Power systems and inverter devices

Abstract

To provide a power system that excellently performs control of an autonomous operation, when parallelly operating a plurality of distributed power supplies.SOLUTION: A power system S1 comprises a plurality of inverter devices A each for supplying power to a load. The inverter devices A each comprise a measurement part 1, a first calculation part 31, a second calculation part 32, a first setting part 41, a second setting part 42, a control part 5, and a communication part 2. The first calculation part 31 produces an active power internal value and calculates an average value of an active power output measured by each of the inverter devices A. The second calculation part 32 produces a reactive power internal value and calculates an average value of a reactive power output measured by each of the inverter devices A. The first calculation part 31 produces a new active power internal value, using a calculation result based on a produced active power internal value and a received active power internal value. The second calculation part 32 produces a new reactive power internal value, using a calculation result based on a produced reactive power internal value and a received reactive power internal value.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present disclosure relates to a power system and an inverter device. [Background technology]

[0002] In recent years, research on distributed power sources using solar cells, storage batteries, etc. Generally, a distributed power source is connected to a power grid, and performs power control by using the phase of the system voltage of the power grid as its own internal phase (for example, Patent Document 1).

[0003] A distributed power source may operate independently when it cannot be connected to the power grid due to a power outage, etc. In this case, since the distributed power source cannot detect the phase from the system voltage of the power grid, it oscillates its own internal phase and uses this to control the output voltage. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2010-68630 A [Patent Document 2] JP 2015-166901 A [Patent Document 3] JP 2018-121189 A Summary of the Invention [Problem to be solved by the invention]

[0005] Multiple distributed power sources may be connected in parallel and operated (parallel operation). In this case, appropriate control of the independent operation is required depending on the number, rated capacity, or type of the distributed power sources. However, in a system in which one of the multiple distributed power sources operates as a voltage source and the others operate as current sources, only the distributed power source that acts as a voltage source immediately follows the load, so a load that exceeds the capacity of the distributed power source that acts as a voltage source cannot be connected. As a countermeasure to this problem, the distributed power source that acts as a current source must also follow the load at the same processing speed as the distributed power source that acts as a voltage source, and the distributed power source that acts as a current source is required to perform extremely high-speed calculations and control. In addition, in a system in which all of the multiple distributed power sources operate as voltage sources, potential differences and phase differences occur due to communication during synchronization between the multiple distributed power sources and measurement errors in each distributed power source, and these potential differences and phase differences become problems. For example, not only does an inrush current occur when the power source is turned on, but unintended leakage of active power and reactive power occurs between the multiple distributed power sources.

[0006] The present disclosure has been made in view of the above circumstances, and has an object to provide a power system that satisfactorily controls isolated operation when multiple distributed power sources are operated in parallel, and also to provide an inverter device that realizes a power system that satisfactorily controls isolated operation. [Means for solving the problem]

[0007] A power system provided by a first aspect of the present disclosure includes a plurality of inverter devices that supply power to a load, each of the plurality of inverter devices includes a measurement unit that measures an active power output and a reactive power output, a first calculation unit that generates an active power internal value based on the active power output and calculates an average value of the active power output measured by each of the plurality of inverter devices, a second calculation unit that generates an active power internal value based on the reactive power output and calculates an average value of the reactive power output measured by each of the plurality of inverter devices, a first setting unit that sets an active power target value using the average value of the active power output, a second setting unit that sets a reactive power target value using the average value of the reactive power output, and an output power calculation unit that calculates an output power based on the measured value of the active power output and the active power target value, and the measured value of the reactive power output and the reactive power target value. and a communication unit that transmits internal values ​​including the generated internal active power value and the generated internal reactive power value to at least one of the other inverter devices and receives the internal values ​​of the inverter device from the at least one of the other inverter devices, wherein the first calculation unit performs a first calculation process to generate a new internal active power value using a calculation result based on the generated internal active power value and the received internal active power value, and the internal active power value converges to an average value of the active power output as the first calculation process is repeated, and the second calculation unit performs a second calculation process to generate a new internal reactive power value using a calculation result based on the generated internal reactive power value and the received internal reactive power value, and the internal reactive power value converges to the average value of the reactive power output as the second calculation process is repeated.

[0008] In a preferred embodiment of the power system, the power system further includes a first acquisition unit that acquires a rated capacity of its own device, and a third calculation unit that generates a rated capacity internal value based on the rated capacity and calculates an average value of the rated capacities of the multiple inverter devices, wherein the internal value further includes the rated capacity internal value, the first setting unit further uses the average value of the rated capacity to set the active power target value, the second setting unit further uses the average value of the rated capacity to set the reactive power target value, and the third calculation unit performs a third calculation process to generate a new rated capacity internal value using a calculation result based on the generated rated capacity internal value and the received rated capacity internal value, and the rated capacity internal value converges to the average value of the rated capacity as the third calculation process is repeated.

[0009] In a preferred embodiment of the power system, the power system further includes a number search unit that searches for a number of the plurality of inverter devices, and a distribution ratio calculation unit that calculates a distribution ratio for the inverter devices of the own device, wherein the number search unit generates an internal value for number search and searches for the number of the plurality of inverter devices using the internal value for number search, the first setting unit calculates a total active power value by multiplying the average value of the active power output by the number of devices, and sets a value obtained by distributing the total active power value by the distribution ratio as the active power target value, and the second setting unit calculates a total reactive power value by multiplying the average value of the reactive power output by the number of devices, and sets a value obtained by distributing the total reactive power value by the distribution ratio as the reactive power target value.

