JP2020137299A - Electric power system stabilization system - Google Patents

Abstract

To provide an electric power system stabilization system which can utilize control by an emergency flow control function.SOLUTION: The system stabilization system includes an accident detection terminal device, a central processing unit and a control terminal device. The accident detection terminal device detects the occurrence of a system accident using system information to transmit an activation signal to the central processing unit. The central processing unit calculates and stores control contents in advance, and on receiving the activation signal from the accident detection terminal device, refers to the control contents stored in advance to transmit a control signal indicative of the control contents to the control terminal device. The control terminal device performs control under the AND condition of the reception of the control signal from the central processing unit and the operation of a fail safe relay in the self-device. The electric power system stabilization system prioritizes emergency flow control by a DC interconnection facility, to control for a supply and demand unbalance which cannot be coped with by the emergency flow control by the DC interconnection facility.SELECTED DRAWING: Figure 1

Description

An embodiment of the present invention relates to a power system stabilization system that suppresses an abnormality in a frequency that occurs due to a system accident and maintains the frequency within a specified range.

A frequency abnormality in an electric power system (hereinafter, frequency abnormality) means that the balance between the load amount and the amount of power generation in the electric power system, that is, the balance between supply and demand of electric power (hereinafter, supply and demand balance) is lost, and the frequency is within the specified range (hereinafter, frequency abnormality). Below, it is 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 controlling the frequency, as a standard frequency (hereinafter, standard frequency) ± 0.2 Hz, and some electric power companies have a standard frequency ± 0. The power system is operated so as to maintain the frequency within this specified range by setting it at 0.3 Hz.

For the gradual supply-demand imbalance (state in which the supply-demand balance of electric power is lost) that occurs as the demand for electric power fluctuates, load frequency control (LFC, Load Frequency Control) and speed governor are used to generate electricity. It controls the machine output, that is, the amount of power supplied. Therefore, since the frequency is maintained within the specified range, it is unlikely that a frequency abnormality will occur. The speed governor is a device that controls the rotation speed of the turbine of the generator.

A large-capacity generator may be disconnected (power dropped) from the power system due to a serious system accident such as an accident that cuts off the transmission line route or an accident that spans multiple buses. If the system that supplies power to the load is separated (load is dropped), a sudden imbalance between supply and demand occurs. In this case, the frequency may deviate from the specified range and lead to a frequency abnormality. Therefore, a frequency relay system is installed in the power system to eliminate or prevent frequency abnormality.

The frequency relay system is a system that maintains a balance between supply and demand of electric power by performing controls such as load limitation and generator cutoff according to the frequency condition in the electric power system. The frequency relay system includes an insufficient frequency relay (UFR, Under Frequency Relay) of the distributed control method that detects the occurrence of a frequency abnormality and controls it, an overfrequency relay (OFR, Over Frequency Relay), and a power of the central control method. There is a system stabilization system.

The power system stabilization system assumes an accident (assumed accident) that is likely to lead to a frequency abnormality in advance, and controls the control content (load limit and power generation) to maintain the frequency within the specified range when an assumed accident occurs. Calculate and store the machine shutoff, etc.) in advance. Then, in the power system stabilization system, when the occurrence of an assumed accident is actually detected, control is immediately executed.

In the power system stabilization system, control can be performed after an assumed accident occurs and before the power system becomes a frequency abnormality. Therefore, there is a feature that it is possible to deal with a system accident that causes a sudden imbalance between supply and demand, which cannot maintain stable operation of the power system by controlling after confirming a frequency abnormality.

Frequency anomalies include both sides when the frequency drops (frequency drops) and rises (frequency rises) with respect to the standard frequency. The power system stabilization system shuts off the pump and limits the load when the frequency drops, and shuts off the generator when the frequency rises. A pump is a generator in operation of a pump that pumps 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 the conventional power system stabilization system will be described with reference to FIGS. 1 and 2.

In the following, in order to simplify the explanation, the response when the frequency drops will be described. Regarding the response when the frequency rises, only the control target is different, and the same concept as when the frequency falls 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 includes a central processing unit 10, an accident detection terminal device 11, and a control terminal device 12.

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 instrument (CT), 7 is a voltage measuring instrument (VT), and 8 is. Communication equipment, 9 is DC interconnection equipment, 10 is the central computing device of the conventional power system stabilization system, 11 is the accident detection terminal device of the conventional power system stabilization system, and 12 is the control of the 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 in 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 has a system capacity, an active power output of a generator (hereinafter, a generator output), and an active power consumed by a load (hereinafter, an active power). System information such as load amount) is often installed at power supply control stations and major electric stations that can receive system information from the power supply information network.

