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| Illustration 1 | g00884611 |
Cross Current Compensation (Typical Example) | |
Cross current compensation (CCC) is often used to minimize circulating current flow between the generators that are connected in parallel. All generators contribute toward establishing the same output voltage to the load. The operation is similar to the reactive voltage droop mode. The secondary circuits of the current transformers for all of the generators are connected in series. Each generator is initially adjusted in order to provide the same output voltage.
When all of the generators have the same current, there will not be any significant voltage output on the secondary windings of any of the generator current transformers. If one of the generators carries more current, then a net difference voltage signal will be created on the burden resistor for that CT. If the current of a generator is out-of-phase with respect to the current of other generators, a net difference voltage signal will be created on the burden resistor for that CT. If the generator is supplying more reactive current than the other generators, the magnitude of the signal that is returned to the voltage regulator will cause a decrease in the generated voltage. This will reduce the amount of reactive current. As the reactive current decreases, the generator voltage will rise back to the nominal voltage. The output current of each generator is lessened to an operating point. All of the generators have an equal amount of load current. This current will be in proportion to the CT ratio. There will be little current or no circulating current between generators.