摘要
随着乌东德特高压三端直流的投产,南方电网“西电东送”直流工程将达到13回,馈入广东受端电网的直流增加至10回,受端广东、广西电网存在多直流馈入问题,电网在严重故障下的安全稳定运行遭受重大挑战,存在大面积停电的风险。基于南方电网2020年夏大方式规划数据,在RTDS中建立乌东德直流的三端常规直流和三端混合直流实时仿真模型。分析乌东德直流对南方电网当前网架及系统主要特性的影响,认为多回直流发生持续换相失败的问题突出,云南电网可能存在高周动作风险。基于RTDS全电磁暂态实时仿真平台,开展了乌东德直流受端落点近区电网交直流系统发生单一严重故障的仿真试验,故障类型包括交流N-1、交流N-2、单相短路中开关拒动、三相短路中开关单相拒动、直流闭锁,共计50个试验项目。从受端交流电网电压稳定性、送端交流电网频率稳定性、乌东德直流应对严重故障的响应、乌东德直流对其它直流的影响四个方面,综合对比研究了乌东德直流受端为LCC或VSC对系统稳定性的影响。研究表明,乌东德直流广东、广西受端若采用LCC,受端发生交流线路N-1、交流线路N-2、线路单相短路中单相开关拒动、线路三相短路中单相开关拒动故障时,都将导致乌东德等多回直流发生换相失败、云南电网频率增大,甚至导致系统电压失稳;乌东德受端若采用VSC,受端交流故障时直流功率跌落相对较小、恢复速度较快,对交流系统稳定性、电压和频率恢复的支撑效果更优。因此,乌东德受端采用VSC换流器更有利于提高电网交直流严重故障下的稳定性。
With the commissioning of UHV three-terminal DC in Wudongde,China Southern Power Grid’s“west-to-east”DC transmission project will reach 13 cycles,and the DC fed into the Guangdong receiving-end power grid will increase to 10 cycles,and the receiving-end Guangdong and Guangxi power grids will have mul⁃tiple DC feed-in problems.The safe and stable operation of the power grid under serious faults is greatly chal⁃lenges,and there is a risk of large-scale blackouts.Based on the summer planning data of China Southern Pow⁃er Grid’s in 2020,a real-time simulation model of three-terminal conventional DC and three-terminal hybrid DC of Wudongde DC was established in RTDS.Analyzing the impact of Wudongde DC on the main character⁃istics of the current grid and system of the Southern Power Grid,it is believed that the continuous commutation failure of the multi-circuit DC is prominent,and the Yunnan Power Grid may have highcycle operation risks.Based on the RTDS full-electromagnetic transient real-time simulation platform,a simulation test of a single serious fault in the AC/DC system near the DC receiving end of Wudongde was carried out.The types of faults include AC N-1,AC N-2,single-phase short circuit medium switch refuses to move,the three-phase short circuit medium switch single-phase refuses to move,and the DC lockout,a total of 50 test items.From the four aspects of voltage stability of the receiving end AC power grid,the frequency stability of the sending end AC power grid,the response of Wudongde DC to serious faults,and the influence of Wudongde DC on other DCs,the influence of LCC or VSC on system stability of the Wudongde DC receiving end is comprehensively study.The research shows that if LCC is adopted at the receiving ends of Wudongde DC in Guangdong and Guangxi,the commutation failure of multi-circuit DC such as Wudongde DC will occur when AC line N-1,AC line N-2,switch failure in single-phase short circuit of line and switch failure in single-phase short circuit of line occur at the receiving ends,and the frequency of Yunnan power grid will increase,or even system voltage instability will occur.If the VSC is adopted in the receiving end of Wudongde,the DC power drop is relatively small and the recovery speed is fast,and the support effect on the stability,voltage and frequency recovery of the AC sys⁃tem is better.Therefore,the VSC converter at the receiving end of Wudongde is more conducive to improving the stability of the grid under serious AC and DC faults.
作者
徐攀腾
朱博
宋述波
严海健
喻文翔
樊友平
XU Pan-teng;ZHU Bo;SONG Shu-bo;YAN Hai-jian;YU Wen-xiang;FAN You-ping(Guangzhou Bureau of China Souther Power Grid Co.,Ltd.,EHV Transmission Company,Guangzhou 510500,China;School of Electrical and Automation,Wuhan University,Wuhan 430072,China)
出处
《电力学报》
2021年第6期475-482,共8页
Journal of Electric Power
基金
“南方电网乌东德电站送电广东、广西特高压多端柔性直流示范工程”项目研究成果
国家重点研发计划项目(2016YFB0900903)。
