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4880results about "Reactive power compensation" patented technology

Method for operating a wind turbine

InactiveUS6965174B2Voltage fluctuationUnwanted fluctuationWind motor controlMachines/enginesPower gridWind force
The present invention relates to a method for operating a wind turbine with an electrical generator, drivable by a rotor, for supplying electrical power to an electric grid, in particular to the loads connected thereto. The object of the present invention is to define a method for operating a wind turbine and to provide a wind turbine and/or a wind farm that is capable, even when the output of non-reactive power fluctuates, of reducing or at least of insignificantly increasing the unwanted fluctuation in voltage at a predefined point in the grid compared to the situation with no wind turbine(s). Method for operating a wind turbine with an electrical generator, drivable by a rotor, for supplying electrical power to an electric grid, in particular to the loads connected thereto, characterized in that the phase angle φ is changed in response to at least one voltage measured in the grid.
A method for operating a wind turbine and to provide a wind turbine and/or a wind farm that is capable, even when the output of non-reactive power fluctuates, of reducing or at least of insignificantly increasing the unwanted fluctuation in voltage at a predefined point in the grid compared to the situation with no wind turbines. Method for operating a wind turbine with an electrical generator, drivable by a rotor, for supplying electrical power to an electric grid, in particular to the loads connected thereto, characterized in that the phase angle φ is changed in response to at least one voltage measured in the grid.
Owner:WOBBEN ALOYS

Modular charging/discharging system of power battery pack of multifunctional electromobile

The invention relates to a modular charging/discharging system of a power battery pack of a multifunctional electromobile, which aims to provide a system which can effectively meet the requirement for the bi-directional power transmission of a charging station and can exert the functions of peak clipping and valley filling as well as peak modulation and frequency modulation of a power grid. The technical scheme is as follows: the modular charging/discharging system of the power battery pack of the multifunctional electromobile comprises a charging-station monitoring system and an information management system, wherein the charging-station monitoring system is composed of a computer and a network communication system. The modular charging/discharging system is characterized by also comprising a three-phase step-down transformer, wherein the high voltage side of the three-phase step-down transformer is connected with a power grid, and the low voltage side of the three-phase step-down transformer is connected in parallel with a plurality of charging/discharging branches; each branch comprises a three-phase distribution transformer and a charging/discharging module, and the three-phase distribution transformer is connected in series with the charging/discharging module; and each charging/discharging module comprises a pulse-width modulation alternating current/direct current (PWM AC/DC) converter with the function of bi-directional power transmission, a plurality of electromagnetic isolation type DC/DC transform modules with the function of bi-directional power transmission and the information management system, and the electromagnetic isolation type DC/DC transform modules are connected in parallel.
Owner:梁一桥

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

Energy-saving type cascade multilevel photovoltaic grid-connected generating control system

The invention discloses an energy-saving type cascade multilevel photovoltaic grid-connected generating control system comprising an energy-saving cascade multilevel photovoltaic generating inverter, a controller and a power grid, wherein the multilevel inverter consists of 3n energy-saving type photovoltaic generating modules, wherein n modules are connected in series into one phase of a three-phase inverter; and the single-stage power of each module is converted to realize the buck-boost, the inverting and energy saving and adapt to the wide-range change of the battery voltage with high reliability. 3n photovoltaic cells and energy-saving cells are distributed on 3n modules; the generation of each module is independently controlled, thereby realizing the distributed maximum power track, collecting solar energy to the maximum extent, realizing high efficiency and avoiding the problems of power loss and hot spot caused by the local shade generated when the photovoltaic cells are connected in series; and the invention can flexibly control the stable power of a feeder grid of the multilevel inverter and achieve the functions of reactive power consumption, the power pitch peak control and the like, has the advantage of multilevel inversion and low output harmonic voltage and is suitable for high-voltage, high-power and transformer-free grid connection.
Owner:BEIJING JIAOTONG UNIV

System, method, and article of manufacture for controlling operation of an electrical power generation system

A system, a method, and an article of manufacture for controlling operation of an electrical power generation system are provided. The electrical power generation system has a plurality of electrical generators electrically coupled to an electrical grid. The method includes obtaining a first output parameter value associated with the electrical power generation system. The method further includes determining an error value indicative of a difference between the first output parameter value and a desired output parameter value. The method further includes determining a first gain value based on at least one of the first output parameter value and a time-varying operational parameter of the electrical power generation system. The method further includes determining a first power value based on the error value and the first gain value. The method further includes determining a second gain value based on at least one of the first output parameter value, the time-varying operational parameter, and a reference value. The method further includes determining a second power value based on the error value and the second gain value. The method further includes generating a desired power command for the electrical power generation system based on the first and second power values.
Owner:GENERAL ELECTRIC CO

Active and reactive coordination control method for permanent-magnet direct-driven wind turbines in low-voltage ride-through process

Enclosed is an active and reactive coordination control method for permanent-magnet direct-driven wind turbines in the low-voltage ride-through process. Two different control strategies are employed for a grid side converter according to amplitude change of power grid voltage: when the power grid voltage is in a normal state, the grid side converter is in an active-priority maximum power tracing control mode so that the wind turbines capture wind energy to the maximum extent; when the power grid voltage is beyond the normal range, the grid side converter is in an active priority control mode so that the dynamic reactive current which is injected into an electricity system meets the requirements of grid combining. An engine side converter is in a direct-current voltage control mode based on rotor energy storage, power unbalance of the direct-current side of the engine side converter is relieved and the direct-current voltage is stabilized by utilizing the self rotating speed of the permanent-magnet direct-driven wind turbines and the change of the kinetic energy. The active and reactive coordination control for the wind turbines before or after the sudden change of the power grid voltage is realized according to the amplitude change of the power grid voltage, the fluctuation of the direct-current bus voltage is restrained by releasing or storing the rotor kinetic energy, so that the low-voltage ride-through capability of the permanent-magnet direct-driven wind turbines is improved, reactive power support is rapidly and accurately provided for the power grid, and certain support is given to restoration of the power grid voltage.
Owner:NORTH CHINA ELECTRIC POWER UNIV (BAODING)

Cooperative control method for participating in frequency modulation and pressure regulation of power system by wind storage cluster

The invention discloses a cooperative control method for participating in the frequency modulation and pressure regulation of a power system by a wind storage cluster. The method comprises the following steps: using the over-speed control and pitch angle control of a wind turbine generator to preserve a part of active power and reactive power for the wind storage cluster as the frequency modulation and pressure regulation standby power of the power system in accordance with the active power and reactive power capacity standby requirements given by the operation condition of a wind power plant, wind speed and the scheduling of the power system; determining the size of the active power and reactive power given by the wind storage cluster in accordance with the state of the wind storage cluster when the frequency or voltage of the power system is fluctuated; and finally, by reference to the capacity limitation of a wind turbine generator and stored energy, determining the final output condition of the wind turbine generator and the stored energy. According to the cooperative control method provided by the invention, the condition that the wind storage cluster participates in the system frequency and voltage regulation, and the stability and electric energy quality of the power system can be effectively improved by less energy storage capacity allocation in the power system with higher wind power permeability.
Owner:INST OF ELECTRICAL ENG CHINESE ACAD OF SCI +3

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
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