Showing papers on "Fault current limiter published in 2009"
TL;DR: In this paper, two approaches are proposed to solve the directional overcurrent relay coordination problem associated with the installation of distributed renewable generation (DRG) in interconnected power delivery systems (IPDS), depending on the existing system protection capability (adaptive or non-adaptive).
Abstract: Two approaches are proposed to solve the directional overcurrent relay coordination problem associated with the installation of distributed renewable generation (DRG) in interconnected power delivery systems (IPDS), depending on the existing system protection capability (adaptive or non-adaptive). For adaptive protection systems, the first proposed approach introduces a procedure to select the optimal minimum number of relays, their locations and new settings. This procedure is restricted by the available relay setting groups. For non-adaptive protection systems, the second proposed approach implements a practice to obtain optimal minimum fault current limiter values (FCL) to limit DRG fault currents and restore relay coordination status without altering the original relay settings. An integration of the proposed two approaches is evaluated for IPDSs possessing both protection systems. Three scenarios are assessed for different numbers of DRGs, and DRG and fault locations using an optimisation model implemented in GAMS software and a developed MatLab code. The obtained results are reported and discussed.
139 citations
TL;DR: In this article, a diode-bridge type nonsuperconductor fault current limiter (NSFCL) is proposed to control the magnitude of DC reactor current, a discharging resistor is used in the proposed structure, and a series connection of DC voltage source with DC reactor is used to compensate the power loss of both nonsuperconducting dc reactor and diodes of fault current limiters.
Abstract: In this paper, a diode-bridge-type nonsuperconductor fault current limiter (NSFCL) is proposed. The structure has the capability of controlling the DC reactor current that yields to control the magnitude of fault current. In order to control the magnitude of DC reactor current, a discharging resistor is used in the proposed structure. By controlling the magnitude of DC reactor current, it is possible to reduce the current rating and inductance of DC reactor. In addition, a series connection of DC voltage source with DC reactor is used to compensate the power loss of both nonsuperconducting dc reactor and diodes of fault current limiters (FCLs). By means of proposed NSFCL, it is possible to eliminate all disconnecting switches in the distribution network. The simulation and experimental results are presented to clarify the theory and possibility of implementation of the proposed NSFCL.
103 citations
TL;DR: In this paper, a saturated iron-core type 35 kV/90 MVA superconductive fault current limiter was developed and installed in a transmission network at Puji substation of China Southern Power Grid for live-grid operation.
Abstract: We developed a saturated iron-core type 35 kV/90 MVA superconductive fault current limiter and installed the device in a transmission network at Puji substation of China Southern Power Grid for live-grid operation. Innovative design in the iron-core configuration ensures that the device has low impedance in normal power transmission and sufficiently high impedance for a fault current limiting action. A magnetization control circuit allows the iron-core to be saturated or de-saturated depending upon the functional requirements. An energy release and voltage-surge protection unit can promptly discharge the magnetic energy accumulated in the iron-core and suppress the induced and surge voltages of the dc circuit in a current limiting event. This device has been designed to reduce the magnitude of a fault current by about 50%, which will prevent the breaking capacity of the existing circuit breakers in the transmission network from being exceeded in the predictable future. This article presents structural and functional specifications and reports up-to-date live-grid operation data of the device.
69 citations
Patent•
11 Sep 2009TL;DR: In this paper, a method, voltage source converter and computer program product for limiting the current in a DC power transmission system are disclosed, which includes a control unit and at least one switching unit of a first type provided in the fault current path and that includes a primary switching element together with an anti-parallel secondary controllable rectifying element.
Abstract: A method, voltage source converter and computer program product for limiting the current in a DC power transmission system are disclosed. The voltage source converter has an AC side and a DC side and a fault current path between these sides. It furthermore includes a control unit and at least one switching unit of a first type provided in the fault current path and that includes a primary switching element together with an anti-parallel secondary controllable rectifying element. Based on a fault being detected in the DC power system when the primary switching elements of the converter are blocked, the control unit changes the control of the controllable rectifying element from acting as a non-controllable rectifying to acting as a controllable rectifying element.
65 citations
TL;DR: The limiting capability of YBCO CCs has been investigated and was demonstrated in a successful laboratory test of a 2.2 MVA medium voltage FCL and the cooperation has entered a new DOE funded joint project that encompasses the design, construction and test of an 115 kV FCL for power transmission within a time frame of 4-5 years and additional partners.
