The petal-shaped distribution network has high power supply reliability.However,the closed-loop operation mode and the access of inverter-interfaced distributed generators(IIDGs)bring great challenges to the protectio...The petal-shaped distribution network has high power supply reliability.However,the closed-loop operation mode and the access of inverter-interfaced distributed generators(IIDGs)bring great challenges to the protection schemes.The current amplitude differential protection is an effective means to solve this problem,but the existing criterions rarely consider both sensitivity to high-resistance faults and low requirements for data synchronization.Therefore,the general variation laws of the amplitude difference between the current steady-state components at both terminals and the phase differences between current fault components at both terminals are revealed.For external faults,the steady-state-component current amplitude difference is around zero and the fault-component current phase difference is around 180◦.For internal faults,either the amplitude difference is large or the phase difference is small.Accordingly,a current differential protection scheme based on the pre-fault and postfault steady-state current is proposed.The amplitude and phase of current at both terminals of the protected line are required in the proposed scheme,which has low requirements for data synchronization.The simulation results show that the proposed protection scheme is not affected by the fault type,position,resistance and capacity of the IIDGs.It can also be applied to radial distribution networks with IIDGs.展开更多
The limitation of fault currents from converter based distributed generators(CBDGs)in hybrid AC/DC islanded microgrids poses a significant challenge for microgrid protection.This paper presents a novel interharmonic c...The limitation of fault currents from converter based distributed generators(CBDGs)in hybrid AC/DC islanded microgrids poses a significant challenge for microgrid protection.This paper presents a novel interharmonic current differential protection scheme for the AC side of hybrid AC/DC islanded microgrids supplied by CBDGs.During faults,the proposed scheme exploits the varying interharmonic components of the currents at both terminals of the faulted line,arise due to variations in the droop-based no-load frequency limits of the interlinking converters(ICs)and the CBDGs.By leveraging these variations,the scheme effectively detects and isolates internal faults within the AC sub-grid,enhancing system reliability.The effectiveness of the suggested scheme is assessed using an enhanced IEEE33-bus hybrid AC/DC microgrid modelled in PSCAD/EMTDC,demonstrating its ability to reliably detect and isolate faults under various operating conditions.Additionally,the scheme is further evaluated using a real-time hardware-in-the-loop experimental setup implemented on an RTDS platform,validating its practical applicability.The simulation and experimental results validate that the presented protection scheme accurately discriminates between normal and faulty conditions across various fault locations,types,and resistance values.This discrimination is achieved without requiring high-bandwidth communication,overcoming a key limitation of existing protection schemes and improving feasibility in real-world deployments.展开更多
The emergence of distributed generators has changed the operational mode and fault characteristics of the distribu-tion network,in a way which can severely influence protection.This paper proposes a d-axis-based curre...The emergence of distributed generators has changed the operational mode and fault characteristics of the distribu-tion network,in a way which can severely influence protection.This paper proposes a d-axis-based current differential protection scheme.The d-axis current characteristics of inverter-interfaced distributed generators and synchronous generators are analyzed.The differential protection criterion using sampling values of the d-axis current component is then constructed.Compared to conventional phase-based current differential protection,the proposed protection reduces the number of required communication channels,and is suitable for distribution networks with inverter-interfaced distributed generators with complex fault characteristics.Finally,a 10 kV active distribution network model is built in the PSCAD platform and protection prototypes are developed in RTDS.Superior sensitivity and fast speed are verified by simulation and RTDS-based tests.展开更多
This paper proposes a novel scheme for detecting and classifying faults in stator windings of a synchronous generator(SG).The proposed scheme employs a new method for fault detection and classification based on Suppor...This paper proposes a novel scheme for detecting and classifying faults in stator windings of a synchronous generator(SG).The proposed scheme employs a new method for fault detection and classification based on Support Vector Machine(SVM).Two SVM classifiers are proposed.SVM1 is used to identify the fault occurrence in the system and SVM2 is used to determine whether the fault,if any,is internal or external.In this method,the detection and classification of faults are not affected by the fault type and location,pre-fault power,fault resistance or fault inception time.The proposed method increases the ability of detecting the ground faults near the neutral terminal of the stator windings for generators with high impedance grounding neutral point.The proposed scheme is compared with ANN-based method and gives faster response and better reliability for fault classification.展开更多
To improve the resource utilization ratio and shorten the recovery time of the shared path protection with differentiated reliability （SPP-DiR） algorithm, an algorithm called dynamic shared segment protection with d...To improve the resource utilization ratio and shorten the recovery time of the shared path protection with differentiated reliability （SPP-DiR） algorithm, an algorithm called dynamic shared segment protection with differentiated reliability （DSSP-DiR） is proposed for survivable GMPLS networks. In the proposed algorithm, a primary path is dynamically divided into several segments according to the differentiated reliability requirements of the customers. In the SPP-DiR algorithm, the whole primary path should be protected, while in the DSSP- DiR algorithm, only partial segments on the primary path need to be protected, which can reduce more backup bandwidths than that in the SPP-DiR algorithm. Simulation results show that the DSSP-DiR algorithm achieves higher resource utilization ratio, lower protection failure probability, and shorter recovery time than the SPP-DiR algorithm.展开更多
基金supported in part by Science and Technology Project of State Grid Corporation of China:Research on Key Protection Technologies for New-type Urban Distribution Network with Controllable Sources and Loads.
