Research On Static Security Risk Assessment And Preventive Control Method For Power System

With the continuous development of the society and the continuous improvement of the level of industry,the power demand is increasing rapidly,and the scale of the system is also growing.These changes have brought a series of security issues to power system.Therefore,establishing an effective power system security assessment and preventive control method,for the safe and economic operation of power system,has a very positive significance.In this thesis,the methods of risk assessment to determine the system's static security status,not only can consider several kinds of uncertain factors,but also can combine the likelihood and severity of unsafe state.The power system bus voltage and branch power flow as static security risk evaluation index,quantitative system static security risk value and to determine the level of risk,a comprehensive grasp of the security state of the system.Firstly,this thesis studies the static security assessment of power system,including system power flow calculation and system component model.This thesis selects probabilistic load flow based on cumulants and Gram-Charlier series expansion,and the calculation accuracy are analyzed.The components in power system model is established,including the probability model of stochastic load model,power generation unit probability model and wind farm output.At the same time,the influence of the wind power and the disconnection of the power system is considered,and the method of improving the probability power flow is realized.Secondly,this thesis calculated the possibility of the unsafe condition based on the static security assessment index;to establish the static security risk based on Utility Theory assessment of severity index,thereby obtaining an element level of static safety risk value,and to determine the level of risk;the gray relational analysis method to determine the evaluation index weight,and puts forward the improved grey relational analysis method(IGRA)get index weight and to calculate the system risk level and to determine the risk level of the system,provides the decision-making basis for the subsequent security control.Again,this thesis considering the risk to improve power system static security level of prevention and control mathematical model;used to calculate the objective function of the improved primal dual interior point method is put forward,and through the IEEE 5-bus system as examples to verify the superiority of the improved algorithm;before using the improved methods according to the risk assessment results to calculate the optimal prevention and control measures,and with the conventional control measures are compared and analyzed.Its superiority is proved.Finally,the main conclusions of the thesis are summarized,and the contents of the thesis are also discussed.