Mathematical modeling means that when a practical problem needs to be analyzed and studied quantitatively, people should express it as a mathematical formula with mathematical symbols and language on the basis of in-depth investigation, understanding of object information, making simplified assumptions and analyzing internal laws, and then use the calculated model results to explain the actual problem and accept the actual test. The whole process of establishing mathematical model is called mathematical modeling.

Digital simulation is a process of establishing mathematical models of power system network and load components, and using the mathematical models to carry out experiments and research on digital computers. The realization of digital simulation generally includes three main steps: establishing mathematical model, establishing digital simulation model and simulation experiment; Digital simulation of power system is widely used, including: studying digital simulation of power system, such as electromagnetic transient calculation program (EMTP), power system integrated power flow program (BPA), training digital simulation of power system, such as power system dispatcher training system (DTS), substation training simulation system and so on.