JP5969059B2 - Power conditioner variable control device and control method for power conditioner - Google Patents

Description

  The present invention relates to a power factor variable control device and control method for 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. About.

  A distributed power source such as a solar cell or a fuel cell is provided with a power conditioner that converts frequency and voltage into AC power so as to be compatible with a power system in order to be used in conjunction with a commercial system.

  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.

  A ground fault or short-circuit accident occurs in a distribution line where the distributed power source is connected to the commercial system, or power transmission from the substation to the distribution line is stopped due to a planned power outage, etc. In such a case, it is necessary to reliably disconnect the distributed power source from the distribution line in order to prevent the influence on the operation of the section switch and to ensure the safety of the work of the distribution line.

  In order to detect an isolated operation state, a standard active isolated operation detection method (frequency feedback method with step injection) of a single-phase power conditioner for a distributed power source has been standardized (Japan Electric Industry Association JEM1498).

  In addition, when a distributed power source such as a solar power generation system becomes widespread, it becomes difficult to manage the voltage of the distribution line. In general, an electric power company uses a tap control device (SVR), STATCOM, or the like to manage the distribution line voltage so as to maintain an appropriate value. However, in recent years when distributed power sources have become widespread, it is required to variably control the power factor in order to manage the voltage of the distribution line closest to the power conditioner.

  However, when the power factor variable control and the active islanding detection method such as the frequency feedback method with step injection are used at the time of grid connection, there is a possibility that the accuracy of the islanding operation is lowered due to interference with each other. .

  In Patent Document 1, as an isolated operation detection device that can improve the power factor of an inverter circuit, an inverter circuit that injects an output current of reactive power between a distributed power source and a commercial system, and a high-frequency component from the output current are disclosed. Filter circuit for cutting, isolated operation detection circuit for detecting isolated operation based on frequency fluctuation of injected reactive power, reactive energy calculation unit for calculating reactive power corresponding to desired output current, and calculated reactive power In order to output a desired output current based on the amount, an isolated operation detection device including an output current control unit that drives and controls an inverter circuit has been proposed.

  The output current control unit includes a frequency measurement unit that measures a commercial system frequency, a voltage measurement unit that measures a commercial system voltage, a commercial system frequency measured by the frequency measurement unit, a voltage value measured by the voltage measurement unit, and An inflow current amount calculation means for calculating an inflow current amount flowing into the capacitor based on the capacitance of the capacitor, and the frequency measurement means measures the commercial system frequency at a period of 1/3 or less of the commercial system period. It is configured as follows.

  The isolated operation detection device detects the amount of inflow current flowing into the capacitor provided in the filter circuit from the output current of the inverter circuit, and flows into the reactive power amount corresponding to the desired output current amount output as the isolated operation detection device. The reactive power amount corresponding to the current amount is added, and the inverter circuit is driven and controlled based on the reactive power amount obtained as a result of the addition, so that a part of the output current of the inverter circuit flows into the capacitor. However, the power factor of the output current of the inverter circuit can be improved while outputting the desired output current as an isolated operation detection device.

  Patent Document 2 proposes a solar power generation apparatus that can maintain a power factor at a connection point with an AC power system at a predetermined value using one current detector. The solar power generation apparatus includes a DC / AC conversion unit that converts DC power generated by a solar cell into predetermined AC power, a reactor having one end connected to one side line of an output of the DC / AC conversion unit, and the reactor And a capacitor connected between the other end of the output and the other line of the output, a filter for making the output waveform a sine wave, and an output current of a DC / AC converter for connecting to an AC power system And a control unit that detects a detection signal of the current detector and a voltage of the capacitor to control the DC / AC conversion unit, and the control unit converts the detection signal of the current detector into a current. In addition to being used for feedback control, control is performed to predict the current flowing through the capacitor and maintain the power factor at the connection point with the AC power system at a predetermined value by a detection signal.

  In Patent Document 3, after increasing the reactive power to suppress the voltage rise, when the reactive power is further increased to change the reactive power in accordance with the deviation of the commercial system frequency, the apparent power increases, There has been proposed a control apparatus for a power conditioner that addresses the problem of increasing the load on the circuit and the like provided in the conditioner.

  The control device outputs the power conditioner in order to suppress the change in the first reactive power that is the fast reactive power or the slow reactive power to be output by the power conditioner according to the frequency deviation and the increase in voltage. The output of the power conditioner is controlled based on at least one of the change amount of the second reactive power, and the second reactive power is output when the voltage corresponding to the output voltage of the power conditioner is equal to or higher than the upper limit voltage. It is characterized by controlling the output of the power conditioner so that the active power output by the power conditioner is reduced when the phase advance reactive power output by the power conditioner is increased based on the amount of change. To do.

  Patent Document 4 discloses a control of a power conditioner that addresses the problem that the accuracy of isolated operation detection decreases due to interference between the reactive power control for detecting an isolated operation and the reactive power control for suppressing voltage rise. A device has been proposed.

