New Monitoring Method Against Abnormal Utilization Based On Local Power Datum

In recent years, with the rapid development of electric power industry, as well as thescale of power system, research on monitoring against abnormal utilization has arousedgreat attention of the electric power staff around the world. The imbalance of three-phasevoltage and current will lead to serious error of electric energy in power system. Anabnormal electricity monitoring terminal designed in this paper is used to monitor themeasurement error of three phase unbalanced operation.A new monitoring method against abnormal utilization is presented in this paper,which applies the power calculation method of three-phase four-wire system to establishthe local power datum after comparing with the actual measurement of three-phasethree-wire power, to determine whether a user has unbalanced load. Normal electricityutilization and unbalanced load is simulated respectively by using matlab and the resultshows that the metering error exists when the load is unbalanced, and the error ismeasuring less electricity power that unbalanced load users consumed.According to the actual requirements, an abnormal utilization monitoring terminal isdesigned based on ADS8556+ARM7. This device includes sampling module, CPUcontrolling module, power supply module, memory module, communication module,liquid crystal display module, keys module, real-time clock module, etc. ADS8556isused as the core of sampling module and the core is used for collecting electricitysynchronously. ARM7is used as the core of data processing and logic controlling, whichanalyzes and deals with the discrete signal sent by sampling module. ZTE ME3000isused as the core of communication module to realize the remote communication betweenmonitoring terminal and background host. Keil3.8development environment used forprogramming, μC/OS Ⅱ system embedded in LPC2378chip, and modular design idea isapplied in programming. The software system is easy to expand and has flexiblestructure.In order to verify the performance of the monitoring terminal, three-phase powersource is taken as electric grid to test the monitoring terminal and analyze the result inthe lab. The results show that: the measurement precision is up to0.5level, abnormalutilization monitoring function is effective, and remote communication runs well.In this thesis the power grid is monitored by the monitoring terminal and then thevalue of practical voltage, current and power is obtained. The practical value and basicvalue are compared through calculating to judge how the power grid runs, at the sametime the GPRS wireless transmission is used to transmit the results to the substationbackground host in order to discover abnormal utilization behavior in time and detect the loss result of statistical measurement error. It is important to save energy and decreaseloss in power system.