Droop speed control

Droop speed control is a governor method in which a generator’s speed or frequency setpoint falls as its power output rises. This characteristic lets parallel generators share load without continuous communication.

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Speed governor: A feedback controller that adjusts a prime mover’s input to regulate rotational speed. It changes fuel, steam, or water flow in response to speed deviation.
Synchronous generator: An alternating-current generator whose rotor turns in synchronism with the electrical frequency it produces. Its rotor speed is directly tied to grid frequency, giving the governor a measurable control signal.
Islanded power system: An electrical network operating separately from the wider grid and relying on its own generation. Droop lets parallel units share load while the island’s frequency shifts with demand.
Load-frequency control: A supervisory control process that adjusts generation to maintain scheduled frequency and power exchanges. It corrects the frequency offset left by primary droop response.
Frequency regulation: The control of power-system frequency by balancing generation with electrical demand. Droop makes generator output respond to frequency deviations across the grid.
Prime mover: A machine that converts an energy source into mechanical power to drive another machine. The governor changes the prime mover’s mechanical input to alter generator output.
Microgrid: A localized electrical network that can operate connected to a larger grid or independently. Droop control helps coordinate sources when a microgrid operates independently.
Secondary frequency control: A slower control layer that restores system frequency and scheduled interchange after primary response. It changes generator setpoints after droop has shared the initial imbalance.
Load sharing: The division of a system’s demand among multiple power sources or machines. Generators with compatible droop settings divide changes in demand according to their response slopes.
Governor: A control device that regulates a machine’s speed by adjusting its power input. Droop speed control is one operating characteristic of a governor.