一种新型低频电压注入式励磁绕组接地保护

A New Field Winding Ground Fault Protection with Low Frequency Voltage Injection

新型低频电压注入式励磁绕组接地保护将交流电压经变压、整流后,再由电子开关切换得到频率可控的低频方波电压作为注入电压。文中介绍了保护的原理、动作判据和硬件运行机理,对保护精度和灵敏度也进行了分析。静态模拟试验和动态模拟试验结果表明,保护精度和灵敏度可以满足实际运行需要。另外,对保护应用中的3个问题也进行了分析:采取适当措施保证保护的精度、两点接地保护的应用以及对间歇性接地故障的处理。在三峡左岸电站的运行记录表明,装置运行可靠,性能良好,具有良好的工程应用前景。

In the new field winding ground fault protection with low frequency square-wave voltage injection, the injection voltage is transformed from an AC voltage by transformer, rectifier and electronic switches, and its frequency is controllable. The principle, criterion and hardware configuration of protection are introduced. The accuracy and sensitivity of new protection are also analyzed. The results of static simulation test and dynamic simulation test show that the accuracy and sensitivity of protection can meet the operation requirement. Furthermore, three problems about protection application are analyzed： taking the appropriate measures to ensure the protection accuracy, the application of two-point ground fault protection, and the detection of intermittent ground fault. The operational result of protection in Three Gorges Left Bank Power Plant indicates that the protection operates reliably, with stable performance, so the protection＇s engineering application prospect is good.