JP3857750B2 - Grid-connected power supply system and power supply system - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a grid-connected power supply system and a power supply system in which a solar cell and a voltage detection current control type inverter and a single-phase three-wire distribution line are connected, and particularly when the connection is released, the inverter The present invention relates to a power supply system configured to operate independently.
[0002]
[Prior art]
In recent years, a grid-connected power supply system in which a solar cell is linked to a single-phase three-wire commercial power system via an inverter device and supplies the generated power of the solar cell to a load such as a home appliance has been put into practical use. (Japanese Patent Laid-Open No. 5-308780).
[0003]
For example, six solar cell modules that output a DC voltage of about 30 V are connected in series to 180 V, and this is converted to AC 100 V single-phase AC power by an inverter device using this as an input voltage. Connect to R phase or T phase.
[0004]
[Problems to be solved by the invention]
In a conventional grid-connected power supply system, a grid protection device is provided for disconnecting the inverter device from the commercial power system when an abnormality or a power failure occurs in the commercial power system. The interconnection protection device quickly detects a power failure or abnormality, opens the switch within a specified time, disconnects the inverter device from the commercial power system, and simultaneously stops the operation of the inverter device.
[0005]
Therefore, when an abnormality or a power failure occurs, the generated power of the solar battery is not used, and there is a problem in terms of effective use of sunlight.
The present invention has been made in view of the above-described problems. When the connection between the commercial power system and the inverter is released, the inverter can be operated independently, and the generated power of the solar cell can be effectively used. An object is to provide a grid-connected power supply system and a power supply system that can be used.
[0006]
[Means for Solving the Problems]
  In the system according to the first aspect of the present invention, a plurality of voltage detection current control type inverters for converting DC power output from a solar cell into AC power are connected to a distribution line, and the distribution line and the commercial power system are connected. A grid-connected power supply system configured to connect the inverter and the commercial power system by being connected via a system protection device, the link protection device comprising: a system abnormality detection circuit; A switch is configured to release the interconnection by the switch when an abnormality of the commercial power system is detected by the system abnormality detection circuit, and the interconnection is released by the switch Sometimes, a voltage and frequency signal of the same type as the commercial power system is applied to the distribution line.GenerateA reference signal supply unit to be supplied, and an overall control unit for providing a command signal for controlling the output voltage or output current to be output to the inverter are provided.
[0007]
  The system according to a second aspect of the present invention provides a signal of the same voltage and frequency as that of the commercial power system to the distribution line when the interconnection is released by the switch.GenerateA reference signal supply unit to be supplied, a secondary battery, a charger connected to the distribution line so as to charge at least the secondary battery when the interconnection is released, and the interconnection is released Sometimes, an overall control unit is provided for giving a command signal for controlling the output current to be output to each inverter.
[0008]
In the system according to the invention of claim 3, the general control unit detects the input current and the input voltage input to the charger and controls the command signal to control the input voltage so as not to exceed a predetermined value. Is configured to output.
[0009]
In the system according to claim 4, the overall control unit detects a charging current to the secondary battery, and outputs the command signal for controlling the charging current so as not to exceed an appropriate value. Configured as follows.
[0010]
  The system according to the invention of claim 5 is provided with a second inverter having the secondary battery as an input power source..
[0011]
The reference signal supply unit supplies a signal having the same voltage and frequency as those of the commercial power system to the inverter via the distribution line. For example, when the inverter outputs to a single-phase three-wire R phase or T phase, 100 V of single phase 50/60 Hz is supplied. The inverter detects the reference signal supplied from the reference signal supply unit, and outputs a current having the same frequency.
[0012]
The overall control unit controls the output current or output voltage of the inverter so that the charger charges the secondary battery without overcharging. For example, when the terminal voltage of the secondary battery increases due to charging, a command signal is given to decrease the output current of the inverter. In addition, a command signal for controlling the output current of the inverter is provided so that the input voltage to the charger does not exceed the allowable value.
