Multi-motor-driving frequency-converting energy-saving device based on common DC bus and pumping unit

Abstract

The invention provides a multi-motor-driving frequency-converting energy-saving device based on a common DC bus and a pumping unit. The multi-motor-driving frequency-converting energy-saving device based on the common DC bus includes a power grid, a transformer, an integrated PWM rectifying device, the common DC bus, more than one inverter device and more than one motor being driven. A three-phase AC current output by the power grid is connected to the input terminal of the transformer; the output terminal of the transformer is connected to the input terminal of the integrated PWM rectifying device; the output terminal of the integrated PWM rectifying device is connected to the input terminal of the common DC bus; the output terminal of the common DC bus is connected to the input terminals of the more than one inverter device; and the output terminal of each inverter device is connected to the input terminal of one motor only. By using the multi-motor-driving frequency-converting energy-saving device based on the common DC bus, an energy regeneration problem of the motor caused by large starting torque, light operation load, high transformer configuration capacity and upstream-downstream unbalance of a conventional pumping unit is solved; the purpose of saving energy is realized; and meanwhile, power factors are increased, reliability of the system is improved and the cost of the system is reduced.

Description

technical field [0001] The invention relates to a frequency conversion energy-saving device, in particular to a multi-machine drive frequency conversion energy-saving device and an oil pumping unit based on a common DC bus. Background technique [0002] Beam pumping unit, also known as kowtowing unit, belongs to a kind of oil pumping equipment widely used in the field of oil field exploitation. At present, the pumping unit has problems such as low operating efficiency, low power factor, and large waste of electric energy. For example, the power consumption of the pumping unit accounts for about 40% of the total electricity consumption of the oil field, and its average operating efficiency is only about 25%. Therefore, how to effectively improve the operating efficiency of the pumping unit and reduce the power consumption of the pumping unit belongs to the key research direction of the petroleum industry, which directly affects the overall energy-saving effect of the petroleu...

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Problems solved by technology

[0006] The above method mainly has the following problems: (1) The diode rectifier bridge used by the two-quadrant inverter will cause serious harmonic pollution to the power grid, which reduces the power factor; (2) The feedback energy is directly consumed by the braking energy-dissipating resistor, wasting (3) Each pumping unit needs to be equipped with a transformer and a frequency converter, and each frequency converter has a rectification link. For the occasions where multiple pumping units are close to each other, system resources are wasted and increased system cost

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