Abstract: All over the world there is a growing need for current limiting devices in electrical networks with steadily increasing power demands and fault currents. Production of YBCO coated conductors (CCs) paves the way for the economic viability of superconducting fault current limiters (FCLs) both in power distribution and transmission networks. In a cooperation between AMSC and Siemens the limiting capability of YBCO CCs has been investigated and was demonstrated in a successful laboratory test of a 2.2 MVA medium voltage FCL. This device is based on bifilar coils as switching elements and corresponds to one phase of a 3-phase FCL designed for the 13 kV-class distribution voltage level. In more than 40 switching tests at voltages up to 7.7 kV the device showed excellent limiting performance. Presently this cooperation has entered a new DOE funded joint project that encompasses the design, construction and test of a 115 kV FCL for power transmission within a time frame of 4-5 years and additional partners. AMSC as the project leader is responsible for wire manufacturing, system integration and cryogenics. Siemens' main task is switching modules development, Nexans contributes the high voltage terminations and Los Alamos National Lab investigates AC losses. Installation and testing are planned for a Southern California Edison substation. A project overview and progress under the first phase will be reported.
52 citations
26 Jul 2009
TL;DR: In this paper, the effect of proposed Solid State Fault Current Limiters (SSFCLs) on reduction of fault current is investigated and a genetic algorithm is employed to search for the optimal number, locations and size of proposed SSFCL.
Abstract: Expose of distributed generation (DG) to the distribution network increases the fault current level. This will give rise to fault current which is normally greater than interrupt capability of breakers and fuses. The introduction of Solid State Fault Current Limiters (SSFCLs) becomes an effective way for suppressing such a high short-circuit current fault in distribution systems. In this paper, the effect of proposed SSFCL on reduction of fault current is investigated. Then genetic algorithm is employed to search for the optimal number, locations and size of proposed SSFCL. The Numerical and simulation results show the efficiency of proposed GA based FCL allocation and sizing method in terms of minimization of distribution protection system cost.
48 citations
TL;DR: This paper investigates the SFCL and DC breaker and their use in combination and proposes that the fault current be limited by a superconducting fault-current limiter (SFCL) and that this limited current is interrupted by a DC circuit breaker.
Abstract: Many alternative energy power generation systems create DC electricity. Also, many devices consume DC converted from AC. Therefore, it may be possible to reduce conversion losses and CO2 emissions by adopting DC distribution. We assume that superconducting cables will be used for dc distribution because their electrical resistance is almost zero. However, if a superconducting cable is adopted, it is of great concern that if an excessive current flows because of, for instance, a short circuit, then there is a possibility that this current cannot be interrupted by a circuit breaker alone. We propose that the fault current be limited by a superconducting fault-current limiter (SFCL) and that this limited current is then interrupted by a DC circuit breaker. In this paper, we have separately investigated the SFCL and DC breaker and their use in combination.
44 citations
TL;DR: In this article, the status of three key programs currently underway at American Superconductor Corp. are described, including a transmission voltage high temperature superconducting cable program, with funding support from the US Department of Energy.
Abstract: This paper will describe the status of three key programs currently underway at American Superconductor Corp. The first program is the LIPA project which is a transmission voltage high temperature superconducting cable program, with funding support from the US Department of Energy. The 600 m cable, capable of carrying 574 MVA, was successfully installed and commissioned in LIPA grid on April 22, 2008. An overview of the project, system level design details and operational data will be provided. In addition, the status of the newly awarded LIPA II project will be described. The second program is Project Hydra, with funding support from the US Department of Homeland Security, to design, develop and demonstrate an HTS cable with fault current limiting functionality. The cable is 300 m long and is being designed to carry 96 MVA at a distribution level voltage of 13.8 kV. The cable will be permanently installed and energized in Manhattan, New York in 2010. The initial status of Project Hydra will be presented. The final program to be discussed is a transmission voltage, high temperature superconducting fault current limiter funded by the US DOE. The project encompasses the design, construction and test of a 115 kV FCL for power transmission within a time frame of 4–5 years. Installation and testing are planned for a Southern California Edison substation. A project overview and progress under the first phase will be reported.