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

As shown in FIG. 1, the central processing unit 10 includes a pre-calculation unit 10A and a post-calculation unit 10B. Hereinafter, the processing of the central processing unit 10 will be described with reference to FIG.

FIG. 3 is a diagram for explaining the processing of the conventional central processing unit 10. The pre-calculation 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 P ₀ from the power supply information network. The pre-calculation unit 10A uses the system information, the preset power frequency characteristic K, and the target frequency deviation Δf _C, and uses, for example, the target control amount P required to maintain the frequency when an assumed accident of power failure occurs. _C is calculated by the following equation (1).

_{P C = ΔP-K × Δf} C × (P 0 -ΔP) ... (1) Equation where,
P _C: target control amount [MW]
ΔP: Unbalanced supply and demand at the time of an 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 supply-demand imbalance amount ΔP when an assumed accident occurs is + (plus, that is, a positive value) when the amount of power generation is less than the load amount. That is, in the equation (1), when the supply-demand imbalance amount ΔP at the time of the assumed accident occurs is +, the load is limited according to the magnitude.

Pre calculation unit 10A, based on the calculated target control amount P _C, load limiting load (hereinafter, control contents) selecting from the plurality of load 2, and stores.

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. The load amount of may be acquired.

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

Here, the assumed accident and the control contents in the conventional power system stabilization system will be described with reference to FIGS. 4 and 5. 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 a conventional control content.

As shown in FIG. 4, the information on the assumed accident includes items such as the assumed accident case number, the monitoring point, and the accident aspect. The assumed accident case number indicates the number assigned to the assumed accident. The monitoring points indicate the points where the assumed accident is expected to occur. The details of the assumed accident are shown in the accident aspect.

As shown in FIG. 5, the control content information includes items such as an assumed accident case number, a supply-demand imbalance amount ΔP, and a control content. Also comprises a control content, target control amount P _C, items such as the control target. The assumed accident case number is a number corresponding to the assumed accident case number in FIG. The supply-demand imbalance amount ΔP indicates the supply-demand imbalance amount when an assumed accident occurs. The control target indicates a load 2 for load limiting.

In the example of FIGS. 4 and 5, shown as an accident of postulated accident case number 1, if a route blocking accident X transmission line occurs in the A power plant, the target control quantity P _C is P _C-1, the control The load is limited to L1, L2, and L3 as the target load 2.

The accident detection terminal device 11 is used in the A power plant 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 value. Detects the occurrence of a route cutoff accident on the X transmission line. Further, the accident detection terminal device 11 may detect a route cutoff accident of the X transmission line by acquiring an operation signal of the protection device of the X transmission line and the bus protection device of the A power plant. The protection device is a device that minimizes the influence of an accident and protects the power system by outputting an operation signal that shuts off the circuit breaker when an accident on a transmission line or a bus is detected.

The post-calculation unit 10B receives the start signal from the accident detection terminal device 11. The start signal is a signal instructing that the control content is executed when a system accident is detected by the accident detection terminal device 11. The post-calculation unit 10B refers to the control content stored by the pre-calculation unit 10A based on the received start signal. The post-calculation unit 10B executes the control content of the assumed accident from the stored control content. 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 that the load 2 controlled by the control terminal device 12 is load-limited (the supply of electric power to the load 2 is cut off).

Returning to FIG. 1, the control terminal device 12 includes a control unit 12A. When the control terminal device 12 receives the control signal from the central processing unit 10, the control terminal device 12 opens the circuit breaker 5 of the load 2. Hereinafter, the processing performed by the control terminal device 12 will be described with reference to FIG.

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

The fail-safe relay 95F acquires the bus voltage from the voltage measuring instrument 7 and calculates the frequency from the acquired bus voltage. When the calculated frequency is less than a predetermined threshold value (set value f _95F ) (or less than or equal to a predetermined threshold value), the fail-safe relay 95F outputs a signal (95F operation) to that effect.

The control terminal device 12 outputs a circuit breaker command to the circuit breaker 5 to which the load 2 is connected under the AND condition of the control signal and the signal indicating the decrease in frequency from the fail-safe relay 95F (95F operation), and causes the circuit breaker 5 to operate. Open the pole. The cutoff command is a signal for commanding the cutoff of the electric power supplied to the load 2. As a result, the control terminal device 12 not only receives the control signal from the central processing unit 10, but also limits the load when the frequency actually drops _{below the} predetermined set value f _95F , thereby causing a malfunction. To prevent. Here, the set value f _95F of the fail-safe relay 95F is set near the lower limit of the specified range so that it can be detected that the frequency of the fail-safe relay 95F deviates from the specified range.

