JP5906403B2 - Power conversion system - Google Patents

Description

  The present invention relates to a power conversion system that converts power generated by a generator into AC power, and distributes and supplies this AC power to indoor wiring of a plurality of consumers.

  Conventionally, power generated by a common generator (for example, solar cells, fuel cells, wind power generators, etc.) is distributed to a plurality of consumers who are individually supplied with power from the commercial power system using a predetermined distribution ratio. A power conversion system has been proposed (Patent Document 1).

JP 2003-134673 A

  Such a power conversion system is, for example, a distribution that is determined in advance according to the investment ratio or the like when it is desired to provide a common generator in an apartment house, or when a plurality of neighboring customers want to provide a common generator. The generator was used using the ratio.

  This power conversion system includes a solar cell as a generator, and directly supplies the power generated by the solar cell to the power conversion device of each consumer. The generated power is generated by operating each power conversion device so that each consumer can take in a power having a predetermined distribution ratio.

  However, for example, when an abnormality occurs in a certain customer that prevents power from being supplied from the commercial power system to the indoor wiring due to electric leakage, etc., for safety, this customer's indoor wiring and this customer generate power. The power converter that supplies the power is disconnected. In such a case, the customer who has an abnormality cannot use the power generated by the generator, resulting in unfairness.

  The present invention has been made in view of the above-mentioned problems, and even when an abnormality occurs in which power is not supplied from the commercial power system to the indoor wiring, the indoor wiring and power conversion device of the customer in which the abnormality has occurred It is an object to provide a power conversion device that allows an abnormal customer to use power generated by a generator while disconnecting the power.

  In order to achieve the above object, the power from the generator provided in common to the indoor wiring of a plurality of consumers configured to be able to supply power from a commercial power system and power generated by a generator different from the system. In the power conversion system configured to control supply, the power generated by the generator is converted into controlled AC power, and a separate first power meter is connected to each indoor wiring of the plurality of consumers. A plurality of inverter circuits supplied via the first inverter, the inverter circuit being provided between the output side of the inverter circuit and the first power meter, and short-circuiting / opening between the inverter circuit and the indoor wiring of the consumer. 1 switch, provided between the inverter circuit and the first switch, and the commercial power system via a second power meter, short-circuit / open between the inverter circuit and the power system Second switch And when the indoor wiring has an abnormality, the first switch is opened, the second switch is short-circuited, the first power meter is bypassed, and the commercial power is supplied from the inverter circuit. The generated power is supplied to a system.

  According to the present invention, when power is not supplied to the indoor wiring from the commercial power system, the indoor wiring and the inverter circuit are opened by the first switch, and the indoor wiring is bypassed to bypass the commercial power system and the inverter. The second switch that connects the circuit is short-circuited. For this reason, it is possible to sell power to the commercial power system by bypassing the indoor wiring of the customer in which the abnormality has occurred, while separating the customer and the power conversion device in which the abnormality has occurred. That is, an abnormal customer can use the power generated by the generator in the form of power sales.

  In the above-mentioned invention, the consumer inputs AC power supplied from the commercial power system via a third power meter, and uses the first power meter to supply AC power supplied from the inverter circuit. A distribution board that distributes the input power to a load connected to the indoor wiring, and a second power meter is provided on the input side of the commercial power system of the distribution board. The second switch is provided between the inverter circuit and the first switch, and the distribution board and the power meter. The second switch is provided so as to detect power flowing backward from the indoor wiring to the commercial power system. It is characterized by short-circuiting / opening.

  Moreover, in the above-mentioned invention, it is provided with the power failure detection circuit which detects the power failure of the said commercial power system, and when the said power failure detection circuit detects a power failure, the short circuit of the said 2nd switch is prohibited.

  Moreover, in the above-mentioned invention, it is provided on the commercial power system side of the second switch, has a voltage sensor for detecting the voltage of the commercial power system, and the power failure detection circuit detects the voltage detected by the voltage sensor. It is characterized by detecting a power failure when there is an abnormality.

  In the above-described invention, the power failure detection circuit detects whether power is supplied from the inverter circuit when power is not supplied from the commercial power system to the indoor wiring of the plurality of consumers. And determining that the commercial power system is out of power when power is being supplied from the inverter circuit when no power is supplied from the commercial power system to the indoor wiring of a plurality of consumers. It is characterized by.

