The application of microgrids in critical infrastructures has grown considerably due to the power supply reliability and resilience, and the island operation possibility of providing independence from the main grid. However, the necessity of intense information exchange between the devices that compose the microgrid to their proper operation, and the communication infrastructure required to realize that, makes the system vulnerable to cybersecurity threats. In this context, the case study presented in this paper raises two important subjects of discussion in the Brazilian electrical sector context, which are microgrids and cybersecurity in critical infrastructures of the electrical sector. Therefore, this paper presents the practical challenges related to these two subjects by reporting the development, implementation, and commissioning of a new microgrid controller, and the solutions found to accelerate the development by reducing costs, mitigating risks, and optimizing the commissioning time.

This work proposes a mixed-integer linear programming model for the operational cost function of lithium-ion batteries that should be applied in a microgrid centralized controller. Such a controller aims to supply loads while optimizing the leveled cost of energy, and for that, the cost function of the battery must compete with the cost functions of other energy resources, such as distribution network, dispatchable generators, and renewable sources. In this paper, in order to consider the battery lifetime degradation, the proposed operational cost model is based on the variation in its state of health (SOH). This variation is determined by experimental data that relate the number of charge and discharge cycles to some of the most important factors that degrade the lifespan of lithium-ion batteries, resulting in a simple empirical model that depends on the battery dispatch power and the current state of charge (SOC). As proof-of-concept, hardware-in-the-loop (HIL) simulations of a real microgrid are performed considering a centralized controller with the proposed battery degradation cost function model. The obtained results demonstrate that the proposed cost model properly maintains the charging/discharging rates and the SOC at adequate levels, avoiding accelerating the battery degradation with use. For the different scenarios analyzed, the battery is only dispatched to avoid excess demand charges and to absorb extra power produced by the non-dispatchable resources, while the daily average SOC ranges from 48.86% to 65.87% and the final SOC converges to a value close to 50%, regardless of the initial SOC considered.

This paper proposes a Virtual State Damping (VSD) plugin to output current controllers of distributed generation (DG) inverters. The VSD is designed to suppress the resonance usually present in LCL-type grid-connected DG systems, providing robustness to the control system against grid impedance uncertainties or variations. Typical active damping techniques apply an equivalence impedance model to design their structures. The proposed VSD has the advantage of not needing to take such analysis into account for its design, i.e., it is not dependent on the LCL filter's physical model. The VSD structure applies the model reference theory, and it does not require additional sensors for its implementation. The paper also presents the VSD design methodology and stability analysis. Real-time domain emulation (RTDE) results and 5kW lab-prototype experimental results demonstrate the effectiveness of the proposed technique.

Grid-tied inverters are being widely used in distributed generation, as in photovoltaic generation. This paper presents the robust design and analysis of a control structure for three-phase grid-tied inverters based on stationary frame. The synchronization with the grid is carried out using a DMSOGI-FLL structure, which allows to estimate DC offset voltage and it increases the system robustness under grid voltage abnormalities. Furthermore, a current reference generator is detailed considering the dc-link voltage regulation and the control of active and reactive power. A proportional resonant (PR) approach with harmonic compensation (HC) is applied for the output inverter current control. Moreover, the proposed structure also includes an active damping technique with capacitor current estimation to improve the system robustness in weak or strong grids. Results under several operating conditions are presented from a numerical analysis and it demonstrates the performance of the proposed control structure.

In recent years, fleet electrification has become a viable alternative for reducing carbon emissions through laws and government incentives around the world. Not only that, such incentives have favored the development of new technologies for the sector that have resulted in the reduction of the manufacturing cost of electric vehicles, which in turn, enabled new business models favoring the evolution of the electromobility sector. However, Brazil has also shown itself to be a market on the rise. However, electromobility in Brazil is still at an early stage of development when compared to other countries. In this sense, this paper sought to present the current state of the Brazilian sector through existing laws, regulations and incentives. In addition, it discusses and proposes alternatives for the development and maturation of the sector. Finally, technical aspects related to the standardization of communication protocols and charger installations are also presented.