Inverter Device

Abstract

To provide an inverter device capable of stabilizing a frequency of a power system while always outputting maximum power by MPPT control of a solar power generation apparatus or the like.SOLUTION: An inverter device includes: an inverter 600 for converting DC power of a solar light generation apparatus 200 into AC power; a series circuit of a chopper 400 connected between DC terminals of the inverter 600 and a resistor 500; and a control unit 100A for controlling the inverter 600 and the chopper 400, and is constituted so that the inverter 600 is driven by system linkage operation with a power system. The control unit 100A includes: means for operating a power consumption command value by finding out a difference between a DC power command value for performing MPPT control of the solar light generation apparatus 200 and an effective power measurement value of the inverter 600; means for controlling the chopper 400 so that the resistor 500 consumes power corresponding to the power consumption command value; and means for controlling the inverter 600 so that the effective power measurement value follows an effective power command value.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to an inverter device that operates a power generation facility such as a solar power generation facility in connection with a power grid while performing MPPT (maximum power point tracking) control. [Background technology]

[0002] In recent years, a large number of power generation facilities using renewable energy sources such as solar and wind power have been connected to the power grid, resulting in a relative decrease in the proportion of synchronous generators, and a tendency for the frequency stability of the power grid to decline. As is well known, in a synchronous generator, the difference between the input motive power and the generated power is stored in the inertial energy of the rotor, which becomes the angular velocity of the rotor, i.e., the frequency of the output voltage. In other words, the inertia of the rotor of a synchronous generator serves to stabilize the frequency of the power system.

[0003] In contrast, inverter devices for PCS (power conditioning systems), which connect solar power generation equipment to the power grid, are controlled to quickly follow the voltage of the power grid, and do not have the function of independently maintaining the output frequency like a synchronous generator. Therefore, when the proportion of synchronous generators in the power system decreases, the frequency stabilization function of the synchronous generators does not work sufficiently, and fluctuations in the system frequency become large. In view of the above, a conventional technique has been proposed in which the frequency stabilization function of a synchronous generator is realized by controlling a pseudo-synchronous generator in an inverter device.

[0004] 8 and 9 show this type of inverter device and its control circuit disclosed in Patent Document 1, for example. In FIG. 8, reference numeral 10 denotes a three-phase inverter device that performs pseudo-synchronous generator control, 11 denotes a power generation facility such as a solar cell module or a storage battery, 12 denotes an inverter that converts DC power into AC power by the operation of semiconductor switching elements, X denotes a smoothing reactor connected to an interconnection line 21 between the inverter 12 and the power grid 20, C denotes a capacitor similar to the above, and 30 denotes a synchronous generator that supplies AC power to the power grid 20.

[0005] The control circuit 40 that controls the inverter 12 controls the output current I a ,I b ,I c (If necessary, I a,b,c ) and an output voltage V a ,V b ,V c (Also V a,b,c , a generator rotor simulator 43, a sine wave calculator 44, and a PWM calculator 45. inv ,V s are the voltages across the reactor X, and the voltage V s is essentially the voltage V a,b,c is equal to.

[0006] FIG. 9 is a configuration diagram of the generator rotor simulator 43 in the control circuit 40. As shown in FIG. In FIG. 9, the active power measurement unit 43a measures the output current I a,b,c and the output voltage V a,b,c The effective power P is measured from the input and input to the adding and subtracting means 43b. The adding and subtracting means 43b also receives the output target value of the inverter 12, which is regarded as the input (motive force) of the synchronous generator to be simulated, and the output of a damper 43e, which will be described later. The output of the addition / subtraction means 43b is integrated by the first integration means 43c to calculate the normalized angular velocity ω of the rotor of the simulated synchronous generator (if the rated frequency is 50 Hz, then the angular velocity [rad / s] is divided by 50 Hz × 2π). M in the first integration means 43c is a coefficient corresponding to the inertia of the rotor of the synchronous generator. The angular velocity ω is input to a damper 43e that suppresses the vibration component, and is also input to a second integration means 43d where it is integrated, and the output is multiplied by a constant K (=50 [Hz] × 2π) to calculate the voltage phase θ of the internal electromotive force of the simulated synchronous generator.

