基于级联H桥变流器的双向功率阻抗测量装置

Dual Power Flow Impedance Measurement Device Based on Cascaded H-bridge Converter

新能源并网变流器大规模接入电网诱发了许多宽频振荡事故,并网变流器与电网的阻抗特性不匹配是此类宽频振荡问题的根源。因此需精确实测新能源并网换流器的阻抗特性,以评估新能源接入后的系统稳定性。为此,提出了一种基于单相级联H桥变流器的双向功率流阻抗测量装置,通过所提控制策略,可在子模块无直流电源供电情况下,实现5~2 000 Hz范围内扰动电流的注入,所提控制策略简化了装置拓扑,提高了装置功率密度。通过半实物实验验证该阻抗测量装置获取谐波阻抗的精确性。

The large-scale integration of renewable energy grid-connected converters into the grid has induced many broadband oscillation accidents.The impedance mismatching between the grid-connected converter and the power grid leads to the broadband oscillation problem.Therefore,it is necessary to accurately measure the impedance of the new energy grid-connected converter to evaluate the system stability.Therefore,a dual power flow impedance measurement device based on a single-phase cascaded H-bridge converter is proposed.By the proposed control strategy,the disturbance in the range of 5-2 000 Hz can be injected into the system under test without DC power supply.The proposed control strategy simplifies the device topology and improves the power density of the device.The accuracy of the impedance measuring device to obtain the harmonic impedance is verified by a hardware-in-loop experiment.