JP7128132B2 - Power system stabilization system - Google Patents

Description

An embodiment of the present invention relates to a power system stabilization system that suppresses frequency anomalies caused by system faults and maintains the frequency within a specified range.

A frequency abnormality in a power system (hereafter referred to as frequency abnormality) means that the balance between the amount of load and the amount of power generated in the power system, that is, the balance between the supply and demand of electricity (hereafter referred to as the supply-demand balance) is broken, and the frequency falls outside the specified range ( hereinafter referred to as a state that deviates from the specified range).

Frequency anomalies adversely affect the operation of power consumers and various facilities in the power system. For this reason, many electric power companies in Japan set the specified frequency range, that is, the range for frequency management, to the standard frequency (hereinafter referred to as the standard frequency) ± 0.2 Hz, and some electric power companies set the standard frequency ± 0.2 Hz. .3 Hz, and the electric power system is operated to maintain the frequency within this prescribed range.

In response to the gradual imbalance of supply and demand (state where the balance of supply and demand for electricity is lost) that occurs with fluctuations in the demand for electricity, power generation is controlled by load frequency control (LFC) and governors. It controls machine output, that is, the amount of power supplied. Therefore, since the frequency is maintained within the specified range, frequency anomalies are less likely to occur. The speed governor is a device that controls the rotation speed of the turbine of the generator.

Large-capacity generators are disconnected from the power system due to serious system accidents, such as accidents that cut off transmission line routes and accidents that span multiple bus lines, such as double-bus accidents. If the system that supplies power to the load is separated (dropped load), a sharp imbalance of supply and demand will occur. In this case, there is a possibility that the frequency will deviate from the prescribed range and lead to frequency anomaly. Therefore, a frequency relay system is installed in the electric power system to eliminate or prevent the frequency abnormality.

A frequency relay system is a system that maintains the balance between supply and demand of electric power by performing control such as load shedding and generator shutdown according to the frequency situation in the electric power system. The frequency relay system includes a distributed control type under frequency relay (UFR), an over frequency relay (OFR), and a central control type power relay. There is a grid stabilization system.

The power system stabilization system assumes in advance an accident (assumed accident) that has a high possibility of causing a frequency abnormality, and controls contents (load limit, power generation Machine break, etc.) are calculated and stored in advance. Then, in the power system stabilization system, control is immediately performed when the occurrence of the assumed accident is actually detected.

The power system stabilization system can perform control after an assumed accident occurs and before the power system becomes abnormal in frequency. For this reason, it has the advantage of being able to respond to system failures that cause sudden imbalances in supply and demand, in which stable operation of the power system cannot be maintained by control after confirming a frequency abnormality.

Frequency anomaly has two sides: a case where the frequency drops (frequency drop) and a case where the frequency rises (frequency rise) with respect to the standard frequency. The power system stabilization system cuts off the pumps and limits the load when the frequency drops, and cuts off the generator when the frequency rises. A water pump is a generator that pumps up water used for pumped-storage power generation, and is a device that consumes electric power in the same manner as a load.

Here, the configuration and operation of a conventional power system stabilization system will be described with reference to FIGS. 1 and 2. FIG.

In order to simplify the explanation, the response when the frequency drops will be explained below. As for the response at the time of frequency increase, only the object to be controlled is different, and the same idea as at the time of frequency decrease can be applied.

1 and 2 are diagrams showing the configuration of a conventional power system stabilization system. As shown in FIGS. 1 and 2, the conventional power system stabilization system comprises a central processing unit 10, an accident detection terminal device 11, and a control terminal device 12. FIG.

In FIG. 2, 1 is a generator, 2 is a load, 3 is a bus, 4 is a transmission line or transformer, 5 is a circuit breaker, 6 is a current measuring device (CT), 7 is a voltage measuring device (VT), and 8 is Communication equipment, 9 DC interconnection equipment, 10 central processing unit of conventional power system stabilization system, 11 accident detection terminal device of conventional power system stabilization system, 12 control of conventional power system stabilization system It is a terminal device.

The accident detection terminal device 11 is often installed in a power plant or the like. The control terminal device 12 is often installed at a substation or the like. The central processing unit 10 can communicate with the accident detection terminal device 11 and the control terminal device 12, and also provides system capacity, active power output of the generator (hereinafter referred to as generator output), active power consumed by the load (hereinafter referred to as It is often installed in a power supply control center or a major electrical station where system information such as load amount) can be received from the power supply information network.

As shown in FIG. 1, the accident detection terminal device 11 includes an accident detection section 11A, and detects a generator dropping accident. As shown in FIG. 2, the accident detection terminal device 11 detects the open/close state of the circuit breaker 5 provided in the transmission line 4 on the side of the generator 1 in the power system to be controlled, and the current measuring device 6 and the voltage measuring device 7. Using the generator output calculated from the obtained current and voltage, the presence or absence of the falling accident of the generator 1 is detected. The accident detection terminal device 11 transmits the detection result to the central processing unit 10 via the communication facility 8 .

The central processing unit 10, as shown in FIG. 1, includes a pre-computation unit 10A and a post-computation unit 10B. The processing of the central processing unit 10 will be described below with reference to FIG.

FIG. 3 is a diagram for explaining the processing of the conventional central processing unit 10. As shown in FIG. The pre-computation unit 10A receives system information such as the generator output of the generator 1, the load amount of the load ₂ , and the system capacity P0 from the power supply information network. The pre-computing unit 10A uses the system information, the preset power frequency characteristic K, and the target frequency deviation Δf _C to calculate, for example, the target control amount P _C is calculated by the following equation (1).

