Amardeep B. Shitole

Soft-Switching DC–DC Converter for Distributed Energy Sources With High Step-Up Voltage Capability

This paper presents high step-up dc-to-dc converter for low voltage sources such as solar photovoltaics, fuel cells, and battery banks. To achieve high voltage gain without large duty cycle operation, combination of coupled inductor and switched capacitor voltage doubler cells are used. By incorporating active clamp circuit, voltage spike due to the leakage inductance of the coupled inductor is alleviated and zero-voltage switching turn on of the main and auxiliary switch is obtained. Due to the use of MOSFETs of low voltage rating and soft turn on of the switches, conduction loss and switching losses are reduced. This improves the efficiency and power density of the converter. The proposed converter can achieve high voltage gain with reduced voltage stress on MOSFET switches and output diodes. Design and analysis of the proposed converter is carried out, and finally, a 500-W experimental prototype is built to verify theoretical analysis.

Comparative evaluation of synchronization techniques for grid interconnection of renewable energy sources

This paper presents comparative performance evaluation of conventional SRF-PLL, existing adaptive notch filter (ANF) and an amplitude adaptive notch filter (AANF) based synchronization techniques used for converter-interfaced renewable energy systems. In addition, real time implementation and extraction of frequency and amplitude of the input grid voltage signal by all the three techniques has been presented. Comparative analysis has been done based on their ability in extracting amplitude and frequency variation of the input grid voltage signal under unbalanced and frequency variation condition. The single phase AANF provides high degree of accuracy than SRF-PLL and ANF in extracting appropriate signal information even for unbalanced and distorted grid condition. The important feature of the AANF is its amplitude adaptability, which improves its speed of response and accuracy when grid signal is of variable amplitude. Experimental results demonstrates better performance of AANF for frequency and amplitude detection than existing ANF and SRF-PLL, hence it can be used for wide range of applications such as converter interfaced distributed generation systems, islanding detection in smart grids, various fault detection techniques etc.

Adaptive notch filter based synchronization technique for integration of distributed generation systems to utility grid

This paper presents the adaptive notch filter based synchronization technique used for generation of reference currents for hysteresis current controlled three phase voltage source inverter. These three phase reference current components are then used to control the active power injected by the three phase voltage source inverter. In addition, the proposed control strategy can provide compensation for reactive power demands as well as harmonic load current requirements of the nonlinear loads during interconnection of inverter to the utility grid. Hysteresis current controlled technique is used to control the three phase voltage source inverter. By sensing the actual load currents, an adequate amount of active power, reactive power and harmonic current demanded by nonlinear load will be compensated with fast dynamic response into the utility grid. The effectiveness of the proposed technique is verified with injection of active and reactive power generated by three phase voltage source inverter through MATLAB/Simulink environment. An experimental work is undergoing and can be presented latter.

Soft switched coupled inductor based high step up converter for distributed energy resources

In this paper coupled inductor based high step up converter for dc micro grid is proposed. Switched capacitor based improved voltage extension cell is utilized to obtain high voltage gain. By using extended and improved voltage doubler cell, the voltage stress on the main switch and output diode are reduced. So active switches of low Rds(on) can be used and thus overall efficiency of the system is improved. Active clamp technique is incorporated to limit the voltage excursion on main switch and also to obtain zero voltage switching for both main and auxiliary switches which further improve the efficiency and power density. Design and analysis of the proposed converter is carried out and the result are verified by using PSIM Simulation package. Finally, a 500 W experimental prototype is build to verify the theoretical and simulation results.

