Sample Generation for Security Region Boundary Identification Based on Topological Features of Historical Operation Data

Since the scale and uncertainty of the power system have been rapidly increasing,the computation efficiency of constructing the security region boundary(SRB)has become a prominent problem.Based on the topological features of historical operation data,a sample generation method for SRB identification is proposed to generate evenly distributed samples,which cover dominant security modes.The boundary sample pair(BSP)composed of a secure sample and an unsecure sample is defined to describe the feature of SRB.The resolution,sampling,and span indices are designed to evaluate the coverage degree of existing BSPs on the SRB and generate samples closer to the SRB.Based on the feature of flat distribution of BSPs over the SRB,the principal component analysis(PCA)is adopted to calculate the tangent vectors and normal vectors of SRB.Then,the sample distribution can be expanded along the tangent vector and corrected along the normal vector to cover different security modes.Finally,a sample set is randomly gen-erated based on the IEEE standard example and another new sample set is generated by the proposed method.The results indicate that the new sample set is closer to the SRB and covers different security modes with a small calculation time cost.

Orbiting Optimization Model for Tracking Voltage Security Region Boundary in Bulk Power Grids

A voltage security region(VSR)is a powerful tool for monitoring the voltage security in bulk power grids with high penetration of renewables.It can prevent cascading failures in wind power integration areas caused by serious over or low voltage problems.The bottlenecks of a VSR for practical applications are computational efficiency and accuracy.To bridge these gaps,a general optimization model for tracking a voltage security region boundary(VSRB)in bulk power grids is developed in this paper in accordance with the topological characteristics of the VSRB.First,the initial VSRB point on the VSRB is examined with the traditional OPF by using the base case parameters as initial values.Then,the rest of the VSRB points on the VSRB are tracked one after another,with the proposed optimization model,by using the parameters of the tracked VSRB point as the initial value to explore its adjacent VSRB point.The proposed approach can significantly improve the computational efficiency of the VSRB tracking over the existing algorithms,and case studies,in the WECC 9-bus and the Polish 2736-bus test systems,demonstrate the high accuracy and efficiency of the proposed approach on exploring the VSRB.