Δφ_c = 180 – 100 = 80°. The system is stable. At no-load conditions,

the cutoff frequency decreases, and Δφ_c increases.

Effect of System Parameters on Stability

Voltage Unit (VU / Блок БН). When setting "КΔU to position "8":

The LAFC of the system rises, ω_c increases, and the system

 may become unstable. When changing "КΔU" towards a lower value,

 the alteration of the term (1 + p · 0.24) leads to a decrease

 in ω_c and a more sluggish transient response.

Amplification Unit (AU / Блок БУ). Increasing "kIв" while

holding the remaining gain coefficients constant reduces the

gain at frequency range of 1/0.24 > ω > 1/5.94. It then

recovers at frequencies of ω > 1/0.24. With a further decrease

 in K_AU, ω_c may decrease.

To evaluate the quality of the AVR transient response, we

utilize the methodology outlined in [13]. Let us evaluate the

behavior of the control system under a step input excitation

applied to the system: X_Т(p) = 1/p. The reference

points correspond to actual operating modes of the system

under various disturbances that lead to voltage or reactive

power oscillations.

(From the feedback side regarding voltage and reactive current).

From Fig. 8 page 19.4, the transfer function of the open-loop system in t

he region of ω_c is: