30 results about "Zigzag transformer" patented technology

A DC to DC converter including a zigzag transformer. The transformer operates at high frequency with integrated magnetics and does not provide isolation. The multiphase converter has gate inputs with PWM signals appropriately phase-shifted depending on the number of phases to make balanced phase voltages across the transformer windings. The switching frequency of the converter is relatively low but fast transient response can be achieved by adding an integrated zigzag transformer.

The invention relates to an ultra-low frequency alternating-current (AC) constant-current demagnetization device of a large transformer or mutual inductor, comprising a display (1) and a CPU control unit (2), wherein the CPU control unit (2) is connected with a power-frequency signal generator (3); the power-frequency signal generator (3) is connected with a voltage power amplifier (4); the voltage power amplifier (4) is connected with a voltage booster (5); the CPU control unit (2) is also connected with an ultra-low frequency signal generator (6); a switch is arranged between a transformer or a mutual inductor (8) to be tested and the voltage booster (5); and a switch is arranged between the transformer or the mutual inductor (8) to be tested and a current power amplifier (7). The invention overcomes the defects of long demagnetization time, easy transformer coil deformation, and the like of the traditional method and has the advantages of short demagnetization time, light equipment weight, and the like. The invention also discloses a demagnetization detection method adopting the demagnetization device.

The invention is a harmonics reduction device for three-phase poly-wire power lines, which can more reliably eradiate harmonics current applied to an electric power system via a neutral line. The invention comprises an electric power system having three-phase poly-wire power lines in order to supply alternating-current (AC) power voltage to a load; a zigzag transformer in which windings connected with three-phase lines in the electric power system are wound through first and second legs, second and third legs, and third and first legs of a core having three legs, respectively, while varying direction of each magnetic flux, and an intermediate point of each winding is commonly connected with a neutral line of the electric power system and that of the load; and an open delta connection portion in which an winding connected with the neutral line of a load side is wound through the three legs so as to be connected with a neutral line of the electric power system.

A DC to DC converter comprising a zigzag transformer is provided. The transformer operates at higher frequency with integrated magnetics and does not provide isolation. The multiphase converter has gate inputs with PWM signals appropriately phase-shifted depending on the number of phases to make balanced phase voltages across the transformer windings. The switching frequency of the converter is slightly lower but fast transient response can be achieved by adding an integrated zigzag transformer. The disclosed converter improves overall efficiency, reduces current ripple and simplifies current control.

A power conversion system eliminates output transformers and replaces them with a zig-zag transformer and a filter that provides a 3-phase 5-wire system with significantly reduced weight and size as compared with conventional systems. The zig-zag transformer may have a low zero sequence impedance. The power conversion system also ensures operational safety by detecting various types of ground faults.

The invention provides a novel zero-sequence current compensator. An inverter bridge is connected between a neutral point and a neutral line of a zigzag transformer; and a current output by the inverter bridge is injected into a system through a low-impedance zero-sequence current channel which is provided by the zigzag transformer so as to compensate for a neutral current. A controllable rectifier module is connected with the secondary side of the zigzag transformer to supply a direct-current power supply to the inverter bridge, and thus, the two-way flow of energy is realized and the problem of direct-current voltage rise caused when the compensator absorbs active power is solved. The novel zero-sequence current compensator has a series of advantages of good compensation effect, low direct-current voltage, small switching stress, few influences of system parameters, flexible control, few influences on system operation and the like.

The invention discloses a novel neutral line triple harmonic current suppressor, which comprises two LC circuits I and II and a zigzag transformer 5, wherein the two LC circuits I and II consist of capacitors and reactors; the LC circuit I is connected in series with a neutral line, a reactance end of the LC circuit I is connected with the neutral line at an input end of a low-voltage distribution network, a capacitance end of the LC circuit I is connected with the neutral line at a load side, three ends A, B and C of the zigzag transformer are connected with three-phase wires of the low-voltage distribution network, an N end of the zigzag transformer is connected with an reactance end of the LC circuit II, and a capacitance end of the LC circuit II is connected with the capacitance end of the LC circuit I. The neutral line triple harmonic current suppressor can overcome the influence of zero sequence voltage on the zigzag transformer on the basis of effectively suppressing the current of the neutral lines, and has little influence on the electrical energy quality of a user. The neutral line triple harmonic current suppressor has the advantages of simple circuit structure, low manufacturing cost, easy implementation, less influence on the zero sequence voltage of an electric network, good suppression effect on the neutral line triple harmonic current, and the like.

