JP2021035125A - Independent operation detection method - Google Patents

Abstract

To provide an independent operation detection method of an invalid power injection method, in which a flicker event of a system is suppressed even if the invalid power is injected.SOLUTION: An independent operation detection method includes the steps of: calculating an amount of invalid power from a system frequency fluctuation type independent operation detection system and inputting it to an invalid power addition section; inputting the invalid power from the system voltage fluctuation type independent operation detection system to the invalid power addition section based on a predetermined condition; inputting an invalid power from a harmonic fluctuation type independent operation detection system to the invalid power addition section based on the predetermined condition; and injecting the invalid power added by the invalid power addition section into the system. The invalid power that gradually increases with a predetermined inclination and gradually decreases with the predetermined inclination is injected as an invalid power adding the invalid power from the system voltage fluctuation type independent operation detection system and the invalid power from the harmonic fluctuation type independent operation detection system.SELECTED DRAWING: Figure 1

Description

The present invention relates to an independent operation detection method of an ineffective power injection method.

In Patent Document 1, in addition to giving reactive power to the power system to detect whether or not the distributed power source is separated from the power system and operating independently, system frequency fluctuation, system voltage fluctuation, and harmonic fluctuation are caused. , A method of detecting independent operation based on the system frequency fluctuation, system voltage fluctuation, and harmonic fluctuation (hereinafter, referred to as "invalid power injection method independent operation detection method") is disclosed.

In the solitary operation detection method of Patent Document 1, the solitary operation is detected by adding the ineffective power input to the ineffective power addition unit and injecting the added inactive power into the power system. When the system frequency deviation is equal to or less than a certain level and the system voltage fluctuation satisfies a predetermined determination condition, a constant amount of reactive power is input to the reactive power addition unit. Further, when the system frequency deviation is equal to or less than a certain value and the harmonic fluctuation of the system satisfies a predetermined determination condition, a certain amount of ineffective power is input to the ineffective power addition unit.

Non-Patent Document 1 is a standard of the Japan Electrical Manufacturers' Association, which shows a standard active independent operation detection method for a single-phase power conditioner for a distributed power source. In this standard, the start condition of step injection, the injection time, and the additional injection amount are specified for the additional ineffective power to be added to the ineffective power at the set operating power factor in the independent operation detection method of the ineffective power injection method.

Japanese Patent No. 4835587

Japan Electric Industry Association, "Japan Electric Industry Association Standard JEM1498 Standard type active independent operation detection method of single-phase power conditioner for distributed power supply (frequency feedback method with step injection)", Japan Electric Industry Association, August 27, 2012 Date established, revised on December 15, 2017 (3rd)

In Patent Document 1, when detecting isolated operation, as described in FIG. 9 and paragraphs [0077], [0078] and the like, a fixed amount of reactive power that changes stepwise is injected into the system. .. However, when a certain amount of reactive power that changes in steps is injected into the system, a flicker event may occur.

The present invention has been made in view of the above problems, and an object of the present invention is to suppress a flicker event even if an ineffective power is injected in the independent operation detection method of the ineffective power injection method.

The isolated operation detection method according to the first aspect of the present invention is invalid by calculating the amount of invalid power from the system frequency fluctuation type isolated operation detection system based on the system frequency deviation calculated from the measurement result of the system frequency of the system power. Invalid from the system voltage fluctuation type independent operation detection system when the process of inputting to the power addition unit and the calculated system frequency deviation are less than a certain level and the electrical fluctuation in the independent operation state is the system voltage fluctuation. Harmonic fluctuation type independent operation detection in the process of inputting power to the invalid power addition unit and when the calculated system frequency deviation is less than a certain level and the electrical fluctuation in the independent operation state is harmonic fluctuation. The step of inputting the invalid power from the system to the negative power addition unit and the step of adding the invalid power input by the negative power addition unit and injecting the added invalid power into the system are included. As the ineffective power obtained by adding the ineffective power from the system voltage fluctuation type independent operation detection system and the ineffective power from the harmonic fluctuation type independent operation detection system, it gradually increases with a predetermined inclination and gradually increases with a predetermined inclination. Inject reduced power.

