An Online Voltage Stability Judgment Method for AC/DC Hybrid System

Abstract

The invention provides an on-line voltage stability judging method for an alternating current and direct current series-parallel system. The method includes the steps that step1, a two-node model of an electric transmission line is established according to parameters, such as resistance R, reactance X and admittance B collected in real time, of the electric transmission line; step2, active power PB and reactive power QB of the receiving end of the electric transmission line and bus voltage UA of the transmitting end of the line are collected in real time; step3, the on-line voltage stability evaluation indexes of all electric transmission lines are calculated according to the two-node models of all the electric transmission lines; step4, whether the system reaches a boundary of voltage instability or not is judged according to the on-line voltage stability evaluation indexes of all the electric transmission lines. According to the judging method, the level of the static voltage stability can be effectively evaluated in a slow-growth mode of loads, besides, the level of transient voltage stability of the system can be effectively evaluated under the failure condition of direct current shutting, different voltage stability judging methods are adopted according to the difference of failure properties, the on-line calculation scale is obviously simplified, and calculation speed is increased.

Description

technical field [0001] The invention relates to the field of safety and stability analysis of electric power systems, in particular to an on-line voltage stability judgment method of an AC / DC hybrid system. Background technique [0002] The successive occurrence of voltage collapse accidents in large power grids abroad has brought profound warnings to the electric power industry and has effectively promoted the in-depth development of the field of voltage stability. However, the theoretical system of voltage stability has not been perfected so far. Before the 1990s, the research on voltage stability mainly focused on static stability. At present, the research on dynamic voltage stability analysis method is being deepened continuously. Japan emphasizes the enhancement of the voltage control capability after the accident, while France focuses on the preventive measures in the state of emergency before the accident. Units such as Italian Power Grid, Swedish Power Grid, and Hy...

AI Technical Summary

Problems solved by technology

For the first type of fault, since the short-circuit impact is not considered, the situation is relatively simple; it is similar to the voltage instability caused by the slow increase of load considered in static voltage stability. The static voltage stabilization method cannot accurately simulate the response of loads, generators, etc., but some types of load responses and generator constraints can also be considered in static voltage stabilization

At present, the commonly used static voltage stability indicators include sensitivity index, load margin index, Jacobian matrix minimum singular value index, local voltage stability L index, etc., and have achieved good static voltage stability evaluation results, but these methods need to be carried out to varying degrees. It is difficult to apply to the online voltage stability monitoring system that requires fast calculation

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