JP5702055B2 - Power oscillation suppression device, power oscillation suppression method, and power oscillation control program - Google Patents

Description

  The present invention relates to a power oscillation suppression device, a power oscillation suppression method, and a power oscillation control program.

  Conventionally, maintenance of system stability has been an important issue in power transmission from remote locations. As a countermeasure with the highest cost-effectiveness for this problem, super-fast response excitation control with a power system stabilization device is mainly used. Here, the power system stabilizer (PSS: Power System Stabilizer) is generated in the power system by controlling the excitation (field) voltage of the generator based on the active power P and the rotational speed ω of the generator. This device suppresses power fluctuation.

  Specifically, the PSS detects fluctuations generated in the generator (power system) based on the active power P and the rotational speed ω of the generator. The PSS outputs a control signal (auxiliary signal) for controlling the field voltage to an automatic voltage regulator (AVR) provided in the generator according to the magnitude of power fluctuation. , Suppress the power fluctuation of the generator. Such PSS includes various types according to the type of input signal that is input as a signal indicating the state of the generator. For example, PSS includes “ΔP type PSS” for inputting active power P, and “ΔP + ω type PSS” for inputting active power P and rotational speed ω of a generator.

  In recent years, “Multi-input Power System Stabilizer (MPSS)” is highly effective in suppressing weak braking long-period power fluctuations (power fluctuations with a period of about 2 seconds or more) in a long-distance high-power transmission system. Has also been developed (see Non-Patent Documents 1 to 7, for example). This MPSS newly adds a reactive power Q, a changing speed dP of the active power P, and a changing speed dEa of the terminal voltage Ea as input signals without changing the constants of the already installed ΔP + Δω type PSS. It is a thing.

  Here, the reactive power Q, the active power change rate dP, and the terminal voltage change rate dEa added as input signals to the MPSS are signals that reduce the field voltage immediately after the system fault is removed. (Hereinafter referred to as “voltage drop signal”). This voltage drop signal is a factor that reduces the transient stability of the power system. Therefore, the MPSS is provided with “transient stability improvement logic” which is a circuit for canceling the voltage drop signal.

  In order to cancel the voltage drop signal, the transient stability improvement logic outputs a control signal to the AVR that increases the field voltage to the upper limit value (top voltage or ceiling voltage) when the system fault is removed. Specifically, the transient stability improvement logic determines that a system fault has occurred when the terminal voltage of the generator falls below a predetermined value, and when the system fault is removed, Increase the magnetic voltage to the upper limit.

Kitauchi, Taniguchi, “Development of multi-input PSS (P + ω + Q type) for long-period oscillation suppression”, Research Institute of Electric Power Research Institute T96021, May 1997 Kitauchi, Taniguchi, Shirasaki, Ichikawa, Amano, Hijo, “Effects of applying multi-input PSS to power system”, IEEJ Power System Technical Meeting, PSE-98-6, 1998 Kitauchi, Taniguchi, Yoshimura, Shirasaki, Ichikawa, Amano, Hiroki, “Constant setting method and verification of multi-input PSS for long-period oscillation suppression,” Central Research Institute of Electric Power Research Report T96030, April 1999 Y. Kitauchi, H. Taniguchi, T. Shirasaki, Y. Ichikawa, M. Amamo, M. Banjo, "Experimental Verification of Multi-input PSS with Reactive Power Input for Damping Low Frequency Power Swing", IEEE Transactions on Energy Conversion Vol . 14, No. 4, December 1999 Kitauchi, Taniguchi, Shirasaki, Ichikawa, Amano, Hiroki, “Constant setting method of multi-input PSS for long-period oscillation suppression in multi-machine system and its experimental verification”, Denki B, Vol. January 2002 Morita, Inamura, Fuse, Tsukada, Kitauchi, "About field verification of multi-input PSS", IEEJ, Power Technology / Power System Technology Joint Study Group, PE-03-115 / PSE-03-126, Heisei 15 ( 2003) Kitauchi, “Development of a generator excitation control system for improving the stability of long-distance high-power transmission systems”, Central Research Institute of Electric Power Industry T76, March 2004

  However, the conventional MPSS described above has a problem that power fluctuation cannot be effectively suppressed when a far end accident or an unbalanced accident occurs as described below.

  As described above, the transient stability improving logic raises the field voltage to the upper limit value when a system fault that causes the terminal voltage to become a predetermined value or less is removed. However, when a remote end accident or an unbalanced accident occurs in the power system, the terminal voltage of the generator may not decrease to a predetermined value. Therefore, in the conventional MPSS, the transient stability improvement logic may not operate even when a far end accident or an unbalanced accident occurs.

  That is, the conventional MPSS can cope with a system fault at the closest end of the generator in which the terminal voltage is greatly reduced, but cannot cope with a far end accident or an unbalanced accident. Therefore, the conventional MPSS cannot output a control signal of an appropriate magnitude to the AVR when a far end accident or an unbalanced accident occurs, and can effectively suppress power fluctuation. There wasn't.

