274 results about "Power quality control" 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 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.

A solar electric system comprises photovoltaic elements having integrated energy storage and control, ideally on each PV-panel. The energy storage media may be primary or secondary cylindrical cells interconnected into a battery and/or an array of capacitors (or super-capacitors) and are accompanied by an electronic control circuit which may perform a variety of functions, including but not limited to: power quality control, load following, pulse powering, active line transient suppression, local sensing, remote reporting, wireless or wired communications allowing two way programmable control through local or remote operation. The operation of the system may yield direct current or with the integration of bidirectional micro-inverters create distributed alternating current generation enhanced with energy storage and control two way energy flows between the solar system and the grid.

The invention discloses a novel electric power electric transformer. The electric power electric transformer consists of a high-voltage level, an isolation level and a low-voltage level, wherein the high-voltage level comprises 2*N*n half-bridge topology first power modules; the isolation level consists of N1 second level power modules, and each second power module comprises a medium high frequency wave chopper part, a medium high frequency transformer part and a medium high frequency synchronous rectifier part; and the low-voltage level consists of N2 level third power modules. The electric power electric transformer skillfully utilizes the prior half-bridge topology structure technique, better solves the problems of low operating efficiency, voltage resistance and voltage sharing of switch devices on the input side and big volume of an input filter existing in the common electric power electric transformer, and simultaneously realizes reactive power control of the high-voltage level and the low-voltage level, quality control of electric energy and limitation of failure current, improves the practicability of the device and quickens commercialization of the electric power electric transformer.

The invention provides a grid power quality control system and method based on a unified power quality conditioner. The system comprises a series MMC, a parallel MMC and a control circuit. The series MMC and the parallel MMC form a unified power quality conditioner (UPQC) topological structure based on MMC, and are connected to a grid side and a load side through a transformer respectively. The method comprises the following steps: carrying out transformation on an MMC module under an abc stationary coordinate system to obtain a differential equation matrix model under a dq rotating coordinate system; obtaining small-signal models of the series MMC and the parallel MMC under the dq rotating coordinate system; utilizing the parallel MMC to output an offset current and stabilize DC side voltage; and utilizing the series MMC to output an offset voltage. A fundamental wave positive sequence voltage component and a fundamental wave positive sequence current component adopt a PI regulator, and other components adopt a PR regulator to realize non-static-error control, so that compensation is carried out not only for the cases of distortion, harmonic wave and reactive power and the like, but also for the cases of unbalance power source voltage and unbalance load, and the load is allowed to obtain reliable power supply.

The invention belongs to the technical field of the power quality control of wind power generation, in particular a double-fed aerogenerator excitation system based on the hybrid stored energy of a super capacitor and a storage battery. The system is characterized by comprising a rotor side converter 3, a net side converter 4, a chopper A5, a chopper B7, a super capacitor 6, a storage battery 8, a bilateral switch as well as a limiting resistor Rl and a direct current side capacitor C, wherein a hybrid stored energy device comprising the chopper A5, the chopper B7, the supper capacitor 6 and the storage battery 8 is connected to both ends of the direct current capacitor in parallel; the rotor side converter 3 is responsible for providing excitation power to an aerogenerator; the net side converter 4 is responsible for transmitting power exchanging with the output end of the rotor side of the aerogenerator, and exactly controlling the charge and discharge power of the storage battery and the super capacitor by controlling the chopper A5 and the chopper B7 so as to compensate external power fluctuation. The invention has the advantages that the aerogenerator generates stable electrical energy under the condition of the frequent fluctuation of the aerogenerator, the safe stability of large-scale synchronization running of a wind farm is improved, and the excitation system can also be widely used in ocean power generation such as wave-actuated power generation and tidal power generation.

The invention discloses a standardized current conversion device applicable to an electric vehicle and a distributed power source to be accessed to a public power distribution network. The traditional distributed power source can not be effectively isolated from the power network, the requirements of high-end users for power quality can not be ensured, and power users with severe pollution can not be prevented from injecting power into the power network. The standardized current conversion device comprises a power network side module, a user side module, an electric vehicle charging and discharging module and a controller, wherein the network side module is connected with the electric vehicle charging and discharging module in parallel and then is connected with the power network side module in series; a trigger pulse signal generated by the controller is transmitted to the power network side module, the user side power module and the electric vehicle charging and discharging module through optical fibers, the controller communicates with a background server through Ethernet, and a background monitoring software module is installed in the background server. The invention can realize the effective isolation of the distributed power source and the power network and can also combines the functions of dynamic reactive compensation, fault current limitation, power quality control and the like.

