The Design Of High-precision Smart Electric Energy Metering System

With the "Smart Grid" concept proposed, the electric energy metering system has to faced multi-function and higher accuracy requirements. However the electric energy meter accuracy has been greatly affected by the problem of voltage transformer secondary circuit voltage drop and imperfect solutions. In order to improve the stability and precision of the electric energy meter, overcome limitations of existing device, this paper proposed an electric energy metering system based on optical fiber transmission and DSP + ARM9 structure. This novel electric energy metering system adopted modular design and included two parts: acquisition- measuring device and synthetic communication device. The acquisition- measuring device applied DSP with high accuracy and high speed to complete grid signal acquisition and calculation.. The synthetic communication device applied ARM with excellent control ability and rich peripheral to complete data management and communication function. WinCE5.0 embedded operation system was installed in the synthetic communication device, providing a friendly human-machine interface. Optical fiber was applied to transfer data from the acquisition-measuring device to the synthetic communication device, which can be free from the interference of electro-magnetic field and with no voltage transformer secondary circuit voltage drop problem.This system can meet the demand of the electric energy meter in substation. Acquisition-measuring device can be installed on electric energy measurement circuit in switch cabinet. Multiple acquisition-measuring devices can transfer data to synthetic communication device through a serial port expansion modular. Synthetic communication device can be installed in control room.A test platform was constructed by using data acquisition card and LabVIEW software to measure the error of this electric energy metering system. Experiment results show that voltage measure accuracy is 0.05 class, active energy measure accuracy is 0.2 class, reactive energy measure accuracy is 0.5 class, better than the existing device.