JP6700102B2 - Power converter - Google Patents

Description

  The present invention relates to a power conversion device.

  Various power conversion devices between a power system such as a commercial power system and a distributed power source such as a solar power generation facility, a fuel cell power generation facility, and a power storage facility have been proposed. For example, in Patent Document 1, transition between grid interconnection operation with a power system of a distributed power source and self-sustaining operation can be performed without interruption, or autonomous load sharing with a plurality of distributed power sources can be performed. As a configuration for realizing short-term system frequency stabilization, it is disclosed that virtual generator model control is performed to control the amount of power received from a distributed power source, assuming that a virtual generator is connected to the power system. ing.

International Publication No. 2013/008413

Ryuken Yu, Shinobi Toshinobu, Kakinano Hiroaki, Miura Tomofumi, Ise Toshifumi, "Distribution-free commercial grid connection/disconnection switching control of household distributed power sources using virtual synchronous generators", The Institute of Electrical Engineers of Japan Transaction B (Journal of Electric Power and Energy), 2013, vol.133, No.5, pp.430-438

  However, the configuration of Patent Document 1 is applied when the power system is a three-phase system. The configuration of Patent Document 1 cannot be directly applied to a single-phase three-wire power system that is a small capacity system for home use. In particular, recently, a micro grid using a fuel cell power generation facility or a solar power generation facility installed in each home or the like has rapidly spread. Since such a micro grid is connected to a single-phase three-wire power system, the power conversion device as in Patent Document 1 cannot be applied as it is.

  Non-Patent Document 1 describes a mode in which virtual generator model control is applied to such a single-phase three-wire power system. However, in this configuration, it is necessary to separately control the neutral line during the self-sustaining operation, and it is necessary to switch the operation mode for transition between the grid interconnection operation and the self-sustaining operation. Further, this also complicates the configuration of the power conversion device. Therefore, in the configuration as in Non-Patent Document 1 described above, in a system in which a distributed power source is connected to a single-phase three-wire power system, switching between control modes is not performed and system interconnection operation and independent operation are performed. You cannot move without interruption.

  The present invention is to solve the above-mentioned problems, and in a power conversion device connected between a single-phase three-wire power system and a distributed power source, system interconnection operation is performed without requiring switching of control modes. It is an object of the present invention to provide a power conversion device that can perform a transition between a self-sustaining operation and a self-sustaining operation without interruption.

A power converter according to one aspect of the present invention is a power converter connected between a distributed power source and a single-phase three-wire power system having a first voltage line, a second voltage line, and a neutral voltage line. An inverter having a pair of input terminals connected to the distributed power source and three output terminals connected to each voltage line of the electric power system; and the device on the electric power system side of the inverter, A current measuring device for respectively measuring a first output current of a first output end connected to a first voltage line and a second output current of a second output end connected to the second voltage line; A voltage measuring device that measures a first system voltage on the first voltage line for the neutral voltage line and a second system voltage on the second voltage line for the neutral voltage line, and a controller that controls switching of the inverter. And the first virtual generator is connected between the first voltage line and the neutral voltage line, and the controller includes a second voltage line and the neutral voltage line. Assuming that a second virtual generator is connected in between, a virtual frequency command value for each virtual generator is generated from the current and voltage measured by the current measuring device and the voltage measuring device, and to generate a phase angle command value by integrating the frequency command value, said first generating a phase angle of each virtual generator from the mains voltage and the second system voltage, the phase angle between the phase angle of the virtual generator From the difference between the command value and the phase difference angle generator for calculating the virtual phase difference angle in each virtual generator, and the current and voltage measured by the current measuring device and the voltage measuring device, the virtual difference of each virtual generator. From the voltage measured by the voltage measuring device, the phase difference angle, the induced voltage and the predetermined internal impedance of each virtual generator, the current command of each virtual generator is calculated. A current command value generation unit that generates a value, and is configured to switch the inverter so that the current measured by the current measuring device becomes the current command value, and the phase difference angle generation unit includes the phase difference angle generation unit. Generating a common frequency command value between one virtual generator and the second virtual generator, and/or one phase of the first virtual generator and the second virtual generator It is configured to correct the error between the phase angles by adjusting the angle based on the phase angle of the other of the first virtual generator and the second virtual generator.

  According to the above configuration, the virtual generator is connected between the first voltage line and the neutral voltage line and between the second voltage line and the neutral voltage line of the single-phase three-wire power system. Assuming that the first voltage line, the second voltage line and the neutral voltage line are connected, switching of the inverter is controlled. With this, with a simple configuration, it is possible to perform the transition between the grid interconnection operation and the self-sustaining operation on the first voltage line and the second voltage line without interruption, without requiring switching of the control mode. Further, a common frequency command value is generated between the two virtual generators, and/or the error between the phase angles is adjusted by adjusting the phase angle of one of the two virtual generators based on the phase angle of the other. Is corrected. Accordingly, the two virtual generators can be synchronized with each other, and not only the first system voltage and the second system voltage but also the voltage between the first voltage line and the second voltage line can be maintained.

  The phase difference angle generation unit calculates the total sum of active power by the first virtual generator and the second virtual generator from the current and voltage measured by the current measuring device and the voltage measuring device, and the effective By generating the frequency command value from the sum of electric power, the active power command value, and the reference frequency, the common frequency command value is generated between the first virtual generator and the second virtual generator. You may. According to this, since the control loop of the active power is shared between the two virtual generators, it is possible to match the phases of the induced voltages between the two virtual generators with a simple configuration.

The phase difference angle generation unit proportionally calculates a difference between the phase angle of the first virtual generator and the phase angle of the second virtual generator, and outputs the proportional calculation result to the first virtual generator. of by adding to one of the frequencies of the frequency and the second virtual power generator, the error of the phase Kakuma may be corrected. According to this, it is possible to reduce the phase shift of the induced voltage between the two virtual generators, regardless of the configuration of the control loop of active power.

  The induced voltage generator calculates the reactive power of each virtual generator from the current and the voltage measured by the current measuring device and the voltage measuring device, and the reactive power and the magnitude of the first system voltage and The induced voltage of each virtual generator may be calculated from the magnitude of the second system voltage, each reactive power command value, and the reference voltage. The degree of freedom in control can be increased by providing a control loop for reactive power individually for each virtual generator.

The phase difference angle generation unit calculates a difference between the total of the active powers and the active power command value by using a transfer function K _G (s)=K _gd /(1+T _g s), and the calculated result is the reference value. The frequency command value may be generated by adding a frequency. Here, K _gd is a coefficient showing the frequency droop characteristic in each virtual generator, and T _g is a time constant showing the characteristic of the tracking delay of the rotation speed due to inertia in each virtual generator. This makes it possible to easily realize a control mode simulating governor control using active power in a virtual generator.

