In a DC analogy with batteries in parallel, only voltage needs to be controlled for proper load sharing. Similarly, in a mechanical AC analogy, only torque requires control. However, when paralleling AC generators, both variables — torque and excitation — must be properly managed.
- Torque control regulates the division of real power (kilowatts, kW).
- Excitation control manages the division of reactive power (kilovolt-amperes reactive, kVAR).
Both must be precisely controlled to ensure stable and efficient generator operation.
Real power represents the actual work performed by the electrical energy generated. It is supplied by the prime mover in the form of torque, which the generator converts into electrical energy. This energy is then delivered to a load, where it is transformed into useful forms such as heat, light, or mechanical motion (e.g., in a motor).
Reactive power, on the other hand, is the power required by inductive or capacitive loads to store energy during each half-cycle. In the example shown in Drawing 10, the load is purely resistive, such as a heating element. Since no reactive power is needed at any point on the sine wave, the current remains directly proportional to the voltage at all times. Real power can be calculated using Ohm’s Law in this scenario.
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