P _C = ΔP−K×Δf _C ×(P ₀ −ΔP) Equation (1) where,
P _C : Target controlled variable [MW]
ΔP : Amount of supply and demand imbalance at the time of assumed accident [MW]
K: Power frequency characteristics (system constant) [1/Hz]
Δf _C : Target frequency deviation [Hz]
P ₀ : system capacity [MW]

In equation (1), the polarity of the demand-supply imbalance amount ΔP at the occurrence of an assumed accident is set to + (plus, that is, a positive value) when the power generation amount is less than the load amount. That is, in the formula (1), when the supply-demand imbalance amount ΔP at the time of occurrence of the assumed accident is +, the load is restricted according to its magnitude.

Based on the calculated target control amount PC, the pre _- computation unit 10A selects and stores a load to be limited (hereinafter referred to as control content) from the plurality of loads 2 .

Note that the central processing unit 10 may acquire the generator output of the generator 1 measured by the accident detection terminal device 11 without going through the power supply information network, or the load 2 measured by the control terminal device 12. You may make it acquire the load amount of .

The pre-computation unit 10A selects a combination of the loads 2 to be subject to load limitation so that the amount of load when the load is limited is as close as possible to the target control amount. The pre-computation unit 10A always repeats the above processing at predetermined time intervals to update the control content.

Here, an assumed accident in a conventional power system stabilization system and details of control will be described with reference to FIGS. 4 and 5. FIG. FIG. 4 is a diagram showing a configuration example of information indicating a conventional assumed accident. FIG. 5 is a diagram showing a configuration example of information indicating the content of conventional control.

As shown in FIG. 4, the assumed accident information includes, for example, items such as assumed accident case number, monitoring point, and accident mode. The postulated accident case number indicates the number assigned to the postulated accident. A monitoring point indicates a point where a hypothetical accident is supposed to occur. The accident mode indicates the details of the assumed accident.

As shown in FIG. 5, the control content information includes items such as an assumed accident case number, supply and demand imbalance amount ΔP, and control content, for example. In addition, items such as the target control amount P _C and the controlled object are provided as control contents. The assumed accident case number is a number corresponding to the assumed accident case number in FIG. The supply and demand imbalance amount ΔP indicates the supply and demand imbalance amount when an assumed accident occurs. The controlled object indicates the load 2 to be load-limited.

In the example of FIGS. 4 and 5, when the route interruption accident of X transmission line occurs at power plant A, which is shown as the accident of assumed accident case number 1, the target control amount P _C is P _C-1 , and the control The settings are such that loads L1, L2, and L3 as the target load 2 are limited.

When the circuit breaker 5 of the X transmission line changes from the closed state to the open state, or when the power or current flowing through the X transmission line decreases below a predetermined threshold, the accident detection terminal device 11 detects the Detect the occurrence of a route interruption accident of the X transmission line. Further, the accident detection terminal device 11 may detect a route interruption accident of the X transmission line by acquiring the operation signal of the protection device of the X transmission line or the bus protection device of the A power plant. A protective device is a device that minimizes the effects of an accident and protects the power system by outputting an operation signal to cut off a circuit breaker when an accident is detected in a transmission line or busbar.

Post-calculation unit 10B receives an activation signal from accident detection terminal device 11 . The activation signal is a signal that instructs execution of the control contents in response to the detection of a system fault by the fault detection terminal device 11 . Post-computation unit 10B refers to the control details stored by pre-computation unit 10A based on the received activation signal. The post-calculation unit 10B implements the control details of the assumed accident based on the stored control details. Specifically, the post-calculation unit 10B transmits a control signal to the control terminal device 12 that controls the load 2 (L1, L2, and L3 in the example of FIG. 5) selected as the control content. The control signal is a signal instructing the control terminal device 12 to limit the load 2 to be controlled (to cut off the power supply to the load 2).

Returning to FIG. 1, the control terminal device 12 includes a control section 12A. The control terminal device 12 opens the circuit breaker 5 of the load 2 when receiving the control signal from the central processing unit 10 . Processing performed by the control terminal device 12 will be described below with reference to FIG.

FIG. 6 is a block diagram showing the configuration of a conventional control terminal device 12. As shown in FIG. The control terminal device 12 has, for example, a failsafe relay 95F. The fail-safe relay 95F is a frequency relay that prevents malfunction of erroneously cutting off power supplied to the load 2 .

The failsafe relay 95F acquires the bus voltage from the voltage measuring instrument 7 and calculates the frequency from the acquired bus voltage. The fail-safe relay 95F outputs a signal (95F operation) indicating the fact when the calculated frequency is less than a predetermined threshold (setting value _f95F ) (or equal to or less than the predetermined threshold).

The control terminal device 12 outputs a shutdown command to the circuit breaker 5 connected to the load 2 under the AND condition of the control signal and the signal indicating the frequency drop from the fail-safe relay 95F (95F operation), and the circuit breaker 5 Open the pole. The cutoff command is a signal that commands cutoff of power supplied to the load 2 . As a result, the control terminal unit 12 not only receives the control signal from the central processing unit 10, but also prevents malfunction by limiting the load when the frequency actually drops below a predetermined set value _f95F . To prevent. Here, the setting value f _95F of the failsafe relay 95F is set near the lower limit of the specified range so that it can be detected that the frequency of the failsafe relay 95F has deviated from the specified range.

Here, the relationship between the specified frequency range and the set value _f95F in the conventional power system stabilization system will be described with reference to FIG. FIG. 7 is a diagram for explaining the relationship between the specified frequency range and the set value _f95F . The horizontal axis in FIG. 7 indicates time, and the vertical axis indicates frequency [Hz]. The standard frequency _f0 indicates the standard frequency in the electric power system. Frequency f _95F indicates the frequency corresponding to the setting value of failsafe relay 95F. The frequency _fUFR is a frequency corresponding to the setting value of a UFR (under-frequency relay) provided in the power system, separate from the power system stabilization system. Further, in FIG. 7, frequencies within a predetermined range from the standard frequency _f0 are shown as the specified range.

