【作者】 姚伟；

【导师】 程时杰； 文劲宇；

【作者基本信息】 华中科技大学 ， 电力系统及其自动化， 2010， 博士

【摘要】 随着互联电力系统规模和复杂度的不断增加,基于就地反馈信号的控制器越来越难以保证互联电力系统的稳定性。信息处理和网络通信技术的迅猛发展和在电力系统的应用,尤其是同步相量技术和广域测量系统的应用,给电力系统的监控提供了使用全局信息的可能。而在广域测量系统中,广域信息是通过通信网络传输的,这将不可避免地存在信息的通信延迟问题。通信延迟使得电力系统成为时滞电力系统,它的存在降低了电力系统的稳定性甚至使其变得不稳定。本文针对时滞电力系统的稳定性和控制进行了相应的分析研究。论文在回顾时滞电力系统的时滞产生原因以及其稳定分析和控制研究现状的基础上,指出了时滞电力系统稳定分析和控制的主要难点。针对时滞电力系统的特点,采用时变时滞相关稳定性判据对时滞电力系统进行稳定分析,并将可以补偿网络延迟的网络预测控制应用于时滞电力系统的控制。全文由以下几个部分组成：首先分别介绍了基于自由权矩阵的保守性小的线性单时变时滞系统和线性多时滞系统的稳定性判据,并给出了采用线性矩阵不等式求解线性时滞系统时滞稳定裕度的两种方法。简要给出了网络预测控制系统的基本结构,分别给出了基于受控自回归滑动平均模型和基于受控自回归积分滑动平均模型的两种网络预测控制算法。该方法在改进的广义预测控制的基础上,增加了网络延迟补偿器来补偿通信延迟。与传统的广义预测控制只利用一步控制信号相比,该网络预测控制不仅利用了全部的预测控制信息,还同时能够补偿固定和随机通信延迟。其次,研究了含有一个广域阻尼控制器的电力系统时变时滞相关稳定性问题。利用单时变时滞稳定判据计算了含有广域阻尼控制器的电力系统的时滞稳定裕度。计算表明,时滞稳定裕度可以用来整定广域阻尼控制器的参数,以保证系统在有足够大时滞稳定裕度的同时也有较好的阻尼效果。再次,分别用单时滞相关和多时滞稳定性判据对采用常规PI控制器的单区域和两区域负荷频率控制系统进行时滞相关稳定性分析。研究了PI控制器增益和时滞稳定裕度之间的关系,并采用时域仿真的方法验证了时滞相关稳定性判据的有效性。第四部分,设计了一种基于受控自回归积分滑动平均模型网络预测负荷频率控制的策略,并对三区域负荷频率控制系统进行了仿真研究,在仿真中考虑了发电机组功率速率约束的影响,仿真结果验证了本文所提出的负荷频率控制策略的有效性,且该控制器结构简单,便于在线实现。第五部分,提出了一种基于网络预测控制的广域阻尼控制器的设计方法。预测模型采用带变遗忘因子的递归最小二乘法在线辨识获得。四机两区域电力系统的仿真结果表明,基于网络预测控制的广域阻尼控制器能够有效地补偿固定和随机通信延迟的影响。此外,该广域阻尼控制器还具有算法和结构简单、易于在线实现的优点。最后,以含有静态无功补偿器(SVC)的新英格兰电力系统为例,通过对系统线性模型的可控／可观度分析,选择SVC的常规附加阻尼控制器的广域输入信号,采用留数法计算得出其参数。在此基础上,用时滞相关稳定性判据分析了含有SVC的常规附加阻尼控制器电力系统的时滞稳定性,根据分析结果设计了考虑时滞影响的SVC附加阻尼控制器。仿真结果表明,考虑时滞影响的SVC附加阻尼控制器不仅能够有效地阻尼系统区域间低频振荡而且可以增强系统的时滞鲁棒性。更多还原

【Abstract】 With the increasing of scale and complexity of the interconnected power system, the local controllers, in which the local measurements are employed as the feedback signals, are increasingly difficult to maintain the stability of the interconnected power system. The rapid development of the synchronized phasor technology and wide-area measurement system (WAMS) provides an opportunity to apply global signals to monitor and control the power system. The signals transmit from WAMS via communication networks will inevitably introduce time delays into the control loop. Those time delays will degrade the dynamic performance of the power system and may even cause the instability of the whole power systems.The main objective of this thesis is to investigate the the delay-dependent stability analysis and control of the power systems with time delays. Power system exsiting communication delays, and the current research backgrounds and results in the field of time-delay power system stability analysis and control are presented. Then, the main difficulties of the stability analysis and control the time-delay power system have been identified. Two time-varying delay-dependent stability criterions and the networked predictive control (NPC) have been applied for the stability analysis, compensation the network communication delays and control of the time-delay power system, respectively. The structure of the whole thesis is listed as follows:Firstly, two novel free-weighting matrices based stability criterions with small conservative for the single time-varying delays and multiple time delays linear systems are recalled, two methods, which use the linear matrix inequalities (LMI) to calculate the delay margin of the linear time-delay system, are proposed. After giving the basic principle and structure of the NPC system, two NPC control strategies, based on the controlled auto-regressive moving average (CARMA) model and the controlled auto-regressive integrated moving average (CARIMA) model, are stated, respectively. These NPC methods, based on the modified generalized predictive control (MGPC), increase networked delay compensator (NDC) to compensate the communication delays. Compared with the traditional GPC, which is only use one step predictive control signal, the NPC uses all of the predictive control sequence to compensate the communication delays.Secondly, the delay-dependent stability of the power systems with a wide-area damping controller (WADC) embedded is analyzed. The stability criterion of the linear system with single time-varying delay is applied to calculate its delay margin. Calculated results show the delay margin can be used to tune the parameters of the WADC to ensure the power system have both large enough delay margin and good damping performances.Thirdly, the delay-dependent stability criterions with single and multiple delays are employed to analyze one-area and two-area load frequency control (LFC) system with the conventional PI controllers. The relationships between the delay margin and the PI controller parameters are studied. Moreover, time-domain simulation method is used to verify the effectiveness of calculated delay margin.Fourthly, a decentralized LFC controller is designed based on NPC considering the communication delays. Then, this decentralized LFC controller is applied in three-area LFC system for the case study. The generation rate constraints are considered in the simulation. The simulation results validate the effectiveness of the proposed decentralized LFC controller. Furthermore, this proposed controller is relatively simple and easy to implement online.Fifthly, a WADC based on NPC is designed. CARMA model is used as predictive model is identified online by using the recursive least-squares (RLS) with a variable forgetting factor algorithm. The design of the proposed WADC is carried out and verified based on the two-area four-machine benchmark power system. The simulation results show that the proposed WADC can improve the damping performances of the inter-area oscillation and effectively compensate both the constant and random communication delays. In addition, the structure and algorithm of the proposed WADC are simple and easy for online implementation.Finally, the conventional wide-area supplementary damping controller (WSDC) of static Var compensator (SVC) has been investigated. The New England test power system (NETPS) equipped with a SVC is used as the test system. At first, the input wide-area signal of the WSDC is selected by analyzing the controllability/observability of linear model of the NETPS. Then, the residue method is used to determine the parameters of the conventional WSDC. The delay-dependent stability of the closed-loop power system is analyzed. The gain of the conventional WSDC is determined by using the analysis results. Simulation results are presented to show that the designed conventional WSDC of the SVC can improve the damping performances and handle a relative large communication delays.更多还原