A portable impedance measurement device with controllable broadband for power grid

Abstract

In order to avoid grid oscillations caused by the frequency domain impedance mismatch of power electronic devices and power system, this paper studies and designs a controllable broadband power grid impedance measurement device to measure real-time parameters of low-voltage distribution network. The core circuit of this portable device adopts an improved “butterfly bridge” circuit, which reduces the size and weight of the device. The main control unit selects the DSP chip TMS320F28335 of Texas Instruments Semiconductor and one injection can realize wide-frequency harmonic excitation. In addition, users can directly generate modulation signals at specific frequency band through touching on the screen, and monitor the process and results of disturbance injection in real time. The final built device has a power of about 5 kV.A, has an AC voltage below 400V, and an AC current below 50A sampling capacity. Considering the measuring results, the designed device is efficient in measuring the wide-frequency band impedance for power grid within the set frequency range.