  The above-mentioned problem occurs not only in the MPSS that controls the generator excitation system, but also in the above-described ΔP-type PSS and ΔP + ω-type PSS.

  The present invention has been made in view of the above, and even when a far-end accident or an unbalanced accident occurs, a power oscillation control device, a power oscillation control method, and the like that can effectively suppress power oscillation, An object is to provide a power oscillation control program.

In order to solve the above-described problems and achieve the object, the present invention provides a power fluctuation suppression device that suppresses power fluctuation generated in an electric power system, in which active power and invalidity of a power device connected to the electric power system are reduced. A power factor angle calculating means for calculating a power factor angle from electric power, and a system fault has occurred in the power system when the change rate of the power factor angle calculated by the power factor angle calculating means exceeds a predetermined value. An accident determination means for determining, and when the accident determination means determines that the system fault has occurred, a value of an input signal indicating an output state of the power device is less than 0 for a predetermined period after the accident occurs Based on the signal obtained by removing the voltage reduction signal as a signal from the input signal, a control signal for stabilizing the power fluctuation of the power device is output, and after the predetermined period, the input signal including the voltage reduction signal Based on There are, characterized in that a power oscillation control means for outputting a control signal for stabilizing the power oscillations of the power equipment.

Further, the present invention is a power fluctuation suppressing method for suppressing power fluctuation generated in an electric power system, the step of calculating a power factor angle from active power and reactive power of a power device connected to the electric power system, A step of determining that a system fault has occurred in the power system when the power factor angle change speed exceeds a predetermined value; and a step after the accident has occurred when it is determined that the system fault has occurred. Control for stabilizing power fluctuation of the power device based on a signal obtained by removing from the input signal a voltage drop signal that is a signal having a value less than 0 among the input signals indicating the output state of the power device A step of outputting a control signal for stabilizing power fluctuation of the power device based on the first control signal adjustment procedure to be output as a signal and the input signal including the voltage drop signal after the predetermined period has elapsed. Characterized in that it contains a flop.

Further, the present invention is a power fluctuation suppression program for suppressing power fluctuation generated in a power system, and calculates a power factor angle from active power and reactive power of a power device connected to the power system. An accident determination procedure for determining that a system fault has occurred in the power system when a change rate of the power factor angle calculated by the procedure, the power factor angle calculation procedure exceeds a predetermined value, and the accident determination procedure When it is determined that the system fault has occurred , a voltage lowering signal that is a signal having a value less than 0 among the input signals indicating the output state of the electric power device is output from the input signal for a predetermined period after the accident occurs. based on the exception signal, a first control signal adjustment procedure for outputting the power oscillations of the power apparatus as a control signal to stabilize, after the predetermined period, based on the input signal including the voltage lowering signal There are, characterized in that to execute a second control signal adjusting steps for outputting a control signal to stabilize the power oscillations of the power device to the computer.

  According to the present invention, even when a far end accident or an unbalanced accident occurs, there is an effect that power fluctuation can be effectively suppressed.

FIG. 1 is a block diagram illustrating the configuration of the MPSS according to the first embodiment. FIG. 2 is a block diagram showing the configuration of the FD circuit shown in FIG. FIG. 3 is a flowchart illustrating the processing procedure of the voltage fluctuation control by the MPSS according to the first embodiment. FIG. 4 is a diagram (1) for explaining the effect of power fluctuation suppression by the MPSS according to the first embodiment. FIG. 5 is a diagram (2) for explaining the effect of power fluctuation suppression by the MPSS according to the first embodiment. FIG. 6 is a diagram (3) for explaining the effect of power fluctuation suppression by the MPSS according to the first embodiment. FIG. 7 is a block diagram illustrating the configuration of the ΔP + Δω type PSS according to the second embodiment. FIG. 8 is a block diagram showing a configuration of the FD circuit shown in FIG. FIG. 9 is a diagram (1) for explaining the effect of power fluctuation suppression by the ΔP + Δω type PSS according to the second embodiment. FIG. 10 is a diagram (2) for explaining the effect of power fluctuation suppression by the ΔP + Δω type PSS according to the second embodiment. FIG. 11 is a diagram (3) for explaining the effect of power fluctuation suppression by the ΔP + Δω type PSS according to the second embodiment.

  Hereinafter, embodiments of a power oscillation suppression device, a power oscillation suppression method, and a power oscillation control program according to the present invention will be described in detail with reference to the drawings. Below, the case where this invention is applied to MPSS and (DELTA) P + (DELTA) omega type PSS is demonstrated. In addition, this invention is not limited by the Example demonstrated here.

  First, as a first embodiment, a case where the present invention is applied to MPSS will be described. The MPSS according to the first embodiment inputs the active power P, the rotational speed ω, the reactive power Q, the change speed dP of the active power P, and the change speed dEa of the terminal voltage Ea. And MPSS stabilizes the electric power fluctuation of a generator by outputting the control signal for controlling a field voltage with respect to AVR with which a generator is provided based on the input signal.

