Girish G. Talapur

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

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Hybrid Control of High-Efficient Resonant Converter for Renewable Energy System

-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.

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

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

This paper presents the hybrid control of a dc–dc resonant converter for a dc micro-grid. The hybrid control is the simultaneous variation of the frequency and the duty ratio, which can provide excellent voltage regulation and maintain zero-voltage switching (ZVS) over a wide load range. Hence, excellent conversion efficiency is also maintained over the wide load range using hybrid control. However, the conventional control methods for a dc–dc resonant converter using either variable switching frequency or duty ratio have their own limitations. The frequency control requires wide variation in switching frequency for output voltage regulation, which leads to higher switching losses at turn-off of switches and lower efficiency particularly at light loads. The duty ratio control has a limitation of loosing of ZVS at light loads. The simulation and experimental results of hybrid control of resonant converter operating above 100 kHz with maximum duty ratio of 0.48 for 3 kW are presented from full load to no load. The maximum efficiency of the resonant converter is found to be 98%, which was achieved at 75% of the full load.

Resonant Converter for renewable energy with utilization of transformer magnetizing inductance as shunt element

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 This paper presents real time performance evaluation of three phase extension of an amplitude adaptive notch filter (AANF) for online estimation of frequency, amplitude, and sequence components of the input grid voltage signal. The performance of an extended AANF is compared with conventional synchronous reference frame-phase lock loop (SRF-PLL), enhanced phase lock loop (EPLL), and existing adaptive notch filter (ANF). Comparative analysis has been carried out based on their ability in extracting frequency and amplitude of input grid voltage signal under balanced and unbalanced voltage sag/swell, frequency shift and distorted grid condition. Three phase AANF method provides high degree of accuracy than SRF-PLL, EPLL, and ANF in extracting appropriate signal information for unbalanced and harmonically distorted grid condition. The important feature of this method is its amplitude adaptability, which improves its speed of response and accuracy when grid signal is of variable amplitude. OPAL-RT’s (OP4500) real time controller with an in-built Xilinx Kintex-7 FPGA processor is used for real time implementation. Experimental results validate fast and accurate performance of an extended AANF in extracting frequency, amplitude, and sequence components of the utility grid voltage signal, which can be further used for performance improvement of grid connected renewable energy systems, custom power devices, and flexible ac transmission systems (FACTS) devices.

Performance improvement of digital variable band hysteresis current control using dual processor microcontroller

This paper presents a Resonant Converter with high frequency transformer(HF) magnetizing inductance (Lm) considered as shunt inductance. The resonant network comprises of series branch (Ls&Cs) and shunt branch (Lp&Cp). Shunt branch inductance (Lp) of resonant converter is used as magnetizing inductance of HF transformer. HF transformer is designed in such a way that Lm is equal to Lp which in-turn eliminates need of shunt branch inductance Lp in the resonant converter design. The proposed converter optimizes resonant circuit design for power source to minimize no-load and full load losses along with transformer magnetizing inductance as (Lp). It is shown that by considering above concept the converter can be controlled at higher frequency with higher efficacy and also provides greater flexibility as same as considering shunt branch in converter and also reduce the weight and size of power converters. Properly designing shunt and series branch elements one can regulate the required output voltage and achieve as low ripple in the output.

Soft-Switched High Voltage Gain Boost-Integrated Flyback Converter Interfaced Single-Phase Grid-Tied Inverter for SPV Integration

An improved high voltage gain boost integrated flyback converter with quasi resonant voltage multiplier cell is proposed for low voltage energy sources. MOSFETs of the proposed converter are turn ON with ZVS, whereas all the diodes of the resonant voltage multiplier cells turn OFF with ZCS. This results higher efficiency compared to the conventional passive clamp boost integrated flyback converters. Proposed converter makes use of a small sized coupled inductor. Hence magnetic utilization is improved. A 250W prototype is build and tested and the results are provided.

Modified multilevel topology for grid integration of high power solar PV system

In this paper digital implementation of variable band hysteresis current control for grid connected inverter is presented. The current control technique is implemented in both single processor TMS320F28377S and dual processor TMS320F28377D microcontroller. The step by step implementation of variable band hysteresis current control is explained in detail with flowcharts. Experimental evaluation of grid connected inverter with variable band hysteresis current control technique using both single processor and dual processor is presented. Improvement in the inverter output current THD using dual processor implementation over single processor is experimentally analyzed.