Here, the relationship between the specified frequency range and the set value f _95F in the conventional power system stabilization system will be described with reference to FIG. 7. FIG. 7 is a diagram for explaining the relationship between the specified frequency range and the set value f _95F . The horizontal axis of FIG. 7 represents time, and the vertical axis represents frequency [Hz]. The standard frequency f ₀ indicates a standard frequency in the power system. The frequency f _95F indicates a frequency corresponding to the set value of the fail-safe relay 95F. The frequency f _UFR is a frequency corresponding to the set value of the UFR (insufficient frequency relay) provided in the power system separately from the power system stabilization system. Further, FIG. 7 shows the frequency from the standard frequency f ₀ in a predetermined range as the specified range.

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

Here, the transmission format used for transmitting information between each device in the 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 is performed between the devices using the same format as when the current differential protection type transmission line protection device outputs various signals. Specifically, the start 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 have bit information (0 or 1) according to this transmission format. ) Is transmitted.

The transmission format is composed of, for example, 12 [frames] and 1080 [bits]. Further, in the transmission format, 1080 [bit] information is transmitted at 20 [ms], and transmission is performed at a transmission speed of 54 [kbps]. One [frame] of the transmission format is composed of 90 [bits], and is composed of frame synchronization, a first word, a second word, and the like as a breakdown.

For example, when the control signal is transmitted from the central processing unit 10 to the control terminal device 12, the bit information of the control signal to be 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 a control terminal device 12 that controls a circuit breaker 5 that supplies or cuts off power to a load 2 that is subject to load limitation, and gives a cutoff command to the circuit breaker 5. It is a control terminal device 12 that outputs.

On the other hand, the central processing unit 10 is set to "no control" (for example, "0") and transmitted to the other control terminal device 12. The other control terminal device 12 is a control terminal device 12 that controls a circuit breaker 5 that supplies or cuts off power to a load 2 that is not subject to load limitation.

Although the description is omitted in FIGS. 6 and 8, as shown in FIG. 2, the control terminal device 12 often controls a plurality of loads 2. 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. The control terminal device 12 shuts 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 facility 9 will be described. As shown in FIG. 1, in the power system, the power system to be controlled may be connected to an external power system (hereinafter, external system) by a frequency converter station or a DC interconnection line. In such a power system, a DC interconnection facility 9 is provided between the external system and the power system to be controlled. The DC interconnection facility 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 facility 9 has an emergency power flow control function. The emergency power flow control function of the DC interconnection facility 9 is called emergency AFC (Auto Frequency Control) or EPPS (Emergency Power Presetting Switch), and tends to maintain a balance between supply and demand when the frequency deviates from the specified range. The interconnection power flow is controlled to keep the frequency of the controlled power system within the specified range. That is, the emergency tidal current control function is a function of controlling the direction and magnitude of the interconnection tidal current in an emergency such as a frequency abnormality.

The DC interconnection facility 9 increases the amount of power received from the external system or reduces the amount of power transmitted to the external system when the frequency drops. On the other hand, the DC interconnection facility 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 rises.

As described above, in the frequency control by the emergency power flow control function of the DC interconnection equipment 9, the interconnection power flow is controlled and the load is not limited so as to cause a power failure of the consumer. Therefore, from the viewpoint of stable power supply, it is desirable to prioritize the control by the emergency power flow control function of the DC interconnection facility 9 over the control by the power system stabilization system.

IEEJ Technical Report No. 1127 "Accident Ripple Prevention Technology by Frequency Relay System", Institute of Electrical Engineers of Japan, September 2008

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

Therefore, if the set value of the fail-safe 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 frequency abnormality can be resolved by the emergency power flow control function of the DC interconnection facility 9, the power system stabilization system controls the frequency first, so that the emergency power flow control function is used. It was a control that could not be utilized.

On the contrary, 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, the control by the emergency power flow control function can be prioritized. However, since the control of the power system stabilization system is slowed down, there is a risk of a wide-area power outage if the frequency abnormality cannot be resolved by the emergency power flow control function.

In order to solve this problem, the present invention gives priority to control by the emergency power flow control function when the frequency abnormality can be solved by the emergency power flow control function of the DC interconnection facility, and solves the frequency abnormality by the emergency power flow control function. An object of the present invention is to provide a power system stabilization system that controls when it cannot be performed.