[0013]
The second inverter operates using the secondary battery as a power source, and outputs, for example, commercial AC power. As the secondary battery, for example, a fuel cell or a storage battery is used.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
1 is a block diagram showing a circuit of a grid-connected power supply system 1 according to the present invention, FIG. 2 is an overview diagram of an AC module 5, FIG. 3 is a block diagram showing a circuit of the AC module 5, and FIG. FIG. 5 is a block diagram for explaining the connection state, FIG. 5 is a diagram for explaining the connection state of the AC module 5, and FIG. 6 is a diagram showing the arrangement state of the AC module 5.
[0015]
In FIG. 1, a grid-connected power supply system 1 includes a single-phase three-wire distribution line 3, a grid protection device 4, AC modules 5a, 5b, 5c,. , And a personal computer 7. All or part of the AC modules 5a, 5b, 5c.
[0016]
The distribution line 3 is composed of an R phase and a T phase constituted by two voltage lines R and T and one neutral line N. The R phase and the T phase are both single-phase AC100V, and the voltage lines R and T are single-phase AC200V.
[0017]
The connection protection device 4 includes a switch 11, a system abnormality detection circuit 12, a connection control circuit 13, and the like.
The switch 11 is closed or opened in accordance with a signal from the system abnormality detection circuit 12, and the AC module 5 and the distribution line 3 are connected to be connected to each other or disconnected to be disconnected.
[0018]
The system abnormality detection circuit 12 is provided with OVR / UVR and OFR / UFR, monitors the presence or absence of abnormality in the voltage and frequency of the commercial power system, and when those abnormalities are detected, a signal for opening the switch 11 Is output. The system abnormality detection circuit 12 is also provided with passive and active isolated operation prevention functions, detects when the AC module 5 is in an isolated operation state due to a power failure of the commercial power system, etc. Outputs an open signal.
[0019]
The interconnection control circuit 13 controls the entire interconnection protection device 4. The interconnection control circuit 13 has a communication function using an RS-232C interface. When the system abnormality detection circuit 12 detects an abnormality and opens the switch 11, the interconnection control circuit 13 outputs a gate block command signal to all AC modules 5 and stops their operation. An open / close state signal SK indicating the state of the switch 11 is received and output to the independent operation control device 6. The interconnection control circuit 13 receives information on each power generation state and operation state from each AC module 5.
[0020]
The interconnection control circuit 13 communicates with the personal computer 7. The personal computer 7 receives information from the grid protection device 4 to perform monitoring such as detection of the power generation state of each AC module 5 or the presence or absence of a failure.
[0021]
As shown in FIG. 2, the AC module 5 is configured by integrating one solar cell module PVM and one inverter unit VTU. One solar cell module PVM outputs a DC voltage of about 30V. The inverter unit VTU converts the output of the solar cell module PVM into a direct current of about 180 V by a DC / DC converter (converter circuit 21), and then 50/60 Hz AC power by a voltage-type current control type inverter (inverter circuit 23). Convert to
[0022]
A large number of AC modules 5 configured in this way are connected to the R phase or T phase of the distribution line 3a by the same number to achieve interconnection with the commercial power system. Each AC module 5 is arranged as shown in FIG. 6, for example, and is installed outdoors. Such an interconnection system has the following advantages.
(1) Since each solar cell module PVM generates power according to each condition, it is possible to minimize the influence of environmental conditions such as orientation, shadow, temperature, etc. on each solar cell module PVM. In addition, MPPT control (optimum operating point tracking control) can be performed on each solar cell module PVM, and the efficiency of the entire system is improved.
(2) Since a system can be constructed by connecting a plurality of solar cell modules PVM in parallel for the R phase or the T phase, the entire installation space can be effectively used, and the design and construction are easy.
(3) Since the output of one AC module 5 is as small as about 100 W, by increasing or decreasing the number of AC modules 5, it is possible to easily cope from a small system of about 100 W to a medium scale system of about several KW. It is. In order to maintain the phase balance between the R phase and the T phase of the distribution line 3, basically an even number of AC modules 5 are necessary, but even in the case of an odd number, the unbalance is 100 W at the maximum. There is practically negligible range.
(4) Since there is no DC circuit, a backflow prevention diode or the like is unnecessary, and there is no DC loss due to it. Also, the wiring work is only an AC circuit, and can be done by normal indoor wiring work.
