Speed factors computed for pumping schedules in Water Distribution Networks: DDA versus PDA formulations

Remus Alexandru Mădulărea,Petre-Ovidiu Ciuc,Andrei-Mugur Georgescu,Sanda-Carmen Georgescu,M.C Balan,F Bode,C Croitoru,C Georgescu,A Georgescu,A Dogeanu,I Nastase,M Sandu

doi:10.1051/e3sconf/20198506002

Abstract

This paper focuses on a methodology allowing to derive the pumping schedule in Water Distribution Networks (WDN), upon a time dependent water demand. The selected test case is a previously studied WDN. Two pumping algorithms give different pumping rules. By solving the nonlinear system of equations, consisting of energy balance equations, mass balance equations and pumping rules, one gets the pumps speed factors. Solutions attached to the Pressure Driven Analysis (PDA) correspond to energy and cost savings, with respect to the solutions given by the Demand Driven Analysis (DDA). The methodology described in this paper is simple and rapid, but the iterative numerical method used to solve the system of equations is highly dependent on the starting guess.

Highlights

Pumping schedules attached to variable speed driven pumps in Water Distribution Networks (WDN) are a major concern for water companies, because appropriate/ personalized schedules allow reducing significantly the overall energy consumption [1, 2].Hydraulic analysis of WDNs can be performed using either specialised software (e.g. EPANET [3]; Bentley WaterGEMS; WDNetXL [4]; WaterNetGen [5] etc), or individually developed codes.With respect to nodal demands [8], the hydraulic analysis can be mainly performed as Demand Driven Analysis − DDA, or as Pressure Driven Analysis − PDA
The selected test case is a simple WDN fed by variable speed driven pumps, previously studied [12]
We present in table 3 the computed results for the PDA formulation, for cq(t) = 1.4 at time t = 13, for both classical and improved algorithms

Summary

Introduction

Pumping schedules attached to variable speed driven pumps in Water Distribution Networks (WDN) are a major concern for water companies, because appropriate/ personalized schedules allow reducing significantly the overall energy consumption [1, 2]. Among the above listed specialised software, only EPANET lacks the PDA formulation, but it incorporates emitters, which allow modelling pressure-dependent outflows at the consumers [11]. Speed factor values can be inserted into the model as fixed values over time, or through time dependent speed patterns [3] issued from computations performed outside the current software [1,12], or through rule-based controls [3], e.g. where pump's speed factor is adjusted in imposed steps upon the pressure level available at a certain node [2, 13]. We present a methodology to derive the pumping schedule in WDNs (to compute pumps speed factors), for both formulations: DDA and PDA. DDA results are discussed with respect to similar results obtained by Georgescu [12], using another DDA-based methodology

Speed factors computing method

L g 2 D 5

Results and discussions

Conclusions