[0010] In a preferred embodiment of the power system, the plurality of inverter devices include a plurality of storage battery control devices each connected to a storage battery, and the plurality of storage battery control devices further include a second acquisition unit that acquires a storage battery capacity and a charging rate of the storage battery connected to the storage battery control device itself, a fourth calculation unit that generates a storage battery capacity internal value based on the storage battery capacity and calculates an average value of the storage battery capacities of the plurality of inverter devices, and a fifth calculation unit that generates a charging rate internal value based on the charging rate and calculates an average value of the charging rates of the storage batteries connected to the plurality of storage battery control devices, the internal values ​​further including the storage battery capacity internal value and the charging rate internal value, and the first setting unit of the storage battery control device further sets the rated capacity and the charging rate acquired by the second acquisition unit. the fourth calculation unit performs a fourth calculation process to generate a new internal battery capacity value using a calculation result based on the generated internal battery capacity value and the received internal battery capacity value, and the internal battery capacity value converges to the average value of the battery capacity as the fourth calculation process is repeated; the fifth calculation unit performs a fifth calculation process to generate a new internal battery capacity value using a calculation result based on the generated internal battery capacity value and the received internal battery capacity value, and the internal battery capacity value converges to the average value of the battery capacity as the fifth calculation process is repeated.

[0011] An inverter device provided by a second aspect of the present disclosure is an inverter device that supplies power to a load together with at least one or more other inverter devices, the inverter device including: a measurement unit that measures an active power output and a reactive power output; a first calculation unit that generates an active power internal value based on the active power output and calculates an average value of the active power output measured in each of the plurality of inverter devices; a second calculation unit that generates a reactive power internal value based on the reactive power output and calculates an average value of the reactive power output measured in each of the plurality of inverter devices; a first setting unit that sets an active power target value using the average value of the active power output; a second setting unit that sets a reactive power target value using the average value of the reactive power output; The inverter device includes a control unit for controlling power, and a communication unit for transmitting internal values ​​including the generated internal active power value and the generated internal reactive power value to at least one of the other inverter devices and receiving the internal values ​​of the inverter device from the at least one of the other inverter devices, wherein the first calculation unit performs a first calculation process to generate a new internal active power value using a calculation result based on the generated internal active power value and the received internal active power value, and the internal active power value converges to the average value of the active power output as the first calculation process is repeated, and the second calculation unit performs a second calculation process to generate a new internal reactive power value using a calculation result based on the generated internal reactive power value and the received internal reactive power value, and the internal reactive power value converges to the average value of the reactive power output as the second calculation process is repeated. Effect of the Invention

[0012] According to the power system of the present disclosure, when multiple inverter devices are operated in parallel, the operation of each inverter device can be controlled so that the output power (active power and reactive power) of each inverter device is appropriately distributed. This enables the power system to appropriately control the independent operation according to the number of inverter devices, the rated capacity, or the type of DC power source, and thus allows the independent operation to be well controlled.

[0013] Other features and advantages of the present disclosure will become more apparent from the following detailed description taken in conjunction with the accompanying drawings. [Brief description of the drawings]

[0014] [Figure 1] 1 is a diagram illustrating an example of the overall configuration of a power system according to a first embodiment. [Diagram 2] FIG. 2 is a graph illustrating the power system according to the first embodiment. [Diagram 3] 2 is a diagram illustrating a detailed configuration example of the inverter device according to the first embodiment. FIG. [Figure 4] FIG. 11 is a diagram illustrating a detailed configuration example of an inverter device according to a second embodiment. [Diagram 5] FIG. 11 is a diagram illustrating an example of the overall configuration of a power system according to a third embodiment. [Figure 6] FIG. 13 is a diagram illustrating a detailed configuration example of a storage battery control device according to a third embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A preferred embodiment of a power system and an inverter device according to the present disclosure will be described below with reference to the drawings. In the following, identical or similar components are designated by the same reference numerals and duplicated descriptions will be omitted.

[0016] FIG. 1 shows an example of the overall configuration of a power system S1 according to a first embodiment. As shown in the figure, the power system S1 includes n (n is a natural number) inverter devices A. In the example shown in FIG. 1, the power system S1 includes five inverter devices A. When the five inverter devices A are to be distinguished from one another, they are referred to as inverter devices A1 to A5. In FIG. 1, a thick line indicates a power connection line, and a dotted arrow indicates that the inverter devices A communicate with each other. As shown in FIG. 1, the power system S1 includes a plurality of inverter devices A (A1 to A5) electrically connected in parallel with one another. The power system S1 performs an independent operation (non-grid operation) in a state where the power system S1 is disconnected from a power system K. The power system S1 controls the independent operation by each of the plurality of inverter devices A operating in a cooperative and distributed manner. During the independent operation, power is supplied from the plurality of inverter devices A to a load L.

[0017] As shown in Fig. 1, a DC power supply 9 is connected to each of the multiple inverter devices A. The DC power supply 9 is, for example, a generator that uses renewable energy such as a solar cell, a generator that uses an internal combustion engine or an external combustion engine, or a storage battery. Each inverter device A appropriately converts and outputs the power generated by the DC power supply 9 or the power stored in the DC power supply 9. Instead of the DC power supply 9, an AC power supply may be connected to each inverter device A via a rectifier circuit.

[0018] Each of the multiple inverter devices A can communicate with at least one of the other inverter devices A. FIG. 2 shows a graph representing the communication connection state of the multiple inverter devices A. In each graph of FIG. 2, five vertices represent five inverter devices A1 to A5, and the sides with arrows represent the communication state between the inverter devices A. Each side indicates that mutual communication is performed. In the power system S1, the multiple inverter devices A communicate with each other in a connection relationship shown in FIG. 2(a), for example. As shown in FIG. 2(a), a communication path exists between any two vertices (inverter devices A) in the graph, so the graph is connected. The communication between the inverter devices A in the power system S1 is not limited to the connection relationship shown in FIG. 2(a), and may be the connection relationship shown in FIG. 2(b) and (c). The graphs shown in FIG. 2(b) and (c) are also connected. In this way, it is sufficient that each inverter device A communicates with at least one of the multiple inverter devices A and that a communication path exists (connected state) for any two inverter devices A in the power system S1, and it is not necessary for all inverter devices A to communicate with each other. Also, as shown in Fig. 2(d), when the two inverter devices A1 and A4 are out of service, communication may be performed by the three inverter devices A2, A3, and A5. In this case, the three inverter devices A2, A3, and A5 control the independent operation.