In the above method, the waveform of the injected reactive power is, for example, a sine wave, a triangular wave, or a trapezoidal wave.

In this way, by injecting ineffective power that gradually increases / decreases with a predetermined inclination as the inactive power to be injected in the independent operation detection method of the ineffective power injection method, it is possible to suppress the occurrence of flicker events in the system. can do.

In the isolated operation detection method of the ineffective power injection method according to the first aspect of the present invention, the system frequency is measured, the system frequency deviation is calculated based on the measured system frequency, and the calculated system frequency deviation is used as the first method. 1 The process of calculating the injection ineffective power and the system voltage are measured, and the system voltage is measured based on the difference between the average value of the past predetermined multiple cycles and the measured value in the latest predetermined cycle. The process of determining whether or not there is fluctuation, measuring the harmonic voltage of the system, and for this measured harmonic voltage, the difference between the average value of a predetermined multiple cycle in the past and the measured value in the latest predetermined cycle. In the step of determining whether or not there is a fluctuation in the harmonic voltage of the system based on the above, and when the calculated system frequency deviation is below a certain level and there is the system voltage fluctuation or the harmonic voltage fluctuation. The step of adding the first injection ineffective power and the second injection ineffective power that gradually increases with a predetermined inclination and gradually decreases with a predetermined inclination is included in the system.

In this way, a flicker event occurs in the system by injecting the ineffective power that gradually increases / decreases with a predetermined inclination as the second injection ineffective power to be injected in the independent operation detection method of the ineffective power injection method. Can be suppressed.

According to the present invention, in the active power injection type independent operation detection method, it is possible to suppress the occurrence of a flicker event in the system due to the injection of reactive power.

Block diagram showing a configuration example of the grid interconnection system of the first embodiment The figure which shows the relationship between the frequency deviation of a system and the 1st injection reactive power. The figure which shows the waveform example of the reactive power to be additionally injected The figure for demonstrating the action effect by additionally injecting the ineffective power of FIG. Block diagram showing a configuration example of the grid interconnection system of the second embodiment

Hereinafter, embodiments will be described with reference to the drawings.

(Embodiment 1)
FIG. 1 is a block diagram showing a configuration example of the grid interconnection system of the first embodiment. The grid interconnection system is configured so that the electric power supplied from the distributed power source 2 can be supplied to the load 6 or reverse power flow to the grid 5.

As shown in FIG. 1, the grid interconnection system includes an inverter device 3 for interconnecting the distributed power source 2 to the grid 5, an MPPT (maximum power point tracking) control unit 4, and an independent operation detection device 100. .. Here, an example in which a solar cell is used as the distributed power source 2 will be described. However, the distributed power source 2 is not limited to the solar cell. In the following description, it is assumed that the solar cell is also designated by the same reference numeral 2 as the distributed power source.

The inverter device 3 is configured to step down the output voltage of the solar cell 2 and output it by utilizing the switching operation of the switching element (not shown). The inverter device 3 receives the maximum power point tracking control of the MPPT control unit 4 and operates at a predetermined power factor. Specifically, the inverter device 3 includes a PWM control unit 31 that outputs a PWM (Pulse Width Modulation) signal that controls the switching operation of the switching element. The PWM control unit 31 adjusts the duty ratio of the PWM signal based on the power command P output from the MPPT control unit 4 and the invalid power command Q output from the adder 140 described later. The MPPT control unit 4 adjusts the power command P so that the output power of the solar cell 2 is maximized based on the output voltage and the output current of the solar cell 2. As the specific circuit configuration of the inverter device 3 and the MPPT control unit 4 can be applied to those conventionally known, detailed description thereof will be omitted here.

The independent operation detection device 100 includes a power factor calculation unit 110, a first reactive power calculation unit 120, a second reactive power calculation unit 130, an adder 140, and an independent operation detection unit 150.

The power factor calculation unit 110 receives the power command P output from the MPPT control unit 4, calculates the invalid power to be injected into the system 5 (hereinafter referred to as injection invalid power Q0), and outputs the power factor calculation unit 110 to the adder 140. The injection invalid power Q0 is calculated based on the power command value P output from the MPPT control unit 4 and the preset operating power factor (for example, 0.96).

