| The dynamic characteristics and model of AC/DC parallel transmission power system are investigated in this paper. Taking System status and parameters variation into account, a comprehensive uncertain nonlinear model is presented, and robust stability control strategy is introduced into and robust controller is designed. And the characteristics and theories of complex random network power system are preliminarily studied as well.At first, the model of classic AC/DC parallel transmission power system is presented, in which the dynamic characteristics of both AC and DC part are considerd. The parameters of generator units in AC part are considered differently and dealt with respectively, and a third-order dynamic model is used to describe the DC part. Power perturbation of the system is also taken into account. The proposed model is a nonlinear and uncentain one which can appropriately describe common classic AC/DC systems. Then a robust control strategy is brought in for this model. The model is linearized by exact feedback linearization method and then a robust controller is designed. Simulation results show the effectiveness of the controller.Then the model is improved for multi-geneator systems. Excitation control is considered in the AC part, and algebraic equations of the system as power flow equations are added to connect AC and DC part. So that, nonlinear uncertain differential-algebraic model of AC/DC system is established. The nonlinear model is then linearized by feedback method for differential-algebraic system. Robust controller is designed to the system and simulation results show that the presented controller can improve the stability of power system.In the last part of this paper, research achievements in the field of complex random network are introduced briefly. The model of complex power grid with AC/DC transmission line is preliminarily studied, and the model of generator network is presented. Controller is designed correspondingly.
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