Optimization Study On Integrated Power Transmission Capacity Of Photovoltaic Plants Incorporating Clustering Effect

Nowadays the main approach to explore solar energy is to connect large-scale photovoltaic into the power grid in centralized method. So how to rationally determine the capacity of the transmission line has been a primary issue. Because of the fluctuation and intermittent of solar power, the traditional method which decided capacity of the transmission line as total install capacity of the clustering photovoltaic plants probably reduce utilization of transmission line.Accordingly, fluctuation characteristic of solar power must be taken into account when determining the capacity of the transmission line.In order to discovery the impact of integrated photovoltaic plants to power system and rebuild photovoltaic model, the solar output power from large-scale solar base located on northwest of China was analyzed previously. Based on actual data, the factors, such as season and weather, which influence on output power were exhibited. A new method to evaluate power fluctuation was presented and analyzed the solar power fluctuation characteristic under different install capacity. The clustering effect was interpreted from correlation characteristic and duration characteristic standpoint of solar power. A new method was pointed out to determine capacity of the transmission line with clustering effect.Combined with Copula function, a solar irradiance computational method was proposed.This method contains solar irradiance time varying property simulation module and the randomness cloud cover simulation module. Using this solar irradiance computational method, a clustering photovoltaic plants power model was built in consideration of clustering effect and the effect of max power point control system.Based on clustering photovoltaic plants power model, an optimization method for determining integrated power transmission capacity of clustering photovoltaic plants was presented. In order to maximize the comprehensive benefits and determining optimal power transmission capacity, the following factors have been taken into account, such as the transmission benefit, transmission constructing cost as well as the congestion loss probably caused by a low transmission capacity. Case study showed that compared with equal capacity method, the proposed method can achieve higher transmission project benefit and enhance the utilization of transmission line.