The liquid metal current limiter(LMCL)is regarded as a viable solution for reducing the fault current in a power grid.But demonstrating the liquid metal arc plasma self-pinching process of the resistive wall,and reduc...The liquid metal current limiter(LMCL)is regarded as a viable solution for reducing the fault current in a power grid.But demonstrating the liquid metal arc plasma self-pinching process of the resistive wall,and reducing the erosion of the LMCL are challenging,not only theoretically,but also practically.In this work,a novel LMCL is designed with a resistive wall that can be connected to the current-limiting circuit inside the cavity.Specifically,a novel fault current limiter(FCL)topology is put forward where the novel LMCL is combined with a fast switch and current-limiting reactor.Further,the liquid metal self-pinch effect is modeled mathematically in three dimensions,and the gas-liquid two-phase dynamic diagrams under different short-circuit currents are obtained by simulation.The simulation results indicate that with the increase of current,the time for the liquid metal-free surface to begin depressing is reduced,and the position of the depression also changes.Different kinds of bubbles formed by the depressions gradually extend,squeeze,and break.With the increase of current,the liquid metal takes less time to break,but breaks still occur at the edge of the channel,forming arc plasma.Finally,relevant experiments are conducted for the novel FCL topology.The arcing process and current transfer process are analyzed in particular.Comparisons of the peak arc voltage,arcing time,current limiting efficiency,and electrode erosion are presented.The results demonstrate that the arc voltage of the novel FCL topology is reduced by more than 4.5times and the arcing time is reduced by more than 12%.The erosions of the liquid metal and electrodes are reduced.Moreover,the current limiting efficiency of the novel FCL topology is improved by 1%–5%.This work lays a foundation for the topology and optimal design of the LMCL.展开更多
The GaInSn liquid metal current limiter based on the fluid pinch effect has broad application prospects due to its particular properties. However, the limited rated current and abil- ity of power dissipation are the c...The GaInSn liquid metal current limiter based on the fluid pinch effect has broad application prospects due to its particular properties. However, the limited rated current and abil- ity of power dissipation are the critical problems for its wide application. Firstly, the temperature distribution of the liquid metal current limiter （LMCL） was obtained by experiments with a rated current of 1 kA and the arc ignition phenomenon was observed with 1.5 kA, which indicates that the rated current is mainly limited by the arc rather than the high temperature compared to the traditional switchgears. Furthermore, an improved method is proposed by adding the paralleled pure resistance, impedance or another LMCL element to protect the setup from the fault energy concentration in the setup. The problem of a slower arc voltage increasing rate can be solved by adding a paralleled impedance with suitable parameters. Finally, the current limiting properties based on the improved method were investigated and the alternating oscillating current was found between two paralleled LMCL elements owing to their deviation of arc ignition in reality.展开更多
This article gives an overview of the main passive solutions and active techniques, based on AC switches to limit inrush currents in medium power AC-DC converters （up to 3.7 kW） for electric vehicle charging systems...This article gives an overview of the main passive solutions and active techniques, based on AC switches to limit inrush currents in medium power AC-DC converters （up to 3.7 kW） for electric vehicle charging systems. In particular, a strategy, based on SCR （silicon controlled rectifier） phase, shift control in a mixed rectifier bridge with diodes and thyristors, is proposed. The challenge is to help designers optimize the triggering delay of SCRs to both limit the peak value of inrush current spikes and optimize the charge duration of the DC-link capacitor. A mathematical model （Mathcad engineering tool） has been defined to point out, the interest of a variable triggering delay to control SCRs to meet the expectations described previously. Experimental measurements using an industrial evaluation board of the AC-DC converter demonstrate the robustness of the method.展开更多
The effectiveness of a combination of fault current limiter and thyristor controlled braking resistor on power system stability enhancement and damping turbine shaft torsional oscillations has been studied. If both de...The effectiveness of a combination of fault current limiter and thyristor controlled braking resistor on power system stability enhancement and damping turbine shaft torsional oscillations has been studied. If both devices operate at the same bus, the stabilization control scheme can be carried out continuously and with flexibility. As a result, the fault currents are limited, and the generator disturbances and the turbine shaft torsional oscillations are converged quickly. In this paper, the effectiveness of the combination of both devices has been demonstrated by considering 3LG （three-lines-to-ground） fault in a two-machine infinite bus system. Also, temperature rise effect of both devices with various resistance values and weights has been demonstrated. Simulation results indicate a significant power system stability enhancement and damping turbine shaft torsional oscillations as well as with allowable temperature rise.展开更多
