Design and Implementation of a Switching Converters Based Power System for Regions Victim to Frequent Power Outage

摘要

This paper documents a design and implication of an efficient and low cost power electronic converters based power supply system to the localities which are prone to frequent power outage and poor on-grid voltage regulation. The proposed system offers a grid integrated power circuit producing 230 V ac (mains R.M.S. voltage in Bangladesh and South Asia) from a 12 V dc source. The presented system consists of a grid interfaced battery charging unit which incorporates a 230 V-to-12 V step down transformer and a rectifier fed dc link step up (24 V) converter. The battery charging unit comprises galvanic isolation and a Pulse Width Modulation (PWM) controlled Boost converter to ensure protection and a suitable charging voltage level respectively. The power inverter has been constructed using semiconductor switches and transformer action for voltage and power transformation. During on-grid condition, the receiving-end utilities and the converter based power unit are fed power by the mains line. During off-grid condition, the customized power unit serves the utilities and the transfer from grid to the customized power unit is automatic and instantaneous. The transfer application has been substantiated by a changeover relay and there is a switching relay circuit to control and prevent the over-charging phenomenon of the battery. The overall system has been implemented on a base power of 250 w and the testbed contains load banks of different ratings varying from 60 w-to-192 w and a CPU+Display unit rated with 250 w respectively. The system is oriented to supply power in case of outage and thereby power supply unit has been tested on the basis of duration of considerable power transfer to the loads. The laboratory assessment and test results corroborate the reliability and cost-effectiveness of the proposed power system.