含直流故障限流装置动作的直流电网故障电流计算方法

The DC Fault Current Calculation of DC Fault Current Limiter Action Included in Bipolar MMC-HVDC Grid

模块化多电平换流器型柔性直流电网作为光伏和风电等新能源汇集的有效手段,其直流故障限流和故障线路的快速隔离具有重要意义。该文提出一种含限流器投切、断路器跳开和避雷器耗能过程的直流电网故障电流计算方法。首先,根据直流电网双极短路故障后电容快速放电机理,分析电感型故障限流器投入前后故障电流的变化情况。其次,考虑故障限流器投入过程与直流断路器的切断过程,并兼顾故障限流器和直流断路器中的金属氧化物避雷器(metal-oxide arrester,MOA)特性,提出一种包含6个子阶段的柔性直流电网故障电流计算方法。通过PSCAD/EMTDC电磁仿真平台验证该算法的准确性。

The modular multilevel converter(MMC) based bipolar HVDC grid is an effective option for the renewable energy sources integration such as wind and PV power, and thus the DC fault current-limiting and fast isolation of the fault branch have great importance to the HVDC transmission. This paper proposed DC fault current calculation method considering the prompt actions of fault current limiters(FCLs) and DC circuit breakers(DCCBs). First, based on the capacitor discharging mechanism of the bipolar HVDC grid under solid pole-to-pole short-circuit fault, the transient performance of the grid before and after the insertion of the inductive FCL was analyzed. Then, considering the action processes of the FCL and DCCB along with the energy consumption characteristics of the metal-oxide arrester(MOA), the HVDC gird fault current calculation method was proposed which includes six substages, then each stage can be accurately reproduced. The electromagnetic transient(EMT) simulations on PSCAD/EMTDC and the calculations on Matlab shows that the proposed calculation method is accurate and superior over the EMT simulation in terms of the computational efficiency.