Test Cases Library of Power System Sustained Oscillations

Forced oscillation case FM_7_1 (Back to the homepage)

In this forced oscillation case, the source of oscillations is at the governor of generators 79 and 118, i.e. there simultaneously exists two sources of harmonic disturbances in the governors of two generators, creating near-resonance conditions with two different natural modes.

System model:

All the generators are in GENCLS model.

Parameter D for all generators equals 4.

All loads are in constant MVA model.

Small signal analysis:

All natural modes have reasonably good damping.

The system has the following natural modes at 0.445, 0.476 and 0.667Hz.

External force:

Forced oscillations are injected into the governor of generator79 at f=0.65Hz and into the generator 118 at f=0.43Hz.

The gains of both these external signals is 0.03 p.u.

Figure 1. Block diagram of the external force at generator 79

Figure 2. Block diagram of the external force at generator 118

Figure 3. WECC 179-bus power system