【摘要】 对称单极结构背靠背柔性直流输电系统(back-to-back flexible DC transmission system, DC-BTB)带启动电阻充电期间发生阀侧不对称接地故障时故障特征不明显，易造成保护拒动；正常充电期间存在正负极不平衡电压，易造成保护误动。针对此问题，分析带启动电阻充电期间发生阀侧不对称接地故障时的特征量，并与运行期间相同故障下的特征量进行对比；分析正常充电和极对地故障下正负极不平衡电压特征；针对不同接地故障及其特征，优化换流变压器阀侧零序过压保护、换流变压器阀侧中性点过流保护和直流电压不平衡保护的定值设计。最后，基于实际控制保护装置，在实时数字仿真系统(real time digital simulation system, RTDS)中搭建模型进行仿真分析，结果表明经定值优化后的保护可有效识别充电期间接地故障特征和正常充电特征。仿真结果验证了所提定值优化设计方法的可靠性。更多还原

【Abstract】 The asymmetric grounding fault characteristics of back-to-back flexible DC transmission system(DC-BTB) with symmetrical monopole structure are not obvious in charging process which may cause protection failure. On the other hand, there is positive and negative unbalanced voltage in the charging process, which may result in prevention misoperation. Therefore, this paper analyzes the characteristic quantities of asymmetric grounding fault at valve side during charging with starting resistance, and makes comparisons with the characteristic quantities in case of the same fault during operation. Furthermore, it analyzes the characteristics of positive and negative unbalanced voltage under normal charging and pole-to-ground faults. Then, according to different grounding faults and their characteristics, setting value designs of zero sequence overvoltage protection, neutral overcurrent protection and DC voltage imbalance protection are optimized. Finally, the paper establishes the model in the real time digital simulation system(RTDS) for simulation analysis based on actual control and protection devices and proves the availability of protection setting value design to distinguish grounding fault and normal charging characteristics. The simulation results verify the reliability of the proposed optimized design method for setting value.更多还原