverter, and is a device that converts dc power to ac power. Since the solar battery generates dc power and the general load is an ac load, an inverter solar inverter diagram is indispensable. The inverter may be divided into an independent operation inverter and a grid-connected inverter according to an operation mode. The independent operation inverter is used for an independent operation solar cell power generation system and supplies power for an independent load. The grid-connected inverter is used for feeding the generated electric energy into a power grid by the solar cell power generation system in grid-connected operation. The inverter can be divided into a square wave inverter and a sine wave inverter according to the output waveform. The direct output of solar energy is generally current-type output, and can be directly connected in parallel and in series to form different direct current outputs. In order to supply electric power to 220VAC appliances, DC power generated by the solar power system 04 needs to be converted into AC power, and therefore a DC-AC inverter needs to be used. The main function of the alternating current power distribution cabinet in a power station system is the switching function of a standby inverter, the normal power supply of the system is guaranteed, and meanwhile, the metering of the circuit electric energy is realized.
In the embodiment of the present invention, the inverter detection module 05 is configured to detect the power output by the inverter, obtain the voltage and the current output by the inverter, and input the detected voltage and current to the control module 06, so as to calculate the output power of the inverter according to the voltage and the current.
In the embodiment of the present invention, the load detection module 01 detects a voltage and a current at the load 07 end to calculate the load power according to the voltage and the current. For example, the voltage and current input to the load may be detected at the input of the load 07, and the detected voltage and current may be input to the control module 06 to calculate the load power.
In the embodiment of the present invention, the utility power module 02 is used for providing utility power to the load 07, which is another power supply source besides the too-energy power supply.
In the embodiment of the present invention, the utility relay 03 is an electric control device, and is an electric appliance that generates a predetermined step change in a controlled amount in an electric output circuit when a change in an input amount (excitation amount) meets a predetermined requirement. It has an interactive relationship between a control system (also called an input loop) and a controlled system (also called an output loop). It is commonly used in automated control circuits, which are actually a "recloser" that uses low current to control high current operation. Therefore, the circuit plays the roles of automatic regulation, safety protection, circuit conversion and the like. And receiving a control signal of the control module 06, and disconnecting the commercial power module 02 from the solar energy storage power generation system.
In an embodiment of the present invention, the control module 06 includes a main control chip and a signal conversion circuit, and is configured to receive data of the inverter detection module 05 and the load detection module 01, adjust the inverter output power according to preset logic, the inverter output power, and the load power, so that when an islanding occurs, a load terminal voltage is abnormal along with adjustment of the inverter output power, and when the load terminal voltage is detected to be abnormal, output a control instruction, so that the utility power relay 03 is configured to receive the control instruction of the control module 06 to disconnect connection between the utility power and the solar power generation system 04.
For example, referring to fig. 2, fig. 2 is a schematic diagram of another islanding control system suitable for a solar energy storage power generation system according to a first embodiment of the present invention. Solar panel converts solar energy input into electric energy output, through two-way DCtoDC module with electric energy storage in the battery, two-way DCtoDC module is exactly direct current commentaries on classics direct current module, and it can be step-down module also can be step-up module or both combine, the purpose of two-way DCtoDC module is exactly for the voltage of adaptation solar energy output and the voltage of battery. The inverter converts direct current output by solar energy into alternating current and supplies power to a load, the output end of the inverter is connected with an inversion detection module 05 to detect the output power of the inverter, the load detection detects the power of the load, the utility power module 02 supplies power to the load through the utility power relay 03, when the utility power relay 03 is disconnected, the utility power cannot supply power to the load, and when the utility power relay 03 is closed, the utility power supplies power to the load. The commercial power module 02 is connected with the control module 06, and output control of commercial power can be achieved. The control module 06 is connected to the inversion detection module 05 and the load detection module 01, and configured to adjust the inversion output power according to a preset logic, the inversion output power and the load power, so that when an island occurs, a load terminal voltage is abnormal along with adjustment of the inversion output power, and when the load terminal voltage is detected to be abnormal, a control instruction is output, so that the utility power relay 03 is configured to receive the control instruction of the control module 06 to disconnect the utility power from the solar power generation system 04.