  Moreover, in the above-mentioned invention, when the power failure detection circuit detects that no electric power is supplied from the commercial power system to at least one of the indoor wirings of the plurality of consumers, all inverters The circuit is temporarily stopped, and after the suspension, the operation of the inverter circuit that supplies power to the indoor wiring of the customer that is supplied with power from the commercial power system among the indoor wiring of the plurality of consumers is resumed. It is configured to be possible.

  According to the present invention, even when an abnormality occurs in which power is not supplied from the commercial power system to the indoor wiring, the abnormality occurred while separating the indoor wiring and the power conversion device of the customer where the abnormality occurred. Provided is a power conversion device that allows a consumer to use power generated by a generator.

It is a schematic diagram which shows the installation state of a power conversion system. It is a wiring diagram which shows the connection with a distribution board, a commercial power system, and a power converter device. It is a circuit diagram of a power converter. It is a control flowchart of a control circuit.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a schematic diagram showing an installation state of the power conversion system 1. As shown in this figure, each consumer 2a-2c is supplied with AC power from the commercial power system 3, and a common power conversion system 1 is provided for these consumers 2a-2c.

  The power conversion system 1 includes a solar cell 10 (generator) common to the consumers 2a to 2c and a power conversion device 11. In the present embodiment, the consumers 2a to 2c are constituted by detached houses, and the consumers 2a to 2c are neighboring houses, respectively. The solar cell 10 is installed in the vicinity of these consumers 2a-2c, and the power converter 11 is arrange | positioned beside one consumer 2a among the some consumers 2a-2c. The power conversion device 11 has two wirings La1 to La3 and Lb1 to Lb3 for each of the consumers 2a to 2c, and uses the two wirings La and Lb to respectively generate power. It distributes and supplies to consumers 2a-2c. Note that the consumers 2a to 2c are not limited to neighboring single-family houses, and may be constituted by, for example, an apartment house such as an apartment or an apartment. Moreover, although the solar cell 10 is installed in the vicinity of the consumers 2a-2c, you may make it install in the roof of at least 1 consumer 2a-2c.

  Each consumer 2a-2c has distribution boards 21a-21c. FIG. 2 shows a wiring diagram showing connections between the distribution board, the commercial power system, and the power converter 11. The distribution boards 21a to 21c input AC power supplied from the commercial power system 3 via power meters 22a to 22c and a first breaker (third switch) 61, which will be described later. Moreover, the distribution boards 21a-21c input the electric power which the power converter device 11 supplies via the wattmeters 24a-24c and the 2nd breaker (4th switch) 62 which are mentioned later. The input AC power is superimposed in the distribution boards 21a to 21c and is distributed to the indoor wirings 31a to 31c of the consumers 2a to 2c.

  The first breaker 61 cuts off the connection between the commercial power system 3 and the indoor wirings 31a to 31c by detecting that a leakage current has occurred in the load or the like and an overcurrent has flown in the indoor wirings 31a to 31c, respectively. Similarly, the second breaker detects the occurrence of leakage in the load or the like, and detects that overcurrent flows in the indoor wirings 31a to 31c, thereby connecting the power converter 11 and the indoor wirings 31a to 31c. Cut off.

  One wiring La of the two wirings La and Lb of the power conversion device 11 is connected to the side of the distribution board where the AC power is input to the power conversion device 11. Moreover, the other wiring Lb (bypass circuit) of the two wirings La and Lb connects the power conversion device 11 between the power meters 23a to 23c and the distribution boards 21a to 21c described later. Thereby, the power converter 11 supplies the generated power of the solar cell 10 to the commercial power system 3 by bypassing the distribution boards 21a to 21c (indoor wirings 31a to 31c).

  In addition, on the commercial power system 3 side of the distribution boards 21a to 21c of the consumers 2a to 2c, there are power purchase meters (third power measuring devices) 22a to 22c and power selling meters (second power measuring devices). 23a to 23c are provided. Moreover, the wattmeters (1st power measuring device) 24a-24c are provided in the power converter device 11 side of the distribution boards 21a-21c of each consumer 2a-2c. The electricity purchase meters 22a to 22c detect the electric power supplied from the commercial power system 3 to the indoor wirings 31a to 31c of the consumers 2a to 2c. The detected power is used to calculate a purchased power charge. The electricity sales meters 23a-23c detect the electric power supplied to the commercial power system 3 from the indoor wirings 31a-31c of the consumers 2a-2c. Moreover, the electricity sales meters 23a-23b detect the electric power supplied to the commercial power grid 3 from the other wiring Lb (bypass circuit). The detected power is used to calculate a power selling power charge. Moreover, the wattmeters 24a-24c detect the electric power supplied from the power converter 11 to the indoor wiring 31a-31c of the consumers 2a-2c.

