ESP Motor Current Balancing for Flat Cable Impedance Mismatch
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The impedance mismatch in flat cables used to supply electrical energy to electric submersible pump (ESP) systems results in unbalanced electric currents, leading to increased electrical losses, torque ripple, and premature component failures.
Innovation Solution
Employing a method of symmetrical components to resolve unbalanced three-phase currents into balanced positive and negative sequence components, using proportional-integral controllers to generate voltage commands that eliminate negative-sequence currents and ensure balanced currents at the motor terminals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If a flat cable is used to supply power to the ESP system, then the cable geometry is thinner and more compact, but the impedance between conductors becomes unbalanced
Solution Approach 1:
The patent applies parameter changes by adjusting the voltage output of the variable speed drive to compensate for the unbalanced impedance in the flat cable. The system measures the actual current in each phase and dynamically adjusts the voltage parameters to achieve balanced current flow, thereby resolving the impedance balance issue while maintaining the compact flat cable geometry
Solution Approach 2:
The patent implements feedback control by continuously monitoring the current in each phase of the ESP motor and using this information to adjust the voltage output of the variable speed drive. This closed-loop feedback mechanism ensures that despite the unbalanced impedance in the flat cable, the currents remaining balanced at the motor terminals
2Device complexity
If unbalanced currents are supplied to the electric motor, then the cable impedance mismatch is tolerated, but electrical losses and torque ripple increase
Solution Approach 1:
The system changes the voltage parameters output by the variable speed drive based on real-time current measurements. By adjusting the voltage magnitude and phase for each conductor, the system compensates for the cable impedance mismatch and eliminates excessive electrical losses while maintaining the simple flat cable configuration
Solution Approach 2:
The patent applies preliminary anti-action by pre-compensating for the known impedance imbalance in the flat cable. The system calculates the required voltage adjustments in advance based on the cable characteristics and applies these corrections before the unbalanced currents can cause excessive electrical losses and torque ripple
3Shape
If unbalanced currents flow through the motor, then the flat cable structure is maintained, but torque ripple and component fatigue increase
Solution Approach 1:
The patent uses feedback control to continuously monitor motor current and adjust the variable speed drive output accordingly. This real-time feedback ensures that balanced currents are supplied to the motor, preventing torque ripple and component fatigue while maintaining the flat cable structure
Solution Approach 2:
The system dynamically changes the voltage parameters supplied to each motor phase to compensate for the flat cable's impedance characteristics. This parameter adjustment ensures balanced current distribution, eliminating torque ripple and preventing shaft and coupling fatigue while preserving the compact flat cable structure
Data Source
AI summary
Processing device-based systems and methods for controlling an electric motor of an electric submersible pump system in a balanced current condition using a variable speed drive despite an impedance imbalance of an electric cable connecting the electric motor to the variable speed drive. The systems and methods can utilize estimated motor shaft angular position and speed values, as well as values of three-phase motor currents measured at an output of an inverter of the variable speed drive as input information. Positive-sequence and negative-sequence current components may be extracted from measured current values and compared to reference values. The system provides an overall voltage command in the abc reference frame to a pulse width modulation controller, which generates an inverter switching pattern that will control the electric motor of the electric submersible pump system in a balanced current condition.