## 4 Case Study
### Results and Analysis  
#### 4.2.1 Impact of Energy Storage Equipment and Electric Energy Substitution on RIES  
In order to compare and analyze the effect of the energy storage equipment on the RIES and the impact of electric energy substitution on energy storage system configuration, the following three scenarios are set. Scenario 1: The RIES contains no energy storage systems;  
Scenario 2: The RIES contains no P2G and EB (no electric energy substitution strategy);  
Scenario 3: The RIES contains energy storage systems, P2G and EB. As can be seen from the above analysis in Section 2, the power balance equation in each scenario can be described as:  
Scenario 1: \(L+\mathbf{P}_{\text{P2G,EB}}=\mathbf{C}(\mathbf{P}^{\text{net}}+\mathbf{P}_{\text{WT,PV}})\);  
Scenario 2: \(L=\mathbf{C}(\mathbf{P}^{\text{net}}+\mathbf{P}_{\text{WT,PV}})-\mathbf{P}_{\text{ch}}+\mathbf{P}_{ \text{dis}}\);  
Scenario 3: \(L+\mathbf{P}_{\text{P2G,EB}}=\mathbf{C}(\mathbf{P}^{\text{net}}+\mathbf{P}_{\text{WT,PV}})-\mathbf{ P}_{\text{ch}}+\mathbf{P}_{\text{dis}}\). In this paper, the Yalmip toolbox was used to model the model, and the Gurobi solver was called to solve the model. Before Gurobi starts to solve the problem, there is a pre-solve process for the model This process is a branch and bound process in which the solution search space of this model is greatly reduced. Solution results were as follows: Yalmip modeling time was 1.7064s, iteration number was 25, and solution time was 0.2006s. The configuration results solved by [PERSON] in both off-grid mode and grid-connected mode are shown in Table 4. The costs of the RIES in different scenarios are shown in Table 5.  
As shown in Tables 4 and 5, in the off-grid mode, the electric-gas-thermal energy storage systems were added in scenario 3 compared with scenario 1. Although the energy storage configuration cost was added, the system operation cost was greatly reduced. The total costs were reduced from 2902 yuan \begin{table}
\begin{tabular}{c c c c c c c c} \hline  & & \multicolumn{2}{c}{**EES**} & \multicolumn{2}{c}{**TES**} & \multicolumn{2}{c}{**GES**} \\ \cline{3-8}  & & \(\mathbf{C^{1}/k\text{W}\cdot h}\) & \(\mathbf{P^{2}/k\text{W}}\) & \(\mathbf{C/k\text{W}\cdot h}\) & \(\mathbf{P/k\text{W}}\) & \(\mathbf{C/k\text{W}\cdot h}\) & \(\mathbf{P/k\text{W}}\) \\ \hline \multirow{3}{*}{Off-grid} & Seen.31 & - & - & - & - & - & - \\  & Seen.2 & 363.58 & 125.84 & 484.77 & 86.85 & 121.45 & 53.56 \\  & Seen.3 & 284.70 & 96.49 & 145.98 & 37.8 & 80.1 & 33.96 \\  & Seen.1 & - & - & - & - & - & - \\ Grid-connected & Seen.2 & 109.04 & 47.14 & 189.47 & 76.25 & 63.1 & 21.2 \\  & Seen.3 & 68.07 & 37.01 & 86.17 & 35.98 & 30.5 & 12.6 \\ \hline \end{tabular}  
* Capacity; 2 Power; 3 Scenario.  
\end{table} 
Table 4: The configuration results. Figure 3: Load forecasting curve. in scenario 1 to 2454 yuan in scenario 3, down 15.4%, while the cost of purchasing natural gas decreased by 4%, and the rate of abandoned wind power reduced from 4.02% to 0. A similar conclusion can be drawn in the grid-connected mode. The results of comparing scene 2 with scene 1 illustrates the conclusion that the energy storage systems can improve the economic benefits of the RIES. As shown in Tables 4 and 5, in the off-grid mode, there were no P2G or EB devices in scenario 2 compared with scenario 3, where lot of wind power was abandoned. Due to the electric energy substitution strategy in scenario 3, where the surplus electricity was converted into natural gas and heat by P2G and EB equipment during the period of abandoning wind power, the costs of abandoned wind power was thus reduced. Moreover, the total costs were reduced by 45.3% compared with scenario 2, with a 30.4% reduction in the cost of purchasing natural gas, and the cost of energy storage configuration was also reduced. The conclusion that the P2G and EB equipment can reduce energy storage systems configuration costs and significantly improve the economics of the RIES has been obviously drawn according to the results of comparing scene 3 with scene 2.