Optimal Operation Of Flexible Distribution Network With Distributed Generation

With the continuous increment of load demand and the shortage of fossil resource,the access of renewable energy has become an inevitable trend.At the same time,the randomness and volatility of distributed generators(DGs)also affect the stable operation of the distribution network.The new challenges put forward a higher requirement for the regulation ability and flexible operation of distribution network.With the development and production of power electronic devices,energy storage system(ESS)and soft open point(SOP)are integrated into the network.Distribution network is gradually evolving into a flexible distribution network(FDN).Compared with the traditional distribution network,the FDN can realize the flexible operation with higher regulation ability,faster corresponding speed and lower operating loss.Therefore,the FDN has high application prospects and research value.However,a large number of power electronic devices and various types of controllable equipment are integrated into FDN.Compared with the traditional distribution network,the modeling analysis is more complicated.Further research is needed to achieve the optimized operation of FDN.This thesis first focuses on the modeling and characteristics of FDN considering the penetration of DGs.The modeling analysis on typical DGs such as photovoltaic(PV)and wind turbine(WT)is conducted.Then,facing the inevitable trend of the transformation of distribution network,this thesis further analyzes the evolution trend of source,network,load and grid structure in FDN.The evolution mechanism and characteristics of FDN are also elaborated in detail.After that,according to the adjustment capabilities and responding speed of controllable equipment,the modelling and multi-time-scale characteristics the controllable equipment are analyzed.By replacing tie switch with an SOP,the economic efficiency of SOP are verified and a suggestion of reasonable site selection is given.Furthermore,facing actual demand of FDN,the equivalent models are introduced respectively.The operation evaluation index of distribution network is introduced and enriched since the concepts of operation margin are proposed,which are used to express the regulation potential of FDN,including line power margin(LPM),node voltage margin(NVM),and system operation margin(SOM).Finally,the optimized operation model of FDN is constructed.Modified IEEE 33 node test system is adopted to quantify the operation margin of FDN and verify the improvement of operating status brought by ESS and SOP through the power flow adjustment.