[0007] Returning to FIG. 8, the sine wave calculation unit 44 calculates a sine wave voltage command V using the voltage phase θ and the frequency and amplitude of the output voltage of the inverter 12. * a,b,c and outputs it to the PWM calculation unit 45. The PWM calculation unit 45 generates a voltage command V * a,b,c The inverter 12 compares the voltage with a carrier to generate a pulse signal, and the semiconductor switching elements of the upper and lower arms of each phase of the inverter 12 are driven by this pulse signal.

[0008] In this conventional technology, the frequency and phase of the output voltage of the inverter 12 are controlled so that when the phase of the output voltage of the inverter 12 leads the phase of the system voltage, the inverter 12 outputs active power to the power grid 20, and when it lags, the inverter 12 absorbs active power from the power grid 20. This acts as a so-called synchronizing force, and the system frequency can be maintained and stabilized at a predetermined value even when the proportion of strong power sources such as synchronous generators connected to the power grid 20 is small.

[0009] In power generation facilities that use renewable energy such as solar or wind power, the amount of power generated is greatly affected by weather conditions such as the amount of solar radiation and wind speed. On the other hand, in the above-mentioned conventional technology, the output of the inverter device 10 is determined based on changes in the system frequency and phase, regardless of the weather, and there are also cases where commands are generated and controlled not only for the power generation mode but also for the charging mode, making it difficult to control the pseudo-synchronous generator as designed.

[0010] Furthermore, for the power generation equipment 11, the DC output voltage is set so that maximum power can always be obtained by MPPT control using, for example, a hill-climbing method. However, in a state where the AC output of the inverter device 10 is suppressed by the pseudo synchronous generator control, it is not possible to appropriately track the DC voltage using the hill-climbing method. For example, as shown in the PV curve of FIG. 10, the DC output P DC Even if the suppression state of is released at time t1, the DC output voltage V DC It is difficult to control quickly.

[0011] Patent Document 2 describes an invention in which, in a distributed power supply system in which a wind power generation facility is connected to a power grid, an output suppression device consisting of a step-down transformer, a PWM rectifier circuit, a PWM inverter, and a resistor is connected to the interconnection point between the wind power generation facility and the power grid, and when the amount of active power injected from the wind power generation facility into the power grid exceeds a predetermined range, the PWM inverter is controlled to cause the resistor to consume the surplus power. Patent Document 3 describes an invention in which a control device for an AC / DC converter that is controlled by a pseudo-synchronous generator to charge and discharge active power and reactive power from a storage battery to a power grid controls the AC / DC converter by adding a frequency fluctuation suppression amount equivalent to the inertia force of the synchronous generator, calculated based on the phase difference between the output voltage of the AC / DC converter and the grid voltage, to an active power target value. Furthermore, Patent Document 4 describes an invention in which, in a distributed power supply system equipped with a solar power generation device that is MPPT controlled, a storage battery is connected to a DC bus between a solar cell power conversion device and a power conversion device for a power grid via a power conversion device for a storage battery, and each power conversion device is controlled based on the target voltage value of the DC bus and the voltage ranges set for each of the three power conversion devices. [Prior art documents] [Patent documents]

[0012] [Patent Document 1] JP 2007-318833 A (

[0024] to

[0033] , Figure 1, etc.) [Patent Document 2] JP 2005-218229 A (

[0008] to

[0014] , Figure 1, etc.) [Patent Document 3] JP 2019-3454 A (

[0015] to

[0017] , Figure 1, etc.) [Patent Document 4] JP 2020-127339 A (

[0032] to

[0035] ,

[0041] to

[0044] , Figures 1 to 4, etc.) Summary of the Invention [Problem to be solved by the invention]

[0013] As described above, in the conventional technology disclosed in Patent Document 1, even if the suppression state of the AC output of the inverter device is released, it takes a long time for the output of the power generation equipment to return to the maximum power point, which reduces the effectiveness of MPPT control. In addition, in Patent Document 2, AC power controlled to a predetermined value by AC / AC conversion using a PWM rectifier circuit and a PWM inverter is supplied to a resistor for consumption, which complicates the configuration of the output suppression device and the calculation processing of the control circuit. Furthermore, although Patent Document 3 omits illustrations of photovoltaic power generation devices and the like (

[0013] ), it does not particularly assume MPPT control of these. In the prior art disclosed in Patent Document 4, voltage ranges must be set using appropriate upper and lower limit values ​​for each of the three power conversion devices, which poses problems such as the need for a large storage capacity.

