Three、Software function deion
3.1. differential quick break protection
When any phase difference current is greater than the value of the differential speed, the protection action is stopped. Fast removal of generators in the case of a serious fault in the area of the generator. Differential speed determine the value should be able to avoid the external fault of the maximum unbalanced current, and taking into account the current transformer saturation factor, generally take 3 to 8 times the rated current
3.2.Ratio differential protection
Using the conventional ratio differential principle, the equations of motion are as follows:
Id > Icd （Ir Ir0）
Id - Icd > Kcd ·(Ir- Ir0) (Ir ≥ Ir0)
At the same time to meet the above two equations, the ratio of the differential element action. Among them, Id for the differential current, Ir for the braking current, Kcd for
Ratio braking coefficient, Icd is the threshold value of the differential current, and Ir0 is the turning point of the current value.
1)under the time limit: when the three-phase current is greater than the lower limit of the value of any phase, but not meet the anti time limit start value, press the lower limit delay action on the alarm signal;
2) inverse time: when the three-phase current any phase current is larger than the inverse time starting value, according to the inverse time lag action equation I2-1 t is greater than or equal to K acts, type: I for the generator current standard? Value, K - generator stator winding allows thermal time constant.
3) the upper bound limit: when the three-phase current is greater than the upper limit value, the time limit is delayed by the time limit.
3.8 transverse differential protection
Generator transverse differential protection is usually used for the reaction of generator stator winding inter turn short circuit and a parallel windings open welding, protection from the generator neutral point between two branch imbalance fundamental current, but current is greater than fixed value setting delay action on the alarm or trip.
1.3 function configurationFunction configuration of SAI3880D digital generator differential protection deviceDifferential quick break, ratio brake differential, CT disconnection locking differential, CT disconnection alarm, stator overvoltage protection, stator ground fault protection, overload alarm, anti time overcurrent protectionFunction configuration of backup protection device for SAI3881D digital generatorTransverse differential protection, loss of excitation protection, rotor one point grounding protection, rotor two points grounding protection composite voltage over current protection, inverse time negative sequence overcurrent protection, Pt disconnection alarm, non electricity protection (generator water shutoff, and the generator thermal, generator excitation accident, main steam valve closed),
