As a new generation of direct current(DC)transmission technology,voltage sourced converter(VSC)based high voltage direct current(HVDC)has been widely developed and applied all over the world.China has also carried out...As a new generation of direct current(DC)transmission technology,voltage sourced converter(VSC)based high voltage direct current(HVDC)has been widely developed and applied all over the world.China has also carried out a deep technical research and engineering application in this area,and at present,it has been stepped into a fast growing period.This paper gives a general review over China’s VSC based HVDC in terms of engineering technology,application and future development.It comprehensively analyzes the technical difficulties and future development orientation on the aspects of the main configurations of VSC based HVDC system,topological structures of converters,control and protection technologies,flexible DC cables,converter valve tests,etc.It introduces the applicable fields and current status of China’s VSC based HVDC projects,and analyzes the application trends of VSC based HVDC projects both in China and all over the world according to the development characteristics and demands of future power grids.展开更多
Voltage source converter(VSC) based high voltage direct current(HVDC) transmission is most suited for the wind farm as it allows flexibility for reactive power control in multi-terminal transmission lines and transmit...Voltage source converter(VSC) based high voltage direct current(HVDC) transmission is most suited for the wind farm as it allows flexibility for reactive power control in multi-terminal transmission lines and transmits low power over smaller distance. In this work, a new method has been proposed to detect the fault, identify the section of faults and classify the pole of the fault in DC transmission lines fed from onshore wind farm. In the proposed scheme, voltage signal from rectifier end terminal is extracted with sampling frequency of 1 k Hz given as the input to the detection, classification and section discrimi-nation module. In this work, severe AC faults are also considered for section discrimination. Proposed method uses fuzzy inference system(FIS) to carry out all relaying task. The reach setting of the relay is 99.9% of the transmission line. Besides, the protection covers and discriminates the grounding fault with fault resistance up to 300 Ω.Considering the results of the proposed method, it can beused effectively in real power network.展开更多
In the voltage source converter based high-voltage direct current(VSC-HVDC)grids,fast and reliable protections are the key technologies.The traditional protection schemes are easily affected by fault resistance,line d...In the voltage source converter based high-voltage direct current(VSC-HVDC)grids,fast and reliable protections are the key technologies.The traditional protection schemes are easily affected by fault resistance,line distributed capacitance,etc.Meanwhile,the influence of fault current limiting strategy(FCLS)has not been fully considered.In this paper,the fault characteristics under FCLS and the feasibility of traditional travelling wave protections are analyzed.To improve the reliability and sensibility,a similarity comparison based pilot protection scheme is proposed,which focuses on the relationship between the fault characteristics and the state of the protected transmission line,with the establishment of a precise frequencydependent transmission line model.The criteria based on the similarity comparison calculated by cross-wavelet can identify the fault effectively.Meanwhile,the protection scheme can also endure the influence of error synchronization.Finally,the protection performance is verified in the PSCAD/EMTDC under different fault conditions.展开更多
基于电压源换流器高压直流输电(voltage source converter based HVDC,VSC-HVDC)的直流系统存在与交流线路并联运行的情况。交直流系统之间相互切换的运行工况复杂,且切换过程存在切换依据难以确定、切换冲击大以及通信延时等问题。为...基于电压源换流器高压直流输电(voltage source converter based HVDC,VSC-HVDC)的直流系统存在与交流线路并联运行的情况。交直流系统之间相互切换的运行工况复杂,且切换过程存在切换依据难以确定、切换冲击大以及通信延时等问题。为解决该问题,在分析VSC-HVDC工作原理、数学模型及其控制策略的基础上,提出了一种大型风电场经VSC-HVDC交直流并联系统并网的运行控制策略,该策略在不改变换流站控制方式的情况下,可实现交直流并联系统运行方式的无缝切换。基于MATLAB/Simulink仿真软件,建立了系统仿真模型,对交直流并联系统稳态运行及动态切换过程进行了仿真分析。仿真结果表明,所提出的控制策略能够较好地实现交直流并联系统有功功率的精确分配和运行方式的无缝切换,算法简单,可靠性高。展开更多
