Showing papers on "Fault current limiter published in 2006"

Arc fault detection scheme for 42-V automotive DC networks using current shunt

Abstract: Introduction of higher dc system voltage distribution networks, such as the 42-V PowerNet in future passenger vehicles appears to be an unavoidable consequence of meeting the increasing future electrical power demand. Higher voltage electrical distribution networks in vehicles force considerable component and system changes regarding electrical safety and reliability. In the event of an arc fault, e.g., when a wire is pinched or cut, or disengaged terminals under load etc., the resulting current may be significantly lower than the trip current of the protection devices such as fuses and circuit breakers. In these cases either the fault is cleared late (depending on the time/current characteristics of the fuse) or, in some cases the fault may not be cleared at all. A cost effective arc fault detection scheme using input side current shunt was developed, built, and tested with different loads including motor loads to clear both parallel and series arc faults in a 42-V dc network. This paper presents the details of the developed arc fault detection scheme and test results under several fault conditions

Simulation of HTS saturable core-type FCLs for MV distribution systems

Abstract: The design principles and performance characteristics of a prototype high-temperature superconductor saturable magnetic core-type fault current limiter are described. These are based on a distribution network service provider feasibility specification that included the footprint and regulatory requirements for limiting fault currents. Time-domain simulations using PSCAD/EMTDC are given to illustrate specific applications and the transient behavior of the different distribution system configurations are investigated.

Fault current limiters report on the activities of CIGRE WG A3.16

Abstract: The paper presents an overall view on the activities of the CIGRE Working Group (WG) A316 which focuses on the interaction between different fault current limiting technologies and protection systems in both MV and HV systems Beside state of the art of fault current limiters (FCL) and a general classification of different types of FCLs, the paper presents the results of a survey which shows an increased need for short circuit current limitation in the voltage level of 110 to 145 kV The limiting behaviors as well as potential applications of fault current limiters are described and some basic ideas presented showing the influence of FCL devices on protection schemes The paper concludes with a report of a recent field test of a fault current limiter installed in a distribution network in Germany

Intelligent life testing methods and apparatus for leakage current protection

Abstract: An apparatus for testing the life of a leakage current protection device having a leakage current detection circuit and a trip mechanism having a switch device. In one embodiment, the apparatus a ground fault simulation unit, a fault detector of the leakage current detection circuit and the trip mechanism, and a life testing detection control unit having an MCU for controlling operation of the fault detector. In operation, a first signal (pulse signal) is sent to the gate of the switching device to generate a first voltage at the cathode of the switching device, a second signal is sent to the ground fault simulation unit to generate a simulated ground fault for the leakage current detection circuit to generate a second voltage at the gate of the switching device, and the first and second voltages are measured to determine whether a fault exists in the leakage current detection circuit and the trip mechanism.

Highlights of coated conductor development in Japan

Abstract: Coated conductors using RE–Ba–Cu–O (RE: rare earth element) superconductors have been expected to be used in many electric power applications since they have a high critical current density at liquid nitrogen temperature even under high magnetic fields. Many efforts have been made in development of processing for a long coated conductor with high superconducting performance. In Japan, the new five-year national project for development of coated conductor processing was started in FY2003 and was scheduled until the end of FY2007. The expected goals in this project are 500 m long tapes with a high Ic value of 300 A cm−1 W−1 at a production rate of 5 m h−1 etc. The progress in recent years is remarkable, such as long tapes over 100 m in length with high Ic values of over 100 A cm−1 W−1. The long tapes have been successfully realized by not only one institution but several. Additionally, a solenoid type magnet and a power cable using YBCO conductors have already been demonstrated as one of the preliminary results for applications. For the future plans of coated conductor applications, the following power devices using coated conductors have been proposed: (1) power cable, (2) transformer, (3) motor, (4) fault current limiter, (5) cryocooler and so on.

