Research On Reliability Evaluation Method Of Distribution Network Considering Integrated Energy Services

With the increasing shortage of fossil energy,the aggravation of environmental pollution,and the continuous imbalance of energy consumption structure,the traditional single energy system that operates independently,dispatches separately,and is decentralized managemented has low energy utilization efficiency and a single type of energy,so it can no longer meet the rapidly growing needs of diversified energy.Under the background of "dual carbon",energy transformation is constantly being promoted,energy conversion technology is becoming more and more mature,integrated energy services are developing rapidly,and the coupling between the distribution network and other forms of energy network is deepening.This kind of coupling enhances the flexibility of the system,but it also greatly increases the complexity of the system and the risk of fault propagation across systems,bringing new problems to the reliability evaluation.Therefore,from the perspective of reliability evaluation of distribution network,this thesis focuses on the impact of various energy subsystems and coupling links on the reliability of distribution network under the background of integrated energy services.The main research work is as follows:(1)A reliability evaluation method of distribution network considering the influence of natural gas network is proposed.A power system model and a natural gas system model are established,and the coupling relationship between the power system and the natural gas system is described in the form of an energy hub.The failure analysis of each part of the system is carried out,and the probability model of component outage considering the influence of the external environment and service time is established.In order to better show the specific impact of the coupling system and various external factors on the distribution network,a short-term power supply reliability evaluation index system including load loss indexes and margin indexess is established.In order to solve the problem of many constraints and complex calculation process in the unified optimal power flow calculation,an optimal load shedding algorithm based on hierarchical decoupling is proposed.Finally,the non-sequential Monte Carlo simulation method is used to verify the validity of the model and method proposed in this thesis and to analyze the influence of the external environment,natural gas system component failure,and capacity of combined heat an power plant on the reliability of the distribution network.(2)A reliability evaluation method for distribution network is proposed that takes into account the dynamic characteristics of the natural gas system.According to the generation mechanism of gas dynamic characteristics,the dynamic model of natural gas system is established by using mass conservation equation,ideal gas state equation and momentum equation.The Wendroff scheme is introduced to carry out the second-order precision difference of the model in time and space directions,reducing the model to a linear equation describing the relationship between nodal pressure and flow.Finally,the reliability evaluation of the distribution network considering the influence of the natural gas’ s dynamic characteristics is carried out,and the influence of the dynamic characteristics of the natural gas system and the initial pipeline gas storage on the reliability of the distribution network is analyzed.(3)A reliability evaluation method of distribution network considering the influence of natural gas network and heat network is proposed.Based on the principles of thermodynamics and fluid mechanics,a thermal system model is established.The energy hub model in the integrated energy system is constructed,and the failure analysis of the thermal system is carried out.Adjust the load shedding process and build an optimal load shedding model based on the hierarchical decoupling algorithm for the electricity-gas-heat integrated energy system.Finally,the influence of the failure of the thermal system components,the coupling mode between the energy subsystems and the access location of the energy hub on the reliability of the distribution network is studied.