## 4 Results and Analysis
Figure 13 shows the comparison chart of the output process of the joint system corresponding to the traditional mode and hedging strategy under the typical scenarios of sunny and cloudy days. Figure 12: Pareto frontier of the scheduling scheme considering system output volatility. (**a**) Pareto frontier under three objectives. (**b**) Pareto frontier under two objectives. Figure 13: The output of the hydropower, photovoltaic, and joint system under a compromise solution. (**a**) Traditional solution for typical sunny day scenarios. (**b**) Hedging solution for typical sunny day scenarios. (**c**) Traditional solution for typical cloudy day scenarios. (**d**) Hedging solution for typical cloudy day scenarios. As can be seen from Figure 13a,c, the traditional compromise optimization scheme under the typical sunny and cloudy scenarios is a compromise optimization in the Pareto solution set and the conflict problem is not optimized. Under the condition of full PV processing, the peak valley difference under the typical sunny scenario is 114,440 kW and the peak valley difference under the typical cloudy scenario is 161,010 kW. The main reason for the increase in the peak valley difference between cloudy and sunny days is the instability of photovoltaic output, which requires more regulation ability of other power generation types in the grid. The multi-objective hedging dispatching scheme proposed in this paper ensures the stability of water-light bundling power generation by making full use of the regulation capacity of the reservoir on the premise that downstream flood control is acceptable, storing water in the common storage capacity, and increasing hydropower output during 0-7 h and 20-24 h PV low-output periods. When photovoltaic output increases in 8 to 19 h, photovoltaic power generation is mainly consumed and hydropower output is reduced by water storage in the reservoir, so that the peak-valley difference of the combined system is low. The results are consistent under sunny and cloudy weather scenarios, as shown in Figure 13b,d. In order to further analyze the advantages of the hedging model proposed in this paper, the output extremum and peak valley difference of the hydropower photovoltaic joint system under typical scenarios of sunny and cloudy days are compared, as shown in Figure 14.  
Figure 14a,b shows the peak valley difference of the output of the joint system corresponding to the traditional multi-objective compromise decision-making scheme and the decision-making scheme under the hedging mechanism in the typical scenarios of sunny and cloudy days, respectively. It can be seen that the optimal dispatching model considering multi-objective hedging makes full use of the regulation and storage function of the reservoir and effectively reduces the peak valley difference of the output of the combined system, and the joint output curve of hydropower and photovoltaic power is more stable, which is of positive significance for the traditional uncertain photovoltaic grid connection consumption. Table 4 shows the results of the peak valley difference of output of the combined system under the two schemes. Figure 14: The comparison of hydropower and photovoltaic joint output’s volatility under the two schemes. (**a**) Comparison of peak valley difference between the traditional methods and hedging strategies in typical sunny day scenarios (**b**) Comparison of peak valley difference between the traditional methods and hedging strategies in typical cloudy day scenarios. It can be seen from the above table that the output of the hydropower photovoltaic combined system in the traditional scheme under the typical sunny day scenario is 5,004,670 kW and the output of the hydropower photovoltaic combined system with hedging is 4,979,970 kW. However, the peak valley difference of the system under the hedging scheme is 50.67% lower than that under the traditional scheme.