  The control device outputs a power conditioner linked to the commercial system according to a frequency deviation indicating a difference between the latest moving average value of the commercial system cycle and the past moving average value from the latest moving average value. A first reactive power change amount deriving unit for deriving a change amount of the first reactive power that is power fast reactive power or slow phase reactive power, and suppresses an increase in voltage at the connection point between the power conditioner and the commercial system Therefore, a second reactive power change amount deriving unit for deriving a change amount of the second reactive power that is the phase reactive power to be output by the power conditioner, and a change amount of the first reactive power according to the change amount of the second reactive power And a control unit that controls the output of the power conditioner so as to prevent interference.

JP 2008-54395 A Japanese Patent Laid-Open No. 2002-354681 Japanese Patent Application Laid-Open No. 2014-207811 JP 2014-207808 A

  In the isolated operation detection device disclosed in Patent Document 1, since the update timing of the frequency measurement unit is every 5 ms, which is a cycle of 1/3 or less of the commercial system cycle, the response to the current flowing through the capacitor is not so good. There is a problem that the current flowing through the capacitor is estimated only by the capacitance, ignoring the internal resistance of the capacitor, and there is a problem that the estimated current is not so accurate, From the viewpoint, a power factor variable control device for a power conditioner capable of highly accurate power factor control has been desired.

  The solar power generation device disclosed in Patent Document 2 has the same problem, and further, when the output power fluctuates because the estimated current is added to the command value of the output current by the feed forward method instead of the feedback method. There was a problem that it was extremely difficult to maintain the power factor at a predetermined value.

  In the power conditioner control device described in Patent Documents 3 and 4, a complex control algorithm is used to avoid interference between the reactive power control for detecting an isolated operation and the reactive power control for suppressing voltage rise. There was a problem that the development man-hours and development costs were increased because it was necessary to employ them.

  In view of the above-described problems, the object of the present invention is to ensure that the power factor is reliably set to the target power factor without interfering with the active islanding detection method even when the active islanding detection method is employed. The object is to provide a power factor variable control device and control method for a power conditioner that can be stably controlled.

で求まるコンデンサ電流ｉ_ｃを減算することによりパワーコンディショナから商用系統電源に出力される逆潮流電流ｉ_ｓｐを推定する逆潮流電流推定部と、商用系統電圧ｅ_ｕｗの計測値から商用系統電圧ｅ_ｕｗの位相角度θ_ｕｗを出力する第１のＰＬＬ処理部と、前記逆潮流電流推定部で推定された逆潮流電流ｉ_ｓｐから逆潮流電流ｉ_ｓｐの位相角度θ_ｓｐを出力する第２のＰＬＬ処理部と、前記第１のＰＬＬ処理部及び第２のＰＬＬ処理部から出力される位相角度から得られる商用系統電圧ｅ_ｕｗと逆潮流電流ｉ_ｓｐの位相差Δφ（θ_ｕｗ−θ_ｓｐ）に基づいて、力率帰還信号及び無効電流帰還信号を生成する帰還信号生成部と、前記力率帰還信号に基づいて逆潮流電力の力率が力率指令値に収束するように目標力率を生成する力率制御部と、前記力率制御部で生成された目標力率と前記無効電流帰還信号に基づいて前記インバータを制御するインバータ制御部に無効電流目標値を出力する無効電流制御部と、を備えている点にある。 In order to achieve the above-mentioned object, the first characteristic configuration of the power factor variable control device for a power conditioner according to the present invention is that, as described in claim 1 of the claims, the DC generated power is changed to AC power. A power factor variable control device for a power conditioner comprising an inverter that converts and interconnects with a commercial system, and an LC filter that removes harmonic components from the output of the inverter, the commercial system voltage e _uw , From the measured value of the inverter output current i _inv as the capacitor current i _c , the capacitor capacitance C _f , and the internal resistance R _c

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 feedback signal generation unit that generates the power factor feedback signal and the reactive current feedback signal, and generates the target power factor so that the power factor of the reverse power flow converges to the power factor command value based on the power factor feedback signal. Power factor to do 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. A reactive current target value is generated by the reactive current control unit based on the target power factor generated by the power factor control unit and the reactive current feedback signal, and a desired reverse flow current _isp is appropriately output from the inverter. .

を生成し、力率指令値に従って当該係数に進相または遅相を示す符号を付加する係数生成部を備えて構成されている点にある。 In the second feature configuration, as described in claim 2, in addition to the first feature configuration described above, the power factor controller corrects based on a deviation between the power factor command value and the power factor feedback signal. A PI control unit for generating a value, and a coefficient for obtaining reactive power from a power factor target value PF ^* _real obtained by adding a power factor command value to the correction value generated by the PI control unit

And a coefficient generation unit that adds a sign indicating phase advance or delay to the coefficient according to the power factor command value.

A correction value is calculated by the PI control unit so that the power factor feedback signal converges to the power factor command value from the deviation between the power factor feedback signal output from the feedback signal generation unit and a preset power factor command value. A power factor target value PF ^* _real obtained by adding the power factor command value 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 indicates the slow reactive current, and the sign “−1” is added when the power factor command value indicates the fast reactive current.