  First, the configuration of the MPSS according to the first embodiment will be described. FIG. 1 is a block diagram illustrating the configuration of the MPSS according to the first embodiment. As shown in FIG. 1, the MPSS according to the first embodiment includes reset circuits 11 to 13, incomplete differentiation circuits 14 to 15, phase adjustment circuits 21 to 23, gains 31 to 35, and a circuit 40 that allows only positive values to pass. , A circuit 50 for passing only negative values, a limiter 60, a system fault detection (FD) circuit 70, adders 81 to 84, and a multiplier 91.

  The reset circuit 11 receives an active power P of a generator (not shown) and outputs an active power deviation ΔP that is a deviation of the active power P from a steady state. The transfer function of the reset circuit 11 is -s / (1 + s). The reset circuit 12 receives the rotational speed ω of the generator and outputs a rotational speed speed deviation Δω that is a deviation of the rotational speed ω from the steady state. The transfer function of the reset circuit 12 is 5 s / (1 + 5 s). The reset circuit 13 inputs the reactive power Q of the generator and outputs a reactive power deviation ΔQ that is a deviation of the input reactive power Q from a steady state. The transfer function of the reset circuit 13 is 5 s / (1 + 5 s).

  The incomplete differentiation circuit 14 receives the terminal voltage Ea of the generator and outputs a terminal voltage change rate dEa that is a change rate of the input terminal voltage Ea. The transfer function of the incomplete differentiation circuit 14 is −0.1 s / (1 + 0.1 s). The incomplete differentiation circuit 15 receives the active power deviation ΔP output from the reset circuit 11 and outputs the change rate dP of the input active power deviation ΔP. The transfer function of the incomplete differentiation circuit 15 is 0.1 s / (1 + 0.1 s).

  The phase adjustment circuit 21 receives the active power deviation ΔP output from the reset circuit 11 and adjusts the phase of the input active power deviation ΔP. The phase adjustment circuit 22 receives the rotational speed deviation Δω output from the reset circuit 12 and adjusts the phase of the input rotational speed deviation Δω. The phase adjustment circuit 23 receives the reactive power deviation ΔQ output from the reset circuit 13 and adjusts the phase of the input reactive power deviation ΔQ.

  The gain 31 receives the terminal voltage change rate dEa output from the reset circuit 14 and multiplies the input terminal voltage change rate dEa by a gain constant KdEa. Here, the gain constant KdEa = 1. The gain 32 receives the active power change rate dP output from the reset circuit 15 and multiplies the input active power change rate dP by a gain constant KdP. Here, the gain constant KdP = 1. The gain 33 receives the active power deviation ΔP output from the phase adjustment circuit 21 and multiplies the input active power deviation ΔP by a gain constant Kp. Here, the gain constant Kp = 0.7, but this value may be adjusted to an appropriate value depending on the configuration of the power system and the power flow conditions.

The gain 34 receives the rotational speed deviation Δω output from the phase adjustment circuit 22 and multiplies the input rotational speed deviation Δω by a gain constant Kω. Here, the gain constant Kω = 8.
The gain 35 receives the reactive power deviation ΔQ output from the phase adjustment circuit 23 and multiplies the input reactive power deviation ΔQ by a gain constant Kq. Here, although the gain constant Kq = 0.08, this value may be adjusted to an appropriate value depending on the configuration of the power system and the power flow conditions.

  The adding unit 81 adds the active power deviation ΔP output from the gain 33 and the rotational speed deviation Δω output from the gain 34. The adder 82 adds the terminal voltage change rate dEa output from the gain 31, the active power change rate dP output from the gain 32, and the reactive power deviation ΔQ output from the gain 35.

  The circuit 40 that passes only a positive value receives the signal (ΔQ + dEa + dP) output from the adder 82 and extracts only the positive component (positive value signal) included in the input signal (ΔQ + dEa + dP). The circuit 50 that passes only negative values receives the signal (ΔQ + dEa + dP) output from the adder 82 and extracts only the negative component (negative value signal) included in the input signal (ΔQ + dEa + dP).

  The FD circuit 70 performs control so as to cancel the negative component of the control signal output by the MPSS for a predetermined period after the occurrence of the system failure when the system failure occurs in the power system. The FDD circuit 70 will be specifically described later.

  The multiplier 91 multiplies the negative component of the signal (ΔQ + dEa + dP) output from the circuit 50 that passes only negative values by the control signal FDgain output from the FD circuit 70. The adder 83 adds the positive component of the signal (ΔQ + dEa + dP) output from the circuit 40 that passes only positive values and the negative component of the signal (ΔQ + dEa + dP) output from the multiplier 91, and obtains the resulting signal (ΔQ + dEa + dP) is output. The adder 84 adds the signal (ΔP + Δω) output from the adder 81 and the signal (ΔQ + dEa + dP) output from the adder 83.

