## 4 Example Analysis
In particular, DR participation eliminated additional wind curtailment penalty costs, resulting in a USD 6710 reduction in total cost, which shows that the flexible dispatch strategy and responsiveness of DR resources play an important role in wind power consumption and power balancing. The optimized outputs of thermal units significantly vary in the aforementioned three cases. Taking unit G1 as an example, Figure 12 shows the comparison of the output curves of G1 in the three cases. With the DR resource participating in system dispatch, the fluctuation of the G1 output is clearly smoothed. Additionally, the trend of the G1 output curve in the case where the wind farm is connected to the grid is similar to the case where the wind farm is not connected to the grid. In addition, the overall output of G1 is lower than the former due to wind power consumption. As can be found in Figure 13, the overall level of load decreases, and the curve flattens out after the DR resources participate in system dispatch. DR resources increase the load during the nighttime low-load period while decreasing the load during the daytime peak load period. Thus, the peak-to-valley difference of the system decreases. It can be seen that it plays an important role in relieving the pressure of peak load regulation of thermal units. After the wind power is integrated into the grid, DR resources can reduce the wind power curtailment caused by the anti-peak regulation characteristic. By orderly calling DR resources in 24 h, the sensitivity of its regulation can be used to increase more load to absorb wind power in the valley and reduce load to balance the peaking pressure of thermal power in peak hours. \begin{table}
\begin{tabular}{c c c c c} \hline \hline  & **Total Cost** & \begin{tabular}{c} **Thermal Unit** \\ **Operating Cost** \\ \end{tabular} & \
\begin{tabular}{c} **Wind Curtailment** \\ **Penalty Cost** \\ \end{tabular} &
\begin{tabular}{c} **Unit Startup/Shutdown** \\ **Cost** \\ \end{tabular} & **DR Cost** \\ \hline DRs participate & 96,322 & 89,013 & 6710 & 599 & 0 \\ DRs quit & 89,412 & 84,518 & 0 & 412 & 4842 \\ \hline \hline \end{tabular}
\end{table} 
Table 6: The impacts of DR participation on system dispatch cost (USD). Figure 11: The wind curtailment amount without DR participation in Case 3. In Figure 14, \(C_{t}\) represents the total cost, and \(C_{f}\), \(C_{ss}\) and \(C_{dr}\) are the costs of thermal units, startup and shutdown and DR, respectively. As shown in Figure 11, the costs of unit operating and startup/shutdown on the source side of the system were reduced because of the participation of DR and wind power. Figure 14: Comparison of the system operating costs in three cases. Figure 12: Outputs of G1 in three cases. Figure 13: Variation in daily system load curve. Compared to the case without DR participation, although DRs bring extra cost, the total cost is still reduced by 2.91% and 7.64% in Case 2 and Case 3, respectively, because of the greater reduction in the cost of thermal units. Overall, the total cost reduction is due to three main reasons as follows:  
* The flexible dispatch of DR resources reduces the cost due to the frequent startup and shutdown costs of thermal units. * The reduction in peak load decreases the pressure on peak load regulation of thermal units. * The improved wind power consumption level and the participation of DR resources reduce the high cost of wind curtailment penalty.