Flexibility Resource Collaborative Planning And Optimization Allocation Of Power System In The Context Of Carbon Emission Peak And Carbon Neutrality

Large-scale development of wind and solar power generation is an important strategic measure to achieve the low-carbon transition of power sector and the national goal of carbon emission peak and carbon neutrality.However,integrating massive variable renewable energy poses a great challenge for the stability and safety of power system operation.The flexibility ability of power system is an important determining factor for grid connection of variable renewable energy power generation.In order to improve the consumption ability and quality of power system for wind and solar power,this thesis takes the “carbon emission peak and carbon neutrality” target as the background and the integration of variable renewable energy as the main line,discussing the integration mechanism of variable renewable energy in power system based on the evolution of power system structure and the mode action of flexibility resources;building a power system flexibility resource planning and operation optimization model considering the constraints of investment and operation of flexibility resource,renewable energy consumption,and carbon emission limitation;analyzing the changes in installed capacity and operation structure of dispatchable power generation,inter-regional interconnection,energy storage and demand side response under different flexibility option combination scenarios according to the scenario simulation results of provincial power systems;and presenting the renewable energy development path and flexibility resource allocation strategy for national and typical provincial power systems based on the differences in system cost,carbon emission and evaluation index of variable renewable energy consumption.The research results provide theoretical basis and practical reference for the national and regional system planning and variable renewable energy integration.The results show:(1)The increase in the proportion of variable renewable energy power generation will lead to the dynamic evolution of components and structure forms of power system.The operation mechanism of power system will change from “sourceload” to “source-grid-load-storage” coupling and cooperative control mode.Different flexibility resources play various roles in integrating variable renewable energy:dispatchable generation technologies complement the changes of variable renewable energy generation by adjusting power output;the grid provides spatial support for the long-distance consumption of variable renewable energy by strengthening interregional connection;demand load responds to the output change of generation side by adjusting power consumption;and energy storage improves the synchronization between variable power generation and power demand through energy conversion.Eight configuration scenarios are formed by combing flexibility resources from time scale,configuration process,spatial scope,and application context dimensions:“dispatchable generation”,“dispatchable generation + energy storage”,“dispatchable generation + inter-regional transmission”,“dispatchable generation + demand side response”,“dispatchable generation + energy storage + inter-regional transmission”,“dispatchable generation + demand side response + inter-regional transmission”,“dispatchable generation + energy storage + demand side response”,“dispatchable generation + energy storage + demand side response + inter-regional transmission”,which provide different regulation for dynamic integration of variable renewable energy in the process of power system construction planning and flexibility resource allocation.(2)Different flexibility resource allocations have various promotion effects on the development scale of variable renewable energy in different stages.The penetration level of variable renewable generation will reach 23.8%-27.5% and 45.7%-68.4% in2030 and 2060,respectively.Inter-regional connection,energy storage and their combination will play a significant role in promoting wind power construction before2030,and the distribution of wind power will shift from North China and northwest to central and eastern regions.Demand side response gradually replaces energy storage and becomes an important means to promote wind power construction in the later planning period.Energy storage,demand side response and their combination will continue to play a significant role in promoting solar power construction,and the distribution of solar power will gradually shift from northwest and eastern regions to central,southern,and southwestern regions in 2030 and 2050.(3)The synergy and substitution between flexibility technology configurations gradually emerge with increasing penetration level of variable renewable energy.When other types of flexibility options are not considered,ultra-supercritical coal-fired units dominate in the deployment of dispatchable generation technology,which will be replaced by gas-fired units when inter-regional connection,energy storage,demand side response are introduced into the system operation.However,the construction of hydropower and nuclear units begin to accelerate in the middle and late planning period,which restrains the continuous increase of installed capacity for gas-fired units.There is a mutual substitution between energy storage and inter-regional connection,and inter-regional connection has more restrictive effect on electrochemical energy storage than that on pumped storage hydropower.In addition,demand side response has a certain substitution effect on energy storage,but it will increase the construction demand of inter-provincial transmission lines,and the additional capacity is mainly distributed in the transmission channels sent to the eastern and southern regions.(4)There are great differences in the effects of different flexibility resource combinations on variable renewable energy consumption in the power systems and carbon reduction targets in the power sector.The introduction of inter-regional connection,energy storage,and demand side response will promote the low-carbon operation of power systems.The carbon emission will peak 1-6 years earlier and the peak value of will decrease by 260-480 million tons compared with the single configuration scenario of dispatchable generation technology.Lower carbon emissions can be achieved when emission reduction target is decomposed into the provincial power systems,but the coupling relationship between the carbon emission reduction process flexibility options is weak.It is difficult to match the system scheduling requirement for the corresponding flexibility resources commination configuration,especially the configuration scenarios without inter-regional transmission in Anhui,Yunnan,Guangxi,Inner-Mongolia,Ningxia,Qinghai,and Gansu,resulting in the decrease of utilization rate of wind and solar power generation because these provinces only need to meet local power demand.The high-quality consumption of variable renewable energy cannot be achieved from the whole power sector.By comparison,the collaborative operation of flexibility options will further accelerate the process of carbon emission peak and reduction,and increase the system’s consumption level of variable renewable energy at the cost of economic efficiency.Based on the above research conclusions,this paper put forward the following policy recommendations: establishing a cooperative planning mechanism of flexibility resources;perfecting the scheduling system of flexibility resource operation;formulating flexibility enhancement strategy considering provincial disparity;improving consumptive responsibility weight of renewable energy.