JP2019041480A - Controller of power converter, control method, and control program - Google Patents

Abstract

To provide a controller of a power converter, a control method, and a control program for improving accuracy of detection of an isolated operation in an isolated system.SOLUTION: A control unit 22 (controller) of a power converter 33 suppresses fluctuation of a system frequency of a power system 1, and has: a frequency fluctuation suppression unit 24 which calculates frequency deviation between the measured system frequency of the power system 1 and a reference frequency, and calculates an effective current command or an effective power command for suppressing fluctuation of the system frequency by using the frequency deviation; and a current control unit 26 which controls the power converter 33 according to the effective current command or the effective power command to output effective current or effective power from the power converter 33 to a lower-order system 3, in which the frequency fluctuation suppression unit 24 has a frequency deviation holding unit 304 which holds the frequency deviation calculated immediately before change speed of the frequency deviation exceeds predetermined change speed when the change speed of the frequency deviation exceeds the predetermined change speed.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a control device, a control method, and a control program for controlling a power converter.

  Lower power system (for example, substation facilities) in which multiple distributed power sources (for example, solar power generation facilities, wind power generation facilities, storage battery facilities, fuel cell power generation facilities, gas turbine engine power generation facilities, induction power generation facilities, etc.) are connected The power system that supplies power to the customer (power receiving equipment) via the distribution line: the subordinate system, the system fault (ground fault / short circuit accident) or system power outage (work / planned power outage), etc. It is separated from an electric power system (for example, an electric power system that supplies electric power from a synchronous power generation facility such as a thermal power generation facility to a substation facility via a transmission line: an upper system) and becomes a single system.

  When a single system is formed, the distributed power source detects that it has become a single system within a specified time, stops power supply to the single system to which it is connected, and then disengages itself from the single system. Line up.

  However, it is assumed that the distributed power source cannot be disconnected from the single system and the single operation is continued. For example, a storage battery facility including a power converter and a storage battery is equipped with a single operation detection unit that detects that it is a single operation within a predetermined time and a frequency fluctuation suppression unit that suppresses fluctuations in the system frequency of the power system. If it is, the storage battery facility cannot be disconnected from the single system, and there is a risk of continuing the single operation. That is, there is a possibility that the state where the storage battery facility that continues the single operation pressurizes the single system continues.

  The islanding operation detection unit detects islanding by using the difference between the fluctuation of the system frequency before being separated from the upper system and the fluctuation of the system frequency after being separated from the upper system. In other words, since the distributed power source such as induction power generation equipment is connected to the single system separated from the upper system in addition to the storage battery equipment, the system frequency fluctuates more rapidly than before the separation from the upper system. An isolated operation is detected by detecting a rapid fluctuation in the system frequency.

  On the other hand, the frequency fluctuation suppression unit assists synchronous power generation equipment such as thermal power generation equipment because fluctuations in the system frequency increase due to the influence of the distributed power supply when a large number of distributed power supplies are connected to the power system. For this purpose, the increase in fluctuations in the system frequency is suppressed using the electrical energy stored in the storage battery of the storage battery facility. However, since the frequency fluctuation suppressing unit suppresses the fluctuation of the system frequency of the single system even for the single system, it is assumed that the single operation detecting unit cannot detect the single operation. That is, the accuracy of isolated operation detection is reduced in a single system.

  In Patent Documents 1, 2, and 3, the reactive power control for detecting the isolated operation and the reactive power control for suppressing the voltage rise interfere with each other, and the control that suppresses the decrease in the accuracy of the isolated operation detection. An apparatus is disclosed.

JP-A-2015-180123 JP, 2015-180122, A JP 2014-207808 A

  However, the above-described control device is configured so that when the single battery detection unit and the frequency fluctuation suppression unit are mounted on the storage battery facility, the frequency fluctuation suppression unit suppresses an increase in system frequency fluctuation in the single system, thereby allowing the single operation. This does not prevent the detection unit from becoming unable to detect an isolated operation.

  An object of one aspect of the present invention is to provide a power converter control device, a control method, and a control program that improve the accuracy of single operation detection in a single system.

  A control device for a power converter that suppresses fluctuations in the system frequency of a power system that is one form according to the present invention calculates a frequency deviation between the measured system frequency of the power system and a reference frequency, and uses the frequency deviation. Frequency fluctuation suppression unit that calculates active current command or active power command for suppressing fluctuation of system frequency, and power converter is controlled according to active current command or active power command, and it is effective from power converter to power system A current control unit that outputs current or active power. The frequency variation suppression unit includes a frequency deviation holding unit that holds a frequency deviation calculated immediately before the frequency deviation change rate exceeds the predetermined change rate when the frequency deviation change rate exceeds the predetermined change rate.

  Further, the control device for the power converter that suppresses the fluctuation of the system frequency of the power system according to another embodiment of the present invention calculates the frequency deviation between the measured system frequency of the power system and the reference frequency, and calculates the frequency deviation. A frequency fluctuation suppression unit that calculates an active current command or an active power command for suppressing fluctuations in the system frequency using the power converter, and controls the power converter according to the active current command or the active power command. And a current control unit that outputs an effective current or an effective power. When the frequency deviation change rate exceeds the predetermined change rate, the frequency fluctuation suppressing unit holds the active current command or active power command calculated immediately before the frequency deviation change rate exceeds the predetermined change rate. Have

  Further, the control device for the power converter that suppresses the fluctuation of the system frequency of the power system according to another embodiment of the present invention calculates the frequency deviation between the measured system frequency of the power system and the reference frequency, and calculates the frequency deviation. A frequency fluctuation suppression unit that calculates an active current command or an active power command for suppressing fluctuations in the system frequency using the power converter, and controls the power converter according to the active current command or the active power command. And a current control unit that outputs an effective current or an effective power. The frequency fluctuation suppression unit includes a frequency deviation processing unit that calculates a frequency deviation that can be considered that the change rate of the frequency deviation fluctuates at the predetermined change rate when the change rate of the frequency deviation exceeds the predetermined change rate.

