Before resynchronization of an isolated area to the interconnection, what are three important power system parameters that must be within acceptable limits?

The correct choice highlights three critical parameters that ensure the stability and reliability of the power system when an isolated area is resynchronized to the larger interconnection: phase angle, voltage magnitude, and frequency.

Phase angle is vital because it indicates the relative timing of the waves of voltage and current. When resynchronizing, it is crucial that the phase angles of the isolated area and the grid are closely aligned to prevent significant disturbances or oscillations which could lead to system instability.

Voltage magnitude is also important, as it ensures that the voltage levels of the isolated area are similar to the levels of the interconnected system. A significant difference can cause equipment damage or operational issues, making it essential to match voltage magnitudes before connecting the systems.

Frequency is another critical parameter, as it reflects the overall balance between generation and load. A frequency discrepancy can lead to serious implications such as generator tripping or potential system blackouts. Maintaining frequency within acceptable limits ensures a smooth integration of the isolated area into the interconnection.

In summary, these three parameters—phase angle, voltage magnitude, and frequency—must be carefully monitored and controlled to ensure safe and stable resynchronization of an isolated area with the wider power grid.