As shown in FIG. 7, the setpoint value f _95F is set, for example, near the lower limit of the specified range of frequencies in the power system. This is because the power system stabilization system controls load shedding as quickly as possible. On the other hand, since the UFR is a device that checks the continuation of the frequency abnormality due to the frequency drop and limits the load, its set value f _UFR is set to a value lower than the frequency f _95F .

Here, a transmission format used for information transmission between devices in a conventional power system stabilization system will be described with reference to FIG. Each device in the power system stabilization system is each device of the central processing unit 10 , the accident detection terminal device 11 , and the control terminal device 12 .

FIG. 8 is a diagram showing an example of a conventional transmission format. FIG. 8 shows an example in which transmission between devices is performed using the same format as when a current differential protection type power transmission line protection device outputs various signals. Specifically, the activation signal transmitted from the accident detection terminal device 11 to the central processing unit 10 and the control signal transmitted from the central processing unit 10 to the control terminal device 12 are bit information (0 or 1 ).

The transmission format is composed of, for example, 12 [frames] and 1080 [bits]. As for the transmission format, information of 1080 [bits] is transmitted at 20 [ms], and transmission is performed at a transmission rate of 54 [kbps]. One [frame] of the transmission format consists of 90 [bits], and is composed of frame synchronization, first word, second word, and the like.

For example, when a control signal is transmitted from the central processing unit 10 to the control terminal device 12, the bit information of the control signal transmitted to the control terminal device 12 to be controlled is set to "with control" (for example, "1"). Here, the control terminal device 12 to be controlled is the control terminal device 12 that controls the circuit breaker 5 that supplies or cuts off power to the load 2 that is the target of load limitation. is the control terminal device 12 that outputs the .

On the other hand, the central processing unit 10 sets "no control" (for example, "0") to the other control terminal devices 12 and transmits them. The other control terminal device 12 is the control terminal device 12 that controls the circuit breaker 5 that supplies or interrupts power to the load 2 that is not subject to load limitation.

Although not shown in FIGS. 6 and 8, the control terminal device 12 often controls a plurality of loads 2 as shown in FIG. Therefore, the control signal transmitted from the central processing unit 10 to the control terminal device 12 is set to "with control" or "without control" for each load 2. FIG. The control terminal device 12 cuts off the circuit breaker 5 of the corresponding load according to the received control signal.

Next, the emergency power flow control function of the DC interconnection equipment 9 will be described. As shown in FIG. 1, in a power system, a power system to be controlled may be interconnected with an external power system (hereinafter referred to as an external system) via a frequency conversion station or a DC interconnection line. In such a power system, a DC interconnecting facility 9 is provided between the external system and the power system to be controlled. The DC interconnection equipment 9 controls the power received from the external system or the power transmitted to the external system, that is, the direction and magnitude of the interconnection power flow according to the frequency fluctuation.

The DC interconnection equipment 9 has an emergency power flow control function. The emergency power flow control function of the DC interconnection equipment 9 is called emergency AFC (Auto Frequency Control) or EPPS (Emergency Power Presetting Switch). It controls the grid power flow to keep the frequency of the controlled power system within a specified range. In other words, the emergency power flow control function is a function to control the direction and magnitude of the interconnected power flow in an emergency such as a frequency abnormality.

The DC interconnection equipment 9 increases the amount of power received from the external system or decreases the amount of power transmitted to the external system when the frequency drops. On the other hand, the DC interconnection equipment 9 increases the amount of power transmitted to the external system or decreases the amount of power received from the external system when the frequency is increased.

In this way, the frequency control by the emergency power flow control function of the DC interconnection equipment 9 controls the interconnection power flow and does not limit the load that would result in a power outage of the consumer. Therefore, from the viewpoint of stable power supply, it is desirable to give priority to the control by the emergency power flow control function of the DC interconnection equipment 9 over the control by the power system stabilization system.

The Institute of Electrical Engineers of Japan Technical Report No. 1127 "Technology for Preventing Influence of Accidents by Frequency Relay System", The Institute of Electrical Engineers of Japan, September 2008

As described above, in the conventional power system stabilization system, control such as load limitation was performed under the AND condition of accident detection (control signal) and the operation of the fail-safe relay 95F.

Therefore, if the set value of the failsafe relay 95F is set near the lower limit of the frequency regulation range, high-speed control is possible in the power system stabilization system. However, on the other hand, even if the accident can be resolved by the emergency power flow control function of the DC interconnection equipment 9, the power system stabilization system will perform control first, so the emergency power flow control function It was a control that could not be utilized.

Conversely, when the set value of the fail-safe relay 95F is set lower than the frequency at which the emergency power flow control function operates, priority can be given to control by the emergency power flow control function. However, because the control of the power system stabilization system slows down, there is a risk of wide-area blackouts if the emergency power flow control function cannot resolve the frequency anomaly.

In order to solve this problem, the present invention prioritizes control by the emergency power flow control function when the frequency abnormality can be resolved by the emergency power flow control function of the DC interconnection equipment, and eliminates the frequency abnormality by the emergency power flow control function. It is an object of the present invention to provide a power system stabilization system that performs control when it cannot.