  The limiter 60 receives the signal output from the adder 84 and extracts a component having a magnitude from −0.1 to +0.1 included in the input signal. Then, the limiter 60 outputs the extracted signal as a control signal to the AVR (PSS output). Here, the control signal output by the limiter 60 is added to a portion for setting the voltage setting value of the AVR, and is used for controlling the field voltage.

  Next, the configuration of the FD circuit 70 shown in FIG. 1 will be described. FIG. 2 is a block diagram showing a configuration of FD circuit 70 shown in FIG. As illustrated in FIG. 2, the FD circuit 70 includes a power factor angle calculation unit 71, a reset circuit 72, an accident determination unit 73, and a control signal adjustment unit 74.

  The power factor angle calculation unit 71 calculates the power factor angle θ from the active power P and the reactive power Q of the generator. Specifically, the power factor angle calculation unit 71 calculates the power factor angle θ based on the following equation (1).

  The reset circuit 72 calculates a power factor angle change speed Δθ that is a change speed of the power factor angle θ calculated by the power factor angle calculator 71. Specifically, the reset circuit 72 calculates the power factor angle change speed Δθ by the following equation (2).

  The accident determination unit 73 determines that a system fault has occurred in the power system when the power factor angle change speed Δθ calculated by the reset circuit 72 exceeds a predetermined value.

  In general, when a system fault occurs in an ultra-high-voltage power transmission system, since there is almost no resistance in the transmission line, the active power P of the generator rapidly decreases to almost zero. In addition, since most of the short-circuit current is reactive current, the reactive power Q increases rapidly.

  Therefore, specifically, the accident determination unit 73 determines that a system fault has occurred when the power factor angle change speed Δθ calculated by the reset circuit 72 exceeds 10 degrees. Further, the accident determination unit 73 determines that no system fault has occurred when the power factor angle change speed Δθ calculated by the reset circuit 72 does not exceed 10 degrees. In general, even when the generator is shaken after the occurrence of an accident, the power factor angle change speed Δθ is several degrees at most, so here the operating threshold of the FD circuit 70 is set to 10 degrees. Is set.

  The reset circuit 72 described above calculates the power factor angle change speed Δθ with a transfer function having a time constant of 0.1 seconds. Therefore, the accident determination unit 73 determines that a system fault has occurred only when a rapid change occurs in the power factor angle θ, and does not react to a steady variation in the power factor angle θ. Therefore, it is possible to accurately detect a far end accident or an unbalanced accident.

  When the accident determination unit 73 determines that a system fault has occurred, the control signal adjustment unit 74 performs control so as to cancel the negative component of the control signal output by the MPSS for a predetermined period after the accident occurs.

  Specifically, the control signal adjustment unit 74 has an FDtimer for controlling the magnitude of the control signal. Then, the control signal adjustment unit 74 sets FDgain, which is an output signal of the FD circuit, to “0” and sets the FDtimer to “0” when the accident determination unit 73 determines that a system fault has occurred. Later, FDtimer is started. Thereafter, the control signal adjustment unit 74 sets the size of the FDgain to “0” for 2 seconds after starting the FDtimer.

  Here, while “0” is set to FDgain by the control signal adjustment unit 74, the negative component of the signal (ΔQ + dEa + dP) output from the circuit 50 that passes only a negative value as a result of multiplication by the multiplication unit 91. Canceled by FDgain. Thus, for 2 seconds after the occurrence of the accident, the voltage reduction signal output by the reactive power Q, the change rate dP of the active power, and the change rate dEa of the terminal voltage immediately after the removal of the grid fault can be set to “0”.

  Then, the control signal adjustment unit 74 returns FDgain at a speed of 0.5 per second after 2 seconds have elapsed since the start of the FDtimer. That is, the control signal adjustment unit 74 returns FDgain to “1” over 2 seconds after 2 seconds have elapsed since the start of the FDtimer.

  In the first embodiment, it is assumed that the power oscillation period is a maximum of 4 seconds, and a negative value signal is output from the (ΔQ + dEa + dP) portion of MPSS for 2 seconds when the internal phase difference angle δ after the removal of the system fault is increased. It is not output.

  Even if the power factor angle change speed Δθ exceeds 10 degrees for a moment due to noise or small disturbance, the FD circuit 70 only suppresses the negative value of the signal (ΔQ + dEa + dP). Therefore, the ΔP + Δω type PSS part included in the MPSS operates as usual.

  Next, a processing procedure of power fluctuation control by MPSS according to the first embodiment will be described. Here, the description will focus on the processing performed by each part of the FD circuit 170. FIG. 3 is a flowchart illustrating a processing procedure of power fluctuation control by MPSS according to the first embodiment.

  As shown in FIG. 3, in the MPSS according to the first embodiment, first, the power factor angle calculation unit 71 calculates the power factor angle θ from the active power P and the reactive power Q of the generator (step S1). Subsequently, the reset circuit 72 calculates a power factor angle change speed Δθ that is a change speed of the power factor angle θ calculated by the power factor angle calculator 71 (step S2).