  In addition to the first or second feature configuration described above, the third feature configuration is invalid according to the frequency deviation within a predetermined time obtained from the measured value of the commercial system frequency. Reactive power injection amount calculation unit for calculating the power injection amount, and whether or not a single operation state based on the commercial system frequency, the operating frequency and the harmonic voltage effective value when the reactive power of the reactive power injection amount is injected An independent operation detecting unit that detects the reactive power injection amount calculated by the reactive power injection amount calculating unit to the target power factor generated by the power factor control unit. The reactive current target value is output to the inverter based on the reflected final target power factor and the reactive current feedback signal.

  The reactive current target value output from the reactive current control unit is generated based on the final target power factor and the reactive current feedback signal and output to the inverter. The final target power factor is a value in which the reactive power injection amount calculated by the reactive power injection amount calculation unit is reflected in the target power factor generated by the power factor control unit. The voltage can be appropriately controlled.

Further, the power factor variable control unit and to reduce the degree interference with step injection with frequency feedback function, the PI control block reactive current controller proportional gain K _p is a proportional gain K of the PI control block power factor variable control unit _It was designed by X times _p , and the integrator time constant T _i was designed by 1 / X. By designing in this manner, the transient response speed of the reactive current control unit is X times faster than the power factor control unit, and the convergence time to the steady state is also 1 / X. In this embodiment, X is designed with a value of 10 or more.

  In the fourth feature configuration, as described in claim 3, in addition to the third feature configuration described above, the reactive power injection amount calculation unit has a subsequent frequency deviation according to a frequency deviation at a certain time point. A frequency-corresponding reactive power injection amount calculation unit that calculates the reactive power injection amount from the frequency deviation / reactive power injection amount characteristic table in which the reactive power injection amount is set to be gradually increased, and the frequency deviation at a certain point is basically unchanged. And a step reactive power injection amount calculating unit that calculates a constant amount of reactive power injection in a constant direction when the wave voltage and / or the harmonic voltage fluctuates.

  Even when a large number of distributed power sources are connected to commercial power sources, the reactive power of the same tendency is injected from each distributed power source by the step reactive power injection amount calculation unit. In addition to avoiding inconvenient situations where the reactive power injected from the system is canceled out, unnecessary detection can be avoided without providing a separate complicated detection algorithm. Whether or not there is can be detected.

The fifth 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 first to fourth feature configurations described above, as described in claim 5. 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 sixth feature configuration, as described in claim 6, in addition to any of the first to fifth feature configurations described above, when the output power deviates from a predetermined allowable range with respect to the rated power, An output limiting unit that limits the reactive current target value output by the reactive current control unit is provided.

  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 cope with this problem, if the active power is adjusted so as to decrease, the stability of the 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 power factor can be stably controlled while suppressing the apparent power to the rated value. become.

で求まるコンデンサ電流ｉ_ｃを減算することによりパワーコンディショナから商用系統電源に出力される逆潮流電流ｉ_ｓｐを推定する逆潮流電流推定ステップと、系統電圧ｅ_ｕｗの計測値から商用系統電圧ｅ_ｕｗの位相角度θ_ｕｗを出力する第１のＰＬＬ処理ステップと、前記逆潮流電流推定ステップで推定された逆潮流電流ｉ_ｓｐから逆潮流電流ｉ_ｓｐの位相角度θ_ｓｐを出力する第２のＰＬＬ処理ステップと、前記第１のＰＬＬ処理ステップ及び第２のＰＬＬ処理ステップから出力される位相角度から得られる商用系統電圧ｅ_ｕｗと逆潮流電流ｉ_ｓｐの位相差Δφ（θ_ｕｗ−θ_ｓｐ）に基づいて、力率帰還信号及び無効電流帰還信号を生成する帰還信号生成ステップと、前記力率帰還信号に基づいて逆潮流電力の力率が力率指令値に収束するように目標力率を生成する力率制御ステップと、前記力率制御ステップで生成された目標力率と前記無効電流帰還信号に基づいて前記インバータを制御するインバータ制御部に無効電流目標値を出力する無効電流制御ステップと、を備えている点にある。 The first characteristic configuration of the power conditioner variable control method of the power conditioner according to the present invention is as described in claim 7, wherein an inverter connected to a commercial system by converting DC generated power into AC power, and the inverter Is a power conditioner variable control method for a power conditioner having an LC filter that removes harmonic components from the output of the power supply, and includes 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

A reverse flow current estimation step of estimating a reverse flow current i _sp output from the power conditioner to a commercial system power source by subtracting the capacitor current i _c which is obtained by, the grid voltage e _uw from the measured value of the system voltage e _uw The first PLL processing step for outputting the phase angle θ _uw of the current and the second PLL processing for outputting the 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 And a 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. A feedback signal generation step for generating a power factor feedback signal and a reactive current feedback signal, and the power factor of the reverse power flow based on the power factor feedback signal is a power factor command value A power factor control step for generating a target power factor so as to converge, and a reactive current target value in an inverter control unit that controls the inverter based on the target power factor generated in the power factor control step and the reactive current feedback signal And a reactive current control step for outputting.

