## 1 Introduction  
The acceleration of renewable energy penetration is an irresistible trend of a power system to reduce energy crises and environmental problems [1]. However, compared with traditional thermal units, the variability and uncertainty of renewable energy such as wind power and solar photovoltaic (PV) pose great challenges to power system operation. Under the circumstance that the power system lacks operational flexibility, utilization of the costly electricity storage [2] and employment of the large amount of scheduled reserves [3] are common solutions to reduce the uncertainty of wind power and PV power. These methods lack cost-effectiveness in accommodating large-scale renewable energy. In this light, the development of concentrating solar power (CSP) provides a new approach for renewable energy exploitability due to its dispatchability through using high-efficiency thermal energy storage (TES) [4]. [PERSON] et al. [5] and [PERSON] et al. [6] simulated a sole TES system and a two-tank indirect TES system respectively and analyzed the dynamic characteristics of TES to provide flexible thermal energy. A CSP station with TES collects direct normal irradiation (DNI) during the daytime by converting it into thermal power, which is partially stored in TES and generates electricity as needed. Even in the cloudy day or at night, large-capacity TES enables CSP station to shift solar energy between different days to satisfy the load demand [7; 8]. Besides, the capital cost of TES in a CSP station is $15/kWh, which is 1/10 of grid-connected electricity storage cost [9]. Furthermore, TES supports the coordinated operation between a CSP and electrical heater (EH). The incorporation of an EH enhances controllability of CSP to convert excess electricity in the power system into thermal energy for subsequent runs. In summary, the dispatchability of CSP with TES/EH would be an optimal choice to reduce renewable energy integration challenges and promote the power system to high renewables penetration. Currently, much research is absorbed in the optimized operation strategy of CSP station [10; 11] and economic benefit of a CSP station [12; 13]. Additionally, the majority of works incorporated the CSP model into an electricity market, and addressed the strategic operation of CSP to maximize market profits [14; 15]. With the increased CSP capacity, a CSP plant is definitely connected to the power system and receives the dispatching instructions. However, fewer studies analyzed the optimization of CSP operation from the perspective of the power system. [PERSON] et al. [16] considered capitalized cost of the renewable energy and the transmission line, and discussed the probability of 100% renewables-dominated power system involving a CSP station. [PERSON] et al. [17] established a scheduling model to minimize the operating costs, and analyzed the economic benefits bought by the flexibility of a CSP in the renewable-dominated power system, however, the aspect of grid infrastructure expansion was not considered, where a CSP could provide cost advantages compared to other intermittent renewable technologies. [PERSON] et al. [18] simulated a power system dispatching model with a CSP station to analyze the function of a CSP in reducing operating cost and renewables curtailment, however, the uncertainty of renewables was not considered. [PERSON] et al. [19] proposed a stochastic unit commitment (UC) and economic dispatch (ED) approach to evaluate the benefits of a CSP station for providing energy and extra reserve, but the results had geographical limitations and the simplified hypotheses needed further evaluation. From the power system perspective, the optimization of a CSP station operation would not only concentrate on the energy services to reduce the overall operating cost of power system and increase renewables penetration, but also pays attention to the additional value of a CSP station to produce reserve services. [PERSON] et al.