Seven-level medium-voltage frequency converter for electric submersible pump

Abstract

The invention relates to the field of oil-field oil production equipment, in particular to a seven-level medium-voltage frequency converter for an electric submersible pump. According to the technical scheme, the frequency converter consists of an input phase-shifting transformer, an electric control cabinet, a power unit and a CPU (Central Processing Unit) control and display assembly, wherein the input phase-shifting transformer is arranged on the lower part of the control cabinet; the electric control cabinet is arranged in the middle of the control cabinet; the power unit is used for holding an upper layer power unit, a middle layer power unit and a lower layer power unit; each layer is provided with three transverse power units; the output mode of each layer is in serial connection; the CPU control and display assembly consists of a CPU control board and a display box; the CPU control board is arranged inside the electric control cabinet; and the display box is arranged on a front panel of the electric control cabinet. The frequency converter has the advantages that: the automatic management level of the electric submersible pump is raised, failures are reduced, the service life of the electric pump is prolonged, and the operation cost is lowered.

Description

Technical field: [0001] The invention relates to the field of oil production equipment in an oil field, in particular to a seven-level medium-voltage frequency converter for a submersible electric pump. Background technique: [0002] As the energy supply becomes more and more tense, the requirement of energy saving is placed in a more prominent position than before. At present, frequency conversion speed regulation technology has been widely used in various industries as an energy-saving means. However, the general-purpose inverter adopts three-phase six-pulse rectification, and the harmonic current is large, which also brings increasingly serious harmonic pollution to the power grid. [0003] Since the voltage range of the submersible electric pump is 1000V~3000V, it belongs to the medium voltage range. At present, there are two main ways to obtain medium-voltage variable frequency power supply at home and abroad: high-low-high way and medium-voltage three-level way. ...

AI Technical Summary

Problems solved by technology

The high-low-high method adopts two step-up and step-down transformers, which has a complex structure, low operating efficiency, and extremely high input and output harmonics

The DC bus voltage of the medium-voltage three-level method is high, the semiconductor device withstands high voltage, is easy to break, and has low reliability. It also has major disadvantages of input and output harmonics.

[0004] The operating conditions of the submersible electric pump are harsh: the operating voltage is high, the cable is very long (1000 meters to 3000 meters), the distributed capacitance of the cable is very complicated, the temperature around the cable is high, and the insulation is low

A medium-voltage inverter with large output harmonics will cause the superposition of cable harmonic voltage, high harmonic voltage, large harmonic current, and high temperature, which will cause easy breakdown of the cable and affect the service life of the unit

[0005] Due to the huge flaws of each of these two methods, they are becoming less and less suitable for future use

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