  If the difference between the frequency deviation calculated this time and the previously calculated frequency deviation is greater than the upper limit value of the frequency fluctuation, the frequency deviation processing unit adds the upper limit value to the previously calculated frequency deviation and calculates this time. If the difference is smaller than the lower limit value of the frequency fluctuation, the lower limit value is added to the previously calculated frequency deviation to obtain the frequency deviation calculated this time.

  Further, the control device for the power converter that suppresses the fluctuation of the system frequency of the power system according to another embodiment of the present invention calculates the frequency deviation between the measured system frequency of the power system and the reference frequency, and calculates the frequency deviation. A frequency fluctuation suppression unit that calculates an active current command or an active power command for suppressing fluctuations in the system frequency using the power converter, and controls the power converter according to the active current command or the active power command. And a current control unit that outputs an effective current or an effective power. The frequency fluctuation suppression unit is an active current command or an active power command corresponding to a frequency deviation that can be considered that the frequency deviation change speed fluctuates at the predetermined change speed when the frequency deviation change speed exceeds the predetermined change speed. The active current command processing unit for calculating

  In the single system, the accuracy of the single operation detection can be improved.

It is a figure which shows an example of an electric power grid | system. It is a figure which shows an example of electrical storage equipment. It is a figure which shows an example of a frequency fluctuation suppression part (frequency deviation holding | maintenance). It is a figure which shows an example of operation | movement of a frequency deviation holding part. It is a figure for demonstrating frequency deviation holding | maintenance. It is a figure for demonstrating the effect of a frequency fluctuation suppression part. It is a figure which shows an example of a frequency fluctuation suppression part (effective current command holding | maintenance). It is a figure which shows an example of operation | movement of an active current command holding | maintenance part. It is a figure which shows an example of a frequency fluctuation suppression part (frequency deviation process). It is a figure which shows an example of operation | movement of a frequency deviation process part. It is a figure for demonstrating a frequency deviation process. It is a figure for demonstrating the effect of a frequency fluctuation suppression part. It is a figure which shows an example of a frequency fluctuation suppression part (active current command process). It is a figure which shows an example of operation | movement of an active current command process part. It is a figure which shows an example of the hardware of a computer.

Hereinafter, embodiments will be described in detail with reference to the drawings.
The power system 1 will be described.

  FIG. 1 is a diagram illustrating an example of a power system 1. The electric power system 1 has an upper system 2 and a lower system 3. The host system 2 includes, for example, a synchronous power generation facility 4, a switch 5, a power transmission line 6, and the like. The synchronous power generation facility 4 supplies power to the lower system 3 via the switch 5, the transmission line 6, and the substation facility 7. The subordinate system 3 includes, for example, a distributed power source such as a substation facility 7, a power storage facility 8, a solar power generation facility 9, an induction power generation facility 10, and a distribution line 11. The distributed power source supplies power to a consumer (power receiving facility) (not shown) via the distribution line 11.

  The synchronous power generation facility 4 is a power generation facility such as a thermal power generation facility, a hydropower generation facility, or a nuclear power generation facility. The switch 5 is a switch used when the lower system 3 is disconnected from the upper system 2 when a system failure or a system power failure is detected. The substation facility 7 is a facility that transforms the high voltage supplied from the synchronous power generation facility 4 into a low voltage that can be used by consumers.

  The power storage facility 8 includes a storage battery and a power conditioner (PCS), and supplies the electrical energy stored in the storage battery to the lower system 3 using a power converter (inverter) included in the PCS. The solar power generation facility 9 includes a solar panel and a PCS, and supplies power generated by the solar panel to the lower system 3 using a power converter included in the PCS. The induction power generation facility 10 includes an induction motor (IM) and supplies electric power generated using the induction motor to the lower system 3. In FIG. 1, the power storage facility 8, the solar power generation facility 9, and the induction power generation facility 10 are shown as the distributed power source, but the present invention is not limited to the distributed power source of FIG.

The power storage facility 8 will be described.
FIG. 2 is a diagram illustrating an example of the power storage facility 8. The power storage facility 8 includes a PCS 20 and a storage battery 21. The PCS 20 has a control unit 22 (control device). The control unit 22 includes an isolated operation detection unit 23, a frequency fluctuation suppression unit 24, a reactive current command calculation unit 25, and a current control unit 26. The current control unit 26 includes a two-phase three-phase rotation coordinate conversion unit 27, a phase synchronization unit 28 (PLL), a current controller 29 (ACR), a current controller 30 (ACR), an adder 31, and a pulse width modulation unit 32 ( PWM). The PCS 20 includes a power converter 33 (inverter), a measurement transformer 34, a connection switch 35, a capacitor 36, a coil 37, a coil 38, and a capacitor 39.

  The PCS 20 supplies current or power to the lower system 3 using the electrical energy stored in the storage battery 21. Further, the PCS 20 stores the storage battery 21 using the power of the lower system 3. The storage battery 21 is, for example, a lithium ion battery, a nickel hydride battery, a nickel cadmium battery, a lead storage battery, or a sodium sulfur battery.

  The control unit 22 is a circuit configured using, for example, a CPU (Central Processing Unit), a multi-core CPU, and programmable devices (FPGA (Field Programmable Gate Array), PLD (Programmable Logic Device), etc.). The control unit 22 includes a storage unit inside or outside thereof, and reads and executes a control program stored in the storage unit.

