Stabilization of Load Voltage under Fault Condition by Using Grid Integrated PV Fed Super Lift Luo Converter

Abstract

This paper focuses on performance of a DC-DC Converter called Super-Lift Luo Converter for load voltage stabilization during faults as well as during variation of temperature. The converter which is fed by a PV System as input stabilizes the DC output voltage during variation of temperature which is fed to a multilevel inverter where it gets converted to AC Voltage and this converter also improves voltage quality on AC Side during fault condition. In this work, first a normal Luo Converter performance is analyzed under fault conditions and then the Super-Lift Luo Converter performance is studied.

Introduction

I. INTRODUCTION

Power generation by utilizing renewable energy sources like solar, wind etc. have overcome the many setbacks and disadvantages associated with conventional energy sources. The majorly utilized renewable energy source is Solar PV System due to the advantages it provide like its available everywhere, can be installed anywhere near house, industry etc. The recent application of such energy sources is that they are integrated to an electrical grid, such a power system is known as Grid Integrated PV system or Grid tied PV System [8].

The advantages associated with such system is that the overall reliability of the power system is increased and whenever there are faults in grid, the PV system can provide sufficient power without affecting the functionality of the load.

PV Systems are dependent on Temperature and Irradiation, the temperature changes throughout the day and its variability are especially observed during monsoons, such variability may cause variation in PV output voltage and this voltage cannot be directly fed into the grid and it must be regulated regardless of any temperature variation. For this purpose, a DC-DC Converter controlled in closed loop fashion must be used [14].

The regulation of DC output voltage of PV System regardless of variation in temperature, was already obtained by using Luo converter and Super-Lift Luo Converter where the mitigation is provided by controlling duty cycle by utilizing a closed loop control [1] , [3].

his regulated DC Voltage is fed as an input to Cascaded H-Bridge Multi-Level Inverter whose AC output voltage is used for grid integration [7], [11], [13]. The MLI is switched by using Multicarrier Pulse Width Modulation [6].

This paper mainly focuses on how such system operates when a fault occurs on the transmission lines on grid side, its performance is studied and it was observed that under fault conditions due to the size and increased number of components in Luo converter transients were introduced into the PV System, this in turn led to increased settling time of Regulated DC Output voltage, Overshoots as well as Oscillations and Steady state error were also introduced into the DC Voltage [16]. These oscillations and less steady state accuracy made their way into the load. This resulted in oscillations as well reduction in load voltage.

To overcome such disadvantage a more advanced configuration or DC-DC Converter called Super-Lift Luo Converter is utilized [4], [5].

The advantage associated with this converter is that the size as well as energy storage components were reduced due to which no transients were introduced into PV System and PV System is protected [15].

Due to the absence of input transients the overshoots, oscillations, steady state error were all eliminated and DC Voltage is regulated at required. The response time is also reduced. This led to enhancement of Load voltage along with eradication of oscillations in the Load Voltage.

Conclusion

Hence, from above simulation results it can be inferred that when Luo converter is used voltage is regulated but when a fault has occurred in grid a huge transients were introduced into PV System and also the output regulated DC voltage experienced slow response, high settling time, oscillations , steady state error, less accuracy as well as overshoots these oscillations and steady state error have made their way to load voltage where the effect is that the load voltage is reduced as well as it became oscillatory. So, it was proposed to use a Super-Lift Luo Converter which employs reduced number components, reduced size of components its effect is the regulated output DC voltage performance is improved as well as PV system is protected from transients under fault conditions. Due to the improvement in Performance of DC Output Voltage the Load Voltage was also improved and %THD is very much reduced, oscillations and overshoots eliminated and steady state error also eliminated.

References

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Copyright

Copyright © 2023 Kondapalli Surya Teja. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.