Submerged Pump VFD with DC Bus Storage
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Solution Overview
Problem
Pumping installations for hydrocarbons face disruptions due to electrical network failures, leading to backspin and significant production losses, as existing solutions are either costly or ineffective for asynchronous induction motors.
Innovation Solution
Incorporating a reversible DC-DC converter connected to a DC bus within a variable frequency drive system, which utilizes an electricity storage element, such as batteries or supercapacitors, to ensure uninterrupted power supply and prevent backspin by drawing energy from the storage element during network disruptions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a battery-powered system is used to prevent backspin during power failures, then reliability is improved, but device complexity and cost increase
Solution Approach 1:
The patent combines the battery power supply system with the existing variable frequency drive (VFD) control system. The battery is integrated into the DC bus of the VFD, allowing seamless switching between grid power and battery power without requiring separate control systems. This merging approach maintains reliability while minimizing additional complexity.
Solution Approach 2:
The DC bus serves as an intermediary energy storage element between the grid power source and the motor load. During normal operation, the DC bus is charged from the grid through the rectifier. During power failures, the DC bus capacitance and the connected battery provide the necessary energy to prevent backspin, acting as a mediator that smooths power transitions.
2Loss of energy
If energy recovery from rotating parts is implemented, then energy efficiency is improved, but the solution is only effective under specific mechanical conditions
Solution Approach 1:
The patent converts the harmful backspin phenomenon into a beneficial energy recovery opportunity. When the motor acts as a generator during deceleration or reverse rotation, the generated electrical energy is captured by the rectifier and stored in the DC bus and battery, transforming what was previously wasted energy into a useful resource that extends system autonomy during power failures.
Solution Approach 2:
The system dynamically changes operational parameters to enable energy recovery. The control system adjusts the motor's operating mode from motor mode to generator mode based on rotational speed and power availability, allowing the system to recover energy across a range of operating conditions rather than requiring specific mechanical conditions.
3Duration of action of stationary object
If rapid switching between power sources is implemented, then continuity of operation is improved, but switching complexity increases
Solution Approach 1:
The battery and DC bus are pre-charged during normal grid operation before power failures occur. This preliminary energy storage ensures that when the grid fails, power continuity is immediately maintained without requiring complex real-time switching decisions. The system is prepared in advance, eliminating the need for complex switching control during critical moments.
Solution Approach 2:
The patent maintains continuous power supply to the motor by keeping the DC bus continuously charged from the grid during normal operation. The large capacitance of the DC bus and the connected battery create an energy buffer that ensures uninterrupted power delivery to the inverter and motor, maintaining continuous useful action without interruption or complex switching.
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 solution provides reliable and cost-effective continuous operation of pumping installations by optimizing energy use and minimizing losses due to network disruptions, ensuring the pumping operation continues at optimized speeds with available energy, even during power supply instability.
Implementation Method 1
the DC bus having a capacitor C connected thereto
Implementation Method 2
a reversible DC-DC converter (6) connected to said DC bus (11)
Implementation Method 3
a rectifier (4) connected to said network (A) and arranged for supplying said DC bus (11)
Implementation Method 4
an inverter (3) connected to said motor (M) and powered by said DC bus (11)
Data Source
AI summary
The present invention concerns an installation for pumping hydrocarbons, including a pump submerged in a well and a motor for driving the pump, said motor being linked to a variable frequency drive powered during normal operation by an external network, the drive including a rectifier supplying a DC bus, an inverter supplied by the DC bus and linked to the motor, and a controller, said installation wherein it further includes an electricity storage element linked by a reversible DC-DC converter to the DC bus, the installation being arranged to ensure the variable frequency drive is supplied by the storage element in case of an interruption to the supply via the external network.