(5) The number of inverter units VTU used is increased. For example, the number of inverter units VTU used is more than ten times that of a 3KW inverter device, so the cost can be reduced due to the mass production effect.
(6) The AC module 5 has only a built-in self-protection function, and the control is complicated and does not have a sophisticated interconnection protection function and independent operation control function. Therefore, the circuit configuration of the AC module 5 is simplified and the number of parts is reduced. Cost reduction and high reliability can be achieved.
(7) The main circuit of the AC module 5 can be made into an IC by using a thick film IC or the like to reduce the size.
(8) Since the output voltage of the inverter unit VTU is 100 V, which is a half of that when connecting between the voltage lines of the distribution line 3 (output voltage is 200 V), the total conversion efficiency of the inverter unit VTU is high.
[0023]
In FIG. 3, the inverter unit VTU includes a converter circuit 21, an MPPT circuit 22, an inverter circuit 23, a gate control circuit 24, an operational amplifier 25, a multiplier 26, operational amplifiers 27 and 28, a bandpass filter 29, an interface 30, and a current transformation. The device 31 and the transformer 32 are included.
[0024]
The converter circuit 21 converts a DC voltage of about 30V output from the solar cell module PVM to a DC voltage of about 180V by high frequency switching. At that time, the MPPT circuit 22 performs known optimum operating point tracking control for extracting the maximum power from the solar cell module PVM.
[0025]
The inverter circuit 23 includes a plurality of switching elements connected in a bridge manner. The gate control circuit 24 has a microprocessor and supplies a pulse width modulated switching control signal to the inverter circuit 23.
[0026]
The voltage V11 input to the inverter circuit 23 is input to the operational amplifier 25, and an input error signal Sa that is a difference from the voltage command value Vref is generated. The input error signal Sa becomes one input signal of the multiplier 26. The signal S12 is input as the other input signal of the multiplier 26. The signal S12 is obtained by adding the fundamental frequency component S11 of the interconnection point voltage V3 extracted by the bandpass filter 29 and the voltage control signal S13 given by the signal SC by the operational amplifier 28. A current command value signal Si indicating a control target value is generated by multiplying the input error signal Sa and the signal S12. The current command value signal Si, the actual output current value detected by the current transformer 31, and the current control signal S14 given by the signal SC are input to the operational amplifier 27, and a current error signal SΔi is generated. This current error signal SΔi is input to the gate control circuit 24.
[0027]
In the gate control circuit 24, a switching signal whose pulse width is adjusted is generated by comparing the current error signal SΔi with the reference triangular wave signal of about 20 kHz, and is output to the inverter circuit 23.
[0028]
The interface 30 performs digital serial communication with an external device via the RS-232C interface, inputs the voltage control signal S13 and the current control signal S14 described above from the outside, and information on the operation state of the inverter unit VTU. Output to the outside.
[0029]
By such feedback control, AC power having an appropriately set current value and a power factor of 1 having the same current phase as the system voltage is output from the inverter circuit 23 to the R-phase or T-phase load of the distribution line 3. The
[0030]
As can be understood from the above description, the voltage of the commercial power system becomes the connection point voltage V3 during the connection, but when the connection is released, the voltage of the commercial power system disappears and the connection point voltage V3 becomes zero. It becomes. In that case, instead of the commercial power system, a reference signal supply unit 61 described later supplies the same AC voltage as that of the commercial power system as a reference signal, so that the inverter unit VTU can be operated. Even if the connection point voltage V3 is zero, control can be performed by a voltage control signal S13 instead of the connection point voltage V3. Since the voltage control signal S13 needs to have a voltage waveform with an appropriate frequency, the control must be performed at high speed. Therefore, an oscillator that generates a voltage waveform with an appropriate frequency may be provided, and the amplitude thereof may be controlled by the signal SC. Further, the magnitude of the output current can be controlled by the current control signal S14.
[0031]
Next, a wiring connection method between the distribution line 3a (distribution line 3) and the AC module 5 will be described.
