JP2016185018A - System voltage suppression controller and system voltage suppression control method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a system voltage suppression controller of a power conditioner capable of enhancing stabilization of the commercial system voltage of the nearest distribution line, while using natural energy effectively for power generation.SOLUTION: A system voltage suppression controller includes a reverse power flow current estimation unit for estimating a reverse power flow current by subtracting the capacitor current of an LC filter, determined by a predetermined mathematical formula from the output current of an inverter interconnected with a commercial system, a first PLL processing unit for determining the phase angle of the commercial system voltage, a second PLL processing unit for outputting the phase angle from the estimated reverse power flow current, and a feedback signal generation unit for generating a power factor feedback signal and a reactive current feedback signal based on the phase difference Δφ(θ-θ). When the commercial system voltage drops, a suppression variation for suppressing the drop is obtained, ad when the voltage rises, a suppression variation for suppressing the rise is obtained. The system voltage suppression controller also includes a power factor control unit for controlling the power factor command value and output suppression command value based on the suppression variation, an output limit unit and a reactive current control unit for outputting a reactive current target value based on the reactive current feedback signal.SELECTED DRAWING: Figure 5

Description

  The present invention relates to a system voltage suppression control device and system voltage of a power conditioner including an inverter that converts DC generated power into AC power and is linked to a commercial system, and an LC filter that removes harmonic components from the output of the inverter. The present invention relates to a suppression control method.

  The distributed power source that constitutes the photovoltaic system is equipped with a power conditioner that converts it into AC power with a frequency and voltage suitable for the grid frequency and grid voltage of the grid to be used in conjunction with a commercial grid. Yes.

  The power conditioner includes a DC / DC converter that adjusts a DC voltage generated by a distributed power source to a predetermined DC voltage value, an inverter that converts DC power output from the DC / DC converter into AC power, An LC filter that removes high-frequency components from the output is provided.

  Management for maintaining the voltage of the distribution line within a predetermined allowable range has become difficult due to the introduction and expansion of the photovoltaic power generation system. Generally, electric power companies introduce tap control equipment (SVR), STATCOM, and the like to manage the distribution lines so that they are maintained at an appropriate voltage.

  However, in recent years, in order to adjust the voltage of the nearest distribution line from the power conditioner side, it has a function to adjust the operating power factor of the power conditioner to be constant during grid connection operation or to suppress an increase in commercial system voltage It came to be required.

  Japanese Patent Application Laid-Open No. 2004-133830 describes a change amount of a first reactive power that is a fast reactive power or a slow reactive power that should be output by a power conditioner according to a deviation of a commercial grid frequency, and a rise in the commercial grid voltage. In addition, there has been proposed a control device that controls the output of the power conditioner based on at least one of the amount of change in the second reactive power that the power conditioner should output.

  When the control device changes the phase reactive power output from the power conditioner based on the amount of change in the second reactive power, the voltage corresponding to the output voltage of the power conditioner exceeds the upper limit voltage. If it becomes, it will be comprised so that the output of a power conditioner may be controlled so that the active power which a power conditioner outputs may be reduced.

  Patent Document 2 relates to a distributed power supply interconnection system having a configuration in which a plurality of distributed power supply facilities each having a distributed power supply and a load are connected to a power distribution system, and has conventionally been provided for suppressing a voltage drop in the power distribution system A distributed power supply interconnection system that aims to reduce the power consumption is disclosed.

  The distributed power interconnection system has two sets of injection frequencies each consisting of two injection frequencies that cause a beat, in which a plurality of distributed power supply facilities are classified into two groups, a first group and a second group. Thus, the frequency difference between the two injection frequencies constituting each set is the same in both sets, and the four injection frequencies constituting both sets are different from each other and are different from the fundamental frequency of the distribution system. Using the second set of injection frequencies, each distributed power supply facility belonging to the first group includes a current injection device for injecting an injection current including a current set of the first set of injection frequencies into the power distribution system, An injection frequency voltage measuring device for measuring a voltage at an interconnection point between the facility and the power distribution system and measuring at least one injection frequency of the second set of injection frequencies; Genus Each of the distributed power source holding facilities is a voltage at a connection point between the current injection device that injects an injection current including the current set of the second set of injection frequencies into the distribution system, and the own facility and the distribution system. An injection frequency voltage measuring device for measuring a voltage of at least one injection frequency of the first set of injection frequencies, and each of the distributed power source holding facilities of both groups is a group to which the own equipment belongs. Is called the other group, and the group to which the own equipment does not belong is called the other group, and the injected current causes the phase of each current of the current set constituting the injected current injected by the current injection device of the own equipment to be generated. A total phase of the injected current injected by the current injection device of the distributed power source possessing equipment belonging to another group while maintaining the same phase relation common within the same group with respect to the phase of the own equipment beat that is The voltage generated by It becomes provided with respective synchronization control unit for synchronizing with other groups beat.

  And each distributed power supply facility of both groups is equipped with a power consumption measuring device for measuring the power consumption received from the distribution system of its own equipment, and the current injection of each distributed power supply facility of both groups The apparatus injects the injection current having a magnitude corresponding to the power consumption measured by the power consumption measuring device of the own equipment, respectively, and each of the distributed power supply possession equipments of both groups A slow-phase reactive power control circuit that controls a distributed power source of equipment and outputs delayed-phase reactive power having a magnitude corresponding to the injected frequency voltage measured by the injected frequency voltage measuring device of the equipment from the distributed power source of the equipment. Each is equipped.

Japanese Patent Application Laid-Open No. 2014-207811 JP 2011-36067 A

  However, according to the control device disclosed in Patent Document 1, the amount of increase / decrease in reactive power is constant in the steady state in which the commercial grid voltage is maintained in a range defined by the Electric Utility Law, for example, 101V ± 6V. Therefore, it is difficult to suppress fluctuations in active power and reactive power in the vicinity of the set value of the commercial system voltage.

  In addition, the distributed power interconnection system disclosed in Patent Document 2 is provided with a power consumption measuring device in its own equipment to monitor the load power consumption and the voltage of the distribution line, and increase the load power consumption and at the same time the commercial system of the distribution line. Since it is configured to supply late phase reactive power to suppress the voltage drop, many current sensors are required to constantly monitor the load power consumption, which increases the cost and complexity of the control program. There was a problem of becoming.

  In view of the above-described problems, an object of the present invention is to provide a system voltage suppression control device and system for a power conditioner that can stably adjust the commercial system voltage of the latest distribution line while effectively using natural energy for power generation. This is in providing a voltage suppression control method.

In order to achieve the above-mentioned object, the first characteristic configuration of the system voltage suppression control device according to the present invention is a commercial product obtained by converting DC generated power into AC power as described in claim 1 of the claims. A system voltage suppression control device for a power conditioner including an inverter connected to a system, wherein a first threshold voltage and a second threshold voltage higher than the first threshold voltage are set in advance to an effective value E _uw of a commercial system voltage. In the hysteresis region between the first threshold voltage and the second threshold voltage, when the effective value E _uw of the commercial grid voltage is equal to or lower than the first threshold voltage, the commercial grid voltage is supplied only by supplying the slow phase power. controlling said inverter in suppressing system voltage drop suppression mode to decrease, when the effective value E _uw commercial system voltage is above the second threshold voltage, the quotient by the supply and / or reduction of active power of leading phase power In that it is configured to control the inverter to increase of the system voltage suppressing system voltage rise suppression mode.

  Even in the steady state where the commercial grid voltage is maintained in the range defined by the Electricity Business Law, for example, 101V ± 6V, the drop in grid voltage is suppressed by supplying slow-phase power when the voltage drops below the first threshold voltage. If the voltage rises above the second threshold voltage, phase-advancing power is supplied, and if necessary, the active power is reduced to suppress the increase in the commercial system voltage. In addition, the hysteresis area is provided to suppress the system voltage increase. Thus, the commercial system voltage can be stabilized by preventing the reduction suppression from being repeated.

As described in claim 2, the second characteristic configuration includes, in addition to the first characteristic configuration described above, an inverter connected to a commercial system by converting DC generated power into AC power, and A system voltage suppression control device for a power conditioner having an LC filter that removes harmonic components from the output, as a commercial system voltage e _uw , an LC filter capacitor current i _c , a capacitor capacitance C _f , and an internal resistance R _c From the measured value of the inverter output current i _inv

The reverse flow current estimator that estimates the reverse flow current i _sp that is output from the power conditioner to the commercial power supply by subtracting the capacitor current _ic obtained in step ( _b) , and the commercial grid voltage e from the measured value of the commercial grid voltage e _uw a first PLL unit for outputting the phase angle theta _uw of _uw, second PLL which outputs a phase angle theta _sp of backward flow current _{i sp} from reverse flow current _{i sp} estimated by the backward flow current estimating unit The phase difference Δφ (θ _uw −θ _sp ) between the commercial system voltage e _uw and the reverse flow current i _sp obtained from the phase angle output from the processing unit and the first PLL processing unit and the second PLL processing unit. based on the power factor feedback signal and a feedback signal generator for generating a reactive current feedback signal, the effective value E _uw commercial system voltage suppressing deterioration suppressing a decrease in the commercial system voltage when: the first threshold voltage A decrease suppression control unit for determining the reduction amount, an increase suppression control unit and the effective value E _uw is seeking inhibiting elevation variation suppressing an increase in the commercial system voltage when the above high second threshold voltage than the first threshold voltage And a power factor that generates a target power factor so that the power factor of reverse power flow converges to a power factor command value set by the driving power factor setting unit based on the power factor feedback signal. A power factor control unit that generates a target power factor so that a power factor of reverse power flow converges to a power factor command value set by the power factor setting unit based on the power factor feedback signal; And a reactive current control unit that outputs a reactive current target value to an inverter control unit that controls the inverter based on the target power factor generated by the power factor control unit and the reactive current feedback signal. .

If the commercial system voltage e _uw is measured without using a separate sensor for detecting the reverse flow current in addition to the output current i _{inv of the} inverter necessary for controlling the inverter, , the capacitance of the capacitor _{C f,} accurate capacitor current _{i c} in consideration of the internal resistance _{R c} can be estimated. The commercial system obtained from the first PLL processing unit based on the phase angle θ _sp of the reverse flow current i _sp obtained from the second PLL processing unit based on the capacitor current _ic and the commercial system voltage e _uw and a phase angle theta _uw voltage _{e uw,} a phase difference Δφ of the commercial system voltage _{e uw} and reverse flow current _{i sp} (θ _{uw -θ sp)} is obtained, the power factor feedback signal from the phase difference Δφ by the feedback signal generation unit And a reactive current feedback signal is generated.

In the operating power factor setting unit, the decrease suppression control unit suppresses the decrease in the commercial system voltage when the effective value E _uw of the commercial system voltage is equal to or lower than the first threshold voltage, that is, increases the slow phase reactive current. The power factor command value is corrected based on the decrease suppression change amount so that the rise of the commercial system voltage is suppressed when the effective value E _uw is equal to or higher than the second threshold voltage higher than the first threshold voltage. The power factor command value is corrected based on the rise suppression change amount so as to increase, and the power factor control unit calculates the target power factor from each power factor command value and the power factor feedback signal, and the target power factor and reactive current feedback are calculated. A reactive current target value is generated by the reactive current control unit based on the signal, and a desired reverse flow current _isp is appropriately output from the inverter. As a result, the fluctuation of the commercial system voltage of the latest distribution line to which the power conditioner is connected is suppressed.

In the third feature configuration, as described in claim 3, in addition to the second feature configuration described above, the decrease suppression control unit is configured to set a power factor lower limit value PF _min to a preset value. The current power factor command value PF ^* is corrected by a decrease suppression change amount Δy calculated based on a deviation of the commercial system voltage with respect to the lower limit allowable voltage E ^* _min of the commercial system voltage, and the increase suppression control unit The current power factor command value PF ^* is corrected by the increase suppression change amount Δy calculated based on the deviation of the commercial system voltage from the upper limit allowable voltage E ^* _max up to a preset power factor lower limit value PF _min. It is in the point comprised as follows.

When the effective value E _uw of the commercial system voltage is equal to or lower than the first threshold voltage, the reduction based on the deviation between the lower limit allowable voltage E ^* _min of the commercial system voltage and the measured effective value of the commercial system voltage by the reduction suppression control unit When the suppression change amount Δy is calculated and the power factor command value PF ^* is set according to the decrease suppression change amount Δy, and the effective value E _uw of the commercial system voltage is equal to or higher than the second threshold voltage, the second power factor command value is set. The increase suppression change amount Δy based on the deviation of the commercial system voltage with respect to the upper limit E ^* _max of the commercial system voltage is calculated by the unit, and the power factor command value PF ^* is set according to the increase suppression change amount Δy. In any case, the power factor command value PF ^* does not fall below a preset power factor lower limit value PF _min .

In the fourth feature configuration, as described in claim 4, in addition to the third feature configuration described above, the power factor command value PF ^* set by the increase suppression control unit is a power factor lower limit value PF _min. The output limiting unit is provided that limits the reactive current target value output by the reactive current control unit.

