Lightning faults early warning and trip probability calculation have a positive significance for power system protection against lightning faults. A novel algorithm for calculating lightning trip probability based on lightning subareas information at three adjacent time intervals is proposed. Firstly

lightning subareas are identified based on image recognition technology according to lightning monitoring information at each time interval. Then the optimal trajectory of lightning subareas is determined by the optimization method. The lightning subareas information at current time interval

previous adjacent time interval and the trajectory of lightning subareas constitute the lightning subareas information at three adjacent time intervals

based on which the relevant information

including variations of lightning subareas characteristics (area

lightning current intensity

lightning probability of the lightning subarea) at next time interval are forecasted. Finally

the trip probability of the transmission lines within the forecasted lightning subareas are calculated. Since more lighting monitoring information is utilized

the method proposed has higher precision of lighting area forecast. Accordingly

the lines trip probability also has higher precision and could be used as the lighting warning index. The results of the samples show the validity of the proposed method.