Operation optimization of distributed energy systems considering nonlinear characteristics of multi-energy transport and conversion processes

The various energies in distributed energy system (DES) have different transmission and storage characteristics but are tightly coupled through transport and conversion processes, hindering their accurate and efficient analysis severely. To meet this challenge, this work builds a holistic DES model that fully considers the nonlinearity of energy transport and conversion processes in residential quarters based on the heat current method. A two-layer iterative algorithm is further proposed to realize the efficient optimization calculation, and the operation cost of the DES in the whole day reaches $7873.68 after optimization. The optimization results reveal that the operational states of various devices have established a tight spatiotemporal coupling across different moments and buildings, and the nonlinear characteristics in heat transfer, power transmission, and power-heat conversion processes substantially influence the system's operation. Comparatively, neglecting nonlinear heat transfer constraints results in substantial deviations, with a notable reduction in the fluctuation of heat output from each piece of equipment. The average and maximum relative errors in heat stored within the heat storage device (HS) are 31.9% and 81.8%, respectively. Conversely, overlooking the bus voltage constraint leads to an overestimation of heat stored in HS, with the average relative error in heat stored reaching 49.5%.