The induced voltage generation unit multiplies the difference between the reactive power and the reactive power command value by a coefficient K _ad indicating a voltage droop characteristic, adds the reference voltage to the result, and generates a voltage command value. The difference between the value and the magnitude of the corresponding voltage measured by the voltage measuring device is calculated using the transfer function K _A (s)=K _ap +K _ai /s, and the calculation result is output as the induced voltage. May be. Here, K _ap is a coefficient indicating a proportional element, and K _ai is a coefficient indicating an integral element. This makes it possible to easily realize a control mode simulating automatic voltage adjustment control using reactive power in a virtual generator.

  The controller extracts the positive phase components of the current and the voltage measured by the current measuring device and the voltage measuring device, and handles the extracted positive phase components of the respective values in a rotating coordinate system synchronized with the positive phase. By doing so, a current command value for each virtual generator may be generated. By extracting the positive phase component of each value and configuring the virtual generator on the rotating coordinate system synchronized with the positive phase, it is possible to easily handle the two virtual generators in the rotating coordinate system.

  According to the present invention, in a power conversion device connected between a single-phase three-wire type power system and a distributed power source, switching between system interconnection operation and self-sustaining operation can be performed without requiring switching of control modes. The transition can be performed without interruption.

FIG. 1 is a control block diagram showing a power conversion device according to an embodiment of the present invention. FIG. 2 is a diagram showing a schematic configuration of an inverter in the power conversion device shown in FIG. FIG. 3 is a block diagram showing the configuration of the frequency command value calculation unit in the present embodiment. FIG. 4 is a block diagram showing the configuration of the automatic voltage regulator according to the present embodiment. FIG. 5 is a diagram showing vectors in the synchronous coordinate system of the system voltage and the induced voltage in the present embodiment. FIG. 6 is a block diagram showing the configuration of the phase difference angle generation unit in the first modified example of the present embodiment. FIG. 7 is a block diagram showing the configuration of the phase difference angle generator in the second modification of the present embodiment. FIG. 8 is a block diagram showing the configuration of a system to which the power conversion device in this simulation is applied. FIG. 9A is a graph showing a simulation result in the first case, which is a graph showing changes in power consumption of a load with time. FIG. 9B is a graph showing a simulation result in the first case, and is a graph showing a change over time in the output voltage of the second power generation device. FIG. 9C is a graph showing a simulation result in the first case, and is a graph showing a change over time in the output voltage of the first power generation device. FIG. 9D is a graph showing a simulation result in the first case, which is a graph showing changes in frequency with time. FIG. 9E is a graph showing a simulation result in the first case, and is a graph showing a change in phase difference angle with time. FIG. 9F is a graph showing the simulation result in the first case, and is a graph showing the change over time of the effective value of the system voltage. FIG. 10A is a graph showing a simulation result in the second case, which is a graph showing a change over time in power consumption of a load. FIG. 10B is a graph showing a simulation result in the second case, and is a graph showing a change over time in the output voltage of the second power generation device. FIG. 10C is a graph showing a simulation result in the second case, and is a graph showing a change over time in the output voltage of the first power generation device. FIG. 10D is a graph showing a simulation result in the second case and showing a change in frequency with time. FIG. 10E is a graph showing a simulation result in the second case, and is a graph showing a change in phase difference angle with time. FIG. 10F is a graph showing the simulation result in the second case, and is a graph showing the change over time in the effective value of the system voltage.

  Embodiments of the present invention will be described below with reference to the drawings. In the following, elements having the same or the same functions are denoted by the same reference symbols throughout all the drawings, and duplicated description thereof will be omitted.

  FIG. 1 is a control block diagram showing a power conversion device according to an embodiment of the present invention. The power conversion device 1 in the present embodiment is connected between the distributed power supply 2 and the single-phase three-wire power system 3. The distributed power source 2 is a power source facility such as a photovoltaic power generation facility, a fuel cell power generation facility, and a power storage facility. The single-phase three-wire type power system 3 includes a first voltage line 3a, a second voltage line 3c, and a neutral voltage line 3b. The power system 3 is introduced as a small-capacity system into a general home or the like, and is connected to the distributed power source 2 via the power converter 1.

The power conversion device 1 includes an inverter 4 that connects the distributed power supply 2 and the power system 3. FIG. 2 is a diagram showing a schematic configuration of an inverter in the power conversion device shown in FIG. As shown in FIG. 2, the inverter 4 has a pair of input terminals connected to the distributed power source 2 and three output terminals connected to the respective voltage lines 3 a to 3 c of the power system 3. In this way, the inverter 4 can be realized by operating a three-phase inverter that outputs three-phase alternating current from a direct-current voltage as a single-phase three-wire inverter. A total of six switching elements 41 to 46 are provided, two for each of the output units 4a, 4b, and 4c connected to the power system 3. The inverter 4 has a PWM signal generation unit 47 that converts voltage command values v _a ^* , v _b ^* , v _c ^* from the controller 8 described later into a PWM signal. The PWM signal converted based on the voltage command values v _a ^* , v _b ^* , v _c ^* is sent to each switching element 41 to 46 as a gate drive signal S1 to S6 for switching on/off of each switching element, The DC voltage output from the distributed power supply 2, which is a DC power supply facility, is converted into a single-phase three-wire AC voltage. The output units 4a, 4b, 4c are connected to the respective voltage lines 3a, 3b, 3c of the power system 3 via a filter circuit 5 including a coil, a capacitor and the like.

The power conversion device 1 includes, on the power system side of the inverter 4, the first output current i _a of the first output unit 4a connected to the first voltage line 3a and the second output unit 4c connected to the second voltage line 3c. Current measuring device 6 for respectively measuring the second output current i _c of the power system 3, the first system voltage v _g1 in the first voltage line 3a for the neutral voltage line 3b of the power system 3, and the second voltage line for the neutral voltage line 3b. 3c, the voltage measuring instrument 7 which respectively measures the 2nd system voltage _vg2 . Known configurations can be applied to the configurations of the current measuring device 6 and the voltage measuring device 7.

The power conversion device 1 includes a controller 8 that controls switching of each of the switching elements 41 to 46 of the inverter 4. The controller 8 generates the voltage command values v _a ^* , v _b ^* , v _c ^* based on the current measured by the current measuring device 6 and the voltage measured by the voltage measuring device 7.