Behavior Investigations of Superconducting Fault Current Limiters in Power Systems

Abstract: When electric power systems are interconnected in operation, the fault current levels increase. This problem can be solved by deploying a bus-tie Superconducting Fault Current Limiter (SFCL) in distribution substations which allows two buses to be tied without significantly raising fault current levels. The Alternative Transient Program (ATP) version of Electromagnetic Transient Program (EMTP), ATPDraw and The Output Processor (TOP) are applied to investigate the operational behavior of the SFCL in a parallel connection of radial supply systems. The case study showed that an SFCL on bus tie location can not only suppress the fault current levels effectively but also improve the power quality and the reliability of the supply network. The simulation results will be presented and discussed in detail

Study of Superconducting Fault Current Limiter Using Vacuum Interrupter Driven by Electromagnetic Repulsion Force for Commutating Switch

Abstract: Using a high-temperature superconductor, we constructed and tested a model superconducting fault current limiter (SFCL). The superconductor and the vacuum interrupter as the commutation switch were connected in parallel using a bypass coil. When the fault current flows in this equipment, 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. Due to the opening of the vacuum interrupter, the current in the superconductor is broken. By using this equipment, the current flow time in the superconductor can be easily minimized. On the other hand, the fault current is also easily limited by large reactance of the parallel coil

Ground fault detector for vehicle

Abstract: A ground fault detector and detection method for a vehicle that can determine the cause of the occurrence of a ground fault after detecting the presence of the ground fault. The output terminal of a high-voltage battery is connected to one side of a coupling capacitor. In operation, a pulse signal is applied to a measurement point on the other side of the coupling capacitor, and the voltage generated at that point is detected. Whether the high-voltage battery or the electrical equipment units are grounded is determined. To determine the cause of the ground fault, the oscillation frequency of the square-wave pulse signal is changed and applied to the measurement point. From the change in voltage amplitude detected, it is determined whether the cause of the ground fault is a resistive or a capacitive ground fault, according to the change in the impedance of the battery or the units.

Over current protection coordination of distribution networks with fault current limiters

Abstract: The connection of new distributed generator (DG) to the existing network increases the fault current and disturbs the existing over current (O/C) protection coordination. The main focus of this study was to investigate the possibility of using a fault current limiter (FCL) to address the above issues. A case study was carried out for a 20 kV distribution network in interactive power system analysis (IPSA) simulation package. Connection of a DG to the considered network increases the fault current closer to the rating of two switchgears and disturbs the O/C protection coordination. An FCL is introduced and varies its impedance and location of installation to investigate the limiting capability and effect on protection coordination. The modifications required to O/C protection scheme for proper coordination were also investigated. The study proved that when locating the FCL near the DG, it limits the fault current while minimizing the problems associated with the protection.

Fundamental Characteristics of Superconducting Fault Current Limiter Using LC Resonance Circuit

Abstract: A new type of fault current limiter (FCL) utilizing series LC resonance circuit composed of a superconducting coil and a capacitor is proposed. The superconducting coil is wound by Bi-2223/Ag HTS tape conductor. The new FCL can suppress the rapid increase of a fault current by its energy storing capacity. Both theoretical analysis and experiments are carried out. The experimental result shows the current limiting ability of this FCL. The obtained experimental result agrees well with the theoretical one

Method and adaptive distance protection relay for power transmission lines

Abstract: A method and an adaptive distance protection relay for compensating for a remote line end infeed effect during determination of a distance (d) to a resistive fault on a three- phase power transmission line are presented. It is assumed that a fault current (IF) flows through the fault resistance (RF). A fault loop impedance (Zrelay) is first calculated by a known algorithm from phase voltages (Vph1, Vph2, Vph3) and phase currents (Iph1, Iph2, Iph3). Then a shift of the fault loop impedance (ΔZ) is determined from the fault loop impedance (Zrelay), the impedance of the transmission line for the positive current sequence (Z1L) and the phase angle (ϒ) of a complex fault current distribution factor (kF), where the fault current distribution factor (kF) is the ratio of the fault loop current (Irelay) to the fault current (IF). Finally, the distance to fault (d) is calculated by subtracting the impedance shift (ΔZ) from the fault loop impedance (Zrelay) and dividing the result by the impedance of the transmission line for the positive current sequence (Z1L).

