Design Of The New Voltage Monitor

According to State Grid Corporation’s development goal of establishing a nationwide unified power supply voltage acquisition system in SG186 project, designing and implementing a new grid voltage monitoring instrument in line with the latest standards has very important realistic significance.Firstly, the functional requirements and performance index is analyzed in this article. Then a hardware design solution along with a variety of communication interfaces is proposed, which makes use of microprocessor LM3S9B96 and dedicated energy metering chip ADE7753 as system core. The wireless encryption unit consists of GPRS module SIM800 E and encryption chip NRSEC3000.Secondly the digital voltage effective value measurement theory is studied in depth and the principles of RMS and MAV calculation methods are described in detail. Systematic error of frequency offset is analyzed, its common compensation means are simulated and compared. Take look-up table as the compensation strategy of system.On this basis, the relationship of waveform factor and waveform distortion factor is derived. Solve the single harmonic voltage effective value calculation of MAV method based on sample values.Software uses the SAFERTOS real-time operating system to allocate resources and schedule tasks. It adopts the modular programming method to realize functions such as voltage effective value calculation, data storage, human-machine interaction and wireless communication. Two buffer protocol architecture and data transceiver control based on finite state machine improve the packets processing efficiency. In order to manage statistics effectively, a database based on nor flash and relevant FTL(Flash Transfer Level) algorithm are designed, which can extend the lifetime of flash, improve the operation’s efficiency and wear leveling. The new voltage monitor’s remote software update program is designed and realized at last. Users can update the device’s application software by GPRS network with the help of remote server.A prototype of the new voltage monitor is developed successfully. Quality detection in Zhejiang Province Electric Power Research Institute confirms that it meets the latest standards of State Grid Corporation. Now it is registered on line of NARI server and ready to run.