68results about How to "Solve power quality problems" patented technology

The invention relates to a single-phase universal electric energy quality controller for power supply for electrified railways, and belongs to the technical field of flexible AC power transmission and distribution; the invention comprises a single-phase multi-coil transformer composed of a primary coil and n secondary coils, so that the secondary coils of the transformer can be connected in parallel with n voltage sources of current transformers; n capacitors are connected with n voltage source current transformers, so as to form a single-phase chain-type H-bridge current transformer with n chains; the AC terminal of the H-bridge current transformer is directly connected with the traction grid through a reactor. The invention has the functions of active power control, reactive power compensation and harmonic compensation, so as to resolve three-phase voltage unbalance, voltage fluctuation, low power factor and harmonic pollution and so on that exist in ER traction transformer stations, effectively lower the capacity of traction transformers, increase ER transport capacity and transportation capability. Moreover, the invention is characterized in small occupied area, little loss and low cost, in order to gain perfect harmonic suppression characteristics and dynamic response features, and provide convenience in industrial production and improve device reliability.

The invention discloses a distributed power quality conditioner and a method for controlling the same. The distributed power quality conditioner comprises one or more series compensation devices and parallel compensation devices, wherein each of the series compensation devices and the parallel compensation devices comprises a central controller; the series compensation devices and the parallel compensation devices do not share a direct current bus; and when the series compensation devices and the parallel compensation devices are used together, a management center is configured for acquiring the voltage of an electric network and load current information to determine the failure type of the electric network, and coordinately operating all series compensation devices and all parallel compensation devices.

The invention provides a micro-grid structure and a power quality control method thereof. The micro-grid structure comprises a plurality of distributive micro sources and a common busbar. The distributive micro sources are parallelly connected to the common busbar through corresponding feeder lines and respectively connected with nonlinear loads and linear loads, and the common busbar is connected with the nonlinear loads and the linear loads. A first switch is in parallel connection with an isolation transformer to control an input state of an inverter for compensation. A static switch which is an option switch is arranged at a point of common coupling, and option ends of the static switch correspond to a large power grid side and a ground terminal respectively.

The invention discloses a scattered type power quality regulation system. The scattered type power quality regulation system comprises one or more series-wound type compensation apparatus and shunt-wound type compensation apparatus, wherein each of the series-wound type compensation apparatuses and shunt-wound type compensation apparatuses comprises a central control unit; and direct current buses are not shared between the series-wound type compensation apparatuses and shunt-wound type compensation apparatuses. When the multiple series-wound type compensation apparatuses and shunt-wound type compensation apparatuses are jointly used, a management center is provided, wherein the management center judges power grid fault types by sampling power grid voltages and load current information so as to realize coordinated operation of the respective series-wound type compensation apparatuses and the shunt-wound type compensation apparatuses.

The invention discloses an electric energy quality control system and method of a low voltage distribution network. The system comprises an electric energy quality active compensation unit, a system controller, a passive reactive compensation unit and a commutation switch block; the electric energy quality active compensation unit has functions of harmonic wave treatment, reactive compensation andthree phase imbalance adjustment; the passive reactive compensation unit realizes reactive compensation and has the three phase imbalance treatment function to certain extent; the commutation switchblock adjusts rules of three-phase imbalance regularly of the low voltage distribution network with short circuit among phases; and the system realized ordered high-efficiency operation of the electric energy quality active compensation unit, the passive reactive compensation unit and the commutation switch block. Different electric energy quality problems of the low-voltage distribution network can be solved effectively, the treatment effect is ensured, and the system loss is minimized as possible.

The invention provides a hierarchical distributed photovoltaic access power distribution network voltage control system and method. The system comprises a feed line voltage controller and local voltage controllers. Each local voltage controller is directed to a local photovoltaic power station. The feed line voltage controller is directed to the whole feed line and coordinates and controls each local voltage controller on the feed line. If the local voltage controller cannot solve the local voltage off-limit problem, the local voltage controller uploads the operation state of the local photovoltaic power station to the feed line voltage controller to which the local voltage controller belongs, and the feed line voltage controller calculates the control amount and issues the control instruction according to electrical information uploaded by the local voltage controller. According to the instruction sent by the feed line voltage controller, the local voltage controller calculates the control amount of the local area, and controls reactive power output of a local reactive power compensator and a local photovoltaic inverter, so to achieve voltage off-limit control in the feed line area. The voltage off-limit problem caused by the photovoltaic access is solved, and the power distribution network voltage distribution meets engineering operation requirements.

