Synchronizing Stability Analysis and Region of Attraction Estimation of Grid-Feeding VSCs Using Sum-of-Squares Programming

摘要: Grid-synchronising Stability (GSS) is an emerging issue that exists in grid-feeding voltage-source converters (VSCs). Its occurrence primarily related to the nonlinear dynamics of a type vastly applied synchronization units - Phase-locked Loops (PLL). Dynamic characterisation and modelling for GSS analysis can be achieved by using simplified system model, which second-order autonomous equation; however, with presence indefinite damping term. As revealed demonstrated this work, effect result inaccurate Region-of-Attraction (ROA) estimation traditional Equal Area Principle (EAP)-based method. To overcome achieve valid ROA estimation, paper adopts sum-of-squares (SOS) programming technique, numeric optimisation method SOS relaxations. The development implementation program are presented. Numerical case studies time-domain verifications demonstrate analysis, almost precise first quadrant. This evidence makes promising tool because problem most concerned stability within swing cycle, i.e.,