应用电子式电流互感器的变压器差动保护研究

Applying Electronic Current Transformer to Transformer Differential Protection

电磁式电流互感器在电力系统故障情况下可能发生饱和,常导致继电保护装置误动或拒动。利用电子式电流互感器无饱和的特点,在动模试验环境下,研究了应用电子式电流互感器的变压器差动保护性能,指出电子式电流互感器采用空心线圈,没有饱和现象,可正确反映故障情况下各次谐波含量,提高变压器保护区外故障时动作的安全性、区内故障时动作的可靠性以及基于谐波制动原理的差动保护动作速度。结合实际应用中的问题,指出GPS硬件时钟同步法是解决数据同步采样问题的优选方案,并对应用电子式互感器的差动保护新原理的研究进行了简要探讨。

The saturation of magnetic current transformers, occurred during a fault on the power system, will lead to mal-operation or refused operation of protection relay. As a novel air-core non-saturation transducer, electronic current transformer （ECT） can measure the base component and harmonic components of fault current correctly. The performance of transformer differential protection applied ECT was researched under dynamic tests environment. It proved that ECT could improve the safety of transformer differential protection when out-zone fault occurred and the reliability of transformer differential protection when in-zone fault occurred. The operation speed of relay based on second harmonic restraint theroy could be accelerated too. It pointed out that GPS synchronic sampling method are the better solutions to the problem of data synchronic sampling when applying ECT to substation automation system. It also discussed new differential protection theory based on applying ECT briefly.