Study On Resilience Assessment Of Electricity-Gas Regional Integrated Energy System

The integrated electricity-gas district energy system consists of an electricity system,a natural gas system and an energy centre,which mainly realises the complementary support between the distribution network,the gas distribution network,the district energy centre and other district energy systems on a regional scale.In an integrated electricity-gas district energy system,the distribution network is located at the end of the power system and is more vulnerable than the main network,and the energy conversion equipment that couples electricity and natural gas brings new resilience influences to the system.Thus,The study of the resilience of integrated electricity-gas regional energy systems is of great importance for the operation and protection control of the systems under extreme disasters.This paper studies the vulnerability and resilience assessment of integrated electricity-gas regional energy systems,with the following main work.(1)The Newton-Raphson(N-R)method is used to decompose tidal currents for the electricity-gas integrated energy system.The tidal models of the electricity system,natural gas system and coupled electricity-gas system are constructed for different energy subsystem structures.The N-R method is used to solve the tidal model of the electricity-gas regional integrated energy system and obtain the tidal calculation results,which provide the basis for the elasticity analysis of the electricity-gas regional integrated energy system.The example analysis verifies the correctness and validity of the decomposition tide calculation of the electricity-gas regional integrated energy system.(2)A method is proposed to identify the vulnerable lines of the distribution network under the electricity-gas regional integrated energy system.Based on the complex network theory,the topology of the distribution network is analysed to establish the structural vulnerability index;the N-R method is used to analyse the tide of the distribution network to establish the operational vulnerability index;on this basis,a comprehensive vulnerability index is proposed to identify and analyse the vulnerability of the distribution network lines.Finally,the effectiveness of the proposed method is verified by means of case studies.(3)A quantitative index system is proposed for the resilience of electricity-gas regional integrated energy systems based on heterogeneous dependency networks.According to the characteristics of the complex network model,the coupling components in the electricity-gas network are electrically decoupled,and a two-layer heterogeneous dependency network model of the electricity-gas regional integrated energy system is established and transformed into a two-layer bipartite diagram.Based on the bilayer bipartite diagram,a system of quantitative indicators of resilience is proposed,which is expressed in the form of complex numbers,taking into account the vulnerability and resilience of the system.Finally,a fault propagation analysis and the establishment and calculation of quantitative resilience indicators are carried out for the electricity-gas integrated district energy system by means of an arithmetic example.(4)A comprehensive assessment method for the resilience of electricity-gas regional integrated energy systems based on the geometric mean G1-inverse entropy weighting method is proposed.The resilience assessment of the electricitygas regional integrated energy system based on multiple resilience indicators belongs to a multi-indicator comprehensive evaluation problem.By comparing and analysing the sequential relationship method(G1 method),entropy weight method,inverse entropy weight method,hierarchical analysis method and other comprehensive evaluation methods,a comprehensive system resilience assessment method based on the geometric mean G1-inverse entropy weight method is proposed.On the basis of the calculation of quantitative indicators of elasticity,the comprehensive elasticity value of the system is obtained.Finally,the resilience assessment of the system under different fault conditions of the electricity-gas area integrated energy calculator is carried out to verify the correctness and effectiveness of the proposed method.