[0019] 3 shows a detailed configuration example of each of the multiple inverter devices A. As shown in the figure, each of the multiple inverter devices A includes a measurement unit 1, a communication unit 2, a processing unit 3, a setting unit 4, a control unit 5, and an inverter circuit INV.

[0020] The measurement unit 1 measures the active power output value and the reactive power output value of each inverter device A as an active power measurement value Pout and a reactive power measurement value Qout. The measurement unit 1 outputs the active power measurement value Pout and the reactive power measurement value Qout to the processing unit 3 and the control unit 5, respectively.

[0021] The communication unit 2 communicates with other inverter devices A. The communication method may be wireless communication or wired communication. The communication unit 2 includes a transmission unit 21 and a reception unit 22. The transmission unit 21 transmits an internal value, which will be described later, to the other inverter devices A with which it can communicate. The transmission unit 21 receives the internal value from the processing unit 3. The reception unit 22 receives the internal value, which will be described later, from the other inverter devices A with which it can communicate. The reception unit 22 outputs the received internal value to the processing unit 3.

[0022] The processing unit 3 calculates a state value representing an electrical state and a physical state of the power system S1. The state value is for each inverter device A to perform distributed and cooperative autonomous operation control. In this embodiment, the state value calculated by the processing unit 3 includes an average value of an active power output (active power average value) and an average value of a reactive power output (reactive power average value) of each inverter device A, as well as the number of inverter devices A. The processing unit 3 generates an internal value in each inverter device A to calculate the state value. The processing unit 3 transmits the generated internal value to other inverter devices via the transmitting unit 21, and receives the internal value from the other inverter devices A via the receiving unit 22. The processing unit 3 performs an operation of the following formula (1) using the generated internal value Xi and each internal value Xj received by the receiving unit 22, and generates a new internal value Xi. The internal value Xi is an internal value generated in the own device (i-th inverter device A), where i is a natural number from 1 to n. The internal value Xj is an internal value received from the j-th inverter device A among the other inverter devices A, where j is a natural number from 1 to n-1. The coefficient ε is a value that satisfies 0<ε<1 / dmax. dmax is the number of internal values ​​Xj received by the receiver 22, even though the inverter device A communicates with the largest number of other inverter devices A among the multiple inverter devices A. The coefficient ε is used to suppress excessive fluctuations in the internal value Xi, and if the processing in the processor 3 is a continuous time process, it is not necessary to multiply the coefficient ε. The coefficient α is set to "1" or "0." The coefficient α is set to "1" for the internal value Xj received by the receiver 22, and the coefficient α is set to "0" for the internal value Xj not received. The processor 3 repeatedly performs the calculation process of the following formula (1). By repeating this calculation process, the internal value Xi and the internal value Xj converge to the arithmetic mean value of the initial value of the internal value Xi generated by each inverter device A. This can be understood from the technical idea described in Patent Document 2. In this embodiment, the internal values ​​include an active power internal value based on an active power output, a reactive power internal value based on a reactive power output, and an internal value for number search for searching the number of the plurality of inverter devices A. The processing unit 3 includes a first calculation unit 31, a second calculation unit 32, and a number search unit 39.

number

[0023] The first calculation unit 31 calculates an active power average value by repeatedly performing a calculation process (first calculation process) for generating an active power internal value. The first calculation unit 31 sets an initial value of the active power internal value by using the active power measurement value Pout input from the measurement unit 1. This initial value is updated when the active power measurement value in the measurement unit 1 is updated. In the inverter device A in which the active power measurement value is updated, the difference between the updated active power measurement value Pout(t) and the previous active power measurement value Pout(t-1) is added to the active power internal value Pi, so that the active power internal value becomes the updated initial value. In the first calculation process, the first calculation unit 31 generates a new active power internal value Pi by using a calculation result based on the generated active power internal value Pi and each active power internal value Pj input from the receiving unit 22. Specifically, in the first calculation process, a calculation is performed using the active power internal value Pi as the internal value Xi and the active power internal value Pj as the internal value Xj in the above formula (1). The newly generated internal active power value Pi is output to the transmitting unit 21 and is used in the next first calculation process. By repeating such a first calculation process, the internal active power value converges to the arithmetic mean value of the active power outputs of the multiple inverter devices A. The first calculation unit 31 outputs the converged internal active power value to the setting unit 4 as the active power average value.

[0024] The second calculation unit 32 calculates a reactive power average value by repeatedly performing a calculation process (second calculation process) for generating a reactive power internal value. The second calculation unit 32 sets an initial value of the reactive power internal value by using the reactive power measurement value Qout input from the measurement unit 1. This initial value is updated when the reactive power measurement value in the measurement unit 1 is updated. In the inverter device A in which the reactive power measurement value is updated, the difference between the updated reactive power measurement value Qout(t) and the previous reactive power measurement value Qout(t-1) is added to the reactive power internal value Qi, so that the reactive power internal value becomes the updated initial value. In the second calculation process, the second calculation unit 32 generates a new reactive power internal value Qi by using a calculation result based on the generated reactive power internal value Qi and each reactive power internal value Qj input from the receiving unit 22. For example, in the second calculation process, a calculation is performed using the reactive power internal value Qi as the internal value Xi and the reactive power internal value Qj as the internal value Xj in the above formula (1). The newly generated internal reactive power value Qi is output to the transmitting unit 21 and is used in the next second calculation process. By repeating such second calculation process, the internal reactive power value converges to the arithmetic mean value of the reactive power outputs of the multiple inverter devices A. The second calculation unit 32 outputs the converged internal reactive power value to the setting unit 4 as the reactive power average value.

