JP6691730B2 - Control circuit for controlling inverter circuit, inverter device including the control circuit, power system including the inverter device, and control method - Google Patents

Description

  The present invention relates to a control circuit for controlling an inverter circuit, an inverter device including the control circuit, a power system including the inverter device, and a control method.

  In recent years, research on distributed power sources using natural energy such as sunlight has been advanced. Generally, a distributed power source is connected to a power system in order to reversely flow the generated power to the power system. In this case, the distributed power supply uses the phase of the system voltage of the power system as its own internal phase to control the output current and adjust the power (see Patent Document 1, for example).

  FIG. 6 is a diagram for explaining a conventional distributed power supply A '.

  The distributed power supply A ′ converts the DC power output from the DC power supply 1 into AC power by the inverter circuit 2 and outputs the AC power to the load and the power system B. The control circuit 3 ′ controls the inverter circuit 2, generates a PWM signal based on the signal detected by each sensor provided in the distributed power supply A ′, and outputs the PWM signal to the inverter circuit 2. The control circuit 3'includes a phase detector 31 ', a command signal generator 32, and a PWM signal generator 33. The phase detection unit 31 ′ detects the phase θ from the voltage signal obtained by detecting the system voltage, and outputs this to the command signal generation unit 32 as the internal phase θ. The command signal generation unit 32 generates a command signal using the internal phase θ and outputs it to the PWM signal generation unit 33. The PWM signal generation unit 33 generates a PWM signal based on the command signal input from the command signal generation unit 32 and outputs it to the inverter circuit 2. Since the distributed power sources A'connected to the same interconnection point detect the same system voltage, the internal phase θ is synchronized.

  On the other hand, when the power system is out of power for a long time due to a disaster or when there is no power system on an isolated island, the distributed power sources need to be operated independently without being connected to the power system. In this case, the distributed power supply cannot detect the phase from the system voltage of the power system, and therefore oscillates the internal phase and controls the output voltage using this.

  FIG. 7: is a figure for demonstrating the conventional distributed power supply A "which performs self-sustaining operation.

  The distributed power supply A ″ differs from the distributed power supply A ′ in that the distributed power supply A ″ includes an internal phase generation unit 31 ″ instead of the phase detection unit 31 ′. The internal phase generator 31 ″ generates the internal phase θ. The command signal generator 32 uses the internal phase θ to generate the command signal.

As shown in FIG. 7, in the case of a power system in which a plurality of distributed power supplies A ″ are connected in parallel, it is necessary to synchronize the internal phase θ of each distributed power supply A ″. Therefore, the monitoring device C for centrally monitoring each distributed power supply A ″ has a function of synchronizing the internal phase θ of each distributed power supply A ″. Hereinafter, this method is referred to as "centralized monitoring method". That is, the communication unit 34 transmits the internal phase θ generated by the internal phase generation unit 31 ″ of each distributed power supply A ″ to the monitoring device C. The monitoring device C calculates, for example, an arithmetic mean value (arithmetic mean value) of the received internal phase θ of each distributed power supply A ″, and sends it to each distributed power supply A ″ as a target internal phase θ ^* . The internal phase generation unit 31 ″ controls the internal phase θ so that it becomes the target internal phase θ ^* . Alternatively, one distributed power supply A ″ (master) substitutes for the monitoring device C and another distributed power supply A The target internal phase θ ^* is output to "(slave). In the following, this system is referred to as the" master slave system ".

