JP4044512B2 - Power system stabilization control device and power system stabilization control method - Google Patents

Description

  The present invention relates to a power system stabilization control device and a power system stabilization control method for performing a stabilization control by calculating a control amount that is stably maintained when a failure occurs in a power system.

  A system stabilizing device as a conventional power system stabilizing control device tabulates a transient stability maintenance countermeasure control amount for each assumed failure by stability calculation for a failure (control target failure) that can be assumed in advance. For example, when a ground fault occurs in a transmission line, the system stabilization device is activated with a sudden change in the measurement element such as voltage drop as a kick, and the failure type is identified by the information on the transmission line protection relay or the input information on the circuit breaker To do. In addition, the power system stabilizer always calculates the power flow value that flows through the transmission line from the current and voltage input through the sensor, and compares it with a preset control table (control value for power flow value, failure point, failure type, etc.). Then, a system stabilization control amount is calculated, and a shutoff signal is output through an output cable to a generator that generates electric power corresponding to the control amount to maintain transient stability (for example, Patent Document 1). reference).

  In addition, the conventional power system stabilization control method according to another example is an online stabilization control method based on the result of online measurement, and a control logic is constructed based on the energy method to predict predictive and quantitative stability. Evaluate. In addition, an effective power output-internal angle curve based on online data is estimated, and an optimum stabilization control amount is calculated in accordance with an accident condition or a system state (for example, see Non-Patent Document 1).

JP 2001-359241 A "Development of on-line stabilization control system for large-capacity power supply system" IEEJ Transactions Volume B, August 1990, (Vol.110-B, No.8)

  Such conventional power system stabilization control performs appropriate stabilization control in accordance with the accident conditions and system conditions in the event of an accident, but the economic loss due to the stabilization control is hardly considered, and transient There has been a problem that proper control for maintaining the stability may involve a large economic loss.

  The present invention has been made to solve the above-described problems. When a disturbance occurs in the power system, an appropriate stabilization control can be quickly performed by on-line control in accordance with the accident condition and system state. The purpose of the present invention is to carry out stable control and system operation with good economic efficiency while suppressing economic loss due to the control.

When a disturbance occurs in the power system, the power system stabilization control apparatus according to the present invention stabilizes the power system by performing appropriate control on the power system. The power system stabilization control device includes means for detecting the occurrence of an accident in the power system from various quantities (hereinafter referred to as system information) measured in each part of the power system, and the system information after the occurrence of the accident is detected. Based on the above, a means for calculating the required control amount online so as to maintain transient stability for the generator or load to be controlled, and a plurality of controls that block the control target within a range that satisfies the required control amount Control pattern determining means for calculating the optimum power flow online so as to select an optimal control pattern that optimizes the economic efficiency associated with the control from the patterns. Then, the power system is controlled and stabilized according to the selected optimum control pattern.

The power system stabilization control method according to the present invention includes a first step of detecting an occurrence of an accident in the power system from system information, and a generator to be controlled based on the system information after the occurrence of the accident is detected. The second step of calculating the required control amount online so as to maintain the transient stability with respect to the load , and the control pattern from among a plurality of control patterns that block the control target within a range that satisfies the required control amount. a third step of economic efficiency is computed online an optimal power flow so as to select an optimum control pattern for the optimization associated with the fourth to stabilize by controlling the electric power system according to the optimal control pattern is the selected The steps are provided.

  In such power system stabilization control, it is possible to quickly perform appropriate stabilization control in accordance with accident conditions and system conditions, and to select an optimal control pattern that optimizes the economic efficiency associated with the control. By performing the optimum power flow calculation, it is possible to easily and surely determine the optimal control pattern of economic efficiency, and it is possible to carry out stable control and system operation with good economic efficiency.

