On Market-based Robust Load-frequency Control H. Bevrani and T. Hiyama Dept. of Electrical & Computer Eng., Kumamoto University Japan Key Words: LFC, Mixed ∞ /H H 2 , Robust performance, Time delay, LMI. Abstract 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 ∞ /H H 2 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. 1. Introduction In a liberalized electricity market, control is highly decentralized. Each load matching contract requires a separate control process, yet this control processes must cooperatively interact to maintain system frequency and minimize time error. Since a separate control process is needed for each load matching contract, there must be a Virtual Control Area (VCA) associated with each contract group. Therefore, the concept of physical control area is replaced by VCA. The boundary of the VCA encloses the generation companies (Gencos) and the distribution companies (Discos) associated with the contract. The Discos receive the regulating power directly or through transmission companies (Transcos). Such an overall configuration is shown conceptually in Fig. 1. Each VCA will be interconnected to each other either through Transco or Gencos. The control center includes two agents: Data Acquisition and Monitoring (DAM) agent, and, Decision and Control (DC) agent. The Gencos send the bid regulating reserves Fi($,t) to the DAM agent through a secure internet service. The DAM agent sorts these bids by pre-specified time period and price. Then, it sends the sorted regulating reserves with the demanded load from Discos and the measured tie-line flow and area frequency to Author Personal Copy Author Personal Copy