2. Conference Papers
Permanent URI for this collectionhttps://idr.nitk.ac.in/handle/1/7
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Item Design and Analysis of Multi-Loop Feed Forward Control Schemes for DVR under Distorted Grid Conditions(2018) Karthikeyan, A.; Abhilash, Krishna, D.G.; Kumar, S.; Nagamani, C.Voltage sags are considered as important power quality problems and the Dynamic Voltage Restorer(DVR) is an effective solution to mitigate the sags and other power quality problems related to voltage. The DVR involves two major aspects: (i) reference generation and (ii) control algorithm. Under unbalanced grid conditions the presence of negative sequence components in the grid voltage causes sustained oscillations in the estimated dq- voltages, which makes sag detection difficult with conventional SRF-PLL and there by chances of controller malfunctioning. In this paper, a Delayed Signal Cancellation (DSC) pre-filter based Positive and Negative Sequence Extractor (PNSE) is employed to extract the Instantaneous Symmetrical Components (ISC) of the grid voltage and filter out the harmonic voltages from the estimated dq-voltages. As the response of the DVR mainly depends on the controller action this paper presents an multiloop PI feed forward controller for enhancing the operation of DVR under distorted grid conditions. The efficacy of the proposed controller is illustrated by comparative study with multiloop feed forward P controller using time response and relative stability analysis. Simulation studies are performed in PSCAD/EMTDC for a 10kV medium voltage DVR under various voltage disturbances such as symmetric and asymmetric voltage sags. � 2017 IEEE.Item Standalone single stage PV fed reduced switch inverter based independent control of two PMSM drive(2019) Karthikeyan, A.; Prabhakaran, K.K.; Abhilash, Krishna, D.G.; Nagamani, C.This paper proposes a standalone singe stage PV fed air cooler which consists of two motors (fan blower and water pump). The proposed system comprises of PV source, reduced switch inverter and two PMSM drive. The proposed system aims at reducing the switching losses and overall cost by using reduced switch inverter. The reduced switch inverter uses only eight switches whereas the conventional VSI utilizes twelve switches. In the proposed scheme, blower and pump are independently controlled using field oriented control scheme where speed reference is obtained using Perturb and Observe (PO) technique. Simulation studies for the proposed PV fed two 400 W PMSM driven blower and pump is performed using MATLAB platform and respective results are presented to show the efficacy of the system. � 2018 IEEE.Item Uncertainity and disturbance estimator based control of transformerless DVR(2019) Karthikeyan, A.; Abhilash, Krishna, D.G.; Kurra, S.; Prabhakaran, K.K.This paper presents Uncertainty and Disturbance Estimator (UDE) based control for Transformerless Dynamic Voltage Restorer (TDVR). The proposed UDE based control algorithm for TDVR mitigate the voltage disturbances and maintain robustness during parameter (filter) variations. The control equation of UDE is derived based on the dynamic model of a voltage source inverter along with the LC filter. The proposed UDE control estimates the uncertainties and disturbances by an appropriate filter (loop filter involved in the derived UDE control law) and used for further synthesis, thus accounts for robustness. The simulation studies are performed for 230 V low voltage (LV) system in MATLAB to verify the efficacy of UDE control for symmetric and asymmetric voltage sags along with the parameter mismatch (inverter filter) conditions. � 2018 IEEE.Item Virtual Impedance based DFCL for DVR during Downstream Faults(2018) Karthikeyan, A.; Abhilash, Krishna, D.G.; Nagamani, C.This paper proposes a Downstream Fault Current Limiter (DFCL) for DVR during downstream faults. It Is based on the concept of Virtual Impedance (VI) which introduces the impedance in series to the system to suppress the large fault currents in the line. In the present work no additional equipment is involved for limiting the fault current and DVR itself is controlled such that FCL operation is ensured. The proposed VI based FCL features flexible implementation and can effectively suppress the fault current during the downstream faults and thereby the DVR is protected along with restoration of PCC voltages. Simulation studies are performed for 10 kV system using PSCAD/EMTDC platform and respective results are presented which proves the feasibility and efficacy of the proposed FCL. � 2018 IEEE.