The fault current limiter(FCL)is an effective measure for improving system stability and suppressing short-circuit fault current.Because of space and economic costs,the optimum placement of FCLs is vital in industrial...The fault current limiter(FCL)is an effective measure for improving system stability and suppressing short-circuit fault current.Because of space and economic costs,the optimum placement of FCLs is vital in industrial applications.In this study,two objectives with the same dimensional measurement unit,namely,the total capital investment cost of FCLs and circuit breaker loss related to short-circuit currents,are considered.The circuit breaker loss model is developed based on the attenuation rule of the circuit breaker service life.The circuit breaker loss is used to quantify the current-limiting effect to avoid the problem of weight selection in a multi-objective problem.The IEEE 10-generator 39-bus system in New England is used to evaluate the performance of the proposed genetic algorithm(GA)method.Comparative and sensitivity analyses are performed.The results of the optimized plan are validated through simulations,indicating the significant potential of the GA for such optimization.展开更多
A novel magnetic-controlled switcher type fault current limiter （FCL） for high voltage electric network is presented. The current limiting principle of the FCL and the bias current influence on the characteristic of...A novel magnetic-controlled switcher type fault current limiter （FCL） for high voltage electric network is presented. The current limiting principle of the FCL and the bias current influence on the characteristic of the FCL axe discussed. The experiments on the 220 V/50 A test model show that the FCL can limit the fault current swiftly and effectively. Under the normal state, the bias current adjustment can change the FCL voltage loss; under the fault state, the steady fault current can be easily adjusted to the preset level by bias current regulating. The experimental result is in accordance with the principle analysis and the FCL has the advantages of flexible control strategy and simple and reliable structure.展开更多
Due to its significant attributes,the liquid metal current limiter(LMCL)is considered a new strategy for limiting short-circuit current in the power grid.A resistive wall liquid metal current limiter(RWLMCL)is designe...Due to its significant attributes,the liquid metal current limiter(LMCL)is considered a new strategy for limiting short-circuit current in the power grid.A resistive wall liquid metal current limiter(RWLMCL)is designed to advance the starting current-limiting time.Experiments are performed to investigate the dynamic behaviors of liquid metal,and the influence of different currents on the liquid metal self-shrinkage effect is compared and analyzed.Furthermore,the liquid metal self-shrinkage effect is mathematically modeled,and the reason for the formation of arc plasma is obtained by simulation.The laws of arc plasma formation and the current transfer in the cavity are revealed,and the motion mechanisms are explained by physical principles.The simulations are in accordance with the test data.It is demonstrated that the sudden change of the current density at both ends of the wall causes the liquid metal to shrink and depress under the electromagnetic force,and the current starts to transfer from the liquid metal path to the wall resistance path.The RWLMCL can effectively advance the starting current-limiting time.展开更多
A novel magnetic-controlled switcher type fault current limiter (FCL) based on the topology of the saturated iron core high temperature superconducting FCL is proposed. The magnetic field distribution of the FCL iron ...A novel magnetic-controlled switcher type fault current limiter (FCL) based on the topology of the saturated iron core high temperature superconducting FCL is proposed. The magnetic field distribution of the FCL iron core is analyzed by FEA software ANSYS. The current limiting characteristic is investigated by both 3-D field-circuit coupled simulation and Matlab. The experiments on the 220 V/50 A test model show that the FCL can limit the fault current swiftly and effectively,and the FCL has the advantages of simple and reliable structure, flexible control strategy. The simulation and experimental results prove that the theoretical expectation and current limiting performance is satisfactory for practical use.展开更多
A deregulated power market is making short-circuit currents likely to exceed the thermal or mechanical permissible limits of switchgear. Consequently fault current limiters （FCL） become more necessary in power syste...A deregulated power market is making short-circuit currents likely to exceed the thermal or mechanical permissible limits of switchgear. Consequently fault current limiters （FCL） become more necessary in power systems. The use of FCLs has an impact on the protection schemes and functions in power systems. Thus, before FCLs can be applied in the network, the impacts on existing protection system must be understood. Depending on the current limiting technique used, today＇s protection concepts may have to be adapted or revised to ensure proper network protection selectivity. A relationship between fault current limiters and protection schemes should be established by taking into account both protection and network specific issues, such as the impact of different FCL technologies, existing and new protection concepts, selectivity and innovative network. This paper is presenting a frame work for accomplishing this task.展开更多
