Importance of Frequency Control in AC Power Systems

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What determines the frequency in an AC power system?

The balance between generation and demand

Why would large frequency drops be damaging to transformers and induction motors?

Due to the high magnetizing currents required for maintaining the flux

What are turbine blades designed to avoid?

Mechanical vibrations at their natural frequencies

Why may a 50 Hz steam turbine not be able to withstand frequency deviations greater than ±2.5 Hz?

Turbine blades are designed to operate within a narrow frequency band

What is the operational range for system frequency, according to power quality considerations?

$49.5 Hz ≤ f(t) ≤ 50$

Why must system frequency remain within its operational range?

To prevent damage to transformers and induction motors

What is the primary purpose of automatic load shedding in the operation of turbo-generators under abnormal system operating conditions concerning frequency?

To reject just enough loads to lighten the remaining generation system from overload and restore the system frequency close to nominal

Why does the reduction in frequency cause generator control systems to increase their input power?

To maintain the generation and demand balance

Why does a reduction in frequency and an increase in power may result in an increase of the internal temperature of the turbine and generator windings?

Due to a decrease in cooling and an increase in power demand

What is the purpose of primary frequency control after an underfrequency event?

Automatically adjust output of generators equipped with frequency sensors

What is the purpose of secondary frequency control if the under-frequency event does not correct itself?

Automatically regulate generation through Automatic Generation Control (AGC)

What is the maximum operating time of a 60 Hz steam turbine at full load when its frequency drops to 58.8 Hz?

$90$ minutes

How do grid operators typically respond if the frequency starts to exceed 60/50 Hertz?

By reducing output from some generators

Why are under-frequency events more serious compared to over-frequency events?

They are often unexpected and involve the loss of a large source of electricity

What is done when under-frequency events occur?

Automatic load shedding is activated.

What increases as a result of a reduction in frequency and an increase in power?

Internal temperature of the turbine and generator windings.

Explore the significance of frequency control in AC power systems and its impact on the balance between generation and demand. Learn about the potential effects of frequency changes on transformers and induction motors.

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