JP6203449B2 - System stability estimation apparatus and system stability estimation method - Google Patents

Description

  The present invention relates to a system stability estimation device and a system stability estimation method for estimating transient stability of a plurality of system cross sections in an electric power system.

  In fields such as power system operation, supervisory control, and system stabilization, the stability of current and future power systems is calculated and used to calculate control amounts. In particular, transient stability (whether or not a step-out phenomenon occurs) when an accident occurs in the power system is one of the important factors.

  As a means for evaluating the transient stability, there is a method by an equal area method. When this equal area method is applied to the evaluation of transient stability, a power phase difference curve of the generator is required.

  As an evaluation method of behavior at the time of an accident in the electric power system, there is typically a method in which several accident forms and system states are assumed in advance, and behavior corresponding to each is calculated. At this time, as a method of calculating the power phase difference angle curve, a method of performing detailed stability calculation and calculating a power phase difference angle curve based on the calculation result of the detailed stability calculation is generally used (for example, Patent Document 1). reference).

JP 2003-348754 A

  In order to estimate the power system transient stability in advance using the equal area method for some accident modes and system conditions, it is necessary to estimate the power phase difference angle curve when a system disturbance occurs due to an accident or failure. In order to estimate such a power phase difference angle curve, detailed stability calculation must be performed.

  Since the generator output, load, and power flow in the power system change from moment to moment, it is desirable to always perform detailed stability calculations assuming the latest grid conditions. On the other hand, in order to estimate in advance the transient stability of the power system for accidents in many power facilities, it is necessary to perform detailed stability calculation many times, and the calculation time becomes enormous.

  The present invention has been made to solve the above-described problems, and a system stability estimation apparatus and system stability estimation method for estimating the transient stability of a plurality of system cross sections in a power system with less computation time. The purpose is to provide.

  The system stability estimation apparatus according to the present invention includes a power phase difference angle curve calculation unit that calculates a power phase difference angle curve that represents a relationship between the output power of the generator and a phase difference angle, and a power phase difference angle curve based on the power phase difference angle curve. The maximum power phase difference angle curve estimator that estimates the maximum power phase difference angle curve that expresses the relationship between the output power of the generator and the maximum phase difference angle that is the maximum point of reaching the phase difference angle after the accident, and the maximum power phase angle A system stability margin calculating unit that calculates a system stability margin based on the curve.

  The system stability estimation method according to the present invention includes (a) a step of calculating a power phase difference angle curve representing a relationship between the output power of the generator and a phase difference angle, and (b) a power generator based on the power phase difference angle curve. Estimating a maximum power phase difference angle curve representing the relationship between the amount of change in output power and the amount of change in maximum phase difference angle; and (c) estimating the maximum phase difference angle from the amount of change in output power in the power maximum phase difference angle curve. And calculating a margin for system stability.

  According to the system stability estimation apparatus and system stability estimation method according to the present invention, the maximum phase difference angle can be estimated without performing detailed stability calculation in each system section. According to the present invention, a power phase difference angle curve is obtained from a detailed stability calculation result in a system cross section, and a power maximum phase difference angle curve is estimated based on the power phase difference angle curve. Therefore, it is possible to estimate the maximum phase difference angle due to the occurrence of an accident when the system state changes based on the maximum power phase difference angle curve, and the system stability margin can be calculated. That is, since the margin of the system stability can be calculated without performing the detailed stability calculation in the system cross section in which the system state has changed, the calculation time can be shortened.

  The objects, features, aspects and advantages of the present invention will become more apparent from the following detailed description and the accompanying drawings.

3 is a functional block diagram of the system stability estimation apparatus according to Embodiment 1. FIG. 2 is a hardware configuration diagram of the system stability estimation apparatus according to Embodiment 1. FIG. It is a figure which shows the power phase difference angle curve which concerns on Embodiment 1. FIG. It is a figure for demonstrating the method of estimating the maximum electric power phase difference angle curve from the electric power phase difference angle curve which concerns on Embodiment 1. FIG. It is a figure which shows the maximum power phase difference angle curve which concerns on Embodiment 1. FIG. 3 is a flowchart showing the operation of the system stability estimation apparatus according to Embodiment 1. 6 is a functional block diagram of a system stability estimation apparatus according to Embodiment 2. FIG. 6 is a flowchart showing the operation of the system stability estimation apparatus according to the second embodiment. FIG. 10 is a functional block diagram of a system stability estimation apparatus according to Embodiment 3. 10 is a flowchart showing the operation of the system stability estimation apparatus according to Embodiment 3. FIG. 10 is a functional block diagram of a system stability estimation device according to Embodiment 4.