  The isolated operation detection unit 23 detects that the isolated operation has been performed within a predetermined time from the time when the lower system 3 is disconnected from the upper system 2. The predetermined time may be, for example, a time such as 0.2 [seconds] defined in the grid connection regulations. Further, when the isolated operation is detected, the isolated operation detection unit 23 outputs an isolated operation detection command for opening the interconnection switch 35.

  In the example of FIG. 2, the isolated operation detection unit 23 calculates the system frequency using the information Vai indicating the A-phase AC voltage Va, which is the system voltage measured by the measurement transformer 34, and rapidly calculates the calculated system frequency. Frequency fluctuations (for example, fluctuations such as a frequency change rate of 2 [Hz / second]) are detected. In the example of FIG. 2, the frequency of the A-phase AC voltage Va is used as the system frequency. However, the frequency is not limited to the A-phase AC voltage Va, but the frequency of the B-phase AC voltage Vb or the C-phase AC voltage Vc. May be used.

  The frequency fluctuation suppressing unit 24 (effective current command calculating unit) measures the system frequency of the lower system 3 and the reference frequency (for example, information indicating 50 [Hz] or 60 [Hz]) stored in the storage unit in advance. The active current command Ip * or the active power command Pp * for suppressing the increase in system frequency fluctuation is calculated using the frequency deviation. The effective current command Ip * is, for example, a value proportional to the calculated frequency deviation. The active power command Pp * is a value obtained by multiplying the active current command Ip * by a voltage V (≈1.0 [V] or the like). In the following description, an embodiment of the present invention will be described using an effective current command.

  The reactive current command calculating unit 25 calculates a frequency deviation between the latest moving average value of the system frequency and a past moving average value from the latest moving average value, and determines the reactive current command Iq * according to the calculated frequency deviation. calculate. For example, it is conceivable to use a standard active isolated operation detection method (frequency feedback method with step injection) defined in JEM 1505 of the Japan Electrical Manufacturers' Association standard.

  The current control unit 26 controls the power converter 33 using the active current command Ip * output from the frequency fluctuation suppression unit 24 and the reactive current command Iq * output from the reactive current command calculation unit 25, The power converter 33 is caused to output current or power to the lower system 3. That is, the current control unit 26 sends the active current or active power according to the active current command Ip * and the reactive current or reactive power according to the reactive current command Iq * to the power converter 33 from the power converter 33. Output to subordinate system 3.

  The two-phase / three-phase rotation coordinate conversion unit 27 uses the active current command Ip *, the reactive current command Iq *, and the system voltage synchronization phase θ to generate a two-phase current command (effective current command Ip *, reactive current command Iq *). Is converted into a three-phase current command (A-phase current command Ia *, B-phase current command Ib *, C-phase current command Ic *).

  The phase synchronization unit 28 calculates the system voltage synchronization phase θ using the system frequency (for example, information indicating any one of the system voltages Va, Vb, and Vc).

  The current controller 29 (ACR) processes the A-phase current command Ia * output from the two-phase / three-phase rotational coordinate conversion unit 27 using feedback control (for example, PI control), and the A-phase voltage command Va *. Is calculated. The current controller 30 (ACR) processes the C-phase current command Ic * output from the two-phase three-phase rotational coordinate conversion unit 27 using feedback control (for example, PI control), and the C-phase voltage command Vc *. Is calculated. Adder 31 calculates B phase voltage command Vb * using A phase voltage command Va * and C phase voltage command Vc *. The calculation of the B phase voltage command Vb * is not limited to the calculation method using the current controller 29, the current controller 30, and the adder 31. For example, the B-phase voltage command Vb * may be calculated by processing the B-phase current command Ib * using feedback control (for example, PI control).

  The pulse width modulation unit 32 uses the A phase voltage command Va *, the B phase voltage command Vb *, and the C phase voltage command Vc * to control a semiconductor switching element (not shown) provided in the power converter 33. A signal is generated and output to the power converter 33.

  The power converter 33 converts the DC power output from the storage battery 21 into AC power, and supplies the AC power to the lower system 3 (distribution line 11). Further, the power converter 33 converts the AC power input from the lower system 3 (distribution line 11) into DC power, and supplies the DC power to the storage battery 21. Note that a matrix converter or the like may be used as the power converter 33.

  The measurement transformer 34 measures the voltage of the distribution line 11 connected to the interconnection switch 35 and outputs the voltage to the control unit 22. 2 is connected to one end of each of the coils 37 and 38 and the capacitor 39, or between the power converter 33 and the other end of the coil 37, or connected to the other end of the coil 38. It is good also as a system voltage by measuring the voltage between the switches 35.

  The interconnection switch 35 is, for example, a mechanical switch such as a relay or a switch that is used when the power storage facility 8 is disconnected from the distribution line 11 when single operation is detected.

(1) The frequency fluctuation suppressing unit 24 (frequency deviation holding) will be described.
FIG. 3 is a diagram illustrating an example of the frequency fluctuation suppressing unit 24 (frequency deviation holding). The frequency fluctuation suppressing unit 24 illustrated in FIG. 3 includes a reference frequency setting unit 301, a frequency detection unit 302, an adder 303, a frequency deviation holding unit 304, and an adjustment unit 305.

  The reference frequency setting unit 301 corresponds to a part of a storage unit (not shown), and a reference frequency indicating a system frequency as a reference is set. The reference frequency is, for example, 50 [Hz] or 60 [Hz].

  The frequency detector 302 detects the system frequency. For example, the system frequency is detected using information Vai indicating the A-phase AC voltage Va.

