Accelerating virtual rotor control with integral feedback loop in low-inertia microgrids

Abstract

This research introduces a new concept called Accelerating Virtual Rotor Control (AVRC) to address the challenges of low inertia and damping in a multi-source microgrid with combined Load Frequency Control (LFC) and Automatic Voltage Regulator (AVR). While existing controllers have shown effectiveness, they often suffer from complexity and impracticality in real-world applications, the AVRC offers simplicity and effectiveness; therefore, it has been applied to low- inertia microgrids (MGs) by incorporating Superconducting Magnetic Energy Storage (SMES) device for improved microgrid response. Nevertheless, the Phase-Locked Loop (PLL) usually suffers from the low bandwidth, which affects the system response, and stability in some cases. Consequently, a Proportional-Integral (PI) controller has been integrated into the VRC system, where the effects of the measurement delays in the PLL are mitigated. In terms of SMES response, PI controller can create a static error resulting an over charging/discharging issue. To overcome this effect, an integral feedback loop is added into the AVRC, resulting in a comprehensive control strategy known as PI-AVRC/I. Additionally, to achieve a better optimization performance for the parameters of the proposed control strategy, a modification has been introduced to the Zebra Optimization Algorithm (MZOA) using Levy Flight motion to enhance its global search capability and avoid local optima. A Hardware-In-the-Loop is demonstrated using a Real-Time Digital Simulator (RTDS) with the aid of RSCAD software in order to evaluate the efficacy of the proposed control strategy under different scenarios such as step load perturbations with/without high Renewable Energy Sources (RESs) integration, random domestic loads fluctuation, and Communication Time Delay (CTD). The results affirm the robustness of the proposed control strategy in maintaining frequency and voltage deviation withing favorable limits, especially with high RESs penetration.

Keywords

• Accelerating virtual rotor
• Load frequency control
• Automatic voltage regulator
• Superconducting magnetic energy storage
• Modified zebra optimizer
• Renewable energy