直流故障隔离技术是多端柔性直流输、配电系统发展的关键技术。然而,直流系统直流侧故障存在电流快速上升、过流幅值大等特点,对隔离技术提出了极为苛刻的要求。该文针对工程实际中最为典型的两电平电压源换流器(two-level voltage sour...直流故障隔离技术是多端柔性直流输、配电系统发展的关键技术。然而,直流系统直流侧故障存在电流快速上升、过流幅值大等特点,对隔离技术提出了极为苛刻的要求。该文针对工程实际中最为典型的两电平电压源换流器(two-level voltage source converter,two-level VSC)型和模块化多电平换流器(modular multi-level converter,MMC)型直流系统,结合国内外研究成果,以交流断路器、换流器和直流断路器为分类依据,归纳、阐述了各自适用的隔离措施。同时,对各种隔离措施的优缺点进行了分析说明。基于Matlab/Simulink仿真平台,分别搭建了基于两电平VSC和MMC的直流系统,对相关隔离方法进行了仿真测试、验证与比较,为工程实际中隔离措施的配置提供理论依据。展开更多
基于模块化多电平换流器(modular multilevel converter,MMC)的柔性直流输电系统(flexible high voltage DC transmission based on MMC,MMC-HVDC),在可再生能源的远距离电力输送方面富有潜力。直流线路故障是MMC-HVDC必须解决的关键问...基于模块化多电平换流器(modular multilevel converter,MMC)的柔性直流输电系统(flexible high voltage DC transmission based on MMC,MMC-HVDC),在可再生能源的远距离电力输送方面富有潜力。直流线路故障是MMC-HVDC必须解决的关键问题。提出一种具有直流故障穿越能力的MMC改进拓扑。该拓扑基于二极管嵌位式双子模块,利用子模块电容电压来抑制直流故障的二极管续流效应,关断故障电流通路,从而迅速地清除故障电流。对于瞬时性直流故障,由于故障清除过程中无需断开交流断路器,MMC还能够快速重启、恢复供电。这种改进拓扑附加功率器件的额定电压仅为常规功率器件的一半,额外成本较低。达到同等电压等级,所需子模块数目仅为常规设计的一半,降低了脉冲控制的设计难度和硬件成本。基于PSCAD仿真平台的结果验证了文中所提拓扑和保护方法的有效性。展开更多
Rapid development of renewable energy in China is driving a major shift in the characteristics and control requirements of the electricity grid.Since the best renewable energy resources are far away from load centers ...Rapid development of renewable energy in China is driving a major shift in the characteristics and control requirements of the electricity grid.Since the best renewable energy resources are far away from load centers in the east and southeast,transmission over long distances is required.Over 20 high-voltage DC(HVDC)transmission lines,with a combined capacity exceeding 150 GW,are in operation or are currently under construction.This rapid expansion of new generation and transmission capacities based on power electronics starts to change the characteristics of the grid,especially in areas where they concentrate,creating new stability problems and operational challenges.New system theories and technologies are required to support the development and operation of a future grid that relies more and more on power electronics.This paper highlights the characteristics of power electronics as used in renewable energy generation and HVDC transmission systems,discusses the impacts of these power-electronics-based assets on grid stability and operational requirements,and identifies opportunities for the development of both new system theories and system technologies to support a national energy policy that emphasizes the use of clean energy.展开更多
文摘基于模块化多电平换流器(modular multilevel converter,MMC)的柔性直流输电系统(flexible high voltage DC transmission based on MMC,MMC-HVDC),在可再生能源的远距离电力输送方面富有潜力。直流线路故障是MMC-HVDC必须解决的关键问题。提出一种具有直流故障穿越能力的MMC改进拓扑。该拓扑基于二极管嵌位式双子模块,利用子模块电容电压来抑制直流故障的二极管续流效应,关断故障电流通路,从而迅速地清除故障电流。对于瞬时性直流故障,由于故障清除过程中无需断开交流断路器,MMC还能够快速重启、恢复供电。这种改进拓扑附加功率器件的额定电压仅为常规功率器件的一半,额外成本较低。达到同等电压等级,所需子模块数目仅为常规设计的一半,降低了脉冲控制的设计难度和硬件成本。基于PSCAD仿真平台的结果验证了文中所提拓扑和保护方法的有效性。
基金supported in part by the State Grid Science and Technology Project“Impedance-Based Modeling and Control of Distributed Generation Systems”(NYB1720170218).
文摘Rapid development of renewable energy in China is driving a major shift in the characteristics and control requirements of the electricity grid.Since the best renewable energy resources are far away from load centers in the east and southeast,transmission over long distances is required.Over 20 high-voltage DC(HVDC)transmission lines,with a combined capacity exceeding 150 GW,are in operation or are currently under construction.This rapid expansion of new generation and transmission capacities based on power electronics starts to change the characteristics of the grid,especially in areas where they concentrate,creating new stability problems and operational challenges.New system theories and technologies are required to support the development and operation of a future grid that relies more and more on power electronics.This paper highlights the characteristics of power electronics as used in renewable energy generation and HVDC transmission systems,discusses the impacts of these power-electronics-based assets on grid stability and operational requirements,and identifies opportunities for the development of both new system theories and system technologies to support a national energy policy that emphasizes the use of clean energy.
