System stabilization device

Abstract

To provide a grid stabilization device with which it is possible to maintain the finish frequency of a power grid after disengagement of a power generator within a target frequency range, taking into account the frequency response of an equivalent load.SOLUTION: The grid stabilization device comprises: a coefficient calculation unit that calculates an equivalent load frequency response coefficient concerning an equivalent load; and a control variable setting unit that sets an equivalent load control variable so that the finish frequency of grid frequency of a power grid after a first power generator is disconnected is included within a target frequency range. The coefficient calculation unit calculates the equivalent load frequency response coefficient on the basis of the total value of loads, the total output value of a plurality of renewable energy power sources, and a load frequency response coefficient. The control variable setting unit sets the equivalent load control variable on the basis of the total value of equivalent loads, a frequency deviation between the reference frequency and the grid frequency of the power grid, the power generator frequency response coefficient of a plurality of power generators, an equivalent load frequency response coefficient, and the power supply disengagement amount of the first power generator.SELECTED DRAWING: Figure 6

Description

[Technical Field]

[0001] The present disclosure relates to a power grid stabilization device. [Background technology]

[0002] In a power system stabilization system aimed at maintaining frequency, events that cause frequency fluctuations (e.g., power source failure, route cut-off accident on a heavy current line, etc.) are detected, and generators and loads are shut off to maintain frequency (e.g., Non-Patent Document 1). [Prior art documents] [Non-patent literature]

[0003] [Non-Patent Document 1] Atsushi Kino, Kenichiro Yamazato, Fuminao Kinjo, Wataru Shima, Yasuyuki Owada, Hiroshi Nishino, Toru Maeda, Shuji Oshida, Development and Application of a Centralized System Stabilization System (SSC) for Small-Scale and Isolated Power Systems, 2011 Electrical Engineering Society Conference, 19-1, 2011 Summary of the Invention [Problem to be solved by the invention]

[0004] In recent years, the introduction of renewable energy power sources (such as solar power generation and wind power generation) has increased rapidly, and the system control functions of inverter equipment, including renewable energy power sources, are becoming more sophisticated, which can become an uncertain factor in the control of system stabilization systems. Therefore, in order to keep the power system's final frequency within the target frequency range after a generator trips (i.e., a power source trips) or after a load trips, it is necessary to properly consider the frequency characteristics of the renewable energy power source as well as the frequency characteristics of the load that consumes power.

[0005] An object of one aspect of the present disclosure is to provide a grid stabilization device that can maintain the final frequency of the power grid after a generator trip within a target frequency range, taking into account the frequency characteristics of the load and an equivalent load including a renewable energy power source.An object of another aspect of the present disclosure is to provide a grid stabilization device that can maintain the final frequency of the power grid after a load trip within a target frequency range, taking into account the frequency characteristics. [Means for solving the problem]

[0006] According to one embodiment, there is provided a power system stabilization device for a power system connected to multiple generators, multiple loads, and multiple renewable energy power sources. The power system stabilization device includes a coefficient calculation unit that calculates an equivalent load frequency characteristic coefficient for an equivalent load that is a combination of the multiple loads and multiple renewable energy power sources, and a control variable setting unit that, when a first generator of the multiple generators is disconnected from the power system, sets an equivalent load control variable so that the final system frequency of the power system after the first generator is disconnected falls within a target frequency range. The coefficient calculation unit calculates the equivalent load frequency characteristic coefficient based on the total load values ​​of the multiple loads and the total output value of the multiple renewable energy power sources at an initial point in time before the first generator is disconnected from the power system, and the load frequency characteristic coefficients for the multiple loads. The control quantity setting unit calculates an equivalent load total value for the equivalent load at the initial point in time based on the load total value and output total value at the initial point in time, and sets an equivalent load control quantity based on the equivalent load total value, the frequency deviation between the reference frequency and the system frequency of the power system, generator frequency characteristic coefficients of the multiple generators, equivalent load frequency characteristic coefficients, and the amount of power loss of the first generator.

[0007] According to another embodiment, there is provided a system stabilization device for a power system connected to a plurality of generators, a plurality of loads, and a plurality of renewable energy power sources. The system stabilization device includes a coefficient calculation unit that calculates an equivalent load frequency characteristic coefficient for an equivalent load that is a combination of the plurality of loads and a plurality of renewable energy power sources, and a control variable setting unit that, when some of the equivalent loads are disconnected from the power system, sets a generator control variable so that the final system frequency of the power system after some of the equivalent loads are disconnected falls within a target frequency range. The coefficient calculation unit calculates the equivalent load frequency characteristic coefficient based on the total load values ​​of the plurality of loads and the total output value of the plurality of renewable energy power sources at an initial point in time before some of the equivalent loads are disconnected from the power system. The control quantity setting unit calculates an equivalent load total value for the equivalent load at the initial point in time based on the load total value and output total value at the initial point in time, and sets the generator control quantity based on the equivalent load total value, the frequency deviation between the reference frequency of the power system and the system frequency, generator frequency characteristic coefficients of the multiple generators, equivalent load frequency characteristic coefficients, and equivalent load dropout amounts of a portion of the equivalent load. [Effects of the Invention]

[0008] According to the present disclosure, the final frequency of the power system after a generator trip and a load drop can be maintained within a target frequency range by taking into account the frequency characteristics of the load and the equivalent load including the renewable energy power source. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a diagram showing the overall configuration of a power grid stabilization system. [Figure 2] FIG. 10 is a diagram for explaining an equivalent load model. [Figure 3] FIG. 2 is a block diagram showing an example of a hardware configuration of an accident detection terminal device. [Figure 4] FIG. 10 is a diagram for explaining the frequency characteristics of the total output value of renewable energy power sources. [Figure 5]FIG. 2 is an image diagram for explaining the effect of the first embodiment. [Figure 6] FIG. 2 is a block diagram showing an example of the functional configuration of a power system stabilizing device. [Figure 7] FIG. 10 is an image diagram for explaining the effect of the second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In the following description, the same components are denoted by the same reference numerals. The names and functions of the components are also the same. Therefore, detailed description thereof will not be repeated.

