Operational Flexibility Assessment And Enhancement Of Power System With Renewable Energy Base On Uncertainty Marginal Pricing

The destruction of the environment and the predatory use of natural resources make it more serious of global environmental pollution and climate problems.The supply of fossil energy is increasingly scarce.It has become the consensus of all countries in the world to vigorously develop renewable energy and develop sustainably.Compared with conventional generating units,renewable energy source represented by wind power and photovoltaic power generation has the advantages of large reserves,low investment,zero pollution,zero emission and recyclability,but it also has five extraordinary characteristics that have a significant disadvantage on the safety and stably operation of power system:volatility,uncertainty,location specificity,and asynchronous operation.These characteristics change the operation strategy of traditional power system which use controllable generation to meet the uncontrollable load,making it difficult to maintain the balance between supply and demand of power system.Power system today needs new resources and new operation strategies urgently to cope with the rapid growth of renewable energy.Operational flexibility of power system coping with the volatility and uncertainty of renewable energy has become the focus of energy transition.In this paper,an operational flexibility assessment and enhancement strategy of power system with renewable energy source based on uncertainty marginal pricing has proposed,which aiming to attract the flexible dispatchable resources of different stakeholders in power market to participate in power system operation,and improving power system operational flexibility.First,a modeling method for modeling spatiotemporal distribution of uncertainty caused by renewable energy generation to power system supply and demand balance is proposed for evaluating spatiotemporal specificity of power system flexibility requirements.(1)Multi-stage robust optimizing model containing robust security constrained unit commitment and stochastic security constrained economy dispatch is constructed.(2)Locational marginal price and uncertainty marginal price are derived based on the aforementioned model,by which the disadvantage caused by renewable energy generation to power system supply and demand balance is quantified.Second,mathematical models of flexible dispatchable resources of different stakeholders responding to electricity price signals and improving power system operational flexibility are proposed.The models constructed are:(1)transport model and charge-discharge model of mobile energy source considering traffic constraint.(2)flexible charging model of electric vehicle fleets with commuting characteristics.(3)co-optimizing model of new energy vehicle fleets composed of electric vehicles and fuel cell vehicles and urban hydrogen/electricity charging stations.Third,the market clearing model and solution methodology of dispatchable flexible resources providing flexible as ancillary service are proposed.(1)A bi-level master-follower game model is proposed to describe the game relationship between different stakeholders: The model of master minimizes operating cost of power system with renewable energy and derives LMP/UMP.The model of followers are dispatching models of flexible resources operated by various stakeholders.(2)An efficient iterative algorithm is designed to solve the proposed master-follower game model and determine the market equilibrium.To avoid homogenous behaviors of flexibility resources,a sequential dispatching algorithm is developed.An objective function update strategy is also developed to ensure a maximum total profit for MES owners.Finally,the proposed method is verified by IEEE 6-Bus system,IEEE118-Bus system and IEEE 300-Bus system.The results demonstrate that the proposed method can effectively drive the flexible resources of independent operators to serve power system and improve the social welfare.Specifically,(1)the operational flexibility of the power system have improved and the operating cost have reduced;(2)the electricity payments of power users is reduced;(3)flexible resource operators make reasonable profits.