Load Frequency Control of Multiple-area Power Systems

In an interconnected power system, as a power load demand varies randomly, both area frequency and tie-line power interchange also vary. The objectives of load frequency control (LFC) are to minimize the transient deviations in theses variables (area frequency and tie-line power interchange) 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. Active disturbance rejection control (ADRC), as an increasingly popular practical control technique, has the advantages of requiring little information from the plant model and being robust against disturbances and uncertainties. This thesis presents a solution to the LFC problem based on ADRC. The controller is constructed for a three-area power system with different turbine units including non-reheat, reheat and hydraulic units in different areas. The dynamic model of the power system and the controller design based on the model are elaborated in the thesis. Simulation results and frequency-domain analyses proved that ADRC controller is attractive to the LFC problem in its stability and robustness.