Embodiment 1 FIG.
Hereinafter, a power system stabilization control method according to Embodiment 1 of the present invention and a power system stabilization control apparatus to which the control method is applied will be described.
1 is a diagram showing a configuration of a power system stabilization control device and a protection target system (hereinafter referred to as a protection system) according to Embodiment 1 of the present invention.
As shown in the figure, the protection system is connected to the main bus 1E on the main system side by the interconnection 2D, and the buses 1A to 1D, the power transmission lines 2A to 2C, the circuit breakers 3A to 3H, and the generator 8A to the on-line measurement 8C and load 9 are provided. The power system stabilization control device 10 (hereinafter referred to as the system stabilization device 10) includes sensors (current transformers) 4A to 4D for capturing transmission line currents, and sensors (transformer) for capturing bus voltage. 5A, 5B, input cables 6A-6F for capturing circuit breaker information and current / voltage, output cables 7A, 7B for outputting output signals for power limit (shut off) and load limit (shut off), and transmission line 2A 2B or the buses 1A and 1D, the generators 8A to 8C or the load 9 are cut off to maintain the transient stability in the protection system.

Next, the operation will be described below based on the flowchart shown in FIG.
First, in step ST1, the system stabilizing device 10 collects various amounts (hereinafter referred to as system information) that are measured in each part of the protection system at a normal time, for example, at a constant period. For example, by calculating the power flow value flowing in the transmission lines 2A and 2B from the current and voltage as system information input by the input cables 6A and 6B through the sensors 4A to 4C and 5A, the controlled generator output is calculated. The value of the load 9 is calculated from the current and voltage as the system information input by the input cables 6E and 6F, and the system information from the central power supply command station (not shown) is also collected so that the optimum power flow calculation described later can be performed. Waiting at.

Next, in step ST2, occurrence of an accident in the power system is detected from the input system information. For example, when a ground fault occurs in the power transmission line 2A, the occurrence of an accident is determined by detecting that the voltage of the bus 1B suddenly changes below a predetermined value. The operation here is performed by an accident occurrence detection means (not shown) which is an arithmetic function that the system stabilizing device 10 has.
Next, in step ST3, the transient stability in the protection system is quantitatively calculated by, for example, a known calculation using the energy method from the system information that is measured and input online after the occurrence of the accident. Calculate the amount online.
Next, in step ST4, on the assumption that a control pattern by a combination of controls is satisfied so as to satisfy the calculated control amount for the controlled object, optimal power flow calculation is performed online, and optimal control that minimizes economic loss is performed. Select a pattern. The operation here is performed by a control pattern determining means (not shown) which is an arithmetic function included in the system stabilizing device 10. The optimum power flow calculation will be described in detail in a second embodiment to be described later.
Next, in step ST5, the selected optimal control pattern, that is, the combination control that minimizes the economic loss is performed by outputting a cutoff signal through an output cable, for example.
And in step ST6, a series of processing of the system stabilization device 10 after the occurrence of the accident is stopped and returned to a steady state.

  As described above, in this embodiment, when an accident occurrence is detected from the grid information, the control pattern that minimizes the economic loss is calculated by calculating the necessary control amount from the grid information measured online and using the optimum power flow calculation. Can be promptly determined by online processing. For this reason, it is possible to perform stable control with good economic efficiency that flexibly corresponds to the state of the accident.

Embodiment 2. FIG.
With respect to the first embodiment, details of the stabilization control including the optimum power flow calculation process will be described below, taking as an example a case where a ground fault has occurred in the transmission line 2A.
FIG. 3 is a flowchart showing the operation of system stabilization control according to the second embodiment.
First, in step ST1, as described above, the system stabilizing device 10 flows from the current and voltage as system information input by the input cables 6A and 6B to the power transmission lines 2A and 2B through the sensors 4A to 4C and 5A. The power flow value is calculated to calculate the output of the generator to be controlled, the value of the load 9 is calculated from the current and voltage as system information input by the input cables 6E and 6F, and from the central power supply command station (not shown) The system information is also collected, and it waits in a state where the optimum power flow calculation described later is possible.
Next, in step ST2, when a ground fault occurs in the power transmission line 2A, it is determined that the accident has occurred by detecting that the voltage of the bus 1B suddenly changes to a predetermined value or less.

