Non-Invasive Wideband-frequency Grid Impedance Measurement Device

The increasing presence of power electronics devices challenges the stability of modern grids. The measurement device proposed in this work enables the non-invasive measurement of the grid impedance at the point of common coupling of the device over a wide frequency range. Based on the measured grid impedance, the grid operator can assess the grid stability and initiate countermeasures against instability. The functionality of the proposed device can also be integrated into existing grid connected inverters. Before, during or after the measurement process no shut down or interruption of the measured grid is necessary. Being a small-signal method and by using band-limited white noise, no significant disturbances are introduced in the measured grid while at the same time the measurement duration is minimized. Therefore, the measurement of the grid impedance is possible during any operational state of the grid, especially in situations of heavy load. The proposed measurement device is validated by simulations and laboratory experiments.