Which condition is mostly associated with the risk of angle instability in power systems?

Angle instability in power systems is primarily related to the dynamic behavior of the system, particularly concerning the relationships between generators and the loads they serve. High torque and power angles indicate that the operating point of the generators is approaching their stability limits.

When the torque angle—the angle between the rotor's magnetic field and the stator's magnetic field—increases significantly, it can lead to a condition where the power being generated is no longer in balance with the power being consumed. This state can cause a loss of synchronism among generators, resulting in instability. Essentially, if the angle is too high, the system can experience oscillations that may eventually lead to a separation of areas within the grid, risking cascading failures.

Other factors, such as reactive power deficiency, might influence system stability, but they typically relate more to voltage stability rather than angle stability specifically. Low MVA ratings and transmission path misalignment can have implications for power delivery, but they do not directly relate to the immediate risk of angle instability to the extent that high torque and power angles do. Thus, high torque and power angles more directly symbolize a precarious balance within the system, making them a key factor in assessing the risk of angle instability.