The adder 303 calculates a frequency deviation between the system frequency and the reference frequency.
The frequency deviation holding unit 304 holds the frequency deviation calculated by the adder 303 immediately before the frequency deviation change rate exceeds the predetermined change rate when the frequency deviation change rate exceeds the predetermined change rate. Is output to the adjustment unit 305. Further, when the change rate of the frequency deviation does not exceed the predetermined change rate, the frequency deviation holding unit 304 outputs the frequency deviation calculated this time by the adder 303 to the adjustment unit 305 as it is. As the predetermined change speed, for example, a frequency change speed of a system frequency of 2 [Hz / second] or more defined in the grid connection regulation may be considered.

FIG. 4 is a diagram illustrating an example of the operation of the frequency deviation holding unit 304.
In step S1, the frequency deviation holding unit 304 calculates a difference dF between the frequency deviation calculated this time by the adder 303 and the previously calculated frequency deviation.

  In step S2, the frequency deviation holding unit 304 determines whether or not the absolute value of the difference is greater than the limit value. If the absolute value of the difference | dF | is greater than the limit value (S2: Yes), the process proceeds to step S3. If the absolute value | dF | of the difference is equal to or smaller than the limit value (S2: No), the process proceeds to step S4. The limit value is a value set in advance by the user, and is a value representing the upper and lower limits of the frequency deviation that can be allowed by the power system to be controlled. Specifically, a value in the range of −2 [Hz / sec] to 2 [Hz / sec] determined by the FRT (Fault Ride Through) requirement defined in the grid connection is conceivable. However, it is not limited to the value of the said range.

  In step S <b> 3, the frequency deviation holding unit 304 outputs the frequency deviation (previously calculated frequency deviation) calculated immediately before exceeding the limit value (immediately before the frequency deviation change rate exceeds the predetermined change rate) to the adjustment unit 305. . That is, the frequency deviation calculated this time is not output, but the frequency deviation calculated last time is output to the adjustment unit 305.

  In step S4, the frequency deviation holding unit 304 outputs the frequency deviation calculated this time to the adjustment unit 305.

  In step S5, the frequency deviation holding unit 304 stores the frequency deviation output in step S3 or S4 as the previously calculated frequency deviation. That is, the frequency deviation holding unit 304 holds the frequency deviation.

  FIG. 5 is a diagram for explaining the frequency deviation holding. In FIG. 5, the vertical axis represents frequency deviation, and the horizontal axis represents time. In step S2, if the frequency deviation holding unit 304 determines that the absolute value | dF | of the difference is larger than the limit value, that is, the actual frequency deviation (solid line) in FIG. 5 corresponds to the limit value. When exceeding (broken line) (see point A), the frequency deviation previously calculated by the processing of steps S3 and S5 is held (frequency deviation after holding (bold solid line)), thereby substantially suppressing the frequency fluctuation. Disable the control to be performed.

  Subsequently, the adjustment unit 305 in FIG. 3 calculates an effective current command Ip * by multiplying the frequency deviation by a gain value stored in advance in the storage unit. The gain value is a value determined by the system frequency, and is determined by experiment or simulation, for example.

  Subsequently, the current control unit 26 outputs the active current command Ip * output from the adjustment unit 305, the reactive current command Iq * output from the reactive current command calculation unit 25, and the system voltage output from the phase synchronization unit 28. A PWM signal is generated using the synchronization phase θ, the power converter 33 is controlled by the PWM signal, and current or power is output from the power converter 33 to the distribution line 11.

  In this way, when the frequency deviation change rate exceeds the predetermined change rate, the frequency deviation calculated immediately before the frequency deviation change rate exceeds the predetermined change rate is held using the frequency fluctuation suppressing unit 24 shown in FIG. By performing the control, it is possible to relax the guarantee of variation with respect to the frequency deviation that changes suddenly during the single operation, and thus it is possible to weaken the function of suppressing the increase in the variation of the system frequency. By doing so, even when the isolated operation detecting unit 23 and the frequency fluctuation suppressing unit 24 are mounted in the power storage facility 8, the isolated operation detecting unit 23 can normally detect that the system frequency fluctuates rapidly as usual. That is, the accuracy of the isolated operation detection in the isolated system can be improved.

  FIG. 6 is a diagram for explaining the effect of the frequency fluctuation suppressing unit 24. Moreover, the simulation result shown in FIG. 6 is a simulation result at the time of performing independent operation detection using the model corresponding to the electric power system 1 shown in FIG. Further, A, B, and C in FIG. 6 indicate A: system voltage, B: system current, and C: system frequency when the frequency variation suppressing unit 24 does not take measures to maintain the frequency deviation. D, E, and F in FIG. 6 indicate D: system voltage, E: system current, and F: system frequency when the frequency variation suppressing unit 24 takes measures to maintain the frequency deviation. Moreover, the vertical axis of FIG. 6 shows A, D: voltage [V], B, E: current [A], C, F: frequency [Hz], and the horizontal axis shows time. The simulation conditions are a reference frequency of 50 [Hz], a gain value of 10, and an inertia constant of 0.1 [seconds]. The inertia constant indicates the magnitude of inertia of the induction motor IM (rotational load) included in the induction power generation facility 10 shown in FIG.

  If no countermeasure is taken, the PCS 20 suppresses an increase in the fluctuation of the system frequency (because the fluctuation of the system frequency becomes gentle as shown in FIG. 6C), the isolated operation detection unit 23 detects the isolated operation from the isolated operation. The time until the start (time from the single operation shown in FIG. 6C to the detection 1) requires a little less than 0.8 [seconds]. On the other hand, when countermeasures are taken, the PCS 20 does not suppress an increase in the fluctuation of the system frequency (because the fluctuation of the system frequency is large as shown in F of FIG. 6), so ] (Self operation can be detected with a little (time from the single operation shown in F of FIG. 6 to detection 2). The larger the gain value and the inertia constant, the longer the time until the isolated operation is detected.

