JP3084343B2 - Grid stabilization control method - Google Patents

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 controlling an abnormal frequency that occurs when an interconnection of an electric power system is separated or a generator is dropped to an appropriate frequency. It is.

[0002]

2. Description of the Related Art FIG. 8 is a block diagram showing a frequency control apparatus to which a conventional system stabilization control method is applied.
Reference numerals 1 to 4 are buses of the power system, 5 is a transmission line (interconnection line) interconnecting the main system and the bus 1, 6 to 8 are transmission lines interconnecting each bus 1 to 4, and 9 is a bus 1 , 10 is a load connected to the bus 3, 11 is a generator connected to the bus 3, 12 is a generator connected to the bus 4, and 13 to 16 are circuit breakers.

Further, reference numeral 17 denotes a current transformer for detecting a current I flowing through the transmission line 5, 18 denotes a transformer for detecting a voltage V applied to the transmission line 5, and 19 denotes a transmission line based on the current I and the voltage V. 5 is a measuring terminal that measures the tidal current value P flowing through 5 and also measures the frequency f of the system, 20 is a central power supply command center that collects the system capacity W (load amount) of the generators 11 and 12, 21
Calculates a required control amount based on the tidal current value P, the frequency f, and the system capacity W, and outputs a trip signal based on the control amount.
When the trip signals are output from the circuit breakers 13 to
16 is a control terminal for tripping.

Next, the operation will be described. First, the measuring terminal 19 measures the power flow value P flowing through the transmission line 5 based on the current I detected by the current transformer 17 and the voltage V detected by the transformer 18, and also measures the frequency f of the system. I do. Thus, the central processing unit 21 takes in the power flow value P and the frequency f measured by the measuring terminal 19, and also takes in the system capacity W collected by the central power supply command center 20, and sets the frequency of the power system to an appropriate value. Is calculated as shown below.

[0005] _{Q L = (P-K L} · Δf · W) / (1-K L · Δf) ··· (1) Q P = P-K H · Δf · W ··· (2) However, K _L is the system constant factor during system constant K _H is the generator shut off during load rejection, the formula (1), while showing a control amount Q _L in the case of controlling the frequency by disconnecting the load from the system, wherein (2) shows a control quantity Q _P in the case of controlling the frequency by disconnecting the generator from the system.

Namely, the central processing unit 21, when the frequency of the system drops abnormally, it is necessary to increase the frequency to obtain the control amount Q _L by calculating the equation (1), the controlled variable in order to cut off only the load corresponding to Q _L, to select a load commensurate with the load from the load of the power system. For example, when selecting the load 9 and the load 10, if appropriate to the load amount corresponding to the control amount Q _L, the load 9 and the load 10 is selected, and outputs a trip signal to the control terminal 22.
Then, the control terminals 22 and 23 trip the circuit breakers 13 and 14, disconnect the load 9 and the load 10 from the system, and control the frequency of the system to an appropriate value.

On the other hand, when the frequency of the system rises abnormally, the central processing unit 21 calculates the control amount Q _P by calculating equation (2) because it is necessary to decrease the frequency. in order to cut off only the power generation amount corresponding to the Q _P, selects a generator commensurate with the amount of power generation by the generator of the power system.
For example, when the generator 11 is selected, if the amount of power generation corresponds to the control amount Q _P , the generator 11 is selected and a trip signal is output to the control terminal 24. Then, the control terminal 24 trips the circuit breaker 15, disconnects the generator 11 from the system, and controls the frequency of the system to an appropriate value.

[0008]

Since the conventional system stabilization control method is configured as described above, the frequency of the system is controlled by disconnecting the load or the generator from the system. Since it is not considered at all whether or not the plant characteristics of each generator transition to an unstable state, simply disconnecting a generator or the like having a power generation amount corresponding to the control amount from the system will make the system unstable In some cases, there were problems.

The present invention has been made to solve the above problems, and the state of the power system changes every moment.
To maintain stable conditions of all generators
While controlling the frequency abnormality to the appropriate frequency,
It is an object of the present invention to obtain a system stabilization control method capable of efficiently selecting various system control patterns .

