不同拓扑柔性直流配电系统过电流理论计算方法适用范围

Application Scope of Theoretical Overcurrent Calculation Methods for Flexible DC Distribution Systems with Different Topologies

柔性直流配电系统是接入新能源、促进分布式能源发展的重要技术手段,其过电流计算是限流方案设计、设备选型、保护策略等的研究基础。具有普适性的精确理论计算方法可以简化和指导过电流的大量电磁暂态仿真。因此,文中开展了放射状和环状柔性直流配电系统极间短路故障下典型过电流理论计算方法的误差原因、影响因素和适用范围的系统性分析。首先,分别分析放射状柔性直流配电系统中过电流的解析计算方法和环状柔性直流配电系统中过电流的数值计算方法,提出了理论计算方法产生误差的根本原因是线路模型误差和公共线路耦合等。然后,在不同拓扑结构下,分析限流电抗器、线路型式及线路长度等因素对过电流理论计算误差的影响。最后,针对不同工况,提出了不同拓扑结构的柔性直流配电系统过电流理论计算方法的适用范围。

Flexible DC distribution system is an important technical mean to connect renewable energy and promote the development of distributed energy.Its overcurrent calculation is the basis of current limiting scheme design,equipment selection,protection strategy,etc.The accurate theoretical calculation method with universality can simplify and guide a large number of electromagnetic transient simulations of overcurrent.Therefore,a systematic analysis on the error causes,influencing factors and application scopes of the typical theoretical calculation methods of overcurrent in radial and circular flexible DC distribution systems under pole-to-pole short circuit faults is carried out in this paper.Firstly,the analytical calculation method of overcurrent in radial flexible DC distribution systems and the numerical calculation method of overcurrent in circular flexible DC distribution systems are analyzed,respectively.It is proposed that the fundamental causes of errors in theoretical calculation methods are line model errors and public line coupling.Then,with different topological structures,the influence of current limiting reactors,line type and line length on the theoretical calculation error of overcurrent is analyzed.Finally,for different operation conditions,the applicability of the theoretical calculation methods for overcurrent in flexible DC distribution systems with different topologies is proposed.