The system stabilization system of the embodiment includes an accident detection terminal device, a central processing unit, and a control terminal device. The accident detection terminal device detects the occurrence of a system accident using system information and transmits a start signal to the central processing unit. The central processing unit calculates and stores the control contents in advance, and when the start signal is received from the accident detection terminal device, the central processing unit refers to the stored control contents and sends the control terminal device to the control terminal device. A control signal indicating the control content is transmitted. The control terminal device performs control under AND conditions of receiving the control signal from the central processing unit and operating a fail-safe relay in the own device. The power system stabilization system gives priority to emergency power flow control by the DC interconnection equipment, and controls an unbalanced supply and demand that cannot be handled 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. The figure for demonstrating the processing of the conventional central processing unit 10. The figure which shows the structure of the information which shows the conventional assumed accident. The figure which shows the structure of the information which shows the conventional control content. The figure for demonstrating the process performed by the conventional control terminal apparatus 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. The figure for demonstrating the processing of the central processing unit 10 of the 2nd Embodiment. The figure which shows the structure of the information which shows the control content of the 2nd and 3rd Embodiment. The figure for demonstrating the process performed by the control terminal apparatus 12 of the 3rd Embodiment. 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.

Hereinafter, the power system stabilization system of the embodiment will be described with reference to the drawings. In the following description of the embodiment, in order to simplify the description, the response at the time of frequency decrease will be described. Regarding the response when the frequency rises, only the control target is different, and the same concept as when the frequency falls can be applied.

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

Hereinafter, the operation of the power system stabilization system of the present embodiment will be described.
In the power system stabilization system of the present embodiment, priority is given to emergency power flow control by the DC interconnection facility 9. Here, giving priority to emergency power flow control by the DC interconnection facility 9 means that emergency power flow control by the DC interconnection facility 9 is performed before the load is limited by the power system stabilization system of the present embodiment. To say.

In the power system stabilization system of the present embodiment, it is premised that a part of the supply-demand imbalance amount ΔP at the time of the assumed accident is eliminated by the emergency power flow control by the DC interconnection facility 9. In addition, the remaining unbalanced amount shall be eliminated by the power system stabilization system. That is, of the supply-supply imbalance amount ΔP at the time of the assumed accident, a part of the unbalance amount is the electric energy expected to be adjusted by the emergency power flow control of the DC interconnection facility 9. Further, the remaining control amount is an unbalanced amount that cannot be dealt with by the emergency power flow control, and is the amount of power to be controlled by the power system stabilization system of the present embodiment.

The pre-calculation unit 10A of the central processing unit 10 receives the interconnection tidal current _PT from the power supply information network, and obtains the difference from the preset capacity _{PT max} of the DC interconnection equipment 9 by the equation (2). , emergency adjustable interconnection tide adjustment range by flow controller, i.e., interconnection tide expectation [Delta] P T _{(hereinafter,} adjusting the expected value [Delta] P _T) to.

_{ΔP T = P Tmax -P T ...} (2) equation here,
[Delta] P _T: adjusting the expected value of the interconnection power flow due to emergency flow controller of DC interconnection facilities [MW]
_PTmax : Capacity of DC interconnection equipment [MW]
_PT : Interconnection tide [MW]

In Eq. (2), the polarities of the interconnected tidal current _PT and the capacitance _PTmax are + (plus, that is, a positive value) in the power receiving direction. That is, in the equation (2), the direction in which the power system to be controlled receives power from the external system is +.

Pre calculation unit 10A is the amount obtained by subtracting the adjusted expected value [Delta] P _T from supply unbalance amount [Delta] P during postulated accident occurs, determined by equation (3). The pre-calculation unit 10A obtains the supply-demand imbalance amount ΔP at the time of the assumed accident by using the content of the assumed accident and the system information such as the generator output of the generator 1 received from the power supply information network. That is, the pre-calculation unit 10A obtains the generator output of the generator that falls off due to the assumed accident as the supply-demand imbalance amount ΔP at the time of the assumed accident.

Precomputed section 10A, (3) was determined by the equation, corresponding demand for the amount obtained by subtracting the adjusted expected value [Delta] P _T from supply unbalance amount [Delta] P during postulated accident occurs, corresponding with the power system stabilizing system of this embodiment The unbalanced amount ΔP _SSC (hereinafter referred to as the corresponding supply-demand unbalanced amount ΔP _SSC ).

