Design Of Tri-phase Multi-rate Watt Hour Meter Based On Energy Metering IC

The multi-rate electric charge policy is broadly used in our country during these years. It can effectively ease the situation of power emergency, and regulate the electric power load curve. Civil aviation enterprises and factories consume a great part of the annual electricity supply, by positively adopting the multi-rate policy, will not only be helpful to the target of peak shaving and valley filling, but also improve its operation benefits. The tri-phase multi-rate watt hour meter, which is a hotspot of electric power instruments research area in recent years, is specially designed for those civil aviation enterprises. The achievement of this research project can also be promoted to other industry areas.This dissertation discussed the design alternative of this tri-phase multi-rate watt hour meter. The system uses PIC18F452, which has abundant on-chip resources and strong EMC ability, as its master controller. The design strictly referenced the national standard of energy metering, has various functions such as time-sharing energy calculating, time interval management, automatic balancing and RS-485 communication.Firstly, this paper introduces the theory of tri-phase energy and its classical methods of measurement, after that, it put out the design objection and whole frame of this metering system. Several important ICs, such as ATT7026, DS1302 and MAX485 are also introduced. In the 5th chapter, the system is divided into modules. Modules are discussed both in their detailed solutions of hardware and software, which include signal transform and isolation circuits, energy metering and time interval control algorithm, and various communication realizations. The accuracy of RTC, EMC design and meter adjust method have also been discussed.Finally this dissertation gives the running result of this system, and analyzed the accuracy of the meter and its stabilization.