JPH1028326A - Method for controlling system stabilization - Google Patents

Abstract

PROBLEM TO BE SOLVED: To perform stabilization control, even when a wide-extent failure occurs due to the failure of a trunk transmission system by deciding the optimum stabilization controlling quantity by detecting the location of the failure and the failure of the trunk transmission system by comparing the value of kinetic energy at a fixed period of time, after the occurrence of the failure with a preset threshold. SOLUTION: A terminal device 1A computes the electric output of equivalent power generator (a single equivalent power generator for the operators being operated in a power plant 3A) at every hour, based on the voltage data and current data measured by means of a sensor 51A. Then the device 1A predicts the hourly changing locus of the kinetic energy and discriminates whether a failure occurs in a trunk transmission system or power system, by comparing the predicted kinetic energy value at a certain point of time after the occurrence of the failure with a preestablished criterion level. Therefore, whether a failure is a trunk transmission system failure or power system failure can be discriminated on-line, merely from the local backup information of the power plant, and stabilization control can be performed optimumly in accordance with the location of the failure.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a system stabilization control method for preventing the effects of an accident occurring in a power system from spreading and spreading, and preventing a generator connected to the power system from stepping out. It is about.

[0002]

2. Description of the Related Art FIG. 7 is a system configuration diagram of a system stabilizing relay device which realizes a conventional transient stability control method disclosed in, for example, a paper 1343 of the National Convention of the Institute of Electrical Engineers of Japan in 1990. In FIG. A terminal device installed at a power station, 1N is a central processing unit, 1B is a terminal device installed at a substation, 21N is an information transmission line connecting the terminal device 1B and the central processing unit 1N, and 3A is a controlled object (power supply restriction). Power plant, 3B
Is a substation, 4A is a power system, and 51A is a sensor that measures voltage data and current data between the power plant 3A and the substation 3B.

Next, the operation will be described. The terminal device 1B installed in the substation measures the bus voltage data, the current data, and the circuit breaker signal of the substation 3B, and detects an accident in the system. In power plants installed terminal apparatus 1A, performs voltage data of the generator measured by the sensor 51A, the operation of the generator electrical output P _E type the current data, the central processing unit 1N
And receives a shut-off command from the central processing unit 1N, and outputs it to the circuit breaker.

In the central processing unit 1N, as shown in FIG. 7, a power supply system to be controlled is modeled as one infinite bus system, and an equivalent generator (target generator is used) at an assumed control completion time. From the power phase difference angle curve estimated based on the kinetic energy Vk accumulated in the parallel impedance method and the online data, FIG.
Calculate the critical energy Vc of the system as shown in
The transient stability of the system is determined from the magnitude of the critical energy Vc. That is, if Vk ≧ Vc, it is unstable. If Vk <Vc, it is stable. If it is determined that it is unstable, the kinetic energy Vk and critical energy Vc when the generator is cut off are calculated, and the optimal power generation for stabilization is calculated. The combination of the generators is selected, and a generator shutoff command is transmitted to the terminal device 1A installed at the power plant.

[0005] Fig. 8 is a diagram in which the target power supply system is reduced to one equivalent generator system by the parallel impedance method. Therefore, the mechanical input Pm, the electrical output Pe, and the inertia constant M are the target. This is the total value of all generators operating in the power system. Further, reactances jXd 'and jXt are parallel combined values of all generators in operation, jX1 is a parallel combined value of power supply lines, and jXs is a value estimated from data measured at a generator end after a failure has occurred. The infinite bus is a temporary bus representing a very large power system.

The electric output Pe in FIG. 8 is given by the following equation. Pe = P ^* sin δ (1) FIG. 9 shows a power phase angle curve (Pe−δ curve) based on this equation. Note that P ^* is proportional to 1 / X (in FIG. 8, X = jXd '+ jXt + jX1 + j
Xs). Further, since X takes a very large value during an accident (during a failure), the Pe-δ curve during the accident becomes smaller than after the accident is cleared. Accordingly, the relationship as shown in FIG. 9 is obtained, and the kinetic energy -Vk and the critical energy Vc are given as shown in FIG.