The controller 8 is composed of a computer such as a microcontroller and/or various electronic circuit elements. The controller 8 has a first virtual generator connected between the first voltage line 3a and the neutral voltage line 3b, and a second virtual generator between the second voltage line 3c and the neutral voltage line 3b. Control is performed to generate the voltage command values v _a ^* , v _b ^* , v _c ^* on the assumption that the virtual generator is connected. That is, the controller 8 controls the power converter 1 with two systems of virtual generators (virtual synchronous generators) for the first voltage line 3a and the second voltage line 3c in the single-phase three-wire power system 3. Control as a system. At this time, since the neutral voltage line 3b is constant as the reference voltage, the voltage command value v _b ^* is always 0 in the present embodiment.

The controller 8 includes, as functional blocks, a phase difference angle generator 9, an induced voltage generator 10, and a current command value generator 11. The phase difference angle generator 9 generates a virtual frequency command value ω _R for each virtual generator from the current and voltage measured by the current measuring device 6 and the voltage measuring device 7, and integrates the frequency command value ω _R. Then, the phase angle command value θ _R is generated.

In the present embodiment, the phase difference angle generator 9 uses the first output current i _a , the second output current i _c , the first system voltage v _g1 and the second system voltage v _{g2 as} the first virtual generator and the second virtual generator. Of the active power calculation unit (total active power calculation unit) 12 that calculates the total P of active power by the virtual generator, and the frequency command value from the total P of active power, the active power command value P ^*, and the reference frequency ω ^*. (Common frequency command value) ω _R frequency command value calculation unit (common frequency command value calculation unit) 13 is provided.

As will be described later, in the virtual generator control according to the present embodiment, each value is handled on the rotating coordinate system (dq coordinate system) synchronized with the positive phase. For this reason, the total P of active powers also needs to be expressed using the positive phase component. Here, the active power P ₁ from the first virtual generator is represented by P ₁ =2(v _g1d ⁺ i _ad ⁺ +v _g1q ⁺ i _aq ⁺ ) and the active power P ₂ from the second virtual generator is P ₂ = ₂ because it is expressed by ^{_{(v g2d + i cd + +}} v g2q + i cq +), the sum P of the active ^{_{power, P = P 1 + P 2}} = 2 (v g1d + i ad + + v g1q + i aq ^{_{+ + v g2d + i cd +}} + v represented by g2q _{⁺ i cq +).} The active power calculation unit 12 calculates the total P of active power based on the above formula.

FIG. 3 is a block diagram showing the configuration of the frequency command value calculation unit in the present embodiment. As shown in FIG. 3, the total sum P of active powers calculated by the active power calculation unit 12 is subtracted from the active power command value P ^* , and the difference is input to the first-order delay calculator 14. The first-order delay calculator 14 is adjusted so as to have a predetermined drooping characteristic and an inertial effect showing a tracking delay between the total sum P of active powers and the frequency command value ω _R.

In the present embodiment, the first-order delay calculator 14 outputs the calculation result using the transfer function K _G (s)=K _gd /(1+T _g s). Here, K _gd is a coefficient showing the frequency droop characteristic in each virtual generator, and T _g is a time constant showing the characteristic of the tracking delay of the rotation speed due to inertia in each virtual generator. This makes it possible to easily realize a control mode simulating governor control using active power in a virtual generator. The frequency command value calculation unit 13 adds the predetermined reference frequency ω ^* to the calculation result of the first-order delay calculator 14 to generate the frequency command value ω _R. In this way, the phase difference angle generator 9 generates the common frequency command value ω _R between the first virtual generator and the second virtual generator. Phase angle generating unit 9 has an integrator 15 for integrating the frequency command value omega _R, generates a phase angle command value theta _R by integrating the frequency command value omega _R.

Further, the phase difference angle generation unit 9 has phase angle generation units 161, 162 that generate the phase angles θ ₁ , θ ₂ of each virtual generator from the first system voltage v _g1 and the second system voltage v _g2 . The phase angle generators 161 and 162 respectively include normal phase extraction units 171 and 172 that extract positive phase components of the system voltages v _g1 and v _g2 .

The normal phase extraction units 171 and 172 respectively extract the normal phase component from the single phase signal. A single-phase signal can be represented as the sum of a positive-phase signal and a negative-phase signal. For example, the first system voltage is represented as v _g1 =v _g1 ⁺ +v _g1 ⁻ . As described above, in the present embodiment, the positive phase component of the signal is represented by adding + to the right shoulder of the code indicating the signal, and the negative phase component of the signal is the right shoulder of the code indicating the signal. Is represented by a-. In the virtual generator control according to the present embodiment, each value is handled on the rotating coordinate system (dq coordinate system) synchronized with the positive phase. Therefore, two-phase signals (d-axis components v _g1d ⁺ , v _g2d ⁺ and q-axis components v _g1q ⁺ , v) are extracted by extracting the positive-phase components of the system voltages v _g1 and v _g2 that are the single-phase signals. _g2q ⁺ , and in some cases, they are collectively referred to as v _g1dq ⁺ and v _g2dq ⁺ ). As a method of extracting the positive phase components of the system voltages v _g1 and v _g2 , a known method such as DDSRF (Double Decoupled Synchronous Reference Frame) and DSOGI (Dual Second Order Gneralized Integrator) can be adopted.

In addition, the phase angle generators 161 and 162 receive the q-axis component of the positive phase components of the system voltages v _g1 and v _g2 as an input, and rotate the coordinate system in synchronization with each positive phase via the proportional integral (PI) element. rotation frequency omega _1, the frequency calculation unit 181 and 182 for outputting omega _2, the rotation frequency omega _1, the phase angle theta ₁ of the system voltage by integrating omega _2, an integrator 191, 192 to generate a theta ₂ I have it. The phase angles θ ₁ and θ ₂ output from the integrators 191 and 192, respectively, are fed back to the corresponding normal phase extraction units 171 and 172, so that the phase angle generation units 161 and 162 can perform PLL (Phase Locked). Loop) forming a control circuit.

The phase difference angle generation unit 9 subtracts the phase angles θ ₁ and θ ₂ of the virtual generators generated by the phase angle generation units 161 and 162 from the phase angle command value θ _R to calculate the virtual phase difference angle of each virtual generator. Calculate δ ₁ and δ ₂ .

The induced voltage generator 10 includes a reactive power calculator 201 that calculates the reactive power Q ₁ from the first virtual generator from the first output current i _a and the first system voltage v _g1 , and the second output current i _c and the second output current i _c . The reactive power calculation unit 202 that calculates the reactive power Q ₂ by the second virtual generator from the two-system voltage v _g2 , the respective reactive powers Q ₁ and Q ₂ , the magnitude of the first system voltage |v _g1 | Automatic voltage adjustment for calculating induced voltages E _f1 and E _f2 of each virtual generator from the magnitude |v _g2 | of the two system voltages, each reactive power command value Q ₁ ^* , Q ₂ ^*, and the reference voltage v _g ^* And parts 211 and 212.

