High-Power Closed-Loop SMPC-Based Photovoltaic System Characterization under Varying Ambient Conditions

Pallavi Bharadwaj,Vinod John

doi:10.3390/en14175296

Abstract

Photovoltaic energy generation potential can be tapped with maximum efficacy by characterizing the source behaviour. Characterization refers to the systematic terminal measurement-based PV modeling which can further facilitate output prediction and fault detection. Most of the existing PV characterization methods fail for high-power PV array due to increased thermal losses in electronic components. Here, we propose a switched-mode power converter-based PV characterization setup which is designed with input filter to limit switching ripple entering into PV array under test, thereby enhancing system life and efficiency. The high resonant frequency input filter ensures its compactness with high-speed characterization capability. To further enhance the system performance, a closed-loop current control of the system is designed for high bandwidth and stable phase margins. Variation of the controller parameters under varying ambient conditions of 200–1000 W/m2 irradiation and 25–70 °C temperature is documented and an adaptive PI controller is proposed. Experimental and simulation results validate the high performance of the closed loop operation of the PV characterization at 1.2 kW range power level in real-time field conditions. Compared to the open loop operation, the closed-loop operation eliminates the waveform ringing by 100% during characterization.

Highlights

Photovoltaic characterization is extremely useful in PV research for output prediction, fault diagnosis, and system efficiency estimation
This shows that the open loop system settles faster with very high overshoot and ringing as compared to the closed loop operation of the PV characterization set up
In this work, the design, development, and implementation of a high-power closedloop photovoltaic characterization setup based on switched mode power converter is presented

Summary

Introduction

Photovoltaic characterization is extremely useful in PV research for output prediction, fault diagnosis, and system efficiency estimation. PV characterization finds direct application in performance assessment of different PV technologies [1] based on which the optimization of photovoltaic devices and systems can be achieved [2]. The gain is enhanced for higher bandwidth. With the introduction of the adaptive gain PI controller: at low duty ratio of 0.05, a bandwidth of 237 rad/s is achieved showing a seventeen time improvement compared to the fixed gain PI controller. On further analysis it is seen that the performance near 0.25 duty ratio can be enhanced with a gain of 4, as higher gain at this condition reduces the phase margin.

Methods

Results

Conclusion