When the power factor command value PF ^* for suppressing the increase of the commercial system voltage is corrected based on the increase suppression change amount, and the power factor command value PF ^* reaches the power factor lower limit value PF _min, it is invalidated by the output limiting unit. By limiting the current target value, an increase in the system voltage is suppressed. When the reactive current is variably controlled by the reactive current control unit and the apparent power increases, the burden on the circuit elements constituting the power conditioner increases. Therefore, it is necessary to select an expensive circuit element that can withstand that. In order to deal with this problem, if the active power is adjusted so as to decrease, the stability of the operating power factor is impaired, and eventually the stability of the commercial system voltage is impaired. Even in such a case, since the reactive current target value output by the reactive current control unit is limited by providing the output limiting unit, the driving power factor can be stably controlled while suppressing the apparent power to the rated value. It becomes like this.

In the fifth feature configuration, in addition to any one of the second to fourth feature configurations described above, the power factor control unit includes a power factor command value PF ^* and a power factor. A PI control unit that generates a correction value based on the deviation of the feedback signal, and a reactive power from the power factor target value PF ^* _real obtained by adding the power factor command value PF ^* to the correction value generated by the PI control unit Coefficient to find

And a coefficient generation unit for adding a sign indicating a phase advance or delay to the coefficient according to the power factor command value PF ^* .

Correction value as the power factor feedback signal from the deviation of the power factor feedback signal output from the feedback signal generator unit with a preset power factor command value PF ^* by the PI control unit is converged to the power factor command value PF ^* is A power factor target value PF ^* _real obtained by adding the power factor command value PF ^* to the correction value is obtained. The coefficient generation unit calculates a coefficient represented by [Equation 2] that is a ratio of reactive power to active power, and adds a code according to the power factor command value. Specifically, the sign “+1” is added when the power factor command value PF ^* indicates a slow reactive current, and the sign “−1” is added when it indicates a fast reactive current.

The sixth feature configuration is the update time of the reactive current target value output by the reactive current control unit in addition to any of the second to fifth feature configurations described above, as described in claim 6. Is set at a time when the absolute value of the reverse flow current i _sp shows the maximum value or at a time _{close to} it every half cycle of the commercial system frequency, and the reactive component of the measured reverse flow current i _sp is the reverse flow current i _sp. It is in the point which is comprised so that it may change at the time of the vicinity of the maximum value of absolute value.

The amplitude of the reverse flow current fluctuates by drawing a sine curve based on the commercial grid frequency, but the reactive current target value is updated at the time when the sine curve zero-cross point, that is, when the absolute value of the reverse flow current _isp is the minimum value. Then, the command value i of the output current becomes a timing when the influence of the invalid component of the command value i ^* _inv of the output current (a value calculated by the product of the target amplitude value of the reactive current and COS (θ _uw )) becomes large. ^* _Inv changes greatly. As a result, the output current i _inv overshoot or undershoot tends to occur, and there is a possibility that the stability of the output current i _inv is impaired.

However, when the reactive current target value is updated every half cycle of the commercial system frequency and when the absolute value of the reverse flow current _isp is at or near its maximum, the command value i ^* _inv of the output current is updated. Since the output current i _inv is controlled at a timing when the influence of the reactive component (a value calculated by the product of the target amplitude value of reactive current and COS (θ _uw )) is reduced, the response of power factor control is improved. In addition, the stability of the output current i _inv is also improved.

In the seventh feature configuration, in addition to any one of the second to sixth feature configurations described above, the decrease suppression change amount Δy is at least a set value for voltage decrease suppression. It is obtained by the product of the difference ΔE _{min from the} commercial system voltage and the proportional gain Kp, the proportional gain Kp is changed to a magnitude based on the magnitude of the difference ΔE _min , and the increase suppression change amount Δy is at least a voltage increase suppression The proportional gain Kp is obtained by multiplying the difference ΔE _max between the set value and the commercial grid voltage and the proportional gain Kp, and the proportional gain Kp is changed to a magnitude based on the magnitude of the difference ΔE _min. .

The decrease suppression or increase suppression change amount Δy is calculated based on the product of the difference ΔE _min and the proportional gain Kp. If the difference ΔE _min is large at that time, the proportional gain Kp is set to a large value and the change amount Δy is large. Therefore, a large amount of suppression is obtained, and if the difference ΔE _min is small, the proportional gain Kp is set to a small value, the amount of change Δy is small, hunting near the settling value is suppressed, and convergence is improved.

As described in claim 8, the first characteristic configuration of the system voltage suppression control method according to the present invention is an inverter connected to a commercial system by converting DC generated power into AC power, and harmonics from the output of the inverter. A system voltage suppression control method for a power conditioner having an LC filter that removes a wave component, including an inverter output as a commercial system voltage e _uw , a capacitor current i _c of the LC filter, a capacitor capacity C _f , and an internal resistance R _c From the measured value of current i _inv

The reverse power flow current estimation step for estimating the reverse power flow current i _sp output from the power conditioner to the commercial power supply by subtracting the capacitor current _ic obtained in step (b), and the commercial system voltage e from the measured value of the commercial system voltage e _uw a first PLL processing step of outputting the phase angle theta _uw of _uw, second PLL which outputs a phase angle theta _sp of backward flow current _{i sp} from reverse flow current _{i sp} estimated by the backward flow current estimation step The phase difference Δφ (θ _uw −θ _sp ) between the commercial system voltage e _uw and the reverse flow current i _sp obtained from the processing step and the phase angle output from the first PLL processing step and the second PLL processing step. based on the feedback signal generating step of generating a power factor feedback signal and reactive current feedback signal, the effective value E _uw of the commercial system voltage is less than the first threshold voltage Suppression and decrease suppression control step of determining the decrease suppression variation suppressing deterioration of the commercial system voltage, a rise in the commercial system voltage when the effective value E _uw is more higher second threshold voltage than the first threshold voltage to come A driving power factor setting step including a rising suppression control step for obtaining a rising suppression change amount, and a power factor of the reverse power flow based on the power factor feedback signal to the power factor command value set in the driving power factor setting step A power factor control step for generating a target power factor so as to converge, and a target so that the power factor of the reverse flow power based on the power factor feedback signal converges to the power factor command value set in the power factor setting step. Based on the power factor control step for generating a power factor, the target power factor generated in the power factor control step and the reactive current feedback signal, a reactive current target value is output to an inverter control unit that controls the inverter In that it includes disabling the current control step, the that.

In the second feature configuration, as described in claim 9, in addition to the first feature configuration described above, the decrease suppression control step is performed up to a preset power factor lower limit value PF _min . The current power factor command value PF ^* is corrected by the decrease suppression change amount Δy calculated based on the deviation of the commercial system voltage with respect to the lower limit allowable voltage E ^* _min of the commercial system voltage, and the increase suppression control step includes: The current power factor command value PF ^* is corrected by the increase suppression change amount Δy calculated based on the deviation of the commercial system voltage from the upper limit allowable voltage E ^* _max up to a preset power factor lower limit value PF _min. It is in the point comprised as follows.

In the third feature configuration, as described in claim 10, in addition to the second feature configuration described above, the power factor command value PF ^* set by the increase suppression control step is a power factor lower limit value PF _min. When the value reaches the reactive current control value, the reactive current target value output by the reactive current control step is limited.

In the fourth feature configuration, in addition to any of the first to third feature configurations described above, the driving power factor control step includes a power factor command value PF ^* and a power factor. The PI control step for generating a correction value based on the deviation of the rate feedback signal, and the power factor target value PF ^* _real obtained by adding the power factor command value PF ^* to the correction value generated in the PI control step is invalid Coefficient for calculating power

And a coefficient generation step of adding a sign indicating a phase advance or delay to the coefficient according to the power factor command value PF ^* .

The fifth feature configuration is the update time of the reactive current target value output by the reactive current control step in addition to any of the first to fourth feature configurations described above, as described in claim 12. Is that the absolute value of the reverse flow current _isp is set at or near the half cycle of the commercial grid frequency.

In the sixth feature configuration, in addition to any one of the first to fifth feature configurations described above, the decrease suppression change amount Δy is at least a set value for suppressing voltage decrease. It is obtained by the product of the difference ΔE _{min from the} commercial system voltage and the proportional gain Kp, the proportional gain Kp is changed to a magnitude based on the magnitude of the difference ΔE _min , and the increase suppression change amount Δy is at least a voltage increase suppression The proportional gain Kp is obtained by multiplying the difference ΔE _max between the set value and the commercial grid voltage and the proportional gain Kp, and the proportional gain Kp is changed to a magnitude based on the magnitude of the difference ΔE _min. .

  The seventh characteristic configuration is the driving power factor setting for setting the driving power factor before the grid interconnection operation, in addition to any one of the first to sixth characteristic configurations described above. A step, and at the time of grid interconnection operation, the grid voltage linked operation is performed at the driving power factor set in the driving power factor setting step immediately after canceling the grid voltage suppression control.

  The characteristic configuration of the power conditioner according to the present invention is that, as described in claim 15, any one of the first to seventh system voltage suppression control devices described above is incorporated.

  As described above, according to the present invention, the system voltage suppression control device and the system voltage suppression of a power conditioner that can stably adjust the commercial system voltage of the latest distribution line while effectively using natural energy for power generation. A control method can be provided.

1 is a circuit configuration diagram of a distributed power source to which a system voltage suppression control device according to the present invention is applied. Control block diagram of system voltage suppression control device according to the present invention (A) is an output restriction control block diagram, (b) is an operation explanatory diagram of the switch SW of FIG. 3 (a). (A) is a power factor control block diagram, (b) is an explanatory diagram of the update time of the reactive current target value output by the reactive current control unit (A) is explanatory drawing of the relationship between a commercial system voltage, 1st and 2nd threshold voltage, and suppression control mode, (b) is explanatory drawing of the control system at the time of each suppression control. (A) is a decrease and increase suppression control unit, (b) is a characteristic diagram of the decrease suppression change amount Δy calculated by the decrease suppression control unit, and (c) is an increase suppression change amount Δy calculated by the increase suppression control unit. Characteristics chart Flow chart explaining operation of voltage rise suppression control Explanatory drawing of variable gain of decrease and increase suppression control unit

Hereinafter, a system voltage suppression control apparatus and a system voltage suppression control method for a power conditioner, which is a power conversion apparatus according to the present invention, will be described with reference to the drawings.
FIG. 1 shows a solar battery power generation apparatus 100 that is an example of a distributed power source. Solar cell power generation apparatus 100 is configured with a power conditioner PC that solar panels SP and the solar cell panel SP is connected, connector relay via a (not shown) unilamellar three-wire commercial system power source e _grid It is connected to the. Note that the present invention is not limited to the solar cell panel SP as the power generator connected to the power conditioner PC, and can also be applied when other power generators such as fuel cells are connected.

The power conditioner PC has a predetermined frequency and voltage value so as to be linked to a DC / DC converter 1 that boosts a DC voltage generated by the solar panel SP to a predetermined DC link voltage V _dc and a commercial power supply. An inverter 3 for converting to an AC voltage, an inductor L _f, and a capacitor C _f are provided, and an LC filter 4 for removing harmonic components is provided. Note that _Rf is a resistance component of the inductor, and _Rc is a resistance component of the capacitor.

The switches S1, S2, S3 and S4 provided in the inverter 3 are turned on / off by PWM control executed by a control block including the system voltage suppression control device 10 so that the frequency and voltage are adapted to be linked to the commercial system power supply. The harmonic component is removed from the output of the inverter 3 by the LC filter 4 and output as a sine wave AC power. In the figure, symbol C _dc is an electrolytic capacitor for stabilizing the DC link voltage, i _inv is the output current of the inverter, R _grid and L _grid are commercial system impedances, e _uw is the line voltage of u−w, e _uo commercial system voltage between uo, e _wo commercial system voltage between wo, i _sp is the reverse flow current, R _uw represents an AC load connected to the grid.

  FIG. 2 shows a control block of the system voltage suppression control device 10 configured to include a microcomputer, a memory, a peripheral circuit, and the like.

  The system voltage suppression control device 10 includes four control blocks, which are a power factor control unit, a DC voltage control unit, a reactive current control unit, and an output current control unit of an inverter. The system voltage suppression control device 10 has a cycle sufficiently shorter than the commercial power cycle, for example, several msec. The control program corresponding to each control block is repeatedly executed in the cycle.

  Specifically, the reverse flow current estimation unit 11, the first PLL processing unit 12, the second PLL processing unit 13, the feedback signal generation unit 14, the power factor control unit 15, the reactive current control unit 16, DC voltage control unit 17, output limiting unit 18, reactive power generation unit 19, active power generation unit 20, inverter output current control unit 21, PWM control unit 22, driving power factor setting unit 23, etc. Each control block is provided.