In FIG. 4, each inverter unit VTU has five connection poles R, N, T, PO, E for connecting the output of the inverter circuit 23 to the R phase or the T phase, and is parallel to each other. Two fixed-side connectors 41a and 41b connected to are attached.
[0032]
A jumper line circuit 42 is provided between the output of the inverter circuit 23 and the connection poles R and T. By changing the connection of the jumper line 42a, the output of the inverter circuit 23 is changed to the R phase or the T phase. Can be selectively connected to any of the above.
[0033]
Referring also to FIG. 5, the inverter units VTU are sequentially connected to each other by connection cables 50 having cable-side connectors 51a and 51b provided at both ends. That is, each cable side connector 51a, 51b has five connection poles R, N, T, PO, E that can be connected to the fixed side connectors 41a, 41b, and each cable side connector 51a, 51b is adjacent to each other. All the inverter units VTU, that is, the AC modules 5 are sequentially connected to each other by being inserted into and connected to the respective fixed connectors 41b and 41a provided in the matching inverter unit VTU.
[0034]
The fixed connection connector 41a of the first inverter unit VTU1 is connected to an interconnection cable 55 having a cable connector 51a provided at one end. The interconnection connection cable 55 has three electric wires R, N, and T connected to the distribution line 3 and two electric wires PO and E as interface circuits of the interconnection protection device 4 and the independent operation control device 6. It is connected.
[0035]
As a result, the output of each AC module 5 is connected to the R-phase or T-phase of the distribution line 3, and the signal SC of the interface 30 of each AC module 5 is connected to the interconnection protection device 4 and independent via the wires or poles PO and E. Connected to the operation control device 6.
[0036]
As shown in FIG. 6A, a large number (24 in this example) of AC modules 5 are arranged in a matrix, and each AC module 5 is adjacent to each other as shown by a chain line in the figure. The connection cables 50 are sequentially connected to each other. In each AC module 5, the AC modules 5 connected to the R phase and the AC modules 5 connected to the T phase are arranged in a staggered manner by selectively connecting the respective jumper wires 42a.
[0037]
When arranged in a zigzag pattern as shown in FIG. 6 (A), even when the sunlight is behind a building or the like, the R-phase and T-phase objects are almost averagely shaded. Therefore, no large imbalance occurs between the R phase and the T phase.
[0038]
As described above, the AC module 5 is connected to the distribution line 3a by adopting the common connector system in which the adjacent AC modules 5 are sequentially connected by the common connection cable 50 regardless of the R phase or the T phase. The wiring work is extremely easy, the work can be performed in a short time, and there is no fear of incorrect wiring. In addition, by changing the connection of the jumper wire 42a of each AC module 5, it can be easily changed to either the R phase or the T phase without changing the actual position of the AC module 5. Their arrangement can be arbitrarily set.
[0039]
In FIG. 6B, the upper AC module 5 is for the R phase, and the lower AC module 5 is for the T phase. When arranged in this way, it is easy to manage because the R phase and the T phase are gathered together, but there is a high possibility that it will be shifted to either the R phase or the T phase and become a shadow. In that case, an unbalance occurs between the R phase and the T phase.
[0040]
In addition, when any AC module 5 fails, when the load is unbalanced, or when the number of AC modules 5 is increased or decreased, the connection of the jumper wire 42a of any AC module 5 is changed and the whole is changed. Can be balanced.
[0041]
Furthermore, as can be understood from FIG. 6, all the AC modules 5 are connected by sequentially connecting the shortest distances by three electric wires in the connection cable 50, so that the required electric wire length can be reduced. As a result, the cost can be reduced, the reliability can be increased, and the maintenance can be facilitated. Actually, for example, when the R-phase or T-phase AC modules 5 are separately connected in order to realize the arrangement shown in FIG. Since the four electric wires are stretched over the entire surface, the necessary electric wires are lengthened, the possibility of erroneous wiring is high, and maintenance is not easy.
[0042]
When the switch 11 of the interconnection protection device 4 is opened and the interconnection is released, the independent operation control device 6 operates the AC module 5 in an independent state from the commercial power system, and outputs the emergency power supply. It is for use as. The independent operation control device 6 includes a reference signal supply unit 61, a charger 62, an emergency inverter 63, an overall control unit 64, a battery 65, an output changeover switch 66, and an outlet 67.