In the adder 140, the injection ineffective power Q0 output from the power factor calculation unit 110 and the first injection ineffective power Q1 and the second injection ineffective power Q2, which will be described later, are added. The addition result of the adder 140 is output to the PWM control unit 31 as an invalid power command Q.

The first reactive power calculation unit 120 includes a system frequency measurement unit 121, a frequency deviation calculation unit 122, and an invalid power calculation unit 123.

The system frequency measuring unit 121 measures the frequency of the system voltage (hereinafter referred to as the system frequency).

The frequency deviation calculation unit 122 calculates the frequency deviation based on the system frequency measured by the system frequency measurement unit 121. The method for calculating the frequency deviation is not particularly limited, but is calculated based on, for example, the difference between the past period and the latest period of the system frequency. The moving average of a predetermined period may be used as the past cycle and the latest cycle.

The invalid power calculation unit 123 calculates the first injection invalid power Q1 to be injected into the system based on the frequency deviation calculated by the frequency deviation calculation unit 122. The calculated first injection invalid power Q1 is added to the injection invalid power Q0 by the adder 140. In other words, the first injection reactive power Q1 is the reactive power injected into the system 5 in addition to the injection reactive power Q0 output from the power factor calculation unit 110.

FIG. 2 is a diagram showing the relationship between the frequency deviation calculated by the frequency deviation calculation unit 122 and the first injection ineffective power Q1. As shown in FIG. 2, the gain of the calculation of the injection invalid power Q0 may be changed with a predetermined frequency deviation f (for example, ± 0.01 [Hz]) as a boundary. Further, the upper limit / lower limit of the injection ineffective power Q0 (for example, ± 0.25 [pu]) may be set. The injection timing of the injection ineffective power Q0 is not particularly limited, but is executed within half a cycle after the frequency deviation is detected, for example. When the solitary operation detection device 100 is in a state where it is determined not to detect the solitary operation (hereinafter referred to as a standby state), the first injection ineffective power Q1 is set to zero (0 [p.u. .]).

The second reactive power calculation unit 130 includes a fundamental wave voltage measurement unit 131, a fundamental wave determination unit 132, a harmonic voltage measurement unit 133, a harmonic determination unit 134, and an output unit 135.

The fundamental wave voltage measuring unit 131 calculates the fundamental wave voltage of the system voltage (hereinafter, simply referred to as the fundamental wave voltage) based on the measurement result of the system voltage.

The fundamental wave determination unit 132 determines whether or not the fundamental wave voltage calculated by the fundamental wave voltage measurement unit 131 has a fundamental wave voltage fluctuation that satisfies a predetermined fundamental wave voltage condition. The predetermined fundamental wave voltage condition is a condition for determining whether or not to additionally inject the invalid power, and can be arbitrarily set at the time of designing the grid interconnection system, for example. The fundamental wave determination unit 132 determines whether or not a predetermined fundamental wave voltage condition is satisfied based on whether or not all of the following equations (11) to (16) are satisfied, for example.

(N _b0 −N _ba )> 2.5 [V] ・ ・ ・ (11)
(N _b1- N _ba )> 2.5 [V] ... (12)
(N _b2- N _ba )> -0.5 [V] ... (13)
-0.5 [V] <(N _b3- N _ba ) <0.5 [V] ... (14)
-0.5 [V] <(N _b4- N _ba ) <0.5 [V] ... (15)
-0.5 [V] <(N _b5- N _ba ) <0.5 [V] ... (16)

Here, N _bi (an integer of i = 0 to 5) starts from the latest cycle (0 cycle) and indicates the fundamental wave voltage from that starting point to i cycles before. Further, N _ba is an average value of the fundamental wave voltage in the past predetermined cycle period (for example, 3 cycle period 3 to 5 cycles before the latest cycle).

The harmonic voltage measuring unit 133 calculates the harmonic voltage of the system (hereinafter, simply referred to as the harmonic voltage) based on the measurement result of the system voltage.

