Research On The Operation Of Flexible DC Control In The Electromagnetic Loop Network Of Guangzhou

With the continuous development of Guangzhou power grid,the power supply and power consumption are increasing,the problem of electromagnetic loop network operation in the city has become increasingly prominent.On the one hand,the operation of electromagnetic loop network in Guangzhou will cause the short circuit current of the power grid.However,the operation of opening loop will reduce the reliability of the power grid,power supply capacity and the ability to deal with serious fault.On the other hand,the Guangzhou power grid is used as the receiving end power grid of several HVDC transmission lines.The system dynamic reactive power support is insufficient,and the city power grid lacks the flexible regulation means.These problems all threaten the security and stability of Guangzhou power grid.Therefore,this paper proposes to apply the flexible DC control technology to the Guangzhou electromagnetic loop network to solve the problem of power system.In this paper,the actual power grid in Guangzhou is the research object.Designing the flexible DC controller to apply it to the model of Guangzhou power grid,and study its control mode and function.Firstly,the basic structure and operation principle of the modular multilevel converter(MMC)are studied.On the basis building the flexible HVDC back-to-back connection model in PSCAD/EMTD simulation software,and designing the corresponding controller.In addition,according to the BPA data of Guangzhou power grid the electromagnetic transient equivalent model of Guangzhou power grid is established in PSCAD/EMTDC.The flexible DC controller is used to connect the two grids of Guangzhou power grid to realize the operation of the flexible DC link flexible loop.In the model,the control mode and strategy of the flexible DC controller are studied,and the short-circuit current limiting mode,the emergency power support mode and the power flow control mode are designed.The power flow calculation method of AC / DC power system is proposed.And by the power flow calculation,the control reference value of the flexible DC controller is obtained.Finally,in the Guangzhou power grid model,the control function and the effect of each control mode of the flexible DC controller are verified.And the flexible control ability can solve the problem of the electromagnetic loop network in Guangzhou.By using the flexible DC control technology to solve or alleviate the problem of electromagnetic loop network operation in Guangzhou is presented in this paper.This method has important guiding significance to improve the quality of power supply,management level,and the reliability and controllability of grid.And Guangzhou power grid as a typical representative of the urban power grid,the research of this topic has a significant demonstration significance and application prospect.