Development and Test of 10.5 kV/1.5 kA HTS Fault Current Limiter

Abstract: Superconducting Fault Current Limiter (SFCL) is an attractive appliance for modern electrical power system. A 10.5kV/1.5 kA three-phase HTS fault current limiter was developed by IEE, CAS. This improved rectifier-type SFCL with HTS coil of 6.25 mH is going on a demonstrated long-term reliable operation in a real 10.5 kV substation located in Hunan, China. In a three-phase-to-ground short circuit test of grid, the prospective fault current of 3.5 kA was limited to 635 A at the pre-setup short-circuit point successfully

Visualization Study on Boiling of Nitrogen During Quench for Fault Current Limiter Applications

Abstract: For the development of a 13.2 kV/630 A bifilar winding type high-Tc superconducting fault current limiter (SFCL), a visualization study has been conducted to clarify boiling characteristics during the quench of the high-Tc SFCL. A series of experiments was carried out using a stainless steel strip on a G10 plate as a heating element to simulate the quench state of the high-Tc SFCL. A pulse of DC power input was applied to the strip in saturated and subcooled liquid nitrogen. The magnitude of the heat generation was varied from 10 W/cm2 to 170 W/cm2 and the period of the heat impulse was fixed at approximately 100 ms. Bubble behavior was observed by a high-speed camera through view ports of a cryostat. The boiling phenomena, the temperature rising of the strip and the recovery time were compared for different power densities and liquid nitrogen operating conditions. The bubble suppression was clearly observed with respect to the degree of subcooling

Transient Simulation and Analysis for Saturated Core High Temperature Superconducting Fault Current Limiter

Abstract: In this paper, the transient performance of a magnetic core fault current limiter (FCL) saturated by high temperature superconducting (HTS) dc bias winding is investigated by using both 3-D field-circuit coupled simulation and magnetic circuit analysis. A high voltage is induced on the dc HTS winding during the fault current state. The induced voltage is computed and a short circuit coil for the reduction of induced voltage is studied. The numerical computations are verified by the experiment results on an FCL prototype

Integration issues for fault current limiters and other new technologies- a utility perspective

Abstract: This paper presents some issues and perspectives on the needs for fault current limiting functionality, particularly for dense urban load centers. It provides some perspective on the present conditions relative to fault currents in New York City and potential sources for increased fault currents throughout the power grid. It provides the author's perspective on some requirements that an effective fault current limiter must meet, identifies some unique requirements for special applications and provides a broad overview of current industry activities pursued to encourage the development of multiple alternatives to mitigate fault currents, and to encourage wide stakeholder participation in this effort.

DC superconducting fault current limiter

Abstract: There is a lack of satisfying solutions for fault currents using conventional technologies, especially in DC networks, where a superconducting fault current limiter could play a very important part. DC networks bring a lot of advantages when compared to traditional AC ones, in particular within the context of the liberalization of the electric market. Under normal operation in a DC network, the losses in the superconducting element are nearly zero and only a small, i.e. a low cost, refrigeration system is then required. The absence of zero crossing of a DC fault current favourably accelerates the normal zone propagation. The very high current slope at the time of the short circuit in a DC grid is another favourable parameter. The material used for the experiments is YBCO deposited on Al2O3 as well as YBCO coated conductors. The DC limitation experiments are compared to AC ones at different frequencies (50–2000 Hz). Careful attention is paid to the quench homogenization, which is one of the key issues for an SC FCL. The University of Geneva has proposed constrictions. We have investigated an operating temperature higher than 77 K. As for YBCO bulk, an operation closer to the critical temperature brings a highly improved homogeneity in the electric field development. The material can then absorb large energies without degradation. We present tests at various temperatures. These promising results are to be confirmed over long lengths.

