Аннотация:A dynamic model for the development of the transport network of the energy market in a given planning interval is proposed. A method for solving the problem of optimizing public welfare, reducing it to a finite set of auxiliary problems of convex programming, is specified. An auxiliary problem is considered with a fixed vector of line expansion indicators, which determines the line expansion schedule. It is shown that this problem is a special case of the well-known optimal control problem with discrete time with linear dynamics. For the initial dy- namic problem, if the functions of the variable costs of the extension are independent of time, and discounting is not essential, then, for ev- ery expanding line, all extensions must be done in the initial periods of the planning interval. If, in addition, the functions of variable costs are linear, then all extensions are made in the first period of time. In this case, the dynamic problem is reduced to the static one. In general the demand functions endogenously depend on the previous development of the transmission system. The corresponding model is also consid- ered. Finally, special features of modern electricity markets are consid- ered, and the task of optimal network development for the wholesale market is formulated taking into account these features.