As described above, in the virtual generator control according to the present embodiment, each value is handled on the rotating coordinate system (dq coordinate system) synchronized with the positive phase. Therefore, the reactive power also needs to be expressed using the positive-phase component. Here, the reactive power Q ₁ by the first virtual generator is represented by Q ₁ =2(−v _g1d ⁺ i _aq ⁺ +v _g1q ⁺ i _ad ⁺ ), and the reactive power Q ₂ by the second virtual generator is Q ₂ = represented by ^{_{2 (-v g2d + i cq +}} + v g2q + i cd +). The reactive power calculation units 201 and 202 calculate the reactive powers Q ₁ and Q ₂ of the corresponding electric motors based on the above equations, respectively.

FIG. 4 is a block diagram showing the configuration of the automatic voltage regulator according to the present embodiment. In FIG. 4, the two automatic voltage adjusting units 211 and 212 are collectively referred to as an automatic voltage adjusting unit 21n (n=1, 2), and the corresponding reactive powers Q ₁ , Q ₂ etc. are also called Q _n etc. write. As shown in FIG. 4, the automatic voltage adjuster 21n are multiplied by a coefficient K _ad showing a voltage droop characteristic to the difference between the reactive power Q _n and the reactive power command value Q _n ^*, the result to a reference voltage V _R ^* in addition the voltage command value calculating portion 22n that generates a voltage command value V _Rn, the size of the voltage command value V _Rn, the corresponding voltage measured by the voltage measuring instrument 7 | V _{gn |} the difference between the proportional integral And a PI computing unit 23n for computing.

The PI calculation unit 23n performs a proportional integral calculation using a transfer function K _A (s)=K _ap +K _ai /s, which is a value obtained by subtracting the corresponding voltage magnitude |v _gn | from the voltage command value V _nR . Here, K _ap is a coefficient indicating a proportional element, and K _ai is a coefficient indicating an integral element. The calculation result of the PI calculation unit 23n is output as the induced voltage E _fn . For the magnitudes |v _g1 | and |v _g2 | of each system voltage, the positive phase components v _g1dq ⁺ and v _g2dq ⁺ of the voltage are extracted from the system voltages v _g1 and v _g2 in the respective positive phase extraction units 241 and 242. Obtained from the results. The normal phase extraction units 241 and 242 have the same configuration as the normal phase extraction units 171 and 172 in the phase difference angle generation unit 9, and are described as separate configurations in the present embodiment for easy understanding in the drawings. However, 171 and 241 may be shared, and 172 and 242 may be shared.

As described above, by applying the voltage droop characteristic to the difference between the reactive powers Q ₁ and Q ₂ and the reactive power command value Q _n ^* , the virtual power generator automatically uses the reactive powers Q ₁ and Q ₂ A control mode simulating voltage regulation (AVR) control can be easily realized.

The current command value generator 11 includes the system voltages v _g1 and v _g2 measured by the voltage measuring device 7, the phase difference angles δ ₁ and δ ₂ , the induced voltages E _f1 and E _f2, and the inside of each predetermined virtual generator. From the impedance z, the current command values i _adq ^* , i _cdq ^* of each virtual generator are generated. The current command value generation unit 11 is input with the first system voltage v _g1 , the phase difference angle δ ₁ in the first virtual generator and the induced voltage E _f1, and outputs the current command value i _adq ^* in the first virtual generator. The first current command value generation unit 251, the second system voltage v _g2 , the phase difference angle δ ₂ of the second virtual generator and the induced voltage E _f2 are input, and the current command value i _cdq of the second virtual generator is input. ^And a second current command value generation unit 252 that outputs ^* . The internal impedance z is common to the first virtual generator and the second virtual generator.

  In the present embodiment, the controller 8 extracts the positive phase components of the current and voltage measured by the current measuring device 6 and the voltage measuring device 7, and synchronizes the extracted positive phase components of the respective values with the positive phase. The current command value of each virtual generator is generated by handling it in the rotating coordinate system. By extracting the positive phase component of each value and configuring the virtual generator on the rotating coordinate system synchronized with the positive phase, it is possible to easily handle the two virtual generators in the rotating coordinate system.

FIG. 5 is a diagram showing vectors in the synchronous coordinate system of the system voltage and the induced voltage in the present embodiment. As described above, since the system voltages v _g1 and v _g2 are single-phase voltages, their positive phase components are extracted and converted into two-phase signals. In FIG. 5, the d axis is the real number axis (horizontal axis) and the q axis is the imaginary number axis (vertical axis). As shown in FIG. 5, the phase difference angles δ ₁ and δ ₂ represent the angles formed by the system voltages v _g1 and v _g2 and the induced voltages E _f1 and E _f2 . Therefore, in the synchronous coordinate systems of the first system and the second system in which the d axis is the real axis and the q axis is the imaginary axis, the induced voltages E _f1 and E _f2 are E _f1 e ^jδ1 , E _f2 e ^jδ2 and the vector Can be expressed. The current command values i _adq ^* , i _cdq ^* of each electric motor are given as the vector difference between the induced voltages E _f1 , E _f2 and the system voltages v _g1 , v _g2 in the synchronous coordinate system divided by the internal impedance z. That is, the current command value for the first virtual generator is given by i _adq ^* =(E _f1 e ^jδ1- v _g1dq ⁺ )/z, and the current command value for the second virtual generator is i _cdq ^* =(E It is given by _f2 e ^jδ2- v _g2dq ⁺ )/z.

Since the system voltages v _g1 and v _g2 are based on the neutral voltage line 3b, voltages of opposite signs are generated for the same voltage command value in the synchronous coordinate system. That is, the voltages v _g1dq and v _g2dq are vectors in mutually opposite directions on the synchronous coordinate system. Therefore, between the first voltage line 3a and the second voltage line 3c, a voltage that is twice the voltage on the first voltage line 3a or the second voltage line 3c is output.

Further, the phase difference angles δ ₁ and δ ₂ (=θ _R −θ ₁ and θ _R −θ ₂ ) rotate with the coordinate system rotating with the frequency command value ω _R and the frequencies ω ₁ and ω ₂ . The voltages v _g1dq and v _g2dq are angles relative to the coordinate system and are vectors synchronized with the coordinate system rotating at frequencies ω ₁ and ω ₂ , respectively. Therefore, the induced voltages E _f1 and E _f2 are both rotating at the phase angle (command value) θ _R in synchronization with the coordinate system rotating at the frequency command value ω _R. The frequencies ω ₁ and ω ₂ transiently differ from the frequency command value ω _R , but in the steady state, they match the frequency command value ω _R.

