In this chapter we present the price-based control as a suitable approach to solve some of the challenging problems facing future, market-based power systems. On the example of economically optimal power balance and transmission network congestion control problem, we present how global objectives and constraints can in real-time be translated into time-varying prices which adequately reflect current state of the physical system. Furthermore, we show how the price signals can be efficiently used for control purposes. Becoming the crucial control signals, the timevarying prices are employed to optimally shape, coordinate and synchronize local, profit-driven behaviors of producers/consumers to mutually reinforce and guarantee global objectives and constraints. The main focus in the paper is on exploiting specific structural properties of the global system constraints in the synthesis of pricebased controllers. The global constraints arise from sparse and highly structured power flow equations. Preserving this structure in the controller synthesis implies that the devised solutions can be implemented in a distributed fashion.