JP2003111274A - Transmission threshold calculation method for power system, and computer readable recording medium recorded with transmission threshold calculation program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the problem in a prior art that a transmission threshold can be obtained if detailed stability calculations are repeatedly executed for obtaining the transmission threshold of a power system, but it cannot quickly be obtained as it takes long hours to complete the calculation of the detailed stability. SOLUTION: The detailed stability calculation and a stability discrimination are concurrently executed, and the stability discrimination includes five processes of calculations of an excessive load discrimination, a power stability discrimination, frequency limitation, a transient stability discrimination, and a movement stability discrimination. The detailed stability calculation and the stability discrimination are interrupted when stability or instability is determined and, when the discrimination result shows the stability discrimination to be stable, the amount of the transmission is increased, to concurrently re-execute the detailed stability calculation and the stability discrimination. Also, when the result shows the stability discrimination to be unstable, a transmission amount immediately before being unstable is presumed as the transmission threshold.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transmission limit calculation method and a transmission limit calculation program for reducing a calculation amount and improving accuracy when calculating a transmission limit value of a power system including a generator and a load. The present invention relates to a computer-readable recording medium in which is recorded.

[0002]

2. Description of the Related Art FIG. 8 is a flowchart showing a conventional power transmission limit calculation method. In the figure, STl is a step for creating data necessary for detailed stability calculation, and ST2 is ST.
The step of executing the detailed stability calculation using the data created in l, ST3 is the step of analyzing the calculation result of the detailed stability calculation, ST4 is the step of judging whether or not the power system is stable, and ST5. Is a step of increasing the power transmission amount when the power system is stable, and ST6 is a step of recognizing the power transmission amount immediately before the power system becomes unstable as the power transmission limit value when the power system is unstable. Next, the operation will be described. When calculating the power transmission limit value, first, data required for the detailed stability calculation is created (ST1), and the detailed stability calculation is executed using the data (ST2). Then, the calculation result of the detailed stability calculation is analyzed (ST
3) Determine whether the power system is stable (ST
4). When the power system is stable, the amount of power transmission is increased by increasing the value of a specific generator or load (ST5), and the above detailed stability calculation is re-executed. On the other hand, when the power system becomes unstable, the amount of power transmitted immediately before the power system becomes unstable is recognized as the power transmission limit value (ST6).

[0003]

Since the conventional power transmission limit calculation method uses the above-mentioned method, the power transmission limit value can be obtained by repeatedly executing the detailed stability calculation. Since the stability calculation is repeatedly performed until it is calculated, the calculation takes a long time and the calculation cost is high. The present invention has been made in order to solve the above problems, and establishes a method capable of shortening the calculation time and accurately calculating the power transmission limit and reading by a computer in which the power transmission limit calculation program is recorded. The aim is to obtain a feasible recording medium.

[0004]

A transmission limit calculation method according to the present invention comprises a first calculation for determining overload, a second calculation for determining voltage stability, and a third calculation for frequency limit. , The fourth calculation for determining the transient stability, and the fifth calculation for determining the dynamic stability are performed in parallel with the detailed stability calculation. When it is determined that the power system is stable or unstable in the first to fifth calculations, the detailed stability calculation and the execution of the stability determination are stopped, and if stable, the power transmission amount is increased. When the stability is determined by executing the detailed stability calculation and the first to fifth calculations again, and the stability is determined, the amount of power transmission immediately before becoming unstable is set as the power transmission limit value.

Further, there is provided a method for determining the dynamic stability of the power system after an accident, which comprises the following steps (1) to (4). (1) A step of allocating the power flow value at the accident point by the ratio of the rated capacities of the plurality of generators operating in the system. (2) A step of obtaining the center of inertia δ center of the system from the inertia constant and the phase angle of each generator of the system. (3) A generator group having a phase angle larger than the δ center is set as an acceleration side group, a generator group having a small phase angle is set as a deceleration side group, and the two groups of generators of the acceleration side group and the deceleration side group are contracted. And obtaining the respective phase angles δ ₁ and δ ₂ . (4) The difference δ between δ ₁ and δ ₂ is the phase angle of one equivalent machine,
This phase angle δ is compared with a preset threshold value δsh, and δ
A step of determining unstable if> δsh and stable if δ <δsh.

