BOLT 8T4196 - Caterpillar

The parameters that are related to voltage regulation with "Cross Current Compensation" (CCC) are listed below.
Rated generator voltage
Generator PT primary voltage rating
Generator PT secondary voltage rating
Voltage set point
Generator frequency
Knee frequency
Integral gain
Derivative gain
Proportional gain
Loop gain
Generator CT current primary rating
Generator CT current secondary rating
Load compensation mode
Droop percentage
Rated generator currentCross current compensation is often used in order to minimize circulating current flow between the generators that are connected in parallel. The advantage of this operating mode is that all generators contribute in order to establish the same output voltage to the load. Cross current compensation is only used for paralleling multiple generator sets. Cross current compensation is not used when paralleling with a utility.Cross current compensation operation is similar to the reactive voltage droop mode. There is a difference from CCC to the droop mode. For CCC, the secondary circuits of the current transformers of all generators are interconnected in a series string. Each generator is initially adjusted in order to provide the same output voltage.When all generators share the same current, in magnitude and phase, there will be no significant current output on the secondary of any generator CT.Note: The magnitude and phase are according to the CT ratio.A net difference current signal will be created in the CT for a generator if any of the following are true.
One generator carries more current
The current is lagging relative to the others
The current is leading relative to the othersIf one generator is supplying more reactive (lagging) current than other generators, a slight decrease in the generated voltage will occur. The increased reactive (lagging) current causes a change in the phase polarity and magnitude of the signal returned to the DVR. Less reactive (or more leading) current will cause the generator voltage to rise.One goal is to trim the generated voltage and output current of each generator. The desire is to configure the system where all generators will share the same load current.The load current is in proportion to the CT ratio. Another goal is to prevent circulating current between the generators. Droop percentage controls the amount of individual generator voltage droop (or rise) for a given amount of CT signal.The CT secondary circuits are all interconnected. The CT signal seen by any individual regulator is not representative of the actual current flowing in that particular generator. Any display or calculations that might use that signal as if the signal were the actual generator current will provide erroneous results.Reactive voltage-droop must to be selected. An enable contact must be closed in order to enable cross current compensation. Refer to the Testing and Adjusting, RENR7941, "Wiring Diagrams" section for a wiring diagram of the cross current compensation circuit.