In recent years, the Oil and Gas Industry has greatly improved efforts in evaluating the electrical system involved in operating Electrical Submersible Pumps (ESP). The negative effects that poor power quality has on ESP motors equipped with variable speed drives is generally understood by the industry. However, with a strong focus on optimization and reliability, improvements of the power quality provided to our ESP systems has tremendous potential to enhance the ESP lifecycle. This paper will provide a detailed description of the current mitigation technique involving the conventional designs of PWM sinewave filters. Additionally, this paper will outline multiple Case Studies that have been conducted on several wells with ESPs installed, that demonstrate the success of a new design approach for PWM sinewave filters yielding lower electrical distortion and significantly improved motor performance.
A detailed analysis evaluating problems and premature failures was performed on existing ESP wells equipped with both "6-step" and PWM operation. Computer simulations executed to analyze the new sinewave filter design showed much lower voltage distortion (< 2%) as well as other important improvements in performance included a very low insertion loss (ie. < 3% drop in voltage at full load) and improvement in PF to near unity at the inverter output. To complete the study, sinewave filters were built, tested and installed in several wells. Field data was gathered providing power quality measurements for electrical distortion, current imbalance, motor temperatures, motor vibration and production rates.
The successful sinewave filter design used different tuned frequency parameters than conventional sinewave filters with clear data providing performance improvement. These results showed a substantial reduction in motor temperature leading to confidence in operations regarding the positive effect this would have on lifecycle of downhole equipment. The improvements can be streamlined across other ESP wells in the field leading to improved runtime, decrease in CAPEX & OPEX cost associated with ESPs and other surface equipment eventually leading to a strong cash flow performance for operators.