采用架空线柔性直流输电技术进行远距离输电是大规模风电场友好型并网的有效手段。针对架空线路易发生故障的问题,采用对称双极主接线并配置直流断路器是其主要解决方案之一。该文基于双极接线方案运行方式灵活及直流断路器的故障清除能...采用架空线柔性直流输电技术进行远距离输电是大规模风电场友好型并网的有效手段。针对架空线路易发生故障的问题,采用对称双极主接线并配置直流断路器是其主要解决方案之一。该文基于双极接线方案运行方式灵活及直流断路器的故障清除能力,提出风电经架空线基于模块化多电平换流器的柔性直流输电(modular multilevel converter based high voltage direct current,MMC-HVDC)并网的直流故障穿越协调控制策略。根据非故障极的功率转带能力,将故障清除后的不平衡功率分配划分为自消纳情景和非自消纳情景。针对自消纳情景,通过合理切换双极MMC的控制模式,可在提高非故障极功率转带能力的同时自主消纳不平衡功率,进而有效降低转移功率的影响范围;针对非自消纳情景,设计考虑风机转速约束的风电场超速减载协调控制策略,优化分配各风电机组承担的减载功率,充分利用其转子动能和捕获风功率的变化实现精确减载;同时通过控制模式切换使非故障极MMC自主运行于满载状态,减小单极退出运行对受端交流系统的影响。最后,基于Matlab/Simulink仿真模型验证所提直流故障穿越协调控制策略的有效性。展开更多
随着电力系统中新能源接入比例不断提高,采用跟网控制的模块化多电平换流器型柔性直流输电(Modular multilevel converter based high voltage direct current,MMC-HVDC)在输电系统中占据越来越重要的地位,其并网暂态同步稳定性会影响...随着电力系统中新能源接入比例不断提高,采用跟网控制的模块化多电平换流器型柔性直流输电(Modular multilevel converter based high voltage direct current,MMC-HVDC)在输电系统中占据越来越重要的地位,其并网暂态同步稳定性会影响电力系统的安全运行。研究跟网型MMC-HVDC系统的暂态同步稳定机理,首先建立了以锁相环为同步单元的换流器的并网动力学模型,随后基于此模型,研究了电网强度、换流器的故障穿越策略以及锁相环参数对其暂态稳定性的影响。当电网强度较高、换流器故障期间注入无功电流分量增大时,换流器的并网暂态稳定性较强,减小锁相环的比例和积分增益有利于暂态稳定性。根据暂态稳定机理,提出了与阻抗角匹配的故障期间注入电流策略,以提升换流器的暂态同步稳定性。在时域仿真软件PSCAD/EMTDC中搭建了电磁暂态仿真模型并验证了本文结论和所提暂态稳定增强策略的有效性。展开更多
With continuously increasing of photovoltaic (PV) plant’s penetration, it has become a critical issue to improve the fault ride-through capability of PV plant. This paper refers to the German grid code, and the PV sy...With continuously increasing of photovoltaic (PV) plant’s penetration, it has become a critical issue to improve the fault ride-through capability of PV plant. This paper refers to the German grid code, and the PV system is controlled to keep grid connected, as well as inject reactive current to grid when fault occurs. The mathematical model of PV system is established and the fault characteristic is studied with respect to the control strategy. By analyzing the effect of reactive power supplied by the PV system to the point of common coupling (PCC) voltage, this paper proposes an adaptive voltage support control strategy to enhance the fault ride-through capability of PV system. The control strategy fully utilizes the PV system’s capability of voltage support and takes the safety of equipment into account as well. At last, the proposed control strategy is verified by simulation.展开更多
文摘采用架空线柔性直流输电技术进行远距离输电是大规模风电场友好型并网的有效手段。针对架空线路易发生故障的问题,采用对称双极主接线并配置直流断路器是其主要解决方案之一。该文基于双极接线方案运行方式灵活及直流断路器的故障清除能力,提出风电经架空线基于模块化多电平换流器的柔性直流输电(modular multilevel converter based high voltage direct current,MMC-HVDC)并网的直流故障穿越协调控制策略。根据非故障极的功率转带能力,将故障清除后的不平衡功率分配划分为自消纳情景和非自消纳情景。针对自消纳情景,通过合理切换双极MMC的控制模式,可在提高非故障极功率转带能力的同时自主消纳不平衡功率,进而有效降低转移功率的影响范围;针对非自消纳情景,设计考虑风机转速约束的风电场超速减载协调控制策略,优化分配各风电机组承担的减载功率,充分利用其转子动能和捕获风功率的变化实现精确减载;同时通过控制模式切换使非故障极MMC自主运行于满载状态,减小单极退出运行对受端交流系统的影响。最后,基于Matlab/Simulink仿真模型验证所提直流故障穿越协调控制策略的有效性。
文摘随着电力系统中新能源接入比例不断提高,采用跟网控制的模块化多电平换流器型柔性直流输电(Modular multilevel converter based high voltage direct current,MMC-HVDC)在输电系统中占据越来越重要的地位,其并网暂态同步稳定性会影响电力系统的安全运行。研究跟网型MMC-HVDC系统的暂态同步稳定机理,首先建立了以锁相环为同步单元的换流器的并网动力学模型,随后基于此模型,研究了电网强度、换流器的故障穿越策略以及锁相环参数对其暂态稳定性的影响。当电网强度较高、换流器故障期间注入无功电流分量增大时,换流器的并网暂态稳定性较强,减小锁相环的比例和积分增益有利于暂态稳定性。根据暂态稳定机理,提出了与阻抗角匹配的故障期间注入电流策略,以提升换流器的暂态同步稳定性。在时域仿真软件PSCAD/EMTDC中搭建了电磁暂态仿真模型并验证了本文结论和所提暂态稳定增强策略的有效性。
文摘With continuously increasing of photovoltaic (PV) plant’s penetration, it has become a critical issue to improve the fault ride-through capability of PV plant. This paper refers to the German grid code, and the PV system is controlled to keep grid connected, as well as inject reactive current to grid when fault occurs. The mathematical model of PV system is established and the fault characteristic is studied with respect to the control strategy. By analyzing the effect of reactive power supplied by the PV system to the point of common coupling (PCC) voltage, this paper proposes an adaptive voltage support control strategy to enhance the fault ride-through capability of PV system. The control strategy fully utilizes the PV system’s capability of voltage support and takes the safety of equipment into account as well. At last, the proposed control strategy is verified by simulation.