[0011] Embodiment 1 <Overall structure> Fig. 1 is a diagram showing the overall configuration of a power system stabilization system 1000. Referring to Fig. 1, the power system stabilization system 1000 according to the first embodiment includes a fault detection terminal device 10, a power system stabilization device 15, and load control terminal devices 21-2n (hereinafter also referred to as "load control terminal device 20"). When the plant is operating normally, the plant control devices GA1C-GAnC control the input amounts of the generators GA1-GAn in a direction to increase the output of the generators GA1-GAn if the frequency of the power system 120 (hereinafter also referred to as "power system frequency") drops, and to decrease the output of the generators GA1-GAn if the power system frequency rises.

[0012] A plurality of generators GA1 to GAn provided in the power plant 100 are connected to the power system 120 via a bus BA and a power transmission line 80. Electric power from the plurality of generators GA1 to GAn is supplied to the power system 120.

[0013] A plurality of generators GA1 to GAn (hereinafter also collectively referred to as "generators GA") are installed in the power plant 100, and the output of each generator is controlled by a corresponding plant control device. Specifically, the output of the generator GA1 is controlled by a plant control device GA1C, and the output of the generator GAn is controlled by a plant control device GAnC.

[0014] Each of the generators GA1 to GAn is connected to the bus BA via a corresponding transformer and a corresponding circuit breaker. Specifically, the generator GA1 is connected to the bus BA via a transformer MTr1 and a circuit breaker CB1. The generator GAn is connected to the bus BA via a transformer MTrn and a circuit breaker CBn.

[0015] A plurality of loads L1, L2, ... Ln (hereinafter also collectively referred to as "loads L") are connected to the power system 120. Each load L is disconnected from the power system 120 under the control of a corresponding load control terminal device. Specifically, load L1 is disconnected from the power system 120 under the control of load control terminal device 21, load L2 under the control of load control terminal device 22, and load Ln under the control of load control terminal device 2n. Note that each load L may be connected to the power system 120 under the control of a corresponding load control terminal device.

[0016] The power system stabilization device 15 is configured to be able to communicate with each load control terminal device 20, and receives the load amount of the corresponding load L as measurement information from each load control terminal device 20. The power system stabilization device 15 transmits a command signal to the load control terminal device 20 to disconnect the load from the power system 120.

[0017] Furthermore, a plurality of renewable energy power sources ER1, ER2, ..., ERn (hereinafter also collectively referred to as "renewable energy power sources ER") are connected to the power system 120. In this embodiment, each renewable energy power source ER is disconnected from the power system 120 under the control of a corresponding load control terminal device. Specifically, a renewable energy power source ERn is disconnected from the power system 120 under the control of a load control terminal device 2n. Furthermore, the power system stabilization device 15 receives the output amount (e.g., active power value) of the corresponding renewable energy power source ER from each load control terminal device 20 as measurement information. Note that each renewable energy power source ER may be connected to the power system 120 under the control of the corresponding load control terminal device. Furthermore, the load control terminal device 20 may be configured to be able to individually control the connection and disconnection between the load L and each of the renewable energy power sources ER and the power system 120.

[0018] Each renewable energy power source ER may be disconnected from or connected to the power grid 120 under the control of a corresponding power control terminal device (not shown). In this case, the power grid stabilization device 15 is configured to be able to communicate with each power control terminal device.

[0019] In this embodiment, an equivalent load model is considered, which combines a load L and a renewable energy power source ER.

[0020] 2 is a diagram for explaining an equivalent load model. Referring to FIG. 2, the equivalent load amount P of the equivalent load LE, which is a combination of each load L and each renewable energy power source ER, is LE is the total load value P of each load L L The total output value P of renewable energy sources ER ER (i.e., P LE =P L -P ER In this embodiment, the equivalent load P LE is assumed to be positive. In other words, the total load value P L The total output value P ER shall be greater than

[0021] Referring again to Fig. 1, a current transformer for measuring current is provided at the sending end of each transformer corresponding to generators GA1 to GAn. Specifically, a current transformer CT1 for measuring the sending end output current of generator GA1 is provided at the sending end of transformer MTr1 corresponding to generator GA1. A current transformer CTn for measuring the sending end output current of generator GAn is provided at the sending end of transformer MTrn corresponding to generator GAn. In addition, a voltage transformer PT for measuring the bus voltage is provided at bus BA.

[0022] A power plant 100 is provided with a fault detection terminal device 10. The outputs of the current transformers CT1 to CTn and the output of the voltage transformer PT are individually input to the fault detection terminal device 10. The fault detection terminal device 10 also individually receives signals indicating the open / closed states of the circuit breakers CB1 to CBn (hereinafter also referred to as "open / close signals").

[0023] Each plant control device detects a plant fault (for example, a fault in a boiler, turbine, or a number of valves in the plant control device, or a fault in a generator). When each plant control device detects a plant fault, it outputs a tripping command (i.e., an opening command) to the corresponding circuit breaker.