  If the power factor angle change speed Δθ is greater than 10 degrees (step S3, Yes), the accident determination unit 73 determines that a system fault has occurred. When the accident determination unit 73 determines that a system fault has occurred, the control signal adjustment unit 74 sets FDgain to “0” and FDtimer to “0”, and then activates the FDtimer (step S4). Thereby, the addition of the timer value by the FDtimer is started.

  Thus, every time the FD circuit 70 calculates the power factor angle change speed Δθ larger than 10 degrees, the FD timer is set to “0” and restarted, thereby continuously causing system faults. Even in this case, the suppression of the voltage drop signal can be continued.

  After starting the FDtimer, the control signal adjustment unit 74 moves the process to step S1. Then, the control signal adjustment unit 74 increases the timer value of the FDtimer as time passes while the FDtimer is activated.

  On the other hand, when the power factor angle change speed Δθ is 10 degrees or less (step S3, No), the accident determination unit 73 determines that no system fault has occurred. When the accident determination unit 73 determines that no system fault has occurred, the control signal adjustment unit 74 determines whether the FDtimer is being activated. Here, when the FDtimer is not activated (step 5, No), the control signal adjustment unit 74 shifts the processing to step S1.

  If the FDtimer has been activated (step 5, Yes), the control signal adjustment unit 74 determines whether the FDtimer has reached 2 seconds. If the FD timer has not reached 2 seconds (step S6, Yes), the control signal adjustment unit 74 sets FDgain to “0” (step S7). Thereafter, the control signal adjustment unit 74 proceeds to step S1. That is, the value of FDgain is “0” until FDtimer reaches 2 seconds.

  If the FDtimer has reached 2 seconds (step S6, No), the control signal adjustment unit 74 determines whether the FDtimer has reached 4 seconds. If the FDtimer has not reached 4 seconds (step S8, Yes), the control signal adjustment unit 74 sets FDgain to (FDtimer-2) × 0.5 (step S9). Thereafter, the control signal adjustment unit 74 proceeds to step S1. As a result, the FDgain value gradually increases at a rate of 0.5 per second until the FDtimer exceeds 2 seconds and reaches 4 seconds.

  If the FDtimer has reached 4 seconds (step S8, No), the control signal adjustment unit 74 stops the FDtimer (step S10). Thereby, the addition of the timer value by the FDtimer is stopped. Also, since the FDtimer has reached 4 seconds, the value of the FDgain has returned to “1”. Thereafter, the control signal adjustment unit 74 proceeds to step S1. That is, after FDtimer reaches 4 seconds, the value of FDgain becomes “1”.

  Next, the effect of power fluctuation suppression by the MPSS according to the first embodiment will be described. FIGS. 4-6 is a figure for demonstrating the effect of the power fluctuation suppression by MPSS which concerns on the present Example 1. FIG. Here, the MPSS according to the first embodiment is referred to as “improved MPSS”, and the conventional MPSS is referred to as “conventional MPSS”.

  Here, in the power system shown in FIG. 4, the improved MPSS was applied to a 100 kVA generator, and the stability improvement effect was verified. As a result, as shown in FIGS. 5 and 6, the improved MPSS has a maximum value of the internal phase difference angle δ as compared with the conventional MPSS because the FD circuit operates appropriately against a far end accident and an unbalanced accident. It was confirmed that damping (braking) was excellent.

  Further, as shown in the following table, the improved MPSS was able to improve the marginal transmission power by about 6% compared with the current ΔP + Δω type PSS.

  As described above, in the first embodiment, the power factor angle calculation unit 71 calculates the power factor angle θ from the active power P and the reactive power Q, and the reset circuit 72 has a change rate of the power factor angle θ. The power factor angle change speed Δθ is calculated. Further, the accident determination unit 73 determines that a system fault has occurred in the power system when the power factor angle change speed Δθ exceeds a predetermined value. Then, when it is determined that a system fault has occurred, the control signal adjustment unit 74 performs control so as to cancel the negative component of the control signal output by the MPSS for a predetermined period after the accident occurs. That is, according to the first embodiment, it is possible to suppress the voltage drop signal output by the reactive power Q, the active power change rate dP, and the terminal voltage change rate dEa immediately after the removal of the system fault. Therefore, even when a far end accident or an unbalanced accident occurs, it is possible to effectively suppress power fluctuation.

  In the first embodiment, the reset circuit 72 inputs the power factor angle θ calculated by the power factor angle calculator 71 and outputs a power factor angle change rate Δθ that is a change rate of the input power factor angle θ. To do. Then, the accident determination unit 73 determines that a system fault has occurred when the power factor angle change speed Δθ output from the reset circuit 72 exceeds a predetermined value. Therefore, according to the first embodiment, since it is determined that a system fault has occurred only when the power factor angle θ changes rapidly, it is possible to accurately detect a far end accident or an unbalanced accident. is there.