ΔP _SSC = ΔP−α × ΔP _T … (3) Equation Here,
ΔP _SSC : Corresponding supply-demand imbalance amount [MW] supported by the power system stabilization system
[Delta] P _T: adjusting the expected value of the interconnection power flow due to emergency flow controller of DC interconnection facilities [MW]
α: Coefficient (0 <α ≦ 1)

Here, (3) the coefficient α in the formula is a coefficient for adjusting the degree to consider adjusting the expected value [Delta] P _T. The coefficient α is preset in the range of 0 <α ≦ 1. When considering the total amount of the adjustment expectation [Delta] P _T, that is, the emergency power flow control of the DC interconnection equipment 9, when the total amount of the adjustment expectation [Delta] P _T is assumed to be adjusted, the coefficient alpha, "1" Is set to. On the other hand, when the power system stabilization system of the present embodiment controls the DC interconnection equipment 9 without waiting for the entire amount of emergency power flow control to be completed, the coefficient α is set to a value smaller than 1.

When the corresponding supply-demand imbalance amount ΔP _SSC is positive, the pre-calculation unit 10A obtains the control amount for eliminating the unbalance amount obtained by the equation (3) by the equation (4), and obtains the target control amount. and P _C.

_{P C = ΔP SSC -K × Δf} C × (P 0 -ΔP) ... (4) equation, where
P _C: target control amount [MW]
ΔP _SSC : Corresponding supply-demand imbalance amount [MW] supported by the power system stabilization system
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, and the supply and demand imbalance that cannot be dealt with by the emergency power flow control by the DC interconnection equipment 9. (That is, the corresponding supply-demand imbalance amount ΔP _SSC ) is dealt with.

As a result, in the power system stabilization system of the first embodiment, in anticipation that emergency power flow control will be performed by the DC interconnection facility 9, in order to eliminate the supply-demand imbalance that cannot be handled by the DC interconnection facility 9. Only in is controlled by the power system stabilization system. Therefore, the emergency power flow control by the DC interconnection facility 9 can be utilized. By performing emergency power flow control by the DC interconnection facility 9, it is possible to prevent excessive control such as load limitation by the power system stabilization system. Moreover, since the power system stabilization system can handle the unbalanced supply and demand that cannot be handled by the DC interconnection facility 9, it is possible to prevent a wide-area power outage.

(Second Embodiment)
Next, the second embodiment will be described. The present embodiment is different from the above-described embodiment in that the emergency power flow control by the DC interconnection facility 9 is performed in case the emergency power flow control does not operate correctly. Here, when the emergency tidal current control by the DC interconnection facility 9 does not operate correctly, the interconnection tidal current is not adjusted by the DC interconnection facility 9, or the tidal current is expected to be adjusted. Means that is not adjusted.

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

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

The configuration and operation of the power system stabilization system of the present embodiment will be described with reference to FIGS. 9 to 11. 9 and 10 are diagrams showing the configuration of the power system stabilization system of the second 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 the present embodiment includes a DC monitoring terminal device 13. The DC monitoring terminal device 13 transmits tidal current interconnection information regarding the interconnection tidal current to the central processing unit 10.

The DC monitoring terminal device 13 includes a DC interconnection monitoring unit 13A. The DC interconnection monitoring unit 13A calculates the interconnection power flow _PT using the current and voltage input from the current measuring instrument 6 and the voltage measuring instrument 7. The DC interconnection monitoring unit 13A transmits the calculated interconnection power flow _PT as DC interconnection information to the central processing unit 10. Here, the DC interconnection information such as the interconnection tidal current _PT is an analog quantity. The DC interconnection information such as the interconnection current _PT is transmitted by being set as a binary number, that is, bit information (0 or 1) in the second word or the like of the transmission format shown in FIG. 8, for example. ..

As shown in FIG. 11, the pre-calculation unit 10A of the central processing unit 10 uses the interconnection power flow P _T received from the feeding information network or direct-current monitoring terminal device 13, the adjustment expectation ΔP _T (2) expression in Ask. Also, pre-calculating section 10A, the supply-demand imbalance amount [Delta] P caused when the assumed fault occurs, by subtracting the adjustment expectation [Delta] P _T, the corresponding supply and demand unbalance amount [Delta] P _SSC, determined in (3) below.

When the corresponding supply-demand imbalance amount ΔP _SSC is positive, the pre-calculation unit 10A obtains the control amount for eliminating the corresponding supply-demand imbalance amount ΔP _SSC by the equation (5), and sets the target control amount _PC1 of the first control. To do.

