## 4 Case Study
### IEEE RTS-24 Node Case Study System
#### 4.2.2 Planning Results under Different Scenarios  
In order to verify the advantages and disadvantages of the proposed method in this paper, the above example data are substituted into the single-step static transmission grid planning, single transmission grid planning, and the multi-stage collaborative planning model of the transmission grid and energy storage proposed in this paper, respectively. The planning results under different Cases are shown in Table 1, Table 2, and Table 3, respectively. The multi-stage planning scenarios obtained by the multi-stage collaborative planning model of transmission grid and energy storage are shown in Figure 4.  
From Table 1, it can be seen that in the single-step static collaborative planning scheme of transmission grid and energy storage, the construction of transmission lines and the location and capacity determination of energy storage are only carried out in the first planning stage, but the planning scheme is based on the grid-connected capacity and load demand of wind farms and photovoltaic power plants in the third stage. The single-step static collaborative planning scheme of transmission network and energy storage will result in \"over-investment\" of transmission lines and energy storage, that is, the amount of transmission line expansion and energy storage configuration far exceeds the transmission capacity demand corresponding to the current load. Therefore, the new construction of power grid lines and the location and capacity of energy storage of this scheme can fully absorb the wind power of the system when applied in the first stage. The cost of wind abandonment penalty is reduced to 0, and when applied in the second stage, the wind abandonment penalty is only 89 million yuan. \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline \multirow{2}{*}{**Stage**} & \multirow{2}{*}{\begin{tabular}{c} **Transmission Line Planning** \\ **Scheme: Corridor (Number of New Lines)** \\ \end{tabular} } & \begin{tabular}{c} **Energy Storage** \\ **Planning** \\ **Cost (\(\times 10^{8}\) CNY)** \\ \end{tabular} & \begin{tabular}{c} **Transmission** \\ **Line Investment Cost** \\ **(\(\times 10^{8}\) CNY)** \\ \end{tabular} & \begin{tabular}{c} **Energy Storage** \\ **Investment Cost** \\ **(\(\times 10^{8}\) CNY)** \\ \end{tabular} & \
\begin{tabular}{c} **Wind** \\ **Curaliment Cost** \\ **(\(\times 10^{8}\) CNY)** \\ \end{tabular} &
\begin{tabular}{c} **Solar** \\ **Curaliment Cost** \\ **(\(\times 10^{8}\) CNY)** \\ \end{tabular} \\ \hline \multirow{4}{*}{1} & 2-4(2), 2-6(1), 4-9(2), 7-8(2), 11-13(1), 12-23(2), 20-23(1), 20-23(1) & 13(63.76/264.80), 20(112.80/527.72), 23(76.11/361.53) & 21.47 & 5.38 & 0 & 0 \\  & - & - & - & 0.89 & 0 \\  & - & - & - & 3.41 & 0.13 \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Single-step static coordination planning scheme of the transmission network and energy storage and associated costs. \begin{table}
\begin{tabular}{c c c c c} \hline \hline \multirow{2}{*}{**Stage**} & \multirow{2}{*}{\begin{tabular}{c} **Transmission Line Planning Scheme:** \\ **Corridor (Number of New Lines)** \\ \end{tabular} } & \begin{tabular}{c} **Transmission Line** \\ **Investment Cost (\(\times 10^{8}\) CNY)** \\ \end{tabular} & \
\begin{tabular}{c} **Wind Curtailment Cost** \\ **(\(\times 10^{8}\) CNY)** \\ \end{tabular} &
\begin{tabular}{c} **Solar Curtailment Cost** \\ **(\(\times 10^{8}\) CNY)** \\ \end{tabular} \\ \hline \multirow{4}{*}{2} & 2-6(1), 7-8(1), 11-13(1) & 1.32 & 1.64 & 0.02 \\  & 2-4(1), 4-9(1), 7-8(1), 20-23(1) & 0.88 & 2.57 & 0.03 \\  & 2-4(1), 4-9(1), 10-12(1), 12-23(1), 13-23(1) & 2.80 & 13.69 & 0.69 \\  & Total Cost (Present Value) & 4.99 & 17.89 & 0.74 \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Single multi-stage transmission expansion planning and associated costs.