Natural oscillation case ND_1 (Back to the homepage)
This case is a single source - single local mode natural oscillation case, where the oscillation source is generator 45.
System model:
Disturbance:
Small signal analysis:
Observation from transient:
![Mountain View](source\wecc179_1nd.jpg)
Figure 1. WECC 179-bus power system
Fig. 2 shows the spectra of oscillations and Fig. 3 shows the rotor angles for generators 45 and 159. This case has one lightly damped local mode 1.41Hz and the source of negative damping is the generator 45.
![Mountain View](source\Spectra_NO_case1.jpg)
Figure 2. Spectra of oscillations for the case ND_1
![Mountain View](source\Rotor_Angles1_NO_case1.jpg)
![Mountain View](source\Rotor_Angles2_NO_case1.jpg)
![Mountain View](source\Rotor_Angles3_NO_case1.jpg)
Figure 3. Rotor angles of generator 45 and 159 in the case ND_1
The specifics of this case is that a fault at generator 159 excites the maximal magnitude of rotor angle oscillations at generator 159 while the source of oscillations is actually located at another generator, i.e. generator 45.