578 results about "Fault current limiter" patented technology

A device and method for making a persistent joint allowing end terminations of superconducting MgB₂ wire to be joined with a superconducting bridge. Superconducting electromagnetic coils may be joined in series or joining of coil assemblies to current sources and the two ends of a persistent switch. The device includes wire filaments with end preparation exposing reacted MgB₂, inserted into a block and surrounded with Mg+B and/or MgB₂ in powder, solid, slurry or sol-gel form and subsequently reacted to establish a bridge of superconducting MgB₂ electrically connecting the superconducting MgB₂ wires. Autonomous operation of the superconducting background magnet coils in magnetic resonance imaging (MRI) and nuclear magnetic resonance (NMR) devices are allowed, or similar devices where autonomous operation of an MgB₂ based superconducting magnet is required. The low resistant joint will also be beneficial for other superconducting applications such as fault current limiters, motors, generators, etc.

The invention concerns a semi-conductor device comprising on a substrate:a first dynamic threshold voltage MOS transistor (10), with a gate (116), and a channel (111) of a first conductivity type, anda current limiter means (20) connected between the gate and the channel of said first transistor.In accordance with the invention, this first transistor is fitted with a first doped zone (160) of the first conductivity type, connected to the channel, and the current limiter means comprises a second doped zone (124) of a second conductivity type, placed against the first doped zone and electrically connected to the first zone by an ohmic connection.Application to the manufacture of CMOS circuits.

A fault current limiter system including a fault current limiter and a variable shunt current splitting device. The current splitting device includes first and second conductive windings, wherein the first conductive winding is connected in parallel with the fault current limiter and is configured to carry current in a first direction. The second conductive winding is electrically connected in series with the fault current limiter and is configured to carry current in a second direction opposite to the first direction so that the reactance of the first winding is negated by the reactance of the second winding during steady state operation of the fault current limiter system. Thus, a first portion of a steady state current is conveyed through the fault current limiter and a second portion of the current is conveyed through the current splitting device. The steady state current load, on the fault current limiter is thereby reduced.

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.

A superconducting short circuit current limiter (40a) for an alternating current system includes AC reactors having superconducting direct current bias windings (4a, 4b) that at normal conditions maintain the reactor's cores in saturated state. There are at least two AC coils (3a, 3b) for each phase operating at opposite half periods or at both half periods. The reactor may also have an additional feedback coil (42a, 42b) that at least partly compensates for the bias field of the superconducting coil at fault conditions enhancing a limiting capacity of the reactor. The reactor's core can be configured for decreasing its dimensions and mass as compared with known devices and for decreasing core losses. High voltage/high current devices include several standard modules connected in series or/and in parallel. A positional relationship of the modules is defined for decreasing necessary numbers of Amp?re-turns of superconducting and non-superconducting coils.

The invention relates to a fault current limiter on the basis of a combined rapid switch-on switch. The combined rapid switch-on switch is firstly connected in parallel with a capacitor C and then is connected in series with a conventional reactor L; the combined rapid switch-on switch is formed by combining a tight coupling double-winding reactor and a rapid switch-on switch, of which dotted terminals are opposite; a first winding L1 of the tight coupling double-winding reactor is firstly connected in series with the rapid switch-on switch and then is connected in parallel with a second winding L2; the rapid switch-on switch is formed by connecting one group or a plurality of groups of mechanical switches K, transistors T, controllable trigger gaps G and lightning arresters MOV in parallel; and in the case of a short circuit fault, switch-on on the first winding L1 of the tight coupling double-winding reactor can be implemented by selecting the rapid switch-on switch with tolerance to a low short circuit current. After the first winding L is conducted, reactances generated by the first winding L1 and the second winding L2 of the tight coupling double-winding reactor are balanced out mutually, so that the reactances are reduced.

