Develoment And Research On Multiparameter Digital Display For Low-Voltage Power Grid

Multiparameter digital display for low-voltage power grid is used for real-time measuring three-phase AC signal of low-voltage power grid. It not only can measure VRMS, IRMS, power and power factor, etc. and also can alarm and make protection on the grid when it is in the abnormal states such as short circuit, over-current, over-voltage, under-voltage. The measuring data can be viewed directly through the LCD, and can be transferred to PC for further control and analysis. The three-phase electrical parameter measure instrument design in this paper has the advantages of low-cost, high-precision, high-performance, and has the functions of measurement, control, protection, digital display and communication, which is usually used in electrical distributing box and power supply monitor room.In this paper, the development of electrical parameter measure equipment is introduced first, and then the current commonly electrical parameter measure techniques are analyzed comparatively, finally an electrical parameter measure module's overall design under the technical requirements and features is confirmed. High-precision energy measure chip ADE7758 with high-performance MCU AT89S52 is adopted in the hardware. ADE7758 collects current signal from current transformer and voltage signal from dividing resistors, and calculates through internal functional units, and the results are read and calculated by MCU AT89S52 and stored in FRAM and displayed in LCD. The keyboard is used to toggle the display of data and adjust the real-time time. In order to achieve centralized management and optimal control, the data can be transmitted from MCU AT89S52 to upper computer effectively by RS-232C standard bus communication. Software consisting of main program and various service subprograms such as electrical parameter measurement, data storage, data display, serial communication, etc. is programmed by the use of function module design. At the same time, measuring precision is improved by calibration and expiation functional units of ADE7758.After repeated testing and debugging, the multiparameter digital display for low-voltage power grid design in this thesis completes three-phase electrical parameter measurement and display and reaches the design requirements. It is many advantages, such as high-precision, multi-function, low cost, friendly interface, and easy operation. After enhancing its reliability and stability, the system will have a much more broad application prospect.