Research On Optimal Operation And Market Bidding Strategy Of Electric-gas Integrated Energy System

With the sharp decrease of natural gas price brought by shale gas development technology and the breakthrough of turbine technology,gas-fired power generations play a progressively important position in the electricity system,which leads to enhanced interdependencies between the electricity system and the natural gas system.Additionally,after the injection of large-scale renewable energy including wind power into the electricity system,efficient flexible resources are required for wind power accommodation.The rapid response characteristics of gas-fired power generations can supply more flexible resources for the electricity system,which provides a new way to solve the wind power accommodation problem.However,the rapid response characteristics of gas-fired power generations lead to more and more frequent intra-day variability in pipeline flow.In order to promote the development of the energy market and promote the coordinated operation of the energy market,the reform of natural gas market,which tends to synchronize with the electricity market,has become a generally recognized trend of energy market transformation.Under the above research background,how to utilize the rapid response ability of gas-fired power generations to solve the problem of renewable energy abandonment represented by wind power and the bidding strategy of gas-fired generators in the new energy market environment is of great significance.Therefore,this paper mainly makes the following work:1)Firstly,the complex operation characteristics of combined-cycle gas turbines were introduced,and combined-cycle gas turbines’ operation model based on mode-based model was introduced by introducing mode transfer matrix.Then,we take combined-cycle gas turbines as the coupling element of electricity system and natural gas system,and establish a unit commitment model with high proportion of wind power including the reserve dispatching and natural gas transmission constraints,to fully exploit the quick response ability of combined-cycle gas turbines to inprove the wind power accommodation capacity of electricity system.Finally,the non-convex Weymouth equation in natural gas network is transformed into a second-order cone constraint with a penalty term by using the concave-convex process algorithm,and the unit commitment model is transformed into an iterative mixed integer second order cone programming problem.2)Under the interdependent electricity and natural gas market environment,we propose a bilevel strategic bidding model and studies the market behaviors of the gas-fired units which plays the role of a strategic power producer in the electricity market and a gas buyer in the natural gas market.Firstly,the bi-level bidding strategic of gas-fired units is proposed to maximize the profits of gas-fired units as the upper model.Then,based on the theory of locational marginal price,the electricity market-clearing model and the natural gas market-clearing model were established as two lower-level models,respectively.Finally,we converted the two lower-level optimization models involving a second-order cone problem as KKT conditions and added to the upper-level model,transforming the bi-level strategic bidding model to a single-level mixed integer second order cone programming model which can be efficiently solved.3)An integrated energy system consisting of a modified IEEE5-bus electricity system and a7-node natural gas system is used as a study case to optimize and analyze the unit commitment problem with reserve dispatching and natural gas transmission constraints in the electricity system with high proportion of wind power and the bidding strategy of gas-fired units in interdependent electricity and natural gas market,respectively.The results of the calculation examples show that based on ensuring sufficient gas supply in the natural gas network,the unit commitment model proposed in this paper can improve the wind power utilization rate and reduce the operating cost of the electricity system;Meanwhile,the proposed bidding strategy model shows stronger adaptability in responding to the natural gas marketization transformation,to ensure that gas-fired units can make the most favorable decisions in the more complex interdependent electricity and natural gas market.Futhermore,the modified IEEE 24-bus electricity system with 14-node natural gas system and the modified IEEE 118-bus electricity system with 14-node natural gas system integrated energy system are used to further verify the effectiveness of the proposed model in large-scale systems.