[0043]
The reference signal supply unit 61 supplies the AC module 5 with the fundamental frequency component S11 of the connection point voltage V3 when the connection is released, so that the distribution line 3a has the same voltage and frequency as the commercial power system. Supply the signal. Therefore, the reference signal supply unit 61 only needs to output the same waveform as that of the interconnection point voltage V3 and does not need to supply power. However, the reference signal supply unit 61 does not need to supply power. It is preferable that power of about 10 to several hundred mW can be output.
[0044]
The charger 62 rectifies the output of the AC module 5 and converts it into direct current, and charges the battery 65. The values of the input current, input voltage, output current, and output voltage of the charger 62 are detected by a detection device (not shown) and input to the overall control unit 64. The charger 62 is provided with an electromagnetic switch that opens and closes the distribution line 3a so that the charger 62 operates only when the connection is released. The operation may be electronically controlled without providing such an electromagnetic switch. Since the output current of the charger 62 is determined by the input current, that is, the output current of the AC module 5, the AC module 5 has a state corresponding to the state of the battery 65 so that the battery 65 is not overcharged by the charger 62. The output current is controlled by the overall control unit 64. Further, the overall control unit 64 controls the output current and output voltage of the AC module 5 so that the voltage applied to the charger 62 does not exceed the input allowable voltage range.
[0045]
The emergency inverter 63 converts the DC power stored in the battery 65 into single-phase AC100V commercial power and supplies it to the outlet 67 or the distribution line 3b according to the connection of the output changeover switch 66. The emergency inverter 63 is of a surge type and can instantaneously output a surge current about 10 times the rated current value. Therefore, it is possible to operate an inductive load having a large starting current such as an electric motor, and a refrigerator, a washing machine, an air conditioner, or the like can be connected to the outlet 66 or the distribution line 3b.
[0046]
The overall control unit 64 controls the entire independent operation control device 6 so that the AC module 5 operates in an independent state when the switch 11 is opened and the connection between the commercial power system and the AC module 5 is released. To do. The overall control unit 64 outputs a command signal SC that is a basis of the current control signal S14 for controlling the output current of each AC module 5 so that the charging current of the battery 65 is appropriate. The command signal SC is output to each AC module 5 via the RS-232C interface, for example, every second. Each AC module 5 generates a current control signal S14 based on the command signal SC.
[0047]
As described above, the command signal SC for controlling the output current of the AC module 5 only needs to be output at a slow speed on the order of seconds, and thus can be sufficiently controlled by serial communication.
[0048]
As can be understood from the above description, the independent operation control device 6 is for using the generated power of the AC module 5 as an emergency power source when the interconnection is canceled due to a power failure or the like of the commercial power system. . Since power generation using only sunlight is unstable as a power supply device, the battery 65 is charged thereby, and the electric power stored in the battery 65 is converted into commercial power and supplied to the load. Thereby, the electric power generated by the solar cell module PVM is stably supplied to the load, so that the sunlight can be effectively used. Further, by switching the connection of the electrical product connected to the distribution line 3 or 3a, for example, a home computer, to the distribution line 3b simultaneously with the release of the interconnection, the grid-connected power supply system 1 can be used as an uninterruptible power supply system for the computer. It can be operated. Moreover, since such complicated control is performed by the independent operation control device 6, it can be realized without complicating the circuit configuration of each AC module 5.
[0049]
Although not shown, the overall control unit 64 has a mode changeover switch for switching whether the independent operation control by the independent operation control device 6 is automatically activated or manually activated when the interconnection is released. A manual start switch for starting when the mode is set, other switches, various display lamps, and the like are provided.
[0050]
Next, the operation of the independent operation control device 6 will be described with reference to a flowchart.
FIG. 7 is a flowchart showing an outline of the operation of the independent operation control device 6, and FIG. 8 is a flowchart showing a process flow of the independent operation.
