Transient voltage stabilization judgment method based on real-time generalized Thevenin equivalence

Abstract

The invention discloses a transient voltage stabilization judgment method based on real-time generalized Thevenin equivalence, which is applied to an electric power system. The method comprises the following steps: obtaining a Jacobian matrix J and an inverse matrix J-1 of a node power equation at a corresponding moment according to voltage and power statuses of the system and a correction system admittance matrix Y' at each moment in a transient process of the electric power system; and further obtaining a relational expression between node voltage variation and load power variation at an equivalent node, obtaining a relational expression between load current variation and the load power variation at the equivalent node, then obtaining a Thevenin equivalence impedance of the corresponding moment, and finally calculating transient voltage stabilization judgment indexes for off-line analysis and on-line status tracking and early warning of the electric power system. The method disclosed by the invention aims to judge whether transient voltage instability occurs in the system by calculating current Thevenin equivalence parameters according to the status of single time section in the transient process of the electric power system, and the method has the characteristics of intuition and accuracy.

Description

technical field [0001] The invention relates to a data judging method applied to a power system, in particular to a transient voltage stability judging method based on real-time generalized Thevenin equivalents. Background technique [0002] Power system transient voltage stability refers to the ability of all buses in the system to maintain stable voltage after the power system is subjected to large disturbances such as line faults, loss of generators or loads in a short period of time. How to accurately judge the occurrence of transient voltage instability in the power system is still a difficult problem to be solved. At present, the following practical criterion is generally adopted in my country: when the bus voltage at the system voltage center point drops continuously (usually 1s) below the limit value during the transient process (Generally 0.75p.u.), it is considered that the system or load voltage is unstable; otherwise, the system or load voltage is stable. This pr...

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Problems solved by technology

[0004] After searching the existing technologies, it is found that there are many Thevenin equivalent parameter tracking algorithms, which can be roughly divided into three categories according to the principle of the method, and all have their own shortcomings: 1) Based on local state monitoring or power flow calculation algorithm

The problem with this type of method is that it directly applies the conclusions of linear circuits to nonlinear power systems, ignoring the changes of Thevenin equivalent parameters in these two states, so there is a certain deviation

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