[0025] The number search unit 39 searches for the number of multiple inverter devices A by repeatedly performing a calculation process (number search calculation process) for generating an internal value for number search. The number search unit 39 sets, for example, "0" or "1" as an initial value of the internal value for number search. The initial value of the internal value for number search is basically "0", but is "1" in any one of the multiple inverter devices A. Note that the initial value of the internal value for number search may be "1" in any inverter device A. The number search unit 39 generates the internal value for number search with an initial value of "0" or "1" at the time of system startup of the power system S1, or at the time of transition from grid-connected operation to independent operation (at the start of independent operation), for example. Then, in the number search calculation process, the number search unit 39 generates a new internal value for number search using a calculation result based on the generated internal value for number search and each internal value for number search input from the receiving unit 22. In the number search calculation process, in the above formula (1), the internal value for number search generated by the number search unit 39 is used as the internal value Xi, and the internal value for number search received by the receiving unit 22 is used as the internal value Xj. The newly generated internal value for number search is output to the transmitting unit 21 and is used in the next number search calculation process. By repeating such a number search calculation process, the internal value for the number search unit converges to the reciprocal 1 / n of the number n of the multiple inverter devices A. As a result, the number search unit 39 calculates the reciprocal of the internal value for number search as the number n of the multiple inverter devices A. It is understood from the technology described in Patent Document 3 that the number of the multiple inverter devices A is specified by the above method. The number search unit 39 outputs the number n of the multiple inverter devices A that it has searched for to the setting unit 4. The number search unit 39 may store information on the number n of the searched units in a storage unit, or may perform a number search at a predetermined timing.

[0026] The setting unit 4 sets a target value of an active power output and a target value of a reactive power output in each inverter device A. The setting unit 4 includes a first setting unit 41, a second setting unit 42, and a distribution ratio calculation unit 43.

[0027] The distribution ratio calculation unit 43 calculates the distribution ratio for each inverter device A. The distribution ratio calculation unit 43 calculates the reciprocal 1 / n of the number n of the multiple inverter devices A as the distribution ratio for each inverter device A. Information on the number n of the multiple inverter devices A is input from the number search unit 39. The distribution ratio calculation unit 43 outputs the calculated distribution ratio to the first setting unit 41 and the second setting unit 42.

[0028] The first setting unit 41 sets a target value of the active power output (active power target value Pref) by using the active power average value input from the first calculation unit 31. As shown in FIG. 3, the first setting unit 41 includes a multiplier 411 and a distribution unit 412. The multiplier 411 multiplies the active power average value by the number n of the inverter devices A input from the unit number search unit 39 to calculate a total value of the active power output of the inverter devices A (total active power value). The distribution unit 412 divides the total active power value (the multiplication result of the multiplier 411) by a distribution rate input from the distribution rate calculation unit 43 to distribute the total active power value to each inverter device A. In this embodiment, the distribution rate is the reciprocal 1 / n of the number n of the inverter devices A, so that the distribution unit 412 distributes the total active power value equally to each inverter device A. The first setting unit 41 sets the output (division result) of the distribution unit 412 as the active power target value Pref, and outputs the set active power target value Pref to the control unit 5.

[0029] The second setting unit 42 sets a target value of the reactive power output (reactive power target value Qref) by using the reactive power average value input from the second calculation unit 32. As shown in FIG. 3, the second setting unit 42 includes a multiplier 421 and a distribution unit 422. The multiplier 421 multiplies the reactive power average value by the number n of the inverter devices A input from the unit number search unit 39 to calculate a total value of the reactive power output of the inverter devices A (reactive power total value). The distribution unit 422 divides the reactive power total value (the multiplication result of the multiplier 421) by the distribution rate input from the distribution rate calculation unit 43 to distribute the reactive power total value to each inverter device A. In this embodiment, the distribution rate is the reciprocal 1 / n of the number n of the inverter devices A, so that the distribution unit 422 distributes the active power total value equally to each inverter device A. The second setting unit 42 sets the output (division result) of the distribution unit 422 as the reactive power target value Qref, and outputs the set reactive power target value Qref to the control unit 5.

[0030] The control unit 5 controls the output power of the inverter circuit INV based on the active power measurement value Pout, the active power target value Pref, and the reactive power measurement value Qout, and the reactive power target value Qref. The inverter circuit INV is disposed between a DC power source 9 and the measurement unit 1, and converts the power input from the DC power source 9 into DC power and outputs it. The control unit 5 includes a first calculation unit 51, a second calculation unit 52, a phase control unit 53, and an amplitude control unit 54.

[0031] The first calculation unit 51 receives an active power measurement value and an active power target value, and generates a voltage phase command value. As shown in FIG. 3, the first calculation unit 51 includes a difference calculator 511 and a controller 512. The active power target value and the active power measurement value are input to the difference calculator 511, and the difference calculator 511 calculates a deviation ΔP therebetween. The controller 512 calculates a voltage phase command value for making the deviation ΔP zero. The controller 512 performs, for example, any one of proportional control (P control), PI control, and PID control. The first calculation unit 51 outputs a voltage phase command value (output of the controller 512) to the phase control unit 53.

[0032] The second calculation unit 52 receives the reactive power measurement value and the reactive power target value, and generates a voltage amplitude command value. As shown in FIG. 3, the second calculation unit 52 includes a difference calculator 521 and a controller 522. The reactive power target value and the reactive power measurement value are input to the difference calculator 521, and calculates a deviation ΔQ therebetween. The controller 522 calculates a voltage amplitude command value for making the deviation ΔQ zero. The controller 522 performs, for example, any one of proportional control (P control), PI control, and PID control. The second calculation unit 52 outputs the voltage amplitude command value (output of the controller 522) to the amplitude control unit 54.

[0033] The phase control unit 53 controls the phase of the output voltage based on the voltage phase command value. When the voltage phase command value is a target value for the phase of the output voltage, the phase control unit 53 controls the phase of the output voltage to the voltage phase command value. When the voltage phase command value is an adjustment value for the phase of the output voltage, the phase control unit 53 adjusts the phase of the output voltage from the current value by the voltage phase command value.

[0034] The amplitude control unit 54 controls the amplitude of the output voltage based on the voltage amplitude command value. When the voltage amplitude command value is a target value for the amplitude of the output voltage, the amplitude control unit 54 controls the amplitude of the output voltage to the voltage amplitude command value. When the voltage amplitude command value is an adjustment value for the amplitude of the output voltage, the amplitude control unit 54 adjusts the amplitude of the output voltage from the current value by the voltage amplitude command value.

