Voltage Control for dc Microgrids Using an Adaptative Fuzzy Controller
DC microgrid, Fuzzy inference, PI compensator, resonant proportional compensator, DC-AC converter.
The growth of renewable energy sources led to the rise of microgrids and, therefore, it is necessary to study and develop techniques that make them more efficient and stable. This work makes the study of a DC microgrid, composed of a photovoltaic generating unit, a DC-DC converter of the typeBoost, a DC bus connectedto the load and the bidirectional DC-AC converter responsible for making the interface with the concessionaire network. The DC-DC converter is responsible for tracking the maximum power of the photovoltaic panels while the bidirectional DC-AC converter has two functions: to keep the DC bus voltage constant and to inject/extract power from the grid. The control of the bidirectional converter consists of two loops: an internal one that controls the AC current and an external one responsible for controlling the DC bus voltage. The internal mesh uses a Resonant Proportional controller suitable for tracking sinusoidal current reference. The Intelligent Controller of the bus voltage is composed of a Proportional Integral compensator and a Fuzzy controller and are used together to reduce the transients caused by disturbances. The control signal of the PI compensatorin steady state is stored and processed by the Fuzzy controller, and from then on the microgrid adapts around this point of operation. The Fuzzy controller is able to control the microgrid more quickly and efficiently, mitigating the overrun and transitory time. Finally, the results of the microgrid control are presented from two simulation scenarios, highlighting the transient in each instant that the system disturbances occur,demonstrating the effectiveness of the proposed controller compared to the conventional PI compensator, most used in the literature.