Busbar differential protection method

A busbar differential protection method, characterized in that the method comprises the steps of:

• (1). sampling the voltage of a busbar continuously and respectively sampling the currents of all intervals on the busbar synchronously at the meantime;
• (2). respectively fitting the sample values of the busbar voltage and current sample values of the respective intervals to get a fitting curve for the voltage of the busbar and fitting curves for the currents of the respective intervals;
• (3). determining a zero-crossing point on the fitting curve for the voltage of the busbar;
• as to the fitting curve for the current of each interval, sampling each fitting curve for the current in turn from the above zero-crossing point according to a given sample time period, to get a sample sequence of each interval, said sample sequence comprising current sample values of sampling points and sample serial numbers corresponding to the sampling points;
• the sample serial numbers of sampling points at the same time being the same for the sample sequences of the respective intervals;
• (4). storing the sample sequences of the respective intervals, differentially computing the current values with same sample serial numbers for the sample sequence of respective interval, and conducting a differential protection according to the computation results.