Which line would a GMD most likely impact?

A Ground-Magnetic Disturbance (GMD) primarily affects power lines by inducing voltage levels that can disrupt normal operations. The level of series compensation in a transmission line relates to how much reactive power the line can manage and how it responds to changes in load or conditions.

Lines with higher percentages of series compensation tend to be more resilient to fluctuations because they are designed to handle a larger amount of reactive power. Therefore, the impact of a GMD on any line would be greater in scenarios where there is less compensation capacity, as such lines would have a harder time dealing with the disturbances caused by the GMD.

Lines with 0% series compensation are effectively unprotected against voltage transients caused by GMD. Such lines are significantly more susceptible to disturbances, leading to the potential for malfunction, increased risk of outages, or damage to equipment. In contrast, lines with higher series compensation values (like 25%, 50%, and 75%) are better equipped to manage the effects of a GMD.

This understanding indicates that a line with 0% series compensation is most likely to be impacted by a GMD, as it lacks the necessary compensation to mitigate the adverse effects of induced voltages.