直流异步联网对送端系统阻尼特性的影响
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摘要
大型交流电网采用柔性直流系统进行异步联网后,可以完全消除区域系统间的低频振荡,但送端系统内部的低频振荡特性也会发生改变。为探讨送端系统在柔性直流异步联网前后的低频振荡阻尼构成和变化规律,重点分析了负荷、交流联络线功率、运行电压及线路阻抗对系统阻尼的影响,并推导了交流联络线上增加柔性直流输电系统后,换流站不同控制方式及安装位置对送端系统低频振荡阻尼特性及小干扰稳定能力的影响机理,得出了异步联网情形的阻尼系数表达式;最后采用PSASP程序仿真计算进行验证,结果表明柔性直流异步联网能够阻断区域间低频振荡,提升送端系统阻尼特性及小干扰稳定能力,但有可能改变送端系统的区域内振荡模式。
Asynchronous grid interconnection in which a flexible HVDC system is adopted can eliminate the inter-area oscillations in large interconnected systems. However, the oscillations inside the sending end system may be affected. To explore the composition and variation of low frequency oscillation damping of sending end in the cases of AC and flexible dc interconnection, firstly, we analyzed the effects of system load, tie line flow, operating voltage and impedance on system damping in detail. Secondly, taking the addition of flexible DC system on AC tie into account, we derived a system damping expression corresponding to different control mode and installation position of DC converter. Thereby, the variation mechanism of low frequency oscillation characteristics and small disturbance stability of sending end system was revealed, and PSASP simulation was used to verify these theories. The results show that the flexible DC interconnection can clear the inter-area low frequency oscillation, improve the damping characteristics and small disturbance stability of sending end system, but it may change the oscillation mode inside the area.
Asynchronous grid interconnection in which a flexible HVDC system is adopted can eliminate the inter-area oscillations in large interconnected systems. However, the oscillations inside the sending end system may be affected. To explore the composition and variation of low frequency oscillation damping of sending end in the cases of AC and flexible dc interconnection, firstly, we analyzed the effects of system load, tie line flow, operating voltage and impedance on system damping in detail. Secondly, taking the addition of flexible DC system on AC tie into account, we derived a system damping expression corresponding to different control mode and installation position of DC converter. Thereby, the variation mechanism of low frequency oscillation characteristics and small disturbance stability of sending end system was revealed, and PSASP simulation was used to verify these theories. The results show that the flexible DC interconnection can clear the inter-area low frequency oscillation, improve the damping characteristics and small disturbance stability of sending end system, but it may change the oscillation mode inside the area.
引文
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[18]屠竞哲,张健,贾俊川,等.多回直流换相失败后送端三机群系统稳定机理及影响因素研究[J].电网技术,2016,41(3):683-690.TU Jingzhe,ZHANG Jian,JIA Junchuan,et al.Study on stability mechanism and influential factors of sending-side three-machine system after multiple HVDC commutation failure[J].Power System Technology,2016,41(3):683-690.
[19]屠竞哲,张健,王建明,等.大规模直流异步互联系统受端故障引发送端稳定破坏的机理分析[J].中国电机工程学报,2015,35(21):5492-5499.TU Jingzhe,ZHANG Jian,WANG Jianming,et al.Mechanism analysis on the sending-side instability caused by the receiving-side contingencies of large-scale HVDC asynchronous interconnected power systems[J].Proceedings of the CSEE,2015,35(21):5492-5499.
[20]钟庆,马新华,王钢,等.电压源型换流器稳态等值电路模型[J].高电压技术,2014,40(8):2485-2489.ZHONG Qing,MA Xinhua,WANG Gang,et al.Static equivalent circuit models of voltage source converter[J].High Voltage Engineering,2014,40(8):2485-2489.
