What is Generator Synchronization?

generator synchronization

Daylight savings time has a way of throwing people out of sync, especially if they forget to change their clocks. Just like people need to sync their clocks to the rest of the world, generators need to be synchronized if they are removed from the service and connected back to the power system during variations of the load, emergency outages, maintenance, and in other situations. This helpful article from Woodstock Power explains what you need to know about generator synchronization.

Generator Synchronization: Basics

Generator synchronization is the process of matching parameters such as voltage, frequency, phase angle, phase sequence, and waveform of alternator (generator) or other source with a healthy or running power system. This is done before the generator is reconnected to the power system. Once a generator is synchronized with the parameters of another generator, alternator, or bus bar, the system can run smoothly again.

Generator synchronization to a power system must be conducted carefully to prevent damage to the unit, as well as the power system itself. When synchronizing a generator to a power system, the frequency and voltage of the generator must match closely. The rotor angle and the instantaneous power system phase angle must be close prior to closing the generator breaker and connecting the isolated generator to a power system.

In the majority of cases for generator synchronization, the synchronization process is automated via an automatic synchronizer with manual control capabilities that can be used in backup situations. Synchronizing panels generally indicate any adjustments that the operator should make in regards to the governor and excited and when it’s deemed acceptable to close the breaker.

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Why is Generator Synchronization Needed?

A generator cannot deliver power to an electrical power system unless all the aforementioned parameters exactly match those of the network. The need for synchronization arises when two or more alternators work together to supply the power to the load. Since electrical loads do not remain constant, the two or more generators supplying the power need to be interconnected and operate in parallel to handle larger loads.

Techniques for Synchronization

Generator synchronization can be a complex idea to understand, but here are the basics of three techniques for generator synchronization:

  • Three Dark Lamps Method – uses bus bar to synchronize second generator; cannot provide information on generator and bus bar frequency.
  • Two Bright, One Dark Method – measures frequency but cannot check the correctness of the phase sequence.
  • Synchroscope Method – indicates whether the alternator frequency is higher or lower than the bus bar frequency

Modern synchronization equipment automates the entire synchronization process in order to avoid manual lamps and synchroscope observations. These methods are far more reliable.

Faulty Generator Synchronization

If generator synchronization with a power system is done incorrectly or poorly executed, there is the potential for:

  • Generator & prime mover damage due to mechanical stress caused by rapid accelerator/deceleration need to bring the rotating masses in synch.
  • Damage to the generator and step-up transformer windows due to the high currents
  • Disturbance to the power system, such as oscillations and deviating voltages that are not nominal
  • Keeps the generator from staying online and pick up loads when the protective relay determines the generator is running in abnormal operating conditions, which can cause the generator to shutoff

Contact Woodstock Power for More

If you would like more information about generator synchronization, the process, or techniques to do it, our staff at Woodstock Power would be happy to help. Contact us today!

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