Grid Interfaced Distributed Generation System With Modified Current Control Loop Using Adaptive Synchronization Technique

This paper presents real-time implementation of a grid interfaced distributed generation (DG) system with modified current control loop using three phase amplitude adaptive notch filter (AANF) based synchronization tool. A grid current feedback based modified

A Reliable Microgrid With Seamless Transition Between Grid Connected and Islanded Mode for Residential Community With Enhanced Power Quality

dq

Performance improvement of grid interfaced three level diode clamped inverter under various power quality events

-current control technique for interfacing inverter is developed in order to achieve constant loading on the grid, transient-free operation, and power factor improvement close to unity power factor (UPF) of the utility grid during sudden load variations. This technique does not require separate calculation of reference reactive component and harmonics component of currents hence reduces control circuit complexity. In addition, it requires only three voltage and three current sensors. Three phase AANF is developed and is used for online extraction of utility voltage phase angle to generate synchronized reference current signals for interfacing inverter. AANF is used because of its adjustable accuracy and amplitude adaptability even under unbalanced voltage sag and swell, frequency variation, and distorted grid conditions. Fast and accurate behavior of three phase AANF improves the dynamic response of entire DG system control performance for sudden load variations. The dynamic behavior of the proposed grid interfaced DG system is experimentally evaluated in maintaining constant loading on grid, transient-free operation, and power factor improvement close to UPF operation of the utility grid, by compensating total reactive power and harmonic current demanded by variable linear as well as nonlinear load.

Low switching stress DC-DC converter with capability of high voltage gain for low voltage energy sources

This paper presents a reliable microgrid for residential community with modified control techniques to achieve enhanced operation during grid connected, islanded, and resynchronization mode. The proposed microgrid is a combination of solar photovoltaic, battery storage system and locally distributed generation (DG) systems with residential local loads. A modified power control technique is developed such that local load reactive power demand, harmonic currents, and load unbalance are compensated by respective residential local DG. However, active power demand of all local residential load is shared between the microgrid and respective local DG. This control technique also achieves constant active power loading on the microgrid by supporting additional active power local load demand of respective residential DG. Hence, proposed modified power control technique achieves transient free operation of the microgrid during residential load disturbances. An additional modified control technique is also developed to achieve seamless transition of microgrid between grid-connected mode and islanded mode. The dynamic performance of this microgrid during grid-connected, islanded, and resynchronization mode under linear and nonlinear load variations is verified using real-time simulator.

A Comparative Performance Evaluation of Extended AANF with Different Parameter Estimation Techniques for Renewable Energy Integration

Unpredictable power quality (PQ) events such as, balanced and unbalanced voltage sag/swell, frequency shift, phase jump and harmonic distortions in the utility grid voltage drastically affects the performance of a grid interfaced distributed generation (DG) systems due to unreliable synchronization. This paper presents adaptive synchronization based dq-current control technique for three-level NPC grid interfaced inverter DG system. An amplitude adaptive notch filter (AANF) is used for detection of utility voltage phase angle due to its adjustable accuracy and amplitude adaptability. Three phase extension of single phase AANF is developed and its performance is evaluated under aforementioned PQ events. Robust behavior of three phase AANF enhances the control performance of the interfacing inverter in injecting constant current into utility grid under aforementioned PQ events. This technique also operates interfacing inverter close to UPF mode. The efficacy of the proposed control technique in integrating the DG system to the utility grid under aforementioned PQ events is investigated through MATLAB simulation results. The laboratory experimentation is ongoing and can be presented latter.

Soft switched high voltage gain boost integrated flyback converter

Abstract A soft-switched integrated boost-forward converter with switched capacitor voltage extension cell for low voltage energy sources is proposed. Extended switched capacitor voltage multiplier circuit is incorporated at the secondary side of the forward type coupled inductor. Switched capacitors of the voltage extension cell, charge in parallel through the coupled inductor when the main switch is OFF and discharge to the output in series when the main switch is ON. Thus high voltage step-up is achieved and the voltage stress on the MOSFETs and diodes are reduced. Here, the auxiliary MOSFETs switch helps to realize zero voltage switching turn ON of the MOSFET switches and clamp the voltage across the switches. Modeling and steady state analysis of the converter is provided. A 400 W experimental prototype is build and tested in laboratory. Measured full load efficiency of the converter is 94.29% and highest efficiency is 96.03%.