Test Cases Library of Power System Sustained Oscillations

Forced oscillation case F_5_2 (Back to the homepage)

In this forced oscillation case, the source of oscillations is at generator 79.

System model:

Generator 79 is in GENROU model.

All other generators are in GENCLS model.

Parameter D for all generators equals 4, except for generator 79 whose D equals 0.

All loads are in constant MVA model.

Small signal analysis:

All natural modes have reasonably good damping.

The system has natural modes at 0.44Hz and 0.47Hz.

External force:

Forced oscillation is injected into excitation system as a sinusoidal signal at generator 79 with a frequency 0.46Hz.

The gain of the external force is tuned such that the largest peak-to-peak value among all generators' active power outputs is about 73MW.

Figure 1. Block diagram of the external force

Figure 2. WECC 179-bus power system

Generator angle oscillations for the case F_5_2 are shown in Fig.3. Many generators across the system have comparable magnitude of oscillations and the magnitude at the source in not the largest one.

Figure 3. Generator angles in the case F_5_2. Blue curve represents the source of oscillation at generator 79. Note that the magnitude of angle oscillation of the source generator is not the largest one.