The system stabilization system of the embodiment has an accident detection terminal device, a central processing unit, and a control terminal device. The fault detection terminal device detects the occurrence of a system fault using the system information and transmits an activation signal to the central processing unit. The central processing unit preliminarily calculates and stores control content, and upon receiving the activation signal from the accident detection terminal device, refers to the stored control content and transmits the control content to the control terminal device. It transmits a control signal indicating the content of control. The control terminal device performs control on the AND condition of the reception of the control signal from the central processing unit and the operation of the fail-safe relay within the device itself. The power system stabilization system gives priority to emergency power flow control by the DC interconnection equipment, and controls supply and demand imbalance that cannot be dealt with by the emergency power flow control by the DC interconnection equipment.

The block diagram which shows the structure of the conventional power system stabilization system. The block diagram which shows the structure of the conventional power system stabilization system. FIG. 4 is a diagram for explaining processing of a conventional central processing unit 10; The figure which shows the structure of the information which shows the conventional assumption accident. The figure which shows the structure of the information which shows the content of conventional control. FIG. 4 is a diagram for explaining processing performed by a conventional control terminal device 12; The figure which shows the frequency control system of the conventional power system stabilization system. The figure which shows the example of the transmission format of the conventional power system stabilization system. The block diagram which shows the structure of the power system stabilization system of 2nd Embodiment. The block diagram which shows the structure of the power system stabilization system of 2nd Embodiment. FIG. 7 is a diagram for explaining processing of the central processing unit 10 of the second embodiment; The figure which shows the structure of the information which shows the control content of 2nd, 3rd embodiment. The figure for demonstrating the process which the control terminal device 12 of 3rd Embodiment performs. The figure which shows the example of the transmission format of the power system stabilization system of 3rd Embodiment. The figure which shows the frequency control system of the power system stabilization system of 3rd Embodiment.

A power system stabilization system according to an embodiment will be described below with reference to the drawings. In the description of the embodiments below, the response at the time of frequency drop will be described for the sake of simplicity. As for the response at the time of frequency increase, only the object to be controlled is different, and the same idea as at the time of frequency decrease can be applied.

(First embodiment)
First, the first embodiment will be explained. The configuration of the power system stabilization system of this embodiment is the same as that of the conventional power system stabilization system. That is, the configurations shown in FIGS. 1, 2, 3, and 6 have already been described. Therefore, description of the configuration of the power system stabilization system of this embodiment is omitted.

The operation of the power system stabilization system of this embodiment will be described below.
In the power system stabilization system of the present embodiment, priority is given to emergency power flow control by the DC interconnection equipment 9 . Here, prioritizing the emergency power flow control by the DC interconnection equipment 9 means that the emergency power flow control by the DC interconnection equipment 9 is performed before the load limit is performed by the power system stabilization system of the present embodiment. It means to make

In the power system stabilization system of the present embodiment, it is assumed that part of the supply and demand imbalance amount ΔP at the occurrence of an assumed accident is eliminated by emergency power flow control by the DC interconnection equipment 9 . In addition, the remaining unbalance amount shall be eliminated by the power system stabilization system. In other words, part of the supply-demand imbalance amount ΔP at the occurrence of an assumed accident is assumed to be the power amount expected to be adjusted by the emergency power flow control of the DC interconnection equipment 9 . The remaining control amount is an unbalanced amount that cannot be dealt with by emergency power flow control, and is assumed to be the electric power amount to be controlled by the power system stabilization system of the present embodiment.

The pre-computing unit 10A of the central processing unit 10 receives the interconnection power flow _PT from the power supply information network, and obtains the difference from the preset capacity _PTmax of the DC interconnection equipment 9 by the equation (2). , an adjustment range of the interconnection power flow that can be adjusted by the emergency power flow control, that is, an expected value ΔP _T of the interconnection power flow (hereinafter referred to as an expected adjustment value ΔP _T ).

ΔP _T =P _Tmax -P _T (2) where,
ΔP _T : Expected value for adjustment of interconnection power flow by emergency power flow control of DC interconnection equipment [MW]
P _Tmax : Capacity of DC interconnection facility [MW]
P _T : Interconnection power flow [MW]

In the equation (2), the polarities of the interconnection power flow _PT and the capacity _PTmax are set to + (plus, that is, a positive value) in the power receiving direction. That is, in equation (2), the direction in which the power system to be controlled receives power from the external system is assumed to be +.

The pre-computation unit 10A obtains the amount obtained by subtracting the expected adjustment value _ΔPT from the demand-supply imbalance amount ΔP at the time of occurrence of the assumed accident, using equation (3). The pre-computation unit 10A obtains the supply and demand imbalance amount ΔP at the time of occurrence of the assumed accident using the content of the assumed accident and system information such as the generator output of the generator 1 received from the power supply information network. That is, the precalculation unit 10A obtains the generator output of the generator dropped due to the assumed accident as the demand-supply imbalance amount ΔP at the occurrence of the assumed accident.

The pre-computation unit 10A subtracts the adjustment expected value ΔP _T from the supply and demand imbalance amount ΔP at the time of occurrence of the assumed accident obtained by the equation (3), The imbalance amount ΔP _SSC (hereinafter referred to as the corresponding supply and demand imbalance amount ΔP _SSC ).

ΔP _SSC =ΔP−α×ΔP _T (3) where,
ΔP _SSC : Amount of supply and demand imbalance corresponding to the power system stabilization system [MW]
ΔP _T : Expected value for adjustment of interconnection power flow by emergency power flow control of DC interconnection equipment [MW]
α: Coefficient (0<α≤1)

Here, the coefficient α in the equation (3) is a coefficient for adjusting the degree of considering the adjustment expected value _ΔPT . The coefficient α is set in advance within the range of 0<α≦1. When considering the total amount of the adjustment expected value _ΔPT , that is, when it is assumed that the total amount of the adjustment expected value _ΔPT is adjusted by the emergency power flow control of the DC interconnection equipment 9, the coefficient α is "1". is set to On the other hand, the coefficient α is set to a value smaller than 1 when the control is performed by the power system stabilization system of the present embodiment without waiting for the completion of all the emergency power flow control of the DC interconnection equipment 9 .

