Natural Gas And Power Integrated Regional Energy System Coordinated Operation Strategy

In the traditional energy system like power system,natural gas system and heating system,the correlation of various energy system is weak and the operation of each sytem is relatively independent.With the rapid development of energy supply technologies,which mainly consist of natural gas distributed energy and renewable energy,the diversification of energy sources on demand side promotes the coupling of diffierent energy systems.Under the background of energy interconnection,the gas-electricity coupling regional integrated energy system is gradually becoming the main form of energy supply in future cities.Gas-electricity coupling regional integrated energy system is consistes of power distribution network,natural gas distribution network and distributed energy hub.Whether the integrated energy system can achieve multi-energy complementary advantages depends on the coordinated operation strategy of various heterogeneous energy networks and distributed energy hub.Therefore,the operation strategy of integrated energy system is a hot topic in both industry and academia worldwide.This paper starts from the research of network energy flow modeling method for gas-electricity region integrated energy system.The power flow of distribution network and the mathematical description method of natural gas flow in distribution network is analysed firstly.After that,the coordinated optimization operation strategy is studied in both dircect control and price incentive scenarios.In this paper,a multi-time scale and multi-management model coordinated operation model of gas-electricity coupling regional integrated energy system is constructed.The specific research results are as follows:(1)Multi-energy flow modeling problem.In the distribution power system,a single-phase power flow linearization methods based on power loss sensitivity and DistFlow voltage assumption for the three-phase balanced network is proposed.Additionally,a power flow linear model for three-phase unbalanced network is also proposed based on fixed point theory.The presented methods can reduce the difficulty of solving optimization problems on the premise of calculation accuracy.In the distribution gas network,a steady flow model under isothermal conditions is established according to the pressure drop equation and the flow balance of the pipeline network.Considering the influence of gas flow rate and line pack,a dynamic model of gas pipeline axial movement is further constructed.The model is simplified by the slow dynamic characteristics of nataual gas system,and the mathematical description of gas flow state in different time scales is realized.(2)Under the unified control scenario,a multi-time scale coordinated optimization model including two stages of day-ahead optimization and intraday correction is proposed.In the previous stage,through the cooperation among distributed energy hubs,power distribution network and gas distribution network,the power fluctuation of renewable energy is transferred to the natural gas system and the cooling/heating system locally.In the intraday stage,the power output of micro-gas turbine is revised by updating prediction information,to reduce the impact of the prediction error of renewable energy.With the propoed model,renewable power fluctuation in integrated energy system is stabilized locally,and the dual peak shaving role of distributed energy hub in both power system and natural gas system is fully utilized.(3)An incentive energy price calculating and decomposing method for integrated energy system is proposed.Based on the multi-energy flow optimization model,the power marginal price and gas marginal price are calculated respectively by Lagrange function.After that,the marginal energy price is decomposed by multiplier,which gives the abstract marginal price practical physical significance.With the marginal energy pricing mechanism,users can realize the perception of the system operation limit.Even if they control the distributed resources for their own interests,the operation mode of distributed resources can ensure the system security.