柔性直流电网线路保护与直流断路器优化协调配合策略研究
Study on Optimized Coordination Strategies Between Line Protection and DC Breakers for VSC-based DC Grid
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摘要: 采用架空线作为传输线路是未来高压大容量长距离柔性直流电网进行功率传输的主流形式,然而,架空线的应用势必会造成直流线路故障概率的大大增加,因此,研究如何快速隔离直流故障线路这一关键问题显得十分突出。该文基于直流断路器的保护技术路线,在深入分析传统保护配合策略的基础上,以行波保护为例,提出两种线路保护与直流断路器优化协调配合策略,降低故障期间近端换流站闭锁和直流电网主设备电力电子开关损坏的风险。最后,针对典型工况,对所提出的优化协调配合策略进行仿真分析。Abstract: The mainstream form of power transmission in future high-voltage, large capacity and long distance VSC-based DC grid is using overhead lines as transmission lines. However, the application of overhead lines is bound to cause a great in-crease in the probability of DC line failure.Therefore, it is very important to study how to isolate the DC fault line quickly. Based on the protection technology route using DC breaker, on the basis of in-depth analysis of traditional protection coordination strategy, taking traveling-wave protection as an example, two optimized coordination strategies between line protection and DC breaker were proposed in this paper. As a result, the risks of both the blocking of the MMC which is near the fault position and damage of power electronic switches of the main equipment in VSC-based DC grid are reduced. Finally, the optimized coordination strategy was simulated and analyzed under typical working condition.
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