Nonlinear H_∞ governor for diesel engine of ship power station

The frequency stability of a ship power system is determined by the speed response characteristic of the diesel engine speed regulation system in the ship power station. The diesel engine speed regulation system in the ship power station is a nonlinear control system. In order to analyze the dynamic characteristic of the system, a nonlinear mathematical model of the diesel engine speed regulation system was built first, and a nonlinear H_∞ governor was designed on the basis of this. The method which combines direct feedback linearization with H_∞ control theory was used to design the diesel engine governor, which transforms the specifications of the system into a standard H_∞ control problem, then a nonlinear H_∞ speed control law of the diesel engine was achieved by solving the Riccati equation. The computer simulation results show that the nonlinear H_∞ governor improves the dynamic precision of the system and the ability to restrain the load disturbance in case of system model uncertainty, thus improves the frequency stability of a ship power system.