| Abstract [eng] |
The increasing integration of photovoltaic (PV) systems into electricity distribution networks presents new challenges related to voltage stability and line loading, particularly in low-voltage grids with prosumer installations. This research investigates the application of dynamic export limitation based on line loading to enhance grid reliability and support safe PV penetration in Lithuania’s distribution network. A simulation model was developed using “MATLAB” / “Simulink” to analyze voltage and power dynamics under varying irradiance and grid conditions. The model incorporated Maximum Power Point Tracking (MPPT) algorithms – Perturb and Observe (P&O) and Incremental Conductance (“IncCond”) – and was applied with both two-level and three-level inverters. The performance of these algorithms was compared under irradiance fluctuation and voltage disturbance scenarios. The results showed that the Incremental Conductance algorithm, combined with a three-level inverter, achieved faster stabilization (0.06 s) and a higher power factor (cos(φ) ≈ 0.917) than the P&O algorithm (0.14 s; cos(φ) ≈ 0.809). Additionally, the “IncCond” method exhibited lower power oscillations (~0.1 kW) and reduced harmonic amplitude (~10⁻⁴). Simulated power ranged from 2.65 to 5.84 kW, closely matching real measurements of 2.48 to 5.71 kW, with an average deviation of ±0.21 kW. Dynamic export limitation based on line loading and voltage thresholds (e.g., Vac > 250 V) proved to be an effective strategy to reduce overvoltage risk and improve system flexibility. The results validate the model’s accuracy for real-world analysis and highlight the importance of integrating such methods into future grid management frameworks to support renewable energy expansion in Lithuania. |