<Embodiment 1>
<Configuration>
FIG. 1 is a functional block diagram of the system stability estimation apparatus 1 according to the first embodiment. The system stability estimation apparatus 1 includes an arithmetic processing unit 150 and a data storage unit 180. The arithmetic processing unit 150 stores data used for processing in the data storage unit 180 and reads the stored data.

  The arithmetic processing unit 150 includes a sensor input unit 152, a data setting unit 154, a power phase difference angle curve calculation unit 160, a reference cross section maximum phase difference angle calculation unit 170, a power maximum phase difference angle curve estimation unit 171 and system stability. And a margin calculating unit 172.

  The sensor input unit 152 receives a measurement value of an electrical quantity (current, voltage, active power, reactive power, etc.) from the power system, and stores it in the data storage unit 180 as an electrical quantity measurement value 181.

  The data setting unit 154 receives the setting value. Specifically, system constants such as transmission line impedance and transformer transformation ratio are received and stored in the data storage unit 180 as system information 182, and an assumed accident condition is received and the data storage unit 180 as an accident condition 183. To store.

  The power phase difference angle curve calculation unit 160 calculates a power phase difference angle curve. Specifically, the power phase difference angle curve is calculated using the electric quantity measurement value 181, the system information 182, and the accident condition 183 stored in the data storage unit 180. Then, the power phase difference angle curve coefficient defining the calculated power phase difference angle curve is stored in the data storage unit 180 as the power phase difference angle curve coefficient 186.

  Next, power phase difference angle curve calculation processing in the power phase difference angle curve calculation unit 160 shown in FIG. 1 will be described. The power phase difference angle curve calculation unit 160 includes a detailed stability calculation unit 162 and a power phase difference angle curve coefficient identification unit 164.

The detailed stability calculation unit 162 performs the detailed stability calculation using the system information 182 and stores the result in the data storage unit 180 as the detailed stability calculation result 185. In the detailed stability calculation, a simulation that simulates the transient fluctuation phenomenon of the power system is executed, and at least the generator output active power (P _e ) and the generator internal phase difference angle (δ) are calculated.

  The power phase difference angle curve coefficient identifying unit 164 determines a power phase angle curve from the active power information and phase difference angle information of the detailed stability calculation result 185, and identifies the power phase angle curve coefficient from the power phase angle curve. Then, the obtained power phase difference angle curve coefficient is stored in the data storage unit 180 as the power phase difference angle curve coefficient 186.

  The reference cross section maximum phase difference angle calculation unit 170 calculates the power output from the detailed stability calculation result and calculates the maximum phase difference angle.

  The power maximum phase difference angle curve estimation unit 171 uses the power phase difference angle curve calculated by the power phase difference angle curve calculation unit 160 to output the output power (generator output) of the generator before the accident and the generator after the accident occurs. The power maximum phase difference curve showing the relationship of the maximum phase angle is estimated. Here, the maximum phase difference angle is the maximum reaching point of the generator phase difference angle after the accident occurs. Here, “before the accident” means immediately before the accident occurs. “After the accident” means the time from the occurrence of the accident until the transient system disturbance due to the accident and the removal of the accident is sufficiently settled. The system stability margin calculation unit 172 calculates a system stability margin when the system cross section changes.

  FIG. 2 is a diagram illustrating a hardware configuration of the system stability estimation apparatus 1. The data setting unit 154 in FIG. 1 can be realized by inputting with the input device 2001 shown in FIG.

  The data storage unit 180 in FIG. 1 can be realized by storing in the main storage device 2003 shown in FIG. 2 and saving or reading and saving via a transmission medium. The sensor input unit 152 measures the voltage, current, active power, reactive power, and the like of each bus and power transmission line connected to the system and stores them in the data storage unit 180.

  The data setting unit 154 stores the transmission line impedance, the transformer transformation ratio, and the like in the data storage unit 180. The target accident condition is stored in the data storage unit 180.

  The power phase difference angle curve calculation unit 160, the reference cross section maximum phase difference angle calculation unit 170, the power maximum phase difference angle curve estimation unit 171 and the system stability margin calculation unit 172 in FIG. 1 read out data necessary for the CPU 2005 from the main storage device 2003. This is realized as a function of the CPU 2005 by executing a software program stored in the secondary storage device 2002. However, these may be realized in cooperation with a plurality of CPUs 2005, for example.