JP, 2010-68630, A

Reza Olfati-Saber, J. Alex Fax, and Richard M. Murray, "Consensus and Cooperation in Networked Multi-Agent Systems", Proceedings of the IEEE, Vol.95, No.1, (2007) Mehran Mesbahi and Magnus Egerstedt, "Graph Theoretic Methods in Multiagent Networks", Princeton (2010)

  When the internal phase θ is synchronized by the centralized monitoring method or the master slave method as described above, the system becomes bulky, it is difficult to flexibly respond to the increase / decrease of the distributed power supply A ″, and it is vulnerable to failure. For example, in the case of the centralized monitoring system, it is necessary to provide a monitoring device C and communicate with each distributed power supply A ″. In the case of wired communication, it is necessary to connect the monitoring device C and each distributed power supply A ″ with a communication line. In the case of wireless communication, it is necessary to prevent the electric wave from being blocked by an obstacle or the like. In the case of the slave system, it is not necessary to separately provide the monitoring device C, but it is necessary to communicate with the distributed power supply A ″ (master) and each distributed power supply A ″ (slave). The distributed power supply A ″ In order to increase / decrease, the control program of the monitoring device C or the distributed power supply A ″ (master) needs to be changed. Further, when the monitoring device C or the distributed power supply A ″ (master) fails, the internal phase θ There is also a problem that can not be synchronized.

  The present invention has been conceived under the circumstances described above, and an object thereof is to provide a method of synchronizing the internal phase that can solve the above-mentioned problems.

  In order to solve the above problems, the present invention takes the following technical means.

  A control circuit provided by the first aspect of the present invention is a control circuit for controlling an inverter circuit included in each distributed power supply in a power system in which a plurality of distributed power supplies that are not in a master-slave relationship are connected in parallel. , An internal phase generation means for generating an internal phase used for control, and a communication means for communicating with at least one other distributed power source, wherein the communication means includes an internal phase generated by the internal phase generation means, Transmitting to at least one of the other distributed sources, the internal phase generating means based on the generated internal phase and the internal phase received by the communication means from at least one of the other distributed sources. It is characterized in that the internal phase is generated using the calculation result. Note that “not in a master-slave relationship” is not a relationship in which one of the distributed power sources (master: master) monitors and controls the other (slave: slave), but both are equal relationships. It means that. Further, the “electric power system” means, for example, a system in which a plurality of distributed power sources are connected in parallel.

In a preferred embodiment of the present invention, the internal phase generation means is configured to perform a calculation based on the generated internal phase and the received internal phase, and a predetermined calculation result output by the calculation means. Adding means for adding to the angular frequency and outputting as a corrected angular frequency;
Integrating means for integrating the modified angular frequency to calculate an internal phase.

  In a preferred embodiment of the present invention, the calculation means calculates the calculation result by subtracting the generated internal phase from the received internal phase and adding all the subtraction results.

  In a preferred embodiment of the present invention, the arithmetic means subtracts the generated internal phase from the received internal phase, adds all the subtraction results, and the communication means performs other communication. The operation result is calculated by dividing by the number of distributed power sources.

  In a preferred embodiment of the present invention, the calculating means subtracts the generated internal phase from the received internal phase, adds all subtraction results, and multiplies the generated internal phase, Calculate the calculation result.

  In a preferred embodiment of the present invention, the calculating means subtracts the received internal phase from the generated internal phase, adds all the subtraction results, and multiplies the square of the generated internal phase. Thus, the calculation result is calculated.

  In a preferred embodiment of the present invention, the phase detection means for detecting the phase of the system voltage is provided, and when the distributed power source is connected to the power system, the phase detected by the phase detection means is When the distributed power supply is disconnected from the power system, the internal phase generated by the internal phase generating means is used for control.

  An inverter device provided by the second aspect of the present invention is characterized by including the control circuit provided by the first aspect of the present invention and an inverter circuit.

  The power system provided by the third aspect of the present invention is characterized in that a plurality of distributed power sources each having a DC power source and an inverter device provided by the second aspect of the present invention are connected in parallel. ..

  A control method provided by the fourth aspect of the present invention is a control method for synchronizing an internal phase of each distributed power supply in a power system in which a plurality of distributed power supplies that are not in a master-slave relationship are connected in parallel. A first step of generating a phase, a second step of transmitting the internal phase generated in the first step to at least one other distributed power supply, and an internal transmission of at least one other distributed power supply The third step of receiving the phase is performed by each distributed power supply, and the first step is to perform a calculation result based on the generated internal phase and the internal phase received in the third step. It is characterized in that it is used to generate an internal phase.

