多端直流输电系统中限流电抗器配置研究

Research on configuration of current limiting reactor in multi-terminal HVDC system

多端直流电网的故障暂态发展极快,因此在实际工程中一般需要配置限流电抗器来抑制故障电流的上升。但是,限流电抗器的配置在限制故障电流的同时,也会对非故障的部分产生影响,因此文中对多端直流输电系统中限流电抗器的配置进行了研究。建立了多端直流输电系统的故障计算模型,并给出了包含断路器各动作阶段的系统状态量的计算方法;分析了多端直流输电系统中限流电抗器的配置需要考虑的问题;以四端直流输电系统为例,针对不同的限流电抗器配置情况下的直流系统故障过程进行了仿真计算,并根据计算结果分析了限流电抗器对系统最大故障电流、换流站闭锁情况、直流母线过压情况和过电流衰减时间等问题的影响。

The fault transient of multi-terminal DC power grid develops very fast,so it is necessary to configure current-limiting reactor to restrain the rise of fault current in practical engineering.However,the configurations of current-limiting reactor will also impact on non-fault part while limiting the fault current.Therefore,configurations of current-limiting reactor in multi-terminal HVDC transmission system are studied in this paper.Firstly,the fault calculation model of multi-terminal DC transmission system is established,and the calculation method of system state quantity including each action stage of circuit breaker is given.Then,this paper analyzes the problems that are considered in the configuration of a current limiting reactor in multi-terminal HVDC transmission system.Finally,taking four-terminal HVDC transmission system as an example,the fault process of the DC system under different current-limiting reactor configurations is simulated and calculated.Based on the calculation results,the influence of current-limiting reactor on the maximum fault current,the blocking condition of converter station,overvoltage of DC bus and decay time of over-current of a system is analyzed.