  In this way, each consumer 2a-2c is individually provided with a power purchase meter 22a-22c and a power sale meter 23a-23c, and can be configured to individually buy and sell power with an electric power company. Has been.

  Next, the power converter 11 will be described in detail with reference to the drawings. FIG. 3 is a circuit diagram of the power converter. As shown in this figure, the power converter 11 includes a booster circuit 41, a plurality of inverter circuits 42a to 42c, first system interconnection relays 43a to 43c (first switch), and second system interconnection relay 45a. To 45c (second switch), control circuit 44, input current sensor 51, input voltage sensor 52, output current sensors 53a to 53c, output voltage sensors 54a to 54c, system voltage sensors 55a to 55c, and indoor wiring voltage sensor 56a To 56c. Further, the booster circuit 41, the plurality of inverter circuits 42a to 42c, the grid connection relays 43a to 43c, the second grid connection relays 45a to 45c (second switch), the control circuit 44, the input current sensor 51, the input The voltage sensor 52, the output current sensors 53a to 53c, the output voltage sensors 54a to 54c, the system voltage sensors 55a to 55c, and the indoor wiring voltage sensors 56a to 56c are housed in a common housing, and are shared by arranging this housing. (Here, next to the customer 2c). When the number of consumers is large, the booster circuits are distributed and stored in a plurality of adjacent housings, and the plurality of inverter circuits and the plurality of current sensors are also divided into the plurality of housings. Can be stored and configured.

  The booster circuit 41 is connected between the solar cell 10 and the plurality of inverter circuits 42 a to 42 c and boosts the voltage of the solar cell 10. The booster circuit 41 includes a reactor, a switching element such as IGBT or FET, a diode circuit, and a capacitor. Specifically, the reactor and the diode are connected in series to form a series circuit, and the reactor side of the series circuit is connected to the positive electrode side of the solar cell 10. Moreover, the connection point of a reactor and a diode and the negative electrode side of a solar cell are connected via the switch element. Moreover, the diode side of the series circuit and the negative electrode side of the solar cell are connected via a capacitor. The booster circuit 41 periodically conducts / cuts off the switch element. For example, by setting a ratio (hereinafter referred to as ON ratio) for conducting the switch element for each period, the voltage of the solar cell is set at a desired boost ratio. Boost and output to both ends of the capacitor.

  The plurality of inverter circuits 42 a to 42 c each convert the generated power of the common solar cell 10 input via the booster circuit 41 into AC power. Further, wirings La1 to La3 are connected to the output sides of the plurality of inverter circuits 42a to 42c, and the inverter circuits 42a to 42c are connected to the indoor wirings 31a to 31c of the consumers 2a to 2c using the wirings La1 to La3. The power generated by the solar cell 10 is supplied via the individual power meters 24a to 24c. Between the output sides of the inverter circuits 42a to 42c of the wirings La1 to La3 and the wattmeters 24a to 24c, first system interconnection relays 43a to 43c are provided, respectively, for these first system interconnections. Relays 43a to 43c short-circuit / open between inverter circuits 42a to 42c and indoor wirings 31a to 31c of consumers 2a to 2c, respectively.

  Also, the wirings (bypass circuits) Lb1 to Lb3 are connected between the inverter circuits 42a to 42c and the first system interconnection relays 43a to 43c, respectively, and the first system interconnection relays 43a to 43c and the indoor wiring 31a. The power generated by the solar cell 10 can be supplied from the inverter circuits 42a to 42c to the commercial power system 3 by bypassing ˜31c. The wirings Lb1 to Lb3 are connected to the second system interconnection relay via the second power meter between the inverter circuits 42a to 42c and the first system interconnection relays 43a to 43c and the commercial power system 3. 45a to 45c are provided (the second power grid relays 45a to 45c are provided on the inverter circuits 42a to 42c side in the power selling meters 23a to 23c and the second grid power relays 45a to 45c). These second system interconnection relays 45 a to 45 c short-circuit / open between the inverter circuits 42 a to 42 c and the commercial power system 3.

  Thus, the first system interconnection relay 43 is short-circuited and the second system interconnection relay 45 is opened to the indoor wiring 31 of the customer 2 for the first system interconnection. The inverter circuit 42 that opens the relay 43 and short-circuits the second system interconnection relay 45 bypasses the first system interconnection relay 43 and the indoor wiring 31 and is connected to the customer 2. The generated power of the solar cell 10 is distributed to the commercial power system 3.

