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A Novel DQ Impedance Measurement Method in Three-Phase Balanced Systems
Year: 2020 | Author: Ye Tang | Paper: P3.5
Fig. 1. Impedance measurement results for a passive load.
The single-phase impedance measurement process has been applied to two prototype three-phase balanced systems. For passive circuits, voltage perturbations and current responses are both multiplied by the ratio of square root of 8/3 in single-phase impedance measurement compared to three-phase measurement, leading to the same impedance measurement results. For a converter system with d-q frame controls, in order to obtain accurate impedance measurement results using the single-phase impedance measurement method, three-phase balanced perturbations are required by the impedance measurement unit, regardless if the three phases are perturbed together or separately. The analysis shows that only six sensors are needed for measuring d-q impedances of three-phase balanced power systems. Compared to the traditional approach, this method will reduce the quantity of sensors. The reduction in sensors is especially beneficial for high-voltage and high-power applications where bulky and expensive current and voltage sensors are needed.
Fig. 2. Single-phase measurement method on a VSI with current control under three separate phase perturbations.