The controller 8 switches the inverter 4 so that the currents i _a and i _c measured by the current measuring device 6 become the current command values i _adq ^* and i _cdq ^* . That is, the controller 8 does not directly generate and control the voltage command value and the frequency command value with respect to the system voltages v _g1 and v _g2 and the system frequencies ω ₁ and ω ₂ , but controls the internal variables corresponding to the generator. And the parameters, that is, the phase difference angles δ ₁ , δ ₂ , the induced voltages E _f1 , E _f2 and the internal impedance z are introduced to control so as to output a current simulating the characteristics of the generator.

In the present embodiment, the controller 8 converts the current command values i _adq ^* , i _cdq ^* into the voltage command values v _a ^* , v _c ^* , and then outputs the voltage command values v _a ^* , v _c ^* to the inverter 4. The current command values i _adq ^* , i _cdq ^* generated by the current command value generation unit 11 are command values for the positive phase current, and therefore the currents i _a , i measured by the current measuring device 6 to be compared with the current command values i _adq ^* , i _cdq ^* _{As for c, the} normal phase components i _adq ⁺ and i _cdq ⁺ are also extracted by the normal phase extraction units 261 and 262. The controller 8 subtracts i _adq ⁺ , i _cdq ⁺ extracted by the positive phase extraction units 261 and 262 from the current command values i _adq ^* and i _cdq ^* , and the deviation is input to the PI compensators 271 and 272. .. The PI compensators 271 and 272 perform PI compensation on the basis of the input deviation to convert it into a voltage command value. The voltage command values output from the PI compensators 271, 272 are the positive phase components v _ad ^* , v _aq ^* of the voltage command value v _a ^{* in} the synchronous coordinate system and the positive phase components of the voltage command value v _c ^{* in} the synchronous coordinate system. The components are v _cd ^* and v _cq ^* .

The controller 8 converts the positive phase components v ad * , v aq * , v cd * , v cq * into single-phase current command values v a * , v c * in the fixed coordinate system. , 282. The voltage command conversion unit 281 converts the positive phase components v ad * , v aq * and the phase angle θ 1 of the voltage command value in the first virtual generator from the conversion formula v a * =2(v ad * cos θ 1 −v aq. * Sin θ 1 ) is used to output the voltage command value v a * for the first voltage line 3a. Similarly, the voltage command conversion unit 282, the positive phase component of the voltage command value in the second virtual generator v cd *, v cq * and the phase angle theta 2, the conversion equation v c * = 2 (v cd * cosθ 2 -V cq * sin θ 2 ) is used to output the voltage command value v c * for the second voltage line 3c.

The controller 8 inputs the voltage command values v _a ^* , v _c ^* thus obtained and the voltage command value v _b ^* =0 for the neutral voltage line 3 b to the PWM signal generation unit 47 of the inverter 4.

  According to the above configuration, between the first voltage line 3a and the neutral voltage line 3b of the single-phase three-wire power system 3 and between the second voltage line 3c and the neutral voltage line 3b, respectively. Assuming that a virtual generator is connected, switching of the inverter 4 to which the first voltage line 3a, the second voltage line 3c and the neutral voltage line 3b are connected is controlled. With this, with a simple configuration, it is possible to perform the transition between the grid interconnection operation and the self-sustaining operation in the first voltage line 3a and the second voltage line 3c without interruption without requiring switching of control modes. it can.

  Further, in the present embodiment, the control of the frequency and the voltage is individually performed by the first virtual generator and the second virtual generator, while the control of the active power is performed by the total load of the power system 3. Will be done in a batch.

More specifically, by forming a PLL control loop based on the phase angles θ ₁ and θ ₂ of each virtual generator by the phase angle generators 161 and 162, independent voltage command values v _a between virtual generators. ^* , v _c ^* are generated. Therefore, in the case where the load connected between the first voltage line 3a and the neutral voltage line 3b does not match the load connected between the second voltage line 3c and the neutral voltage line 3c. Even if there is, independent virtual generator control can be performed in each case.

On the other hand, a common frequency command value ω _R is generated from the total sum P of active power between the two virtual generators. As a result, the control loop of active power is shared between the two virtual generators. That is, since the phase angle command values θ _R of the induced voltages E _f1 and E _f2 between the two virtual generators are made common, the phases of the induced voltages E _f1 and E _f2 match. Therefore, it is possible to synchronize the two virtual generators (the synchronous coordinate systems of the virtual generators) with each other, and not only the first system voltage v _g1 and the second system voltage v _g2 but also the first voltage line 3a and The voltage v _g21 (200 V) between the two voltage lines 3c can be maintained. Although there is no direct control loop for the voltage v _g21 between the first voltage line 3a and the second voltage line 3c, the load between the first voltage line 3a and the second voltage line 3c is not present. Seen from the inverter 4, it can be regarded that they are equivalently connected to the first voltage line 3a and the second voltage line 3b, and as a result, they are stabilized by the control loop by each virtual generator.

The induced voltages E _f1 and E _f2 themselves are calculated based on the reactive powers Q ₁ and Q ₂ for each virtual generator. In the reactive power control loop, even if the actual load and the command value do not match at the time of self-sustaining operation, the induced voltage E _f1 and E _f2 are adjusted by the active power control loop, so that a proper state is obtained. Calm down. Therefore, the control loop of the reactive power can be enhanced by providing the control loop for each virtual generator individually.

[Modification]
Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various improvements, changes and modifications can be made without departing from the spirit of the present invention.

For example, in addition to the above-described aspect in which the phase difference angle generation unit 9 generates the common frequency command value ω _R between the first virtual generator and the second virtual generator, the first virtual generator and the first virtual generator The phase angle θ _{1 is} adjusted by adjusting the phase angle (eg, θ ₂ ) of one of the two virtual generators based on the phase angle (eg, θ ₁ ) of the other of the first virtual generator and the second virtual generator. , Θ ₂ may be provided with a phase angle error correction unit 29 (FIG. 6).

FIG. 6 is a block diagram showing the configuration of the phase difference angle generation unit in the first modified example of the present embodiment. In FIG. 6, the same components as those in the above embodiment are designated by the same reference numerals, and the description thereof will be omitted. As shown in FIG. 6, the phase difference angle generation unit 9B in the first modified example includes a phase angle error correction unit 29, and the phase angle error correction unit 29 corresponds to the phase angle θ _{1 of} the first virtual generator. By providing a proportional calculator 30 that proportionally calculates the difference from the phase angle θ ₂ of the second virtual generator, and adding the proportional calculation result in the proportional calculator 30 to the frequency ω ₂ of the second virtual generator, It is configured to correct the error between the angles θ ₁ and θ ₂ . The corrected frequency ω ₂ ′ obtained by adding the correction amount of the phase angle output from the proportional calculator 30 to the frequency ω ₂ of the second virtual generator output from the frequency calculator 182 is input to the integrator 192. Then, the corrected phase angle θ ₂ is generated by integrating this.