Next, in step ST3, the transient stability index of the generator to be controlled is calculated by, for example, a known calculation using the energy method from the system information measured and input online after the accident occurs, and the necessary control amount Calculate the required power limit amount
Next, in step ST4, it is determined whether or not the transient stability is within an allowable range without control, based on the necessary power supply limit amount calculated in step ST3. If the stability is within the allowable range, the process proceeds to step ST7, and if not, the process proceeds to step ST5.

Next, in step ST5, an optimal control pattern of economic efficiency is selected using optimal power flow calculation which is an online calculation process. Here, first, a control pattern is assumed in which the control amount (cutoff amount) is equal to or greater than the necessary power limit amount calculated in step ST3. Specifically, a control pattern (blocking pattern) having a blocking amount of any one of the generators 8A to 8C or a combination thereof is assumed. Then, for each of a plurality of assumed control patterns, the tidal current calculation is performed assuming that the control is performed, and the economic efficiency is optimized by selecting the control pattern with the lowest economic loss as the optimal control pattern. .
Note that the tidal current calculation performed by this optimum tidal current calculation is a simple tidal current calculation based on the DC method tidal current calculation.
The optimal power flow calculation is performed, for example, by the following calculation process.
The objective function at this time can be expressed as follows.

また、式（１）の目的関数の最小値を求める際に、以下のような制約条件を想定することができる。

Further, when obtaining the minimum value of the objective function of Expression (1), the following constraint conditions can be assumed.

Within the constraints, the supply and demand balance equation (2) can be calculated by the DC method, ignoring transmission loss, and the objective function, which is the power generation cost, can be instantly optimized using linear programming. To.
In this case, the following calculation is performed so as to select a combination of controls that is equal to or greater than the necessary power supply limit calculated in step ST3 and that minimizes economic loss before and after the control. That is, by calculating the power generation maximum value (Gmaxi) of the generator to be controlled in Expression (3) as zero, the power generation distribution and the total power generation cost when the power generator is shut off are calculated, and the above-mentioned For each of a plurality of assumed control patterns, a simple DC method power flow calculation is sequentially repeated for the combination of generators to be cut off, and a control pattern that minimizes economic loss is selected.
Although the objective function is the total power generation cost here, other costs may be considered.
In addition, the power generation cost of each generator and the capacity of each transmission line used for the optimum power flow calculation are taken from the central power supply command station.

Next, in step ST6, the optimal control pattern selected in step ST5, that is, the control of the combination that minimizes the economic loss is performed by, for example, outputting a cutoff signal through an output cable.
And in step ST7, a series of processes of the system stabilization apparatus 10 after the occurrence of an accident are stopped, and it returns to a steady state.

  As described above, by using the optimum power flow calculation, the control pattern that minimizes the economic loss can be quickly and reliably determined by online processing. Moreover, since simple power flow calculation is performed by DC method power flow calculation, it is possible to realize a stabilization control that is easy to calculate and can respond quickly to the occurrence of an accident.

Embodiment 3 FIG.
Next, the case where overload control is performed due to the occurrence of an accident will be described based on the flowchart of FIG. The configurations of the system stabilizing device 10 and the protection system are the same as those in FIG.
First, in step ST1, the system stabilizing device 10 collects system information at a normal time, for example, at a constant cycle. For example, by calculating the power flow value flowing in the transmission lines 2A and 2B from the current and voltage as system information input by the input cables 6A and 6B through the sensors 4A to 4C and 5A, the controlled generator output is calculated. The value of the load 9 is calculated from the current and voltage as the system information input by the input cables 6E and 6F, and the system information from the central power supply command station (not shown) is also collected so that the optimum power flow calculation described later can be performed. Waiting at.

Next, in step ST2, occurrence of an accident in the power system is detected from the input system information.
Next, in step ST3, tidal current calculation reflecting the state of the accident that occurred is performed from the system information measured and input online after the accident occurs, and the tidal current value after the accident on each line in the protection system is calculated online. calculate.
Next, in step ST4, the power flow value after the accident of each line calculated in step ST3 is collated with the capacity of each line, and it is determined whether there is a line that is overloaded by the accident. If an overload line exists, the process proceeds to step ST5, and if not, the process proceeds to step ST7.