The invention relates to an integrated energy saving system of a power supply and distribution system, wherein all energy saving devices and power quality control devices of the power supply and distribution system are integrated to form the integrated energy saving system which implements unified control to cause the power supply and distribution system to always run in the most economical manner; in every subsystem, all the energy saving devices are unified to work coordinately and cooperatively so that the distribution network can achieve the best energy saving effect. The integrated energy saving system structurally comprises a supervisory computer monitoring module, a communication module and a plurality of execution submodules; the supervisory computer monitoring module carries out visual and real-time control to the whole system and adopts a mass memory device and a large management database; the communication module adopts the Ethernet, a fieldbus and wireless communication device and other modules of the system for communication; the execution submodules comprise a comprehensive series-control energy saving device, a configuration monitoring device, a fieldbus device, a reactive power compensation device, a voltage stabilizing device, a harmonic wave regulating device, a frequency control device and an intelligent box-type substation device.

The invention discloses a novel power quality control system with a fault current-limiting function and a control method thereof. The novel power quality control system with the fault current-limiting function comprises a three-phase H-leg PWM rectifier, a three-phase four-leg series converter, a thyristor controlled short-circuit branch, a thyristor controlled bypass reactance branch and a corresponding control method. The PWM rectifier and the three-phase four-leg series converter share one direct current side to achieve bidirectional energy conversion, the series converter compensates the fall, the raising and three-phase imbalance of the grid voltage and solves the quality problem of the harmonic voltage, at the same time, the system controls the series converter, the thyristor controlled short-circuit branch and the thyristor controlled bypass reactance branch to limit the current when various short-circuit faults occur on the grid, and thus the purposes of stabilizing the loaded supply voltage, improving power supply quality, protecting the grid and load equipment when short-circuit faults occur and improving the safety and stability of the electric power system are achieved.

The invention discloses a device used in an electrified railway for controlling and compensating electric energy quality, and belongs to the field of power supply of electrified railways. The device comprises a passive filter formed by a second-order high-pass filter, a group of voltage source type converters, and a phase reactor, wherein the passive filter is used for providing an electric locomotive on an electrified railway with reactive power and filtering harmonic current generated by the electric locomotive; the voltage source type converters can generate voltage with controllable amplitude, phase and frequency and are used for negative sequence compensation, flicker control and the like of a traction power supply system of an electric railway; and the voltage source type converters are connected in parallel onto a 25kV traction electric network through the phase reactor and the passive filter. The device provided by the invention can solve the electric quality problems such as three phases imbalance, harmonic wave, voltage fluctuation, flicker and the like while compensating power factors of the power supply system of the electric railway. Additionally, with the fully play of the advantages of the passive filter, such as convenience for configuration and low cost, and the advantages of the voltage source type converter, such as small occupation area and low consumption as much as possible, the whole set of device can achieve the best technical specification and the greatest economic performance.

The invention provides a multi-target electric energy quality comprehensive control and optimization device which comprises a control part and a main circuit part, wherein the control part comprises a detection functional module, a multi-target electric energy quality control and optimization controller and a man-machine interface, the main circuit part comprises a passive LC main circuit and an active VSI main circuit, the detection functional module is used for detecting and analyzing electric energy quality indexes of a load, a power grid and the multi-target electric energy quality comprehensive control and optimization device, and the multi-target electric energy quality control and optimization controller controls the device to conduct evaluation and analysis on the priorities of electric energy quality control targets and an optimal control strategy at the current moment within the range of security capacity in a unified and coordinated mode and sends out a control command to control the main circuits to conduct electric energy quality control and optimization in a unified and coordinated mode. The device is high in capacity and easy to expand, and capable of solving the electric energy quality problems such as voltage deviation, voltage fluctuation and flickering, three-phase imbalance, harmonic waves and low power factors to a certain extent.

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 series electric energy quality controller, including: an electric energy detecting unit, a control unit, an offset voltage generator, a DC unit, a connect unit and a protective unit It is equivalent to a voltage source in series with the distribution wire of a system to eliminate the effect of system voltage distortion on a load, and is a load-oriented electric energy quality improving device. It is connected in series between the system and load, and quickly outputs an offset voltage as the voltage waveform is distorted, so as to avoid the sensitive load from being affected by the system voltage fluctuation and assure the power supply quality for the sensitive load. It can effectively solve the quality problems of dynamic voltage, like voltage drop, etc., and also give consideration to the quality problems of stable voltage, such as system voltage harmonics, voltage fluctuation, three-phase imbalance, etc..