A method for determining the dynamic stability of the electric power system after an accident has the following steps (1) to (5). (1) A step of monitoring the phase angle δe of each generator. (2) A step of obtaining the phase angle δemax of the most accelerated generator and the phase angle δemin of the least accelerated generator among the phase angles δe of the generators. (3) A step of calculating the phase angle δ of one equivalent aircraft from immediately after the occurrence of the accident to the time of determination at the timing when the difference between δemax and δemin is maximum. (4) At least 3 points for the highest point and the lowest point of the phase angle δ.
A step of obtaining a total of 6 points for each point, calculating the difference between the highest point and the lowest point, and confirming the divergence tendency of the phase angle. (5) A step of discriminating that the divergence tendency is unstable and the convergence tendency is stable.

In addition, there is a method of performing the following steps (1) and (2) for determining the stability from the frequency limit when the power system is separated after the occurrence of the accident. (1) The total power generation amount P _G and the total load amount P _L in each grid are calculated, and the frequency deviation ΔF ₁ within the governor-free region and the frequency deviation ΔF outside the governor-free region are calculated from the following equations (1) and (2). _Two
Calculating step.

[Equation 5]

[Equation 6] (2) A step of determining that the calculated frequency deviation ΔF of each system is stable if it is within a preset allowable range, and unstable if it is outside the allowable range.

Further, when the power transmission limit amount is recognized, a detailed stability calculation is executed to confirm and confirm its validity.

A computer-readable recording medium in which the transmission limit calculation program according to the present invention is recorded includes a detailed stability calculation procedure and a stability determination processing procedure for performing stability determination in parallel. The degree determination processing procedure includes a first calculation for determining an overload, a second calculation for determining a voltage stability, a third calculation for calculating a frequency limit, and a fourth calculation for determining a transient stability. And the fifth calculation for determining the dynamic stability, the first
~ When the power system is determined to be stable or unstable in the fifth calculation result, the execution of the detailed stability calculation and the stability determination is stopped, and when the power system is determined to be stable, power transmission is performed. When the detailed stability calculation and the stability determination are performed again by increasing the amount, and if it is determined to be unstable, the transmission limit value qualification processing procedure in which the transmission amount immediately before becoming unstable becomes the transmission limit value It is equipped with and.

A computer-readable recording medium in which the program for determining the dynamic stability of the power system after the accident according to the present invention is recorded has the following steps. (1) A step of calculating the sum of the rated capacities of each of the generators operating in the grid and distributing the power flow value at the accident point by the ratio of the rated capacities of the generators. (2) A step of obtaining the center of inertia δ center of the system from the inertia constant and the phase angle of each generator of the system. (3) Comparing the δ center with the phase angle of each generator, the generator group having a phase angle larger than the δ center is the acceleration side group, and the generator group having a small phase angle is the deceleration side group, The phase angles δ ₁ and δ of the two groups of generators of the acceleration side group and the deceleration side group are reduced.
₂ and the step to ask. (4) The difference δ between δ ₁ and δ ₂ is the phase angle of one equivalent machine,
This phase angle δ is compared with a preset threshold value δsh, and δ
A step of determining unstable if> δsh and stable if δ <δsh.

A computer-readable recording medium in which a program for determining the dynamic stability of an electric power system after an accident according to the present invention is recorded has the following steps. (1) A step of monitoring the phase angle δe of each generator. (2) A step of obtaining the phase angle δemax of the most accelerated generator and the phase angle δemin of the least accelerated generator among the phase angles δe of the generators. (3) A step of calculating the phase angle δ of one equivalent aircraft from immediately after the occurrence of the accident to the time of determination at the timing when the difference between δemax and δemin is maximum. (4) At least 3 points for the highest point and the lowest point of the phase angle δ.
A step of obtaining 6 points in total and calculating the difference between the highest point and the lowest point to confirm the divergence tendency of the phase angle. (5) A step of determining that the difference between the highest point and the lowest point is unstable if the difference is divergent and stable if the difference is convergent.

Further, a computer-readable recording medium according to the present invention, in which a stability determination program from a frequency limit when the power system after the accident has been separated, is recorded, has the following steps. . (1) The total power generation amount P _G and the total load amount P _L in each grid are calculated, and the frequency deviation ΔF ₁ within the governor-free region and the frequency deviation ΔF outside the governor-free region are calculated from the following equations (1) and (2). _Two
Calculating step.