[0010]

According to a first aspect of the present invention, there is provided a system stabilization control method which performs prediction of a predicted frequency with respect to an assumed accident.
From the predicted frequency to make the plant state unstable.
If it is determined that there is a generator that
Any of the multiple system control patterns
Predicted cycle calculated again assuming that the pattern was executed
Based on the wave number, all generators leading to instability are safe.
When selecting a system control pattern that can transition to a constant state,
Priority among multiple system control patterns
System control patterns in order of increasing
System control pattern selection to be updated at predetermined intervals
It is something to do.

[0011]

According to a first aspect of the present invention, there is provided a system stabilization control method which calculates a predicted frequency for an assumed accident and calculates the predicted frequency.
It is determined that there is a generator that is unstable from the wave number.
In this case, a plurality of preset system control patterns
It is assumed that an arbitrary system control pattern has been implemented.
To the unstable state based on the predicted frequency calculated again.
System control pattern that can transition all generators to a stable state
When selecting a pattern, a plurality of system control patterns
Of the system control patterns with the highest priority
And select the system control pattern for the assumed accident,
By updating it every predetermined cycle,
Even if the state of the system changes every moment,
While maintaining the state of the electric machine stably,
Can be controlled to the wave number, and the optimal system control pattern
Be able to select efficiently.

[0012]

[Embodiment 1] An embodiment of the present invention will be described below with reference to the drawings. FIG.
FIG. 2 is a flowchart showing a system stabilization control method according to Embodiment 1 of the present invention. FIG. 2 is a configuration diagram showing a frequency control device to which the system stabilization control method of FIG. 1 is applied. The same reference numerals denote the same or corresponding parts, and a description thereof will not be repeated. Reference numeral 31 denotes operation information of the generators 11 and 12 connected to the power system (whether or not to generate power, amount of power generation, and the like).
Central Power Supply Command Office 32 for collecting information
Based on the operation information of the generators 11 and 12 and the power flow value P of the transmission line 5 (interconnection line), the power system stability is calculated in consideration of the power plant characteristics with respect to the assumed accident, and the stability calculation is performed. It is determined whether or not the generator reaching the unstable state exists in the power system from the result of the above, and if the generator reaching the unstable state exists, any of a plurality of preset system control patterns is determined. Is a central processing unit that selects a system control pattern capable of shifting all generators that reach an unstable state to a stable state based on the result of the stability calculation performed again assuming that the system control pattern has been implemented. .

[0013] Next, the operation will be described. First, the measuring terminal 19 detects the current I detected by the current transformer 17 and the voltage V detected by the transformer 18 in the same manner as the conventional one.
, The tide value P flowing through the transmission line 5 is measured, and the frequency f of the system is measured. Thereby, the central processing unit 32 calculates the frequency f measured by the measuring terminal 19.
Is calculated, and the amount of change of the frequency f with respect to the reference frequency is calculated, and based on the amount of change, it is determined whether or not an accident to be controlled in the power system has occurred (step ST1).

[0014] When it is determined that the accident power system has not occurred, the power flow value P measured by the measuring terminal 19, the operation of the generator 11, 12 that are collected by the central feed command part 31 Import information (step ST
2) The power system stability is calculated in consideration of the power plant characteristics with respect to the assumed accident (step ST3). Here, the power system stability calculation itself is a well-known calculation method and will not be described in detail. However, since the phase angle and frequency of each generator are calculated by the stability calculation, if the stability calculation is performed, For each generator, it can be determined whether the state including the stability of the plant is in a stable state or an unstable state.

[0015] Then, if the result in unstable state from the results of stability calculations generator determines whether present in the power system (step ST4), the generator leading to unstable condition exists on the power system Among a plurality of system control patterns set in advance (in the system control pattern, a combination of a load to be interrupted and a generator and an output amount of the generator to be controlled are registered), Is performed, and the power system stability calculation is repeatedly performed until a system control pattern that can transition all the generators to the stable state is found (steps ST5 and ST6). More specifically, priorities are set for each of the plurality of system control patterns. When a system control pattern that allows the machine to transition to the stable state is found, the stability calculation ends.

