A Practical Application of a Sinewave Filter to Resolve ESP Motor Failures

In an effort to address high failure rates in Electrical Submersible Pumps (ESPs), Oil Field operators have been encouraged to use either 6-Step Drives or PWM Drives equipped with sinewave filters. Although both provide improvement over PWM Drives without sinewave filters, premature failure rates in filters and motors are commonplace resulting in extremely costly repairs and even more costly downtime. Little can be done to improve the performance of the 6-Step topology with respect to voltage waveform distortion but significant improvement can be achieved with PWM topology through the application of a uniquely designed sinewave filter.This paper provides a detailed description of the problems associated with 6-Step and PWM Drive operation in ESP applications. Conventional designs of PWM sinewave filters are reviewed and a new design approach is introduced for PWM sinewave filters that lowers voltage and current distortion and provides nearly complete compensation for the motor’s reactive power while minimizing exposure to resonance. Case Studies on successful retrofits of a 200 HP and an 1100 HP ESP drive are discussed.