The utility model discloses carry out the model equivalence to how to various component devices and distribution lines in the active distribution network, lack research in prior art, the problem that leads to developing the follow -up calculation of high frequency harmonic wave trend provides an equivalent model combination circuit for calculating active distribution network high frequency harmonic wave trend. This circuit includes: higher level's background harmonic equivalence model circuit, it adopts source of harmonic voltage to carry out the equivalence, voltage source type grid -connected inverter equivalence model circuit, it adopts a controlled source of harmonic voltage and dc -to -ac converter equivalence harmonic impedance to establish ties equivalently, current source -type grid -connected inverter equivalence model circuit, a controlled source of harmonic current and the parallelly connected equivalence of dc -to -ac converter equivalence harmonic impedance, each equivalent model circuit connection corresponding position in equivalent model combination circuit are adopted to it. The utility model discloses a carry out the model equivalence to the various component devices in the active distribution network and distribution lines, have very important's effect to research and development initiative distribution network.