Optimal Flow Research With Regulation Of Meshed Pipeline In Meshed District Heating Network With Multiple Heat Sources

With the development of society,the scale of the district heating(DH)system is getting larger and larger,and the meshed DH system with multiple heat sources has become the development trend of the DH system.However,the current meshed DH network with multiple heat sources only adjusts the pump or valve at the heat source or heat substation,and ignores the loop adjustment,which limits the adjustment capacity of the DH network.In the end,the energy consumption of the transmission and distribution of the system is wasted.This article is based on the primary network flow adjustment of the heating system.The mesh valve adjustment and the mesh water pump adjustment are used to improve the operating status of the heating system.The total power of the water pump in the primary network is used as the objective function.The supply water amount of each heat source,the opening degree of each valve,the the rotation speed of each pump and the selection of the mesh adjustment position are selected as the control variable,to perform the hydraulic optimization of the DH network.Firstly,the steady-state hydraulic model of the meshed DH system with multiple heat sources is established,which is the basis of hydraulic optimization research,and two major methods named "flow method" and "hydraulic method" for hydraulic calculation of DH network are summarized.At the same time,the basic loop analysis method in the "flow method" and the node equation method in the "hydraulic method" were used to solve the hydraulic model of the actual DH network.The result shows that the best solution method for hydraulic model of meshed DH network with multiple heat sourcrs is basic loop analysis method.Subsequently,in the research on the hydraulic optimization of the DH network,the linear search method was used to optimize the positions of meshed pipeline regulation,and at the same time,the particle swarm optimization algorithm(PSO)and genetic algorithm(GA)were applied to optimize the water supply amount of each heat source,the valve opening degree and the rotation speed of each pump.Which combining linear search method with PSO and GA to improve the convergence of the algorithm.Finally,the hydraulic optimization results of the DH network under the two regulation schemes of the meshed pipeline are compared and analyzed through the example of the DH network.The result shows that considering the two regulation schemes of meshed pipeline,the energy consumption of the pump in the network has been reduced by more than 20%,which verified the huge energy saving potential of the meshed DH network with multiple heat sources.