Power system modelling and scripting is a general and ambitious title. To cover all aspects of power system modelling would lead to an encyclopedia and likely be an impossible task. Therefore, the book focuses on a subset of power system models based on the following assumptions: (i) devices are modelled as a set of nonlinear differential algebraic equations, (ii) all alternating current devices operate in three-phase balanced fundamental frequency, and (iii) the time frame of the dynamics of interest ranges from tenths to tens of seconds. These assumptions restrict the analysis to transient stability phenomena and generator controls. The modelling step is not self-sufficient. Mathematical models must be translated into computer programming code to be analyzed, understood, and experienced. This is a key objective of the book.