Discontinuous Feedback Linearization Sliding Mode Control of a synchronous generator machine and hydraulic turbine

A novel robust control technique is proposed for the control of synchronous machines operating in electric power systems. The Sliding Mode Control technique belongs to the Variable Structure Systems Theory. The control law used is unique, non-linear and besides, it is discontinuous. Its discontinuous nature allows the controller to enhance the robustness of the system; which means that the control is insensitive to model uncertainties as well as to external disturbances. The sliding mode control approach is applied together with the Feedback Linearization technique, which is used here to obtain a decoupled-reduced form of the system in terms of the output controlled variables and the control input. Two different control schemes using sliding mode control are proposed and applied to synchronous machines. The response is obtained using a complete high order model for the machine, taking in consideration the model of the hydraulic turbine. The analysis of the obtained results show that in both cases the system response to small as well as to large disturbances, show a significant advantage of the proposed control techniques over conventional linear control systems for the Automatic Voltage Regulation (AVR) and the Power System Stabilizer (PSS). Moreover, the analysis of the system response to parameter variations demonstrates the robust characteristic of the non-linear discontinuous controller. The advantages obtained with sliding mode control appear directly in the operational behavior of the system as a substantial improvement in the stability characteristics of the electric power system.