Dispatch Model And Efficient Algorithm Research On Integrated Electricity-Gas System

Integrated electricity-gas systems(IEGSs)can take advantage of the multiple-energy collaboration and promote large-scale integration of renewable energy,which is expected to help achieve the national carbon peaking and carbon neutrality goals.However,due to the privacy protection needs of different energy systems,the uncertainty of renewable energy,and the potential risk of multi-system cascade failure,the collaborative operation of IEGS faces several challenges.The challenges include proposing a distributed collaborative algorithm that takes into account the privacy protection needs and collaborative efficiency for electricity and gas systems belonging to different entities,designing the rolling dispatch framework and model of IEGS in the context of electricity-gas coupling to effectively revise the dispatch scheme and cope with the uncertainty of renewable energy,quickly and accurately evaluating the security of subsystems during the collaboration to reduce the risk of cascading failures between systems and ensure the system security during the collaboration.To address the above issues,this paper conducted four studies on the collaborative operation of IEGS in terms of modeling and algorithms in the three dimensions of"space-time-security".The core contents and contributions of this paper are summarized as follows.Firstly,we established both an accurate dynamic model and a simplified "linepack"model that can reflect the dynamic characteristics of the natural gas system and further developed IEGS system dynamic models with different accuracy.An accurate power to gas(P2G)model that considers both the electrolysis and methanation reaction processes was proposed based on the different reaction characteristics and coupling relationships between electrolysis and methanation.The accuracy of the proposed two different natural gas system dynamics models and their applicability scenarios are compared and analyzed in the case studies,which lays the model foundation for the later study.Then,a study on the multi-entities collaboration of electricity and gas in IEGS is carried out in the space dimension,and a privacy-preserving distributed collaboration(P-DC)algorithm is proposed.The secure multi-party computation theory is introduced in the distributed collaboration framework,and the collaboration is completed by ciphertext information to avoid privacy leakage.To solve the non-convex constraint in the natural gas system subproblem,an adaptive solving algorithm(A-SA)is further proposed,which improves the speed of solving the natural gas system subproblem.The effectiveness of the proposed P-DC algorithm is verified in the case studies.Next,the IEGS dispatch problem with day-ahead and intraday collaboration is studied in the time dimension.An IEGS intra-day rolling dispatch model that takes into account the natural gas system dynamics and P2G operation characteristics is proposed.On the one hand,an accurate dynamic model of the natural gas system considering the dynamic characteristics and an accurate P2G model taking into account the reaction process of electrolysis and methanation are applied to the rolling dispatch model of IEGS.On the other hand,the rolling dispatch model also considers the uncertainty of wind power and uses chance constraints to reduce operational risks caused by wind power forecasting errors.The simulation results demonstrate the necessity of considering the natural gas system dynamics and P2G operation characteristics in the intraday rolling dispatch of IEGS.Finally,the security region of the natural gas system in IEGS is investigated from the security dimension.The concept and mathematical model of the dynamic security region(DSR)for the natural gas system are proposed,which incorporated the natural gas system dynamics and the coupling relationship between the energy flow at the electricity-gas coupling boundary into the security region evaluation model.In addition,a fast evaluation algorithm(FEA)is designed to address the problem of solving the non-convex dynamic constraints of natural gas systems.Case studies show that the combination of DSR and FEA can achieve an accurate and fast evaluation of the security operating range of natural gas systems.