[0024] Alternatively, a transmission line protection relay (not shown) installed on the transmission line 80 outputs a shutoff command to each circuit breaker when it detects an accident on the transmission line 80 based on the current value detected by the current detector (for example, when the current value is equal to or greater than a specified value).

[0025] When a circuit breaker is opened due to a power transmission line accident, a plant failure, or the like, the corresponding generator is disconnected from the power system 120. In the following description, disconnecting a generator from the power system 120 is also referred to as "the generator dropping out." For example, when the circuit breaker CB1 is opened, the generator GA1 is disconnected from the power system 120 (i.e., the generator GA1 drops out).

[0026] Signals indicating the open / closed states of the circuit breakers CB1 to CBn are transmitted at predetermined intervals from the fault detection terminal device 10 to the power system stabilization device 15. As a result, the power system stabilization device 15 determines whether the generators GA1 to GAn have tripped or not based on the open / close signals of the circuit breakers CB1 to CBn. Specifically, the power system stabilization device 15 determines that the generator GA1 has tripped when the circuit breaker CB1 is open, and determines that the generator GA1 has not tripped when the circuit breaker CB1 is closed.

[0027] The fault detection terminal device 10 calculates the active power value output from each of the generators GA1 to GAn based on the current values ​​from the instrument current transformers CT1 to CTn and the voltage value from the instrument transformer PT. The calculated active power values ​​are transmitted to the system stabilization device 15 at predetermined intervals. This allows the system stabilization device 15 to constantly monitor the active power value output from each generator. The fault detection terminal device 10 may also transmit electrical quantity (e.g., current, voltage) information input from the instrument current transformers CT1 to CTn and the instrument transformer PT to the system stabilization device 15 as measurement information.

[0028] The system stabilization device 15 receives the output active power value of each generator GA1 to GAn as measurement information from the fault detection terminal device 10, and also receives tripping information indicating whether each generator GA has tripped. Note that the mechanical input value to each generator GA1 to GAn corresponds to the output active power value when each generator GA has not tripped and the system is not fluctuating. Typically, the tripping information is an open / close signal of each circuit breaker CB.

[0029] When a generator trips from the power grid 120, the frequency of the power grid 120 (hereinafter also referred to as "system frequency") drops. The power grid stabilization device 15 sets a control amount of the equivalent load LE (e.g., equivalent to the load reduction amount of the equivalent load) so that the completed frequency of the power grid 120 after the generator trips falls within a target frequency range. Specifically, the power grid stabilization device 15 sets the equivalent load control amount so that the completed frequency of the power grid 120 after the generator trips falls within the target frequency range using various characteristic information of each generator GA, system information, power output from the generator, various characteristic information of each load L, various characteristic information of each renewable energy power source ER, etc.

[0030] The power system stabilization device 15 selects a load corresponding to an equivalent load control amount from among the loads L1 to Ln based on a preset priority order, and outputs a command signal to shedding the selected load to the corresponding load control terminal device 21 to 2n. Note that this is an example of a method for setting a load control target in the power system stabilization device 15, and the load may be selected by other methods.

[0031] Alternatively, the power system stabilization device 15 may select a renewable energy power source corresponding to an equivalent load control amount from among the plurality of renewable energy power sources ER1 to ERn based on a preset priority order, and output a command signal to the renewable energy power source to cause the renewable energy power source to perform a discharge operation (for example, an operation to control power in the discharge direction). Note that the configuration may also be such that a load and renewable energy power source corresponding to the equivalent load control amount are selected, and the load is cut off and the renewable energy power source is caused to perform a discharge operation.

[0032] As a result, the final frequency of the power grid 120 after the tripping of the generator is maintained within the target frequency range. In other words, the grid is stabilized.

[0033] <Hardware configuration> (Accident detection terminal device) Fig. 3 is a block diagram showing an example of a hardware configuration of the accident detection terminal device 10. Referring to Fig. 3, the accident detection terminal device 10 includes an auxiliary transformer 32, an A / D conversion unit 35, an arithmetic processing unit 40, a communication circuit 50, a digital output circuit (D / O: Digital Output) 55, and a digital input circuit (D / I: Digital Input) 56.

[0034] The auxiliary transformer 32 receives electrical quantities from the current transformer and voltage transformer, converts them into voltages suitable for signal processing in the relay's internal circuitry, and outputs them. The A / D conversion unit 35 receives the voltages output from the auxiliary transformer 32 and converts them into digital data. Specifically, the A / D conversion unit 35 includes an analog filter, a sample-and-hold circuit, a multiplexer, and an A / D converter.

[0035] The analog filter removes high-frequency noise components from the current waveform signal output from auxiliary transformer 32. The sample-and-hold circuit samples the current waveform signal output from the analog filter at a sampling period. Based on a timing signal input from arithmetic processing unit 40, the multiplexer sequentially switches the waveform signals input from the sample-and-hold circuit in time series and inputs them to the A / D converter. The A / D converter converts the waveform signals input from the multiplexer from analog data to digital data. The A / D converter outputs the digitally converted waveform signals to arithmetic processing unit 40.

[0036] The arithmetic processing unit 40 includes a CPU (Central Processing Unit) 41, a RAM (Random Access Memory) 42, and a ROM (Read Only Memory) 43. These elements are connected to each other via a bus 44. The arithmetic processing unit 40 may include an electrically rewritable non-volatile memory such as a flash memory or hardware.