36 citations
TL;DR: In this article, a variety of newly developed configurations: striation, narrow width, low-resistance joints and high quality insulation are described, which will promote the wide use of 2G HTS wire.
Abstract: Besides critical current and conductor length, thermal stability, mechanical properties and ac loss characteristics of second-generation (2G) HTS wire are very important performance parameters to electric power device applications. Each application sets specific technical requirements on conductors. The properties of the practical 2G HTS wire manufactured at SuperPower, Inc. have enabled satisfactory performance in a number of demonstration devices including cable, high-field magnetic coil and fault current limiter. Yet, effort is being made to develop new conductor structures and configurations toward further enhanced performance in order to extend the potential of 2G HTS wire over a wider application range. This paper describes a variety of newly developed configurations: striation, narrow width, low-resistance joints and high quality insulation. The performance of wire with new configurations will promote the wide use of 2G HTS wire.
35 citations
Patent•
29 Jul 2009
TL;DR: In this article, a fault line selection method for a small current grounding system of a distribution network comprises assembling resistances, a vacuum contactor, a single-phase voltage mutual-inductor and a zero sequence current mutual-indicator in parallel.
Abstract: A fault line selection method for a small current grounding system of a distribution network comprises: assembling resistances, a vacuum contactor, a single-phase voltage mutual-inductor and a zero sequence current mutual-inductor in parallel; when the permanent grounding fault occurs in the small current grounding system of the distribution network, switching the resistances connected in parallel in a set time, and further phase angles of the zero sequence currents on outgoing lines of the substation changing; and determining the fault line according to change characteristic roots of the phase angles of the zero sequence currents.
35 citations
TL;DR: In this paper, a voltage compensation type active superconducting fault current limiter (SFCL) was proposed to reduce the transient swing amplitude of rotor and extend the critical clearance time under mode 1, compared with mode 2 and mode 3 having few effects on enhancing the transient stability.
Abstract: We have proposed a voltage compensation type active superconducting fault current limiter (SFCL). In this paper, the influence of the SFCL on the transient stability of power system is investigated. For the typical one-machine infinite-bus system, the power-angle characteristics of generator with SFCL are studied in different working conditions, and the transient physical process is analyzed. Using MATLAB SIMULINK, the power-angle swing curves are simulated under different current-limiting modes, fault types and fault clearance times. The results show that the proposed SFCL can effectively reduce the transient swing amplitude of rotor and extend the critical clearance time under mode 1, compared with mode 2 and mode 3 having few effects on enhancing the transient stability.
TL;DR: In this article, the authors constructed and tested a model superconducting fault current limiter (SFCL) using a high-temperature superconding film according to a design that includes a vacuum interrupter with an electromagnetic repulsion mechanism.
Abstract: The authors constructed and tested a model superconducting fault current limiter (SFCL) using a high-temperature superconducting film according to a design that includes a vacuum interrupter with an electromagnetic repulsion mechanism. The superconductor and the vacuum interrupter are connected in parallel with a bypass coil. If a fault occurs and current flows through the system, the superconductor is quenched and the current is transferred to the parallel coil because of the voltage drop in the superconductor. This large current in the parallel coil actuates the magnetic repulsion mechanism of the vacuum interrupter. On opening the vacuum interrupter, the current in the superconductor is interrupted. This model is expected to exhibit very low-energy consumption by the superconductor. The authors succeeded in interrupting the current flowing in the superconductor within a half-cycle using a prototype SFCL. An improved SFCL with higher voltage and current ranges was used to carry out current-limiting tests and to investigate the possibility of adapting our SFCL in a power system. The authors also carried out a current-limiting test using a conventional high-speed vacuum circuit breaker (HSVCB) as a new method for realising our concept.
TL;DR: In this article, a dc magnetization system, consisting of a HTS dc bias coil, a current source, a high-speed switch, and an energy release circuit, was built for a 35 kV/90 MVA saturated iron-core fault current limiter to enhance its functional capability and reliability and to reduce its size and weight.
