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
This paper describes the statistical study of important factors that influences transient over voltages resulting from three-phase reclosing of shunt compensated transmission lines. These factors include the model use...This paper describes the statistical study of important factors that influences transient over voltages resulting from three-phase reclosing of shunt compensated transmission lines. These factors include the model used for transmission line representation and the influence of line transposition. Additionally, the over voltages reduction to proper levels depending on the type of control technique are illustrated and analyzed in statistical terms. The evaluation covers three shunt compensation degrees. The digital simulations were performed using the PSCAD/EMTDC software.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
The problem of reclosing current limiting in voltage source converter based high-voltage direct current(VSCHVDC)systems is becoming more and more serious.A soft reclosing scheme for DC permanent faults is presented in...The problem of reclosing current limiting in voltage source converter based high-voltage direct current(VSCHVDC)systems is becoming more and more serious.A soft reclosing scheme for DC permanent faults is presented in this paper.Because the converter voltages of stations at both terminals of the disconnected faulty line may be different,the choice of which terminal to reclose first will affect the reclosing overcurrent.A method for selecting the terminal to reclose first is investigated to achieve a minimum peak overcurrent during the reclosing process.In order to ensure that the hybrid DC circuit breaker(HDCCB)adapts to the needs of the reclosing process better,the traditional HDCCB is improved by adding a soft reclosing module(SRM).The energy dissipated in the arresters is significantly reduced when using the improved HDCCB.The improved HDCCB will be able to reclose multiple times safely and thus increase the possibility of successful reclosing.Moreover,the recovery time after the HDCCB is successfully reclosed is very short with the improved HDCCB and its control principles.Simulation results show that this proposed scheme is capable of limiting the reclosing overcurrent when the fault still exists.展开更多
This paper proposes a reclosing scheme using synchronism checking for utilization of battery energy storage system(BESS) in a distribution system. The algorithm disconnects the faulty phase and keeps the power supply ...This paper proposes a reclosing scheme using synchronism checking for utilization of battery energy storage system(BESS) in a distribution system. The algorithm disconnects the faulty phase and keeps the power supply from the BESS to the healthy phase. Synchronism checking between the main source side and the load side is applied to minimize the transients at the reclosing instant.The BESS at the faulty phase is reconnected after checking the successful reclosing. The distribution system including BESS and proposed reclosing scheme are modeled by the electromagnetic transients program(EMTP)/ATPDraw.The various simulations by varing the fault clearing time are conducted and the simulation results are discussed.Also, the relation between proposed reclosing scheme and reliability is discussed.展开更多
In this paper, a simple method for placing an optimal number of recloser is presented. The algorithm is solved using genetic algorithm as the optimization method. The majority of outage events experienced by customers...In this paper, a simple method for placing an optimal number of recloser is presented. The algorithm is solved using genetic algorithm as the optimization method. The majority of outage events experienced by customers are due to electrical distribution failures. Increasing network reliability is a necessity in order to reduce interruption events. Distribution network automation can trim down outage events and increase system reliability. Network automation has to be done using optimization approaches. Genetic Algorithm (GA) is a relatively new technique used in power systems optimization problems. Distribution network automation is one of the aspects tackled using GA. However ,the methodologies used to improve the reliability of radial distribution feeders are reviewed. The reliability improvement are demonstrated for typical distribution feeder layouts. determined. The method enjoys the simplicity of conFigure uration, accuracy of the results and reduction of the time consuming. The obtained results also show the applicability of the展开更多
Reliability of power systems is a key aspect in modern power system planning, design, and operation. The ascendance of the smart grid concept has provided high hopes of developing an intelligent network that is capabl...Reliability of power systems is a key aspect in modern power system planning, design, and operation. The ascendance of the smart grid concept has provided high hopes of developing an intelligent network that is capable of being a self-healing grid, offering the ability to overcome the interruption problems that face the utility and cost it tens of millions in repair and loss. In this work, we will examine the effect of the smart grid applications in improving the reliability of the power distribution networks. The test system used in this paper is the IEEE 34 node test feeder, released in 2003 by the Distribution System Analysis Subcommittee of the IEEE Power Engineering Society. The objective is to analyze the feeder for the optimal placement of the automatic switching devices and quantify their proper installation based on the performance of the distribution system. The measures will be the changes in the reliability system indices including SAIDI, SAIFI, and EUE. In addition, the goal is to design and simulate the effect of the installation of the Distributed Generators (DGs) on the utility’s distribution system and measure the potential improvement of its reliability.展开更多
