【作者】 孙会洁；

【导师】 梁小冰；

【作者基本信息】 广西大学 ， 电力系统及其自动化， 2008， 硕士

【摘要】 轻型高压直流输电(VSC-HVDC)技术是在传统直流输电基础上发展起来的一种新型输电技术,其主要部件是以绝缘栅双极晶体管(IGBT)构成的电压源换流器(VSC)。VSC-HVDC凭借着其优越的特性,已经在实际电力系统中得到了广泛地成功应用,但是在理论研究和实际应用中仍然存在很多亟待解决的问题。与传统HVDC相比,VSC-HVDC可以同时控制有功功率和无功功率是一个非常重要的特点。因此,如何有效地实现有功、无功独立调节的解耦控制就成为了一个重要的研究课题。本文首先研究了空间矢量脉宽调制技术(SVPWM)在VSC控制中的应用。在分析了SVPWM用传统方法不易于实现的情况下,讨论其等效实现方法,并提出一种新的易于实现的等效方案。在VSC稳态模型的基础上,通过坐标变换,引入中间控制量A、B,从而推导出VSC功率传输方程的直角坐标形式,消除三角函数对被控量的影响;采用逆系统方法确定VSC-HVDC系统中间控制量与被控量(直流电压、无功、有功、交流电压)以及中间量与控制量(电压的相角与幅值)之间的函数关系,分析VSC-HVDC系统在连接有源和无源系统时的控制方式和要求,提出与之对应的控制策略;并针对不同的被控制量设计有功功率、无功功率独立调节的VSC-HVDC控制系统。采用PSCAD/EMTDC仿真软件对VSC-HVDC系统工作在有源逆变方式和无源逆变方式两种情况下分别进行了仿真试验,经反复调试,得到稳态运行波形和经整定值调节、潮流反转后各被控制量的波形变化,分析结果表明本文所采用的控制策略在VSC-HVDC系统中能够达到良好的响应速度和控制效果。更多还原

【Abstract】 VSC-HVDC is a kind of new DC transmission technology developed from the traditional HVDC, with the IGBT based Voltage Source Converter (VSC) as its major components. Resorting to its superior characteristics, VSC-HVDC has been put into practical application successfully. But there are still many problems that need to be solved in theoretical and practical aspects. Compared with the traditional HVDC, a very important feature of VSC-HVDC is that the real and reactive power can be controlled separately and simultaneously. Therefore, how to effectively realize the decoupling control for separate adjusting of real and reactive power has become an important research topic.First, the application of the SVPWM in the VSC-HVDC is investigated in detail. Analysis shows that SVPWM is difficult to be implemented with traditional method. So, the equivalent implementation method is discussed and a new equivalent scheme, which is more easily implemented, is proposed. Based on the steady state model of VSC and through coordinate transformation, the intermediate control variables are introduced, and the VSC’s power transmitting equations in rectangular coordinates is derived, so the impact of the trigonometric function is eliminated. The function relationships between the intermediate control variables and controlled variables(dc voltage、real power、reactive power、ac voltage) as well as between the intermediate control variables and controlling variables(voltage phase angle and magnitude) are determined with the theory of inverse system. After analyzing the control modes and requirements respectively for VSC-HVDC linked to active and passive systems, the corresponding control strategy is presented. So the VSC-HVDC control system is designed for different controlled variables, this control system can realize the separate adjusting of real and reactive power.PSCAD/EMTDC software is employed to simulate VSC-HVDC operation for active as well as passive inverter operating mode. Through repeatedly simulating, the controlled variable waveforms, for steady-state operation, setting point changing and load flow reversing respectively, are obtained. Simulation results show that the proposed VSC-HVDC control strategy can achieve sufficient response speed and good control effect.更多还原