  The reverse power flow current estimation unit 11, the first PLL processing unit 12, the second PLL processing unit 13, the feedback signal generation unit 14, the power factor setting unit 23, and the power factor control unit 15 constitute a power factor control block. The voltage control unit 17 constitutes a constant control block for the DC bus voltage, the reactive current control unit 16 constitutes a reactive current control block, the reactive power generation unit 19, the active power generation unit 20, the inverter output current control unit 21, and the PWM. The control unit 22 constitutes an output current control block.

The reverse flow current estimator 11 subtracts the capacitor current _ic obtained by the following [ _Equation 5] from the measured value of the inverter output current i _inv using a current sensor or the like to change from the power conditioner to the commercial system power supply e _grid . This is a block for estimating the output reverse flow current i _sp (i _sp = i _inv −i _c ). _{Incidentally, e uw} commercial system voltage, the _{i c} capacitor current of the LC filter, the _{C f} capacitance, _{R c} is the internal resistance.

First PLL processing unit 12, a commercial system voltage e from the measured values of _uw block for outputting the phase angle theta _uw commercial system voltage e _uw, divided AC voltage by the resistor divider commercial system voltage e It is input to the first PLL processing unit 12 as _uw .

Second PLL processing section 13, the reverse flow current _{i sp} estimated by the reverse flow current estimating unit 11 is inputted, a block for outputting the phase angle theta _sp of backward flow current _{i sp} by PLL processing.

Feedback signal generator 14, a first PLL unit 12 and the second of the grid voltage _{e uw} and reverse flow current _{i sp} obtained from the phase angle output from the PLL section 13 phase difference Δφ (θ _uw - Based on θ _sp ), a block for generating a power factor feedback signal and a reactive current feedback signal, the value of cos (Δφ) is generated as the power factor feedback signal PF, and tan (Δφ) and the _peak value 2P _{uw of the} active current are generated. A product of / E _{uw · max} is generated as the reactive current feedback signal I _q . As shown in [ _Equation 6] below, P _uw is the active power, E _{uw · max} is the maximum voltage value, and T _Grid is the cycle of the system voltage.

The voltage range of the single-phase three-wire distribution system needs to be adjusted to 101V ± 6V according to the Electricity Business Act. Therefore, the operating power factor setting unit 23 obtains a reduction suppression change amount that suppresses the decrease in the commercial system voltage when the effective value E _uw of the commercial system voltage is equal to or lower than the first threshold voltage (98 V in the present embodiment). A decrease suppression control unit that corrects the rate command value, and an increase suppression change amount that suppresses an increase in system voltage when the effective value E _uw is equal to or higher than a second threshold voltage (104 V in the present embodiment) higher than the first threshold voltage. And a rise suppression control unit that obtains and corrects the intensification factor command value. With the corrected power factor command value, the rise and fall of the system voltage are suppressed.

As shown in FIG. 4A, the power factor control unit 15 generates a correction value based on the deviation between the rate command value PF ^* and the power factor feedback signal PF set by the driving power factor setting unit 23. 15A and a coefficient for obtaining reactive power from the power factor target value PF ^* _real obtained by adding the power factor command value PF ^* to the correction value generated by the PI control unit 15A based on the following [Equation 7] A coefficient generation unit 15B is provided that generates and adds a sign indicating phase advance or delay to the coefficient according to the power factor command value PF ^* . When the power factor command value PF ^* indicates a slow reactive current, a symbol “+1” is added, and when the power factor command value PF ^* indicates a fast reactive current, a symbol “−1” is added.

The reactive current control unit 16 outputs the reactive current target value to the inverter output current control unit 21 that controls the inverter 3 based on the target power factor PF _out and the reactive current feedback signal I _q generated by the power factor control unit 15. Is a control block.

Specifically, the product of the target power factor PF _out and the _peak value 2P _uw / E _{uw · max} of the active current is generated as the reactive current control value I ^* _q , and the reactive current feedback signal I _q is generated as the reactive current control value I ^* _q. This is a control block for PI calculation of the control amount so as to converge to.

The reactive power generation unit 19 multiplies the command value feedback-controlled by the reactive current control unit 16 and the cosine wave of the phase angle θ _uw corresponding to the commercial system voltage input from the first PLL processing unit 12 to invalidate the reactive power generation unit 19 It is a control block which produces | generates an electric power component.

The active power generation unit 20 is a block that generates an active power component by multiplying the bias DC voltage output from the DC voltage control unit 17 by a sine wave having a phase angle θ _uw corresponding to the commercial system voltage. The bias DC voltage is input from the DC voltage control unit 17 that adjusts and outputs the DC link voltage V _dc input from the DC / DC converter 1 to the command value V ^* _dc of the DC bus voltage, and has a phase corresponding to the commercial system voltage. A sine wave having an angle θ _uw is input from the first PLL processing unit 12.

Outputs from the active power generation unit 20 and the reactive power generation unit 16 are added by an adder to generate a current command value i ^* _inv for the inverter 3, and the current command value i ^* _inv is input to the inverter control unit 21. .

  When the reactive current is variably controlled by the reactive current control unit 16 and the apparent power increases, the burden on the circuit elements constituting the power conditioner PC increases. Therefore, it is necessary to select an expensive circuit element that can withstand that. . In order to deal with this problem, if the active power is adjusted so as to decrease, the stability of the operating power factor is impaired, and eventually the stability of the commercial system voltage is impaired.

  Therefore, an output limiting unit 18 is provided that limits the target current value output by the reactive current control unit 16 and the DC voltage control unit 17 when the output power deviates from a predetermined allowable range with respect to the rated power. By providing the output limiting unit 18, the target current value output by the reactive current control unit 16 and the DC voltage control unit 17 is limited, so that the power factor can be controlled stably while suppressing the apparent power to the rated value. It becomes like this.

As shown in FIGS. 3A and 3B, the output limiting unit 18 includes an apparent power control unit that performs PI control so that the feedback value S _uw of the apparent power converges to the apparent power command value S ^* _uw , A switch SW and an adder are provided. When the apparent power feedback value S _uw is within ± Δx% of the rated power S _PU (S _PU = S _uw / S ^* _uw ), the switch SW contact is switched to 1 to control the apparent power. When the apparent power feedback value S _uw deviates from the range of ± Δx% with respect to the rated power S _PU , the contact of the switch SW is switched to 0, and the output is limited to I _lim, that is, the rated power. The switch SW is switched with a hysteresis of Δx%.

The inverter control unit 21 to which the output current value i _inv of the inverter 3 is input as a feedback value performs feedback control using, for example, PI calculation so that the output current value of the inverter 3 becomes the current command value i ^* _inv. A control value for 3, here a duty ratio D, is generated. The duty ratio D generated by the inverter control unit 19 is input to the PWM control unit 22, and the PWM control unit 22 generates control signals for the switches S1, S2, S3, and S4. It is output to the switches S1, S2, S3 and S4.

As shown in FIG. 4B, the update timing of the current target value output by the reactive current control unit 16 and the DC voltage control unit 17 is every half cycle of the commercial system frequency and is the absolute value of the reverse flow current i _sp . It is set at a time when the value shows the maximum value or a time close to it. Specifically, it is _{determined in} a range of | i _sp | ≧ X · I _spmax (0 ≦ X ≦ 1). It is preferable to set X ≧ 0.9.

The amplitude of the reverse flow current fluctuates by drawing a sine curve based on the commercial grid frequency, but the reactive current target value is updated at the time when the sine curve zero-cross point, that is, when the absolute value of the reverse flow current _isp is the minimum value. Then, the command value i of the output current becomes a timing when the influence of the invalid component of the command value i ^* _inv of the output current (a value calculated by the product of the target amplitude value of the reactive current and COS (θ _uw )) becomes large. ^* _Inv changes greatly. As a result, the output current i _inv overshoot or undershoot tends to occur, and there is a possibility that the stability of the output current i _inv is impaired.

However, when the reactive current target value is updated every half cycle of the commercial system frequency and when the absolute value of the reverse flow current _isp is at or near its maximum, the command value i ^* _inv of the output current is updated. Since the output current i _inv is controlled at a timing when the influence of the reactive component (a value calculated by the product of the target amplitude value of reactive current and COS (θ _uw )) is reduced, the response of power factor control is improved. In addition, the stability of the output current i _inv is also improved.

As a result, a reactive current target value is generated by the reactive current control unit 16 based on the target power factor generated by the power factor control unit 15 and the reactive current feedback signal, and a desired reverse power flow current _isp is appropriately generated from the inverter 3. As a result, the fluctuation of the commercial system voltage can be appropriately suppressed.

Hereinafter, the driving power factor setting unit 23 will be described in detail.
As shown in FIGS. 5A and 5B, the power factor command value is set to 1 by the operating power factor setting unit 23 in a standard state where the effective value E _uw of the commercial system voltage falls within the range of 101 ± ΔV. Thereafter, when the effective value E _uw of the commercial system voltage decreases to 101−ΔV or less, the decrease suppression change amount is calculated by the decrease suppression control unit, and based on this, the power factor command value PF ^* is corrected, and the power factor control unit As a result, a slow phase reactive current is supplied to the commercial system, whereby the commercial system voltage is controlled to increase. When the effective value E _uw of the commercial system voltage rises to 101 + ΔV or more, the increase suppression change amount is calculated by the increase suppression control unit, and the power factor command value PF ^* is corrected based on the calculated increase suppression change amount. The commercial system voltage is controlled to be lowered by supplying a phase advance reactive current to the system.

The hysteresis characteristic is realized in the range of the effective value E _uw 101 ± ΔV of the commercial system voltage so that the control state does not change frequently between the suppression control at the time of system voltage drop and the control at the time of system voltage rise. Is set to The lower limit value PF _min of the power factor command value is set to 0.8 (80%). Note that the threshold value (effective value E _uw 101 ± ΔV) at which these controls are executed is not particularly limited, but is set as appropriate, and the single-phase three-wire commercial system voltage is defined within a range of 101 ± 6V. In Japan, it should be set within that range. In this embodiment, ΔV = 3 is set.

The power factor control unit 15 calculates a target power factor from each power factor command value PF ^* and the power factor feedback signal PF, and the reactive current control unit 16 performs a reactive current target value based on the target power factor and the reactive current feedback signal. Is generated, and a desired reverse flow current i _sp is appropriately output from the inverter 3. As a result, fluctuations in the commercial system voltage of the latest distribution line to which the power conditioner PC is connected are suppressed.

The decrease suppression control unit calculates the decrease suppression calculated based on the deviation of the commercial system voltage from the lower limit allowable voltage E ^* _min of the commercial system voltage up to a preset power factor lower limit value PF _min (= 0.8). The current power factor command value is corrected based on the amount of change Δy, and the rise suppression control unit increases the upper limit allowable voltage E ^* up to a preset power factor lower limit value PF _min (= 0.8) ^. _The present power factor command value PF ^* is corrected by the suppression change amount Δy calculated based on the deviation of the commercial system voltage with respect to _max .

As shown in FIG. _6A, when the effective value E _uw of the commercial system voltage becomes 101−ΔV or less, the control switch SW is switched to the 0 position, and the decrease suppression change amount Δy for suppressing the voltage decrease is calculated. When the effective value E _uw of the commercial system voltage becomes equal to or greater than 101 + ΔV, the control switch SW is switched to the 1 position, and the increase suppression change amount Δy for suppressing the voltage increase is calculated. As the effective value of the commercial grid voltage, an average value of several cycles to several tens of cycles of the commercial grid is used.

Figure 6 reference numerals shown in (a) ^E _{* min} is the voltage drop suppression set value clogging 101-2 · ΔV (= 95V), reference numeral _{E min} is the minimum value of the effective voltage value between u-o and w-o, code E ^* _max is set value, i.e. 101 + 2 · ΔV (= 107V ) of voltage rise suppression, reference numeral _{E max} is the maximum value of the effective voltage value between u-o and w-o, Delta] u is an integer value of the voltage rise suppression ^E _{* max} And the difference in the maximum value E _max of the effective voltage value between u−o and w−o.

Suppressing reduction variation Δy clogging correction amount at the time of voltage drop _suppression, after normalizing by multiplying _{1 /} a _(E uo ₊ E _wo) the difference Delta] E _min of _{E min} and ^E _{* min,} a low pass filter for removing an abrupt change This is a value obtained by processing, multiplying by the proportional gain Kp, and further limiting the upper limit by a limiter. FIG. 6B shows the decrease suppression change amount Δy when the proportional gain Kp is 0.5 or 1.0. Here, the upper and lower limit values of the limiter are set to ΔV / 101.

Elevation suppressing variation Δy clogging correction amount at the time of voltage rise _suppression, after normalizing by multiplying _{1 /} a _(E uo ₊ E _wo) the difference Delta] E _max of _{E max} and ^E _{* max,} a low pass filter for removing an abrupt change This is a value obtained by processing, multiplying by the proportional gain Kp, and further limiting the upper limit by a limiter. FIG. 6C shows the increase suppression change amount Δy when the proportional gain Kp is 0.5 or 1.0. fc is the cutoff frequency of the low-pass filter.

