## 5 Simulation Analysis
### Optimization Result Analysis  
* Analysis of the weak Stackelberg equilibrium solution  
Based on the above conditions, the weak Stackelberg equilibrium of the game is obtained as shown in Figure 5. The payoffs of the RE company and BSS at the weak Stackelberg equilibrium are V276,480 and V58,671, respectively. When RE company adopts the strategy at the weak Stackelberg equilibrium point, no matter what kind of rational strategy BSS adopts, the income of RE company  
Figure 4: Price of electricity purchased by the distribution company. Figure 3: Prediction of wind power and photovoltaic power. will not be lower than Y276,480. Therefore, the weak Stackelberg equilibrium solution is a conservative decision for the RE company, and the payoff at the equilibrium point is the minimum of its payoff. Comparing Figures 4 and 5, it can be seen that the changing trend of charge/discharge price is basically consistent with that of the RE purchase price of the distribution company. During periods of low purchase price of distribution company, such as period 0-6, the RE company sets a low charge/discharge price, and directs the BSS to charge and to store power. During the period of high purchase price of the distribution company, such as period 20-21, the RE company sets a high charge/discharge price to attract BSS to discharge, so as to increase the revenue of electricity sale of the RE company. Table 2 compares the revenue of RE and BSS under the cooperative and non-cooperative models. In the non-cooperative mode, BSS buys electricity directly from the distribution network company in accordance with the contract price \(\rho_{\text{DC}}\), and does not consider the sale of electricity to the power grid by BSS. As shown in Table 2, compared to the case of non-cooperation, in the game model proposed in this paper, the revenue of both RE and BSS has increased. Therefore, both of them have the motive of cooperation. The average charge/discharge price constraint could realize the redistribution of the total revenue and prevent the RE company from using its first-mover advantage to encroach on the reasonable income of BSS. In Table 3, as the average charge/discharge price \(\overline{\rho}\) declines, revenue of the RE company continues to decrease, while BSS's revenue continues to increase. It can be predicted that with the continuous decline of \(\overline{\rho}\), when the revenue of RE is less than \(\forall\)252,054 (its revenue under the non-cooperative mode given in Table 2), the RE company will not have the motivation to participate in the game. Similarly, with the increasing of \(\overline{\rho}\), when the revenue of BSS is less than \(\forall\)58,671 (its revenue under the non-cooperative mode given in Table 2), BSS will not have the motivation to participate in the cooperation. Therefore, the introduction of average charge/discharge price constraint is necessary and effective. \(\overline{\rho}\) should be reasonably set to mobilize the enthusiasm of both sides of the game. \(\bullet\) Sensitivity analysis of the reserve ratio \(\alpha\) of battery swapping demand  
Considering the randomness of the battery-swapping demand, it is necessary to retain a certain reserve to avoid the curtailment of EV users' demand. Table 4 shows the revenue of the RE company and BSS at different reserve levels. With the increase of \(\alpha\), the revenue of both sides decrease. This can be explained as the available capacity of the BSS decreases at a high demand-reserve level, since the BSS needs more fully charged batteries to meet a possible additional battery-swapping demand. In Figure 6, we compare the remaining energy of the BSS when \(\alpha\) is 5% and 25%. When \(\alpha\) is 25%, the remaining energy of the BSS is higher in each period of time, which indicates that the BSS has prepared more backup batteries to satisfy the battery-swapping demand. During the high charge/discharge price periods, such as time intervals 8-10, BSS is unable to sell more energy to the RE company to raise income.