184 results about "Fault current limiting" patented technology

The invention discloses a novel electric power electric transformer. The electric power electric transformer consists of a high-voltage level, an isolation level and a low-voltage level, wherein the high-voltage level comprises 2*N*n half-bridge topology first power modules; the isolation level consists of N1 second level power modules, and each second power module comprises a medium high frequency wave chopper part, a medium high frequency transformer part and a medium high frequency synchronous rectifier part; and the low-voltage level consists of N2 level third power modules. The electric power electric transformer skillfully utilizes the prior half-bridge topology structure technique, better solves the problems of low operating efficiency, voltage resistance and voltage sharing of switch devices on the input side and big volume of an input filter existing in the common electric power electric transformer, and simultaneously realizes reactive power control of the high-voltage level and the low-voltage level, quality control of electric energy and limitation of failure current, improves the practicability of the device and quickens commercialization of the electric power electric transformer.

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.

The invention discloses a control method and device for an alternating-current solid-state power controller with a current limiting function. Through control over a first power tube and a second power tube of a main branch circuit and a third power tube and a fourth power tube of a current limiting branch circuit, when loads are normally started, natural zero-voltage turn-on and natural zero-current turnoff of the alternating-current solid-state power controller are achieved within a half of power source period, when large-capacity capacitive loads or rectifier bridge loads with large-capacity filtering capacitance are started, current-limiting charging is firstly performed through the current-limiting branch circuit, and then the alternating-current solid-state power controlled is completely turned on; when a short circuit fault happens on the alternating-current solid-state power controller, the main branch circuit is firstly turned off to perform fault current limiting, and then the alternating-current solid-state power controller is turned off. Natural zero-voltage on-off of the alternating-current SSPC is achieved within the half of the power source period, besides, the control method and device have a high-power current-limiting function, capacity for carrying the capacitive loads and the rectifier bridge loads of the alternating-current SSPC is improved, and anti-interference capacity of short circuit protection of the alternating-current SSPC is improved.

The invention discloses a standardized current conversion device applicable to an electric vehicle and a distributed power source to be accessed to a public power distribution network. The traditional distributed power source can not be effectively isolated from the power network, the requirements of high-end users for power quality can not be ensured, and power users with severe pollution can not be prevented from injecting power into the power network. The standardized current conversion device comprises a power network side module, a user side module, an electric vehicle charging and discharging module and a controller, wherein the network side module is connected with the electric vehicle charging and discharging module in parallel and then is connected with the power network side module in series; a trigger pulse signal generated by the controller is transmitted to the power network side module, the user side power module and the electric vehicle charging and discharging module through optical fibers, the controller communicates with a background server through Ethernet, and a background monitoring software module is installed in the background server. The invention can realize the effective isolation of the distributed power source and the power network and can also combines the functions of dynamic reactive compensation, fault current limitation, power quality control and the like.

The invention relates to a reactor type short-circuit fault current limiter, which consists of reactors, a capacitor, a switch and lightning arresters. During the stable state of an electric grid, the current limiter works at a series resonance or series compensation status and is of low impedance; and after the electric grid is subjected to short-circuit fault, windings of the reactors are saturated due to overcurrent, or meanwhile, the change of the reactance of the reactors is controlled through closing the switch, so that the current limiter generates high impedance to realize fault current limiting. According to the current limiter, the automatic fault response is realized through the saturation of the reactors, and the current-limiting capacity is improved through circuit resonance; meanwhile, the manufacture cost of a system can be greatly lowered through the reasonable design of a current limiter structure; and the current limiter is strong in current-limiting capacity and has little influence on the electric grid, and the safety and the reliability of the operation of the electric grid are effectively improved.

The invention discloses a novel power quality control system with a fault current-limiting function and a control method thereof. The novel power quality control system with the fault current-limiting function comprises a three-phase H-leg PWM rectifier, a three-phase four-leg series converter, a thyristor controlled short-circuit branch, a thyristor controlled bypass reactance branch and a corresponding control method. The PWM rectifier and the three-phase four-leg series converter share one direct current side to achieve bidirectional energy conversion, the series converter compensates the fall, the raising and three-phase imbalance of the grid voltage and solves the quality problem of the harmonic voltage, at the same time, the system controls the series converter, the thyristor controlled short-circuit branch and the thyristor controlled bypass reactance branch to limit the current when various short-circuit faults occur on the grid, and thus the purposes of stabilizing the loaded supply voltage, improving power supply quality, protecting the grid and load equipment when short-circuit faults occur and improving the safety and stability of the electric power system are achieved.

The invention discloses a novel multifunctional fault current limiting system based on an optical storage technology and a control method thereof. The novel multifunctional fault current limiting system mainly comprises a photovoltaic power generation part, a storage battery energy storage part, a PWM converter and a fault current limiting part. The photovoltaic power generation part, the storage battery energy storage part and the PWM converter share a DC bus, and energy is exchanged among the photovoltaic power generation part, the storage battery energy storage part and the PWM converter. When the voltage quality problems of falling, rising and three-phase imbalance happen to the voltage of a power grid, compensating voltages are provided for the power grid through the PWM converter. Meanwhile, when short circuit faults of different types happen to the power grid, the system intrudes inductance into the system for current limiting by controlling the fault current limiting part. The novel multifunctional current fault current limiting system based on the optical storage technology and the control method thereof can achieve the purposes of stabilizing the load power supply voltage, improving the power supply quality and limiting short circuit currents through solar energy resources.