The harmonic determination unit 134 determines whether or not the harmonic voltage calculated by the harmonic voltage measuring unit 133 has a harmonic voltage fluctuation that satisfies a predetermined harmonic voltage condition. The predetermined harmonic voltage condition is a condition for determining whether or not to additionally inject the ineffective power, and can be arbitrarily set at the time of designing the grid interconnection system, for example. The harmonic determination unit 134 determines whether or not a predetermined harmonic voltage condition is satisfied based on whether or not all of the following equations (21) to (26) are satisfied, for example.

(N _h0 −N _ha )> 2 [V] ・ ・ ・ (21)
(N _h1- N _ha )> 2 [V] ・ ・ ・ (22)
(N _h2- N _ha )> -0.5 [V] ・ ・ ・ (23)
-0.5 [V] <(N _h3- N _ha ) <0.5 [V] ... (24)
-0.5 [V] <(N _h4- N _ha ) <0.5 [V] ... (25)
-0.5 [V] <(N _h5- N _ha ) <0.5 [V] ... (26)

Here, N _bj (an integer of j = 0 to 5) starts from the latest cycle (0 cycle) and indicates the harmonic voltage j cycles before the starting point. Further, N _ha is an average value of harmonic voltages in a predetermined cycle period in the past (for example, a period of 3 cycles 3 to 5 cycles before the latest cycle).

The output unit 135 outputs the second injection reactive power Q2 set based on the determination results of the fundamental wave determination unit 132 and the harmonic voltage measurement unit 133 to the adder 140. Specifically, the output unit 135 applies a predetermined second injection reactive power Q2 when at least one of the fundamental wave voltage condition of the fundamental wave determination unit 132 and the harmonic voltage condition of the harmonic voltage measurement unit 133 is satisfied. Output. FIG. 1 shows an example in which the output unit 135 is configured by using the OR gate 136 and the selector 137. However, the configuration of the output unit 135 is not limited to the configuration shown in FIG. 1, and may be realized by using another circuit configuration, a program, or the like. The output unit 135 may set the second injection invalid power Q2 to zero (0 [pu]) regardless of the frequency deviation when the independent operation detection device 100 is in the standby state.

FIG. 3 is an example of a power waveform of the second injection invalid power Q2. As shown in FIG. 3, the technique of the present disclosure is characterized in that, as the second injection ineffective power Q2, an ineffective power that gradually increases with a predetermined inclination and gradually decreases with a predetermined inclination is additionally injected. is there. In FIG. 3A, the second injection ineffective power Q2 increases in a linear shape (straight line or ramp shape) up to a maximum value Y (for example, 0.1 [pu]), and then in a linear shape (straight line or ramp shape). An example of a triangular wave that decreases linearly or in a ramp shape is shown. The second injection ineffective power Q2 may be a triangular wave (for example, an isosceles triangle or a regular triangle) in which the inclination when the injection ineffective power increases and the inclination when the injection ineffective power decreases are the same, or the injection is invalid. The slope when the power increases and the slope when the power decreases may be different from each other. For example, in FIG. 1, as shown by the solid line, the slope may be larger when increasing than when decreasing, and as shown by the broken line, the slope may be larger when decreasing than when increasing.

In the second injection reactive power Q2, the increase / decrease of the power waveform may change (increase / decrease) in a curved shape like a sine wave or a quadratic curve. FIG. 3B shows an example in which the power waveform of the second injection reactive power Q2 is a sine wave. Further, as shown in FIG. 3C, the power waveform of the second injection invalid power Q2 may be trapezoidal. The injection time of the second injection ineffective power Q2 is not particularly limited, but is, for example, within 3 cycles (X = 3 in FIG. 3).

The independent operation detection unit 150 detects the independent operation based on the system frequency measured by the system frequency measurement unit 121. The method of detecting the isolated operation is not particularly limited. For example, it is confirmed that the independent operation detection unit 150 is in the independent operation state based on the system frequency measured by the system frequency measurement unit 121, and when the state continues for a predetermined time, the independent operation is detected. It shall be.

Summarizing the above, in the present embodiment, the independent operation is detected through the following steps (1) to (4).

(1) The system frequency measurement unit 121 measures the system frequency, the frequency deviation calculation unit 122 calculates the system frequency deviation based on the system frequency measured by the system frequency measurement unit 121, and the ineffective power calculation unit 123 calculates the system frequency deviation. , A step of calculating the first injection invalid power Q1 from the system frequency deviation calculated by the frequency deviation calculation unit 122.

