Research Of Three-phase Watt-hour Meter Based On AT89S52

The intelligent total energy meter is studied and discussed in this paper. With ADE7758 as electrical energy measurememt IC and AT89S52 as control unit, the principium of measuring circuit, and characters of system structure, design and realization of hardware and software for power-subsection are introduced. As to achieving accurate measurement under normal load and lower load for 10～35kV power system, this paper presents a new strategy of three-phase watt-hour meter with the function of real-time measuring in section according to load power. Considering time-unbanlance of power-consumption, another strategy of multi-rate time-subsection measuring to regulate power load curves is also proposed.In this paper, current sensors with double ratios are used to carry out signal detecting and sampling. When the load current is below 20% of rated value, the singlechip regulates ratios of current sensors to lower load measuring circuit, which reduces current sensor's detecting error under lower laod, and enhances accurate measurement. By means of power parameters detecting, the adjustment of measuring circuits between normal load and lower load are finished. Time memory and time-subsection measuring are realized by time parameters detecting.The initial values of ADE7758 are computed according to the configurations of meter parameters. In order to evaluate the authenticity and efficiency for the measuring data, this paper designs the analog input circuits, and uses ME300B to do simulation and debugging on line. Using power parameters as evaluation index, the experiment results show that the measuring data are valid and faithful, by means of comparing power parameters that computed in theory and that displayed by three-phase watt-hour meter.In the design of three-phase watt-hour meter, current sensor with double ratios enlarges the load measuring range and enhances measuring precision. This scheme can be expected to realize the whole-process precision balance and accurate measurement, and also provides a method for real-time subsection measuring. The design process and test process have been finished. With accurate experiment-table, gain calibration and offset calibration can be done,and this scheme has a good application value.