L
Len Howe
Hi,
if you are having high amp draws and poor power factor, then you need better droop current compensation installed on each unit's AVR (automatic voltage regulator). Besides speed control, generators require voltage control. Like the other authors suggest having one generator operate in isochronous mode (frequency control) and the other gens in droop speed control (followers) The voltage regulators must be set up in the same way. One of the four 2MW generators should have the voltage droop mode off (this unit sets the voltage of the system grid). The other 3 2MW units should operate in voltage droop mode (following). Using this method you will not get circulating current between generators because the three units paralleled in droop mode will not "push" the voltage up or pull it down. A simple current droop compensation circuit requires a CT (current transformer), a resistor (a load which builds a voltage when current is passed through it, and a transformer (basically an amplifier) to boost that ac voltage formed on the resistor. This circuit is installed on each generator and a switch can short the CT current effectively disabling droop compensation. Also the output of the transformer is connected in series with the voltage sensing of the AVR voltage regulator. Depending upon the direction of the current the voltage sign either adds or subtracts from the nominal sense voltage. Thus this negative feed back circuit protects each generator against high circulating current (over current tripping)and poor PF power factor etc.
Hope this helps.
Len Howe AET Avionics.
My e mail is lenhowe at cintek dot com.
if you are having high amp draws and poor power factor, then you need better droop current compensation installed on each unit's AVR (automatic voltage regulator). Besides speed control, generators require voltage control. Like the other authors suggest having one generator operate in isochronous mode (frequency control) and the other gens in droop speed control (followers) The voltage regulators must be set up in the same way. One of the four 2MW generators should have the voltage droop mode off (this unit sets the voltage of the system grid). The other 3 2MW units should operate in voltage droop mode (following). Using this method you will not get circulating current between generators because the three units paralleled in droop mode will not "push" the voltage up or pull it down. A simple current droop compensation circuit requires a CT (current transformer), a resistor (a load which builds a voltage when current is passed through it, and a transformer (basically an amplifier) to boost that ac voltage formed on the resistor. This circuit is installed on each generator and a switch can short the CT current effectively disabling droop compensation. Also the output of the transformer is connected in series with the voltage sensing of the AVR voltage regulator. Depending upon the direction of the current the voltage sign either adds or subtracts from the nominal sense voltage. Thus this negative feed back circuit protects each generator against high circulating current (over current tripping)and poor PF power factor etc.
Hope this helps.
Len Howe AET Avionics.
My e mail is lenhowe at cintek dot com.