A New Control Strategy for Achieving Minimum Power Injection of Dynamic Voltage Restorer A . O. A l-M athnani, H. Shareef, A . M ohamed, M . A . M ohd A li , M . A . Hannan Abstract  This paper presents a new DVR design and a control mechanism to minimize active power injection and forced the load voltage to be in phase with grid voltage during the sag, swell and short outage for the non linear load. The control technique incorporates a short time delay and mitigates the harmonic distortion during the charging of the energy storage capacitor. The new design is based on two continuous vector control. It extracts the fundamental components of the measured voltage and current using a 12 switch inverter connected in parallel to improve the time response. The proposed control method is tested on an 11 kV distribution system. Photovoltaic source with a boost converter is included to suppor t the DC source during voltage sag. It shows that the proposed method improve the in-phase compensation technique, minimum active power and response for nonlinear loads. Keywords: Two Continuous Vector Contr ol, Dynamic Voltage restor er , Voltage Sag Nomenclature V th Source voltage I L Load current V L L oad voltage Z th Thevenin equivalent system impedance V 1 Faulted supply voltage vector Angle of DVR A ngle of Z th Angle of V th Angle of load power factor P in Supply input power P out Load power a,b,c Three phase source voltage K p Proportional gain of the PI-controller K I Integral gain of the PI-controller Angular frequency of the grid voltage T s Sampling time T i Integration time I. Introduction A dynamic voltage restorer (DV R) is a custom power device which is used to restore voltage during power quality disturbances such as voltage sags. DVR can maintain load voltage at the desired amplitude during voltage sag or swell, by injecting a compensating voltage in series with the load. The ideal voltage restoration is to make the load voltage unchanged. When a DVR restores voltage disturbances, active and reactive powers are injected from the DVR into the distribution system. In fact, by choosing an appropriate amplitude and phase angle of the DV R injected voltage, one can control the injecting or absorbing power such that compensation with zero or minimum power injection can be realized. This means that either a minimum rated energy storage device can be incorporated into the design or a maximum load ride-through can be achieved with minimal energy storage capacity [1]. A kind of DVR with minimum energy injection is developed to compensate voltage disturbances on distribution systems [2]. Various control strategies have been reported for DV R control. The inverter control strategy will directly affect the performance of the DVR. M any scholars have studied the inverter control strategy for the exploration and research [3]. A multi-loop controller for the DVR is developed to reduce the amount of stored energy [4]. Fuzzy logic control [5] is applied to provide voltage regulation by controlling pulse width modulation (PWM) and maintained the magnitude at 98%. Different compensation techniques including in-phase compensation, pre-sag compensation and phase shift compensation as in [6]. But during the compensation the energy storage decays due to the high injection of the active power into the system. Reference [7] proposed the open-loop controller to guarantee the f ast dynamic response, but in the steady-state load voltage may not be compensated to the desired value. Differently, hysteresis voltage control using fuzzy logic controller in Matlab software as in [8]. The controller can maintain a balanced and constant load voltage during the fault condition and the distortion is generated during the non-linear load. The zero-crossing detection is used to estimate the phase angle of the grid voltage. Fast tracking has been obtained