Sliding mode-based direct power control of unified power quality conditioner

Area of Science:

• Electrical Engineering
• Power Systems Engineering
• Control Systems

Background:

• Unified Power Quality Conditioner (UPQC) mitigates distribution system power quality issues like harmonics and voltage sags/swells.
• Conventional Sliding Mode Controllers (SMC) in UPQCs exhibit chattering, wide switching frequency variations, and coupled active/reactive power control.
• These limitations hinder optimal UPQC performance in dynamic and steady-state conditions.

Purpose of the Study:

• To propose and evaluate a novel Sliding Mode-based Direct Power Control (SMC-DPC) for UPQCs.
• To address the limitations of conventional SMC by reducing chattering and switching frequency variations.
• To achieve simultaneous and precise regulation of active and reactive power in UPQC shunt and series compensators.

Main Methods:

• Developed a nonlinear control strategy, SMC-DPC, for UPQC shunt and series compensators.
• Implemented real-time power error-based voltage vector selection for optimized control.
• Simulated the proposed SMC-DPC on a 20 kVA system using MATLAB Simulink®.

Main Results:

• Achieved a source current Total Harmonic Distortion (THD) of 1.52%, significantly lower than conventional SMC (2.31%) and linear controllers (5.11%).
• Demonstrated robustness to grid parameter variations and effective performance in both strong and weak grids.
• Reduced line losses by 13.71% and 14.54% in weak grids compared to SMC and linear controllers, respectively.

Conclusions:

• The proposed SMC-DPC effectively mitigates power quality issues and enhances UPQC performance.
• SMC-DPC offers improved steady-state and dynamic power tracking with simplified system design.
• Results comply with IEEE-519 and IEC 61000-3-12 standards, confirming its suitability for distribution systems.