When the central processing unit 32 finds a system control pattern capable of shifting all the generators to a stable state, the stabilization control table stores the system control pattern as an accident processing pattern when the assumed accident actually occurs. The control pattern is registered (step ST7). However, if it is determined in step ST4 that the generator that has reached the unstable state does not exist in the power system, it is registered in the stabilization control table that control is not necessary even if the assumed accident actually occurs. .

Meanwhile, the central processing unit 32, step ST
In 1, when it is determined that an accident has occurred in the power system, the accident point and the accident type of the accident are specified based on the power flow value P, active power, voltage V, frequency f, and the like (step ST8). . When the accident point and the accident type of the accident are specified, it is determined whether or not there is an assumed accident that coincides with the accident among the assumed accidents whose stability was calculated in step ST3 (step ST9). ),
If there is an assumed accident that matches the accident, the system control pattern of the coincident assumed accident is read with reference to the stabilization control table (step ST10).

[0018] Then, finally, the central processing unit 32, the read line control pattern matching postulated accident, and outputs a trip signal or the generator control signal to the control terminal 22 to 25 based on the system control patterns. Thereby, the control terminals 22 to 25 shut off the load or the generator,
Alternatively, the output amount of the generator is controlled (step ST1).
1).

As described above, according to the first embodiment, when it is determined from the result of the power system stability calculation with respect to the assumed accident that there is a generator reaching an unstable state, a plurality of predetermined system Of the control patterns, based on the power system stability calculation performed again assuming that an arbitrary system control pattern was implemented, a system control pattern that can transition all generators that reach an unstable state to a stable state Since it is selected, it is possible to control the frequency abnormality to an appropriate frequency while shifting the generator that is in an unstable state due to the frequency abnormality to the stable state, and as a result, keep the power system stable The effect that can be achieved.

[0020] Note that a registration system control table performed in Step ST1~ step ST7, the state of the power system changes with time, if the state of the power system changes, the system control table previously enrolled supposed In order to be able to always select an appropriate system control table, registration of a system control pattern for an assumed accident is performed at a predetermined period (several seconds to several minutes) so that an appropriate system control table can be selected. It is updated every time.
Thereby, even when the state of the power system changes moment by moment, there is an effect that the frequency abnormality can be controlled to an appropriate frequency while maintaining the states of all the generators stably.

Embodiment 2 FIG . In the first embodiment, the stability of the power system with respect to the assumed accident is calculated, and it is determined from the result of the stability calculation whether or not the generator reaching the unstable state exists in the power system. A predicted frequency for an accident may be calculated, and it may be determined from the predicted frequency whether a generator whose plant state is in an unstable state exists in the power system. Play. By the way,
FIG. 3 is a flowchart showing a system stabilization control method according to Embodiment 2 of the present invention.

[0022] Next, the operation will be described. In FIG. 3, since steps other than steps ST21 to ST24 are the same as those in the first embodiment, only steps ST21 to ST24 will be described. That is, when the central processing unit 32 captures the tidal current value P measured by the measuring terminal 19 and the operation information of the generators 11 and 12 collected by the central power supply command station 31 (step ST2), the prediction for the assumed accident is performed. Frequency ΔF
Is calculated as shown below (step ST21). ΔF = P / {K _HG · P _OG + K _HL (P _OG −P)} (3) where P _OG is the total power generation of the generator in the own system K _HG is the power generation in the own system K _HL is the system constant of the load in the own system.

[0023] Then, the central processing unit 32 determines whether the generator leading to an unstable state from the predicted frequency ΔF which is the operation exists in the power system (step ST22).
The, during the operation of the accident before the generator output P _G and predicted frequency [Delta] F (finish frequency after the accident occurred) Specifically,
Since there is the relationship shown in FIG. 4, the area boundary line (dotted line in FIG. 4)
If the value of the predicted frequency ΔF exceeds
It is expected that the plant state of the generator (hereinafter, the stability of the generator indicates the plant state) will reach an unstable state.