_{P C1 = ΔP SSC -K × Δf} C × (P 0 -ΔP) ... (5) formula, where
_PC1 : Target control amount of the first control [MW]
ΔP _SSC : Corresponding supply-demand imbalance amount [MW] supported by the power system stabilization system
K: Power frequency characteristics (system constant) [1 / Hz]
Δf _C : Target frequency deviation [Hz]
P ₀ : System capacity [MW]

Further, the pre-calculation unit 10A obtains the control amount expected for the emergency power flow control of the DC interconnection facility 9 by the equation (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 value of the coefficient α used in the equation (3).

_PC2 = α × ΔP _T ... (6) Equation Here,
_PC2 : Target control amount of the second control [MW]
α: Coefficient (0 <α ≦ 1)
[Delta] P _T: adjusting the expected value of the interconnection power flow due to emergency flow controller of DC interconnection facilities [MW]

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

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

As shown in FIG. 12, the control content information of the present embodiment includes the items of the assumed accident case number, the supply-demand imbalance amount ΔP, the control content of the first control, and the control content of the second control. Further, as the control content of the first control and the control content of the second control, items such as a target control amount _PC1 , a target control amount _PC2 , and a control target are provided. Since the assumed accident case number, the supply-demand imbalance amount ΔP, and each item to be controlled are the same as those in FIGS. 4 and 5, the description thereof will be omitted. The control content of the first control indicates a load 2 that limits the load with respect to the target control amount _PC1 targeted by the first control. The control content of the second control indicates a load 2 that limits the load with respect to the target control amount _PC2 targeted by the second control.

In the example of FIG. 12, shown as a grid fault of postulated accident case number 1, if a route blocking accident X transmission line occurs in the A power plant, the first control target control quantity P _C1 is at P _C1-1 , L1, L2, and L3 as the load 2 to be controlled are set to load limit. The target control quantity _{P C2} of the second control is a _{P C2-1,} and the L4 and L5 as a load 2 to be controlled by a set of load limits.

When the post-calculation unit 10B receives the start signal from the accident detection terminal device 11, the post-calculation unit 10B refers to the control content stored by the pre-calculation unit 10A based on the received start signal. The post-calculation unit 10B first executes the control content of the first control corresponding to the system accident that has occurred from the stored control content. Specifically, the post-calculation unit 10B attaches the load 2 to the control terminal device 12 that controls the load 2 (L1, L2, and L3 in the example of FIG. 12) selected as the control content of the first control. Sends a control signal instructing load limitation.

Further, the post-calculation unit 10B receives, for example, a preset fixed time or a time until the frequency recovers within the specified range after receiving the start signal, and the interconnection power flow _PT received from the DC monitoring terminal device 13. To monitor. The post-calculation unit 10B determines that the emergency tidal current control is not operating correctly when the interconnection tidal current _PT does not change in the increasing direction. When the post-calculation unit 10B determines that the emergency power flow control is not operating correctly, 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.

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

P _T (t) < _PT (t−ΔT)… (7) Equation Here,
_PT (t): Interconnected tidal current at time t: Current time ΔT: Time interval

The DC interconnection information used for determining the operation of emergency tidal current control is not limited to the interconnection tidal current _PT . The operation determination of the emergency power flow control is a determination of whether or not the emergency power flow control is operating correctly. That is, in the above, the case where the determination as to whether or not the emergency tidal current control is operating correctly is determined according to whether or not the interconnection tidal current _PT has changed in the increasing direction has been described as an example. There is no limitation.

For example, the post-calculation unit 10B may determine the operation of the emergency power flow control based on the state of the DC interconnection facility 9 (for example, normal / abnormal binary information). In this case, the DC monitoring terminal device 13 takes in the state of the DC interconnection facility 9 and transmits it to the central processing unit 10. Then, the post-calculation unit 10B determines that the emergency power flow control is not operating correctly when an abnormality is shown in the information indicating the state of the DC interconnection facility 9 acquired from the DC monitoring terminal device 13. 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 the 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 facility 9. In this case, the DC monitoring terminal device 13 transmits the voltage input from the voltage measuring instrument 7 provided on the bus 3 and the transmission line 4 connected to the DC interconnection facility 9 to the central processing unit 10. Then, in the post-calculation unit 10B, when the voltage values of the bus 3 and the transmission line 4 connected to the DC interconnection facility 9 are lower than the preset values at the time of the assumed accident, the emergency power flow control operates correctly. It is determined that the control is not present, 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 the emergency power flow control based on the frequency state. In this case, the DC monitoring terminal device 13, 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, when the post-calculation unit 10B determines that the frequency after the first control is executed has not changed to the recovery tendency, it determines that the emergency power flow control is not operating correctly, and causes the second control to be executed. The 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 is provided with the first control and the second control. The first control is a control that is performed with priority given to emergency power flow control by the DC interconnection facility 9. The second control is a control performed when the emergency power flow control does not operate correctly. The central processing unit 10 calculates and obtains the control contents of each of the first control and the second control. When the central processing unit 10 receives the start signal from the accident detection terminal device, it first transmits the control signal of 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 accident, and when it is determined that the emergency power flow control is not operating correctly, the control signal of the second control is output. It is additionally transmitted to the control terminal device.