[21]郑超,汤涌,马世英,等.基于等效仿真模型的VSC-HVDC次同步振荡阻尼特性分析[J].中国电机工程学报,2007,27(31):33-39.ZHENG Chao,TANG Yong,MA Shiying,et al.Subsynchronous oscillation damping characteristic analysis for VSC-HVDC based on its equivalent simulation model[J].Proceedings of the CSEE,2007,27(31):33-39.
[22]徐友平,张珂,潘晓杰,等.渝鄂背靠背柔性直流附加阻尼控制策略研究[J].电力系统保护与控制,2016,44(18):163-169.XU Youping,ZHANG Ke,PAN Xiaojie,et al.Damping control based on back to back VSC-HVDC connecting Chongqing and Hubei Power Grid[J].Power System Protection and Control,2016,44(18):163-169.
[2]JANSSENS N,KAMAGATE A.Interarea oscillations in power systems[J].Power Electronics&Power Systems,2000,33(5):217-226.
[3]邓集祥,贺建明,姚天亮,等.大区域联网条件下四川电网低频振荡分析[J].电网技术,2008,32(17):78-83.DENG Jixiang,HE Jianming,YAO Tianliang,et al.Analysis of low frequency oscillation for Sichuan Power Grid in large scale interconnected power systems[J].Power System Technology,2008,32(17):78-83.
[4]马为民,吴方劼,杨一鸣,等.柔性直流输电技术的现状及应用前景分析[J].高电压技术,2014,40(8):2429-2439.MA Weimin,WU Fangjie,YANG Yiming,et al.Flexible HVDCtransmission technology’s today and tomorrow[J].High Voltage Engineering,2014,40(8):2429-2439.
[5]李兴源,曾琦,王渝红,等.柔性直流输电系统控制研究综述[J].高电压技术,2016,42(10):3025-3037.LI Xingyuan,ZENG Qi,WANG Yuhong,et al.Control strategies of voltage source converter based direct current transmission system[J].High Voltage Engineering,2016,42(10):3025-3037.
[6]游广增,徐政,刘昇,等.小水电富集电网的柔性直流异步联网方案研究[J].电网技术,2016,40(4):1059-1065.YOU Guangzeng,XU Zheng,LIU Sheng,et al.Study on VSC-HVDCasynchronous interconnection schemes for regional grids with concentrated small hydropower[J].Power System Technology,2016,40(4):1059-1065.
[7]周保荣,洪潮,金小明,等.南方电网同步运行网架向异步运行网架的转变研究[J].中国电机工程学报,2016,36(8):2084-2092.ZHOU Baorong,HONG Chao,JING Xiaoming,et al.Study of backbone structure change from synchronous to asynchronous in China Southern Power Grid[J].Proceedings of the CSEE,2016,36(8):2084-2092.
[8]余贻鑫,李鹏.大区电网弱互联对互联系统阻尼和动态稳定性的影响[J].中国电机工程学报,2005,25(11):6-11.YU Yixin,LI Peng.The impact of weak interconnection of bulk power grids to damping and dynamic stability of power systems[J].Proceedings of the CSEE,2005,25(11):6-11.
[9]朱方,赵红光,刘增煌,等.大区电网互联对电力系统动态稳定性的影响[J].中国电机工程学报,2007,27(1):1-7.ZHU Fang,ZHAO Hongguang,LIU Zenghuang,et al.The influence of large power grid interconnected on power system dynamic stability[J].Proceedings of the CSEE,2007,27(1):1-7.
[10]王青,马世英.电力系统区间振荡的阻尼与区域间送电功率关系特性[J].电网技术,2011,35(5):40-45.WANG Qing,MA Shiying.Relationship between inter-area oscillation damping in power system and inter-area transmitted power[J].Power System Technology,2011,35(5):40-45.
[11]周孝信,何志华,张祖平.电力系统阻尼特性和低频振荡现象的分析[J].电网技术,1984,8(增刊1):3-13.ZHOU Xiaoxin,HE Zhihua,ZHANG Zuping.Analysis of power system damping characteristics and low frequency oscillation[J].Power System Technology,1984,8(Supplement 1):3-13.