The invention relates to a unified power quality control device employing a resonant electronic switch, and belongs to the technical field of power electronics and flexible alternating current transmission and distribution. The device comprises the resonant electronic switch, a voltage source converter, an energy storage unit and a master control system, wherein the master control system consists of a master controller and a plurality of sensors; the resonant electronic switch comprises a group of inductors Lr1 and Lr2, a group of capacitors Cr1 and Cr2 and a group of bidirectional thyristors T1; a branch formed by connecting the bidirectional thyristors T1 in series with the inductor Lr2 and the capacitor Cr1 is connected in parallel with the inductor Lr1; and a parallel branch formed by Lr1, Lr2, Cr1 and T1 is connected in series with the capacitor Cr2. A method comprises the steps of judging various power quality faults and controlling the device to quickly switch and operate among four modes. The device has the advantages of simple structure, low cost, high overload resistance and high operation efficiency.

The invention discloses a diagnosis method for an active power filter switching device open-circuit fault based on model reference analysis. The diagnosis method includes the steps that on the basis of building an actual operation model of active power filter main circuits, a reference model is constructed; measurable active power filters in all sampling periods are used for outputting three-phase compensating currents, and voltage residual errors are generated according to reference analysis of the model; by setting a threshold value and two judgment flag bits, the residual errors are evaluated to detect whether the open-circuit fault happens on an APF switching device or not in real time; if the fault happens, the specific position where the open-circuit fault of the switching device happens is diagnosed according to the two judgment flag bits. The diagnosis method is effectively used for monitoring the active power filters on line and diagnosing faults, and electric, electronic and electric energy quality control devices such as the active power filters and reactive compensators operate reliably and safely.

The invention relates to a UPQC for flexibility power transmission and distribution of a power system, in particular to a high-capacity UPQC and a control method of the high-capacity UPQC. The high-capacity UPQC is applied to the parallel-connection side of the UPQC by using the structure that a secondary side of a multi-winding transformer is connected with an H-bridge convertor. Three phases on the parallel-connection side are equivalent to three single-phase rectifier models connected to line voltage in a cross mode. As being controlled independently, each H-bridge rectifier is not affected by unbalance of three-phase voltage, and the stability of voltage across the direct current side of the UPQC when network voltage fluctuates is facilitated. A control method based on virtual orthogonal coordinate conversion is adopted, the single-phase rectifier models on the parallel-connection side of the UPQC are equivalent to a three-phase rectifier model, the functions of the controllable power factor and harmonic suppression of a three-phase rectifier are achieved, and all functions of the three-phase rectifier on the condition of the symmetric system voltage can be completely achieved.

The invention discloses a testing system of a unified power quality controller and a testing method of the testing system. The testing system comprises an electric current perturbation generation device, a voltage disturbance generation device and a power quality monitoring system, wherein the current perturbation generation device is connected at the load side of the unified power quality controller in parallel, the wire outlet terminal of the voltage disturbance generation device is connected with the wire incoming terminal of the unified power quality controller, the wire incoming terminal of the voltage disturbance generation device is connected with the power supply of the system, the two ends of the current perturbation generation device and two ends of the voltage disturbance generation device are connected with the power quality monitoring system respectively. According to the testing system and the testing method, various working conditions of the unified power quality controller in practical application can be simulated, the power quality control function and the power quality control performance can be monitored and analyzed in real time, therefore, the purpose of comprehensively testing and analyzing the unified power quality controller can be achieved.

The invention is concerned with the compensation equipment that uses for electrification railroad reactive power compensation and the electrical energy quality control, including: two groups of passive filters using to provide reactive power for electrification railroad locomotive and filters the harmonic current of the electrification locomotive; two groups of contravariant equipments using to create current that can control the breadth value, the phase and the frequency; two groups of transformers using to coupling the current from the two contravariant equipments to the supply are of the electrification railroad; the public direct-current unit using to transform the active power between the two groups of contravariant equipments and provide the direct-current to the two groups of contravariant equipments. The invention can process power factor compensation for the electrification railroad supply system, control the quality of the electricity energy.

The invention is an energy quality controller for a traction power substation, composed of a three-phase converter and a Scott transformer, two orthogonal single-phase output power supplies are connected with two single-phase output ends of the Scott transformer, respectively, the three-phase converter connects in series with a three-phase output end of the Scott transformer, where the three-phase converter is an inverter with capacitor in parallel with the DC bus. It controls two power supply arms of the traction transformer at the same time and can effectively compensate harmonics in drawing electric network, reactive power and negative sequence current.

The invention discloses a reactive compensation method and device having a transformer reactive current real-time compensation function and belongs to the field of electric energy quality control. The reactive compensation method and device are used for conducting real-time calculation on the no-load loss and the loss (changing along with the load rate) in the load-available condition, real-time compensation of reactive current of a transformer is achieved, and the problem that the power factor is low due to the reactive loss of the transformer is solved. Meanwhile, the optimal control theory is used for calculating the switching strategy of capacitance compensation of an SVG and a TSC, switching of the SVG and the TSC can reach the optimized effect, and the advantages of fastness and nonpolarity are achieved completely.

