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2555results about "Harmonic reduction arrangement" patented technology

Multipurpose, universal Converter with battery control and real-time Power Factor Correction.

The Electric Power Converter has the qualifications for an uninterruptable power supply, battery management, energy conversion, micro-grid formation, Power Factor Correction including Total Harmonic Distortion correction in real time. Uninterruptable power supply's use is for always-on, real-time, all-time, reduced distortion with functions of load reduction and management during peak load events. The Electric Power Converter as well has the ability to provide maintenance for most types of batteries including charging and discharge regiments to increase the overall lifetime of a battery, the maintenance, incorporating restorative functions that can refurbish dead batteries or can further increase the overall efficiency and useful function of weaker/aged/defective batteries. Energy conversion capabilities allow for the conversion of AC or DC to AC or DC with high efficiency and ability to actively vary the frequency in accordance to the required parameters. The Electric Power Converter is able to establish and sustain a micro-grid with multiple and varying sources of power generation and load conditions. The Electric Power Converter is achieving dynamic, real-time, interactive Power Factor Correction (PFC) function with advanced voltage harmonic distortion correction with a high efficiency ratio. The Electric Power converter is designed to function with the emerging Smart Grid technologies and provide an overall higher level of operating efficiency and higher quality of electrical power.
Owner:3DFS L L C

Super capacitor energy storage type power quality compensator

The invention relates to a super capacitor energy storage type power quality compensator. A system structure comprises a compensation transformer, a series compensator, a parallel compensator, a super capacitor group, a current foldback circuit, a bidirectional DC/DC chopper circuit, a signal sampling circuit, a control circuit, a drive circuit, a human-computer interface and corresponding auxiliary circuits, which form a three-phase three-wire system topological structure. By utilizing the excellent characteristics of great power density, high charging and discharging speed and long cycle life of a super capacitor, the super capacitor energy storage type power quality compensator is matched with the DC/DC chopper circuit to form an energy storage control system which plays the roles of adjusting power and stabilizing the voltage of a direct current bus in work. The invention also has the functions of dynamic voltage recovery, active filter and reactive compensation and can ensure that a load can obtain rated sine voltage and the current of a grid is sine current with the same direction (unit power factor) with that of a voltage fundamental wave positive sequence active component, thereby comprehensively improving the quality of power. The invention has positive generalization and application value for both the public grid and users.
Owner:TIANJIN UNIV

Method for injecting harmonic voltage to restrain harmonic current of PMSM (permanent magnet synchronous motor)

The invention provides a method for injecting a harmonic voltage to restrain a harmonic current of a PMSM (permanent magnet synchronous motor), which is characterized in that a ring to restrain the harmonic current is added to realize the closed-loop control for the harmonic current on the basis of extracting harmonic current components in the PMSM in real time, thus calculating to obtain harmonic voltage components which are required to be injected to restrain 5-order and 7-order harmonic currents of the PMSM; and then the obtained harmonic voltage components are injected into a three-phase control voltage in a speed control system of the PMSM so as to offset the 5-order and 7-order harmonic components in a motor current when the PMSM runs, thereby reaching the purpose of restraining the 5-order and 7-order harmonic currents. The method is used to solve the technical difficulty that current ZCP (zero crossing point) is required to detect accurately in a traditional mode to restrain the harmonic current, remarkably improves the current waveform of the motor, effectively restrains the 5-order and 7-order harmonic currents caused by the nonlinear characteristics of an inverter and the air-gap field distortion of the motor, effectively reduces the additional loss caused by the 5-order and 7-order harmonic current components, reduces the electromagnetic torque and the revolving speed pulse of the PMSM and improves the running efficiency and the running reliability of the PMSM.
Owner:CHONGQING UNIV

Battery energy storage system based power conversion system and control method thereof

