A New Approach for Steady-State Analysis of a Hybrid ac-dc Microgrid

Abstract

The dc grid became more popular, by emerging the distributed generations (DGs). Despite this popularity, the dc grid is not yet widely used because the majority of loads in a power system are ac, which means the ac grid is still the dominant grid in the power system. Therefore, the concept of a hybrid ac-dc microgrid was emerged because of this contradiction. Hybrid ac-dc microgrid was introduced in order to exploit the benefits of both ac and dc microgrids. However, the combination of both ac and dc microgrids will add more complexity to the network. Because in all studies for hybrid ac-dc microgrid, such as steady-state analysis or dynamic study, two sets of equations should be considered and solved either separately or simultaneously, the solutions that were presented before. These solutions increase the time of simulation and operation. In this paper, a novel procedure for steady-state analysis of a general hybrid ac-dc microgrid is proposed. In this technique, the dc microgrids will be transferred to the ac side by proposing two lemmas and then the whole grid will be analyzed as one ac network. It will be proved that not only the new ac grid has the same power flow result with the initial topology of the ac-dc microgrid, but also the simulation time of the proposed method is less than the other existing methods.