文摘The petal-shaped distribution network has high power supply reliability.However,the closed-loop operation mode and the access of inverter-interfaced distributed generators(IIDGs)bring great challenges to the protection schemes.The current amplitude differential protection is an effective means to solve this problem,but the existing criterions rarely consider both sensitivity to high-resistance faults and low requirements for data synchronization.Therefore,the general variation laws of the amplitude difference between the current steady-state components at both terminals and the phase differences between current fault components at both terminals are revealed.For external faults,the steady-state-component current amplitude difference is around zero and the fault-component current phase difference is around 180◦.For internal faults,either the amplitude difference is large or the phase difference is small.Accordingly,a current differential protection scheme based on the pre-fault and postfault steady-state current is proposed.The amplitude and phase of current at both terminals of the protected line are required in the proposed scheme,which has low requirements for data synchronization.The simulation results show that the proposed protection scheme is not affected by the fault type,position,resistance and capacity of the IIDGs.It can also be applied to radial distribution networks with IIDGs.
基金supported by the ASPIRE Virtual Research Institute Program,Advanced Technology Research Council(No.VRI20-07),UAE.
文摘The limitation of fault currents from converter based distributed generators(CBDGs)in hybrid AC/DC islanded microgrids poses a significant challenge for microgrid protection.This paper presents a novel interharmonic current differential protection scheme for the AC side of hybrid AC/DC islanded microgrids supplied by CBDGs.During faults,the proposed scheme exploits the varying interharmonic components of the currents at both terminals of the faulted line,arise due to variations in the droop-based no-load frequency limits of the interlinking converters(ICs)and the CBDGs.By leveraging these variations,the scheme effectively detects and isolates internal faults within the AC sub-grid,enhancing system reliability.The effectiveness of the suggested scheme is assessed using an enhanced IEEE33-bus hybrid AC/DC microgrid modelled in PSCAD/EMTDC,demonstrating its ability to reliably detect and isolate faults under various operating conditions.Additionally,the scheme is further evaluated using a real-time hardware-in-the-loop experimental setup implemented on an RTDS platform,validating its practical applicability.The simulation and experimental results validate that the presented protection scheme accurately discriminates between normal and faulty conditions across various fault locations,types,and resistance values.This discrimination is achieved without requiring high-bandwidth communication,overcoming a key limitation of existing protection schemes and improving feasibility in real-world deployments.
基金supported by China Southern Power Grid Technology Project.
文摘The emergence of distributed generators has changed the operational mode and fault characteristics of the distribu-tion network,in a way which can severely influence protection.This paper proposes a d-axis-based current differential protection scheme.The d-axis current characteristics of inverter-interfaced distributed generators and synchronous generators are analyzed.The differential protection criterion using sampling values of the d-axis current component is then constructed.Compared to conventional phase-based current differential protection,the proposed protection reduces the number of required communication channels,and is suitable for distribution networks with inverter-interfaced distributed generators with complex fault characteristics.Finally,a 10 kV active distribution network model is built in the PSCAD platform and protection prototypes are developed in RTDS.Superior sensitivity and fast speed are verified by simulation and RTDS-based tests.
文摘This paper proposes a novel scheme for detecting and classifying faults in stator windings of a synchronous generator(SG).The proposed scheme employs a new method for fault detection and classification based on Support Vector Machine(SVM).Two SVM classifiers are proposed.SVM1 is used to identify the fault occurrence in the system and SVM2 is used to determine whether the fault,if any,is internal or external.In this method,the detection and classification of faults are not affected by the fault type and location,pre-fault power,fault resistance or fault inception time.The proposed method increases the ability of detecting the ground faults near the neutral terminal of the stator windings for generators with high impedance grounding neutral point.The proposed scheme is compared with ANN-based method and gives faster response and better reliability for fault classification.
基金supported by the National Natural Science Foundation of China (60673142)Applied Basic Research Project of Sichuan Province (2006J13-067)
文摘To improve the resource utilization ratio and shorten the recovery time of the shared path protection with differentiated reliability （SPP-DiR） algorithm, an algorithm called dynamic shared segment protection with differentiated reliability （DSSP-DiR） is proposed for survivable GMPLS networks. In the proposed algorithm, a primary path is dynamically divided into several segments according to the differentiated reliability requirements of the customers. In the SPP-DiR algorithm, the whole primary path should be protected, while in the DSSP- DiR algorithm, only partial segments on the primary path need to be protected, which can reduce more backup bandwidths than that in the SPP-DiR algorithm. Simulation results show that the DSSP-DiR algorithm achieves higher resource utilization ratio, lower protection failure probability, and shorter recovery time than the SPP-DiR algorithm.
