In a deregulated environment, Load-frequency control (LFC), as an ancillary service essential for maintaining the system reliability, acquires a fundamental role to enable power exchanges and to provide better conditions for the electricity trading. Since the LFC system is faced by new uncertainties in the liberalized electricity market, a reevaluation in traditional modeling and control structures is highly needed. In response to the coming challenge of integrating computation, communication and control into appropriate levels of system operation and control, a comprehensive scenario is proposed to perform the LFC task in a deregulated environment. As a part of the mentioned scenario, this paper addresses a new method to design of robust LFC with considering the communication delays. First the LFC problem is reduced to a static output feedback control synthesis for a multiple delays power system, and then the control parameters are easily carried out via a mixed H2/H∞ control technique, using a developed iterative linear matrix inequalities (ILMI) algorithm. The proposed method is applied to a 3-control area power system ∞and the results are compared with the recently developed H∞ -based LFC designs.
