# Reduced load in a turbine generator

• Leannie
In summary, the conversation discusses a turbine generator delivering a 20MW load at 50Hz, which suddenly drops to 15MW. The governor starts to open the steam valve after 0.5s, and the goal is to calculate the frequency to which the generated voltage rises before the steam flow decreases. The solution involves using an energy conservation equation, as the relationship between rotational kinetic energy and angular speed is quadratic rather than linear.
Leannie

## Homework Statement

A turbine generator is delivering a 20MW load at 50Hz, to a local load.; it is not connected to the grid. The load suddenly drops to 15 MW, and the governor starts to open the steam valve after 0.5s. Calculate the frequency to which the generated voltage rises, before the steam flow decreases in response to the reduced load. The stored energy in the rotating parts is 80MJ at 3000rpm.

## Homework Equations

I know it a 2 pole generator from p=120f/n (don't know if this matters)
I also know reducing the torque will give a reduced power output.

power(kW)=(2∏×torque(Nm)×rpm)/60000
torque=(60000×power)/(2∏×rpm)
P=E/t

## The Attempt at a Solution

During the 0.5 seconds before the steam flow is reduced there is extra power generated.
20MW-15MW=5MW
E=Pt=5MWx0.5s
E=2.5MJ

Total energy from rotating parts=80MJ+2.5MJ=82.5MJ
(2.5/80)x100=3.125% increase in energy at shaft

Will the frequency simply then be an increase of 3.125% i.e. 50+(50x0.03125)=51.5625Hz

Or is it more complicated than this, would the torque be considered?

Thanks

Leannie said:
Total energy from rotating parts=80MJ+2.5MJ=82.5MJ
(2.5/80)x100=3.125% increase in energy at shaft

Will the frequency simply then be an increase of 3.125% i.e. 50+(50x0.03125)=51.5625Hz

Or is it more complicated than this, would the torque be considered?

No, it won't be a linear relationship since the relationship between rotational kinetic energy and angular speed is quadratic.

I would try an energy conservation equation instead.

ok thanks, i thought it wouldn't be as straight forward as that. i will try the an energy conservation equation instead.

## 1. What is reduced load in a turbine generator?

Reduced load in a turbine generator refers to the decrease in power output from the generator. This can be caused by a variety of factors, such as changes in demand or maintenance issues.

## 2. How does reduced load affect the performance of a turbine generator?

Reduced load can have a significant impact on the performance of a turbine generator. It can lead to decreased efficiency, increased wear and tear on the equipment, and potentially even damage if the generator is not designed to operate at reduced loads.

## 3. What are the potential causes of reduced load in a turbine generator?

Reduced load in a turbine generator can be caused by a variety of factors, including changes in demand, problems with the turbine or generator components, or issues with the power grid. It can also be a deliberate action taken by the operator to protect the equipment.

The approach to addressing reduced load in a turbine generator will vary depending on the cause. In some cases, adjustments can be made to the turbine or generator components to optimize performance at lower loads. In other cases, the operator may need to adjust the output of other generators in the system to compensate for the reduced load.

## 5. What are the potential consequences of prolonged reduced load in a turbine generator?

Prolonged reduced load in a turbine generator can have negative consequences, including increased maintenance and repair costs, reduced efficiency, and potential damage to the equipment. It can also lead to disruptions in the power supply if the generator is unable to meet the demand for electricity.

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