Faculty Publications
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Item A study on hybrid Renewable Energy Source interface to the non-ideal grid at distribution level with power quality improvements(Institute of Electrical and Electronics Engineers Inc., 2016) Jayasankar, V.N.; Gururaj, M.V.; Vinatha Urundady, U.Air pollution is one of the prominent issues that we are facing nowadays. The major contributor for air pollution is the waste output of power plants which uses fossil fuels to generate power. Urbanization and industrialization have changed the lifestyle of human society and the need for electrical energy has enhanced significantly. As the conventional energy sources are not capable of serving the purpose, the researchers have turned their face towards Renewable Energy Sources (RES). Energy sources are scattered across the globe, therefore the available green energy at the distribution level is also used to generate electricity. The hybrid combination of wind/solar systems has proved to be a reliable source to the utility. For extracting maximum power from the RES, battery bank is connected across it. Due to the problem associated with the chemical batteries the wind/solar hybrid combination is directly connected to the grid. There are many issues related to the interconnection of RES to the grid which are addressed with the growth in power electronics field. However the power quality issue occurs due to the presence of non-linear loads at the point of common coupling. Shunt active filter has proved to mitigate the problems associated with the non-linear loads. Researchers have limited their work to interconnection of RES to ideal grid voltages which is not the practical case. In this paper the wind/solar hybrid system is modeled and is interconnected to the unbalanced and distorted grid. Also, RES interfacing inverter is added with shunt active filter functionality and hence overall cost curtailment of the project can be achieved. © 2016 IEEE.Item A Transformerless Photovoltaic Microinverter using High-gain Z-Source Boost Converter for Single-phase Grid connected Applications(Institute of Electrical and Electronics Engineers Inc., 2020) Prabhu, N.S.; Damodaran, R.; Balasubramanian, B.; Mishra, S.Microinverters are the latest advancements in the area of photovoltaic (PV) technology due to their compact design. They improve energy efficiency of PV systems due to the reduced effect of non-uniform operating conditions caused primarily by shading. However due to the low output voltage rating of PV modules, high output to input voltage gain ratio is required for microinverters integrated to the utility grid. Several of the existing techniques use transformers or coupled inductors to achieve high gain ratios. These often require precise design and increase the size and cost of the PV system. The Z-source network based high-gain converters can offer superior performance with reduced components, size and cost. However their operation in a microinverter for grid connected applications have not yet been studied. Therefore this paper presents a novel microinverter utilizing a high-gain Z-source boost converter followed by an H-bridge inverter. The principle of operation of the microinverter is detailed and the overall gain ratio is obtained. The operating region in the I-V characteristics of PV module is determined and the control strategies implemented are discussed in detail. Simulations are performed in MATLAB/Simulink platform to validate the performance of the proposed microinverter under possible operating condition. © 2020 IEEE.Item A novel AC module with high gain Z-Source converter and pseudo DC-link inverter(Institute of Electrical and Electronics Engineers Inc., 2020) Damodaran, R.; Dastagiri Reddy, B.D.; Balasubramanian, B.The effects of partial shading in low power PV systems can be considerably reduced by using a single PV module of appropriate rating. Such a system is termed as the AC module in the literature and consists of a PV module along with the required power electronic circuitry, known as module integrated converter (MIC). The AC module integrated with the grid is required to operate at high efficiency and provide an output voltage of the expected magnitude and frequency. In this paper an efficient MIC with pseudo DC-link (pDC-l) for grid integration of AC module is proposed. The proposed MIC is claimed to be high efficient due to the fundamental frequency operation of the inverter. To obtain a pDC-l of required magnitude from single photovoltaic (PV) module, a high gain Z-source buck-boost converter (ZBBC) is used. It is followed by an unfolding circuit which operates at fundamental frequency to convert the pDC-l to sinusoidal output. The fundamental frequency operation reduces the switching losses without affecting the total harmonic distortion (THD). The operation of the ZBBC, when used to obtain a pDC-l output is analysed and a simple closed loop control is developed. The control ensures a pseudo DC-link voltage at the input of the H-bridge that acts as an unfolding circuit. The control also ensures power balance by controlling the current injected to the grid. Simulations of the proposed AC module with ZBBC cascaded with pDC-l inverter have been carried out using MATLAB/Simulink platform and the results are presented to validate the proposed MIC and its closed loop control. © 2020 IEEE.Item Grid integration of wind and photovoltaic hybrid energy system(Universitatea Politehnica din Timisoara blucretiu@yahoo.com, 2014) Vinatha Urundady, V.; Vittal, P.K.Hybrid energy system usually consists of two or more renewable/nonrenewable energy sources. Currently hybrid systems involving wind power as one of the constituent along with fuel cell and/or photovoltaic power are more appealing. The main purpose of such hybrid power systems is to overcome the intermittency and uncertainty of wind energy and to make the power supply more reliable. Hybrid wind power with fuel cell can avoid the drawback of wind power intermittency, since fuel cell can act as an energy barrier and adjust the power output effectively. Wind power and solar energy can be combined into a hybrid system, especially for the power supply for remote areas where the cost of transmission line is too high. Another advantage of this kind of hybrid system is that they are both renewable energies, which is compatible to the environment. In order to deliver the stable power to the load, a substantial battery bank is needed, which enhances the size of the system, cost and also causes environmental pollution. The deployment of battery can be avoided by directly connecting the hybrid system to the grid. The