【作者】 戚军；

【导师】 曹一家；

【作者基本信息】 浙江大学 ， 电气工程， 2009， 博士

【摘要】 全国电网互联使电力系统的规模越来越大、运行状态越来越多变,互联电力系统中出现了严重危害系统稳定运行的低频／超低频振荡。广域测量系统(WAMS)的出现为广域电力系统的稳定分析和控制提供了新的契机。考虑到广域测量信号带有不可忽略的时滞,采用广域测量信号作为输出反馈的区间低频振荡阻尼控制器的设计必须考虑时滞的影响。目前,考虑广域输出反馈信号时滞影响的电力系统区间低频振荡阻尼控制的研究仍处于初始阶段；因此,探索新理论、新技术和新方法,研究适用于大型互联电力系统的时滞输出反馈鲁棒阻尼控制器来抑制区间低频振荡,具有重要的理论意义和工程应用价值。围绕这一主题,全文的内容主要包括以下几个部分：第一部分利用WAMS提供的大量实时准确的广域测量信号,提出了一种通用的Prony辨识算法来快速获取电力系统降阶传递函数模型,避免了小信号分析法中繁杂的系统元件建模／模型更新过程。该算法允许待辨识系统初始状态非零,可采用任意类型的激励信号,并能综合处理多时段数据。仿真分析结果表明,通用Prony辨识方法能准确辨识初始状态和传递函数,计算速度快且几乎不随系统规模而变化,辨识方法具备在线应用的潜力。第二部分针对电力系统区间低频振荡问题,提出了两种利用时滞广域测量信号的电力系统鲁棒阻尼控制器的设计方法。其中,第一种方法适用于单输入-单输出控制,该方法采用通用Prony传递函数辨识法和纯时滞环节Pade逼近法建立时滞电力系统模型,然后基于混合灵敏度H∞控制理论和极点配置方法设计阻尼控制器；第二种方法适用于多输入-多输出控制,该方法结合时滞依赖状态反馈鲁棒控制和状态观测理论,实现了广域电力系统的时滞输出反馈鲁棒控制。仿真实例表明,这两种时滞鲁棒阻尼控制器都能够显著抑制系统区间低频振荡,并且具有时滞不敏感性和运行条件鲁棒性。第三部分基于WAMS提供的电力系统惯量中心(COI)数据,建立了COI参考坐标系下完全解耦的发电机模型,并根据Lyapunov理论和反步法思想,提出了一种简单实用的分散非线性励磁控制方法。仿真结果表明,这种非线性励磁控制器不仅对发电机参数、运行状态和负荷类型具有良好的鲁棒性,而且允许COI信号存在较大的时滞。基于这个发现,进一步提出了一种时滞广域测量信号的选择策略,以此来降低时滞对控制性能的影响、简化控制器的设计。更多还原

【Abstract】 With interconnection of power grids, power system size becomes larger, and operation condition becomes more variable. In operation of interconnected power systems, there are low/ultra-low frequency oscillations, which drastically endanger system stability. The emerging of wide-area measurement systems (WAMS) provides new opportunities for the analysis and control of wide area power systems. Since there is an unavoidable time delay in wide-area measurements, it is necessary to take delay into consideration when wide-area measurements are adopted as output feedback signals of damping controller for inter-area low frequency oscillations.At present, design of inter-area low frequency oscillation damping control, which considers time delay effect introduced by wide-area output feedback signals, is on the elementary stage, and there are still many problems to be explored thoroughly. Therefore, exploring the new theory, new technology and new method, researching on delayed output feedback robust damping control to inhibit inter-area low frequency oscillations in large power systems, have enormous theoretic and project significance. The dissertation consists of three main parts as follows:In the first part, by adopting large number of real-time accurate wide-area measurements from WAMS, a general Prony algorithm for transfer function identification is brought forward, in order to obtain the reduced model of power systems with no need to model/remodel every device in power system in detail. This algorithm permits the appearance of non-zero initial states and any type of pumping signals in the system to be identified, and could deal with multiple time-intervals situation. Simulation and analysis results show that this algorithm identifies initial states and transfer function accurately; moreover computation-time for identification is short and almost identical when system size changes. The general Prony identification algorithm is promising for online applications.In the second part, for inter-area low-frequency oscillation in power systems, two novel strategies for robust damping controller design using time delayed wide-area measurements are proposed. One of them is applicable to single-input single-output control. Time delay model of power system is established by employing general Prony identification of transfer function and Pade approximation of dead time delay. The damping controller is designed based on the mixed-sensitivity Hoo control theory and pole placement approach. Another one of them is applicable to multi-input multi-output control. Combining theories of delay-dependent state-feedback robust control and state observer, time-delay output feedback robust control is realized for wide-area power system. Small signal analyses and time-domain simulations demonstrate that these two controllers can inhibit inter-area low frequency oscillations evidently; meanwhile they are insensitive to time delay and robust to operating conditions.In the third part, based on the centre of inertia (COI) data provided by WAMS in power systems, completely decoupled generator model is constructed within COI-reference coordinate frame. According to Lyapunov theory and back-stepping concept, a simple and practical method is brought forward for decentralized nonlinear excitation control design. Simulation results show that this nonlinear excitation controller is robust to generator parameters, operating conditions and load types; meanwhile it allows the existence of relatively large time delays in COI signals. Based on this discovery, a novel strategy for time delay wide-area measurements selection is proposed in order to depress delay effects on control performance and simplify control design.更多还原