The invention discloses an intelligent electrical load unbalance compensation device, which belongs to the technical field of low voltage power distribution networks. The intelligent electrical load unbalance compensation device comprises a central control device, and a current and voltage sampling device, a zero sequence compensation device and a negative sequence compensation device which are in control connection with the central control device, wherein the current and voltage sampling device is used for collecting current and voltage signals of a load circuit; the zero sequence compensation device consists of a zigzag transformer TR and an impedance dynamic regulation device; and the negative sequence compensation device consists of combination switches FK1 to FK3, and grouped-switched compensation capacitors of each phase. The device can filter zero sequence current to be within 1A in a rated unbalanced load, increase the unbalance of three phases of current to be within 10 percent, ensure high electric energy utilization rate, safe and reliable running and remarkable energy saving effects, reduce loss and cost and improve the economic efficiency. The whole device is connected into a power grid in parallel, and is convenient to arrange, simple to use and applied to the low voltage power distribution networks of industrial mining, enterprises, traffic transportation department, residential areas and the like.

An inverter circuit for discharge lamps, in which transformers are separated into multiple small or middle-sized transformers connected to one another to provide a high-power transformer equivalent to a large transformer. The inverter circuit includes a plurality of leakage flux step-up transformers each having a magnetically continuous central core, a primary winding, and a distributed-constant secondary winding, wherein a part of a resonance circuit is formed among a leakage inductance produced on the secondary winding side, a distributed capacitance of the secondary winding and a parasitic capacitance produced around a discharge lamp close to a proximity conductor, and as the resonance circuit resonates, the secondary winding has a close coupling portion in a vicinity of the primary winding which has a magnetic phase close to that of the primary winding and magnetically close couples with the primary winding.

A transformer includes a zigzag transformer comprising first, second and third magnetic cores. The transformer further includes an auxiliary winding set comprising respective pairs of series-connected windings on respective pairs of the first, second and third magnetic cores, the pairs of series-connected windings having respective first terminals connected to respective AC phases of the zigzag autotransformer and respective second terminals configured to provide respective AC output phases.

Provided is a testing method of a phase shifting angle of a zigzag transformer. The testing method comprises the steps of enabling a B phase and a C phase of a primary side of the zigzag transformer to be in short circuit; adding alternating voltage between an A phase and the B phase; utilizing voltage meters to respectively measure the voltage between the A phase and the B phase of the primary side, the voltage between an a phase and a b phase of a secondary side and the voltage between the b phase and a c phase of the secondary side; calculating the phase change ratio of the voltage between the A phase and the B phase of the primary side to the voltage between the phase and the b phase of the secondary side; calculating the phase change ratio of the voltage between the A phase and the B phase of the primary side to the voltage between the b phase and the c phase of the secondary side; and finally solving the phase shifting angle beta of the zigzag transformer by means of the formula as followed. According to the testing method, the transformation ratio and the phase shifting angle of the zigzag transformer can be quickly and accurately measured by means of the reading of the two ordinary voltage meters and the formula, the problem troubling people for a long time caused by the testing of the zigzag transformer is solved well, and convenience is created for production, application and maintenance of the zigzag transformer.

The invention provides a balance compensation device of a low-voltage power grid. The balance compensation device comprises a zigzag transformer, a single-phase inverter, a zero sequence current detecting circuit and an inverter controller, wherein the zigzag transformer is connected to the three phases of the low-voltage power grid, one end of the output end of the single-phase inverter is connected with the neutral line of the zigzag transformer, the zero sequence current detecting circuit is used for detecting the currents of the neutral line of the zigzag transformer and the currents of the neutral line of the low-voltage power grid, the inverter controller controls the single-phase inverter according to the detecting results of the zero sequence current detecting circuit, and the other end of the output end of the single-phase inverter is used for being connected with the neutral line of the low-voltage power grid. By the balance compensation device, zero sequence currents form a loop among the zigzag transformer, the single-phase inverter and a load, the currents of the neutral line of the low-voltage power grid is allowed to drop to zero, compensation of the zero sequence currents of the low-voltage power grid is completed, and the three-phase unbalance problem of the low-voltage power grid is solved.