[0014] Therefore, an object of the present invention is to provide an inverter device that can stabilize the frequency of the power system while always outputting maximum power from power generation equipment such as a solar power generation equipment through MPPT control of the power generation equipment. [Means for solving the problem]

[0015] In order to solve the above problems, No. 1The present invention provides an inverter device that includes an inverter that converts DC power output from a power generation facility into AC power, a series circuit of a chopper and a resistor connected between a pair of DC terminals of the inverter, and a control unit that controls the inverter and the chopper, the inverter being connected to an electric power grid and operated, The control unit a means for calculating a power consumption command value by determining a difference between a DC power command value for maximum power point control of the power generation facility and a measured active power value of the inverter; a means for controlling the chopper so that the resistor consumes power according to the power consumption command value; a means for controlling the inverter so that the measured active power value follows an active power command value; The present invention is characterized by the following.

[0016] No. 2 The invention The first invention In the inverter device, The power supply is characterized by comprising a means for reducing the output frequency of the inverter when the measured active power value is greater than the DC power command value.

[0017] Third The present invention provides an inverter device that includes an inverter that converts DC power output from a power generation facility into AC power, a series circuit of a DC / DC converter and a storage battery connected between a pair of DC terminals of the inverter, and a control unit that controls the inverter and the DC / DC converter, the inverter being operated in a manner that is interconnected with a power grid, The control unit a means for calculating a charge / discharge power command value by determining a difference between a DC power command value for maximum power point control of the power generation facility and a measured active power value of the inverter; a means for controlling the DC / DC converter so as to charge and discharge the storage battery in accordance with the charge / discharge power command value; a means for controlling the inverter so that the measured active power value follows an active power command value; The present invention is characterized by the following.

[0018] Fourth The present invention provides an inverter device that includes an inverter that converts DC power output from a power generation facility into AC power, a series circuit of a chopper and a resistor connected between a pair of DC terminals of the inverter, and a control unit that controls the inverter and the chopper, the inverter being connected to an electric power grid and operated, The control unit a means for calculating a power consumption command value by determining a difference between a DC power command value for maximum power point control of the power generation facility and an active power command value of the inverter; a means for controlling the chopper so that the resistor consumes power according to the power consumption command value; means for controlling the inverter in accordance with the active power command value; The present invention is characterized by the following.

[0019] No. 5 The invention The fourth invention In the inverter device, The upper limit of the active power command value is limited by the DC power command value.

[0020] No. 6 The present invention provides an inverter device that includes an inverter that converts DC power output from a power generation facility into AC power, a series circuit of a DC / DC converter and a storage battery connected between a pair of DC terminals of the inverter, and a control unit that controls the inverter and the DC / DC converter, the inverter being operated in a manner that is interconnected with a power grid, The control unit a means for calculating a charge / discharge power command value by determining a difference between a DC power command value for maximum power point control of the power generation facility and an active power command value of the inverter; a means for controlling the DC / DC converter so as to charge and discharge the storage battery in accordance with the charge / discharge power command value; means for controlling the inverter in accordance with the active power command value; The present invention is characterized by the following.

[0021] Seventh The invention Any one of the first to sixth inventions In the inverter device, The control unit controls the inverter as a pseudo-synchronous generator, thereby making it possible to simulate a frequency stabilization function due to the inertia of a rotor of a synchronous generator connected to the power grid.

[0022] No. 8 The invention Any one of the first to seventh inventions In the inverter device, The power generation facility is characterized in that it is composed of a solar power generation device or a wind power generation device and a converter that converts the AC output of the device into DC power. [Effects of the Invention]

[0023] According to the present invention, it is possible to constantly maximize the output of a power generation facility such as a solar power generation system, synchronize the output frequency of an inverter device with the power system, and stabilize the frequency of the power system. [Brief explanation of the drawings]

[0024] [Figure 1] 1 is a connection configuration diagram of an inverter device according to a first embodiment of the present invention. [Figure 2] FIG. 2 is a block diagram showing a first embodiment of a control unit 100A in FIG. [Figure 3] FIG. 3 is a block diagram of the power consumption adjusting means in FIG. 2(a). [Figure 4] FIG. 6 is a connection configuration diagram of an inverter device according to a second embodiment of the present invention. [Figure 5] FIG. 5 is a block diagram showing a first embodiment of a control unit 100B in FIG. 4. [Figure 6] FIG. 2 is a block diagram showing a second embodiment of the control unit 100A in FIG. [Figure 7] FIG. 5 is a block diagram showing a second embodiment of the control unit 100B in FIG. 4. [Figure 8] FIG. 1 is a configuration diagram of an inverter device and its control circuit according to a conventional technique. [Figure 9] FIG. 9 is a configuration diagram of a generator rotor simulator in FIG. 8. [Figure 10] FIG. 1 is an explanatory diagram of a PV curve in the hill-climbing method. DETAILED DESCRIPTION OF THE INVENTION

