Browsing by Author "Krishna, D.G.A."

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A Comparative Study of PI and PDF Controllers for DVR under Distorted Grid Conditions
(Institute of Electrical and Electronics Engineers Inc., 2018) Karthikeyan, A.; Krishna, D.G.A.; Tejaswini, A.; Panda, A.S.; Prasanna, R.L.
In this paper the enhancement of power quality related issue is dealt by using Dynamic Voltage Restorer (DVR). There are mainly two aspects with DVR injection voltages one is reference generation and the other is control of DVR. Under unbalanced grid conditions negative sequence components will appear in the grid voltage and causes continuous oscillations in the estimated dq - voltages, which makes sag detection difficult with conventional SRF-PLL. In this paper Double Second Order Generalized Integrator (DSOGI) prefilter based PLL is used for extracting the symmetrical components of grid voltage and further mitigate the harmonic ripple in estimated dq quantities. Further a Pseudo Derivative Feedback (PDF) controller is proposed for single loop voltage feedback control for DVR. The robustness of the proposed controller is verified through comparative studies with PI controller using time response analysis. It is observed that the proposed PDF controller improves the system dynamics i.e., eliminates oscillations and overshoot compared to PI controller. MATLAB/SIMULINK platform is used to perform simulation studies for the 10 kV system subjected to different disturbances viz balanced and unbalanced voltage sags for both PI and PDF based controller. Finally, the experimental studies are carried out for low voltage DVR of 0.5 kVA, 100 V laboratory prototype. Â© 2018 IEEE.
An Efficient Pseudo-Derivative-Feedback-Based Voltage Controller for DVR Under Distorted Grid Conditions
(Institute of Electrical and Electronics Engineers Inc., 2021) Krishna, D.G.A.; Karthikeyan, K.; Koothu Kesavan, K.K.; Kumar, S.
Grid integration of distributed energy resources has become a technical challenge in the distribution network operation due to the intermittent nature of renewable energy sources and their impact on grid voltage stability. Thus, a dynamic voltage restorer (DVR) is installed in the distribution network system to reduce such grid voltage impact on sensitive loads. In this article, a pseudo-derivative-feedback (PDF)-based voltage controller is implemented for the effective operation of DVR under voltage disturbances. Response of DVR primarily depends upon its controller action. This article addresses the issues in conventional P and PI multiloop controller with and without feedforward path then proposes PDF control strategy for DVR. Using the proposed controller, dynamic performance of DVR is improved. The efficacy of the proposed controller is illustrated by a comparative study with conventional P and PI controller using time response and relative stability analysis. Finally, PSCAD simulation studies for a 10 kV medium voltage DVR and experimental results using a low voltage laboratory prototype DVR are presented to prove the robustness of proposed controller for DVR under symmetric and asymmetric voltage sags. © 2020 IEEE.
A Comparative Study of PI and PDF Controllers for DVR under Distorted Grid Conditions
(2018) Karthikeyan, A.; Krishna, D.G.A.; Tejaswini, A.; Panda, A.S.; Prasanna, R.L.
In this paper the enhancement of power quality related issue is dealt by using Dynamic Voltage Restorer (DVR). There are mainly two aspects with DVR injection voltages one is reference generation and the other is control of DVR. Under unbalanced grid conditions negative sequence components will appear in the grid voltage and causes continuous oscillations in the estimated dq - voltages, which makes sag detection difficult with conventional SRF-PLL. In this paper Double Second Order Generalized Integrator (DSOGI) prefilter based PLL is used for extracting the symmetrical components of grid voltage and further mitigate the harmonic ripple in estimated dq quantities. Further a Pseudo Derivative Feedback (PDF) controller is proposed for single loop voltage feedback control for DVR. The robustness of the proposed controller is verified through comparative studies with PI controller using time response analysis. It is observed that the proposed PDF controller improves the system dynamics i.e., eliminates oscillations and overshoot compared to PI controller. MATLAB/SIMULINK platform is used to perform simulation studies for the 10 kV system subjected to different disturbances viz balanced and unbalanced voltage sags for both PI and PDF based controller. Finally, the experimental studies are carried out for low voltage DVR of 0.5 kVA, 100 V laboratory prototype. � 2018 IEEE.