951 results about "Reactive power control" patented technology

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.

Systems and methods for supplying power (both active and reactive) at a medium voltage from a DCSTATCOM to an IT load without using a transformer are disclosed. The DCSTATCOM includes an energy storage device, a two-stage DC-DC converter, and a multi-level inverter, each of which are electrically coupled to a common negative bus. The DC-DC converter may include two stages in a bidirectional configuration. One stage of the DC-DC converter uses a flying capacitor topology. The voltages across the capacitors of the flying capacitor topology are balanced and switching losses are minimized by fixed duty cycle operation. The DC-DC converter generates a high DC voltage from a low or high voltage energy storage device such as batteries and/or ultra-capacitors. The multi-level, neutral point, diode-clamped inverter converts the high DC voltage into a medium AC voltage using a space vector pulse width modulation (SVPWM) technique.

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.

The present invention provides a mixed integer cone programming based intelligent distribution system synthetic voltage reactive power optimization method. The method comprises: inputting a distribution system structure and a parameter of a distribution system; establishing a time sequence optimization model of a distribution system synthetic voltage reactive power control problem considering various types of adjustment means; converting the established model into a mixed integer second-order cone model; solving the obtained mixed integer second-order cone model by using a mathematical solver capable of solving mixed integer second-order cone programming; and outputting a solution result. The method provided by the present invention greatly reduces solving difficulty and facilitates performing solution by using a solving tool, so that a complex mixed integer non-linear programming problem can be solved, cumbersome iteration and a large number of tests are avoided, and the calculation speed is greatly improved.

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.

Systems and methods are disclosed to control voltage profiles of a power grid by forming an autonomous voltage control model with one or more neural networks as Deep Reinforcement Learning (DRL) agents; training the DRL agents to provide data-driven, real-time and autonomous grid control strategies; and coordinating and optimizing reactive power controllers to regulate voltage profiles in the power grid with a Markov decision process (MDP) operating with reinforcement learning to control problems in dynamic and stochastic environments.

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.

Wind farms and methods for operating wind farms are provided. A wind farm includes a plurality of wind turbine generators. A method includes determining an available reactive power value for each of the plurality of wind turbine generators. The method further includes distributing an individual reactive power command to each of the plurality of wind turbine generators. The individual reactive power command is individually tailored to each wind turbine generator of the plurality of wind turbine generators based on the available reactive power value for that wind turbine generator.

The invention relates to the field of protection and control of micro-grids of electric power systems and particularly relates to a micro-grid island fast detection method. The method is sued for an inverter-based distributed generation (IBDG) with a PQ (power quest) decoupling control strategy; a corresponding reactive power control strategy is adopted in the method on the basis of measuring a voltage effective value UPCC and the load reactive power of a common coupling point PCC in real time through comparing the voltage effective value UPCC with the voltage effective value under a normal condition; when island determination is performed, firstly, a voltage threshold value and a frequency threshold value are predetermined, the voltage effective value UPCC is compared with the voltage threshold value, if the voltage effective value UPCC exceeds the threshold value, the PCC is directly determined be in an island state and the island detection is finished, and if the voltage effective value UPCC does not exceed the threshold value, the voltage frequency f of the PCC is compared with the frequency threshold value, the PCC is determined to be in the island state if the voltage frequency f of the PCC exceeds the threshold value. With the adoption of the detection method, the micro-grid island detection can be realized fast, and the effectiveness of the island detection can be ensured even under the existence of a plurality of inverter-based distributed generations.

The invention discloses an inverter grid-connected control method based on the virtual synchronous generator technology and belongs to the field of distributed power generation system grid-connected researches. According to the technical scheme, the method includes the steps that a grid-connected inverter phase voltage phase value is obtained through calculation by simulating a conventional synchronous generator unit active power control method; a grid-connected inverter phase voltage amplitude value is obtained through calculation by simulating a conventional synchronous generator unit reactive power control method; a three-phase voltage reference value is worked out according to the inverter phase voltage phase value and the inverter phase voltage amplitude value, a three-phase modulated wave is figured out according to direct current side voltage obtained through detection, and the three-phase modulated wave is compared with a carrier wave to obtain six switching signals to control turn-off and turn-on of switching devices in a main circuit. System damping and active power-frequency droop control are achieved by means of control link signals, and power grid frequency does not need to be detected. The method simplifies a control structure and avoids the problems caused by a frequency detection link. Effectiveness of the method is verified through simulation and experiment results.

The invention relates to a symmetrical drop-off low voltage ride through reactive power control method of a photovoltaic power generation system. A controller detects whether a grid connection point voltage drops off in real time, and if the voltage does not drop off to 90% of a nominal voltage, an active current reference value id* is taken from an outer voltage loop, and grid connection control when the voltage is normal is adopted; if the grid connection point voltage drops off below 90% of the nominal voltage, the outer voltage ring is disconnected, low-voltage ride through control is adopted, namely inner current loop control is adopted, definite reactive power is output to a power grid by the photovoltaic power generation system according to the drop-off amplitude, and recovery of the voltage of the power grid is facilitated; if it is detected that the voltage recovers, the active power of the photovoltaic power generation system recovers at 10% rated power/second, reactive power is gradually reduced to zero at the same time, and finally the grid connection control when the voltage is normal is adopted. According to the method, an outlet current of a photovoltaic grid-connected inverter is limited within an over-current protection action current, reactive power support is provided for the grid voltage to recover to the normal value, investment of reactive power equipment is saved, and resources are saved.