Abstract: A dc magnetization system, comprises a HTS dc bias coil, a current source, a high-speed switch, and an energy release circuit, was built for a 35 kV/90 MVA saturated iron-core fault current limiter to enhance its functional capability and reliability and to reduce its size and weight. The dc bias coil is made of high temperature superconducting silver sheathed Bi-2223 tapes with a magnetization capacity of 141,000 ampere ldr turns. The current source is able to supply a maximum of 350 A constant current. The energy release circuit was designed to quickly discharge the magnetic energy of the saturated iron cores and to suppress the voltage surge across the dc coil when the magnetization circuit was switched to open in a short-circuit event. This controllable magnetization system enables the fault current limiter to respond to a short-circuit fault in one millisecond, to reach full current limiting function in 5 milliseconds, and to re-saturate the iron cores in 800 milliseconds after the clearance of a fault. In this paper, we introduce the configuration and specifications of the system. Some experimental results are also reported.
TL;DR: In this paper, experimental results from a shielded inductive type superconducting fault current limiter (SFCL) demonstrator incorporating YBCO coated conductor together with results from an analytic study of a large 13 MVA SFCL are discussed.
Abstract: We report experimental results from a shielded inductive type superconducting fault current limiter (SFCL) demonstrator incorporating YBCO coated conductor together with results from an analytic study of a large 13 MVA SFCL. Important parameters such as the superconductor temperature rise, re-cooling time and voltage characteristics following a short-circuit quench are discussed. These results are compared with the measured and predictive performance of a resistive type SFCL incorporating a similar volume of YBCO CC and providing the same level of current limiting.
TL;DR: In this article, a three-phase set of current limiting coils installed in a sub-cooled nitrogen cryostat with a GM cryocooler, circuit breakers and a sequence circuit was developed and successfully tested.
Abstract: As one of the programs in the Ministry of Economy, Trade and Industry (METI) project regarding R&D on superconducting coated conductor, three-phase superconducting fault current limiter (SFCL) for 6.6 kV application was developed and successfully tested. The developed SFCL was mainly comprised three-phase set of current limiting coils installed in a sub-cooled nitrogen cryostat with a GM cryocooler, circuit breakers and a sequence circuit. The whole system was installed in a cubicle. Two tapes of coated conductor were wound in parallel in each coil to obtain the rated current of 72 A rms. After developing the whole SFCL system, short circuit experiments were implemented with a short circuit generator. In a three-line ground fault test, the SFCL successfully restricted the prospected short circuit current over 1.6 kA to about 800 A by the applied voltage of 6.6 kV. The SFCL was installed in a user field and connected with a gas engine generator, followed by a consecutive operation. In this program, 600 A class FCL coil, with which four coated conductor tapes were wound, was also developed. The coil showed sufficiently low AC loss at the rated current. With these results, the program attained the planned target of the fundamentals for the 6.6 kV/600 A SFCL.
TL;DR: In this paper, the authors proposed the use of non-superconducting DC reactor type fault current limiter (NSFCL) instead of superconducting fault current limiters (SFCLs) which has high cost and technology.
Abstract: This paper proposes the use of non-superconducting DC reactor type fault current limiter (NSFCL) instead of superconducting fault current limiters (SFCLs) which has high cost and technology. Proposed FCL consists of three similar sets, each including a diode bridge and a single non-superconducting DC reactor. The device is connected in series with distribution line and it has almost no effect on the normal system operation. It is not necessary to use a control circuit and it has a simple and cheap power circuit. Design characteristics, analytical analysis and overall transient and steady-state performance of NSFCL in normal and fault conditions are presented in this paper. The comparison between experimental and simulation results indicate good agreements. The results confirm that the power loss of NSFCL is a very small percentage of distribution line power. Also, the system current and load voltage distortions due to using NSFCL is explained and simulated. Copyright © 2008 John Wiley & Sons, Ltd.
17 May 2009
TL;DR: In this paper, a new configuration of the inductive Fault Current Limiters (FCLs) is introduced, where the amount of required material has been reduced considerably and the induced overvoltage across the dc winding is decreased.