[0035] In the power system S1, the first calculation unit 31 calculates the average value (active power average value) of the active power output measured by each of the multiple inverter devices A. Then, the first setting unit 41 sets the active power target value using this active power average value. In this embodiment, the multiple inverter devices A have a value obtained by equally distributing the total value of each active power output of the multiple inverter devices A to each of the multiple inverter devices A (i.e., active power average value) set as the active power target value. Similarly, the second calculation unit 32 calculates the average value (reactive power average value) of the reactive power output measured by each of the multiple inverter devices A. Then, the second setting unit 42 sets the reactive power target value using the reactive power average value. In this embodiment, a value obtained by equally distributing the total value of each reactive power output of the multiple inverter devices A to each of the multiple inverter devices A (i.e., average value of reactive power output) is set as the reactive power target value. With this configuration, the output power (active power and reactive power) of each inverter device A is equalized by the multiple inverter devices A, and all the inverter devices A can be controlled to operate in the same way. Therefore, the power system S1 can suppress the phase difference and potential difference (amplitude difference) between the multiple inverter devices A even when each inverter device A is configured with a voltage type inverter. The leakage of active power occurs due to a phase shift in the output voltage of the inverter device A, and the leakage of reactive power occurs due to a shift in the amplitude of the output voltage of the inverter device A. In other words, the power system S1 can suppress the potential difference and phase difference between the multiple inverter devices A, and therefore can suppress unintended leakage of power in the multiple inverter devices A. Therefore, when multiple inverter devices A are operated in parallel, each of the multiple inverter devices A can perform appropriate independent operation according to the number of inverter devices A. In other words, the power system S1 makes it possible to control the independent operation appropriately according to the number of inverter devices A, and the independent operation of the power system S1 becomes good.

[0036] In the power system S1, the first calculation unit 31 repeatedly performs the first calculation process using the internal active power value, and the second calculation unit 32 repeatedly performs the second calculation process using the internal reactive power value. Each inverter device A communicates with at least one of the other inverter devices A, and the communication state of each inverter device A is in a connected state, so that the internal active power value and the internal reactive power value of all the inverter devices A converge to the average active power value and the average reactive power value, respectively. With this configuration, each inverter device A can calculate the average active power value and the average reactive power value without providing a management device for managing multiple inverter devices A in the power system S1. Then, each inverter device A sets an active power target value using the calculated average active power value, and sets a reactive power target value using the calculated average reactive power value to control the output power. As a result, the power system S1 can control the autonomous operation of the power system S1 without providing the above-mentioned management device, by each inverter device A controlling the output power in a cooperative and distributed manner. In addition, the power system S1 does not have the aforementioned management device, and controls the output power in a cooperative and decentralized manner through communication with other inverter devices A, making it easy to add and remove inverter devices A, thereby increasing the scalability of the system.

[0037] In a configuration different from the power system S1, the first setting unit 41 may not include the multiplier 411 and the distribution unit 412, and may set the active power average value input from the first calculation unit 31 as the active power target value Pref. The second setting unit 42 may not include the multiplier 421 and the distribution unit 422, and may set the reactive power average value input from the second calculation unit 32 as the reactive power target value Qref. In the power system S1, in the process of calculating the active power target value by the first setting unit 41, the active power average value is multiplied by the number n of units, and the multiplication result is multiplied by the reciprocal of the number n of units. That is, the calculated active power target value is the same as the active power average value. Therefore, the first setting unit 41 of this modification can set the same active power target value as the power system S1 without using information on the number n of units. This is also true in the process of calculating the reactive power target value by the second setting unit 42. In this modification, each inverter device A does not need to include the unit number searching unit 39 and the distribution rate calculating unit 43.

[0038] In a configuration different from the above-described power system S1, the number of units search unit 39 may output an internal value for number search (1 / n) converged by repeating the number of units search calculation process to the distribution rate calculation unit 43. In this case, the distribution rate calculation unit 43 sets the internal value for number search input from the number of units search unit 39 as the distribution rate.

[0039] A power system S2 according to the second embodiment will be described. Fig. 4 shows a detailed configuration example of each inverter device A. The overall configuration and communication connection relationship of the power system S2 are the same as the overall configuration (see Fig. 1) and communication connection relationship (see Fig. 2(a)) of the power system S1. However, unlike the power system S1, the power system S2 has at least one inverter device A among the multiple inverter devices A with a different rated capacity. In other words, the multiple inverter devices A include inverter devices with different rated capacities.

[0040] 4, each inverter device A of the power system S2 differs from each inverter device A of the power system S1 in the following points. First, an acquisition unit 6 is further included. Second, the processing unit 3 further includes a third calculation unit 33. Third, a distribution ratio calculation unit 43 calculates a distribution ratio according to the rated capacity of each inverter device A.

[0041] The acquisition unit 6 includes a first acquisition unit 61. The first acquisition unit 61 acquires the rated capacity of each inverter device A. Information on the rated capacity is stored, for example, in a storage unit (not shown). The first acquisition unit 61 outputs the acquired information on the rated capacity to the processing unit 3 and the setting unit 4.

[0042] The processing unit 3 of this embodiment further calculates, as a state value, an average value (average rated capacity value) of the rated capacity of each inverter device A. The processing unit 3 of this embodiment further generates, as an internal value, a rated capacity internal value based on the rated capacity.

[0043] The third calculation unit 33 calculates the rated capacity average value by repeatedly performing a calculation process (third calculation process) for generating the rated capacity internal value. The third calculation unit 33 sets the rated capacity acquired by the first acquisition unit 61 as an initial value of the rated capacity internal value. In the third calculation process, the third calculation unit 33 generates a new rated capacity internal value using a calculation result based on the generated rated capacity internal value and each rated capacity internal value input from the receiving unit 22. In the third calculation process, a calculation is performed using the generated rated capacity internal value as the internal value Xi and the rated capacity internal value received by the receiving unit 22 as the internal value Xj in the above formula (1). The newly generated rated capacity internal value is output to the transmitting unit 21 and is used in the next third calculation process. By repeating such a third calculation process, the rated capacity internal value converges to the arithmetic mean value of the rated capacities of the multiple inverter devices A. The third calculation unit 33 outputs the converged rated capacity internal value to the setting unit 4 as the rated capacity average value. The third calculation unit 33 may store the calculated rated capacity average value in a storage unit, or may calculate the rated capacity average value at each predetermined timing.