  The smaller the proportional gain Kp, the smaller the increase / decrease suppression change amount Δy near the voltage rise / fall suppression settling value, and the more stable the operating power factor of the power conditioner PC. It is also possible to suppress the suppression fluctuation amount of the commercial system voltage.

When the effective value E _uw of the commercial system voltage is equal to or lower than the first threshold voltage, the reduction based on the deviation between the lower limit allowable voltage E ^* _min of the commercial system voltage and the measured effective value of the commercial system voltage by the reduction suppression control unit When the suppression change amount Δy is calculated and the power factor command value is set according to the decrease suppression change amount Δy, and the effective value E _uw of the commercial system voltage is equal to or higher than the second threshold voltage, the increase suppression control unit sets the commercial system voltage. An increase suppression change amount Δy based on the deviation of the commercial system voltage with respect to the upper limit E ^* _max is calculated, and the power factor command value PF ^* is set according to the increase suppression change amount Δy. In any case, the power factor command value PF ^* does not fall below a preset power factor lower limit value PF _min .

The output limiting unit 18 described above limits the reactive current target value output by the reactive current control unit 16 when the power factor command value corrected by the increase suppression change amount Δy reaches the power factor lower limit value PF _min. It is configured as follows. Further, this is a power factor command value PF ^* for suppressing an increase in the commercial system voltage. When the power factor command value PF ^* reaches the power factor lower limit value PF _min , the reactive current target value is limited by the output limiting unit. As a result, an increase in the commercial system voltage is suppressed. Even if the power factor command value PF ^* corrected by the decrease suppression change amount Δy reaches the power factor lower limit value PF _min , the reactive current target value by the output limiting unit 18 is not limited.

[Equation 8] shows an arithmetic expression of the power factor command value PF ^* for suppressing the commercial system voltage drop reflecting the increase / suppression change amount Δy.

Seek operation power factor coefficient a at the rated from the ratio between the output power _{P uw} and rated apparent power _{S uw.rated,} as compared to power factor lower limit _{PF min,} operating power factor coefficients a and power factor lower limit value _{PF min} And find the maximum value. The reason for obtaining the maximum value of the driving power factor coefficient a and the power factor lower limit value PF _min is that the delay power is supplied without controlling the output limitation, and the power factor lower limit value PF _min (= 0.8) can be changed. It is for doing so. When the effective value E _uw of the commercial system voltage becomes 101−ΔV (= 98V) or more, the power factor command value PF ^* returns to the operating power factor set value PF _cst . The range of the driving power factor set value PF _cst can be set to a value between the power factor lower limit value PF _min and 1.

FIG. 7 shows a calculation flow of the power factor command value for suppressing the system voltage rise based on [Equation 8] and [Equation 9]. If the difference Δu between the set value 101 + 2 · ΔV (= 107V) and the feedback value of the system voltage rise suppression control is negative, the suppression operation is performed (S1, S2, S3, S4), and if it is the opposite, the suppression is canceled (S1) , S5, S6, S7). Here, when the voltage rise suppression operation is performed, the driving power factor is lowered to the lower limit (0.8) to suppress the voltage rise. At this time, when the commercial system voltage increases, the limiter value I _lim for output limitation (see FIG. 3B) is decreased to suppress the output power. When canceling the voltage rise suppression, the driving power factor is returned to the driving power factor set value PF _cst after canceling the output restriction. If the limiter value I _lim for output limitation is larger than the power factor lower limit value PF _min , the limiter value I _lim for output limitation and the power factor command value PF ^* using [Equation 8] and [Equation 9] ^. Is returned to the driving power factor set value PF _cst to perform constant control of the driving power factor.

FIG. 8 shows a configuration in which the proportional gain Kp of the suppression control loop is variably set.
It is preferable that the value of each proportional gain Kp can be changed within a range of ± X% of the command value E ^* of the suppression voltage of the control block shown in FIG. The speed at which the commercial system voltage is suppressed or decreased and the speed at which it is canceled can be adjusted by the value of the proportional gain Kp, and the proportional gain is used to improve the stability of the system near the suppression command value. This is because the value of Kp can also be lowered. Note that the values of the proportional gains Kp and X are values that are appropriately set through experiments or the like. In this embodiment, K1 = 0.5, K2 = 0.25, K3 = 1, and X = 5 are set.

That is, the decrease suppression change amount Δy is obtained by the product of at least the difference ΔE _min between the voltage drop suppression settling value and the commercial system voltage and the proportional gain Kp, and the proportional gain Kp is increased or decreased based on the difference ΔE _min. In other words, the increase suppression change amount Δy is obtained by a product of at least the difference ΔE _max between the voltage increase suppression settling value and the commercial system voltage and the proportional gain Kp, and the proportional gain Kp is increased or decreased based on the difference ΔE _min. It is comprised so that it can be replaced.

That is, the system voltage suppression control method of the power conditioner according to the present invention is based on the measured value of the inverter output current i _inv as the commercial system voltage e _uw , the LC filter capacitor current i _c , the capacitor capacitance C _f , and the internal resistance R _c. The reverse flow current estimation step for estimating the reverse flow current i _sp output from the power conditioner to the commercial power supply by subtracting the capacitor current _ic obtained by the above [Equation 3], and the measurement of the commercial grid voltage e _uw a first PLL processing step of outputting the phase angle theta _uw commercial system voltage e _uw from the value, and outputs a phase angle theta _sp of backward flow current i _sp from reverse flow current i _sp estimated by the backward flow current estimation step A second PLL processing step and a phase output from the first PLL processing step and the second PLL processing step. Based on obtained from time commercial system voltage e _uw and reverse flow current i _sp phase difference Δφ (θ _uw -θ _sp), the feedback signal generating step of generating a power factor feedback signal and reactive current feedback signal, the commercial A decrease suppression control step for obtaining a decrease suppression change amount that suppresses a decrease in the commercial system voltage when the effective value E _uw of the system voltage is equal to or lower than the first threshold voltage; and a first step in which the effective value E _uw is higher than the first threshold voltage. An operation power factor setting step including an increase suppression control step for determining an increase suppression change amount that suppresses an increase in commercial system voltage when the threshold voltage is equal to or higher than two threshold voltages; and a power factor of reverse power flow based on the power factor feedback signal A power factor control step for generating a target power factor so as to converge to the power factor command value set in the driving power factor setting step, and a target power factor generated in the power factor control step and the reactive current feedback signal. Zui and, a, a reactive current control step of outputting a reactive current target value to the inverter controller for controlling the inverter.

The power factor command value corrected by the decrease suppression change amount is based on a deviation of the commercial system voltage from the commercial system voltage lower limit allowable voltage E ^* _min up to a preset power factor lower limit value PF _min. The present power factor command value is corrected by the calculated decrease suppression change amount Δy. The power factor command value corrected by the increase suppression change amount is the increase suppression change amount calculated based on the deviation of the commercial system voltage from the upper limit allowable voltage E ^* _max up to a preset power factor lower limit value. The current power factor command value PF ^* is corrected by Δy.

Furthermore, when the power factor command value PF ^* set by the increase suppression control step reaches the power factor lower limit value PF _min , an output limiting step is provided for limiting the reactive current target value output by the reactive current control step. .

The driving power factor control step includes a PI control step for generating a correction value based on a deviation between the power factor command value PF ^* and the power factor feedback signal, and a power factor command value PF ^* as a correction value generated in the PI control step. A coefficient for generating reactive power from the power factor target value PF ^* _real obtained by addition and generating a coefficient determined by the above-mentioned [Equation 4], and adding a sign indicating a phase advance or delay to the coefficient according to the power factor command value It comprises a generation step.

As described above, the system voltage suppression control device sets the first threshold voltage and the second threshold voltage higher than the first threshold voltage in advance to the effective value E _uw of the commercial system voltage, and the first threshold voltage and the second threshold voltage are set. When the effective value E _uw of the commercial system voltage is equal to or lower than the first threshold voltage, the inverter is operated in a system voltage decrease suppression mode that suppresses the decrease in the commercial system voltage only by supplying the slow phase power. And when the effective value E _uw of the commercial grid voltage is equal to or higher than the second threshold voltage, the system voltage rise suppression mode suppresses the rise of the commercial grid voltage by supplying the phase advance power and / or reducing the active power. It is configured to control the inverter.

  Each of the above-described embodiments is merely an example of a system voltage suppression control device and control method for a power conditioner according to the present invention. Specific configurations (hardware and software), various numerical values, and the like of each component block are according to the present invention. Needless to say, it is possible to change and design appropriately within the range where the effects are exhibited.

1: DC / DC converter 3: Inverter 4: LC filter 10: System voltage suppression control device 11: Reverse power flow current estimation unit 12: First PLL processing unit 13: Second PLL processing unit 14: Feedback signal generation unit 15 : Power factor control unit 16: Reactive current control unit 17: DC voltage control unit 18: Output limiting unit 19: Reactive power generation unit 20: Active power generation unit 21: Inverter control unit 22: PWM control unit 23: Driving power factor setting Unit 100: Distributed power source (solar cell power generator)
PC: Power conditioner SP: Solar cell panels S1, S2, S3, S4: Switch elements provided in the inverter device

  The present invention relates to a system voltage suppression control device and system voltage of a power conditioner including an inverter that converts DC generated power into AC power and is linked to a commercial system, and an LC filter that removes harmonic components from the output of the inverter. The present invention relates to a suppression control method.

  The distributed power source that constitutes the photovoltaic system is equipped with a power conditioner that converts it into AC power with a frequency and voltage suitable for the grid frequency and grid voltage of the grid to be used in conjunction with a commercial grid. Yes.

  The power conditioner includes a DC / DC converter that adjusts a DC voltage generated by a distributed power source to a predetermined DC voltage value, an inverter that converts DC power output from the DC / DC converter into AC power, An LC filter that removes high-frequency components from the output is provided.

  Management for maintaining the voltage of the distribution line within a predetermined allowable range has become difficult due to the introduction and expansion of the photovoltaic power generation system. Generally, electric power companies introduce tap control equipment (SVR), STATCOM, and the like to manage the distribution lines so that they are maintained at an appropriate voltage.

  However, in recent years, in order to adjust the voltage of the nearest distribution line from the power conditioner side, it has a function to adjust the operating power factor of the power conditioner to be constant during grid connection operation or to suppress an increase in commercial system voltage It came to be required.

  Japanese Patent Application Laid-Open No. 2004-133830 describes a change amount of a first reactive power that is a fast reactive power or a slow reactive power that should be output by a power conditioner according to a deviation of a commercial grid frequency, and a rise in the commercial grid voltage. In addition, there has been proposed a control device that controls the output of the power conditioner based on at least one of the amount of change in the second reactive power that the power conditioner should output.

  When the control device changes the phase reactive power output from the power conditioner based on the amount of change in the second reactive power, the voltage corresponding to the output voltage of the power conditioner exceeds the upper limit voltage. If it becomes, it will be comprised so that the output of a power conditioner may be controlled so that the active power which a power conditioner outputs may be reduced.

  Patent Document 2 relates to a distributed power supply interconnection system having a configuration in which a plurality of distributed power supply facilities each having a distributed power supply and a load are connected to a power distribution system, and has conventionally been provided for suppressing a voltage drop in the power distribution system A distributed power supply interconnection system that aims to reduce the power consumption is disclosed.

  The distributed power interconnection system has two sets of injection frequencies each consisting of two injection frequencies that cause a beat, in which a plurality of distributed power supply facilities are classified into two groups, a first group and a second group. Thus, the frequency difference between the two injection frequencies constituting each set is the same in both sets, and the four injection frequencies constituting both sets are different from each other and are different from the fundamental frequency of the distribution system. Using the second set of injection frequencies, each distributed power supply facility belonging to the first group includes a current injection device for injecting an injection current including a current set of the first set of injection frequencies into the power distribution system, An injection frequency voltage measuring device for measuring a voltage at an interconnection point between the facility and the power distribution system and measuring at least one injection frequency of the second set of injection frequencies; Genus Each of the distributed power source holding facilities is a voltage at a connection point between the current injection device that injects an injection current including the current set of the second set of injection frequencies into the distribution system, and the own facility and the distribution system. An injection frequency voltage measuring device for measuring a voltage of at least one injection frequency of the first set of injection frequencies, and each of the distributed power source holding facilities of both groups is a group to which the own equipment belongs. Is called the other group, and the group to which the own equipment does not belong is called the other group, and the injected current causes the phase of each current of the current set constituting the injected current injected by the current injection device of the own equipment to be generated. A total phase of the injected current injected by the current injection device of the distributed power source possessing equipment belonging to another group while maintaining the same phase relation common within the same group with respect to the phase of the own equipment beat that is The voltage generated by It becomes provided with respective synchronization control unit for synchronizing with other groups beat.

  And each distributed power supply facility of both groups is equipped with a power consumption measuring device for measuring the power consumption received from the distribution system of its own equipment, and the current injection of each distributed power supply facility of both groups The apparatus injects the injection current having a magnitude corresponding to the power consumption measured by the power consumption measuring device of the own equipment, respectively, and each of the distributed power supply possession equipments of both groups A slow-phase reactive power control circuit that controls a distributed power source of equipment and outputs delayed-phase reactive power having a magnitude corresponding to the injected frequency voltage measured by the injected frequency voltage measuring device of the equipment from the distributed power source of the equipment. Each is equipped.

