Research On Power System Transient Voltage Stability And Control Of Large Scale Receiving-end Power System

Modern power system is a complex nonlinear dynamic system with four parts of generation, transmission, distribution and using. The fundamental demand of power system is safety and stability and voltage stability is one of prominent problem. Transient Voltage stability is especially a vital important problem which can be a reason for vast power system collapse.This thesis devotes to develop and improve new generation theory of reactive power optimization as important preventive control means for voltage stability problem, realize voltage stability contingency screening and ranking considering transient voltage stability, provide flexible and practical decision-making foundation for safety surveillance, dynamic assessment, prevention control and emergency control of power system to dispatcher. This dissertation deeply discusses a series of important topics, such as theory and mechanism of transient voltage stability, static and dynamic reactive power optimization and their application in power system. Mainly, it obtains following achievements.(1) It presents a kind of improving contingency screening and ranking algorithm taking into consideration voltage security problems, it is shown that the newly proposed method has the good performance in terms of accuracy and computation time.(2) Based on the localization feature of voltage problem, a new concept of "electrical distance" is presented to select the candidate location of Reactive Power Devices.(3) Based on intelligent serach and trajectory optimization, a algorithem is presented to select the location and capacitory of Reactive Power Devices.(4) A kind of emergency load shedding algorithm is presented considering voltage stability. According to this algorithm, minimum load shedding objective can be obtained, it can be guaranteed that voltage stability margin is larger than a given critical value and multi objective of safety and economics can be satisfied.(5)The motheds presented above have been used to analysis large scale power grid transient voltage stability problem which prove the algorithems are correct and useful.