The outputs of renewable energy sources (RESs) are inherently variable and uncertain

such as wind power (WP) and photovoltaic (PV). However

the outputs of various types of RESs in different regions are complementary. If the capacity of RESs could be properly allocated during system planning

variability of the total output could be reduced. Consequently

system reliability and renewable energy (RE) consumption could be improved. This paper proposes an analytical model for optimal complementary capacity allocation of RESs to decrease variability of the total output. The model considers the capacity ratio of RESs as decision variables and the coefficient of variation (CV) of the total output as the objective function. The proposed approach transforms the single-level optimization model into a bilevel optimization model and derives an analytical equation that can directly calculate the optimal complementary capacity ratio (OCCR) of system RESs. Case studies on wind and solar farms in Xinjiang and Qinghai

China

are performed to verify the effectiveness of the proposed analytical allocation method.