4880results about "Reactive power compensation" patented technology

A system uses an intelligent load controller for managing use of a consumable resource at an associated load. The controller has a resource measuring component for measuring the rate of use of the resource by the associated load, including measuring at least one of an instantaneous usage rate and a usage rate over an integration period and a load status component for receiving load status data for the associated load. The controller also has a communication component for receiving control messages from and sending load status messages to other associated controllers; a memory for storing a load control goal set; and a load control computer program responsive to the resource measuring component, the load status component, the control messages from other associated controllers and the load control goal set, to determine a load operating level for, and provide control commands to, the associated load.

A system and method of regulating the voltage of the power supplied to a plurality of power customers via a power distribution system that includes low voltage power lines and medium voltage power lines is provided. In one embodiment, the method includes measuring the voltage of a plurality of low voltage power lines at a plurality locations in the power distribution system with a plurality of voltage monitoring devices; with the plurality of voltage monitoring devices, transmitting voltage data in real time to a remote computer system; receiving, with the computer system, the real time voltage data of the voltage measured from the voltage monitoring devices; comparing, with the computer system, the real time voltage data with a first threshold value; and if the real time voltage data is beyond the first threshold value, transmitting with the computer system a first voltage adjustment instruction to a voltage control device configured to adjust the voltage supplied to a low voltage power line.

The present invention provides a method, computer program product, and apparatus and control system and method for providing substantially uninterrupted power to a load. The apparatus includes a control system coupled with an electrical power storage subsystem and a electrical power generator. The control system is configured to provide a plurality of modes of operation including at least a static compensator (STATCOM) mode, an uninterruptible power supply (UPS) mode and a generator mode (gen set), and to control transitions between each of the plurality of modes. In one embodiment, the control system is an integrated closed loop control system that includes a current control system and a voltage control system. The apparatus is capable of operating at least two of the plurality of modes simultaneously, including ramping the gen set mode up and simultaneously ramping the UPS mode down as the gen set mode is ramped down.

A method is provided in one example embodiment and includes receiving a message associated with a detection of reactive power in an energy system and inducing a first quantity of reactive power at a power level specified in the message. The first quantity of reactive power is induced in order to mitigate a second quantity of reactive power that is detected on a specific segment of the energy system. The first quantity of reactive power is induced at a local level on which a source associated with the second quantity of reactive power operates. In more specific embodiments, the message is sent in response to a sensor detecting the second quantity of reactive power, where the first quantity and the second quantity of reactive power are the same. In other embodiments, the method can include receiving a second message to stop mitigating the first quantity of reactive power.

A method for controlling dynamic power factor or the reactive power of a wind farm is provided. The wind farm comprises a number of wind turbines connected to a utility grid driven with a requested power factor or a requested reactive power. The wind turbine output voltage is controlled to a specific voltage set point. In the method, the wind farm power factor is measured and compared with the power factor requested for the utility grid, or the wind farm reactive power is measured and compared with the reactive power requested for the utility grid, respectively; the ratio of the wind farm voltage to the utility grid voltage is adjusted, and the output voltage of the individual wind turbines is regulated to correspond to the specific voltage set point; the steps are repeated until the power factor of the wind farm electricity corresponds to the requested reactive power.

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.

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.

A system and method of reactive power regulation in a wind farm having a plurality of wind turbines that provides optimum control of the reactive power compensation in the wind farm and is able to keep a reactive power reserve in order to support eventual grid contingencies.

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.

An integral method for realizing parallel generation and network reactive power compensation at the same time is based on the transient reactive power theory applying park transfer to transform a three phase inverter output current to a rotation dq coordinate to realize separation of active current and reactive current to convert the DC current of the photovoltaic to AC current by controlling the currents and directions carry out reactive power compensation to the local network. When a photovoltaic battery has enough energy to output, it realizes parallel generation and reactive compensation at the same time, when it stops the output, the inverter compensates the network independently.