Japanese Patent Application Laid-Open No. 2014-207811 JP 2011-36067 A

  However, according to the control device disclosed in Patent Document 1, the amount of increase / decrease in reactive power is constant in the steady state in which the commercial grid voltage is maintained in a range defined by the Electric Utility Law, for example, 101V ± 6V. Therefore, it is difficult to suppress fluctuations in active power and reactive power in the vicinity of the set value of the commercial system voltage.

  In addition, the distributed power interconnection system disclosed in Patent Document 2 is provided with a power consumption measuring device in its own equipment to monitor the load power consumption and the voltage of the distribution line, and increase the load power consumption and at the same time the commercial system of the distribution line. Since it is configured to supply late phase reactive power to suppress the voltage drop, many current sensors are required to constantly monitor the load power consumption, which increases the cost and complexity of the control program. There was a problem of becoming.

  In view of the above-described problems, an object of the present invention is to provide a system voltage suppression control device and system for a power conditioner that can stably adjust the commercial system voltage of the latest distribution line while effectively using natural energy for power generation. This is in providing a voltage suppression control method.

In order to achieve the above-mentioned object, the first characteristic configuration of the system voltage suppression control device according to the present invention is a commercial product obtained by converting DC generated power into AC power as described in claim 1 of the claims. A system voltage suppression control device for a power conditioner including an inverter connected to a system, wherein a first threshold voltage and a second threshold voltage higher than the first threshold voltage are set in advance to an effective value E _uw of a commercial system voltage. In the hysteresis region between the first threshold voltage and the second threshold voltage, when the effective value E _uw of the commercial grid voltage is equal to or lower than the first threshold voltage, the commercial grid voltage is supplied only by supplying the slow phase power. controlling said inverter in suppressing system voltage drop suppression mode to decrease, when the effective value E _uw commercial system voltage is above the second threshold voltage, the quotient by the supply and / or reduction of active power of leading phase power In that it is configured to control the inverter to increase of the system voltage suppressing system voltage rise suppression mode.

  Even in the steady state where the commercial grid voltage is maintained in the range defined by the Electricity Business Law, for example, 101V ± 6V, the drop in grid voltage is suppressed by supplying slow-phase power when the voltage drops below the first threshold voltage. If the voltage rises above the second threshold voltage, phase-advancing power is supplied, and if necessary, the active power is reduced to suppress the increase in the commercial system voltage. In addition, the hysteresis area is provided to suppress the system voltage increase. Thus, the commercial system voltage can be stabilized by preventing the reduction suppression from being repeated.

As described in claim 2, the second characteristic configuration includes, in addition to the first characteristic configuration described above, an inverter connected to a commercial system by converting DC generated power into AC power, and A system voltage suppression control device for a power conditioner having an LC filter that removes harmonic components from the output, as a commercial system voltage e _uw , an LC filter capacitor current i _c , a capacitor capacitance C _f , and an internal resistance R _c From the measured value of the inverter output current i _inv

The reverse flow current estimator that estimates the reverse flow current i _sp that is output from the power conditioner to the commercial power supply by subtracting the capacitor current _ic obtained in step ( _b) , and the commercial grid voltage e from the measured value of the commercial grid voltage e _uw a first PLL unit for outputting the phase angle theta _uw of _uw, second PLL which outputs a phase angle theta _sp of backward flow current _{i sp} from reverse flow current _{i sp} estimated by the backward flow current estimating unit The phase difference Δφ (θ _uw −θ _sp ) between the commercial system voltage e _uw and the reverse flow current i _sp obtained from the phase angle output from the processing unit and the first PLL processing unit and the second PLL processing unit. based on the power factor feedback signal and a feedback signal generator for generating a reactive current feedback signal, the effective value E _uw commercial system voltage suppressing deterioration suppressing a decrease in the commercial system voltage when: the first threshold voltage A decrease suppression control unit for determining the reduction amount, an increase suppression control unit and the effective value E _uw is seeking inhibiting elevation variation suppressing an increase in the commercial system voltage when the above high second threshold voltage than the first threshold voltage power factor to produce the operating power factor setting unit, the target power factor as the power factor of the backward flow power on the basis of the previous SL power factor feedback signal converges to the set power factor command value by said power factor setting unit comprising And a reactive current control unit that outputs a reactive current target value to an inverter control unit that controls the inverter based on the target power factor generated by the power factor control unit and the reactive current feedback signal. There is in point.

If the commercial system voltage e _uw is measured without using a separate sensor for detecting the reverse flow current in addition to the output current i _{inv of the} inverter necessary for controlling the inverter, , the capacitance of the capacitor _{C f,} accurate capacitor current _{i c} in consideration of the internal resistance _{R c} can be estimated. The commercial system obtained from the first PLL processing unit based on the phase angle θ _sp of the reverse flow current i _sp obtained from the second PLL processing unit based on the capacitor current _ic and the commercial system voltage e _uw and a phase angle theta _uw voltage _{e uw,} a phase difference Δφ of the commercial system voltage _{e uw} and reverse flow current _{i sp} (θ _{uw -θ sp)} is obtained, the power factor feedback signal from the phase difference Δφ by the feedback signal generation unit And a reactive current feedback signal is generated.

In the operating power factor setting unit, the decrease suppression control unit suppresses the decrease in the commercial system voltage when the effective value E _uw of the commercial system voltage is equal to or lower than the first threshold voltage, that is, increases the slow phase reactive current. The power factor command value is corrected based on the decrease suppression change amount so that the rise of the commercial system voltage is suppressed when the effective value E _uw is equal to or higher than the second threshold voltage higher than the first threshold voltage. The power factor command value is corrected based on the rise suppression change amount so as to increase, and the power factor control unit calculates the target power factor from each power factor command value and the power factor feedback signal, and the target power factor and reactive current feedback are calculated. A reactive current target value is generated by the reactive current control unit based on the signal, and a desired reverse flow current _isp is appropriately output from the inverter. As a result, the fluctuation of the commercial system voltage of the latest distribution line to which the power conditioner is connected is suppressed.

In the third feature configuration, as described in claim 3, in addition to the second feature configuration described above, the decrease suppression control unit is configured to set a power factor lower limit value PF _min to a preset value. The current power factor command value PF ^* is corrected by a decrease suppression change amount Δy calculated based on a deviation of the commercial system voltage with respect to the lower limit allowable voltage E ^* _min of the commercial system voltage, and the increase suppression control unit The current power factor command value PF ^* is corrected by the increase suppression change amount Δy calculated based on the deviation of the commercial system voltage from the upper limit allowable voltage E ^* _max up to a preset power factor lower limit value PF _min. It is in the point comprised as follows.

When the effective value E _uw of the commercial system voltage is equal to or lower than the first threshold voltage, the reduction based on the deviation between the lower limit allowable voltage E ^* _min of the commercial system voltage and the measured effective value of the commercial system voltage by the reduction suppression control unit When the suppression change amount Δy is calculated and the power factor command value PF ^* is set according to the decrease suppression change amount Δy, and the effective value E _uw of the commercial system voltage is equal to or higher than the second threshold voltage, the second power factor command value is set. The increase suppression change amount Δy based on the deviation of the commercial system voltage with respect to the upper limit E ^* _max of the commercial system voltage is calculated by the unit, and the power factor command value PF ^* is set according to the increase suppression change amount Δy. In any case, the power factor command value PF ^* does not fall below a preset power factor lower limit value PF _min .

In the fourth feature configuration, as described in claim 4, in addition to the third feature configuration described above, the decrease suppression change amount Δy is a difference between at least a voltage drop suppression settling value and a commercial system voltage. ΔE _min And the proportional gain Kp, and the proportional gain Kp is the difference ΔE. _min The amount of increase suppression change Δy is at least the difference ΔE between the set value of suppression of voltage increase and the commercial system voltage. _max And the proportional gain Kp, and the proportional gain Kp is the difference ΔE. _max It is in the point which is comprised so that it may be changed into the size based on the magnitude of.

The decrease suppression or increase suppression change amount Δy is the difference ΔE. _min Is calculated based on the product of the proportional gain Kp and the difference ΔE _min Or the difference ΔE _max Is large, the proportional gain Kp is set to a large value and the change amount Δy becomes large, so that a large suppression amount is obtained, and the difference ΔE _min Is small, the proportional gain Kp is set to a small value, the change amount Δy is small, hunting near the settling value is suppressed, and the convergence is improved.

In the fifth feature configuration, as described in claim 5 , in addition to the third or fourth feature configuration described above, the power factor command value PF ^* set by the increase suppression control unit is a power factor lower limit. When the value PF _min is reached, an output limiting unit that limits the reactive current target value output by the reactive current control unit is provided.

When the power factor command value PF ^* for suppressing the increase of the commercial system voltage is corrected based on the increase suppression change amount, and the power factor command value PF ^* reaches the power factor lower limit value PF _min, it is invalidated by the output limiting unit. By limiting the current target value, an increase in the system voltage is suppressed. When the reactive current is variably controlled by the reactive current control unit and the apparent power increases, the burden on the circuit elements constituting the power conditioner increases. Therefore, it is necessary to select an expensive circuit element that can withstand that. In order to deal with this problem, if the active power is adjusted so as to decrease, the stability of the operating power factor is impaired, and eventually the stability of the commercial system voltage is impaired. Even in such a case, since the reactive current target value output by the reactive current control unit is limited by providing the output limiting unit, the driving power factor can be stably controlled while suppressing the apparent power to the rated value. It becomes like this.

The sixth characterizing feature of the can, as noted in the claim 6, in addition the second above Fifth any feature configuration of the power factor controller, power factor command value PF ^* and power factor A PI control unit that generates a correction value based on the deviation of the feedback signal, and a reactive power from the power factor target value PF ^* _real obtained by adding the power factor command value PF ^* to the correction value generated by the PI control unit Coefficient to find

And a coefficient generation unit for adding a sign indicating a phase advance or delay to the coefficient according to the power factor command value PF ^* .

Correction value as the power factor feedback signal from the deviation of the power factor feedback signal output from the feedback signal generator unit with a preset power factor command value PF ^* by the PI control unit is converged to the power factor command value PF ^* is A power factor target value PF ^* _real obtained by adding the power factor command value PF ^* to the correction value is obtained. The coefficient generation unit calculates a coefficient represented by [Equation 2] that is a ratio of reactive power to active power, and adds a code according to the power factor command value. Specifically, the sign “+1” is added when the power factor command value PF ^* indicates a slow reactive current, and the sign “−1” is added when it indicates a fast reactive current.

The seventh feature configuration is the update time of the reactive current target value output by the reactive current control unit in addition to any of the second to sixth feature configurations described above, as described in claim 7. Is set at a time when the absolute value of the reverse flow current i _sp shows the maximum value or at a time _{close to} it every half cycle of the commercial system frequency, and the reactive component of the measured reverse flow current i _sp is the reverse flow current i _sp. It is in the point which is comprised so that it may change at the time of the vicinity of the maximum value of absolute value.

The amplitude of the reverse flow current fluctuates by drawing a sine curve based on the commercial grid frequency, but the reactive current target value is updated at the time when the sine curve zero-cross point, that is, when the absolute value of the reverse flow current _isp is the minimum value. Then, the command value i of the output current becomes a timing when the influence of the invalid component of the command value i ^* _inv of the output current (a value calculated by the product of the target amplitude value of the reactive current and COS (θ _uw )) becomes large. ^* _Inv changes greatly. As a result, the output current i _inv overshoot or undershoot tends to occur, and there is a possibility that the stability of the output current i _inv is impaired.

However, when the reactive current target value is updated every half cycle of the commercial system frequency and when the absolute value of the reverse flow current _isp is at or near its maximum, the command value i ^* _inv of the output current is updated. Since the output current i _inv is controlled at a timing when the influence of the reactive component (a value calculated by the product of the target amplitude value of reactive current and COS (θ _uw )) is reduced, the response of power factor control is improved. stability of the output current i _inv not only be ing to enhance.

