41results about How to "Improve voltage waveform" patented technology

The invention discloses a microgrid inverter multi-loop control method based on a virtual synchronous generator, and the method comprises power control of an outer loop and voltage current control of an inner loop. The power control of the outer loop comprises the following steps: measuring the three-phase voltage and current of an output side of an inverter, calculating active power and reactive power according to the instantaneous power theory, carrying out calculation and regulation through an active power-frequency equation, a reactive frequency equation, a torque inertia equation and an electromagnetic transient equation of a synchronous motor, obtaining the amplitude of an output voltage and a phase angle given value, and then carrying out modulation through voltage and current double loops. The method can achieve the non-corresponding control of voltage size and frequency well, outputs active and reactive power, can achieve precise manual control, and has the characteristics of V/F and PQ control. When a fault happens to a power grid, the method can simulate the primary modulation, primary voltage regulation and inertia characteristics of the synchronous generator, participates in the power grid adjustment, provides frequency and voltage support, and facilitates the stabilization of the power grid.

The invention relates to a reactive power compensation method and a reactive power compensation system for a micro power grid. The system comprises a distributed measuring unit, a reactive power compensation control unit, a reactive power compensation unit and a communication unit. The micro power grid comprises a distributed power supply with reactive regulation output. For the micro power grid operated in an isolated network mode, the overall reactive power balance condition of the micro power grid is obtained by measuring the active and reactive power distribution conditions of each branchcircuit of the micro power grid, and a reactive power compensation device or the reactive power compensation device and the distributed power supply are subjected to reactive regulation in the micro power grid according to a specific isolated network reactive control strategy to realize the reactive power compensation of the micro power grid. The power factor of the micro power grid can be measured and corresponding reactive power compensation is performed according to the power factor when the micro power grid is operated in a grid-connected mode and in the isolated network mode.

The invention relates to an overall salient type intermediate-frequency brushless excitation synchronous generator, which comprises a main generator, an exciter, an excitation regulating system. The excitation regulating system consists of a compound excitation device, a rotating rectifier and an AVR automatic voltage regulator, wherein the compound excitation device consists of a compound excitation winding, a compound excitation current transformer and a three-phase rectifier bridge, the stator of the main generator adopts a fractional slot type short-range winding, the slot number per pole and per phase q is a fractional value, the rotor of the main generator is formed by lamination of multi-pole rotor core laminated pieces, the rotor core of the main generator is of an overall salient type rotor core structure and is formed by overall punching and lamination of rotor core laminated pieces, each rotor core laminated piece is formed with a magnetic pole and a magnetic yoke integrated, and an axial air-cooling hole is arranged at the magnetic yoke. The generator realizes the brushless excitation intermediate-frequency generation, outputs the single-phase or three-phase intermediate-frequency voltage, and has the advantages of excellent performance, stable and reliable operation and high output power.

A low-pulse rare earth permanent magnetism brushless motor comprises a stator and a rotor which forms a column shape by stacking the punched sheet. A radial air gap is arranged between the stator and the rotor. The rotor is uniformly and symmetrically arranged with a permanent magnet accommodating holes. The permanent magnet is inserted in the accommodating hole and the end of the accommodating hole is arranged with magnetism-splitting holes which are symmetrically arranged at two ends of the diagonal of the accommodating hole. The magnetism-splitting hole is larger at the side next to the accommodating hole and gradually reduces along the radian direction of the outer diameter of the rotor and at last forms a small arc. Through arranging a magnetism-splitting hole at the end of the permanent magnet accommodating hole of the punched piece of the rotor and at the same time designing the radial air gap between the stator and the rotor to asymmetric air gap through the different positions of the inner diameter of the stator and the outer diameter of the rotor, the invention has the advantages of endowing the electric motor with magnetism collecting function, evidently improving the voltage waveform induced in the stator winding, namely improving the back electromotive force waveform of the electric motor, reducing the torque of the tooth socket, reducing the torque ripple, and realizing the high-efficiency, smooth and silent operation of the permanent magnet brushless motor.