[12]GAO H,ZHAN X,JIANG X,et al.Research on mechanism of power system low frequency oscillation based on damping coefficient[C]//International Conference on Electrical and Electronic Engineering.Ankara,Turkey:IEEE,2017:99-103.
[13]KLEIN M,ROGERS G J,KUNDUR P.A fundamental study of inter-area oscillations in power systems[J].IEEE Transactions on Power Systems,1991,6(3):914-921.
[14]蔡葆锐,王兴刚,司大军.异步联网对云南电网安全稳定性的影响[J].云南电力技术,2015,43(1):83-86.CAI Baorui,WANG Xinggang,SI Dajun.Impact of asynchronous networking for Yunnan Power Grid security and stability[J].Yunnan Electric Power,2015,43(1):83-86.
[15]杜斌,张丹,张军民,等.异步联网后云南电网的稳定特性与控制措施[J].南方电网技术,2016,10(7):13-16.DU Bin,ZHANG Dan,ZHANG Junmin,et al.Stability characteristics and control measures of Yunnan Power Grid after asynchronous interconnection[J].Southern Power System Technology,2016,10(7):13-16.
[16]潘晓杰,张顺,文汀,等.渝鄂异步互联对华中电网运行特性的影响[J].电力系统保护与控制,2016,44(19):157-162.PAN Xiaojie,ZHANG Shun,WEN Ting,et al.Operation characteristic analysis of Central China Power Grid in unsynchronized interconnection of Chongqing and Hubei Power Grid[J].Power System Protection and Control,2016,44(19):157-162.
[17]徐蔚,林勇,周煜智,等.区域电网互联对广东电网暂态稳定性的影响分析[J].电力系统自动化,2013,37(21):34-38.XU Yu,LIN Yong,ZHOU Yuzhi,et al.Impact analysis of regional grid interconnection on transient stability of Guangdong Power Grid[J].Automation of Electric Power Systems,2013,37(21):34-38.
[18]屠竞哲,张健,贾俊川,等.多回直流换相失败后送端三机群系统稳定机理及影响因素研究[J].电网技术,2016,41(3):683-690.TU Jingzhe,ZHANG Jian,JIA Junchuan,et al.Study on stability mechanism and influential factors of sending-side three-machine system after multiple HVDC commutation failure[J].Power System Technology,2016,41(3):683-690.
[19]屠竞哲,张健,王建明,等.大规模直流异步互联系统受端故障引发送端稳定破坏的机理分析[J].中国电机工程学报,2015,35(21):5492-5499.TU Jingzhe,ZHANG Jian,WANG Jianming,et al.Mechanism analysis on the sending-side instability caused by the receiving-side contingencies of large-scale HVDC asynchronous interconnected power systems[J].Proceedings of the CSEE,2015,35(21):5492-5499.
[20]钟庆,马新华,王钢,等.电压源型换流器稳态等值电路模型[J].高电压技术,2014,40(8):2485-2489.ZHONG Qing,MA Xinhua,WANG Gang,et al.Static equivalent circuit models of voltage source converter[J].High Voltage Engineering,2014,40(8):2485-2489.
[21]郑超,汤涌,马世英,等.基于等效仿真模型的VSC-HVDC次同步振荡阻尼特性分析[J].中国电机工程学报,2007,27(31):33-39.ZHENG Chao,TANG Yong,MA Shiying,et al.Subsynchronous oscillation damping characteristic analysis for VSC-HVDC based on its equivalent simulation model[J].Proceedings of the CSEE,2007,27(31):33-39.
[22]徐友平,张珂,潘晓杰,等.渝鄂背靠背柔性直流附加阻尼控制策略研究[J].电力系统保护与控制,2016,44(18):163-169.XU Youping,ZHANG Ke,PAN Xiaojie,et al.Damping control based on back to back VSC-HVDC connecting Chongqing and Hubei Power Grid[J].Power System Protection and Control,2016,44(18):163-169.