Research On Frequency Conversion Control System In Beam Pumping Unit Based On DC Bus Power Supply

ABSTRACT:At present, variable frequency control devices for beam pumping unit are applied more and more widely in the oil fields at home or abroad, for their superior performance in both oil volume increase and energy-saving implementation. But they also brought a series of questions, including:heavier current harmonic in power system side, low power factor and unreasonably dealing with feedback energy from motor regenerating electricity, and so on. In response to these questions in this paper, and in accordance with the feature of many pumping units concentrated neighbourly, we research and develop a pumping unit variable frequency group control system based on power-fed DC bus. The system not only can increase production and save energy disipation greatly, but also significantly reduce the cost to improve the performance-cost-ratio.This system uses common DC bus power supply technology, which links many inverter terminals, and high performance DSP TMS320LF2407A as control core. With the application of common DC bus power supply technology, the original AC-DC-AC inverter main circuit is separated into both AC-DC and DC-AC part, and many terminals use the same one AC-DC part to supply DC power. In this paper, the configurations of the rectifier and filter and inverter terminals are researched and analyzed, and both a DC relay control circuit and a new self-start scheme for the special switching power supply are proposed. All of these such as the DSP-based control system, isolated drive unit, detection and protection unit are developed in hardware and software design.The system links the many pumping units together through the DC bus, can take greater advantage of the group, circulate and share the energy regenerated, reduce harmonic pollution and the transformer capacity, improve the power factor, and can prevent electricity theft. Rusults from experiment and the field test has shown that the system can improve the pumping performance compared with the original variable frequency control device, save energy, increase the production of crude oil, and perform all the advantages above. The correctness and feasibility of the system scheme have been comfiemed.