In FIG. 9, Pe ^* (tsh) is an output at a control completion assumed time tsh, P ^* is a peak value of a power phase angle curve, Δω is a correction coefficient, and kinetic energy V
k (tsh) and critical energy Vc are obtained by the equations (2) and (3). Vk = M {Δω (tsh) } / 2 ··· (2) Vc = P * (cosδ sh -cosδ u) + Pm (δ sh -δ u) ··· (3)

[0008] The following describes calculation of the generator electrical output P _E. P _E (t) = {v (t) · i (t) + v (t−90) · i (t−90)} / 2 (4) v (t) · i (t): current Sampling voltage and current (difference filter) v (t-90) .i (t-90): sampling voltage and current (electrical difference filter) 90 ° before electrical angle

[0009] At the above equation, as shown in FIG. 10, 4.167Ms electrical output P _E of the generator for each phase (electrical angle of 90
゜), and the moving average is calculated by the following formula at a period of 12.5 ms (electrical angle: 270 °). P _Ea1 (t) = {P _Ea10 (t) + P _Ea10 (t−Tc) + P _Ea10 (t−2Tc) + P _Ea10 (t−3Tc)} / 4 (5) take. P _E1 (t) = P _Ea1 (t) + P _Eb1 (t) + P _Ec1 (t) (6) Further, the total of the power plants is _calculated by the following equation. P _E (t) = P _E1 (t) + P _E2 (t) + P _E3 (t) + P _E4 (t) (7)

[0010]

The conventional system stabilization control method is configured as described above. 1) The target phenomenon is limited to a local phenomenon caused by a power line failure, and a main system failure occurs. It cannot respond to a wide range of phenomena caused by such factors. 2) In principle, it is not possible to determine the stability of the main system failure and determine the stabilization control amount. 3) Even in the case of a power supply system failure, the influence of a change in the generator internal voltage due to the excitation system control is merely considered with a simple correction coefficient K, so that if the change is large, it becomes an error factor.
There were issues such as.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems, and can perform stabilization control not only for local phenomena but also for a wide range of phenomena caused by backbone failures. It is an object of the present invention to provide a system stabilization control method capable of performing high-accuracy stabilization control in consideration of the influence of a generator internal voltage change due to an excitation system control even when a power supply system fails.

[0012]

According to a first aspect of the present invention, there is provided a system stabilization control method, wherein kinetic energy calculated from current data and voltage data measured for each power plant in an electric power system and kinetic energy generated from a failure occurrence. Using the trajectory of the kinetic energy in which the elapsed time is plotted in orthogonal plane coordinates, the kinetic energy value is generated in the power system by comparing the kinetic energy value after a certain time from the occurrence of the failure with the threshold value set in advance by simulation. A failure location, a core failure of the stabilization control and a dead zone are detected, and an optimum stabilization control amount is determined according to the detection result.

According to a second aspect of the present invention, in the system stabilization control method, when it is determined that a main system failure has occurred, a prediction is made a predetermined time ahead based on a trajectory of a kinetic energy transition, and the predicted value is compared with a settling value. By doing so, the stabilization control amount of the backbone failure is determined.

According to a third aspect of the present invention, in the system stabilization control method, when it is determined that a power supply system has failed, an electrical output and an equivalent generator calculated from current data and voltage data measured for each power plant. The transition trajectory of the power phase angle curve in which the phase angle of the power phase angle curve is orthogonal to the plane coordinates is estimated by applying a fixed arithmetic expression, and the sum of the estimated peak value of the power phase angle curve and the stability margin previously settled is calculated. By comparing the value with the mechanical input of the equivalent generator, the severity of the transient stability is determined, and an appropriate stabilization control amount is determined according to the severity.

According to a fourth aspect of the present invention, in the system stabilization control method, when it is determined that the transient stability has a relatively large margin, a band region having a constant width is provided around the estimated power phase angle curve as an axis. The optimum stabilization control amount is determined in accordance with the fact that the measured data is at the upper limit, the lower limit of the band area, or within the band area.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below. Embodiment 1 FIG. FIG. 1 is a configuration diagram of a system stabilization system based on a system stabilization control method according to a first embodiment, where 1N is a central processing unit of the system stabilization system;
1A is a terminal device of the system stabilization system, 3A is a power plant to be controlled (power supply restriction), 4A is a power system, 51A
Is a sensor that measures voltage data and current data of the power system 4A.

Next, the operation will be described. Terminal device 1A
Then, based on the voltage data and the current data measured by the sensor 51A, the electrical output Pe at each time of the equivalent generator (the generator operating at the power plant 3A is consolidated into one equivalent by the parallel impedance method) (T1) is calculated. The kinetic energy Vk (t) is calculated from the following equations (8) and (9) using the time series data of the electrical output measured online.

(Equation 1)

(Equation 2) Here, ωo: reference angular frequency of the driving generator, △ ω (t):
Average angular frequency deviation of the operating generator, Pm: total mechanical input of the operating generator, Pe: electrical output, weighted by the inertia constant of the operating generator, M: total inertia of the operating generator Is a constant.