  Each of the inverter circuits 42a to 42c has a bridge circuit including four switch elements such as IGBT and FET, and a filter circuit including two reactors and a capacitor. In the bridge circuits of the inverter circuits 42a to 42c, the DC side is connected to both ends of the capacitor of the booster circuit, and the AC side is connected to the filter circuit. In the filter circuit, one end of each of the two reactors is connected by a capacitor, and the other end of each of the reactors is connected to the AC side of the bridge circuit. The inverter circuits 42a to 42c use a predetermined PWM (Pulse Width Modulation) signal to conduct / cut off the four switch elements, thereby generating AC power having a waveform synchronized with the commercial power system at both ends of the capacitor of the filter circuit. It produces | generates and supplies to the indoor wiring 31a-31c of the consumers 2a-2c.

  The input current sensor 51 is provided on the input side of the booster circuit 41 and detects a DC input current Ii input from the solar cell 10 to the booster circuit 41. The input voltage sensor 51 is provided on the input side of the booster circuit 41 and detects a DC input voltage input from the solar cell 10 to the booster circuit 41. Output current sensors 53a to 53c are provided on the output sides of the plurality of inverter circuits 42a to 42c, respectively, and detect instantaneous output currents Ioa to Ioc of the inverter circuits 42a to 42c. Output voltage sensors 54a to 54c are provided on the output sides of the plurality of inverter circuits 42a to 42c, respectively, and detect instantaneous output voltages Voa to Voc of the inverter circuits 42a to 42c. The system voltage sensors 55a to 55c are provided on the commercial power system 3 side of the second system interconnection relays 45a to 45c, respectively, and the system voltage Vc1 of the commercial power system 3 that supplies power to the respective consumers 2a to 2c. ˜Vc3 (AC) is detected. Indoor wiring voltage sensors 56a to 56c are provided on the indoor wiring 31a to 31c side of the first system interconnection relays 43a to 43c, and the indoor wiring voltages Vw1 to the indoor wirings 31a to 31c of the respective consumers 2a to 2c are provided. Vw3 is detected.

  The detected input current Ii and input voltage Vi are input to the control circuit. The output currents Ioa to Ioc, the output voltages Voa to Voc, the system voltages Vc1 to Vc3, and the indoor wiring voltages Vw1 to Vw3 are input to the control circuit, and the output currents Ioa to Ioc and the output voltages Voa to Voc input in the past. The execution value is calculated in the control circuit 44 using the system voltages Vc1 to Vc3 and the indoor wiring voltages Vw1 to Vw3. Thereafter, the effective values of the output currents Ioa to Ioc are the output currents Ia to Ic, the effective values of the output voltages Voa to Voc are Va to Vc, the effective values of the system voltages Vc1 to Vc3 are Vca to Vcc, and the indoor wiring voltage Vw1 The effective value of Vw3 is defined as Vwa to Vwc. The input current Ii, the input voltage Vi, the output currents Ia to Ic, the output voltages Va to Vc, the system voltages Vca to Vcc, and the indoor wiring voltages Vwa to Vwc are used for controlling the operation of the power converter 11.

  The control circuit 44 is composed of, for example, a microcomputer, and controls the operation of the booster circuit 41, the operations of the inverter circuits 42a to 42c, and the operations of the grid interconnection relays 43a to 43c.

The control circuit 44 sets the ON ratio of the booster circuit 41 so that the generated power of the solar cell 10 (input power to the booster circuit 41) is maximized. Specifically, the generated power of the solar cell 10 input to the booster circuit 41 is calculated from the input current and the input voltage obtained from the input current sensor 51 and the input voltage sensor 52. If the calculated generated power is greater than the previously calculated generated power, change the ON ratio to the same one that changed the previous ON ratio (lower the previous ON ratio, lower it again, and increase the previous ON ratio) If you do, increase it). Conversely, if the generated power is smaller than the previously calculated power, change the ON ratio to the opposite of the previous ON ratio change (the higher the previous ON ratio, the higher the previous ON ratio) If so, lower).

  The control circuit 44 generates a PWM signal for conducting / interrupting the switching elements of the inverter circuits 42a to 42c so that a plurality of output powers detected by the output current sensors 53a to 53c are the same as the generated power.

