:01 - Generator Output Voltage
:02 - Ratio of Output Voltage to Sensing Voltage
:03 - Generator Type
:04 - Rated Generator Output Current
:05 - Current Transformer (CT) Voltage at Rated Generator Current
:06 - Knee Frequency
:15 - Voltage Gain
:16 - Integral Gain
:17 - Proportional Gain
:22 - Droop/CCC Select (only on part number 155-xxxx and later)
:30 - Droop Percentage
There are two primary objectives for parallel generator operation.
- The generators are to share the real power requirements of the electrical load.
- The generators are to share the reactive power requirements of the electrical load.
The engine governors will control sharing of the real power requirements (kW) and the voltage regulator will control sharing of the reactive power requirements (KVAR) of the total system load.
If the output voltage of one generator is slightly higher than the other generators, the generator will supply a lagging reactive current to the other generators that are connected to the group. The lagging reactive current will circulate between generators. The lagging reactive current can cause ampere overloading. One method that can be used in order to minimizing this effect is to cause the output voltage of an individual generator to sag, or "droop", in proportion to the lagging reactive current. The lagging reactive current value must be measured via a current transformer (CT).
For proper reactive load sharing, the regulator must know the rated generator output current (parameter :04), the CT voltage at rated generator current (parameter :05) and the desired percentage of output voltage droop (parameter :30) when the generator is at rated reactive output current.
As reactive lagging generator output current increases, the regulator will cause the output voltage to droop (lower the voltage) proportionally. If the measured reactive output current is leading, the output voltage will rise. In either case, this action will tend to reduce the reactive current for better KVAR sharing with other units.
The droop percentage (parameter :30) controls the amount that the generator output voltage will vary for a given amount of reactive current. The polarity must be correct for the CT that is connected for the voltage to droop with the lagging current flow. The line loss compensation voltage gain (parameter :15) function can adversely affect load sharing. For reactive droop to work properly, parameter :15 should be set to zero.