The single-phase active electric power filter of using analog cascaded controller includes control circuit, and connected main circuit. The control circuit includes first and second proportional plus integral controllers, multiplier, subtracter, feedforward controller, and adder. Principle of the invention is as following: using voltage loop composed of these analog parts adjusts DC voltage of bus in two control loops including external current loop as well as generates current of reference power supply; using current loop reduces interference effect, and tracks current of reference filter; finally, generating command signal for main circuit to generate compensating current. Using analog devices in low cost without need of microprocessor, the invention realizes active electric power filter capable of restraining harmonic, and correcting power factor. The invention reduces cost of the filter, and has no mathematic burden for calculating fundamental wave and harmonic of load current.

The invention discloses a method for detecting an island of a grid-connected photovoltaic power system on the basis of the electric energy quality constraint. A detection unit is used for comparing an operating voltage of a grid-connected point of the grid-connected photovoltaic power system with a rated voltage of the grid-connected point to further periodically change a trigger pulse duty ratio of a Boost circuit in the grid-connected photovoltaic power system so that an output voltage of a grid-connected photovoltaic inverter is regulated according to a designated proportion, then comparing a voltage variable quantity of the grid-connected point of the grid-connected photovoltaic power system, which is measured at the moment, with a set island detection voltage variable quantity threshold value and finally determining whether the island occurs. According to the invention, not only can an undetectable region existing in a passive detection method when an output power of the grid-connected photovoltaic inverter is matched with a load power be avoided, but also the problem of electric energy quality, which is caused by the existing active detection method, can be solved. The method disclosed by the invention has strong adaptability to the operation of a power grid and is convenient for actual engineering application.

The invention relates a device and a method for optimizing electric energy quality of a photovoltaic poverty-alleviation rural power grid based on cooperative self-government. According to the device and the method, the problems that conventional electric energy quality processing devices are relatively single and do not have ideal treatment effect in rural power grids of existing photovoltaic poverty-alleviation projects can be solved. The device comprises electric energy quality coordinating controllers and a single-phase electric energy quality processing device, wherein electric energy quality coordinating controllers are connected to phases A, B and C of a total inlet wire position of a low-voltage area network of rural power grid and are used for detecting electric energy quality information and sending electric energy quality information to a control circuit of the single-phase electric energy quality processing device; and single-phase electric energy quality processing device comprises an inverter circuit and control circuit, an energy storage device is connected to a direct current side of the inverter circuit, an alternate current side of inverter circuit and control circuit are connected with a phase line and a null line in the phases A, B and C, and control circuit is used for detecting electric energy quality information of an access point, simultaneously receiving energy quality information of electric energy quality coordinating controllers and controlling an IGBT (Insulated Gate Bipolar Translator) switch device to output current. According to the device and method, electric energy quality operation level of low-voltage area network is remarkably improved, operation efficiency and economy of a power distribution network are improved, and meanwhile, electric energy quality construction and transformation costs of low-voltage area network are lowered; and device and method are generally applicable to vast rural power networks.

The invention provides an in-phase traction power supply and power generation system and a control method, and relates to the technical field of electrified railway power supply. The secondary side ofa traction transformer is connected with a traction bus; the head ends of the n uplink feeders are connected with the traction bus, the tail ends of the n uplink feeders are correspondingly connectedwith the n uplink contact networks, the head ends of the m downlink feeders are connected with the traction bus, and the tail ends of the m downlink feeders are correspondingly connected with the m downlink contact networks; the input end of a coordination controller is connected with the measuring end of a voltage transformer and the measuring end of the current transformer at the same time, andthe output end of the coordination controller is connected with the control end of a new energy power generation device. The AC output end of the new energy power generation device is connected withthe traction bus. According to the invention, nearby consumption of new energy is facilitated, green development of a railway system is promoted, related electric energy quality problems are avoided,and extra economic income can be brought.

