电网系统中基于频率变化率的孤岛效应检测

近年来,分布式发电迅速发展并成为电网的关键技术之一,然而也引发了孤岛效应等稳定性威胁。电网系统的运行状态监测,及时诊断孤岛效应等稳定性威胁,对维护系统稳定、电网管理策略研究具有重要意义。首先,提出了一种基于信号辨识的孤岛监测方案,以频率变化率(RoCoF)表征电力信号的频率波动剧烈程度,作为检测其孤岛、判断系统故障发生的重要依据。然后,分别利用正交锁相环(QPLL)以及插值离散傅里叶变换结合无迹卡尔曼滤波器(IDFT-UKF)的方法设计估计器,实时跟踪信号频率及其变化率。通过深入分析二者的特性与调解律,针对实际电网系统工况,设计鲁棒诊断策略,并通过仿真实验验证其有效性。

Islanding Detection Based on Rate of Change of Frequency in Power Grids

In recent years,distributed generation has been dramatically developed and has become a key technique in the field of power grids.However,it also brings about stability hazards,such as the islanding,threatening the effectiveness and reliability of the overall system.Therefore,the monitoring of the operation status of the power grids and the timely diagnosis of stability threats are of great significance for maintaining system stability and grid management strategy.First of all,an islanding monitoring scheme based on signal identification is proposed,making use of the rate of change of frequency(RoCoF)to characterize the severity of frequency fluctuations of power signals,which is an important basis for detecting islanding and the occurrence of system failures.Two estimators are designed to estimate the frequency and its rate of change based on quadrature phase-locked loop(QPLL)and the interpolated discrete Fourier transform(IDFT).Subsequently,features and tuning rules of the two estimators are analyzed and compared in depth.Concerning the actual scenario of the power grid,a robust estimation-based diagnosis scheme is designed whose effectiveness has been confirmed by extensive numerical experiments.