Simulation Research And Model/Strategy Of Coordinated Control In AC/DC Systems

With the execution of the project of the power transmission from west to east, a highly complex AC/DC Power System will be established. Given the coordinated control strategies of AC/DC Power System are far from flawless, a new control strategy has to be developed to improve the controller's functions. An efficient and accurate simulation analysis capacity which lays the foundation of the design, operation and dispatching of the AC/DC Power System is one of the major measures to improve the dynamic stability of the system. The PSASP, BPA and PSS/E are the commonly adopted simulation software packages by the power industry, and they are varied by using different electric component models, parameters and date format. However, the help file of software and the existing literature rarely analyze this aspect, making proper use and grid data conversion of them less desirable. Considering the above two problems, this paper firstly studies the dynamical model and Robust Control strategy of the AC/DC coordinated control, then it analyzes and compares the models, parameter settings and User-defined Modeling of PSASP, BPA and PSS/E. It makes a noticeable progress on the following points:â‘ A six-order nonlinear dynamic model is set up for a single machine infinite bus system, in which the coordinated control process of the generator and HVDC are considered comprehensively. The modulating signals of firing delay angle at the rectifier and firing lead angle at the inverter, and the excitation voltage are chosen to be control variables. The offset of the current of DC line and the extinction angle and the power angle of generator are chosen to be control outputs. By making use of the linear matrix inequality(LMI) approach, H2 controller parameters are obtained. The simulation results show that the nonlinear controllers have ulterior better ability to damp the oscillation and to improve the dynamic stability of the studied system in comparison with the conventional controller.â‘¡This paper has introduced the working principle of the transformer, generator models, and excitation regulator of PSASP, BPA and PSS/E. To this end, this paper has demonstrated the conversion formula of transformer models, the correctness of introduced content has been demonstrated by applying to a simulation example. According to existing research, this paper has more detailed introduced the two winding transformer's excitation branch model and three winding transformer's impedance model. Then the realization of User-defined excitation regulator has been newly added. Above all, it has made foundation of proper use and software secondary function extension.â‘¢This paper has analyzed and compared the steady state model and quasi-steady state model. The combined difference of DC control modes are also analyzed in this paper. The analysis has been verified by a simulation case. According to existing research, this paper has added DC models and the combined DC control modes of different software, which has made foundation of proper use.