[Equation 7]

[Equation 8] (2) A step of determining that the calculated frequency deviation ΔF of each system is stable if it is within a preset allowable range, and unstable if it is outside the allowable range.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiment 1. Hereinafter, a method of calculating a transmission limit of an electric power system according to Embodiment 1 of the present invention will be described with reference to the drawings. FIG. 1 is a configuration diagram of a power transmission limit calculation tool based on the power transmission limit calculation method of the present invention for the purpose of helping understanding of the present invention. FIG. 2 is a flowchart of the power transmission limit calculation method. In FIG. 2, in ST1, data necessary for executing the detailed stable calculation is created according to the preset condition. The short-circuit current is calculated in ST2, the detailed stability calculation result is constantly monitored in ST3, and the first calculation for overload determination, the second calculation for voltage stability determination, the third calculation for frequency limit calculation, and the transient calculation are made. The fourth calculation for stability determination, the fifth calculation for dynamic stability determination and various calculations are executed, and the stability of the power system is determined from the calculation result in ST4. When it is determined to be stable or unstable in the determination in ST4, the execution of the detailed stability calculation and the calculation of the stability determination is stopped. In ST5, the first to third ST3 discriminated in ST4.
When it is determined that the fifth calculation results are stable, the stable generator output and load values, that is, the amount of power transmission are sequentially increased, the first to fifth calculations of ST3 are performed again, and the stability of ST4 is achieved. , To determine instability. If it is determined to be unstable, the amount of power transmission immediately before being determined to be unstable is set as the power transmission limit value.
As described above, according to the first embodiment of the present invention, at the same time as the detailed stability calculation of the power system is performed, the first calculation for overload determination, the second calculation for voltage stability determination, and the first calculation for frequency limit calculation are performed. 3), 4th calculation of transient stability determination, and 5th calculation of dynamic stability determination are performed to perform stability determination, and detailed stability calculation is performed when the determination result is determined to be stable or unstable. Since the stability judgment calculation is stopped forcibly and the stability judgment calculation is also stopped, the stability judgment result can be obtained and the transmission limit value can be obtained before the calculation of the detailed stability calculation. The power transmission limit value can be promptly obtained while shortening appropriately, and the power transmission limit value in consideration of each stability can be calculated. Note that FIG. 1 is also an explanatory diagram showing a construction example of a program for executing the power transmission limit calculation method, and this program (a power transmission including a stability calculation processing procedure, a stability determination processing procedure, and a power transmission limit value qualification processing procedure). Limit calculation program) is a computer-readable hard disk or CDR
It shall be recorded on a computer-readable recording medium such as OM. Further, the power transmission limit calculation method according to the first embodiment is not limited to the case where the power system is operating stably, and the power transmission limit calculation method is used when an accident such as a lightning strike occurs in the power system. ,
It is more effective.

Embodiment 2. In the second embodiment, the dynamic stability which is the fifth calculation adopted in the stability determination of the first embodiment is taken up, and the stability of the power system after the accident occurs is discriminated from the aspect of the dynamic stability. It is related to. FIG. 3 is a flowchart of a method of calculating the power transmission limit from the aspect of dynamic stability. In the figure, in STl, the power flow before the accident is calculated, and the power flow state before the accident is calculated. In ST2, a search for a system separated by opening the accident point due to the accident is carried out. In ST3 and ST4, when the system is separated, the system after each accident is created depending on the case where the system is not separated. In ST5, power flow calculation is performed using the post-accident system created in ST3 and ST4 to calculate the power flow state after the accident. In ST6, the phase angle δ of one equivalent aircraft is calculated from the power flow state after the accident, and in ST7, the phase angle δ is calculated.
Then, the stability determination of the power system is performed by comparing with a preset threshold value Δsh. Next, a system creation portion after an accident when the systems are separated in ST3 and ST4 shown in FIG. 3 will be described. When the power system is separated by opening the accident point due to an accident, the power unbalance occurs in the system. In this case, it is considered that the imbalance will be absorbed by a governor-free generator, etc., so (3)
From the formula, calculate the total of the rated capacity ( _GMVA ) of the remaining generators in the system after separation, and calculate the power flow value ΔP at the accident point from (4)
As shown in the equation, P _i ′ is distributed to each generator at the ratio of the rated capacity.

[0015]

[Equation 9]

[Equation 10]

If the system is not separated by opening the accident point due to the accident, no power imbalance occurs in the system after the accident, so the line at the accident point to be opened is deleted. Next, a description will be given of a portion for determining the stability of the power system by calculating the phase angle δ of one equivalent machine from the power flow state after the accident in ST6 and ST7 of FIG. The center of inertia of the system is calculated using the following equation (5) from the power flow calculation result after the accident in ST5.

