Research On Capacity Credit Of Renewable Energy Sources And Its Application

With the increasingly serious environmental problems,people pay more and more attention to the green new energy.The wind and solar energy are the most promising and exploitable energy in all kinds of new energy.However,because of the intermittent and volatility,new energy units cannot provide the same capacity as their installed capacity,which making it difficult to consider their capacity benefit on the system in the power grid planning.The credible capacity and capacity credit of new energy sources has become the key to the power system integrated with new energy sources.In this paper,the probability density model of new power output is established firstly.The wind speed and the light intensity are simulated by the Weibull distribution and the Beta distribution.The wake effect between different wind turbines is also included.From the power curve,the power output models of the wind farms and the photovoltaic plants are obtained.By using Markov Chain Monte Carlo method,MCMC model of new energy sources is obtained.The calculation cases are based on practical data in a region.Through the study above,it can be used for the power output prediction of the new energy units in the future.Secondly,a reliability assessment model of generation and transmission systems integrated with the new energy sources is established,which is based on the Monte Carlo method.The power flow and the network structure are calculated and judged by the DC power flow calculation and the depth priority algorithm.This model also considers the volatility of system loads and the uncertainty the failures of generators and transmission lines,which can be used to study the influence of new energy sources on the power system reliability.Then,the definitions of the capacity credit of new energy sources are given from the generation side and the system loads side.This paper divides the capacity credit to different types according to different time scales,and the capacity credit of new energy generators combined with the conventional generators and energy storage equipment are studied.The calculation method is also proposed.Based on the IEEE-RTS 79system,the capacity of new energy generators can replace conventional generators is obtained according to the secant method.The influence of some factors,such as the transmission lines capacitites,the intergration capacities and solutions on the calculation are analyzed.Finally,from the perspective of medium and long term planning,this paper proposes a new energy cost model considering the capacity credit,which can be used to measure different new energy inegrateion programs and provide a reference for determining the new energy capacity.Then,the impact of new energy sources on power system peak regulation is studied.A method,which considers the capacity credit to calculate the peak-valley of power system is presented and analyzed by example.This paper is helpful to evaluate the capacity value,economic value and environmental value of new energy,and provides a reference for the new energy power planning.