Reliability of power systems is a key aspect in modern power system planning, design, and operation. The ascendance of the smart grid concept has provided high hopes of developing an intelligent network that is capabl...Reliability of power systems is a key aspect in modern power system planning, design, and operation. The ascendance of the smart grid concept has provided high hopes of developing an intelligent network that is capable of being a self-healing grid, offering the ability to overcome the interruption problems that face the utility and cost it tens of millions in repair and loss. In this work, we develop a MATLAB code to examine the effect of the smart grid applications in improving the reliability of the power distribution networks via Monte Carlo Simulation approach. The system used in this paper is the IEEE 34 test feeder. The objective is to measure the installations of the Automatic Reclosers (ARs) as well as the Distributed Generators (DGs) on the reliability indices, SAIDI, SAIFI, CAIDI and EUE, and make comparisons with results from a previous study done by the authors using another approach. The MATLAB code should provide close results to the output of the previous research to verify its effectiveness.展开更多
The research reported in this paper focuses on non-technical power loss reduction for power distribution systems. Such reduction of costs of energy not served (ENS.COST), is intelligently evaluated and optimized using...The research reported in this paper focuses on non-technical power loss reduction for power distribution systems. Such reduction of costs of energy not served (ENS.COST), is intelligently evaluated and optimized using a firefly algorithm, from where savings of 43.3% on energy not served are achieved.展开更多
As the structures of multiple branch lines(MBLs)will be widely applied in the future flexible DC distribution network,there is a urgent need for improving system reliability by tackling the frequent non-permanent pole...As the structures of multiple branch lines(MBLs)will be widely applied in the future flexible DC distribution network,there is a urgent need for improving system reliability by tackling the frequent non-permanent pole-to-pole(P-P)fault on distribution lines.A novel fault restoration strategy based on local information is proposed to solve this issue.The strategy firstly splits a double-ended power supply network into two single-ended power supply networks through the timing difference characteristics of a hybrid direct current circuit breaker(HDCCB)entering the recloser.Then,a method based on the characteristic of the transient energy of fault current is proposed to screen the faulty branch line in each single-ended power supply network.Also,a four-terminal flexible DC distribution network with MBLs is constructed on PSCAD to demonstrate the efficacy of the proposed strategy.Various factors such as noise,fault location,and DC arc equivalent resistance are considered in the simulation model for testing.Test results prove that the proposed strategy for fault restoration is effective,and features high performance and scalability.展开更多
With the development of power electronics technology,the flexible DC grid will play a significant role in promoting the transformation and reformation of the power grid.It is immune to commutation failure and has high...With the development of power electronics technology,the flexible DC grid will play a significant role in promoting the transformation and reformation of the power grid.It is immune to commutation failure and has high flexibility in power control and renewable energy grid integration.However,the protection and fault handling technology for a flexible DC grid is a big challenge because of the limited overcurrent capability of the converters.This paper summarizes the development of the flexible DC grid,and analyzes the fault characteristics in detail.Next,the applicability,advantages and disadvantages of the existing protection principle,fault isolation and recovery schemes are reviewed.Finally,the key problems and development trend of the future flexible DC grid are pointed out and forecasted respectively.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.
文摘This paper describes the statistical study of important factors that influences transient over voltages resulting from three-phase reclosing of shunt compensated transmission lines. These factors include the model used for transmission line representation and the influence of line transposition. Additionally, the over voltages reduction to proper levels depending on the type of control technique are illustrated and analyzed in statistical terms. The evaluation covers three shunt compensation degrees. The digital simulations were performed using the PSCAD/EMTDC software.
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.
基金This work was supported by National Key R&D Program of China(No.2017YFB0902400).
文摘The problem of reclosing current limiting in voltage source converter based high-voltage direct current(VSCHVDC)systems is becoming more and more serious.A soft reclosing scheme for DC permanent faults is presented in this paper.Because the converter voltages of stations at both terminals of the disconnected faulty line may be different,the choice of which terminal to reclose first will affect the reclosing overcurrent.A method for selecting the terminal to reclose first is investigated to achieve a minimum peak overcurrent during the reclosing process.In order to ensure that the hybrid DC circuit breaker(HDCCB)adapts to the needs of the reclosing process better,the traditional HDCCB is improved by adding a soft reclosing module(SRM).The energy dissipated in the arresters is significantly reduced when using the improved HDCCB.The improved HDCCB will be able to reclose multiple times safely and thus increase the possibility of successful reclosing.Moreover,the recovery time after the HDCCB is successfully reclosed is very short with the improved HDCCB and its control principles.Simulation results show that this proposed scheme is capable of limiting the reclosing overcurrent when the fault still exists.
