Multi-terminal hybrid high-voltage direct current(HVDC)systems have been developed quickly in recent years in power transmission area.However,for voltage-source converter(VSC)stations in hybrid HVDC systems,no direct ...Multi-terminal hybrid high-voltage direct current(HVDC)systems have been developed quickly in recent years in power transmission area.However,for voltage-source converter(VSC)stations in hybrid HVDC systems,no direct current(DC)filters are required.In addition,the DC reactor is also not installed at the line end because the DC fault can be limited by the converter itself.This means that the boundary element at the line end is absent,and the single-ended protections used in line commutated converter(LCC)based HVDC(LCC-HVDC)systems or VSC-HVDC systems cannot distinguish the fault line in multi-terminal hybrid HVDC systems.This paper proposes a novel singleended DC protection strategy suitable for the multi-terminal hybrid HVDC system,which mainly applies the transient information and active injection concept to detect and distinguish the fault line.Compared with the single-ended protections used in LCC-HVDC and VSC-HVDC systems,the proposed protection strategy is not dependent on the line boundary element and is thus suitable for the multiterminal hybrid HVDC system.The corresponding simulation cases based on power systems computer aided design(PSCAD)/electromagnetic transients including DC(EMTDC)are carried out to verify the superiority of the proposed protection.展开更多
A fault identification scheme for protection and adaptive reclosing is proposed for a hybrid multi-terminal HVDC system to increase the reliability of fault isolation and reclosing.By analyzing the"zero passing&q...A fault identification scheme for protection and adaptive reclosing is proposed for a hybrid multi-terminal HVDC system to increase the reliability of fault isolation and reclosing.By analyzing the"zero passing"characteristic of current at the local end during the converter capacitor discharge stage,the fault identification scheme is proposed.The distributed parameter-based fault location equation,which incorporates fault distance and fault impedance,is developed with the injection signal and the distributed parameter model during the adaptive reclosing stage.The fault distance is determined using a trust region reflection algorithm to identify the permanent fault,and a fault iden-tification scheme for adaptive reclosing is developed.Simulation results show that the proposed scheme is suitable for long-distance transmission lines with strong anti-fault impedance and anti-interference performance.Also,it is less affected by communication delay and DC boundary strength than existing methods.展开更多
提出了两种含VSC-MTDC的交、直流系统潮流控制算法,即节点注入电流法和改进序列潮流算法。节点注入电流法中,以各端公共耦合点PCC(point of common coupling)作为交替求解的接口,VSC-MTDC系统对交流系统的影响通过改变PCC点的注入电流...提出了两种含VSC-MTDC的交、直流系统潮流控制算法,即节点注入电流法和改进序列潮流算法。节点注入电流法中,以各端公共耦合点PCC(point of common coupling)作为交替求解的接口,VSC-MTDC系统对交流系统的影响通过改变PCC点的注入电流来实现。针对节点注入电流法中由于接口变量数目较多而导致收敛性能变差的问题,改进了序列潮流算法,只需设置主站PCC点传输的有功功率作为接口变量进行迭代更新,直至收敛。在新英格兰系统上验证了两种所提算法的有效性和可行性。对比分析两种方法可知,改进序列潮流算法总体性能优于节点注入电流法,为含VSC-MTDC的交、直流系统潮流算法的选择提供参考。展开更多
文摘Multi-terminal hybrid high-voltage direct current(HVDC)systems have been developed quickly in recent years in power transmission area.However,for voltage-source converter(VSC)stations in hybrid HVDC systems,no direct current(DC)filters are required.In addition,the DC reactor is also not installed at the line end because the DC fault can be limited by the converter itself.This means that the boundary element at the line end is absent,and the single-ended protections used in line commutated converter(LCC)based HVDC(LCC-HVDC)systems or VSC-HVDC systems cannot distinguish the fault line in multi-terminal hybrid HVDC systems.This paper proposes a novel singleended DC protection strategy suitable for the multi-terminal hybrid HVDC system,which mainly applies the transient information and active injection concept to detect and distinguish the fault line.Compared with the single-ended protections used in LCC-HVDC and VSC-HVDC systems,the proposed protection strategy is not dependent on the line boundary element and is thus suitable for the multiterminal hybrid HVDC system.The corresponding simulation cases based on power systems computer aided design(PSCAD)/electromagnetic transients including DC(EMTDC)are carried out to verify the superiority of the proposed protection.
基金supported by the Technology Projects of Southern Power Grid Electric Power Research Institute of China(SEPRI-K22B055)National Nature Science Foundation project(2021YFB1507000,2021YFB1507004)the Natural Science Foundation of Xinjiang Uygur Autonomous Region(2022D01C662).
文摘A fault identification scheme for protection and adaptive reclosing is proposed for a hybrid multi-terminal HVDC system to increase the reliability of fault isolation and reclosing.By analyzing the"zero passing"characteristic of current at the local end during the converter capacitor discharge stage,the fault identification scheme is proposed.The distributed parameter-based fault location equation,which incorporates fault distance and fault impedance,is developed with the injection signal and the distributed parameter model during the adaptive reclosing stage.The fault distance is determined using a trust region reflection algorithm to identify the permanent fault,and a fault iden-tification scheme for adaptive reclosing is developed.Simulation results show that the proposed scheme is suitable for long-distance transmission lines with strong anti-fault impedance and anti-interference performance.Also,it is less affected by communication delay and DC boundary strength than existing methods.
文摘提出了两种含VSC-MTDC的交、直流系统潮流控制算法,即节点注入电流法和改进序列潮流算法。节点注入电流法中,以各端公共耦合点PCC(point of common coupling)作为交替求解的接口,VSC-MTDC系统对交流系统的影响通过改变PCC点的注入电流来实现。针对节点注入电流法中由于接口变量数目较多而导致收敛性能变差的问题,改进了序列潮流算法,只需设置主站PCC点传输的有功功率作为接口变量进行迭代更新,直至收敛。在新英格兰系统上验证了两种所提算法的有效性和可行性。对比分析两种方法可知,改进序列潮流算法总体性能优于节点注入电流法,为含VSC-MTDC的交、直流系统潮流算法的选择提供参考。