[0017]

[Equation 11]

Next, the phase angle δi of each generator and the center of inertia δ center are compared, and the generator group having a larger δ than the δ center is set as the acceleration side group, and the small generator group is set as the deceleration side group. From equations (6) to (7), reduce to an equivalent generator.

[0019]

[Equation 12]

[Equation 13]

From the above equations (6) to (7), the two-machine system is reduced to a one-machine system which is equivalent in stability. Then, S shown in FIG.
At T7, the difference δ between the phase angle δ ₁ of each generator of the acceleration side group and the phase angle δ ₂ of the deceleration side group obtained by the equation (7), that is, the equivalent phase angle δ of one machine is set in advance. It is judged to be unstable if the threshold value δsh is exceeded, and stable if δsh or less. As described above, according to the second embodiment of the present invention, it is possible to perform system stability determination from the aspect of dynamic stability after a power system accident occurs, and as a result of this stability determination, it is determined that the system is stable. In such a case, the detailed stable calculation, which consumes a large amount of cost and calculation time, is started, but it is unnecessary, and the stability determination can be performed easily and at low cost.

Embodiment 3. In the third embodiment, a method of performing more detailed stability determination of the dynamic stability will be described for the case in which the stability is determined to be unstable in ST7 shown in FIG. 3 of the second embodiment. To do.
FIG. 4 is a flowchart thereof. In the figure, ST
In 1 and ST2, the internal phase angle δ of all generators in the system is monitored, and the timing at which the difference between δ of the most accelerated generator and δ of the least accelerated is calculated is calculated. ST3,
In ST4 and ST5, it is reduced to one equivalent machine at the timing calculated in ST2, and stability determination is performed from the internal phase angle δ of the equivalent one machine. Next, equivalent 1 of ST3, ST4 and ST5 in FIG.
The method for determining the stability of the dynamic stability from the phase angle δ of the machine will be described in detail. Embodiment 2 at the timing when the difference between δ of the most accelerated generator and δ of the least accelerated is largest among the phase angles δ of all the generators in the system calculated in ST1 and ST2. By the same method as described in 1., the equivalent one-machine system is contracted, and the phase angle δ of the equivalent one-machine system from the time immediately after the occurrence of the accident until the time of determination is calculated. The highest point and the lowest point of the phase angle δ of the equivalent one-machine system from the time immediately after the occurrence of the calculated accident to the present time are calculated. Lowest point difference D _P1 ~ D
_P3 is calculated and the divergence tendency of the phase angle δ of the equivalent one-machine system is confirmed. As shown in FIG. 5, if the difference between the highest point and the lowest point gradually widens, it is determined to be unstable, and if it narrows, it is determined to be stable.
As described above, according to the third embodiment of the present invention, the stability determination of the system after the occurrence of the power system accident can be confirmed by a more detailed calculation method from the viewpoint of dynamic stability. If it is determined to be stable, cost and calculation time can be reduced without depending on the detailed stable calculation.

Fourth Embodiment In the fourth embodiment, a method of calculating the power transmission limit viewed from the side of the frequency when grid separation occurs due to an accident that occurs in the power grid will be described with reference to FIGS. 6 and 7. FIG. 6 is a flowchart of a method of calculating the power transmission limit viewed from the side of the frequency when the grid separation occurs. In STl, a search for a system separated by opening the accident point due to an accident is carried out. S
In T2 and ST3, when the system separation occurs, the frequency for each system is calculated and the stability is determined. Next, S in FIG.
A method of calculating the frequency for each system and performing the stability determination when the system separation of T2 and ST3 occurs will be described in detail. The total power generation amount P _G and the total load amount P _L in each system are calculated, and the frequency deviation ΔF ₁ within the governor-free region and the frequency deviation Δ outside the governor-free region are calculated from the following equations (1) and (2).
Calculate F ₂ .

[0023]

[Equation 14]

[Equation 15]

Assuming that the output increase of the governor-free generator is up to the governor-free capacity and the output decrease is not limited, the frequency ΔF of each system has the characteristics shown in FIG. 7, and the frequency deviation is within the governor-free region. The frequency deviation ΔF ₁ and the frequency deviation ΔF ₂ outside the governor-free region have smaller values. Whether or not the calculated ΔF of the system deviates from a preset allowable range (ΔFmin ≦ ΔF ≦ ΔFmax) is used to make a stability determination. If ΔF is within the allowable range, the stability is determined. Judge as unstable. As described above, according to the fourth embodiment of the present invention, the stability determination of the power system after the occurrence of the accident can be performed from the side of the frequency without performing the detailed stability calculation. .