Example two
The embodiment of the invention provides an island control method suitable for a solar energy storage power generation system. Referring to fig. 3, fig. 3 is a schematic flow chart of an island control method suitable for a solar energy storage power generation system according to a second embodiment of the present invention. The method includes steps S11 to S13, which are described in detail below.
And S11, acquiring the inversion output power and the load power of the inverter.
In the embodiment of the present invention, the control module may obtain the inversion output power output by the inverter according to the inversion detection module, and may obtain the power of the load end according to the load detection module.
And S12, adjusting the inversion output power according to preset logic, the inversion output power and the load power so as to enable the voltage of the load end to be abnormal along with the adjustment of the inversion output power when an island occurs.
In the embodiment of the present invention, referring to fig. 4, step S12 includes steps S21 to S22, which will be described in detail below.
And S21, reducing the current inversion output power cycle by cycle according to preset logic, the inversion output power and the load power, so that the load end voltage is reduced along with the reduction of the inversion output power when the island occurs, wherein the preset logic comprises that the current inversion output power is smaller than the current load power.
In the embodiment of the invention, the output current of the inverter is reduced cycle by cycle, so that the obtained energy of the load end is reduced, and the voltage of the load end is abnormal.
And S22, detecting that the voltage of the load end is reduced along with the reduction of the inversion output power, wherein the voltage of the load end is smaller than a preset normal commercial power threshold value until the voltage of the load end is abnormal.
In the embodiment of the invention, when the load end voltage is less than the normal commercial power threshold range, the commercial power is judged to be lost, and the load end voltage is determined to be abnormal.
And S13, when the load end voltage is detected to be abnormal, disconnecting the commercial power relay to realize the separation of the commercial power and the solar power generation system.
In the embodiment of the present invention, the method further includes:
and adjusting the inverter to be converted into an off-grid mode, so as to supply power to a load end.
After the mains supply is separated from the solar power generation system through the mains supply relay, the system load is supplied with power by the solar power generation system, and the solar power generation system is in an off-grid mode and converts solar energy into electric energy to directly supply power to the load.
Specifically, when the utility power is normal, the control module is utilized, the inverter adopts current control at the moment, namely, the output current of the inverter is controlled to be a sine wave with the same frequency and phase as the utility power, the inversion output power is calculated by utilizing sampling of inversion output voltage and current, the inversion output current is changed by controlling the modulation waveform of the inversion output so as to adjust the inversion output power P2, the inversion output power P2 is smaller than the load power P1, the difference value between the inversion output power P1 and the load power P1 is within a range, and the delta P1 is less than P1-P2 and less than the delta P2, wherein the delta P1 and the delta P2 are set values according to actual conditions. At the moment, insufficient energy is provided for the load by the commercial power, the commercial power and the solar energy are jointly loaded, and the inverter is in a grid-connected joint loading mode.
Under the condition of combined load, when the commercial power is lost, the energy required by the load is provided by solar energy through an inversion link, and the inversion output power is the same as the load power. According to the set logic (the inversion output power is less than the load power), therefore, the control module adjusts the driving waveform of the inversion link one by one according to the actual sampling condition, reduces the output current waveform, further reduces the output inversion output power, the energy of the load end is reduced cycle by cycle, and according to the set logic, the inversion output power is less than the load power, therefore, the inversion output power can be reduced cycle by cycle of the mains power, and the energy of the load end is reduced cycle by cycle. The positive feedback is formed through the process, so that the energy of the load end has an avalanche accumulation effect, the voltage of the load end further generates avalanche, the voltage of the load end exceeds the range of normal commercial power, the commercial power is judged to be lost, the commercial power relay is disconnected, the commercial power is disconnected from the inversion link, the inverter is converted into an off-grid mode, and the load is normally supplied with power.
In this embodiment of the present invention, the preset logic further includes: the current inversion output power is smaller than the current load power, and a value obtained by subtracting the inversion output power from the load power is within a preset range, wherein the preset range comprises a maximum value and a minimum value.