  Next, in step ST5, an optimal control pattern of economic efficiency is selected using optimal power flow calculation which is an online calculation process. Here, first, the optimal tidal current calculation is performed by the DC method tidal current calculation so that the economic loss is minimized by using the tidal current diversion coefficient, and the power generation state in which the tidal current value of the overloaded line is below the specified value is set. Calculate. At this time, if the overload can be eliminated only by the shutoff control of the generator, the control pattern (optimum control pattern) based on the optimum power flow calculation result is determined. Further, when it is not possible to cope with only the generator cutoff control, the optimum power flow calculation is performed in advance assuming a control pattern combined with the load cutoff control. That is, for each of a plurality of assumed control patterns, the power flow calculation is performed assuming that the control is performed, and the control pattern with the lowest economic loss is selected as the optimal control pattern. Furthermore, for example, when the generator type that cannot limit the output at high speed is not possible, the optimal power flow calculation assuming that the generator is shut off more than the calculated limit amount is performed. A control pattern with low economic loss is selected as the optimal control pattern. It should be noted that the load shedding control pattern is used as a table in advance.

Next, in step ST6, the optimal control pattern selected in step ST5, that is, the control of the combination that minimizes the economic loss is performed by, for example, outputting a cutoff signal through an output cable.
And in step ST7, a series of processes of the system stabilization apparatus 10 after the occurrence of an accident are stopped, and it returns to a steady state.

  As described above, by using the optimum power flow calculation, the control pattern that minimizes the economic loss can be quickly and reliably determined by online processing. Moreover, since the overload is eliminated by the optimum power flow calculation reflecting the state after the accident, the overload control with the minimum economic loss can be realized.

Embodiment 4 FIG.
Next, stabilization control against an unexpected increase in power demand such as a natural increase in load will be described based on the flowchart of FIG. The configurations of the system stabilizing device 10 and the protection system are the same as those in FIG.
First, in step ST2, the system stabilization device 10 activated in step ST1 performs power flow calculation based on the system information captured at a constant period, and calculates the power flow value of each line or transformer in the protection system. .
Next, in step ST3, each power flow value calculated in step ST2 is collated with each specified value (operational value less than or equal to the rated capacity value), and there is a transmission line or a transformer whose power flow value exceeds the specified value. Determine whether or not. If it exists, the process proceeds to step ST4. If not, the process proceeds to step ST6. Note that the operation here, that is, the operation of monitoring the power flow value of each line or transformer in the protection system and detecting the increase in power demand due to the fluctuation of the power flow value is an operation that the system stabilization device 10 has inside. This is performed by power demand increase detection detecting means (not shown) which is a function.

  Next, in step ST4, an optimal control pattern for economic efficiency is selected using optimal power flow calculation, which is an online calculation process. Here, first, the optimum power flow calculation is performed assuming in advance a control pattern based on system change control that does not involve interruption such as opening of a line or switching of a bus. That is, the tidal current calculation is performed using the line tidal current diversion coefficient that is assumed to be controlled for each of a plurality of assumed control patterns, and the control pattern with the lowest economic loss is selected as the optimum control pattern. The operation here is performed by a control pattern determining means (not shown) which is an arithmetic function included in the system stabilizing device 10.

Next, in step ST5, the optimum control pattern selected in step ST4, that is, the system change control that minimizes the economic loss and the system operation alarm are transmitted as a system change command to the central power supply command station. The transmission of the system change command is performed by a system change command generating means (not shown) of the system stabilizing device 10. Note that the actual system change control is performed again by determining whether or not the central power supply command station performs.
In step ST6, while the central power supply command station performs the system change control and confirms it, the processing of the system stabilization device 10 is stopped.

  As described above, in this embodiment, an increase in power demand is detected from the grid information, and the system change control without interruption for overload cancellation is performed using the optimal power flow calculation, thereby minimizing economic loss. It can be determined promptly by online processing. Therefore, it is possible to perform stable control with good economic efficiency that flexibly corresponds to the system state. In addition, overload monitoring control of each part of the system can be performed efficiently with minimum economic loss.

