In this chapter, the main scope lies in the time-domain analysis of regulation and operation of HPPs. The primary goal is to briefly present the methods and procedures of the analysis. First, a numerical model in the software TOPSYS, developed for scientific studies and consultant analyses of the transient processes of HPPs, is briefly presented. Second, information of a practical engineering case, i.e., areal Chinese HPP with a surge tank and Francis turbines, is introduced. In the third place, a case study of various dynamic processes is conduced based on a real consultant project of the Chinese HPP; key requirements and main influencing factors of the diverse conditions of regulation and operation are analyzed.