を生成し、力率指令値に従って当該係数に進相または遅相を示す符号を付加する係数生成ステップを備えて構成されている点にある。 In the second feature configuration, as described in claim 8, in addition to the first feature configuration described above, the power factor control step is corrected based on a deviation between a power factor command value and a power factor feedback signal. PI control step for generating a value, and a coefficient for obtaining reactive power from a power factor target value PF ^* _real obtained by adding a power factor command value to the correction value generated in the PI control step

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

  The third feature configuration is invalid according to the frequency deviation within a predetermined time obtained from the measured value of the commercial system frequency in addition to the first or second feature configuration described above, as described in claim 9. Reactive power injection amount calculating step for calculating the power injection amount, and whether or not it is in the single operation state based on the commercial system frequency, the operating frequency, and the harmonic voltage effective value when the reactive power of the reactive power injection amount is injected An independent operation detecting step for detecting the reactive power injection, wherein the reactive current control step adds the reactive power injection amount calculated in the reactive power injection amount calculation step to the target power factor generated in the power factor control step. The reactive current target value is output to the inverter based on the reflected final target power factor and the reactive current feedback signal.

  In the fourth feature configuration, as described in claim 10, in addition to the third feature configuration described above, the reactive power injection amount calculating step has a subsequent frequency deviation according to a frequency deviation at a certain time point. Reactive power injection amount calculation step that calculates the reactive power injection amount from the frequency deviation / reactive power injection amount characteristic table in which the reactive power injection amount is set to gradually increase, and the frequency deviation at a certain point is basically unchanged. And a reactive power injection amount calculating step for calculating a constant amount of reactive power injection in a constant direction when the wave voltage and / or the harmonic voltage fluctuate.

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 one of the first to fourth feature configurations described above. 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, as described in claim 12, in addition to any of the first to fifth feature configurations described above, when the output power deviates from a predetermined allowable range with respect to the rated power, An output limiting step of limiting the reactive current target value output by the reactive current control step is provided.

  As described above, according to the present invention, even when the active islanding detection method is adopted, the power factor is reliably stabilized at the target power factor without interfering with the method and regardless of the state of the output power. It is now possible to provide a power factor variable control device and control method for a power conditioner that can be controlled.

Circuit block diagram of a distributed power source to which an isolated operation detection device according to the present invention is applied Functional block diagram of an isolated operation detection 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 Operation explanatory diagram of system frequency measurement unit (A) is explanatory drawing of the frequency deviation and reactive power injection amount characteristic table used in a frequency corresponding reactive power injection amount calculation part, (b) is operation | movement explanatory drawing of a step reactive power injection amount calculation part. (A) is an explanatory diagram at the time of instantaneous drop and sudden phase change, (b) is a characteristic explanatory diagram of the operating frequency f _PLL and the commercial system frequency f _grid at the time of single operation. (A) is a sequence diagram of the operation frequency _{f PLL} and the grid frequency _{f grid,} (b) the sequence diagram of the harmonic effective voltage THD _v Explanatory diagram of experimental results

Hereinafter, a power factor variable control device and a control method for a power conditioner 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. The solar battery power generation apparatus 100 is configured to include a solar battery panel SP and a power conditioner PC to which the solar battery panel SP is connected, and is connected to a commercial power supply e _grid via a connection relay (not shown). . 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, S4 provided in the inverter 3 are turned on / off by PWM control executed by a control block including the variable power factor control device 10 so that the frequency and voltage are adapted to be linked to the commercial 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 system impedances, e _uw is the line voltage of u−w, i _sp Is a reverse flow current and R _uw is an AC load.

FIG. 2 shows a functional block configuration of the power factor variable control apparatus 10 configured with a microcomputer, a memory, a peripheral circuit, and the like. In this embodiment, the power factor variable control unit 10 also functions as alone operation detecting apparatus, based on a control program or the like which includes a power factor variable control algorithm according to the present invention with corresponding step infusion with frequency feedback scheme intended The power factor variable control method is configured to be executed.

  The variable power factor control device 10 is composed of five main blocks: a power factor control block A, a DC bus voltage constant control block B, a reactive current control block C, an inverter output current control block D, and an isolated operation detection block E. ing.

  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 control unit 21, PWM control unit 22, commercial system frequency measurement unit 23, isolated operation Each functional block includes a detection unit 24, a reactive power injection amount calculation unit 25, and the like.

  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, and the power factor control unit 15 constitute a power factor control block A, and the DC voltage control unit 17 The DC bus voltage constant control block B is configured, the reactive current control unit 16 includes the reactive current control block C, and the reactive power generation unit 19, the active power generation unit 20, the inverter control unit 21, and the PWM control unit 22 perform the inverter. Output current control block D is configured, and an independent operation detection block E is configured by the commercial system frequency measurement unit 23, the isolated operation detection unit 24, and the reactive power injection amount calculation unit 25.

The reverse flow current estimation unit 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 transformer 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 . In addition, as shown in the following [ _Equation 6], P _uw is the active power, and E _{uw · max} is the maximum value of the voltage.

As shown in FIG. 4A, the power factor control unit 15 includes a PI control unit 15A that generates a correction value based on a deviation between the power factor command value PF ^* and the power factor feedback signal PF, and a PI control unit 15A. 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 generated correction value is generated based on the following [Equation 7], and the power factor command value PF ^{According to *,} a coefficient generation unit for adding a code indicating a leading phase or a lagging phase to the coefficient is provided. 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 commercial system frequency measurement unit 23 includes a zero-cross detection circuit including a binarization circuit that binarizes the AC voltage signal divided by the resistance voltage divider circuit.