When the corresponding supply-demand imbalance amount ΔP _SSC obtained by the formula (3) is positive, the pre-computation unit 10A obtains the control amount for eliminating the imbalance amount by the formula (4), and obtains the target control amount. Let _PC .

P _C =ΔP _SSC −K×Δf _C ×(P ₀ −ΔP) Equation (4) where,
P _C : Target controlled variable [MW]
ΔP _SSC : Amount of supply and demand imbalance corresponding to the power system stabilization system [MW]
K: Power frequency characteristics (system constant) [1/Hz]
Δf _C : Target frequency deviation [Hz]
P ₀ : system capacity [MW]

As described above, the power system stabilization system of the first embodiment gives priority to the emergency power flow control by the DC interconnection equipment 9, (That is, the corresponding supply and demand imbalance amount ΔP _SSC ) is dealt with.

As a result, in the power system stabilization system of the first embodiment, in anticipation that the DC interconnection equipment 9 will perform emergency power flow control, in order to eliminate the supply and demand imbalance that the DC interconnection equipment 9 cannot handle. Control by the power system stabilization system is performed only during Therefore, emergency power flow control by the DC interconnection equipment 9 can be utilized. By performing emergency power flow control by the DC interconnection equipment 9, it is possible to prevent excessive control such as load restriction by the power system stabilization system. In addition, since the supply and demand imbalance that cannot be dealt with by the DC interconnection equipment 9 can be dealt with by the power system stabilization system, wide-area blackouts can be prevented.

(Second embodiment)
Next, a second embodiment will be described. This embodiment differs from the above-described embodiments in that control is performed in preparation for the case where the emergency power flow control by the DC interconnection equipment 9 does not operate correctly. Here, the case where the emergency power flow control by the DC interconnection equipment 9 does not operate correctly means that the interconnection power flow is not adjusted by the DC interconnection equipment 9, or the expected power flow is not adjusted. is not adjusted.

The power system stabilization system of the present embodiment calculates two controls, a first control and a second control, which will be described later, in preparation for the occurrence of an assumed accident. The first control is the content of load restriction corresponding to the corresponding supply and demand imbalance amount ΔP _SSC described in the above-described embodiment, and is control assuming that emergency power flow control is performed by the DC interconnection equipment 9. be. The second control is the content of load restriction by the power system stabilization system corresponding to the control expected to be implemented by the emergency power flow control by the DC interconnection equipment 9 .

The power system stabilization system of this embodiment performs the first control and monitors the interconnection power flow when an assumed accident occurs. Then, after the first control is performed, the power system stabilization system of the present embodiment additionally performs the second control when it is determined that the emergency power flow control by the DC interconnection equipment 9 is not operating correctly. .

The configuration and operation of the power system stabilization system of this embodiment will be described with reference to FIGS. 9 to 11. FIG. FIG.9 and FIG.10 is a figure which shows the structure of the power system stabilization system of 2nd Embodiment. FIG. 11 is a diagram for explaining the processing of the central processing unit 10 of the power system stabilization system of the second embodiment.

As shown in FIGS. 9 and 10 , the power system stabilization system of this embodiment includes a DC monitoring terminal device 13 . The DC monitoring terminal device 13 transmits to the central processing unit 10 tidal current interconnection information regarding interconnection tidal currents and the like.

The DC monitoring terminal device 13 includes a DC interconnection monitoring section 13A. The DC interconnection monitoring unit 13A uses the current and voltage input from the current measuring device 6 and the voltage measuring device 7 to calculate the interconnection power flow _PT . The DC interconnection monitoring unit 13A transmits the calculated interconnection power flow _PT to the central processing unit 10 as DC interconnection information. Here, the DC interconnection information such as the interconnection power flow _PT is an analog quantity. The DC interconnection information such as the interconnection power flow _PT is transmitted, for example, by setting it as a binary number, that is, bit information (0 or 1) in the second word of the transmission format shown in FIG. .

As shown in FIG. 11, the pre-computing unit 10A of the central processing unit 10 uses the interconnection power flow _PT received from the power supply information network or the DC monitoring terminal device 13 to calculate the adjustment expected value _ΔPT by equation (2). Ask. Further, the pre-computing unit 10A obtains the corresponding demand-supply imbalance amount ΔP _SSC by subtracting the adjustment expected value _ΔPT from the demand-supply imbalance amount ΔP that occurs when the assumed accident occurs, using equation (3).

When the corresponding supply-demand imbalance amount ΔP _SSC is positive, the pre-computation unit 10A obtains the control amount that eliminates the corresponding supply-demand imbalance amount ΔP _SSC using the equation (5), and calculates the target control amount P _C1 for the first control. do.

P _C1 =ΔP _SSC −K×Δf _C ×(P ₀ −ΔP) Expression (5) Here,
P _C1 : Target control amount [MW] of the first control
ΔP _SSC : Amount of supply and demand imbalance corresponding to the power system stabilization system [MW]
K: Power frequency characteristics (system constant) [1/Hz]
Δf _C : Target frequency deviation [Hz]
P ₀ : system capacity [MW]

In addition, the pre-computing unit 10A obtains the control amount expected for the emergency power flow control of the DC interconnection equipment 9 by the formula (6), and sets it as the target control amount _PC2 of the second control. The coefficient α in the equation (6) is the same value as the coefficient α used in the equation (3).