The invention relates to a battery energy storage system based power conversion system and a control method thereof. The power conversion system comprises a battery energy storage system, a bidirectional DC/DC (direct-current) converter, a grid-side current transformer, a filter circuit and an isolated voltage transformer. The battery energy storage system is in parallel connection with a direct-current bus of the grid-side current transformer through the bidirectional DC/DC converter; the grid-side current transformer, the filter circuit and the isolated voltage transformer are connected in sequence; and the isolated voltage transformer accesses to a power grid. The control method includes sequentially monitoring the battery energy storage system, the bidirectional DC/DC converter, the grid-side current transformer, the filter circuit and the isolated voltage transformer by a control circuit. Since the battery energy storage system utilizes battery cells connected in series and is in parallel connection with the common direct-current bus through the bidirectional DC/DC converter, circulation among battery packs is avoided, and capacity expansion of the system is facilitated. Further, by the aid of the monitoring control strategy for SOC (super capacitor state of charge) of the battery energy storage system and battery end voltage, excessive charge or discharge state of the battery energy storage system is avoided, service lives of the battery packs are prolonged, and comprehensive service cost is lowered.
Owner:CHINA ELECTRIC POWER RES INST +2

Virtual synchronous generator control method based on self-adapting moment inertia

The invention relates to a virtual synchronous generator control method based on self-adapting moment inertia. The output of a grid-connected inverter in distributed generation is connected with an AC bus of a filter capacitor Cf which is in parallel connection with the grid-connected inverter through a filter inductor Lf; sampling is performed to obtain the output power, the voltage and the current of an output interface of an inverter; the output power, the voltage and the current are transmitted to a VSG (virtual synchronous generator) algorithm; the calculated terminal voltage of a VSG stator is sent to be controlled by a voltage external loop; the voltage external loop adopts a PI controller to stably load the voltage; the current of the filter capacitor is sent to be controlled by a voltage internal loop; the voltage internal loop adopts a PI controller to increase the response speed; a control signal is outputted by a voltage-current dual-closed loop to the grid-connected inverter; the moment inertia in the virtual synchronous generator in the control method can be changed in a self-adapted manner according to the change capacity of the system frequency. Through the adoption of the virtual synchronous generator control method disclosed by the invention, the transient state process of the system is reduced; a great deal of harmonic waves in the system is offset; the stability of frequency and the stability of voltage can be improved; the adaptability and the power supply quality of a micro-electrical network are improved; the problem that in a conventional method, the output frequency is reduced, is solved.
Owner:SHANGHAI UNIVERSITY OF ELECTRIC POWER

Electrified railway traction power supply and energy storage device and method thereof

The invention discloses an electrified railway traction power supply and energy storage device and a method of the electrified railway traction power supply and energy storage device. The energy storage device is connected between a feeding arm alpha or feeding arm beta at the output end of a traction transformer and a steel rail, or two energy storage devices are connected between the feeding arm alpha and the steel rail and between the feeding arm beta and the steel rail respectively, wherein the energy storage device is arranged in a traction substation. The energy storage device comprises a control unit, an isolation transformer, a PWM current transformer, an energy transformation circuit and an energy storage element, wherein the PWM current transformer, the energy transformation circuit and the energy storage element are connected in sequence, and the control unit is used for carrying out calculation according to the voltage, current and direction of the feeding arm alpha and/or feeding arm beta to complete control over the PWM current transformer and the energy transformation circuit and achieve energy exchange between the energy storage device and the feeding section connected with the energy storage device. The electrified railway traction power supply and energy storage device can fully recycle locomotive braking feedback electric energy, improve the energy utilization ratio of a traction power supply system, reduce the installation billing capacity of the traction transformer, reduce cost and absorb and store energy even in electricity valleys, has the effect of peak load shifting and further has the functions of dynamic reactive-power compensation and low-order harmonic suppression.
Owner:CSR ZHUZHOU ELECTRIC LOCOMOTIVE RES INST

Multi-functional grid-connected inverter and grid-connected inverter control method

The invention belongs to the field of electrical engineering, distributed power generation and power quality control, and aims to provide a multi-functional grid-connected inverter and a grid-connected inverter control method. The grid-connected inverter comprises a direct-current bus bar with a capacitor and three sets of single-phase full-bridge inverter circuits sharing the direct-current bus bar, the direct-current output ends of a distributed power supply or a grid-connected energy-storing generating set are connected to both ends of the capacitor of the direct-current bus bar, the output of each set of single-phase full-bridge inverter circuit is connected to a filter, and the output ends of each filter are connected with a distribution network of the 380V voltage class through a single-phase step-up isolation transformer. According to the invention, the grid-connected inverter equipment is effectively utilized to carry out effective control on the power quality of points of interconnection, so that the grid-connected inverter is multi-purpose and multi-functional, the cost performance of the grid-connected inverter is enhanced, the investment, operation and maintenance cost of a system can be reduced, and the reliability of the system can be enhanced. The principle of the provided control scheme is clear, and the control scheme is highly operable and reliable in operation.
Owner:ZHEJIANG UNIV