Superconducting fault current limiter (SFCL) in the medium and high voltage grid

Abstract: Superconducting fault current limiters (SFCLs) combine features not provided by conventional switching devices. In the medium voltage (MV) grid the installation of SFCLs as bus coupler and in the transformer feeders are of special interest. Thus the short circuit power can be increased without exceeding the admissible short circuit strength. In consequences higher loadings and perturbing custumers can be connected. In the high voltage (HV) grid an interesting application for SFCLs is the coupling of 110 kV sub-grids by which the surplus of transformer capacity can considerably be reduced. The reserve power is delivered by the other sub-grid, while the short-circuit current is limited to admissible values by SFCL. To prove the feasibility a 10 kV SFCL demonstrator was installed in a 10 kV substation. The fundamental design of the apparatus, the tests and the service experience are presented. In total the apparatus demonstrated a good long-term performance.

Manufacture and Test of Small-Scale Superconducting Fault Current Limiter by Using the Bifilar Winding of Coated Conductor

Abstract: Superconducting fault current limiters (SFCLs) have been developed by many research groups. However, there is no standard for current limiting device. Recently, YBCO coated conductor (C.C.) which is named as 2nd-generation wire has been developed rapidly. YBCO C.C. has many advantages for applying to fault current limiting material. In this paper, a bifilar winding type SFCL was manufactured using YBCO C.C. The bifilar coil was wound as pancake type, and the length of C.C. tape used was 8 m. The short-circuit test of the SFCL was performed successfully rated on 30V/80A. The SFCL had a very low impedance in normal operation and limited the fault current effectively when a fault occurred. From the result, it could be confirmed that the bifilar winding type FCL using YBCO C.C. is feasible. Large-scale SFCL using C.C. should be developed in the future

Effect of Magnetic Saturation on the Current Limiting Characteristics of Transformer Type Superconducting Fault Current Limiter

Abstract: Various types of fault current limiters have been proposed to reduce the fault currents in power transmission lines. The transformer type superconducting fault current limiter is one of the fault current limiters, and has many advantages such as design flexibility. By using an experimental fault current limiter, the short-circuit fault test was carried out for different fault phase angles. From the results of the experiments, it is confirmed that the transmission line fault current is seriously affected by the magnetic saturation of the transformer core. This has to be considered in the design of the transformer. Thus, in this paper, the transient characteristics of the transformer type super-conducting fault current limiter are analyzed by the numerical simulation considering the magnetic saturation of the transformer iron core and the time-dependent resistance of the current limiting device. The analysis is carried out by using the parameters obtained from the experimental superconducting fault current limiter. From the results of the analyses, the influence of the transformer core is clarified

Complex superconducting fault current limiter

Abstract: The present invention relates to a complex superconducting fault current limiter which adds a current limiting reactor to a superconductor to protect the power line from a fault current, and more particularly, to a complex superconducting fault current limiter using a minimum number of superconducting fault current limiters, while avoiding series and parallel connections of a plurality of superconductors and coils, in order to economically manufacture the fault current limiter in a small size. A superconductor, a high speed switch, and a circuit breaker are connected in series to each other, and a first reactor with a low impedance and a second reactor with a high impedance are connected in parallel to the power line so as to provide a branch circuit for the current to the series circuit. A semiconductor switch is connected in parallel to the second reactor with a high impedance in accordance with the opening high speed switch. A circuit is breaker trip drive controller is configured so as to be connected to the superconductor and the branch circuit, and when a fault current occurs, the fault current is branched into the branch circuit, so that the second reactor limits the fault current. When a fault current occurs, the circuit breaker trip drive controller provides a trip drive signal to the circuit breaker for tripping in accordance with the voltage of the superconductor or the current of the branch circuit.

