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Development of Analyzing System for Power Factor and Harmonic Direction in Electric Power Distribution System using FA Computer
Abstract
In these days, the electric power is essential for our life. The electronic technology makes rapid progress and the electrical instruments get our life to be convenient. However, some of them have the circuits generating the harmonic. For that reason, the wave of electric current in electric power distribution system can be distorted, and it gives a lot of instruments damages. Therefore, measuring the quality of electric power is needed for supplying the stabilized electricity. In this study, the authors have developed a system for analyzing the power factor and the direction of harmonics with FA computer. When the users measure the states of electric power, they can use it through Web browser. In this system, FA computer measures the voltage and current, performs AD conversion, and sends data to a remote Web browser. The Web browser calculates the power factor and the direction of harmonics, and displays the result of analysis.
- The current sensor of the voltage-current sensor system proposed by us comprises two air-core sensing coils connected in series to each other with an opposite polarity. By doing so, it can measure the harmonics and power factor while removing the influence from power lines of other phases. When the sensors are surrounded by an iron case of a pole switch, EMF may be influenced. However, it has been confirmed that a large change is not observed with regard to measurement of harmonics, and the proposed sensors including a voltage sensor can be available without problem. Therefore it has been found out that the proposed sensor is able to perform power measurements in a state of being incorporated in the pole switch.
- As a result of the progress in renewable energy technologies, distributed generation (DG) with harmonic compensation capability has become an attractive topic. If photovoltaic (PV) systems have harmonic compensation functionality, they can help suppress the harmonic currents produced by multiple harmonic sources like energy-saving household appliances. This paper proposes harmonic circulate control, which is a harmonic suppression method that uses DG units. Using the proposed method, the current distortion in three-phase distribution grids can be suppressed by a smaller number of harmonic compensators than with conventional methods. In order to verify the validity of the proposed control strategy, experimental results using a laboratory system are presented.