建立了含柔性直流输电(voltage source converter based high voltage direct current,VSC-HVDC)的交直流混合发输电系统的可靠性分析模型,该模型既考虑了VSC-HVDC的稳态功率特性,还计及了发输电网络的故障率和输电线路的有功限制,采用...建立了含柔性直流输电(voltage source converter based high voltage direct current,VSC-HVDC)的交直流混合发输电系统的可靠性分析模型,该模型既考虑了VSC-HVDC的稳态功率特性,还计及了发输电网络的故障率和输电线路的有功限制,采用非序惯蒙特卡罗仿真实现;在满足系统安全约束的前提条件下,对系统进行模拟调度,重点评价了与发输电网络连接的VSC-HVDC对电网可靠性的影响,给出系统和节点的风险指标,为VSC-HVDC规划和运行提供参考依据,最后算例分析证明了该算法的可行性和合理性。展开更多
在传统控制方式下,柔性直流输电(voltage source converter based high voltage direct current,VSC-HVDC)系统换流站难以有效参与电网动态调节,而虚拟同步电机技术通过合适的控制设计使得换流器单元能够为系统提供惯性支撑,已引起广泛...在传统控制方式下,柔性直流输电(voltage source converter based high voltage direct current,VSC-HVDC)系统换流站难以有效参与电网动态调节,而虚拟同步电机技术通过合适的控制设计使得换流器单元能够为系统提供惯性支撑,已引起广泛关注。首先结合VSC-HVDC系统数学模型,分析换流站等效为同步电机的可行性,给出基于虚拟同步电机技术的换流站控制方案。其次,针对整流侧换流站,在动态过程中将逆变侧等效为一个恒功率负载,建立虚拟同步电机内环和电压外环的小信号数学模型,分析并给出一种系统化的控制参数设计方法。最后,通过仿真分析验证文中理论分析的正确性和参数设计方法的有效性。展开更多
针对基于电压源换流器的高压直流输电(voltage source converter based high voltage direct current,VSC-HVDC),提出了基于永磁同步风力发电机、不控整流和Boost电路的变速直流风力发电系统结构。首先给出先并后串的新型风电场结构;然...针对基于电压源换流器的高压直流输电(voltage source converter based high voltage direct current,VSC-HVDC),提出了基于永磁同步风力发电机、不控整流和Boost电路的变速直流风力发电系统结构。首先给出先并后串的新型风电场结构;然后建立最小串联系统的简化模型,用一种基于直流电压电流乘积控制的最大风能跟踪控制算法解析出输出电压和输出功率的关系。仿真结果表明:最小串联系统中的2个机组可以互不影响地独立运行,输出电压按照输出功率的变化而变化,同时2个机组均具有较好的最大风能跟踪精度和速度。展开更多
过电流关断试验是柔性直流输电(voltage sourced converter based high voltage direct current transmission,VSC-HVDC)换流阀暂态试验之一,是为了检验换流阀设计的正确性及对桥臂直通工况应力耐受性进行的试验。研究阀过电流关断试验...过电流关断试验是柔性直流输电(voltage sourced converter based high voltage direct current transmission,VSC-HVDC)换流阀暂态试验之一,是为了检验换流阀设计的正确性及对桥臂直通工况应力耐受性进行的试验。研究阀过电流关断试验的试验方法,分析桥臂直通工况下的应力,提出等效试验方法并设计试验电路,最后给出试验电路中阀的应力波形与实际工况下应力波形的对比,结合关键应力等效性分析,验证试验方法和试验电路的等效性。展开更多
基金This work was supported by National Natural Science Foundation of China(No.51261130471).
文摘As a new generation of direct current(DC)transmission technology,voltage sourced converter(VSC)based high voltage direct current(HVDC)has been widely developed and applied all over the world.China has also carried out a deep technical research and engineering application in this area,and at present,it has been stepped into a fast growing period.This paper gives a general review over China’s VSC based HVDC in terms of engineering technology,application and future development.It comprehensively analyzes the technical difficulties and future development orientation on the aspects of the main configurations of VSC based HVDC system,topological structures of converters,control and protection technologies,flexible DC cables,converter valve tests,etc.It introduces the applicable fields and current status of China’s VSC based HVDC projects,and analyzes the application trends of VSC based HVDC projects both in China and all over the world according to the development characteristics and demands of future power grids.
文摘Voltage source converter(VSC) based high voltage direct current(HVDC) transmission is most suited for the wind farm as it allows flexibility for reactive power control in multi-terminal transmission lines and transmits low power over smaller distance. In this work, a new method has been proposed to detect the fault, identify the section of faults and classify the pole of the fault in DC transmission lines fed from onshore wind farm. In the proposed scheme, voltage signal from rectifier end terminal is extracted with sampling frequency of 1 k Hz given as the input to the detection, classification and section discrimi-nation module. In this work, severe AC faults are also considered for section discrimination. Proposed method uses fuzzy inference system(FIS) to carry out all relaying task. The reach setting of the relay is 99.9% of the transmission line. Besides, the protection covers and discriminates the grounding fault with fault resistance up to 300 Ω.Considering the results of the proposed method, it can beused effectively in real power network.
