The hybrid dc circuit breaker(HCB)has the advantages of fast action speed and low operating loss,which is an idealmethod for fault isolation ofmulti-terminal dc grids.Formulti-terminal dc grids that transmit power thr...The hybrid dc circuit breaker(HCB)has the advantages of fast action speed and low operating loss,which is an idealmethod for fault isolation ofmulti-terminal dc grids.Formulti-terminal dc grids that transmit power through overhead lines,HCBs are required to have reclosing capability due to the high fault probability and the fact that most of the faults are temporary faults.To avoid the secondary fault strike and equipment damage that may be caused by the reclosing of the HCB when the permanent fault occurs,an adaptive reclosing scheme based on traveling wave injection is proposed in this paper.The scheme injects traveling wave signal into the fault dc line through the additionally configured auxiliary discharge branch in the HCB,and then uses the reflection characteristic of the traveling wave signal on the dc line to identify temporary and permanent faults,to be able to realize fast reclosing when the temporary fault occurs and reliably avoid reclosing after the permanent fault occurs.The test results in the simulation model of the four-terminal dc grid show that the proposed adaptive reclosing scheme can quickly and reliably identify temporary and permanent faults,greatly shorten the power outage time of temporary faults.In addition,it has the advantages of easiness to implement,high reliability,robustness to high-resistance fault and no dead zone,etc.展开更多
Automatic reclosing is widely employed in wind farm transmission lines.However,conventional reclosing strategies cannot identify the nature of the fault before reclosing,thereby posing a risk to the safe opera-tion of...Automatic reclosing is widely employed in wind farm transmission lines.However,conventional reclosing strategies cannot identify the nature of the fault before reclosing,thereby posing a risk to the safe opera-tion of the wind farm transmission system and associated equipment,especially during permanent faults.This study focuses on 220 kV wind farm transmission lines without parallel reactors.A single-phase ground fault circuit model is established first,and expressions for faulted phase-end voltages are derived before and after arc extinction.Then,the variations in voltage amplitude before and after fault arc extinction are revealed.The short-time Fourier transform is employed to extract fundamental frequency voltage amplitude from the sec-ondary side of the capacitive voltage transformer(CVT).Subsequently,an adaptive reclosing strategy based on fundamental frequency voltage amplitude detection for wind farm transmission lines is proposed to enhance fea-ture variations through sequential overlapping derivative(SOD)transformation.Finally,through analysis and validation on the RTDS platform,the proposed adaptive reclosing strategy is demonstrated to be simple,feasible,robust against transient resistances,and characterized by high sensitivity.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
基金supported by the Science and Technology Project of State Grid Corporation of China under Grant 520201210025。
文摘The hybrid dc circuit breaker(HCB)has the advantages of fast action speed and low operating loss,which is an idealmethod for fault isolation ofmulti-terminal dc grids.Formulti-terminal dc grids that transmit power through overhead lines,HCBs are required to have reclosing capability due to the high fault probability and the fact that most of the faults are temporary faults.To avoid the secondary fault strike and equipment damage that may be caused by the reclosing of the HCB when the permanent fault occurs,an adaptive reclosing scheme based on traveling wave injection is proposed in this paper.The scheme injects traveling wave signal into the fault dc line through the additionally configured auxiliary discharge branch in the HCB,and then uses the reflection characteristic of the traveling wave signal on the dc line to identify temporary and permanent faults,to be able to realize fast reclosing when the temporary fault occurs and reliably avoid reclosing after the permanent fault occurs.The test results in the simulation model of the four-terminal dc grid show that the proposed adaptive reclosing scheme can quickly and reliably identify temporary and permanent faults,greatly shorten the power outage time of temporary faults.In addition,it has the advantages of easiness to implement,high reliability,robustness to high-resistance fault and no dead zone,etc.
基金supported by the National Natural Sci-ence Foundation of China(No.52037003)the Major Science and Technology Projects in Yunnan Province(No.202402AG050006).
文摘Automatic reclosing is widely employed in wind farm transmission lines.However,conventional reclosing strategies cannot identify the nature of the fault before reclosing,thereby posing a risk to the safe opera-tion of the wind farm transmission system and associated equipment,especially during permanent faults.This study focuses on 220 kV wind farm transmission lines without parallel reactors.A single-phase ground fault circuit model is established first,and expressions for faulted phase-end voltages are derived before and after arc extinction.Then,the variations in voltage amplitude before and after fault arc extinction are revealed.The short-time Fourier transform is employed to extract fundamental frequency voltage amplitude from the sec-ondary side of the capacitive voltage transformer(CVT).Subsequently,an adaptive reclosing strategy based on fundamental frequency voltage amplitude detection for wind farm transmission lines is proposed to enhance fea-ture variations through sequential overlapping derivative(SOD)transformation.Finally,through analysis and validation on the RTDS platform,the proposed adaptive reclosing strategy is demonstrated to be simple,feasible,robust against transient resistances,and characterized by high sensitivity.
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.