(2) The fundamental wave voltage measuring unit 131 measures the system voltage (primary wave voltage), and the fundamental wave determination unit 132 measures the system voltage measured by the fundamental wave voltage measuring unit 131, which is the average value of a predetermined plurality of cycles in the past. The step of determining whether or not there is a system voltage fluctuation based on the difference between the measured value and the measured value in the latest predetermined cycle.

(3) The harmonic voltage measuring unit 133 measures the harmonic voltage of the system, and the harmonic determination unit 134 sets the average value of the harmonic voltage measured by the harmonic voltage measuring unit 133 in the past predetermined multiple cycles. A step of determining whether or not there is a fluctuation in the harmonic voltage of the system 5 based on the difference from the measured value in the latest predetermined cycle.

(4) When the system frequency deviation calculated by the frequency deviation calculation unit 122 is below a certain level and the fundamental wave determination unit 132 determines that there is a system voltage fluctuation, or the harmonic determination unit 134 causes a harmonic voltage fluctuation. When it is determined that there is, the first injection ineffective power Q1 calculated by the ineffective power calculation unit 123 and the second injection ineffective power Q2 that gradually increases with a predetermined inclination and gradually decreases with a predetermined inclination. (For example, see FIGS. 3A to 3C) and inject into the system.

As in the present embodiment, in the independent operation detection (invalid power injection method) of the grid interconnection system, the system has a second injection ineffective power Q2 that gradually increases with a predetermined inclination and gradually decreases with a predetermined inclination. By additionally injecting into the system 5, it is possible to suppress the occurrence of a flicker event in the system 5. Hereinafter, a specific description will be given with reference to FIG.

In FIG. 4, (a) is a diagram showing an example of an equivalent circuit between the system 5 and the system interconnection system, and (b) is a diagram showing a change in the vector due to injection of reactive power. c) is a diagram for explaining the change in the waveform due to the injection of the reactive power.

As shown in FIG. 4, there is a line impedance (described as% R and% L in FIG. 4) between the power plant 8 and the grid interconnection system. Further, as shown in FIG. 4, the system may include a phase-advancing capacitor C. Accordingly, in the detection of the isolated operation of the reactive power injection method, adding inject reactive power to the system, a predetermined reactive current I _Q flows in the system 5. Then, as shown in the vector diagram of FIG. 4 (b), the system voltage changes from V (0) to V (1). At this time, when a sharply changing ineffective power is injected as in the conventional technique (for example, the technique of Patent Document 1), the vector changes abruptly as shown by the broken line in FIG. 4 (b). , The system voltage may fluctuate as shown by the broken line in FIG. 4C, or the equipment connected to the system (for example, the equipment constituting the grid interconnection system of the present embodiment) may be adversely affected. There is.

On the other hand, by gradually changing the second injection ineffective power Q2 as in the present embodiment, the change of the vector shown by the broken line in FIG. 4B can be moderated. As a result, as described above, it is possible to suppress the occurrence of a flicker event in the system 5.

In addition, in FIGS. 3A and 3C, the case where the 2nd injection invalid power Q2 rises with a constant inclination and decreases with a constant inclination has been described, but the 2nd injection is invalid in the process of increasing or decreasing. The slope of the power Q2 may change.

(Embodiment 2)
FIG. 5 is a block diagram showing a configuration example of the grid interconnection system of the second embodiment. In FIG. 5, components common to those in FIG. 1 are designated by a common reference numeral. Further, here, the description will be focused on the differences from the first embodiment, and the description of the configuration and operation common to the first embodiment may be omitted.

In the present embodiment (configuration of FIG. 5), the configuration of the block that outputs the second injection invalid power Q2, which is one of the input signals of the adder 140, is different from that of the first embodiment (configuration of FIG. 1). ..

Specifically, in the present embodiment, as shown in FIG. 5, the first additional reactive power Q21 output from the system voltage fluctuation type independent operation detection system 160 and the harmonic fluctuation type independent operation detection system 170 output. The second injection ineffective power Q2 is generated by adding the second additional ineffective power Q22 with the adder 180.

