【作者】 刘刃；

【导师】 廖勇；

【作者基本信息】 重庆大学 ， 电气工程， 2008， 博士

【摘要】 对于以传统同步发电机作为主要发电设备的现代电力系统,随着快速励磁系统的引入,削弱了机电振荡模式的阻尼,使机电振荡模式呈现弱阻尼甚至负阻尼,导致电力系统振荡失稳问题变得日益突出。异步化汽轮发电机作为一种新型发电机,其转子结构和励磁控制的特点,使其具有超越传统同步发电机的优良运行性能和阻尼特性。论文主要针对电力系统的低频振荡问题,从异步化汽轮发电机的阻尼特性出发,通过在电力系统中引入异步化汽轮发电机部分取代传统同步发电机后,对电力系统低频振荡的抑制作用进行了深入研究。论文首先对异步化汽轮发电机在单机无穷大系统下的稳态和暂态运行性能进行了研究,指出采用双通道励磁控制策略的异步化汽轮发电机具有独立的有功和无功调节、深度吸无功进相运行以及无功(电压)调节的快速响应性等超越传统同步发电机的优良稳态运行性能,以及在暂态过程中实现励磁磁场最佳定向,维持较大电磁转矩和电压稳定的良好暂态运行性能,指出异步化汽轮发电机为解决超高压和长距离输电系统的稳定问题以及由无功过剩所引起的持续工频过电压问题提供了新的途径。论文从阻尼角度对现代电力系统产生低频振荡的原因进行了分析,指出传统同步发电机采用以机端电压作为反馈的快速励磁控制系统可能削弱系统的机电模式阻尼,使系统的机电振荡模式呈现弱阻尼甚至负阻尼,从而导致电力系统出现低频振荡现象;同时指出抑制电力系统低频振荡最根本的措施就是增强系统的机电模式阻尼,抵消由快速励磁系统引起的负阻尼效应。论文详细分析了异步化汽轮发电机的阻尼特性,尤其对双通道励磁控制策略下异步化汽轮发电机的闭环阻尼特性进行了深入的研究,并与传统同步发电机的阻尼特性进行了对比分析,结果表明异步化汽轮发电机的阻尼特性要明显优于传统同步发电机,单机无穷大系统下异步化汽轮发电机的同步转矩系数和阻尼转矩系数与发电机的运行状态无关,而仅与励磁控制系数、发电机参数和输电线路参数有关,通过励磁控制的调节可对同步转矩系数和阻尼转矩系数进行改善,使系统具有良好的稳定性和足够的阻尼。论文建立了含异步化汽轮发电机并考虑阻尼绕组作用的多机电力系统线性化数学模型,在分析异步化汽轮发电机阻尼特性的基础上,提出了在电力系统中利用异步化汽轮发电机部分取代传统同步发电机来有效抑制低频振荡的理论和方法,并对含异步化汽轮发电机的电力系统进行了关于低频振荡问题的仿真研究和验证,从仿真角度论证了异步化汽轮发电机的引入对电力系统低频振荡的有效抑制作用。论文将电力系统引入异步化汽轮发电机后对低频振荡的抑制作用和电力系统稳定器对低频振荡的抑制作用进行了对比研究,指出异步化汽轮发电机在有效抑制电力系统低频振荡的同时,还能够提高系统的暂态稳定性,同时具有吸收过剩无功等综合作用,因此在提高电力系统稳定性方面能够发挥更大的作用。论文将异步化汽轮发电机的研究重点从发电机本体转移到电力系统,从电力系统的角度对异步化汽轮发电机进行研究,所取得的研究成果对于异步化汽轮发电机投入工程实际应用具有重要的理论价值。更多还原

【Abstract】 In the modern power system with the conventional synchronous generator as major power generation equipment, the rapid excitation system of generators has weakened the damping of the electrical and mechanical oscillation mode, so the electrical and mechanical oscillation mode showed weak or even negative damping that leading to unstable power system oscillations change issues in the increasingly prominent. The asynchronized turbogenerator as a new generator, owing to the rotor structure and excitation control, goes beyond the conventional synchronous generator with the excellent performance and damping characteristics. In this paper mainly aiming at the low-frequency oscillations of power system, based on the damping characteristics of the asynchronized turbogenerator, the low-frequency oscillations of the power system have been deeply researched when the asynchronized turbogenerator partly replacing the conventional synchronous generator in power system.Firstly the steady-state and transient-state operation of the asynchronized turbogenerator was studied in the one-machine infinite-bus power system. The results showed that the asynchronized turbogenerator under the dual-channel excitation control strategy has the fine steady operating performances beyond the conventional synchronous generator such as independent active and reactive power regulation, in-depth absorption into reactive power and the rapid response reactive power(voltage) regulation, as well as the transient process of achieving optimal excitation magnetic field orientation, maintaining larger electromagnetic torque and good transient voltage stability. The asynchronized turbogenerator has supplied a new way to solve the problems of continuous over voltage on extra-high voltage transmission lines due to the surplus of reactive power and the stability of power systems with long distance transmission line.The causes has been analysed that producing the low-frequency oscillation of modern power system from the perspective of damping. The results showed that the rapid excitation control system of conventional synchronous generator with voltage as feedback may weaken the damping of the electrical and mechanical oscillation mode, and the electrical and mechanical oscillation mode shows weak or even negative damping, that resulting the low frequency oscillation phenomenon in the power system, and the results pointed out that the most fundamental measure restraining low frequency oscillation is to enhance the damping of the electrical and mechanical oscillation mode, offset the negative damping effect by the rapid excitation system.The damping characteristics of the asynchronized turbogenerator has been detailed analysed, particularly the closed-loop damping characteristics of the asynchronized turbogenerator under dual-channel excitation control strategy was in-depth researched, and was compared with the damping characteristics of the conventional synchronous generator. The results showed that the damping characteristics of the asynchronized turbogenerator is superior to conventional synchronous generator, such as in the one-machine infinite-bus power system synchronous torque coefficient and damping torque coefficient is independent of the operational status of generators, but is only dependent on the excitation control parameters, the generator parameters and the transmission line parameters, through the regulation of excitation control parameters can improve synchronous torque coefficient and damping torque coefficient and the power system has a good stability and adequate damping.In this paper the linear mathematical model of the multi-machine power system was established including the asynchronized turbogenerator with the damping windings. Based on the damping characteristics of the asynchronized turbogenerator, the theory and methods of effectively restraining low frequency oscillation that the asynchronized turbogenerator partly replaces the conventional synchronous generator has been proposed, and the simulation results validate the theory and methods.The effect of restraining low-frequency oscillations was compared between the asynchronized turbogenerator and power system stabilizer (PSS), the rsults showed that the asynchronized turbogenerator not only can effectively restrain low-frequency oscillations of the power system, but also can improve transient stability, absorb surplus reactive and so on, thus the asynchronized turbogenerator can play a greater role on improving the stability of the power system.In this paper the focus on researching the asynchronized turbogenerator is to the multi-machine power system, and not to the generator individual. The research results have important theoretical value to the practical application of the asynchronized turbogenerator.更多还原