work presented in this paper consists of modeling and simulation of wind and photovoltaic hybrid energy system inter-connected to electrical grid through power electronic interface. The power conditioning system is implemented to control power electronic circuits and system performance is evaluated for different input power levels and load variation.Item Sliding Mode Controller with Integral Action for DC-Link Voltage Control of Grid-Integrated Domestic Photovoltaic Systems(Springer, 2020) Kumar, N.B.; Urundady, V.The grid integration of photovoltaic systems is preferred over the islanded mode of operation as the former does not require additional storage element, hence less maintenance and no chemical pollution. To regulate power exchange between the grid and the photovoltaic system, a robust DC-link voltage controller capable of withstanding the intermittent nature of solar energy and sudden variations in load is inevitable. A proportional–integral controller is used for DC-link voltage control, exhibiting oscillations during steady state and overshoot during transients. However, the conventional sliding mode controller reduces the overshoot at the expense of increased steady-state error. This paper proposes a robust sliding mode controller for DC-link voltage control to reduce steady-state error by incorporating integral action to the conventional sliding mode controller. The harmful effect of chattering phenomenon is minimised by limiting the error in the control variable using a signum function. The added features of the work include an incremental conductance method for obtaining maximum power from the photovoltaic system, instantaneous pq theory-based self-tuning filter for the extraction of fundamental component and inverter switching pulse generation using hysteresis current control technique. The grid-integrated photovoltaic system along with all features is modelled and simulated in MATLAB/Simulink platform. The results of numerical simulations carried out for various system conditions illustrate that the proposed controller provides superior performance when compared to proportional integral controller and conventional sliding mode controller in terms of harmonic compensation, power flow balance and speed of response at all system conditions. © 2020, King Fahd University of Petroleum & Minerals.Item Control of Converter for a Solar PV-BESS Powered Telecom Load With Real, Reactive and Harmonic Power Exchange With Grid(Institute of Electrical and Electronics Engineers Inc., 2023) Sheeja, V.; Kalpana, R.; Subramaniam, U.; Almakhles, D.J.Due to safety considerations and the challenges involved in tracking the maximum output of series-connected cells, solar photovoltaic (PV) arrays are generally operated at lower voltage levels. A multiport converter can be used to interface telecom DC loads, typically rated at 48 V and powered by PV arrays and battery energy storage system (BESS). The grid integration of the system improves reliability while lowering the BESS rating. This work proposes a sliding mode control-based power flow management controller that maintains the load voltage of a telecom DC load, allows maximum power extraction from the PV module, and facilitates power sharing with AC grid. A voltage source converter and a high-gain bidirectional converter exchange power with the AC grid. A second-order generalized integral algorithm-based voltage source converter control is provided to inject/absorb active power, reactive power, and eliminate the harmonics of the telecom AC load. Detailed simulation studies employing MATLAB software are performed to validate the functionality of the converter as well as the power flow management control. Moreover, the system's performance is evaluated using a laboratory-developed experimental prototype. © 2013 IEEE.Item A non-isolated bidirectional high gain integrated multiport converter for grid tied solar PV fed telecom load(John Wiley and Sons Inc, 2023) Sheeja, V.; Kalpana, R.; Singh, B.; Subramaniam, U.; Muhibbullah, M.A multiport converter (MPC) with a non-isolated high gain bidirectional port is proposed for the grid integration of solar photovoltaic array (SPA) fed telecommunication load. The SPA along with a battery energy storage (BES) meets the power demand of the telecom DC load and the excess/deficit power is exchanged with AC grid. The MPC feeds the DC link of a voltage source converter for bidirectional operation with the AC grid. The small signal analysis of the converter shows that its operation is stable. The SPA, BES, and telecommunication load are rated for lower voltages, consecutively reducing the complexity with series-connected SPA. The proposed MPC possesses the merits of high voltage gain, reduced inductor size, and reduced number of components. Moreover, a power flow management algorithm is devised for the proposed converter that regulates the DC voltage at the telecom load and ensures smooth power flow control among various ports. The MPC is able to operate at various modes by controlling the ports independently. The converter performance during steady state and dynamic operating conditions under various modes are analyzed with detailed simulation studies. An experimental prototype is developed and test results are demonstrated to prove the viability of the designed converter. © 2022 The Authors. IET Power Electronics published by John Wiley & Sons Ltd on behalf of The Institution of Engineering and Technology.Item A Nonisolated High Gain Bidirectional DC–DC Converter With Reduced Switch Count: Analysis and Implementation(Institute of Electrical and Electronics Engineers Inc., 2025) VSheeja, S.; Kalpana, R.; Singh, B.This article investigates a bidirectional dc–dc converter having a very high voltage gain for grid integration of a microgrid supported by renewable power sources. The proposed converter interfaces the low-voltage solar PV and battery energy storage systems with a high-voltage system. Because of its large voltage gain both in forward and reverse operating modes, the proposed converter can be used at lower and moderate duty ratios. In comparison to previously reported topologies of a similar nature, this converter can provide better performance with fewer switches and passive components, resulting in better efficiency. The input current's ripple is observed to be lowered as a result of the parallel operation of inductors. The converter stability is investigated using state space modeling and small signal analysis. The laboratory hardware prototype confirms the suggested converter's effectiveness for bidirectional operation, and the outcomes are in line with theoretical studies. © 2020 IEEE.