【作者】 李潇潇；

【导师】 王宣银；

【作者基本信息】 浙江大学 ， 机械电子工程， 2009， 博士

【摘要】 现代汽轮发电机组的汽门调节控制系统从机械液压调节过渡到了以计算机为核心的数字电液调节(DEH)，摆脱了长期以来可靠性差、调节精度低、稳定性不好的局面，提高了功率、频率的调节品质，但目前我国现有的大部分汽轮机DEH系统不具备汽门快速控制功能。汽轮机汽门快速控制是使电力系统在受到干扰时保持稳定运行的一种经济有效的措施，如果应用在电网结构比较薄弱的地区，可大幅度的提高电力系统的暂态稳定水平。本文以200MW汽轮机数字电液调节控制系统作为研究对象，对电网故障时汽门快速控制的原理和机构设计与优化控制进行了系统的理论分析与实验研究。同时对DEH系统的泄漏、堵塞、卡涩等故障诊断及其容错控制进行研究。分析了电网故障下汽门快速控制的作用原理，提出了对汽轮机DEH系统实现电液快控的新方法与优化控制策略，对所设计的快控系统进行了系统的理论分析与实验研究。同时，研究了DEH系统的故障机理和诊断方法，并首次提出基于位移、流量、压力反馈的汽轮机DEH系统容错控制方法。论文各章内容分述如下：第一章，阐述了本课题的相关研究背景和意义，在查阅国内外相关研究文献的基础上，综述了汽轮机调节系统的研究发展和应用现状，介绍了汽轮机快控系统的特点及应用，分析了汽轮机调节系统研究所面临的主要问题，给出了本课题的研究内容。第二章，完成了由机液调节系统到电液调节系统的改造并设计了汽轮机新型快控机构。分析了现有快控汽门的常用控制方法，阐述了汽轮机进汽阀门的工作原理及结构特点，对阀门进行了详细的受力分析。对200MW中间再热凝汽式汽轮机的机液调节系统进行电液改造，在此基础上设计出新型快控系统，具有对汽轮机进汽阀门的快速关闭和快速开启功能。第三章，建立快控系统的数学模型并进行仿真与实验研究。对整个电液伺服及快控系统进行数学建模，为全文提供了理论基础。利用AMESIM对调节系统进行了建模与仿真，分析了影响快开系统调节性能的多种因素，研究了快开系统的工作死区，在此基础上提出对死区区间内开度进行恢复的优化控制策略。搭建了快控调节系统实验台并完成了快控系统性能测试实验，对比分析了仿真和实验结果，通过实验验证了快控系统的快速调节性能。第四章，研究了汽轮机电液调节系统的内泄漏问题。首先分析了汽轮机电液系统产生内泄漏的原因，详细分析了系统中几种常见内泄漏故障机理并建立了数学模型，对传统内泄漏故障诊断方法存在的问题进行分析。然后分别研究了调节系统中的油动机、错油门滑阀、伺服比例阀部件在不同内泄漏量和不同泄漏部位下，活塞调节时间、油动机油压、流量等参数的变化情况，比较了对称泄漏和非对称泄漏对系统的影响。在仿真分析基础上给出了对系统内泄漏进行辨识的特征表，最后通过实验对分析结果进行验证。第五章，研究了调节汽门操纵机构的卡涩故障和DEH系统中伺服阀的堵塞故障。分析了汽轮机调节汽门操纵机构的结构和卡涩机理，针对特有的弹簧偏心卡涩故障展开研究，推导出弹簧偏心距的理论计算方程，在此基础上展开三种卡涩诊断方法的研究。对DEI-I系统中伺服阀工作状态下系统的输出信号进行分析，从而提取伺服阀堵塞时的故障特征并进行诊断，在仿真分析基础上得到伺服阀堵塞故障特征表，提出采用双重神经网络并根据据系统中活塞位移、油压等特征量的变化对伺服阀的堵塞情况进行诊断。研制出用于汽轮机DEH系统伺服阀的智能测试与故障分析诊断系统，可对各种常用伺服阀、伺服比例阀、比例阀进行全面的性能测试分析。提出伺服阀静态和动态性能一次测试的思想，首次在伺服阀测试系统中使用插装阀控制油路，系统具有全自动、响应快、流量大等优点，可以完成GB/T 15623-1995中的各项检测实验，对发电厂对伺服阀的检修及故障分析起到重要作用。第六章，提出汽轮机电液调节系统多反馈容错控制新方法。介绍了容错技术在汽轮机电液控制系统中的应用现状，设计了基于位移、流量、压力反馈的FTC汽轮机调节系统，制定了传感器故障诊断规则与容错控制规则，通过建模仿真比较了三种闭环反馈控制方式下系统的调节性能，最后通过实验验证了FTC汽轮机调节系统的可行性。第七章，总结本文的主要工作，阐述了本课题的研究结论和创新点，并对后续研究工作做出了展望。更多还原