FCL （fault current limiter） is used to solve relays miscoordination problem arises from DG （distributed generation） installation. In most published researches, different optimization methods are developed to obtai...FCL （fault current limiter） is used to solve relays miscoordination problem arises from DG （distributed generation） installation. In most published researches, different optimization methods are developed to obtain optimal relay settings to achieve coordination in case of not installing DG, then depending on the achieved optimal obtained relay settings, FCL impedance is deduced to ensure relays coordination restoration in case of installing DG. Based on original optimal relay settings, obtained FCL impedance is not the minimum one required to achieve relay coordination. The contribution of this paper is the generation of multi sets of original relay settings that increase the possibility of finding FCL impedance of minimum value which is lower than the calculated value based on original optimal relay settings. The proposed method achieves better economic target by reducing FCL impedance. The proposed approach is implemented and tested on IEEE-39 bus test system.展开更多
With the global energy transition,the proportion of renewable energy power generation in total electricity production has exceeded 30%and continues to rise,even the ratio is higher in China.Multi-terminal high-voltage...With the global energy transition,the proportion of renewable energy power generation in total electricity production has exceeded 30%and continues to rise,even the ratio is higher in China.Multi-terminal high-voltage direct-current(MT-HVDC)transmission systems have advantages of integration of distributed renewable energy sources,dynamic grid interconnections,and reliable islanding operation capabilities,being critical for next-generation power grid.Current limiting technologies are pivotal in maintaining grid safety and stability,especially for HVDC systems without natural zero-crossing point in fault currents.In this perspective,a superconducting fault current limiter(SFCL)with combination of resistance and inductance is necessary and more effective solution in protecting MT-HVDC transmission systems.展开更多
Fault current limiting is a critical technology to en sure the safe operation of modular multilevel converter based multi-terminal direct current(MMC-MTDC)grids.This paper proposes a fault severity classification base...Fault current limiting is a critical technology to en sure the safe operation of modular multilevel converter based multi-terminal direct current(MMC-MTDC)grids.This paper proposes a fault severity classification based coordination con trol strategy of fault current limiter(FCL)and MMC for adap tive fault current limiting.The proposed strategy reduces the in vestment in FCL,and keeps the bus voltages of non-faulty lines at reasonable values.Firstly,a rapid fault circuit parameter esti mation(FCPE)method using initial fault current information is proposed.With this method,the fault distance and fault transi tion resistance can be quickly estimated,which are used for a quantitative indication of the fault severity.Subsequently,the coordination control strategy of FCL and MMC is proposed,in which the FCL action is prioritized,while the control of MMC is complementary for current limiting.Based on the proposed strategy,fault severity phase planes(FSPPs)are constructed to assess fault severity and calculate the activation time of FCL and voltage regulation factor of MMC.Therefore,the FCL acti vation and MMC control are matched to the fault severity.The effectiveness and advantages of the proposed strategy are vali dated by the simulations in PSCAD/EMTDC.展开更多
Distributed generation units(DGUs)bring some problems to the existing protection system,such as those associated with protection blinding and sympathetic tripping.It is known that fault current limiters(FCLs)help mini...Distributed generation units(DGUs)bring some problems to the existing protection system,such as those associated with protection blinding and sympathetic tripping.It is known that fault current limiters(FCLs)help minimize the negative impact of DGUs on the protection system.In this paper,a control-based FCL is proposed,i.e.,the FCL is integrated into the DGU control law.To this end,a predictive control strategy with fault current limitation is suggested.In this way,a DGU is controlled,not only for power exchange with the power grid but also to limit its fault current contribution.The proposal is posed as a constrained optimization problem allowing taking into account the current limit explicitly in the design process as a closed-loop solution.A linear approximation is proposed to cope with the inherent nonlinear constraints.The proposal does not require incorporating extra equipment or mechanisms in the control loop,making the design process simple.To evaluate the proposed control-based FCL,both protection blinding and sympathetic tripping scenarios are considered.The control confines the DGU currents within the constraints quickly,avoiding large transient peaks.Therefore,the impact on the protection system is reduced without the necessity that the DGU goes out of service.展开更多