  According to the present invention, the internal phase generation means generates the internal phase using the calculation result based on the generated internal phase and the internal phase of the other distributed power supply received by the communication means. The internal phase generation means of each distributed power supply does this so that the internal phases of all distributed power supplies converge to the same value. Each distributed power supply only needs to communicate with at least one distributed power supply (for example, one located nearby) and one distributed power supply or monitoring device needs to communicate with all other distributed power supplies. There is no. Therefore, the system does not become large-scale. Even if one distributed power source fails, the internal phase can be synchronized as long as all the other distributed power sources can communicate with any of the distributed power sources. Moreover, it is possible to flexibly deal with the increase and decrease of the distributed power source.

  Other features and advantages of the present invention will become more apparent from the detailed description given below with reference to the accompanying drawings.

It is a figure for explaining the distributed type power supply concerning a 1st embodiment. It is a figure which shows the electric power system to which the distributed power supply which concerns on 1st Embodiment was connected in multiple numbers. It is a figure which shows the simulation result of the change of the internal phase of each distributed power supply in an electric power system. It is a figure for demonstrating the other communication state of the distributed power supply connected in parallel with the electric power system. It is a figure for demonstrating the distributed power supply which concerns on 2nd Embodiment. It is a figure for demonstrating the conventional distributed power supply. It is a figure for demonstrating the conventional distributed power supply which performs self-sustaining operation.

  Hereinafter, an embodiment of the present invention will be specifically described with reference to the drawings by taking a case where a control circuit according to the present invention is used as a distributed power supply as an example.

  FIG. 1 is a diagram for explaining the distributed power supply according to the first embodiment. FIG. 2 is a diagram showing a power system in which a plurality of distributed power sources according to the first embodiment are connected in parallel.

  As shown in FIG. 1, the distributed power supply A includes a DC power supply 1, an inverter circuit 2, and a control circuit 3. The distributed power supply A converts the DC power output from the DC power supply 1 into AC power by the inverter circuit 2 and outputs the AC power. Although not shown, the output side of the inverter circuit 2 is provided with a transformer for stepping up (or stepping down) the AC voltage. A combination of the inverter circuit 2 and the control circuit 3 is an inverter device, which is a so-called power conditioner.

  The DC power supply 1 outputs DC power and includes a solar cell. A solar cell produces direct current power by converting sunlight energy into electric energy. The DC power supply 1 outputs the generated DC power to the inverter circuit 2. The DC power supply 1 is not limited to the one that generates DC power by the solar cell. For example, the DC power supply 1 may be a fuel cell, a storage battery, an electric double layer capacitor or a lithium ion battery, or AC power generated by a diesel engine generator, a micro gas turbine generator, a wind turbine generator or the like. It may be a device that converts to DC power and outputs it.

  The inverter circuit 2 converts the DC power input from the DC power supply 1 into AC power and outputs the AC power. The inverter circuit 2 includes a PWM control inverter and a filter (not shown). The PWM control inverter is a three-phase inverter including three sets and six switching elements (not shown), and switches the switching elements between ON and OFF based on the PWM signal input from the control circuit 3 to generate DC power. Convert to AC power. The filter removes high frequency components due to switching. The inverter circuit 2 is not limited to this. For example, the PWM control inverter may be a single-phase inverter or a multi-level inverter. Further, the present invention is not limited to PWM control, and other methods such as phase shift control may be used.

  The control circuit 3 controls the inverter circuit 2, and is realized by, for example, a microcomputer. The control circuit 3 generates a PWM signal based on the input voltage, output voltage, output current, etc. of the inverter circuit 2 detected by each sensor provided in the distributed power supply A, and outputs the PWM signal to the inverter circuit 2. The control circuit 3 includes an internal phase generator 31, a command signal generator 32, a PWM signal generator 33, and a communication unit 34.