  Specifically, the control circuit 44 calculates the output current command values Ita to Itc of the respective inverter circuits 42a to 42c, when the description is facilitated assuming that the voltage of the commercial system supplied to each consumer is the same, A PWM signal that outputs the output voltage of the inverter circuits 42a to 42c is generated so that the detected output current matches the output current command value. In consideration of the AC voltage on the consumer side, the power output from the inverter circuit may be controlled according to the distribution ratio.

  When the ratio (distribution ratio) of the electric power Pa to Pc for distributing the generated electric power Pi of the solar cell 10 to the consumers 2a to 2c is represented by ra to rc, the output current command values Ita to Itc of the inverter circuits 42a to 42c Can be computed as follows. The distribution ratios ra to rc are configured so that the distribution ratios ra to rc agreed between the consumers 2a to 2c can be freely set.

  First, the relationship between the electric power Pa to Pc distributed to each consumer 2a to 2c, the distribution cost ra to rc, and the input power is Pn = rn × Pi (n = a, b, c). And since the electric power distributed to each consumer 2a-2c is Pn = In * Vn (n = a, b, c), the electric current value (output current command value) Ita- which should be made to output to each inverter circuit 2a-2c Itc is Ia to Ic at this time. In summary, the output current command value is Itn = rn × Pi / Vn (n = a, b, c). Note that the values Va to Vc detected by the output voltage sensor 54 can be used for Vn. However, since the voltage of the commercial power system 3 is determined in advance, a voltage may be used.

For example, the generated power Pi of the solar cell 10 is 4000 [W], the voltage Vn (Va = Vb = Vc) of the commercial power system 3 is 200 [V], and the ratio of the distribution ratio to each consumer 2a to 2c ( When ra: rb: rc) is 1/4: 1/4: 1/2, the output current command values Ita to Itc are as follows.
Ita = ra × Pi / Va = 5 [A]
Itb = rb × Pi / Vb = 5 [A]
Itc = rc × Pi / Vc = 10 [A]

When the control circuit 44 obtains the output current command values Ita to Itc, the inverter circuits 42a to 42c output voltages such that the difference between the output current command values Ita to Itc and the output current sensors 53a to 53c becomes zero, respectively. Such a PWM signal is generated and supplied to the switching elements of the inverter circuits 42a to 42c. As a result, AC power distributed at a predetermined distribution ratio is supplied from each inverter circuit 42a to 42c to each consumer 2a to 2c (internal wiring of each consumer or a commercial power system connected to each consumer). .

  When the control circuit 44 is in an abnormal state in which power is not supplied from the commercial power system 3 to the indoor wirings 31a to 31c (for example, a breaker due to a power failure in the commercial power system 3 or leakage to the consumers 2a to 2c) 1), the first system connection relays 43a to 43c are opened and the second system connection relays 45a to 45c are short-circuited, and the indoor wirings 31a to 31c and the wattmeters 24a to 24c are connected. Bypassing, the generated power of the solar cell 1 is supplied from the inverter circuits 42 a to 42 c to the commercial power system 3.

  The control circuit 44 corresponds to the respective consumers 2a to 2c according to the three states, the first grid connection relays 43a to 43c, the second grid connection relays 45a to 45c, and the inverter circuits 42a to 42c. These operations are controlled every 42c. The three states are as follows: (A) The commercial power system 3 has a power failure, and the power supply from the commercial power system 3 to the indoor wirings 31a to 31c of the consumers 2a to 2c is stopped (hereinafter, a power failure state). (B) The state in which the commercial power system 3 is normally feeding the indoor wiring of the consumers 2a to 2c (hereinafter referred to as normal state), (C) The commercial power system 3 is in the feeding state, but the commercial power system 3 Is a state where power is not supplied to the indoor wiring of the consumers 2a to 2c (hereinafter referred to as an abnormal state).

  Therefore, the control circuit 44 has a function as a detection circuit (a power failure detection circuit, a normal state detection circuit, and an abnormal state detection circuit) that detects these three states. When detecting a power failure (power failure state) in the commercial power system 3, the control circuit 44 prohibits a short circuit of the second grid interconnection relay for supplying power to the commercial power system 3 that has detected the power failure. The control circuit 44 detects an abnormal state in which power is not supplied from the commercial power system 3 to the indoor wirings 31a to 31c (for example, a breaker due to a power failure in the commercial power system 3 or leakage of electricity to the customers 2a to 2c). And the like, the first system interconnection relays 43a to 43c are opened, the second system interconnection relays 45a to 45c are short-circuited, the indoor wirings 31a to 31c are bypassed, and the inverter circuits 42a to 42c are used. The generated power of the solar cell 1 is supplied from the line 42c to the commercial power system 3. In addition, when the control circuit 44 detects a normal state in which power is supplied from the commercial power system 3 to the indoor wirings 31a to 31c, the control circuit 44 short-circuits the first system connection relays 43a to 43c and uses them for the second system connection. Relays 45a to 45c are opened, and the generated power of solar cell 1 is supplied to indoor wirings 31a to 31c of consumers 2a to 2c. Details of these operations of the control circuit 44 and a method of detecting the three states will be described in detail below.