The invention discloses an electrified railway double-current system traction power supply system and a control method thereof, and relates to the technical field of electrified railway power supply. The electrified railway double-current system traction power supply system comprises a three-phase high-voltage bus HB, a traction transformer TT, an in-phase compensation device CPD, an alternating-current bus AB, a direct-current bus DB and a measurement and control system MCS which are arranged in the double-current traction substation DCS. The secondary side of the traction transformer TT is connected to an alternating current bus AB in parallel, and the direct current side of the alternating current-direct current-alternating current converter ADA is connected to a direct current bus DB in parallel, so that required power is provided for a train, and alternating current and direct current power supply at the same place is realized; the measurement and control system MCS is composed of a voltage transformer VT, a voltage transmitter VD, a current transformer CT, a diverter RW and a controller CD and can calculate alternating current load power and direct current load power, the generated negative sequence power is compared with the three-phase high-voltage bus negative sequence allowable quantity, the output power of a converter is controlled in real time, the negative sequence generated by an electrified railway is compensated, and the compensated negative sequence meets the compensation target requirement.

The invention relates to a hybrid three-phase power balancing device and method based on inter-phase capacitors. A system bus close to a system power side is connected with an active power balance inverter unit through the output reactance, the active power balance inverter unit is connected to a PWM pulse signal port, an output current transformer is arranged between the output reactance and the system bus, the output current transformer is connected to an output current sampling port, a system bus between a system power supply and the active power balance inverter unit is connected to a system voltage transformer, and the system voltage transformer is connected to a system voltage sampling port. A system bus close to the load side is connected to a passive balance unit, the passive balance unit is connected to a passive control signal port, a system bus between a load and the passive balance unit is provided with a load current transformer, and the load current transformer is connected to a load current sampling port. The compensation precision is good, the loss is small, the service life of the equipment is prolonged, and the stability and the reliability of equipment operation are improved.

Provided is a feeder interconnection converter. One end of a first controlled power supply (30) is connected with a first feeder unit power supply (10) through an isolation transformer (14), the other end of the first controlled power supply (30) is connected with a direct-current bus of a second controlled power supply (32) and a distributed power generation or energy storage unit (33) through a direct-current bus voltage stabilizing capacitor (31), and the second controlled power supply (32) is connected with a second feeder unit power supply (20) through an isolation transformer (17). Through control of the first controlled power supply (30), the second controlled power supply (32) and the distributed power generation or energy storage unit (33), interactive transfer of active power or reactive power among the first feeder unit power supply (10), the second feeder unit power supply (20) and the distributed power generation or energy storage unit (33) is achieved so as to improve electricity quality of the first feeder unit power supply (10) and the second feeder unit power supply (20).

The invention discloses an equivalent locomotive-traction network coupling test platform and a test method thereof. The phenomena, including harmonic resonance, unstable harmonic wave, low frequency network pressure vibration, and the like, which frequently occur on the railway site can reemerge through the test platform, and meanwhile, the impedance frequency characteristics of locomotive / traction network can be tested and a technical support is supplied for solving the power quality problem of the high-speed rail traction power supply.

The invention provides a power regulator and method based on a dq0 conversion method, SVPWM and hysteresis control. The power regulator combines a series active filter and a parallel active filter, sothat the advantages of serial and parallel active filters can be fully used in power system applications. The power regulator has an integrated power quality regulation function. The dq0 conversion method is used to detect harmonic current. Compensation current is compared with actual compensation current, and the comparison result of compensation current and actual compensation current is used as the input of a hysteresis comparator. The input generates a PWM signal which turns a switch on and off, and then compensation current is adjusted. The dq0 conversion method is used to detect harmonic voltage. The PWM signal is generated and comes into the series active filter to control on-off of the inverter switch, and a compensation voltage signal is output and injected into a power grid to compensate for distortion voltage. UPQC uses the dq0 conversion method, an SVPWM algorithm and hysteresis control, and makes full use of the advantages of series and parallel active filters.

