【作者】 何飞跃；

【导师】 段献忠；

【作者基本信息】 华中科技大学 ， 电力系统及其自动化， 2006， 博士

【摘要】 现代大型电网的安全控制是一个没有很好解决的复杂问题,2003年的美加大停电便是例证,美国《技术评论》杂志因此将其列为九个开拓性的新兴科技领域之一。电力系统中现有的各种控制系统,如电网紧急控制、EMS/SCADA、无功电压控制、继电保护、综合自动化,各自相互独立,且大都采用点对点的专线通信方式,如果将基于网络的控制系统(NCS)技术引入电力系统,可望为解决大系统的安全控制问题提供一条崭新的途径。本文在国家自然科学基金重大项目子课题的资助下,以电力网络化控制为主题,对AGC、水电机组、TCSC系统的控制,网络性能对控制系统的影响以及电力系统信息综合传输网络的控制展开研究。阐述了网络化控制系统的基本原理和构成,从理论上对网络化控制系统中的模型、节点驱动方式、延迟、资源调度进行了定性研究。运用网络演算理论给出了网络化控制系统的延迟上界。提出了将已有的实时调度算法运用于网络化控制系统中的思想。详细分析了电力系统实现网络化控制中的信息综合传输、通信时延对系统的影响、网络化控制系统的信息安全、多采样率和同步采样问题,并探讨了有效的解决方案。研究了网络性能对控制系统的影响,采用Truetime网络化控制仿真工具箱,选择励磁系统作为控制对象进行了仿真研究。对励磁系统网络化控制中的资源调度、节点驱动方式和通信网络的选择进行了研究。仿真分析验证了在资源调度方面,动态调度EDF算法可以有效保证网络化控制系统的性能,采用事件驱动方式可以有效避免网络化控制系统中的空采样和信息丢弃问题,在通信网络选择方面,采用高带宽和具有优先级机制的交换式以太网可以在信息综合传输网络中保证励磁系统网络化的控制性能。提出了网络化AGC控制模式,运用时滞动力系统理论建立了网络化AGC控制系统的模型。对时滞动力系统中的时滞依赖性稳定性条件和时滞独立稳定条件进行了比较分析,针对时滞独立性稳定性条件保守性大、条件严格的弱点,从解决工程实际问题的角度,提出了基于时滞依赖性稳定条件的鲁棒控制器设计方法。通过两区域的网络化AGC控制系统仿真研究表明,根据时滞依赖性稳定条件设计的控制器具有较小的保守性和良好的控制效果。研究了基于网络化控制系统的水电机组控制模式,探讨了其实现方法。建立了网络化控制系统延迟的乘性摄动模型,得出了基于μ综合控制理论的水电机组网络化鲁棒控制框架,求得了具有稳定鲁棒性和性能鲁棒性的控制器。对水电机组的频率和负荷扰动仿真分析表明,μ综合控制器比H∞控制器和常规的PID控制器具有良好的控制效果。提出了基于广域测量信号的TCSC网络化控制方案。为将包含通信延迟的TCSC网络化控制模型转化不含延迟的常规控制系统模型,本文采用了引入增广状态方程的方案,并根据工程实际的需要,采用离散滑模变结构控制的思想,进行了控制器的设计。针对滑模变结构中的抖振问题,采用了有效的解决方案。仿真分析表明滑模控制器的有效性。在分析了现有IP QoS模型的基础上,针对电力系统信息业务的特点,提出了基于多协议标签交换(MPLS)的电力系统信息综合传输模式。对电力系统的信息特性进行了分析和建模,采用OPNET网络仿真工具对电力系统信息综合传输的仿真表明, MPLS+DiffServ网络比单纯的DiffServ网络更能有效地解决了电力系统信息综合传输中的拥塞问题,保证实时控制信息传输的时延和通信可靠性要求。更多还原

【Abstract】 Security control for modern large power grids is a complicated problem with no perfect solution for the time being—the 8.14 blackout that occurred in North America in 2003 substantiated the difficulty to solve the problem. It has been listed as one of the nine pioneer fields of new technology in the journal of Technical Review of America. The control systems used in power system, such as power system emergency control, EMS/SCADA, or voltage and reactive power control, power system protection, and substation automation, all work independently and communicate by peer to peer via private network. In that case, introducing NCS technology to power system will provide a novel solution to the problem of large system security control. Our study, funded by National Science Foundation of China, aims to deal with this problem, especially such aspects as network performance effect on control performance, hydroturbine generating unit, AGC, TCSC and power system integrative information transmission.Firstly, this paper describes the fundamentals of the theory of NCS, including the model, node driven mode, time delay, task schedule and network schedule problems. The upper threshold of time delay in NCS is then presented by means of the network calculus theory, and the idea of using well developed real-time schedule algorithm in NCS is put forward. Based on the proposed NCS theory, some problems in power system NCS are analyzed, including integrative information transmission, impact of time delay on the controlled system, information security, multi-rate sampling, and synchronized sampling, and then the effective solutions to the problems are given.Secondly, in order to study the network performance effects on NCS, the networked excitation system is studied and simulated with networked control simulation tool True time toolbox. The issues of task schedule, network schedule, node driven mode and communication network type in power system excitation system are then addressed. The results of simulation analysis validate that dynamic schedule EDF algorithm can guarantee the performance of networked excitation system in task schedule and network schedule, that event driven mode can perfectly avoid vacant sampling problem in NCS, and that the Ethernet with high band and priority mechanism can guarantee the performance of the NCS based excitation system.Furthermore, a networked AGC model is proposed based on the time-delay dynamic system theory. The time delay dependent stability cretia and the time delay independent stability cretia are compared. As the latter is more conservative and strict in engineering application, a robust controller designed with the former cretia is proposed. The digital simulation of networked AGC demonstrates that the controller designed with the time delay dependent stability cretia has lower conserativity and better performance.The networked based hydroturbine generation unit and its realization are also dealt with in this paper. The uncertain model of time delay is built by the multiplicative perturbations model, and the robust control structure of networked hydroturbine generating unit is thereby deduced; then a controller with both robust stability and performance robustness is designed. The simulation of frequency and load perturbation indicate thatμcontroller has superior control effect than H∞controller and conventional PID controller.Next, the wide-area measuring system (WAMS) based on TCSC networked control strategy is presented. In order to transform the TCSC model with time delay to the conventional model without time delay, the augmented status is introduced. The controller design is based on the discrete sliding mode control theory so as to meet the demand of engineering application. A feasible improvement approach solution is also proposed to overcome the chattering problem. In addition, a single machine to infinite bus system is studied through digital simulations to demonstrate the comprehensive applications of the proposed strategy.Finally, after analyzing the conventional IP QoS model, an integrated information transmission mode based on MPLS is proposed with the characteristics of information transmission in power system in consideration. The results of network simulation indicate that MPLS + DiffServ network has better performance than DiffServ network alone in the power information congestion control, and that it guarantees the time delay and communication reliability of real time control information transmission.更多还原