197results about How to "Reduce Harmonic Pollution" patented technology

This invention discloses a inversion method for photovoltaic parallel in network, which uses digital signal processor (DSP) as core, the power factor is one and having small harmonic pollution to electric network, said method is a high efficiency and high reliability inversion method.

The invention discloses a reactive power control circuit of a single-phase photovoltaic inverter. The reactive power control circuit comprises a bus voltage supporting capacitor, a single-phase full-bridge inversion circuit, a filtering inductor, an EMC (Electro Magnetic Compatibility) filtering circuit, a sampling circuit, a power switch pipe driving circuit and a DSP (Digital Signal Processor), wherein the DSP consists of a PLL (Phase Locked Loop) control module, a voltage outer ring PI control module, a current inner ring PI feedforward control module and a sinusoidal PWM (Pulse-Width Modulation) wave sending control module, and an input signal of the sinusoidal PWM wave sending control module of the DSP further includes a current inner ring current given amount Ig. The invention further provides a reactive power control method of the single-phase photovoltaic inverter. The method not only can be used for judging whether the voltage Uac of a power grid is larger than zero, and comparing the absolute value of a PWM wave sending control input modulation wave Upwm with a given triangular carrier wave Uc, but also can be used for judging whether the given current inner ring current amount Ig is larger than zero. Not only can the conduction loss of a power switching tube be reduced, and the conversion efficiency of the inverter is improved, but also the current waveform can be continuous, an output harmonic wave is reduced, and the pollution on a harmonic wave of a power grid is reduced.

The invention relates to the technical field of wind power generation, in particular to a wind power generation-combined ordered charge and discharge coordinated control system of a pure electric vehicle. The system is characterized in that: information of each charging station is transmitted to a power grid dispatching center, the power grid dispatching center judges the state of the current power system to generate a corresponding charging control mode, and then, the information is transmitted to a charging station concentrated coordination monitoring system to carry out information interaction; the power gird dispatching center transmits a pitch peak instruction to each dynamic battery, namely a dynamic battery group, through a communication network of the charging station concentrated coordination monitoring system; and the dynamic battery group receives the pitch peak instruction to realize pitch peak and feeds back residual electric quantity to a power grid at the same time. According to the system disclosed by the invention, an advantage complementation relation among wind power generation, charge and discharge of the electric vehicle and power gird stabilization is realized and coordinated; the acceptability of wind and electricity is improved; the harmonic pollution caused by disordered charge of the pure electric vehicles and the adverse influence on the power grid are reduced to the greatest extent, and the utilization efficiency of wind and electricity and the stabilization level of the power grid are improved.

The invention relates to a three-phase-to-five-phase double-stage matrix converter based on a Z source, which belongs to the technical field of power electronic converters and aims to overcome the problems that the traditional five-phase voltage source inverter is large in size, low in input side power factor and limited in service life of a frequency converter and causes serious pollutions to power grid harmonic waves and the existing matrix type converter is low in voltage transmission ratio. The matrix converter provided by the invention comprises a double-stage matrix type converter and a Z source network, wherein the double-stage matrix type converter is composed of a rectifier stage circuit and an inverter stage circuit; the Z source network is connected in series between the rectifier stage circuit and the inverter stage circuit; one end of a first capacitor of the Z source network is connected with one end of a first inductor to serve as a first input end; the other end of the first inductor is connected with one end of a second capacitor to serve as a first output end; the other end of the second capacitor is connected with one end of a second inductor to serve as a second input end; and the other end of the second inductor is connected with the other end of the first capacitor to serve as a second output end. The matrix converter provided by the invention is suitable for driving a five-phase motor.

The invention discloses a method for smoothing output power of a wind power station by utilizing an energy storage system. In the method, not only wind power is introduced to predict or rectify the output power of the wind power station, but an improved self-adaptive filtering algorithm is applied. Since the output power of the wind power station is rectified by predicting the wind power, the change rate of the output power of the wind power station is decreased, and the output power of the wind power station can meet standards to inject into a power grid. By employing the self-adaptive filtering algorithm, regarding to the input power in different time, time weight coefficient in an adaptive filtering structure can be automatically calculated according to the input, so that the defect that different input cannot correspond to different filtering time constant by utilizing a low pass filter smoothing method in the past can be overcome. After the smoothing method is employed to smooth the output power of the wind power station, the output voltage of the wind power station is kept stable, fluctuation and flicker of the power grid voltage is reduced, harmonic pollution is reduced and accidents are reduced.

