The Study Of Dynamic Voltage Restorer Based On Voltage-Space-Vector PWM Control

The quality of electric power in modern power system is an issue. That is nowadays gaining significant interest to both electrics and end users. Waveform distortion caused by nonlinear equipment and voltage sag caused by short circuits etc. and other power quality problems compose the main research of modern power quality. Voltage sags are now one of the most serious imperil to modern informational social.Dynamic Voltage Restorer (DVR) is a custom power device that is connected in series with the distribution system to protesting sensitive loads from voltage sags. A DVR can compensate voltage to a normal in a few milliseconds, and also can restrain the voltage disturbances such as harmonic distortion, flicker etc. It's a useful device to restrain the problems of dynamic voltage.This paper analysis DVR for the real-time detection and control of voltage sags and puts forward a new method named the fasting method of the d-q conversion of instantaneous voltages. The method proposed possess the superiority of high accuracy and fast dynamic performance, which can be used to instantaneously quantify the magnitude, duration and phase-angle jump for single-phase. Phase-jump compensation is achieved using a phase-locked-loop method. The network phase tracking method and pre-fault compensate that Especially it can compensate fast voltage disturbances such as sags or swells. It's very useful for estimate of a DVR on detection and compensation control.The controls of a DVR include reference injected-voltage control andthree-phase inverter control. The paper study the vector-control of three-phase voltage-source inverter with lead-acid batteries to provide real power, based on the voltage-space-vector PWM (VSVPWM) algorithm is presented. VSVPWM inherit the excellence of SVPWM, which have high using rise and fast dynamic response. VSVPWM is a direct voltage control, which base the space voltage vector instruction that come from synchrony-rotary-coordinate, then uses SVPWM control make space voltage vector track the instruction of voltage vector, last attain the purpose of voltage control directly. The switching strategy based on seven-section sequence scheme and low total harmonic distortion, which heighten the utilization ration in the DC of the DVR and reduce the switching loss and gain a good dynamic natural. Simulation results are shown to validate the control methods.