【作者】 何金平；

【导师】 毛承雄； 陆继明； Lee Wei-Jen；

【作者基本信息】 华中科技大学 ， 电力系统及其自动化， 2012， 博士

【摘要】 电力的生产和消耗是电力系统中的两大关键环节,电能的高效利用和安全生产对于电力事业的发展至关重要。当今能源日益紧缺,电力联网规模日趋宏大,稳定高效一直是电力系统行业关注的焦点。电动机作为电力系统中的用电大户,消耗了整个系统大部分电能。采用传统变频器拖动的电动机产生了大量的再生电能,而这部分能量白白的消耗在了制动单元上,这不符合国家提出的提倡建设节约型社会、倡导节能减排的思想。另一方面,随着西电东送工程的建设和区域电网联网,阻尼不足及低频振荡问题严重影响系统的稳定,研究新型励磁系统提高系统稳定性具有实际意义。电压源型变换器因其良好的控制特性及灵活的结构,在电力系统中得到了越来越广泛的应用。本文研究电压源型PWM变换器在电梯节能、抽油机节能以及全控器件励磁系统中的控制与应用,主要有以下几个方面的内容：首先研究了基于电压源型数字式能量回馈装置的基本原理,详细阐述了电压源型数字式能量回馈装置的设计与实现过程,包括主回路设计,器件参数选型,控制电路及外围电路设计,控制程序设计等。实验表明,装置能够良好的适应网侧电压的较大范围变化,并保持接近单位功率因数运行；直流侧回馈点电压上下限能够灵活调节；通过现场长时间运行,表明装置运行可靠,不会对原有系统造成不利影响,通过长时间数据记录,显示电梯在使用数字式能量回馈单元后,具有明显的节电效果。紧接着,本文在分析了游梁式抽油机的运行规律基础上,设计开发了应用于抽油机的双PWM变频器装置,给出了主回路、控制及外设电路、控制程序的具体设计过程。通过实际现场应用,表明装置具有良好的运行性能：接近单位功率因数,无功功率接近零,同时线路压降降低；灵活调节电动机运行速度,在不影响单位时间产油量的同时,降低了有功消耗；通过相关专业监测,表明双PWM变频器在应用于抽油机后,能够极大的提高系统节电率。随后,本文将电压源型PWM变换器应用于励磁系统,分析了全控器件励磁系统的基本运行原理,研究了机端注入无功电流对发电机系统等效阻尼系数的影响,并提出了基于电压源型PWM变换器串联DC/DC斩波器的全控励磁系统的控制策略。通过仿真分析,表明全控器件励磁能够有效的提高系统阻尼,随着补偿容量的提高,效果更加明显,并具有提高发电机的动稳极限,提高系统稳定运行的能力。最后,本文建立了基于三阶同步发电机模型的全控器件励磁系统等效模型,并依据此模型,提出了两输入、两输出的状态变量反馈线性化控制策略,通过仿真分析,将这种非线性控制与传统的线性控制AVR+PSS)做了比较,结果表明,基于状态变量反馈线性化的控制能够有效的提高系统阻尼,并且随补偿容量的增大,阻尼效果越明显；相对于线性控制,非线性控制方法具有更好的适应性。更多还原

【Abstract】 The production and consumption of electricity are two main key points in power system, and its efficiency and safety is very important in the development of power engineering. In nowadays, as the short of energy and the expansion of the power grid, stability and efficiency are always the focus in power system research.Inductive motor is the main consumer of power in the power system. Under the drive of frequency converter, it can produce huge regenerative energy which was always wasted through the break unit. This way is not cooperate with the strategy of construct energy saving society and reduce exhaust. And another aspect, with the construction of’west to east power transmission’and the connection of area grid, the problem of lack damping and low frequency oscillation became a serious problem. So the research on a new excitation system has its practical significance.The PWM converter of voltage source has been used more and more in power system because of its good controllability and flexible structure. This dissertation mainly studies on the usage of this kind converter in energy saving field:lift, oil pump unit and the excitation system as follows:First is the research on the basic theory of digital energy feedback device based on the voltage source converter, and talked about its process of design and implementation in details, include the design of main circuit, the calculation of component parameters, and the design of control circuit, peripheral circuit and control program. The experiment results indicated that, the device can adapt to the voltage’s big deviation and keep unit power factor; the voltage of feedback point can be adjust in a certain range. Through a long time operation in the lift field, the device worked well, and has no passive impact to the frequency converter. And its record indicated that after the installation of the energy feedback device, the lift has a remarkable energy saving effectThen this dissertation analyzed the beam pumping unit’s motion low in petroleum exploitation, and designed a dual PWM frequency converter; include the main circuit, control circuit, peripheral circuit and the control program. After the field operation, the device worked well with perfect performance:nearly unit power factor, zero reactive power, reduced line voltage drop, flexible speed adjusting. It can reduce much consumption of active power with no impact to the oil production. Through the professional testing, after the installation of the dual PWM frequency converter, the beam pump unit has a remarkable energy saving effect.Then the voltage source PWM converter was used in the excitation system:analyzed the principle of how the injected reactive current affects the electric power of generator compensates proper current will increase the damping of generator. And a control strategy of voltage source converter excitation system based on full controlled devices was designed, that using three phase full bridge PWM converter as exciter. The simulation results show that, this kind of voltage source converter excitation system can supply more damping to system through another way, and also increase the dynamic stability of the generator. The larger capacity of the compensation system, the more damping there will be.At last, this dissertation deduced a third-order model of this kind of excitation system. And with the main goal of controlling the rotor angle as well as the terminal voltage, a MIMO nonlinear control strategy was designed through this model. The simulation results show that, comparing to the linear control scheme (AVR+PSS), this nonlinear scheme has better effect in enhancing the system’s damping, with the compensation capacity increase, and better effect can be achieved; when system parameters changed, still has a good performance and better suitability.更多还原