Capacity Credit Evaluation Of Intermittent Energy Considering The Correlation

Recently, due to global warming problem and the deficiency of fossil fuels, intermittent energy plays a key role as alternatives of these fuels, especially wind and solar power renewable energy. However, intermittent energy is provided with unstable and variable characteristic, it is necessary to evaluate the capacity credit of intermittent energy. In addition, with the increasing penetration of intermittent energy, it is insignificant in practice if we just calculate the capacity credit of single intermittent energy farm. The comprehensive capacity credit considering correlation among the intermittent energies should be studied. In this context, a method to evaluate the capacity credit of intermittent energy considering the correlation among them was presented in this paper.A multiple wind farms joint output model considering correlation is proposed. The model considers some factors such as the wind speed, wake effect and wind to power conversion comprehensively. When modeling for wind speed, firstly, Copula multivariate distribution model is used to capture spatial dependencies, and then ARMA model is utilized to describe the temporal correlation. Finally, pick the spatial dependence of copula and the temporal characteristic of ARMA model to build Copula-ARMA wind speed model.A wind farm and PV station joint output model considering correlation is proposed. The proposed model takes factors due to intermittent wind speed, solar irradiance, and environment temperature and energy conversion characteristics of two kinds of new energy into consideration. Due to the output of PV station has obvious diurnal variation characteristics, daytime and nighttime wind farms & PV station joint output models were established respectively. A Copula-ARMA model for multivariate wind speed-radiation time series was used during the day which is similar to the above multivariate wind speed time series model. Taking into account that the output of PV station is approximately zero, so ARMA model was only used to the wind speed time series.A reliability and capacity credit evaluation model of intermittent energy was proposed. Firstly, Sequential Monte Carlo simulation method was used to calculate the system reliability, and then Secant method was used to evaluate the capacity credit of intermittent energy. Finally, by an example of IEEE-RBTS test systems, a number of uncertainty factors which affect capacity credit of intermittent energy were analyzed. Research results show that the proposed intermittent energy output model considering correlation can be applied to comprehensive capacity credit evaluation. Intermittent energy output model, the correlation between outputs as well as the capacity configuration have non-negligible effects on comprehensive capacity credit of intermittent energy, which provide direct and reliable basis for planning and development of system containing large-scale intermittent energy.