[0025]

As described above, according to the present invention, there is provided a power transmission limit calculation method in which detailed stability calculation and stability determination are performed in parallel, and the determination of stability includes overload determination and voltage stability. It has the contents to perform discrimination, frequency limit, transient stability, and dynamic stability and five calculations. When the stability is determined by the above calculation, the execution of detailed stability and stability determination is stopped. If it is determined to be stable, the amount of power transmission is increased, detailed stability calculation and stability determination are performed again, and if it is determined to be unstable, the amount of power transmission immediately before that is set as the transmission limit value. Therefore, it is possible to quickly obtain the transmission limit value,
It has an excellent effect of saving calculation time and cost.

Further, the determination of the dynamic stability of the electric power system after the accident occurs is (1) the power flow value at the accident point is distributed by the rated capacity ratio of each generator, and (2) the center of inertia δ center of the system is obtained,
(3) Compare the δ center with the phase angle of each generator, reduce the generators into two groups, the acceleration side and the deceleration side, and obtain the respective phase angles δ ₁ and δ _2, and (4) δ A step of determining that the difference δ between ₁ and δ ₂ is the phase angle of one equivalent machine and comparing this phase angle δ with a preset threshold value δsh to be unstable if δ> δsh and stable if δ <δsh Since it is provided, the stability can be easily determined without depending on the detailed stability calculation, and the cost can be reduced.

Similarly, the determination of the dynamic stability of the electric power system after the accident occurs is (1) monitoring the phase angle δe, and (2) the phase angle δemax of the most accelerated generator and the least accelerated. Calculate the phase angle δemin of the generator, and (3) Phase angle δ = δemax-δemin of one equivalent machine from immediately after the accident occurs until the time of discrimination
Ask for. (4) The highest point and the lowest point of the phase angle δ are 6 in total.
Since the divergence tendency of the phase angle is confirmed from the point-obtained difference and (5) it is provided with the step of determining that the divergence tendency is unstable and the converging tendency is stable, the same effect as described above is obtained.

Similarly, after the accident, the stability determination from the frequency limit when the power system is separated is performed by (1) the frequency deviation ΔF ₁ within the governor free region and the frequency deviation ΔF ₂ outside the governor free region. The step of calculating (2) determining that the calculated frequency deviation ΔF of each system is stable if the frequency deviation ΔF is within a preset allowable range and unstable if the calculated frequency deviation ΔF deviates from the range is provided. Play.

Further, according to the present invention, the storage medium is recorded with a transmission limit calculation program for performing the detailed stability calculation procedure and the stability determination procedure in parallel, and the overload determination is used to determine the stability. , Voltage stability determination, frequency limit, transient stability, dynamic stability determination and five calculations are performed, and detailed stability and stability determination are performed at the time when the stability determination is made in the above calculation. If the execution is stopped and it is determined to be stable, the power transmission amount is increased and the detailed stability calculation and stability determination are performed again.If it is determined to be unstable, the power transmission amount immediately before that is set as the transmission limit value. Since it is equipped with a transmission limit value qualification processing procedure that enables the transmission limit value to be quickly obtained,
It has an excellent effect of saving calculation time and cost.

Further, the determination of the dynamic stability of the power system after the accident occurs (1) The power flow value is distributed by the rated capacity ratio of each generator, (2) the center of inertia δ center of the system is obtained, and (3) Compare the δ center and the phase angle of each generator,
It is reduced to two groups on the deceleration side, the respective phase angles δ ₁ and δ ₂ are obtained, and (4) the difference δ between δ ₁ and δ _{2 is taken} as the phase angle of one equivalent machine, and this phase angle δ and preset The threshold value δsh is compared, and if δ> δsh, it is unstable, and if δ <δsh, it is stable. Since it is a recording medium, by using it, the stability can be easily discriminated without depending on the detailed stability calculation, and the cost can be reduced.

