故障分量发电机定子单相接地保护应用研究

简要分析了发电机发生定子单相接地故障后,机端和中性点侧零序电压变化的特性,并对基波和3次谐波电压原理的发电机定子接地保护方案的灵敏度进行比较.研究表明,发电机绕组中部接地时电压增量相对较小,不利于保护灵敏度的提高.在此基础上,提出改进的利用基波和3次谐波零序电压综合信息量的差动保护判据.该判据忽略基波零序电压增量的影响,减少了调试和整定环节,能有效提高保护灵敏度.理论分析以及实验研究均表明其优越性.

New Differential Protection Research for Generator Stator Single Phase Ground Fault

With occurring of single phase ground fault, fundamental zero-sequence voltages and the third-harmonic voltages at the generator neutral and the terminals change simultaneously. These changing characteristics and their influence on the protection schemes are analyzed. Results show that the fault contributed zero sequence voltages at the middle winding present lower values than at other locations, which affects performance of the protection scheme greatly. Hence this paper describes a new differential protection scheme based on fault contributed zero-sequence voltage. Because it uses the integrated information of the fundamental zero-sequence voltage and third-harmonic voltage, the proposed method can detect ground fault with 100% coverage and high sensitivity. Simulation and experimental results confirm its high sensitivity and reliability.