文摘This paper proposes a reclosing scheme using synchronism checking for utilization of battery energy storage system(BESS) in a distribution system. The algorithm disconnects the faulty phase and keeps the power supply from the BESS to the healthy phase. Synchronism checking between the main source side and the load side is applied to minimize the transients at the reclosing instant.The BESS at the faulty phase is reconnected after checking the successful reclosing. The distribution system including BESS and proposed reclosing scheme are modeled by the electromagnetic transients program(EMTP)/ATPDraw.The various simulations by varing the fault clearing time are conducted and the simulation results are discussed.Also, the relation between proposed reclosing scheme and reliability is discussed.
文摘In this paper, a simple method for placing an optimal number of recloser is presented. The algorithm is solved using genetic algorithm as the optimization method. The majority of outage events experienced by customers are due to electrical distribution failures. Increasing network reliability is a necessity in order to reduce interruption events. Distribution network automation can trim down outage events and increase system reliability. Network automation has to be done using optimization approaches. Genetic Algorithm (GA) is a relatively new technique used in power systems optimization problems. Distribution network automation is one of the aspects tackled using GA. However ,the methodologies used to improve the reliability of radial distribution feeders are reviewed. The reliability improvement are demonstrated for typical distribution feeder layouts. determined. The method enjoys the simplicity of conFigure uration, accuracy of the results and reduction of the time consuming. The obtained results also show the applicability of the
文摘Reliability of power systems is a key aspect in modern power system planning, design, and operation. The ascendance of the smart grid concept has provided high hopes of developing an intelligent network that is capable of being a self-healing grid, offering the ability to overcome the interruption problems that face the utility and cost it tens of millions in repair and loss. In this work, we will examine the effect of the smart grid applications in improving the reliability of the power distribution networks. The test system used in this paper is the IEEE 34 node test feeder, released in 2003 by the Distribution System Analysis Subcommittee of the IEEE Power Engineering Society. The objective is to analyze the feeder for the optimal placement of the automatic switching devices and quantify their proper installation based on the performance of the distribution system. The measures will be the changes in the reliability system indices including SAIDI, SAIFI, and EUE. In addition, the goal is to design and simulate the effect of the installation of the Distributed Generators (DGs) on the utility’s distribution system and measure the potential improvement of its reliability.
文摘Reliability of power systems is a key aspect in modern power system planning, design, and operation. The ascendance of the smart grid concept has provided high hopes of developing an intelligent network that is capable of being a self-healing grid, offering the ability to overcome the interruption problems that face the utility and cost it tens of millions in repair and loss. In this work, we develop a MATLAB code to examine the effect of the smart grid applications in improving the reliability of the power distribution networks via Monte Carlo Simulation approach. The system used in this paper is the IEEE 34 test feeder. The objective is to measure the installations of the Automatic Reclosers (ARs) as well as the Distributed Generators (DGs) on the reliability indices, SAIDI, SAIFI, CAIDI and EUE, and make comparisons with results from a previous study done by the authors using another approach. The MATLAB code should provide close results to the output of the previous research to verify its effectiveness.
文摘The research reported in this paper focuses on non-technical power loss reduction for power distribution systems. Such reduction of costs of energy not served (ENS.COST), is intelligently evaluated and optimized using a firefly algorithm, from where savings of 43.3% on energy not served are achieved.
基金supported by the National Natural Science Foundation of China(No.51877174)。
文摘As the structures of multiple branch lines(MBLs)will be widely applied in the future flexible DC distribution network,there is a urgent need for improving system reliability by tackling the frequent non-permanent pole-to-pole(P-P)fault on distribution lines.A novel fault restoration strategy based on local information is proposed to solve this issue.The strategy firstly splits a double-ended power supply network into two single-ended power supply networks through the timing difference characteristics of a hybrid direct current circuit breaker(HDCCB)entering the recloser.Then,a method based on the characteristic of the transient energy of fault current is proposed to screen the faulty branch line in each single-ended power supply network.Also,a four-terminal flexible DC distribution network with MBLs is constructed on PSCAD to demonstrate the efficacy of the proposed strategy.Various factors such as noise,fault location,and DC arc equivalent resistance are considered in the simulation model for testing.Test results prove that the proposed strategy for fault restoration is effective,and features high performance and scalability.
基金funded by the Fundamental Research Funds for the Central Universities(No.2019YJS179).
文摘With the development of power electronics technology,the flexible DC grid will play a significant role in promoting the transformation and reformation of the power grid.It is immune to commutation failure and has high flexibility in power control and renewable energy grid integration.However,the protection and fault handling technology for a flexible DC grid is a big challenge because of the limited overcurrent capability of the converters.This paper summarizes the development of the flexible DC grid,and analyzes the fault characteristics in detail.Next,the applicability,advantages and disadvantages of the existing protection principle,fault isolation and recovery schemes are reviewed.Finally,the key problems and development trend of the future flexible DC grid are pointed out and forecasted respectively.