[0044] The distribution ratio calculation unit 43 of the power system S2 calculates, as a distribution ratio, the ratio of the rated capacity of each inverter device A to the total value of the rated capacities of the multiple inverter devices A (total rated capacity value). The distribution ratio calculation unit 43 includes a multiplier 431 and a divider 432. The multiplier 431 multiplies the average rated capacity value input from the third calculation unit 33 by the number of units n input from the unit number search unit 39 to calculate the total value of the rated capacities of the multiple inverter devices A (total rated capacity value). The divider 432 calculates the distribution ratio by dividing the rated capacity of its own device input from the first acquisition unit 61 by the total rated capacity value (the multiplication result of the multiplier 431).

[0045] In the power system S2, the distribution ratio calculation unit 43 calculates the ratio of the rated capacity of each inverter device A to the total value of the rated capacity of the multiple inverter devices A as the distribution ratio. According to this configuration, in the power system S2, output distribution is performed for multiple inverter devices A having different rated capacities according to their respective rated capacities. Therefore, when multiple inverter devices A are operated in parallel, appropriate independent operation can be performed according to the number of inverter devices A and the rated capacity of each inverter device A. In other words, the power system S2 can control appropriate independent operation according to the number of inverter devices A and the rated capacity of each inverter device A, and the independent operation of the power system S2 is good. Moreover, in the power system S2, like the power system S1, each inverter device A communicates with the other inverter devices A and controls the output power in a cooperative and distributed manner, so that the independent operation can be controlled without providing a management device that manages the multiple inverter devices A.

[0046] In a configuration different from the above power system S2, the rated capacities of the multiple inverter devices A may all be the same. In this case, the distribution ratio calculated by the distribution ratio calculation unit 43 of the power system S2 is the same as the value calculated by the distribution ratio calculation unit 43 of the power system S1 (the reciprocal 1 / n of the number n of the multiple inverter devices A). In other words, the output power (active power and reactive power) of each inverter device A is equalized among the multiple inverter devices A, so that the same effect as the power system S1 is achieved.

[0047] In a configuration different from the power system S2, each inverter device A may calculate an active power target value without using information on the number n of the inverter devices A. For example, the first setting unit 41 may calculate an active power target value by multiplying the active power average value input from the first calculation unit 31 by the rated capacity input from the first acquisition unit 61 and dividing the multiplication result by the rated capacity average value input from the third calculation unit 33. The second setting unit 42 may also calculate a reactive power target value in a similar manner. In the power system S2, in the process of calculating the active power target value by the first setting unit 41, the active power average value is multiplied by the number n to calculate the active power total value, and the rated capacity average value is multiplied by the number n to calculate the rated capacity total value. Then, the active power total value is multiplied by the distribution rate to calculate the active power target value. In other words, the calculation result of the active power target value is the same whether or not the multiplication by the number n of each unit is omitted. Therefore, the first setting unit 41 of this modification can set the same active power target value as that of the power system S2 without using information on the number of units n. This is similar to the second setting unit 42. In this modification, the number of units searching unit 39 and the distribution rate calculation unit 43 do not need to be provided.

[0048] A power system S3 according to the third embodiment will be described. FIG. 5 shows an example of the overall configuration of the power system S3. As shown in FIG. 5, the inverter devices A of the power system S3 include the battery control devices B. In the example shown in FIG. 5, all of the inverter devices A are the battery control devices B. The DC power sources 9 connected to the battery control devices B are the batteries 91. In this embodiment, the battery control devices B have the same rated capacity, but the batteries 91 have different rated capacities. Hereinafter, the rated capacity of the battery 91 is referred to as the "battery capacity." In the power system S3, each battery control device B distributes the active power output according to the battery capacity of the connected battery 91. Note that the reactive power output may be distributed according to the rated capacity of each battery control device B, for example.

[0049] Fig. 6 shows a detailed configuration example of the storage battery control device B. As shown in Fig. 6, each storage battery control device B has the same components as the inverter device A in the second embodiment, and the acquisition unit 6 further includes a second acquisition unit 62. The second acquisition unit 62 acquires the storage battery capacity and charging rate (SoC: State of Charge) of the connected storage battery 91. The second acquisition unit 62 outputs the acquired storage battery capacity and charging rate to the processing unit 3 and the setting unit 4.

[0050] The processing unit 3 of the storage battery control device B further calculates, as state values, an average value of the storage battery capacity (average storage battery capacity value) and an average value of the charging rate (average charging rate value) of the storage batteries 91 connected to each storage battery control device B. The processing unit 3 of the storage battery control device B also generates, as internal values, a storage battery capacity internal value based on the storage battery capacity and a charging rate internal value based on the charging rate. In other words, the internal values ​​of the power system S3 further include a storage battery capacity internal value and a charging rate internal value.

[0051] The fourth calculation unit 34 calculates the battery capacity average value by repeatedly performing a calculation process (fourth calculation process) for generating the battery capacity internal value. The fourth calculation unit 34 sets the battery capacity acquired by the second acquisition unit 62 as an initial value of the battery capacity internal value. In the fourth calculation process, the fourth calculation unit 34 generates a new battery capacity internal value using a calculation result based on the generated battery capacity internal value and each battery capacity internal value input from the receiving unit 22. In the fourth calculation process, a calculation is performed using the generated battery capacity internal value as the internal value Xi and the battery capacity internal value received by the receiving unit 22 as the internal value Xj in the above formula (1). The newly generated battery capacity internal value is output to the transmitting unit 21 and is used in the next fourth calculation process. By repeating such a fourth calculation process, the battery capacity internal value converges to the arithmetic mean value of the rated capacity of the storage batteries 91 connected to each of the multiple storage battery control devices B. The fourth calculation unit 34 outputs the converged storage battery capacity internal value as a storage battery capacity average value to the setting unit 4. The fourth calculation unit 34 may store the calculated storage battery capacity average value in a storage unit, or may calculate the storage battery capacity average value at each predetermined timing.

