Adaptability analysis and performance improvement method of ac protection in inverter-interfaced system with series compensation device

Abstract

With the continuous increase in the capacity of renewable energy system integrated into the grid, parts of renewable energy systems located in remote area are required to equip with series compensation device to improve their transfer capacity. However, in terms of relay protection, the connection of series compensation device will change the topology of the grid. And this results that the system with series compensation will exhibit special fault characteristics, which may deteriorate the performance of relay protection and cause significant losses to the grid. On this context, to solve the problem, the authors deeply analyze the adaptability of AC protection in the compensated inverter-interfaced system first. Then, for the inadaptability protections, the authors propose a series of methods based on special fault features of the grid or active harmonic injection to improve them. Based on the novel methods, the criteria for directional relay, phase selector, and distance protection have been deduced. Finally, the PSCAD simulation results demonstrate the correctness of the adaptability analysis and the effectiveness of the proposed protection methods.

Keywords

• Compensated inverter-interfaced system
• adaptability analysis of AC protection
• fault feature analysis
• active harmonic injection
• novel protection methods