Optimal Design Of Thermal Energy Storage Capacity Of CSP For Wind-Photovoltaic-Thermal Power System

Its volatility and intermittent nature make the grid peaking is one of the difficulties in safe and reliable operation of the power grid with the large-scale grid connection of renewable energy such as wind power and photovoltaic power generation.Concentrating solar power(CSP)is an emerging form of large-scale utilization of solar energy.Its thermal energy storage(TES)system has a good regulation effect on the output characteristics of CSP stations.By adjusting the output of the CSP can effectively alleviate the problem of grid peaking caused by the grid connection of renewable energy when the combined system formed by CSP stations,wind turbines,photovoltaic plants and thermal power units.On the one hand,the TES of CSP can alleviate the phemomenon of abanding the power from renewable energy by storing part of the thermal energy during the peak period of the renewable energy output.On the other hand,the TES can alleviate the phemomenon of cutting load by releasing thermal energy and incresing output during the period of low output of renewable energy.Therefore,it's the key factor to improve the penetration of renewable energy power,reduce the difference of power system peak-to-valley and the cost of the combined system by rational allocationing the capacity of the thermal energy system of CSP stations.In this context,a multi-objective robust optimization configuration method for the capacity of thermal storage system in CSP station is proposed considering the uncertainty of wind power,photovoltaic output and grid loadFirstly,the composition of CSP station and the working mechanism of different types of TES systems in the CSP station are introduced.Five working modes of the operation of the CSP station are proposed according to different working conditions.The analysis the output characteristics of different types of power generations is carried out according to the operating mechanism of the power generation equipment in the combined system.The principle of multi-energy complementary operation in the combined system is proposed based on the two angles of energy balance and climbing rate matching.Then,the robust optimization theory is introduced,and the uncertainty of wind power,photovoltaic output and load demand is described in the form of robust interval.A robust optimal configuration model for the TES capacity of the CSP under multi-objective conditions is established with the optimization objectives of minimizing the cost of the combined system and maximizing the penetration of renewable energy and the restrictions of power balance and operating constraints of thermal power units and CSP stations.Finally,the robust transformation algorithm is used to transform the uncertain optimization problem into a deterministic optimization problem,and the improved NSGA-? is used to solve the problem.Taking a certain place in northwest China as an example,the established model and the adopted algorithm are verified.The optimization results show that the output of the combined system can be adjusted through the TES,which can effectively alleviate the phenomenon of abanding wind and solar energy and shedding load after the CSP is equipped with TES.And it can improve the reliability of the system operation and improve the penetration of renewable energy power.