The internal phase generator 31 generates an internal phase θ _i used to generate a command signal. Details of the internal phase generator 31 will be described later.

The command signal generator 32 generates a command signal for controlling the output voltage. The command signal generation unit 32 performs so-called three-phase / two-phase conversion processing (αβ conversion processing) and rotational coordinate conversion processing (dq conversion processing) on the three-phase voltage signal that has detected the output voltage of the inverter circuit 2, and d It is converted into a signal of an axial component and a q-axis component. The three-phase / two-phase conversion process is a process of converting a three-phase AC signal into an equivalent two-phase AC signal. The three-phase AC signal is a stationary rectangular coordinate system (hereinafter, "stationary coordinate system"). That is, by decomposing into the components of the α axis and the β axis which are orthogonal to each other, and adding the components of the respective axes, the AC signal of the α axis component and the AC signal of the β axis component are converted. The rotating coordinate conversion process is a process of converting a two-phase (α-axis component and β-axis component) signal of the stationary coordinate system into a two-phase (d-axis component and q-axis component) signal of the rotating coordinate system. .. The rotating coordinate system is an orthogonal coordinate system that has a d-axis and a q-axis that are orthogonal to each other and rotates at a predetermined angular velocity. The rotational coordinate conversion process is performed based on the internal phase θ _i input from the internal phase generator 31.

The command signal generation unit 32 extracts only the DC component from the d-axis component and the q-axis component of the voltage signal, performs a control process separately for each of the two compensation signals, and performs a stationary coordinate conversion process (inverse dq conversion process) and a two-compensation signal. Phase / three-phase conversion processing (inverse αβ conversion processing) is performed to convert into three compensation signals. The stationary coordinate conversion process performs the reverse process of the rotating coordinate conversion process, and the two-phase / three-phase conversion process performs the reverse process of the three-phase / two-phase conversion process. The static coordinate conversion process is performed based on the internal phase θ _i input from the internal phase generator 31. The command signal generation unit 32 generates three command signals from the sine wave signal generated based on the internal phase θ _i input from the internal phase generation unit 31 and the three compensation signals, and the PWM signal generation unit To 33.

  The command signal generator 32 controls the input voltage of the inverter circuit 2, but a description thereof will be omitted. In the present embodiment, the case where the distributed power supply A is a three-phase system has been described, but it may be a single-phase system. In the case of a single-phase system, the command signal generator 32 may control the single-phase voltage signal that has detected the output voltage of the inverter circuit 2.

  The PWM signal generator 33 is for generating a PWM signal. The PWM signal generation unit 33 generates a PWM signal by the triangular wave comparison method based on the carrier signal and the command signal input from the command signal generation unit 32. For example, a pulse signal that is high level when the command signal is larger than the carrier signal and is low level when the command signal is equal to or lower than the carrier signal is generated as the PWM signal. The generated PWM signal is output to the inverter circuit 2. The PWM signal generation unit 33 is not limited to the case of generating the PWM signal by the triangular wave comparison method, and may generate the PWM signal by a hysteresis method, for example.

The communication unit 34 communicates with another distributed power source A. The communication unit 34 receives the internal phase θ _i generated by the internal phase generation unit 31 and transmits it to the communication unit 34 of another distributed power supply A. The communication unit 34 also outputs the internal phase θ _j received from the communication unit 34 of the other distributed power supply A to the internal phase generation unit 31. The communication method is not limited, and wired communication may be used or wireless communication may be used.

  As shown in FIG. 2, the distributed power supply A is connected in parallel with another distributed power supply A in the power system. FIG. 2 shows a state in which five distributed power sources A (A1 to A5) and four loads L are connected. In the actual power system, more distributed power sources A and loads L are connected, but an extremely small number of cases are shown for simplification of description.