  FIG. 4 shows a control flowchart of the control circuit. For each of the blocks A, B, and C surrounded by the one-dot chain line, (A) a power failure state flowchart, (B) a normal state flowchart, and (C) an abnormal state flowchart are shown. This flowchart shows the operations of the first grid connection relays 43a to 43c, the second grid connection relays 45a to 45c, and the inverter circuits 42a to 42c corresponding to the respective consumers 2a to 2c. First, the first system interconnection relay 43a, the second system interconnection relay 45a, and the inverter circuit 42a corresponding to the customer 2a will be described.

  When the solar cell 10 can generate power and can be supplied with power, first, the operation shifts to a power failure state operation. That is, the block A also becomes a starting point for starting the operation when the solar cell 10 can generate power and can supply power.

  When the operation block A is shifted to the power failure state, the second system interconnection relay 45a is prohibited from being short-circuited, and the inverter circuit 42a is gate-blocked (step S11). Next, it is determined whether or not the commercial power system 3 that supplies power to the customer 2a is in a power failure state (step S12). This determination is made by referring to the system voltage Vca detected by the system voltage sensor 55a. That is, when the system voltage Vca is not a predetermined voltage (for example, 50 Hz, 100 V, etc. defined by the commercial power system) (when there is an abnormality), it can be determined that there is a power failure. If it is determined in step S12 that the commercial power system 3 that supplies power to the customer 2a is in a power failure state, power is not supplied from the inverter circuit 42a to the commercial power system 3 or the indoor wiring 31a. Repeat the determination of S12.

  If it is determined in step S12 that there is no power failure, the short circuit prohibition of the second system interconnection relay 45a is canceled, the gate block of the inverter circuit 42a is released (step S13), and the indoor wiring 31a of the customer 2a is abnormal. It is determined whether it is in a state (step S14). This determination is made by referring to the indoor wiring voltage Vwa detected by the indoor wiring voltage sensor 56a. That is, when the indoor wiring voltage Vwa is not a predetermined voltage (for example, 50 Hz or 100 V defined by the commercial power system), it can be determined as an abnormal state. If it is determined in step S12 that the commercial power system 3 that supplies power to the customer 2a is in an abnormal state, the process proceeds to block C in the abnormal state. If it is determined in step S12 that the commercial power system 3 that supplies power to the customer 2a is in a normal state, the process proceeds to block B in a normal state.

  When shifting to the block B in the normal state, the operation of the inverter circuit 42a is started (step S21), and the first system interconnection relay 43a is short-circuited (step S22). Thereby, supply of the generated electric power of the solar cell 10 starts from the inverter circuit 42a to the indoor wiring 31a of the consumer 2a. Next, it is determined whether or not the commercial power system 3 that supplies power to the customer 2a is in a power failure state (step S23). This determination may be the same as that in block A, but with AC power supplied from the inverter circuit to the wiring that does not supply power from the commercial power system 3 used in the conventional grid interconnection device. This can be determined by using an isolated operation detection function for detecting whether or not there is. Specifically, when a single operation state is detected in a plurality of consumers 2a to 2c, it is unlikely that a plurality of consumers have leaked electric power at the same time, so it is determined that the commercial power system 3 is out of power. can do.

  When a power failure state is detected in step S23, the first system interconnection relay 43a is opened to stop the inverter circuit, and the process proceeds to block A (step S11) in a power failure state. When the power failure state is not detected in step S23, it is determined whether the indoor wiring 31a of the customer 2a is in an abnormal state (step S24). When this determination is performed in the block B, since power is being supplied from the inverter circuit 42a to the indoor wiring 31a, it may be determined by using the isolated operation detection function. If it is determined in step S24 that the state is not abnormal, the process returns to step S23. If it is determined that the state is abnormal, the first system interconnection relay 43a is opened to stop the inverter circuit 42a. Transition to block C at the time of the state.