As described in claim 8, the first characteristic configuration of the system voltage suppression control method according to the present invention is an inverter connected to a commercial system by converting DC generated power into AC power, and harmonics from the output of the inverter. A system voltage suppression control method for a power conditioner having an LC filter that removes a wave component, including an inverter output as a commercial system voltage e _uw , a capacitor current i _c of the LC filter, a capacitor capacity C _f , and an internal resistance R _c From the measured value of current i _inv

The reverse power flow current estimation step for estimating the reverse power flow current i _sp output from the power conditioner to the commercial power supply by subtracting the capacitor current _ic obtained in step (b), and the commercial system voltage e from the measured value of the commercial system voltage e _uw a first PLL processing step of outputting the phase angle theta _uw of _uw, second PLL which outputs a phase angle theta _sp of backward flow current _{i sp} from reverse flow current _{i sp} estimated by the backward flow current estimation step The phase difference Δφ (θ _uw −θ _sp ) between the commercial system voltage e _uw and the reverse flow current i _sp obtained from the processing step and the phase angle output from the first PLL processing step and the second PLL processing step. based on the feedback signal generating step of generating a power factor feedback signal and reactive current feedback signal, the effective value E _uw of the commercial system voltage is less than the first threshold voltage Suppression and decrease suppression control step of determining the decrease suppression variation suppressing deterioration of the commercial system voltage, a rise in the commercial system voltage when the effective value E _uw is more higher second threshold voltage than the first threshold voltage to come A driving power factor setting step including a rising suppression control step for obtaining a rising suppression change amount, and a power factor of the reverse power flow based on the power factor feedback signal to the power factor command value set in the driving power factor setting step A power factor control step for generating a target power factor so as to converge, and a target so that the power factor of the reverse flow power based on the power factor feedback signal converges to the power factor command value set in the power factor setting step. Based on the power factor control step for generating a power factor, the target power factor generated in the power factor control step and the reactive current feedback signal, a reactive current target value is output to an inverter control unit that controls the inverter In that it includes disabling the current control step, the that.

In the second feature configuration, as described in claim 9, in addition to the first feature configuration described above, the decrease suppression control step is performed up to a preset power factor lower limit value PF _min . The current power factor command value PF ^* is corrected by the decrease suppression change amount Δy calculated based on the deviation of the commercial system voltage with respect to the lower limit allowable voltage E ^* _min of the commercial system voltage, and the increase suppression control step includes: The current power factor command value PF ^* is corrected by the increase suppression change amount Δy calculated based on the deviation of the commercial system voltage from the upper limit allowable voltage E ^* _max up to a preset power factor lower limit value PF _min. It is in the point comprised as follows.

In the third feature configuration, as described in claim 10, in addition to the first or second feature configuration described above, the decrease suppression change amount Δy includes at least a voltage decrease suppression settling value and a commercial system voltage. Difference ΔE from _min And the proportional gain Kp, and the proportional gain Kp is the difference ΔE. _min The amount of increase suppression change Δy is at least the difference ΔE between the set value of suppression of voltage increase and the commercial system voltage. _max And the proportional gain Kp, and the proportional gain Kp is the difference ΔE. _max It is in the point which is comprised so that it may be changed into the size based on the magnitude of.

In the fourth feature configuration, as described in claim 11 , in addition to the second or third feature configuration described above, the power factor command value PF ^* set by the increase suppression control step is a power factor lower limit. When the value PF _min is reached, an output limiting step for limiting the reactive current target value output by the reactive current control step is provided.

In the fifth feature configuration, as described in claim 12 , in addition to any of the first to fourth feature configurations described above, the driving power factor control step includes a power factor command value PF ^* and a power factor. The PI control step for generating a correction value based on the deviation of the rate feedback signal, and the power factor target value PF ^* _real obtained by adding the power factor command value PF ^* to the correction value generated in the PI control step is invalid Coefficient for calculating power

And a coefficient generation step of adding a sign indicating a phase advance or delay to the coefficient according to the power factor command value PF ^* .

The sixth feature configuration is the update time of the reactive current target value output by the reactive current control step in addition to any of the first to fifth feature configurations described above, as described in claim 13. It is Ru near the point where the absolute value of the reverse flow current i _sp a every half cycle of the utility power frequency is set timing or in the vicinity thereof timing indicating the maximum value.

  The seventh characteristic configuration is the driving power factor setting for setting the driving power factor before the grid interconnection operation, in addition to any one of the first to sixth characteristic configurations described above. A step, and at the time of grid interconnection operation, the grid voltage linked operation is performed at the driving power factor set in the driving power factor setting step immediately after canceling the grid voltage suppression control.

  The characteristic configuration of the power conditioner according to the present invention is that, as described in claim 15, any one of the first to seventh system voltage suppression control devices described above is incorporated.

  As described above, according to the present invention, the system voltage suppression control device and the system voltage suppression of a power conditioner that can stably adjust the commercial system voltage of the latest distribution line while effectively using natural energy for power generation. A control method can be provided.

1 is a circuit configuration diagram of a distributed power source to which a system voltage suppression control device according to the present invention is applied. Control block diagram of system voltage suppression control device according to the present invention (A) is an output restriction control block diagram, (b) is an operation explanatory diagram of the switch SW of FIG. 3 (a). (A) is a power factor control block diagram, (b) is an explanatory diagram of the update time of the reactive current target value output by the reactive current control unit (A) is explanatory drawing of the relationship between a commercial system voltage, 1st and 2nd threshold voltage, and suppression control mode, (b) is explanatory drawing of the control system at the time of each suppression control. (A) is a decrease and increase suppression control unit, (b) is a characteristic diagram of the decrease suppression change amount Δy calculated by the decrease suppression control unit, and (c) is an increase suppression change amount Δy calculated by the increase suppression control unit. Characteristics chart Flow chart explaining operation of voltage rise suppression control Explanatory drawing of variable gain of decrease and increase suppression control unit

Hereinafter, a system voltage suppression control apparatus and a system voltage suppression control method for a power conditioner, which is a power conversion apparatus according to the present invention, will be described with reference to the drawings.
FIG. 1 shows a solar battery power generation apparatus 100 that is an example of a distributed power source. Solar cell power generation apparatus 100 is configured with a power conditioner PC that solar panels SP and the solar cell panel SP is connected, connector relay via a (not shown) unilamellar three-wire commercial system power source e _grid It is connected to the. Note that the present invention is not limited to the solar cell panel SP as the power generator connected to the power conditioner PC, and can also be applied when other power generators such as fuel cells are connected.

The power conditioner PC has a predetermined frequency and voltage value so as to be linked to a DC / DC converter 1 that boosts a DC voltage generated by the solar panel SP to a predetermined DC link voltage V _dc and a commercial power supply. An inverter 3 for converting to an AC voltage, an inductor L _f, and a capacitor C _f are provided, and an LC filter 4 for removing harmonic components is provided. Note that _Rf is a resistance component of the inductor, and _Rc is a resistance component of the capacitor.

The switches S1, S2, S3 and S4 provided in the inverter 3 are turned on / off by PWM control executed by a control block including the system voltage suppression control device 10 so that the frequency and voltage are adapted to be linked to the commercial system power supply. The harmonic component is removed from the output of the inverter 3 by the LC filter 4 and output as a sine wave AC power. In the figure, symbol C _dc is an electrolytic capacitor for stabilizing the DC link voltage, i _inv is the output current of the inverter, R _grid and L _grid are commercial system impedances, e _uw is the line voltage of u−w, e _uo commercial system voltage between uo, e _wo commercial system voltage between wo, i _sp is the reverse flow current, R _uw represents an AC load connected to the grid.

  FIG. 2 shows a control block of the system voltage suppression control device 10 configured to include a microcomputer, a memory, a peripheral circuit, and the like.

  The system voltage suppression control device 10 includes four control blocks, which are a power factor control unit, a DC voltage control unit, a reactive current control unit, and an output current control unit of an inverter. The system voltage suppression control device 10 has a cycle sufficiently shorter than the commercial power cycle, for example, several msec. The control program corresponding to each control block is repeatedly executed in the cycle.

  Specifically, the reverse flow current estimation unit 11, the first PLL processing unit 12, the second PLL processing unit 13, the feedback signal generation unit 14, the power factor control unit 15, the reactive current control unit 16, DC voltage control unit 17, output limiting unit 18, reactive power generation unit 19, active power generation unit 20, inverter output current control unit 21, PWM control unit 22, driving power factor setting unit 23, etc. Each control block is provided.

  The reverse power flow current estimation unit 11, the first PLL processing unit 12, the second PLL processing unit 13, the feedback signal generation unit 14, the power factor setting unit 23, and the power factor control unit 15 constitute a power factor control block. The voltage control unit 17 constitutes a constant control block for the DC bus voltage, the reactive current control unit 16 constitutes a reactive current control block, the reactive power generation unit 19, the active power generation unit 20, the inverter output current control unit 21, and the PWM. The control unit 22 constitutes an output current control block.

The reverse flow current estimator 11 subtracts the capacitor current _ic obtained by the following [ _Equation 5] from the measured value of the inverter output current i _inv using a current sensor or the like to change from the power conditioner to the commercial system power supply e _grid . This is a block for estimating the output reverse flow current i _sp (i _sp = i _inv −i _c ). _{Incidentally, e uw} commercial system voltage, the _{i c} capacitor current of the LC filter, the _{C f} capacitance, _{R c} is the internal resistance.

First PLL processing unit 12, a commercial system voltage e from the measured values of _uw block for outputting the phase angle theta _uw commercial system voltage e _uw, divided AC voltage by the resistor divider commercial system voltage e It is input to the first PLL processing unit 12 as _uw .

Second PLL processing section 13, the reverse flow current _{i sp} estimated by the reverse flow current estimating unit 11 is inputted, a block for outputting the phase angle theta _sp of backward flow current _{i sp} by PLL processing.

Feedback signal generator 14, a first PLL unit 12 and the second of the grid voltage _{e uw} and reverse flow current _{i sp} obtained from the phase angle output from the PLL section 13 phase difference Δφ (θ _uw - Based on θ _sp ), a block for generating a power factor feedback signal and a reactive current feedback signal, the value of cos (Δφ) is generated as the power factor feedback signal PF, and tan (Δφ) and the _peak value 2P _{uw of the} active current are generated. A product of / E _{uw · max} is generated as the reactive current feedback signal I _q . As shown in [ _Equation 6] below, P _uw is the active power, E _{uw · max} is the maximum voltage value, and T _Grid is the cycle of the system voltage.

The voltage range of the single-phase three-wire distribution system needs to be adjusted to 101V ± 6V according to the Electricity Business Act. Therefore, the operating power factor setting unit 23 obtains a reduction suppression change amount that suppresses the decrease in the commercial system voltage when the effective value E _uw of the commercial system voltage is equal to or lower than the first threshold voltage (98 V in the present embodiment). A decrease suppression control unit that corrects the rate command value, and an increase suppression change amount that suppresses an increase in system voltage when the effective value E _uw is equal to or higher than a second threshold voltage (104 V in the present embodiment) higher than the first threshold voltage. And a rise suppression control unit that obtains and corrects the intensification factor command value. With the corrected power factor command value, the rise and fall of the system voltage are suppressed.

As shown in FIG. 4A, the power factor control unit 15 generates a correction value based on the deviation between the power factor command value PF ^* set by the driving power factor setting unit 23 and the power factor feedback signal PF. The coefficient for obtaining reactive power from the power factor target value PF ^* _real obtained by adding the power factor command value PF ^* to the correction value generated by the control unit 15A and the PI control unit 15A is expressed by the following [Equation 7]. And a coefficient generation unit 15b that generates a code based on the power factor command value PF ^* and adds a sign indicating a phase advance or delay to the coefficient. When the power factor command value PF ^* indicates a slow reactive current, a symbol “+1” is added, and when the power factor command value PF ^* indicates a fast reactive current, a symbol “−1” is added.

The reactive current control unit 16 outputs the reactive current target value to the inverter output current control unit 21 that controls the inverter 3 based on the target power factor PF _out and the reactive current feedback signal I _q generated by the power factor control unit 15. Is a control block.

Specifically, the product of the target power factor PF _out and the _peak value 2P _uw / E _{uw · max} of the active current is generated as the reactive current control value I ^* _q , and the reactive current feedback signal I _q is generated as the reactive current control value I ^* _q. This is a control block for PI calculation of the control amount so as to converge to.

The reactive power generation unit 19 multiplies the command value feedback-controlled by the reactive current control unit 16 and the cosine wave of the phase angle θ _uw corresponding to the commercial system voltage input from the first PLL processing unit 12 to invalidate the reactive power generation unit 19 It is a control block which produces | generates an electric power component.

The active power generation unit 20 is a block that generates an active power component by multiplying the bias DC voltage output from the DC voltage control unit 17 by a sine wave having a phase angle θ _uw corresponding to the commercial system voltage. The bias DC voltage is input from the DC voltage control unit 17 that adjusts and outputs the DC link voltage V _dc input from the DC / DC converter 1 to the command value V ^* _dc of the DC bus voltage, and has a phase corresponding to the commercial system voltage. A sine wave having an angle θ _uw is input from the first PLL processing unit 12.

Outputs from the active power generation unit 20 and the reactive power generation unit 19 are added by an adder to generate a current command value i ^* _inv for the inverter 3, and the current command value i ^* _inv is input to the inverter control unit 21. .

  When the reactive current is variably controlled by the reactive current control unit 16 and the apparent power increases, the burden on the circuit elements constituting the power conditioner PC increases. Therefore, it is necessary to select an expensive circuit element that can withstand that. . In order to deal with this problem, if the active power is adjusted so as to decrease, the stability of the operating power factor is impaired, and eventually the stability of the commercial system voltage is impaired.

