含限流器的多端柔直系统故障保护策略

Protection Scheme for VSC-MTDC System with Fault Current Limiter

针对采用模块化多电平换流器(MMC)的多端直流系统(MTDC)故障电流大、上升速度快,现有混合式直流断路器(DCCB)无法快速有效隔离故障区域的问题,提出一种新型故障处理策略。通过对比电感型超导限流器(I-SFCL)和电阻型超导限流器(R-SFCL)对短路电流的影响,选取更具限流优势的R-SFCL,结合实验建立其失超和恢复超导态的等效模型。在分析R-SFCL和DCCB配合原理的基础上,提出R-SFCL和DCCB配合的故障处理流程。基于舟山工程在PSCAD/EMTDC仿真平台上对所提新型配合策略加以验证,仿真结果表明该配合策略能够快速地隔离故障,实现非故障站的故障穿越,提高了MTDC系统的稳定运行能力。

With fast rising speed, the DC fault current in modular multilevel converter(MMC) based multi terminal high-voltage DC(MTDC) system can be pretty huge, which makes it difficult f or the existing hybrid DC circuit breaker(DCCB) to quickly and effectively isolate the fault area. To solve this problem, a new protection scheme was proposed. By comparing the effects between inductive type superconducting fault current limiter(I-SFCL) and resistive type SFCL(R-SFCL) on fault current, R-SFCL with more current limiting advantages was selected and establishing an equivalent model of quenching and recovering based on experiment. By analyzing the cooperation principle of R-SFCL and DCCB, the new protection scheme by coordinating R-SFCL and DCCB was proposed. The correctness and efficiency of the scheme was verified on PSCAD/EMTDC based on Zhoushan Project. Simulation results show that the proposed scheme can quickly isolate the fault area, r ealize the fault ride-through capacity for non-faulty terminals, which further enhances the stability of the MTDC system.