Definite-time zero-sequence over-current protection is presently used in systems whose neutral point is grounded by a low resistance(low-resistance grounding systems).These systems frequently malfunction owing to thei...Definite-time zero-sequence over-current protection is presently used in systems whose neutral point is grounded by a low resistance(low-resistance grounding systems).These systems frequently malfunction owing to their high settings of the action value when a high-impedance grounding fault occurs.In this study,the relationship between the zero-sequence currents of each feeder and the neutral branch was analyzed.Then,a grounding protection method was proposed on the basis of the zero-sequence current ratio coefficient.It is defined as the ratio of the zero-sequence current of the feeder to that of the neutral branch.Nonetheless,both zero-sequence voltage and zero-sequence current are affected by the transition resistance,The influence of transition resistance can be eliminated by calculating this coefficient.Therefore,a method based on the zero-sequence current ratio coefficient was proposed considering the significant difference between the faulty feeder and healthy feeder.Furthermore,unbalanced current can be prevented by setting the starting current.PSCAD simulation results reveal that the proposed method shows high reliability and sensitivity when a high-resistance grounding fault occurs.展开更多
The move to Inverter-Based Renewable Resources(IBRs)is a challenge for power system protection since IBRs generate much lower fault currents than traditional synchronous generators.This compromises the operation of co...The move to Inverter-Based Renewable Resources(IBRs)is a challenge for power system protection since IBRs generate much lower fault currents than traditional synchronous generators.This compromises the operation of conventional protection relays.In order to solve this problem,the present study employs a detailed Institute of Electrical and Electronics Engineers(IEEE)9-bus model in Real Time Simulation for Computer Aided Design(RSCAD)to examine the fault behaviour at four different levels of renewable energy penetration.The investigation measures the reduction of the fault current as a result of the gradual substitution of synchronous generation by photovoltaics.The findings enable the production of different sets of relay settings for each case,thus assuring the correct functioning of protection coordination in terms of reliability and selectivity.The main point is an extensive adaptive protection concept.This thoughtful plan serves as an essential guide for the dynamic adjustment of relay settings,thus ensuring the resilience and stability of the grid during the energy transition.展开更多
基金supported in part by National Key Research and Development Program of China(2016YFB0900603)Technology Projects of State Grid Corporation of China(52094017000W).
文摘Definite-time zero-sequence over-current protection is presently used in systems whose neutral point is grounded by a low resistance(low-resistance grounding systems).These systems frequently malfunction owing to their high settings of the action value when a high-impedance grounding fault occurs.In this study,the relationship between the zero-sequence currents of each feeder and the neutral branch was analyzed.Then,a grounding protection method was proposed on the basis of the zero-sequence current ratio coefficient.It is defined as the ratio of the zero-sequence current of the feeder to that of the neutral branch.Nonetheless,both zero-sequence voltage and zero-sequence current are affected by the transition resistance,The influence of transition resistance can be eliminated by calculating this coefficient.Therefore,a method based on the zero-sequence current ratio coefficient was proposed considering the significant difference between the faulty feeder and healthy feeder.Furthermore,unbalanced current can be prevented by setting the starting current.PSCAD simulation results reveal that the proposed method shows high reliability and sensitivity when a high-resistance grounding fault occurs.
文摘The move to Inverter-Based Renewable Resources(IBRs)is a challenge for power system protection since IBRs generate much lower fault currents than traditional synchronous generators.This compromises the operation of conventional protection relays.In order to solve this problem,the present study employs a detailed Institute of Electrical and Electronics Engineers(IEEE)9-bus model in Real Time Simulation for Computer Aided Design(RSCAD)to examine the fault behaviour at four different levels of renewable energy penetration.The investigation measures the reduction of the fault current as a result of the gradual substitution of synchronous generation by photovoltaics.The findings enable the production of different sets of relay settings for each case,thus assuring the correct functioning of protection coordination in terms of reliability and selectivity.The main point is an extensive adaptive protection concept.This thoughtful plan serves as an essential guide for the dynamic adjustment of relay settings,thus ensuring the resilience and stability of the grid during the energy transition.
