面向配电网的π形等效电路链形网络级联数目确定方法

Method of Determining Cascading Number ofπ-Shaped Equivalent Circuit Chain Network Oriented to Distributed Network

配电网的物理模拟日益受到重视,其中传输线常使用π形等效电路链形网络模拟,如何经济且有效地搭建传输线模型十分重要。首先,文中给出了无损耗π形电路链形网络在不同级联数目时的输入阻抗表达式,明确其与无损耗均匀传输线之间相频特性的差异。然后,分析了π形电路链形网络与无损耗均匀传输线之间特性阻抗的幅频误差,发现当工作频率接近或超过前者对后者模拟的上限频率时,二者出现本质上的差异,且任意频率与上限频率之比仅与特性阻抗误差有关。以链形网络中每节π形电路均工作在其首次谐振频率以内为前提,可确定特性阻抗合理的误差范围,进一步得到适合配电网π形电路链形网络的合理级联数目。最后,通过对典型传输线参数进行计算及仿真,以及利用物理模拟系统试验结果进行对比,验证该方法的合理性与有效性。

Increasing attention has been paid to the physical simulation of the distribution network. The transmission line often adopts the π-shaped equivalent circuit chain network in simulation. It is very important how to construct the transmission line model economically and effectively. Firstly, this paper gives the input impedance expressions of the lossless π-shaped circuit chain network with different cascading numbers, and clarifies the difference in phase-frequency characteristics between the chain network and the uniform transmission lines without losses. Then, the amplitude-frequency error of the characteristic impedance between theπ-shaped circuit chain network and the uniform transmission line without losses is analyzed. It is found that when the operation frequency approaches or exceeds the upper limit frequency, with which the π-shaped circuit chain network simulate the uniform transmission line without losses, the two are essentially different. The ratio of any frequency to the upper limit frequency is only related to the characteristic impedance error. Each π-shaped circuit in the chain network is premised on working within its first resonant frequency, so that the reasonable error range of the characteristic impedance can be determined. Furthermore, the reasonable cascading number which is suitable for π-shaped circuit chain network of the distribution network can also be obtained.Finally, through the calculation and simulation of typical transmission line parameters and comparing the experimental results of physical simulation system, the method is verified to be reasonable and effective.