  In the above description, the power phase difference angle curve calculation unit 160, the reference cross section maximum phase difference angle calculation unit 170, the power maximum phase difference angle curve estimation unit 171 and the system stability margin calculation unit 172 are executed by the CPU 2005 of FIG. It was realized by operating in accordance with a software program stored in the above. However, instead of this, the power phase difference angle curve calculation unit 160, the reference cross section maximum phase difference angle calculation unit 170, the power maximum phase difference angle curve estimation unit 171 and the system stability margin calculation unit 172 perform the operation by an electrical circuit of hardware. You may implement | achieve by the signal processing circuit to implement | achieve. Software power phase difference angle curve calculation unit 160, reference cross section maximum phase difference angle calculation unit 170, power maximum phase difference angle curve estimation unit 171, system stability margin calculation unit 172, hardware power phase difference angle curve calculation unit 160, reference cross section As a concept combining the maximum phase difference angle calculation unit 170, the power maximum phase difference angle curve estimation unit 171 and the system stability margin calculation unit 172, the word “processing circuit” or “module” is used instead of the word “part”. You can also.

<Operation>
First, the basic concept of the method for calculating the power phase difference angle curve in the first embodiment will be described. FIG. 3 is a diagram for explaining the basic concept of the method for estimating the power phase difference angle curve according to the first embodiment.

FIG. 3 is a diagram showing a power phase difference angle curve in a certain system section (hereinafter also referred to as a reference section). The power phase angle curve shows the relationship between the δ internal phase angle of the generator and the generator output P _e. The power phase difference angle curve is calculated by detailed stability calculation. The power phase difference angle curve can be approximated by the following equation 1 from its characteristics. In Equation 1, P ₀ , P ₁ and P ₂ are power phase difference angle curve coefficients.

A method for estimating the maximum phase difference angle δ _max based on the equal area method from the power phase difference angle curve calculated by the detailed stability calculation will be described. As shown in FIG. 3, the area of a portion the generator output P _e in the steady state is assumed to be equal to the mechanical input P _m0, the locus of the power phase angle plane due to accident falls below the mechanical input P _m0 VA ₀ (acceleration energy) and an area VD ₀ (deceleration energy) of a portion exceeding the mechanical input P _m0 are calculated.

That is, immediately after the accident occurs, the transmission power from the generator decreases as the system voltage decreases, so the mechanical input P _m0 to the generator becomes redundant, and the generator itself accelerates to store kinetic energy. After that, when the accident is removed, the system voltage recovers, so the generator releases kinetic energy and decelerates. Here, if the acceleration energy is relatively large, the generator continues to accelerate and the phase difference angle increases, and eventually a step-out phenomenon may occur. On the other hand, if the deceleration energy is relatively large, the phase difference angle of the generator spreads to a certain extent, but the balance is maintained at the phase difference angle that has been decelerated before reaching the step-out phenomenon.

At this time, as shown in FIG. 3, the maximum phase difference angle (δ _R0 ) is a phase difference angle at which acceleration energy (corresponding to area VA ₀ ) and deceleration energy up to the maximum arrival point (corresponding to area VD ₀ ) are equal. is there.

  If such a maximum phase difference angle is calculated for a plurality of system cross sections, it is necessary to perform a detailed stability calculation for each system cross section. Performing the detailed stability calculation for each system section requires enormous calculation time.

Therefore, the system stability estimation apparatus 1 according to the first embodiment estimates the relationship between the mechanical input P _m0 and the maximum phase difference angle δ _R0 from the power phase difference angle curve in the reference cross section, thereby making the mechanical input from the reference cross section. Is estimated to be the maximum phase difference angle δ _R1 at the system cross section where ΔP _{m is} increased. More specifically, system stability estimating device 1 estimates the relationship between P _e and the maximum phase angle δmax based on the area method using power phase difference angle curve in the reference plane. Then, the margin of system stability is calculated based on the estimated maximum phase difference angle.

A method for estimating the maximum power phase difference angle curve indicating the relationship between the mechanical input P _m0 of the generator and the maximum phase difference angle from the power phase difference angle curve calculated by the detailed stability calculation will be described.

  FIG. 4 is a diagram for explaining the principle of estimating the maximum power phase difference angle curve of the system stability estimation apparatus 1 according to the first embodiment.

FIG. 4 shows a power phase difference angle curve in the reference cross section. As shown in FIG. 4, when the generator output P _e increases [Delta] P _m from P _m0 in some state, the maximum phase difference angle from [delta] _R0 to Δδ increased by [delta] _R1. Also at this time, the acceleration energy (area VA ₀ ) and the deceleration energy (area VD ₀ ) are the same area. Therefore, it is possible to only power phase angle curve without performing detailed stability calculations, to calculate the maximum phase angle increment Δδ for the output increment [Delta] P _m.

When calculating Δδ, since the detailed stability calculation is not performed, the phase difference angle (δ _C ) at the time of accident removal cannot be obtained accurately. In the first embodiment, the initial phase difference angle (δ ₀ ) and the advance amount of the phase difference angle during the accident (δ _C −δ ₀ ) are constant under the condition that the change ΔP _m in the generator output is very small. Assume that there is. Through this process, it is possible to calculate the change amount Δδ of the maximum phase difference angle from the power phase difference angle curve.