To select the type and value of the impedance of fault current limiters（FCLs） for power network designers, we introduce a new method to calculate the optimum value of FCL impedance depending on its position in the n...To select the type and value of the impedance of fault current limiters（FCLs） for power network designers, we introduce a new method to calculate the optimum value of FCL impedance depending on its position in the network. Due to the complexity of its impedance, the costs of both real and imaginary parts of FCL impedance are considered. The optimization of FCL impedance is based on a goal function that maximizes the reduction of the fault current while minimizing the costs. While the position of FCL in the network has an effect on the calculation of the optimum impedance value, the method for selecting FCL location is not the focus of this study. The proposed method for optimizing FCL impedance can be used for every network that has symmetrical and/or asymmetrical faults. We use a 14-bus IEEE network as an example to explain the process. The optimum FCL impedance used in this network is calculated by considering the vast range of costs for both real and imaginary parts of FCL impedance.展开更多
A 500 kV high-voltage AC fault current limiter(FCL)based on a high coupled split reactor(HCSR)is pro-posed by the National key R&D project team.Low impedance under normal conditions and high impedance under short-...A 500 kV high-voltage AC fault current limiter(FCL)based on a high coupled split reactor(HCSR)is pro-posed by the National key R&D project team.Low impedance under normal conditions and high impedance under short-circuit conditions are accomplished by the cooperation of HCSR and high-speed switches.High-speed switches play an important role in current limiting processes,thus interruption characteristics of the high-speed switch in the 500 kV FCL are studied in this paper.The simulation model of the FCL and the external equivalent power grid are established.The short-circuit current and recovery voltage characteristics of the high-speed switch in FCL are simulated.The results show that maximum DC component of the short-circuit current of the high-speed switch reaches 91%,the maximum peak value is 118 kA,and the longest arcing time is 14.8 ms.There is a discontinuity in the curve of the short-circuit current peak and arcing time as a function of the short-circuit occurrence time;the peak recovery voltage of a single break of the high-speed switch has a maximum value of 87.5 kV under a three-phase ungrounded short-circuit condition,and the rate of rise of recovery voltage is o.22 kV/s.The recovery voltage peak shows a period change with the short-circuit occurrence time,and the period is 10 ms.The effects of the shunt capacitor value and short-circuit ground resistance on the recovery voltage of high-speed switching are also studied.The research can be used for reference by R&D personnel and testersof500kVFCLs.Index Terms-Fault current limiter(FCL),high coupled split reactor(HCSR),high-speed switch,interruption characteristics,short circuit current.展开更多
This paper presents a new type of fault current limiter (FCL) based on fast closing switch, which is composed of a capacitor bank and a reactor in series. The main control component is a fast closing switch connecte...This paper presents a new type of fault current limiter (FCL) based on fast closing switch, which is composed of a capacitor bank and a reactor in series. The main control component is a fast closing switch connected in parallel with the capacitors, which is driven by the electromagnetic repulsion force. It can response the order within 1 ms. When fault occurs, the switch closes and the capacitors are bypassed, and the fault current is limited by the reactor. Simulation analysis and experiment show that the electromagnetic repulsion force actuator can meet the demand of fast closing switch, it is feasible to develop the FCL with low cost and high reliability.展开更多
Several substations in operation were commissioned decades ago.These substations are overstressed,then their protection equipment cannot provide an effective safety condition to the system.In the worst cases,short‐ci...Several substations in operation were commissioned decades ago.These substations are overstressed,then their protection equipment cannot provide an effective safety condition to the system.In the worst cases,short‐circuits can cause permanent damage to the system if the overcurrent is higher than the capacity of the installed equipment.There are some possible solutions for those cases:replace all the equipment in the overstressed substation,build a new one in parallel or install a fault current limiter(FCL)device.From an economic point of view,introducing FCLs in the power system is the best way to solve the described problem.The commercial solutions available are the pyrotechnic FCL,air coil reactor,neutral earthing resistor,and high impedance transformer.However,these devices are limited and present several drawbacks.Since the’70s,there has been a search for reliable FCL devices that do not interfere in the regular operation of substations and could limit the fault currents to the protection system rated level.There were so many FCL technologies proposed in the last decades.These proposed new devices may use superconducting technologies,power electronics,or both.This paper reviews proven FCL technologies,focusing on full‐scale devices demonstrated in field and lab tests.The goal is to introduce the main FCL technologies in development and discuss didactically their operation principle,the built prototypes,the commercial units,whether they exist,and the main drawbacks for each technology presented.A final analysis of the level of maturity for each FCL technology is discussed using the TRL(Technology readiness level)scale in order to find technologies with more potential for mass production.The three technologies closer to the full commercial application are:the Resistive Superconducting FCL,the Saturated Iron Core FCL,and the Series Reactor FCL.展开更多