[0051]
In FIG. 7, when the independent operation is started, the switch 11 is in the open state, and the line voltage is zero (Yes in # 11 to 13), the reference signal supply unit 61 is operated to output the reference signal. The distribution line 3a is supplied (# 14), the operation of the AC module 5 is started (# 15), and the independent operation control process is performed (# 16).
[0052]
Here, the activation of the independent operation is detected by the mode changeover switch being in the automatic mode or by the manual activation switch being turned on in the manual mode. The fact that the switch 11 is in the open state is detected by an open / close state signal SK from the switch 11. The fact that the line voltage is zero is detected, for example, when the interconnection point voltage V3 is zero.
[0053]
In FIG. 8, in the independent operation control, first, it is determined whether or not there is a stop command (# 21). When the manual start switch is turned off or when the stop switch is pressed (Yes in # 21), the output of the charger 62, the AC module 5, and the emergency inverter 63 is stopped, and the reference signal supply unit 61 is stopped. Stop processing such as stopping the operation is performed (# 31).
[0054]
Output current command I of AC module 5₁Is updated (# 22). The state of charge or discharge of the battery 65, for example, the terminal voltage of the battery 65 is monitored at an appropriate cycle (for example, every few minutes), and the output current command I is determined according to the state.₁Is updated.
[0055]
When updating (Yes in # 22), output current command I₁Is updated (# 23), and the correction coefficient a is set to 1.0 (# 24). Current command Ip (= a × I) for current command port₁) Is output (# 25). A signal SC is generated based on the current command Ip and output to the AC module 5. In AC module 5, current control signal S14 is generated based on signal SC.
[0056]
Output current I of AC module 5₀(# 26) and output current I₀And output current command I₁Are compared (# 27). Output current I₀If it is smaller (No in # 27), the process from step # 21 is repeated. Output current I₀Is larger (Yes in # 27), in order to reduce the correction coefficient a, a value obtained by multiplying the correction coefficient a by a coefficient d smaller than 1 is set as a new correction coefficient a (# 28). As the coefficient d, a fixed value is used, or an appropriate value read from a preset conversion table is used. Such a conversion table stores, for example, coefficients d for various voltage values of the battery 65. The above-described processing is repeated within a range where the correction coefficient a is not smaller than the minimum value (# 29).
[0057]
When the correction coefficient a is smaller than the minimum value (Yes in # 29), the output current I₀Is determined to be impossible, and abnormality processing is performed (# 30). In the abnormality process, the outputs of the charger 62, the AC module 5, and the emergency inverter 63 are stopped, the operation of the reference signal supply unit 61 is stopped, and the abnormality display lamp is turned on.
[0058]
Thus, the output current of the AC module 5 is adjusted according to the terminal voltage of the battery 65 and the like so that the charging current decreases as the charging of the battery 65 proceeds.
[0059]
According to the above-described embodiment, even when some of the solar cell modules PVM have failed, the operation of the AC module 5 related to the failure is stopped, and the R phase and the T phase are balanced by the jumper wire circuit 42. The operation by the solar cell module PVM that has not failed can be continued. Since each solar cell module PVM operates independently of each other, even if the power generation status of each solar cell module PVM is different from each other, the maximum power can be drawn from each solar cell module PVM, and overall high conversion Efficiency can be obtained.
[0060]
Further, when the connection between the commercial power system and the AC module 5 is released, the AC module 5 can be operated independently, and the generated power of the solar cell module PVM can be effectively used. In this case, the battery 65 is charged by the output of the AC module 5 and the emergency inverter 63 is driven by the battery 65 to supply commercial power. Therefore, the supplied power is stabilized, and the AC module 5 and the independent operation control device are supplied. 6 can be used as an emergency power source for household electric appliances.
[0061]
In the above embodiment, the interconnection protection device 4, the AC module 5, and the independent operation control device 6 are connected by the RS-232C interface, and the signal SC is exchanged bidirectionally. An interface other than -232C may be used, and an analog signal may be used. A changeover switch may be provided as the jumper line circuit 42. During normal times when the commercial power system and the AC module 5 are linked, the battery 65 may be trickle charged by obtaining a small amount of power from the commercial power system.