Using this kinetic energy Vk (t),
As shown in FIG. 2, the fault location and the dead zone of the stabilization control are determined. That is, appropriate times t1 and t2 after the failure is eliminated are determined, and during that time, Vk is set in an area defined by appropriate kinetic energies Vk0 and Vk1 by the above equations (8) and (9) based on digital simulation. (T) exists for a certain period of time or more, transiently stable {Vk (t) <Vk0; dead zone},
Backbone failure {(t) <Vk1}, power supply failure {Vk
(T) ≧ Vk1} is determined. Here, t1, t2, V
k0 and Vk1 are pre-set values for each power plant. In addition,
If it is determined that a main system failure has occurred, the stabilization control amount is determined based on the kinetic energy prediction value.If it is determined that the power supply system failure has occurred, the stabilization control amount is determined according to the band method algorithm. Determines the stabilization control amount to be zero.

When a distributed system configuration using only self-terminal information (a system configuration in which a central processing unit such as a power plant is arranged and there is no exchange between the devices) is assumed, a failure in a main system and a failure in a power supply system are considered. Therefore, it is difficult to apply the same control logic. The reason for this is that a trunk system failure is a phenomenon in a multi-machine system mode, whereas a power supply system failure is often an infinite bus system phenomenon in one machine. However, according to the above-described first embodiment, it is possible to determine the main system failure and the power supply system failure off-line only using the self-end information of the power plant, so that it is possible to perform optimal stabilization control according to each failure location. Become.

Embodiment 2 If it is determined in the first embodiment that the main system failure has occurred, the kinetic energy Vk (t)
Is used to determine the required stabilization control amount (electric control amount). It should be noted that the required amount of control cannot be accurately determined unless the kinetic energy Vk (t) at a point in time after the occurrence of the system failure is used, but the required amount of control increases as the time delays. Would.

Therefore, in the second embodiment, the required amount of electricity control for the backbone failure is determined by using the temporally predicted value of the kinetic energy Vk (t). Therefore, for example, the motion of the kinetic energy Vk (t) is secondarily approximated as in the following equation. Vk (t) = V2t ² + V1t + V0 (10) The least squares method is applied to the equation (10) from the sampling data at t1 to t2 shown in FIG.
Determine V2. As a result, Vk (t3) at the power limit time t3 can be predicted.

Compared with this Vk (t3) and a fixed threshold value set in advance by digital simulation using a model simulating the target system in detail, there is no power control.
(T3) <Vd1}, one electric control {Vd1 ≦ VK (t3)
<Vd2}, two electronic controls {Vd2 ≦ Vx (t3) <Vd
3}, three electronic control units {Vx (t3) ≧ Vd3} are determined. Also, the level determination thresholds Vd1 and Vd2 of the electric control amount
And Vd3 are set values obtained by a preliminary offline simulation.

In a distributed system configuration, it is very difficult to determine an optimal stabilization control amount for a multi-machine mode phenomenon caused by a main system failure. However, according to the above-described second embodiment, the optimal stabilization control amount can be obtained in an autonomous and decentralized manner using only the own end information of the power plant.

Hereinafter, a method of obtaining the coefficients V0, V1, and V2 will be described. The coefficients V0, V1, and V2 are obtained as follows by applying the least squares method. t1
When sampling data of t2 (s) is obtained from (s), the following determinant can be derived. b = A · X (11) Here, each vector and matrix are as shown in Expression (12).

(Equation 3) From the above equation (12), the coefficients V1, V2, and V3 are given by the following (1)
3) It is obtained as shown in the equation.

(Equation 4)

Embodiment 3 In the first and second embodiments, the system stabilization method is described in which it is determined whether a main system failure or a power supply system failure occurs using the kinetic energy Vk (t), and the system stabilization method is performed when the main system failure is determined. If it is determined that the power supply system has failed, the processing is performed using a power phase angle curve (hereinafter, referred to as a Pe-δ curve) as shown in FIG. The configuration of the stabilization device based on the system stabilization method of the third embodiment is the same as the configuration example of the first embodiment shown in FIG. The power system can be modeled as a virtual equivalent one-machine infinite bus system as shown in FIG. 5, and the electric output Pe of the generator G in FIG.
It can be expressed like an expression. Pe = P0 + P1sinΔδ + P2cosΔδ (14) Δδ: generator phase angle deviation P0, P1, P2: constant coefficient

Next, the operation will be described. The electric output Pe of the power plant 3A is constantly calculated by sending the voltage and current data measured by the sensor 51A from the terminal device 1A to the central processing unit 1N, and is calculated based on the kinetic energy Vk (t) shown in the first embodiment. On condition that the value has reached a certain set value (kick), the central processing unit 1N shifts from the continuous mode to the monitoring mode, and performs stabilization control according to the flowchart shown in FIG.