  Therefore, an output limiting unit 18 is provided that limits the target current value output by the reactive current control unit 16 and the DC voltage control unit 17 when the output power deviates from a predetermined allowable range with respect to the rated power. By providing the output limiting unit 18, the target current value output by the reactive current control unit 16 and the DC voltage control unit 17 is limited, so that the power factor can be controlled stably while suppressing the apparent power to the rated value. It becomes like this.

As shown in FIGS. 3A and 3B, the output limiting unit 18 includes an apparent power control unit that performs PI control so that the feedback value S _uw of the apparent power converges to the apparent power command value S ^* _uw , A switch SW and an adder are provided. When the apparent power feedback value S _uw is within ± Δx% of the rated power S _PU (S _PU = S _uw / S ^* _uw ), the switch SW contact is switched to 1 to control the apparent power. When the apparent power feedback value S _uw deviates from the range of ± Δx% with respect to the rated power S _PU , the contact of the switch SW is switched to 0, and the output is limited to I _lim, that is, the rated power. The switch SW is switched with a hysteresis of Δx%.

The inverter control unit 21 to which the output current value i _inv of the inverter 3 is input as a feedback value performs feedback control using, for example, PI calculation so that the output current value of the inverter 3 becomes the current command value i ^* _inv. A control value for 3, here a duty ratio D, is generated. The duty ratio D generated by the inverter control unit 19 is input to the PWM control unit 22, and the PWM control unit 22 generates control signals for the switches S1, S2, S3, and S4. It is output to the switches S1, S2, S3 and S4.

As shown in FIG. 4B, the update timing of the current target value output by the reactive current control unit 16 and the DC voltage control unit 17 is every half cycle of the commercial system frequency and is the absolute value of the reverse flow current i _sp . It is set at a time when the value shows the maximum value or a time close to it. Specifically, it is _{determined in} a range of | i _sp | ≧ X · I _spmax (0 ≦ X ≦ 1). It is preferable to set X ≧ 0.9.

The amplitude of the reverse flow current fluctuates by drawing a sine curve based on the commercial grid frequency, but the reactive current target value is updated at the time when the sine curve zero-cross point, that is, when the absolute value of the reverse flow current _isp is the minimum value. Then, the command value i of the output current becomes a timing when the influence of the invalid component of the command value i ^* _inv of the output current (a value calculated by the product of the target amplitude value of the reactive current and COS (θ _uw )) becomes large. ^* _Inv changes greatly. As a result, the output current i _inv overshoot or undershoot tends to occur, and there is a possibility that the stability of the output current i _inv is impaired.

However, when the reactive current target value is updated every half cycle of the commercial system frequency and when the absolute value of the reverse flow current _isp is at or near its maximum, the command value i ^* _inv of the output current is updated. Since the output current i _inv is controlled at a timing when the influence of the reactive component (a value calculated by the product of the target amplitude value of reactive current and COS (θ _uw )) is reduced, the response of power factor control is improved. In addition, the stability of the output current i _inv is also improved.

As a result, a reactive current target value is generated by the reactive current control unit 16 based on the target power factor generated by the power factor control unit 15 and the reactive current feedback signal, and a desired reverse power flow current _isp is appropriately generated from the inverter 3. As a result, the fluctuation of the commercial system voltage can be appropriately suppressed.

Hereinafter, the driving power factor setting unit 23 will be described in detail.
As shown in FIGS. 5A and 5B, the power factor command value is set to 1 by the operating power factor setting unit 23 in a standard state where the effective value E _uw of the commercial system voltage falls within the range of 101 ± ΔV. Thereafter, when the effective value E _uw of the commercial system voltage decreases to 101−ΔV or less, the decrease suppression change amount is calculated by the decrease suppression control unit, and based on this, the power factor command value PF ^* is corrected, and the power factor control unit As a result, a slow phase reactive current is supplied to the commercial system, whereby the commercial system voltage is controlled to increase. When the effective value E _uw of the commercial system voltage rises to 101 + ΔV or more, the increase suppression change amount is calculated by the increase suppression control unit, and the power factor command value PF ^* is corrected based on the calculated increase suppression change amount. The commercial system voltage is controlled to be lowered by supplying a phase advance reactive current to the system.

The hysteresis characteristic is realized in the range of the effective value E _uw 101 ± ΔV of the commercial system voltage so that the control state does not change frequently between the suppression control at the time of system voltage drop and the control at the time of system voltage rise. Is set to The lower limit value PF _min of the power factor command value is set to 0.8 (80%). Note that the threshold value (effective value E _uw 101 ± ΔV) at which these controls are executed is not particularly limited, but is set as appropriate, and the single-phase three-wire commercial system voltage is defined within a range of 101 ± 6V. In Japan, it should be set within that range. In this embodiment, ΔV = 3 is set.

The power factor control unit 15 calculates a target power factor from each power factor command value PF ^* and the power factor feedback signal PF, and the reactive current control unit 16 performs a reactive current target value based on the target power factor and the reactive current feedback signal. Is generated, and a desired reverse flow current i _sp is appropriately output from the inverter 3. As a result, fluctuations in the commercial system voltage of the latest distribution line to which the power conditioner PC is connected are suppressed.

The decrease suppression control unit calculates the decrease suppression calculated based on the deviation of the commercial system voltage from the lower limit allowable voltage E ^* _min of the commercial system voltage up to a preset power factor lower limit value PF _min (= 0.8). The current power factor command value is corrected based on the amount of change Δy, and the rise suppression control unit increases the upper limit allowable voltage E ^* up to a preset power factor lower limit value PF _min (= 0.8) ^. _The present power factor command value PF ^* is corrected by the suppression change amount Δy calculated based on the deviation of the commercial system voltage with respect to _max .

As shown in FIG. _6A, when the effective value E _uw of the commercial system voltage becomes 101−ΔV or less, the control switch SW is switched to the 0 position, and the decrease suppression change amount Δy for suppressing the voltage decrease is calculated. When the effective value E _uw of the commercial system voltage becomes equal to or greater than 101 + ΔV, the control switch SW is switched to the 1 position, and the increase suppression change amount Δy for suppressing the voltage increase is calculated. As the effective value of the commercial grid voltage, an average value of several cycles to several tens of cycles of the commercial grid is used.

Figure 6 reference numerals shown in (a) ^E _{* min} is the voltage drop suppression set value clogging 101-2 · ΔV (= 95V), reference numeral _{E min} is the minimum value of the effective voltage value between u-o and w-o, code E ^* _max is set value, i.e. 101 + 2 · ΔV (= 107V ) of voltage rise suppression, reference numeral _{E max} is the maximum value of the effective voltage value between u-o and w-o, Delta] u is an integer value of the voltage rise suppression ^E _{* max} And the difference in the maximum value E _max of the effective voltage value between u−o and w−o.

Suppressing reduction variation Δy clogging correction amount at the time of voltage drop _suppression, after normalizing by multiplying _{1 /} a _(E uo ₊ E _wo) the difference Delta] E _min of _{E min} and ^E _{* min,} a low pass filter for removing an abrupt change This is a value obtained by processing, multiplying by the proportional gain Kp, and further limiting the upper limit by a limiter. FIG. 6B shows the decrease suppression change amount Δy when the proportional gain Kp is 0.5 or 1.0. Here, the upper and lower limit values of the limiter are set to ΔV / 101.

Elevation suppressing variation Δy clogging correction amount at the time of voltage rise _suppression, after normalizing by multiplying _{1 /} a _(E uo ₊ E _wo) the difference Delta] E _max of _{E max} and ^E _{* max,} a low pass filter for removing an abrupt change This is a value obtained by processing, multiplying by the proportional gain Kp, and further limiting the upper limit by a limiter. FIG. 6C shows the increase suppression change amount Δy when the proportional gain Kp is 0.5 or 1.0. fc is the cutoff frequency of the low-pass filter.

  The smaller the proportional gain Kp, the smaller the increase / decrease suppression change amount Δy near the voltage rise / fall suppression settling value, and the more stable the operating power factor of the power conditioner PC. It is also possible to suppress the suppression fluctuation amount of the commercial system voltage.

When the effective value E _uw of the commercial system voltage is equal to or lower than the first threshold voltage, the reduction based on the deviation between the lower limit allowable voltage E ^* _min of the commercial system voltage and the measured effective value of the commercial system voltage by the reduction suppression control unit When the suppression change amount Δy is calculated and the power factor command value is set according to the decrease suppression change amount Δy, and the effective value E _uw of the commercial system voltage is equal to or higher than the second threshold voltage, the increase suppression control unit sets the commercial system voltage. An increase suppression change amount Δy based on the deviation of the commercial system voltage with respect to the upper limit E ^* _max is calculated, and the power factor command value PF ^* is set according to the increase suppression change amount Δy. In any case, the power factor command value PF ^* does not fall below a preset power factor lower limit value PF _min .

The output limiting unit 18 described above limits the reactive current target value output by the reactive current control unit 16 when the power factor command value corrected by the increase suppression change amount Δy reaches the power factor lower limit value PF _min. It is configured as follows. Further, this is a power factor command value PF ^* for suppressing an increase in the commercial system voltage. When the power factor command value PF ^* reaches the power factor lower limit value PF _min , the reactive current target value is limited by the output limiting unit. As a result, an increase in the commercial system voltage is suppressed. Even if the power factor command value PF ^* corrected by the decrease suppression change amount Δy reaches the power factor lower limit value PF _min , the reactive current target value by the output limiting unit 18 is not limited.

[Equation 8] shows an arithmetic expression of the power factor command value PF ^* for suppressing the commercial system voltage drop reflecting the increase / suppression change amount Δy.

Seek operation power factor coefficient a at the rated from the ratio between the output power _{P uw} and rated apparent power _{S uw.rated,} as compared to power factor lower limit _{PF min,} operating power factor coefficients a and power factor lower limit value _{PF min} And find the maximum value. The reason for obtaining the maximum value of the driving power factor coefficient a and the power factor lower limit value PF _min is that the delay power is supplied without controlling the output limitation, and the power factor lower limit value PF _min (= 0.8) can be changed. It is for doing so. When the effective value E _uw of the commercial system voltage becomes 101−ΔV (= 98V) or more, the power factor command value PF ^* returns to the operating power factor set value PF _cst . The range of the driving power factor set value PF _cst can be set to a value between the power factor lower limit value PF _min and 1.

FIG. 7 shows a calculation flow of the power factor command value for suppressing the system voltage rise based on [Equation 8] and [Equation 9]. If the difference Δu between the set value 101 + 2 · ΔV (= 107V) and the feedback value of the system voltage rise suppression control is negative, the suppression operation is performed (S1, S2, S3, S4), and if it is the opposite, the suppression is canceled (S1) , S5, S6, S7). Here, when the voltage rise suppression operation is performed, the driving power factor is lowered to the lower limit (0.8) to suppress the voltage rise. At this time, when the commercial system voltage increases, the limiter value I _lim for output limitation (see FIG. 3B) is decreased to suppress the output power. When canceling the voltage rise suppression, the driving power factor is returned to the driving power factor set value PF _cst after canceling the output restriction. If the limiter value I _lim for output limitation is larger than the power factor lower limit value PF _min , the limiter value I _lim for output limitation and the power factor command value PF ^* using [Equation 8] and [Equation 9] ^. Is returned to the driving power factor set value PF _cst to perform constant control of the driving power factor.

FIG. 8 shows a configuration in which the proportional gain Kp of the suppression control loop is variably set.
It is preferable that the value of each proportional gain Kp can be changed within a range of ± X% of the command value E ^* of the suppression voltage of the control block shown in FIG. The speed at which the commercial system voltage is suppressed or decreased and the speed at which it is canceled can be adjusted by the value of the proportional gain Kp, and the proportional gain is used to improve the stability of the system near the suppression command value. This is because the value of Kp can also be lowered. Note that the values of the proportional gains Kp and X are values that are appropriately set through experiments or the like. In this embodiment, K1 = 0.5, K2 = 0.25, K3 = 1, and X = 5 are set.

That is, the decrease suppression change amount Δy is obtained by the product of at least the difference ΔE _min between the voltage drop suppression settling value and the commercial system voltage and the proportional gain Kp, and the proportional gain Kp is increased or decreased based on the difference ΔE _min. In other words, the increase suppression change amount Δy is obtained by the product of at least the difference ΔE _max between the voltage increase suppression settling value and the commercial system voltage and the proportional gain Kp, and the proportional gain Kp is increased or decreased based on the difference ΔE _max. It is comprised so that it can be replaced.

