Transient and Small Signal Stability of a Two Area HVAC Power Network Interconnected with an HVDC Link.

L.C. Azimoh, D.T. Oyedokun, S. Chowdhury, S.P. Chowdhury, and K.A. Folly (South Africa)


HVDC, HVAC, Transient stability, small signal stability, eigenvalue


This paper presents an analysis of transient and small signal stability of a two-area multi machine power system. This is achieved by investigating the responses of generator speed, the terminal voltage, the rotor angle difference and power transmitted, after a transient perturbation of a single phase to ground fault. Furthermore, the study shows the effect of small signal disturbance of power systems when a dc link is interconnected with a weak ac link. The small signal stabilities of three different transmission systems are investigated, using the two-area power system model. The following three cases are used for the study of small signal stability study - High Voltage Alternating Current (HVAC) Link, High Voltage Direct Current (HVDC) Link and the hybrid HVAC/HVDC link. The transient stability was investigated on the hybrid HVAC/HVDC by applying a single phase to ground fault at middle of the line L9 of HVAC line on the hybrid power network. This study shows that even when the parent networks HVAC and HVDC are stable, their interaction could affect the stability of the power network if the tie between them is weak.

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