  The arrow shown in FIG. 2 indicates that communication is being performed. The distributed power supply A1 communicates only with the distributed power supply A2, and the distributed power supply A2 communicates only with the distributed power supply A1 and the distributed power supply A3. The distributed power supply A3 communicates only with the distributed power supply A2 and the distributed power supply A4, and the distributed power supply A4 communicates only with the distributed power supply A3 and the distributed power supply A5, and the distributed power supply A5. Communicates only with the distributed power source A4. As described above, the communication unit 34 of the distributed power supply A is communicating with at least one communication unit 34 of the distributed power supply A among the distributed power supplies A connected to the power system, and is connected to the power system. It is only necessary that a communication path exists for any two distributed power sources A (hereinafter, this state is referred to as a “connected state”), and all of the connected power systems are connected. It is not necessary to communicate with the communication unit 34 of the distributed power source A.

For example, when the distributed power supply A is the distributed power supply A2, the communication unit 34 transmits the internal phase θ ₂ generated by the internal phase generation unit 31 to the communication units 34 of the distributed power supplies A1 and A3, and the distributed power supply A1. The internal phase θ ₁ is received from the communication unit 34 of the above, and the internal phase θ ₃ is received from the communication unit 34 of the distributed power supply A3.

  Next, details of the internal phase generator 31 will be described.

Internal phase generating unit 31 includes an internal phase theta _i which generated, is input from the communication unit 34, by using the internal phase theta _j other distributed power supply A, and generates an internal phase theta _i. Even if the internal phase θ _i and the internal phase θ _j are different, the internal phase θ _i and the internal phase θ _j converge to a common internal phase by repeating the calculation process in the internal phase generation unit 31. As shown in FIG. 1, the internal phase generation unit 31 includes a calculation unit 311, a multiplier 312, an adder 313, and an integrator 314.

The calculation unit 311 performs a calculation based on the following formula (1). That is, the calculation unit 311 subtracts the internal phase θ _i generated by the internal phase generation unit 31 from each internal phase θ _j input from the communication unit 34, and adds the calculation results u _{i obtained} by adding all the subtraction results. Output to the device 313.

For example, when the distributed power supply A is the distributed power supply A2 (see FIG. 2), the calculation unit 311 performs the calculation of the following formula (2) and outputs the calculation result u ₂ .

The multiplier 312 multiplies the calculation result u _i input from the calculation unit 311 by a predetermined coefficient ε and outputs the result to the adder 313. The coefficient ε is a value that satisfies 0 <ε <1 / d _max and is set in advance. The d _max is the largest of all the distributed power sources A connected to the power system among the d _i , which is the number of other distributed power sources A with which the communication unit 34 communicates. In other words, it is the number of internal phases θ _j input to the communication unit 34 of the distributed power sources A connected to the power system that are communicating with the most other distributed power sources A. The coefficient ε is multiplied by the calculation result u _i in order to prevent the corrected angular frequency ω _i from becoming too large (small) and the fluctuation of the internal phase θ _{i from} becoming too large. Therefore, when the processing in the internal phase generator 31 is continuous time processing, it is not necessary to provide the multiplier 312.

The adder 313 adds the input from the multiplier 312 to a predetermined angular frequency ω ₀ and outputs it as a corrected angular frequency ω _i to the integrator 314. The integrator 314 integrates the modified angular frequency ω _i input from the adder 313 to generate and output the internal phase θ _i . The integrator 314 generates an internal phase theta _i by adding the corrected angular frequency omega _i in the interior phase theta _i previously generated. Further, the integrator 314 outputs the internal phase θ _i as a value in the range of (−π <θ _i ≦ π). The method of setting the range of the internal phase θ _i is not limited to this, and may be, for example, (0 ≦ θ _i <2π). The internal phase θ _i is output to the command signal generation unit 32, the communication unit 34, and the calculation unit 311.