[0025] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Fig. 1 is a connection configuration diagram of an inverter device according to a first embodiment of the present invention. In Fig. 1, a positive bus 200P and a negative bus 200N are connected to the DC output side of a solar power generation device 200 as a power generation facility, and a smoothing capacitor 300 is connected between the buses 200P and 200N. In addition, a series circuit of a chopper 400 and a resistor 500 is connected to both ends of the capacitor 300, and both ends of this series circuit are connected to a pair of DC terminals of an inverter 600, and the AC terminals of the inverter 600 are connected to the power grid 20 via an interconnection line 21.

[0026] The power generation facility is not limited to the solar power generation facility 200, but may be a facility that combines an AC generator of a wind power generation facility with a converter that converts the output of the generator into DC power, or a storage battery.

[0027] The control unit 100A turns on and off the semiconductor switching elements that respectively constitute the chopper 400 and the inverter 600 to perform the following control operations. First, the inverter 600 is made to perform DC / AC conversion so as to output an AC voltage of a predetermined amplitude and frequency in synchronization with the frequency of the power grid 20 by pseudo-synchronous generator control, while maintaining the DC output voltage at a predetermined value in order to MPPT control the solar power generation device 200. Furthermore, when the AC output of the inverter 600 (required output from the power grid 20) is suppressed and a difference occurs between the DC output of the solar power generation device 200 and the DC input required by the inverter 600, the chopper 400 is controlled (turned on) so that the differential power is consumed by the resistor 500.

[0028] Next, FIG. 2 is a block diagram showing a first embodiment of the control unit 100A in FIG. 1, and shows functions realized by the hardware of a processing unit such as a microcomputer and the software installed therein. 2(a), an active power measuring means 101 measures active power based on the output voltage and output current of an inverter 600. This active power measurement value P is input to an adding / subtracting means 102 to calculate an active power command value P * The difference between these is calculated, and this difference is input to the frequency droop control means 103. The frequency droop control means 103 controls the frequency f according to the difference by an integral operation. d and generate this frequency f d and the reference frequency f0 (50 Hz or 60 Hz) of the power grid 20 are added by the addition / subtraction means 104 to calculate the frequency f. The frequency f becomes a frequency command value f' for the inverter 600 via the addition / subtraction means 105, and a sinusoidal output voltage command value for the inverter 600 is generated based on the output voltage phase determined by integrating this frequency command value f'.

[0029] The inverter control system (pseudo synchronous generator control system) including the above-mentioned active power measurement means 101, frequency droop control means 103, etc., is for controlling the inverter 600 as a grid forming (GFM) inverter, and this inverter control system controls the frequency and phase of the output voltage of the inverter 600 by transferring active power between the inverter 600 and the power grid 20, thereby exerting a synchronizing force on the grid voltage. Such an operation of the inverter control system is similar to that in FIG. 5, which will be described later.

[0030] On the other hand, the MPPT control means 106 in FIG. 2(a) outputs a DC voltage command value V DC * is output, and the DC voltage adjustment means (DC-AVR) 107 outputs the DC voltage command value V DC * DC power command value P according toDC * is generated. DC power command value P DC * is input to the addition / subtraction means 108 to calculate the difference with the active power measurement value P, and this difference is used as the power consumption command value P LOSS * is input to one input side of the adding / subtracting means 115. Also, the power consumption command value P LOSS * is given to the other input side of the adding / subtracting means 115 via a limiter 109 whose lower limit value is "0", and is also input to a power consumption adjusting means (LOSS-APR) 110 to generate a drive signal for the semiconductor switching element of the chopper 400. Furthermore, the output of the adding / subtracting means 115 is input to the adding / subtracting means 105 as a value Δf equivalent to the frequency correction amount. 2(b), gain multiplication means 116 may be provided between the addition / subtraction means 115 and the addition / subtraction means 105, and the output of the addition / subtraction means 115 may be multiplied by an appropriate gain G to calculate the frequency correction amount equivalent value Δf. Alternatively, as shown in FIG. 2(c), PI (proportional-integral) adjustment means 117 may be provided, and the proportional gain and integral gain thereof may be set to appropriate values ​​to calculate the frequency correction amount equivalent value Δf. Incidentally, FIG. 2(a) corresponds to the case where the gain G in FIG. 2(b) is set to 1, or the case where the proportional gain of the PI adjustment means 117 in FIG. 2(c) is set to 1 and the integral gain is set to 0.

