Method for calculating time-lag electric power system eigenvalue and discriminating stability based on Pade approximation

Abstract

The invention discloses a method for calculating time-lag electric power system eigenvalues and discriminating stability based on Pade approximation. The method uses Pade approximation to make wide area feedback time-lag approximate to a rational polynomial. Though connecting with an electric power system without time-lag and a wide area damping controller, a linearized model of the time-lag electric power system is established. Finally, part of characteristic roots of the time-lag system is directly obtained according to a system state matrix, and then time-lag stability of the system is determined. According to an eigenvalue calculating result of a four-machine two-region example system, the method can relatively accurately solve part of the eigenvalues and eigenvectors which are corresponding to dynamic elements in the time-lag system. The method can conveniently and accurately determine time-lag stability of the system, correctly solve the number of the eigenvalues which are corresponding to a time-lag link and calculate precision which is related to order of the rational polynomial. In addition, the method is advantaged by small calculated amount, and short calculating time.

Description

technical field [0001] The invention relates to a time-delay power system eigenvalue calculation and stability discrimination method, in particular to a time-delay power system eigenvalue calculation and stability discrimination method based on Pade approximation. Background technique [0002] With the expansion of the scale of the power system, the low-frequency oscillation between regions is becoming a bottleneck limiting the transmission capacity of the power grid, and the existing damping controllers (mainly power system stabilizers designed according to the single-machine infinite system) cannot solve this problem well. a question. The fundamental reasons are: (1) The relative power angle and relative angular velocity cannot be directly used to form a closed-loop control. Although using relative power angle and relative angular velocity to realize damping control is the most direct and effective, the necessary measurement method has been lacking for a long time, and ot...

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Problems solved by technology

[0002] With the expansion of the scale of the power system, the low-frequency oscillation between regions is becoming a bottleneck limiting the transmission capacity of the power grid, and the existing damping controllers (mainly power system stabilizers designed according to the single-machine infinite system) cannot solve this problem well. a question

The fundamental reasons are: (1) The relative power angle and relative angular velocity cannot be directly used to form a closed-loop control

Although the use of relative power angle and relative angular velocity to achieve damping control is the most direct and effective, but the necessary measurement method has been lacking for a long time, and other indirect variables can only be used instead, resulting in poor control effect

(2) Limited to local local information

Such methods are inherently conservative in judging the stability of the system

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