[0052] The fifth calculation unit 35 calculates the average charging rate by repeatedly performing a calculation process (fifth calculation process) for generating the charging rate internal value. The fifth calculation unit 35 sets the charging rate acquired by the second acquisition unit 62 as an initial value of the charging rate internal value. In the fifth calculation process, the fifth calculation unit 35 generates a new charging rate internal value by using a calculation result based on the generated charging rate internal value and each charging rate internal value input from the receiving unit 22. In the fifth calculation process, a calculation is performed using the generated storage battery capacity internal value as the internal value Xi and the charging rate internal value received by the receiving unit 22 as the internal value Xj in the above formula (1). The newly generated charging rate internal value is output to the transmitting unit 21 and is used in the next fifth calculation process. By repeating such a fifth calculation process, the charging rate internal value converges to the arithmetic mean value of the charging rates of the storage batteries 91 connected to each of the multiple storage battery control devices B. The fifth calculation unit 35 outputs the converged internal charging rate value as the charging rate average value to the setting unit 4. The fifth calculation unit 35 may store the calculated charging rate average value in a storage unit, or may calculate the charging rate average value at a predetermined timing.

[0053] The distribution ratio calculation unit 43 of the power system S3 calculates a distribution ratio (first distribution ratio) to be output to the first setting unit 41 and a distribution ratio (second distribution ratio) to be output to the second setting unit 42. The second distribution ratio is the same as the distribution ratio of the power system S2, that is, the distribution ratio according to the rated capacity. In calculating the first distribution ratio, the distribution ratio calculation unit 43 calculates the ratio of the storage battery capacity of each storage battery control device B to the total value of each storage battery capacity of the multiple storage battery control devices B (total storage battery capacity value) as the first distribution ratio. Specifically, the multiplier 431 multiplies the storage battery capacity average value input from the fourth calculation unit 34 by the number n input from the number search unit 39 to calculate the total value of the storage battery capacities of the multiple storage battery control devices B (total storage battery capacity value). The divider 432 calculates the first distribution ratio by dividing the storage battery capacity connected to the device itself, which is input from the second acquisition unit 62, by the storage battery capacity total value (the multiplication result of the multiplier 431).

[0054] As shown in Fig. 6, the first setting unit 41 of the power system S3 includes a multiplier 411, a distributor 412, and a corrector 413. The processing of the multiplier 411 and distributor 412 is the same as that of the power systems S1 and S2. The corrector 413 corrects the output of the distributor 412 by the difference between the average charging rate and the charging rate of each storage battery 91. In other words, the active power target value is corrected by the difference between the average charging rate of each storage battery 91 and each charging rate. The first setting unit 41 outputs the active power target value corrected by the corrector 413 to the control unit 5 (first calculation unit 51).

[0055] In the power system S3, the distribution ratio calculation unit 43 of the storage battery control device B calculates the ratio of the rated capacity of each storage battery 91 to the total value of the rated capacities of the multiple storage batteries 91 as the distribution ratio of the storage battery control device B to which the storage battery 91 is connected. With this configuration, in the power system S3, the storage batteries 91 having different storage battery capacities (the rated capacities of the storage batteries 91) can perform output distribution of active power according to the respective storage battery capacities. Therefore, when multiple storage battery control devices B (inverter devices A to which storage batteries are connected) are operated in parallel, each storage battery control device B can perform an appropriate independent operation according to the number of storage battery control devices B and the rated capacity (storage battery capacity) of each storage battery 91. In other words, the power system S3 can control an appropriate independent operation according to the number of storage battery control devices B and the rated capacity (storage battery capacity) of each storage battery 91, and the independent operation of the power system S3 becomes good. In addition, in the power system S3, similar to the power systems S1 and S2, each battery control device B communicates with the other battery control devices B and controls the output power in a cooperative and distributed manner, so that autonomous operation can be controlled without setting up a management device to manage multiple battery control devices B.

[0056] In the power system S3, the first setting unit 41 corrects the active power target value Pref based on the difference between the average value of the charging rates of the storage batteries 91 and each charging rate. With this configuration, when there is a difference in the charging rates of the storage batteries 91, the charging rates of the storage batteries 91 are averaged, and bias in the charging rates can be suppressed. In other words, in the power system S3, control is performed to intentionally circulate power between a plurality of inverter devices A (storage battery control devices B), making it possible to average the charging rates of the storage batteries 91.

[0057] In a configuration different from the power system S3, each storage battery control device B may calculate the active power target value without using information on the number n of the multiple storage battery control devices B. For example, the first setting unit 41 of the storage battery control device B may calculate the active power target value by multiplying the active power average value input from the first calculation unit 31 by the storage battery capacity input from the second acquisition unit 62 and dividing the multiplication result by the storage battery capacity average value input from the fourth calculation unit 34. In the power system S3, in the calculation process of the active power target value by the first setting unit 41, in order to calculate the active power total value, the active power average value is multiplied by the number n of devices, and in order to calculate the storage battery capacity total value, the storage battery capacity average value is multiplied by the number n of devices. Then, the active power target value is calculated by multiplying the active power total value by the distribution rate. In other words, whether or not the multiplication by the number n of devices is omitted, the calculation result of the active power target value is the same. Therefore, the first setting unit 41 of this modification can set the same active power target value as the power system S3 without using information on the number n of devices. In this case, the processing unit 3 does not need to be provided with the number-of-machines searching unit 39, and the setting unit 4 does not need to be provided with the distribution rate calculation unit 43.