  Next, a case where the present invention is applied to a ΔP + Δω type PSS will be described as a second embodiment. The ΔP + Δω type PSS is suitable for suppressing short-period power fluctuation (power fluctuation with a period of about 1 second) in a local system and weakly long-period power fluctuation (power fluctuation with a period of about 2 seconds or more) in a wide-area system. . In the ΔP + Δω type PSS, it is known that the ΔP type PSS part outputs a voltage lowering signal for reducing the terminal voltage of the generator immediately after the system fault is removed. According to the present invention, this voltage drop signal can be suppressed.

  First, the configuration of the ΔP + Δω type PSS according to the second embodiment will be described. FIG. 7 is a block diagram illustrating the configuration of the ΔP + Δω type PSS according to the second embodiment. This ΔP + Δω type PSS inputs an active power P and a rotational speed ω of a generator (not shown). Then, the ΔP + Δω type PSS outputs a control signal for controlling the field voltage to the AVR included in the generator based on the input signal, thereby stabilizing the power fluctuation of the generator.

  As shown in FIG. 7, the ΔP + Δω type PSS according to the second embodiment has reset circuits 111 and 112, phase adjustment circuits 121 and 122, gains 131 and 132, a circuit 140 that allows only positive values to pass, and only negative values that pass. Circuit 150, limiter 160, system fault detection (FD) circuit 170, adders 181 and 182, and multiplier 191.

  The reset circuit 111 receives a rotational speed ω of a generator (not shown) and outputs a rotational speed speed deviation Δω that is a speed deviation of the rotational speed ω. The transfer function of the reset circuit 111 is 5 s / (1 + 5 s). The reset circuit 112 receives the active power P of the generator and outputs an active power deviation ΔP that is a deviation of the active power P. The transfer function of the reset circuit 112 is -s / (1 + s).

  The phase adjustment circuit 121 receives the rotational speed deviation Δω output from the reset circuit 111 and adjusts the phase of the input rotational speed deviation Δω. The phase adjustment circuit 122 receives the active power deviation ΔP output from the reset circuit 112 and adjusts the phase of the input active power deviation ΔP.

  The gain 131 receives the rotational speed deviation Δω output from the phase adjustment circuit 121 and multiplies the input rotational speed deviation Δω by a gain constant Kω. Here, the gain constant Kω = 8, but this value may be adjusted to an appropriate value depending on the configuration of the power system and the power flow conditions. The gain 132 receives the active power deviation ΔP output from the phase adjustment circuit 122 and multiplies the input active power deviation ΔP by a gain constant Kp. Here, the gain constant Kp = 0.7, but this value may be adjusted to an appropriate value depending on the configuration of the power system and the power flow conditions.

  The circuit 140 that passes only a positive value receives the active power deviation ΔP output from the gain 132 and extracts only the positive component (positive value signal) included in the input active power deviation ΔP. The circuit 150 that passes only negative values receives the active power deviation ΔP output from the gain 132 and extracts only the negative component (negative value signal) included in the input active power deviation ΔP.

  When a system fault occurs in the power system, the FD circuit 170 performs control so as to cancel the negative component of the control signal output by the ΔP-type PSS portion of the ΔP + Δω-type PSS for a predetermined period after the accident occurs. The FD circuit 170 will be specifically described later.

  Multiplier 191 multiplies the negative component of active power deviation ΔP output from circuit 150 that allows only negative values to pass through by control signal FDgain output from FD circuit 170. The adder 181 adds the positive component of the active power deviation ΔP output from the circuit 140 that passes only positive values and the negative component of the active power deviation ΔP output from the multiplier 191 and obtains the result. The active power deviation ΔP is output. Adder 182 adds rotation speed deviation Δω output from gain 131 and active power deviation ΔP output from adder 181.

  The limiter 160 receives the signal output from the adder 182 and extracts a component having a magnitude from −0.1 to +0.1 included in the input signal. The limiter 160 outputs the extracted signal as a control signal to the AVR (PSS output). Here, the control signal output from the limiter 160 is used to control the field voltage by AVR.

  Next, the configuration of the FD circuit 170 illustrated in FIG. 7 will be described. FIG. 8 is a block diagram showing a configuration of FD circuit 170 shown in FIG. As illustrated in FIG. 8, the FD circuit 170 includes a power factor angle calculation unit 171, a reset circuit 172, an accident determination unit 173, and a control signal adjustment unit 174. The functions of power factor angle calculation unit 171, reset circuit 172, and accident determination unit 173 are the same as the functions of power factor angle calculation unit 71, reset circuit 72, and accident determination unit 73 shown in FIG. The description is omitted here.

  When the accident determination unit 173 determines that a system fault has occurred, the control signal adjustment unit 174 calculates a negative component of the control signal output by the ΔP type PSS portion of the ΔP + Δω type PSS for a predetermined period after the occurrence of the accident. Control to cancel.

