Proceedings of 2018 International Conference on Emerging Trends and Innovations in Engineering and Technological Research (ICETIETR) 978-1-5386-5744-7/18/$31.00©2018IEEE 1 A Comparative Study of Full-Bridge Inverter based DVR and Semi-Z-Source Inverter based DVR Remya V K Dept. of EEE NIT, Karnataka, India remyavkarthikeyan@gmail.com P. Parthiban Asst. Professor, Dept. of EEE National Institute ofTechnology , Karnataka Avinash Nandakumar Student, Dept. of EEE National Institute of Technology , Karnataka Abstract— There is always a necessity to protect the voltage sensitive industrial systems from Power Quality (PQ) issues to prevent the loss of product quality and revenue. Generally, custom power devices take the responsibility to mitigate these PQ problems, restore the voltage and thus maintain the PQ standards. Dynamic Voltage Restorer (DVR) is one among the custom power devices which offers an economical compensation of load voltage under abnormal supply voltage conditions. The voltage injected in series by the DVR compensates the load profile during PQ events; appropriate voltage injected by the DVR in series with supply protects the load and restores the voltage to pre-defined values. The required injected voltage is generated by the inverter circuit in the DVR system. The most commonly used DVR inverter is the full-bridge inverter which consists of four switches. The Semi-Z-Source (SZS) inverter based DVR which offers same injection capability with only two- switches is compared with the full-bridge inverter. The in-phase compensation technique is employed in both the DVRs for injecting required voltage into the grid. The efficiency, quality of the injected voltage and load voltage are studied. This paper presents simulation results in MATLAB/Simulink environment to validate thecomparison. Keywords—Power Quality (PQ), DVR, voltage sag, Full- bridge (FB) inverter, Semi-Z-Source (SZS) inverter, in-phase compensation, voltage injection capability I. INTRODUCTION Nowadays, the industrial loads are becoming voltage sensitive and any deviation from the pre-defined quality of power results in temporary shut downs, equipment damage and deteriorated end products. The Power Quality (PQ) issues such as voltage sag, swell, flicker, harmonics, notches etc causes loss of production and loss of revenue[1]–[4]. With the advent of power electronics, a new class of power electronic based voltage support solutions are offered by CUPS such as Distributed Static Compensator (DSTATCOM), Dynamic Voltage Restorer (DVR), Unified Power Flow Controller (UPQC) and they bring considerable and measurable improvement in the power quality. The inclusion of these compensating type CUPS in the power line is a prerequisite for profitable operations in the critical industries. During unhealthy supply voltage conditions, these devices help to improve power quality by restoring the load voltage profile [5], [6] . Among the CUPS, the most economical compensation is provided by the DVR [7]. DVR is a series connected compensating device which maintains the load profile to pre- specified standards by injecting appropriate voltage in series with the supply voltage. The DVR structure consists of dc-link and energy storage, converter, filter, injection transformer, bypass equipment and disconnection equipment as shown in Fig.1[8]. The real power source in the DVR is the energy sources such as Battery, SMES (Superconducting magnetic energy storage), super capacitors, flywheel, fuel cell etc [9]. The type of the energy storage determines the type of converter in the DVR circuit [10]. The ac energy source such as flywheel requires ac-ac conversion or ac-dc-ac conversion. If the energy source supplies dc power such as battery, fuel cell etc, the converter type is dc to ac or inverter. The most commonly used inverter in the DVR system is Full Bridge (FB) inverter [11]. The FB inverter based DVR finds application in low voltage to high voltage distribution system. [12],[13]. Fig.1 Basic structure of DVR