MMC-HVDC系统过电压保护和绝缘配合的研究

在整个MMC-HVDC系统的设计中，过电压保护和绝缘配合是一个必须解决的关键问题。鉴于国内外相关专题研究较少，在充分借鉴传统直流工程以及MMC-HVDC系统本身特性研究成果的基础上，基于西门子Transbay工程，提出了一种适用于MMC-HVDC系统的过电压保护方案。该保护方案通过将避雷器安置在换流站的关键位置，通过限制关键点的过电压去实现保护换流站关键部件的功能。鉴于该工程全部采用直流海缆，可以不考虑雷电过电压，所以提出了14种换流站中可能发生的故障，用来作为换流站绝缘设计的校核工况。借助于PSCAD/

Study of overvoltage protection and insulation coordination for MMC based HVDC

In the entire cycle of MMC-HVDC planning, overvoltage protection and insulation coordination is one of the most important parts needed to be considered. An overvoltage protection scheme, which takes the Transbay project by Siemens as an example system, is proposed. The scheme combines the research results in traditional HVDC systems and the characteristics of MMC-HVDC systems, and places arresters at some key locations in the MMC-HVDC converter station, which can directly limit the overvoltage to an acceptable range and hence protect the key equipment concerned. Since all the DC lines of the project are undersea cables, no lighting overvoltage is considered and 14 faults which could happen are carefully selected to serve as the verification conditions for the insulation design. Based on the PSCAD/EMTDC simulations and the deterministic method, the required withstand voltage level of the key equipment in the converter station is calculated.