The invention discloses an accumulator formation charging/discharging main circuit structure which can improve power factor and reduce the harmonic pollution to power network. The invention comprises a power supply which is a reversible DC power supply with an anode and a cathode respectively connected with a positive DC bus and a negative DC bus which are connected with at least one charging/discharging unit; each charging/discharging unit comprises a charging circuit which is connected with a reversible LED in parallel and a discharging circuit; the input terminal of the charging circuit is connected with the positive DC bus; the output terminal of the discharging circuit and the cathode output terminal of the charging/discharging unit are both connected with the negative DC bus; the output terminal of the charging circuit is connected with the input terminal of the discharging circuit and then connected with the anode output terminal of the charging/discharging unit. The power factor of the invention is close to 1; the invention greatly reduces the harmonic pollution to power network and saves energy resource.

The invention relates to a hybrid energy storage topological structure on the basis of an MMC (modular multilevel converter). The structure comprises a positive bridge arm and a negative bridge arm; the positive bridge arm is formed by sequentially connecting power conversion subunits 1 to n in series; one end of the positive bridge arm is connected with a high-voltage DC (Direct Current) positive bus bar and the other end of the positive bridge arm is connected to a high-voltage three-phase AC (Alternating Current) power grid by a current limiting reactor; the negative bridge arm is formed by sequentially connecting power conversion subunits n+1 to 2n in series; one end of the negative bridge arm is connected with a high-voltage DC negative bus bar and the other end of the negative bridge arm is connected to the high-voltage three-phase AC power grid by a current limiting reactor; each functional conversion subunit is formed by connecting a power conversion module, a potential isolation module and an energy storage module in series. According to the invention, various energy storage bodies are flexibly switched into a power system and an energy storage function and a service which are uninterrupted, high in quality, flexible to control and safe to operate are provided for the power system.

The invention relates to storage battery charge and discharge circuit topology which comprises a first stage of circuit, a second stage of circuit and a digital signal processor (DSP) controller; the first stage of circuit comprises three phases of alternating current power grids and an inverter circuit; the inverter circuit is provided with six transistors of a three-phase bridge, and the second stage of circuit comprises a first conversion circuit, a transformer, a second conversion circuit and a battery; and the DSP controller controls the output voltage, the output current and the switching direction of the inverter circuit and two direct current-direct current (DC-DC) conversion circuits so as to control the charge or the discharge of the whole circuit. After the device is adopted, charge and discharge with unit power factor can be realized for a power grid side; the pollution to the power grid is little; through a certain control method, a pulse width modulation (PWM) rectifier can realize a scalable vector graphics (SVG) function; the output of a wide voltage scope can be realized; and the charge and discharge efficiency is higher.

The invention discloses a highly-reliable main circuit topological structure of a railway ground deflector. The highly-reliable main circuit topological structure comprises a rectification unit, an intermediate DC link and an inversion unit, wherein the rectification unit comprises a single-phase input multi-winding isolation transformer and N power modules on the rectification side. The primary side of the single-phase input multi-winding isolation transformer is connected with a railway traction network, and the secondary side of the single-phase input multi-winding isolation transformer is a plurality of electrically isolated multi-winding coils. Each multi-winding coil is connected with the AC input side of a rectification-side power module, the positive DC bus of the power module is in parallel with the positive DC bus of the intermediate DC link, and the negative DC bus of the power module is in parallel with the negative DC bus of the intermediate DC link. M electrical isolation converter sub-systems can be designed according to system power transformation requirements, power modules in the converter sub-systems are controlled through a carrier phase-shift PWM modulation strategy, cascade operation is carried out through the magnetic field of an isolation transformer, and the reliability of a converter is improved.

The invention discloses a mining high-voltage frequency converter with an explosion-proof type. The frequency converter comprises a phase-shifting transformer unit explosion-proof box and a power unit explosion-proof box; a phase-shifting isolation transformer and a heat radiation system are arranged in the phase-shifting transformer unit explosion-proof box; and a plurality of sets of power units, a control unit and a heat radiation system are arranged in the power unit explosion-proof box, wherein the plurality of sets of power units are in series connection. A high-tension side of the phase-shifting isolation transformer is in series connection with a three phase high voltage power network; the plurality of sets of power units are respectively connected with a low tension side of the phase-shifting isolation transformer; and the power units and the control unit are connected by a fiber. According to the invention, all assembling combination surfaces of the phase-shifting transformer unit explosion-proof box and the power unit explosion-proof box are constructed into sealing structures, so that an external environment is isolated from the phase-shifting transformer unit explosion-proof box and the power unit explosion-proof box; therefore, it can be avoided that corresponding chain explosions happen at high-risk occasions including a coal mine and the like and an explosion-proof effect is good. Besides, a control signal is transmitted by a fiber, so that an electrical isolation capability and an anti-electromagnetic interference performance are good.

