This study presents a harmonic transfer function(HTF)based single-input single-output(SISO)impedance modeling method.The method converts an HTF from phase domain to sequence domain and then transforms it into an SISO ...This study presents a harmonic transfer function(HTF)based single-input single-output(SISO)impedance modeling method.The method converts an HTF from phase domain to sequence domain and then transforms it into an SISO impedance while preserving the frequency coupling information of different sequences and different harmonics.Applications of this method to a line-commutated converter based high-voltage direct current(LCC-HVDC)system are presented.The results demonstrate the accuracy of the derived SISO impedance,and a truncation-order selection is suggested.The case study shows that the proposed method facilitates simpler impedance measurements and associated stability analysis.展开更多
With the rapid development of renewable energy,wind-thermal-bundled power transmission by line-commutated converter based high-voltage direct current(LCC-HVDC)systems has been widely developed.The dynamic interaction ...With the rapid development of renewable energy,wind-thermal-bundled power transmission by line-commutated converter based high-voltage direct current(LCC-HVDC)systems has been widely developed.The dynamic interaction mechanisms among permanent magnet synchronous generators(PMSGs),synchronous generators(SGs),and LCC-HVDC system become complex.To deal with this issue,a path analysis method(PAM)is proposed to study the dynamic interaction mechanism,and the damping reconstruction is used to analyze the damping characteristic of the system.First,based on the modular modeling,linearized models for the PMSG subsystem,the LCC-HVDC subsystem,and the SG subsystem are established.Second,based on the closed-loop transfer function diagram of the system,the disturbance transfer path and coupling relationship among subsystems are analyzed by the PAM,and the damping characteristic analysis of the SG-dominated oscillation mode is studied based on the damping reconstruction.Compared with the PAM,the small-signal model of the system is obtained and eigenvalue analysis results are presented.Then,the effect of the control parameters on the damping characteristic is analyzed and the conclusions are verified by time-domain simulations.Finally,the penalty functions of the oscillation modes and decay modes are taken as the objective function,and an optimization strategy based on the Monte Carlo method is proposed to solve the parameter optimization problem.Numerical simulation results are presented to validate the effectiveness of the proposed strategy.展开更多
The series line-commutated converter(LCC)and modular multilevel converter(MMC)hybrid high-voltage direct current(HVDC)system provides a more economical and flexible alternative for ultra-HVDC(UHVDC)transmission,which ...The series line-commutated converter(LCC)and modular multilevel converter(MMC)hybrid high-voltage direct current(HVDC)system provides a more economical and flexible alternative for ultra-HVDC(UHVDC)transmission,which is the so-called Baihetan-Jiangsu HVDC(BJ-HVDC)project of China.In one LCC and two MMCs(1+2)operation mode,the sub-module(SM)capacitors suffer the most rigorous overvoltage induced by three-phase-to-ground fault at grid-side MMC and valve-side single-phase-to-ground fault in internal MMC.In order to suppress such huge overvoltage,this paper demonstrates a novel alternative by employing the MMC-based embedded battery energy storage system(MMC-BESS).Firstly,the inducements of SM overvoltage are analyzed.Then,coordinated with MMC-BESS,new fault ride-through(FRT)strategies are proposed to suppress the overvoltage and improve the FRT capability.Finally,several simulation scenarios are carried out on PSCAD/EMTDC.The overvoltage suppression is verified against auxiliary device used in the BJ-HVDC project in a monopolar BJ-HVDC system.Further,the proposed FRT strategies are validated in the southern Jiangsu power grid of China based on the planning data in the summer of 2025.Simulation results show that the MMC-BESS and proposed FRT strategies could effectively suppress the overvoltage and improve the FRT capability.展开更多
Subsequent commutation failure(SCF)can be easily generated during the first commutation failure(CF)recovery process in a line-commutated converter-based high voltage direct-current system.SCF poses a significant threa...Subsequent commutation failure(SCF)can be easily generated during the first commutation failure(CF)recovery process in a line-commutated converter-based high voltage direct-current system.SCF poses a significant threat to the safe and stable operation of power systems,and accurate prediction of CF is thus important.However,SCF is affected by the operating characteristics of the main circuit and the coupling effects of sequential control response in the inverter station.These are difficult to predict accurately.In this paper,a new SCF prediction method considering the control response is proposed based on the physical principle of SCF.The time sequence and switching conditions of the controllers at different stages of the first CF recovery process are described,and the corresponding equations of commutation voltage affected by different controllers are derived.The calculation method of the SCF threshold voltage is proposed,and the prediction method is established.Simulations show that the proposed method can predict SCF accurately and provide useful tools to suppress SCF.展开更多
The recent in-depth development of hybrid highvoltage direct current(HVDC) transmission systems poses looming adaptability challenges to protection. The various and disparate direct current(DC) transmission topologies...The recent in-depth development of hybrid highvoltage direct current(HVDC) transmission systems poses looming adaptability challenges to protection. The various and disparate direct current(DC) transmission topologies can profoundly affect the operating characteristics of DC transmission networks, which result in the lack of performance of conventional DC protection schemes in such topologies. This significantly limits the application of hybrid HVDC technologies. This paper proposes a single-end protection scheme based on the transient power waveshape for fast and sensitive detection and classification of different types of DC faults in hybrid HVDC transmission lines. The fault characteristics and their causes under different fault conditions are analyzed in detail with a pre-introduced linearized transient model of a hybrid HVDC transmission system, demonstrating that the formation of the fluctuation characteristics of local measurements is mainly determined by the buffering and absorption effects of lumped-parameter reactors on transient traveling-wave(TW) energy. Simulation results verify the sensitivity, rapidity, reliability, and anti-interference ability of the proposed scheme when applied to hybrid HVDC transmission lines. Furthermore, it is confirmed that the proposed scheme is adaptable to symmetric voltage-sourced converter(VSC) and conventional line-commutated converter(LCC) based HVDC transmission lines.展开更多
基金supported by National Natural Science Foundation of China(No.52177104).