The invention discloses a novel system and method for managing electrification railway electric energy quality, wherein the system comprises a traction transformer with a filter winding, a sensing filter circuit, an MMC compensation system, an MMC controller, a voltage and electric current measuring apparatus; the traction transformer high voltage side is connected to electric network; a traction side is connected to a traction arm of an electric locomotive for providing electric power for the electric locomotive; and a low voltage compensation side is connected to the sensing filter circuit and the MMC compensation system. The MMC compensation system is constituted by two connected to single-phase MMC traction arm groups; direct current sides of the two MMC traction arm groups are connected together through a serial capacitor; and a grounding point of the MMC compensation system is led out in the geometric midpoint of the serial capacitor. With the method, harmonic waves are dynamically tracked and suppressed through the MMC technology and the sensing filter technology; active power balance and reactive power adjustment are performed to the load at two traction sides, thereby achieving the purposes of managing the harmonic waves, reactive power and negative sequence of the traction transformer high-voltage side of the electrification railway.

The present invention relates to a circuit voltage-based comprehensive power quality management device and a method. Based on the calculation of the fundamental waves of a positive-sequence active current, a compensation target value formed through the superimposition of a harmonic current, a reactive current and a negative-sequence active current is directly obtained. Meanwhile, based on the control algorithm of a circuit voltage, a duty ratio outputted by PWM waves is directly calculated. The complex calculation process of the space vector algorithm and other algorithms is simplified. Meanwhile, the calculated duty ratio is adopted as a basis for the generation of a trigger pulse sequence. An insulated gate bipolar transistor (IGBT) drive circuit is arranged to control the on / off state of an IGBT transistor, so that the output of an inverter unit is controlled. The compensation of a target value is realized. The device and the method have the functions of eliminating the harmonic waves of a power grid, compensating the reactive power of the system, and balancing three-phase loads. Meanwhile, the common power quality problem of the power grid can be simultaneously and comprehensively solved. The power quality of the power grid is improved and the power grid is purified. The electricity environment of the power grid is optimized. The equipment operation reliability and the operation reliability of the power grid are improved.

The invention discloses a uniform power quality controller. The uniform power quality controller comprises a series connection unit, a parallel connection unit and an energy taking unit. The series connection unit comprises a series connection converter and three single-phase transformers, the parallel connection unit comprises a parallel connection converter, the energy taking unit comprises a parallel connection converter, and the series connection unit is connected with the alternating current side of the parallel connection unit through a three-phase feeder line. According to the uniform power quality controller, the energy taking unit is added, under the condition of normal voltage, a power supply connected with the three-phase feeder line maintains public direct current bus voltage through the parallel connection unit. When voltage slag happens, a power supply connected with the energy taking unit is in a connected state, the public direct current bus voltage is maintained through the energy taking unit, and the voltage slag is continuously compensated, so that the power quality of load voltage is not influenced, the uniform power quality controller does not need to be provided with an additional large capacity energy storage device, and device cost is effectively reduced.

The invention discloses an inductance integrated hybrid railway power flow controller. A public supply network is changed into both alpha and beta phases of a railway traction network by a three-phase V / v transformer and the alpha and beta phases are respectively connected with alpha-phase and beta-phase LC (Inductance / Capacitance) coupling compensation arms; inductances of the alpha-phase and beta-phase LC coupling compensation arms are integrated into a secondary side of the V / v traction transformer by a non-orthogonal decoupling technology to form alpha-phase and beta-phase integrated inductive windings; the alpha-phase and beta-phase LC coupling compensation arms are respectively connected with two output ends of a back-to-back converter by first and second step-down transformers. The inductance integrated hybrid railway power flow controller adopts the non-orthogonal decoupling technology to integrate the inductances of the coupling arms into the transformer windings and the occupied area of a high-speed railway active compensation system can be reduced; due to adoption of the technical scheme of combining active and passive systems, the capacity of the converter is greatly reduced. The inductance integrated hybrid railway power flow controller is an electrical railway electric energy quality control system with high cost performance.

