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

Frontiers in Energy Research

Zheng Li¹  Xu Cai²  Chen Zhang³  Marta Molinas³ 

[1] College of Environmental Science and Engineering, Donghua University, Shanghai, China;Department of Electrical Engineering, Shanghai Jiao Tong University, Shanghai, China;Department of Engineering Cybernetics, Norwegian University of Science and Technology, Trondheim, Norway;

关键词: PLL;    VSC;    non-linear;    ROA;    stability;    SOS;   

DOI  :  10.3389/fenrg.2020.00056

来源: DOAJ

【 摘 要 】

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

【 授权许可】

Unknown