Research On Interaction Effects Among Multi-converter In Distributed Power Flow Controller

The Distributed Power Flow Controller is a distributed flexible AC power transmission system with small size,low investment,flexible layout,and easy operation and maintenance.It is a kind of new technology which is suitable for the fast,flexible,and comprehensive power control supply of the safe and stable operation of power electronic smart grids.Due to its own characteristics,Distributed Power Flow Controllers can be applied to AC transmission and distribution networks.The characteristics and control laws of the controllers must be fully analyzed before application.This paper makes a detailed analysis of the interaction between control variables of Distributed Power Flow Controller and lays a foundation for the development of prototypes and practical engineering applications.This paper starts with the research status of flexible AC transmission systems,distributed and flexible AC transmission technologies and Distributed Power Flow Controller.After fully understanding the characteristics of it,the topology structure and working principle are studied.The 3rd harmonic is an important channel for serial and parallel energy transmission of Distributed Power Flow Controller.The mechanism of its energy transmission is analyzed in detail.And analyzed the serial parallel operation mode and power flow control range of the Distributed Power Flow Controller.Mathematical models,as the basis for the study of the interaction effects of Distributed Power Flow Controller,introduce several important mathematical models of Distributed Power Flow Controller,including equivalent voltage source models,power injection models,and current injection models.The principle and of the characteristics mathematical models are introduced.Based on the injection current model and the influence of the 3rd harmonic energy dynamic exchange,the corresponding series-parallel controllers and 3rd harmonic controller were designed.For the interaction between serial and parallel controllers of Distributed Power Flow Controller,the relationship between output powers of the controllers is first analyzed,and the output power is studied for the Distributed Power Flow Controller to compensate system voltages and regulate the system power flow.The effect of the reference value on the system is studied.For active power flow control,the relationship between active control and voltage is analyzed.The setting of active power reference value and its influence are analyzed.Based on a typical system,the relationship between active compensation and DC voltage fluctuation amplitude is simulated.For the interaction between Distributed Power Flow Controller and series converters,a relative gain array method and NI are used to quantitatively calculate the effects of two serial converters,and the relationship between the diagonal elements of the matrix,NI coefficient and 1 is observed,and get the mutual influence of multiple series converters.Finally,the interactive influence of multi-series converters of Distributed Power Flow Controller is deduced and analyzed.Taking three series converters as examples,the influence of electrical distance on multiple series converters is simulated.