Flexible Interconnection Strategy Of Distribution Station Areas To Enhance Photovoltaic Acceptability Under The Background Of Whole County PV

In recent years,with the transformation of energy structure and the continuous introduction of clean energy policies,the access ratio of distributed photovoltaic and DC loads in low-voltage distribution networks has continued to rise,and the operating characteristics of distribution station areas have become more complex and changeable.The difference of time sequence characteristics between source and load in distribution station areas easily leads to problems such as power reverse and transformer overload,which makes it more difficult to plan distributed generation and control the operation of distribution station areas,and also puts forward higher requirements for safety and flexibility of traditional AC distribution network.The flexible interconnection technology of distribution station area can change the traditional distribution network structure,and directly connect adjacent distribution areas with complementary operation characteristics through flexible power electronic devices.With the power control capability of flexible equipment ports,the interconnection system can realize the flexible mutual assistance of source and load resources across stations,which is beneficial to the consumption of distributed photovoltaic and the optimal operation of regional distribution network.Based on this,this paper studies the flexible interconnection strategy of distribution station areas to improve the photovoltaic acceptance ability under the background of " whole county PV".Firstly,the working principle,topological structure,control strategy and application scope of typical flexible interconnection system are introduced and analyzed,and the power balance constraint of interconnection system based on converter is established.On this basis,a day-ahead economic dispatch model of flexible interconnected system with distributed photovoltaic,energy storage and load demand response is proposed.With the power regulation function of converter,the power transfer within and between distribution station areas is optimized,so as to reduce the operation cost of interconnected station areas and realize the economic operation of AC-DC hybrid system.Secondly,in order to solve the problems of photovoltaic consumption and safe and economic operation of distribution network with high proportion of distributed photovoltaic,the demand index and connectability analysis method of distribution station area are put forward,and the flexible interconnection bilevel planning model of distribution station area is constructed based on this.The upper layer decides the interconnection state of distribution station areas and the capacity of interconnection devices,and the lower layer explores the economic operation mode of regional distribution network.By optimizing interconnection scheme and power interaction between distribution areas,cross-area consumption of distributed photovoltaic and real-time load transfer are realized,so as to improve the photovoltaic consumption rate and the operation efficiency of distribution network.Finally,considering the role of distribution area interconnection in improving the acceptance capacity of distributed photovoltaic in operation and planning,a joint planning method of distributed photovoltaic-distribution station area flexible interconnection is proposed.This method optimizes the photovoltaic capacity and interconnection scheme of each distribution station area in regional distribution network at the same time,and breaks the limitation of load level in distribution station area on the photovoltaic access capacity when it operates independently,which provides more optimization space for the distributed photovoltaic planning and optimal operation of regional distribution network under the background of"whole county photovoltaic.