As shown in FIG. 5 (a), a commercial system voltage waveform obtained by resistance-dividing the commercial system voltage e _uw (indicated by a broken line in the figure) is converted into a binary value by a binarization circuit with a voltage value of zero as a threshold value. A square wave (indicated by a solid line in the figure) having a duty ratio of 50% corresponding to the commercial system frequency is obtained by converting into values.

Counting the time difference between the intermediate value of the falling edge and rising edge of the square wave and the intermediate value of the next falling edge and rising edge with a sampling frequency of 2.5 MHz (accuracy of 0.4 μs.) Thus, the commercial system frequency f _grid corresponding to the commercial system voltage e _uw is measured. The sampling frequency is an example, and is not limited to this value.

Returning to FIG. 2, the reactive power injection amount calculation unit 25 includes a frequency-corresponding reactive power injection amount calculation unit 25A and a step reactive power injection amount calculation unit 25B, and is invalidated from the frequency-corresponding reactive power injection amount calculation unit 25A. It is output power injection quantity _{K fvar,} reactive power injection quantity _{K step} from step reactive power injection amount calculating section 25B is output.

The isolated operation detection unit 24 is operated in the isolated operation state based on the commercial system frequency, the operation frequency, and the harmonic voltage effective value when the reactive power injection amount calculated by the reactive power injection amount calculation unit 25 is injected. This block detects whether or not there is. The isolated operation detection unit 24 receives the operation frequency f _PLL corresponding to the commercial system voltage e _uw obtained by the first PLL processing unit 12 and the system frequency f _grid measured by the commercial system frequency measurement unit 23. ing.

The reactive current control unit 16 reflects the reactive power injection amount K _fvar and K _step calculated by the reactive power injection amount calculation unit 25 in the target power factor PF _out generated by the power factor control unit 15, that is, the final target power factor, that is, This block outputs a reactive current target value to the inverter control unit 21 that controls the inverter 3 based on the total reactive power injection amount _KQ and the reactive current feedback signal _Iq .

Specifically, the product of the total reactive power injection amount K _Q 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 ^{* This} block performs PI calculation of the control amount so as to converge to _q .

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 block that generates a 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 the DC link voltage V _dc input from the DC / DC converter 1 to the DC voltage command value V ^* _dc and outputs the phase angle θ corresponding to the commercial system. The sine wave of _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 cope with this problem, if the active power is adjusted so as to decrease, the stability of the 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 18A that performs PI control so that the feedback value S _uw of the apparent power converges to the apparent power command value S ^* _uw. , Switch SW and adder. 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. is, when the feedback value S _uw apparent power deviates from the range of ± [Delta] x% of the rated power S _PU, the output contact of the switch SW is switched to 0 Ru is limited to I _lim clogging 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 preferable to update in the range of | i _sp | ≧ 0.95I _spmax .

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 while detecting the isolated operation.

Below, it supplements about the reactive power injection amount calculation part 25. FIG.
The frequency-corresponding reactive power injection amount calculation unit 25a is a block that calculates the reactive power injection amount according to the frequency deviation Δf _grid obtained based on the commercial system frequency f _grid measured by the commercial system frequency measurement unit 23. The reactive power injection amount K _fvar is calculated from the frequency deviation / reactive power injection amount characteristic table in which the reactive power injection amount is determined so that the subsequent frequency deviation gradually increases in accordance with the frequency deviation Δf _grid .

As shown in FIG. 5 (c), the commercial grid frequency f _grid is updated every cycle, and 5 ms. The latest 40 ms. The moving average is calculated and stored in the storage unit. As shown in FIG. 5B, 200 ms. Previous 80ms. 40ms from the moving average of the minute. The frequency deviation Δf _grid is calculated by subtracting the moving average between them.

FIG. 6A shows frequency deviation / reactive power characteristics. The frequency-corresponding reactive power injection amount calculation unit 20 calculates the reactive power injection amount K _fvar based on the frequency deviation / reactive power characteristics, and the reactive power calculated within half a cycle of the commercial system frequency f _grid from the calculation of the frequency deviation Δf _grid. An injection amount K _fvar is injected.

In the frequency deviation / reactive power characteristic, a reactive power injection amount K _fvar having different _slopes is defined in a low-sensitive band region where the frequency deviation Δf _grid is within ± 0.01 Hz and a high-sensitive band region on both outer sides thereof. In any case, the reactive power injection amount K _fvar in the direction of increasing the frequency deviation is defined, and the slope of the second-stage gain in the high-sensitive area is higher than the inclination of the first-stage gain in the low-sensitive area where the frequency deviation Δf _grid is. It is set to be large. The maximum value is ± 0.25 p. u. (Per unit). In addition, the frequency deviation / reactive power characteristic is an example, and is not limited to this characteristic.

The step reactive power injection amount calculation unit 25b has a constant amount of reactive power injection in a constant direction when the fundamental wave voltage E _uw and / or the harmonic voltage THD _v fluctuate without any change in the frequency deviation Δf _grid at a certain time. _This is a block for calculating the quantity K _fstep . In this specification, the “state in which there is no fluctuation in the frequency deviation” is used as a concept including a state in which the fluctuation is small, that is, a state in the above-described low-sensitive band region.

