Multiple Operating Points in Complex Pump Networks

Abstract

Pump networks are pipe networks in which most head changes are produced by pumps. When nonmonotoncity exists in one or more pump characteristic curves, possibility of multiple operating points exists. An optimization model for steady state networks of arbitrary topology, complexity, and size is presented. Stationary points of the optimization model define possible operating points. Uniqueness conditions as well as conditions for possible multiple operating points are identified. Operating points can correspond to minimums, maximums, or saddle points of the optimization model objective function. A two pump network example illustrates the different possibilities. It is concluded that the stationary point character defines the relative stability of different steady state operating points.