文摘This study presents a harmonic transfer function(HTF)based single-input single-output(SISO)impedance modeling method.The method converts an HTF from phase domain to sequence domain and then transforms it into an SISO impedance while preserving the frequency coupling information of different sequences and different harmonics.Applications of this method to a line-commutated converter based high-voltage direct current(LCC-HVDC)system are presented.The results demonstrate the accuracy of the derived SISO impedance,and a truncation-order selection is suggested.The case study shows that the proposed method facilitates simpler impedance measurements and associated stability analysis.
基金supported in part by the National Natural Science Foundation of China(No.U22B20109).
文摘With the rapid development of renewable energy,wind-thermal-bundled power transmission by line-commutated converter based high-voltage direct current(LCC-HVDC)systems has been widely developed.The dynamic interaction mechanisms among permanent magnet synchronous generators(PMSGs),synchronous generators(SGs),and LCC-HVDC system become complex.To deal with this issue,a path analysis method(PAM)is proposed to study the dynamic interaction mechanism,and the damping reconstruction is used to analyze the damping characteristic of the system.First,based on the modular modeling,linearized models for the PMSG subsystem,the LCC-HVDC subsystem,and the SG subsystem are established.Second,based on the closed-loop transfer function diagram of the system,the disturbance transfer path and coupling relationship among subsystems are analyzed by the PAM,and the damping characteristic analysis of the SG-dominated oscillation mode is studied based on the damping reconstruction.Compared with the PAM,the small-signal model of the system is obtained and eigenvalue analysis results are presented.Then,the effect of the control parameters on the damping characteristic is analyzed and the conclusions are verified by time-domain simulations.Finally,the penalty functions of the oscillation modes and decay modes are taken as the objective function,and an optimization strategy based on the Monte Carlo method is proposed to solve the parameter optimization problem.Numerical simulation results are presented to validate the effectiveness of the proposed strategy.
文摘The series line-commutated converter(LCC)and modular multilevel converter(MMC)hybrid high-voltage direct current(HVDC)system provides a more economical and flexible alternative for ultra-HVDC(UHVDC)transmission,which is the so-called Baihetan-Jiangsu HVDC(BJ-HVDC)project of China.In one LCC and two MMCs(1+2)operation mode,the sub-module(SM)capacitors suffer the most rigorous overvoltage induced by three-phase-to-ground fault at grid-side MMC and valve-side single-phase-to-ground fault in internal MMC.In order to suppress such huge overvoltage,this paper demonstrates a novel alternative by employing the MMC-based embedded battery energy storage system(MMC-BESS).Firstly,the inducements of SM overvoltage are analyzed.Then,coordinated with MMC-BESS,new fault ride-through(FRT)strategies are proposed to suppress the overvoltage and improve the FRT capability.Finally,several simulation scenarios are carried out on PSCAD/EMTDC.The overvoltage suppression is verified against auxiliary device used in the BJ-HVDC project in a monopolar BJ-HVDC system.Further,the proposed FRT strategies are validated in the southern Jiangsu power grid of China based on the planning data in the summer of 2025.Simulation results show that the MMC-BESS and proposed FRT strategies could effectively suppress the overvoltage and improve the FRT capability.
基金supported in part by the National Natural Science Foundation of China under Grant(51877018).
文摘Subsequent commutation failure(SCF)can be easily generated during the first commutation failure(CF)recovery process in a line-commutated converter-based high voltage direct-current system.SCF poses a significant threat to the safe and stable operation of power systems,and accurate prediction of CF is thus important.However,SCF is affected by the operating characteristics of the main circuit and the coupling effects of sequential control response in the inverter station.These are difficult to predict accurately.In this paper,a new SCF prediction method considering the control response is proposed based on the physical principle of SCF.The time sequence and switching conditions of the controllers at different stages of the first CF recovery process are described,and the corresponding equations of commutation voltage affected by different controllers are derived.The calculation method of the SCF threshold voltage is proposed,and the prediction method is established.Simulations show that the proposed method can predict SCF accurately and provide useful tools to suppress SCF.
基金supported by the Science and Technology Project of State Grid Corporation of China “Research on ultra-high-speed protection and fault isolation technology of transmission lines in DC power grid with different structures”(No. 5100-202155030A-0-0-00)。
文摘The recent in-depth development of hybrid highvoltage direct current(HVDC) transmission systems poses looming adaptability challenges to protection. The various and disparate direct current(DC) transmission topologies can profoundly affect the operating characteristics of DC transmission networks, which result in the lack of performance of conventional DC protection schemes in such topologies. This significantly limits the application of hybrid HVDC technologies. This paper proposes a single-end protection scheme based on the transient power waveshape for fast and sensitive detection and classification of different types of DC faults in hybrid HVDC transmission lines. The fault characteristics and their causes under different fault conditions are analyzed in detail with a pre-introduced linearized transient model of a hybrid HVDC transmission system, demonstrating that the formation of the fluctuation characteristics of local measurements is mainly determined by the buffering and absorption effects of lumped-parameter reactors on transient traveling-wave(TW) energy. Simulation results verify the sensitivity, rapidity, reliability, and anti-interference ability of the proposed scheme when applied to hybrid HVDC transmission lines. Furthermore, it is confirmed that the proposed scheme is adaptable to symmetric voltage-sourced converter(VSC) and conventional line-commutated converter(LCC) based HVDC transmission lines.
