【作者】 刘翀；

【导师】 印永华； 蒋卫平； 朱艺颖；

【作者基本信息】 中国电力科学研究院 ， 电力系统及其自动化， 2009， 硕士

【摘要】 为适应地域能源分布及经济发展的不平衡,实现资源的优化配置,国家提出大力开发西部和北部的水火电基地和可再生能源基地,实现西电东送,南北互供和全国联网的战略目标。2020年前后,我国将建成以百万伏级交流和±800千伏级直流特高压骨干网架为核心的国家电网。特高压系统形成后,将是一个规模巨大的超、特高压交直流混合运行的复杂电网,部分地区将形成多回直流集中馈入的系统。根据特高压电网规划,2015水平年将有8回直流落点华东电网,对于如此规模的多直流馈入系统,交直流系统之间相互作用将更为复杂。为了更好地发挥其输电潜力并保障系统安全稳定运行,研究多直流馈入系统的运行特性成为电力系统研究的当务之急。本文采用EMTDC/PSCAD电磁暂态仿真程序建立了2015水平年等值网络的仿真模型,对多直流馈入系统的运行特性进行研究,主要研究结论如下：(1)建立大规模多直流馈入特高压交/直流电网全数字电磁暂态仿真平台,包括动态等值、EMTDC模型建立及动态特性校核等,为特高压电网多直流馈入系统运行特性研究提供了仿真手段。(2)综合分析多直流馈入系统换相失败的机理,研究电压暂态变化及速率、换相电压过零点偏移、交流系统短路电流水平、直流电流突增及直流控制保护系统等多种因素对换相失败的影响,为多直流馈入系统运行特性研究提供了分析方法和思路。(3)对受端交流系统故障引起直流换相失败问题进行深入研究,表明存在多回直流同时发生换相失败的现象,但故障切除后直流输电系统能够恢复正常运行,验证了华东受端电网接受8回直流输电方案的技术可行性。(4)对特高压交直流混合输电系统的安全稳定性进行全面研究,系统发生N-1故障能够保持稳定运行；发生N-2故障时存在安全稳定问题,但采取安全稳定措施后系统也能够保持稳定运行,证实特高压交直流混合输电系统符合“电力系统安全稳定导则”的要求。(5)对提高特高压交直流混合输电系统安全稳定性的措施进行仿真研究,分析了直流功率紧急提升和配置动态无功补偿等措施的作用,为这些措施的应用提供了技术依据。更多还原

【Abstract】 In the purpose of meeting the unbalanced regional energy distribution and economic development, the government made a strategic target that is to develope hydropower, thermal power and renewable energy bases in the western and northern part and implement transmitting power from West to East and nationwide power grid interconnection. In 2020, China will build a national backbone grid consisting of 1000kV AC system and±800kV HVDC system. After the formation of the UHV Power Grid, multi-infeed HVDC system will emerge in some areas. According to the UHV Power Grid planning, the terminals of 8 HVDC transmission lines will be in East-China power grid in 2015, the interaction between AC and DC systems will become more complicated. It’s necessary to study the operation performance in Multi-infeed HVDC system.The equivalent power grid in 2015 is established using the EMTDC/PSCAD electromagnetic transient simulation software to study the operation performance in Multi-infeed HVDC system. The main research conclusion are listed as follows:(1) The methods of establishing all-digital electromagnetic transient simulation system with large-scale multi-infeed HVDC system are studied, including the dynamic equivalence, EMTDC model establishment, and the dynamic performance checking. The simulation means of analyzing the operation performance in multi-infeed HVDC system under Ultra High Voltage Power Grid is provided.(2) In order to provide analysis methods and ideas for the study on operation performance in Multi-infeed HVDC system, the mechanism of commutation failure in Multi-infeed HVDC system is comprehensively analyzed. Several factors that may cause commutation failure are studied, such as transient voltage changes and voltage decreasing rate, commutating voltage zero-crossing phase shift, AC system short circuit current level, sudden increase of DC current, and HVDC control and protection characterastic. (3) The commutation failure caused by the AC system faults at the receiveing side is studied deep. The study results show the commutation failure takes place at more than one HVDC systems simultaneously, but the HVDC systems can return to normal operation after faults clearing. The technical feasibility for the focus of eight HVDC terminals in east china is verified.(4) The thesis makes overall research on the security and stability of UHV AC-DC hybrid transmission system. The system can maintain stable operation when the N-1 fault happens. When N-2 fault happens, the system can be kept stable with security and stability measures. So it’s proved that the security and stability of UHV AC/DC hybrid transmission system meets the requirements of "Power System Security and Stability Guide".(5) To improve system security and stability of UHV AC-DC hybrid transmission system, the Emergency upgrade of dc power and Strengthen dynamic reactive power compensation measures are simulated to provide the technical reference.更多还原