  Specifically, the control signal adjustment unit 174 has an FD timer for controlling the magnitude of the control signal. When the FD timer is started by the accident determination unit 173, the FD circuit is then used for 0.4 seconds. The size of FDgain, which is the output signal of, is set to “0”.

  Here, while “0” is set to FDgain by the control signal adjustment unit 174, the negative component of the active power deviation ΔP output from the circuit 150 that passes only negative values as a result of multiplication by the multiplication unit 191 is Canceled by FDgain. Thereby, for 0.4 seconds after the occurrence of the accident, the voltage reduction signal output by the ΔP-type PSS portion immediately after the removal of the system accident can be made zero.

  Then, the control signal adjustment unit 174 returns FDgain to 1 over 0.4 seconds after 0.4 seconds have elapsed since the start of FDtimer.

  In the second embodiment, in consideration of the increase rate of the active power P after removal of the grid fault, both the time for setting the FDgain to “0” and the time taken for returning the FDgain to 1 are set to 0. 0. 4 seconds. This time can be extended or shortened according to the increasing speed of the active power P after the accident is removed.

  Even if the power factor angle change rate Δθ exceeds 10 degrees for a moment due to noise or small disturbance, the FD circuit 170 only suppresses the negative value of the signal output by the ΔP-type PSS portion. . Therefore, the Δω-type PSS part included in the ΔP + Δω-type PSS operates as usual.

  Note that the processing procedure of power fluctuation control by the ΔP + Δω type PSS according to the second embodiment is basically the same as the processing procedure shown in FIG. Specifically, the time required to set FDgain to “0” and the time taken to return FDgain to 1 were 2 seconds in the first embodiment, whereas each time was 0 in the second embodiment. The only difference is that it is 4 seconds.

  Next, the effect of power fluctuation suppression by the ΔP + Δω type PSS according to the second embodiment will be described. FIGS. 9-11 is a figure for demonstrating the effect of the power fluctuation suppression by (DELTA) P + (DELTA) omega type PSS which concerns on the present Example 2. FIG. Here, the ΔP + Δω type PSS according to the second embodiment is referred to as “ΔP + Δω type PSS with FD circuit”, and the conventional ΔP + Δω type PSS is referred to as “active ΔP + Δω type”.

  Here, in the power system shown in FIG. 9, a ΔP + Δω type PSS with an FD circuit was applied to a 100 kVA generator, and the stability improvement effect was verified. As a result, as shown in FIG. 10, the ΔP + Δω type PSS with the FD circuit operates the FD circuit appropriately with respect to the far end accident and the unbalanced accident. The value was suppressed and it was confirmed that damping (braking) was excellent. Moreover, as shown in FIG. 11, it can be seen that the voltage drop signal immediately after the system fault is suppressed by the FD circuit by the ΔP + Δω type PSS with the FD circuit.

  Further, as shown in the following table, the ΔP + Δω type PSS with the FD circuit was able to improve the marginal transmission power by about 3% compared with the working ΔP + Δω type PSS.

  Here, in the power system shown in FIG. 4, the improved MPSS was applied to a 100 kVA generator, and the stability improvement effect was verified. As a result, as shown in FIG. 5, the improved MPSS suppresses the maximum value of the internal phase difference angle δ as compared with the conventional MPSS by appropriately operating the FD circuit against a far end accident and an unbalanced accident. In addition, it was confirmed that damping (braking) was excellent. Further, as shown in the following table, the improved MPSS was able to improve the marginal transmission power by about 6% compared with the current ΔP + Δω type PSS.

  As described above, in the second embodiment, the power factor angle calculation unit 171 calculates the power factor angle θ from the active power P and the reactive power Q, and the reset circuit 172 has a change rate of the power factor angle θ. The power factor angle change speed Δθ is calculated. In addition, the accident determination unit 173 determines that a system fault has occurred in the power system when the power factor angle change speed Δθ exceeds a predetermined value. When the control signal adjustment unit 174 determines that a system fault has occurred, the control signal adjustment unit 174 cancels the negative component of the control signal output by the ΔP-type PSS portion of the ΔP + Δω-type PSS for a predetermined period after the accident occurs. Control. That is, according to the second embodiment, it is possible to suppress the voltage drop signal output by the ΔP-type PSS portion immediately after removal of the system fault. Therefore, even when a far end accident or an unbalanced accident occurs, it is possible to effectively suppress power fluctuation.

  In the second embodiment, the reset circuit 172 inputs the power factor angle θ calculated by the power factor angle calculator 171 and outputs a power factor angle change rate Δθ that is a change rate of the input power factor angle θ. To do. The accident determination unit 173 determines that a system fault has occurred when the power factor angle change speed Δθ output from the reset circuit 172 exceeds a predetermined value. Therefore, according to the second embodiment, since it is determined that a system fault has occurred only when the power factor angle θ changes rapidly, it is possible to accurately detect a far end accident or an unbalanced accident. is there.

