Centrifugal Pump Flow Rate Determination via Model-Based Excitation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing methods for determining the delivery flow and delivery height of speed-controlled centrifugal pump units in hydraulic pipeline networks face challenges with noise interference at low excitation amplitudes, leading to reduced accuracy and increased noise in signal determination.
Innovation Solution
A method involving periodic excitation signals applied to the centrifugal pump unit's speed or torque, using a pump-motor model to simulate behavior, calculate model speed, and adjust parameters to reduce noise and improve accuracy, allowing for dynamic compensation of modeling inaccuracies and detection of system changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a large modulation amplitude is used for periodic excitation of the centrifugal pump unit, then the signal-to-noise ratio in the useful signal is improved, but flow noise is generated in the piping network
Solution Approach 1:
A pump-motor model acts as an intermediary between the actual pump system and the measurement system. The model simulates the pump's behavior and allows determination of flow rate and head from the system response without requiring large excitation amplitudes, thus avoiding flow noise while maintaining measurement accuracy
Solution Approach 2:
The patent replaces direct mechanical measurement methods with a computational model-based approach. Instead of relying on large mechanical excitation amplitudes to generate measurable signals, the system uses a mathematical pump-motor model to interpret smaller signals, substituting mechanical measurement with computational analysis
2Object-generated harmful factors
If a low modulation amplitude is used for periodic excitation, then flow noise is reduced, but the noise in the useful signal increases, impairing accuracy
Solution Approach 1:
The pump-motor model serves as a mediator that enables accurate measurement at low excitation amplitudes. By providing a computational framework to interpret the system response, the model allows reliable flow rate determination without the need for large excitation amplitudes that would generate flow noise
Solution Approach 2:
The patent changes the approach from direct signal-based measurement to model-based parameter estimation. By using the pump-motor model to calculate flow rate and head from the system response, the system can operate at low excitation amplitudes where flow noise is minimized while maintaining measurement accuracy through computational analysis
Data Source
Figure 1~2
Figure 3
Figure 4~8
AI summary
The invention relates to a centrifugal pump assembly and a method for determining the flow rate (Q) and/or the delivery head (H) of a speed-controlled centrifugal pump assembly (3, 4) by applying a reference speed (no) or torque of the centrifugal pump assembly (3, 4) with a periodic excitation signal (fA(t)) of a specific excitation frequency (ωA) in order to achieve a modulated target speed (nset).In this process, a model speed (ωmdl) is calculated using a mathematical pump-motor model (9) that simulates the behavior of the centrifugal pump unit (3, 4) within a hydraulic system (1), at least one disturbance signal (TD, PD) is calculated from a deviation of the model speed (ωmdl) from the actual speed (ωreal), at least one correction signal (TD1sin, TD1cos, PD1sin, PD1cos) is determined by integrating the product of the disturbance signal (TD, PD) and a sine or cosine signal with a simple or multiple of the excitation frequency (ωA) over at least one period of the excitation signal (fA(t)), and finally at least one model parameter (Rhyd, J, Lhyd, ct) of the pump-motor model (9) is adjusted as a function of the correction signal (TD1sin, TD1cos, PD1sin, PD1cos). The flow rate (Q) and/or the delivery head (H) are then calculated using the adapted pump-motor model (9).