| In order to implement the decision of the 19 th National Congress of the implementation of the rural revitalization strategy,government units at all levels actively carry out the "The beautiful countryside" construction project,among which the rural distribution network as the foundation of rural economic development are paid much attention to.However,China’s rural power grid foundation is generally weak,and there are problems such as low reliability,low voltage and poor power quality.Although the grid connection of distributed generation（DG）has a certain positive impact on the above problems,the distributed generation using renewable energy is greatly affected by environmental factors,and the output power has a strong uncertainty,which may further deteriorate the power quality.Energy storage system（ESS）has characteristics of rapid response,flexibility,low geographical requirements,by cooperating with DG can effectively solve the negative impact on the grid,and further improve the power supply reliability,voltage quality and renewable energies consumption,provides a new path for rural distribution network planning.Therefore,the thesis starts from the optimization planning requirements of rural distribution network with DG connected under following aspects.Firstly,based on the background of rural distribution network,introduces the typical network structure,power load structure,existing problems of rural distribution network,expounds the influence of uncertainties of renewable energy DG on rural distribution network,including the impact on voltage distribution,active power loss and power supply reliability.According to their characteristics,established the output power model of photovoltaic power generation,small hydropower and the charge/discharge power model of energy storage battery.On this basis,the K-means clustering algorithm is used to integrate the annual climate data to generate typical climate scenarios of months,which lays a theoretical and data foundation for the subsequent research in this thesis.Secondly,after the introduction of reliability evaluation methods,evaluation index and established annual real-time load model,aiming at the impact of ESS connects to DG-containing distribution network on reliability evaluation,considering the power margin constraints and capacity constraints provided during islanding operation,a dynamic load cutting strategy considering islanding sustainable load capacity during islanding operation is proposed.The improved RBTS-BUS6 feeder is used as a simulation example to verify the proposed reliability evaluation method.The result showing that the proposed dynamic load cutting strategy can preferentially guarantee the continuous power supply of important loads and improve the system reliability during islanding operation,and also quantify the influence of different ESS configurations and ESS grid connection position on the system reliability.Thirdly,in response to the ESS configuration for distribution network in rural areas needs to take into account the demands of economy and reliability of distribution network,considering the interactive relationship between the configuration of ESS and its operational control,a bi-level programming model of energy storage optimal configuration of distribution network considering system economy and reliability is proposed.The upper planning configuration model aims at maximizing the economic and reliability benefits by configuring ESS.Combined with the reliability evaluation method proposed that considers islanding sustainable load capacity,the modified crisscross optimization algorithm（MCSO）is used to solve the problem;the lower level operation model aims at the lowest daily operating cost of the distribution network system,and the model is relaxed by second-order cone programming technology and solved by a mathematical solver.Finally,the validity and practicability of the proposed method and model are verified with an actual rural distribution network in northern Guangdong.The resulting ESS configuration scheme can effectively balance economy and reliability.The boundary limits or conditions such as different target weights and different PV penetrations are all analyzed. |
