自适应漏电保护技术及其应用

在电网及用电设备工作正常情况下,由于用电设备数量或电网结构的变化,或是大气环境的变化,电网中的漏电电流会有较大的变化,因此固定动作阈值的漏电保护不能满足实际需要。本文建立了一种自适应漏电保护模型,将漏电保护范围分成几个区间,根据漏电电流的变化情况,自动改变漏电动作阈值,实现漏电保护的自适应保护。在漏电电流超过一定值(但小于漏电动作阈值)的情况下,其持续时间大于一定值时,自动调节漏电动作阈值。本文还提出了对漏电动作阈值进行修正的方法,根据温度、湿度选择不同的修正系数,更合理地进行漏电保护。采用漏电保护的反时限特性进行级间配合的方法,减少故障漏电动作的影响范围。最后,采用单片机,研制出实现具有自适应漏电保护功能的漏电断路器。

Adaptive Technology of Leakage Current Operation Protection and Its Application

In the normal condition of electric power system and equipment, the leakage current will change largely due to changes of equipment or environment, so the leakage current protection of fixed threshold operation will not meet actual requirements. An adaptive leakage current protection model is discussed, and leakage current protection range is divided into several parts. Based on changes of leakage current, threshold of residual operating current can be changed automatically, and then adaptive leakage current protection is accomplished. When leakage current goes beyond limit range but below the threshold over a period of time, it is regarded as normal change of leakage current. The threshold will be adjusted correspondingly. Modification method of leakage operating threshold is also introduced, correction factor can be selected for corresponding temperature and humidity, thus it can adapt the environment changes and protect more reasonably. The inverse time characteristic is used in multi-level leakage protection, and the fault leakage current operating range can be reduced. Finally, the leakage current circuit-breaker with microcontroller is developed and adaptive leakage protection is fulfilled.