Abstract: Installation of new generating units and increased penetration of distributed generators (DGs) in the power systems increase the total power transmitted in the power grid. In the case of a fault, the amount of power captured by a short circuit is enlarged, leading to higher peaks of the fault currents and, consequentially, to higher stresses to the power system components. Installations of Fault Current Limiters (FCLs) are expected to prevent expensive upgrade and replacement of the components exposed to the over-stresses. Inductive FCL are particularly interesting due to their inherent reaction to a fault. However, some challenges are to be solved: excessive weight and induced over-voltage across the dc winding. The goal of this paper is to introduce a new configuration of the inductive FCL, where the amount of the required material has been reduced considerably and the induced over-voltage across the dc winding is decreased. Employment of one core per-phase instead of two reduces the amount of magnetic material. The core has three legs, where the middle leg is used as a shunt path for the ac flux. It enables a gap insertion in the ac magnetic circuit without influencing the dc magnetic circuit, i.e. amount of dc winding material. This means that a smaller core (less magnetic material) can be used for a same power level. The simulation results obtained from FCL models created in SaberDesigner are presented. They have been confirmed through the testing of the lab-scale prototype.
05 Jun 2009
TL;DR: A fault current limiter based on an arrangement of parallel connected high temperature superconducting tapes constituting a limiter element was designed and tested in 220 V line for a fault current peak between 1 kA to 2 kA as mentioned in this paper.
Abstract: A fault current limiter (FCL) based on an arrangement of parallel connected high temperature superconducting tapes constituting a limiter element was designed and tested in 220 V line for a fault current peak between 1 kA to 2 kA. The limiter employed second generation (2G) HTS tapes of YBCO coated conductor reinforced with stainless steel. Four tapes were electrically connected in parallel with 0.4 m effective length per element wherein 16 elements connected in series constitutes a single-phase unit. The FCL performance was evaluated through over-current and current fault tests. Its recovery characteristics were used to design the shunt protection. The designed limiting ratio is 4 for 16 elements and the experimental result for one element showed a 20% limiting ratio. For the fault current test one element can withstand five cycles of fault without degradation. It was observed recovery times below 0.5 s under nominal load using a shunt resistance of 173 mOmega.
TL;DR: In this paper, a hybrid fault current limiter is proposed for primary distribution systems, which incorporates a high temperature superconducting element in parallel with other two branches, an inductive impedance to share the fault current with, and a gate-turn-off thyristor switch controlled to work in either of two modes.
13 Nov 2009
TL;DR: Based on the characteristics of the DC system, a novel circuit scheme has been proposed in this article, which makes full use of the ideology of soft switching and current-commutation forced by resonance.
Abstract: Existing mechanical circuit breakers can not satisfy the requirements of fast operation in power system due to noise, electric arc and long switching response time. Moreover the non-grid-connected wind power system is based on the Flexible Direct Current Transmission (FDCT) technique. It is especially necessary to research the Solid-State Circuit Breakers (SSCB) to realize the rapid and automatic control for the circuit breakers in the system. Meanwhile, the newly-developed Solid-State Circuit Breakers (SSCB) operating at the natural zero-crossing point of AC system is not suitable for a DC system. Based on the characteristics of the DC system, a novel circuit scheme has been proposed in this paper. The new scheme makes full use of ideology of soft-switching and current-commutation forced by resonance. This scheme successfully realizes the soft turn-on and fast turn-off. In this paper, the topology of current limiter is presented and analytical mathematical models are derived through comprehensive analysis. Finally, normal turn-on and turn-off experiments and overload delay protection test were conducted. The results show the reliability of the novel theory and feasibility of proposed topology. The proposed scheme can be applied in the grid-connected and non-grid-connected DC transmission and distribution systems.
TL;DR: In this paper, a liquid metal fault current limiter (LMFCL) was investigated as a tool for improving the power quality and reliability of power service, which can effectively limit the fault current by taking advantage of the pinch effect and arcs in LMFCL.
Abstract: A liquid metal fault current limiter (LMFCL) was investigated as a tool for improving the power quality and reliability of power service. The LMFCL is a newly developed current limiter for low-voltage power systems. It can effectively limit the fault current by taking advantage of the pinch effect and arcs in the LMFCL. A multiphysics simulation of magneto-fluid in the LMFCL was performed based on the 3-D finite element method for analysis of the pinch effect. The magnetic forces were calculated, and the turbulence driven by the magnetic forces was simulated. The results of the turbulent simulation coincide with those of the experiments. Several characteristics of the LMFCL are described based on analysis of the results of experiments with single-phase power sources of 253, 440, and 725-V.
20 Apr 2009
TL;DR: In this article, a fault isolation and re-configuration on a DC bus distributed through an electrical system is studied, where three electromechanical no load switches in a single assembly are utilized at the interface between electrical zones.
