Impact Analysis of On-Load Tap-Changer on Reactive Power and Voltage Optimization in Distribution Networks

As renewable energy integration, particularly photovoltaic (PV) generation continues to grow, its inherent volatility and randomness pose significant challenges to power grid, including voltage fluctuations, voltage out of limit and increased line losses. The traditional reactive power and voltage optimization method combining off-circuit tap-changer (OCTC) transformers and capacitor banks (CBs) has become ineffective. This paper proposes a novel reactive power and voltage optimization method based on objective programming to address these issues in low-voltage distribution networks. The method focuses on minimizing voltage deviations and network losses by leveraging on-load tap-changer (OLTC) transformers and CBs. A Particle Swarm Optimization (PSO) algorithm is employed to solve the multi-objective optimization model, which prioritizes voltage quality and power factor improvement while reducing network losses. Simulation results demonstrate that replacing OCTC transformers with OLTC transformers significantly enhances voltage regulation performance, ensuring voltage compliance and reducing network losses. Furthermore, the study explores the impact of different OLTC tap types, concluding that a 5-tap adjustment scheme is more efficient than a 9-tap scheme under operational constraints. This research provides valuable insights for optimizing reactive power and voltage control in distribution networks with high renewable energy penetration, offering a practical approach for improving power grid voltage levels.