Two-stage optimisation of hybrid solar power plants

Abstract

Hybrid solar power plants which combine concentrated solar power (CSP) and photovoltaic (PV) systems with thermal energy storage (TES) have the potential to provide cost competitive and dispatchable renewable energy. The integration of energy storage gives dispatchability to the variable renewable generation while the combination of different generation technologies can reduce the costs. However, the design of reliable and cost competitive hybrid solar power plants requires the careful balancing of trade-offs between financial and technical performance. This is made more complicated by the dependence on a larger number of parameters compared to conventional plants and due to the integration of TES which requires that the operational profile is optimised for every design. This contribution presents a two-stage, multi-objective optimisation framework which combines multi-objective linear programming methods for the operational optimisation with multi-objective genetic algorithms for the design optimisation. The operational optimisation which is performed for every design point needs to be performed with linear programming methods. Here an automated scalarisation method is developed for the linear programming method which enables the multi-objective optimisation of the operational profile. This enables the evaluation of the trade-offs between financial and technical performance in both the design and operational optimisation, which is required to design reliable and cost competitive sustainable energy systems. The two-stage multi-objective optimisation is applied to analyse and improve the design of the hybrid solar power plant Atacama-1. It is demonstrated that balancing the trade-off between financial and technical performance is key to increase the competitiveness of solar energy and that it is possible to simultaneously increase dispatchability and decrease the levelised cost of energy. This shows that the operational and design optimisations have to be directly linked in order to exploit the synergies of hybrid systems. Thus the optimisation framework presented in this study can improve the decision making in the design of hybrid solar power plants.

Long Term Impact of Grid Level Energy Storage on Renewable Energy Penetration and Emissions in the Chilean Electric System

“…This means that all the new CSP capacity added to the system have a solar multiple of 2.5, power block efficiencies of 37% and 17.5 h of thermal storage capacity. These values also agree with the optimal values found by Bravo et al [32].…”

Hybrid solar power plant with thermochemical energy storage: A multi-objective operational optimisation

“…In order to handle both objectives, and according to the results presented in [24], here a linear scalarisation method is implemented. The model developed in [24], which optimises the annual operation of a hybrid solar power plant with energy storage, found that the linear scalarisation method works faster than the epsilon ( ) constrain method, obtaining the same Pareto frontier. The only precaution is to choose a suitable scaling factor (ω) to scale the second objective (section 3.3 presents the analysis to define the value of ω for the case study described below).…”

“…In the simplified model shows in figure 1, the power flows to the inverter and then is dispatched to the grid. According the model described in [24], the total efficiency of the PV plant, from the solar irradiation to the electric power, considers the efficiency of panels and inverters, in addition with the losses related with module mismatch, connections and wiring.…”

“…In a future study, different regions will be analysed in order to compare key performance indicators under different solar resource and market features. For instance, if configuration G (with modifications in the solar field to keep fixed the total energy available) is analysed under the solar irradiation data corresponding to Atacama-1, a hybrid solar power plant located in Northern Chile [24], the LCOE drops to 137.8 USD M W h −1 and the LPSP reaches 0.1%. For the LPSP, by increasing any of the parameters shown in figure 3b, the energy dispatched to fulfil the commitment increases (and the LPSP decreases).…”

Self-Affine Analysis of ENSO in Solar Radiation

“…The variability of the solar irradiation in the Atacama Desert (northern Chile with a GHI of 3300 kWh/m 2 on latitude tilt surfaces [24]) is influenced by ENSO. These phenomena will result in years with significantly different solar irradiation than the TMY [25]. The solar radiation time series have characteristics associated with natural climatic phenomena, revealing that a reduction in solar radiation can be considered an indirect indicator of an ENSO period [26].…”