Unique performance of a standalone solar photovoltaic energy system with SEPIC converter

Abstract

Electricity production using Photovoltaic (PV) energy system is the cheapest among all existing means. The primary source of input to this system is sunlight, which is available plenty in nature. To transfer maximum power available from the PV source at any instant, the service of Maximum Power Point Tracking (MPPT) controllers are needed. Incorporation of the most suited MPPT controller in the system limits the supply of abnormal current, voltage and power to the load. Moreover, the nonlinear behavior of the Solar PV (SPV) module with respect to the output parameters like current, voltage, power depends mainly on climatic conditions like solar irradiation and air temperature of the location. To increase the voltage magnitude of a PV source within a certain limit, PV cells may be arranged in series. The role of a high gain converter in the system is to increase this voltage compatible with the utility. By increasing the duty cycle, high voltage gain can be expected from a Boost converter. The performance of the Boost converter with high gain is not appreciated as a solution for a practical solar PV system on account of the presence of ripples in input/inductor current. This in turn increases the conduction loss and affects the converter power efficiency. Targeting an improvement in the performance of the PV system, highlighting improved voltage gain and converter efficiency, high gain SEPIC converters are proposed and their performance in the system are analysed using various MPPT controllers. The quality of the power obtained from the energy system has a specific dependence on the type of controller and converter used [1]. There are various research work utilizing different controller techniques in search of efficient utilization of energy from a PV source [2,3]. This paper addresses an analysis on the ripples associated with input current, output voltage, output power and power efficiency of a PV energy system, employing a high gain DC-DC converter. Performance analysis is carried out using four different controllers and climatic conditions. A detailed simulation is done on the system and analysis is done based on the outcome from numerical experiments. Even though numerous research contributions are available in the field of solar energy extraction using different controller techniques, this paper specifically concentrates on a high gain converter which multiplies the input voltage to nearly 20 times at the output side. Here an elaborate analysis is done on the system with four different controller techniques in search of the most apt MPPT controller for the system.