With rapid growth of power demand, transmission capacity is also in urgent need of upgrading. In some cases, converting existing AC transmission lines to DC lines can Improve the transmission capacity and reduce the c...With rapid growth of power demand, transmission capacity is also in urgent need of upgrading. In some cases, converting existing AC transmission lines to DC lines can Improve the transmission capacity and reduce the construction investment. In this paper, the upstream finite element method was expanded to calculate the total electric field of same tower multi-circuit DC lines converted from double-circuit AC lines, and the validity of the algorithm was confirmed by experiments. Taking a DC line converted from a typical same tower 500 kV double-circuit AC transmission line as an example, the surface electric field and the ground total electric field in different pole conductor arrangement schemes were calculated and analyzed, and the critical height of pole conductors for DC lines in residential and non-residential area were determined. Then, the corridor width of DC and AC lines at critical height in residential and non-residential areas before and after AC-DC line transformation were compared. The results indicate that for DC lines converted from common 500 kV double-circuit AC lines, the ground total electric field can meet the requirements of corresponding standard with appropriate pole conductor arrangement schemes.展开更多
为提高系统运行稳定性,高补偿度串补装置广泛投入使用,但线路故障后潜供电流存在高幅值的低频分量,潜供电弧难以自熄。针对此问题,基于交直流混联输电线路,研究了不同布置方式下串补度对潜供电流与恢复电压幅值影响,提出了一种固定串补(...为提高系统运行稳定性,高补偿度串补装置广泛投入使用,但线路故障后潜供电流存在高幅值的低频分量,潜供电弧难以自熄。针对此问题,基于交直流混联输电线路,研究了不同布置方式下串补度对潜供电流与恢复电压幅值影响,提出了一种固定串补(fixed series compensation,FSC)和可控串补(thyristor controlled series compensation,TCSC)混合复用抑制潜供电弧的方法。此外,为满足线路对高补偿度的需求,设计FSC和TCSC混合复用串补度最佳配置方案。结果表明,交直流混联线路采用串补度40%的双平台分散布置方式,潜供电流与恢复电压幅值达到最小,燃弧时间最短。高补偿度串补线路TCSC采用串补度10%、20%的配置方案更利于熄弧,提高重合闸成功率。展开更多
随着高压直流输电工程的不断投产,以及风电项目的增多,越来越多的风电场出现在电网换相换流器高压直流输电(line-commutated-converter based high voltage direct current,LCC-HVDC)受端换流站近区,两者构成的系统存在振荡风险。为此,...随着高压直流输电工程的不断投产,以及风电项目的增多,越来越多的风电场出现在电网换相换流器高压直流输电(line-commutated-converter based high voltage direct current,LCC-HVDC)受端换流站近区,两者构成的系统存在振荡风险。为此,该文针对直流受端馈入站与近区风电场系统的振荡特性展开研究。首先,建立并验证系统的状态空间模型,基于该模型计算出系统特征值,确定LCC-HVDC与风电场共同参与的振荡主导模式并进行参与因子分析。进一步地,通过对比是否接入LCC-HVDC的主导模式,得到LCC-HVDC的接入会削弱系统阻尼的结论。最后,从系统额定容量、交流系统短路比、风电场并网线路长度等方面探究系统稳定性的影响因素,并分析系统的不同短路比、潮流比对风机网侧换流器(grid-side converter,GSC)外环控制和换流站定电流控制器性能的影响。展开更多
首先介绍在远距离大容量输电场合,3种基于模块化多电平换流器(modular multilevel converter,MMC)的高压直流输电(high voltage direct current,HVDC)拓扑及其处理直流故障的方法:基于半桥子模块(half bridge sub-module,HBSM)的HMMC-H...首先介绍在远距离大容量输电场合,3种基于模块化多电平换流器(modular multilevel converter,MMC)的高压直流输电(high voltage direct current,HVDC)拓扑及其处理直流故障的方法:基于半桥子模块(half bridge sub-module,HBSM)的HMMC-HVDC跳换流站交流侧断路器,基于箝位双子模块(clamp double sub-module,CDSM)的CMMCHVDC通过换流器控制实现直流侧故障自清除,以及基于电网换相换流器(line commutated converter,LCC)和MMC的混合拓扑在MMC直流出口处加装大功率二极管(LCC-D-MMC-HVDC)。然后,在由MMC-HVDC和交流线路构成的交直流并列简化系统中,基于等面积法则,对上述3种直流故障处理方法的暂态过程进行理论分析,并提出评价指标。最后通过仿真验证了分析结果。展开更多
文摘With rapid growth of power demand, transmission capacity is also in urgent need of upgrading. In some cases, converting existing AC transmission lines to DC lines can Improve the transmission capacity and reduce the construction investment. In this paper, the upstream finite element method was expanded to calculate the total electric field of same tower multi-circuit DC lines converted from double-circuit AC lines, and the validity of the algorithm was confirmed by experiments. Taking a DC line converted from a typical same tower 500 kV double-circuit AC transmission line as an example, the surface electric field and the ground total electric field in different pole conductor arrangement schemes were calculated and analyzed, and the critical height of pole conductors for DC lines in residential and non-residential area were determined. Then, the corridor width of DC and AC lines at critical height in residential and non-residential areas before and after AC-DC line transformation were compared. The results indicate that for DC lines converted from common 500 kV double-circuit AC lines, the ground total electric field can meet the requirements of corresponding standard with appropriate pole conductor arrangement schemes.
基金Project supported by Funds for Innovative Research Groups of China （51021005）, National Basic Research Program of China （973 Program） （2009CB724504）, National Natural Science Foundation of China（50707036）.
文摘为提高系统运行稳定性,高补偿度串补装置广泛投入使用,但线路故障后潜供电流存在高幅值的低频分量,潜供电弧难以自熄。针对此问题,基于交直流混联输电线路,研究了不同布置方式下串补度对潜供电流与恢复电压幅值影响,提出了一种固定串补(fixed series compensation,FSC)和可控串补(thyristor controlled series compensation,TCSC)混合复用抑制潜供电弧的方法。此外,为满足线路对高补偿度的需求,设计FSC和TCSC混合复用串补度最佳配置方案。结果表明,交直流混联线路采用串补度40%的双平台分散布置方式,潜供电流与恢复电压幅值达到最小,燃弧时间最短。高补偿度串补线路TCSC采用串补度10%、20%的配置方案更利于熄弧,提高重合闸成功率。
文摘随着高压直流输电工程的不断投产,以及风电项目的增多,越来越多的风电场出现在电网换相换流器高压直流输电(line-commutated-converter based high voltage direct current,LCC-HVDC)受端换流站近区,两者构成的系统存在振荡风险。为此,该文针对直流受端馈入站与近区风电场系统的振荡特性展开研究。首先,建立并验证系统的状态空间模型,基于该模型计算出系统特征值,确定LCC-HVDC与风电场共同参与的振荡主导模式并进行参与因子分析。进一步地,通过对比是否接入LCC-HVDC的主导模式,得到LCC-HVDC的接入会削弱系统阻尼的结论。最后,从系统额定容量、交流系统短路比、风电场并网线路长度等方面探究系统稳定性的影响因素,并分析系统的不同短路比、潮流比对风机网侧换流器(grid-side converter,GSC)外环控制和换流站定电流控制器性能的影响。
