Time Optimal Control of Constant Power Loads in DC Microgrids

Constant Power Loads (CPLs) are nonlinear loads which often introduce instabilities to the power system. To improve the startup transient of such systems, time optimal control of CPLs in DC microgrid (DCMG) is presented in this paper. First, simplified dynamical model of the DCMG is derived including the CPL effect. Then the dynamic optimization problem is introduced to drive the system states to the desired values in minimum time while preserving the control and state constraints. Both the time optimal control and states are obtained by solving the problem using Legendre-Gauss-Radau (LGR) direct orthogonal collocation pseudospectral method. Simulations were carried out and results are presented to demonstrate the effectiveness of the proposed concept.