What happens to the system frequency when significant MW load is suddenly reduced?

When a significant megawatt (MW) load is suddenly reduced in an electrical system, the balance between power generation and power consumption is disrupted. In this case, the generation of electricity continues at its current level, but the demand suddenly decreases. When demand falls, there is less need for the same amount of power, resulting in an excess of generation relative to the load.

As per the principles of frequency regulation in power systems, frequency is directly related to the balance between load and generation. A reduction in load while maintaining generation causes the frequency to rise. This occurs because the synchronous generators connected to the grid continue to turn at a speed that corresponds to their original operating frequency. Since less load is consuming power, the generators are effectively producing more power than is being used, which leads to an increase in system frequency.

This behavior is governed by the laws of physics governing synchronous machines, where the rotational speed (and therefore frequency) of the generators increases when they are under less load. Thus, when there is a significant reduction in MW load, the system frequency increases, making this the correct answer.