Passivity based control applied to stand alone generators

The paper presents the study and the design of air embedded electronic control system that allows diesel engine driven stand-alone synchronous generators to operate at variable (optimum) speed. A new control strategy has been developed, based on passivity theory for the PWM inverter control and a fuzzy, logic fuel admission control system, to overcome the nonlinearity introduced into the system by the diesel engine. In order to use the passivity theory approach, the system was described in Euler-Lagrange form, such systems representing the outcome of the powerful variational modelling method. MATLAB software was used for the complete power and control system design and simulation and a novel approach was adopted for the FPGA implementation of the digital controller. The method is based on using Handel-C, an innovative language for implementing algorithms in hardware, architectural design space exploration and hardware/software co-design. The new PWM passivity based controller was designed, successfully simulated and is currently being implemented in a Virtex Xilinx FPGA. Experimental tests are being carried out to validate the behaviour of the controller. The main achievements of the new control system relate to the efficient maintenance of the output voltage at the desired magnitude and frequency independent of the rotational speed of the generator, under variable loading conditions, thus allowing variable (optimum) speed operation of the diesel engine.