The design progress of superconducting fault current limiter(SFCL)for transmission voltage is presented,with a focus on the results of recent key experiments that have led to a state‐of‐the‐art high‐voltage high‐...The design progress of superconducting fault current limiter(SFCL)for transmission voltage is presented,with a focus on the results of recent key experiments that have led to a state‐of‐the‐art high‐voltage high‐capacity super‐conducting current limiting techniques:the resistive alternating current(AC)SFCL,saturated iron cores AC SFCL,and resistive direct current(DC)SFCL.The main driving factors for designing SFCL in these projects are the preparation of high‐performance superconducting materials,the development of large‐scale superconducting current limiting winding,system testing,and operation technology.Based on the authors’experience with both AC and DC SFCLs,this paper focuses on the main design aspects of resistive SFCL at transmission voltage.The relationship between the hot spot caused by the inhomogeneity of long superconducting tape and the overall parameter selection is presented.In addition,the thermal calculation based on the current limiting resistance and a real‐time current curve is also proposed for the parameter design of the current limiting winding.展开更多
基金supported by National Natural Science Foundation of China(Nos.51777025,52177131)the Interdisciplinary Program of the Wuhan National High Magnetic Field Center(No.WHMFC202130)Huazhong University of Science and Technology。
文摘The liquid metal current limiter(LMCL)is regarded as a viable solution for reducing the fault current in a power grid.But demonstrating the liquid metal arc plasma self-pinching process of the resistive wall,and reducing the erosion of the LMCL are challenging,not only theoretically,but also practically.In this work,a novel LMCL is designed with a resistive wall that can be connected to the current-limiting circuit inside the cavity.Specifically,a novel fault current limiter(FCL)topology is put forward where the novel LMCL is combined with a fast switch and current-limiting reactor.Further,the liquid metal self-pinch effect is modeled mathematically in three dimensions,and the gas-liquid two-phase dynamic diagrams under different short-circuit currents are obtained by simulation.The simulation results indicate that with the increase of current,the time for the liquid metal-free surface to begin depressing is reduced,and the position of the depression also changes.Different kinds of bubbles formed by the depressions gradually extend,squeeze,and break.With the increase of current,the liquid metal takes less time to break,but breaks still occur at the edge of the channel,forming arc plasma.Finally,relevant experiments are conducted for the novel FCL topology.The arcing process and current transfer process are analyzed in particular.Comparisons of the peak arc voltage,arcing time,current limiting efficiency,and electrode erosion are presented.The results demonstrate that the arc voltage of the novel FCL topology is reduced by more than 4.5times and the arcing time is reduced by more than 12%.The erosions of the liquid metal and electrodes are reduced.Moreover,the current limiting efficiency of the novel FCL topology is improved by 1%–5%.This work lays a foundation for the topology and optimal design of the LMCL.
基金supported by the Technology Project of State Grid(No.SGSNKYOOKJJS1501564)the National Key Basic Research Program of China(973 Program)(No.2015CB251005)
文摘The GaInSn liquid metal current limiter based on the fluid pinch effect has broad application prospects due to its particular properties. However, the limited rated current and abil- ity of power dissipation are the critical problems for its wide application. Firstly, the temperature distribution of the liquid metal current limiter （LMCL） was obtained by experiments with a rated current of 1 kA and the arc ignition phenomenon was observed with 1.5 kA, which indicates that the rated current is mainly limited by the arc rather than the high temperature compared to the traditional switchgears. Furthermore, an improved method is proposed by adding the paralleled pure resistance, impedance or another LMCL element to protect the setup from the fault energy concentration in the setup. The problem of a slower arc voltage increasing rate can be solved by adding a paralleled impedance with suitable parameters. Finally, the current limiting properties based on the improved method were investigated and the alternating oscillating current was found between two paralleled LMCL elements owing to their deviation of arc ignition in reality.
文摘This article gives an overview of the main passive solutions and active techniques, based on AC switches to limit inrush currents in medium power AC-DC converters （up to 3.7 kW） for electric vehicle charging systems. In particular, a strategy, based on SCR （silicon controlled rectifier） phase, shift control in a mixed rectifier bridge with diodes and thyristors, is proposed. The challenge is to help designers optimize the triggering delay of SCRs to both limit the peak value of inrush current spikes and optimize the charge duration of the DC-link capacitor. A mathematical model （Mathcad engineering tool） has been defined to point out, the interest of a variable triggering delay to control SCRs to meet the expectations described previously. Experimental measurements using an industrial evaluation board of the AC-DC converter demonstrate the robustness of the method.
