Research On Optimization Of Transmission Network Expansion Planning Integrated Wind-photovoltaic Generations

In recent years,with the vigorous implementation of China’s energy transformation policy,the power grid integrated large-scale wind-photovoltaic generations has become an inevitable trend.However,renewable energy resources generations such as wind-photovoltaic have strong randomness,intermittence,and volatility.It makes the transmission network integrated wind-photovoltaic generations have more uncertain factors.In addition,the electricity market reform and the proposal of a comprehensive consideration of the electricity market and green low-carbon policy have added more uncertainties to the transmission network expansion planning.Therefore,it is urgent and important to deal with the uncertainty of renewable energy resources generations such as wind-photovoltaic and establish a safe,economic,and reliable transmission network expansion planning model considering the above factors.Based on the data of the 18-bus system and the actual data of the 52-bus system in a certain area of Sichuan Province in the project “Research on Regional Transmission Planning Considering the Largescale Integration of New Energy Resources under the Electricity Market”,the research on optimization of transmission network expansion planning integrated wind-photovoltaic generations is carried out in this paper.The primary contents of this thesis are as follows:First of all,to consider the uncertainty problem caused by renewable energy resources generations such as wind-photovoltaic,starting from the uncertainty probability modeling method,the two-parameter Weibull distribution,Beta distribution,two-point probability distribution,and normal distribution are used to characterize the output probability models of wind power,photovoltaic power,hydropower,and load.Based on the semi-invariant probabilistic power flow method,the linear probabilistic DC power flow model is established,which lays the foundation for the model of transmission network expansion planning considering congestion.Secondly,to consider the transmission congestion problem in the power pool+centralized market environment mode,the annual congestion surplus index based on the market is used to describe the severity of transmission congestion,and the transmission network expansion planning model considering economy and the system congestion level is established.The optimization algorithm of Hybrid-Adaptive Differential Evolution with Decay Function is used to solve the established model.Through cases of the 18-bus system and the 52-bus system in a certain area of Sichuan,the correctness and effectiveness of the proposed transmission network expansion planning model considering congestion are verified.The Hy DE-DF algorithm has good applicability and accuracy.The obtained planning scheme meets the better economy and has a certain effect on mitigating the congestion level of the transmission network.Thirdly,to further consider the volatility of the power of wind-photovoltaic generations over time,starting from the scenario analysis method,based on the normal distribution prediction error model of the power of wind-photovoltaic generations,the Latin hypercube sampling method and synchronous back substitution subtraction method are used to construct multiple output scenarios that can comprehensively characterize the power characteristics and volatility of wind-photovoltaic generations.Through the example of one-day power generation data of typical wind farms and photovoltaic power plants in a 52-bus system in a certain area of Sichuan,the results show that the scenario analysis method can effectively describe the volatility of the power of wind-photovoltaic generations,which provides a prerequisite basis for the two-stage transmission network expansion planning and modeling for greater consumption of wind-photovoltaic outputs.Finally,considering the economy of transmission network expansion planning and improving the accommodation capacity of wind-photovoltaic generations,a two-stage transmission network expansion planning model considering transmission investment cost and operation cost is established based on scenario analysis,and the Hy DE-DF algorithm is used to solve the established model.Through cases of the 18-bus system and the 52-bus system in a certain area of Sichuan,the accuracy and effectiveness of the proposed two-stage transmission network expansion planning model are verified.The planning scheme obtained by the Hy DE-DF algorithm meets the economy and has good wind-photovoltaic consumption ability.