A Novel Cross Iteration Method for Dynamic Energy Flow Calculation of the Hot-water Heating Network in the Integrated Energy System

The state information of district heating network (DHN) is significant to the secure operation and control of the integrated energy system. This paper focuses on the dynamic energy flow calculation method of the hot-water heating network under variable flow rate conditions, i.e. under the quantity regulation mode. First of all, known inputs, desired outputs and mathematical formulation of the energy flow calculation model are clarified. For the partial differential equation describing the temperature dynamics in each pipe, we apply the finite difference method to convert it into a group of algebraic equations for standardized solution. After that, a cross iteration method is proposed to solve the high-dimensional nonlinear model, where the global mass flow rate distribution and the temperatures of return water at each load are alternately updated until both converge to their acceptable precision levels. One nice feature of our method is that the temperatures of return water at each load do not need to be known inputs. Instead, the dynamic response of them can be fully captured, which is crucial for identifying the thermal conditions at each load. Test results of a DHN in the Barry Island demonstrate the validity and effectiveness of our method.