Optimal wind and solar sizing in a novel hybrid power system incorporating concentrating solar power and considering ultra-high voltage transmission

The coordinated operation of concentrating solar power (CSP) and traditional thermal power can facilitate the integration of variable wind and solar renewable energy (VRE) into the grid supported by ultra-high voltage (UHV) transmission line, forming a novel HRES. The optimal sizing of VRE in this novel HRES has been rarely investigated. This paper thus proposed a framework serving the capacity configuration optimization for VRE in aforementioned HRES. The lifecycle economic and technical performance of the HRES was evaluated to guide capacity planning. The operational characteristics of the thermal power and CSP were investigated via short-term scheduling optimization. The methodology was applied to a HRES base located in Qinghai Province, China. Results indicate a maximum capacity ratio of VRE to flexible power of 1.74:1 without power curtailments. Further expansion of VRE leads to an escalation in power curtailments. The optimal VRE sizing is determined as a combination of 4000 MW solar power and 1000 MW wind power, which achieves a levelized cost of energy as low as 0.363 CNY/kWh, corresponding to a capacity factor of 0.32. The role of CSP in mitigating VRE fluctuations in HRES is more significant than that of thermal power due to its superior flexibility and low operating costs. The inter-day heat transfer of CSP can further facilitate the stability of the HRES output between consecutive days. These findings provide valuable insights for capacity configuration and operation of the new HRES, which will promote the utilization of renewable energy and cleaner production of the power system.