The system voltage fluctuation type independent operation detection system 160 is an independent operation detection system that injects reactive power into the power system as electrical fluctuations indicating system voltage fluctuations in the independent operation state. Specifically, the system voltage fluctuation type independent operation detection system 160 includes a fundamental wave voltage measuring unit 161 and a first additional reactive power calculation unit 162.

The fundamental wave voltage measuring unit 161 calculates the fundamental wave voltage based on the measurement result of the system voltage.

The first additional reactive power calculation unit 162 determines whether or not the electrical fluctuation in the independent operation state is the system voltage fluctuation based on the fundamental wave voltage calculated by the fundamental wave voltage measuring unit 161. Further, the first additional ineffective power calculation unit 162 is added when the system frequency deviation calculated by the frequency deviation calculation unit 122 is below a certain level and the electrical fluctuation in the independent operation state is the system voltage fluctuation. The invalid power Q21 is output to the adder 180. It should be noted that the determination as to whether or not the electrical fluctuation in the isolated operation state is the system voltage fluctuation can be performed in the same manner as the determination as to whether or not the predetermined fundamental wave voltage condition is satisfied in the first embodiment described above. , The detailed description thereof will be omitted here. The first additional reactive power Q21 is an example of the reactive power from the system voltage fluctuation type independent operation detection system.

The harmonic fluctuation type independent operation detection system 170 is an independent operation detection system that injects invalid power into the power system as electrical fluctuations indicating harmonic distortion voltage fluctuations (harmonic fluctuations) in the independent operation state. Specifically, the harmonic fluctuation type independent operation detection system 170 includes a harmonic voltage measuring unit 171 and a second additional reactive power calculation unit 172.

The harmonic voltage measuring unit 171 calculates the harmonic voltage based on the measurement result of the system voltage.

The second additional reactive power calculation unit 172 determines whether or not the electrical fluctuation in the independent operation state is a harmonic fluctuation based on the harmonic voltage calculated by the harmonic voltage measuring unit 171. Further, the second additional ineffective power calculation unit 172 is added when the system frequency deviation calculated by the frequency deviation calculation unit 122 is below a certain level and the electrical fluctuation in the independent operation state is a harmonic fluctuation. The invalid power Q22 is output to the adder 180. It should be noted that the determination as to whether or not the electrical fluctuation in the isolated operation state is the harmonic fluctuation can be performed in the same manner as the determination as to whether or not the predetermined harmonic voltage condition is satisfied in the first embodiment described above. , The detailed description thereof will be omitted here. The second additional reactive power Q22 is an example of the reactive power from the harmonic fluctuation type isolated operation detection system.

The adder 180 adds the first additional ineffective power Q21 and the second additional ineffective power Q22, and outputs the addition result to the adder 140 as the second injection ineffective power Q2. In this embodiment, the adder 140 is an example of an ineffective power adder unit.

The first additional ineffective power Q21 and the second additional ineffective power Q22 are electric powers such that the output (addition result) from the adder 180 gradually increases with a predetermined inclination and gradually decreases with a predetermined inclination. Is set to be. Here, the additional invalid power may be output from only one of the first additional invalid power calculation unit 162 and the second additional invalid power calculation unit 172. Therefore, the first additional ineffective power Q21 and the second additional ineffective power Q22 are predetermined in both the case where the additional ineffective power is output from either one and the case where the additional ineffective power is output and added from both. The electric power gradually increases with an inclination and gradually decreases with a predetermined inclination. The specific shape of the waveform is not particularly limited, but for example, the waveform of FIG. 3A is the same or slightly shifted in timing from both the first additional invalid power calculation unit 162 and the second additional invalid power calculation unit 172. It can be realized by outputting.

Summarizing the above, in the present embodiment, the independent operation is detected through the following steps (1) to (4).

(1) The frequency deviation calculation unit 122 calculates the system frequency deviation based on the measurement result of the system frequency of the system power measured by the system frequency measurement unit 121, and the ineffective power calculation unit 123 is the frequency deviation calculation unit 122. A step of calculating the amount of invalid power from the system frequency fluctuation type independent operation detection system based on the calculated system frequency deviation and outputting it to the adder 140. In this embodiment, the first ineffective power calculation unit 120 is an example of a system frequency fluctuation type independent operation detection system. The system frequency fluctuation type independent operation detection system is an independent operation detection system that injects invalid power into the power system as an electric fluctuation indicating the system frequency fluctuation in the independent operation state.

