Load frequency control of power systems with non-linearities

Load frequency control (LFC) for power systems with governor deadband (GDB) and generation rate constraint (GRC) non-linearities is discussed in this study, with the objective to add anti-windup schemes for any designed LFC controller, so that the stability and performance of the existing LFC controller can be retained when there are non-linearities. Effects of GDB and GRC on the performance of LFC controllers are first analysed via describing function method. Anti-windup schemes are then proposed to compensate the GDB and GRC non-linearities. For GDB, the error between the realistic and the ideal outputs of the generator is added to the output of LFC controller for rejection, and for GRC, the error between the realistic and the ideal outputs of the turbine is fed back to the observer of the LFC controller for estimation and elimination. Simulation results show that the compensation schemes are effective in overcoming the adverse effects of GDB and GRC.