[0062]
In the above-described embodiment, the output voltage of the solar cell module PVM, the configuration of the inverter unit VTU, the total number of AC modules 5, the configuration of the interconnection protection device 4, the configuration of the independent operation control device 6, and the communication method between them The overall configuration, operation content, operation sequence, and the like of the grid-connected power supply system 1 can be changed as appropriate in accordance with the gist of the present invention.
[0063]
The power supply system of the present invention is not limited to a system using the above-described AC module, but is a conventional grid connection that links power output from a plurality of solar cell modules to a commercial power grid through one inverter. It can also be applied to system systems.
[0064]
【The invention's effect】
According to the first to sixth aspects of the invention, when the connection between the commercial power system and the inverter device is released, the inverter device can be operated independently, and the generated power of the solar cell is effectively used. can do.
[0065]
According to the second to sixth aspects of the invention, the supplied power is stable and can be used as an emergency power source.
According to the invention of claim 5, since it is possible to supply commercial power by the second inverter, it is also possible to connect household electric equipment as a load.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a circuit of a grid-connected power supply system according to the present invention.
FIG. 2 is an overview of an AC module.
FIG. 3 is a block diagram showing a circuit of an AC module.
FIG. 4 is a block diagram for explaining a connection state of an AC module.
FIG. 5 is a diagram for explaining a connection state of an AC module;
FIG. 6 is a diagram illustrating an arrangement state of an AC module.
FIG. 7 is a flowchart showing an outline of the operation of the independent operation control device.
FIG. 8 is a flowchart showing a flow of independent operation processing.
[Explanation of symbols]
1 Grid-connected power supply system
3,3a Distribution line
5 AC module (power supply system)
6 Independent operation control device (power supply system)
11 Switch
61 Reference signal supply unit
62 Charger
63 Emergency inverter (second inverter)
64 General control department
65 Battery (secondary battery)
SC1 command signal
PVM solar cell module (solar cell)
VTU inverter unit (inverter)

Claims (6)

A plurality of voltage detection current control type inverters that convert DC power output from solar cells into AC power are connected to a distribution line, and the distribution line and a commercial power system are connected via an interconnection protection device. A grid-connected power supply system configured to link the inverter and the commercial power system by:
The linkage protection device includes a system abnormality detection circuit and a switch, and is configured to release the connection by the switch when an abnormality of the commercial power system is detected by the system abnormality detection circuit.
A reference signal supply unit that generates and supplies a signal of the same voltage and frequency as the commercial power system to the distribution line when the interconnection is released by the switch;
An overall control unit that gives a command signal for controlling the output voltage or output current to the inverter;
A grid-connected power supply system characterized by comprising: A plurality of voltage detection current control type inverters that convert DC power output from solar cells into AC power are connected to a distribution line, and the distribution line and a commercial power system are connected via an interconnection protection device. A grid-connected power supply system configured to link the inverter and the commercial power system by:
The linkage protection device includes a system abnormality detection circuit and a switch, and is configured to release the connection by the switch when an abnormality of the commercial power system is detected by the system abnormality detection circuit.
A reference signal supply unit that generates and supplies a signal of the same voltage and frequency as the commercial power system to the distribution line when the interconnection is released by the switch;
A secondary battery,
A charger connected to the distribution line so as to charge the secondary battery at least when the interconnection is released;
An overall control unit that gives a command signal for controlling each output current to the inverter when the interconnection is released;
A grid-connected power supply system characterized by comprising: The overall control unit is configured to detect an input current and an input voltage input to the charger and output the command signal for controlling the input voltage so as not to exceed a predetermined value.
The grid connection power supply system according to claim 2. The overall control unit is configured to detect a charging current to the secondary battery and output the command signal for controlling the charging current so as not to exceed an appropriate value.
The grid connection power supply system according to claim 2. A second inverter having the secondary battery as an input power source is provided;
The grid connection power supply system in any one of Claims 2 thru | or 4.   6. The grid-connected power supply system according to claim 1, wherein the solar cell and the inverter are integrated to form an AC module, and a plurality of the AC modules are connected to the distribution line.

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