Reduced Order Observer Based Load Frequency Control Using Pole-Placement Design

Abstract

In a power system, as a power load demand varies randomly, both area frequency and line power also vary. The objectives of load frequency control (LFC) are to minimize the transient deviations in these variables (area frequency and line power) and to ensure their steady state errors to be zeros. When dealing with the LFC problem of power systems, unexpected external disturbances, parameter uncertainties and the model uncertainties of the power system pose big challenges for controller design. In this project, a reduced-order state observer with a practical point of view for LFC problem in a power system is proposed based on the pole-placement method. A proper choice of closed-loop pole location has been proposed using symmetrical root locus (SRL) method. In the practical environment, there is limited access to all state variables of system and measuring all of them is usually impossible. So when the available sensors are less than the number of states or when it may be undesirable, expensive or impossible to measure directly all of the states, a reduced-order state observer can be applied as proposed in this project. The proposed strategy is tested on a single area power system. The dynamic model of the power system and the controller design based on the model are elaborated. The robustness and stability of the control schemes is examined through simulations.