(2) The frequency fluctuation suppressing unit 24 (active current command holding) will be described.
FIG. 7 is a diagram illustrating an example of the frequency variation suppressing unit 24 (active current command holding). The frequency fluctuation suppressing unit 24 illustrated in FIG. 7 includes a reference frequency setting unit 301, a frequency detection unit 302, an adder 303, an adjustment unit 71, and an active current command holding unit 72. The description of the reference frequency setting unit 301, the frequency detection unit 302, and the adder 303 has already been described with reference to FIG.

  The adjustment unit 71 calculates the effective current command Ip * by multiplying the frequency deviation by a gain value stored in advance in the storage unit.

  The effective current command holding unit 72 holds and holds the effective current command calculated by the adjusting unit 71 immediately before the change rate of the frequency deviation exceeds the predetermined change rate when the change rate of the frequency deviation exceeds the predetermined change rate. The effective current command is output to the current control unit 26. Further, when the change rate of the frequency deviation does not exceed the predetermined change rate, the active current command holding unit 72 outputs the effective current command calculated this time by the adjustment unit 71 to the current control unit 26 as it is.

  FIG. 8 is a diagram illustrating an example of the operation of the active current command holding unit 72. Description of steps S1 and S2 has already been described with reference to FIG. However, in step S2 of FIG. 8, when the difference absolute value | dF | is larger than the limit value (S2: Yes), the process proceeds to step S81, and when the difference absolute value | dF | is equal to or less than the limit value (S2 : No), the process proceeds to step S82.

  In step S81, the active current command holding unit 72 uses the effective current command (the previously calculated effective current command) calculated immediately before exceeding the limit value (immediately before the change rate of the frequency deviation exceeds the predetermined change rate) as the current control unit. 26. That is, the currently calculated effective current command is not output, and the previously calculated effective current command is output to the current control unit 26.

  In step S <b> 82, the active current command holding unit 72 outputs the currently calculated effective current command to the current control unit 26.

  In step S83, the active current command holding unit 72 stores the active current command output in step S81 or S82 as the previously calculated active current command. That is, the active current command holding unit 72 holds the active current command. In step S83, the active current command holding unit 72 stores the previous frequency deviation when the active current command is output in step S81, and stores the current frequency deviation when the active current command is output in step S82. To do.

  As described above, when the frequency deviation change rate exceeds the predetermined change rate, the effective current command calculated immediately before the frequency deviation change rate exceeds the predetermined change rate is held using the frequency fluctuation suppressing unit 24 shown in FIG. By performing the control, it is possible to relax the variation guarantee for the frequency deviation that changes suddenly during the single operation, and therefore, it is possible to weaken the function of suppressing an increase in the variation of the system frequency. By doing so, even when the isolated operation detecting unit 23 and the frequency fluctuation suppressing unit 24 are mounted in the power storage facility 8, the isolated operation detecting unit 23 can normally detect that the system frequency fluctuates rapidly as usual. That is, the accuracy of the isolated operation detection in the isolated system can be improved.

(3) The frequency fluctuation suppressing unit 24 (frequency deviation processing) will be described.
FIG. 9 is a diagram illustrating an example of a frequency fluctuation suppressing unit (frequency deviation processing). The frequency fluctuation suppressing unit 24 illustrated in FIG. 9 includes a reference frequency setting unit 301, a frequency detection unit 302, an adder 303, a frequency deviation processing unit 91, and an adjustment unit 92. The description of the reference frequency setting unit 301, the frequency detection unit 302, and the adder 303 has already been described with reference to FIG.

  The frequency deviation processing unit 91 calculates a frequency deviation that can be considered that the change rate of the frequency deviation fluctuates at the predetermined change rate when the change rate of the frequency deviation exceeds the predetermined change rate, and calculates the calculated frequency deviation. The data is output to the adjustment unit 92. Further, when the change rate of the frequency deviation does not exceed the predetermined change rate, the frequency deviation processing unit 91 outputs the frequency deviation calculated this time by the adder 303 to the adjustment unit 92 as it is.

FIG. 10 is a diagram illustrating an example of the operation of the frequency deviation processing unit 91.
In step S101, the frequency deviation processing unit 91 calculates a difference dF between the frequency deviation calculated this time and the frequency deviation calculated last time.

  In step S102, the frequency deviation processing unit 91 determines whether or not the difference dF is larger than the upper limit value. If the difference dF is larger than the upper limit value (S102: Yes), the process proceeds to step S103, and the difference dF Is less than or equal to the upper limit value (S102: No), the process proceeds to step S104.

  In step S <b> 103, the frequency deviation processing unit 91 sets the value obtained by adding the upper limit value to the previously calculated frequency deviation as the currently calculated frequency deviation, and outputs it to the adjustment unit 92. The upper limit value indicates the upper limit side of the limit value described above (the upper limit of the frequency fluctuation limit value). Specifically, it is 2 [Hz / second] when set in accordance with the grid connection regulations. However, the upper limit value is not limited to 2 [Hz / second].

  In step S104, the frequency deviation processing unit 91 determines whether or not the difference dF is smaller than the lower limit value. If the difference dF is smaller than the lower limit value (S104: Yes), the process proceeds to step S105. If it is equal to or greater than the lower limit value (S104: No), the process proceeds to step S106. The lower limit value indicates the lower limit side of the limit value described above (the lower limit of the frequency fluctuation limit value). Specifically, it is −2 [Hz / second] when set in accordance with the grid connection regulations. However, the lower limit value is not limited to −2 [Hz / second].

  In step S <b> 105, the frequency deviation processing unit 91 sets the value obtained by adding the lower limit value to the previously calculated frequency deviation as the currently calculated frequency deviation, and outputs it to the adjustment unit 92.

  In step S <b> 106, the frequency deviation processing unit 91 outputs the frequency deviation calculated this time to the adjustment unit 92.

