Resilient Controller Design with Exponential Reaching Law for Enhanced Load Frequency Stability in Multi-Area Interconnected Microgrids

TL;DR

The paper tackles load frequency control in multi-area interconnected microgrids with substantial renewable penetration by proposing a decentralized robust global integral terminal sliding mode controller (GITSMC) equipped with an exponential reaching law, enabling finite-time convergence under bounded disturbances. It constructs a detailed area-wise state-space model with integrated PV and WT disturbances and a lumped uncertainty term $\sigma_i$, then designs a global integral terminal sliding surface $\Theta_i(t)$ and a two-part control law $\mu_i(t)=\mu_{eqi}+\mu_{swi}$ to suppress chattering and ensure rapid convergence using Lyapunov analysis. Validation on the IEEE 39-bus New England four-area system under varying load and renewable scenarios shows substantial reductions in squared-error metrics (ITSE, ISE) and faster stabilization of both frequency and tie-line power compared with a PI controller, demonstrating enhanced robustness and transient performance. The work advances robust, decentralized LFC design for renewable-rich microgrids and points to future enhancements via adaptive inertia, learning-based control, and hardware-in-the-loop testing for real-world deployment.

Abstract

We present a load frequency control strategy deploying a decentralized robust global integral terminal sliding mode control (GITSMC) method to maintain stable frequency and tie-line power in multi-area interconnected microgrids with aggregated uncertainties. To achieve this, firstly, we have developed a mathematical model of the multi-area interconnected system incorporating disturbances from solar photovoltaic (PV), wind turbine (WT) generation and load demand, as aggregated uncertainties. Secondly, we have designed a global integral terminal sliding surface with an exponential reaching law for each area to enhance system dynamic performance and suppress chattering within a finite time. Thirdly, the overall stability of the closed-loop system is analyzed using the Lyapunov stability theorem. Finally, extensive simulations are conducted on the IEEE 10-generator New England 39-bus power system, including load disturbances and variable PV and WT generation. The results demonstrate the performance of the proposed GITSMC approach, achieving approximately 94.9% improvement in ITSE and 94.4% improvement in ISE, confirming its superior accuracy and dynamic performance compared to the existing controller.

Figures (5)

• Figure 1: Multi-area interconnected microgrids with thermal power plant along with PV and wind generators.
• Figure 2: Single line illustration of the IEEE 10-generator New England 39-bus power system roy2024robustroy2024multiIEEE39busyan2020multi.
• Figure 3: Step load, PV, and wind disturbances are applied across the four interconnected areas to emulate realistic operating conditions for evaluating the proposed GITSMC. Each disturbance includes added zero-mean constant variance Gaussian noise.
• Figure 4: Frequency deviations under variable PV, WT power, and step load fluctuations. The proposed GITSMC shows faster settling and smaller overshoot/undershoot compared to the PI controller.
• Figure 5: Tie-line power deviations under load, PV, and WT disturbances. The proposed GITSMC stabilizes the tie-line power quicker and decreases the oscillations compared to the PI controller.