Resilience Modeling And Assessment Method For Distribution Network Considering Multi Energy Coupling

In recent years,with the dramatic change of global climate,extreme natural disasters occur more and more frequently,which has developed into the primary factor leading to large-scale blackouts.In this context,the concept of resilience is introduced to reflect the ability of distribution network to minimize the blackout range of loads,reduce the load losses during the failure process,ensure the power supply for critical loads and quickly recover the blackout loads under extreme disturbance with low probability-high losses.Along with the rapid development of integrated energy system(IES),the coupling relationships among distribution network with other energy networks are becoming tighter.The transformation and coordination of multi energy including electricity,gas and heat can support the power supply of distribution network when the large-scale blackout occurs under extreme disturbance,reduce load losses and speed up the recovery process,which effectively enhances the distribution network resilience.Therefore,this paper focuses on the resilience modeling and assessment methods for distribution network considering multi energy coupling.The main works are as follows:(1)A distributed state estimation algorithm for IES containing electricity,gas,and heat is proposed.Taking the multi energy coordination relationships on various coupling units into consideration,the IES state estimation model is built based on the weighted least square(WLS)algorithm.According to the bilinear theory,three bilinear measurement models are derived respectively for distribution network,gas network and heat network.Then,the IES state estimation is equivalently converted to a three-stage convex optimization problem consisting of two linear estimations and an intermediate nonlinear transformation.The three-stage procedure can be further decoupled over three networks with coordination on coupling units,yielding a fully distributed scheme based on the modified alternating direction method of multipliers(ADMM)to quickly and accurately obtain the global operating status of IES,providing a complete and reliable data basis for resilience modeling and assessment.(2)A resilience model for distribution network considering multi energy coordination is established.Taking typhoon as the representative of extreme disturbance,its influence mechanism on distribution network is analyzed and modeled.Based on the component vulnerability model,the failure rates of distribution lines can be derived to quantify the influence of disturbance.The non-sequential Monte Carlo simulation method is adopted to generate failure scenarios of distribution network.According to the optimal load shedding strategy,the response model for distribution network considering multi energy coordination is built with dynamic characteristics of gas and heat network considered.The model can accurately simulate the operation processes of energy networks in IES under disturbance to analyze the support to power supply and the resilience enhancement effects from multi energy coordination,as the source of the quantitative indexes for resilience assessment.(3)A resilience assessment index system and its corresponding assessment method for distribution network considering multi energy coupling are proposed.A set of the resilience assessment indexes is selected after analyzing the resilience influence factors,in which some multi energy indexes related to gas and heat networks are introduced to quantify the influence of multi energy coordination.The relationships among the indexes are comprehensively determined by the correlation analysis based on model and data,and then the distribution network resilience assessment index system is constructed as the network hierarchy structure through the analytic network process(ANP).Based on the optimal weighting model,the comprehensive weights of indexes are obtained from the combination of their subjective and objective weights.The fuzzy comprehensive assessment method is adopted to get the resilience assessment results for distribution network considering the multi energy coupling,which provides the reference for IES joint planning and optimal operation with the aim to enhance the distribution network resilience.