57results about How to "Inhibit short circuit current" patented technology

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.

The invention relates to a double-closed-loop control apparatus and control method of a three-phase PWM voltage type inverter, and belongs to the field of an inverter control technology. Through combination of fractional-order PI and prediction function control, a novel FOPI-PFC algorithm is obtained, conventional PI control is replaced, such a method is introduced to an inverter voltage and current double-closed-loop system to replace a conventional prediction controller or a PI controller which is used by a voltage external ring so as to improve the system dynamic response capability and the anti-disturbance capability, and on the basis of this, a new fractional-order parameter is introduced, such that control is more flexible; and furthermore, a discrete sliding mode current controller is taken as a current controller of an internal ring, such that a good dynamic response capability and stable output voltages can be obtained.

The invention discloses a multi-terminal offshore wind power flexible direct current and energy storage cooperative grid-connected system. The system comprises a plurality of offshore wind power clusters, a plurality of offshore converter stations connected in parallel, and land converter stations connected with the offshore converter stations. Each offshore converter station is directly connected with the output end of the corresponding offshore wind power cluster, and the direct current output ends of the offshore converter stations are connected in parallel; the land converter stations are connected to the AC main power grid; the energy storage subsystem is connected with the land converter station, comprises a plurality of energy storage units and is used for stabilizing offshore wind power output fluctuation; and the invention further discloses a corresponding control method. The branch type multi-terminal offshore wind power flexible direct-current power transmission subsystem integrates a plurality of dispersedly distributed offshore wind power clusters, shares a seabed transmission corridor and an onshore converter station, is connected with the energy storage subsystem at the onshore converter station, saves the seabed transmission corridor and landing point resources, reduces the network loss of a current collection system, smoothes the wind power output, and improving the flexibility, stability and reliability of offshore wind power generation.

The invention discloses a permanent magnet fault tolerant motor driving system. The system includes a permanent magnet fault tolerant motor, two sets of three-phase full-bridge driving circuits, two bidirectional thyristors, six fuses, and a separate 270V DC power source; the permanent magnet fault-tolerant motor comprises one set of armature ABC windings and one set of XYZ windings which are independent of each other, are symmetrical with respect to each other and are wound in a manner that each slot is wound with one phase of coils in a three-phase single-layer centralized mode; each set ofthree-phase full-bridge driving circuit is composed of six power switching tubes; the two sets of three-phase full-bridge driving circuits respectively control the ABC windings and XYZ windings of the permanent magnet fault-tolerant motor; when the system fails, a corresponding bidirectional thyristor is turned on, so that a half-bridge power conversion circuit with a neutral point is formed, andtherefore, the control of the fault-tolerant operation of the system is realized. The permanent magnet fault tolerant motor driving system of the invention has the advantages of magnetic isolation, physical isolation, thermal isolation, small cogging torque ripple, suppression of short-circuit current, and high fault tolerance, and can realize fault-tolerant operation under a condition that different electrical faults occur alone or simultaneously.

The invention discloses a DC bias type flux reverse permanent magnet motor, which comprises a permanent magnet stator and a salient pole iron core rotor. An independent air gap is formed between the permanent magnet stator and the salient pole iron core rotor; the permanent magnet type stator comprises a stator yoke part and a plurality of stator teeth, wherein the stator yoke part and the plurality of stator teeth form a plurality of stator slots; armature windings are placed in the stator slots; bias direct current is injected into the armature windings; a permanent magnet is arranged at theslot opening of each stator slot; the permanent magnets and the adjacent stator teeth form a pair of magnetic poles; and the number and the magnetizing modes of the permanent magnets at the slot openings of the stator slots are the same. Multi-harmonic simultaneous work of the stator armature windings can be achieved, motor magnetic field adjustment is achieved by controlling positive and negative injected direct currents, and the motor is quite suitable for high-power demand occasions such as wind power generation and electric vehicles.

The invention discloses a modular permanent magnet hub motor. The motor comprises a rotor and a stator. The motor is characterized in that the rotor comprises a rotor iron core and a permanent magnet;the stator comprises a stator core composed of at least two or more modular stator units; a magnetic bridge is formed between the adjacent modular stator units; the winding directions of armature windings on the adjacent modular stator units are opposite, and the armature windings belonging to the same phase have a 180-degree electrical angle difference in space. The modular permanent magnet hubmotor has the advantages that the magnetic bridge is arranged and the arrangement mode of the armature windings is improved to eliminate counter potential even harmonics of the armature windings, so that the output torque performance of the motor is improved; and auxiliary windings are arranged by utilizing a large-groove structure generated by the magnetic bridge, so that the torque and the powerdensity of the motor are further improved.