In some cases, the phase angles θ ₁ and θ ₂ held by the integrators 191 and 192 in the PLL control loops of the phase angle generators 161 and 162 may be greatly deviated from each other due to an error due to a sudden load change or the like. Conceivable. If a large deviation of the phase angles θ ₁ and θ ₂ occurs during self-sustaining operation, the deviation of the phase angles θ ₁ and θ ₂ cannot be recovered by the configuration of FIG. On the other hand, according to the first modified example, when the phase angles θ ₁ and θ ₂ output from the phase angle generators 161 and 162 are different, one of the phase angles θ ₁ is set according to the difference. The other phase angle θ ₂ is corrected so as to approach. Therefore, the deviation of the phase angles θ ₁ and θ ₂ of the voltages V _g1 and V _g2 between the two virtual generators can be reduced regardless of the configuration of the control loop of active power. As a result, the voltage between the first voltage line 3a and the second voltage line 3c can be stabilized.

The correction amount output from the proportional calculator 30 is set to an amount that does not affect the operation of the virtual generator. Moreover, if a compensator including an integral calculation element is used instead of the proportional calculator 30 that generates the correction component, the phase angles θ ₁ and θ ₂ of the two virtual generators always operate so as to match each other. When the load connected between the first voltage line 3a and the neutral voltage line 3b and the load connected between the second voltage line 3c and the neutral voltage line 3b become unbalanced , Each virtual generator control will not be performed properly. Therefore, by using the proportional calculator 30 as a calculator for compensating the deviation between the phase angles θ ₁ and θ ₂ , the deviation can be allowed to some extent, and the phase angle can be controlled while operating the virtual generator control of the two systems appropriately. When the deviation between θ ₁ and θ ₂ becomes large, this can be corrected.

When the phase angle error correction unit 29 as described above is provided, the phase difference angle generation unit 9 separates the frequency command values ω _{1R for} the first virtual generator and the second virtual generator from each other. , Ω _2R , that is, the individual phase angle command values θ _1R and θ _2R may be generated. FIG. 7 is a block diagram showing the configuration of the phase difference angle generator in the second modification of the present embodiment. In FIG. 7, the same components as those in the above-described embodiment and the first modification are designated by the same reference numerals, and the description thereof will be omitted.

As illustrated in FIG. 7, the phase difference angle generation unit 9C in the second modified example calculates the first active power P ₁ by the first virtual generator from the first output current i _a and the first system voltage v _g1 . A first active power calculation unit 121, and a second active power calculation unit 122 that calculates the second active power P ₂ from the second virtual generator from the second output current i _c and the second system voltage v _g2 . ing. In the present modification, the first active power calculation unit 121 outputs active power P ₁ =2 (v _g1d ⁺ i _ad ⁺ +v _g1q ⁺ i _aq ⁺ ) from the first virtual generator, and the second active power calculation unit 121. 122, active power _P 2 ₌ ² according to the second virtual power generator ^{_{(v g2d + i cd + +}} v g2q + i cq +) outputs a.

Further, the phase difference angle generation unit 9C generates a first frequency command value ω _1R for the first virtual generator from the first active power P ₁ , the first active power command value P ₁ ^*, and the reference frequency ω ^*. a first frequency command value calculator 131, and a first integrator 151 to generate a first phase-angle command value theta _1R by integrating the first frequency command value omega _1R, the. Further, the phase difference angle generation unit 9C also applies the second frequency command value ω _2R from the second active power P ₂ , the second active power command value P ₂ ^*, and the reference frequency ω ^{* in the same} manner for the second virtual generator. It includes a second frequency command value calculating section 132 for generating a second integrator 152 to generate a second phase-angle command value theta _2R by integrating the second frequency command value omega _2R, the a.

According to this modification, the two virtual generators can be synchronized with each other by correcting the error between the phase angles θ ₁ and θ ₂ of the two virtual generators.

Further, in the above embodiment, in the reactive power control loop, the reactive powers (Q ₁ , Q ₂ ) input to the automatic voltage adjusting units 211, 212 and their command values (Q ₁ ^* , Q ₂ ^* ) are set. Although the individual values are used, the total reactive power Q and the command value Q ^* thereof may be input to both of the automatic voltage adjusting units 211 and 212. In this case, the sum Q of the reactive power _is given by ^{_{Q = Q 1 + Q 2 =}} 2 (-v g1d + i aq + + v g1q + i ad + -v g2d + i cq + + v g2q + i cd +).

[simulation result]
By showing the simulation result in the power conversion device 1 of the above-described embodiment, the power conversion device 1 of the above-described embodiment shifts from grid interconnection to disconnection, and load sharing with other power generation devices. It is shown that the operation of is preferably performed. In this simulation, the switching of the control mode and the parameter change in the power conversion device 1 are not performed at all during the operation.

  FIG. 8 is a block diagram showing the configuration of a system to which the power conversion device in this simulation is applied. As shown in FIG. 8, in this simulation, the first power generation device 2A, which is a distributed power source, is connected to the power conversion device 1 in the above-described embodiment, and the first power generation device 2A includes a solar power generation device and the like. The second power generator 2B based on another inverter system is configured to be connected to the power system 3 in parallel.

  The second power generator 2B controls the current flowing into the power system 3 in synchronization with the power system 3 in the system interconnection state. For example, in a solar power generation device, control is performed to flow a current according to the amount of solar power generation into the power system 3. The first power generator 2A is controlled by the power converter 1 in the above-described embodiment, that is, the frequency droop characteristic for active power, the voltage droop characteristic for reactive power, and the frequency fluctuation characteristic simulating the inertia effect.

That is, since the first power generator 2A outputs the frequency and voltage according to the droop characteristic based on the reference frequency ω ^* and the reference voltage v ^* in the power converter 1 during the self-sustained operation, the first power generator 2A should also be stopped during the grid disconnection. Continue driving without. Therefore, the second power generators 2B arranged in parallel continue to operate while the first power generator 2A is regarded as a power system even when the grid is disconnected. The reference frequency ω ^* and the reference voltage v ^* in the power conversion device 1 are set to the same values as the reference frequency and the reference voltage of the power system 3. The first power generation device 2A is connected to the power system 3 via the power conversion device 1 by three lines, but the second power generation device 2B is normally two lines between the first voltage line 3a and the second voltage line 3c. Connect to.

