Comparison of methods for controllers design of single phase inverter operating in island mode in a microgrid: Review

In recent years, new strategies of electric power generation are being developed and these are based on distributed generation systems (DG). With this new strategy of electric power generation based on renewable sources, there is a need to implement interfaces that allow the connection of these sources to the grid, as well as feed loads directly when operating in island mode or disconnected from the grid. Such interfaces are known as microgrids and the energy conversion systems that integrate them are very important. Therefore, the design of these units of energy conversion is a priority; therefore in this work we present the comparison of three methods of controllers design and the model of a single phase inverter for island mode operation in a microgrid. Particularly, the mathematical model is represented using transfer functions. This model describe the mathematical relationships that enable design in a simple and direct way the controllers of the different control loops that make up the energy conversion system. For the controller design in this operation mode, a conventional direct current method based on frequency method was first developed, from which a proportional-integral PI controller is designed. Second, an approximate method based on direct current to alternating current transformation (dc-ac), that allows the design of a proportional controller add generalized integrator (P+IG). This controller is obtained from the PI controller design in direct current. Third, an exact method is developed, which consists in applying a general methodology based on the frequency analysis. In particular, this work distinguishes the advantages of the second method, considering that its application allows the controllers design in a simple way for the different inverter control loops.