# Game Approach to HDR-TS-PV Hybrid Power System Dispatching
## 5 Discussion  
Further analysis of payoff and extra profits was carried out to reveal the role of the players in the hybrid power system and the source of the extra profits. It can be seen from Table 2 that under the _TOU_ price given in Figure 3, the arbitrage operation of the _TS_ power station cannot be profitable due to the low power generation efficiency of the _ORC_ generator. As a result, the _TS_ power station can only benefit by abandoning heat and electricity with zero marginal cost through cooperating with _HDR_ power station or _PV_ plant. Therefore, its dispatching strategy is to always adopt a minimum generation operation in low TOU price periods and _PV_ generation periods in order to store as much as possible the waste heat and surplus power, as shown in Figure 7. It can be seen from the  
Figure 11: The extra profits allocation of _HDR-TS-PV_ coalition. actual operation shown in Figure 6 that under this operating strategy, the _TS_ power station can play a peak shaving role by storing geothermal energy, which realizes its payoff and makes the geothermal energy mainly generated in high TOU price periods, thereby creating extra profits. Simultaneously, the _TS_ power station can recover the waste heat of the _HDR_ power station when the down reserve is provided to the _PV_ plant, further improving the system profits. As can be seen from the allocation results in Table 4, the extra profits of the _TS_ power station accounted for 50.04% of the total extra profits. This result further shows that the _TS_ power station has the most considerable marginal contribution to the extra profits, reflecting the decisive role of the _TS_ power station in the game relationship. Due to its operating characteristics, the _HDR_ power station cannot cooperate with the _PV_ plant without abandoning heat, so it cannot provide auxiliary services for the _PV_ plant alone. Since the _TS_ power station can directly store geothermal energy, it can help the _HDR_ power station realize arbitrage. Table 3 shows that when the _HDR_ power station and the _TS_ power station cooperate, the payoff of the _HDR_-_TS_ coalition increases by 8.04% relative to the non-cooperation operation, and the overall payoff of the grand coalition only increases by 1.95% relative to the _HDR_-_TS_ coalition when the _PV_ plant joins. The extra profits in Table 4 show that the _HDR_ power station is allocated 42.02% of the overall extra profits. This result shows that the increased profits of the hybrid power system in the cooperative game mainly come from the peak shaving arbitrage of geothermal energy. Figures 10 and 11 also show that the _HDR_ power station is not affected by grid parameters \(\sigma\) and \(p\), which further clarifies that the payoff and extra profits of the _HDR_ power station mainly come from its geothermal energy. Table 3 shows that when the _PV_ plant and the _TS_ power station cooperate, the overall payoff of the hybrid system only increased by 1.12%. In the grand coalition, the extra profits of the _PV_ plant accounted for only 7.94%. It can be seen that the contribution of the _PV_ plant to the extra profits of the hybrid system is small. The main interest of _PV_ plants participating in the coordinated dispatch of the hybrid power system is to increase the credible capacity and reduce the impact on the grid so as to obtain the priority of grid connection. This result is also reflected in Figures 10 and 11. The increase in the allowed fluctuation rate and the penalty coefficient decrease indicates that the grid's ability to absorb fluctuating power has increased. A strong power grid increases the non-cooperative payoff of the _PV_ plant and decreases the cooperative extra profits, thereby reducing the willingness of the _PV_ plant to cooperate. Moreover, since the temperature of the geothermal reservoir is a critical parameter that restricts the operating performance of the _HDR_ power station, we conducted a preliminary simulation on the influence of the temperature change on the overall payoff of the hybrid power system.