## 1 Introduction
The existing hydropower and photovoltaic power dispatching models mainly focus on how to improve the utilization capacity of photovoltaic power, but rarely pay attention to the conflict between interests and risks in the combined hydropower system, resulting in poor performance of the dispatching scheme. Hedging in economics refers to deliberately reducing the risk of another investment. It is a means of making profits in investment while reducing business risk. Generally, hedging refers to carrying out two kinds of transactions with relevance, different optimization directions, equal quantity, and equal increase and decrease at the same time. In the late 1940s, [PERSON] [18] first applied the hedging rule to the reservoir scheduling problem based on the time preference of reservoir storage and economic principles. He studied the reservoir scheduling problem based on the economic concept of marginal value of storage, and constructed the hedging theory of reservoirs. That is, the idea of storing some water in a reservoir in case of a significant loss of water scarcity in the future, by losing some of its current benefits. The key point of the reservoir hedging rule is to determine when to carry out the scheme of water supply and quantity limitation. Most of the current research is carried out from two aspects: numerical simulation and theoretical analysis. Most of the initial studies used numerical optimization methods [19] to integrate hedging rules into complex reservoir scheduling and took the minimum water shortage index as the goal, and used optimization algorithms to find the optimal rules. In recent years, according to the principle of marginal benefit in economics, many scholars theoretically studied the starting point, ending point, and hedging component of hedging, and obtained the quantitative analytical expression of hedging rules. [PERSON] [20] and [PERSON] [21] et al. substituted the uncertainty of reservoir inflow into the analysis of future marginal benefits and formulated the reser-voir operation scheme from two dimensions of numerical quantification and theoretical derivation. [PERSON] [22] applied the concept of hedging to reservoir flood control operation. The key of hedging for flood control operation is to adjust the final storage capacity of the period based on the forecast information and uncertainty in the future to balance the present and future risks, so as to minimize the risk of flood control. The interest hedging between flood control and power generation of reservoirs [23], the interest hedging between flood control and water supply [24], the interest hedging between multiple reservoirs, the interest hedging between multiple objectives of reservoir operation, the interest hedging considering historical decisions, and the optimization of hedging rules [25] are the focus of current scholars, which has built a theoretical basis for the research on multi-objective and multi interest conflicts of cascade reservoirs. The above related studies show that most of the initial studies on hydropower and photovoltaic joint scheduling focus on the establishment and solution of the scheduling model. With the deepening of the research, the multi-objective optimization algorithm is gradually maturing. However, the optimal scheduling problem of joint systems is a very complex scheduling problem. Firstly, the \"dimensionality disaster\" problem has not been effectively solved at present and there is no general solution method for joint scheduling [26]. Secondly, with the continuous improvement in the installed scale of new energy such as photovoltaic, the requirements for comprehensive benefits of hydropower stations in reservoirs are increasing and the conflicts of interests of various stakeholders are becoming more and more obvious.