That is, the system voltage suppression control method of the power conditioner according to the present invention is based on the measured value of the inverter output current i _inv as the commercial system voltage e _uw , the LC filter capacitor current i _c , the capacitor capacitance C _f , and the internal resistance R _c. The reverse flow current estimation step for estimating the reverse flow current i _sp output from the power conditioner to the commercial power supply by subtracting the capacitor current _ic obtained by the above [Equation 3], and the measurement of the commercial grid voltage e _uw a first PLL processing step of outputting the phase angle theta _uw commercial system voltage e _uw from the value, and outputs a phase angle theta _sp of backward flow current i _sp from reverse flow current i _sp estimated by the backward flow current estimation step A second PLL processing step and a phase output from the first PLL processing step and the second PLL processing step. Based on obtained from time commercial system voltage e _uw and reverse flow current i _sp phase difference Δφ (θ _uw -θ _sp), the feedback signal generating step of generating a power factor feedback signal and reactive current feedback signal, the commercial A decrease suppression control step for obtaining a decrease suppression change amount that suppresses a decrease in the commercial system voltage when the effective value E _uw of the system voltage is equal to or lower than the first threshold voltage; and a first step in which the effective value E _uw is higher than the first threshold voltage. An operation power factor setting step including an increase suppression control step for determining an increase suppression change amount that suppresses an increase in commercial system voltage when the threshold voltage is equal to or higher than two threshold voltages; and a power factor of reverse power flow based on the power factor feedback signal A power factor control step for generating a target power factor so as to converge to the power factor command value set in the driving power factor setting step, and a target power factor generated in the power factor control step and the reactive current feedback signal. Zui and, a, a reactive current control step of outputting a reactive current target value to the inverter controller for controlling the inverter.

The power factor command value corrected by the decrease suppression change amount is based on a deviation of the commercial system voltage from the commercial system voltage lower limit allowable voltage E ^* _min up to a preset power factor lower limit value PF _min. The present power factor command value is corrected by the calculated decrease suppression change amount Δy. The power factor command value corrected by the increase suppression change amount is the increase suppression change amount calculated based on the deviation of the commercial system voltage from the upper limit allowable voltage E ^* _max up to a preset power factor lower limit value. The current power factor command value PF ^* is corrected by Δy.

Furthermore, when the power factor command value PF ^* set by the increase suppression control step reaches the power factor lower limit value PF _min , an output limiting step is provided for limiting the reactive current target value output by the reactive current control step. .

The driving power factor control step includes a PI control step for generating a correction value based on a deviation between the power factor command value PF ^* and the power factor feedback signal, and a power factor command value PF ^* as a correction value generated in the PI control step. A coefficient for generating reactive power from the power factor target value PF ^* _real obtained by addition and generating a coefficient determined by the above-mentioned [Equation 4], and adding a sign indicating a phase advance or delay to the coefficient according to the power factor command value It comprises a generation step.

As described above, the system voltage suppression control device sets the first threshold voltage and the second threshold voltage higher than the first threshold voltage in advance to the effective value E _uw of the commercial system voltage, and the first threshold voltage and the second threshold voltage are set. When the effective value E _uw of the commercial system voltage is equal to or lower than the first threshold voltage, the inverter is operated in a system voltage decrease suppression mode that suppresses the decrease in the commercial system voltage only by supplying the slow phase power. And when the effective value E _uw of the commercial grid voltage is equal to or higher than the second threshold voltage, the system voltage rise suppression mode suppresses the rise of the commercial grid voltage by supplying the phase advance power and / or reducing the active power. It is configured to control the inverter.

  Each of the above-described embodiments is merely an example of a system voltage suppression control device and control method for a power conditioner according to the present invention. Specific configurations (hardware and software), various numerical values, and the like of each component block are according to the present invention. Needless to say, it is possible to change and design appropriately within the range where the effects are exhibited.

1: DC / DC converter 3: Inverter 4: LC filter 10: System voltage suppression control device 11: Reverse power flow current estimation unit 12: First PLL processing unit 13: Second PLL processing unit 14: Feedback signal generation unit 15 : Power factor control unit 16: Reactive current control unit 17: DC voltage control unit 18: Output limiting unit 19: Reactive power generation unit 20: Active power generation unit 21: Inverter control unit 22: PWM control unit 23: Driving power factor setting Unit 100: Distributed power source (solar cell power generator)
PC: Power conditioner SP: Solar cell panels S1, S2, S3, S4: Switch elements provided in the inverter device

Claims (15)

A system voltage suppression control device for a power conditioner including an inverter connected to a commercial system by converting DC generated power into AC power,
A commercial system voltage is set in advance by setting a first threshold voltage and a second threshold voltage higher than the first threshold voltage to an effective value E _uw of the commercial system voltage, and setting a hysteresis region between the first threshold voltage and the second threshold voltage. When the effective voltage value E _uw is less than or equal to the first threshold voltage, the inverter is controlled in a system voltage decrease suppression mode that suppresses the decrease in the commercial system voltage only by supplying the slow phase power, and the effective value of the commercial system voltage When E _uw is equal to or higher than the second threshold voltage, the inverter is controlled in a system voltage increase suppression mode that suppresses an increase in commercial system voltage by supplying phase advance power and / or reducing active power. System voltage suppression control device. A system voltage suppression control device for a power conditioner including an inverter that converts DC generated power into AC power and that is linked to a commercial system, and an LC filter that removes harmonic components from the output of the inverter,
From the measured value of the inverter output current i _inv as the commercial system voltage e _uw , the capacitor current i _c of the LC filter, the capacitor capacity C _f , and the internal resistance R _c

A reverse flow current estimation unit that estimates the reverse flow current i _sp output from the power conditioner to the commercial power supply by subtracting the capacitor current _ic obtained by
A first PLL unit for outputting the phase angle theta _uw commercial system voltage _{e uw} from the measured value of the commercial power system voltage _{e uw,}
A second PLL processing unit that outputs a phase angle θ _sp of the reverse flow current i _sp from the reverse flow current i _sp estimated by the reverse flow current estimation unit;
Based on the phase difference Δφ (θ _uw −θ _sp ) between the commercial system voltage e _uw obtained from the phase angle output from the first PLL processing unit and the second PLL processing unit and the reverse flow current i _sp. A feedback signal generator for generating a rate feedback signal and a reactive current feedback signal;
A reduction suppression control unit that obtains a reduction suppression change amount that suppresses a reduction in commercial system voltage when the effective value E _uw of the commercial system voltage is equal to or lower than a first threshold voltage; and the effective value E _uw is obtained from the first threshold voltage. An operating power factor setting unit including an increase suppression control unit for determining an increase suppression change amount that suppresses an increase in the commercial system voltage when the voltage is equal to or higher than a high second threshold voltage;
A power factor control unit that generates a target power factor so that the power factor of the reverse power flow power converges to the power factor command value set by the driving power factor setting unit based on the power factor feedback signal;
Based on the target power factor generated by the power factor control unit and the reactive current feedback signal, a reactive current control unit that outputs a reactive current target value to an inverter control unit that controls the inverter;
A system voltage suppression control device. The decrease suppression control unit uses a decrease suppression change amount Δy calculated based on a deviation of the commercial system voltage with respect to the lower limit allowable voltage E ^* _min of the commercial system voltage up to a preset power factor lower limit value PF _min. It is configured to correct the current power factor command value PF ^* ,
The increase suppression control unit determines the current power factor command based on the increase suppression change amount Δy calculated based on the deviation of the commercial system voltage from the upper limit allowable voltage E ^* _max up to a preset power factor lower limit value PF _min. The system voltage suppression control device according to claim 2, which is configured to correct the value PF ^* . An output limiting unit that limits a reactive current target value output by the reactive current control unit when the power factor command value PF ^* set by the increase suppression control unit reaches a power factor lower limit value PF _min . Item 4. The system voltage suppression control device according to Item 3. The power factor control unit includes a PI control unit that generates a correction value based on a deviation between the power factor command value PF ^* and the power factor feedback signal, and a power factor command value PF ^* to the correction value generated by the PI control unit ^. _Is a coefficient for obtaining reactive power from the power factor target value PF ^* _real obtained by adding

The system voltage suppression control according to any one of claims 2 to 4, further comprising: a coefficient generation unit that generates a power factor command value PF ^* and adds a sign indicating phase advance or delay to the coefficient. apparatus. The reactive current target value output by the reactive current control unit is updated every half cycle of the commercial system frequency, and is set to a time when the absolute value of the reverse flow current i _sp shows the maximum value or a time close thereto, The system voltage suppression control device according to any one of claims 2 to 5, wherein the ineffective component of the measured reverse flow current _isp is changed in the vicinity of the maximum absolute value of the reverse flow current _isp. . The decrease suppression change amount Δy is obtained by a product of at least the difference ΔE _min between the voltage drop suppression settling value and the commercial grid voltage and the proportional gain Kp, and the proportional gain Kp is determined based on the difference ΔE _min. The increase suppression change amount Δy is obtained by the product of at least the difference ΔE _max between the voltage increase suppression settling value and the commercial system voltage and the proportional gain Kp, and the proportional gain Kp is the magnitude of the difference ΔE _min . The system voltage suppression control device according to any one of claims 2 to 6, wherein the system voltage suppression control device is configured so as to be changed to a large or small size based on the above. A system voltage suppression control method for a power conditioner including an inverter connected to a commercial system by converting DC generated power to AC power, and an LC filter that removes harmonic components from the output of the inverter,
From the measured value of the inverter output current i _inv as the commercial system voltage e _uw , the capacitor current i _c of the LC filter, the capacitor capacity C _f , and the internal resistance R _c

A reverse flow current estimation step for estimating a reverse flow current i _sp output from the power conditioner to the commercial power supply by subtracting the capacitor current _ic obtained by
A first PLL processing step of outputting the phase angle theta _uw commercial system voltage _{e uw} from the measured value of the commercial power system voltage _{e uw,}
A second PLL processing step for outputting a phase angle θ _sp of the reverse flow current i _sp from the reverse flow current i _sp estimated in the reverse flow current estimation step;
Based on the phase difference Δφ (θ _uw −θ _sp ) between the commercial grid voltage e _uw and the reverse flow current i _sp obtained from the phase angle output from the first PLL processing step and the second PLL processing step, the force A feedback signal generation step for generating a rate feedback signal and a reactive current feedback signal;
A decrease suppression control step for obtaining a decrease suppression change amount that suppresses a decrease in the commercial system voltage when the effective value E _uw of the commercial system voltage is equal to or lower than the first threshold voltage; and the effective value E _uw is obtained from the first threshold voltage. A driving power factor setting step including an increase suppression control step for determining an increase suppression change amount that suppresses an increase in the commercial system voltage when the voltage is equal to or higher than a high second threshold voltage;
A power factor control step for generating a target power factor so that the power factor of the reverse power flow converges to the power factor command value set in the operating power factor setting step based on the power factor feedback signal;
Based on the target power factor generated in the power factor control step and the reactive current feedback signal, a reactive current control step that outputs a reactive current target value to an inverter control unit that controls the inverter;
A system voltage suppression control method comprising: The decrease suppression control step is based on a decrease suppression change amount Δy calculated based on a deviation of the commercial system voltage with respect to the lower limit allowable voltage E ^* _min of the commercial system voltage up to a preset power factor lower limit value PF _min. It is configured to correct the current power factor command value PF ^* ,
The increase suppression control step includes a current power factor command based on an increase suppression change amount Δy calculated based on the deviation of the commercial system voltage from the upper limit allowable voltage E ^* _max up to a preset power factor lower limit value PF _min. The system voltage suppression control method according to claim 8, wherein the system voltage suppression control method is configured to correct the value PF ^* . An output limiting step is provided for limiting the reactive current target value output by the reactive current control step when the power factor command value PF ^* set by the increase suppression control step reaches a power factor lower limit value PF _min . Item 12. The system voltage suppression control method according to Item 9. The driving power factor control step includes a PI control step for generating a correction value based on a deviation between the power factor command value PF ^* and the power factor feedback signal, and a power factor command value PF to the correction value generated in the PI control step. ^* Power factor target value PF obtained by adding ^* PF ^* Coefficient for obtaining reactive power from _real

The system voltage suppression control according to any one of claims 8 to 10, further comprising: a coefficient generation step of generating a power factor command value PF ^* and adding a sign indicating a phase advance or delay to the coefficient according to the power factor command value PF ^*. Method. The update time of the reactive current target value output by the reactive current control step is set to a time when the absolute value of the reverse flow current _isp is the maximum value or a time close thereto every half cycle of the commercial system frequency. The system voltage suppression control method for a power conditioner according to any one of claims 8 to 11. The decrease suppression change amount Δy is obtained by a product of at least the difference ΔE _min between the voltage drop suppression settling value and the commercial grid voltage and the proportional gain Kp, and the proportional gain Kp is determined based on the difference ΔE _min. The increase suppression change amount Δy is obtained by the product of at least the difference ΔE _max between the voltage increase suppression settling value and the commercial system voltage and the proportional gain Kp, and the proportional gain Kp is the magnitude of the difference ΔE _min . The system voltage suppression control device according to any one of claims 8 to 12, wherein the system voltage suppression control device is configured so as to be changed in size based on the above. A driving power factor setting step for setting the driving power factor before grid connection operation is provided.
The system interconnection operation according to any one of claims 8 to 13, wherein the system interconnection operation is performed at the operation power factor set in the operation power factor setting step immediately after the system voltage suppression control is canceled during the system interconnection operation. System voltage suppression control method.   A power conditioner configured to incorporate the system voltage suppression control device according to claim 1.