[0031] Next, the configuration of the power consumption adjusting means 110 in FIG. 2 will be described with reference to FIG. As shown in FIG. 3, the power consumption adjusting means 110 adjusts the power consumption command value P LOSS * and the resistance value R of the resistor 500 in FIG. 1 (P LOSS * ×R) is input to square calculation means 111, and its output is √(P LOSS * ×R)=V DCR * and the DC voltage V of the inverter 600 DCand a PWM calculation means 113 that generates a drive signal for the semiconductor switching element of the chopper 400 based on the output of the division means 112.

[0032] Here, the power consumption by resistor 500 is P LOSS * In order to make it equal to V DCR * When I said, V DCR * ×(V DCR * / R)=P LOSS * , i.e., (V DCR * ) 2 =P LOSS * ×R Therefore, the square calculation means 111 calculates √(P LOSS * ×R) to V DCR * and set it equal to this V DCR * and V DC The chopper 400 can be controlled to be turned on and off based on the ratio of

[0033] Returning to FIG. 2, the DC power command value P DC * is greater than the measured active power value P, the power consumption command value P LOSS * Voltage command value V according to DCR * By controlling the chopper 400 based on LOSS * A power equivalent to is dissipated by resistor 500. Therefore, the output of the inverter 600 is suppressed by the pseudo synchronous generator control, and the DC power command value P DC *becomes larger than the active power measurement value P, the operation can be continued without impairing the MPPT control of the solar power generation device 200. In other words, since the MPPT control is possible even in the output suppression state of the inverter 600 as shown in Fig. 10, there is no inconvenience such as taking a long time to return to the maximum power point after the output suppression state is released.

[0034] According to FIG. 2, the power consumption command value P LOSS * If is positive, the frequency correction amount equivalent value Δf becomes zero, and therefore the frequency command value f′ for the inverter 600 becomes f′=f. In addition, the active power measurement value P is the DC power command value P DC * If the input voltage Vp becomes larger than the limiter 109, the output of the adding / subtracting means 108 becomes negative, and one input of the adding / subtracting means 115 becomes negative. LOSS * ) is limited to "0", the output of the adding / subtracting means 115 (frequency correction amount equivalent value Δf) becomes negative, and therefore control is performed to decrease the frequency command value f' of the inverter 600.

[0035] Next, FIG. 4 is a connection configuration diagram of an inverter device according to a second embodiment of the present invention. In FIG. 4, the same parts as those in FIG. 1 are denoted by the same reference numerals and the description thereof will be omitted, and the following description will focus on the different parts. 4, a series circuit of a DC / DC converter 700 and a storage battery 800 is connected across the capacitor 300 instead of the series circuit of the chopper 400 and the resistor 500 in FIG.

[0036] The control unit 100B in FIG. 4 performs MPPT control on the solar power generation device 200 in the same manner as the control unit 100A, and also performs DC / AC conversion on the inverter 600 by pseudo-synchronous generator control so as to output an AC voltage of a predetermined amplitude and frequency in synchronization with the frequency of the power grid 20. Furthermore, for example, when the AC output of the inverter 600 is suppressed and a difference occurs between the DC output of the photovoltaic power generation device 200 and the DC input required by the inverter 600, the DC / DC converter 700 performs DC / DC conversion of the difference power and supplies it to the storage battery 800 to charge the storage battery 800. Furthermore, when the DC output of the photovoltaic power generation device 200 is insufficient for the DC input corresponding to the AC output of the inverter 600, the DC / DC converter 700 is controlled so that the shortage of power is supplied to the DC side of the inverter 600 by discharging the storage battery 800.

[0037] As described above, according to the second embodiment, the AC output of the inverter 600 is suppressed, and the DC power command value P DC * becomes larger than the active power measurement value P, the MPPT control of the solar power generation device 200 can be continued by the charging operation of the storage battery 800 by the DC / DC converter 700, and there is no inconvenience such as a long time required to return to the maximum power point when the output suppression state of the inverter 600 is released.