The invention discloses a unipolar and bipolar hybrid modulation method for a single-phase voltage type PWM rectifier. By the adoption of the hybrid modulation manner with unipolar modulation and bipolar modulation combined, the problem that zero crossing point current distorts in the unipolar modulation process is solved, the sine degree of current is improved, and the problem of large switching losses in the bipolar modulation process is also solved. The purpose that harmonic pollution on a power grid from net-side unit power factors is low is achieved, and meanwhile the efficiency of the PWM rectifier can be improved.

The invention discloses a control method for an aging power supply device, and belongs to the field of power electronic system control. The method comprises a control method of a single-phase AC/DC converter circuit, an open-loop control method adopted by an LLC resonant converter, and a control method of a bidirectional BUCK-BOOST converter circuit. Through the control method of the single-phaseAC/DC converter circuit, the DC bus voltage is kept constant, fluctuation of the power grid frequency and distortion of the grid connection current at the non-fundamental frequency are suppressed, andharmonic pollution to the power grid is reduced. Through the adoption of the open-loop control method, the series LLC resonant converter can work in an intermittent mode, the switching loss of the circuit is reduced, and meanwhile, the requirement of boosting between a direct-current bus and the input of the BUCK-BOOST converter circuit is also met. Through the control method of the bidirectionalBUCK-BOOST converter circuit, power sharing by a host and a slave in a constant-current mode is realized, switching tube driving signals of two BUCK-BOOST converters are subjected to phase shifting by 180 degrees to realize interleaved parallel connection, ripples of the current on the output side are reduced, and the quality of the output current is improved.

The invention discloses a high-power modular battery formation charging/discharging system, belonging to the field of battery formation charge/discharge. The system comprises an invertible DC (direct current) power module, a DC bus, a conversion charging/discharging module and a central control unit. The invertible DC power module adopts an automatic master-slave current sharing technology, can automatically configure the module number according to the system capacity, realizes automatic current sharing among the modules, and can inversion-feed the redundant electric energy back to the power grid so as to realize master-slave redundant invertible DC power module design; the DC bus transmits electric energy in the system; the conversion charging/discharging module is directly connected with the DC bus; by adopting the automatic master-slave current sharing technology, each module can form a loop independently for production, or multiple modules are freely connected in parallel to form a loop for production; and the central control unit is connected with the invertible DC power module and the conversion charging/discharging module through the bus, and can realize the functions of operation data acquisition, system resource allocation, module alternation coordination, system capacity reduction protection and the like.

The invention provides a vehicle-mounted charger control circuit and method, a charger and an electric vehicle. The vehicle-mounted charger control circuit comprises a filtering and rectification module, a power factor correction module, a half-bridge LLC resonant conversion module and a main control module, wherein the filtering and rectification module is used for converting an input alternating-current electric signal into a direct-current signal after filtering out an electromagnetic interference signal; the half-bridge LLC resonant conversion module is used for enabling switching tubes tooperate in a zero-voltage state so as to realize zero-voltage switching when the charger is charged; and the main control module is used for acquiring a resonant current zero-crossing point of the half-bridge LLC resonant conversion module and a voltage zero-crossing point of mid-point voltage of the half-bridge LLC resonant conversion module in real time. By comparing the potential difference between the two zero-crossing points, resonant network input impedance of the half-bridge LLC resonant conversion module is detected to ensure that the half-bridge LLC resonant conversion module works in an inductive area, and it is ensured that the charger works in a zero-voltage working area no matter load changes or the input voltage changes, thereby reducing harmonic pollution during charging ofthe charger.

The invention discloses an integrated control system of an elevator, which comprises a master control module, an external signal module and a motor, wherein the external signal module and the motor are respectively and electrically connected with the master control module. The integrated control system is characterized in that the master control module comprises a logic control module and a drive control module; the logic control module is used for receiving and processing a signal from the external signal module; the drive control module is used for controlling the operation of the motor; and the master control module further comprises a power-off automatic flat-layer module used for controlling the elevator to be operated to the flat-layer position under emergency circumstances. The integrated control system with the technical scheme has the benefits that the logic control and the drive control to the elevator are organically combined, high integration is achieved, and the function of driving the elevator by a frequency converter is optimized fully.

The invention provides an overhead contact system intelligent ice melting system. The overhead contact system intelligent ice melting system comprises an ice melting control device and N converters; one end of each converter is connected with a direct current overhead contact system, and the other end of each converter is connected with an alternating current network; the converters are used for entering rectification working conditions according to a first control signal and entering inversion working conditions according to a second control signal; the ice melting control device is used for obtaining the first control signal and the second control signal and sending the first control signal and the second control signal to the converter corresponding to an section needing ice melting, wherein the first control signal and the second control signal both include ice melting current values. Thus, energy circulation is formed among the converters in the rectification working conditions, the section needing ice melting of the direct current overhead contact system and the converters in the inversion working conditions and Between corresponding sections of the alternating current network, and current of the section needing ice melting of the direct current overhead contact system is not less than the ice melting current values.