  The increase in acceleration energy is equal to the increase in deceleration energy minus the decrease in deceleration energy. This relationship is expressed as Equation 2 using a power phase difference curve (Equation 1).

When Expression 2 is transformed into Expression 3, the relationship between the generator output change ΔP _m and the maximum phase difference angle change Δδ is expressed as Expression 4.

Since a set of ΔP _m and Δδ can be uniquely determined as in Expression 4, for example, when Δδ is changed variously (for example, from 1 [deg] by −90 [deg] to 90 [deg]) By calculating ΔP _m , deviations (ΔP _m and Δδ) from P _m and δ _R0 of the reference cross section are determined, and the maximum power phase difference angle curve (FIG. 5) can be obtained.

Finally, the margin of system stability when the generator output changes is obtained from the maximum power phase difference angle curve (FIG. 5). In the first embodiment, the margin of system stability is defined by Equation 5. In Equation 5, δ _limit is the limit of the maximum phase difference angle due to the occurrence of an accident (for example, preset to 120 [deg]), and δ _max is the maximum phase difference angle at the assumed generator output.

If the system stability is judged based on whether or not a step-out occurs due to the occurrence of an accident, the maximum value of deceleration energy (all the parts where the locus on the power phase difference angle plane accompanying the occurrence of the accident exceeds the mechanical input P _m0) It is also possible to define the value obtained by subtracting the acceleration energy from the area) as the system stability margin. There is also a method of calculating the system stability margin by giving a margin to the deceleration energy assuming the operation of the step-out prevention system by the system stabilization device or the like.

Hereinafter, it will be described in detail methods for identifying the power phase angle curve power phase angle curve coefficients in Equation _{(1) (P 0, P 1} , P 2). Any known method can be adopted as the identification method, but an example using the least square method is shown here.

  As described above, the power phase difference angle curve in an arbitrary system cross section can be approximated by the above-described expression 1 from its characteristics. When Expression 1 is expressed in the form of a matrix, it can be expressed as Expression 6 below.

When the time series data (n pieces) of the power information (P _e ) and the phase difference angle information (δ) included in the result of the detailed stability calculation is substituted into Expression 6, Expression 7 is derived.

In Equation 7, P _{e, i} is i-th power information, and δ _i is i-th phase difference angle information. The power phase difference angle curve coefficients (P ₀ , P ₁ , P ₂ ) are determined from Equation 7. Specifically, the power phase difference angle curve coefficients (P ₀ , P ₁ , P ₂ ) are calculated by transforming Expression 7 into Expression 8.

The power phase difference angle curve coefficients (P ₀ , P ₁ , P ₂ ) calculated according to Equation 8 are used as the power phase difference angle curve coefficients in this system section.

The power phase difference angle curve is determined by substituting the obtained power phase difference angle curve coefficients (P ₀ , P ₁ , P ₂ ) into Equation 1. The maximum phase difference angle δ _R0 of the system cross section is obtained from the power phase difference curve.

The method for calculating the generator initial output P _m0 and the maximum phase difference angle δ _R0 from the power phase difference angle curve by using the equal area method has been described, but the generator initial output and the generator included in the result of the detailed stability calculation are described. The maximum value of the phase difference angle may be employed as (P _m0 , δ _R0 ), respectively.

<Description of flowchart>
A processing procedure for estimating the system stability in the system stability estimation apparatus 1 will be described. FIG. 6 is a flowchart showing the operation of the system stability estimation apparatus 1. Each step shown in FIG. 6 is executed by each functional unit constituting the system stability estimation apparatus 1 shown in FIG.

  First, the sensor input unit 152 measures the amount of electricity (current, voltage, active power, reactive power, etc.) from a bus or a transmission line connected to the power system, and the measured amount of electricity is used as an amount of electricity measurement value 181. The data is stored in the data storage unit 180 (step S101).

Subsequently, the detailed stability calculation unit 162 included in the power phase difference angle curve calculation unit 160 performs the detailed stability calculation using the system information 182, the accident condition 183, and the electric quantity measurement value 181 (step S102). . Then, the power phase difference angle curve coefficient identification unit 164 calculates the power phase difference angle curve coefficients (P ₀ , P ₁ , P ₂ ) according to Equation 8 using the result of the detailed stability calculation (step S103). The power phase difference angle curve coefficient is stored in the data storage unit 180. A power phase difference angle curve is determined by substituting the power phase angle curve coefficient into Equation 1 (step S104).

