龙滩水电站10kV厂用变保护的优化配置

Optimization of Protection Configuration for 10kV Station Transformers of Longtan Hydropower Station

通过分析龙滩水电站10kV厂用电系统接线和保护配置情况,指出了原保护配置设计方面的缺陷:10kV厂用变低压侧没有过流保护,高压侧过流保护I段和II段也没有区分保护动作后果,当10kV母线上发生故障且故障电流达到10kV厂用变高压侧过流保护定值时,保护动作将造成越级跳闸,扩大了停电范围。对此提出3种解决办法,并比较了各自的优缺点,最后选用了增加10kV厂用变低压侧过流保护配置和修改保护接线的方案。实际运行证明了该优化配置方案的正确性。

Based on the analysis on the wiring of 10 kV auxiliary system and its protection configuration for Longtan hydropower station, the defects of original design and configuration of the protection for auxiliary system are pointed out that there is no overcurrent protection for low voltage side of 10kV substation transformer and the result of protection action of the first zone of overcurrent protection at its high voltage side is not distinguished from that of the second zone; due to these defects when fault occurs at 10kV bus and the value of fault current reaches the setting value of overcurrent protection for high voltage side of 10kV substation transformers, the overstep trip-out will happen, thus the power interruption range is enlarged. For this occasion, three solving methods are put forward and the advantages and disadvantages of the three methods are compared, finally, a scheme in which overcurrent protection is configured to low voltage side of 10kV station transformer and the protection wiring is modified is adopted. Actual operation result shows that the optimized protection configuration for station transformer is correct.