P _C2 =α×ΔP _T (6) Formula Here,
P _C2 : Target controlled variable [MW] of the second control
α: Coefficient (0<α≤1)
ΔP _T : Expected value for adjustment of interconnection power flow by emergency power flow control of DC interconnection equipment [MW]

Pre-computation unit 10A selects a combination of loads 2 so that the amount of load to be restricted is as close as possible to the target control amount for each of the first control and second control. In addition, the pre-computation unit 10A first selects the control content of the first control, and then selects the control content of the second control from among the loads 2 not selected in the first control. The pre-calculation unit 10A saves the contents of the selected first control and second control as control contents.

Here, the contents of control in the power system stabilization system of this embodiment will be described with reference to FIG. 12 . FIG. 12 is a diagram showing a configuration example of information indicating the control content of this embodiment.

As shown in FIG. 12, the control content information of the present embodiment includes the items of assumed accident case number, supply and demand imbalance amount ΔP, control content of the first control, and control content of the second control. In addition, items such as the target control amount P _C1 , the target control amount P _C2 , and the controlled object are provided as the control content of the first control and the control content of the second control. The assumed accident case number, supply and demand imbalance amount ΔP, and items to be controlled are the same as those in FIGS. The control content of the first control indicates the load 2 to be load-limited with respect to the target control amount _PC1 targeted in the first control. The control content of the second control indicates the load 2 to be load-limited with respect to the target control amount _PC2 targeted in the second control.

In the example of FIG. 12, when a route interruption accident of X transmission line occurs at power plant A, which is shown as a system fault of assumed accident case number 1, the target control amount P _C1 of the first control is P _C1-1 . , L1, L2, and L3 as loads 2 to be controlled are set to be limited. The target control amount P _C2 of the second control is P _C2-1 , and is set to limit the load L4 and L5 as the load 2 to be controlled.

When the post-calculation unit 10B receives the activation signal from the accident detection terminal device 11, the post-calculation unit 10B refers to the control details stored by the pre-calculation unit 10A based on the received activation signal. The post-calculation unit 10B first implements the control contents of the first control corresponding to the occurrence of the system failure from the stored control contents. Specifically, the post-calculation unit 10B sends the control terminal device 12 that controls the loads 2 (L1, L2, and L3 in the example of FIG. 12) selected as the control content of the first control Send a control signal to instruct load shedding.

In addition, after receiving the activation signal, the post-calculation unit 10B, for example, for a predetermined period of time or a period of time until the frequency recovers within a specified range, the interconnection power flow _PT received from the DC monitoring terminal device 13 to monitor. If the interconnection power flow _PT does not increase, the post-calculation unit 10B determines that the emergency power flow control is not operating correctly. When the post-calculation unit 10B determines that the emergency power flow control is not operating properly, the post-calculation unit 10B additionally transmits a control signal to the control terminal device 12 with reference to the control content of the second control. That is, the post-calculation unit 10B instructs the control terminal device 12 that controls the load 2 (L4 and L5 in the example of FIG. 12) selected as the control content of the second control to limit the load of these loads 2. Send a control signal to

The post-calculation unit 10B determines whether or not the interconnection power flow _PT has changed in the increasing direction based on the amount of change in the interconnection power flow _PT at a constant time interval ΔT. For example, when the equation (7) holds, the post-calculation unit 10B determines that the interconnection power flow _PT has not changed in the increasing direction.

P _T (t)<P _T (t−ΔT) (7) where,
P _T (t): Interconnected power flow at time t t: Current time ΔT: Time interval

The DC interconnection information used for determining the operation of emergency power flow control is not limited to the interconnection power flow _PT . Operation determination of emergency power flow control is determination as to whether or not emergency power flow control is operating correctly. That is, in the above description, the case of determining whether or not emergency power flow control is operating correctly is described as an example, depending on whether or not the interconnection power flow _PT has changed in the increasing direction. not limited.

For example, the post-calculation unit 10B may determine the operation of emergency power flow control based on the state of the DC interconnection equipment 9 (for example, normal/abnormal binary information). In this case, the DC monitoring terminal device 13 captures the state of the DC interconnection equipment 9 and transmits it to the central processing unit 10 . Then, if the information indicating the state of the DC interconnection equipment 9 acquired from the DC monitoring terminal device 13 indicates an abnormality, the post-calculation unit 10B determines that the emergency power flow control is not operating correctly, A control signal for executing the second control is transmitted to the control terminal device 12 .

Further, the post-calculation unit 10B may perform operation determination of emergency power flow control based on the power state (for example, voltage value) of the bus 3 and the transmission line 4 connected to the DC interconnection equipment 9 . In this case, the DC monitoring terminal device 13 transmits to the central processing unit 10 the voltage input from the voltage measuring device 7 provided on the bus 3 or transmission line 4 connected to the DC interconnection equipment 9 . Then, when the voltage value of the bus 3 or the transmission line 4 connected to the DC interconnection equipment 9 drops below a preset value at the occurrence of an assumed accident, the post-calculation unit 10B prevents the emergency power flow control from operating correctly. It is determined that the second control is not performed, and a control signal for executing the second control is transmitted to the control terminal device 12 .

Further, the post-calculation unit 10B may determine the operation of emergency power flow control based on the state of the frequency. In this case, the DC monitoring terminal device 13, or the accident detection terminal device 11, or the control terminal device 12 measures the frequency from the voltage input from the voltage measuring device 7, and transmits the measured frequency to the central processing unit 10. . Then, if the post-calculation unit 10B determines that the frequency after performing the first control has not changed to the recovery trend, it determines that the emergency power flow control is not operating correctly, and causes the second control to be performed. A control signal is transmitted to the control terminal device 12 .

