Browsing by Author "Brahmendra Yadav Gorla, N.B.Y."

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A Fault Diagnosis and Postfault Reconfiguration Scheme for Interleaved Boost Converter in PV-Based System
(Institute of Electrical and Electronics Engineers Inc., 2021) Ahmad, M.W.; Brahmendra Yadav Gorla, N.B.Y.; Malik, H.; Panda, S.K.
To utilize the solar photovoltaic (PV) energy efficiently, dc-dc converters are widely used in both grid-connected and stand-alone systems. Among the various topologies, interleaved dc-dc boost converter offers the benefit of modularity, high power density, and high efficiency along with reduced input current ripple to the PV panel, thereby improving its power extraction efficiency. Open-circuit faults in any of the semiconductor switches of interleaved boost converter could lead to unequal loading on the healthy phases and increase in ripple current that reduces the extraction efficiency of the PV system. To address this issue, a new fault detection and localization scheme is proposed in this article. The proposed scheme utilizes the switching-frequency-based harmonic component for fault detection and localization. Once the fault is localized, a postfault restoration and control strategy is also proposed to ensure equal current sharing among the remaining healthy modules within their maximum current rating and minimize the input current ripple in the PV panel. Detailed simulations are carried out to show the effectiveness of the proposed approach. A laboratory prototype of the interleaved converter is built to validate the proposed approach and experimental test results are provided. © 1986-2012 IEEE.
Noninvasive Model-Based Open-Circuit Switch Fault Detection of AC-Bypass Leg Switches in Transformerless PV Inverter
(Institute of Electrical and Electronics Engineers Inc., 2021) Ahmad, M.W.; Brahmendra Yadav Gorla, N.B.Y.; Malik, H.; Panda, S.K.
Transformerless inverters are being used for integrating photovoltaic (PV) sources into the grid. Highly efficient and reliable inverter concept (HERIC) inverter is one such topology, which is derived from an H-bridge by adding a bypass leg on the ac side using two back-to-back insulated gate bipolar transistors (IGBTs). Open-circuit fault in the bypass leg would result in conduction of current through antiparallel diodes of the main switches of the inverter, effectively making the inverter operate in bipolar mode. As a result of the fault, there would not be an issue of leakage current, and the operation would continue at the expense of increased conduction losses and dc-offset in the grid current. This article proposes an online noninvasive model-based technique to detect switch faults in the bypass leg of the HERIC inverter. The grid current at the peak of the carrier signal is predicted based on the measured grid current at the start of the zero states. By comparing the estimated and measured grid currents at the peak of the carrier signal, the faulty switch in the bypass leg is localized. Once the fault is localized, the inverter's modulation scheme is changed to conventional bipolar mode to improve the performance of the converter during the post-fault stage. A detailed simulation study is carried out to verify the effectiveness of the proposed approach. Experimental tests on the prototype converter show that the proposed algorithm can reliably detect the open-circuit fault in switches of the bypass leg, and once a fault is detected, the algorithm would change the modulation scheme to bipolar mode to minimize the inverter loss and dc-offset in the grid current. © 2013 IEEE.
Sliding Mode Observer Based Open-Circuit Fault Detection in the HERIC PV Inverter
(Institute of Electrical and Electronics Engineers Inc., 2022) Muhammad Ramees, M.K.P.; Ahmad, M.W.; Brahmendra Yadav Gorla, N.B.Y.
Grid connected transformer-less Photovoltaic inverter known as highly efficient and reliable inverter concept (HERIC) is derived from the industrial-standard full-bridge topology with two additional switches on ac side. This paper presents a detection and localization method for open-circuit (OC) failures in the semiconductor switches of HERIC inverter. Fault detection based on sliding mode observer (SMO) is proposed for the ac bypass switches and an average current estimator is used to detect failures in the main switches of full bridge inverter. Two parallel SMOs are developed based on the state space model of the converter under different OC fault conditions in ac bypass leg. Observed grid current and measured grid current are used to obtain the residual which determines the location of OC fault in the inverter. The key advantage of the proposed method is that it does not require additional sensors for fault diagnosis which will improve the system robustness. Efficacy and reliability of the proposed method is validated using simulation studies. Â© 2022 IEEE.