Common Mode Filter for ESP High-Frequency Current Mitigation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Electrical submersible pumps (ESP) operating with unfiltered Pulse Width Modulation (PWM) Variable Frequency Drives (VFDs) experience reduced run life due to high frequency common mode phenomena, leading to mechanical and electrical failures.
Innovation Solution
The implementation of a Common Mode Filter (CMF) at the surface, connected to an electrical power supply providing a semi-sinusoidal voltage waveform, effectively reduces high voltage high frequency currents that travel downhole, thereby reducing stress on ESP equipment and extending run times.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If VFDs operate without common mode filters, then device complexity is reduced and cost is lowered, but high frequency common mode phenomena cause reduced run life and mechanical failures
Solution Approach 1:
A common mode filter is introduced as an intermediary component between the VFD and the ESP motor. The filter acts as a mediator that blocks high frequency common mode currents from reaching the motor while allowing normal operating frequencies to pass through, thereby extending ESP run life without fundamentally changing the VFD operation
Solution Approach 2:
The harmful high frequency common mode currents are extracted and diverted from the main power circuit through the common mode filter. The filter separates the useful power frequency signals from the harmful high frequency common mode noise, directing only the harmful currents to ground through the filter's capacitive path
2Duration of action of stationary object
If common mode filters are installed to reduce high frequency currents, then mechanical failures are reduced and run life is extended, but device complexity and initial cost increase
Solution Approach 1:
The common mode filter is installed in advance before high frequency currents can cause damage to the ESP motor. The filter proactively prevents cumulative damage from high frequency transients by blocking these currents at the source, extending the operational duration before maintenance or replacement is needed
Solution Approach 2:
The common mode filter uses relatively inexpensive components (capacitors, inductors, resistors) that can be replaced if necessary, protecting the much more expensive ESP motor. The filter components are designed to handle the stress of high frequency currents that would otherwise rapidly degrade the motor
3Ease of operation
If high voltage high frequency currents are allowed to travel downhole, then VFD operation is simpler and more direct, but electrical and mechanical equipment experiences increased stress and failures
Solution Approach 1:
The common mode filter takes the harmful high frequency common mode currents and converts them into a beneficial filtering action. By providing a low impedance path to ground for these high frequency currents through its capacitive elements, the filter transforms what would be damaging transients into controlled current paths that protect the downstream equipment
Solution Approach 2:
The common mode filter serves as an intermediary between the simple VFD output and the sensitive ESP motor. It maintains the simplicity of VFD operation while mediating the harmful effects of high frequency currents, allowing the VFD to operate as designed without directly exposing the motor to damaging electrical stress
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The use of CMFs significantly reduces high frequency induced mechanical failures, increases ESP run times, and enhances the overall reliability of ESP systems by shunting high frequency currents to ground at the surface.
Implementation Method 1
The common mode line to ground filter substantially reduces the high voltage high frequency current that travels downhole over an electrical cable to the ESP equipment. The high voltage high frequency current is shunted to ground the common mode filter at the surface.
Data Source
AI summary
A common mode line-to-ground filter is disclosed which includes but is not limited to a resistor, capacitor and a ground. The common mode line to ground filter is connected on a high side of a step-up transformer. A low side of the step-up transformer is connected to a variable frequency drive that provides a semi-sinusoidal voltage waveform. The common mode line to ground filter generates a filtered sinusoidal waveform from the output of the step-up transformer. The filtered sinusoidal voltage waveform is supplied via an electrical cable to an electrically submersible pump deployed downhole.