[0037] The communication circuit 50 communicates with an external device (for example, the power system stabilization device 15). The communication circuit 50 communicates with the external device in accordance with a specified protocol.

[0038] The digital output circuit 55 is an interface circuit for outputting a signal to an external device. For example, the digital output circuit 55 may output a breaker command to a circuit breaker in accordance with a command from the CPU 41. The digital input circuit 56 receives, for example, an open / close signal indicating the open / close state of the circuit breaker from the circuit breaker.

[0039] (System stabilization device, load control terminal device) The hardware configuration of the power system stabilizing device 15 and the load control terminal device 20 may be the same as that of the fault detection terminal device 10. Alternatively, the power system stabilizing device 15 and the load control terminal device 20 may be configured to have hardware equivalent to the arithmetic processing unit 40 and the communication circuit 50 in FIG.

[0040] <Equivalent load control amount setting process> The grid stabilization system 1000 shown in Fig. 1 is normally operated so that the power demand (i.e., equivalent load) and the power supply (i.e., power generation amount) are equal. The equivalent load has a frequency characteristic that decreases with a frequency drop. On the other hand, the power generation amount is controlled so that it increases with a frequency drop.

[0041] Therefore, the equivalent load of the equivalent load LE, which is a combination of multiple loads L and multiple renewable energy sources ER, is calculated as P LE [pu], the total mechanical input to each generator GA (i.e., the total mechanical input) is P M [pu], the following equations (1) and (2) hold.

[0042]

number

[0043] where P LE0 [pu] is the equivalent load P LE is the initial value of K LE[pu / Hz] is the frequency characteristic coefficient of the equivalent load LE. Also, ΔF [Hz] is the frequency deviation between the reference frequency Fn [Hz] of the power system 120 and the system frequency F [Hz] of the power system 120 (i.e., ΔF = F - Fn). Also, P M0 [pu] is the total mechanical input value P M is the initial value of K G [pu / Hz] is the equivalent frequency characteristic coefficient when multiple generators GA are considered as one generator. For example, the frequency characteristic coefficient K G is the average value of the frequency characteristic coefficients of multiple generators GA.

[0044] Reference frequency Fn and frequency response coefficient K G is stored in advance in a memory (for example, a ROM, a RAM, hardware, etc.) of the power system stabilization device 15. The power system frequency F is obtained, for example, from the voltage of the bus BA detected by the potential transformer PT. The initial value of the equivalent load amount P LE0 is calculated based on the load amount of each load L and the output amount of each renewable energy power source ER as measurement information in the initial state (for example, when ΔF is 0). M0 corresponds to the output active power value of each generator GA as measurement information in the initial state.

[0045] Considering the supply and demand balance, the equivalent load P LE and the total power generation amount P M Since these are consistent, the following equation (3) holds.

[0046]

number

[0047] Furthermore, let us assume that a certain generator (for example, generator GAx) among the multiple generators GA1 to GAn has tripped. GDR When a generator trips, the equivalent load control amount required to make the finished frequency Fce of the power grid 120 fall within the target frequency range (for example, Fs≦Fce≦Fn) is P LECSThe equivalent load after the generator trips is P LE and total mechanical input value P M are expressed as equations (4) and (5), respectively.

[0048]

number

[0049] Therefore, “P LE0 =P M0 " and the simultaneous equations (3) to (5), the equivalent load control amount P required to make the frequency deviation between the finished frequency Fce and the target frequency Fs ΔF when a generator trip occurs is LECS is expressed as the following equation (6).

[0050]

number

[0051] Next, the above equivalent load frequency characteristic coefficient K LE The calculation method will be explained below. First, the equivalent load P LE The time change of [pu] is P LE (t), the total load of each load L (i.e., the total load P L [pu]) is expressed as P L (t), total load value P L The initial value of P L0 [pu], load frequency characteristic coefficient is K L [pu / Hz], the total output of each renewable energy source ER (i.e., the total output P ER [pu]) is expressed as P ER (t), and the time change of the frequency deviation ΔF is ΔF(t), then equation (7) holds. L is an equivalent frequency characteristic coefficient when a plurality of loads L are regarded as one load, and is stored in advance in the memory of the power system stabilization device 15.

[0052]

number

[0053] First, the total output value P ER In this case, the total output value P ER (t) is the total output value P ER The initial value of P ER0 That is, P ER (t)=P ER0 As explained in Figure 2, the equivalent load P LE is the total load value P L to the total output value P ER Since this corresponds to the subtraction of

[0054]

number

[0055] Therefore, “P ER (t)=P ER0 " and equation (8) are used in equation (7), the equivalent load frequency characteristic coefficient K LE is expressed as the following equation (9).

[0056]

number

[0057] Next, the total output value P ER For example, the total output value P ER has the characteristics shown in FIG.

[0058] 4 is a diagram for explaining the frequency characteristics of the total output value of renewable energy power sources. Referring to FIG. 4, the horizontal axis represents the frequency deviation ΔF, and the vertical axis represents the total output value P ER and its initial value P ER0 Deviation ΔP ER This shows:

[0059] If the frequency deviation ΔF is within the reference range (for example, -ΔF1≦ΔF≦ΔF1), the deviation ΔP ER is 0, so the total output value P ER It is understood that the total output value P ER corresponds to the dead zone where the

[0060] Therefore, when the frequency deviation ΔF is within the reference range, the total output value P ER does not change (i.e., P ER =P ER0 holds), the equivalent load frequency characteristic coefficient K LE is expressed by the above equation (9).

