Parameters that are related to KVAR regulation are listed below.
:01 - Generator Output Voltage
:02 - Ratio Of Output Voltage To Sensing Voltage
:03 - Generator Type
:04 - Rated Generator Output Current
:05 - CT Voltage At Rated Generator Current
:31 - PF/KVAR Select
:33 - KVAR Reference
:36 - Paralleling Integral Gain
:37 - Paralleling Proportional Gain
Note: Parameters :36 and :37 are only available on part number 155-xxxx or newer.
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. It is not possible to control the system voltage when the generator is connected to an infinite bus. In this instance, it is necessary for the digital voltage regulator to 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
Note: KVAR stands for Kilo-Volt-Ampere-Reactive, which is the unit of measurement for reactive power.
When the digital voltage regulator is in the KVAR operating mode, it regulates so that the generator produces a constant value of reactive power (KVARs), regardless of the real power output of the generator. In this case, the generator power factor will change when the real power output of the generator changes. A current transformer (CT) is necessary for this mode to work.
The KVAR mode is active when parameter :31 is set to a logic 1, and the external switch on terminal 41 is closed indicating that the generator is connected in parallel with utility lines. In KVAR mode, the generator will supply a constant amount of KVARs to the system as set in parameter :33 (or a remote rheostat), regardless of the real power (kW) output of the generator set. The generator will supply real power (kW) to the system as determined by the engine governor and/or load sharing device. It is common that utility loads are too reactive (low power factor), which can cause ampere overloading of the system due to large reactive current requirements. In the KVAR mode, the generator can supply a fixed amount of KVARs to the system to provide a less reactive load, which will improve the power factor of the load and reduce the ampere demand on the system.
A remote PF/KVAR adjust rheostat may be connected in the KVAR mode. When in the KVAR mode (parameter :31 set to 1), the remote rheostat adjustment will override the setting for parameter :33.
For stable operation of the generator in the KVAR regulating mode, the generator must be connected to a utility or system that is much larger than the generator. When the tie breaker is closed to the utility, use the external control switch contact at regulator terminal 41, via the gen/utility 52/a aux contact, to enable the KVAR mode. When the terminal 41 contact logic is open, the regulator will be in a voltage control operating mode with or without droop or line loss compensation as previously described.