Control method of alternating voltage sensorless high voltage direct current transmission converter

The invention discloses a control method of an alternating voltage sensorless high voltage direct current transmission converter, belonging to the technical field of electrical equipment and comprising the following steps: establishing a stator resistor and an inductor for a virtual motor; building relative position relationships among a current vector, a voltage vector and a flux linkage vector, and analyzing a vectorgram; establishing a converter and flux linkage mathematic model, and calculating a virtual flux linkage vector of a system to obtain a power feedback quantity of the system; acquiring an active control signal and a reactive control signal of the system through a direct power control algorithm, and generating a PWM trigger converter for respectively and independently controlling the active power and reactive power of the system; and utilizing MATLAB simulation software to set up a system model for verifying, and obtaining a systematic selection device when the verification is successful. By utilizing Matlab/Simulink to set up a corresponding simulation model, the designed method is verified to have rapid response speed, the voltage and power after startup can still reach stable values after about 2 power frequency periods and have high steady state precision.
Owner:SHANGHAI JIAO TONG UNIV

Water, wind, solar and biomass multi-energy integrated complementary power generation method and device

The invention relates to a renewable energy source integrated complementary power generation technology for a distributed power supply and provides a multi-energy integrated complementary power generation method and multi-energy integrated complementary power generation device consisting of water energy, wind energy, solar energy and other renewable energy sources. According to the method, the water energy serves as a main body, the peculiar mountain valley wind of a hydropower station is fully utilized, the solar energy, the biomass energy and other renewable energy sources which can be relatively concentrated are locally utilized and are gathered around the hydropower station, a low-voltage alternating current bus [W1] of the hydropower station serves as a grid-connected access point, and a water, wind, solar and biomass multi-energy integrated complementary power generation system which takes water and electricity as the center and takes the water and wind complementation as the basis. According to the device, a hydropower station [G1] serves as a main body, the electric energy generated by power generation subsystems [G2], [G3], [G4] and [G5] is subjected to full power conversion and is connected to the [W1] in a grid-connected mode, the original switching device and grid line of the hydropower station are utilized, and a multi-type renewable energy source integrated complementary distributed power supply which can supply power in a grid-connected mode and independently operate is formed.
Owner:陈巍 +1

Control method for single-phase grid-connected lcl inverter

A method of controlling the grid-side current of a single-phase grid-connected converter having an LCL filter connected between the output of the converter and the grid. The method includes measuring a grid voltage (vS) and at least one signal in a group of signals consisting of a grid-side current (i0), a converter-side current (i1) and a capacitor voltage (vC0). The method includes estimating the fundamental component (vS,1) of the grid voltage (vS), forming a grid-side current reference (i0*), a converter-side current reference (i1*) and a capacitor voltage reference (vC0*) for the grid-side current of the LCL filter using the fundamental component of the grid voltage (vS,1), forming estimates for the non-measured signals in said group of signals, forming a grid-side current difference term (ĩ0), a converter-side current difference term (ĩ1) and a capacitor voltage difference term ({tilde over (v)}C0) from the differences between the references and measured/estimated values of said signals, forming an injection term for damping the resonance of the LCL filter by using an active damping injection mechanism (ADI), in which the grid-side current difference term (ĩ0), the converter-side current difference term (ĩ1) and the capacitor voltage difference term ({tilde over (v)}C0) are used, forming an estimate of harmonic distortion term ({circumflex over (φ)}) using the grid-side current difference term (ĩ0), and controlling the output voltage (e) of the converter on the basis of the grid voltage, formed injection term and formed estimate of the harmonic distortion term ({circumflex over (φ)}) to produce a grid side (i0) current corresponding to the current reference.
Owner:MARICI HLDG THE NETHERLANDS BV

High-efficiency stable multifunctional single-stage photovoltaic single-phase grid-connected control method