Similarly, (1) the phase angle δe is monitored,
(2) Obtain the phase angle δemax of the most accelerated generator and the phase angle δemin of the least accelerated generator, and (3) Equivalent phase angle δ = δem from immediately after the occurrence of the accident until the time of discrimination.
Calculate ax−δemin. (4) A total of 6 points of the highest point and the lowest point of the phase angle δ are obtained, and the divergence tendency of the phase angle is confirmed from the difference. Since it is a computer-readable recording medium in which the dynamic stability determination program of the electric power system after the occurrence of the accident, which includes the step of, is recorded, the same effect as described above can be obtained by using the recording medium.

Similarly, (1) the frequency deviation ΔF ₁ within the governor-free area and the frequency deviation ΔF outside the governor-free area.
F ₂ is calculated, and (2) the calculated frequency deviation ΔF of each system
Is stable if it is within the allowable range set in advance, and unstable if it is out of the range.A stability determination program from the frequency limit when the power system after the accident is separated is provided Since it is a recorded computer-readable recording medium, the same effects as described above can be obtained.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a power transmission limit calculation tool shown for the purpose of helping understanding of Embodiments 1 to 4 of the present invention.

FIG. 2 is a flowchart of a power transmission limit calculation method according to the first embodiment of the present invention.

FIG. 3 is a flowchart diagram for performing stability determination from the aspect of dynamic stability according to the second embodiment of the present invention.

FIG. 4 is a flowchart for performing stability determination from the aspect of dynamic stability according to the third embodiment of the present invention.

FIG. 5 is a diagram showing a waveform of a phase angle of an equivalent single generator according to a third embodiment of the present invention.

FIG. 6 is a flowchart for performing stability determination from the aspect of frequency limit according to the fourth embodiment of the present invention.

FIG. 7 is a diagram showing waveforms of frequency characteristics according to the fourth embodiment of the present invention.

FIG. 8 is a flowchart showing a conventional power transmission limit calculation method.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Koji Sakaguchi             1-2, Wadasaki-cho, Hyogo-ku, Kobe-shi, Hyogo             No. within Melco Power Systems Co., Ltd. (72) Inventor Yukio Araki             3-3-22 Nakanoshima, Kita-ku, Osaka City, Osaka Prefecture             Kansai Electric Power Co., Inc. F-term (reference) 5G066 AA01 AA03 AA09 AD01 AD06                       AE07 AE09

Claims (9)