In the embodiment of the present invention, referring to fig. 5, the method further includes:
when the value obtained by subtracting the inversion output power from the load power is judged to be smaller than the minimum value, detecting whether the load end voltage is smaller than the preset normal commercial power threshold value;
judging whether the inverter works at the maximum solar power point or not when the value obtained by subtracting the inversion output power from the load power is not less than the maximum value;
when the inverter is judged to work at the solar maximum power point, detecting whether the voltage of the load end is smaller than the preset normal commercial power threshold value;
when the inverter does not work at the maximum solar power point, judging whether the value obtained by subtracting the inverter output power from the load power is larger than the minimum value or not;
when the value obtained by subtracting the inversion output power from the load power is larger than the minimum value, detecting whether the load end voltage is smaller than the preset normal commercial power threshold value;
when the value obtained by subtracting the inversion output power from the load power is judged to be not less than the minimum value, the inversion output power is increased;
and when the load end voltage is not less than the preset normal commercial power threshold value, the inverter is in a grid-connected combined load mode.
In the embodiment of the invention, when the delta P1< P1-P2< deltaP 2 is not satisfied, the inversion output current needs to be adjusted, and the inversion output power is changed. Whether the solar energy works at the maximum power point of the solar energy can be judged according to the MPPT algorithm of the solar energy. When the solar energy does not work at the maximum solar power point, the redundant energy is provided outwards and can be provided for the load. And when the solar energy does not work at the maximum solar energy power point, increasing the reference value of the output current and adjusting the output modulation duty ratio. The output current is increased, the output power is increased, and the solar energy is utilized to supply power to the load as much as possible.
The embodiment of the invention has the following characteristics:
firstly, acquiring inversion output power and load power of an inverter, then adjusting the inversion output power according to preset logic, the inversion output power and the load power so as to enable the voltage of a load end to be abnormal along with the adjustment of the inversion output power when an island occurs, and finally disconnecting a mains supply relay when detecting that the voltage of the load end is abnormal so as to realize the disconnection between a mains supply and a solar power generation system. Under the condition of combined load, when commercial power is lost, energy required by the load is provided only by solar energy through an inversion link, at the moment, inversion output power is the same as load power, then the inversion output power and the load power of the inverter are adjusted according to preset logic, the inversion output power is obtained, the load power changes along with the inversion output power, when an island occurs, the load end voltage is abnormal along with the adjustment of the inversion output power, finally, when the load end voltage is detected to be abnormal, the commercial power relay 03 is disconnected, the commercial power is separated from the solar power generation system, namely, according to an energy positive feedback mode, the load end voltage quickly avalanche triggers the abnormal protection disconnection of the power grid and the connection between the power grid, the solar energy storage power generation system is not influenced by the wide working commercial power frequency range and the large commercial power voltage fluctuation, and the island control of the solar energy storage power generation system is realized. The abnormal commercial power needs to cut off inverter and commercial power, avoids the energy that the contravariant rises to get into the electric wire netting, causes the injury to maintenance personal. When the mains supply is lost, the working mode of the inverter is switched into a voltage source by the current source, a sine wave voltage is output outwards, power is supplied to the load, and power supply safety is guaranteed. Under the condition that the inverter works in a voltage source, the commercial power is not cut, the commercial power is recovered, and the short circuit with the inverter is directly caused, so that the inverter is damaged.
Those skilled in the art will appreciate that all or part of the functions of the various methods in the above embodiments may be implemented by hardware, or may be implemented by computer programs. When all or part of the functions of the above embodiments are implemented by a computer program, the program may be stored in a computer-readable storage medium, and the storage medium may include: a read only memory, a random access memory, a magnetic disk, an optical disk, a hard disk, etc., and the program is executed by a computer to realize the above functions. For example, the program may be stored in a memory of the device, and when the program in the memory is executed by the processor, all or part of the functions described above may be implemented. In addition, when all or part of the functions in the above embodiments are implemented by a computer program, the program may be stored in a storage medium such as a server, another computer, a magnetic disk, an optical disk, a flash disk, or a removable hard disk, and may be downloaded or copied to a memory of a local device, or may be version-updated in a system of the local device, and when the program in the memory is executed by a processor, all or part of the functions in the above embodiments may be implemented.
