Page 165 - AJWEP-v22i2

Enhanced renewable integration for power system stability

factor (VSF), leading to the placement of a STATCOM system’s weakest bus can also be identified using this
at bus 24 for voltage stabilization. In addition, as lines index.
4, 7, and 9 – connecting buses 3 to 4, 4 to 6, and 6 to
7 – experienced high active power variations due to the 5.1.3. Voltage Sensitivity Index
intermittent nature of renewable generation, a UPFC Many utilities employ sensitivity factors as indices to
was installed at bus 6 to regulate voltage magnitude identify voltage stability issues and develop appropriate
and phase angles, ensuring efficient power distribution solutions to correct the voltage. These indices generate
across the grid. This strategic deployment of FACTS QV curves to predict generator voltage control issues,
controllers helped maintain power system stability, which can be described as:
improved voltage profiles, and enhanced the reliability dv
of renewable energy integration into the IEEE-30 bus VSF = ; (IX)
i
network. dq
In this case, VSF is used. A high value of VSF that
5.1.1 L mn eventually changes sign is an indication of an “unstable”
L , a line stability metric, is based on the concept of voltage control state. A high level of sensitivity means
mn
power flow across a single line. The line index L can that even minor changes in loading can result in
mn
take a maximum value of 1 and a minimum value of 0. significant variations in voltage magnitude, signaling
L values near 1 indicate that a line is approaching its bus fragility.
mn
instability point. The origin of the L is given by:
mn
L 4 XQ r (VII) 5.2. Results of simulations under various loading
scenarios
mn
V s sin( 2 Examining the impact of the different loading conditions
)
on the system’s efficiency is important, as the operational
where V is the sending end voltage, Q is the load is constantly changing. The various power system

r
s
receiving end’s reactive power, X represents the line states, including speed deviation (∆ω), angle deviation,
reactance, and θ and δ correspond to the phase angles of and rotor angle, were utilized by the base case system,
the sending and receiving buses, respectively. FACTS devices, and FACTS with the ACO system. For
comparison, three distinct situations were taken into
5.1.2. Fast Stability Index account: normal, lighter, and heavy loading conditions.
The line stability index FVSI is based on the
understanding of power flow through a single line. The 5.2.1. Results from simulation under normal operating
stability index of the linked line is calculated using the conditions
following equation: To evaluate the effectiveness of the ACO-based
FACTS controllers compared to the base case system,
2
FSI = 4 ZQ r (VIII) a simulation under typical loading conditions was
VX conducted. According to the following data, the
2
s
FVSI values near 1 indicate that the line is oscillations in the base case system were unable to
approaching the point of instability. If the value exceeds dampen oscillations.
unity, the system will fail, and a sudden voltage drop Table 2 presents the power system states under
will occur in one of the buses connected to the line. The normal operating conditions, highlighting the impact

Table 2. Performance of the power system under typical operating conditions

Power system Overshoot Settling time (s)
states Base FACTS FACTS Base FACTS FACTS
case only with ACO case only with ACO
∆ω 0.0185 0.0181 0.0155 25 9.2 3.12
∆δ −2.014 −2.016 −1.83 25 11.15 2.98
δ 2.32 2.11 1.97 14 4.27 2.45
Notes: ∆ω: Speed deviation; ∆δ: Rotor angle deviation; δ: Voltage stability.
Abbreviations: ACO: Ant colony optimization; FACTS: Flexible Alternating Current Transmission System.

Volume 22 Issue 2 (2025) 159 doi: 10.36922/ajwep.8393