The invention discloses a low-voltage precharging system for a high-voltage variable frequency system, and a control method of the low-voltage precharging system. The low-voltage precharging system comprises a high-voltage power supply, a high-voltage switch, a transformer, a low-voltage power supply and a low-voltage precharging circuit, wherein an input end of the high-voltage switch receives the high-voltage power supply; a primary side of the transformer is connected with an output end of the high-voltage switch; a secondary side of the transformer is connected with the high-voltage variable frequency system; an input end of the low-voltage precharging circuit receives the low-voltage power supply; an output end of the low-voltage precharging circuit is connected with a low-voltage winding of the transformer; and the low-voltage precharging circuit comprises a precharging switch, a precharging resistor connected in series with the precharging switch, a maintaining resistor connected in series with the precharging resistor, and a bypass switch connected in parallel with the maintaining resistor. Compared with a high-voltage precharging circuit, the low-voltage precharging system can greatly lower the product cost; the space volume of the system can be reduced effectively; impact of short-circuit current on a power supply system can be limited; and the power consumption of the precharging resistor can be reduced effectively.

The invention provides a flexible direct current transmission system. The system comprises a transformer, a current converter and a coupling reactor, wherein the coupling reactor comprises an upper bridge arm coupling reactor and a lower bridge arm coupling reactor; the upper bridge arm coupling reactor and the lower bridge arm coupling reactor are connected through a connection of a same-polarityterminal and a different-polarity terminal; a connection point between the same-polarity terminal and the different-polarity terminal is a grid connection point; one end of the transformer is connected with an alternating-current power grid, and the other end is connected with the grid connection point; the current converter comprises three phase units; the phase units include an upper bridge armand a lower bridge arm; and the coupling reactor is connected between the upper bridge arm and the lower bridge arm.

A high-voltage high-capacity split reactance type current limiter adopts a three-phase independent structure. The single-phase split reactance type current limiter is composed of a single high-voltagesplit reactor and a single multi-break quick vacuum circuit breaker, and the multi-break quick vacuum circuit breaker is located on one arm of the split reactor. The high-voltage split reactor is composed of an inner reactor winding, an outer reactor winding and an insulating baffle. The inner reactor winding and the outer reactor winding are both of a multi-encapsulation parallel dry-type air-core reactor structure. The winding directions of the inner reactor winding and the outer reactor winding are opposite; the wire inlet ends at the bottom share one wiring terminal; the wire outlet endsat the top are mutually independent; and a wire outlet end (1) at the top of the inner reactor winding is arranged on the inner side of the inner reactor winding, a wire outlet end (2) at the top of the outer reactor winding is arranged on the outer side of the outer reactor winding, the inner reactor winding and the outer reactor winding are isolated by an insulating baffle, and the insulating baffle is higher than the inner reactor winding and the outer reactor winding.

The invention provides a bipolar flexible direct-current power transmission system and a converter station thereof and relates to the electric power technology field. When a direct current side of the bipolar flexible direct-current power transmission system generates a fault, a short circuit current can be restrained. The converter station used for the bipolar flexible direct-current power transmission system comprises a positive polarity conversion portion and a negative polarity conversion portion. The positive polarity conversion portion comprises a first converter. The negative polarity conversion portion comprises a second converter. The converter station comprises a current limiting module. The current limiting module comprises an electric reactor. The electric reactor is connected in series to a neutral bus.

A DC-DC converter includes a main reactor interposed in a main energization path extending from a DC voltage input terminal to a DC voltage output terminal, a first main switching element interposed into the main energization path so as to be on-off controlled so that current flowing across the main reactor is intermitted, a second main switching element forming a discharge loop discharging electrical energy stored in the main reactor to the DC voltage output terminal side, an auxiliary reactor interposed between the first main switching element and the main reactor in the main energization path, an auxiliary switching element discharging electrical energy via the main reactor to the DC voltage output terminal side, the electrical energy being stored in the auxiliary and main reactors, and diodes connected in reverse parallel with the first and second main switching elements and the auxiliary switching elements respectively.

