Parallel Pump Characterization for Sensorless Energy Control

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Solution Overview

Problem

Existing multi-pump control systems for water supply networks face challenges in identifying the most energy-efficient subset of pumps to operate, as they rely on pre-known pump characteristics that can change due to manufacturing tolerances and wear, and often lack current flow measurements, leading to inefficient energy consumption.

Innovation Solution

A control system and method that approximates the pump characteristics and power consumption using configuration cycles with varying subsets of pumps, employing second-order polynomials to determine the most energy-efficient subset for a required flow and head, even without current information on pump characteristics or flow measurements.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If pre-known pump characteristics from manufacturer are used for control decisions, then control system operation is simplified, but accuracy deteriorates due to manufacturing tolerances, wear, and fouling causing real characteristics to differ from stored information

Engineering Contradiction:
Improvecontrol system operationVSAvoidpump characteristic accuracy
Core Design Contradiction:
Ease of operationVSMeasurement precision

Solution Approach 1:

The control system performs preliminary characterization of each pump by systematically operating them in different configurations and measuring actual head and power consumption. This preliminary action captures the real pump characteristics including wear and fouling effects, creating an accurate baseline for future control decisions without requiring continuous complex measurements

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The system continuously monitors actual pump performance by measuring head and power consumption during configuration cycles, then feeds this information back to update the pump characteristic database. This feedback mechanism ensures the control system adapts to changing pump conditions over time, maintaining accuracy despite wear and manufacturing variations

Inventive Principle:
Principle #23Feedback

2Measurement precision

If flow sensors are installed to measure current flow accurately, then flow measurement precision is improved, but system cost and complexity increase due to expensive installation and maintenance

Engineering Contradiction:
Improveflow measurement accuracyVSAvoidsensor installation and maintenance
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The system uses head measurement and power consumption data as intermediary parameters to indirectly determine flow characteristics. By measuring these alternative parameters that are easier to obtain and using pump characteristic relationships, the system achieves flow information without requiring direct flow sensors, thus avoiding their associated costs and complexities

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The invention replaces mechanical flow sensors with a computational approach using electrical power measurements and hydraulic head measurements combined with pump characteristic models. This substitution uses more readily available and less expensive measurement types to achieve the same information goal

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

3Measurement precision

If configuration cycles are performed frequently to update pump characteristics, then accuracy of energy-efficient subset identification is improved, but system disturbance and time consumption increase

Engineering Contradiction:
Improvepump characteristic accuracyVSAvoidconfiguration cycle time
Core Design Contradiction:
Measurement precisionVSLoss of time

Solution Approach 1:

The system performs pump characterization configuration cycles periodically rather than continuously or too frequently. This periodic action allows the system to maintain reasonably accurate pump characteristic data while minimizing disruptions to normal water supply operations, finding an optimal balance between accuracy and operational continuity

Inventive Principle:
Principle #19Periodic action

Solution Approach 2:

The system performs a limited number of configuration cycles with a subset of pumps rather than all pumps in all possible combinations. This partial action approach gathers sufficient information to identify energy-efficient operating subsets without requiring exhaustive characterization, thus reducing time loss while maintaining adequate accuracy

Inventive Principle:
Principle #16Partial or excessive action

Data Source

PatentEP3428452B1Measurement of a characteristic curve of one pump in a set of pumps operating in parallel
Publication Date: 2022.08.24 GRUNDFOS HLDG
  • EP3428452B1 patent drawingFigure 1
  • EP3428452B1 patent drawingFigure 2~3
  • EP3428452B1 patent drawingFigure 4~5

AI summary

The present disclosure provides a multi-pump control system (5) comprising a control module (7), a processing module (9), a communication interface (11), and a storage module (13), wherein the control module (7) is configured to run n different subsets of i pumps of a multi-pump system (3) comprising N pumps during n different configuration cycles at a speed ωj, wherein N ≥ 2, 2 ≤ n ≤ 2N-1 and 1 ≤ i ≤ N, wherein each configuration cycle j∈{1,...,n} is associated with a subset j∈{1,...,n} and a speed ωj, wherein the communication interface (11) is configured to receive signals indicative of operational parameters from each subset j during the associated configuration cycle j, wherein the processing module (9) is configured to determine an approximated pump characteristic Δp=f(q, ωj) based on the received signals for each subset j and under the assumption that the i pumps of each subset j share the same part q/i of a reference flow q, wherein the storage module (13) is configured to store the approximated pump characteristic Δp=f(q, ωj) or parameters indicative thereof.