## 6 Simulation Analysis
### Results Analysis  
The above analysis has already demonstrated the influences of different ESD modes on MECS operation. To prove the optimization effect of the ESD on MECS operation, the MECS was scheduled without the ESD to comparatively analyze the results of different operation scenarios. The comparative analysis index encompassed the objective function values, the pollutant emissions, the complementarity indexes, and the load demand curve. Table 5 shows the comparative results of MECS scheduling under different operation scenarios. \begin{table}
\begin{tabular}{c c c c c c c c c c c c c} \hline \hline \multirow{2}{*}{**Mode**} & \multicolumn{8}{c}{**Power Output/MW-h**} & \multicolumn{8}{c}{**Abandoned Energy/MW-h**} \\ \cline{2-11}  & **TPP1** & **TPP2** & **TPP3** & **TPP4** & **WPP** & **PVV** & **HS** & **ESD** & **WPP** & **PV** & **HS** \\ \hline \multirow{2}{*}{Summer} & OEE & 15,000 & 3288 & 550 & 0 & 6837 & 2474 & 12,322 & \(\pm 1305\) & 749.20 & 274.90 & 0 \\  & LLC & 15,000 & 3164 & 693 & 200 & 6793 & 2419 & 12,271 & \(\pm 1100\) & 899.04 & 329.88 & 50.85 \\ \hline \multirow{2}{*}{Winter} & OEE & 15,000 & 5000 & 400 & 0 & 12,654 & 2044 & 5658 & \(\pm 1853\) & 1336.9 & 227.1 & 0 \\  & LLC & 15,000 & 5368 & 400 & 0 & 12,387 & 1999 & 5658 & \(\pm 1200\) & 1604.28 & 272.52 & 0 \\ \hline \hline \end{tabular}
\end{table} 
Table 4: The power output results of MECS scheduling on a typical day. ESD: energy storage device; HS: hydropower station. Figure 12: The power output structure of MECS scheduling under the OEE mode: (**a**) summer and (**b**) winter. When the MECS was scheduled without the ESD, the values of all objective functions worsened. For example, in the LLC mode, the value of F1 decreased by 43.1 thousand V on a typical summer day, and by 47.7 thousand V on a typical winter day, compared with the corresponding values in the OEE mode. In the OEE mode, the value of F3 increased by 3.78 MW on a typical summer day and by 1.52 MW on a typical winter day, compared with the corresponding values in the LLC mode. The outputs of WPP and PV decreased without ESD, as the load demand had to be partly satisfied by thermal power units. Therefore, pollution emissions increased significantly. For example, the total CO2 emission increased by 378 tons and by 189 tons on two typical days, compared with the values in the LLC mode. Consequently, the values of the complementarity indexes also worsened. The LTD reached its lowest value, i.e., 30%, and the SPC and UCC reached their highest values, i.e., 26.17 MW\(\cdot\)h and 329.9 g/kW\(\cdot\)h. Figure 13 shows the scheduling results of the MECS operation without the ESD on a typical day. According to Figure 13, when ESD was not considered, TPP4 was used to provide a reserve service on a typical summer day and part-time service on a typical winter day. TPP3 was also scheduled for full-time load demand satisfaction, and part-time reserve service. For example, TPP3 was scheduled with a power output of 199 MW\(\cdot\)h from 3:00 h to 5:00 h as a reserve service. Moreover, the abandoned power outputs of WPP and PV were 1123.8 MW\(\cdot\)h and 412.35 MW\(\cdot\)h, respectively, on a typical summer day and 2005.35 MW\(\cdot\)h and 340.65 MW\(\cdot\)h on a typical winter day. Thus, the total power generation cost reached 6148.47 tce and 6442.46 tce on the two typical days, respectively. Obviously, the power output structure without the ESD was worse than that with the ESD. Figure 14 shows the net output curve of the thermal power units under different operational strategies. It can be seen that as the ESD charges when load demand is low and discharges when load demand is high, the load demand curve is smoother. Combined with Table 5, if the ESD is not considered, the peak-valley ratio of the net load demand (thermal power out) curve reached the highest value of 2.24 on a typical summer day, and 1.37 on a typical winter day.