The present invention has been described in terms of specific examples, which are provided to aid understanding of the invention and are not intended to be limiting. For a person skilled in the art to which the invention pertains, several simple deductions, modifications or substitutions may be made according to the idea of the invention.
Claims (3)
1. An island control method suitable for a solar energy storage power generation system is characterized by comprising the following steps:
acquiring the inversion output power and the load power of an inverter;
according to preset logic, the inversion output power and the load power, reducing the current inversion output power cycle by cycle to reduce the load end voltage along with the reduction of the inversion output power when an island occurs, wherein the preset logic comprises that the current inversion output power is smaller than the current load power;
detecting that the voltage of the load end is reduced along with the reduction of the inversion output power, wherein the voltage of the load end is smaller than a preset normal commercial power threshold value until the voltage of the load end is abnormal;
when the voltage of the load end is detected to be abnormal, the commercial power relay is disconnected, and the commercial power is separated from the solar power generation system;
adjusting the inverter to be converted into an off-grid mode, and realizing power supply to a load end; the preset logic further comprises: the current inversion output power is smaller than the current load power, and the value obtained by subtracting the inversion output power from the load power is within a preset range, wherein the preset range comprises a maximum value and a minimum value;
when the value obtained by subtracting the inversion output power from the load power is judged to be smaller than the minimum value, detecting whether the load end voltage is smaller than the preset normal commercial power threshold value;
judging whether the inverter works at the maximum solar power point or not when the value obtained by subtracting the inversion output power from the load power is not less than the maximum value;
when the inverter is judged to work at the solar maximum power point, detecting whether the voltage of the load end is smaller than the preset normal commercial power threshold value;
when the inverter does not work at the maximum solar power point, judging whether the value obtained by subtracting the inverter output power from the load power is larger than the minimum value or not;
when the value obtained by subtracting the inversion output power from the load power is larger than the minimum value, detecting whether the load end voltage is smaller than the preset normal commercial power threshold value;
when the value obtained by subtracting the inversion output power from the load power is judged to be not less than the minimum value, the inversion output power is increased;
and when the load end voltage is not less than the preset normal commercial power threshold value, the inverter is in a grid-connected combined load mode.
2. An island control system suitable for a solar energy storage power generation system, for applying the island control method of claim 1, the island control system comprising: the system comprises a load detection module, a mains supply relay connected with the mains supply module, a solar power generation system for realizing solar power supply, an inversion detection module connected with the solar power generation system and a control module respectively connected with the inversion detection module, the load detection module and the mains supply relay;
the inversion detection module is used for detecting the output voltage and current of an inverter in the solar power generation system so as to provide the output voltage and current for the control module to calculate inversion output power;
the load detection module is used for detecting the output voltage and current of the load so as to provide the output voltage and current for the control module to calculate the load power;
the control module is used for adjusting the inversion output power according to preset logic, the inversion output power and the load power so as to enable the load end voltage to be abnormal along with the adjustment of the inversion output power when an island occurs, and outputting a control instruction when the load end voltage is detected to be abnormal;
and the commercial power relay is used for receiving a control instruction of the control module to disconnect the commercial power from the solar power generation system.
3. A computer-readable storage medium, comprising a program executable by a processor to implement the method of claim 1.
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| CN111525524B (en) * | 2020-05-13 | 2022-05-24 | 国网山西省电力公司电力科学研究院 | Relay protection method for distributed photovoltaic access power distribution network |
| CN112383055B (en) * | 2020-11-24 | 2022-12-09 | 珠海格力电器股份有限公司 | Grid-connected and off-grid scheduling method and device and energy storage air conditioning system |
| CN113258557B (en) * | 2021-04-16 | 2022-08-12 | 国网浙江省电力有限公司丽水供电公司 | Standby power supply system and method for high mountain communication station |
| CN113659619B (en) * | 2021-08-04 | 2023-07-18 | 江苏阿诗特能源科技股份有限公司 | Energy storage system and current detection module self-identification method |
| CN115800368A (en) * | 2022-11-30 | 2023-03-14 | 国网江苏省电力有限公司南通供电分公司 | New energy power generation system |
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