Numerical Study of Constant Pressure Systems with Variable Speed Electric Pumps

Rogger José Andrade-Cedeno,Ciaddy Gina Rodríguez-Borges,José David Barros-Enríquez,Yolanda Eugenia Llosas-Albuerne,Carlos David Amaya-Jaramillo,Jesús Alberto Pérez-Rodríguez

doi:10.3390/en15051918

Rogger José Andrade-Cedeno, Ciaddy Gina Rodríguez-Borges + Show 4 more

Open Access

https://doi.org/10.3390/en15051918

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Abstract

This work focuses on the modeling and simulation of constant pressure systems based on variable speed pumps, with the aim of studying and evaluating their performance from a multidisciplinary approach. Using the physical models of the Simscape library, from MATLAB/Simulink R2019b, two study cases are assembled consisting of: piping system, a hydropneumatic tank, centrifugal pumps with an induction motor, variable speed drives, and a control system. Case one is comprised of one pump at a fixed speed and another at variable speed, and case two with both pumps at variable speed. For the parameterization of the models, data from manufacturers and process requirements are used. The different stages of the control system are integrated and configured; these are constant V/f control, slip compensation, space vector modulation (SVM,) and pressure controller. The dynamic response of the system, power saving, transient current at startup, and harmonic distortion are evaluated. The results showed that both cases kept the pressure constant in the face of variable flow demand and smoothed out the current during startup. Case two saved more energy (between 28 and 49%) but generated more harmonic distortion. In addition, both cases have better performance compared with traditional fixed-speed technologies.

Highlights

There are several studies where scalar control with a constant V/f ratio was simulated for the speed control of an induction motor; for example, in an open loop with voltage and slip compensation to improve the performance in low frequencies [9], and adding a PID controller for automatic regulation in a closed loop to eliminate the speed position error [8,10,11]
Two cases were studied to achieve a constant pressure system in a pumping station consisting of two centrifugal pumps in parallel, powered by electricity, and subjected to variable flow demand
The analysis was numerical in nature with modeling and simulation of systems carried out in MATLAB/Simulink R2019b

Summary

Introduction

Commercial, and residential level, applications with pumps, compressors, fans, and others driven by electric motors represent 53% of total energy consumption, and there are new technologies that have the potential to reduce this electricity demand by between 20 to 30% [1]. In pumping applications with variable flow demand, the implementation of variable-frequency drives adapted to electric motors should be evaluated because of the potential energy savings that can be achieved and improvements in the overall performance of the system [2–5]. In these applications, the scalar control strategy with a constant V/f ratio is the most feasible, mainly because of its simplicity and low-cost implementation [6–8]. For the particular case of centrifugal pumps driven by an induction motor with variable speed requirements, computer simulations have been developed

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