Energy Function Methods

This chapter discusses in detail the transient energy function (TEF) method for angle stability. In the power literature, Lyapunov's method has become synonymous with the TEF method and has been applied successfully. Today, this technique has proved to be a practical tool in dynamic security assessment. The chapter discusses the potential energy boundary surface (PEBS) method because of its simplicity and its natural relationship to the equal‐area criterion. The chapter discusses the method through application to a single‐machine infinite‐bus system, the equivalence between the energy function and the equal‐area criterion, and explains the multimachine PEBS method. The energy function, Lyapunov function, and the PEBS are all equivalent in the case of a single‐machine infinite‐bus system. For the multimachine case, the chapter explains the PEBS and the boundary controlling u.e.p (BCU). Finally, the structure‐preserving energy function (SPEF) is derived. The SPEF is an active area of research.