  In the above embodiment, the case where the present invention is applied to the PSS that controls the excitation system of the generator has been described, but the present invention is not limited to this. For example, the present invention can be similarly applied to other power fluctuation suppression devices that suppress power fluctuation generated in the power system. That is, the same effect as that described in the above embodiment can be obtained as long as the power fluctuation suppressing device outputs a voltage lowering signal.

  In addition, all or some of the processing functions of the devices described in the above embodiments can be realized as software by a CPU and a program that is analyzed and executed by the CPU. That is, the power fluctuation suppressing method described in the above embodiment can be realized by executing a program prepared in advance by a computer such as a personal computer or a workstation or a digital signal processor (DSP). This program can be distributed via a network such as the Internet. The program can also be executed by being recorded on a computer-readable recording medium such as a hard disk, a flexible disk (FD), a CD-ROM, an MO, and a DVD and being read from the recording medium by the computer.

11-13, 111, 112 Reset circuit 14-15 Incomplete differentiation circuit 21-23, 121, 122 Phase adjustment circuit 31-35, 131, 132 Gain 40, 140 Circuit that allows only positive values to pass 50, 150 Negative value 60,160 Limiter 70,170 System fault detection circuit (FD circuit)
71,171 Power factor angle calculation unit 72,172 Reset circuit 73,173 Accident determination unit 74,174 Control signal adjustment unit 81-84,181,182 Addition unit 91,191 Multiplication unit

Claims (7)

A power fluctuation suppressing device for suppressing power fluctuation generated in an electric power system,
Power factor angle calculating means for calculating a power factor angle from active power and reactive power of the power equipment connected to the power system;
An accident determination means for determining that a system fault has occurred in the electric power system when the change rate of the power factor angle calculated by the power factor angle calculation means exceeds a predetermined value;
When it is determined by the accident determination means that the system fault has occurred , a voltage lowering signal that is a signal having a value of less than 0 among the input signals indicating the output state of the power device for a predetermined period after the occurrence of the accident. Based on the signal removed from the input signal, a control signal that stabilizes power fluctuation of the power device is output, and after the predetermined period , the power device is based on the input signal including the voltage drop signal. And a power oscillation control means for outputting a control signal for stabilizing the power oscillation of the power oscillation suppression device. The voltage drop signal is a signal that decreases immediately after the accident is removed,
The power oscillation control means stabilizes the power oscillation of the power device based on a signal representing an output state of the power device other than the voltage decrease signal when the value of the voltage decrease signal is negative during the predetermined period. The power fluctuation suppressing device according to claim 1, wherein a control signal to be converted is output. A power factor angle change speed output circuit that inputs the power factor angle calculated by the power factor angle calculation means and outputs a power factor angle change speed that is a change speed of the input power factor angle;
The said accident determination means determines that the said system accident has occurred when the power factor angle change speed output from the power factor angle change speed output circuit exceeds a predetermined value. The power oscillation suppression device described. The power device is a generator,
The power fluctuation control device according to claim 1, wherein the input signal includes at least an active power, a rotation speed, a reactive power, a change speed of the active power, and a change speed of the terminal voltage of the generator. The power device is a generator,
The power fluctuation control device according to claim 1, wherein the input signal includes at least an active power and a rotation speed of the generator. An electric power fluctuation suppressing method for suppressing electric power fluctuation generated in an electric power system,
Calculating a power factor angle from active power and reactive power of a power device connected to the power system;
Determining that a system fault has occurred in the power system when the calculated rate of change of the power factor angle exceeds a predetermined value; and
When it is determined that the system fault has occurred , a voltage lowering signal that is a signal having a value less than 0 among the input signals indicating the output state of the electric power device is output from the input signal for a predetermined period after the accident occurs. A first control signal adjustment procedure for outputting as a control signal for stabilizing power fluctuation of the power device based on the removed signal ;
And a step of outputting a control signal for stabilizing power oscillation of the power device based on the input signal including the voltage drop signal after the predetermined period has elapsed. An electric power fluctuation suppressing program for suppressing electric power fluctuation generated in an electric power system,
A power factor angle calculation procedure for calculating a power factor angle from active power and reactive power of a power device connected to the power system;
An accident determination procedure for determining that a system fault has occurred in the power system when the rate of change of the power factor angle calculated by the power factor angle calculation procedure exceeds a predetermined value;
When it is determined by the accident determination procedure that the system fault has occurred , a voltage drop signal that is a signal having a value less than 0 among the input signals indicating the output state of the power device for a predetermined period after the occurrence of the accident A first control signal adjustment procedure for outputting as a control signal for stabilizing power fluctuation of the power device based on a signal obtained by removing the input signal from the input signal ;
A second control signal adjustment procedure for outputting a control signal for stabilizing power fluctuation of the power device based on the input signal including the voltage reduction signal after the predetermined period has elapsed, Electric power fluctuation suppression program.

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