Operation characteristics of emitter turn-off thyristor (ETO) for solid-state circuit breaker and fault current limiter

Abstract: Solid-state circuit breakers and current limiter can provide significant advantages in speed, lifetime and functionality compared to electromechanical switchgear used in distribution systems. The paper presents the operation characteristics of emerging ETO semiconductor power switch during turn-off transient. The gate commutating rate at turn-off, dI/sub G//dt, is improved to as higher as 12kA//spl mu/s. Experimental results demonstrates that a 75 mm ETO can safety interrupt 8kA current instead of 3 kA in GTO mode. Moreover, thanks to the built-in current sensor and the self-power generation for the gate driver, ETO will largely lower the cost of whole system. This device is suitable for solid-state circuit breaker and fault current limiter with its very fast switching speed, high current interruption capability, low conduction loss and compact structure.

Test of Resonance-Type Superconducting Fault Current Limiter

Abstract: A resonance-type superconducting fault current limiter (FCL) using Bi-2223 superconducting coils was developed and tested in order to demonstrate its actual operation. Over-current tests of the FCL were carried out for 50 Hz steady-state current of up to 120 A with relevant combinations of a superconducting reactor, an arrester, a capacitance and a copper reactor. The test results showed that the currents during faults were controlled within low levels. It was also demonstrated that the FCL could promptly recover to the steady state after the faults were cleared

Active superconducting DC fault current limiter based on flux compensation

Abstract: With the extensive application of DC power systems, suppression of DC fault current is an important subject that guarantees system security. This paper presents an active superconducting DC fault current limiter (DC-SFCL) based on flux compensation. The DC-SFCL is composed of two superconducting windings wound on a single iron core, the primary winding is in series with DC power system, and the second winding is connected with AC power system through a PWM converter. In normal operating state, the flux in the iron core is compensated to zero, and the SFCL has no influence on DC power system. In the case of DC system accident, through regulating the active power exchange between the SFCL’s second winding and the AC power system, the current on the DC side can be limited to different level complying with the system demand. Moreover, the PWM converter that interface the DC system and AC system can be controlled as a reactive power source to supply voltage support for the AC side, which has little influence on the performance of SFCL. Using MATLAB SIMULINK, the mathematic model of the DC-SFCL is created, simulation results validate the dynamics of system, and the performance of DC-SFCL is confirmed.

Comparative Study of Transformer-Type Superconducting Fault Current Limiters Considering Magnetic Saturation of Iron Core

Abstract: The paper reports on the transient performances of the transformer type superconducting fault current limiter (SCFCL). This type of fault current limiters (FCL) consists of a transformer in series with the transmission line and a superconducting current limiting device connected to the transformer. The performances are analysed through simulation during a short-circuit fault in the presence and absence of the shunt inductor. Magnetic saturation of the transformer iron core was compared to clarify its influence on current limiting characteristics of these SCFCLs. The magnetization curve of the transformer core is expressed by Froehlich's formula and the time dependence of resistance R(t) of the current limiting device during its S-N transition (transition from superconducting to normal-conducting state) is considered. It was shown that magnetic saturation deteriorates the current limiting characteristics of this FCL.

Design and Test Results of 66 kV High-Tc Superconducting Fault Current Limiter Magnet

Abstract: This paper describes the design of a 66 kV high-Tc superconducting fault current limiter (FCL) magnet and the test results obtained. The magnet mainly consists of a vacuum vessel, a nitrogen bath, a pair of current leads, cryocoolers, and six sets of coils wound with Bi2223 tape. The rated current is 750 A. The insulation voltage of the magnet is of the 66 kV class. In the final year of the project, all six sets of the coils are set connected in the cryostat and evaluation tests have been implemented. In the cooling test, sub-cooled nitrogen of 65 K was obtained, with homogenous temperature distribution in the cryogen. The rated current of 750 A was successfully obtained for both direct and alternating current tests. In addition, the magnet passed the simultaneous current and voltage application test. The dielectric test results showed that the magnet satisfied the insulation for 66 kV apparatus in the Japanese Electrotechnical Committee Standard. Finally, the magnet was combined with a rectifier bridge circuit to form an FCL. In a fault current limiting test with a short-circuit generator, the FCL successfully limited short circuit current up to 20 kV applied voltage. The obtained result was in good agreement with the design and the Electro-Magnetic Transients Program (EMTP) analysis

