## 6 Conclusions  
A CSP station turns out to be a dispatchable resource owing to the employment of the large-capacity TES and rapid response EH equipment. In this paper, a CSP is incorporated into a chance-constrained stochastic unit commitment model considering the economic and reliability criterion. The validity of  
Figure 9: CSP and system reserve planning results at stochastic scenario 3, including: (**a**) the total scheduled system up reserves in Strategy 3 and Strategy 6; (**b**) the total scheduled system down reserves in Strategy 3 and Strategy 6.  
the proposed model and the functions of the CSP and EH to provide energy and reserve services are tested in the IEEE reliability system.  
Several conclusions are drawn as follows:  
1. In the large-capacity renewables penetration system, the utilization of a TES and an EH could reduce the generation costs of thermal units and penalty costs for renewables spillage. The higher ramp rate and range of the CSP than thermal units support it to provide large scale of firm capacity. The reduced requirement of thermal units allows for greater renewables penetration. The EH enables the CSP to convert excess renewables generation into thermal units stored in TES for later use, which further utilizes the room of the TES system and reduces the renewables spillage significantly. The dispatchable CSP station with TES and EH makes a 100% renewable-dominated power system possible.
2. The reserve services provided by the CSP system with TES and EH could help decline the reserve costs. The capacity of CSP reserves mainly provides the reserve scheduling services through replacing expansive thermal unit reserves. The incorporation of an EH alleviates the renewables uncertainty to avoid unpredicted thermal unit reserve deployment.
3. In particular, the TES produces additional value by realizing the solar power shift to the periods of reduced power output and between different days. The complementary effects of solar-driven power CSP and PV stations enable greater use of solar energy especially in the high solar power penetrated power system.
4. Compared with a conventional reserve planning model, the proposed chance-constrained reserve scheduling has both economic value and reliable significance. The severe consequences of load shedding are greatly hedged in the proposed reserve planning method.  
However, there were some limitations in this study. Firstly, the transmission expansion planning model was not considered in the stochastic unit commitment scheduling. In addition, the double-bounded property of wind power and PV power should be considered and the distribution function to describe limited variables like Beta distribution could be a more reasonable choice. Finally, we expect that the application of the proposed simulation framework into long-term planning could be carried out in a further study.  
Conceptualization, S.G., Y.Z. and Y.L.; Data curation, S.G.; Formal analysis, Y.L.; Investigation, Y.Z.; Methodology, Y.Z.; Project administration, S.G.; Resources, S.G.; Software, Y.Z.; Supervision, S.G. and Y.L.; Validation, S.G., Y.Z. and Y.L.; Visualization, Y.Z.; Writing--original draft, Y.Z.; Writing--review and editing, S.G. and Y.L.  
This research was supported by \"the Fundamental Research Funds for the Central Universities\" in China.  
The authors declare no conflict of interest.