| In order to obtain the panorama information of the grid and to achieve the purpose of intelligent control, smart grid combines information technology, sensor technology, automatic control technology and basic facilities of the grid. Condition monitoring of the grid depends on the collection and analysis of the status information by high voltage intelligent electrical apparatus. The grid information is collected and transferred to the line monitoring devices by the sensor, and then sent to the control center by the line monitoring devices to achieve the function of real-time monitoring for the grid state. Those online monitoring devices and communication equipments usually work around high voltage, but they can't use high-voltage directly as power supply and require additional low voltage power supply, which greatly restricts the use of those electrical apparatus. If it's possible to take power from high voltage as the power supply of the low-voltage electronic devices which is working on the high voltage side, it will greatly expand the scope of these appliances and improve the intelligence level of the grid. The purpose of this article is to design a kind of power supply by taking power from the high voltage transmission line, and then research and test on the power taking system through the experimentIt's clear that the key issues of power taking from high voltage which are needed to be solved is how to overcome the influence of current fluctuations and changing environment on the output power. In view of the problems, a new circuit to take power from high voltage is put forward. This circuit mainly consists of a high voltage capacitor and a special isolation transformer in series, then through a capacitance in parallel with the secondary side of the transformer to limit the voltage and a matching inductor in series to improve the output power and stabilize output voltage. The input and output characteristics, load capacity and lightning overvoltage characteristics of the power taking circuit based on the ideal transformer and nonlinear saturation transformer model are simulated. Results show that the circuit is not affected by current fluctuation and environmental factors, the output of power is stable, and the characteristic of resisting lightning is good. According to the characteristics of the circuit, Design principles of the circuit parameter given in this paper. What's more, design scheme of the transformer and inductance and the selection principle of capacitance.A complete power taking system is designed based on this power taking circuit. The power taking system is made up of power taking circuit, regulator circuit, energy storage systems and protection circuit. The energy storage system is a super capacitor bank. So two kinds of voltage balancing schemes, switch resistance method and flying capacitance method, for super capacitors are designed in this paper. The simulation and experiment prove that the effect of voltage balancing is good. Finally, a prototype is made, which works at a high voltage AC 6000V, whose output voltage is 24V and output power is 10W, and then its reliability is tested through experiment. |
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