Energy Management in a Network of Grid-Connected Microgrids/Nanogrids Using Compromise Programming

A new multi-objective optimization model is proposed for efficient integration of a group of microgrids/nanogrids with local energy storage devices into the power grid. In this model, the individual microgrids/nanogrids can exchange power locally among each other as well as with the external electricity grid. A pricing regime is introduced in which differences in the local and grid buy and sell time-of-use prices of electricity incentivize local inter-microgrid/nanogrid exchanges of power over power exchange with the grid. A novel formulation of a multiple-objective constrained optimization is presented for solving the microgrids/nanogrids energy management problem under the proposed electricity pricing regime. This approach is based on minimization of l(1) or l(2) distances of the microgrids/ nanogrids cost vector to a utopia point in the solution space. Components of the utopia point are defined as the minimum cost achievable by the corresponding microgrid/nanogrid when it always uses the favorable local buy/sell prices. The proposed optimization models are in the form of convex linear/quadratic programs without any binary or integer variables for l(1)/l(2) norms. Results of numerical simulations with on-line rolling horizon optimization of the storage device power flow decisions demonstrate the effectiveness of the proposed methods.