Hierarchical Multi-Objective Fuzzy Collaborative Optimization of Integrated Energy System under Off-Design Performance

In order to solve the frequently occurred nonlinear working characteristics problem of the devices in integrated energy system (IES), where this nonlinear problem causes the offset of operation characteristics and design points of those devices, in this paper, the hierarchical multi-objective fuzzy collaborative optimization model of IES under off-design performance is proposed. Firstly, the high-order nonlinear models of devices under off-design performance, including fuel cell (FC), gas turbine (GT), absorption lithium bromide chiller (ABS), etc., are presented considering renewable energy and diversified storage devices, which can more accurately describe the actual working condition of devices. Secondly, according to the needs of different engineering application modes, the lower level collaborative optimization model of energy hub (EH) with economic, eco-friendly, primary energy saving, and renewable energy accommodation rate as optimization objectives is proposed, which can well adapt to and reflect real world energy system. Thirdly, based on the relationship between master and slave dispatch centers, the upper level modeling and optimal scheduling model of IES consisting of coupling power system, natural gas system, and heat system is proposed. Then, a multi-objective fuzzy collaborative optimization model for EH and IES is developed, where continuous differentiable Sigmoid function is taken as the membership function. Finally, simulation results show that the proposed models and optimal dispatch method can effectively solve the frequently occurred non-linear working characteristics problem of the devices in IES. The optimal results are suitable for planning, calculation, operation, dispatch of IES, which can reasonably reflect the operation characteristics of IES

Distributed Dynamic Economic Dispatch of an Isolated AC/DC Hybrid Microgrid Based on a Finite-Step Consensus Algorithm

The AC/DC hybrid microgrid is the main trend of microgrids’ development, and the dynamic economic dispatch is regarded as an important way to ensure the economic and safe operation of a microgrid system. In this paper, a dynamic economic dispatch model of the isolated AC/DC hybrid microgrid is developed with the objective of minimizing the daily operation cost of controllable units. Furthermore, a distributed algorithm based on the finite-step consensus algorithm is proposed, in which the incremental cost of each distributed generation unit is set as a consensus variable, and all units obtain the optimal values by exchanging information only with their neighbors. In addition, the algorithm converges to the optimal solutions in finite steps, and the efficiency is improved significantly. The effectiveness of the proposed model and the algorithm were verified by simulation