With growing population and number of houses it is very difficult to measure and record power consumption in urban areas. Skyscrapers make it still difficult for manual meter reading as it is time consuming and prone to human errors. Moreover that a tiny electricmeter would be conveniently installed at top of electric poles so that bypassing meter can be permanently avoided. For this the meter must be able to be read wireless.
This project is aimed at a solution that provides easy, cost-effective and accurate Automated Metering Reading System or AMR. This system will comprise of
• Digital Meter Unit which consists 8-bit AtMega32 Microcontrollers (AVR) and Zigbee interface for high speed data transfer.
• A Wireless Personal Area Network (WPAN) which will use Zigbee Specification to transfer recorded itemized data.
• Handheld Device which will be used as buffer to collect data from meter (wireless) and transfer it to computer.
The design of this project will consist of four stages. Upon completion the project will be an industrial compliant system complete to be introduced for potential customers in market.
1. Digital Meter Unit using AVR and Zigbee Transceiver
This meter is based on W.S.Woodward's circuit. It does not have any transformers to sample ac current or potential thus is light and cheap. The calculation circuit is based on Gilbert cell arrangement that converts ac power to equivalent dc voltage. This part is ready to use and made as per desired specifications and tested for high temp of about 60 degree celcius.
2. Designing of dedicated Wireless network Protocol using Zigbee
A protocol is required for flawless high speed transfer of data of thousands of such meter to single hand-held over a distance of approximately 200mts. The protocol uses mesh networking and simplest of all modified slotted-aloha protocol. The protocol is developed and tested.
3. Hand-held device for collecting reading from Meters
A hand held device having another AVR microcontroller collects data from client ie meters. The same mesh protocol is developed for two way communication. This device is undergoing design.
• First, host (hand-held device) sends request for retrieval of data (meter reading).
• Clients (Electric Meter) receives request and sends a packet containing current reading (payload) with its client ID (Unique for each electric meter) to host.
• Host receives packet, extract payload (reading) and client ID.
• This information is stored in handheld device’s memory in form of database.
Wireless AMR offers a number of additional advantages:
• AMR meters could be connected in network, just like computers.
• Real-time reading gives up-to-the-minute clear picture of consumption with an details required, even up to single building level. Power Distribution Company now knows where to upgrade cables and transformers. It doesn't have to rely any more on subjective requests of its customers or use often misleading monthly averages.
• Customer is automatically disconnected when his prepaid balance reaches zero.
• Not only multi-tariffs are allowed but they also could be changed remotely at any time.