高比例新能源电力系统振荡机理及其分析方法研究综述

Review on Oscillation Mechanism and Analysis Methods of High Proportion Renewable Energy Power System

高比例新能源通过大量电力电子变换器并网给电力系统的动态特性带来影响,一些振荡问题逐渐凸显。是目前电力电子化电力系统领域广受关注的重要问题之一。为了深入研究高比例新能源电力系统的振荡问题,对新能源电力系统振荡机理分类和振荡分析方法展开介绍。首先借助LC振荡电路从解析角度对负阻尼振荡、强迫振荡(外共振)和自谐振(内共振)等振荡机理和特点做出总结,结果表明正负阻尼都可能引起系统失稳,不同振荡机理引起的振荡波形相似但起因却并不一定相同,另外多机并网系统存在密集振荡模式,并在某种参数微小交互作用下引起系统快速失稳;在此基础上,进一步对各类振荡稳定性分析方法展开介绍,其中特征值法和阻抗/转矩法相对适用于分析负阻尼振荡,开环模式谐振法主要针对内共振现象,此外还特别介绍了电力系统领域中用于分析密集振荡以及谐振问题的复模态摄动法和模态分析法在电力电子并网系统中的应用;最后,伴随新能源输入波动性和随机性问题对电力系统影响逐渐加重,振荡稳定性问题日益复杂且无规则,从振荡机理和振荡分析理论及方法等方面对未来高比例新能源电力系统提出了展望。

A large number of power electronic converters are connected to the grid by a high proportion of renewable energy sources,which leads to endless power system oscillation problems,which is one of the important issues that have received widespread attention in the field of power systems.In order to further study the oscillation problem of high proportion of renewable energy power system,this paper introduces the classification of oscillation mechanism and stability analysis method of renewable energy power system.Firstly,with the help of LC oscillation circuit,the oscillation mechanism and characteristics of negative damping oscillation,forced oscillation(external resonance)and self-resonance(internal resonance)are summarized from an analytical perspective.The results reveal that both positive and negative damping may cause system instability.The oscillation waveforms are similar but the causes are not necessarily the same.In addition,the multi-machine grid-connected system has close oscillation modes,which causes system instability under the slight interaction of certain parameters;on this basis,this paper further introduces the analysis methods of various oscillations.Among them,the eigenvalue method and the impedance/torque method are suitable for analyzing negative damping oscillations.The open-loop mode resonance method mainly focuses on internal resonance.In addition,this paper also introduces the application of complex modal perturbation method and modal analysis method in power electronic grid-connected systems,which are usually used for the analysis of close-mode oscillations and resonances in the field of power systems.Finally,with the increasing impact of the renewable energy input volatility and randomness on the power system,the stability problem is increasingly complex and irregular.This paper puts forward the prospect of the future high-proportion renewable energy power system from the aspects of the discrimination,positioning,analysis theory and method of the oscillation mechanism type.