基于数字微分算法的电力参数快速准确估算

提出了一种基于数字微分和拉格朗日插值的、在较大范围内实现电力参数的频率、幅值和相角的快速而准确的测量算法。利用数字微分,电力系统的频率、电压幅值和相角可以在1个半周波的时间内得到准确测量,其测量精度达到99.999%。提出的算法分两步进行,第一步为频率估算;第二步为第一幅值和相角计算。该算法适应于电压信号在1～100Hz,电压幅值在160～280V,相角在0°～360°的场合,而且耗时短、计算量小,因而非常适合应用于实时性要求高的应用系统中。该文给出一实例,并在Matlab上进行仿真,其结果令人满意。

Measurement and prohibition of surge on microprocessor based protective relay

This paper makes an analysis of the characteristic of the surge disturbance. A number of Surge Protective Devices (SPD), such as gas tube arresters, metal oxide variators, transient voltage suppressors (TVS), are tested. And their main technical parameters, including response time, the level of the residual voltage, maximum peak pulse current and life times, are compared. Consequently a series of tests are performed on a microprocessor based protective relay taking account of the standard of IEC 61000-4-5. Then the responses of surge disturbance on each port of the relay are measured. According to the analysis of the data gained, some advice is put forward to restrain the surge disturbance. Diverse protective measures should be taken since the surge disturbance applied on each port differs and the circuit characteristic of each port varies.