[0058] The power system and inverter device according to the present disclosure are not limited to the above-described embodiment. The specific configurations of the components of the power system and inverter device according to the present disclosure can be freely designed in various ways. [Explanation of symbols]

[0059] S1 to S3: power system, L: load, A: inverter device, B: storage battery control device, 1: measurement unit, 2: communication unit, 21: transmission unit, 22: reception unit, 3: processing unit, 31: first calculation unit, 32: second calculation unit, 33: third calculation unit, 34: fourth calculation unit, 35: fifth calculation unit, 39: number of units search unit, 4: setting unit, 41: first setting unit, 42: second setting unit, 43: distribution rate calculation unit, 5: control unit, 51: first calculation unit, 52: second calculation unit, 53: phase control unit, 54: amplitude control unit, 6: acquisition unit, 61: first acquisition unit, 62: second acquisition unit, 9: DC power supply, 91: storage battery

Claims

1. A power supply system includes a plurality of inverter devices for supplying power to a load, Each of the plurality of inverter devices is a measurement unit that measures an active power output and a reactive power output; a first calculation unit that generates an internal active power value based on the active power output and calculates an average value of the active power output measured by each of the plurality of inverter devices; a second calculation unit that generates an internal reactive power value based on the reactive power output and calculates an average value of the reactive power output measured by each of the plurality of inverter devices; a first setting unit that sets an active power target value using the average value of the active power output; a second setting unit that sets a reactive power target value using the average value of the reactive power output; a control unit that controls an output power based on the measurement value of the active power output and the active power target value, and the measurement value of the reactive power output and the reactive power target value; a communication unit that transmits internal values ​​including the generated internal active power value and the generated internal reactive power value to at least one of the other inverter devices and receives the internal values ​​of the inverter device from the at least one of the other inverter devices; Equipped with the first calculation unit performs a first calculation process to generate a new internal active power value by using a calculation result based on the generated internal active power value and the received internal active power value; the first calculation process is repeated, so that the internal active power value converges to an average value of the active power output, The second calculation unit performs a second calculation process to generate a new internal reactive power value by using a calculation result based on the generated internal reactive power value and the received internal reactive power value; The power system, wherein the reactive power internal value converges to an average value of the reactive power output by repeating the second calculation process.

2. A first acquisition unit that acquires a rated capacity of the own device; A third calculation unit that generates an internal value of a rated capacity based on the rated capacity and calculates an average value of the rated capacities of the plurality of inverter devices, The internal value further includes the rated capacity internal value; The first setting unit further sets the active power target value by using an average value of the rated capacity, The second setting unit further sets the reactive power target value by using an average value of the rated capacity, The third calculation unit performs a third calculation process to generate a new internal rated capacity value by using a calculation result based on the generated internal rated capacity value and the received internal rated capacity value; The power system according to claim 1 , wherein the internal value of the rated capacity converges to an average value of the rated capacity by repeating the third arithmetic process.

3. a number search unit that searches for the number of the plurality of inverter devices; a distribution ratio calculation unit that calculates a distribution ratio for the inverter device of the own device, the unit number search unit generates an internal value for unit number search, and searches for the number of the plurality of inverter devices using the internal value for unit number search; the first setting unit calculates an active power total value by multiplying the average value of the active power output by the number of units, and sets a value obtained by distributing the active power total value by the distribution rate as the active power target value; 3. The power system according to claim 1, wherein the second setting unit calculates a total reactive power value by multiplying an average value of the reactive power output by the number of units, and sets a value obtained by distributing the total reactive power value by the distribution rate as the reactive power target value.

4. The plurality of inverter devices include a plurality of storage battery control devices each connected to a storage battery, The plurality of battery control devices include A second acquisition unit that acquires a storage battery capacity and a charging rate of the storage battery connected to the device itself; a fourth calculation unit that generates an internal value of a storage battery capacity based on the storage battery capacity and calculates an average value of the storage battery capacities of the plurality of inverter devices; a fifth calculation unit that generates an internal value of a charging rate based on the charging rate and calculates an average value of the charging rates of the storage batteries connected to the plurality of storage battery control devices; Further equipped with The internal values ​​further include the battery capacity internal value and the charging rate internal value; the first setting unit of the storage battery control device further calculates the active power target value by using the rated capacity and the average value of the storage battery capacity acquired by the second acquisition unit, corrects the calculated active power target value by using the average value of the charging rate and the charging rate acquired by the second acquisition unit, and then sets the calculated active power target value to the active power target value; The fourth calculation unit performs a fourth calculation process to generate a new storage battery capacity internal value by using a calculation result based on the generated storage battery capacity internal value and the received storage battery capacity internal value; The fourth calculation process is repeated, so that the internal battery capacity value converges to an average value of the battery capacity. The fifth calculation unit performs a fifth calculation process to generate a new internal charging rate value using a calculation result based on the generated internal charging rate value and the received internal charging rate value; The power system according to claim 1 , wherein the internal charging rate value converges to an average charging rate value by repeating the fifth arithmetic process.

5. An inverter device that supplies power to a load together with at least one other inverter device, a measurement unit that measures an active power output and a reactive power output; a first calculation unit that generates an internal active power value based on the active power output and calculates an average value of the active power output measured by each of the plurality of inverter devices; a second calculation unit that generates an internal reactive power value based on the reactive power output and calculates an average value of the reactive power output measured by each of the plurality of inverter devices; a first setting unit that sets an active power target value using the average value of the active power output; a second setting unit that sets a reactive power target value using the average value of the reactive power output; a control unit that controls an output power based on the measurement value of the active power output and the active power target value, and the measurement value of the reactive power output and the reactive power target value; a communication unit that transmits internal values ​​including the generated internal active power value and the generated internal reactive power value to at least one of the other inverter devices and receives the internal values ​​of the inverter device from the at least one of the other inverter devices; Equipped with the first calculation unit performs a first calculation process to generate a new internal active power value by using a calculation result based on the generated internal active power value and the received internal active power value; the first calculation process is repeated, so that the internal active power value converges to an average value of the active power output, The second calculation unit performs a second calculation process to generate a new internal reactive power value by using a calculation result based on the generated internal reactive power value and the received internal reactive power value; The inverter device, wherein the reactive power internal value converges to an average value of the reactive power output by repeating the second calculation process.

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