Page 168 - AJWEP-v22i2

Reddy and Kumar

Table 4. Performance of the power system under light operating conditions
Power system Overshoot Settling time (s)
states Base FACTS FACTS Base FACTS FACTS
case only with ACO Case only with ACO
∆ω 0.0169 0.0166 0.0144 25 9.45 3.16
∆δ −2.01 −1.95 −1.62 25 7.07 3.02
δ 2.09 2.01 1.87 9.36 3.59 2.16
Notes: ∆ω = Speed deviation; ∆δ = Rotor angle deviation; δ: Voltage stability
Abbreviations: ACO: Ant colony optimization; FACTS: Flexible Alternating Current Transmission System.

5.2.3. Results from simulation under lighter operating
conditions
A disturbance is assumed to occur when the load
changes quickly. The overshoot and settling time under
lighter operating conditions are shown in Table 4.
Table 4 presents the power system performance during
light operation conditions, highlighting the impact of
FACTS controllers with and without ACO. The table
compares the overshoot and settling time for ∆ω, ∆δ,
and δ across three scenarios: the base case (without
FACTS controllers), FACTS only, and FACTS with
ACO. The results demonstrate that ACO-optimized Figure 11. Deviation of rotor speed with FACTS,
FACTS controllers significantly enhanced the system’s without FACTS, and FACTS + ACO, under light
stability by reducing overshoot and improving settling operating conditions
Abbreviations: ACO: Ant colony optimization;
time, even under light operating conditions. In terms of FACTS: Flexible Alternating Current Transmission System.
overshoot, the ACO-FACTS system achieved the lowest
values, indicating better stability. For ∆ω, the overshoot For the base case, FACTS only, and FACTS-
reduced to 0.0144 pu with ACO-FACTS, compared to ACO, the generator’s disturbance caused a maximum
0.0169 pu in the base case and 0.0166 pu with FACTS overshoot of ∆ω that changed from 0.0169, 0.0166,
only. Similarly, the ∆δ overshoot decreased to -1.62 rad and 0.0144 pu, with settling times of 25, 9.45, and 3.16
with ACO-FACTS, which is lower than -2.01 in the s, respectively, as shown in Figure 11. In general, the
base case and -1.95 with FACTS only. δ also showed proposed system’s ∆ω exhibited better damping when
improvement, with the overshoot reducing to 1.87 in the compared to the base case and the FACTS-only device.
ACO-FACTS case, compared to 2.09 in the base case Even though the angle reached its normal value,
and 2.01 with FACTS only. the device became unstable when ∆δ was subjected
For settling time, the ACO-FACTS system again to a change, as this also exposed the active power to
demonstrated superior performance. The settling a change. The rotor angles for the base case and the
time for ∆ω decreased to 3.16 s with ACO-FACTS, a
significant improvement over 25 s in the base case and FACTS controllers with ACO are shown in Figure 12
9.45 s with FACTS only. Similarly, ∆δ and δ settled under light loading conditions.
faster with ACO-FACTS, achieving 3.02 s and 2.16 s, With the base case, FACTS only, and FACTS with
respectively, compared to the longer settling times in ACO, ∆δ were approximately 2.09, 2.01, and 1.87
the base and FACTS-only cases. rad, respectively. In general, the suggested system
These results confirm that the ACO-optimized FACTS exhibits improved damping behavior under light
controllers effectively enhance the power system’s loading conditions, enhancing power system stability.
performance during lighter operating conditions by The gain in power system stability is generally reduced
minimizing overshoot, improving settling time, and by a longer settling period. As a result, the simulation
providing better voltage regulation and oscillation findings show that the damping controllers can be fine-
damping, ultimately ensuring more stable and reliable tuned to demonstrate their superiority over the base case
system operation. system’s insufficient sizing.

Volume 22 Issue 2 (2025) 162 doi: 10.36922/ajwep.8393