含T接逆变电源的配电线路自适应纵联阻抗保护OA

In distribution systems with T-connected inverter-based resources(IBRs),differences in control strategies between grid-following and grid-forming IBRs lead to multi-source coupled nonlinear fault current characteristics,potentially causing maloperation or failure of conventional protection schemes.An adaptive pilot impedance protection method,based on equivalent IBR sequence impedance phase angle intervals,is proposed.The phase angle difference intervals between the point of common coupling voltage and positive-sequence output currents of both types of IBRs are quantified according to their fault ride-through control strategies.Impedance characteristics of IBRs in the negative-sequence network are analyzed,and equivalent sequence impedance phase angle intervals for different IBRs are unified in sequence networks to decouple fault characteristics from source-side control dynamics.Consequently,an adaptive positive-sequence impedance protection criterion is constructed based on the phase angle difference between the estimated T-node voltage and differential current.For asymmetric high-resistance faults,this paper proposes an additional protection criterion,which combines the accumulation and polarity product of negative-sequence impedance phase angles,to enhance resistance to transition resistance.Simulation results show that the proposed protection scheme can identify faults within 8 ms,withstand 500 Ω high-resistance faults eliminate the need for sampling data synchronization,and remain unaffected by the type and capacity of IBR.