Abstract: Fault isolation and re-configuration on a DC bus distributed through an electrical system is studied. This paper builds upon previously proposed zonal architectures that ensure power continuity during a fault and isolation of a fault with minimal impact to un-faulted portions of the system. The approach utilizes no load switches for fault isolation aided by multiple power electronic converters feeding the DC bus. Three electromechanical no load switches in a single assembly are utilized at the interface between electrical zones. The ability of the system to segregate the fault without loss of power to unfaulted zones is very limited without network communications between the power converter and switch components. A simulation model of the DC portion of the integrated power system is developed and simulation results demonstrate the effectiveness of the model in verifying the method for locating a fault and in predicting the impact of the fault to the external medium voltage AC distribution system and inter-zonal low voltage interfaces.
26 Jul 2009
TL;DR: In this article, the impact of fault current limiters performance on reliability of circuit breakers is presented and the absolute, stress-induced failure probability for a given circuit breaker of a power system is computed with and without using FCL.
Abstract: The fault current levels through the breakers have a significant impact on failure probability of circuit breakers. With the expansion of the network, fault current levels increase and circuit breakers are subject to increasing duties and stresses, and are more tending to failures. Deferent method such as circuit breaker replacement proposed. In this paper implementation of Fault Current Limiters (FCL) for solving this problem is proposed. The impact of fault current limiters performance on reliability of circuit breaker is presented. Hence, the absolute, stress-induced failure probability for a given circuit breaker of a power system is computed with and without using FCL. Finally, an economic analysis is performed and an economic feasibility study is conducted. The proposed method is evaluated by numerical studies based on IEEE RTS test system.
26 Jul 2009
TL;DR: In this article, an overview of the different FCL technologies, improvements made in FCL devices and assesses their impacts on overcurrent relay protection is presented based on the results obtained from a network splitting model developed using PSCAD/EMTDC.
Abstract: Due to increasing fault current levels in transmission and distribution level, considerable attention is given towards developing Fault Current Limiter (FCL) devices in recent years. Most of the FCL technologies are in their initial stages of deployment and are being assessed before their use become more widespread. As the objective of FCL is to limit the fault current, it will have impact on protection system. This paper gives an overview of the different FCL technologies, improvements made in FCL devices and assesses their impacts on overcurrent relay protection. An analysis on Overcurrent relay operating time and therefore co-ordination has been presented based on the results obtained from a network splitting model developed using PSCAD/EMTDC.
TL;DR: In this paper, a hybrid FCL system consisting of a coil, a fast switch and a resistor for bypassing the fault current was designed and tested, which showed fast and efficient current limiting characteristic.
Abstract: This paper deals with design and operating test of a novel hybrid FCL. The FCL system consists of a coil, a fast switch and a resistor for bypassing the fault current. The switch is driven by novel non-inductive coil suggested in this paper but an extra driving coil is required for fast switch in existing hybrid FCL. We used two kinds of HTS wire for the coil. The impedance of the coil was negligible in normal operation. But different quench characteristics of HTS wires caused asymmetric current distribution which induced effective magnetic flux in the coil during faults. The switch was opened by repulsive force from this magnetic flux in fast response to the fault. Then, all current were flew through the normal conductive bypass resistor connected in parallel to both the coil and the switch. Electromagnetic analysis of the coil based on finite element method was performed. Also, a small-scale asymmetric non-inductive coil was designed, fabricated and tested. The proposed hybrid FCL system showed fast and efficient current limiting characteristic.
TL;DR: In this article, the authors report results of tests on several MgB2 round wire samples wound with small bend diameters and assess their suitability for use in a resistive type superconducting fault current limiter with a practical aspect ratio.
Abstract: This paper reports results of tests on several MgB2 round wire samples wound with small bend diameters. Wire suitability for use in a resistive type superconducting fault current limiter with a practical aspect ratio is assessed in terms of current limiting performance and tolerance to mechanical process handling. A fully controllable low current supply was used to determine the variation of the wire impedance against frequency and temperature. The frequency response enabled the calculation of coil inductance and superconducting resistance. Critical temperatures measured were in the range of 34 K-39 K. A high current supply was used to test the coil current limiting properties in the temperature range 25-32 K in self field at 50 Hz. Good, repeatable current limiting properties were observed with quench currents in the range 95-390 A. Good tolerance to mechanical process handling was also evident.
