Fault State Identification and Active Suppression of Zero Sequence Oscillation in Resonant Grounded Distribution Networks

Resonant grounding distribution networks generally typically uses overcompensation to prevent the arc suppression coil and system-to-ground capacitance from creating a zero-sequence loop resonance once the fault is cleared. This paper proposes an active injection method to identify the fault status and an active suppression method for zero-sequence resonance to solve this problem. Firstly, the online identification of the impedance parameter of the system to the ground employs the recursive least square (RLS) algorithm. The system's fault condition is then ascertained based on this impedance identification value. Secondly, as soon as the fault disappears, appropriate resistor is put into dissipate the fault transient energy. Finally, two-stage model predictive control (TSMPC) is used to adjust the injected current, clamp the neutral-to-ground voltage and suppress system oscillation. On this basis, the optimal dissipation resistance calculation method is derived. The correctness and feasibility of the method and control strategy are confirmed through both theoretical analysis and simulation.