A windfarm system is provided that is optimized for minimizing electrical loss. The windfarm system includes a plurality of wind turbine generators and a collector system including a conductor or network of conductors. The collector system also including a plurality of transformers with one or more transformers connected between each wind turbine generator and the conductors, and a substation transformer connecting the windfarm collector system to the electrical grid. The windfarm system also includes a monitoring system for monitoring the windfarm system electrical output and thermal condition, and outputs of the individual wind turbine generators. A control function may include voltage and real and reactive power commands to the individual wind turbine generators. The control function incorporates an algorithm whose technical effect is minimizing electrical losses for the windfarm system.

An electric power generator system or a motor comprising a doubly-fed asynchronous generator or motor comprising a stator and a rotor, a transformer having a first winding and a second winding, the first winding having a first end and a second end; and wherein the stator and the transformer are connectable in series with an electric power distribution grid.

The invention features a system for connection to a utility power network. The system includes a reactive power compensation device coupled to the network and configured to transfer reactive power between the utility power network and the reactive power compensation device; a capacitor system configured to transfer capacitive reactive power between the utility power network and the capacitor system; an electro-mechanical switch for connecting and disconnecting the capacitor system to the utility power network; an interface associated with the electro-mechanical switch; a controller configured to provide control signals for controlling the electro-mechanical switch; and a communication channel for coupling the controller to the interface associated with the electro-mechanical switch. The electro-mechanical switch, interface, controller, and communication channel together are configured to connect or disconnect the capacitor system from the utility power network within about three line cycles or less of the nominal voltage frequency when a fault condition is detected on the utility power network.

A voltage control arrangement for a system of multiple windfarms with transmission lines. Voltage is regulated at a point of regulation on the system, such as a high voltage substation or other system bus. Regulation is achieved at the point of regulation by sensing the voltage, comparing to a reference voltage, and adjusting the reactive power output of the wind turbines and other equipment in the system. The regulation point may be shifted to another point if needed to respect voltage limits at that points of the system after attempting to shift reactive load to restore voltage within limits at the other points in the system. The reference voltage may be adjusted to minimize losses for the system of multiple windfarms and transmission lines. A loss optimizing algorithm is applied to the combined multiple windfarm and transmission line to shift reactive load among local windfarms to minimize losses and to shift reactive load among individual wind turbines within an individual windfarm.

A reactive power compensation system includes a distributed energy resource situated at a local location configured to also receive power from a remote location by a distribution feeder line. The distributed energy resource includes an inverter including power semiconductor switching devices and an inverter controller configured for controlling the power semiconductor switching devices so as to provide reactive power support to the distribution feeder line.

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.

A method of providing reactive power support is proposed. The method includes detecting at least one of a plurality of network parameters in a distributed solar power generation system. The generation system includes a plurality of photovoltaic modules coupled to a grid via inverters. The method further includes sensing a state of the photovoltaic modules coupled to the distributed solar power generation system and determining a reactive power measure based upon the sensed state and the detected network parameters. The reactive power measure is used to generate a reactive power command. The reactive power command is further used to compensate reactive power in the distributed solar power generation system.

A reactive power controller for controlling reactive power in a wind farm grid connected to a utility grid and including at least two sub-grids and a collector portion is provided. At least one wind turbine is connected to each sub-grid, wherein the at least two sub-grids are connected to the collector portion and wherein the collector portion establishes the connection to the utility grid. The reactive power controller includes a device for determining an actual reactive power value at the collector portion, and a wind farm controller operatively connected to the device for controlling at least one of said wind turbines on basis of the determined actual reactive power value such that a desired reactive power value is attained.

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.

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.

The invention discloses a control circuit for a voltage dropping type power factor corrector, which is used for controlling a voltage dropping converter to realize the power factor correction function. Inductance current critical intermittent control of changed on-time is performed on a Buck circuit through the control circuit to ensure that the on-time of a switching tube rises in the power frequency period along with increase of input voltage; and the critical intermittent working mode of inductance current in the Buck circuit is controlled, and when the inductance current is greater than zero, the junction capacitance of the switching tube and inductance are resonated, and the switching tube is connected when the voltage resonance of the junction capacitance reaches the volley bottom. The control circuit for the voltage dropping type power factor corrector has the characteristics of ensuring high power factors in the whole input voltage range, and meeting the harmonic requirements of IEC 61000-3-2 Class C, Class D, along with high efficiency.

