Note: KVAR is the unit of measurement for reactive power.
- 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
- Rated generator current
- Generator CT current primary rating
- Generator CT current secondary rating
- Operating mode
- VAR set point
- VAR integral gain
- VAR loop gain
When the generator is connected in parallel with an infinite bus (utility), the voltage of the generator is controlled by the infinite bus. The voltage of the generator will change as the infinite bus voltage changes. The system voltage cannot be controlled when the generator is connected to an infinite bus. In this instance, the digital voltage regulator must regulate the reactive power output which is supplied by the generator. There are two methods for regulating the reactive power output.
- KVAR regulation
- Power factor (PF) regulation
When the digital voltage regulator is in the KVAR operating mode, the digital voltage regulator works to produce a constant KVAR output. The constant KVAR output of the DVR is regardless of the real power output of the generator. In this case, the power factor (generator) will change when the real power output of the generator changes. A current transformer (CT) is necessary for this mode to work. KVARmode must be selected in software. One method to select the KVAR mode is with the "Metering" screen in the CDVR PC software. Another method to select the KVAR mode is with the use of the "VAR/PF Mode Selection" screen in the Cat ET. The contact for the KVAR/PF enable must also be closed. Refer to the following contacts: "P9-6" and "P9-9".
A remote KVAR/PF adjust toggle switch may be used in order to fine-tune the KVAR set point. Refer to the following contacts: "P9-4", "P9-5" and "P9-6". The KVAR/PF toggle switch may be the same switch used for remote voltage adjustment. When the contact for KVAR/PF is closed, and the KVAR mode is selected, the switch will not affect voltage.
Note: The KVAR/PF (auxiliary breaker) contact does not specify if the CDVR is in KVAR or PF mode specifically. KVAR mode must be selected in software (at the "Metering" screen in the CDVR PC software, or under the "VAR/PF Mode Selection" screen in Cat ET.
Note: When operating in parallel operations, make sure that "Droop" mode is selected in the "Settings" screen in the PC software. A 0% droop may be selected.
In KVAR mode, the generator will supply a constant amount of reactive power to the system. The amount of reactive power is determined by the reference (KVAR), regardless of the real power output (kW) of the generator set. The generator will supply real power (kW) to the system. The supply of real power is determined by the engine governor and/or the device that is used for sharing the load. Due to the amount of reactive power on the utility, current overloading of the system (due to large reactive current requirements) is possible. In the KVAR mode, the generator can supply a fixed amount of reactive power to the system.
For stable operation of the generator in the KVAR regulating mode, the generator must be connected to one of the following:
- A utility
- A system that is much larger than the generator
When the tie breaker is closed to the utility, connect terminal "P9-9" and terminal "P9-6" in order to enable the KVAR mode. If terminals "P9-9" and "P9-6" are disconnected from each other, the regulator will be in a voltage control operating mode. The regulator will be in a voltage control operating mode with or without the following:
- Droop
- Line loss compensation