The Research Of Compensatory Strategies Of Dynamic Voltage Restorer Based On The Minimum Energy Method

With the development of science and technology, all kinds of sensitiveelectrical equipment put to use, Voltage sag has became a significant problem inpower quality, and the users put forward more and more high demand to powersystems and power supply. Therefore, the equipment which can restrain voltage sagand disturbance in order to ensure the users’ power supply quality has obtained thedevelopment. Dynamic Voltage Restorer (DVR) is an effective compensation deviceused in voltage sag、rise and three phase imbalance and harmonic problems of powergrid at present. The thesis based on analysizing and discussing the DVR’s workingprincipal and the typical unit, study the compensatory strategy of the minimumenergy method in detail. On the analysis of the minimum energy compensatorymethod, put forward the research idea of the strategy of the compensatorycharacteristic to analysis theoretically. Discussed the device under no compensatoryvoltage constraints, the device proceed zero active exchange and minimum energyexchange. And research the device’s strategy under the compensatory voltageconstraints. Use mathematical modeling methods to achieve minimum energymethod compensation. And work out the minimum energy compensation steps、flowchart and simulation analysis, etc of compensatory strategy. The simulation resultsshows that the method can realize the device outputs the minimum active power atthe same time guarantee the compensation effect. This method can make full use ofthe equipment energy storage, and have high economic benefits.This thesis uses synchronization of coordinate transformation of voltagedetection method to realize to detect the positive sequence fundamental voltageunder the three-phase voltage asymmetry or distortion condition. And fast andaccurate calculate reference voltage.While in the control strategies, discussed the characteristic of feedforwardcontrol and feedback control respectively. Mix them up, this thesis used the hybridcontrol strategy. This method combined the feedforward control and feedbackcontrol’s advantages. Through the feedforward channels can bring the system fasttracking of the change of the power grid voltage. And at the same time gave the loadvoltage feedback control, improved the system damping characteristics, complete thevoltage compensation effects.