## 7 Case Studies
### Analysis of the Impact of Heat Storage Capacity on Cooperative Dispatch  
In order to analyze the impact of heat storage capacity on cooperative dispatch, the following case is set up for comparison with the proposed method.  
Case 1-1: adopt the exiting distributed cooperative dispatch method in [22], i.e., the heat storage capacity of DHN is not taken into account.  
Table 5 shows the comparison of the system cost of the proposed method and Case 1-1. Table 6 shows the comparison of curtailed energy for PV and WT of the proposed method and Case 1-1. Figure 6 shows the comparison of the water supply temperature of DHN of the proposed method and Case 1-1. Figure 7 shows the comparison of the heat generation power of DHN for the proposed method and Case 1-1. Figure 8 shows the comparison of curtailed power for PV and WT of the proposed method and Case 1-1.  
As seen in Table 5, compared to Case 1-1, the operation cost of DN of the proposed method is reduced by 18.1%, the operation cost of DHN is reduced by 2.0%, and the profitability of BESS is reduced by 52.5%, which ultimately results in a reduction of the total system cost by 10.2%. This is because the proposed method takes into account the heat storage capacity of DHN, which significantly increases the operational flexibility of the system. As shown in Figures 6 and 7, under the proposed method, DHN can flexibly adjust the water supply temperature to change the heat generation power. In the period when the output of PV and WT is large, DHN raises the water supply temperature to increase the heat generation power, which converts the electric energy of PV and WT that cannot be absorbed by DN into the heat energy of water and increases the heat storage capacity. In the period when the output of PV and WT is small, DHN reduces the heat generation power and utilizes the heat storage to provide the auxiliary power support, which achieves the effect of increasing the absorption capacity of DN for PV and WT. As shown in Figure 8,  
\begin{table}
\begin{tabular}{c c c} \hline \hline  & **Curtailed Energy for PV** & **Curtailed Energy for WT** \\  & **(kWh)** & **(kWh)** \\ \hline Proposed method & 1185.3 & 0 \\ Case 1-1 & 2349.6 & 0 \\ \hline \hline \end{tabular}
\end{table}
Table 6: Comparison of curtailed energy for PV and WT of the proposed method and Case 1-1.  
Figure 6: Comparison of the water supply temperature of DHN of the proposed method and Case 1-1.  
Figure 7: Comparison of the heat generation power of DHN of the proposed method and Case 1-1.  
the curtailed power for PV and WT of the proposed method is significantly smaller than that of Case 1-1 in several periods. So as shown in Table 6, the curtailed energy for PV of the proposed method is reduced by 1164.3 kWh compared to Case 1-1, and consequently the penalty cost for curtailment for PV and WT of the proposed method is reduced by 49.6% compared with that of Case 1-1.  
From the above analysis, it can be concluded that the proposed method considering the heat storage capacity of DHN can provide additional regulation capacity for DN by flexibly adjusting the water supply temperature of DHN, which in turn improves the absorption capacity of DN for PV and WT and then reduces the system operation cost.