A fault current limiter (FCL) for limiting a fault current in a power line during a fault condition. The FCL includes a magnetic coupling circuit for monitoring current in the power line through magnetic coupling; a sensing circuit for sensing the current in the power line and providing a signal indicative of the sensed current; a control circuit receiving the signal indicative of the sensed current in the power line and determining whether the sensed current indicates that the fault condition exists; and high and low impedance paths that are connected in parallel. The high impedance path includes a discharging impedance circuit for limiting the fault current. The low impedance path includes a reactor circuit and a switching unit having an ON state for conducting current through the low impedance path and an OFF state for conducting current through the high impedance path.

In the present invention, a current vector control unit, which separately controls a d-axis current and a q-axis current that are obtained from a current of an electric motor by means of orthogonal transformation according to a target command value, is provided, and a drive unit drives the electric motor. Furthermore, a phase angle command generation unit generates a phase angle command ([beta]*) on the basis of the difference ([increment]v*) between the absolute value (|v*|) of a voltage command from the current vector control unit to the drive unit and a predetermined reference value (Vlmt). A d-axis current command generation unit generates a d-axis current command (id*) on the basis of the sine value of the phase angle command ([beta]*). A q-axis current limiter sets a limit value for a q-axis current command (iq*) on the basis of the cosine value of the phase angle command ([beta]*). Due to this configuration, voltage saturation is eliminated, and the electric motor is highly stably driven while producing a high output even when a target command value in access of the possible output limit of the electric motor is input when the voltage is nearly saturated.

A superconducting electrical cable system is configured to be included within a utility power grid having a known fault current level. The superconducting electrical cable system includes a non-superconducting electrical path interconnected between a first node and a second node of the utility power grid. A superconducting electrical path is interconnected between the first node and the second node of the utility power grid. The superconducting electrical path and the non-superconducting electrical path are electrically connected in parallel, and the superconducting electrical path has a lower series impedance than the non-superconducting electrical path when the superconducting electrical path is operated below a critical current level and a critical temperature. The superconducting electrical path is configured to have a series impedance that is at least N times the series impedance of the non-superconducting electrical path when the superconducting electrical path is operated at or above one or more of the critical current level and the superconductor critical temperature. N is greater than 1 and is selected to attenuate, in conjunction with an impedance of the non-superconducting electrical path, the known fault current level by at least 10%.

The invention relates to an alternating current high-voltage vacuum circuit breaker, which is characterized in that the invention comprises a case body, a vacuum arc extinguish chamber is seated and connected to the case body, an electromagnetic repulsive force mechanism is disposed in the case body, the mechanism comprises an open coil and a close coil which form a fixed gap, a repulsion disk arranged in the gap, a repulsion rod which is fixedly penetrated by the equipped repulsion disk, a retention capacity rod of a composite disc spring retention force structure connected with the lower end of the repulsion rod, a catch spring fixed on the retention force rod and at least two pieces of disc springs top-arranged on the catch spring. The upper end of the electromagnetic repulsive force is connected with a closing buffer gear which comprises a spring frame structure and a hydraulic cylinder, further, the closing buffer gear comprises an intelligent pulse generator. Because the invention employs the electromagnetic repulsive force mechanism, employs bi-stable composite disc springs to retain, employs the closing hydraulic pressure buffer gear to inhibit closing bouncing, and employs a photoelectric sensor to realize position returning, thereby belonging to the advanced design at home and abroad, therefore, the invention can be widely applied to the field of fault current limiters, phase selection switches, solid change-over switches and the like.

An LED lighting circuit mounted in a lighting device having LEDs as a light source, the circuit including:

• • a light emitting unit that includes a plurality of LED circuits for supplying drive currents to a plurality of LEDs connected in series or parallel;
  • a failure detection unit that detects whether each of the drive currents flowing through the plurality of LED circuits is equal to or larger than a predetermined fault current value for those LED circuits as a whole; and
  • a failure alert unit that performs a predetermined alert operation if the failure alert unit detects that at least one of the drive currents is equal to or larger than the predetermined fault current value.

