An improved line differential protection based on average compensation for synchronous sampling in power systems

The sensitivity of line differential protection inevitably deteriorates in case of asynchronous sampling values caused by sampling devices. This paper proposes a new scheme to compensate the sampling synchronization error based on the average value of sampling value. The numerical processing method of this scheme processes the sampling values of the current on both sides, takes the current sampling value on one side as the reference sampling value sequence, and generates a data curve according to the original sampling value sequence affected by the sampling synchronization error on the other side. The average value is selected on the data curve in the middle of adjacent sampling points as the new data value of the sampling value sequence at the reference time to reduce the sampling synchronization error. Additionally, the effects of two error compensation methods (i.e. fitting and interpolation) are compared and the influences of sampling frequency on operation results are analyzed. The feasibility of the proposed method is verified through simulation.