Effective Utilization and Management of PV and Battery Based Power Supply System for Telecom Load

Abstract

One of the major sectors which have seen a rapid growth in the last decade is mobile telecommunications. It has not only become an important part in peoples lives but also playing a part in world business as the entire world is connected by telecommunication networks. The growing power demand and the dwindling fossil fuels resulted in the unreliable power supply, which is the critical challenge facing by telecommunication industries. Currently, telecom towers are using Diesel Generators (DG) as source of supply, which is rather expensive and emits environmental pollutants. This study analyses the solar photovoltaic (PV) system and battery based hybrid power supply system to reduce the usage of DG. The effective utilization and management of the PV and Battery sources increases the efficiency and reliability of the system. Therefore, in this work, a literature review related to maximum power point tracking of PV array, Li-Ion battery aging mechanism and battery state of health (SoH) estimation techniques have been presented. Non-uniform insolation conditions on PV array is the most common phenomenon and it affects the efficiency of the system. Therefore, in this study two global maximum power point tracking (GMPPT) algorithms have been developed. The first GMPPT technique is scanning based two stage hill climbing technique and the second GMPPT technique is artificial bee colony based soft computing technique. Both the techniques have been developed to track the global maximum power point (GMPP) with the fast convergence speed and with the highest tracking accuracy. Moreover, both the GMPPT techniques uses single current sensor for tracking the (GMPP) to reduce the overall cost of the system. The proposed GMPPT techniques are experimentally validated and its performance characteristics are compared with other GMPPT techniques proposed in literature. Battery is the important power source in the PV and battery based hybrid power supply system. Therefore, reliable power supply to the telecom load depends on the health of the battery. Hence, the knowledge of battery aging mechanism is very vital and helps to configure the right time to replace the battery. In this study, mathematical model of a Li-Ion batiiitery with aging parameters and two SoH estimation algorithms have been developed. The first SoH estimation technique measures the degradation in capacity of the battery over a period and thus estimates the life. The second method estimates the life of the battery by measuring the DC resistance. Both the techniques have been validated using MATLAB/Simulink platform and an experimental prototype. The telecom load operates in a pulsed-power mode intermittently, also the power consumption depends on signal traffic. Maintaining the constant voltage at the DC load terminals during the pulsed power operation is the biggest challenge. Therefore, in this study, Type II compensator is developed to regulate the load voltage with fast response time. The stability analysis of system with Type II compensator is analyzed using the MATLAB/Simulink tool. Moreover, the developed voltage regulator system has been tested for various load and also input voltage varying conditions.