  When the block C is shifted to the abnormal state, the operation of the inverter circuit 42a is started (step S31), and the second grid connection relay 45a is short-circuited (step S32). Thereby, supply (power sale) of the generated power of the solar cell 10 starts directly from the inverter circuit 42a to the commercial power system 3. Next, it is determined whether or not the commercial power system 3 that supplies power to the customer 2a is in a power failure state (step S33). When this determination is performed in the block C, since power is being supplied from the inverter circuit 42a to the indoor wiring 31a, it may be determined by using the isolated operation detection function.

  When a power failure state is detected in step S33, the second system interconnection relay 45a is opened to stop the inverter circuit, and the process proceeds to block A (step S11) in a power failure state. When the power failure state is not detected in step S33, it is determined whether the indoor wiring 31a of the customer 2a is in an abnormal state (step S34). When this determination is performed in the block B, as in the block C, the indoor wiring voltage Vwa detected by the indoor wiring voltage sensor 56a is referred to. That is, when the indoor wiring voltage Vwa is not a predetermined voltage (for example, 50 Hz or 100 V defined by the commercial power system), it can be determined as an abnormal state. If it is determined in step S24 that the state is abnormal, the process returns to step S33. If it is determined that the state is abnormal, the second grid interconnection relay 45a is opened to stop the inverter circuit 42a. Move to block B in normal state.

  In this manner, power based on the output current detected by each of the current sensors 53a to 53c is supplied to each of the indoor wirings 31a to 31c or the commercial power system 3 based on the predetermined distribution ratio ra to rc. The plurality of inverter circuits 42a to 42c are individually operated.

  As described above, according to the embodiment of the present invention, the output currents of the inverter circuits 42a to 42c that supply power to the consumers 2a to 2c are determined to distribute the generated power of the solar cell 10. Do the operation to become. Thereby, the electric power which distributed the generated electric power of the solar cell 10 will be supplied to each consumer 2a-2b, and the frequency | count of supplying / cutting off also decreases. For this reason, the burden concerning the indoor wiring 31a-31c of the consumers 2a-2c can be reduced.

  Further, according to the present embodiment, when power is not supplied to the indoor wiring 31 from the commercial power system 3, the first wiring interconnection relay 43 opens between the indoor wiring 31 and the inverter circuit 42, Bypassing the indoor wiring 31, the second system interconnection relay 45 connecting the commercial power system 3 and the inverter circuit 42 is short-circuited. For this reason, it is possible to sell power to the commercial power system 3 by bypassing the indoor wiring 11 of the customer 2 in which the abnormality has occurred, while separating the customer 2 and the power converter 11 in which the abnormality has occurred. That is, the customer 2 in which an abnormality has occurred can use the power generated by the solar cell 10 in the form of power sale.

  In addition, according to the present embodiment, the second system interconnection relay 45 is short-circuited between the inverter circuit 42 and the first system interconnection relay 43 and between the distribution board 21 and the power sale meter 23. / Since it is opened, a common power meter can be used for the abnormal state and the normal state.

  Further, according to the present embodiment, a power failure detection circuit is provided, and when a power failure is detected, a short circuit of the second grid interconnection relay 42 is prohibited. Thereby, it can prevent supplying electric power to the commercial power grid 3 accidentally at the time of a power failure.

  Further, according to the present embodiment, detection of a power failure by the system voltage sensor 55 has been described. That is, since the power failure can be detected by the system voltage sensor 55 provided in the power converter 11, it is not necessary to separately provide a voltage sensor in the commercial power system 3 and perform communication or the like.

  Moreover, according to this embodiment, when there is no supply of electric power from the commercial power system 3 to the indoor wirings 31a to 31c of the plurality of consumers 2a to 2c, whether or not electric power is supplied from the inverter circuit 42 is determined. To detect. That is, when a single operation is detected in a plurality of consumers, a power failure is detected. Thereby, since a power failure can be detected using the sensor in the power converter 11, it is not necessary to separately provide a voltage sensor in the commercial power system 3 and perform communication or the like.

  As mentioned above, although one Embodiment of this invention was described, the above description is for making an understanding of this invention easy, and does not limit this invention. It goes without saying that the present invention can be changed and improved without departing from the gist thereof, and that the present invention includes equivalents thereof.

  For example, in this embodiment, the solar cell 10 installed in one place was used as a common generator, but for example, a common power conversion device 11 is provided in a plurality of houses, and the power generation of these solar cells 10 is performed. When the power is collected and the generated power of the collected solar cell 10 is distributed by the inverter circuits 42a to 42c, it can be considered that a common generator is used.

