Chaos Oscillation Control Of Parallel Diesel Generators

In the navigation, with the changes in the external environment make impact, ship power system oscillation phenomenon is repeatedly observed, especially in the current application of ship electric promotion evolving circumstances, to avoid a ship power system crashes caused by external disturbances and equipment damage is particularly important. Chaos theory is an important non-linear science research, has penetrated into many disciplines and engineering fields. With the increasing scale of ship power systems, the nonlinear characteristics become more and more obvious, that chaotic behavior will happen under certain conditions, shows as mechanical and electrical irregular oscillations, that the system's security and stable operation be threated. Based on this, this dissertation will take chaotic dynamics theory to study the behavior of the ship power system's characteristics of chaotic dynamics, and induced mechanism also testing methods of ship power system and find effective measures to eliminate the chaotic oscillation.First, based on the model of a single diesel generator, coupled in parallel voltage and current relationship, this dissertation established the nonlinear mathematical model of parallel diesel generators, including speed control system model and voltage control system model. Joint the characteristics of diesel engines, and taking into account the transient change process of field winding, ignored the dynamic process of damping winding, the model dimension is higher than the previously used model, can be more accurate discribed. Use conventional PI control method to design speed and voltage controller, to simulate the change waveform of two generators, it verify the vilidity of the built model.Secondly, use the observation method and Lyapunov indices analysis method as the criterion of chaotic oscillation of dual-parallel system, both from the view and the characteristic quantities to analysis the chaotic dynamic characteristics of the system. Use Jacobian method to solve the Lyapunov indices of an single diesel generator of the system. Lyapunov spectra of the resulting index as a criterion to judge the conditions appear chaotic, by simulation of different conditions,obtain generator power angle and speed phase diagram and the waveform over time. It verify the accuracy of the Lyapunov exponent spectrum.Third, take into account the cycle power disturbance affect the electromechanical transient model,no affect to the transient excitation model. Robust control method is robustness to parameters of the system, and not depend on the precise mathematical model. And the ship power system is interference by many outside factors, is a strongly nonlinear system, so adopt the method of nonlinear robust control method to design the speed governor. Consider the large complex design process of robust nonlinear control method, so still use PI control method to design excitation controller. Simulation results show that under the role of design controller, the chaotic motion of dual-parallel diesel generator has been rapidly inhibit.