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

(Third Embodiment)
Next, a third embodiment will be described. In the present embodiment, two control signals to which information for distinguishing 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, and control. It differs from the above-described embodiment in that the terminal device 12 determines whether or not to implement the second control.

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

The configuration of the control terminal device 12 of the present embodiment will be described with reference to FIG. FIG. 13 is a block diagram showing the configuration of the control terminal device 12 of the present embodiment. The control terminal device 12 of the present embodiment includes a functional unit (holding the control signal) for holding the control signal, a fail-safe relay 95F1 and a fail-safe relay 95F2.

The function unit (holding the control signal) that holds the control signal holds the control signals of the first control and the second control received from the central processing unit 10 by the control terminal device 12 separately from each other. The functional unit for holding the control signal (holding the control signal) controls the first control and the second control based on the signals given to the respective control signals to distinguish the first control and the second control from each other. Keep distinct.

The fail-safe relay 95F1 is a frequency relay that prevents malfunction of the first control. The fail-safe relay 95F1 operates at a predetermined set value f _95F1 . That is, the fail-safe relay 95F1 is a signal indicating that when the frequency measured based on the voltage acquired from the voltage measuring instrument 7 is less than a predetermined set value f _95F1 (or set value f _95F1 or less). (95F1 operation) is output. By this fail-safe relay operation, the control terminal device 12 shuts off when the control signal of the first control is received and the frequency becomes less than a predetermined set value f _95F1 (or set value f _95F1 or less). A cutoff command is output to the device 5. The circuit breaker 5 to which the circuit breaker command is output here is a circuit breaker 5 that controls the load 2 subject to the load limitation in the first control (supplying or shutting off the power to the load 2).

The fail-safe relay 95F2 is a frequency relay that prevents malfunction of the second control. The fail-safe relay 95F2 operates at a predetermined set value f _95F2 . That is, the fail-safe relay 95F2 is a signal indicating that when the frequency measured based on the voltage acquired from the voltage measuring instrument 7 is less than the predetermined set value f _95F2 (or set value f _95F2 or less). (95F2 operation) is output. By this fail-safe relay operation, the control terminal device 12 shuts off when the control signal of the second control is received and the frequency becomes less than a predetermined set value f _95F2 (or set value f _95F2 or less). A cutoff command is output to the device 5. The circuit breaker 5 to which the circuit breaker command is output here is a circuit breaker 5 that controls the load 2 subject to the load limitation in the second control (supplying or shutting off the power to the load 2).

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

Pre calculation unit 10A of the central processing unit 10 uses the interconnection power flow P _T received from the power supply information network, the adjustment expectation [Delta] P _T, determined by equation (2). Also, pre-calculating section 10A, the supply-demand imbalance amount [Delta] P caused when the assumed fault occurs, by subtracting the adjustment expectation [Delta] P _T, the corresponding supply and demand unbalance amount [Delta] P _SSC, determined in (3) below. Then, when the corresponding supply-demand imbalance amount ΔP _SSC is positive, the pre-calculation unit 10A obtains the control amount for eliminating the corresponding supply-demand imbalance amount ΔP _SSC by the equation (5), and obtains the control amount to eliminate the corresponding supply-demand imbalance amount ΔP _SSC by the equation (5), and obtains the target control amount _PC1 of the first control. And. Further, the pre-calculation unit 10A obtains the control amount expected for the emergency power flow control of the DC interconnection facility 9 by the equation (6), and sets it as the target control amount _PC2 of the second control.

