Overcurrent Protection Multi-Value Configuration Scheme for AC Grids Containing New Energy Sources

Due to the unique characteristics of the new energy, which functions as a bidirectional current source, the current that passes through any branch circuit after a fault occurs is influenced by both the new energy component and the synchronous machine component operating in the same or opposite directions. As a result, the amplitude of the short-circuit current varies significantly under different operating conditions. This disparity in current amplitude makes it challenging to select an appropriate overcurrent protection value that adequately addresses selectivity and sensitivity. Consequently, this paper proposes establishing multiple sets of overcurrent protection values to accommodate the distinct electrical characteristics of the new energy components operating in different directions. These sets account for scenarios where the new energy components align with or oppose the positive sequence components, and the electrical transient characteristics serve as an additional criterion to ascertain the direction of the new energy components before switching to predefined values. Finally, the proposed scheme is validated through simulation in the IEEE 39-node system to confirm its effectiveness.