An electrical power system connectable to a power grid includes a plurality of electrical power subsystems, each of the plurality of electrical power subsystems including a power converter electrically coupled to a generator having a generator rotor and a generator stator. The electrical power system further includes an intermediate power path extending from each of the plurality of electrical power subsystems for providing power from each of the plurality of electrical power subsystems to the power grid. The electrical power system further includes a zig-zag transformer electrically coupling each of the plurality of intermediate power paths to the power grid, the zig-zag transformer including a primary winding and a plurality of secondary windings, each of the plurality of secondary windings connected to one of the plurality of intermediate power paths, and wherein at least one of the plurality of secondary windings is a zig-zag winding.

The invention discloses an intelligent electrical load unbalance compensation device, which belongs to the technical field of low voltage power distribution networks. The intelligent electrical load unbalance compensation device comprises a central control device, and a current and voltage sampling device, a zero sequence compensation device and a negative sequence compensation device which are in control connection with the central control device, wherein the current and voltage sampling device is used for collecting current and voltage signals of a load circuit; the zero sequence compensation device consists of a zigzag transformer TR and an impedance dynamic regulation device; and the negative sequence compensation device consists of combination switches FK1 to FK3, and grouped-switched compensation capacitors of each phase. The device can filter zero sequence current to be within 1A in a rated unbalanced load, increase the unbalance of three phases of current to be within 10 percent, ensure high electric energy utilization rate, safe and reliable running and remarkable energy saving effects, reduce loss and cost and improve the economic efficiency. The whole device is connected into a power grid in parallel, and is convenient to arrange, simple to use and applied to the low voltage power distribution networks of industrial mining, enterprises, traffic transportation department, residential areas and the like.

A three-phase unbalanced intelligent compensation device comprises a signal sampling unit, a central control unit, a positive sequence and negative sequence compensation unit and a zero sequence compensation unit and is characterized in that the signal sampling unit is connected in series with a voltage sampling unit and a current sampling unit on a power grid, the signal sampling unit is used for sending information sampled by the voltage sampling unit and the current sampling unit to the central control unit for processing and analysis, the central control unit controls the positive sequence and negative sequence compensation unit and the zero sequence compensation unit which are connected to the power grid, the positive sequence and negative sequence compensation unit comprises an LCL filter and a positive-negative sequence IGBT (Insulated Gate Bipolar Transistor) inversion bridge, and the zero sequence compensation unit comprises a zigzag transformer and a zero sequence IGBT inversion bridge. By the three-phase unbalanced intelligent compensation device, electric energy loss and device loss caused by three-phase unbalance can be effectively improved, a zero sequence current and a negative sequence current existing in the power grid are effectively compensated, a positive sequence current is transferred among phases, so that the three-phase current is balanced. The three-phase unbalanced intelligent compensation device has the advantages of fast response speed and high tracking accuracy, stepless regulation is achieved, and the stability and the reliability of the power grid can be greatly improved.

The invention discloses a power distribution network ground fault arc extinction method and device based on stepless voltage regulation, relates to the technical field of power systems, and aims to obtain a voltage opposite to a fault by using a low-voltage side voltage of a zigzag transformer to suppress a neutral point voltage, quickly switch a neutral point series resistor, change the neutral point voltage and quickly judge whether a fault point disappears or not. Compared with an active arc extinguishing device using a power electronic device, the device disclosed by the invention realizes arc extinguishing through simple transformer, resistor selection and electrodeless on-load voltage regulator, and is simple in structure, low in cost and high in adaptability and stability.

