Research On Optimal Dispatching Strategy Of Flexible Interconnected Distribution Network With Embedded D

The traditional distribution network has many limitations,such as low reliability of power supply,insufficient capacity of accommodating renewable energy and weak flexibility of operation control,which have become bottlenecks to the development of the new distribution system.The flexible interconnection transformation of distribution network by using voltage source converter-based flexible interconnection equipment to realize flexible routing of source and load,thus enhancing the controllability of distribution network and the carrying capacity of random source loads,has become the main technical path for future distribution network development in the context of new power system.The existing research focuses on the flexible interconnected distribution network(FDN)based on flexible power electronic switch(Soft Open Point,SOP)instead of tie switch.This approach suffers from high cost and large footprint,which greatly limits the application of flexible interconnection technology.In this paper,we propose an embedded DC-based distribution network reconfiguration technology based on the existing power supply form of the distribution network,which provides a new technical path for the promotion and application of FDN.On this basis,the operation optimization and scheduling technology of the flexible interconnected distribution network with embedded DC system(EDC-FDN)is studied in depth.The details are as follows:Firstly,the problems and challenges of traditional distribution network in the context of new power system are explained;the development status of FDN and related flexible interconnection equipment is reviewed;the current status of FDN operation optimization and scheduling research is focused on.Next,the limitations of flexible interconnection technology using SOP and flexible multi-state switch(FMS)are analyzed in detail;an embedded DC-based topology reconfiguration technology is proposed;the structural characteristics and operation mode of EDC-FDN are analyzed;a multi-time-scale hierarchical distributed scheduling architecture of EDC-FDN adapting to multiple source-load device access is constructed,and an EDC-FDN multi-time-scale optimal scheduling strategy is highlighted to meet the diversified energy management requirements of the distribution network in the context of the new power system.Then,the two-stage optimal dispatching strategy of EDC-FDN is analyzed in detail;a dynamic reconfiguration optimization model with minimum operational losses and voltage offset of EDC-FDN and a peak-shaving model with minimum variance value after peak-shaving and minimum total dispatching cost of energy storage in each region of the load curve are constructed;a hierarchical coordination based on improved particle swarm algorithm with continuous variables of VSC and discrete variables of switching is proposed;an 88-node four-area power supply FDN case is built to verify the validity and reasonableness of the proposed model and algorithm.The results show that EDC-FDN is more effective than FMS-FDN in improving the economy of FDN operation and the voltage operation level of the distribution network,and also demonstrate the positive effect of the day-ahead optimal scheduling strategy on improving the operation of the distribution network.Finally,an EDC-FDN intra-day rolling optimal dispatching strategy based on model predictive control(MPC)theory is constructed;a rolling optimization model with minimum voltage offset,system active loss and VSC adjustment deviation is proposed;the 88-node FDN case is solved using an improved particle swarm algorithm.The results verify that the intra-day rolling optimal scheduling strategy can reduce the impact of day-ahead forecast errors and improve the intra-day voltage operation while ensuring the effectiveness of the day-ahead scheduling plan.