## 3 Overview and Development of the Proposed Test System Considered for the Study
### The Power Grid System Considered for the Study
#### 3.1.2 IEEE 9 Bus Power System Simulations  
**Initial load demand simulations for the power grid**  
An initial load demand was simulated for the power grid. Tables 9 and 10 show the active and reactive power of the loads and busbars under initial load conditions, while Table 11 shows the voltages on the busbars Bus1, Bus2, Bus3, Bus4, Bus5, and Bus6.  
We used tables to present these results because the time parameter is insignificant since no disturbances were simulated.  
**Increased load demand simulations for the power grid**  
An increase in load demand was simulated to identify the voltage stability collapse point, which might be any voltage outside the range of 0.9500 and 1.0500 per unit based on power system grid codes. The voltages were observed in this simulation for busbars Bus1 to Bus6 in response to the load demand increase in different loads DLoad1, DLoad2, and DLoad3. It was identified that the voltage at Bus2, where DLoad1 is connected, could not recover and, therefore, is critical. This is because it settled and fell to 0.9486 per unit, out of the range of 0.9500 and 1.0500 per unit. This behavior is when the load demand of DLoad1 was raised by 5.0000 MW and 1.9999 MVAr every 0.1 s, which in total ended up in the value of 160.0000 MW and 65.0535 MVAr.  
\begin{table}
\begin{tabular}{c c c} \hline \hline  & **Load Reactive Power (MVAr)** & **Busbar Reactive Power (MVAr)** \\ \hline DLoad1 \(|\) Bus2 & 50.0000 & 50.0000 \\ \hline DLoad2 \(|\) Bus3 & 30.0000 & 30.0000 \\ \hline DLoad3 \(|\) Bus45 & 35.0000 & 35.0000 \\ \hline \hline \end{tabular}
\end{table}
Table 10: Reactive power on load busbars and their loads under initial load demand for the power grid.  
\begin{table}
\begin{tabular}{c c c} \hline \hline  & **Load Reactive Power (MVAr)** & **Busbar Reactive Power (MVAr)** \\ \hline DLoad1 \(|\) Bus2 & 50.0000 & 50.0000 \\ \hline DLoad2 \(|\) Bus3 & 30.0000 & 30.0000 \\ \hline DLoad3 \(|\) Bus45 & 35.0000 & 35.0000 \\ \hline \hline \end{tabular}
\end{table}
Table 10: Reactive power on load busbars and their loads under initial load demand for the power grid.  
\begin{table}
\begin{tabular}{c c c} \hline \hline  & **Load Active Power (MW)** & **Busbar Active Power (MW)** \\ \hline DLoad1 \(|\) Bus2 & 125.0000 & 125.0000 \\ \hline DLoad2 \(|\) Bus3 & 90.0000 & 90.0000 \\ \hline DLoad3 \(|\) Bus5 & 100.0000 & 100.0000 \\ \hline \hline \end{tabular}
\end{table}
Table 9: Active power on load busbars and their loads under initial load demand for the power grid.  
Figure 16: Increased load demand simulations for the power grid: Active power demand by DLoad2 and active power at Bus3.  
Figure 17: Increased load demand simulations for the power grid: Reactive power demand by DLoad2 and reactive power at Bus3.  
Figure 19: Increased load demand simulations for the power grid: Reactive power demand by DLoad3 and reactive power at Bus5.  
Figure 18: Increased load demand simulations for the power grid: Active power demand by DLoad3 and active power at Bus5.  
Figure 21: Increased load demand simulations for the power grid: Bus2 voltage.  
Figure 20: Increased load demand simulations for the power grid: Bus1 voltage.  
Figure 23: Increased load demand simulations for the power grid: Bus4 voltage.  
Figure 22: Increased load demand simulations for the power grid: Bus3 voltage.  
In the simulation of the incremental load demand simulation performed above, we assessed the voltage stability thresholds and the compensation needed. This is how we studied the need to integrate the large-scale wind power plant (LSWPP) described below.  
Figure 24: Increased load demand simulations for the power grid: Bus5 voltage.  
Figure 25: Increased load demand simulations for the power grid: Bus6 voltage.