[0038] FIG. 5 is a block diagram showing a first embodiment of the control unit 100B in FIG. 4, and similarly to the above, shows functions realized by the hardware of a processing unit such as a microcomputer and the software installed therein. 5, the configuration and operation of the inverter control system are substantially the same as those in FIG. 2, and pseudo synchronous generator control is realized by active power measurement means 101, frequency droop control means 103, and addition / subtraction means 102 and 104.

[0039] The converter control system that controls the DC / DC converter 700 also calculates the DC power command value P DC * The difference between the measured active power value P and the charge / discharge power command value P BAT * The charge / discharge power command value P BAT *By controlling the on / off of the semiconductor switching elements of the DC / DC converter 700 in accordance with the above, the storage battery 800 is charged or discharged, and the DC voltage of the inverter 600 is maintained at a predetermined value.

[0040] Next, FIG. 6 is a block diagram showing a second embodiment of the control unit 100A in FIG. In FIG. 6, in addition to the chopper control system consisting of the MPPT control means 106, DC voltage adjustment means 107, addition / subtraction means 108, limiter 109, and power consumption adjustment means 110 similar to those in FIG. 2, an inverter control system is provided that controls the current of the inverter 600 so that a current flows according to the differential voltage between the output voltage of the inverter 600 and the system voltage.

[0041] The inverter control system described above uses an active power command value P * and an active power command generating means 130 for generating the active power command value P * The upper limit value of the DC power command value P DC * and the active power command value after the limit is P AC * and an AC-APR 132 that receives the active power command value P AC * , in other words, the active current command value I AC * An output voltage command value is calculated so that a given current flows through the inverter 600, and a drive signal for the inverter 600 is generated based on this output voltage command value.

[0042] The inverter control system, which includes the above-mentioned active power command generating means 130, AC power adjusting means 132, etc., is for controlling the inverter 600 as a grid following (GFL) inverter, and by exchanging active power between the inverter 600 and the power grid 20, the frequency and phase of the output voltage of the inverter 600 are controlled, and a synchronizing force with respect to the grid voltage is exerted. Such an operation of the inverter control system is similar to that in FIG. 7, which will be described later.

[0043] In this embodiment, the DC power command value P DC * is the active power command value P * If it is larger than the power consumption command value P LOSS * DC voltage command value V according to DCR * By controlling the chopper 400 based on LOSS * A power equivalent to is dissipated by resistor 500. Therefore, even if the output of the inverter 600 is limited by pseudo synchronous generator control, for example, the operation of the solar power generation device 200 can be continued without impairing the MPPT control.

[0044] Next, FIG. 7 is a block diagram showing a second embodiment of the control unit 100B in FIG. 7, in addition to the converter control system consisting of the MPPT control means 106, DC voltage adjustment means 107, addition / subtraction means 108, and charge / discharge power adjustment means 120 as in FIG. 5, an inverter control system is provided which controls the inverter 600 so that a current corresponding to the difference voltage between the output voltage of the inverter 600 and the system voltage flows as in FIG. 6, and this inverter control system includes an active power command generation means 130 and its output P * is the active power command value P AC * and AC power adjustment means 132 that generates drive signals for the semiconductor switching elements of the inverter 600 as a power supply.

[0045] The operation of the converter control system in FIG. 7 is the same as that in FIG. The operation of the inverter control system is almost the same as in Fig. 6, but in Fig. 7, the active power command value P AC * When the DC input power of the inverter 600 increases, the DC power command value P DC* Therefore, the active power command value P AC * The upper limit of the DC power command value P DC * Therefore, in the inverter control system in Fig. 7, the limiter 131 shown in Fig. 6 is removed.

[0046] In this embodiment, the DC power command value P DC * is the active power command value P of the inverter 600 * If it is larger than the reference value P , the charge / discharge power adjusting means 120 adjusts the charge / discharge power command value P BAT * The semiconductor switching elements of the DC / DC converter 700 are controlled to be on and off in accordance with the above, thereby charging the storage battery 800. Therefore, even if the AC output of the inverter 600 is limited by the pseudo synchronous generator control, there is no risk that the MPPT control of the solar power generation device 200 will be impaired.