  In this embodiment, the case where the control circuit 3 is realized as a digital circuit has been described, but it may be realized as an analog circuit. Further, the processing performed by each unit may be designed by a program, and the computer may function as the control circuit 3 by executing the program. Alternatively, the program may be recorded in a recording medium and read by a computer.

In the present embodiment, the internal phase generation unit 31 generates the internal phase θ _i by using the generated internal phase θ _i and the internal phase θ _{j of} another distributed power supply A input from the communication unit 34. To do. When the internal phase θ _i is larger than the arithmetic mean value of the internal phases θ _j , the calculation result u _i output by the calculation unit 311 has a negative value. Then, the corrected angular frequency ω _i becomes smaller than the predetermined angular frequency ω ₀ , and the change amount of the internal phase θ _i becomes small. On the other hand, when the internal phase θ _i is smaller than the arithmetic mean value of the internal phases θ _j , the calculation result u _i output by the calculation unit 311 has a positive value. Then, the corrected angular frequency ω _i becomes larger than the predetermined angular frequency ω ₀ , and the change amount of the internal phase θ _i becomes large. That is, the internal phase θ _i approaches the arithmetic mean value of each internal phase θ _j . By performing this processing on each distributed power supply A, the internal phase θ _i of each distributed power supply A converges to the same value. The internal phase θ _i changes with time, and can be considered to be a combination of a component that changes according to the angular frequency ω ₀ and a component that changes so as to compensate the deviation of the initial phase. When the latter converges to the same value θα, the internal phase θ _i of each distributed power supply A also converges to the same value. It has been mathematically proved that the latter converges to the same value (see Non-Patent Documents 1 and 2). It is also proved that the convergent value θα becomes an arithmetic mean value of initial values of the internal phase θ _i of each distributed power source A, as shown in the following formula (3). n is the number of the distributed power sources A connected to the power system, and the following equation (3) adds all the initial values of the internal phases θ _{1 to} θ _n of the distributed power sources A ₁ to An and divides by n. It indicates that the arithmetic mean value is calculated.

Below, a simulation in which it is confirmed that the internal phase θ _i converges in the power system shown in FIG. 2 will be described.

Initial values of the internal phases θ _{1 to} θ ₅ of the distributed power supplies A1 to A5 are respectively θ ₁ = π / 2, θ ₂ = 0, θ ₃ = π, θ ₄ = 3π / 2, θ ₅ = −π. The simulation was performed as / 4. FIG. 3 shows the result of the simulation, and shows the time response of the internal phases θ _{1 to} θ ₅ of the distributed power supplies A1 to A5, excluding the components that change according to the angular frequency ω _0. ing. FIG. 10A shows the case where the internal phase θ _i is not synchronized (that is, the arithmetic unit 311 and the communication unit 34 shown in FIG. 1 are not provided), and FIG. This is when the internal phase θ _i is synchronized (that is, in the case of the configuration shown in FIG. 1). In the same figure (a), it has not changed from the initial value. On the other hand, in the same figure (b), it converges to "11π / 20" which is the arithmetic mean value of the initial value.

According to the present embodiment, each distributed power source A connected to the power system is in mutual communication with at least one distributed power source A (for example, one located in the vicinity), and the power system is in the connected state. As a result, the internal phases θ _{i of} all distributed power supplies A converge to the same value. That is, it is not necessary for one distributed power supply A or the monitoring device to communicate with all other distributed power supplies A. Therefore, the system does not become large-scale. In addition, even if a certain distributed power source A fails, or if a certain distributed power source A is removed, all other distributed power sources A can communicate with any one of the distributed power sources A, and the power system is connected. In the state, the internal phase θ _i can be synchronized. Further, when increasing the number of distributed power sources A, it is sufficient that the distributed power source A communicates with at least one distributed power source A. Therefore, it is possible to flexibly deal with the increase or decrease of the distributed power source A.

