# Utilizing Energy Storage for Operational Adequacy of Wind-Integrated Bulk Power Systems
## 4 Application of the Proposed Operational Adequacy Framework  
The Roy Billinton Test System (RBTS) [28] is modified as shown in Figure 4 and used to demonstrate the application of the proposed evaluation framework. The generating units are numbered based on their priority loading order. The capacity rating of each generating unit and transmission line is shown in Figure 4, and Table 2 shows their failure rates and operating costs of generating units. The RBTS load model is only available at an hourly interval. The operational adequacy study requires data on theavailability of resources and system conditions at the time to carry out predictive assessment for the next day or week. The conditions, however, change continuously in sequence of time. The proposed method is illustrated using wind speed data and load data for a typical day in January to predict the operational adequacy for the next day. The load data simultaneously collected on 15 January at 15 min intervals by the Alberta Electric System Operator (AESO) [29], the European Network of Transmission System Operators for Electricity (ENTSO-E) [30] (Luxembourg and Germany), and the Independent System Operator (ISO) New England [31], and wind speed data collected by Sotavento Experimental Wind Farm [23], were used in this study to assess the next day operational adequacy of the test system. Operational adequacy studies should, however, be carried out continuously with data updated for the corresponding time stamps in the planning horizon. Figure 5 shows the chronological load profile used in the study for the different load busses and Figures 6 and 7 show historical wind speed profile and wind power probability distribution for two wind regimes obtained from the historical wind speed data. The first study uses the wind profile from Regime 1 to illustrate the negative impact of wind generation on the operating adequacy. The two wind regimes are used in a subsequent study to compare the impacts of different wind profiles. \begin{table}
\begin{tabular}{c c c c c} \hline \hline \multirow{2}{*}{**Generator ID**} & **Operating** & \(\lambda\) & **Trans. Line ID** & \(\lambda\) **(Failures/Year)** \\ \cline{3-5}  & **Costs (\$/MWh)** & **(Failures/Year)** & **L3** & **4** \\ \hline \(1,2\) & \(0.5\) & \(3\) & L1 & \(1.5\) \\ \(3,4\) & \(0.5\) & \(2.4\) & L6 & \(1.5\) \\ \(5,6,7,8\) & \(12\) & \(6\) & L2 & \(1.5\) \\ \(9\) & \(12.5\) & \(5\) & L7 & \(5\) \\ \(10\) & \(12.5\) & \(4\) & L4 & \(5\) \\ \(11,12\) & \(0.5\) & \(2.4\) & L5 & \(1\) \\ \(13,14\) & \(0.5\) & \(2\) & L8 & \(0.5\) \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Generation and transmission line data. Figure 4: Test system. A study was carried out to analyze the impact of wind integration and energy storage on the operational adequacy by applying the proposed method to three system configurations. Configuration 1 is the conventional system shown in Figure 4 without wind power and energy storage. Unit 5 at Bus 1 is replaced by an 80 MW wind farm at Bus 2 in Configuration 2. A 75 MWh ESS with a charge/discharge rate of 10 MW is added at Bus 2 of Configuration 2 to obtain Configuration 3. Figure 6 shows the wind speed profiles for 24 h for two wind regimes based upon historical wind speed data obtained from Reference [23]. Figure 7 shows the two wind power distributions in the first hour of that period. The wind data from Regime 1 in Figure 6 is used in this study. The operational adequacy of the test system was evaluated for a period of 24 h at a day-ahead planning horizon. The evaluation period was divided into 12 unit commitment periods (UCP) assuming lead times of 2 h for assistance from the ready-to-start standby units. The unit commitment is based on  
Figure 5: Load data used for different load points in per unit. Figure 6: Wind regime variation. Figure 7: Wind power distribution associated with different wind regimes at the start of the evaluation period. the N-1 criterion [32]. The unit commitment requires assigning a capacity value to the wind power in Configurations 2 and 3.