That is, in FIG. 6, step ST6-
1 is a processing step of shifting to the monitoring mode when it is determined that the power supply system has failed by the method described in the first embodiment. In step ST6-2, the generator output P for a certain period after the failure is eliminated
e is sampled in time series, and using this sampled data, the constants P0, P1, and P2 are identified by the Pe-δ curve estimation formula (15), and the Pe-δ curve is estimated. .

(Equation 5) In step ST6-3, the peak value P of the Pe-δ curve is determined.
Peak is obtained, and a comparison operation of Expression (16) is performed. Ppeak ≦ Pm + α (16) α: Margin (dead zone: Pre-set value) Pm: Generator mechanical input If Expression (16) holds It is determined that the power supply system to be stabilized is out of synchronization in the first wave, and the process proceeds to step ST6-8.
Otherwise, the process proceeds to step ST6-4.

Step ST6-4 is a process of performing stability discrimination by using a band region (hatched portion) set in advance by digital simulation using a model simulating the target system in detail and shown in FIG. 4 and actual measurement data. Process. That is, if the measured phase angle data decreases to “(dΔδ / dt) <0” or the measured electrical output exceeds the upper limit of the band, it is determined to be stable, and the process proceeds to step ST6-9. Otherwise, step S
This is a processing step that proceeds to T6-5.

Step ST6-5 includes step ST6-
A processing step in which the stability is determined in the same manner as in step 4, and if the measured electrical output data exceeds the lower limit of the band area, it is determined to be unstable, and the process proceeds to step ST6-7, otherwise proceeds to step ST6-6. In step ST6-6, if the time t from when the actually measured data enters the band area is longer than the preset time t3, it is determined to be unstable, and the process proceeds to step ST6-7. This is a processing step returning to -4.

In step ST6-7, Pe- is determined again based on the sampling data up to the time when it is determined to be unstable.
Processing step for estimating a δ curve. Step ST6-8 is a processing step of determining the electric control amount according to the equal area method based on the Pe-δ curve estimated in step ST6-7. Step ST
6-9 is a processing step of determining that the target system is stable and determining that there is no electric power control.

The electric output (power) of the Pe-δ curve
Pe can be calculated from voltage and current sampling data. The phase angle δ can be calculated by integrating the equation (9) again. An appropriate value is set for the sampling period indicated by the bold line based on a previous simulation. Generally 50ms to 2 after clearing the fault
Set to about 50 ms.

As described above, according to the third embodiment, a band area is provided on the Pe-δ curve, and the stability is determined using this band area. After estimating the Pe-δ curve by the bold line portion, the case where the back voltage rises by the control of the generator excitation system to be actually stable is estimated.
In the determination based on the e-δ curve, a stable determination can be accurately performed for an unstable phenomenon.

Embodiment 4 FIG. In the above-described third embodiment, the stabilization control method for the power supply system failure based on the present invention has been described. In the fourth embodiment, however, a method for determining the stability of transient stability using the Pe-δ curve shown in FIG. A specific method will be described. An equation obtained by differentiating equation (14) once with Δδ is equation (17). (DPe / dΔδ) = P1cosΔδ−P2sinΔδ = 0 (17) From the expression (17), the following expression (18) can be obtained. Δδpeak = tan ⁻¹ (P1 / P2) (18) Ppeak is calculated by equation (19) by substituting equation (18) into equation (17). Ppeak = P0 + P1sinΔδpeak + P2cosΔδ (19) Using this Ppeak, a stability determination is performed by equation (16).

As described above, according to the fourth embodiment, severe out-of-step phenomenon can be predicted at an early stage by using the peak value of the Pe-δ curve, and system out-of-step can be prevented beforehand.

[0035]

As described above, according to the first aspect of the present invention, focusing on the kinetic energy of an equivalent generator in which the target generators are integrated into one unit by the parallel impedance method, It is configured to judge whether it is a main system failure or a power supply system failure by comparing the kinetic energy predicted value at a certain point after the occurrence of the failure with the judgment level set in advance, so that only the power station own end information is used. Thus, the main system failure and the power supply system failure can be distinguished online, and there is an effect that optimal stabilization control corresponding to each failure location can be performed.