As described above, in the second power system stabilization system, the central processing unit 10 provides the first control and the second control. The first control is a control that gives priority to emergency power flow control by the DC interconnection equipment 9 . The second control is a control that is executed when the emergency power flow control does not operate correctly. The central processing unit 10 calculates and obtains the contents of each of the first control and the second control. When the central processing unit 10 receives the activation signal from the accident detection terminal device, it first transmits a control signal for the first control to the control terminal device. The central processing unit 10 monitors the operating state of the emergency power flow control using the DC interconnection information before and after the occurrence of the accident, and when it is determined that the emergency power flow control is not operating correctly, outputs the control signal for the second control. Send additionally to the control terminal.

As a result, in the power system stabilization system of the second embodiment, in addition to the effects of the first embodiment described above, when the emergency power flow control by the DC interconnection equipment 9 does not operate correctly, the power system stabilization system can be handled by Therefore, even when the emergency power flow control fails (does not operate correctly), the impact of the accident can be suppressed and wide-area blackouts can be prevented.

(Third embodiment)
Next, a third embodiment will be described. In this embodiment, two control signals to which information for distinguishing between the first control and the second control are attached by the central processing unit 10 are transmitted to the control terminal device 12 when an accident occurs; This embodiment differs from the above-described embodiment in that the terminal device 12 determines whether or not to perform the second control.

The configuration of the power system stabilization system of this embodiment is the same as the conventional power system stabilization system described above and the first embodiment, except for a control terminal device 12, which will be described later. That is, the configurations shown in FIGS. 1, 2, 3, and 6 have already been described. Therefore, description of the configuration of the power system stabilization system of this embodiment is omitted.

The configuration of the control terminal device 12 of this embodiment will be described with reference to FIG. FIG. 13 is a block diagram showing the configuration of the control terminal device 12 of this embodiment. The control terminal device 12 of the present embodiment includes a functional unit that holds control signals (holding of control signals), a failsafe relay 95F1, and a failsafe relay 95F2.

The functional unit that holds the control signal (holding of control signal) holds the control signals of the first control and the second control received by the control terminal device 12 from the central processing unit 10 while distinguishing them from each other. A functional unit that holds the control signal (holding of the control signal) performs the first control and the second control based on the signal that distinguishes the first control and the second control from each other, which is given to each control signal. keep them separate.

Failsafe relay 95F1 is a frequency relay that prevents malfunction of the first control. Failsafe relay 95F1 operates at a predetermined setpoint f _95F1 . That is, when the frequency measured based on the voltage obtained from the voltage measuring instrument 7 is less than the predetermined setting value _f95F1 (or equal to or less than the setting value _f95F1 ), the failsafe relay 95F1 provides a signal indicating that fact. (95F1 operation) is output. By this fail-safe relay operation, the control terminal device 12 receives the control signal of the first control, and when the frequency becomes less than a predetermined set value f _95F1 (or set value f _95F1 or less), the cutoff Outputs a shutdown command to the device 5. Here, the breaker 5 to which the break command is output is the breaker 5 that controls (supplies or cuts off power to the load 2) the load 2 that is subject to load limitation in the first control.

Failsafe relay 95F2 is a frequency relay that prevents malfunction of the second control. Failsafe relay 95F2 operates at a predetermined setpoint f _95F2 . That is, when the frequency measured based on the voltage obtained from the voltage measuring instrument 7 is less than the predetermined setting value _f95F2 (or equal to or less than the setting value _f95F2 ), the failsafe relay 95F2 provides a signal indicating that fact. (95F2 operation) is output. By this fail-safe relay operation, the control terminal device 12 receives the control signal of the second control, and when the frequency becomes less than the predetermined set value f _95F2 (or set value f _95F2 or less), the cutoff Outputs a shutdown command to the device 5. Here, the breaker 5 to which the break command is output is the breaker 5 that controls (supplies or cuts off power to the load 2) the load 2 that is subject to load limitation in the second control.

The operation of the power system stabilization system of this embodiment will be described below.
In the power system stabilization system of this embodiment, as in the second embodiment described above, when the first control that prioritizes the emergency power flow control of the DC interconnection equipment 9 and the emergency power flow control do not operate correctly The second control provided is precomputed by the central processing unit 10 .

The pre-computing unit 10A of the central processing unit 10 uses the interconnection power flow _PT received from the power supply information network to find the adjustment expected value _ΔPT by formula (2). Further, the pre-computing unit 10A obtains the corresponding demand-supply imbalance amount ΔP _SSC by subtracting the adjustment expected value _ΔPT from the demand-supply imbalance amount ΔP that occurs when the assumed accident occurs, using equation (3). Then, when the corresponding supply-demand imbalance amount ΔP _SSC is positive, the pre-computation unit 10A obtains the control amount that eliminates the corresponding supply-demand imbalance amount ΔP _SSC using the equation (5), and calculates the target control amount P _C1 for the first control. and In addition, the pre-computing unit 10A obtains the control amount expected for the emergency power flow control of the DC interconnection equipment 9 by the formula (6), and sets it as the target control amount _PC2 of the second control.

For each of the first control and the second control, the pre-computation unit 10A selects a combination of the loads 2 so that the load amounts to be restricted are as close to the target control amounts P _{C1 and} P _C2 as possible. In addition, the pre-computation unit 10A first selects the control content of the first control, and then selects the control content of the second control from among the loads 2 not selected in the first control. The pre-calculation unit 10A saves the contents of the selected first control and second control as control contents. The contents of control are, for example, contents as shown in FIG.

When the post-calculation unit 10B receives the activation signal from the accident detection terminal device 11, the post-calculation unit 10B refers to the control details stored by the pre-calculation unit 10A based on the received activation signal. From the stored control details, the post-calculation unit 10B gives two control signals respectively indicating the control details of the first control and the second control corresponding to the accident that has occurred a signal capable of distinguishing between the control signals. , to the control terminal device 12 .