Further, the reference cross section maximum phase difference angle calculation unit 170 calculates the power output (acceleration energy) from the detailed stability calculation result, and calculates the maximum phase difference angle δ _R0 in which the deceleration energy has the same area (step S105). Next, the maximum power phase difference angle curve estimation unit 171 sequentially obtains the maximum phase difference angle when the generator output is changed from the power phase difference angle curve based on the equation 4 by the equal area method, and connects the sample points. A power maximum phase difference angle curve (FIG. 5) is estimated (step S106).

Next, the system stability margin calculation unit 172 obtains the maximum phase difference angle δ _max at the assumed generator output from the power maximum phase difference angle curve (FIG. 5) (step S107). Then, based on Equation 5, a margin amount up to a preset maximum phase difference angle limit δ _limit is calculated (step S108).

<Effect>
The system stability estimation apparatus 1 according to the first embodiment is based on a power phase difference angle curve calculation unit 160 that calculates a power phase difference angle curve that represents the relationship between the output power of the generator and the phase difference angle, and the power phase difference angle curve. A maximum power phase difference angle curve estimation unit 171 that estimates a maximum power phase difference angle curve that represents a relationship between the output power of the generator before the accident and the maximum phase difference angle that is the maximum point of reaching the phase difference angle after the accident; A system stability margin calculating unit 172 that calculates a system stability margin based on the maximum power phase difference angle curve.

  Therefore, according to the first embodiment, the maximum phase difference angle can be estimated without performing the detailed stability calculation in each system section. In general, the detailed stability calculation requires more calculation time, so if you try to calculate the power phase difference angle curve by performing the detailed stability calculation for each system section, enormous calculation time is required. . On the other hand, according to the first embodiment, the power phase difference angle curve is obtained from the detailed stability calculation result in a certain system cross section, and the maximum power phase difference angle curve is estimated based on the power phase difference angle curve. Therefore, it becomes possible to estimate the maximum phase difference angle due to the occurrence of an accident when the system state changes based on the power maximum phase difference angle curve, and the system stability margin can be calculated. That is, since the system stability margin can be calculated without performing the detailed stability calculation in the section where the system state has changed, the calculation time can be shortened.

  Moreover, in the system stability estimation apparatus 1 according to the first embodiment, the maximum power phase difference angle curve estimation unit 171 estimates the maximum power phase difference angle curve on the assumption that the initial phase difference angle and the advance amount of the phase difference angle are constant. To do.

  Therefore, by assuming that the initial phase difference angle and the advance amount of the phase difference angle are constant, it is possible to estimate the power maximum phase difference angle curve by applying the equal area method to the power phase difference angle curve.

Moreover, in the system stability estimation apparatus 1 according to the first embodiment, the system stability margin calculation unit 172 estimates the maximum phase difference angle (δ _max ) from the power maximum phase difference angle curve and is predetermined as the maximum phase difference angle. And the phase difference angle (δ _limit ) is compared to calculate the margin of system stability.

Therefore, by changing the value of the predetermined phase difference angle (δ _limit ), it is possible to give a margin to the margin of the system stability, for example, assuming the operation of the step-out prevention system by the system stabilization device or the like. .

  Moreover, the system stability estimation method in this Embodiment 1 is based on (a) the process of calculating the power phase difference angle curve showing the relationship between the output electric power of a generator, and a phase difference angle, and (b) the power phase difference angle curve. A step of estimating a maximum power phase difference angle curve representing the relationship between the amount of change in the output power of the generator and the amount of change in the maximum phase difference angle; and (c) the maximum phase difference from the amount of change in the output power in the power maximum phase difference angle curve. Estimating a corner and calculating a margin of system stability.

  Therefore, according to the first embodiment, the maximum phase difference angle can be estimated without performing the detailed stability calculation in each system section. According to the first embodiment, the power phase difference angle curve is obtained from the detailed stability calculation result in a certain system cross section, and the power maximum phase difference angle curve is estimated based on the power phase difference angle curve. Therefore, it becomes possible to estimate the maximum phase difference angle due to the occurrence of an accident when the system state changes based on the power maximum phase difference angle curve, and the system stability margin can be calculated. That is, since the system stability margin can be calculated without performing the detailed stability calculation in the section where the system state has changed, the calculation time can be shortened.

  In the system stability estimation method according to the first embodiment, in step (b), the maximum phase difference angle curve is estimated on the assumption that the initial phase difference angle and the advance amount of the phase difference angle are constant.

  Therefore, by assuming that the initial phase difference angle and the advance amount of the phase difference angle are constant, it is possible to estimate the power maximum phase difference angle curve by applying the equal area method to the power phase difference angle curve.

  Further, in the system stability estimation method according to the first embodiment, in step (c), the maximum phase difference angle is estimated from the power maximum phase difference curve, and the maximum phase difference angle is compared with a predetermined phase difference angle. Calculate the margin of system stability.

