Study On Coordinated Optimal Dispatch For Transmission And Distribution System With Wind Power

With the integration of distributed energy resources,such as distributed generation,energy storage and active load,traditional distribution network have gradually turned into active distribution network(ADN).The operation of ADN is becoming flexible and the interaction between transmission system and ADN should not be ignored.Meanwhile,the proportion of renewable energy in power system is increasing rapidly,both centralized and distributed renewable energy face great challenge in accommodation.And,with the reform of electricity market,there will be exist more and more independent stakeholders,aiming at maximizing their own profit but not controlled by system operator.So,the interaction mechanism between power system and electricity users should be established.So,the operation of power system will transform form transmission level operation into multi-intelligent agent coordinated dispatch.This paper mainly focus on coordinated optimal dispatch for transmission and distribution system(T&D)with wind power,the mainly research is as followed:1)A hierarchical coordinated optimal dispatch method is proposed in chapter 2.Based on "centralized scheduling,hierarchical management" mechanism in regulated power system,a bi-level stochastic programming model is formulated.Scenario based stochastic programming is used to deal with wind power uncertainty,as leader in upper level,transmission system operator(TSO)optimize firstly.As a controllable dispatch unit in lower level,distribution system operator(DSO)dispatch distributed resources according to boundary power optimized by upper level as well as influence the upper level results.Each level has their own objective and coordinate with each other.Then,KKT optimal condition method is used to transform bi-level to single-level.Test results show that bi-level optimization can coordinate the objective of each level.As controllable dispatch unit,active distribution system can promote the flexibility of transmission system.The system economy and ability to accommodate wind power is enhanced compared with isolated dispatch.2)A hierarchical and distributed multi-source coordinated dispatch method with high proportion of renewable energy is proposed in chapter 3.Considering the autonomous of active distribution system,the power system is divided into transmission system level,distribution system level and local level.In transmission level,the improved interval approach is employed to deal with the uncertainty of renewable energy,and the sub-problem is formulated as energy and reserve co-optimization model.In distribution system,the local dispatch level is set,the scenario based stochastic programming is used to optimize distributed renewable energy with energy storage.Thus,the sub-problem in distribution system is formulated as dynamic economic dispatch model.Finally,the analytic target cascading(ATC)based iterative method is applied to achieve global optimal,while only boundary variables are exchanged between each area.Case study show that this method can take full use of power resources to accommodate renewable energy and promote the economy of whole system.3)A coordinated T&D optimal dispatch method considering electricity price response mechanism in distribution market is proposed in chapter 4.In deregulated power system,electricity price incentive mechanism is an effective demand response method to deal with multi-level coordinated problem.Firstly,based on the operation architecture proposed in chapter 3,a three level dispatch framework is formulated,including TSO,DSO and user agent(UA).TSO and DSO coordinated through boundary power,consistency constraint should be satisfied.In distribution system level,stackelberg game based pricing scheme and energy management is established between DSO and UA.Then,a novel algorithm is proposed,combined with KKT condition,dual linearized and ATC method.So the optimal boundary power between TSO and DSO,as well as optimal incentive electricity price and user power response can be solved at the same time.Finally,the effectiveness of this method is verified through test cases.This method can coordinate the profit of each dispatch agent,and take full use of power resources to achieve global optimal.