The improved method of setting threshold in innovation graph technique

State estimation is the foundation of energy management system. The innovation graph state estimation has an advantage over traditional state estimation in identifying bad data. We infer the distribution function of innovation difference and set the threshold in certain false drop rate, which provides the theoretical basis for identifying bad data in mathematics. The range of acceptable measuring error depends on the accuracy of corresponding measuring instrument. This method reduces the false detecting rate and the loss detecting rate. The function of innovation graph technique to identify bad data is improved. The method proposed in this paper is verified in a simulation with bad data based on IEEE 14-bus system and the result show that the method is effective.