The invention relates to a distributed photovoltaic power generation integrated control system. A low-voltage microgrid control terminal and a low-voltage power quality control device are accessed into a low-voltage grid, and a medium-voltage power quality control device and a medium-voltage distributed power generation control terminal are accessed into a medium-voltage grid. The distributed photovoltaic power generation integrated control system has the advantages that by means of the distributed photovoltaic power generation integrated control system, a distributed photovoltaic power supply serves as standby energy, power supply blockage can be alleviated, margin of a power distribution network is enlarged, power supply reliability is improved remarkably, controllable idle-work output capability is provided, busbar voltage level is maintained, voltage drop is alleviated, large-area power outage is avoided, and capacity of the existing power quality regulation device can be reduced remarkably when the distributed photovoltaic power generation integrated control system and the existing power quality regulation device of the power distribution network are combined to operate to perform idle-work regulation or harmonic wave inhibition.

The invention provides a multi-port power switch based on AC-DC hybrid distribution and utilization. The power switch comprises an electrical physical layer and an electrical information layer, wherein the electrical physical layer is composed of a power electronics solid state module, a solid state module controller, a protection and drive module, a monitoring and sensing module, an internal power supply module, a power interface module and a power storage module, and the electrical information layer is composed of an intelligent control module, a communication module and an upper layer management and application module. The management of a unified grid-connection function of a distributed power supply in a power distribution network is achieved, a uniform DC and AC circuit is established, and uniform power quality control and uniform energy management are achieved.

The invention relates to a parallel unified power quality control device, and belongs to the technical field of power electronics and flexible alternating current transmission and distribution. The device comprises a voltage source converter, an energy storage unit, a resonant electronic switch and a master control system, wherein the master control system consists of a master controller and a plurality of sensors; the resonant electronic switch is connected in series between a grid and a protected sensitive load; two ports of the resonant electronic switch are PCC1 and PCC2 points respectively; an alternating current output port of the voltage source converter is connected in parallel with the PCC2 point; a direct current side capacitance port of the voltage source converter is connected with a corresponding output port of the energy storage unit; and the master controller generates control gate pole signal output and is connected with the voltage source converter and the resonant electronic switch. A method is to judge various power quality faults and control the device to perform quick switching and operation among four modes. The device has the advantages of simple structure, low cost, high overload resistance and high operation efficiency.

The present invention relates to an energy-saving type iron/steel industry energy efficiency tracking control management equipment and its energy-saving control method. Said equipment includes signal acquisition device, electric energy quality controller, programmable controller, visualized operation device, fuzzy controller, workshop control station, engineer control station and energy source management station, between all the portions, the electric connection or signal connection is implemented

The invention discloses a SVG-based multi-objective on-line regulation and control method for power quality management equipment group, comprising the following steps: real-time collecting bus voltage, current and load current signals and calculating system parameters; The capacity of the power quality management equipment group is allocated, and the intelligent allocation strategy is adopted to control the equipment. The load harmonic distortion rate and its contents are measured, and the frequency dividing compensation strategy is used to control the equipment. According to different controltargets, the adoption of an intelligent allocation strategy, Energy replacement strategy and frequency division compensation strategy can optimize the equipment configuration, coordinate and controlthe output proportion of equipment group, realize the multi-objective automatic regulation and control of power quality management equipment group in the region, solve the mutual influence problem between multi-power quality management equipment, and improve the overall power quality management ability and efficiency.

The invention relates to a high-capacity unified power quality conditioner based on a chain structure and a control method of the high-capacity unified power quality conditioner. A three-phase three-wire system series-and-parallel structure is adopted in the high-capacity unified power quality conditioner. The high-capacity unified power quality conditioner comprises a series type voltage source converter and a parallel type voltage source converter, wherein the series type voltage source converter and the parallel type voltage source converter are connected through a common direct-current bus, single-phase H-bridge cascade structures are adopted in the series type voltage source converter, the H-bridge cascade structure of each phase is connected to an alternating-current side power grid through a series capacitor, single-phase H-bridge chain link structures are adopted in the parallel side converter, a back-to-back structure is formed by the single-phase H-bridge chain link structures and H-bridge chain links of the series type voltage source converter, and each H-bridge chain link of the parallel side converter is connected to a direct-current side power grid through the secondary side of a single-phase multi-winding transformer. The invention further provides the control method of the high-capacity unified power quality conditioner. According to the high-capacity unified power quality conditioner, a series side transformer is omitted, short-circuit impedance of a loop is reduced, voltage accuracy of open-loop control is improved, performance of the high-capacity unified power quality conditioner is improved, and the problem that the instantaneous inrush current phenomenon happens when voltage drop of the series side happens is solved.