# Research on Robust Day-Ahead Dispatch Considering Primary Frequency Response of Wind Turbine
## 4 Results
### Cost Analysis  
The grid connection of large-scale wind power led to the shutdown of some conventional synchronous generator sets to meet the wind power accommodation. In this example, we use the wind power to replace the synchronous generator for a simulation. The capacity of the power loss is 20 MW, the initial frequency of the system is 50 Hz, and the economic dispatch results are shown in Table 1.  
From Table 1, we can see that the key scene set screened through the iteration is [6;49]. At this time, the dispatch cost increases dramatically after considering the PFR in the large-scale wind integrated power system, especially for the cost of the primary reserve or the shedding load. Since the uncertainty in the wind power scene set [6;49] is considered in all three cases, the day-ahead dispatch costs are basically the same under the same condition, including the cost of the unit output and the reserve cost for the power imbalance retained for the wind power prediction error. For the remaining real-time operating costs, the classification is as follows:  
The three states in Figure 5 correspond to the three situations in Table 1, respectively. In Figure 5, we find that the adjustment costs of the unit output are the same in the different states in the real-time operation. The real-time unit output adjustment is not only related to the error between the wind power prediction and actual operation, but also to the primary response. Therefore, it is necessary to consider both the cost of unit output adjustment and that of the primary reserve. The actual operating cost changes when we consider the failure of the unit. Figure 5 shows that the impact of the frequency response of the wind power on the primary reserve is demonstrated in the following way: without the frequency response, the total cost stands at 132,257$; when wind power is involved in the frequency response process, the cost will be 132,036$, which is related to the cost coefficient of the wind power primary reserve.  
In fact, under certain circumstances, the output of the unit might drop, and load shedding might occur in real-time operation. Figure 6 depicts the classification of the real-time operating costs, including the load shedding cost.  
\begin{table}
\begin{tabular}{c c c c} \hline \hline \multirow{2}{*}{**Key Subset \(\Omega_{m}\)**} & \multicolumn{3}{c}{**Cost/\$**} \\ \cline{2-4}  & **Without Primary** & **PFR not Involving the** & **PFR Involving the** \\  & **Reserve** & **Wind Power** & **Wind Power** \\ \hline
[6;49] & 5,375,256 & 5,508,326 & 5,508,085 \\ \hline \hline \end{tabular}
\end{table}
Table 1: Dispatch costs in different situations; PFR: primary frequency response.  
Figure 5: Classification of real-time operating costs.  
Figure 6 demonstrates the adjustment cost of applying a real-time operation strategy on a day-ahead basis, in view of the actual output of the wind power. From this figure, we can see that the load shedding cost is relatively high in the real-time operation. Although the load shedding ensures that we can obtain the new optimal solution of the real-time operation strategy through optimization on the basis of the day-ahead dispatch strategy, in view of the great impact it has on the user experience and economic cost, the system dispatcher should avoid sacrificing the user experience to ensure an ample primary reserve. In fact, to avoid using the load shedding as a method of adjustment, a higher load shedding cost is set in this study; so we find a lower load shedding in Figure 6.