A fault current limiter for limiting current faults in an electrical network comprising: a series of phase coils located adjacent a superconductive coil for fault current limiting phase faults within the network; a series of neutral coils located adjacent the superconductive coil for fault current limiting neutral earthing faults in the electrical network.

The invention discloses a YBCO high-temperature superconducting strip-based short circuit fault current limiter. The direct current end of a diode rectifier bridge of a current limiter is connected in parallel with a current limiting coil; and the current limiting coil is formed by winding a YBCO high-temperature superconducting strip. The current limiting coil has the characteristic of a direct current reactor. When a power grid is in a steady state, the current limiter has no influence on the power grid. Once a short circuit fault happens, when a fault current passes through the current limiting coil, the YBCO high-temperature superconducting strip quenches to generate resistance to realize fault current limiting. The superconducting current limiter of the invention can realize automatic fault triggering and automatic current limiting, and can automatically generate current limiting impedance with different intensities according to the intensities of the fault current. The current limiter has strong current limiting capability and little influence on the steady state of the power grid.

The present invention provides a fault detection system and a detection method for a quench-type superconducting fault current limiter. The present invention is characterized in that the present invention consists of a full wave rectification module, a logic circuit module, an analog-digital conversion module, a superconducting control switch module and a current rate detecting module. The working method of the present invention is as follows: (1) signal collection, (2) signal treatment and transmission, (3) analog-digital conversion and output, (4) current limiter operation determination. The present invention has the advantages that as follows: 1. a hardware apparatus is combined with a computer software programming; the hardware apparatus is of simple design and the software programming is easy to be understood; 2. a di/dt fault current rate is adopted to control the operation of the superconducting fault current limiter, which avoids the incorrect operation under the traditional control method; 3. the analog-digital conversion module is cooperated with the logic circuit, so the operation of the superconducting fault current limiter is more accurate and reliable; 4. the data calculation and data processing ability with high speed of the computer is used, so the reliability of the control system is greatly improved.

The invention discloses a fault limit flow method which is based on the rectification bridge and the double throw switch swithing, used bidirectional and unidirectional controllable electronic switching, composed a bridge path, in the electrical power system normal situation, controlled the bridge path work to no control rectification condition, once short-circuited fault occurrence, controlled the bridge path work immediately to two double throw switches conditions, would used for the current limiting super conductivity reactor or the conventional reactor string enters the exchange power supply system, limited the steady state value of the short-circuit current. At the same time, also discloses the fault current limiting equipment based on this method. This invention method and equipment apply to the alternating voltage power supply system, not only the initial period short-circuit current climbing rate of limiting short-circuit fault, also can limit short-circuit steady state value of occurring the short-circuit fault.

The invention discloses a cascaded converter-based multifunctional high-speed switch device which structurally comprises a main switch module, an auxiliary switch K1, an auxiliary switch K2 and an auxiliary switch K3; the main switch module is connected with a power source by the auxiliary switch K1 and is connected with a load by the auxiliary switch K3, and the main switch module is connected with the auxiliary switch K1 and the auxiliary switch K3 with each other in series and is connected with the auxiliary switch K2 in parallel with each other; and the main switch module comprises a cascaded H bridge converter and a wave filtering link, an output end of the cascaded H bridge converter is connected with the wave filtering link, and the cascaded H bridge converter comprises n H bridge converter cascaded units which are connected with one another in series. The cascaded converter-based multifunctional high-speed switch device is flexibly applicable to various connection modes between the power source and the load, has various functions of superspeed switching, voltage compensating, fault current limiting and the like, and is applicable to the middle and high voltage occasion due to a cascaded structure.

A hybrid direct-current current-limiting breaker comprises a rapid mechanical switch B, an IGBT module G, a thyristor module T1, a thyristor module T2, a current limiter FCL, an inductor L1, a capacitor C1 and a lightning arrester MOV. The rapid mechanical switch B is connected between a connecting point 1 and a connecting point 5, the IGBT module G is connected between a connecting point 2 and the connecting point 5, the rapid mechanical switch B is connected with the IGBT module G in series, the thyristor module T2 is connected between the connecting point 1 and the connecting point 2, both the thyristor module T1 and the current limiter FCL are connected between the connecting point 2 and a connecting point 3, and the thyristor module T1 is connected with the current limiter FCL in parallel; and the capacitor C1 is connected between the connecting point 1 and a connecting point 4, the inductor L1 is connected between the connecting point 3 and a connecting point 4, the capacitor and the inductor are connected in series, and the lightning arrester MOV is connected between the connecting point 1 and the connecting point 3. During stable operation of a power grid, the breaker presents low impedance, and influence on the power grid is small; and when a fault occurs in a direct current transmission line, fault current limiting and cutoff of the faulty line can be rapidly realized.