[0061] On the other hand, if the frequency deviation ΔF is larger than “ΔF1”, P ER (t) is expressed by the following equation (10), and when the frequency deviation ΔF is smaller than "-ΔF1", P ER (t) is expressed by the following equation (11): K ER is an equivalent frequency characteristic coefficient when a plurality of renewable energy power sources ER are regarded as one renewable energy power source, and is stored in advance in the memory of the power system stabilization device 15.

[0062]

number

[0063] Therefore, by using equations (8) and (10) in equation (7), the equivalent load frequency characteristic coefficient K when the frequency deviation ΔF is larger than "ΔF1" is LE is expressed as the following equation (12).

[0064]

number

[0065] Similarly, by using equations (8) and (11) in equation (7), the equivalent load frequency characteristic coefficient K when the frequency deviation ΔF is smaller than "-ΔF1" is obtained. LEis expressed as the following equation (13).

[0066]

number

[0067] Equivalent load frequency characteristic coefficient K calculated by equations (9), (12), and (13) LE By using this in equation (6), the appropriate equivalent load control amount P LECS Therefore, the final frequency Fce of the power grid 120 after the tripping of the generator can be more appropriately kept within the target frequency range.

[0068] FIG. 5 is an image diagram for explaining the effect of the first embodiment. Referring to FIG. 5, graph 501 shows the change in frequency over time when the equivalent load amount is not controlled after the tripping of the generator. Graphs 502 and 504 show the change in frequency over time when the equivalent load frequency characteristic coefficient K LE (for example, without performing calculations such as equations (9), (12), and (13), the equivalent load frequency characteristic coefficient K LE (where K is a fixed value), the graph 503 shows the time change of the frequency of the power system 120 when the equivalent load control amount is set using equation (6). LE This figure shows the time change of frequency when the equivalent load control amount is set using equation (6) taking into consideration (for example, by performing calculations such as equations (9), (12), and (13)).

[0069] Referring to graph 501, it can be seen that if the required equivalent load amount is not controlled after the generator trips at time t0, the finished frequency will not be within the target frequency range (i.e., the frequency range above Fs1 and below Fn).

[0070] Referring to graph 502, when the equivalent load amount is controlled at time t1 after the tripping of the generator, the finished frequency is closer to the target frequency Fs1 than the finished frequency of graph 501, but is not included within the target frequency range. This is because the equivalent load frequency characteristic coefficient K LE This is thought to be because the value of was inappropriate and the set equivalent load control amount was insufficient.

[0071] Referring to graph 504, when the equivalent load is controlled at time t1 after the tripping of the generator, the finished frequency is included in the target frequency range, but the difference with the target frequency Fs1 is large. This is because the equivalent load frequency characteristic coefficient K LE This is thought to be because the value of was inappropriate and the equivalent load control amount set was excessive.

[0072] On the other hand, referring to graph 503, when the equivalent load is controlled at time t1 after the generator trips, the finished frequency is included in the target frequency range and is close to the target frequency Fs1. This is because the equivalent load frequency characteristic coefficient K LE This is thought to be because the value of is appropriate, and as a result, an appropriate equivalent load control amount is set.

[0073] <Functional configuration> Fig. 6 is a block diagram showing an example of the functional configuration of the power grid stabilizing device. Referring to Fig. 6, the power grid stabilizing device 15 includes an information receiving unit 201, a coefficient calculating unit 203, a control amount setting unit 205, and a command transmitting unit 207. Typically, these functions are realized by the CPU of the power grid stabilizing device 15 executing a program, but may also be realized by a dedicated hardware circuit.

[0074] The information receiving unit 201 receives various types of information from the fault detection terminal device 10 and the load control terminal device 20. For example, the information receiving unit 201 receives the output active power value and dropout information of each of the generators GA1 to GAn from the fault detection terminal device 10. In addition, the information receiving unit 201 receives the load amount of the corresponding load L and the output amount of the renewable energy power source ER from each load control terminal device 20 as measurement information.

[0075] The coefficient calculation unit 203 receives input of measurement information and setting information, and calculates an equivalent load frequency characteristic coefficient K LE The setting information is the reference frequency Fn, the frequency characteristic coefficient K G ,K L ,K ER Specifically, the coefficient calculation unit 203 calculates the total load amount P of the plurality of loads L at an initial point before the first generator (for example, the generator GAx) is disconnected from the power grid 120. L0 and the total output value P of multiple renewable energy sources ER ER0 and the load frequency characteristic coefficient K for multiple loads L L Based on the equivalent load frequency characteristic coefficient K LE Calculate the following.

[0076] In a certain situation, the total output value P ER does not have a frequency characteristic, the coefficient calculation unit 203 calculates the equivalent load frequency characteristic coefficient K LE Or, the output total value P ER has a frequency characteristic and the frequency deviation ΔF is within a reference range (for example, −ΔF1≦ΔF≦ΔF1), the coefficient calculation unit 203 calculates the equivalent load frequency characteristic coefficient K LE Calculate the following.

[0077] In another aspect, the coefficient calculation unit 203 calculates the total load value P L0 and the total output value P ER0 and the load frequency characteristic coefficient K L and the frequency characteristic coefficient K for multiple renewable energy sources ER ERBased on the frequency deviation ΔF and the reference range, the equivalent load frequency characteristic coefficient K LE Specifically, when the frequency deviation ΔF is larger than the upper limit value “ΔF1” of the reference range, the coefficient calculation unit 203 calculates the equivalent load frequency characteristic coefficient K LE When the frequency deviation ΔF is smaller than the lower limit value "-ΔF1" of the reference range, the coefficient calculation unit 203 calculates the equivalent load frequency characteristic coefficient K LE Calculate the following.