  FIG. 11 is a diagram for explaining the frequency deviation process. In FIG. 11, the vertical axis indicates the frequency deviation, and the horizontal axis indicates time. In step S102, when the frequency deviation processing unit 91 determines that the difference dF is larger than the upper limit value, for example, in FIG. 11, the actual frequency deviation (solid line) corresponds to the upper limit value (frequency change speed upper limit (broken line)). (See point A), the frequency deviation is made to follow the upper limit of the frequency change rate (broken line) by the process of step S103. That is, it is assumed that the change rate of the frequency deviation varies at a predetermined change rate (frequency deviation after processing (bold solid line)). In other words, the excess of the change rate of the frequency deviation is not compensated by the control for suppressing the frequency fluctuation. Similarly, processing that does not perform compensation for the amount exceeding the lower limit of the change rate of the frequency deviation (output along the lower limit of the change rate of the frequency deviation) is performed in step S105.

  Subsequently, the adjustment unit 92 in FIG. 9 calculates a value obtained by multiplying the frequency deviation processed by the frequency deviation processing unit 91 by the gain value stored in advance in the storage unit. Since (3) the gain value used in the frequency deviation process can be regarded as the change rate of the frequency deviation fluctuates at a predetermined change rate, (1) frequency deviation retention, (2) active power It may be a value different from the gain value used for command holding.

  Subsequently, the current control unit 26, the value output from the adjustment unit 92, the reactive current command Iq * output from the reactive current command calculation unit 25 in FIG. 2, and the system voltage synchronization output from the phase synchronization unit 28. A PWM signal is generated using the phase θ, the power converter 33 is controlled by the PWM signal, and current or power is output from the power converter 33 to the distribution line 11.

  In this way, when the frequency deviation change rate exceeds the predetermined change rate using the frequency fluctuation suppressing unit 24 shown in FIG. 9, the frequency deviation that can be considered that the frequency deviation change rate fluctuates at the predetermined change rate. By the control for calculating the fluctuation, it is possible to relax the fluctuation guarantee for the frequency deviation that suddenly changes during the single operation, so that the function of suppressing the increase in fluctuation of the system frequency can be weakened. By doing so, even when the isolated operation detecting unit 23 and the frequency fluctuation suppressing unit 24 are mounted in the power storage facility 8, the isolated operation detecting unit 23 can normally detect that the system frequency fluctuates rapidly as usual. That is, the accuracy of the isolated operation detection in the isolated system can be improved.

  FIG. 12 is a diagram for explaining the effect of the frequency fluctuation suppressing unit 24. Moreover, the simulation result shown in FIG. 12 is a simulation result at the time of performing an isolated operation detection using the model corresponding to the electric power system 1 shown in FIG. Further, A, B, and C in FIG. 12 indicate A: system voltage, B: system current, and C: system frequency when the frequency variation suppressing unit 24 does not take measures for frequency deviation processing. D, E, and F in FIG. 12 indicate D: system voltage, E: system current, and F: system frequency when the frequency variation suppression unit 24 takes measures against frequency deviation processing. In FIG. 12, the vertical axis indicates A, D: voltage [V], B, E: current [A], C, F: frequency [Hz], and the horizontal axis indicates time. The simulation conditions are a reference frequency of 50 [Hz], a gain value of 10, and an inertia constant of 0.1 [seconds].

  When no countermeasure is taken, the PCS 20 suppresses an increase in fluctuations in the system frequency (because the system frequency becomes gentle as shown in FIG. 12C), until the isolated operation detection unit 23 detects the isolated operation from the isolated operation. The time (the time from the single operation shown in FIG. 12C to the detection 1) requires a little less than 0.8 [seconds]. On the other hand, when countermeasures are taken, the PCS 20 does not suppress an increase in fluctuations in the system frequency (because the fluctuations in the system frequency are large as indicated by F in FIG. 12). ] (Self operation can be detected with a little (time from the single operation shown in F of FIG. 12 to detection 3). The larger the gain value and the inertia constant, the longer the time until the isolated operation is detected.

(4) The frequency fluctuation suppressing unit 24 (effective current command processing) will be described.
FIG. 13 is a diagram illustrating an example of the frequency fluctuation suppressing unit 24 (effective current command processing). The frequency fluctuation suppressing unit 24 illustrated in FIG. 13 includes a reference frequency setting unit 301, a frequency detection unit 302, an adder 303, an adjustment unit 131, and an active current command processing unit 132. The description of the reference frequency setting unit 301, the frequency detection unit 302, and the adder 303 has already been described with reference to FIG.

  The adjustment unit 131 multiplies the frequency deviation and the gain value stored in advance in the storage unit to calculate the effective current command Ip *.

  The effective current command processing unit 132, when the change rate of the frequency deviation exceeds a predetermined change rate, the effective current command Ip * corresponding to the frequency deviation that can be considered that the change rate of the frequency deviation varies at the predetermined change rate. And the calculated effective current command Ip * is output to the current control unit 26. Further, when the change rate of the frequency deviation does not exceed the predetermined change rate, the active current command processing unit 132 outputs the effective current command Ip * calculated by the adjustment unit 131 to the current control unit 26 as it is.

  FIG. 14 is a diagram illustrating an example of the operation of the active current command processing unit 132. Description of steps S101, S102, and S104 has already been described with reference to FIG. .

  In step S <b> 141, the active current command processing unit 132 sets a value obtained by adding the previously calculated active current command and the upper limit current limit value as the current active current command and outputs the current current command to the current control unit 26. In step S142, the active current command processing unit 132 outputs a value obtained by adding the lower limit current limit value to the previously calculated active current command to the current control unit 26 as the current active current command.

