三相智能电表设计

CS5467的三相电度表设计

摘要

本文以智能计量总表为研究对象，采用计量芯片CS5467和AT89S52设计三相电度表，介绍了计量电路原理、系统结构特点。针对10∼35kV输配电网正常负荷情况下的精确计量，提出按功率额度计量的电度表设计方案。

采用电流传感器进行信号的检测采样，当负荷电流低于额定电流的20％时，单片机通过检测功率，自动切换到低负荷计量回路，即小电流比计量回路，最大限度降低了电流传感器低负荷运行时造成的信号检测误差，提高电能计量精度。单片机通过对瞬时有功功率的检测，实现了计量回路的实时选通切换和功率分段计量：通过对时间参数的检测，实现了定时存储和分时段计量。

根据电度表参数配置进行CS5467初始化参数计算。为了评估电度表计量数据的真实性和有效性，对模拟信号输入电路进行试验设计，应用ME300B单片机开发系统进行在线仿真调试。以功率参数为性能指标，通过仿真试验，对功率参数的理论值和电度表的显示值两组数据进行分析比较，得出电度表计量数据是真实有效的结论。

采用双变比电流传感器进行电度表设计，扩大了负荷计量范围，提高了电能计量精度，且计量回路切换无需进行人工干预。该方案有望实现全量程的精度均衡和精确计量，为具有实时分段计量功能的三相电度表设计提供一种可行的方案。目前，已完成样表的设计与测试工作。基于精确的试验平台，完成对电度表的增益和偏差校准，即可进行现场试验和数据采集，具有良好的市场应用前景。

关键词：实时分段; 精确计量;CS5467，AT89S52

Abstract

The intelligent total energy meter is studied and discussed in this paper．With CS5467 as electrical energy measurememt IC and AT89S52 as control unit，the principium of measuring circuit，and characters of system structure are introduced．As to achieving accurate measurement undernormal load for 1 0～35kV 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 powerload 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 10ad 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 10ad are finished．Time memory and time．subsection measuring are realized by time parameters detecting．The initial values of CS5467 are computed according to the configurations of meter parameters．In order to evaluate the authenticity and ef|ficiency 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．