[0078] The control amount setting unit 205 receives the measurement information, the dropout information, the setting information, and the equivalent load frequency characteristic coefficient K calculated by the coefficient calculation unit 203. LE Specifically, when a first generator (for example, a generator GAx) among the multiple generators GA is disconnected from the power grid 120, the control amount setting unit 205 sets the equivalent load control amount P so that the finished frequency Fce of the power grid 120 after the first generator is disconnected falls within the target frequency range. LECS Set.

[0079] The control amount setting unit 205 sets the total load value P L0 and the total output value P ER0 Based on this, the total equivalent load value P for the equivalent load LE at the initial point LE0 Specifically, the control amount setting unit 205 calculates the equivalent load total value P LE0 Calculate.

[0080] The control amount setting unit 205 also sets the equivalent load total value P LE0 , the frequency deviation ΔF between the reference frequency Fn of the power system 120 and the system frequency F, and the generator frequency characteristic coefficient K G and the equivalent load frequency characteristic coefficient K LE and the power loss amount of the first generator P GDR Based on this, the equivalent load control amount P LECS Specifically, the control amount setting unit 205 uses the formula (6) to set the equivalent load control amount P LECSAt this time, the frequency deviation ΔF is set to the deviation ΔFs1 (=Fs1-Fn) between the reference frequency Fn and the target frequency Fs1. As a result, the equivalent load control amount P LECS is obtained.

[0081] The command transmitting unit 207 transmits a command signal to the load control terminal device 20 to disconnect a load corresponding to the set equivalent load control amount from the power grid 120. The load control terminal device 20 disconnects the corresponding load L from the power grid 120 in accordance with the command signal. Alternatively, the command transmitting unit 207 may transmit a command signal to the load control terminal device 20 to instruct a renewable energy power source corresponding to the set equivalent load control amount to perform a discharging operation. In this case, the load control terminal device 20 causes the corresponding renewable energy power source to start a discharging operation in accordance with the command signal.

[0082] In addition, the command sending unit 207 may select a load and a renewable energy power source corresponding to the equivalent load control amount, and send a command signal to the corresponding load control terminal device 20 to shut off the load and cause the renewable energy power source to perform a discharge operation.

[0083] Embodiment 2 In the first embodiment, a configuration for maintaining the finished frequency within the target frequency range after a generator trip has been described. In the second embodiment, a configuration for maintaining the finished frequency within the target frequency range after an equivalent load trip will be described. The above-described "overall configuration" and "hardware configuration" are the same, but the power system stabilization device 15 further has the following functions.

[0084] Specifically, the power system stabilization device 15 receives, from each of the load control terminal devices 21-2n, drop information indicating whether the corresponding load L and renewable energy power source ER have dropped off. Based on the drop information, the power system stabilization device 15 determines whether the loads L1-Ln and renewable energy power sources ER1-ERn have dropped off. For example, when the power system stabilization device 15 receives, from the load control terminal device 21, drop information indicating that the load L1 has been disconnected, the power system stabilization device 15 determines that the load L1 has dropped off.

[0085] Assume that a part of the equivalent load LE (for example, the equivalent load LEx) is dropped from the power system 120. In this embodiment, the drop of the equivalent load LEx means that a positive equivalent load P LEX This means that the equivalent load LEx having the equivalent load P LEX is positive when the load amount of the load L at the equivalent load LEx is greater than the output amount of the renewable energy power source ER at the equivalent load LEx.

[0086] When the equivalent load LEx is dropped from the power system 120, the system frequency rises. The power system stabilization device 15 sets the generator control amount to be disconnected (i.e., shut off) from the power system 120 so that the final frequency of the power system 120 after the equivalent load drop falls within the target frequency range. Specifically, the power system stabilization device 15 sets the generator control amount so that the final frequency of the power system 120 after the equivalent load drop falls within the target frequency range, using various characteristic information of each generator GA, system information, power output from the generators, various characteristic information of each load L, etc.

[0087] Therefore, the power system stabilization device 15 selects a generator corresponding to the generator control amount from among the generators GA1 to GAn based on a preset priority order, and outputs a command signal to shut off the selected generator to the fault detection terminal device 10. Note that this is one example of a method for setting the generator to be controlled in the power system stabilization device 15, and a generator may be selected using other methods. The fault detection terminal device 10 outputs a shutoff command to the circuit breaker CB in accordance with the command signal. As a result, the selected generator is disconnected from the power system 120, and the finished frequency of the power system 120 after the equivalent load drop is maintained within the target frequency range. In other words, the power system is stabilized.

[0088] <Generator control variable setting process> Suppose that the equivalent load LEx falls off. The equivalent load LEx falloff amount is P LEDR When the equivalent load is dropped, the generator control amount required to make the finished frequency of the power system 120 fall within the target frequency range is P GCS The equivalent load after the generator trips is P LE and total mechanical input value P M are expressed as equations (14) and (15), respectively.

[0089]

number

[0090] Therefore, “P LE0 =P M0 " and the simultaneous equations of equations (3), (14), and (15) are solved to obtain the generator control amount P required to make the frequency deviation between the finished frequency and the target frequency ΔF when an equivalent load drop occurs. GCS is expressed as the following equation (16).