Fault Current Limiting Characteristics of DC Dual Reactor Type SFCL Using Switching Operation of HTSC Elements

Abstract: The fault current limiting characteristics of DC dual reactor type superconducting fault current limiter (SFCL) using switching operation of high-TC superconducting (HTSC) elements were analyzed. The suggested SFCL consists of a diode bridge, DC dual reactor with magnetic coupling and HTSC elements. Unlike the conventional bridge type SFCL, which requires the controller for the operation of the interrupter to prevent the continuous increase of fault current after a fault happens, this SFCL can be operated without the interrupter and the controller for its operation. In addition, despite different critical currents after a fault accident, the balanced power burden between HTSC elements can be achieved by the magnetic coupling between two coils of DC dual reactor. It was confirmed through the experiments for the fault current limiting characteristics that the suggested SFCL performed the advantageous current limiting operations compared to the conventional bridge type SFCL using HTSC coil

Design and Construction of a Magnetic Fault Current Limiter

Abstract: A fault current limiter using permanent magnets has been designed and its performance simulated using a two-dimensional time-stepping finite-element method incorporating a model of hysteresis for hard magnetic materials.

Investigation on the Thermal Behavior of HTS Power Cable Under Fault Current

Abstract: During the operation of HTS power cable, large fault current can be introduced to a HTS power cable due to several accidents. In this case, a circuit breaker limits the fault current to protect the HTS power cable just as conventional power cables. However, heat is necessarily generated until the circuit breaker operates and severe performance degradation or even burn-out can occur at HTS tapes. To ensure the safety against the fault current, thermal characteristic of the HTS power cable should be verified under the fault current. Several experiments with a simple cable are performed using an AC pulse power supply. During the experiment, the increase of temperature and current redistribution are measured for the various fault current conditions. Through the experiments, safety margin of Korean HTS power cable is verified and the allowable peak current is suggested

A novel IGCT-based Half-controlled Bridge Type Fault Current Limiter

Abstract: A novel IGCT-based half-controlled bridge-type Fault Current Limiter is proposed in this paper By substituting the half-controllable SCR in the rectifier bridge with self-turn-off device IGCT, the uncontrolled time of the Converter Bridge can be reduced from half a cycle to the delay time of the current measuring circuit If the maximum current in the dc reactor is preset, the inductance, volume, weight and cost of the DC reactor can be reduced to one 32th of what it is in the SCR-based bridge type FCL in three phase power systems approximately The magnetization time of the DC reactor is reduced The control method is very simple The dynamic performance of the proposal FCL can be improved Topology and control strategies of the proposal FCL are described in detail Simulations under each short circuit fault mode are carried out An experimental model is constituted and tested Simulation and experiment results proved the practicability and validity of the new FCL

A New Topology of Fault-current Limiter and its control strategy

Abstract: In this paper a new type of fault current limiter based on DC reactor with using superconductor are presented. In normal operation condition the limiter has no obvious effect on loads. When fault happens, the bypass AC reactor and series resistor will insert the fault line automatically to limit the short circuit current, when the control circuit detects a short circuit fault, the solid state bridge in fault line works as an inverter and is closed as soon as possible. Subsequently the fault current is fully limited by the bypass AC reactor and series resistor. The magnitude of Lac and rac must be equal with protected load. By using the Electro-Magnetic Transients in DC systems which are the simulator of electric networks (EMTDC) software we carried out analysis of the voltage and current waveforms for fault conditions. Waveforms are considered in calculating the voltage drop at substation during the fault. The analysis used in selecting an appropriate inductance value for designing.