A method, apparatus, and system in which a neutral deriving transformer incorporates a zig-zag transformer configuration is provided. A zig-zag transformer provides an electrical load with a neutral wire. The zig-zag transformer may be electrically connected downstream of a main AC voltage step-down transformer. Additionally, three phase AC voltage lines can be routed to the zig-zag transformer such that the zig-zag transformer comprises a neutral deriving transformer that electrically connects to a ground conductor. The neutral deriving transformer might not be electrically connected to a neutral conductor of the main voltage step-down transformer. The zig-zag transformer can phase shift each winding by approximately 120 degrees and may derive a neutral for at least one single phase load connected to the zig-zag transformer and one of the three phase AC lines in order to provide a common neutral point that takes the place of a neutral cable that connects back to the main AC voltage step-down transformer.

The invention discloses a dephasing self-coupling zigzag transformer. The dephasing self-coupling zigzag transformer is connected with a transformer load and an arc-suppression-coil load. The dephasing self-coupling zigzag transformer comprises a three-phase high-voltage winding. Each phase of coil of the high-voltage winding comprises an upper coil and a lower coil. The upper coil and the lower coil have same number of turns. The upper coil sleeves an upper iron core of a three-phase iron core. The lower coil sleeves a lower iron core of the three-phase iron core. The upper coil is a main winding with a voltage-adjusting tap. The lower coil is a dephasing winding with a dephasing effect. The dephasing winding and the voltage-adjusting winding have a 60-degree phase relation on each phase.When zero sequence currents with a certain magnitude pass through the transformer, currents of the two single windings on a same steel iron core column are different in direction but same in magnitude, so that magnetic potentials generated by the zero sequence currents are opposite to be offset, and the zero-sequence impedance is low.

The application provides a zero sequence current compensation system of a low voltage distribution network. The zero sequence current compensation system of the low voltage distribution network comprises a zigzag transformer connected with the low voltage distribution network, a single phase inverter, an electric current detection device used to detect an electric current of a neutral line of the zigzag transformer, an electric current of a neutral line of the low voltage distribution network and an electric current of a neutral line of a load and an inverter controller used to control the single phase inverter according to detection results of the electric current detection device, wherein one output end of the single phase inverter is connected with the neutral line of the zigzag transformer, and the other output end of the single phase inverter is connected with the neutral line of the load and the neutral line of the low voltage distribution network. The zero sequence current compensation system of the low voltage distribution network can enable a zero sequence current to form a loop circuit among the zigzag transformer, the single phase inverter and the load, and then reduces the electric current of the neutral line of the low voltage distribution network to zero, and thereby achieves compensation for the zero sequence current of the low voltage distribution network, and furthermore solves the problem that three phases of the low voltage distribution network are imbalanced.

A zigzag autotransformer includes a zigzag transformer including first, second and third magnetic cores and an auxiliary winding set including respective pairs of series-connected windings on respective pairs of the first, second and third magnetic cores, the pairs of series-connected windings having respective first terminals connected to respective AC input phase terminals of the zigzag autotransformer and respective second terminals configured to provide respective AC output phases.

The invention relates to a method and a device for checking differential protection polarity of a large transformer and computer equipment. The method comprises the following steps of acquiring a differential current of the large transformer in a startup process of a large motor; connecting the large motor to a low voltage side of the large transformer; and if the differential current meets a preset polarity condition, confirming that the differential protection polarity of the large transformer is correct. According to the method for checking the differential protection polarity of the largetransformer, a starting current of the large motor is utilized as a load current for checking the differential protection polarity of the large transformer, the differential current of the large transformer is acquired in the startup process of the large motor, and when the differential current meets the preset polarity condition, the differential protection polarity of the large transformer is judged to be correct, the requirements for checking the protection polarity of the large transformer of a new power plant are met, so that the operation condition can be achieved when the large transformer is put into operation, and the method for checking the differential protection polarity of the large transformer is simple, reliable and economical.

The invention provides a low-voltage transformer area electric energy quality control device comprising a transformer and a control loop. The transformer is a ZigZag transformer. The control loop comprises an inverter, a sampling circuit, a PWM modulator, a protection circuit and a filter. With the transformer and the control loop, zero-sequence current of external lines can be effectively detected and can be timely compensated for effectively to filter zero-sequence current.