基金supported by National Natural Science Foundation of ChinaState Grid Joint Fund for Smart Grid(No.U2066210)National Natural Science Foundation of China(No.52007003)。
文摘In the voltage source converter based high-voltage direct current(VSC-HVDC)grids,fast and reliable protections are the key technologies.The traditional protection schemes are easily affected by fault resistance,line distributed capacitance,etc.Meanwhile,the influence of fault current limiting strategy(FCLS)has not been fully considered.In this paper,the fault characteristics under FCLS and the feasibility of traditional travelling wave protections are analyzed.To improve the reliability and sensibility,a similarity comparison based pilot protection scheme is proposed,which focuses on the relationship between the fault characteristics and the state of the protected transmission line,with the establishment of a precise frequencydependent transmission line model.The criteria based on the similarity comparison calculated by cross-wavelet can identify the fault effectively.Meanwhile,the protection scheme can also endure the influence of error synchronization.Finally,the protection performance is verified in the PSCAD/EMTDC under different fault conditions.
文摘基于电压源换流器高压直流输电(voltage source converter based HVDC,VSC-HVDC)的直流系统存在与交流线路并联运行的情况。交直流系统之间相互切换的运行工况复杂,且切换过程存在切换依据难以确定、切换冲击大以及通信延时等问题。为解决该问题,在分析VSC-HVDC工作原理、数学模型及其控制策略的基础上,提出了一种大型风电场经VSC-HVDC交直流并联系统并网的运行控制策略,该策略在不改变换流站控制方式的情况下,可实现交直流并联系统运行方式的无缝切换。基于MATLAB/Simulink仿真软件,建立了系统仿真模型,对交直流并联系统稳态运行及动态切换过程进行了仿真分析。仿真结果表明,所提出的控制策略能够较好地实现交直流并联系统有功功率的精确分配和运行方式的无缝切换,算法简单,可靠性高。
文摘建立了含柔性直流输电(voltage source converter based high voltage direct current,VSC-HVDC)的交直流混合发输电系统的可靠性分析模型,该模型既考虑了VSC-HVDC的稳态功率特性,还计及了发输电网络的故障率和输电线路的有功限制,采用非序惯蒙特卡罗仿真实现;在满足系统安全约束的前提条件下,对系统进行模拟调度,重点评价了与发输电网络连接的VSC-HVDC对电网可靠性的影响,给出系统和节点的风险指标,为VSC-HVDC规划和运行提供参考依据,最后算例分析证明了该算法的可行性和合理性。
文摘在传统控制方式下,柔性直流输电(voltage source converter based high voltage direct current,VSC-HVDC)系统换流站难以有效参与电网动态调节,而虚拟同步电机技术通过合适的控制设计使得换流器单元能够为系统提供惯性支撑,已引起广泛关注。首先结合VSC-HVDC系统数学模型,分析换流站等效为同步电机的可行性,给出基于虚拟同步电机技术的换流站控制方案。其次,针对整流侧换流站,在动态过程中将逆变侧等效为一个恒功率负载,建立虚拟同步电机内环和电压外环的小信号数学模型,分析并给出一种系统化的控制参数设计方法。最后,通过仿真分析验证文中理论分析的正确性和参数设计方法的有效性。
文摘针对基于电压源换流器的高压直流输电(voltage source converter based high voltage direct current,VSC-HVDC),提出了基于永磁同步风力发电机、不控整流和Boost电路的变速直流风力发电系统结构。首先给出先并后串的新型风电场结构;然后建立最小串联系统的简化模型,用一种基于直流电压电流乘积控制的最大风能跟踪控制算法解析出输出电压和输出功率的关系。仿真结果表明:最小串联系统中的2个机组可以互不影响地独立运行,输出电压按照输出功率的变化而变化,同时2个机组均具有较好的最大风能跟踪精度和速度。
文摘过电流关断试验是柔性直流输电(voltage sourced converter based high voltage direct current transmission,VSC-HVDC)换流阀暂态试验之一,是为了检验换流阀设计的正确性及对桥臂直通工况应力耐受性进行的试验。研究阀过电流关断试验的试验方法,分析桥臂直通工况下的应力,提出等效试验方法并设计试验电路,最后给出试验电路中阀的应力波形与实际工况下应力波形的对比,结合关键应力等效性分析,验证试验方法和试验电路的等效性。