  The upper limit current limit value and the lower limit current limit value are values obtained by converting the upper limit limit value and the lower limit limit value of the frequency variation described above into a current command.

  In step S <b> 143, the active current command processing unit 132 outputs the currently calculated active current command to the current control unit 26.

  In this way, when the frequency deviation change rate exceeds the predetermined change rate using the frequency fluctuation suppression unit 24 shown in FIG. 13, the frequency deviation that can be considered that the frequency deviation change rate fluctuates at the predetermined change rate. By controlling to calculate the effective current command corresponding to the above, it is possible to relax the variation guarantee for the frequency deviation that suddenly changes during the single operation, and therefore, it is possible to weaken the function of suppressing the increase in the variation of the system frequency. By doing so, even when the isolated operation detecting unit 23 and the frequency fluctuation suppressing unit 24 are mounted in the power storage facility 8, the isolated operation detecting unit 23 can normally detect that the system frequency fluctuates rapidly as usual. That is, the accuracy of the isolated operation detection in the isolated system can be improved.

  The present invention is not limited to the above-described embodiment, and various improvements and modifications can be made without departing from the gist of the present invention.

  Note that the control unit 22 (control device) of the power converter 33 having the frequency fluctuation suppressing unit 24 described in (1) to (4) above may be mounted on a distributed power source other than the power storage facility 8.

  Further, the control program of the control unit 22 described in (1) to (4) above may be stored in a storage medium as a simulation model and executed by a computer shown in FIG.

  FIG. 15 is a diagram illustrating an example of computer hardware. In the example of FIG. 15, a CPU 151, a RAM 152 (Random Access Memory), a ROM 153 (Read Only Memory), a recording medium 154, a communication interface 155, and an input / output interface 156 are connected to the bus 150 in the example of FIG. The CPU 151 executes a program stored in the RAM 152. The ROM 153 is a nonvolatile storage device that stores programs stored in the RAM 152. The recording medium 154 is, for example, a portable recording medium such as a portable memory (for example, a semiconductor memory) or an optical disk (for example, a CD (Compact Disc) or a DVD (Digital Versatile Disc)). Further, the control program described in (1) to (4) above is recorded as a simulation model on the recording medium 154. The communication interface 155 is an interface that communicates with an external device, and communicates with, for example, a host computer. The input / output interface 156 is an input device (for example, a keyboard or a mouse) or an output device (for example, a monitor or a printer). Note that the RAM 152, the ROM 153, and the recording medium 154 are all examples of a tangible storage medium that can be read by a computer. These tangible storage media are not temporary media such as signal carriers.

DESCRIPTION OF SYMBOLS 1 Power system 2 Upper system 3 Sub system 4 Synchronous power generation equipment 5 Switch 6 Transmission line 7 Substation equipment 8 Power storage equipment 9 Solar power generation equipment 10 Induction power generation equipment 11 Distribution line 20 PCS
DESCRIPTION OF SYMBOLS 21 Storage battery 22 Control part 23 Isolated operation detection part 24 Frequency fluctuation suppression part 25 Reactive current command calculation part 26 Current control part 27 Two-phase three-phase rotational coordinate conversion part 28 Phase synchronization part 29, 30 Current controller 31 Adder 32 Pulse width Modulator 33 Power converter 34 Measurement transformer 35 Interconnection switch 36 Capacitor 37, 38 Coil 39 Capacitor 71 Adjustment unit 72 Effective current command holding unit 91 Frequency deviation processing unit 92 Adjustment unit 131 Adjustment unit 132 Effective current command processing unit 150 bus 151 CPU
152 RAM
153 ROM
154 Recording medium 155 Communication interface 156 Input / output interface 301 Reference frequency setting unit 302 Frequency detection unit 303 Adder 304 Frequency deviation holding unit 305 Adjustment unit

Claims (13)

