What are the key components of a turbine governing system and how do they interact to maintain speed and power output?

The key components of a turbine governing system are the speed sensor, the governor controller, the servomotor, and the wicket gates (or needle valve in a Pelton turbine). These components work together in a closed-loop control system to maintain the turbine's speed and power output at the desired setpoints. The speed sensor continuously monitors the turbine's rotational speed and sends a signal to the governor controller. The governor controller compares the actual speed to the desired speed (speed setpoint) and calculates the necessary adjustment to the turbine's water flow. If the actual speed is below the setpoint, the controller signals the servomotor to increase water flow; if the actual speed is above the setpoint, the controller signals the servomotor to decrease water flow. The servomotor is a hydraulic actuator that positions the wicket gates (or needle valve). The wicket gates control the amount of water flowing through the turbine. By adjusting the wicket gate opening, the servomotor changes the power input to the turbine, thereby controlling its speed. The controller uses algorithms to adjust the wicket gates. For instance, a proportional-integral-derivative (PID) controller adjusts the gate position based on the error between the actual and desired speed, the integral of the error over time, and the rate of change of the error. This continuous feedback loop ensures that the turbine maintains the desired speed and power output, even when load conditions change on the electrical grid. For instance, if the grid load increases, the turbine speed will initially decrease. The governor will sense this decrease and open the wicket gates to allow more water to flow through the turbine, increasing its power output and restoring the speed to its setpoint.