文摘The effectiveness of a combination of fault current limiter and thyristor controlled braking resistor on power system stability enhancement and damping turbine shaft torsional oscillations has been studied. If both devices operate at the same bus, the stabilization control scheme can be carried out continuously and with flexibility. As a result, the fault currents are limited, and the generator disturbances and the turbine shaft torsional oscillations are converged quickly. In this paper, the effectiveness of the combination of both devices has been demonstrated by considering 3LG （three-lines-to-ground） fault in a two-machine infinite bus system. Also, temperature rise effect of both devices with various resistance values and weights has been demonstrated. Simulation results indicate a significant power system stability enhancement and damping turbine shaft torsional oscillations as well as with allowable temperature rise.
基金supported by State Grid Science and Technology Projects(SGTYHT/17-JS-199)National Natural Science Foundation of China(51577163).
文摘The fault current limiter(FCL)is an effective measure for improving system stability and suppressing short-circuit fault current.Because of space and economic costs,the optimum placement of FCLs is vital in industrial applications.In this study,two objectives with the same dimensional measurement unit,namely,the total capital investment cost of FCLs and circuit breaker loss related to short-circuit currents,are considered.The circuit breaker loss model is developed based on the attenuation rule of the circuit breaker service life.The circuit breaker loss is used to quantify the current-limiting effect to avoid the problem of weight selection in a multi-objective problem.The IEEE 10-generator 39-bus system in New England is used to evaluate the performance of the proposed genetic algorithm(GA)method.Comparative and sensitivity analyses are performed.The results of the optimized plan are validated through simulations,indicating the significant potential of the GA for such optimization.
基金the National Basic Research Program(973) of China (No. 2005CB221505)the Research Fund for Doctoral Program of High Education of China(No. 20050248058)
文摘A novel magnetic-controlled switcher type fault current limiter （FCL） for high voltage electric network is presented. The current limiting principle of the FCL and the bias current influence on the characteristic of the FCL axe discussed. The experiments on the 220 V/50 A test model show that the FCL can limit the fault current swiftly and effectively. Under the normal state, the bias current adjustment can change the FCL voltage loss; under the fault state, the steady fault current can be easily adjusted to the preset level by bias current regulating. The experimental result is in accordance with the principle analysis and the FCL has the advantages of flexible control strategy and simple and reliable structure.
基金supported by National Natural Science Foundation of China(No.52177131)the Interdisciplinary Program of Wuhan National High Magnetic Field Center(No.WHMFC202130)Huazhong University of Science and Technology。
文摘Due to its significant attributes,the liquid metal current limiter(LMCL)is considered a new strategy for limiting short-circuit current in the power grid.A resistive wall liquid metal current limiter(RWLMCL)is designed to advance the starting current-limiting time.Experiments are performed to investigate the dynamic behaviors of liquid metal,and the influence of different currents on the liquid metal self-shrinkage effect is compared and analyzed.Furthermore,the liquid metal self-shrinkage effect is mathematically modeled,and the reason for the formation of arc plasma is obtained by simulation.The laws of arc plasma formation and the current transfer in the cavity are revealed,and the motion mechanisms are explained by physical principles.The simulations are in accordance with the test data.It is demonstrated that the sudden change of the current density at both ends of the wall causes the liquid metal to shrink and depress under the electromagnetic force,and the current starts to transfer from the liquid metal path to the wall resistance path.The RWLMCL can effectively advance the starting current-limiting time.
基金Major State Basic Research Development Program of China ( No.2005CB221505)Research Foundation for the Doctoral Programof Higher Education of China(No.20050248058)
文摘A novel magnetic-controlled switcher type fault current limiter (FCL) based on the topology of the saturated iron core high temperature superconducting FCL is proposed. The magnetic field distribution of the FCL iron core is analyzed by FEA software ANSYS. The current limiting characteristic is investigated by both 3-D field-circuit coupled simulation and Matlab. The experiments on the 220 V/50 A test model show that the FCL can limit the fault current swiftly and effectively,and the FCL has the advantages of simple and reliable structure, flexible control strategy. The simulation and experimental results prove that the theoretical expectation and current limiting performance is satisfactory for practical use.
文摘A deregulated power market is making short-circuit currents likely to exceed the thermal or mechanical permissible limits of switchgear. Consequently fault current limiters （FCL） become more necessary in power systems. The use of FCLs has an impact on the protection schemes and functions in power systems. Thus, before FCLs can be applied in the network, the impacts on existing protection system must be understood. Depending on the current limiting technique used, today＇s protection concepts may have to be adapted or revised to ensure proper network protection selectivity. A relationship between fault current limiters and protection schemes should be established by taking into account both protection and network specific issues, such as the impact of different FCL technologies, existing and new protection concepts, selectivity and innovative network. This paper is presenting a frame work for accomplishing this task.