According to the second aspect of the present invention, when it is determined that a main system failure has occurred, a required stabilization control amount is determined by comparing the kinetic energy predicted value with a previously determined control amount determination level. Is determined, so that there is an effect that the optimal stabilization control amount can be obtained in an autonomous and decentralized manner using only the self-end information of the power plant.

According to the third aspect of the invention, when it is determined that the power supply system has failed, the power phase difference angle curve is estimated online, and the sum of the peak value of the estimated curve and the previously set stability margin is calculated. The value is compared with the mechanical input of the equivalent generator to determine the severity of the transient stability.If it is determined that there is no margin in stability, for example, it is shown in the prior art. The stabilization control taking into account the influence of the excitation system control can be performed by immediately determining the stability and determining the stabilization control amount by using the above-described method.

According to the fourth aspect of the invention, when it is determined that there is a margin in stability, a band region having a predetermined width set in advance is provided around the estimated Pe-δ curve as an axis. It is determined that the Pe-δ trajectory is stable when the trajectory exits from the upper side of the band area due to the control of the excitation system or the like within a certain time, or when the phase difference angle δ changes from increasing to decreasing.
When the e-δ trajectory comes out from the lower side of the band or exists in the band over a certain period of time, it is determined that there is an unstable tendency. There is an effect that strict determination of stability and determination of a stabilization control amount can be performed by using the above-described technique.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a system stabilization system based on a system stabilization control method according to a first embodiment of the present invention.

FIG. 2 is a characteristic diagram showing a method for determining a power supply system failure and a main system failure based on kinetic energy according to the present invention.

FIG. 3 is a characteristic diagram showing a method for determining a control amount for a trunk system failure based on an estimated acceleration energy value according to the second embodiment of the present invention.

FIG. 4 is a Pe-δ curve diagram showing a concept of stability determination according to a third embodiment of the present invention.

FIG. 5 is a system model diagram of an infinite bus using one virtual equivalent of a target power supply system according to Embodiment 3 of the present invention.

FIG. 6 is a flowchart illustrating a system stabilization control method according to a third embodiment of the present invention.

FIG. 7 is a configuration diagram illustrating a conventional system stabilization device.

FIG. 8 is a system model diagram of an infinite bus with one equivalent of a target power supply system in a conventional system stabilization control method.

FIG. 9 shows Pe-δ showing the concept of a conventional system stabilization method.
It is a curve figure.

FIG. 10 is an explanatory diagram of a generator output _PE calculation process.

[Explanation of symbols]

Vk kinetic energy, Pm mechanical input, G equivalent generator, Pe electrical output, δ phase angle.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Yoichi Kitamura 1 Higashi-Shinmachi, Higashi-ku, Nagoya City, Aichi Prefecture Inside (72) Inventor Makoto Yamamoto 1 Higashi-Shinmachi, Higashi-ku, Nagoya City, Aichi Prefecture Chubu Electric Power Co., Inc. Inside

Claims (4)

[Claims] A kinetic energy calculated from current data and voltage data measured for each power plant in a power system and a kinetic energy transition trajectory obtained by plotting the elapsed time from the occurrence of a failure on a plane coordinate orthogonal to the failure. By comparing the value of the kinetic energy at a certain time after the occurrence with the threshold value set in advance by simulation, the location of the fault occurring in the power system and the core fault and dead zone of the stabilization control are detected, and the detection is performed. A system stabilization control method characterized in that an optimum stabilization control amount is determined according to a result. 2. When it is determined that a main system failure has occurred, a prediction is made a predetermined time ahead based on a trajectory of a kinetic energy transition, and the predicted value is compared with a set value, thereby stabilizing the control amount of the main system failure. The system stabilization control method according to claim 1, wherein the determination is performed. 3. When it is determined that the power supply system is faulty, the electric power calculated from the current data and the voltage data measured for each power plant and the electric power phase obtained by taking the phase angle of the equivalent generator in plane coordinates orthogonal to each other. Estimate the transition trajectory of the angle curve by applying a certain arithmetic expression, and compare the estimated peak value of the power phase angle curve with the total value of the previously settled stability margin and the mechanical input of the equivalent generator. A system stability control method characterized by determining the degree of transient stability, and determining an appropriate stabilization control amount in accordance with the degree of transient stability. 4. When it is determined that the transient stability has a relatively large margin, a band region having a fixed width is provided around the estimated power phase angle curve, and the actually measured data is the upper or lower limit of the band region or the band region. 4. The system stabilization control method according to claim 3, wherein an optimal stabilization control amount is determined according to the following.