# Effect of sudden loss of reactive power for an induction generator

• anon6912
In summary: The capacitor bank in parallel to the induction generator is primarily for power factor correction, meaning it supplies the reactive power requirements of the generator. In an islanded scenario, where the grid is out and the capacitor bank is out, the induction generator has no source of reactive power to sustain its stator magnetic fields. This would cause the stator magnetic field to collapse, leading to a large voltage spike and potential damage to the generator. Without the stator magnetic field, the rotor would also stop inducing an emf and the generator would come to a stop. In order to prevent this, phase correcting capacitors can be built in to provide the necessary reactive power for the stator magnetic field to continue functioning. Without these capacitors, the rotor could potentially

#### anon6912

So I am having this problem at work where a 150kW induction motor is being used as an induction generator. There is a capacitor bank in parallel to the induction generator which is primarily for PFC(the reactive power requirement of the generator is fed by the grid).

Assume the induction generator is islanded( i.e the capacitor bank is out, the grid is out and the induction generator is the only thing that's connected to the load)

What would happen to the induction generators speed?
If a step by step explanation on what will happen would be great.

From my thinking when the capacitor bank and the grid power goes out the generator has no source of vars to sustain the stator magnetic fields.
(i.e stator magnetic field will collapse pretty much instantly which will produce a large voltage in the stator coils due to Ldi/dt)

1)After this initial Ldi/dt voltage spike it would cause a large current to flow in the stator coils?and it would oscillate?

2)Or because of the lack of reactive power the stator will have no magnetic field and that would stop inducing and emf on the rotor which will collapse the rotor magnetic field and stop the generator all together?

say the magentic field is not there anymore in the stator, would it cause the rotor(which is connected to an impeller) to freewheel and destruct itself?

I know this is a bit of a long question:)

Yes it will collapse unless there are phase correcting capacitors build in.
https://en.wikipedia.org/wiki/Induction_generator said:
An induction generator usually draws its excitation power from an electrical grid. Because of this, induction generators cannot usually "black start" a de-energized distribution system. Sometimes, however, they are self-excited by using phase-correcting capacitors.

## 1. What is reactive power and how is it important for induction generators?

Reactive power is the component of electrical power that is used to establish and maintain electric and magnetic fields in a circuit. It is important for induction generators as it helps to regulate the voltage and current levels in the system, ensuring stable operation and preventing damage to the generator.

## 2. What happens when there is a sudden loss of reactive power for an induction generator?

If there is a sudden loss of reactive power for an induction generator, it can lead to a decrease in voltage and an increase in current, which can cause the generator to trip or shut down. This can result in power outages and damage to the equipment.

## 3. What are the main causes of sudden loss of reactive power for an induction generator?

The main causes of sudden loss of reactive power for an induction generator include changes in load demand, faults in the transmission or distribution system, and faulty equipment such as capacitors or voltage regulators.

## 4. How is the effect of sudden loss of reactive power for an induction generator measured?

The effect of sudden loss of reactive power for an induction generator is measured by the voltage and current levels in the system. If there is a significant decrease in voltage and an increase in current, it indicates a loss of reactive power. This can also be measured by using power quality analyzers.

## 5. What are the solutions to mitigate the effects of sudden loss of reactive power for an induction generator?

There are several solutions to mitigate the effects of sudden loss of reactive power for an induction generator, such as installing capacitors to provide reactive power support, using automatic voltage regulators to regulate voltage levels, and implementing load shedding or curtailment strategies to reduce demand on the system. Regular maintenance and monitoring of the equipment can also help to prevent sudden loss of reactive power.