Modelling and control of district heating networks with reduced pump utilisation

Abstract

Abstract District heating systems (DHS) provide thermal energy to a range of consumers. Hence, an adequate sizing of the key elements involved in the energy supply system and their management are critical. Pumps and valves are essential components of a DHS as they ensure hydraulic operating conditions are met for the energy distribution process. To achieve this, a hydraulic system is typically controlled by defining a differential pressure set‐point at a critical location in the network. However, a good understanding of the dynamic behaviour of the hydraulic system during the diverse operating conditions is required for its efficient control and to maximise its performance. This paper presents a control strategy based on suitable dynamic models of the hydraulic system. These non‐linear models enable the simulation of the behaviour of mass flow rate, pressure drops in pipes, power consumption of the pump and the heat delivery to meet the thermal loads. Control system design is carried out in MATLAB, and the designed controller is verified with Apros—a commercial process simulation software. It is shown that the hydraulic behaviour of a DHS is well described by the dynamic models presented. In addition, the designed control scheme reduces the electricity consumption of pumps compared with a conventional mass flow rate controller based on a look‐up table and a differential pressure valve.