| Kinetic Energy Analysis for Smaller Systems |
|
This analysis is intended for a system with fewer generators and with power supplies that have no inherent inertia, e.g., wind farms. Starting with individual power supplies, we develop the composite of all the sources.
|
|
The stored energy for an individual “real” generator is expressed as follows: |
|
Eg = Hg
* ( F / F0 )^2 * Sg |
|
The stored energy for an individual conventional wind farm is expressed as follows: |
|
Ew = Hw
* ( F / F0 )^2 * Sw |
|
To get the system stored energy of the interconnected resources,
we add up the individual stored energies: |
|
Es = ∑ Hg
* ( F / F0 )^2 * Sg + ∑
Hw * ( F / F0 )^2 * Sw |
|
At this point we “remove” the wind farms since they have no stored energy, i.e., their “H” is zero: |
|
Es = ∑ Hg
* ( F / F0 )^2 * Sg |
|
This is where we can derive a composite “Hs” and a composite “Ss”. Notice that the system stored energy does not include the effect of wind farms:
|
|
Es = Hs * ( F / F0 )^2 * Ss
|
|
Note that:
|
|
Hs * Ss =
∑ Hg * Sg
|
|
This is an opinion for how to derive a “weighted average” for system “H” for simulation studies.
In conclusion, the inertia of the system does not change with the addition of conventional wind farms.
Consider a shaft with large heavy flywheels and some light thin disks.
Where will most of the stored energy reside?
|