Feasibility Study on Real-time Measurement System of Voltage-Current Waveform in Molded Type of Voltage-Current Sensor in Power Distribution Systems

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The real-time observation of a power factor will be essential for the maintenance and the stable voltage regulation in three-phase power distribution systems. Recently, the higher harmonics effect, that may be produced through solid state power converter and inverter systems in factories and homes, has been a serious obstacle, that will result in the destruction of the power apparatus such as an inductor for phase compensation. Therefore the concurrent measurement of both the voltage and current waveforms must be an indispensable technology in power distribution systems. To carry out the concurrent observation of both the voltage and current waveforms, we have devised and proposed a resin molded type of voltage-current sensor, where the design of the geometry of electrodes will be free to some extent, and discussed the fundamental behavior of the new sensor theoretically using the Finite Element Method (FEM).In this project, at first, we have investigated the transient electromagnetic phenomena in the present resin type sensor using the modified FEM analysis aided by the backward finite difference method. As a result, we-have been able to grasp the dynamic behavior of the sensor including the higher order harmonics, that have been observed in the current waveform of the sensor under the pseudo power distribution system at our laboratory. We have designed and implemented the real-time observation system using the Hitachi Microprocessor H8 single board computer system, that has the 10 bits A/D converter and the Ethernet adapter, and the wireless local area network router. Using the H8 operating system(H8 OS), that supports the data based on the HTTP protocol(the port number of 80), when the data acquisition request will be thrown to the single board computer system, the digital data through the AID converter will be obtained over the wireless local network system.