Accurate modeling and parameters of high voltage (HV) grid are critical for stability research of system frequency. In this paper, simulation modeling of the system frequency was conducted of an interconnected power...Accurate modeling and parameters of high voltage (HV) grid are critical for stability research of system frequency. In this paper, simulation modeling of the system frequency was conducted of an interconnected power system with HV transmission lines in China. Based on recorded tripping data of the HV transmission lines, system parameters were identified by using genetic algorithm (GA). The favorable agreement between simulation results and recorded data verifies the validity of gird models and the accuracy of system parameters. The results of this paper can provide reference for the stability research of HV power grid.展开更多
Due to the low impedance characteristic of the high voltage direct current(HVDC)grid,the fault current rises extremely fast after a DC-side fault occurs,and this phenomenon seriously endangers the safety of the HVDC g...Due to the low impedance characteristic of the high voltage direct current(HVDC)grid,the fault current rises extremely fast after a DC-side fault occurs,and this phenomenon seriously endangers the safety of the HVDC grid.In order to suppress the rising speed of the fault current and reduce the current interruption requirements of the main breaker(MB),a fault current limiting hybrid DC circuit breaker(FCL-HCB)has been proposed in this paper,and it has the capability of bidirectional fault current limiting and fault current interruption.After the occurrence of the overcurrent in the HVDC grid,the current limiting circuit(CLC)of FCL-HCB is put into operation immediately,and whether the protected line is cut off or resumed to normal operation is decided according to the fault detection result.Compared with the traditional hybrid DC circuit breaker(HCB),the required number of semiconductor switches and the peak value of fault current after fault occurs are greatly reduced by adopting the proposed device.Extensive simulations also verify the effectiveness of the proposed FCL-HCB.展开更多
Multi-terminal high voltage DC(MT-HVDC)grid has broad application prospects in connecting different energy sources,asynchronous interconnection of power grids,remote load power supply,and other fields.At present,the k...Multi-terminal high voltage DC(MT-HVDC)grid has broad application prospects in connecting different energy sources,asynchronous interconnection of power grids,remote load power supply,and other fields.At present,the key technologies that affect the development of MT-HVDC transmission system include swift fault identification and location in the DC line and its rapid isolation.Traditional fault monitoring relies on line communication,which cannot guarantee the rapidity and reliability of protection;moreover,it may even cause device damage.A fault identification scheme based on a single-terminal transient is presented in this paper.This scheme calculates the line inductance by using the rise rate of fault current at the initial stage of the fault,and determines the occurrence of the fault by comparing the observed line inductance with the set value,which lays a foundation for calculating the location of the fault point using distance protection.A simulation model on the PSCAD/EMTDC platform is built;the simulation example verifies that the proposed scheme can identify faults under dissimilar conditions while maintaining a low error level on the premise of no communication lines so as to meet the protection requirements of the MT-HVDC grid.展开更多
文摘Accurate modeling and parameters of high voltage (HV) grid are critical for stability research of system frequency. In this paper, simulation modeling of the system frequency was conducted of an interconnected power system with HV transmission lines in China. Based on recorded tripping data of the HV transmission lines, system parameters were identified by using genetic algorithm (GA). The favorable agreement between simulation results and recorded data verifies the validity of gird models and the accuracy of system parameters. The results of this paper can provide reference for the stability research of HV power grid.
基金This project is funded by the Dongying Science Development Fund Project(DJ2021013).
文摘Due to the low impedance characteristic of the high voltage direct current(HVDC)grid,the fault current rises extremely fast after a DC-side fault occurs,and this phenomenon seriously endangers the safety of the HVDC grid.In order to suppress the rising speed of the fault current and reduce the current interruption requirements of the main breaker(MB),a fault current limiting hybrid DC circuit breaker(FCL-HCB)has been proposed in this paper,and it has the capability of bidirectional fault current limiting and fault current interruption.After the occurrence of the overcurrent in the HVDC grid,the current limiting circuit(CLC)of FCL-HCB is put into operation immediately,and whether the protected line is cut off or resumed to normal operation is decided according to the fault detection result.Compared with the traditional hybrid DC circuit breaker(HCB),the required number of semiconductor switches and the peak value of fault current after fault occurs are greatly reduced by adopting the proposed device.Extensive simulations also verify the effectiveness of the proposed FCL-HCB.
基金Supported by the National Natural Science Foundation of China(51767014)the Scientific and Technological Research and Development Program of the China Railway(2017J010-C/2017).
文摘Multi-terminal high voltage DC(MT-HVDC)grid has broad application prospects in connecting different energy sources,asynchronous interconnection of power grids,remote load power supply,and other fields.At present,the key technologies that affect the development of MT-HVDC transmission system include swift fault identification and location in the DC line and its rapid isolation.Traditional fault monitoring relies on line communication,which cannot guarantee the rapidity and reliability of protection;moreover,it may even cause device damage.A fault identification scheme based on a single-terminal transient is presented in this paper.This scheme calculates the line inductance by using the rise rate of fault current at the initial stage of the fault,and determines the occurrence of the fault by comparing the observed line inductance with the set value,which lays a foundation for calculating the location of the fault point using distance protection.A simulation model on the PSCAD/EMTDC platform is built;the simulation example verifies that the proposed scheme can identify faults under dissimilar conditions while maintaining a low error level on the premise of no communication lines so as to meet the protection requirements of the MT-HVDC grid.