From the calculation result of the predicted frequency ΔF,
If it is determined that the generator reaching the unstable state is present in the power system, it is assumed that the system control pattern having a higher priority is sequentially executed from among a plurality of preset system control patterns, and all the The calculation of the predicted frequency ΔF is repeatedly performed until a system control pattern that can transition the machine to the stable state is found (steps ST23 and ST24). That is,
The control amount when the system control pattern is executed is Q, and the predicted frequency ΔF after control is calculated as shown below. ΔF = (P−Q) / {K _HG (P _OG −Q) + K _HL (P _OG −P)} (4)

[0025] Then, the central processing unit 32 determines whether all of the generators leading to an unstable state from the predicted frequency ΔF which is the operation can transition to the stable state from the relationship of FIG. 4, all the generators When a system control pattern that can transition to the stable state is found, the system control pattern is registered in the stabilization control table as an accident processing pattern when the assumed accident actually occurs (step ST7). Hereinafter, since it is the same as the first embodiment, the description is omitted.

As described above, according to the second embodiment, the predicted frequency ΔF for the assumed accident is calculated, and the predicted frequency ΔF is calculated.
If it is determined that there is a generator from F to an unstable state, the predicted frequency ΔF is calculated again on the assumption that an arbitrary system control pattern has been executed among a plurality of system control patterns set in advance. The system control pattern that allows all the generators that reach the unstable state to transition to the stable state is selected based on the above, so that the generator that enters the unstable state due to the frequency abnormality is shifted to the stable state. , Frequency abnormalities can be controlled to the appropriate frequency,
As a result, there is an effect that the power system can be kept stable.

Embodiment 3 FIG . In the second embodiment, the operation output P _G of the generator before the accident occurs
The predicted frequency ΔF has been described as to determine the state of the generator from the relationship between the (finished frequency after the accident occurred), the operation of the accident before the generator output P _G and predicted frequency Δ
The state of the generator may be determined from the relationship between F (peak frequency after the occurrence of the accident), and the same effect as in the second embodiment can be obtained. The state of the generator may be determined from the relationship between the two.)

[0028] In other words, the operation of the accident before the occurrence of the generator output P _G
And the predicted frequency ΔF (peak frequency after the occurrence of the accident), there is a relationship shown in FIG.
If it corresponds to the area (see FIG. 5) surrounded by _MIN and the area boundary line S (P _G ), the generator is expected to reach an unstable state. Incidentally, the area boundary line S (P _G ) is specified by the following equation, and the generator stability determination value P _MIN is specified by performing a simulation before the accident. S (P _G ) = a × P _G + b (5) where a and b are constants specific to the generator.

Embodiment 4 FIG . In Embodiment 2, treats system constants K _HG generators in the own system as a fixed value, but not mentioned method for obtaining strains constant K _HG, system constants K _HG of the generator, its own system It is specified by the total power generation amount P _OG of the generators in the inside, the total value M of the inertia constants of the combined generators, and the power flow value P of the transmission line 5 (interconnection line). Constant K
_{If the HG} is obtained, the stability of the generator can be determined with higher accuracy than in the second embodiment. The system constant K _HG of the generator
Is determined by the following equation, and between the system constant K _HG of the generator and the total power generation P _OG of the generator in the own system divided by the total value M of the inertia constants of the combined generator is shown in FIG. There is a relationship shown in

[0030] _{K HG = c · P OG /} M + d · P ··· (6) However, c, d are predetermined coefficients, is identified from the results of the simulation.

Embodiment 5 FIG . In the fourth embodiment, the total power generation amount P _OG ,
Using the total value M or the like of the inertia constants of the incorporation generator, has been described which specifies a system constant K _HG of the generator, the central dispatching center 31, the power generation information of the other facilities in the own line exactly since it is difficult to grasp the may be replaced by the total value M ₁ of the total power generation P _OG1 and the incorporation representative generator inertia constants representative generator group in its own system, the embodiments The same effect as that of No. 4 is obtained. As a result, the system constant KHG of the generator can be easily specified, which has an effect of being extremely practical.