  In this simulation, the following two cases were simulated. In the first case, the first power generation device 2A is connected to the power system 3 and the load L1 is connected between the first voltage line 3a and the neutral voltage line 3b (for 3 seconds). The simulation has started from (point of time). 9A to 9F are graphs showing simulation results in the first case. FIG. 9A shows the time-dependent change in the power consumption of the load, FIG. 9B shows the time-dependent change in the output voltage of the second power generator, and FIG. 9C shows the time-dependent change in the output voltage of the first power generator. 9D shows a change in frequency with time, FIG. 9E shows a change in phase difference angle with time, and FIG. 9F shows a change in effective value of system voltage with time.

As shown in FIG. 9A, at the first time point (at the time point of 3 seconds), the first power generation device 2A is connected to the power system 3, and the first voltage line 3a and the neutral voltage line 3b have 600 W of power. A load L1 is connected (shown as PL_1 in FIG. 9A). Since the load is not connected between the second voltage line 3c and the neutral voltage line 3b, PL_2 is 0 in FIG. 9A, and the total load value PL matches PL_1. Since the power to the load L1 is supplied from the power grid 3, the active power command value P ^* of the first power generator 2A is 0, and as shown in FIG. 9C, the first voltage line of the first power generator 2A. Output power PgB_1 between 3a and the neutral voltage line 3b, output power PgB_2 between the second voltage line 3c and the neutral voltage line 3b, and their sum PgB are all zero.

After that, when the first power generation device 2A and the power system 3 are disconnected at the time of 4 seconds, the first power generation device 2A becomes the independent operation. Therefore, as shown in FIG. 9C, the power supply to the load L1 is handled by the first voltage line 3a of the first power generator 2A (PgA_1 in FIG. 9C changes from 0 W to 600 W). At this time, since the active power command value P ^* remains 0, as shown in FIG. 9D, the frequencies ω ₁ and ω ₂ are the reference frequencies ω ^* (60 Hz at the time of 3 seconds) due to the frequency droop characteristic with respect to the active power. However, it is smoothly shifting to independent operation.

  Then, as shown in FIG. 9B, at 6 seconds, the second power generator 2B is connected between the first voltage line 3a and the second voltage line 3b, and at 8 seconds, the sum PgB of the electric power of 400 W is output. ing. Since this electric power is supplied between the first voltage line 3a and the second voltage line 3c, electric power of 200 W (PgB_1, PgB_2 in FIG. 9B) is supplied to the first voltage line 3a and the second voltage line 3b. To be done.

  As a result, 200 W of the power consumption of 600 W of the load L1 is supplied from the second power generation device 2B. The remaining 400 W is continuously supplied by the first power generator 2A. As a result, as shown in FIG. 9C, the output power PgA_1 between the first voltage line 3a and the neutral voltage line 3b of the first power generator 2A decreases from 600W to 400W. On the other hand, in this case, since there is no load between the third voltage line 3c and the neutral voltage line 3b, the electric power 200W supplied from the second power generation device 2B to the second voltage line 3b becomes surplus. Therefore, the first power generation device 2A absorbs the electric power (PgA_2 changes from 0 W to −200 W in FIG. 9C).

That is, the sum PgA of active power of the first power generator 2A after the time point of 8 seconds is reduced to 200W. Along with this, the frequencies ω ₁ and ω ₂ increase.

Then, as shown in FIG. 9A, when the load L1 decreases from 600 W to 200 W at the time of 12 seconds, all the power of the load L1 can be covered by 200 W supplied from the second power generation device 2B. The output power PgA_1 between the first voltage line 3a and the neutral voltage line 3b of the single power generation device 2A decreases from 400W to 0W. As a result, the first power generator 2A only performs the absorbing operation of the electric power 200W supplied from the second power generator 2B to the second voltage line 3b. That is, the sum PgA of the electric power of the first power generator 2A after the time point of 12 seconds is -200W. Along with this, the frequencies ω ₁ and ω ₂ further rise to a value exceeding the reference frequency ω ^* (60 Hz).

As described above, in this case, appropriate power supply to the load L1 is performed without switching the control mode by the power conversion device 1 according to the grid interconnection, the parallel disconnection, and the load fluctuation. It has been shown. Further, the phase difference angles δ ₁ and δ ₂ between the first voltage line 3a and the second voltage line 3c of the first power generator 2A independently vary according to the loads on the voltage lines 3a and 3c.

  Next, the second case will be described. In the second case, when the first power generator 2A is connected to the power system 3 and the load L2 of 1.2 kW is connected between the first voltage line 3a and the second voltage line 3c. The simulation starts from (at the time of 3 seconds). 10A to 10F are graphs showing simulation results in the second case. 10A to 10F show graphs corresponding to FIGS. 9A to 9F in the first case, respectively.

At the time of 3 seconds, since the power to the load L2 is supplied from the power grid 3, the active power command value P ^* of the first power generation device 2A is 0, and as shown in FIG. The output power PgA_1 between the first voltage line 3a and the neutral voltage line 3b of the device 2A, the output power PgA_2 between the second voltage line 3c and the neutral voltage line 3b, and their sum PgA are all zero. is there.

After that, when the first power generation device 2A and the power system 3 are disconnected at the time of 4 seconds, the first power generation device 2A becomes the independent operation. Therefore, as shown in FIG. 10C, the first power generation device 2A takes charge of power supply to the load L2. Since the load L2 is connected between the first voltage line 3a and the second voltage line 3c, the first power generator 2A supplies 600W to the first voltage line 3a and the second voltage line 3c, respectively. To do. At this time, since the active power command value P ^* remains 0, as shown in FIG. 10D, the frequencies ω ₁ and ω ₂ are reduced due to the droop characteristic, but the operation is smoothly shifted to the self-sustained operation.

  Then, as shown in FIG. 10B, at 6 seconds, the second power generator 2B is connected between the first voltage line 3a and the second voltage line 3c, and at 8 seconds, the sum PgB of the power of 800 W is output. ing. Since this electric power is supplied between the first voltage line 3a and the second voltage line 3c, electric power of 400 W (PgB_1, PgB_2 in FIG. 10B) is supplied to the first voltage line 3a and the second voltage line 3b. To be done.

As a result, 800 W of the 1.2 kW of power consumption of the load L2 is supplied from the second power generator 2B. The remaining 400 W is continuously supplied by the first power generator 2A. As a result, as shown in FIG. 10C, the output power PgA_1 between the first voltage line 3a and the neutral voltage line 3b of the first power generator 2A and the second voltage line 3c and the neutral voltage of the first power generator 2A. The output power PgA_2 between the line 3b and the line 3b both decreases from 600 W to 200 W. Along with this, the frequencies ω ₁ and ω ₂ increase.

