It is proposed that the turning point in the component current Ir0 is set to 1 times the rated current of the high voltage side to ensure that the turn to turn short circuit in the braking current is less than the rated current Ie Ir, there is no braking effect.
Differential current threshold criterion should not be too small, it is recommended to take Icd = (0.3 ~ 0.5) Ie.
The setting of the ratio braking coefficient can be carried out according to the following formula:
Kcd = Kk (Ktx / Fwc + Fph)
Among them, Kk is the reliable coefficient, take 1.3 ~ 1.5
Ktx for the same type coefficient, take 1
Fwc for the current transformer to allow the error, take 0.1
The Fph for the current caused by current transformer unbalanced relative error is 0.05.
Ratio braking coefficient Kcd recommended range of 0.3 to 0.7.Id =∣
2.2.4 precision of various components
Current component: <5%
Voltage components: <5%
Time element: 0s-1s, the error is not more than 40ms;
1s above, the error is not more than < + 2.5%;
Frequency deviation: <0.02Hz
2.2.5 the entire set of action time (including the inherent time of the relay)
Time of motion of a fast moving segment:
1.2 times the value of the entire set of measurement, not more than 50ms
2.2.6 transient transcendence
No more than 5%
2.2.7 og measurement loop accuracy
Measurement and control device for installing special measurement sub module:
Current, voltage: 0.2
Power and electric degree: 0.5
2.3 insulation performance
2.3.1 insulation resistance
Device for charged and uncharged part and a casing and electrical contact of the circuit between the open circuit voltage of 500V megohm meter measuring the insulation resistance value, normal test atmospheric conditions, the circuits of each class of insulation resistance should not be less than 100m ohm.
2.3.2 medium strengthUnder normal test conditions, the device can withstand the frequency of 50Hz, voltage 2000V lasted 1 minutes of power frequency voltage withstand test without breakdown flashover and component damage. During the test, the other circuit is connected to the ground with the other circuit when the voltage is applied.
3.9 inverse time negative sequence overcurrent protectionPower system occur asymmetric short-circuit and three-phase load imbalance may be the negative sequence current flowing in the stator winding of the generator, and produce harmonic current in the rotor, rotor surface overheating caused, generator's inverse time negative sequence over the protection of rotor flow under the situation not long overheated rotor insulation degradation caused damage to the generator, discrimination protection of generator stator negative sequence current size, consists of three parts:
1) under the time limit: when the negative sequence current is greater than the lower bound value but does not meet the start value of the anti time limit, the alarm ** is delayed by the lower limit;
2) inverse time: when the negative sequence current is larger than the inverse time start value, according to the inverse time lag action equation I22-K t is equal to or larger than a action, type: I2-- generator negative sequence current standard? Value, K - generator operation value of negative sequence current in the standard, a generator rotor surface bear negative sequence current capability of constant;
3) the upper bound limit: when the negative sequence current is greater than the upper bound limit, the upper limit is delayed by the time delay.
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