A modular and scalable Matrix-type Fault Current Limiter (MFCL) that functions as a “variable impedance” device in an electric power network, using components made of superconducting and non-superconducting electrically conductive materials. An inductor is connected in series with the trigger superconductor in the trigger matrix and physically surrounds the superconductor. The current surge during a fault will generate a trigger magnetic field in the series inductor to cause fast and uniform quenching of the trigger superconductor to significantly reduce burnout risk due to superconductor material non-uniformity.

A fault current limiter based on a fast switch and a triggered vacuum switch is disclosed, which comprises a fast switch (1) and a current limiting resistor (2) which are connected in parallel, wherein, a first pulse capacitor (3), a first inductor (4) and a first triggered vacuum switch (5) are connected in series between two ends of the fast switch (1); a second pulse capacitor (6), a second inductor (7) and a second triggered vacuum switch (8) are connected in series between two ends of the current limiting resistor (2). The invention: 1) enables short circuit current to be incapable of reaching a first current peak value in a state of infinite current; 2) causes arc current of the fast switch to achieve fast zero crossing and then arc blowout; 3) can pass through large pulse current at high triggering speed and can achieve arc blowout at the time of the zero crossing of the pulse current; 4) can rapidly inhibit the short circuit current; 5) and automatically limits current subsequent to the short circuit of a system to ensure quality of power supply and save establishment expenditure of network.

A three-phase current limiter (30) for an alternating current system includes an AC magnetic circuit having at least one AC coil (35R1, 35S1, 35T1) for each phase of a 3-phase AC supply wound on a saturable ferromagnetic core and configured to subject respective AC coils for each phase to a common magnetic flux, and a DC magnetic circuit (34a, 34b) for biasing the AC magnetic circuit into saturation at normal conditions. In use the AC coils are connected in series with a load and during alternate half cycles of the AC supply at least one of the AC coils produces a magnetic field that opposes a magnetic field of the DC magnetic circuit. The AC coils (35R, 35S, 35T) for each phase are configured so that at least one of the AC coils exhibits unbalanced magnetic impedance relative to remaining ones of the AC coils for each phase.

A current limiting device (30, 40, 50, 60) comprising for each phase of an AC supply a closed magnetic core (31) of reduced volume and mass having first and second pairs of opposing limbs (32a, 32b; 33a, 33b), and at least one AC coil (35a, 35b) enclosing opposing limbs (33a, 33b) of the magnetic core (31) and adapted for series connection with a load. A superconducting DC bias coil (34) encloses a limb) (32a, 32b) of the magnetic core (31) for saturating each of the opposing limbs (33a, 33b) in opposite directions by the bias coil (34). Under fault conditions, the AC flux in at least one limb counteracts the DC bias flux, bringing the limb out of saturation. Preferably, current is reduced in the DC bias coils thus bringing both opposing limbs of the core out of saturation.

The invention relates to a microgrid transient performance intensification device and method based on cooperative control of fault current limit and quick energy storage. The method comprises the following steps: a current limiter and a quick energy storage device are cooperatively controlled to promote fault crossing capability of a microgrid under some conditions, considering the difference among fault positions and interaction needs of a high penetration power when the microgrid encounters an external short circuit fault; the fault current limiter and the quick energy storage device are cooperatively controlled to ensure that the microgrid realizes smooth transition between a grid-connected mode and an island mode when such special conditions occur that as a microgrid link circuit is in short circuit, the microgrid must be disconnected from the main grid. The microgrid transient performance intensification device exerts positive effect on suppressing the microgrid power fluctuation and promoting electric energy quality so as to improve resistance capability of the microgrid to an external short circuit fault, and ensure the operation reliability of the microgrid.

This invention relates to a current limiter of short-circuit fault, which applies the mutual inductance theory of magnets and the impedance variance property of superconductive materials in the fault limit composed of a superconductive faulty limiter and a mutual inductor, a winding of which is serial to a superconductive fault limiter then parallel to another winding to adjust mutual inductance and limit fault current by the property that the impedance of the superconductive limiter varies along with the change of current.

