Steady State Analysis In Wind Power Integrated System Based On Optimal Power Flow Under Multi-operating Mode

The optimal power flow (OPF) problem in power system refers to conductcomprehensive optimization between economic and safety, which is based on the powerflow equations and combined the economic dispatch and power flow calculation. OPF canbe considered as a non-convex, multi-constraint, multi-variant and non-linear programmingproblem. The reliability and power quality can be quantized into corresponding economicindicators by OPF to optimize the allocation of resources, reduce generate electricity,transmit electricity cost, and improve the goals of service quality to the users. With theincreasing of research and development strength to the new energy by the state, one of themost mature, the most large-scale development and commercial development prospects ofrenewable energy power generation, wind power generation has been received muchattention and developed and utilized widely. Multi-operation mode of the power system willbe occured due to the characteristics of randomness, intermittent, fluctuation and withoutschedulability of wind power generation. Considering the uncertainties in the power systemand correlation of random variables, it is necessary to study the OPF computation includingwind farms under multi-operation mode described by probability theory. The steady stateanalysis of grid-connected power system based on OPF under multi-operation mode isresearched in this dissertation. The main contents of the dissertation are as follows:Firstly, the OPF problem is solved by the semismooth Levenberg-Marquardt (L-M)based on the subdifferential and the path following interior point method (PFIP),respectively. The two kinds of algorithm performances are compared. The L-M method andPFIP method to solve the OPF problem are introduced after depicting OPF model explicitly.Then, the algorithm steps to solve the OPF problem are determined. Two kinds of algorithmare verified on the5-bus system, IEEE30-bus system, and IEEE118-bus system,respectively. The OPF results obtained by two methods are compared and the validity ofalgorithm is analyzed.Secondly, the OPF calculation including wind farms is researched and the main factorsto influence the OPF solution after the wind farms integration to the power system areanalyzed. The wind power penetration level problem is also discussed. The OPF modelincluding wind farms is established, based on the asynchronous wind power generatormodel considering the characteristics of the reactive power and the slip. The L-M methodand PFIP method are also employed to solve OPF calculation including wind farms,respectively. The OPF results obtained by these two methods are compared and analyzed.Meanwhile, the impacts of wind speed, wind turbine numbers, and wind power penetrationlevel on OPF results are systematically analyzed.Finally, the probabilistic optimal power flow (POPF) considering the mutualcorrelation of load and randomness of wind speed is researched and the impacts of thecorrelation between load on the solution of POPF are discussed. The POPF model including wind farms is established. The estimated points of random variables in the power system areobtained by four different kinds of schemes (2m,2m+1,3m,4m+1) in point estimatemethod, respectively. The estimate points with the specified correlation coefficient aregenerated by the cholesky factorization method. Finally, the PFIP method is employed tosolve the deterministic OPF. Then, the numerical characteristics, cumulative distributionfunction and probability density function of output variables are obtained. The POPF resultsobtained by these four different kinds of schemes in point estimate method are compared tothat by Monte Carlo simulation method. The impacts of mutual correlation of variables onPOPF results are analyzed.