An interface device transmits a reactive power command depending on a power system from a voltage regulation device of the power system to a wind power generation apparatus electrically connected to the power system, and the wind power generation apparatus receives the reactive power command. Then, the wind power generation apparatus outputs reactive power according to a value obtained by adding, to a reactive power command, another reactive power command for suppression of voltage fluctuation caused by output power of the wind power generation apparatus.

A windpark includes at least two wind energy installations, each of which installations comprises a rotor, a generator driven by the rotor and a control device, and which are connected via connecting lines to a main line. The windpark also includes a linking point which connects the main line to a power transmission network, a parkmaster which is configured for power factor control and has communication lines for transmission of control signals to the wind energy installations, and a power-factor control section including a distributed regulator having a higher-level regulator located at the parkmaster which is configured to determine a nominal voltage in order to set a global power coefficient for the power which is emitted to the power transmission network and to emit the global power coefficient as a signal via the communication lines and lower-level regulators at the wind energy installations.

The present disclosure relates to a method for controlling a wind turbine of the type including a rotor, a generator, a frequency converter, a control unit and means for connecting to a wind farm grid, using means for receiving a local voltage reference value (V_REF) and a regulator (1) which calculates the reactive power to be generated (Q_T) as a function of the voltage error (ΔV), such that it can be operated over the entire voltage range. The system also includes: at least one saturator element (2, 6, 7) in which the reactive power to be generated is limited, whereby the limits (Q_—MAX, Q_—MIN, Q_{C<sub2>—</sub2>}MAX, Q_{C<sub2>—</sub2>MIN}, Q_{S<sub2>—</sub2>MAX}, Q_{S<sub2>—</sub2>MIN}) are calculated dynamically as a function of the voltage, this block outputting a reference reactive power of the wind turbine (Q_—REF, Q_{C<sub2>—</sub2>REF}, Q_{s<sub2>—</sub2>REF}); and an element (3) for calculating the actual limit of the active power (P_MAX) as a function of the pre-limited reactive power (Q_—REF, Q_{s<sub2>—</sub2>REF}) and the apparent power available at that moment.

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.

The invention relates to a method and device for performing on-load scheduling on a single-phase load in the intelligent power grid field. A master controller is mounted at an input end of a three-phase wire, a secondary controller is mounted at each single-phase branch of the wire, and the master controller exchanges information with the secondary controllers through communication interfaces. When the wire power unbalanced degree is over limit, the master controller optimizes and formulates a control scheme to operate the secondary controllers to convert the single-phase load between the phases; in the conversion process, the load is free from instant power off, and the power grid is free from impact and interference; and therefore, the distribution circuit dynamically runs in a load balance state, the unbalanced consumption problem of the circuit is completely solved.

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.

The present invention relates to a method for increasing a total reactive power capability of a cluster of wind turbines operationally connected to a grid. The method comprises the steps of generating a voltage value representative of a grid voltage level, determining a total required reactive power value based on the voltage value, and activating at least one wind turbine in said cluster to increase the total reactive power capability from a present value to the required total reactive power value by a predetermined amount. Moreover, the present invention relates to a system suitable for carrying out the before-mentioned method.

Systems and methods are provided for reactive power regulation and voltage support for renewable energy plants. In one embodiment, a system and method are provided for coordinating voltage and reactive power output of a plant with one or more requirements associated with a utility. The method can include generating a VAR regulator output signal based at least in part on a reactive power control signal received from a utility, controlling reactive power and voltage output of the one or more power sources based at least in part on the generated VAR regulator output signal, aggregating reactive power output or the one or more power sources, and providing the aggregated reactive power to the utility.

A power compensation apparatus for a renewable energy system includes a plurality of converter modules positioned between any two phases of a three-phase AC electrical grid, each converter module including a plurality of inverter circuits connected in series. Each inverter circuit includes an energy storage unit for providing a direct current (DC) voltage; a capacitor connected to the energy storage unit; and an H-bridge circuit converting the DC voltage into an alternating current (AC) voltage. The converter modules perform reactive power compensation and active power regulation on the electrical grid in a delta connection. A plurality of converter modules are respectively positioned between any two phases of the electrical grid in a delta connection, so as to keep the voltage of the electrical grid continuously stable when the voltage of the electrical grid fluctuates, and also compensate load current when system load is not balanced.