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.
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.
2.3.3 impulse voltageIn the normal test atmospheric conditions, device power input circuit, the AC input circuit, output contact circuit and loop between, can withstand the 50s of the standard lightning wave short-time impulse voltage test, open test voltage 5kV.
2.3.4 resistance to damp heat resistance
The device can withstand the damp heat test specified in the twenty-first chapter of the GB7261. The highest temperature test + 40 DEG C, maximum relative humidity of 95%, the test time for 48 hours, each cycle lasted 24 hours of cyclic damp heat test, at the end of the test within 2 hours before according to the requirement 2.3.1, measure the circuits between the conductive circuit foreign Lufei charged metal part and the shell, electrical contact between the insulation resistance is not less than 1.5m ohm, medium compressive strength of not less than 75% of the 2.3.2 provisions of the dielectric strength test voltage amplitude.
The rotor low voltage action criterion equation is：
Kf×Vfd/125 < (P-Pt)/866
3.5 Over load protection
Generator stator winding protective reaction of load generator stator winding overload or fault caused by overcurrent caused overheating winding, discrimination protection generator winding B phase current size, when the current is higher than setting value when the delay send alarm signal.
3.6 compound voltage over current protection
Generator compound voltage over-current protection is as a generator of symmetric and asymmetric short-circuit fault back-up protection, protection discriminant generator three-phase current, AC phase voltage and negative sequence voltage, when any phase current is greater than the fixed value, and AC phase voltage less than fixed value or negative sequence voltage is greater than the fixed value export protection settings have two period of time delay, a movement in solution column or splitting demagnetization, off action to stop, protection can choose to take the current memory function.
3.7 inverse time overcurrent protection
Generator anti time limit over current protection of the generator stator winding current size, the protection of the winding due to the current too large and lead to the stator winding overheating, the protection of the three-phase current size of the judge, from three parts:
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 ＝∣
3.10 stator overvoltage protection
For generator, in particular to a hydro generator, after load rejection due to the speed control of speed control system can not keep up, is easy to appear the stator voltage exceeds the allowed range of over voltage phenomena; at this point to be equipped with over voltage protection, protection from the generator terminal voltage when any phase of more than setting value by setting the delay action to stop.
3.11 stator ground protection
Generator stator grounding protection can for the generator neutral point ungrounded or via arc suppression coil grounding grounding, protection from the generator end opening of the delta winding voltage when open delta windings voltage greater than setting value by setting the exit delay.
1)the maximum phase current of a side is less than 20% of the rated current, it is not sentenced to the side;
2)2) the maximum value of the phase current is greater than 120% of the rated current of the side;
3)3) served as the start of one side of the current than before the start of the increase.In the case of the above three conditions are not satisfied, such as one side at the same time meet the following conditions, then sentenced to CT break:
1)only one phase current is zero;
2) the remaining two phase currents are equal before starting the current.
3.3.2 differential current limit alarmIf the difference is greater than 15% of the rated current, after more than 10s discriminant, issued a warning signal. Differential current limit, but not locked differential protection. The function and the monitoring function of the AC sampling circuit of the protection device
3.4 loss of magnetic protection
Generator loss of excitation protection for generator excitation current abnormal decrease or disappear completely lost magnetic fault protection, by the generator stator impedance as the main criterion, combined with low voltage and generator excitation system low voltage as auxiliary criterion, and have TV disconnection locking function, TV break send alarm signal.
Its action logic is as follows:
device overview
SAI3880D series digital generator protection device with high performance chip supports universal hardware platform, easy to maintain; the Ethernet communication, high-speed data transmission and reliable. Complete localization of Chinese display technology, simple operation.
Based on waterproof, dust, anti vibration design, can be run in a variety of field conditions.
Suitable for capacity of 50MW and below the fire and hydro generator protection.
1.2 main features of the device
An Motorola 32 bit microcontroller technology, the stability and speed of products is guaranteed
The protection. The 14 bit a / D converter, optional measurement module dedicated to the A / D conversion accuracy is up to 24 bits and the measurement indicators easily reach
The purpose of configuration with high capacity RAM and Flash Memory, can record 8 to 50 recorded reports, record the number of events is not less than 1000
An independent tuning of 32 sets of protection setting value, safe and convenient switch
In high precision clock chip, and equipped with GPS hardware circuit for the whole time, system clock synchronization
It is equipped with high speed Ethernet communication interface, and the integration of IEC870-5-103 standard communication protocol
In the electrical design with the machine, no adjustable device
In high grade, quality assurance component selection
An excellent anti-interference performance, panel or installed in the switch cabinet without other anti-jamming module
The purpose of self diagnosis function perfect
The chassis design of waterproof and dustproof and anti vibration.
The purpose of debugging conceptual design
