【作者】 高东锋；

【导师】 梁小冰；

【作者基本信息】 广西大学 ， 电力系统及其自动化， 2005， 硕士

【摘要】 随着国民经济的发展,各个行业对能源的需求越来越大,这对电力系统的发展既是机遇也是挑战。为了满足用户的巨大需求、提高系统的经济性,高压直流系统作为新兴技术正在发挥关键作用。同时,系统的电压稳定性对区域的稳定具有非常重要的意义,而经济的全面发展也造成了负荷的多样性,因此研究直流输电系统的电压稳定性及负荷特性的影响变得越来越重要。 本文介绍了直流输电的相对优势,以及常用的评价直流系统稳定性的参数,同时重点介绍了短路比(SCR)、有效短路比(ESCR)和电压稳定性因子(VSF),并说明了它们和电压稳定性的关系。在此基础上,推导了临界短路比(CSCR)的函数表达式、从理论上证明了MAP和VSF在一定控制条件下的相互关联性,同时在考虑负荷特性的条件下推导了基于单馈入系统的CSCR的函数表达式,从而为从函数角度分析稳定性打下了基础。 为了进一步分析所推导函数关系的正确性,本文采用了电磁暂态仿真软件PSCAD/EMTDC,在国际大电网会议CIGRE提出的HVDC标准模型上,通过在逆变侧连接具有不同特性负荷,进行仿真测试,并将测试结果与理论值进行了比较。在标准测试系统下的仿真结果表明,负荷特性等系统参数对高压直流系统逆变端电压稳定性是有较大影响的。更多还原

【Abstract】 With the developing of national economy, the power demands of all trades become bigger and bigger, and it is not only an opportunity but also a challenge for the development of electrical power system. To meet the demands and minimize the operation cost of power system, as a novel technology, HVDC system will play an increasingly important role. At the same time, the voltage stability is very important for the regional stability, and the overall development of economy produces the variety of loads, thereby studying the voltage stability of inverter AC bus in the HVDC system and influence of load characteristic becomes more important.This paper introduces the advantages of HVDC transmission and some parameters used in evaluating the stability of HVDC system. It focuses on the relationship between stability and the SCR, ESCR, VSF. Based on this, the expression of CSCR is derived, and the relation between MAP and VSF under particular control condition is demonstrated theoretically. Furthermore, considering the load characteristics, the expression of CSCR in single-feed system is deduced, which provides the foundation for studying the stability problem analytically.The electromagnetic-transient simulation software —PSCAD/EMTDC is used to carry out the simulation tests on the HVDC benchmark of CIGRE for different inverter load characteristics . The simulation results are compared with the theoretical values. The final analysis indicates that the load characteristics and some other parameters influence the voltage stability of inverter AC bus significantly.更多还原