故障电流转移型MMC的通用故障电流计算方法

General Fault Current Calculation for Fault Current Transfer MMC

直流电网作为风电和光伏等新能源汇集的有效手段,其故障电流的计算对设备选型、保护设计、参数优化等工作具有重要意义。首先对需要源侧和网侧配合的故障清除方案进行特性分析,介绍了故障电流转移型模块化多电平换流器(modular multilevel converter,MMC)的基本原理。然后结合其故障穿越的具体过程,提出了一种故障电流转移型MMC的通用故障电流计算方法。为确保该类方案的优势最大化,提供了关键参数的设计依据。最后,在PSCAD/EMTDC上搭建了四端直流电网并验证了所提故障电流计算方法的有效性。结果表明:所提故障电流计算方案具有很高的计算精度,并且具备较好的通用性。

As an effective means of the new energy collection such as wind power and photovoltaic,the DC power grid is of great significance for its equipment selection,protection design,parameter optimization,etc.in the calculation of fault current.Firstly,this paper analyzes the characteristics of fault clearing schemes which need the cooperation of the source side and the network side,and introduces the basic principles of the fault current transfer MMC.Then,combined with the specific process of the fault ride-through,a general fault current calculation method for the fault current transfer MMC is proposed.In order to maximize the advantages of such a scheme,the design basis of the key parameters is provided.Finally,a four terminal DC power grid is built on the PSCAD/EMTDC,and the effectiveness of the proposed fault current calculation method is verified.The results show that the proposed fault current calculation scheme has high calculation accuracy and good generality.