Abstract
Instrument current transformers (CTs) measure AC currents. The DC component in the measured current can saturate the transformer and cause gross error. We use fluxgate detection and digital feedback compensation of the DC flux to suppress the overall error to 0.15%. This concept can be used not only for high-end CTs with a nanocrystalline core, but it also works for low-cost CTs with FeSi cores. The method described here allows simultaneous measurements of the DC current component.
Highlights
Instrument current transformers (CTs) can be heavily influenced by the DC component in the measured current [1,2,3]
We have shown an effective way to measure DC currents in the power grid by protection of current transformers, which are already installed within the whole grid [15]
In this paper we show that automatic compensation of the DC flux is possible using a digital feedback loop
Summary
Instrument current transformers (CTs) can be heavily influenced by the DC component in the measured current [1,2,3] This has become a serious problem, as DC currents are very common in the power grid. Sensors 2016, 16, 114 the magnetization characteristics linear, and increases the saturation field Due to their low permeability, these cores exhibit a large phase error of the order of 5 ̋. We have shown an effective way to measure DC currents in the power grid by protection of current transformers, which are already installed within the whole grid [15] This is, in some cases, a preferable solution, when taking into account the costs and difficulties associated with installing new magnetic or optical DC current sensors at high-voltage lines and distribution stations [16,17,18]. On the basis of this benchmarking, we select one of them for the final device
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