Risk Assessment For Voltage Stability Based On Improved Bootstrap Method

The risk assessment of power system voltage stability can provide quantitative reference for protecting the customer power quality demand and decision-making power of enterprises, is an important means to prevent large-scale power outage caused by voltage instability. Because of defects of risk assessment models for the static voltage stability, large-scale asymmetric load access power system, the inherent "dimension disaster" problem for large-scale power system analysis and calculation, etc. Risk assessment research for voltage stability is still a further prospective study.Thesis aimed at two problems of simulation method with slow convergence speed and calculation results with probability, and combined the new method of traditional MC method and bootstrap method. The new method is defined as the improved bootstrap method. The model can improved reuse of sample set and ensured the convergence accuracy at the same time. By contrast, it need more number of analysis system state samples to calculate risk indicators by using traditional simulation method; Through the calculation results of probability distribution of sample set, this model also can strengthen the robustness of convergence results.Thesis aimed at the problems of asymmetric load access, such as traction load, advance the new risk assessment model for static voltage stability based on three-phase OPF. The universal element model, vector constraints, static voltage stability risk index system based on load margin and the weak link of the static voltage stability analysis are established as four core functions for the model. Thesis use modern interior point theory for three-phase OPF. Effectively solves the defects of the risk assessment of traditional static voltage stability model, opens up a new way for the study of static three-phase voltage stability. Simulation and analysis these two reliability test system of IEEE-RTS79and IEEE-RTS96show that:All of improved bootstrap method model, three-phase voltage stability critical point of OPF model, and the risk assessment of static voltage stability system meet the requirements of accuracy and practicability, some new techniques are used in this thesis also improves the expectations of computing speed and the accuracy. It provides that the models can be reasonable reference example for the future industrial application.