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 belongs to the technical field of harmonic treatment, and provides a harmonic suppression circuit for an electromagnetic compatibility laboratory and a compensation method thereof. The circuit and the method thereof adopt two-stage tandem type active power filters connected in series in the forward direction, and a dry-type iron core reactor is connected in parallel between the tandem type active power filters and the power source end of a load. The dry-type iron core reactor is mainly used for restraining high-frequency interference with a frequency higher than 10 KHz, cannot influence the filter performance of the tandem type active power filters, is the major support equipment of a reactive compensation device in an electric system, can effectively restrain higher harmonic, limits the switching-on flashy current and switching overvoltage, improves the voltage waveform of the system, increases the power factor, and plays a greater function for the safe operation of a power capacitor and other electric equipment. Therefore, the dry-type iron core reactor connected in parallel connection guarantees the safe operation of other equipment in the electromagnetic compatibility laboratory, voltage change of inlets of all loads can be compensated, the detection reliability and accuracy in electromagnetic compatibility of the product can be improved.

The invention discloses an electronic-type ballast for reducing the power grid voltage waveform distortion by bidirectional controllable silicon. The electronic-type ballast for reducing the power grid voltage waveform distortion by bidirectional controllable silicon comprises a rectifying circuit, a filter circuit, a contravariant driving circuit and a contravariant circuit. The electronic-type ballast for reducing the power grid voltage waveform distortion by bidirectional controllable silicon is characterized in that an input end of the rectifying circuit is provided with an electronic switch circuit; the electronic switch circuit is always at a disconnection state in the process that the power grid voltage changes from 0V to wave peak and wave trough, and the electronic-type ballast cannot acquire energy from the power grid; when the power grid voltage exceeds the parts close to the wave peak and wave trough, the electronic switch circuit is switched off, and the rectification-type electronic equipment can acquire energy from the power grid. According to the electronic-type ballast, rectification-type equipment only utilizes energy after the power grid voltage exceeds the wave peak and wave trough by controlling the moment in disconnecting and switching off an electronic switch circuit, avoids to utilize the energy of the power grid voltage peak value as well as the energy within the time interval close to the power grid voltage value, can effectively reduce 3rd harmonic component and 5th harmonic component injected into a power grid, reduces the power grid voltage waveform distortion, and improves the power grid electricity energy quality.

The invention relates to the field of unit testing of high voltage transformer products, in particular to a performance testing method for the voltage transformer. The performance testing method for the voltage transformer is characterized in that a frequency modulation voltage-controlled power source is used as a testing power source and a frequency-modulated and voltage-controlled voltage signal is output, the requirements for the exciting voltage of a secondary winding of a tested voltage transformer are met through voltage rising of an exciting transformer, the induction voltage of the first winding of the tested voltage transformer is collected by a voltage sampler, and monitoring is conducted on the output voltage, the frequency and the output currents of the frequency-modulation voltage-controlled power source and high-voltage feedback of the voltage transformer. Compared with the prior art, the performance testing method for the voltage transformer has the advantages that a third harmonic generation power source large in size is replaced, conveying cost of testing equipment is reduced, testing quality is improved, voltage waveform is improved, and disturbance of higher harmonics is avoided. During the testing process, the no-load voltage ratio and excitation characteristic testing can be achieved under the power frequency conditions, and the voltage transformer is multifunctional. Over-voltage protection can be set, and the safety of the tested voltage transformer can be ensured. Equipment is low in weight and convenient to carry.

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 a low-noise saturable reactor, which can lower the reactance value of the saturable reactor in saturated state. The low-noise saturable reactor comprises a saturable reactor iron core, wherein a reactance coil L1 and a direct-current coil L2 are arranged on one side of the saturable reactor iron core; a reactance coil L3 and a direct-current coil L4 are arranged on the other side of the saturable reactor iron core; the reactance coil L1 and the reactance coil L3 have the same structure and the same number of turns; the direct-current coil L2 and the direct-current coil L4 have the same structure and the same number of turns; the homonymous end of the reactance coil L1 is connected with the synonymous end of the reactance coil L3 and is taken as an alternating-current terminal I of a saturable reactor alternating-current loop; the synonymous end of the reactance coil L1 is connected with the homonymous end of the reactance coil L3 and is taken as another alternating-current terminal II of the saturable reactor alternating-current loop; the homonymous end of the direct-current coil L2 is connected with the synonymous end of the direct-current coil L4 and is taken as a direct-current terminal I of a saturable reactor direct-current loop; and the synonymous end of the direct-current coil L4 is taken as another direct-current terminal II of the saturable reactor direct-current loop.

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.

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 otherat 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 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 a non-60° phase-band symmetric double-layer stator winding slot number selection, phase-band division and winding connection method, and provides the relationship between the number of poles, the number of branches, the number of slots per pole and each phase, The phase-band division and its specific requirements point out that non-60° phase-band symmetrical double-layer windings can be wave windings or stacked windings, integer slot windings or fractional slot windings, but they must be connected at full pitches. The invention can solve the problems of capacity, rotating speed and voltage mismatch, and achieve the purpose of weakening harmonics and improving voltage waveforms.