The Research Of Power Quality Monitoring Instrument Based On GPRS

With the development of the national economy,the problem of power quality is getting more and more attention of the power companies and users.It's quite necessary to establish the power quality monitoring system,so that we can get full grasp of status of the power grid with which we can improve the power quality.GPRS introduced packet switching method to the original SM net, thus enhanced the transmission speed dramatically.Applying GPRS to the power monitoring devices is of high cost-effectiveness and good applicability for the real-time monitoring.Given the specialty of the power grid,first the development trends and technical characteristics of the power quality monitoring technique is studied,then the method of adopting the SCM as the control chip and GPRS as the communication in the design of the power quality monitoring devices is introduced in this paper.The monitoring devices adopt the high effective and low-power consuming SOC-C8051F020 of the Silabs Company as the core.After a through study of the GPRS technique and the actual needs of the power quality monitoring,the MC35i of the Simens Company is adopted as the GPRS communication module of the devices,which is connected to the GPRS of the monitoring center.In the A/D sampling circuit,the ADS7864 IC is applied to the 6 lines synchronous sampling of the voltage and current signals,and the hardware phase-locked loop technique is applied to controlling of the frequency tracking and synchronous sampling of the signals,so that in one cycle a signal can be sampled to N points evenly as to solve the problem of the spectrum leakage caused by non- synchronous sampling.The software of the whole system adopt module design,which not only improves the operating efficiency,but also enhances the portability and readability of the process.The devices designed in this paper achieved good results in the experiment;the experimental results show that the devices have high measurement accuracy,which meet the requirements of the power quality monitoring,and the long-distance data transmission-which meet the requirements of the real-time monitoring of the power devices-is secure and stable.