Optimal control approaches of pumping stations to achieve energy efficiency and load shifting

Load shifting (LS) is a main task of demand side management (DSM). It has been treated as a kind of operation efficiency improvement in the POET (performance, operation, equipment and technology) framework and has been formulated as an optimal control problem. In literature, the number of pump switches and the accumulative operation time of individual pumps are barely considered in the operation optimization of pump stations. In this paper, we integrate the two issues into the general optimal control (GOC) problem of pumping stations to form an optimal control problem with consideration of pump switches (OCPS) and an optimal control problem with consideration of accumulative operating time (OCOT), respectively. Particle swarm optimization (PSO) algorithm is employed to solve the newly formulated problems. An intake pump station is taken as a case study. GOC, OCPS, OCOT and a hybrid of OCPS and OCOT (OCPS + OCOT) are applied to the station for simulation study. The results show that the optimal control approaches have the ability to achieve both energy efficiency and LS. Nearly 30% energy cost savings can be obtained by the optimal control approaches. The savings are mostly generated by shifting the operation status of the pumps according to time, specifically, time-of-use (TOU) tariff. Compared with GOC, the newly proposed approaches are more feasible for field applications.