Unitrol 1000 Excitation SystemsValerijs Knazkins, senior scientist at ABB Switzerland, reports on the new automatic voltage regulator with built-in rapid synchronizing functionality

Modern excitation systems control and monitor the operation of the generator, carry out limiting, protecting and other special functions. ABB Ltd. manufactures excitation
systems for synchronous machines from small generators to generators with excitation currents up to 10 000 Amps dc.

ABB Unitrol 1000 excitation systems were developed for small synchronous machines, which are characterized by compact design and a broad range of functions. Among these functions are automatic voltage regulation; power factor, excitation current or reactive power control with bump-less transfer between the control modes; full set of limiters ensuring the safe and reliable operation of the generator; reactive load sharing between several machines in a power plant; power system stabilizers (IEEE PSS2A or PSS2B); dual-channel configuration and self-monitoring; and automatic synchronizing.

The Unitrol 1000, in principle, does not require a dedicated synchronizer. The synchronization performance of Unitrol 1000 originates from the fact that it synthesizes a speed bias signal that is directly added to the summing point of the governor’s speed regulator, said ABB. Thus, the speed setpoint of the governor is biased immediately after receiving the synchronization command. The built-in functionality of Unitrol 1000 also allows the user to reduce the number of critical components. Indirectly, ABB said, this enhances the overall system reliability.


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