Kiichiro Tsuji

Robust load frequency regulation in a new distributed generation environment

A new approach based on /spl mu/-synthesis technique is proposed for the design of robust load frequency controller in response to the new technical demand for load frequency regulation in a competitive distributed generation power system. The siting of numerous generator units in distribution feeders is being encouraged by the current deregulation of the industry is likely to have an impact on the load frequency control (LFC) operation of the existing power systems. In this approach the overall power system will be divided to some distribution areas. Each area is modeled as a collection of distributed generators to supply the area-load. The area is responsible to perform its own LFC by using an independent robust controller. An example for a distribution area is given to illustrate the proposed approach. The resulting controller is shown to minimize the effect of disturbances and achieve acceptable frequency regulation in presence of uncertainties and load variation.

Robust decentralized LFC design in a deregulated environment

In this paper, a decentralized robust approach is proposed for load-frequency control (LFC) design in a deregulated environment using bilateral market scheme. First, the effect of bilateral contracts as a set of new input signals is taken into account in the control area dynamical model, and then the LFC problem will be formulated as a multi-objective problem to cover robust performance, practical constraint on control action and minimize the effects of load disturbance under wide range of demand changes. A mixed H/sub 2//H/sub /spl infin// is used to solve the problem and design the desired robust controllers. A three-control areas power system example with possible contract scenarios and load changes is given to illustrate the proposed approach. The resulting controllers are shown to minimize the effect of disturbances and maintain the robust performance.

Automatic Generation Control: A Decentralized Robust Approach

Automatic Generation Control (AGC) problem has been one of the major subjects in electric power system design/operation and is becoming much more significant today in accordance with increasing size, changing structure and complexity of interconnected power systems. In practice, AGC systems use simple proportional-integral (PI) controllers. However, since the PI controller parameters are usually tuned based on classical or trial-and-error approaches, they are incapable of obtaining good dynamical performance for a wide range of operating conditions and various load changes scenarios in a multi-area power system. nIn this paper, in order to design a robust PI controller for the AGC in a multi-area power system, first the problem is formulated as an Hinf static output feedback control problem, and then it is solved using a developed iterative linear matrix inequalities algorithm to get an optimal performance index. A three control area power system example with a wide range of load changes is given to illustrate the proposed approach and the results are compared with Hinf dynamic output feedback control design.

DC-DC quasi-resonant converters: linear robust control

In this paper, a general robust control synthesis framework is proposed for DC-DC quasi-resonant converters (QRCs) in order to achieve both stability and desired performance, such as reduced sensitivity to load variations, desired disturbance rejection, reduced output impedance and attenuated transfer from input to output. The /spl mu/-analysis is used to design and verify the robustness of the resulted controller. The proposed control strategy is applied to a typical zero-current switching QRC and nonlinear simulation is performed using nonlinear model of converter circuit. The simulation results demonstrate the good reference voltage tracking, line disturbance rejection and show that the designed procedure guarantees the robust stability and robust performance for a wide range of load variation.