Multi-terminal direct current(MTDC)grids provide the possibility of meshed interconnections between regional power systems and various renewable energy resources to boost supply reliability and economy.The modular mul...Multi-terminal direct current(MTDC)grids provide the possibility of meshed interconnections between regional power systems and various renewable energy resources to boost supply reliability and economy.The modular multilevel converter(MMC)has become the basic building block for MTDC and DC grids due to its salient features,i.e.,modularity and scalability.Therefore,the MMC-based MTDC systems should be pervasively embedded into the present power system to improve system performance.However,several technical challenges hamper their practical applications and deployment,including modeling,control,and protection of the MMC-MTDC grids.This paper presents a comprehensive investigation and reference in modeling,control,and protection of the MMC-MTDC grids.A general overview of state-of-the-art modeling techniques of the MMC along with their performance in simulation analysis for MTDC applications is provided.A review of control strategies of the MMC-MTDC grids which provide AC system support is presented.State-of-the art protection techniques of the MMCMTDC systems are also investigated.Finally,the associated research challenges and trends are highlighted.展开更多
近年来,国内外对模块化多电平换流器(modular multilevel converter,MMC)的研究主要集中于系统建模仿真、控制系统设计等方面。对基于模块化多电平换流器的高压直流输电系统(modular multilevel converter based high voltagedirect cur...近年来,国内外对模块化多电平换流器(modular multilevel converter,MMC)的研究主要集中于系统建模仿真、控制系统设计等方面。对基于模块化多电平换流器的高压直流输电系统(modular multilevel converter based high voltagedirect current system,MMC-HVDC)直流线路故障的研究也仅是在简单的故障定性仿真分析上。为了比较精确地定量分析MMC-HVDC系统直流侧故障瞬间电气应力的暂态特性、短路故障状态下的等值电路模型,分析了系统直流侧故障的机理,给出了故障电压、电流的数学表达式。基于RT-LAB软件搭建了双端MMC-HVDC仿真模型,验证了故障暂态特性分析的结果,单极接地故障使得直流非故障极的对地电压与换流站交流侧的相电压增大;双极短路故障会引起换流站的桥臂产生严重的过电流现象;单极断线故障会导致整流站很大的直流电压变化率,引起严重直流过电压。针对上述问题,文章结合分析结果给出了相应的故障保护要求和策略。展开更多
针对宜宾–金华特高压直流全压运行极线路故障重起动过程中,健全的半压运行极出现短时间功率大幅下降的问题进行深入分析。在简要介绍低压限流(voltage dependent current order limiter,VDCOL)等直流系统基本控制原理的基础上,利用楞...针对宜宾–金华特高压直流全压运行极线路故障重起动过程中,健全的半压运行极出现短时间功率大幅下降的问题进行深入分析。在简要介绍低压限流(voltage dependent current order limiter,VDCOL)等直流系统基本控制原理的基础上,利用楞次定律分析了直流线路故障再起动期间故障极对健全极的电磁感应特性,研究并推导了特高压直流双极线路间互感计算公式,揭示了健全极电磁感应电流产生的原理和及其对控制特性的影响,并提出防止一极线路故障引起健全极功率短时间大幅下降的直流控制措施,利用与宾金直流一次系统和实际控制保护程序完全一致的仿真模型验证了改进措施的可行性和有效性,对工程设计及现场运行具有很强的指导意义。展开更多
基金funded by SGCC Science and Technology Program under project Research on Electromagnetic Transient Simulation Technology for Large-scale MMC-HVDC Systems.
文摘Multi-terminal direct current(MTDC)grids provide the possibility of meshed interconnections between regional power systems and various renewable energy resources to boost supply reliability and economy.The modular multilevel converter(MMC)has become the basic building block for MTDC and DC grids due to its salient features,i.e.,modularity and scalability.Therefore,the MMC-based MTDC systems should be pervasively embedded into the present power system to improve system performance.However,several technical challenges hamper their practical applications and deployment,including modeling,control,and protection of the MMC-MTDC grids.This paper presents a comprehensive investigation and reference in modeling,control,and protection of the MMC-MTDC grids.A general overview of state-of-the-art modeling techniques of the MMC along with their performance in simulation analysis for MTDC applications is provided.A review of control strategies of the MMC-MTDC grids which provide AC system support is presented.State-of-the art protection techniques of the MMCMTDC systems are also investigated.Finally,the associated research challenges and trends are highlighted.
文摘近年来,国内外对模块化多电平换流器(modular multilevel converter,MMC)的研究主要集中于系统建模仿真、控制系统设计等方面。对基于模块化多电平换流器的高压直流输电系统(modular multilevel converter based high voltagedirect current system,MMC-HVDC)直流线路故障的研究也仅是在简单的故障定性仿真分析上。为了比较精确地定量分析MMC-HVDC系统直流侧故障瞬间电气应力的暂态特性、短路故障状态下的等值电路模型,分析了系统直流侧故障的机理,给出了故障电压、电流的数学表达式。基于RT-LAB软件搭建了双端MMC-HVDC仿真模型,验证了故障暂态特性分析的结果,单极接地故障使得直流非故障极的对地电压与换流站交流侧的相电压增大;双极短路故障会引起换流站的桥臂产生严重的过电流现象;单极断线故障会导致整流站很大的直流电压变化率,引起严重直流过电压。针对上述问题,文章结合分析结果给出了相应的故障保护要求和策略。
文摘针对宜宾–金华特高压直流全压运行极线路故障重起动过程中,健全的半压运行极出现短时间功率大幅下降的问题进行深入分析。在简要介绍低压限流(voltage dependent current order limiter,VDCOL)等直流系统基本控制原理的基础上,利用楞次定律分析了直流线路故障再起动期间故障极对健全极的电磁感应特性,研究并推导了特高压直流双极线路间互感计算公式,揭示了健全极电磁感应电流产生的原理和及其对控制特性的影响,并提出防止一极线路故障引起健全极功率短时间大幅下降的直流控制措施,利用与宾金直流一次系统和实际控制保护程序完全一致的仿真模型验证了改进措施的可行性和有效性,对工程设计及现场运行具有很强的指导意义。