Therefore, by changing the value of the predetermined phase difference angle (δ _limit ), it is possible to give a margin to the margin of the system stability, for example, assuming the operation of the step-out prevention system by the system stabilization device or the like. .

<Embodiment 2>
<Configuration>
FIG. 7 is a functional block diagram of system stability estimation apparatus 1A according to the second embodiment. The system stability estimation apparatus 1A further includes a power flow calculation unit 156 as compared with the system stability estimation apparatus 1 (FIG. 1) of the first embodiment. Other functional configurations are the same as those in the first embodiment, and thus description thereof is omitted.

  The tidal current calculation unit 156 performs tidal current calculation of the power system. Specifically, a tidal current calculation for calculating a tidal current distribution in the power system to be estimated is performed using the electric quantity measurement value 181 and the grid information 182. The tidal current calculation is to calculate the tidal current distribution in the power system, and it is not necessary to analyze the transient state. Therefore, the calculation result can be output in a shorter time than the above detailed stability calculation.

  The tidal current calculation unit 156 stores the power value included in the tidal current calculation result in the data storage unit 180 as the tidal current calculation result 184.

<Operation>
A processing procedure for estimating the system stability in the system stability estimation apparatus 1A will be described. FIG. 8 is a flowchart showing the operation of the system stability estimation apparatus 1A. The flowchart shown in FIG. 8 is obtained by further adding a step of calculating the amount of power change (step S207) to the flowchart shown in FIG.

Steps S201 to S206 in FIG. 8 are the same as steps S101 to S106 in FIG. In step S207, the power flow calculation unit 156 calculates a generator output in the power system by power flow calculation. Then, to calculate the power variation [Delta] P _m from the generator output by the grid section embodying the detailed stability calculation.

In subsequent step S208, S209, similarly to the first embodiment, estimates the maximum phase angle power variation [Delta] P _m together against the power maximum phase angle curve (FIG. 5), calculates the amount of margin system stability To do.

<Effect>
The system stability estimation apparatus 1B according to the second embodiment further includes a power flow calculation unit 156 that calculates the amount of change in the output power of the generator by performing power flow calculation, and the system stability margin calculation unit 172 includes a power maximum The maximum phase difference angle is estimated from the amount of change in the output power in the phase difference angle curve, and the margin of system stability is calculated.

  According to the second embodiment, in addition to the effects of the first embodiment, when the system state changes from the current system cross section, the value of the generator output is accurately calculated by the power flow calculation that can be calculated in a short calculation time. In addition to shortening the calculation time, the accuracy of the system stability margin can be improved.

  In addition, the system stability estimation method according to the second embodiment includes (d) step (c) (that is, the maximum phase difference angle is estimated from the amount of change in output power in the power maximum phase difference angle curve, and the system stability margin is obtained. The step of calculating a change amount of the output power of the generator by performing a power flow calculation before the step of calculating the power flow, and in step (c), the maximum amount of change in the output power in the power maximum phase difference curve is calculated. Estimate the phase difference angle and calculate the margin of system stability.

  Therefore, when the system status changes from the current system cross section, it is possible to accurately calculate the generator output value by power flow calculation that can be calculated in a short calculation time, and in addition to shortening the calculation time, system stability The margin accuracy can be improved.

<Embodiment 3>
The system stability estimation apparatus 1B according to the third embodiment assumes that a power transaction has been performed when new power generation and consumption are expected to occur from the current system cross section. The margin amount is calculated, and whether or not power trading is possible is determined based on the margin amount of the system stability.

<Configuration>
FIG. 9 is a functional block diagram of system stability estimation apparatus 1B according to the third embodiment. Compared with system stability estimation apparatus 1A (FIG. 7) according to the second embodiment, system stability estimation apparatus 1B further includes power transaction availability determination unit 173 and power transaction availability determination result output unit 174. Further, the data storage unit 180 further stores power transaction information 188 and a power transaction availability determination result 189.

  That is, the system stability estimation device 1B according to the third embodiment is compared with the system stability estimation device 1A according to the second embodiment, the power transaction availability determination unit 173, the power transaction availability determination result output unit 174, and the power transaction information. 188, the power transaction availability determination result 189 is added, the power transaction availability determination is performed based on the calculated system stability margin after power transaction, and the result is output.

  The data setting unit 154 of the system stability estimation apparatus 1B includes, in addition to the operation of the data setting unit 154 of the system stability estimation apparatus 1A, power transaction information 188 including power sale information and power purchase information scheduled for power transaction. Is stored in the data storage unit 180.

  In the third embodiment, the power flow calculation unit 156 selects a set of power sale information and power purchase information from the power transaction information 188, and executes a power transaction based on the information stored in each power system. Tidal current calculation is performed. Then, the generator output in the power system is calculated from the result of the power flow calculation.

