This Research Project Is Submitted To The School Of Computing & Information Management In Partial Fulfilment Of The Requirements For The Award Of Master Of Science Degree In Data Communication
The advent of Global Systems for Mobile Communication (GSM) coupled with the technological advancement realized in the industry of Mobile computing and computer networks has culminated in wide application of seamless data communication in the field of electronic commerce. This Project outlines the design and implementation of an electricity Token vending system that loads electricity Tokens directly onto corresponding energy meters.
The Microcontroller based prepaid energy meter system comprises the following key parts; power sensor or Energy Meter IC, Microcontroller, Liquid Crystal Display and Relay Control Units. The energy meter comes in the form of AT89S52 metering chip. The metering IC monitors the instantaneous load current and voltage signals and generates a frequency (pulse) that corresponds to instantaneous active power. The frequency of the instantaneous pulse is fed into the microcontroller (AT89S52), which stores the pulse count and the recharged Token units. Depending on its count constant, the microcontroller decrements the recharge units by one unit each time a specified number of pulses are realized. When the recharged units are finally decremented to zero, the circuit relay is energized and it disconnects the electricity supply until the Tokens are loaded again. On recharge, the Token is received via the GSM based modem. The microcontroller stores the units in the EEPROM and sends the data value to the LCD. At the same time, a boosted current signal is sent to activate the control relay, which finally connects the electricity supply to the premises.
The smart card of the pre-paid energy meter communicates with the power utility server using GSM network, initiated either via power line communication or modem depending on the particular system. Initially, the LCD registers the total amount of recharged units, called Recharged Amount (RA). But as the power is consumed, the LCD value decreases owing to circuit energy expenses, called Expenditure (E) at each instant and then subtracts from the Recharged Amount to obtain a Balance (B). When the balance becomes zero, the Latch Relay is triggered to open and disconnected supply until the meter is recharged again.
