Automatic load frequency control loop in a power system

What is automatic load frequency controller (ALFC)?

Regulation of voltage and frequency is essential in power plants, which further affects reactive and active power generation. These parameters are normally affected by load variations. Thus, an automatic load frequency controller (ALFC) is one such controller which is used to uphold the frequency of the power system at the desired level.

What is a voltage regulator & a load frequency control (ALFC)?

This AGC consists of two sub-control units, Automatic Voltage Regulator (AVR) and Automatic Load Frequency Control (ALFC). When there are any fluctuations in the voltage, then AVR is used in order to maintain a constant voltage. Similarly, in order to stabilize the frequency fluctuations, ALFC will be used.

Can a triple frequency control loop compensate a large load-generation imbalance?

As discussed above, following a large load-generation imbalance, the provided regulation power by the conventional triple frequency control loops in both power amount and response time points of view may not adequate to compensate the grid frequency and maintain the tie-line power at the scheduled values.

What is a secondary control loop (LFC)?

During off-normal operation, depending on the accessible amount of regulation power, secondary control loop or LFC system will be activated to compensate the power grid frequency and return it to the nominal value. The LFC is the main component of AGC.

Who activates the secondary frequency loop?

The system operator as an overall supervisor may activate the secondary frequency loop. The parameter α that can vary between 0 and 1 shows the amount of frequency regulation power for the grid control support. Fig. 3. Various frequency regulation supports provided by wind turbines.

How can a generator control a load variation?

This problem is basically solved by adding a system, i.e., governor which feedbacks the generator speed, and tunes the input actuator to change the output power to follow the load variation and finally to control the system frequency close to the specified nominal value.