文摘FCL （fault current limiter） is used to solve relays miscoordination problem arises from DG （distributed generation） installation. In most published researches, different optimization methods are developed to obtain optimal relay settings to achieve coordination in case of not installing DG, then depending on the achieved optimal obtained relay settings, FCL impedance is deduced to ensure relays coordination restoration in case of installing DG. Based on original optimal relay settings, obtained FCL impedance is not the minimum one required to achieve relay coordination. The contribution of this paper is the generation of multi sets of original relay settings that increase the possibility of finding FCL impedance of minimum value which is lower than the calculated value based on original optimal relay settings. The proposed method achieves better economic target by reducing FCL impedance. The proposed approach is implemented and tested on IEEE-39 bus test system.
文摘With the global energy transition,the proportion of renewable energy power generation in total electricity production has exceeded 30%and continues to rise,even the ratio is higher in China.Multi-terminal high-voltage direct-current(MT-HVDC)transmission systems have advantages of integration of distributed renewable energy sources,dynamic grid interconnections,and reliable islanding operation capabilities,being critical for next-generation power grid.Current limiting technologies are pivotal in maintaining grid safety and stability,especially for HVDC systems without natural zero-crossing point in fault currents.In this perspective,a superconducting fault current limiter(SFCL)with combination of resistance and inductance is necessary and more effective solution in protecting MT-HVDC transmission systems.
基金supported in part by the National Natural Science Foundation of China(No.52207126)the Natural Science Foundation of Sichuan Province(No.2024NSFSC0869)the Joint Funds of the National Natural Science Foundation of China(No.U22B6006).
文摘Fault current limiting is a critical technology to en sure the safe operation of modular multilevel converter based multi-terminal direct current(MMC-MTDC)grids.This paper proposes a fault severity classification based coordination con trol strategy of fault current limiter(FCL)and MMC for adap tive fault current limiting.The proposed strategy reduces the in vestment in FCL,and keeps the bus voltages of non-faulty lines at reasonable values.Firstly,a rapid fault circuit parameter esti mation(FCPE)method using initial fault current information is proposed.With this method,the fault distance and fault transi tion resistance can be quickly estimated,which are used for a quantitative indication of the fault severity.Subsequently,the coordination control strategy of FCL and MMC is proposed,in which the FCL action is prioritized,while the control of MMC is complementary for current limiting.Based on the proposed strategy,fault severity phase planes(FSPPs)are constructed to assess fault severity and calculate the activation time of FCL and voltage regulation factor of MMC.Therefore,the FCL acti vation and MMC control are matched to the fault severity.The effectiveness and advantages of the proposed strategy are vali dated by the simulations in PSCAD/EMTDC.
基金supported in part by the Universidad Nacional de La Plata (UNLP)Project I255in part by Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET)PIPN°112-2015-0100496COin part by the Agencia Nacional de Promoción Científica y Tecnológica (ANPCyT)PICT N°2015-2257。
文摘Distributed generation units(DGUs)bring some problems to the existing protection system,such as those associated with protection blinding and sympathetic tripping.It is known that fault current limiters(FCLs)help minimize the negative impact of DGUs on the protection system.In this paper,a control-based FCL is proposed,i.e.,the FCL is integrated into the DGU control law.To this end,a predictive control strategy with fault current limitation is suggested.In this way,a DGU is controlled,not only for power exchange with the power grid but also to limit its fault current contribution.The proposal is posed as a constrained optimization problem allowing taking into account the current limit explicitly in the design process as a closed-loop solution.A linear approximation is proposed to cope with the inherent nonlinear constraints.The proposal does not require incorporating extra equipment or mechanisms in the control loop,making the design process simple.To evaluate the proposed control-based FCL,both protection blinding and sympathetic tripping scenarios are considered.The control confines the DGU currents within the constraints quickly,avoiding large transient peaks.Therefore,the impact on the protection system is reduced without the necessity that the DGU goes out of service.
文摘To select the type and value of the impedance of fault current limiters（FCLs） for power network designers, we introduce a new method to calculate the optimum value of FCL impedance depending on its position in the network. Due to the complexity of its impedance, the costs of both real and imaginary parts of FCL impedance are considered. The optimization of FCL impedance is based on a goal function that maximizes the reduction of the fault current while minimizing the costs. While the position of FCL in the network has an effect on the calculation of the optimum impedance value, the method for selecting FCL location is not the focus of this study. The proposed method for optimizing FCL impedance can be used for every network that has symmetrical and/or asymmetrical faults. We use a 14-bus IEEE network as an example to explain the process. The optimum FCL impedance used in this network is calculated by considering the vast range of costs for both real and imaginary parts of FCL impedance.
