摘要
云南外送直流发生单极闭锁、多极闭锁及多回直流组合闭锁故障后,都会导致送端有功功率大量盈余,云南电网高频现象突出且可能出现频率长期越限等问题。直流输电系统的附加控制可以改善交流系统的频率稳定控制特性。首先介绍了云南电网的安全稳定控制系统及切机定值,再对云南电网当前的直流控制系统配置情况进行说明,考虑了云南外送直流发生单极闭锁、双极闭锁、三极闭锁、四极闭锁及多回直流组合闭锁故障情况下造成的不同容量的直流输出功率损失。为了分析云南电网在发生多回直流闭锁故障,导致不同外送直流容量缺额下的频率特性,分别对缺额为1600 MW~38600 MW的直流闭锁故障,采取不考虑FLC功能、考虑FLC功能、现有稳控措施、FLC+稳控措施、多直流协控措施等5种不同措施时的云南电网频率特性进行计算分析。为体现不同措施对维持云南送端系统稳定的作用,按照稳定情况,对不同故障下的切机情况、频率稳定问题进行分类对比研究。研究表明,云南外送直流发生单极闭锁、多极闭锁或多回直流组合闭锁故障后,云南电网主要存在频率升高和频率越限问题,少数直流闭锁故障后存在功角暂态稳定问题。在功率盈余不超过6500 MW时,考虑直流FLC功能可将最高暂态频率控制在50.6 Hz以下,稳控+FLC措施能够在盈余功率低于16000 MW时很好地控制最高暂态频率;而当功率盈余超过21000 MW时,多回直流协控的适用性也将大大下降。当交流内部交流通道不足以转送直流闭锁后的盈余容量而导致功角失稳后,必须采取切除相应直流配套机组,才能恢复系统稳定。基于该研究结果提出的建议,对相关工程具有一定的参考价值。
After the unipolar blocking,multi-pole blocking and multi-circuit DC combined blocking failures of Yunnan’s outbound DC,it will lead to a large surplus of active power at the sending end.The high frequency phenomenon of Yunnan Power Grid is prominent and the frequency may exceed the limit for a long time.The ad⁃ditional control of the DC transmission system could improve the frequency stability control characteristics of the AC system.Firstly,the safety and stability control system of Yunnan Power Grid and its cut-off setting were in⁃troduced,and then the current DC control system configuration of Yunnan Power Grid was explained.Second⁃ly,the output power loss of different capacities of Yunnan outgoing DC was considered under the condition of monopolar locking,bipolar locking,tripolar locking,quadrupolar locking and multiple DC combined locking.In order to analyze the frequency characteristics of Yunnan Power Grid with multiple DC latching faults and different output DC capacity gaps,the DC latching faults with 1600 MW~38600 MW were analyzed respec⁃tively.The frequency characteristics of Yunnan Power Grid were calculated and analyzed under 5 different mea⁃sures,such as including not considering FLC function,considering FLC function,adopting existing stability control measures,adopting FLC+stability control measures,and adopting multi-DC co-control measures.In order to reflect the effect of different measures on maintaining the stability of Yunnan sending-end system,in ac⁃cordance with the stability situation,the cutting conditions and frequency stability problems under different faults were classified and compared.The research showed that,after the monopolar locking,multi-pole or multi-circuit DC combined blocking faults occur in Yunnan transmission DC,Yunnan Power Grid mainly had the problems of frequency increase and frequency exceeding limit,and a few DC blocking faults had the problem of power angle transient stability.When the power surplus was less than 6500 MW,the DC FLC function could control the maximum transient frequency below 50.6 Hz,and the stability control+FLC measure could control the maximum transient fre⁃quency well when the power surplus was less than 16000 MW;when the power surpluses exceeded 21000 MW,the applicability of multi-loop DC cocontrol would be greatly reduced.When the internal AC channel of Yunnan AC was insufficient to transfer the surplus capacity after DC blocking,which leaded to power angle in⁃stability,the corresponding DC supporting units must be removed to restore system stability.The proposals based on the research results could provide reference value for other projects.
作者
徐攀腾
朱博
宋述波
谷裕
喻文翔
樊友平
XU Pan-teng;ZHU Bo;SONG Shu-bo;GU Yu;YU Wen-xiang;FAN You-ping(Guangzhou Bureau of China Southern 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4期306-314,370,共10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)。
关键词
云南电网
频率稳定
协调控制
直流闭锁故障
频率附加控制
多回直流
Yunnan Power Grid
frequency stabilization
coordinated control
DC blocking failure
frequency ad⁃ditional control
multi-circuit DC