The invention discloses a mechanical energy storage type highway speed bump power generation device comprising a mechanical transmission part and an energy storage power generation part. The mechanical transmission part mainly comprises a speed bump, a supporting frame, a metal strip, a first crank, a second crank and a driving swing rod, wherein the first crank, the second crank and the driving swing rod are sequentially hinged; one end of the first crank is hinged to the metal strip, the other end of the first crank and the second crank are jointly hinged to a sliding block, the sliding block is mounted in a guiding groove in a supporting plate, and a return spring is mounted on the lower portion of the sliding block in the guiding groove; a driving pawl of a ratchet wheel structure andthe driving swing rod are fixed, a rotating shaft is fixedly connected with a first one-way clutch and a second one-way clutch which are opposite in linkage direction, and the outer circle of the first one-way clutch is fixedly connected with a ratchet wheel; the energy storage power generation part comprises a power generator and a spring-type elastic energy storage device, a mounting gear is arranged on a power generator shaft, and the mounting gear is engaged with an external gear at the outer circle of the second one-way clutch. According to the mechanical energy storage type highway speedbump power generation device, the multistage variable speed is set, the high transmission ratio is achieved as much as possible through the smallest space, mounting is convenient, and the power generation amount is large.

A power conversion device includes transformers (20n) provided with primary windings connected to input terminals (R,S,T) and secondary windings including pluralities of single-phase open windings that are insulated from each other; a plurality of converter cells (30Xn) connected to the secondary windings of the transformers (20n); and a control circuit (601) for controlling ON/OFF of switching elements. The converter cells (30Xn) each include a converter (3a) and the inverter (3b) that are provided with the switching elements, in which their input ends are connected to the respective single-phase open windings, so that the input ends are connected in mutually parallel fashion, through the transformers (20n), to the input terminal (R,S,T) of each phase, and in which their output ends are connected in mutually serial fashion to an output terminal (U,V,W) of each phase, to thereby perform three or more-level power conversion.

The invention provides an AC chopper-type voltage stabilizer, a filtering method and a filtering system thereof. The voltage stabilizer comprises a two-way switch buck converter, a filter circuit, a transformer and a control unit, wherein the control unit treats the actual input voltage Vm of the voltage stabilizer according to the following filtering method, generates and sends control signals to the two-way switch buck converter, and controls the output waveform of the voltage stabilizer by controlling the turn-on and turn-off of a power switching element. The filtering method at least comprises: (1) performing band-stop filtering on the actual input voltage Vm of the voltage stabilizer and generating a signal Vs1; (2) implementing linear correction and generating a signal Vs2; (3) performing division algorithm and generating a signal Vc; (4) performing negative feedback operation and generating a signal Vs3; and (5) forming a PWM control signal. Through hardware and software filtering, the invention has the advantages of improving filter topology, adding a filtering control method and ensuring good voltage waveform on the primary side of the transformer, good voltage compensation effect of the transformer and superior performance of the voltage stabilizer.

The invention relates to a multi-level reactive compensation system suitable for an unbalanced load and a control method of the multi-level reactive compensation system and belongs to the field of thereactive compensation of electric power systems. According to the multi-level reactive compensation system, a convection circuit includes a direct current link and an inversion circuit which are connected in parallel; the direct current link comprises a plurality of direct current link circuit units which are connected in series; each direct current link unit comprises a switching tube S1, a switching tube S2 and a capacitor C1; the positive pole of the capacitor C1 is connected with the collector of the switching tube S1; the emitter of the switching tube S1 is connected with the collector of the switching tube S2; and the emitter of the switching tube S2 is connected with the negative pole of the capacitor C1. The number of switches and the number of grid drivers can be remarkably reduced compared with a cascade H-bridge structure, therefore, the system is easier to expand, and can effectively inhibit and eliminate harmonic waves in a reactive current compensation process.

