Understanding Generator Fundamentals: A Beginner’s Guide to Power Generation
Learning all power system basics is good practice for anyone who works in the power and utilities industry. Each part of the power grid impacts every other, so holistic knowledge is important to maintaining grid reliability. Since a power grid is useless without power generation, that goes double for generator fundamentals.
While our generator fundamentals course provides a more in-depth exploration, we’ll give you a beginner’s guide to how power generation works in this article, including types of generators, the different kinds of power that are generated, and the role of load sharing in power system stability.
What Is A Generator?
Despite their name, generators don’t create electrical energy, but instead harness the energy generated from another source to force electrons to flow through an electrical circuit.
When people hear the word generator, they often think of a backup power source fueled by diesel, propane, or similar fuel types. However, there are multiple types of generators that play different roles in modern power grids, including:
- Primary Power Generators in the form of large power plants that use fossil fuels, nuclear reactors, or renewable energy sources to produce electricity for the grid.
- Backup and Standby Generators that provide emergency power to buildings or systems during a grid outage. Essential services like hospitals and critical infrastructure typically have large, hardwired standby generators to provide continuous operation. Smaller portable backup generators provide a more modest amount of power and must be connected to the system as needed, making them more appropriate for homes and non-essential businesses.
- Generators in Microgrids that increase the reliability of the system by ensuring demand can be met when renewable energy sources are insufficient or unavailable.
- Blackstart Generators that can kickstart the power grid back after a total blackout by reenergizing the grid and bringing other power sources back online. They’re specially designed to start from a “cold” state without any external power source.
How Power Generation Works
All power generators convert mechanical energy into electrical energy.
Different kinds of generators use different sources of energy, whether it’s the mechanical force of wind, the kinetic energy of flowing water, or the burning of fossil fuels to turn steam-powered turbines.
Ultimately, most power generators use their power source to create mechanical rotation through a turbine or a motor. This rotation is used to create electromagnetic induction, forcing the flow of electrons to “generate” electric power.
A voltage regulator is necessary after electromagnetic induction to ensure a consistent output before distribution. Otherwise, fluctuations might overload circuits or devices.
Generators also require a few ancillary systems, including a cooling system to prevent overheating, an exhaust system for generators that run on combustion, and a control panel to manage startup, shutdown, voltage regulation, and other processes.
Basics of Power Output: Active vs Reactive Power
All electrical power systems contain active and reactive power.
Active power – also called actual power, real power, true power, useful power, or watt-full power – does the real work in a circuit by generating light, heat, or mechanical energy. It always flows from source to load, supplied from the generator.
Reactive power occurs when a system’s voltage and current are not in phase. Reactive power changes direction periodically between the source and the load. When it’s traveling from source to load, it’s positive, and when it’s traveling from load to source, it’s negative. Reactive power is sometimes called “non-useful” because it does not do work within the circuit and it creates inefficiencies; however, since it produces electric or magnetic flux, it’s necessary to maintain voltage and current levels.
Apparent power is the combination of active and reactive power.
The power factor of a system is the ratio of active power to apparent power. It’s used to convey the kind of power being transmitted. A power factor of 0.7 would mean the system is 70% active power and 30% reactive power.
A power factor of 1.0 is called the “unity power factor,” indicating no reactive power at all, but it’s impossible to maintain a 100% power factor in all parts of a power system.
How does reactive power affect a power generator? Generators typically have very little variability in their active power output. When demand exceeds supply or vice versa, reactive power can create equipment damage and safety hazards downstream. In order to prevent this, power plant operators must manage multiple generators in response to demand, starting up or shutting down various generators to meet demand. Since changes in demand are more incremental than starting and stopping entire generators can account for, system operators must use inductors (which absorb reactive power) and capacitors (which generate reactive power) to make up the difference.
Load Sharing and Power System Stability
In order to maintain an electrical grid’s stability and reliability, plant operators and technicians must understand generator fundamentals like load sharing, a principle that ensures multiple generators can work together in parallel at optimal performance.
The goal of load sharing is for each generator working in parallel contribute proportionally to the total load demand. This is to prevent any one generator from overloading, so while two generators with similar capacity will carry a similar load, generators with a larger capacity can handle a higher proportion.
Load sharing requires operators to synchronize the generators’ frequency, voltage, and phase angle to prevent power fluctuations and system damage, but this requires constant monitoring and adjustment. In modern power plants, advanced control systems handle this process, allowing for faster reactions and finer tuning. Load-sharing systems use redundancy to ensure that if one generator fails, there is always another to pick up its load.
Get NERC CE Courses for Beginners Online
As a NERC-recognized training provider, we offer a range of NERC CE courses on power system basics suited to beginners like you.
You could begin by diving deeper into the topic of this article with our Generator Fundamentals course, which contains online, self-paced, and interactive material. You’ll be able to earn NERC CEH or PE hours from any device with internet, wherever and whenever it’s most convenient to you.
