Research On Nonlinear Robust Control Of Ship Power Systems

Compared to the land power systems, the stability of ship power systems have been influenced by the propeller loads obviously. Furthermore, the dynamic/static loads and generators have high nonlinear and coupling interactions. Therefore, based on the method of nonlinear robust control, the stability analysis and nonlinear control problems for ship power systems with thruster load are investigated to increase dynamic quality of ship power systems.Firstly, a nonlinear mathematical model of diesel generator set is established which contains thruster load. The model reflects the impacts of loads and frequency and voltage of generators and shows the relationships of variable coupling of ship power systems.Secondly, the nonlinear relationships among the generators and the dynamic/static loads are deeply analyzed based on mathematical models. Then the speed regulation controller, voltage regulation control and comprehensive coordination control is designed by using Backstepping techniques and L2 disturbances attenuation methods, which seriously reduces the impact of disturbances. Lastly, simulations show that the designed controller is effective to reject the unknown external disturbances when in the case of increase dynamic/static loads.Thirdly, based on Hamilton energy theory control approach, a simple controller structure is obtained. The problem of integrated coordination control involved in excitation and speed-adjusting of ship power systems with propeller loads is investigated. A stabilizing integrated controller is proposed by constructing Hamilton energy function. In particular, the obtained control law explicitly formulates the function relations of the influence of propeller rev on control performance, as different from the existing results.Fourthly, a coordinated control problem of ship power system with SMES is addressed based on Hamilton function method. The higher performance is required for power assignment of ship power systems since power thruster loads and new styles of weapons are introduced, SMES can effectively adjust active power and reactive power in four quadrant directions. Firstly, nonlinear modeling of marine diesel engine generator, SMES modeling, and thruster load modeling, coupling relations among them are analyzed sufficiently. Then Hamilton realization of the modeling of the generator is obtained by a pre-feedback technique. As such, the controllers with SMES are designed to perform speed adjustment, excitation adjustment via Hamilton dissipation theory. The designed controllers have simple structure and tangible physical meanings.Fifthly, this section focuses on the modeling and the problems of integrated coordinate control of ship multi-generator power systems with propeller loads. A control algorithm is developed based on Hamilton energy theory which produces a coordinate control law involved in excitation and speed-adjusting. A stabilizing integrated controller is proposed by constructing Hamilton energy function. A paralleling system of dual machine is simulated. Simulation shows the robustness of the proposed controller.