Calculation method for transient stability evaluation index of system after multi-loop DC commutation failure

Abstract

The invention discloses a calculation method for a transient stability evaluation index of a system after a multi-loop DC commutation failure, and the method comprises the following steps: simplifyingsending and receiving grids into a double-cluster system, and extending the double-cluster system into a three-cluster system which comprises three regions; determining a power angle difference through a Runge-Kutta method during the removing of a fault of the receiving end grid of the three-cluster system, calculating the speed-up area and slow-down area according to the power angle difference and a maximum cutting angle, and determining the stability margin. The method also comprises the steps: analyzing the relation among an inertia time constant, a fault duration time and the stability margin, and obtaining the impact on the stability of a system from the inertia time constant and the fault duration time. According to the invention, the double-cluster system is extended into the three-cluster system, and the extreme cutting angle is determined through the Runge-Kutta method. The stability margin of a power system is calculated, and various demands of actual application are met.

Description

technical field [0001] The invention relates to the field of electrical engineering, in particular to a method for calculating transient stability evaluation indexes of a system after multi-circuit DC commutation fails. Background technique [0002] In recent years, in my country's North China Power Grid and Northwest Power Grid, the installed capacity of wind power and photovoltaics has increased rapidly, which has enabled my country to gradually promote the transmission of power from west to east and build a number of UHV DC lines. , Fufeng 3 circuits of ±800kV UHV DC to the East China Power Grid of the load center, there are 4 circuits of ±500kV UHV DC to the East China Power Grid of the load center, and the total power of the 7 circuits of DC reaches 31760MW [1] . According to my country's power grid planning, in recent years, multiple circuits of UHV DC will be put into operation in Jinbei-Nanjing, Ximeng-Taizhou, Lingzhou-Shaoxing, Zhundong-Wannan, etc. [2-3] . The c...

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Problems solved by technology

At present, the research on this fault form is mainly divided into two-machine cluster method and three-machine cluster method. [5-7] : The two-machine cluster method is to analyze the stability mechanism and influencing factors by equating the actual system to be analyzed into a two-machine cluster system. The actual system can be equivalent to a two-machine cluster system by the equal-area rule to analyze the stability damage caused by DC commutation failure stabilization mechanism [5] , the stability mechanism can be analyzed intuitively from the physical essence, but it is difficult to realize the quantitative calculation of complex systems, and the second-order linear system shock response model is easy to quantitative calculation [6] , but it cannot explain the nature of stability and the poor adaptability to high-power conditions of the tie line; in order to describe the complex state of the actual sending-end system, the "Sanhua" system is equivalent to a three-machine cluster system [7] , which can better interpret the stability mechanism of the stability failure of the sending system caused by the failure of the receiving system. However, the existing literature on the three-machine cluster system focuses on the analysis of the mechanism of the stability failure, and is not perfect in the calculation of quantitative evaluation indicators. Quantitative evaluation indicators cannot be given, so the quantitative calculation still needs to be further improved

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