The invention discloses a high-efficiency stable multifunctional single-stage photovoltaic single-phase grid-connected control method, and belongs to the technical field of photovoltaic power generation control. The method is characterized in that: the method adopts a high-speed digital signal processor and applies a C language dynamic fixed-point algorithm to form a high-performance control algorithm of a whole grid-connected control system; the method adopts a single-stage grid-connected control structure and a quick smooth maximum power point tracking method to directly transmit the maximum energy sent by a photovoltaic array to a local urban power grid through first-stage DC/AC transformation; the harmonic and idle work produced by a local load can be compensated by adopting an FBD method, so the method is favorable for improving the electrical energy quality of the local power grid; and a proportional resonant converter is used to implement precise closed-loop control for the grid-connected current so that the photovoltaic grid-connected current and the commercial single-phase voltage are totally synchronous while implementing maximum power point tracking of the photovoltaic array. The power factor is high, the system efficiency is high, the operation of the whole system is safe and reliable, and the aberration rate of the grid-connected current harmonic is lower than 3 percent.
Owner:WUXI SLD POWER TECH

Electric locomotive non-power-off neutral section passing-electric energy quality comprehensive compensation device and method

The invention relates to an electric locomotive non-power-off neutral section passing-electric energy quality comprehensive compensation device and method, which belongs to the technical field of railway transport equipment and electric electronics. The device comprises a controllable transfer switch, a single-phase step down transformer, a single-phase step down transformer with a middle tap, a two-phase back-to-back converter sharing a DC-side capacitor, a circuit breaker switch, four position sensors and three electric quantity sensors. In the method, when the electric locomotive passes the neutral section, the controllable transfer switch is turned off, and the device works in a non-power-off neutral section passing mode to perform control on amplitude and phase of the neutral section voltage and enable the electric locomotive to pass the neutral section with load in a non-power-off manner. Without locomotive passing, the controllable transfer switch is closed, and the device works in an electric energy quality comprehensive compensation mode and has functions of active power transfer as well as inactive power and harmonic compensation. Through the device, the problems relating to electric energy quality of a traction substation and neutral section can be comprehensively solved based on the traditional traction power supply mode.
Owner:TSINGHUA UNIV +1

Grid-connected current control method for combined single-phase two-stage photovoltaic generation system

The invention discloses a grid-connected current control method for a combined single-phase two-stage photovoltaic generation system. The single-phase photovoltaic generation system is of a two-stage structure and comprises a first-stage BOOST up circuit link and a second-stage single-phase full-bridge inverter circuit link. The single-phase full-bridge inverter circuit link adopts a double-closed-loop control strategy and comprises an outer loop which is a direct-current bus voltage loop and an inner loop which is a grid-connected current loop and further utilizes voltage forward feed control of a power grid. The BOOST up circuit link is used for realizing boosting voltage of a photovoltaic battery module to a direct-current bus voltage reference value while realizing maximum power point tracking. Besides, the single-phase full-bridge inverter circuit link is used for realizing stabilization of the direct-current bus voltage and synchronization of frequency and phase of system output current and voltage of the power grid. The grid-connected current control method for the combined single-phase two-stage photovoltaic generation system has the advantages of excellent stability, flexibility in dynamic response, low content of low-order harmonics, high interference resistance, good robustness, high reliability and the like.
Owner:SOUTHEAST UNIV

Electric energy regulation device and method for electrified railways

The invention discloses an electric energy regulation device and method for electrified railways. The electric energy regulation device is in bridging connection between two power supply arms of a traction transformer. The electric energy regulation device comprises isolation transformers, single-phase back-to-back PWM converters, an energy conversion circuit, an energy storage element and a control unit. The control unit carries out calculation according to voltages, currents and directions of the power supply arms alpha and beta and completes control over the PWM converters and the energy conversion circuit. Consequently, energy conversion between the power supply arms alpha and beta and the energy conversion between the energy storage element and the power supply arm alpha or the power supply arm beta can be achieved. The electric energy regulation device is capable of fully recycling and utilizing braking feedback electric energy of a locomotive through transfer, storage and release of the electric energy, improves the energy utilization rate of a tractive power supply system, reduces the installation billing capacity of a traction transformer, can deal with the negative sequence, idle work and harmonic waves of a traction substation, avoids traction force losses and speed losses, caused by electric phase separation, of a train and can also have the effects of peak load shaving and voltage stabilization and can be used as an emergency power supply.
Owner:CSR ZHUZHOU ELECTRIC LOCOMOTIVE RES INST
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