State space model generation algorithm for analysis and control of power systems with HVDC link

Abstract

This thesis develops a program to generate linearized state space representation of the power systems including HVDC links. The two-axis model of synchronous generator and the IEEE type I model of exciter are used to represent dynamic behaviors of the generating units. For a HVDC model, a constant current controller for rectifier terminal, and a constant-extinction angle controller for inverter are employed. The developed program can accommodate an actual structure of the power systems with some numbers of generating units, HVDC links and the AC buses. In addition, the interchanges of real power between AC and DC sides, and of reactive power between AC side and the converter terminal, are computed using iterative technique. Reverse of the direction of the DC power flow can also be handled. The popular Western System Coordinating Council (WSCC) 3-machine, 9-bus is used for validation of the obtained eigenvalues of the linearized system. Furthermore, the developed program is tested using the Southern Thailand generation and transmission systems with 5 generating units, 1 HVDC link, of which it is connected to Malaysia, and the 28-bus and 41-branch AC transmission network. It is found that the program can function well. The results can then be used for analyzing small signal stability of the system, and for HVDC control design, thereafter.