[0091]

number

[0092] In addition, the equivalent load frequency characteristic coefficient K LEThe calculation method is the same as in the first embodiment. Therefore, the equivalent load frequency characteristic coefficient K LE By using this in equation (16), the appropriate generator control amount P GCS Therefore, the final frequency of the power system 120 after the equivalent load is dropped can be more appropriately kept within the target frequency range.

[0093] FIG. 7 is an image diagram for explaining the effect of the second embodiment. Referring to FIG. 7, graph 601 shows the change in frequency over time when the output of the generator is not controlled after the equivalent load is dropped. Graphs 602 and 604 show the change in frequency over time when the equivalent load frequency characteristic coefficient K LE (for example, without performing calculations such as equations (9), (12), and (13), the equivalent load frequency characteristic coefficient K LE (where is a fixed value), the graph 603 shows the time change of the frequency when the generator control amount is set using equation (16). LE This figure shows the time change of the frequency when the generator control amount is set using equation (16) taking into consideration (for example, by performing calculations such as equations (9), (12), and (13)).

[0094] Referring to graph 601, it can be seen that if the generator output is not controlled after the equivalent load is dropped at time t0a, the finished frequency is not within the target frequency range (i.e., above the reference frequency Fn and below the target frequency Fs2).

[0095] Referring to graph 602, when the generator output is controlled at time t1a after the equivalent load dropout, the finished frequency is closer to the target frequency Fs2 than the finished frequency of graph 601, but is not included within the target frequency range. This is because the equivalent load frequency characteristic coefficient K LE It is believed that this was because the value of was inappropriate and the set generator control amount was insufficient.

[0096] Referring to graph 604, when the generator output is controlled at time t1a after the equivalent load dropout, the finished frequency is included in the target frequency range, but the difference with the target frequency Fs2 is large. This is because the equivalent load frequency characteristic coefficient K LE This is thought to be because the value of was inappropriate and the generator control amount set was excessive.

[0097] On the other hand, referring to graph 603, when the generator output is controlled at time t1a after the equivalent load dropout, the finished frequency is included in the target frequency range and is close to the target frequency Fs2. This is because the equivalent load frequency characteristic coefficient K LE This is thought to be because the value of is appropriate, and as a result, appropriate generator control variables are set.

[0098] <Functional configuration> The functional configuration of the power system stabilizing device 15 according to the second embodiment will be described with reference to Fig. 7. The information receiving unit 201, the control amount setting unit 205, and the command transmitting unit 207 have the following functions in addition to the functions described above.

[0099] The information receiving unit 201 receives disconnection information indicating whether each of the loads L1 to Ln and each of the renewable energy power sources ER has been disconnected from each of the load control terminal devices 21 to 2 n. Typically, the disconnection information is a signal indicating the connection state between each of the loads and each of the renewable energy power sources monitored by each of the load control terminal devices 21 to 2 n and the power grid 120.

[0100] The coefficient calculation unit 203 calculates the total load amount P of the plurality of loads L at an initial point before the equivalent load LEx, which is a part of the equivalent load LE, is disconnected from the power grid 120. L0 and the total output value P of multiple renewable energy sources ER ER0 and the load frequency characteristic coefficient K L Based on the equivalent load frequency characteristic coefficient K LE The specific functional configuration of coefficient calculation section 203 is the same as that in the first embodiment, and therefore detailed description thereof will not be repeated.

[0101] When the equivalent load LEx is disconnected from the power grid 120, the control amount setting unit 205 sets the generator control amount P so that the final system frequency of the power grid 120 after the equivalent load LEx is disconnected falls within the target frequency range. GCS Set.

[0102] The control amount setting unit 205 calculates the equivalent load total value P LE0 Furthermore, the control amount setting unit 205 calculates the equivalent load total value P LE0 , frequency deviation ΔF, and generator frequency characteristic coefficient K G and the equivalent load frequency characteristic coefficient K LE and the equivalent load dropout amount P of the equivalent load LEx LEDR Based on this, the generator control amount P GCS Specifically, the control amount setting unit 205 sets the generator control amount P GCS At this time, the frequency deviation ΔF is set to the deviation ΔFs2 (=Fs2-Fn) between the reference frequency Fn and the target frequency Fs2. As a result, the generator control amount P GCS is obtained.

[0103] The command transmitting unit 207 transmits a command signal to the fault detection terminal device 10 to disconnect the generator corresponding to the set generator control amount from the power system 120. The fault detection terminal device 10 disconnects the corresponding generator GA from the power system 120 in accordance with the command signal.

[0104] Other embodiments. (1) In the above-described embodiment, the power system stabilizing device 15 is configured to receive various pieces of information from the fault detection terminal device 10 and the load control terminal device 20, but is not limited to this configuration. For example, the power system stabilizing device 15 may be configured to store the various pieces of information received from the fault detection terminal device 10 and the load control terminal device 20 in a memory in advance, and to execute the above-described frequency prediction process by using simulation software that can appropriately change the various pieces of information.

[0105] (2) The configurations exemplified as the above-described embodiments are merely examples of the configurations of the present invention, and may be combined with other known technologies, or may be modified, such as by omitting some parts, without departing from the spirit of the present invention. Furthermore, the above-described embodiments may be implemented by appropriately adopting the processes and configurations described in other embodiments.

