摘要
特高压直流(UHVDC)输电在远距离大容量输电方面具有不可替代的作用,同时也给电网安全稳定运行带来风险和难题。为给直流输电技术的应用和发展提供参考,以南方电网为背景,分析了UHVDC输电对电网影响,介绍了解决的典型技术难题。UHVDC对电网带来的主要风险包括:直流输电大功率运行闭锁、交流系统故障导致多回直流持续换相失败或闭锁等。提出的主要解决手段包括:优化直流落点,合理选择单回UHVDC规模;优化电网结构;提高受端电网的动态无功补偿能力。南方电网运用能够高精度模拟直流系统换相过程的电磁暂态仿真平台仿真验证了相关措施的有效性。还举出南方电网特高压直流运行和建设中出现的典型技术难题,如±800 k V双阀组不对称运行典型故障、直流系统双极闭锁、多直流集中馈入系统极端故障、直流接地极选址困难,给出分析和应对措施建议。最后指出,柔性直流技术可有效避免或解决传统直流集中馈入受端电网导致的各种失稳风险,增强交流电网可控性,是未来电网的重要发展方向。
Ultra-high voltage DC(UHVDC) system plays an irreplaceable role in long-distance and large-capacity power transmission. However, it also brings new challenges and difficulties to the safe operation of power system. To provide reference and guidance for the future development and application of UHVDC, based on the practice and analyses of UHVDC components in China Southern Power Grid(CSG) and some experience, the impact of UHVDC to existing power networks is analyzed, some typical technical issues are summarized. The main risks of networks brought by UHVDC include the lockdown of heavily-loaded UHVDC system, the possible continuous commutation failure or lockdown induced by the operation failure of protection devices or switches when there is fault at the load center of receiving end. According to these issues, several measures were applied, such as optimizing the location of UHVDC and the scale of single UHVDC, optimizing the AC network structure, and increasing the dynamic reactive power compensation ability of receiving networks. These measures have been proved to be effective by transient electromagnetic simulation which is able to accurately simulate the commutation process of DC systems in CSG. Several typical technical problems occurred in operation and construction of UHVDC in CSG are presented, such as typical faults in ±800 k V system with the valve groups in asymmetric operation, the bipolar blocking of UHVDC system, the extreme faults of multi-infeed HVDC system, and the difficulties in the location of the DC grounding system. Analysis and advice of countermeasures is given. In the end, it is suggested that the voltage source converter based HVDC(VSC-HVDC) technology is effective for instability at receiving networks caused by multi-infeed HVDC, enhancing the controllability of AC system, and will play an essential part in the development of future power system.
出处
《高电压技术》
EI
CAS
CSCD
北大核心
2015年第8期2481-2488,共8页
High Voltage Engineering
