Performance evaluation of a transformerless multiphase electric submersible pump system

Abstract

Using of low-voltage variable-frequency drive followed by a step-up transformer is the most preferable way to feed an electrical submersible pump motor. The existence of long feeder between the motor and drive systems usually causes over-voltage problems because of the travelling wave phenomenon, which makes the employment of filter networks on the motor or inverter terminals mandatory. The so-called boost-inverter inherently can solve this problem with filter-less operation as it offers a direct sinusoidal output voltage. As boost inverters have voltage boosting capability, it can provide a transformer-less operation as well. This study investigates the performance of a five-phase modular winding induction machine fed from a boost-inverter through a long feeder. A simulation study using a 1000 Hp system and experimental investigation on a 1 Hp prototype machine are used to support the presented approach.

Keywords

• pumps
• variable speed drives
• overvoltage
• invertors
• asynchronous machines
• machine windings
• transformerless multiphase electric submersible pump system
• low-voltage variable-frequency drive
• step-up transformer
• overvoltage problems
• travelling wave phenomenon
• filter networks
• boost-inverter
• filter-less operation
• sinusoidal output voltage
• voltage boosting capability
• five-phase modular winding induction machine