## 3 Case Study
### Optimization Results  
After running the program 20 times, the deviation in the optimization result was less than 0.5% of the iterations, which met the calculation requirements. The optimization results of the evaluation index and equipment capacity under the three operational strategies are shown in Tables 3 and 4. The CEI of HOS was 0.05 to 0.07 higher than those of FEL and FTL. The annual total cost and carbon dioxide emissions of HOS were lower than those of FEL and FTL. The energy efficiency of the DES-HOS was more than 0.8 higher than those of FEL and FTL. The reason for this was that the DES using HOS operates according to the most reasonable energy scheme for different load characteristics. As shown in Table 4, the equipment capacity of the DES-HOS was not the highest or lowest, proving that the optimal equipment configuration of the DES is based on a reasonable operational strategy. In addition, in order to intuitively compare the operational efficiency of the DES under different operational strategies, the process of energy flow with different operational strategies in the optimization process was recorded, which included the conversion of energy among multiple devices and the loss in the process of operation of the DES. A Sankey diagram of energy flow is shown in Figure 9. It can be observed from the Sankey diagram of energy flow that the energy demand for grid power and natural gas was 9717 kW, which is about 13.2% less than those of FEL and FTL when HOS was implemented. Moreover, the \begin{table}
\begin{tabular}{c c c c c c} \hline
**Operational** & **GT (kW)** & **ER (kW)** & **GB (kW)** & **HRSG** (kW)** & **ARU (kW)** & **HE (kW)** \\ \hline HOS & 643 & 1334 & 2159 & 1922 & 2189 & 1762 \\ FEL & 704 & 1112 & 1865 & 2154 & 2320 & 1966 \\ FTL & 603 & 1224 & 2112 & 1789 & 1974 & 1523 \\ \hline \end{tabular}
\end{table} 
Table 4: The equipment capacity optimization results of three operational strategies. Figure 8: Typical daily load of the power load in the summer (**a**) and in the winter (**b**) at the \(\theta\) of \(-\)0.05, 0, 0.05, and 0.1. \begin{table}
\begin{tabular}{c c c c c} \hline
**Operational** & **CEI** & **ATC (Yuan)** & **CE (t)** & **EE** \\
**Strategy** & **CEI** & **ATC (Yuan)** & **CE (t)** & **EE** \\ \hline HOS & 0.151 & 3.22 \(\times\) 10\({}^{6}\) & 3854 & 0.83 \\ FEL & 0.103 & 3.39 \(\times\) 10\({}^{6}\) & 4056 & 0.79 \\ FTL & 0.076 & 3.42 \(\times\) 10\({}^{6}\) & 4112 & 0.77 \\ \hline \end{tabular}
\end{table} 
Table 3: The evaluation index optimization results of three operational strategies. energy waste of the DES-HOS was 1879 kW, which was 19.7% and 15.5% lower than those of FEL and FTL, respectively. Therefore, it was found that the HOS can reduce the energy consumption and waste of the DES under the same building load. The 100 sets of discrete loads with a \(\theta\) from \(-\)0.06 to 0.11 and their typical daily loads were input into the algorithm for the optimization of the DES-HOS. The scatters and fitting lines of the ATC, CE, EE, and CEI are shown in Figure 10. The annual total cost of the DES optimized based on annual hourly load was 4.7% to 6.2% less than that of a typical daily load (Figure 10a). The annual operational cost of the DES-HOS increased by 3.4% and 6.5% as the \(\theta\) increased from \(-\)0.05 to 0.1, respectively. The increase in grid power consumption was the main reason for the increase in the annual operational cost of the DES-HOS. Figure 10b shows that the carbon emissions of the DES optimized base on annual hourly load were 8.7% to 12.5% less than the typical daily load. The energy efficiency of the DES optimized base on annual hourly load was 2.5% to 4.7% higher than the typical daily load (Figure 10c). As \(\theta\) increased from \(-\)0.05 to 0.1, the energy efficiency of the DES decreased by 2.1% and 5.3%, respectively. Figure 10d shows that the CEI of the DES-HOS based on annual hourly load was 4.7% to 6.2% less than the typical daily load.