In one embodiment, system for driving an electromagnetic appliance includes an electromagnetic appliance, a main-drive unit and a sub-drive unit. The electromagnetic appliance includes coils for n number of phases, the coils for each of the n phases being arranged in a pair and wound so as to be excited in a predetermined direction by being energized with opposite-phase currents. The main drive unit is connected to each of the coils and energizes the paired coils with opposite-phase currents. The sub-drive unit is provided parallel with the main-drive unit and is configured to suppress a short-circuit current occurring at the main-drive unit when switching energization of the coils.

The invention discloses a permanent magnet fault-tolerant vernier rim propulsion motor with an optimized consequent pole rotor surface shape, which belongs to the field of electric propulsion systems of water and underwater vehicles such as ships, unmanned ships, underwater robots, submarines, torpedoes and the like, and comprises a rotor, a propeller and a stator, the rotor comprises unipolar permanent magnets, rotor teeth and a rotor yoke; the rotor teeth are uniformly distributed on the rotor yoke, and a rotor groove is formed between every two adjacent rotor teeth; the unipolar permanent magnets are embedded into the rotor grooves; the surfaces of the rotor teeth and the surfaces of the unipolar permanent magnets are bent in shape. The maximum thickness of the rotor teeth are equal to the maximum thickness of the unipolar permanent magnets; the propeller is fixed on the inner surface of the rotor yoke; the stator is provided with a plurality of armature teeth, isolation teeth, winding grooves and armature windings. The armature winding is a single-layer concentrated winding; the permanent magnet fault-tolerant vernier motor and the wheel rim propeller are combined to form the permanent magnet fault-tolerant vernier wheel rim propelling motor, so that the electromagnetic performance of the motor is improved, the cost is reduced, and the fault-tolerant capability is stronger.

An embodiment of the invention provides an inter-line multifunctional fault current limiting system. The system is characterized in that a first switch tube and a first supercapacitor are connected between one end and the other end of a first dynamic voltage compensation module in series; one end of the first dynamic voltage compensation module is connected to one end of a first switch; the otherend of the first switch is connected to one end of a current-limiting inductor; the other end of the current-limiting inductor is connected to the other end of the first dynamic voltage compensation module; one end of an energy-discharging resistor is connected to the other end of the first switch while the other end of the energy-discharging resistor is connected to a collector electrode of a current-limiting IGBT; and an emitter of the current-limiting IGBT is connected to the other end of the first dynamic voltage compensation module; and if a power grid to be controlled normally operates,the current-limiting IGBT is disconnected, and other devices are closed. According to the embodiment of the invention, the short-circuit current obtained when a single feeder has short circuit or thetwo feeders have short-circuit faults simultaneously can be effectively inhibited, the voltage compensation depth is increased, the current of a ground fault line is controlled to be within a certainrange, and the fault overcurrent is restrained.

This drive device drives a plurality of switching elements (20), which include a first switching element (21) and a second switching element (22) and each have a gate electrode, in parallel. The drivedevice is provided with a driver (12) that supplies a voltage to the gate electrode, and a control unit (11) that outputs a control signal to the driver and controls the on/off state of the switchingelements. The control unit has, as control modes, a multi-drive mode in which both the first switching element and the second switching element are driven, and a single-drive mode in which only the first switching element is driven. In the single-drive mode, the control unit sets the gate voltage to be applied to the gate electrode of the first switching element to a clamp voltage that is smallerthan the gate voltage in the multi-drive mode.

The invention discloses a controllable phase shifter, which comprises a series transformer, a parallel transformer, a voltage regulating switch and a current limiter, wherein the current limiter is formed by connecting a bypass switch and a reactor in parallel; the current limiter is connected in series in a secondary side branch of the series transformer or connected in series in a secondary sidebranch of the parallel transformer; one of the series transformer secondary side branch, the parallel transformer primary side branch and the parallel transformer secondary side branch is in triangular connection, and the other two are in star connection, wherein the primary side branch of the series transformer is connected in series in a power transmission line, the primary side branch of the parallel transformer is connected with the primary side branch of the series transformer, and the secondary side branch of the series transformer is connected with the secondary side branch of the parallel transformer. The invention further discloses a control method of the controllable phase shifter. By adopting the technical scheme, the power flow of the power grid can be controlled, and the short-circuit current level is suppressed; the power grid transmission capacity, equipment utilization rate and safety are improved.