一种新型低频减载方案的研究

在突然恶性事故情况下，由于发电厂的退出，电力系统有可能产生严重的频率下降，导致系统崩溃和大面积停电事故。低频减载装置无疑是一种抑制频率下降的有效方法。它依据测量到的频率值，按轮次分步骤地减负荷。显然，此时的电力系统特性已经变化，而低频减频（UFLS）装置却没有做出相应的修正，仍然是在全系统范围内切除预接负荷。作设计了一种新的减负荷方案，它利用频率和电压的变化，针对每一种事故情况，特别是在承受较大扰动的地区切负荷，以求达到供需平衡。对互联系统的严重功率缺额的模拟研究表明，新的减负荷方案明显优于现有的低频减载（UFLS）方案。

A NEW LOAD SHEDDING SCHEME FOR LIMITING UNDERFREQUENCY

When malignant fault suddenly takes place in power system, along with the outage of some power plants the serious frequency drop may appear which leads the system to collapse or causes large area power supply interruption. Undoubtedly, the under frequency load shedding (UFLS) is an effective method to restrain frequency drop and most of UFLS devices use pre specified step to shed loads according the measured value of frequency. It should be pointed out that although the characteristics of power system is changed under malignant fault, but the UFLS device is not correspondingly revised, it still sheds loads in the range of whole system at pre specified steps, thus, the over shedding or under shedding may occur. In this paper a new load shedding project is presented, by use of the variation of voltage and current which sheds loads in the light of each fault, especially in the most affected localities, to regain the load generation balance after each occurred incident. The simulation researches on the serious power shortage in interconnected system show that the presented load shedding project is much better than the existing UFLS sccheme.