  For example, in this embodiment, although the solar cell 10 was used as a generator, it is possible to use various generators, such as a fuel cell, a storage battery, a wind power generator, and an engine generator.

For example, in this embodiment, when an abnormal state is seen for each consumer, an inverter circuit, a first grid interconnection relay, a second grid corresponding to the consumer in which the abnormality is seen Although the interconnection relay is operated, it may be configured to operate as follows.
When an abnormal state in which power is not supplied from the commercial power system 3 to at least one consumer among the indoor wirings 31a to 31c of the plurality of consumers 2a to 2c (when isolated operation is detected), all The inverter circuits 42a to 42c are temporarily stopped, and after the temporary stop, the indoors 31a to 31c of the plurality of consumers 2a to 2c are supplied with electric power from the commercial power system 3 (in a normal state). The operation of the inverter circuit that supplies power to the wiring is configured to be restartable.

When a single operation state is detected in a certain consumer, there is a possibility that another customer may be operating alone because the detection is delayed. By doing in this way, it is possible to deal with isolated operation quickly in other consumers. In addition, since the operation of the inverter circuit can be resumed where the other customer has not detected the isolated operation, the operation of the inverter circuit can be resumed promptly.

DESCRIPTION OF SYMBOLS 1 Power conversion system 2 Consumer 3 Commercial power grid 10 Solar cell 11 Power converter 21 Distribution board 22 Electricity meter (3rd power measuring device)
23 Power meter (second power meter)
24 Wattmeter (first power meter)
30 Load 31 Indoor wiring 41 Booster circuit 42 Inverter circuit 43 Relay for first system connection (first switch)
44 Control circuit 45 Second system interconnection relay (second switch)
51 Input Current Sensor 52 Input Voltage Sensor 53 Output Current Sensor 54 Output Voltage Sensor 55 System Voltage Sensor 56 Indoor Wiring Voltage Sensor Ii Input Current Vi Input Voltage rn Distribution Ratio

Claims (6)

The power supply from the generator provided in common to the indoor wiring of a plurality of consumers configured to be able to supply power from the commercial power system and power generated by a generator different from the system is controlled. In the power conversion system,
A plurality of inverter circuits that convert the generated power of the generator into controlled alternating current power and supply the power to the indoor wiring of each of the plurality of consumers via a separate first power meter;
A first switch provided between the output side of the inverter circuit and the first power meter, and short-circuiting / opening between the inverter circuit and the customer's indoor wiring;
A second opening / closing circuit provided between the inverter circuit and the first switch and the commercial power system via a second power meter to short-circuit / open the inverter circuit and the commercial power system. Equipped with
When there is an abnormality in the indoor wiring, the first switch is opened to short-circuit the second switch, the first power meter is bypassed, and the inverter circuit is connected to the commercial power system. A power conversion system that supplies generated power. The consumer inputs AC power supplied by the commercial power grid via a third power meter, inputs AC power supplied by the inverter circuit via a first power meter, and A distribution board for distributing the input power to a load connected to the indoor wiring;
A power meter is provided on the input side of the commercial power system of the distribution board so as to detect power flowing backward from the indoor wiring to the commercial power system,
2. The second switch according to claim 1, wherein the second switch short-circuits / opens between the inverter circuit and the first switch and between the distribution board and the second power measuring device. The described power conversion system. A power failure detection circuit for detecting a power failure in the commercial power system,
The power conversion system according to claim 1 or 2, wherein when the power failure detection circuit detects a power failure, a short circuit of the second switch is prohibited. A voltage sensor provided on the commercial power system side of the second switch for detecting the voltage of the commercial power system;
4. The power conversion system according to claim 3, wherein the power failure detection circuit detects a power failure when the voltage detected by the voltage sensor is abnormal. The power failure detection circuit detects whether or not power is supplied from the inverter circuit when power is not supplied from the commercial power system to the indoor wiring of the plurality of consumers.
When power is supplied from the inverter circuit when power is not supplied from the commercial power system to indoor wiring of a plurality of consumers, it is determined that the commercial power system is out of power. The power conversion system according to claim 3. When the power failure detection circuit detects that power is not being supplied from the commercial power system to at least one of the indoor wirings of the plurality of consumers, all inverter circuits are temporarily stopped, After the stop, the operation of the inverter circuit that supplies power to the indoor wiring of the customer that is supplied with power from the commercial power system among the indoor wiring of the plurality of consumers is configured to be resumable. The power conversion system according to claim 5.

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