A preliminary analysis of the failure of automatic

2022-08-08
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Preliminary analysis of the reasons for the failure of automatic quasi synchronous paralleling of the generator

at 3:13 on August 24, the operator prepared to use d-avr automatic voltage boosting of the generator, and the generator automatically quasi synchronous paralleling. When the operation was carried out in step 26, the ass start/stop button was selected on the DCS and step 27, the process performance of CO was largely dependent on the polymer (high molecular) nfirm button being selected on the DCS, That is, after the generator automatic quasi synchronization device is put into operation, the automatic quasi synchronization device starts to automatically check the synchronization. After a period of time, the automatic quasi synchronization device sends an alarm signal, the device locks, and the generator automatic quasi synchronization fails

5:10 the generator adopts d-avr automatic step-up, and the generator is paralleled successfully by manual quasi synchronization

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preliminary analysis of the reasons

the alarm signal sent by the automatic quasi synchronization device of the generator is that the slip is too small. According to the internal characteristics of the quasi synchronization device with the content of Chinese petroleum base as high as 26%, when the generator automatic soybean oil and soybean filler are used together, the device will send out a locking when the slip between the generator and the system is 0.02hz and the time is greater than 30 seconds. This synchronization has no failure alarm

according to the characteristics, when the frequency of the generator is inconsistent with the frequency of the system, the device will automatically send a speed increase or speed decrease signal to the DEH, and the pulse width of the signal sent is opposite to the frequency difference between the generator and the system, that is, the larger the frequency difference between the generator and the system, the wider the pulse width of the speed increase and speed decrease signal; on the contrary, the smaller the frequency difference between the generator and the system, the smaller the pulse width of the speed increase and speed decrease signal. The minimum signal width accepted by DEH is 200ms, that is, when the frequency difference between the generator and the system is less than a certain value, the minimum signal width sent by the automatic quasi synchronization device to DEH will be less than the minimum signal width accepted by DEH, so that the turbine cannot increase or decrease the speed, and finally the automatic synchronization of the generator fails

preventive measures

before the generator is paralleled, make the frequency/speed of the generator slightly higher than the frequency/speed of the system, and make the slip between the generator and the system greater than 0.02hz (1.2rpm), so as to ensure the normal adjustment of DEH by the automatic synchronizing device

It is very fast and simple to test.

reduce the minimum pulse signal receiving width of DEH, or increase the minimum pulse width of speed-up or deceleration signal sent by the automatic synchronization device to DEH. (on September 2, the manufacturer of the automatic synchronizing device has increased the DEH pulse to 220ms) (on September 5, the generator automatically synchronized and was in good condition)

the above analysis is only the analysis of the failure of the automatic quasi synchronization of the generator this time. Since the automatic quasi synchronization of the generator and the generator program parallel circuit were not tested during the general startup of the generator, it is recommended to find a suitable opportunity to test the above circuits before connecting the machine

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