It is a figure which shows the structure of the electric power system stabilization control apparatus and protection system by Embodiment 1 of this invention. It is a flowchart which shows the electric power system stabilization control method by Embodiment 1 of this invention. It is a flowchart which shows the electric power system stabilization control method by Embodiment 2 of this invention. It is a flowchart which shows the electric power system stabilization control method by Embodiment 3 of this invention. It is a flowchart which shows the electric power system stabilization control method by Embodiment 4 of this invention.

Explanation of symbols

  8A to 8C generator, 9 load, 10 power system stabilization control device.

Claims (7)

When a disturbance occurs in the power system, in the power system stabilization control device that stabilizes the power system by performing appropriate control on the power system, the above-described amounts are measured from various quantities (hereinafter referred to as system information) measured in each part of the power system. Based on the means to detect the occurrence of an accident in the power system and the above system information after the occurrence of the accident , the required control amount is calculated online to maintain the transient stability for the generator or load to be controlled. And an optimal power flow calculation so as to select an optimal control pattern that optimizes the economic efficiency associated with the control from among a plurality of control patterns that block the control target within a range that satisfies the required control amount. A power system stabilization control apparatus comprising: a control pattern determining means for calculating, and controlling and stabilizing the power system according to the selected optimal control pattern. When a disturbance occurs in the power system, in the power system stabilization control device that stabilizes the power system by performing appropriate control on the power system, the above-described amounts are measured from various quantities (hereinafter referred to as system information) measured in each part of the power system. Based on the means for detecting an increase in power demand in the power system and the system information after detection of the increase in power demand, the economic efficiency associated with the control is optimal from among a plurality of control patterns of assumed system change. Control pattern determining means for calculating optimal power flow calculation online so as to select an optimal control pattern, and means for generating a system change command for the power system according to the selected optimal control pattern Power system stabilization control device. When a disturbance occurs in the power system, in the power system stabilization control method for performing stabilization by performing appropriate control on the power system, the above-mentioned amounts are measured from various quantities (hereinafter referred to as system information) measured in each part of the power system. Based on the first step of detecting the occurrence of an accident in the power system and the above-described system information after the occurrence of the accident , the necessary control amount is set so as to maintain the transient stability for the generator or load to be controlled. An optimal control pattern that optimizes the economic efficiency associated with the control is selected from the second step of calculating online and a plurality of control patterns that block the control target within a range that satisfies the required control amount. a third step of calculating an optimal power flow calculations online, and further comprising a fourth step of stabilization by controlling the electric power system according to the optimal control pattern is the selected Power system stabilizing control how. In the second step, on the basis of the system information after the occurrence of an accident is detected, a transient stability index of the generator to be controlled is calculated, the required control amount for the generator is obtained online, and then the third In the optimal power flow calculation in the step, the power flow calculation assuming the control is performed for each of the plurality of control patterns assumed to shut off the generator at the required control amount or more, and the optimal control pattern is selected. The power system stabilization control method according to claim 3. In the second step, based on the system information after the occurrence of an accident is detected, a tidal current value of each part of the system is calculated by tidal current calculation to detect an overload part, and the tidal current value of each part of the system is within regulation calculated online amount as the required controlled variable, in the above optimal power flow in the third step, the upper Symbol controlled subject to a generator or load the required controlled variable assumed to block a range that satisfies the above plurality of The power system stabilization control method according to claim 3, wherein a power flow calculation assuming the control is performed for each control pattern, and the optimum control pattern is selected. In a power system stabilization control method in which when a disturbance occurs in the power system, the power system is stabilized by performing appropriate control on the power system, based on various amounts measured by each part of the power system (hereinafter referred to as system information). To calculate the power flow, monitor the power flow value of each part of the system, detect the increase in power demand based on the power flow value, and based on the system information after detecting the power demand increase, The optimal tidal current calculation is performed online so that the optimal control pattern that optimizes the economic efficiency associated with the control is selected from a plurality of system change control patterns assumed so that the tidal current value is within the specified range. And a third step of generating a system change command for the power system according to the selected optimal control pattern. The power system stabilization control method according to any one of claims 3 to 6, wherein the optimum power flow calculation in the second step is performed by using a DC method power flow calculation.

Images