  In the third embodiment, the system stability margin calculation unit 172 compares the power change amount from the generator output that has already been subjected to the detailed stability calculation with the power maximum phase difference curve (FIG. 5) to determine the maximum phase difference angle. presume. Then, a margin for system stability is calculated.

  In the present third embodiment, the power transaction availability determination unit 173 determines whether or not the power transaction is possible based on the grid stability margin. Then, the power transaction availability determination result 189 is stored in the data storage unit 180.

  In the third embodiment, the power transaction availability determination result output unit 174 outputs the power transaction availability determination result 189 to, for example, an external display.

  Here, as a method of selecting a pair of power sale information and power purchase information from the power transaction information 188, for example, the power sale information with the lowest power sale price and the power purchase information with the highest power purchase price are combined. . In addition, when there are a plurality of pieces of power sale information or power purchase information having the same price, information with early data setting timing is used. This embodiment does not specify a method for combining the power sale information and the power purchase information.

<Operation>
A processing procedure for estimating the system stability in the system stability estimation apparatus 1B will be described. FIG. 10 is a flowchart showing the operation of the system stability estimation apparatus 1B. Steps S301 to S306 in FIG. 10 are the same as steps S201 to S206 in FIG. In step S307, the power flow calculation unit 156 selects a set of power sale information and power purchase information from the power transaction information 188, performs power flow calculation assuming a power system when the power transaction is performed, and outputs the generator output. Is calculated. Then, to calculate the power variation [Delta] P _m from the generator output by the grid section embodying the detailed stability calculation.

In subsequent step S308, S309, as in the second embodiment, to estimate the maximum phase difference angle against the power maximum phase angle curve (FIG. 5) the power change amount [Delta] P _m, calculates the amount of margin system stability To do.

  Furthermore, in step S310, the power transaction feasibility determination unit 173 performs the power transaction feasibility determination based on the calculated system stability margin.

<Effect>
The system stability estimation apparatus 1B according to the third embodiment further includes a power transaction feasibility determination unit 173, and the system stability margin calculation unit 172 calculates the margin of the system stability assuming a case where power is traded. The power trading availability determination unit 173 determines whether or not power trading is possible based on the system stability margin.

  Therefore, according to the third embodiment, in addition to the effects of the second embodiment, it is possible to calculate the amount of system stability margin according to the power transaction content, and to determine whether or not the power transaction can be performed in a short calculation time. Is possible.

  In addition, the system stability estimation method according to the third embodiment includes (e) step (c) (that is, the maximum phase difference angle is estimated from the amount of change in the output power in the power maximum phase difference angle curve, and the system stability margin is obtained. And a step of determining whether or not power trading is possible on the basis of the margin of the system stability, and assuming that power trading is performed in step (c). Calculate the amount of margin.

  Therefore, according to the third embodiment, it is possible to calculate a margin of grid stability according to the contents of power transaction, and it is possible to determine whether or not power transaction can be performed in a short calculation time.

<Embodiment 4>
FIG. 11 is a functional block diagram of system stability estimation apparatus 1C according to the fourth embodiment. Compared with system stability estimation apparatus 1 (FIG. 1) of Embodiment 1, system stability estimation apparatus 1C further includes an electrical quantity predicted value input unit 175. In addition, the data storage unit 180 further stores a predicted electric quantity 190. Since other functional configurations are the same as those in the first embodiment, description thereof is omitted.

  The predicted electric quantity input unit 175 receives predicted values of various electric quantities of the power system and stores them as the predicted electric quantity 190 in the data storage unit 180. Here, the predicted values of various electric quantities include a voltage predicted value, a current predicted value, an active power predicted value, a reactive power predicted value, and the like. The system stability estimation apparatus 1 </ b> C according to the fourth embodiment includes an electrical quantity predicted value input unit 175. Therefore, not only the various measurement values (voltage, current, active power, reactive power, etc.) input to the sensor input unit 152 but also the predicted values of electricity such as power generation output derived from renewable energy, load amount, and bus voltage. Can be input to the predicted electric quantity input unit 175.

  In the fourth embodiment, the power phase difference angle curve calculation unit 160 performs a calculation by replacing part or all of the electricity quantity measurement value 181 with the electricity quantity prediction value 190.

  The system stability estimation device 1A (FIG. 7) according to the second embodiment may further include an electrical quantity predicted value input unit 175. In this case, the power flow calculation unit 156 of the system stability estimation apparatus 1A performs a calculation by replacing a part or all of the electric quantity measurement value 181 with the electric quantity prediction value 190. In addition, the system stability estimation apparatus 1B (FIG. 9) according to the third embodiment may further include a predicted electric quantity input unit 175. In this case, in the calculation performed by the system stability estimation apparatus 1A, the calculation is performed by replacing part or all of the measured electric quantity 181 with the predicted electric quantity 190.