The invention discloses a slot number selection, phase belt division and winding connection method of non-60-degree phase belt symmetric double-layer stator windings. According to the method, the pole number, the branch number, the relation between the slot number of each phase and each pole, the phase belt division and the specific requirement, it is pointed that the non-60-degree phase belt symmetric double-layer stator windings can be wave windings or lap windings, and can be integral-slot windings or fractional-slot windings, and the windings must be connected in a whole-distance mode. The problem that the capacity, the rotating speed and voltage are mismatched can be solved, and the aims that the harmonic wave is weakened, and the voltage waveform is improved can be achieved.

The invention discloses a series voltage injection-based current-type high voltage direct current transmission (LCC-HVDC) system commutation failure suppression method. The core of the method is thatthree-phase voltage series injection is carried out between the inverter of the LCC-HVDC and a receiving-end AC system to compensate dynamic fall of the voltage of the receiving-end AC system, seriesvoltage injection is realized through a unified power flow controller, a parallel transformer of the unified power flow controller is parallelly connected at the AC system side, and a series transformer is serially connected at the inverter side of the LCC-HVDC. A dynamic voltage series injection control algorithm is designed for the series converter of the unified power flow controller, so as toenable the three-phase voltage generated by the series converter of the unified power flow controller to dynamically compensate the dynamic fall of the voltage at the AC system side through the seriestransformer. Voltage distortion and voltage fall at the LCC-HVDC inverter side can be further reduced, and finally, the LCC-HVDC inverter commutation failure possibility is reduced.

The invention discloses an asymmetric connecting wire balancing transformer and an implementation method thereof. The transformer comprises an iron core, a primary side winding and a secondary side winding, and is characterized in that: the primary side winding adopts a Y-shaped connecting wire; a neural point N of the Y-shaped connecting wire is grounded; the number of circles of the primary side winding is W1; in the secondary side winding, the A-phase winding consists of two windings, namely ea and ab; the B-phase winding consists of one winding bc; and the C-phase winding consists of two windings, namely dc and ca; the number of circles of the windings ab, bc, ca and dc is W2, and the number of circles of the winding ea is W3; the windings ab, ca and ea are connected with one another at a point a serving as a common point, the windings ca, bc and dc are connected with one another at a point c serving as another common point, and the windings ab and bc are connected with each other at a point b serving as another common point; two no-load voltages Ueb and Udb are equal to each other; and the phase difference is 90 degrees. The secondary side of the asymmetric connecting wire balancing transformer has an asymmetric winding structure, so the production is convenient to execute, the comprehensive performance is high, the structure is simple, and the material utilization rate is high.

The invention provides a smoothing reactor end-to-end capacitor discharge test system and a transient wave trapper thereof. The transient wave trapper comprises a first resistor, a second resistor, a third resistor, a first capacitor and a second capacitor, one end of the first resistor is connected to one end of the second resistor and one end of the third resistor, the other end of the second resistor is grounded, the other end of the third resistor is connected to one end of the first capacitor and one end of the second capacitor, and the other end of the first capacitor and the other end of the second capacitor are grounded.

The invention provides a bulb tubular hydraulic generator, and belongs to the technical field of hydroelectric power generation equipment. The bulb tubular hydraulic generator comprises a bulb head and a stator frame integrally fixed and arranged in a co-movable manner, a generator body fixed in the stator frame, a stator upstream flange clamped between the stator frame and the bulb had, at least a group of ventilation assembly, and at least one group of wind screen assembly, a plurality of ventilation assemblies are fixed on the stator upstream flange and uniformly distributed at intervals in a co-circumferential manner, the wind screen assemblies are detachably fixed in the stator frame, the wind screen assemblies and the stator upstream flange are constructed to form a single-circulation air supply unit in which the wind screen assemblies communicate with the ventilation assemblies and the wind screen assemblies and the ventilation assemblies are mutually independent, the generator body comprises excitation assemblies, and the excitation assemblies and the stator frame are arranged in a coaxial manner. According to the bulb tubular hydraulic generator, brushless double-frequency generation can be realized, brushless variable-frequency generation can also be realized, the energy consumption of the whole ventilation system is reduced, the axial air quantity distribution can be effectively improved, and the ventilation and heat radiation effects of a unit can be improved.