A Distance Protection Based on the Estimation of System Model Parameters

Most of the distance relays base their operation on the measured apparent fault impedance. These relays are bound to have an error inflicted by the unknown remote end parameters and fault resistance. This paper presents a method, which diminishes such errors using optimization techniques. The proposed method executes a system model unknown parameter estimation by adjusting model output to measurements from the same substation with the Monte Carlo method in sequence to pre-fault and fault regimes. This allows the elimination of uncertainty, caused by incomplete scope of information, available to classic relays. The proposed method was tested on a three machine system with a fault in one of parallel lines bounded by a mutual inductance and was proved to obtain fault parameters with an acceptable tolerance. The proposed method can be applied in a standalone application or it can provide reliable fault parameter data and improve the distance protection sensitivity.