  In the system stability estimation apparatus 1C according to the fourth embodiment, in addition to the effects described in the first to third embodiments, the power generation output derived from renewable energy expected in the future in the detailed stability calculation and the power flow calculation, Calculations based on predicted values of the amount of electricity such as the load amount and the bus voltage can be performed. As a result, it is possible to calculate a margin of system stability assuming a future system cross section.

  Although the present invention has been described in detail, the above description is illustrative in all aspects, and the present invention is not limited thereto. It is understood that countless variations that are not illustrated can be envisaged without departing from the scope of the present invention.

  1, 1A, 1B System stability estimation device, 150 arithmetic processing unit, 180 data storage unit, 152 sensor input unit, 154 data setting unit, 160 power phase difference angle curve calculation unit, 162 detailed stability calculation unit, 164 power phase difference angle Curve coefficient identification unit, 170 Reference cross section maximum phase difference angle calculation unit, 171 Power maximum phase difference angle curve estimation unit, 172 System stability margin calculation unit, 173 Power transaction availability determination unit, 174 Power transaction availability determination result output unit, 175 Electric quantity Predicted value input unit, 180 data storage unit, 181 electricity measurement value, 182 system constant, 183 accident condition, 185 detailed stability calculation result, 186 power phase difference angle curve coefficient, 187 power maximum phase difference angle curve, 188 power transaction information, 189 Electricity transaction feasibility determination result, 190 electricity predicted value, 2001 input device, 2002 secondary storage device, 2003 Main storage device, 2004 output device, 2005 CPU.

Claims (10)

A power phase difference angle curve calculating unit for calculating a power phase difference angle curve representing the relationship between the output power of the generator and the phase difference angle;
Based on the power phase difference angle curve, the power maximum phase difference angle curve representing the relationship between the output power of the generator before the accident occurrence and the maximum phase difference angle which is the maximum point of reaching the phase difference angle after the accident occurrence is estimated. A maximum phase difference curve estimator,
A system stability margin calculation unit that calculates a margin of system stability based on the maximum power phase difference angle curve;
Comprising
System stability estimation device. It further includes a tidal current calculation unit that calculates the amount of change in the output power of the generator by performing tidal current calculation,
A system stability margin calculation unit estimates a maximum phase difference angle from the amount of change in the output power in the power maximum phase difference angle curve, and calculates a system stability margin amount.
The system stability estimation apparatus according to claim 1. It further includes a power transaction availability determination unit,
The system stability margin calculation unit calculates the amount of system stability margin assuming the case of trading power,
The power transaction availability determination unit determines whether or not power transaction is possible based on the margin of the system stability.
The system stability estimation apparatus according to claim 1. The power maximum phase difference angle curve estimation unit estimates the power maximum phase difference angle curve on the assumption that the initial phase difference angle and the advance amount of the phase difference angle are constant.
The system stability estimation apparatus according to claim 1. The system stability margin calculation unit estimates a maximum phase difference angle from the power maximum phase difference angle curve, and compares the maximum phase difference angle with a predetermined phase difference angle to calculate a margin amount of system stability.
The system stability estimation apparatus according to claim 1. (A) calculating a power phase difference angle curve representing a relationship between the output power of the generator and the phase difference angle;
(B) estimating a power maximum phase difference angle curve representing a relationship between a change amount of the output power of the generator and a change amount of the maximum phase difference angle based on the power phase difference angle curve;
(C) estimating the maximum phase difference angle from the amount of change in the output power in the maximum power phase difference angle curve, and calculating a margin for system stability;
Comprising
System stability estimation method. (D) before the step (c), further comprising the step of calculating the amount of change in the output power of the generator by performing a tidal current calculation,
In the step (c), the maximum phase difference angle is estimated from the amount of change of the output power in the maximum power phase difference angle curve, and a margin of system stability is calculated.
The system stability estimation method according to claim 6. (E) after the step (c), further comprising the step of determining whether or not power trading is possible based on the margin of the system stability;
In the step (c), a margin for system stability is calculated on the assumption that power is traded.
The system stability estimation method according to claim 6. In the step (b), assuming that the initial phase difference angle and the advance amount of the phase difference angle are constant, the power maximum phase difference angle curve is estimated.
The system stability estimation method according to claim 6. In the step (c), the maximum phase difference angle is estimated from the power maximum phase difference angle curve, and the maximum phase difference angle is compared with a predetermined phase difference angle to calculate a margin of system stability.
The system stability estimation method according to claim 6.

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