As shown in FIG. 6B, the step reactive power injection amount calculation unit 21 determines that the harmonic voltage fluctuation satisfies all the following conditional expressions when the frequency deviation Δf _grid is in the low-sensitive band region. Within a half cycle, the upper limit is 0.1 p. u. The reactive power is injected in the direction of delaying the current phase when viewed from the power conditioner PC, that is, in the direction of decreasing the frequency.

THD _v (z) -THD _avr > 2V
THD _v (z-1) -THD _avr > 2V
THD _v (z-2) -THD _avr > −0.5 V
│THD _v (z-3) -THD _avr (z) │ <0.5V
│THD _v (z-4) -THD _avr (z) │ <0.5V
│THD _v (z-5) -THD _avr (z) │ <0.5V

As shown in the following [Equation 8], in this embodiment, the total harmonic voltage effective value from the second order to the seventh order is adopted as a preferable aspect as the harmonic voltage effective value THD _v . Harmonics may be included. In the following description, it is simply expressed as a harmonic voltage. Further, T _ADC in [Equation 8] is a sampling time of the A / D converter, and n is a harmonic order.

Further, when the step reactive power injection amount calculation unit 25b determines that the fundamental voltage fluctuation satisfies all the following conditional expressions when the frequency deviation Δf _grid is in the low-sensitive band region, the step reactive power injection amount calculation unit 25b performs 3 The upper limit is 0.1 p. u. The reactive power is injected in the direction of delaying the current phase when viewed from the power conditioner PC, that is, in the direction of decreasing the frequency.

E _u.rms (z) −E _uw.rms.avr (z)> 2.5V
E _u.rms (z-1) −E _u.rms.avr (z)> 2.5V
E _uw.rms (z-2) −E _uw.rms.avr (z)> − 0.5V
│E _u.rms (z-3) -E _uw.rms.avr (z) | <0.5V
│E _u.rms (z-4) -E _uw.rms.avr (z) | <0.5V
│E _u.rms (z-5) -E _uw.rms.avr (z) | <0.5V

First PLL processing section 12 is a block for generating a reference system voltage signal synchronized with the phase angle theta _uw commercial system voltage e _uw is inputted commercial system voltage e _uw, the second PLL unit 13 backward flow is a block current i _sp generates a reference reverse flow current signal synchronized with a phase angle theta _sp of backward flow current i _sp is inputted.

  In the present embodiment, the gain G1 of the first PLL processing unit 12 is set to a larger value than the gain G2 of the second PLL processing unit 13. Specifically, G2 = 0.5G1 is set, and it is preferable that at least G2 ≦ 0.5G1.

The operation of the isolated operation detection unit 24 will be described in detail. In general, when the system voltage e _uw is normal (202 ± 10V), if the system frequency _fgrid changes suddenly, it can be correctly detected that it is in a single operation state. When a phenomenon occurs in which the voltage decreases instantaneously, the input voltage decreases and the phase shifts.

FIG. 7A shows an example of a waveform at the time of a sag. An instantaneous drop occurs when the commercial system voltage e _uw is at a phase angle of 90 °, and the frequency drops to the system frequency f _grid (z-4) and the operating frequency f _PLL (z-4) at the moment when the phase angle is shifted by + 41 ° at the maximum. Is expressed. Due to the large fluctuation of the frequency, there is a possibility that unnecessary detection may be made if the vehicle is in an isolated operation state.

However, when the phase suddenly changes due to a momentary drop or the like, the commercial system frequency _fgrid fluctuates instantaneously at the time of the sudden change, but is stable before and after that, whereas it is stable before and after the single operation. Fluctuation tends to increase.

That is, as shown in FIG. 7B, the isolated operation detection unit 24 has both the operation frequency f _PLL calculated by the first PLL processing unit 12 and the commercial system frequency f _grid measured by the system frequency measurement unit 11. If it changes to one direction at a plurality of continuous system cycles, it is sufficient to determine that it is in an isolated operation state, and it becomes possible to accurately detect the isolated operation state while avoiding unnecessary detection.

As shown in FIG. 7B, both values may gradually increase, and conversely, both values may gradually decrease. On the other hand, when the phase changes suddenly as shown in FIG. 7A, the operating frequency f _PLL calculated by the first PLL processing unit 12 and the commercial system frequency measured by the commercial system frequency measuring unit 23 are used. Since both _fgrid temporarily rises or falls only in the cycle at the time of sudden change and then returns to the steady state, unnecessary detection can be avoided by determining the tendency, and the isolated operation state can be detected accurately and quickly. .

It is more preferable that the _islanding operation detection unit 24 is configured to detect that it is in the islanding operation state when the harmonic voltage fluctuation rate of the commercial system voltage e _uw exceeds a predetermined ratio and the state continues for a predetermined time. .

  When reactive power is injected into the commercial power supply, even if the harmonic component of the commercial power supply fluctuates due to some reason, the harmonic voltage effective value calculated in the commercial system cycle before and after that does not fluctuate significantly. On the other hand, when the power supply from the commercial system power supply is stopped and the single operation state is entered, the harmonic voltage effective value calculated in the subsequent continuous cycle greatly fluctuates. Therefore, if the state in which the harmonic voltage fluctuation rate of the commercial system power supply exceeds a predetermined ratio continues for a predetermined time, it is possible to avoid unnecessary detection by detecting that it is in a single operation state.

