Studies On Multi-period Energy And Reserve Scheduling Considering UHVDC And Wind Power

With rapid decline of wind turbine manufacturing costs and continuous technical advance,wind power has experienced rapid development over the past decade and has been extensively studied around the world.Under the background of the development of Energy Internet and ubiquitous smart grid,Ultra-High Voltage Direct Current(UHVDC)transmission technology,as the main physical carrier of regional power interconnection,has become an important orientation of power construction in China.However,the randomness,volatility and intermittency of the wind power output introduce many problems to the traditional operation of the power system.The UHVDC transmission system normally has high transmission capacity,and its forced outage and random failure impose severe risks of load shedding on power system.Considering uncertainties from wind power,load fluctuation,UHVDC,unit failure,the scheduling of energy and reserve deserves further studies.Based on the background mentioned above,this dissertation is devoted to studying the generation and reserve scheduling considering integration of UHVDC and wind power,and improving system operation economy on the basis of ensuring the reliability of power system operation.This paper is organized as follows:The recent development of wind power and UHVDC transmission system are introduced firstly to provide basic concepts and background knowledge.The influence of UHVDC and wind power on the scheduling of power system is also summarized and overviewed.The superiority of the multi-period scheduling and the necessity of the joint scheduling of energy and reserve is analyzed.The basic concepts of reserve and how to allocate reserve are introduced.The mathematical model of the joint scheduling of energy and reserve,the piecewise linearization of objective function are elaborated in detail.Based on the cost-benefit analysis method,this paper proposes a reserve optimization method considering the integration of UHVDC and wind power.The wind power prediction error and UHVDC transmission system are equivalent to multi-state unit,which are introduced to the modified Outage Capacity Probability Table(COPT).The revised Expected Energy not Severed(EENS)is used to calculate the reserve benefit.A Unit Commitment(UC)model is calculated to obtain the hourly power generation and reserve of the next day,and the sensitivity of the reserve factors is analyzed.In order to improve the refinement level of the joint dispatch,mitigate negative impacts of uncertainties from wind power,load fluctuation,UHVDC,unit failure,and to improve the reliability and economy of the operation,this paper proposes a multi-period energy and reserve scheduling method according to the principle of"Coordination on Multiple Time Scales".According to the function and response time of reserve,the system reserve is categorized by 30-minute reserve and spinning reserve,the determination of the 30-minute reserve capacity is based on the cost-benefit analysis,the determination of the spinning reserve capacity is based on system reliability.Then,this paper demonstrates the principles and mathematical models of multi-period scheduling method in detail.Considering that the prediction error decreases with the time scale reduction,the accuracy of power system scheduling is continuously improved from long time scale to short time scale,and the economy of system operation is improved on the premise of ensuring the long-term operation reliability and short-term power balance of the system.Finally,a 39-bus test case and a provincial grid case are used to validate the effectiveness of the multi-period energy and reserve scheduling.The simulation results show that the proposed multi-period scheduling method can optimize the reference point of system operation from a longer time scale,effectively reduce the risk of the occurrence of large-scale power system failure and improve the system reliability.The gradual refinement of power system scheduling scheme can effectively cope with the short-term fluctuations of wind power and improve the operation economy while ensuring the system reliability.