The invention provides a through-type traction power supply system, relating to the technical field of traction power supply. A master transformer station CS<M> comprises a step-down transformer T0, the secondary side of which has more than one winding, and a super compensation system, the secondary side of which has more than one winding; the master transformer station CS<M> is used as a voltagesource, other transformer stations with a step-down transformer and a three phase-single phase cascaded converter N are used as system current sources, wherein the master transformer station CS<M> provides power through a three phase-single phase traction transformer TM, the structure of three phase input and single phase output is adopted, the primary side of the step-down transformer T0 is connected with a three phase power grid, the secondary side has more than one group of winding, three phases of output of the more than one group of winding are separately connected with a reactor in series and then are connected with an input end of corresponding super compensator SCN so as to form a parallel super compensation system SC; and the input end of a master controller MC is connected with athree phase network current, a three phase power grid voltage and a support capacitor voltage of the super compensator separately, and the output end of the master controller MC is connected with thecontrol end of the super compensation system SC.

The invention discloses a power quality control system based on an active filtering technology, and is to solve the problems that many devices in a power grid cause power quality problems of grid power factor reduction and harmonic enlargement and the like, and how to carry out analysis on working personnel to obtain a waveform adjustment value, and by adjusting lines of the waveform through the waveform adjustment value, the problem that existing power grid data monitoring cannot be displayed and adjusted according to the staffs is solved. The system comprises an active filter. The active power filter is composed of an active power filter module and an intelligent control module; reactive power and harmonic waves are detected in real time, and reactive power compensation and harmonic wavefiltering can be dynamically carried out, so that the electric energy quality problem is solved; and by adjusting the lines of the waveform corresponding to the parameter data, the staffs can conveniently check the waveform better.

The invention relates to an energy coordination method for ensuring power quality in a low voltage region. The method comprises the steps that 1) a smart power distribution platform is constructed; 2)an information service platform is constructed, wherein the information service platform comprises a basic information processing module, a load forecasting module and an information release module;and 3) a regulation and control management platform which comprises an intelligent operation and maintenance platform, a coordination and optimization platform and an interactive service platform is constructed. According to the scheme provided by the invention, an energy coordination platform of a smart power grid, information interconnection and a regulation and control terminal is comprehensively established; the consumption of clean energy can be effectively promoted; the use efficiency of energy is improved; the problem of seasonal fluctuations of power quality in the low voltage region is solved; national policies are combined; and the method can be gradually promoted to develop in the direction of virtuous circle and in the direction of comprehensive win-win of environment improving, power grid optimizing and resident income increasing.

The invention relates to an electric energy quality comprehensive optimization control system and method for a low-voltage power distribution network. The electric energy quality comprehensive optimization control system for the low-voltage power distribution network comprises an optimization control module which comprises a control unit and an effect inspection unit, wherein the control strategies for solving various electric energy qualities is stored in the control unit, the effect inspection unit is used for inspecting the treatment effects of the control strategies, judging whether the treatment effect reaches an expected standard or not and ending the control of the control system if the treatment effect reaches the expected standard, if the treatment effect does not reach the expected standard, the control unit continuously outputs the related control strategies until the treatment effect reaches the expected standard, and the control is ended. A plurality of compensation modules are dispersed at different positions of a same power distribution area, and each compensation module is used for carrying out related compensation on the low-voltage power distribution network according to the control strategy. According to the present invention, various electric energy quality problems at various positions of the low-voltage power distribution network can be solved.

The invention discloses a PWM rectifier with consideration of power quality control. The PWM rectifier comprises a central controller, at least one slave controller, and at least one rectifier main circuit. In addition, the controlling method includes: the slave controller introduces power feedward decoupling into a power inner-loop controller based on a grid need to control the rectifier main circuit to carry out reactive compensation and / or harmonic suppression. The PWM rectifier and the controlling method have the following advantages: an energy absorption mode and an energy feedback mode are realized and reactive compensation and / or harmonic suppression can be carried out in the two kinds of modes, so that a primary objective of completing active power transmission of a direct-current side can be achieved; and a power quality problem with common point existence can be solved by fully using the residual capacity of the PWM rectifier and energy storage capacity of the energy storage type load.