Specifically, in the present embodiment, the isolated operation detection unit 24 is based on both the current value of the commercial system frequency _fgrid and the operating frequency _fPLL , the value before one commercial system cycle, and the value before two commercial system cycles. Is determined to change in one direction with a plurality of continuous commercial system cycles, and when the harmonic voltage fluctuation rate ΔTHD of the commercial system voltage e _uw exceeds a predetermined ratio and the state continues for a predetermined time It is configured to detect a state and to determine that the state is normal in order to avoid unnecessary detection when either one is not satisfied.

Specifically, as shown in [Equation 9] below, the current value (z) and the previous value (z-1) with respect to the average value of the operating frequency f _PLL and commercial system frequency f _grid 32 cycles before If the product Δf _var (total frequency fluctuation value) of the deviation from the previous value (z−2) is equal to or greater than a predetermined threshold value f _cst , it is in an isolated operation state, and if it is less than the threshold value f _cst , it is normal. It can be judged.

Here, the threshold f _cst is preferably set to a value in the range of 4 to 9% of the fundamental frequency. For example, if the commercial system frequency is 50 Hz, f _cst is set to a range of 2.0 to 4.5. It is preferable to do.

In this embodiment, as shown in FIG. 8 (a), the average value of the operating frequency f _PLL and the commercial system frequency f _grid before 32 cycles is used as an average value for each commercial system for the previous 32 cycles based on the previous 32 cycles. Although the average value of the frequencies is adopted, the number of cycles for obtaining the average value need not be limited to 32 and can be set as appropriate.

Further, as shown in FIG. 8 (b), the harmonic voltage fluctuation rate ΔTHD is an average value of the harmonic voltage effective value THD _v 32 cycles before, and each harmonic voltage of the previous 32 cycles based on 32 cycles before. An average value of the effective values THD _v is adopted and is calculated by the following [Equation 10]. Similarly, the number of cycles for obtaining the average value need not be limited to 32 and can be set as appropriate.

で求まるコンデンサ電流ｉ_ｃを減算することによりパワーコンディショナから商用系統電源に出力される逆潮流電流ｉ_ｓｐを推定する逆潮流電流推定ステップと、商用系統電圧ｅ_ｕｗの計測値から商用系統電圧ｅ_ｕｗの位相角度θ_ｕｗを出力する第１のＰＬＬ処理ステップと、逆潮流電流推定ステップで推定された逆潮流電流ｉ_ｓｐから逆潮流電流ｉ_ｓｐの位相角度θ_ｓｐを出力する第２のＰＬＬ処理ステップと、第１のＰＬＬ処理ステップ及び第２のＰＬＬ処理ステップから出力される位相角度から得られる商用系統電圧ｅ_ｕｗと逆潮流電流ｉ_ｓｐの位相差Δφ（θ_ｕｗ−θ_ｓｐ）に基づいて、力率帰還信号及び無効電流帰還信号を生成する帰還信号生成ステップと、力率帰還信号に基づいて逆潮流電力の力率が力率指令値に収束するように目標力率を生成する力率制御ステップと、力率制御ステップで生成された目標力率と無効電流帰還信号に基づいてインバータを制御するインバータ制御部に無効電流目標値を出力する無効電流制御ステップと、備えているパワーコンディショナの力率可変制御方法が実行される。 The power factor variable control method according to the present invention is executed by the power factor variable control apparatus 10 described above.
That is, 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

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 processing for outputting the phase angle theta _sp of backward flow current _{i sp} from reverse flow current _{i sp} estimated by the backward flow current estimation step And 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 first PLL processing step and the second PLL processing step. A feedback signal generation step for generating a power factor feedback signal and a reactive current feedback signal, and a power factor of reverse power flow converges to a power factor command value based on the power factor feedback signal. Power factor control step for generating the target power factor, and reactive current for outputting the reactive current target value to the inverter control unit for controlling the inverter based on the target power factor generated in the power factor control step and the reactive current feedback signal The control step and the power factor variable control method of the power conditioner provided are executed.

  In the above-described embodiment, the configuration in which the variable power factor control device includes the reactive power injection unit and the single operation detection unit that execute the active islanding detection method has been described. It goes without saying that the present invention can be adopted even in a configuration that does not include an operation detection method.

  Each of the above-described embodiments is merely an example of a power factor variable control device and a control direction of 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.

  Below, the result of having performed a comparative experiment about the power conditioner incorporating the power factor variable control device according to the present invention having the power factor control unit described above and the power conditioner not having the power factor control unit will be described. .

The power factor was measured when the power factor command value PF ^* during commercial grid connection operation was set to 0.9 and the input power was changed from condition 1 to 3.
9A and 9B show experimental results of the actual power factor PF, active power P _uw , reactive power Q _uw, and apparent power S _uw at that time. FIG. 9A shows the experimental results when the power factor control unit is not provided, and FIG. 9B shows the experimental results when the power factor control unit is provided. From these, it was confirmed that by introducing the power factor variable control device according to the present invention, the power factor is controlled to be constant even if the input power changes.