TL;DR: In this article, the impact of inductive fault current limiters (FCLs) on the out-of-phase fault current level was analyzed, and a method for determining the critical length of the power transmission tie lines was also given.
Abstract: With respect to power systems installed with inductive fault current limiters (FCLs), the impact of an FCL on the out-of-phase fault current level was first analyzed, and thereby a method for determining the critical length of the power transmission tie lines was also given. Based on theoretical analysis and deduction, strict mathematical formulas were obtained to properly describe the relationship between the current limit factor and the recovery voltage of a circuit breaker (CB) as well as the rate of rise of recovery voltage (RRRV). Further, the concrete impacts of an FCL on the maximum and the RRRV of the recovery voltage were analyzed. Regarding out-of-phase faults, a conception of interruption severity as well as its quantitative expression for CBs was introduced, and a formula was established to incorporate the influence from the current limit factor and stray capacitance on the interruption severity of CBs, subsequently followed by detailed investigations. The aforementioned proposed research presents analytical methodology and practical reference for the parameter optimization of the inductive FCL and reliable selection of the interrupting characteristics of the high-voltage CBs.
TL;DR: In this paper, the design of a resistive type superconducting fault current limiter using parallel-connected YBCO thin films is discussed, including the role of a parallel resistor and the influence of individual thin film characteristics, based on both theory and experimental results.
Abstract: Superconducting fault current limiters (SFCLs) are able to reduce fault currents to an acceptable value, reducing potential mechanical and thermal damage to power system apparatus and allowing more flexibility in power system design and operation. The device can also help avoid replacing circuit breakers whose capacity has been exceeded. Due to limitations in current YBCO thin film manufacturing processes, it is not easy to obtain one large thin film that satisfies the specifications for high voltage and large current applications. The combination of standardized thin films has merit to reduce costs and maintain device quality, and it is necessary to connect these thin films in different series and parallel configurations in order to meet these specifications. In this paper, the design of a resistive type SFCL using parallel-connected YBCO thin films is discussed, including the role of a parallel resistor and the influence of individual thin film characteristics, based on both theory and experimental results.
TL;DR: In this paper, the quench/recovery characteristics of YBCO-coated conductors with stabilizers with various thicknesses were investigated and it was shown that, as the thickness of the stabilizer decreased, both the final approach temperature and the recovery time decreased.
Abstract: The increased use of distributed power generation has led to increasingly high fault current levels. A superconducting fault current limiter (SFCL) is a potential solution to prevent the problem of short-circuit currents. YBCO-coated conductors (CCs) are one of the most promising superconducting materials for SFCLs. Most YBCO CCs have stabilizers, which play a significant role in limiting the fault current in the SFCL. Therefore, the selection of the appropriate material and the thickness of the stabilizer of the CC used for the SFCL may affect its quench/recovery characteristics. In this paper, the quench/recovery characteristics of YBCO CC tapes having stabilizers with various thicknesses were investigated. The quench/recovery test results showed that, as the thickness of the stabilizer decreased, both the final approach temperature and the recovery time decreased.
Patent•
18 Dec 2009TL;DR: In this paper, a test equipment of direct current thyristor valve, and particularly related to a fault current test equipment for direct current Vt, is presented. And the test equipment includes fault current circuit, fault circuit includes resonant circuit, high voltage low current circuit and low voltage high current circuit.
Abstract: The present invention relates to a test equipment of direct current thyristor valve, and particularly relates to a fault current test equipment of direct current thyristor valve. This present invention equipment includes high voltage low current circuit and low voltage high current circuit, said test equipment includes fault current circuit, said fault current circuit includes resonant circuit, said high voltage low current circuit, low voltage high current circuit and fault current circuit are all connected with the thyristor sample Vt respectively. In his present invention, the thyristor sample is first heated through the high voltage circuit and low voltage high current circuit to reach the stable state. And then shut off the switch and carries out the test using the fault current which is produced by the fault current circuit. This prevents the power system from the short-circuit impact. Further more, the peak current and the current duration of the fault current circuit can be adjusted flexibly by changing the voltage of the adding energy circuit.