[0047] It goes without saying that the present invention is not limited to cases where the inverter 600 is controlled as a pseudo-synchronous generator, but can also be applied to cases where the AC output of the inverter 600 is limited due to a decrease in the load on the power system. [Explanation of symbols]

[0048] 20: Power system 21: Interconnection line 100A, 100B: Control section 101: Active power measurement means 102,104,105,108,115: Addition and subtraction means 103: Frequency droop control means 106: MPPT control means 107: DC voltage regulator (DC-AVR) 110: Power consumption adjustment means (LOSS-APR) 111: Square operation means 112:Division means 113:PWM calculation means 116: Gain multiplication means 117:PI adjustment means 120: Charge / discharge power adjustment means (BAT-APR) 130: Active power command generating means 132: AC power adjustment means (AC-APR) 200: Solar power generation equipment 200P: Positive side bus bar 200N: Negative bus bar 300: Capacitor 400: Chopper 500:Resistor 600: Inverter 700: DC / DC converter 800: Storage battery

Claims

1. An inverter device including: an inverter that converts DC power output from a power generation facility into AC power; a series circuit of a chopper and a resistor connected between a pair of DC terminals of the inverter; and a control unit that controls the inverter and the chopper, wherein the inverter is operated in a state connected to an electric power grid, The control unit a means for calculating a power consumption command value by determining a difference between a DC power command value for maximum power point control of the power generation facility and a measured active power value of the inverter; a means for controlling the chopper so that the resistor consumes power according to the power consumption command value; a means for controlling the frequency and phase of the output voltage of the inverter so that the measured active power value follows an active power command value; Equipped with By controlling the inverter as a pseudo synchronous generator, it is possible to simulate a frequency stabilization function due to the inertia of a rotor of a synchronous generator connected to the power grid. Inverter device.

2. 2. The inverter device according to claim 1, 10. An inverter device comprising: means for reducing an output frequency of the inverter when the measured active power value is greater than the DC power command value.

3. An inverter device comprising: an inverter that converts DC power output from a power generation facility into AC power; a series circuit of a DC / DC converter and a storage battery connected between a pair of DC terminals of the inverter; and a control unit that controls the inverter and the DC / DC converter, wherein the inverter is operated in a state connected to an electric power grid, The control unit a means for calculating a charge / discharge power command value by determining a difference between a DC power command value for maximum power point control of the power generation facility and a measured active power value of the inverter; a means for controlling the DC / DC converter so as to charge and discharge the storage battery in accordance with the charge / discharge power command value; a means for controlling the frequency and phase of the output voltage of the inverter so that the measured active power value follows an active power command value; Equipped with By controlling the inverter as a pseudo synchronous generator, it is possible to simulate a frequency stabilization function due to the inertia of a rotor of a synchronous generator connected to the power grid. Inverter device.

4. An inverter device including: an inverter that converts DC power output from a power generation facility into AC power; a series circuit of a chopper and a resistor connected between a pair of DC terminals of the inverter; and a control unit that controls the inverter and the chopper, wherein the inverter is operated in a state connected to an electric power grid, The control unit a means for calculating a power consumption command value by determining a difference between a DC power command value for maximum power point control of the power generation facility and an active power command value of the inverter; a means for controlling the chopper so that the resistor consumes power according to the power consumption command value; a means for controlling the frequency and phase of the output voltage of the inverter in accordance with the active power command value; Equipped with By controlling the inverter as a pseudo synchronous generator, it is possible to simulate a frequency stabilization function due to the inertia of a rotor of a synchronous generator connected to the power grid. Inverter device.

5. 5. The inverter device according to claim 4, An inverter device characterized in that an upper limit value of the active power command value is limited by the DC power command value.

6. An inverter device comprising: an inverter that converts DC power output from a power generation facility into AC power; a series circuit of a DC / DC converter and a storage battery connected between a pair of DC terminals of the inverter; and a control unit that controls the inverter and the DC / DC converter, wherein the inverter is operated in a state connected to an electric power grid, The control unit a means for calculating a charge / discharge power command value by determining a difference between a DC power command value for maximum power point control of the power generation facility and an active power command value of the inverter; a means for controlling the DC / DC converter so as to charge and discharge the storage battery in accordance with the charge / discharge power command value; a means for controlling the frequency and phase of the output voltage of the inverter in accordance with the active power command value; Equipped with By controlling the inverter as a pseudo synchronous generator, it is possible to simulate a frequency stabilization function due to the inertia of a rotor of a synchronous generator connected to the power grid. Inverter device.

7. The inverter device according to any one of claims 1 to 6, An inverter device, wherein the power generation facility is configured by a solar power generation device or a wind power generation device and a converter for converting the AC output of the solar power generation device into DC power.

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