9C and 9D show experimental results of the power factor command value PF ^* , the actual measurement value PF, and the error value ΔPF with respect to the input power under condition 3. FIG. 9C shows the experimental result of the advanced power, and FIG. 9D shows the experimental result of the delayed power. From these, it became clear that all error values ΔPF are ± 0.5% or less in the steady state.

1: DC / DC converter 3: inverter 4: LC filter 10: variable power factor 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 24: Isolated operation detection unit 25: Reactive power injection amount calculation 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 bridge

Claims (12)

A power factor variable control device for a power conditioner comprising an inverter connected to a commercial system by converting DC generated power into AC power, and an LC filter for removing 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 power factor control unit that generates a target power factor so that the power factor of the reverse power flow converges to a power factor command value based on the power factor feedback signal;
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;
A power factor variable control device of a power conditioner equipped with The power factor control unit adds a power factor command value to the PI control unit that generates a correction value based on a deviation between the power factor command value and the power factor feedback signal, and the correction value generated by the PI control unit. Coefficient for finding reactive power from the obtained power factor target value PF ^* _real

The power factor variable control device for a power conditioner according to claim 1, further comprising: a coefficient generation unit that generates a power factor command value and adds a sign indicating phase advance or delay to the coefficient according to the power factor command value. A reactive power injection amount calculating unit that calculates a reactive power injection amount according to a frequency deviation within a predetermined time obtained from a measurement value of a commercial system frequency;
A single operation detection unit that detects whether or not a single operation state based on the commercial system frequency, the operation frequency, and the harmonic voltage effective value when the reactive power of the reactive power injection amount is injected,
The reactive current control unit is based on a final target power factor that reflects the reactive power injection amount calculated by the reactive power injection amount calculation unit in the target power factor generated by the power factor control unit and the reactive current feedback signal. The power factor variable control device for a power conditioner according to claim 1 or 2, wherein a reactive current target value is output to the inverter.   The reactive power injection amount calculation unit calculates a reactive power injection amount from a frequency deviation / reactive power injection amount characteristic table in which a reactive power injection amount is determined so that a subsequent frequency deviation gradually increases according to a frequency deviation at a certain time. Reactive power injection amount calculation unit for frequency to be calculated and a constant amount of reactive power injection in a constant direction when the fundamental voltage and / or harmonic voltage fluctuates without fluctuation at a certain time. The power factor variable control device for a power conditioner according to claim 3, further comprising: a step reactive power injection amount calculation unit that performs the step. 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 power of the power conditioner as claimed in claim 1, which is configured to vary timing near to one of the fourth absolute value maximum value of the reactive component is reverse flow current i _sp of the measured reverse flow current i _sp Variable rate control device.   The output limiting part which limits the reactive current target value output by the said reactive current control part if output electric power deviates from the predetermined | prescribed allowable range with respect to rated power is provided in any one of Claim 1 to 5 Power factor variable control device for power conditioner. A power factor variable control method for a power conditioner comprising an inverter connected to a commercial system by converting DC generated power into AC power, and an LC filter for removing 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 power factor control step of generating a target power factor so that the power factor of the reverse power flow converges to a power factor command value based on the power factor feedback signal;
A reactive current control step of outputting a reactive current target value to an inverter control unit that controls the inverter based on the target power factor generated in the power factor control step and the reactive current feedback signal;
A power factor variable control method for a power conditioner equipped with The power factor control step includes a PI control step for generating a correction value based on a deviation between the power factor command value and the power factor feedback signal, and adding the power factor command value to the correction value generated in the PI control step. Coefficient for finding reactive power from the obtained power factor target value PF ^* _real

The power factor variable control method for a power conditioner according to claim 7, further comprising: a coefficient generation step for generating a power factor and adding a sign indicating a phase advance or delay to the coefficient according to the power factor command value. A reactive power injection amount calculating step of calculating a reactive power injection amount according to a frequency deviation within a predetermined time obtained from a measurement value of a commercial system frequency;
The reactive current control step is based on the final target power factor reflecting the reactive power injection amount calculated in the reactive power injection amount calculating step and the reactive current feedback signal in the target power factor generated in the power factor control step. The power factor variable control method for a power conditioner according to claim 7 or 8, wherein a reactive current target value is output to the inverter.   The reactive power injection amount calculating step calculates a reactive power injection amount from a frequency deviation / reactive power injection amount characteristic table in which a reactive power injection amount is determined so that a subsequent frequency deviation gradually increases according to a frequency deviation at a certain time. Reactive power injection amount calculation step for frequency to be calculated, and when the fundamental wave voltage and / or harmonic voltage fluctuate with no fluctuation in frequency deviation at a certain time, calculate a constant amount of reactive power injection amount with a constant current phase The power factor variable control method for a power conditioner according to claim 9, further comprising: a step of calculating a reactive power injection amount calculating step. 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 power factor variable control method for a power conditioner according to any one of claims 7 to 10. The output limiting step of limiting the reactive current target value output by the reactive current control step when the output power deviates from a predetermined allowable range with respect to the rated power. The power factor variable control method of the inverter.

Images