基金supported by the National Key R&D Program of China(2018YFB0904300)。
文摘A 500 kV high-voltage AC fault current limiter(FCL)based on a high coupled split reactor(HCSR)is pro-posed by the National key R&D project team.Low impedance under normal conditions and high impedance under short-circuit conditions are accomplished by the cooperation of HCSR and high-speed switches.High-speed switches play an important role in current limiting processes,thus interruption characteristics of the high-speed switch in the 500 kV FCL are studied in this paper.The simulation model of the FCL and the external equivalent power grid are established.The short-circuit current and recovery voltage characteristics of the high-speed switch in FCL are simulated.The results show that maximum DC component of the short-circuit current of the high-speed switch reaches 91%,the maximum peak value is 118 kA,and the longest arcing time is 14.8 ms.There is a discontinuity in the curve of the short-circuit current peak and arcing time as a function of the short-circuit occurrence time;the peak recovery voltage of a single break of the high-speed switch has a maximum value of 87.5 kV under a three-phase ungrounded short-circuit condition,and the rate of rise of recovery voltage is o.22 kV/s.The recovery voltage peak shows a period change with the short-circuit occurrence time,and the period is 10 ms.The effects of the shunt capacitor value and short-circuit ground resistance on the recovery voltage of high-speed switching are also studied.The research can be used for reference by R&D personnel and testersof500kVFCLs.Index Terms-Fault current limiter(FCL),high coupled split reactor(HCSR),high-speed switch,interruption characteristics,short circuit current.
文摘This paper presents a new type of fault current limiter (FCL) based on fast closing switch, which is composed of a capacitor bank and a reactor in series. The main control component is a fast closing switch connected in parallel with the capacitors, which is driven by the electromagnetic repulsion force. It can response the order within 1 ms. When fault occurs, the switch closes and the capacitors are bypassed, and the fault current is limited by the reactor. Simulation analysis and experiment show that the electromagnetic repulsion force actuator can meet the demand of fast closing switch, it is feasible to develop the FCL with low cost and high reliability.
文摘Several substations in operation were commissioned decades ago.These substations are overstressed,then their protection equipment cannot provide an effective safety condition to the system.In the worst cases,short‐circuits can cause permanent damage to the system if the overcurrent is higher than the capacity of the installed equipment.There are some possible solutions for those cases:replace all the equipment in the overstressed substation,build a new one in parallel or install a fault current limiter(FCL)device.From an economic point of view,introducing FCLs in the power system is the best way to solve the described problem.The commercial solutions available are the pyrotechnic FCL,air coil reactor,neutral earthing resistor,and high impedance transformer.However,these devices are limited and present several drawbacks.Since the’70s,there has been a search for reliable FCL devices that do not interfere in the regular operation of substations and could limit the fault currents to the protection system rated level.There were so many FCL technologies proposed in the last decades.These proposed new devices may use superconducting technologies,power electronics,or both.This paper reviews proven FCL technologies,focusing on full‐scale devices demonstrated in field and lab tests.The goal is to introduce the main FCL technologies in development and discuss didactically their operation principle,the built prototypes,the commercial units,whether they exist,and the main drawbacks for each technology presented.A final analysis of the level of maturity for each FCL technology is discussed using the TRL(Technology readiness level)scale in order to find technologies with more potential for mass production.The three technologies closer to the full commercial application are:the Resistive Superconducting FCL,the Saturated Iron Core FCL,and the Series Reactor FCL.
基金supported in part by the National Key Research and Development Program under Grant 2017YFB0902300。
文摘The design progress of superconducting fault current limiter(SFCL)for transmission voltage is presented,with a focus on the results of recent key experiments that have led to a state‐of‐the‐art high‐voltage high‐capacity super‐conducting current limiting techniques:the resistive alternating current(AC)SFCL,saturated iron cores AC SFCL,and resistive direct current(DC)SFCL.The main driving factors for designing SFCL in these projects are the preparation of high‐performance superconducting materials,the development of large‐scale superconducting current limiting winding,system testing,and operation technology.Based on the authors’experience with both AC and DC SFCLs,this paper focuses on the main design aspects of resistive SFCL at transmission voltage.The relationship between the hot spot caused by the inhomogeneity of long superconducting tape and the overall parameter selection is presented.In addition,the thermal calculation based on the current limiting resistance and a real‐time current curve is also proposed for the parameter design of the current limiting winding.
