BOUHADJI, FATIHA2026-05-262026-05-262026http://dspace.univ-chlef.dz/handle/123456789/2447THESIS Submitted in fulfillment of the requirements for the degree of DOCTORATE (LMD) Field: Electrotechnics Specialty: Electrical networksHarmonic distortion caused by nonlinear loads remains a major challenge for modern electrical networks, as it degrades power quality, increases system losses, and accelerates the aging of grid components. Conventional passive filters provide only partial mitigation and lack adaptability under varying operating conditions. To overcome these limitations, active power filters have emerged as an effective solution for harmonic suppression and reactive power compensation. This thesis focuses on the design and control of a parallel active power filter based on a three-level Neutral Point Clamped (NPC) inverter. The Direct Current Control (DCC) method is employed for harmonic current detection, while an advanced Third-Order Sliding Mode Control (TOSMC) strategy is adopted to overcome the drawbacks of conventional controllers, such as sensitivity to parameter variations, steady-state errors, and limited dynamic performance. TOSMC offers improved stability, high tracking precision, and reduced chattering, making it particularly well-suited for power quality applications.In addition, a photovoltaic generator is integrated through the DC link, enabling the system not only to compensate harmonics but also to inject renewable active power into the grid. Simulation results demonstrate significant improvements in harmonic reduction, reactive power compensation, and overall system stability, confirming the effectiveness of the proposed approach.Power qualityHarmonic distortionParallel active filterThesis