Real-Time Digital Simulation (RTDS) is a powerful tool in modeling and analyzing electrical and drive systems because it provides an efficient and accurate process. There are several hardware devices for this type of simulation; however, their high costs have led to the increasing use of more affordable and reconfigurable technologies. In this context, many logic blocks and storage elements make the Field Programmable Gate Array (FPGA) an ideal device to perform RTDS. This work proposes a technique to embed a real-time digital simulator in an FPGA through Hardware Description Language (HDL) since it provides liberty in the architecture choice and no dependency on commercial ready-made hardware–software packages. The approach proposed focuses on system design developing with expression tree graph, synthesizing and verifying, prioritizing the performance and design accuracy concerning area and power consumption. Thus, the result acquisition occurs at a time step considered in real-time. A simulation of a direct current (DC) motor speed control has been incorporated into this work as an example of application, which includes the embedding and simulation of the electric machine and its drive system. Performance tests have shown that the developed simulator is real-time and makes possible realistic analysis of the interaction between the plant and its control. In addition, an idea of the hardware requirement for real-time simulation is proposed based on the number of mathematical operations.

Photovoltaic generation does not have the capacity to compensate imbalances between generation and load demand, which can occur in islanded operation of microgrids and cause voltage and frequency deviations. Thus, battery energy storage systems are inserted to support microgrid regulation, what constitutes the hybrid generation units. In these units, grid interface inverter is driven through a grid-forming droop control, as long as photovoltaic and battery DCDC converters are controlled to promote power balance between generation and load demand. When there is only one hybrid unit in the microgrid, battery charging limit and maximum stateof- charge must also be taken into consideration since supplying of imbalances cannot be shared; and if battery experiences one of these conditions, photovoltaic curtailment is conducted. This paper proposes to test a hybrid unit supplying variable load in islanded mode to evaluate the effectiveness of the grid forming droop control. Through accurate simulations, efficacy of this control strategy is validated for different load, PV generation, and battery conditions.