Single VFD Power Control for Hydraulic Pump Arrays
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current electric motor-powered frac pumps for well servicing require multiple variable frequency drives (VFDs) to control power to each hydraulic pump, increasing cost and complexity, as maximum power is not needed for all applications.
Innovation Solution
A system with a single electric motor and VFD that selectively couples and decouples the VFD to each hydraulic pump using a control system with switches, allowing power to be controlled through a VFD flow path or bypassed for direct motor power, reducing the need for multiple VFDs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple variable frequency drives (VFDs) are used to control power to each hydraulic pump, then power control precision is improved, but device complexity and cost increase
Solution Approach 1:
The patent merges multiple VFD control functions into a single VFD unit that can sequentially control multiple hydraulic pumps. Instead of having one VFD per pump, the system uses one VFD with a control system that switches between pumps, thereby reducing the total number of VFDs while maintaining power control precision for each pump.
Solution Approach 2:
The single VFD is designed to perform multiple functions by sequentially controlling different hydraulic pumps. The control system enables the VFD to switch between pumps based on operational requirements, making the single VFD unit universal for controlling the entire pump array rather than requiring dedicated VFDs for each pump.
2Adaptability or versatility
If multiple variable frequency drives (VFDs) are used to control power to each hydraulic pump, then power control capability is improved, but cost increases
Solution Approach 1:
The patent combines multiple VFD units into a single VFD system that serves all hydraulic pumps. The control system manages the switching between pumps, allowing one VFD to provide power control capability for multiple pumps, thereby reducing the overall cost while maintaining adaptability and versatility in power control.
Solution Approach 2:
Instead of replicating multiple expensive VFD units, the system uses a single VFD that is controlled to replicate the function of multiple VFDs. The control system creates a virtual multiplication of VFD capabilities by sequentially assigning the single VFD to different pumps based on operational needs, eliminating the need to purchase and install multiple identical VFD units.
3Power
If maximum power is always supplied to the electric motor, then power availability is improved, but motor life decreases
Solution Approach 1:
The system dynamically adjusts the power supplied to the electric motor based on the operational requirements of the hydraulic pumps. The control system monitors pump conditions and modulates the VFD output to supply only the necessary power at any given moment, rather than continuously supplying maximum power. This dynamic power adjustment ensures adequate power availability when needed while reducing unnecessary stress on the motor to extend its life.
Solution Approach 2:
The control system incorporates feedback mechanisms that monitor the operational status of hydraulic pumps and adjust the power output from the electric motor accordingly. By receiving feedback on actual pump requirements, the system can optimize motor power delivery to match demand, preventing unnecessary high-power operation that would reduce motor life while ensuring sufficient power is available when pumps require it.
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
This configuration reduces costs and complexity by allowing efficient power control for each pump while minimizing the use of multiple VFDs, extending motor life and optimizing power usage.
Implementation Method 1
a variable frequency drive (VFD) configured to be coupled to the electric motor to control an amplitude of power provided by the electric motor to the plurality of pumps
Data Source
AI summary
A well service pump system supplies high pressure working fluid to a well. The pump system is a linear design which incorporates an electric motor, a variable frequency drive (VFD), a pump drive, closed loop variable flow rate hydraulic pumps, hydraulic ram cylinders, working fluid end cylinders, and a coupling to connect the hydraulic ram cylinders and the working fluid end cylinders. The electric motor powers the hydraulic system which, in turn, provides hydraulic fluid to operate the hydraulic ram cylinders. The VFD is connected to a single one of the hydraulic pumps at a time and applies power to the connected pump, via the pump drive, to drive the connected pump from a cold start to an operating speed. The VFD is connected sequentially, one pump at a time, to each of the hydraulic pumps and disconnected from each pump once the pump reaches the operating speed. Once the pump reaches operating speed, the pump is connected to receive power directly to the electric motor.