[0032] In this connection, the system constant K _HG of the generator is identified by the following equation, and the system constants K _HG of the generator, the total power generation P _OG1 representative generator group in the self system of the incorporation representative generator between those divided by the total value M ₁ of the inertia constant, relationship shown in FIG. K _HG = e · P _OG1 / M ₁ + h · P (7) where e and h are predetermined coefficients and are specified from the result of the simulation.

[0033]

As described above, according to the first aspect of the present invention, a predicted frequency for an assumed accident is calculated, and the predicted frequency is calculated.
It is determined that there is a generator that is unstable from the wave number.
In this case, a plurality of preset system control patterns
It is assumed that an arbitrary system control pattern has been implemented.
To the unstable state based on the predicted frequency calculated again.
System control pattern that can transition all generators to a stable state
When selecting a pattern, a plurality of system control patterns
Of the system control patterns with the highest priority
And select the system control pattern for the assumed accident,
Since it is configured to update every predetermined period, the frequency
The generator, which has reached an unstable state due to an abnormality, transitions to a stable state
Frequency abnormalities to the appropriate frequency.
As a result, there is an effect that the power system can be maintained stably.
You. In addition, the optimal system control pattern can be efficiently selected.
Even if the state of the power system changes every moment,
While maintaining the state of all generators stably,
There is an effect that the frequency can be controlled to be appropriate.

[Brief description of the drawings]

FIG. 1 is a flowchart illustrating a system stabilization control method according to a first embodiment of the present invention.

FIG. 2 is a configuration diagram showing a frequency control device to which the system stabilization control method of FIG. 1 is applied.

FIG. 3 is a flowchart illustrating a system stabilization control method according to a second embodiment of the present invention.

FIG. 4 is a graph illustrating a state of a generator.

FIG. 5 is a graph illustrating a state of a generator.

FIG. 6 is a graph illustrating a system constant of a generator.

FIG. 7 is a graph illustrating a system constant of a generator.

FIG. 8 is a configuration diagram showing a frequency control device to which a conventional system stabilization control method is applied.

[Explanation of symbols]

 5 Transmission line (interconnection line), 11, 12 generator.

────────────────────────────────────────────────── ─── Continuing from the front page (72) Kazuo Shiraishi 2-5 Marunouchi, Takamatsu City, Kagawa Prefecture Inside Shikoku Electric Power Co., Ltd. (72) Yoshihiro Miyamoto 2-5 Marunouchi Takamatsu City, Kagawa Prefecture Shikoku Electric Power Company ( 72) Inventor Kazuhito Kibi 6-1-1-1 Hamayama-dori, Hyogo-ku, Kobe-shi Inside the Kobe Office of Mitsubishi Electric Engineering Co., Ltd. (56) References JP-A-63-181618 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H02J 3/00 H02J 3/04

Claims (1)

(57) [Claims] 1. A power flow value of a link line and a frequency of a system are measured, and it is determined whether or not an accident has occurred in the power system based on a fluctuation amount of the frequency with respect to a preset reference frequency. If it is determined that no accident has occurred, the predicted frequency for the assumed accident is calculated based on the operation information of the generator connected to the power system and the tidal current value of the interconnection line.
Then, based on the predicted frequency, it is determined whether or not a generator whose plant state is in an unstable state is present in the power system. Of the control patterns, assuming that an arbitrary system control pattern has been implemented, the predicted frequency is calculated again,
Based on the predicted frequency, select a system control pattern that allows all generators that reach an unstable state to transition to a stable state .
When a plurality of system control patterns are set in advance,
Conducted sequentially from the higher priority system control pattern and assumed
The selection of the system control pattern for an accident is performed at predetermined intervals.
And the system stabilization control method to be updated .