[0106] The embodiments disclosed herein should be considered to be illustrative in all respects and not restrictive. The scope of the present invention is defined by the claims, not by the above description, and is intended to include all modifications within the meaning and scope of the claims. [Explanation of symbols]

[0107] 21, 22, 2n load control terminal device, 10 fault detection terminal device, 15 system stabilization device, 32 auxiliary transformer, 35 A / D conversion unit, 40 calculation processing unit, 41 CPU, 44 bus, 50 communication circuit, 55 digital output circuit, 56 digital input circuit, 80 transmission line, 100 power plant, 120 power system, 201 information receiving unit, 203 coefficient calculation unit, 205 control quantity setting unit, 207 command transmission unit, 1000 system stabilization system.

Claims

1. A system stabilization device for a power system to which a plurality of generators, a plurality of loads, and a plurality of renewable energy power sources are connected, A coefficient calculation unit that calculates an equivalent load frequency characteristic coefficient for an equivalent load that combines the plurality of loads and the plurality of renewable energy power sources; a control amount setting unit that sets an equivalent load control amount when a first generator of the plurality of generators is disconnected from the power grid so that a finished frequency of the power grid after the first generator is disconnected falls within a target frequency range, the coefficient calculation unit calculates the equivalent load frequency characteristic coefficient based on a total load amount value of the plurality of loads and a total output value of the plurality of renewable energy power sources at an initial point in time before the first generator is disconnected from the power grid, and load frequency characteristic coefficients for the plurality of loads; The control amount setting unit calculating an equivalent load total value for the equivalent load at the initial time point based on the load total value and the output total value at the initial time point; a power system stabilization device that sets the equivalent load control amount based on the total equivalent load amount, a frequency deviation between a reference frequency of the power system and the power system frequency, generator frequency characteristic coefficients of the plurality of generators, the equivalent load frequency characteristic coefficients, and a power source dropout amount of the first generator.

2. The total load value at the initial time point is P Ｌ０ , the output total value at the initial time point is P ＥＲ０ , the total equivalent load value at the initial time point is P ＬＥ０ When the above equation is satisfied, the control amount setting unit uses the following equation (1) to determine the P ＬＥ０ Calculate [Equation 1] The frequency deviation is ΔF, and the generator frequency characteristic coefficient is K Ｇ , the equivalent load frequency characteristic coefficient is K ＬＥ , the amount of power loss is P ＧＤＲ , the equivalent load control amount P ＬＥＣＳ When the above equation is satisfied, the control amount setting unit calculates the P ＬＥＣＳ Calculate [Equation 2] The power system stabilization device according to claim 1.

3. A system stabilization device for a power system to which a plurality of generators, a plurality of loads, and a plurality of renewable energy power sources are connected, A coefficient calculation unit that calculates an equivalent load frequency characteristic coefficient for an equivalent load that combines the plurality of loads and the plurality of renewable energy power sources; a control variable setting unit that sets a generator control variable when a part of the equivalent load is disconnected from the power grid so that a finished frequency of a system frequency of the power grid after the part of the equivalent load is disconnected falls within a target frequency range, the coefficient calculation unit calculates the equivalent load frequency characteristic coefficient based on a total load amount value of the plurality of loads and a total output value of the plurality of renewable energy power sources at an initial point in time before some of the equivalent loads are disconnected from the power grid, and load frequency characteristic coefficients of the plurality of loads; The control amount setting unit calculating an equivalent load total value for the equivalent load at the initial time point based on the load total value and the output total value at the initial time point; a system stabilization device that sets the generator control amount based on the total equivalent load amount, a frequency deviation between a reference frequency of the power system and the system frequency, generator frequency characteristic coefficients of the plurality of generators, the equivalent load frequency characteristic coefficients, and an equivalent load drop amount of a portion of the equivalent loads.

4. The total load value at the initial time point is P Ｌ０ , the output total value at the initial time point is P ＥＲ０ , the total equivalent load value at the initial time point is P ＬＥ０ When the above equation is satisfied, the control amount setting unit calculates the P ＬＥ０ Calculate [Equation 3] The frequency deviation is ΔF, and the generator frequency characteristic coefficient is K Ｇ , the equivalent load frequency characteristic coefficient is K ＬＥ , the equivalent load drop amount P ＬＥＤＲ , the generator control amount P ＧＣＳ When the above equation is satisfied, the control amount setting unit calculates the P ＧＣＳ Calculate [Equation 4] The power system stabilization device according to claim 3.

5. When the output sum does not have a frequency characteristic, the load frequency characteristic coefficient is set to K Ｌ When the above equation is satisfied, the coefficient calculation unit calculates the equivalent load frequency characteristic coefficient using the following equation (5): [Equation 5] The power system stabilization device according to claim 2 or 4.

6. When the frequency deviation is within a reference range, the output sum value is not changed, The coefficient calculation unit 5. The system stabilization device according to claim 2 or 4, wherein the equivalent load frequency characteristic coefficient is calculated based on the total load value and the total output value at the initial point in time, the load frequency characteristic coefficient, frequency characteristic coefficients for the plurality of renewable energy power sources, the frequency deviation, and the reference range.

7. The load frequency characteristic coefficient is K Ｌ , the frequency characteristic coefficients for the plurality of renewable energy power sources are K ＥＲ , the upper limit of the reference range is ΔF １ When the frequency deviation is greater than the upper limit of the reference range, the coefficient calculation unit calculates the equivalent load frequency characteristic coefficient by using the following equation (6): [Equation 6] The lower limit of the reference range is set to -ΔF １ When the frequency deviation is smaller than the lower limit value of the reference range, the coefficient calculation unit calculates the equivalent load frequency characteristic coefficient by using the following equation (7): [Equation 7] The power system stabilization device according to claim 6.

Images