Three Phase Electrical Parameter Measure And Study Of Harmonic Current Detection

To realize safe, high efficient, economic operation of power grid, it is important to detect three phase electrical parameter and real-time monitor operating condition of power grid. It only has measure for voltage, currengt and power and routine protection in usual electrical distributing box. So it is practical and valuable to design measure equipment include measure, digital display, control, protection and communication which is used in modern housing district and centralized power supply monitor-room. Measure equipment the paper designs for the problem can not only measure virtual value voltage and current, electric power, electric energy of three phase, but also detect the lack of phase and correctness of phase- sequence for power grid. Control and relay protected circuit is designed for abnormal state such as over-voltage, over-current and leak current. We can watch the data intuitively by display circuit. The system transport data that we need to monitor and analyze to PC.The paper introduces development and background of electrical parameter measure epuipment first, and designs measure circuit using special measure chip ADE7758 and double MCU. ADE7758 is high precision special measure chip which integrate ADC, digital integrator, temperature sensor and digital signals processor for electrical parameter calculation. Compare with traditional method, system using ADE7758 has merit such as predigested peripheral circuit, low cost, high precision and dependability. Main singlechip can read measure and calculate data from ADE7758. External chip E2PROM can memorize data when the system starts in abnormal condition. System designs data sampling circuit for leak current and monitor leak current r. Relay protection circuit reacts quickly when system is in abnormal condition as over-voltage, over-current, lack of phase and leak current. Slave singlechip achieves data display. We can exchange data between measure system and upper computer by RS232 bus. It is advantageous to realize automation of electric power system.The paper designs software for MCU that realize the function of system. Meanwhile, it optimize software for the dependability and real-time of system. The paper designs calibration and expiation software by using characteristic of ADE7758 which improve measure precision.The paper analyzes development and research actuality of detecting harmonic current. Then it researchs simulation of detecting harmonic current based on instantaneous reactive power theory and puts forward advanced detecting method. Through simulation by simulink proves favorable measure precision and dynamic response. It offers theory basis for detecting harmonic current circuit of measure system.