In the above first embodiment, the varying components so as to compensate for deviation of the initial phase of the internal phase theta _i of distributed power A, the additive of the initial value of the internal phase theta _i of each distributed power source A The case where the average value is converged has been described, but the present invention is not limited to this. The convergence value θα varies depending on the arithmetic expression set in the arithmetic unit 311.

For example, when the arithmetic expression set in the arithmetic unit 311 is the following expression (4), the convergence value θα becomes a value as shown in the following expression (5). d _i is the number of other distributed power sources A with which the communication unit 34 communicates, that is, the number of internal phases θ _j input to the communication unit 34. In other words, the convergence value θα is a weighted average value of initial values of the internal phase θ _i of each distributed power source A, weighted by the number of communication partners.

When the arithmetic expression set in the arithmetic unit 311 is the following equation (6), the convergent value θα is a geometric mean of initial values of the internal phase θ _i of each distributed power source A as shown in the following equation (7). It becomes a value (geometric mean value).

Further, when the arithmetic expression set in the arithmetic unit 311 is the following equation (8), the convergent value θα is, as shown in the following equation (9), the harmonic mean of the initial value of the internal phase θ _i of each distributed power supply A. It becomes a value.

Further, when the arithmetic expression set in the arithmetic unit 311 is the following expression (10), the convergent value θα is, as shown in the following expression (11), the P-th order of the initial value of the internal phase θ _i of each distributed power supply A. It will be the average value.

In addition, in the said 1st Embodiment, although each distributed power supply A demonstrated the case where mutual communication was carried out, it is not restricted to this, You may make it perform one-sided communication. For example, as shown in FIG. 4, the distributed power supply A1 only sends to the distributed power supply A2, the distributed power supply A2 only receives from the distributed power supply A1, and only sends to the distributed power supply A3, The distributed power supply A3 only receives from the distributed power supply A2 and only transmits to the distributed power supply A4, and the distributed power supply A4 only receives from the distributed power supply A3 and only transmits to the distributed power supply A5. Even if the distributed power supply A5 only receives from the distributed power supply A4, the internal phase θ _i can be synchronized. More generally speaking, when a destination is traced from a certain distributed power source A connected to the power system, an arbitrary distributed power source A connected to the power system can be reached (in the graph theory, The state of “including spanning tree” is a condition that the internal phase θ _i can be synchronized.

  In the above-described first embodiment, the case where the power system to which the distributed power source A is connected is always in the self-sustained operation has been described, but the present invention is not limited to this. The present invention can be applied even when the power system to which the distributed power source A is connected is normally connected to the power system. This case will be described below as a second embodiment.

  FIG. 5 is a diagram for explaining the distributed power source according to the second embodiment. In the figure, the same or similar elements as those of the distributed power supply A according to the first embodiment (see FIG. 1) are designated by the same reference numerals. The distributed power supply A according to the second embodiment is different from the distributed power supply A according to the first embodiment in that the internal phase used is changed depending on whether or not it is connected to the power system B. As shown in FIG. 5, the distributed power supply A according to the second embodiment further includes a phase detection unit 31 ′ and a switching unit 35.

  The phase detection unit 31 ′ detects the phase θ from the voltage signal obtained by detecting the system voltage and outputs it to the switching unit 35. The detection position of the voltage signal of the phase detection unit 31 ′ is between the inverter circuit 2 and the circuit breaker C, and when the distributed power supply A is connected to the power system B, the voltage at the detection position becomes the system voltage. Become.

When the distributed power supply A is connected to the power system B, the switching unit 35 outputs the phase θ of the system voltage detected by the phase detection unit 31 ′ to the command signal generation unit 32. On the other hand, when the power system to which the distributed power source A is connected is disconnected from the power system B by the circuit breaker C, the internal phase θ _i generated by the internal phase generation unit 31 is output to the command signal generation unit 32.

  Further, the command signal generation unit 32 performs output current control when the distributed power supply A is connected to the power system B, and performs output voltage control when the distributed power supply A is disconnected from the power system B. ..