[Problem] To prepare a superconducting fault-current limiting element having a high sharing electric field at low cost.

[Means for Resolution] A superconducting fault-current limiting element including an insulator substrate; a superconductive thin film 3 formed on the insulator substrate; and an alloy layer 4 formed on the superconducting thin film 3, said alloy layer having a room-temperature resistivity higher by twice or more than the room-temperature resistivity of a pure metal, in which, when the superconducting thin film 3 goes into a normal conductive state by an overcurrent, the overcurrent flowing through the superconducting thin film 3 is transferred only to the alloy layer 4.

The present invention relates to a doubly-fed wind generator system based on fault current-limiting control and a low voltage ride through method which aim to solve the problems that the current change amplitude is large, a low voltage ride through effect is poor, and the normal operation of the system after voltage recovery is not conducive when the conventional doubly-fed wind generator system carries out the low voltage ride through. The doubly-fed wind generator system based on the fault current-limiting control comprises a doubly-fed wind generator fault current limiter, the fault current limiter is arranged between an equivalent power grid and a doubly-fed wind generator stator and comprises a rectifier bridge circuit and a sectionalized switching circuit, and the rectifier bridge circuit comprises a first bridge arm, a second bridge arm and a third bridge arm. The equivalent power grid is connected with the midpoint of the first bridge arm, the midpoint of the third bridge arm is connected with a doubly-fed wind generator, and the sectionalized switching circuit is connected between the midpoint of the first bridge arm and the midpoint of the third bridge arm. According to the present invention, the fault current limiter possesses a better low voltage ride through performance.

The invention relates to a wind power station LVRT (Low Voltage Ride Through) device which comprises a wind power station, electric reactors, diodes, adjustable voltage sources, a circuit breaker and a grid system. One adjustable voltage source is connected in parallel with one diode after being connected in series with one electric reactor to form one group of fault current limiting circuit; and after two groups of fault current limiting circuits are connected in series, one end of the obtained circuit is connected with the wind power station and the other end of the obtained circuit is connected with the grid system by the current breaker. The wind power station LVRT device is low in cost and easy to implement. When the LVRT function is implemented, the short current limiting capacity is improved; and by the non delay input of the current limiting electric reactors connected in series, the large-area talk around accident caused by the short circuit inside the wind power station can be avoided. The wind power station LVRT device has low requirement for the control characteristic of a unit plant; and a power electronic valve string of the wind power station LVRT device adopts a diode set string with low cost, large through-current capacity and strong short-time overload capacity, so that the system cost is reduced.

The present invention relates to a reclosing control system and method using a superconducting fault current limiter. The reclosing control system includes a superconducting fault current limiting device in which two circuits, each having a switch and a superconducting fault current limiter connected in series with each other, are connected in parallel with each other. A recloser is disposed between the superconducting fault current limiting device and a distribution line and is configured to control reclosing. The distribution line is connected to the recloser and is configured to transfer power to a load.

The proposed invention discloses a safe processing method for active voltage reduction of a ground fault phase of a non-effective ground system, for use in safe processing of a ground fault of a neutral point non-effective ground generator or distribution network. Non-effective ground system side windings of a transformer are equipped with a plurality of shunting taps. When a single-phase ground fault occurs, the shunting tap of the fault phase winding is selected to be short-circuited to ground directly or through an impedance to reduce the fault phase voltage to ensure that the fault point voltage is less than the continuous burning voltage of a ground arc to meet a long-term non-stop safe operation requirements. The proposed method can eliminate the instantaneous single-phase ground fault, suppress the permanent single-phase ground fault current, and limit the rising amplitude of non-fault phase voltage and the risk of non-fault phase insulation breakdown.

A fault current limiting system includes switching means for providing a fast switching operation; a parallel current path comprising a limiting fuse; and a switching system to automatically replace a blown set of fuses with an unblown set of fuses after a fault current limiting operation has occurred. A method of limiting fault current includes providing a fast switching operation; providing a parallel current path comprising a limiting fuse; and automatically replacing a blown set of fuses with an unblown set of fuses after a fault current limiting operation has occurred.

An isolation-type AC fault current limited circuit is a current regulation circuit including a transformer and a conduction circuit. The transformer includes a primary winding coupled in series between a power supply input system and a load output system, and a secondary winding sharing a common iron core with the primary winding and electrically isolated therewith. The conduction circuit is connected to the secondary winding and includes a switch and a breaking element coupled in series. In the event that short circuit takes place on the power system, the breaking element induces great short circuit current of the primary winding and is fused to cut off conduction, so that the transformer becomes an open circuit to increase magnetizing reactance with high impedance to increase equivalent internal impedance of the power supply input system to limit fault current and allow circuit breaking devices of the power system to isolate short circuit.

A fuel cell system includes a fuel cell having conductive coolant flowing there through and a high voltage direct current (HVDC) bus interconnected with the fuel cell. An active isolation circuit includes coolant fault current sensors that detect a fault current (also called residual current) in the coolant and generates a fault signal when the fault current is detected. A switching circuit compensates and redirects the fault current based on the fault signal, providing active fault current limitation thereby.