The invention relates to an auto-transformer with variable specific voltage regulation and current compensation and a method thereof, a bidirectional soft switch (formed by inversely connecting an IGBT and a diode in parallel) is adopted to replace a mechanical switch, and the variable-ratio control on the voltage of a power grid is realized by changing the duty ratio D set by a PWM controller andthe transformation ratio N1 / N2 of the transformer. Furthermore, under the condition that power grid voltage fluctuation is caused by various reasons on the power grid side, the voltage is maintainednot to be distorted. The variable specific voltage regulation current compensation hybrid autotransformer based on the active power filter is a novel transformer, combines a traditional transformer with a power electronic technology, has good controllability, and can be used for solving the ubiquitous problem of electric energy quality at present. According to the transformer, stepless voltage regulation voltage compensation and current compensation functions of a voltage side can be realized at the same time.

The present invention provides an intelligent energy-saving potential and electric energy quality diagnostic device for an individual line user based on double TMS320F2812. The device continuously monitors and records energy consumption data of the individual line user online, and the recorded data is imported to a mobile memory via an external interface, and analyzed in detail by software of a host computer to obtain an energy-saving potential report of the individual line user. On the basis of the newest double-DSP configuration, high-precision A / D sampling technology, large-capacity storage technology and friendly man-machine interaction technology, the diagnostic device employs a scientific measuring means to ensure that electric energy data of the user to be detected is accurately automatically monitored and recorded online in real time; the diagnostic device is characterized by high sampling speed, calculation precision and intelligent level and easy operation; and the diagnostic device has a remote communication function, and thus, can be applied to enterprises information analysis and management systems of a higher level.

The invention discloses a control method for a virtual active power filter of an alternating-current and direct-current hybrid microgrid. The control method adopts predictive current control for performing energy exchange on the virtual active power filter, an alternating-current bus Ua, an alternating-current bus Ub, an alternating-current bus Uc, an alternating-current microgrid and a large power grid in the virtual active power filter of the alternating-current and direct-current hybrid microgrid. Through the control method, the virtual active power filter of the alternating-current and direct-current hybrid microgrid can work in three modes of the active power filter, rectification and inversion; the active power filter can be used for filtering harmonic waves of the hybrid microgrid through compensation reactive power, so that the electric energy quality is improved; and the rectification mode and the inversion mode can enable the alternating-current and direct-current hybrid microgrid to carry out energy bidirectional flow, and also can filter the harmonic waves of the hybrid microgrid through the compensation reactive power, so that the electric energy quality is improved.

The invention discloses a transformer area electric energy quality optimization device based on area wireless communication. The transformer area electric energy quality optimization device comprisesan SVG module, a phase-change controller and a phase-change switch device. According to the invention, an MUC in the SVG module is used as a master control core, the SVG unit communicates with the phase-change controller through RS485, three-phase unbalanced current is adjusted in a unified and coordinated manner, unbalanced coarse adjustment is carried out through the phase-change switch, fine adjustment and reactive compensation are carried out through the SVG, the respective advantages of the two adjustment modes are considered, and the equipment cost is reduced to the maximum extent. 2.4 GHz wireless communication is sampled between the phase-change controller and the phase-change switch device, load data of the phase-change switch device is uploaded to the phase-change controller, thecontroller issues a phase-change command to the corresponding phase-change switch device according to the load imbalance condition, and the switch adjusts the load according to the received command.The problem of low-voltage power grid electric energy quality is solved, the power supply reliability is improved, the power distribution network loss is reduced, the field inspection and load adjustment workload of the operation and maintenance personnel is reduced, and the working efficiency is improved.

The present invention provides a multi-energy complementary microgrid hierarchical control and operation optimization method. The system comprises three buses, namely an electric bus, a hot bus and acold bus, and an electric energy input device included in the electric bus comprises a photovoltaic generator, a wind driven generator, a gas turbine, a storage battery and a large power grid; throughthe implementation of the invention, the optimization of hierarchical control and operation of the multi-energy complementary microgrid is realized, the energy utilization rate of the system is improved on the premise of realizing power optimization, and the problem of electric energy quality during micro-source operation and optimization control is well solved.