(2) Output from the system voltage fluctuation type independent operation detection system 160 when the system frequency deviation calculated by the frequency deviation calculation unit 122 is below a certain level and the electrical fluctuation in the independent operation state is the system voltage fluctuation. The step of inputting the first additional reactive power Q21 to the adder 140 via the adder 180.

(3) When the system frequency deviation calculated by the frequency deviation calculation unit 122 is below a certain level and the electrical fluctuation in the independent operation state is a harmonic fluctuation, it is output from the harmonic fluctuation type independent operation detection system 170. The step of inputting the second additional ineffective power Q22 to the adder 140 via the adder 180.

(4) A step of adding the invalid power input by the adder 140 and injecting the added invalid power into the system.

Here, in the first additional ineffective power Q21 and the second additional ineffective power Q22, the second injection ineffective power Q2 output from the adder 180 gradually increases with a predetermined inclination and gradually decreases with a predetermined inclination. It is characterized in that it is set to do. The second injection ineffective power Q2 is the power obtained by adding the first additional ineffective power Q21 and the second additional ineffective power Q22 by the adder 180.

As described above, according to the present embodiment, similarly to the first embodiment, the second injection ineffective power Q2 that gradually increases at a predetermined inclination and gradually decreases at a predetermined inclination is additionally injected into the system. Therefore, it is possible to suppress the occurrence of a flicker event in the system 5.

120 1st invalid power calculation unit (system frequency fluctuation type independent operation detection system)
140 adder (invalid power adder)
160 System voltage fluctuation type independent operation detection system 170 Harmonic fluctuation type independent operation detection system Q1 1st injection invalid power Q2 2nd injection invalid power

Claims (3)

The process of calculating the amount of invalid power from the system frequency fluctuation type independent operation detection system based on the system frequency deviation calculated from the measurement result of the system frequency of the system power and inputting it to the invalid power addition unit.
When the calculated system frequency deviation is below a certain level and the electrical fluctuation in the independent operation state is the system voltage fluctuation, the reactive power from the system voltage fluctuation type independent operation detection system is input to the negative power addition unit. And the process to do
When the calculated system frequency deviation is below a certain level and the electrical fluctuation in the independent operation state is a harmonic fluctuation, the invalid power from the harmonic fluctuation type independent operation detection system is input to the invalid power addition unit. And the process to do
It is an independent operation detection method including a step of adding the invalid power input by the invalid power addition unit and injecting the added invalid power into the system.
The reactive power obtained by adding the reactive power from the system voltage fluctuation type independent operation detection system and the reactive power from the harmonic fluctuation type independent operation detection system gradually increases with a predetermined inclination and gradually increases with a predetermined inclination. A method for detecting isolated operation, which comprises injecting a reduced amount of reactive power. In the isolated operation detection method according to claim 1,
A method for detecting isolated operation, wherein the waveform of the injected reactive power is any one of a sine wave, a triangular wave, and a trapezoidal wave. It is an independent operation detection method of the invalid power injection method.
The process of measuring the system frequency, calculating the system frequency deviation based on the measured system frequency, and calculating the first injection invalid power from the calculated system frequency deviation,
A process of measuring the system voltage and determining whether or not there is a system voltage fluctuation for the measured system voltage based on the difference between the average value of a predetermined plurality of cycles in the past and the measured value in the latest predetermined cycle. When,
The harmonic voltage of the system is measured, and for this measured harmonic voltage, the fluctuation of the harmonic voltage of the system is based on the difference between the average value of the past predetermined multiple cycles and the measured value in the latest predetermined cycle. The process of determining whether or not there is
When the calculated system frequency deviation is below a certain level and there is a system voltage fluctuation or a harmonic voltage fluctuation, the first injection reactive power is gradually increased with a predetermined gradient and with a predetermined gradient. Including a step of adding a second injection reactive power that gradually decreases and injecting into the system,
A method for detecting isolated operation.

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