The present invention relates to a method of reactive power regulation in a wind turbine comprising a local reactive power control system adapted to operate in a central control mode and a local control mode, a method of reactive power regulation in a wind park connected to an electrical grid, and to a wind park.

The invention discloses an optimized control method for wind power field reactive power compensation capacity considering wind power distribution rule; according to the method, a reactive power compensation capacity optimization model is utilized to carry out an optimized treatment, and the optimization target is that investment cost of reactive power compensation and operation cost of wind power system caused by reactive power are minimized; operation cost and investment cost are calculated; the operation cost comprises the affect of wind power distribution result and power property; and an optimized calculation is carried out by utilizing a particle swarm optimization algorithm combined with a power flow calculation program. The method has the beneficial effects that according to the optimization decision method of the compensation capacity, the reactive power compensation of a wind power field has the best economical efficiency and the strongest pertinency on the premise of adequately ensuring continuity of reactive power adjustment by wind power system.

The invention provides an evaluation method based on a voltage reactive power control system in a grid system. Weights are distributed through the utilization of the fuzzy linear transformation theory and the maximum membership degree principle, by taking factors relevant to an evaluated object into consideration and according to the degree of influences of different indexes on the evaluated object, and then reasonable comprehensive evaluation is given. The method includes the steps that firstly, data of the voltage reactive power control system in a grid are acquired; secondly, an index system of a hierarchical model of first level indexes and second level indexes is formulated; thirdly, system running is analyzed and summarized according to running data, analysis data and running state information of all modules, and then running state parameters and the running state of the voltage reactive power control system are acquired, wherein the first level indexes and the second level indexes in the index system serve as analysis and computation objects of the voltage reactive power control system; fourthly, a judgment set of a classification model is determined; fifthly, a comprehensive analysis hierarchical structure is formed through the Delphi method; sixthly, the weights of the indexes are determined; seventhly, comprehensive evaluation of the highest layer A of the comprehensive evaluation index system is computed according to a fuzzy comprehensive evaluation method and model.

A system and method are provided for performing reactive power control. The system includes a power converter and a controller coupled to the power converter. The power converter is configured to convert a first form of electric power generated from the power source to a second form of electric power suitable to be distributed by the electrical grid. The controller is configured to monitor the electric power transmitted between the power converter and the electrical grid. The controller is further configured to decouple a positive sequence component and a negative sequence component from the monitored electric power. The controller is further configured to perform a positive reactive power control and a negative reactive power control with respect to the decoupled positive and negative sequence components. The controller is further configured to transmit a control signal to the power converter based on the positive and negative reactive power control.

Methods, systems, controller devices, and computer program products for reactive power control at a renewable energy site are provided. Embodiments address dynamic performance problems associated with control loop delay and the changing modes of operation for meeting utility voltage and reactive power constraints. Provided is a method for reactive power control involving: (a) determining a site-wide reactive power command comprised by a sum of a reactive power feedforward or compensation term and an integrator term; and (b) distributing the site-wide reactive power command among inverters. Embodiments can include a reactive power control term based on the sum of a single integrator and feed-forward compensation term, an integrator anti-windup mechanism based on the status of individual inverters, a means for decreasing detrimental effects of loop delay during reactive power reference changes, and/or a means of implementing voltage and power factor limits with smooth transfer between reactive power operating regions.

A power inverter includes a regulator circuit that controls real and reactive power output by the inverter. The regulator measures real and reactive output power by calculating x-phasor components of the inverter's voltage and current output waveforms. Phasor calculation can be adapted for one or more pairs of single-phase voltages and currents. Determining the fundamental in-phase and quadrature components of output voltage and current reduces computational complexity by permitting the regulator to perform its power control processing largely in a dc signal domain, and enables separate real and reactive power control. The power inverter can include islanding detection logic, which exploits the ability to separately control reactive power. Exemplary islanding detection logic is based on determining whether changing the amount of reactive power output by the inverter induces an output frequency shift.

The invention discloses a regional power grid reactive power optimization method relating to a flexible HVDC system. The method achieves the purpose of regional reactive power optimization on the flexible HVDC AC and DC parallel system and provides a basis for setting reactive power control reference values for a current converter. The method includes the steps of acquiring basic parameters of a power grid, determining a relational expression of voltage, current and power of the flexible HVDC system, establishing a reactive power optimization objective function with power regulation cost of flexible HVDC considered, determining equality and inequality constraints of corresponding variables according to the variables in the objective function, solving the regional power grid reactive power optimization objective function with the genetic algorithm by considering current constraints of the current converter of the flexible HVDC system under different operation modes, and improving power control strategies according to current converter reactive current optimal solutions obtained by optimal computation. According to the method, the active power regulation cost of flexible HVDC and the current constraints of the current converter are considered, and therefore rationality in setting the reactive power control reference values of the current converter is improved.