A control device for a power converter that suppresses fluctuations in the grid frequency of the power grid,
A frequency fluctuation suppression unit that calculates a frequency deviation between the system frequency and a reference frequency of the measured power system, and calculates an active current command or an active power command for suppressing fluctuations in the system frequency using the frequency deviation. When,
A current control unit that controls the power converter according to the active current command or the active power command, and outputs an active current or active power from the power converter to the power system, and
The frequency fluctuation suppressing unit is
A power conversion comprising: a frequency deviation holding unit that holds a frequency deviation calculated immediately before the frequency deviation change speed exceeds the predetermined change speed when the frequency deviation change speed exceeds a predetermined change speed. Control device. A control device for a power converter that suppresses fluctuations in the grid frequency of the power grid,
A frequency fluctuation suppression unit that calculates a frequency deviation between the system frequency and a reference frequency of the measured power system, and calculates an active current command or an active power command for suppressing fluctuations in the system frequency using the frequency deviation. When,
A current control unit that controls the power converter according to the active current command or the active power command, and outputs an active current or active power from the power converter to the power system, and
The frequency fluctuation suppressing unit is
An active current command holding unit that holds an active current command or an active power command calculated immediately before the frequency deviation change rate exceeds the predetermined change rate when the frequency deviation change rate exceeds a predetermined change rate; A control device for a power converter characterized by the above. A control device for a power converter that suppresses fluctuations in the grid frequency of the power grid,
A frequency fluctuation suppression unit that calculates a frequency deviation between the system frequency and a reference frequency of the measured power system, and calculates an active current command or an active power command for suppressing fluctuations in the system frequency using the frequency deviation. When,
A current control unit that controls the power converter according to the active current command or the active power command, and outputs an active current or active power from the power converter to the power system, and
The frequency fluctuation suppressing unit is
A frequency deviation processing unit that calculates a frequency deviation that can be considered that the change rate of the frequency deviation fluctuates at the predetermined change rate when the change rate of the frequency deviation exceeds a predetermined change rate; Control device for power converter. It is a control apparatus of the power converter of Claim 3, Comprising:
The frequency deviation processing unit is
When the difference between the frequency deviation calculated this time and the frequency deviation calculated last time is larger than the upper limit limit value of the frequency fluctuation, the upper limit value is added to the frequency deviation calculated last time to obtain the frequency deviation calculated this time,
When the difference is smaller than a lower limit value of frequency fluctuation, the lower limit value is added to the previously calculated frequency deviation to obtain the currently calculated frequency deviation. A control device for a power converter that suppresses fluctuations in the grid frequency of the power grid,
A frequency fluctuation suppression unit that calculates a frequency deviation between the system frequency and a reference frequency of the measured power system, and calculates an active current command or an active power command for suppressing fluctuations in the system frequency using the frequency deviation. When,
A current control unit that controls the power converter according to the active current command or the active power command, and outputs an active current or active power from the power converter to the power system, and
The frequency fluctuation suppressing unit is
When the rate of change of the frequency deviation exceeds a predetermined rate of change, an effective current command or an effective current command corresponding to the frequency deviation that can be considered that the rate of change of the frequency deviation varies at the predetermined rate of change is calculated. A control device for a power converter, comprising: an active current command processing unit. A method for controlling a power converter that suppresses fluctuations in the grid frequency of a power grid,
Calculate a frequency deviation between the system frequency and a reference frequency of the measured power system, and calculate an active current command or an active power command for suppressing fluctuations in the system frequency using the frequency deviation,
Control the power converter according to the active current command or the active power command, and output an active current or active power from the power converter to the power system,
The method of controlling a power converter, wherein when the change rate of the frequency deviation exceeds a predetermined change rate, the frequency deviation calculated immediately before the change rate of the frequency deviation exceeds the predetermined change rate is retained. A method for controlling a power converter that suppresses fluctuations in the grid frequency of a power grid,
Calculate a frequency deviation between the system frequency and a reference frequency of the measured power system, and calculate an active current command or an active power command for suppressing fluctuations in the system frequency using the frequency deviation,
Control the power converter according to the active current command or the active power command, and output an active current or active power from the power converter to the power system,
When the change rate of the frequency deviation exceeds a predetermined change rate, an active current command or an active power command calculated immediately before the change rate of the frequency deviation exceeds the predetermined change rate is held. Control method. A method for controlling a power converter that suppresses fluctuations in the grid frequency of a power grid,
Calculate a frequency deviation between the system frequency and a reference frequency of the measured power system, and calculate an active current command or an active power command for suppressing fluctuations in the system frequency using the frequency deviation,
Control the power converter according to the active current command or the active power command, and output an active current or active power from the power converter to the power system,
When the change rate of the frequency deviation exceeds a predetermined change rate, a frequency deviation that calculates that the change rate of the frequency deviation is fluctuating at the predetermined change rate is calculated. Method. A method for controlling a power converter that suppresses fluctuations in the grid frequency of a power grid,
Calculate a frequency deviation between the system frequency and a reference frequency of the measured power system, and calculate an active current command or an active power command for suppressing fluctuations in the system frequency using the frequency deviation,
Control the power converter according to the active current command or the active power command, and output an active current or active power from the power converter to the power system,
When the change rate of the frequency deviation exceeds a predetermined change rate, an active current command or an active power command corresponding to the frequency deviation that can be considered that the change rate of the frequency deviation fluctuates at the predetermined change rate is calculated. A method for controlling a power converter. A control program for a power converter that suppresses fluctuations in the grid frequency of the power grid,
On the computer,
Calculate a frequency deviation between the system frequency and a reference frequency of the measured power system, and calculate an active current command or an active power command for suppressing fluctuations in the system frequency using the frequency deviation,
Control the power converter according to the active current command or the active power command, and output an active current or active power from the power converter to the power system,
When the change rate of the frequency deviation exceeds a predetermined change rate, a process for holding the frequency deviation calculated immediately before the change rate of the frequency deviation exceeds the predetermined change rate is executed. Control program. A control program for a power converter that suppresses fluctuations in the grid frequency of the power grid,
On the computer,
Calculate a frequency deviation between the system frequency and a reference frequency of the measured power system, and calculate an active current command or an active power command for suppressing fluctuations in the system frequency using the frequency deviation,
Control the power converter according to the active current command or the active power command, and output an active current or active power from the power converter to the power system,
When the change rate of the frequency deviation exceeds a predetermined change rate, a process of holding the active current command or active power command calculated immediately before the change rate of the frequency deviation exceeds the predetermined change rate is performed. To control the power converter. A control program for a power converter that suppresses fluctuations in the grid frequency of the power grid,
On the computer,
Calculate a frequency deviation between the system frequency and a reference frequency of the measured power system, and calculate an active current command or an active power command for suppressing fluctuations in the system frequency using the frequency deviation,
Control the power converter according to the active current command or the active power command, and output an active current or active power from the power converter to the power system,
When the change speed of the frequency deviation exceeds a predetermined change speed, a process is performed to calculate a frequency deviation that can be considered that the change speed of the frequency deviation fluctuates at the predetermined change speed. Control program for the converter. A control program for a power converter that suppresses fluctuations in the grid frequency of the power grid,
On the computer,
Calculate a frequency deviation between the system frequency and a reference frequency of the measured power system, and calculate an active current command or an active power command for suppressing fluctuations in the system frequency using the frequency deviation,
Control the power converter according to the active current command or the active power command, and output an active current or active power from the power converter to the power system,
When the change rate of the frequency deviation exceeds a predetermined change rate, an active current command or an active power command corresponding to the frequency deviation that can be considered that the change rate of the frequency deviation fluctuates at the predetermined change rate is calculated. A control program for a power converter, characterized by causing a process to be executed.