Power System Operation and Control

4.4 GENERATOR LOAD MODEL

The increment in power input to the generator load system is ΔP_G – ΔP_D, where ΔP_G = ΔP_t, the incremental power output and ΔP_D is the load increment. Assume that generator incremental losses of the generator are neglected. The increment in power input to the system is accounted for in two ways:

i) Rate of increase of stored kinetic energy(KE) in the generator rotor at scheduled frequency f⁰

 

The stored KE is        W⁰_ke = H * P_r (KJ of MJ)                    (4.9)

Where P_r, is the MW rating of the turbo-generator and H is defined as its inertia constant.

 

The kinetic energy being proportional to square of speed (frequency), the kinetic energy at a frequency of (f⁰ + Δf⁰) is given by

and the rate of change of KE is ...