In a DC grid with dedicated metallic return(DMR),the coupling effects among the positive pole,negative pole,and DMR conductors must be considered,which makes fault identification particularly difficult.In addition,the...In a DC grid with dedicated metallic return(DMR),the coupling effects among the positive pole,negative pole,and DMR conductors must be considered,which makes fault identification particularly difficult.In addition,the identification of high-impedance faults remains a major challenge for DC grid protection.To address these issues,this study proposes an adaptive single-end protection method for DC grid based on the transient mean value of the current limiting reactor(CLR)modal voltage.First,a fault analysis model of the DC grid with DMR is established using the Clarke transformation.The characteristics of CLR modal voltage are then clarified.A fault pole-selection method based on a novel modulus phase plane is next proposed.A threshold scaling factor based on the differential of DC bus voltage is then constructed to enhance the sensitivity and rapidity of the protection,which can adaptively modify the threshold according to the fault severity.Finally,a simulation model of a four-terminal DC grid with DMR is developed in PSCAD/EMTDC.The speed and reliability of the proposed protection method are verified by simulations and experiments.展开更多
The estimation of sequence or symmetrical components and frequency in three-phase unbalanced power system is of great importance for protection and relay.This paper proposes a new H∞filter based on sparse model to tr...The estimation of sequence or symmetrical components and frequency in three-phase unbalanced power system is of great importance for protection and relay.This paper proposes a new H∞filter based on sparse model to track the sequence components and the frequency of three-phase unbalanced power systems.The inclusion of sparsity improves the error convergence behavior of estimation model and hence short-duration non-stationary PQ events can easily be tracked in the time domain.The proposed model is developed using l1 norm penalty in the cost function of H∞filter,which is quite suitable for estimation across all the three phases of an unbalanced system.This model uses real state space modeling across three phases to estimate amplitude and phase parameters of sequence components.However,frequency estimation uses complex state space modeling and Clarke transformation generates a complex measurement signal from the unbalanced three-phase voltages.The state vector used for frequency estimation consists of two state variables.The proposed sparse model is tested using distorted three-phase signals from IEEE-1159-PQE database and the data generated from experimental laboratory setup.The analysis of absolute and mean square error is presented to validate the performance of the proposed model.展开更多
基金supported in part by the Joint Funds of the National Natural Science Foundation of China(No.U22B6006)the National Natural Science Foundation of China(No.52207126)Natural Science Foundation of Sichuan Province(No.2023NSFSC0296).
文摘In a DC grid with dedicated metallic return(DMR),the coupling effects among the positive pole,negative pole,and DMR conductors must be considered,which makes fault identification particularly difficult.In addition,the identification of high-impedance faults remains a major challenge for DC grid protection.To address these issues,this study proposes an adaptive single-end protection method for DC grid based on the transient mean value of the current limiting reactor(CLR)modal voltage.First,a fault analysis model of the DC grid with DMR is established using the Clarke transformation.The characteristics of CLR modal voltage are then clarified.A fault pole-selection method based on a novel modulus phase plane is next proposed.A threshold scaling factor based on the differential of DC bus voltage is then constructed to enhance the sensitivity and rapidity of the protection,which can adaptively modify the threshold according to the fault severity.Finally,a simulation model of a four-terminal DC grid with DMR is developed in PSCAD/EMTDC.The speed and reliability of the proposed protection method are verified by simulations and experiments.
基金the support of Indian Institute of Information Technology,Bhubaneswar,IndiaVeer Surendra Sai University of Tecnology(Burla),Sambalpur,India,in terms of Laboratory and online Journal facilities to carry out this research work
文摘The estimation of sequence or symmetrical components and frequency in three-phase unbalanced power system is of great importance for protection and relay.This paper proposes a new H∞filter based on sparse model to track the sequence components and the frequency of three-phase unbalanced power systems.The inclusion of sparsity improves the error convergence behavior of estimation model and hence short-duration non-stationary PQ events can easily be tracked in the time domain.The proposed model is developed using l1 norm penalty in the cost function of H∞filter,which is quite suitable for estimation across all the three phases of an unbalanced system.This model uses real state space modeling across three phases to estimate amplitude and phase parameters of sequence components.However,frequency estimation uses complex state space modeling and Clarke transformation generates a complex measurement signal from the unbalanced three-phase voltages.The state vector used for frequency estimation consists of two state variables.The proposed sparse model is tested using distorted three-phase signals from IEEE-1159-PQE database and the data generated from experimental laboratory setup.The analysis of absolute and mean square error is presented to validate the performance of the proposed model.
