Design and Development of Solar Photovoltaic and Battery Based Power Supply System for Grid Integrated Telecom Load

Abstract

Renewable energy based technologies for powering telecommunication loads minimise the burden on the conventional grid while also helping to reduce environmental pollution. The grid and diesel generator based conventional telecom power stations are nowadays substituted with locally available renewable energy sources. This study analyses solar photovoltaic and battery based hybrid power supply systems for telecom stations that are situated in remote areas. To account for changes in PV power generation brought on by the environmental conditions, battery energy storage systems are typically utilised to support solar PV systems. It is possible to feed telecom power stations with multiple renewable energy sources, which are often rated at lower voltage levels, and integrate them into the grid using a suitable power electronic interface and a line frequency transformer. The base transceiver station’s telecom DC load is typically rated for 48 V. The telecom AC load consists of air conditioning and other ancillary loads and are fed from the grid. The solar PV and battery energy storage systems are desired to be operated at lower voltages ensuring safety in operation and the effective power extraction from parallel connected PV arrays. The PV, battery, and telecom DC load, operated at lower voltages, are interfaced to a common low voltage DC bus using a multiport converter reducing the power conversion stages in the system. The low DC voltage of the PV array, battery, and telecom DC load must be converted into a high DC voltage using a high gain bidirectional DC-DC converter for the grid integration. This research is focussed on nonisolated high gain bi-directional DC-DC converters, multiport converters, and a voltage source converter based grid integration. The configurations of power electronic interface for grid integration of a solar PV fed telecom load along with its power flow management control are designed and analysed. The system is designed, modelled and simulated using MATLAB software. Thorough simulation studies are carried out to analyse and verify the system’s various operational modes. A power flow controller is demonstrated for a grid-PV-battery interfaced converter system feeding a telecom load. The performance of the system was satisfactory as evidenced by the regulation of the telecom DC load voltage with reduced overshoot and settling time under dynamic variations in solar PV power. A frequency adaptive second order generalized integral controller is demonstrated for the control of voltage source converter, compensating reactive power and harmonics of the telecom AC load along with real power exchange with grid/AC load. It is observed that the total harmonic distortion of the grid current is maintained within the standards prescribed by IEEE 519. The system’s hardware prototype is also developed and verified in the laboratory and performance is found to be agreeing with simulation and theoretical studies.