基于瞬时电流的大容量高压变频电动机差动保护技术

Differential Protection Technology of Large Capacity High-Voltage Variable Frequency Motor Based on Instantaneous Current

常规的电动机差动保护异常定位通常为单向定位,保护针对性不强,导致误动率增加,为此,本文提出基于瞬时电流的大容量高压变频电动机差动保护技术的设计与分析。根据实际的测定需求及标准,先进行变频单元保护配置,采用多阶的方式,在瞬时电流的背景下,完成三相异步异常定位,提高整体的差动保护针对性,并以此为基础,进行纵差动保护整定计算及瞬时电流接地保护处理,采用变频分设修正实现差动保护。测试结果表明,与传统磁平衡和传统循环差动保护测试组相比,本次设计的瞬时电流电动机差动保护测试组最终得出的误动率相对较低,被较好地控制在了20%以下,对运行过程中的电动机保护效果更佳,具有实际的应用价值。

The conventional abnormal positioning of motor differential protection is usually unidirectional,and the protection is not targeted,resul ting in an increase in maloperation rate.Therefore,this article proposes the design and analysis of differential protection technology for large capacity high-voltage variable frequency motors based on instantaneous current.According to the actual measurement requirements and standards,the frequency conversion unit protection is configured first,and the three-phase asynchronous abnormal positioning is completed in a multi-step way under the background of instantaneous current,so as to improve the pertinence of the overall differential protection.On this basis,the longitudinal differential protection setting calculation and instantaneous current grounding protection processing are carried out,and the differential protection is realized by frequency conversion sub-setting correction.The test results show that compared with the traditional magnetic balance differential protection test group and the traditional circulating differential protection test group,the final misoperation rate of the instantaneous current motor differential protection test group designed this time is relatively low,and is well controlled below 20%,indicating that the protection effect is better during the operation of the motor,and has practical application value.