Innovative Type II Fuzzy-Based Voltage-Frequency Controller for Isolated Microgrid Considering Load Shedding and Uncertainties

Isolated power systems face significant challenges in maintaining stable voltage and frequency, particularly under conditions of high variability and uncertainty in power supply and demand. Existing control methods, such as Type I fuzzy logic and P/F and Q/V droop control, often struggle with precision and response speed, leading to issues such as frequency deviation and voltage instability. To address these challenges, this paper proposes a novel, fast voltage-frequency control (VFC) method specifically designed for isolated power systems. The proposed VFC method leverages battery charging control and consists of two main components: a load shedding unit and an interval type II fuzzy logic system. The load shedding unit plays a critical role in maintaining system stability by strategically disconnecting a portion of flexible loads involved in a demand response program (DRP) for brief periods when system parameters approach critical thresholds. This preemptive approach helps prevent destabilizing fluctuations and maintains operational integrity. In parallel, the interval type II fuzzy logic system significantly enhances the precision of voltage and frequency stabilization, especially in the face of uncertain and dynamic conditions. The control mechanism employs a roulette wheel selection process to choose scenarios based on probability density functions (PDFs), which are then optimized using the modified dynamic parameter bald eagle algorithm (MDP-BES). This ensures robust performance across a wide range of scenarios. Comprehensive simulations were conducted across 20 scenarios in three sections to validate the effectiveness of the proposed method. Comparative analysis with Type I fuzzy logic control and traditional P/F and Q/V droop control methods demonstrated that the new VFC approach offers superior performance. Notably, it achieves higher accuracy and faster response times, with minimal voltage and frequency ripple during stable system operation. Additionally, the simulations revealed that scheduled load shedding within the system leads to a 15% reduction in frequency deviation and a 10% reduction in voltage deviation, highlighting the significant improvements over existing control strategies.