Synergistic Dispatch Studies Considering Transmission And Distribution Correlation

In the current power system,the proportion of renewable energy integration is gradually increasing.When the system changes to be clean,the uncertainty in the transmission and distribution system is increasing,and the consumption of renewable energy is facing challenges.In the distribution system,with the development of various active management measures,the traditional passive distribution system is gradually transformed into an active distribution system,and there will be bi-directional power flow between the transmission and the distribution system.The traditional economic dispatch module which separating the transmission and distribution system is no longer suitable for the new situation.Therefore,this thesis takes the transmission-distribution system as the research object,and studies the economic dispatch of the transmission-distribution system from the perspective of economy and reliability,with the goal of consuming as much renewable energy as possible.Firstly,starting from the coordination relationship of transmission and distribution systems,the thesis analyzes the relationship between transmission and distribution systems,and takes the active power as the only coupling variable,and establishes a coordinated dispatch model considering the active management measures in distribution systems.The coordinated dispatch model of the transmission-distribution system is divided into transmission system dispatch problem and distribution system dispatch problem,and the transmission system is taken as the central coordinator,which is solved only by transferring the coupling variables and the two dispatch problems are alternatively iterated.A variety of active management measures of active distribution system are considered in the model,and the distribution systems with different characteristics are classified to analyze their effects on the transmission system.On the premise of ensuring the information independence between transmission and distribution systems,the proposed method also makes the dispatching decision of the entire system,which improves the operation economy of transmission and distribution systems.Secondly,from the perspective of the consuming large-scale renewable energy,the thesis analyzes the effect of the automatic regulation effect in the transmission system,and gives the corresponding analytical expression.Based on the basic coordination dispatch model,a new coordination model considering the automatic regulation effect of the transmission system is proposed.In the transmission systems,the frequency and voltage regulation effect of generators and loads are taken into account to exploit the potential flexibility in the transmission system.At the same time,the flexibility and the corresponding equivalent reserve provided by the active distribution system are simultaneously considered and the corresponding capabilities are analyzed.The case studies show that the model can effectively reduce the wind spillage and improve the system capability of absorbing the renewable energy.Finally,based on the reliability analysis of the transmission-distribution system,a reliability constrained transmission-distribution scheduling model is established.The model considers the normal operation scenario and the fault scenarios.Considering on the computational efficiency.The constraint addition method is applied to address the influence of a large number of constraints brought by N-l criterion to enhance the computation efficiency.Besides,the influence of the reliability constraint of the transmission and distribution systems on the coordination effect of the transmission-distribution system,on the reserve deployment and on the system's capability of absorbing renewable energy,respectively.The results show that in considering the outage scenarios in transmission system will significantly affect the reserve deployment and more reserve is required to meet the given reliability requirement.While considering the outage scenarios in distribution,more flexibility will be kept for maintaining the reliability in distribution system and the flexibility provided to distribution is reduced.