【Abstract】 The steam valve regulating system of modern steam turbine unit has transmitted from mechanical hydraulic regulation to digital electro-hydraulic(DEH) regulatinon, which improve the quality of adjusting, realize the complex control algorithm, strengthen the system security and enhance the regulating quality of power and frequency. However, there is no fast control valving function in most DEH systems of our country. Fast control valving is an effective measure that kept the electric power system running stably. Especially when it is applied in area where the electric network structure is weak, the transient stabilization ability of electric power system can be enhanced obviously. In this paper, regulating system in 200MW steam turbine is studied. The protection principle of fast valving under the malfunction of electric network, devise of fast control system and optimization operation tactic are all analyzed and experiment research are made. At the same time, the faults such as interal leakage, plugging and jam in DEH system and fault tolerant control of the system are studied deeply. The chapters of the paper are arranged as following:In chapter 1, the related study background and significance of the subject are expounded. On the basis of referring to domestic and international associated documents, the research development and the current application situation of the regulating system in steam turbine are summarized. Characteristics and application of fast control system in steam turbine are introduced. Then the main problems in the study of the regualting system are analyzed. The main study work is proposed.In chapter 2, retrofit of regulating system from mechanical hydraulic control to elecro-hydraulic control is implemented and new type steam turbine fast valving mechanism is devised. The commonly used control rule of fast valving is analyzed. The operation principle and structure of steam valve is set forth. The forces received by valve are analyzed in detail.The retrofit of regulating system in 200MW reheated condensing steam turbine from mechanical hydraulic control to elecro-hydraulic control is implemented, based on which new type fast valving system is devised. There is function of both fast closing valve and fast opening valve.In chapter 3, the mathematic model of the whole fast valving system is built up and the simulation of and experiment are fulfilled. First the mathematic model of the system is given, providing theoretic basis for paper. With the use of software-AMESIM, the model of regulating system is built up. The factors influencing the performance of fast opening system is analyzed and the operation dead zone is studied, based on which optimization control tactic in dead zone is brought forward. The experiment platform of fast valving system is built up and test is realized.The simulation results and experiment results are compared, which validated the correctness of the devise.In chapter 4, the internal leakage in steam turbine electro-hydraulic system is studied. The reasons of leakage in system are analyzed. Several leakage fault mechanisms and their mathematic models are analyzed in detail. The problems of conventional diagnosis methods of internal leakage are given. The internal leakage of oil servo motor, regulating valve and servo-proportional valve are studied respectively. The changes of parameters including regulating time, oil pressure and so on are compared under the conditions of different internal leakage slit and flux. Besides, the influences of symmetrical and asymmetrical internal leakage on system are also compared. After simulation, characteristic table is given to diagnose internal leakage. In the end of this chapter internal leakage experiment is made to validate the analysis results.In chapter 5, the jam fault in manipulative mechanism of steam turbine regulating system and the plugging fault of servo valve in DEH system are studied. The structure of manipulative mechanism and the jam fault cause are both analyzed. Research is done about the particular jam fault caused by spring excursion and the theory formulas of spring excursion length are educed. Based on theory analysis and simulation three diagnosis methods are studied. The online output signals of DEH regulating system are analyzed in order to extract the fault characteristics of the servo valve directly. Based on simulation the characteristic table of the servo valve plugging is given. With characteristic parameters such as the displacement and the oil pressure, the duo-neural network is put forward to achieve an online diagnose on the plugging fault. Intelligent test and fault diagnosis system for servo valve in DEH system of steam turbine is developed, with which general characteristic analysis on common servo valve, servo-proportional valve and proportional valve can be fulfilled. The idea that static and dynamic characteristics of servo valve are analyzed once is advanced. For the first time cartridge valve is applied in servo valve test system to switch oil pipe. There are many advantages in the system such as full automation, fast response, great flux, and etc, with which test in GB/T 15623-1995 can be implemented. It plays an important role in repair and fault diagnosis of servo valve in power plant.In chapter 6, the fault tolerant control method of steam turbine based on multi-feedback is advanced. First the application situation of fault tolerant technique in steam turbine electro-hydraulic control system is introduced. Then the fault tolerant control regulating system based on displacement, flux and pressure feedback is devised. The fault diagnosis rules of sensors and fault tolerant control rules are put forward. The regulating performance under three closed loop control modes are compared based on simulation. Finally the experiment is carried out to demonstrate the feasibility of the design.In chapter 7, the major work of the study is summarized, and the conclusions and innovations of the study are elaborated. At the same time, future development is predicted in order to provide references for the further research on this project.更多还原