直流偏磁对换相失败的影响机理及定量分析方法

针对直流输电系统故障恢复过程中出现的异常换相失败现象,理论分析了换流变压器直流偏磁、换相电压波形畸变、异常换相失败三者之间的关系。以换相电压波形畸变为桥梁,提出了直流偏磁对换相失败影响的定量分析方法。根据采用某特高压直流输电系统实际工程参数建立的PSCAD/EMTDC仿真模型,应用所提方法分析了其故障恢复过程中异常换相失败,揭示了直流偏磁、电压畸变以及换相失败之间的内在联系并且量化了直流偏磁造成的换相电压谐波畸变对换相失败的影响,论证了方法的工程实用性。

Mechanism and Quantitative Analysis Method for The Influence of DC-bias on Commutation Failure

In allusion to the abnormal commutation failure phenomenon which occurred in the fault recovery process of DC transmission system, the theoretical analysis of relationship among converter transformer DC-bias, commutation voltage waveform distortion and abnormal commutation failure is performed. In commutation voltage waveform distortion as a bridge, a quantitative analysis method for the influence of DC-bias on commutation failure is proposed. Based on PSCAD/EMTDC simulation model built by the use of actual engineering parameters of a UHVDC transmission system, and the proposed method is used to analyze the abnormal commutation failure which occurred in its the fault recovery process. Simulation results reveal internal relations among DC-bias, voltage distortion and commutation failure and quantify the influence of commutation voltage harmonic distortion caused by DC-bias on commutation failure, and confirm the effectiveness of the method.