Abstract:
The penetration of renewable energy resources in power systems is steadily increasing,
leading to a transition from traditional centralized power systems to
decentralized architectures incorporating microgrids. In microgrids, maintaining
voltage and frequency stability is particularly challenging during off-grid operation,
commonly referred to as islanded mode. To address this challenge, gridforming
inverters—inverters equipped with advanced control strategies that emulate
grid characteristics—are required. This paper presents the design and laboratory
prototyping of a grid-forming inverter capable of regulating voltage and
frequency in an islanded microgrid. The proposed solution is achieved through
a comprehensive control architecture consisting of outer-loop active and reactive
power droop controllers and an inner-loop voltage regulation scheme. The system
has been modeled and validated through extensive computer simulations. The
system’s dynamic performance, stability, and disturbance ride-through capability
are evaluated under various operating conditions, including load variations, secondary
control operation, and fault scenarios. The simulation results demonstrate
that the proposed grid-forming inverter can significantly enhance the stability and
reliability of renewable energy-based microgrids. A hardware prototype has been
developed using a microcontroller, isolated sensing circuits, an intelligent power
module, and an LC output filter. The laboratory prototyping procedure is presented,
followed by preliminary experimental results required to validate the signal
processing and pulse width modulation of the grid-forming inverter.
