Simulation Analysis and Suppression Method of PT Low Frequency Oscillation in Distribution Network

The PT low frequency nonlinear oscillation is easily excited by external disturbances in the distribution network with ungrounded neutral point, which can cause the PT fuse fuse, burning loss and even the explosion accident frequently. The mechanism of PT low frequency oscillation is analyzed theoretically, and the phenomenon and key factors are simulated based on the electromagnetic transient simulation program PSCAD. A new low frequency oscillation suppression method for PT is proposed, that is, the PT neutral point is grounded by low frequency surge suppressor. The effectiveness of the suppression method is verified by simulation, and the low frequency inrush current can be controlled within the safe range. The theoretical research and the new suppression method proposed in this paper can provide guidance for PT fault analysis and the formulation of countermeasures in distribution network.