Development of a Hybrid Microgrid for Power Generation Through the Interconnection of Sources with a Push-Pull Converter

Abstract

This paper proposes a hybrid microgrid for power generation in isolated/remote locations. Two local primary sources are considered, one in direct current (DC) and other in alternating current (AC). The first being a photovoltaic source (PV) and the second a hydro turbine employing a self-excited induction generator (SEIG). The system also employs a distribution static synchronous compensator (DSTATCOM) and battery energy storage system (BESS) for storage of the surplus energy not consumed by the loads. The management of the energy generated by the considered sources and BESS is performed out through the insulated bidirectional Push-Pull converter. There are two DC busbar in the proposed microgrid, being the primary and secondary of the Push-Pull converter, since the Push-Pull converter is a bidirectional, insulated DC-DC converter, and can operate both in step-up and/or step-down mode. In this paper, both modes are presented. Most specifically, when Push-Pull converter operating in step-up mode, the energy by the PV or BESS is injected in the DC busbar for supply the specifically demand for energy of loads connected in AC busbar. In step-down mode, the energy disposed in the DC busbar of the DSTATCOM (secondary of the Push-Pull converter) is injecting in to the primary DC busbar, where the Buck/Boost converter operate in Buck mode for charge the BESS in nominal current. The energy for charging the BESS in step-down mode comes from the surplus generated by SEIG and not consumed by loads. For the proper functioning of the Push-Pull converter in the proposed microgrid, a mathematical modeling of the converter is performed considering the symmetric PWM modulation, from which the controllers are designed. Most specifically, the Buck converter model is considered to represent the behavior of the Push-Pull converter. Finally, simulation results validate the model and the designed controllers.