Then, as shown in FIG. 10A, when the load L2 decreases from 1.2 kW to 400 W at 12 seconds, 400 W of the sum PgB of 800 W of electric power supplied from the second power generator 2B is the load L2. The remaining 400 W is consumed and the first power generation device 2A absorbs the remaining 400 W. Therefore, as shown in FIG. 10C, the output powers PgA_1 and PgA_2 of the first power generation device 2A are both −200 W. Along with this, the frequencies ω ₁ and ω ₂ further rise to a value exceeding the reference frequency ω ^* (60 Hz).

As described above, also in this case, appropriate power supply to the load L2 is performed without switching the control mode by the power conversion device 1 according to the grid interconnection, the parallel disconnection, and the load fluctuation. It has been shown. Further, in this case, since the voltage lines 3a and 3c connected to the second power generator 2B and the voltage lines 3a and 3c connected to the load L2 are the same, the first power generator 2A is The same electric power is output from the voltage line 3a and the second voltage line 3c, and the phase difference angles δ ₁ and δ ₂ also fluctuate in a mutually matched state.

  In any case, in the case of self-sustaining operation, the internal AC filter serves as a load, so a reactive current flows, and the effective values Vg_1N and Vg_2N of the system voltage slightly change due to the action of the reactive power control in the power converter 1. However, it can be said that there is no problem in practical use.

  As described above, it was shown by the simulation that the power conversion device 1 in the above-described embodiment exhibits effects that cannot be achieved by the conventional single-phase three-wire power conversion device. That is, the power conversion device 1 in the above-described embodiment can realize the transition between the interconnected operation and the self-sustaining operation in the single-phase three-wire system without interruption of the control mode, without requiring switching. . Furthermore, parallel operation and load sharing with another inverter-type power generation device 2B can be realized without switching any control mode.

  A power conversion device according to the present invention, in a power conversion device connected between a single-phase three-wire type power system and a distributed power source, does not require switching of control modes, and system interconnection operation and independent operation It is useful for making the transition between the two without interruption.

1 Power Converter 2 Distributed Power Source 3 Power System 3a First Voltage Line 3b Neutral Voltage Line 3c Second Voltage Line 4 Inverter 6 Current Measuring Device 7 Voltage Measuring Device 8 Controller 9 Phase Difference Angle Generating Unit 10 Induced Voltage Generating Unit 11 Current command value generator

Claims (7)

A power conversion device connected between a distributed power source and a single-phase three-wire power system having a first voltage line, a second voltage line, and a neutral voltage line,
An inverter having a pair of input terminals connected to the distributed power source and three output terminals connected to each voltage line of the power system;
On the electric power system side of the inverter, a first output current at a first output end connected to the first voltage line and a second output current at a second output end connected to the second voltage line are respectively measured. A current meter,
A voltage meter that measures a first system voltage on the first voltage line with respect to the neutral voltage line of the power system and a second system voltage on the second voltage line with respect to the neutral voltage line, respectively.
A controller that controls switching of the inverter,
The controller is
A first virtual generator is connected between the first voltage line and the neutral voltage line, and a second virtual generator is connected between the second voltage line and the neutral voltage line. It is assumed that the virtual frequency command value of each virtual generator is generated from the current and the voltage measured by the current measuring device and the voltage measuring device, and the phase angle command is generated by integrating the frequency command value. It generates the value, the first to generate a phase angle of each virtual generator from the mains voltage and the second system voltage, the virtual generator each virtual generator from deviation between the phase angle command value and the phase angle of the A phase difference angle generation unit that calculates a virtual phase difference angle in
From the current and voltage measured by the current measuring device and the voltage measuring device, an induced voltage generating unit that calculates a virtual induced voltage of each virtual generator,
From the voltage measured by the voltage measuring device, the phase difference angle, the induced voltage and a predetermined internal impedance of each virtual generator, a current command value generating unit that generates a current command value of each virtual generator, Prepare,
It is configured to switch the inverter so that the current measured by the current measuring device becomes the current command value,
The phase difference angle generator generates the frequency command value that is common between the first virtual generator and the second virtual generator, and/or the first virtual generator and the first virtual generator. Configured to correct an error between the phase angles by adjusting a phase angle of one of the two virtual generators based on a phase angle of the other of the first virtual generator and the second virtual generator. Power converter.   The phase difference angle generation unit calculates the total sum of active power by the first virtual generator and the second virtual generator from the current and voltage measured by the current measuring device and the voltage measuring device, and the effective By generating the frequency command value from the sum of electric power, the active power command value, and the reference frequency, the common frequency command value is generated between the first virtual generator and the second virtual generator. The power converter according to claim 1. The phase difference angle generation unit proportionally calculates a difference between the phase angle of the first virtual generator and the phase angle of the second virtual generator, and outputs the proportional calculation result to the first virtual generator. of by adding to one of the frequencies of the frequency and the second virtual power generator, to correct the error of the phase Kakuma, power converter according to claim 1 or 2.   The induced voltage generator calculates the reactive power of each virtual generator from the current and the voltage measured by the current measuring device and the voltage measuring device, and the reactive power and the magnitude of the first system voltage and The power conversion device according to claim 1, wherein the induced voltage of each virtual generator is calculated from the magnitude of the second system voltage, each reactive power command value, and the reference voltage. The phase difference angle generation unit calculates the difference between the sum of the active powers and the active power command value using the following transfer function K _G (s), and adds the reference frequency to the calculation result, The power conversion device according to claim 2, which generates a frequency command value.
K _G (s)=K _gd /(1+T _g s)
Here, K _gd is a coefficient showing the frequency droop characteristic in each virtual generator, and T _g is a time constant showing the characteristic of the tracking delay of the rotation speed due to inertia in each virtual generator. The induced voltage generation unit multiplies the difference between the reactive power and the reactive power command value by a coefficient K _ad indicating a voltage droop characteristic, adds the reference voltage to the result, and generates a voltage command value. The difference between the value and the magnitude of the corresponding voltage measured by the voltage measuring device is calculated using the following transfer function K _A (s), and the calculation result is output as the induced voltage. The power converter described.
K _A (s)=K _ap +K _ai /s
Here, K _ap is a coefficient indicating a proportional element, and K _ai is a coefficient indicating an integral element.   The controller extracts the positive phase components of the current and the voltage measured by the current measuring device and the voltage measuring device, and handles the extracted positive phase components of the respective values in a rotating coordinate system synchronized with the positive phase. The power conversion device according to claim 1, thereby generating a current command value for each virtual generator.

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