Centrifugal Pump Head Control for Stable Partial-Load Flow
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Solution Overview
Problem
Existing methods for controlling centrifugal pumps in hydraulic systems, such as heating pumps, face challenges in dynamically adjusting the amplification factor to prevent oscillations and ensure optimal energy efficiency, particularly in partial load conditions, where the feedback between delivery head and volume flow can lead to inefficiencies or undersupply.
Innovation Solution
A method that dynamically calculates the amplification factor based on the current operating point of the centrifugal pump and the state of the hydraulic system, using a target point to determine the ideal gain factor, which changes cyclically to maintain energy-optimal operation by adjusting the target delivery head and considering different states of the system, such as full load and partial load.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a fixed amplification factor is used in the feedforward control, then the control rule is simple, but the system oscillates or undersupplies consumers in partial load conditions
Solution Approach 1:
The amplification factor is changed from a fixed value to a dynamic value that changes with the operating point. The control system continuously adapts the amplification factor based on the current volume flow and head conditions, allowing the system to maintain stability across varying load conditions rather than using a single fixed parameter
Solution Approach 2:
The amplification factor is adjusted as a variable parameter based on the operating state. By calculating the amplification factor from the current operating point and comparing it with the previous value, the system dynamically modifies this critical parameter to prevent oscillations while maintaining responsiveness
2Speed
If a high amplification factor is used, then the delivery head reacts quickly to volume flow changes, but the hydraulic system oscillates
Solution Approach 1:
The amplification factor dynamically adapts to the operating conditions, being higher when needed for quick response and lower when approaching stability limits. This prevents the system from oscillating while maintaining fast response capability across different operating ranges
Solution Approach 2:
The system uses feedback from the current operating point (volume flow and head) to continuously adjust the amplification factor. This feedback mechanism ensures that the amplification factor remains within stable ranges while still providing quick response to legitimate changes in system conditions
3Reliability
If a low amplification factor is used, then the system is stable, but the consumers are undersupplied or energy efficiency is poor
Solution Approach 1:
The amplification factor is adjusted upward when the system requires faster response to meet consumer demands. By dynamically increasing this parameter based on operating conditions, the system maintains both stability and energy efficiency rather than being constrained by a low fixed value
4Reliability
If the pump is oversized for the hydraulic system, then the pump can meet peak demands, but it operates inefficiently in partial load conditions
Solution Approach 1:
The control system dynamically adjusts the delivery head based on the current operating point and system state. This allows the oversized pump to adapt its performance to match actual demand levels, operating efficiently across the full range from peak to partial load conditions rather than being stuck at a fixed inefficient operating point
Data Source
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Figure 3
Figure 4
AI summary
The invention relates to a method for operating an electric-motor-driven centrifugal pump (3) in a hydraulic system (4) having at least one self-controlled load, wherein a gradient (dQakt/dt) of the volumetric flow rate (Q akt ) of the centrifugal pump (3) is determined and the current setpoint delivery head (H _soll ) of the centrifugal pump (3) is calculated from a mathematical operation on the gradient (dQakt/dt) weighted with a gain factor (K) and the last specified setpoint delivery head (H soll,alt ). The operation describes a positive feeback between the setpoint delivery head (Hsoll) and the volumetric flow rate (Qakt). The gain factor (K) is determined from a calculation instruction, which is modified dynamically during the operation of the centrifugal pump (3) with consideration of the current operating point of the centrifugal pump (3) and with consideration of a current and/or at least one past state of the hydraulic system (4).