In the second embodiment as well, when the power system to which the distributed power source A is connected is disconnected from the power system B by the circuit breaker C, the power system operates independently as in the first embodiment. Also in this case, each distributed power supply A is mutually communicating with at least one distributed power supply A, and if the power system is in the connected state, the internal phases θ _i of all distributed power supplies A should be synchronized. You can Therefore, also in the second embodiment, the same effect as that of the first embodiment can be obtained.

  The control circuit, the inverter device, the power system, and the control method according to the present invention are not limited to the above embodiments. The specific configuration of each part of the control circuit, the inverter device, the power system, and the control method according to the present invention can be modified in various ways.

A, A1 to A5 Distributed power supply 1 DC power supply 2 Inverter circuit 3 Control circuit 31 Internal phase generation unit 311 Calculation unit 312 Multiplier 313 Adder 314 Integrator 31 'Phase detection unit 32 Command signal generation unit 33 PWM signal generation unit 34 Communication unit 35 Switching unit L load

Claims (10)

In a power system in which a plurality of distributed power supplies that are not in a master-slave relationship are connected in parallel, a control provided in one distributed power supply of the plurality of distributed power supplies and controlling an inverter circuit included in the distributed power supply. A circuit,
An internal phase generating means for generating an internal phase value which is a numerical value indicating an internal phase used for control,
Communication means for communicating with a plurality of other distributed power sources,
Equipped with
The communication unit transmits the internal phase value generated by the internal phase generation unit to a plurality of the other distributed power sources as numerical data ,
The internal phase generation means uses an internal phase value generated based on a calculation result based on the generated internal phase value and each internal phase value received as numerical data by the communication means from a plurality of the other distributed power sources. Generate a value,
A control circuit characterized by the above. The internal phase generation means,
An operation unit that performs an operation based on the generated internal phase value and each of the received internal phase values;
An addition unit that adds the calculation result output by the calculation unit to a predetermined angular frequency and outputs the corrected angular frequency;
Integrating means for integrating the modified angular frequency to calculate an internal phase value;
The control circuit according to claim 1, further comprising: The calculation means calculates the calculation result by subtracting the generated internal phase value from each of the received internal phase values and adding all the subtraction results,
The control circuit according to claim 2. The calculation means subtracts the generated internal phase value from each of the received internal phase values, adds all the subtraction results, and adds the number of other distributed power sources with which the communication means is communicating. Calculate the operation result by dividing the result,
The control circuit according to claim 2. The calculation means subtracts the generated internal phase value from each of the received internal phase values, adds all the subtraction results, and multiplies the generated internal phase value by the addition result to obtain the calculation result. Calculate,
The control circuit according to claim 2. The calculating means subtracts each of the received internal phase values from the generated internal phase value, adds all the subtraction results, and multiplies the addition result by the square of the generated internal phase value, Calculate the result,
The control circuit according to claim 2. Equipped with phase detection means to detect the phase of the system voltage,
When the distributed power source is connected to the power system, control is performed using the phase detected by the phase detection means,
When the distributed power supply is disconnected from the power system, control is performed using the internal phase value generated by the internal phase generation means,
The control circuit according to claim 1.   An inverter device comprising the control circuit according to claim 1 and an inverter circuit.   A power system, wherein a plurality of distributed power sources each having a DC power source and the inverter device according to claim 8 are connected in parallel. In a power system in which a plurality of distributed power supplies that are not in a master-slave relationship are connected in parallel, a control method for synchronizing the internal phase of each distributed power supply,
A first step of generating an internal phase value that is a numerical value indicating the internal phase;
A second step of transmitting the internal phase value generated in the first step to a plurality of other distributed power sources as numerical data ;
A third step of receiving, as numerical data, each internal phase value transmitted by a plurality of other distributed power sources,
Is performed by each distributed power source,
The first step generates an internal phase value using a calculation result based on the generated internal phase value and each internal phase value received in the third step,
A control method characterized by the above.