| The need for reducing emissions leads to a continuous increase in the installed capacity of renewable generation technologies,mainly wind turbines.Due to the intermittent and fluctuating nature of renewable energy,it does not match well with the power demand,which leads to the phase redundancy or inadequacy of renewable energy output.Gas turbines are fast responding.Power systems with a fluctuating power supply can obtain more flexibility and reliability from the natural gas system,ensuring a secure power supply.Power-to-gas(P2G)device can store renewable energy sources on a large scale by converting excess electrical energy into hydrogen or natural gas,and enable the two-way flow of energy in the power-natural gas coupling system.P2 G has deepened the coupling and interaction between energy systems and increased the flexibility between energy systems.However,the cost of P2 G devices is high,so there are important research values on how to better use P2 G devices to enhance the coordinated operation of energy systems and improve the economy of energy system operation.Under this background,this dissertation conducts a theoretical study on the investment of P2 G under an uncertain environment by focusing on its efficient utilization of the energy conversion characteristics.Based on a full analysis of the interaction between the electricity and natural gas systems and capacity planning for P2 G,a flexible energy use mechanism for P2 G is proposed to participate in the coordinated operation of the electricity and natural gas systems at the system level.Besides,the operational strategies of reversible solid oxide fuel cells(r SOC)in the electricity market are studied.The main contributions are given as follows.(1)The optimal investment model for power-to-gas plant based on Real Option is developed.In order to cope with uncertain electricity prices,to adapt the analytical framework of the uncertain environment and to take into account the irreversibility of the investment,this thesis proposes an investment method for power-to-gas plant based on real option theory.This method uses Brownian motion to characterize the electricity price,applies Ito's theorem to derive the cost model of the power-to-gas plant,and constructs a profit model and a model of the relationship between capacity and cost for power-to-gas plant.At the same time,a sensitivity analysis is carried out on the relevant parameters affecting the investment of the power-to-gas project.With the investment model presented in this dissertation,it is possible to determine the optimal timing and optimal investment capacity of the power-to-gas plant.In addition,this investment strategy model has broad applicability to physical assets where production costs are highly uncertain and the prices of output production are relatively stable.(2)The optimization model of the integrated electrical and natural gas system is developed,the interaction of the gas-electrical coupling system is analyzed and a planning model of the optimal installed capacity of the power-to-gas plant is studied.The power-to-gas device as an energy conversion method further enhances the interaction between energy systems based on the closer and closer coupling relations between power and natural gas systems.In this dissertation,the interactive influence is examined between the two energy systems.In addition,this thesis establishes a planning model for the optimal installed capacity of the power-to-gas device in order to cope with the operator's requirements of power grid for the limits of generators' variation of the grid-connected power supply.On the basis of meeting the limits of generators' variation of the grid-connected wind power,the optimal capacity of the power-to-gas plant to meet the requirements is determined with the goal of maximizing the operating profit of both wind power and power-to-gas plant.(3)The flexible energy use mechanism for the participation of power-to-gas in the optimal operation of integrated natural gas and electricity energy systems is proposed.In order to consume intermittent renewable energy,to improve the operating efficiency of the power system and the natural gas system,and to provide a high-value application path for power-to-gas plants,this thesis proposes a novel and flexible energy use mechanism based on the coupling relationship between gas turbines,methane steam reforming plants and power-to-gas plants.The demand for hydrogen is co-supplied by electrolysis and methane steam reforming.When the gas turbine is faced with the shortage of natural gas supply,the natural gas capacity of methane steam reforming can be transferred to the gas turbine,and the gas capacity is determined by the result of coordinated optimization.Based on this,this dissertation establishes a mathematical model of the flexible energy use mechanism and incorporates the established model into the optimization model of the power and natural gas systems.Simulations show that compared with the application path of electrolytic hydrogen re-methanation into natural gas pipelines,the flexible energy consumption mechanism proposed in this thesis has higher efficiency for the consumption of redundant renewable energy and can effectively improve the energy conversion efficiency.(4)The coordinated operation strategy of wind power and reversible solid oxide fuel cell(r SOC)in power market is proposed.In order to cope with the risks brought by the uncertainty and uncontrollability of wind power participating in the power market,the wind farm is combined with the r SOC that can compensate for the uncertainty of wind forecast.The operation strategy of the coordination system participating in the electricity market was mathematically modeled,and the cooperative operation strategy of the coordination system in the day-ahead and balanced markets was studied.Simulation analysis shows that the coordinated participation of r SOC and wind plants in the power market can effectively reduce the risk of wind power plants participating in the power market,and improve the economics of the coordinated system composed of wind power plants and rSOCs. |
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