Precomputed section 10A, for the first control and the second control, respectively, to select the combination of the load 2 so that the load amount of the load limit is close as possible to the target control quantity P _C1, P _C2. The pre-calculation unit 10A first selects the control content of the first control, and then selects the control content of the second control from the load 2 not selected in the first control. The pre-calculation unit 10A saves the selected contents of the first control and the second control as control contents. The control content is, for example, the content shown in FIG.

When the post-calculation unit 10B receives the start signal from the accident detection terminal device 11, the post-calculation unit 10B refers to the control content stored by the pre-calculation unit 10A based on the received start signal. From the stored control contents, the post-calculation unit 10B adds a signal capable of distinguishing each other's control signals to two control signals indicating the control contents of the first control and the second control corresponding to the accident that has occurred. , Is transmitted to the control terminal device 12.

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

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

Here, the set point _{f 95F1,} will be described with reference to FIG. 15 the relationship between the setting value _{f 95F2.} FIG. 15 is a diagram illustrating the relationship between the settling value f _95F1 and the settling value f _95F2 in the third embodiment. Since the horizontal axis, vertical axis, standard frequency f _0, frequency f _UFR , and specified range of FIG. 15 are the same as those of FIG. 7, the description thereof will be omitted.

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

As described above, in the power system stabilization system of the third embodiment, the central processing unit 10 is provided with the first control and the second control. The first control is a control that is performed with priority given to emergency power flow control by the DC interconnection facility 9. The second control is a control performed when the emergency power flow control does not operate correctly. The central processing unit 10 calculates and obtains the control contents of each of the first control and the second control. When the central processing unit 10 receives the start signal from the accident detection terminal device, the central processing unit 10 transmits the control signals of the first control and the second control to the control terminal device 12 with signals that can be distinguished from each other. The control terminal device 12 includes a fail-safe relay corresponding to each of the first control and the second control.

As a result, the power system stabilization system of the third embodiment has the effect of the first embodiment described above, and when the emergency power flow control by the DC interconnection facility 9 does not operate correctly, the power system stabilization system Can be handled with. Therefore, even when the emergency power flow control is poor (does not operate correctly), the influence of the accident can be suppressed and a wide-area power outage can be prevented.

According to at least one embodiment described above, priority is given to 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). The quantity ΔP _SSC ) is dealt with by the power system stabilization system. As a result, the emergency power flow control by the DC interconnection facility 9 can be utilized, and it is possible to prevent excessive control such as load limitation by the power system stabilization system.

Although some embodiments of the present invention have been described, these embodiments are presented as examples 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 changes can be made without departing from the gist of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention as well as the invention described in the claims and the equivalent scope thereof.

1 ... Generator, 2 ... Load, 3 ... Bus, 4 ... Transmission line or transformer, 5 ... Breaker, 6 ... Current measuring instrument, 7 ... Voltage measuring instrument, 8 ... Communication equipment, 9 ... DC interconnection equipment, 10 ... Central computing device, 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 accident using system information and sends a start signal to the central processing unit,
The control content is calculated and stored in advance, and when the activation signal is received from the accident detection terminal device, the control content is referred to the stored control content, and a control signal indicating the control content to the control terminal device is displayed. With the central processing unit that sends
A control terminal device that receives the control signal from the central processing unit and controls under AND conditions of fail-safe relay operation in the own device.
It is a power system stabilization system equipped with
Priority is given to emergency power flow control by DC interconnection equipment, and control of supply and demand imbalance that cannot be handled by emergency power flow control by DC interconnection equipment is performed.
A power system stabilization system characterized by this. The central processing unit is provided with a first control that is executed by giving priority to the emergency power flow control by the DC interconnection facility and a second control that is executed when the emergency power flow control does not operate correctly. When the control contents of each of the first control and the second control are calculated and an activation signal indicating the occurrence of an accident is received from the accident detection terminal device, the control signal of the first control is first transmitted to the control terminal device. When the operation state of the emergency power flow control is monitored by transmitting and using the DC interconnection information before and after the occurrence of the accident and it is determined that the emergency power flow control is not operating correctly, the second control is performed. The control signal is additionally transmitted to the control terminal device.
The power system stabilization system according to claim 1, wherein the power system is stabilized. The central processing unit is provided with a first control that is executed by giving priority to the emergency power flow control by the DC interconnection facility and a second control that is executed when the emergency power flow control does not operate correctly. When the control contents of the first control and the second control are calculated and an activation signal indicating the occurrence of an accident is received from the accident detection terminal device, the control signals of the first control and the second control are transmitted. A signal that can be distinguished from each other is added and transmitted 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, wherein the power system is stabilized.

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