[Claims] 1. A method for calculating a power transmission limit of a power system, in which a detailed stability calculation of the power system and a stability determination are performed in parallel, wherein the stability is determined by a first calculation for performing an overload determination. , A second calculation for determining the voltage stability, a third calculation for calculating the frequency limit, and a fourth calculation for determining the transient stability.
And the fifth calculation for determining the dynamic stability, the stability determination is performed by the first to fifth calculations while constantly monitoring the detailed stability calculation result. When it is determined that the power system is stable or unstable as a result of the determination, the detailed stability calculation and the execution of the stability determination are stopped, and when the power system is determined to be stable, the power transmission amount is increased. Then, the detailed stability calculation and the first
~ Execution of the fifth calculation to determine the stability, and when it is determined to be unstable, the transmission amount calculation immediately before the instability is set as the transmission limit value. Method. 2. A method for determining the dynamic stability of an electric power system after an accident occurs, which comprises the following steps (1) to (4). (1) A step of allocating the power flow value at the accident point by the ratio of the rated capacities of the plurality of generators operating in the system. (2) A step of obtaining the center of inertia δ center of the system from the inertia constant and the phase angle of each generator of the system. (3) Comparing the δ center with the phase angle of each generator, the generator group having a phase angle larger than the δ center is the acceleration side group, and the generator group having a small phase angle is the deceleration side group, The phase angles δ ₁ and δ of the two groups of generators of the acceleration side group and the deceleration side group are reduced.
₂ and the step to ask. (4) The difference δ between δ ₁ and δ ₂ is the phase angle of one equivalent machine,
This phase angle δ is compared with a preset threshold value δsh, and δ
A step of determining unstable if> δsh and stable if δ <δsh. 3. A method for determining the dynamic stability of an electric power system after an accident, which comprises the following steps (1) to (5). (1) A step of monitoring the phase angle δe of each generator. (2) A step of obtaining the phase angle δemax of the most accelerated generator and the phase angle δemin of the least accelerated generator among the phase angles δe of the generators. (3) A step of calculating the phase angle δ = δemax−δemin of one equivalent aircraft from immediately after the occurrence of the accident to the time of determination at the timing when the difference between δemax and δemin is maximum. (4) At least 3 points for the highest point and the lowest point of the phase angle δ.
A step of obtaining 6 points in total and calculating the difference between the highest point and the lowest point to confirm the divergence tendency of the phase angle. (5) A step of determining that the difference between the highest point and the lowest point is unstable if the difference is divergent and stable if the difference is convergent. 4. The electric power, characterized in that, after the occurrence of a power system accident, the stability determination from the frequency limit when the power system is separated is performed in the following steps (1) and (2). How to determine system stability. (1) The total power generation amount P _G and the total load amount P _L in each grid are calculated, and the frequency deviation ΔF ₁ within the governor-free region and the frequency deviation ΔF outside the governor-free region are calculated from the following equations (1) and (2). _Two
Calculating step. [Equation 1] [Equation 2] (2) A step of determining that the calculated frequency deviation ΔF of each system is stable if it is within a preset allowable range, and unstable if it is outside the allowable range. 5. The method for calculating a transmission limit of an electric power system according to claim 1, wherein, when the transmission limit amount is recognized, a detailed stability calculation is executed to check its validity. 6. A detailed stability calculation procedure for calculating stability of a power system, and a detailed stability calculation procedure executed in parallel with the detailed stability calculation procedure.
A stability determination processing procedure for constantly monitoring the detailed stability calculation to perform stability determination, the stability determination processing procedure includes a first calculation for performing an overload determination and a voltage stability determination. Has the contents of performing the second calculation for performing the above, the third calculation for calculating the frequency limit, the fourth calculation for determining the transient stability, and the fifth calculation for determining the dynamic stability. When the power system is determined to be stable or unstable from the first to fifth calculation results, execution of the detailed stability calculation and stability determination is stopped, and the power system is determined to be stable. In this case, the amount of power transmission is increased, the detailed stability calculation and the stability determination are executed again, and if it is determined that the power transmission amount is unstable, the power transmission amount immediately before becoming unstable is set as the power transmission limit value. A power transmission limit of a power system characterized by having a value qualification processing procedure Out program recorded computer-readable recording medium. 7. A computer-readable recording medium having a program for determining the dynamic stability of a power system after an accident, which is characterized by comprising the following steps (1) to (4). (1) A step of allocating the power flow value at the accident point by the ratio of the rated capacities of the plurality of generators operating in the system. (2) A step of obtaining the center of inertia δ center of the system from the inertia constant and the phase angle of each generator of the system. (3) Comparing the δ center with the phase angle of each generator, the generator group having a phase angle larger than the δ center is the acceleration side group, and the generator group having a small phase angle is the deceleration side group, The phase angles δ ₁ and δ of the two groups of generators of the acceleration side group and the deceleration side group are reduced.
₂ and the step to ask. (4) The difference δ between δ ₁ and δ ₂ is the phase angle of one equivalent machine,
This phase angle δ is compared with a preset threshold value δsh, and δ
A step of determining unstable if> δsh and stable if δ <δsh. 8. A computer-readable computer-readable record in which a program for determining the dynamic stability of a power system after an accident has been recorded, comprising the following steps (1) to (5): Medium. (1) A step of monitoring the phase angle δe of each generator. (2) A step of obtaining the phase angle δemax of the most accelerated generator and the phase angle δemin of the least accelerated generator among the phase angles δe of the generators. (3) A step of calculating the phase angle δ of one equivalent aircraft from immediately after the occurrence of the accident to the time of determination at the timing when the difference between δemax and δemin is maximum. (4) At least 3 points for the highest point and the lowest point of the phase angle δ.
A step of obtaining 6 points in total and calculating the difference between the highest point and the lowest point to confirm the divergence tendency of the phase angle. (5) A step of determining that the difference between the highest point and the lowest point is unstable if the difference is divergent and stable if the difference is convergent. 9. A computer reading in which a stability determination program from a frequency limit when the power system after the accident is separated is recorded, comprising the following steps (1) and (2): Possible recording medium. (1) The total power generation amount P _G and the total load amount P _L in each grid are calculated, and the frequency deviation ΔF ₁ within the governor-free region and the frequency deviation ΔF outside the governor-free region are calculated from the following equations (1) and (2). _Two
Calculating step. [Equation 3] [Equation 4] (2) A step of determining that the calculated frequency deviation ΔF of each system is stable if it is within a preset allowable range, and unstable if it is outside the allowable range.