Theoretical Study On Dynamic Economic Dispatch Of Power System Considering Flexibility

Under the background of achieving the goal of "carbon peaking and carbon nutralization"before 2060,large-scale renewable energy sources,such as wind power and photovoltaic power,are integrated into power systems.It has been a trend that these renewable energy sources are gradually replacing traditional fossil energy sources as main power sources in power systems.However,their integrations to the grid meet the growing demand for utilization of energy and protection of environment,their inherent characteristics of uncertainty,such as time-variant,volatility,intermittent and other random characteristics,have broken the original regulation mechanism of power balance among source,network and load,and made great imfluences on reliability,economy and flexibility of power system.In order to respond to the impacts and challenges to power systems caused by these inherent uncertain factors of large-scale renewable energy sources,it is necessary to deeply explore the resources of flexibility which can be active regulated from sides of source,network and load,improve their utilization levels,and establish corresponding secure and economic dispatch strategies for power system in order to adjust to safe,reliable and sustainable operation under the new situation.Therefore,it has important theoretical significance and practical engineering value to deeply study the dispatch of resources of flexibility and corresponding risk management in operations and controls of power systems under these backgrounds.The main research contents and innovative achievements of this paper are as follows:(1)In order to achieve the "dual-carbon" objective of the power system,a robust economic dispatch method considering CSP flexibility and N-k security criterion is proposed to solve the promblem that coupling of component fault and uncertainty of renewable energy generation cause flexibility response failure.The principle of CSP is analyzed and its mathematical model is established.A two-stage robust dispatch optimization model is established considering cost of load-shedding in objective function,and is solved by Big-M method and column and constraint generation(C&CG)algorithm.N-k security criterion is used to verify strictly security of power system and CSP is used as additional flexibility sources to solve faults coupling risks.Test examples verified that CSP has the ability of energy storage and peak shaving,which can reduce the output of conventional thermal units,improve the distribution of power flow,and enhance the economy of system.Cooperation with N-k security criterion can solve uncertainty of wind power and improve flexbility of system and reduce the flexibility response risks caused by faults coupling.(2)To solve the problem that the uncertainty caused by renewable energy sources need more flexibility which makes spinning reserve respond risks caused by frequently time period coupling in dynamic economic dispatch,with the background of considering CSP and N-k security criterion,a dynamic ecnomic dispatch model is proposed considering time period coupling respond risks of spinning reserve and risks of prediction on uncertainty and N-k security criterion.The model used an improved multi-universe parallel quantum genetic algorithm to minimize users’ outage loss expectations and wind curtailment loss expectations,which can improve the effectiveness of reserve configuration in power system operation and reduce the risk of load-shedding and wind curtailment.(3)In order to alleviate the problem that the uncertainty of renewable energy sources made flexibility reserve insufficiency supplyed directly by conventional thermal units,a concept of flexibility transfer is proposed to describe the spatiotemporal transfer process of control ability between the power systems and energy storage systems,and an economic dispatch method considering flexibility respond risks and reserve transfer is established,the model of resever tranfer is proposed,which can make cooperation between thermal units and energy storage systems,and coordinately dispatch with reverse strategies.A two-layer optimization model is established to achieve cooperation and coordination between day-ahead economic dispatch and real-time reserve adjustment.The day-ahead economic dispatching calculates the power generation plan,energy storage plan and reserve configuration,The conditional value-at-risk(CVaR)index calculates the reserve demand caused by uncertainty,and considers the N-k security criterion and the real-time reserve risk optimization of the timecoupling response of spinning reserve.Reserve tranfer is used to reduce or eliminate the uncertainty of renewable energy sources.Test examples are used to verifiy that energy storage can reduce the reserve capacity of conventional thermal power units while avoiding frequent unit starts and stops,and improve the system economy;It can also play a role of reserve transfer through cooperation with wind power,while reducing the risk of wind curtailment and load shedding,reducing the risk of uncertainty prediction,and improving the reliability of the system.