Variable Frequency Drive Control System for Electric Submersible Pumps
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Solution Overview
Problem
Variable frequency drives (VFDs) used in electric submersible pumps for oil and gas applications often fail to operate efficiently due to external factors, leading to suboptimal power delivery and increased current consumption, which can be addressed by modifying the information communicated to the main VFD and utilizing a secondary VFD to deliver correction signals.
Innovation Solution
A control system that includes a main drive and a secondary drive, where sensors monitor operational values and determine correction information to implement desired operating conditions, allowing the system to optimize the electric motor's operation along the Maximum Torque per Ampere (MTPA) curve by adjusting voltage, current, or rotor position.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a main VFD is used to drive the electric motor, then the motor can operate, but the system efficiency is reduced due to external factors preventing maximum power delivery
Solution Approach 1:
A secondary VFD is introduced as an intermediary device between the main VFD and the electric motor. The secondary VFD receives correction information from sensors and processes it to generate correction signals that are injected into the motor terminals, thereby mediating the power delivery to overcome external factors and improve system efficiency
Solution Approach 2:
Sensors are implemented to monitor operational values of the electric motor and transmit this information to the control system. The control system processes this feedback and generates correction information that is sent to the secondary VFD, creating a closed-loop feedback mechanism that continuously optimizes motor operation
2Loss of energy
If correction signals are injected through a secondary VFD, then motor efficiency is improved, but the device complexity increases
Solution Approach 1:
The secondary VFD is electrically connected in series with the main VFD output, merging two drive systems into a unified control architecture. This allows the secondary VFD to inject correction signals into the same power pathway without requiring separate parallel circuits, thereby reducing overall system complexity while maintaining efficiency improvements
Solution Approach 2:
The secondary VFD acts as an intermediary that processes correction information and injects minimal correction signals into the power pathway. By handling only the correction component rather than the entire power control function, the secondary VFD reduces the complexity burden compared to redesigning the entire main VFD system
Data Source
AI summary
A system including a control system is provided. The control system includes a main drive that receives power from a power source and outputs a variable frequency and a variable amplitude AC voltage. The control system also includes a controller to interface with the main drive and an electric machine. The controller receives one or more electrical signals associated with an operating condition of the electric machine from one or more sensors disposed between the electric machine and the main drive. The controller determines correction information based on the received electrical signals and based on a desired operating condition of the electric machine. The controller transmits the correction information to the main drive. The correction information corresponds to a rotor position of the electric machine or operating commands configured to implement the desired operating condition of the electric machine.