The invention discloses an optimal configuration method for fault current limiters. An area with high risk of failure in simultaneous phase commutation is judged by using a multi-infeed DC interactionfactor. During the configuration of an SRFCL device, the average electrical distance from a current limiting node to the DC converter stations in the area with high risk of failure in simultaneous phase commutation is calculated, and the priority of the current limiting node is determined to avoid large-range search. Meanwhile, the suppression effect of SRFCL on DC commutation failure is considered. Therefore, an SRFCL optimal configuration scheme taking both short-circuit current limiting and commutation failure suppressing into account is realized. The method is helpful for power system planners to grasp the influence of SRFCL installation and configuration on the phase commutation failure of a multi-infeed DC system and visually determine an SRFCL installation area. The indexes in thearea can be displayed in order during calculation. The method is easy to implement. Decision support is provided for the optimal configuration method of SRFCL in the multi-infeed DC system.

A current limiting controller (100) for a light emitting diode (LED) driver automatically resets the LED driver to normal operation after elimination of a fault. The current limiting controller (100) includes a fault detector to detect a fault across a load (20, 40) that is being driven by the driver circuit (10, 30); a current limiter (130, 230) to limit the current supplied from the driver circuit (10, 30) to the load (20, 40) in response to the detected fault; and a reset circuit (120, 220, 320) to disable the current limiter (130, 230) upon expiration of a first time interval after the fault is detected, and to allow the current limiter (130, 230) again to limit the current supplied from the driver circuit (10, 30) to the load (20, 40) when the detected fault remains after a second time interval.

A liquid nitrogen low-temperature system for a superconducting current limiter belongs to the field of low-temperature engineering and technique. The liquid nitrogen low-temperature system comprises a liquid nitrogen container, a liquid nitrogen valve, a liquid nitrogen refuel valve, a safety valve, a valve cap, a test Dewar, a thermal insulation layer, a rupture disk, a deflation valve, a flow meter, a vacuum measurement gauge, a pressure difference sensor, a pressure sensor, a support part, a pumping valve, a vacuum pump, a superconducting current limiter, a control circuit, a temperature sensor and a discharging air pipe. In the invention, the system adopts the liquid nitrogen as the cooling working medium; the superconducting current limiter for the test is placed in the test Dewar; switching between the superconducting state and superconducting loss state of the superconducting current limiter can be realized through the control circuit; and the pressure, pressure difference and temperature measured by the pressure sensor, the pressure difference sensor and the temperature sensor, and the quality flow of the gasified nitrogen in the superconducting loss state measured by the flow meter are inputted into a computer, so as to evaluate the refrigeration wastage of the low-temperature system of the superconducting current limiter, and study the influence of the bubbles exerted on the low-temperature system pressure intensity when superconducting current limiter is abnormal. The low-temperature system has the advantages of simple structure, good economical efficiency, and favorable safety.

The invention relates to a ship electricity fault current restrictor comprising a ship electricity system and a fault current restrictor. The ship electricity system comprises a power supply end and a load which are electrically connected with each other; and the fault current restrictor is a judging-type impedance device which is electrically connected with a patch from the power supply end to the load and can judge the fault current. A low-impedance state is presented if no fault current occurs and a high-impedance state is presented if the fault current is detected so as to restrict the fault current to pass through.

The invention discloses a current limiting type UPFC system design method. The two sides of a current limiting type UPFC system are connected to the same alternating-current bus power source, the parallel connection side is connected with a power system through a parallel transformer Tsh, the series connection side of the current limiting type UPFC system and a current limiter are connected together through the secondary side of a series transformer Tse, and connected to the power system through the primary side of the series transformer Tse, the series connection side and the parallel connection side of the UPFC system are connected through a direct-current capacitor C, and an outlet of a series connection side filter inductor of the UPFC system is connected with a capacitor overvoltage protection circuit in parallel. The current limiter comprises a half-controlled rectifier bridge composed of six thyristors, and a follow current bridge composed of two thyristors, wherein the follow current bridge is connected with a current-limiting inductor in parallel; the parallel connection side of the UPFC system is connected with the parallel transformer Tsh through a parallel connection side filter inductor.