Here, a signal capable of distinguishing control signals from each other will be described with reference to FIG. 14 . FIG. 14 is a diagram showing an example of the transmission format of this embodiment. Since the frame structure of the transmission format of this embodiment is the same as that of the conventional transmission format shown in FIG. 8, the description thereof will be omitted.

The central processing unit 10, for example, sets the control signal (control signal 1) of the first control to the bit where the conventional control signal is set in the first word. Also, the central processing unit 10 sets the control signal for the second control (control signal 2) to the next bit of the control signal for the first control. In this way, the central processing unit 10 assigns signals that can be distinguished from each other, for example, by setting the positions of the bits that set the control signals of the first control and the second control to different positions in the transmission format.

Here, the relationship between the setting value f _95F1 and the setting value f _95F2 will be described with reference to FIG. FIG. 15 is a diagram illustrating the relationship between the _{setting value f 95F1 and} the setting value f 95F2 in the third embodiment. The horizontal axis, vertical axis, standard frequency f _{0 ,} frequency f _UFR , and prescribed range in FIG. 15 are the same as in FIG.

As shown in FIG. 15, the first control is a control that is performed without waiting for the operation of emergency power flow control. Therefore, the setting value f _95F1 of the failsafe relay 95F1 is set near the lower limit of the specified range. On the other hand, the second control is a control that is performed as a backup when the emergency power flow control does not operate properly. Therefore, the setting value f _95F2 of the fail-safe relay 95F2 is set to a lower value than the setting value f _95F1 .

As described above, in the power system stabilization system of the third embodiment, the central processing unit 10 provides first control and second control. The first control is a control that gives priority to emergency power flow control by the DC interconnection equipment 9 . The second control is a control that is executed when the emergency power flow control does not operate correctly. The central processing unit 10 calculates and obtains the contents of each of the first control and the second control. When the central processing unit 10 receives the activation signal from the accident detection terminal device, the central processing unit 10 gives the control signals for the first control and the second control a signal that can be distinguished from each other and transmits them to the control terminal device 12 . The control terminal device 12 includes failsafe relays corresponding to the first control and the second control.

As a result, in the power system stabilization system of the third embodiment, in addition to the effects of the first embodiment described above, when the emergency power flow control by the DC interconnection equipment 9 does not operate correctly, the power system stabilization system can be handled by Therefore, even when the emergency power flow control fails (does not operate correctly), the impact of the accident can be suppressed and wide-area blackouts can be prevented.

According to at least one embodiment described above, priority is given to the emergency power flow control by the DC interconnection equipment 9, and the supply and demand imbalance that cannot be handled by the emergency power flow control by the DC interconnection equipment 9 (that is, the corresponding supply and demand imbalance quantity ΔP _SSC ) is addressed by the power system stabilization system. As a result, the emergency power flow control by the DC interconnection equipment 9 can be utilized, and it is possible to prevent excessive control such as load restriction by the power system stabilization system.

While several embodiments of the invention have been described, these embodiments have been presented by way of example and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, replacements, and modifications can be made without departing from the scope of the invention. These embodiments and their modifications are included in the scope and spirit of the invention, as well as the scope of the invention described in the claims and equivalents thereof.

DESCRIPTION OF SYMBOLS 1... Generator, 2... Load, 3... Bus, 4... Transmission line or transformer, 5... Circuit breaker, 6... Current measuring instrument, 7... Voltage measuring instrument, 8... Communication equipment, 9... DC interconnection equipment, DESCRIPTION OF SYMBOLS 10... Central processing unit, 11... Accident detection terminal device, 12... Control terminal device, 13... DC monitoring terminal device

Claims (3)

An accident detection terminal device that detects the occurrence of a system fault using system information and transmits a start signal to the central processing unit;
A control content is calculated and stored in advance, and when the start signal is received from the accident detection terminal device, the stored control content is referred to, and a control signal indicating the control content is sent to the control terminal device. a central processing unit that transmits
a control terminal device that receives the control signal from the central processing unit and performs control under the AND condition of the fail-safe relay operation within the device;
a DC monitoring terminal device that takes in information indicating the state of the DC interconnection equipment and transmits it to the central processing unit;
A power system stabilization system comprising:
Using the information indicating the state of the DC interconnection equipment received from the DC monitoring terminal device and the interconnection power flow received from the power supply information network , priority is given to emergency power flow control by the DC interconnection equipment, and the DC interconnection equipment Control the supply and demand imbalance that cannot be handled by emergency power flow control,
A power system stabilization system characterized by: The central processing unit is provided with a first control that prioritizes the emergency power flow control by the DC interconnection facility and a second control that is implemented when the emergency power flow control does not operate properly, The control contents of each of the first control and the second control are calculated, and when an activation signal indicating the occurrence of an accident is received from the accident detection terminal device, the control signal for the first control is first transmitted to the control terminal device. and monitor the operating state of the emergency power flow control using the DC interconnection information before and after the occurrence of the accident, and when it is determined that the emergency power flow control is not operating correctly, the second control additionally transmitting a control signal to the control terminal device;
The power system stabilization system according to claim 1, characterized by: The central processing unit is provided with a first control that prioritizes the emergency power flow control by the DC interconnection facility and a second control that is implemented when the emergency power flow control does not operate properly, The control contents of each of the first control and the second control are calculated, and when an activation signal indicating the occurrence of an accident is received from the accident detection terminal device, the control signal of each of the first control and the second control is Add a signal that can be distinguished from each other and transmit it to the control terminal device 12,
The control terminal device includes a fail-safe relay corresponding to each of the first control and the second control,
The power system stabilization system according to claim 1, characterized by:

Images