We operated 200 KW Solar System and 200 KVA Diesel Generator in Island mode , a lot of humming was observed from DG, light ,fans air conditioner?
When the solar was disconnected DG alone was good .
When grid is available solar-Grid works well. But Solar-DG there are problems ?
Not able to understand..
Unfortunately you don't give a lot of detail to help analysing the issue. I suspect however that the humming you observe is simply the normal operation of the DG which isn't doing anything when the grid is connected, but has suddenly found itself having to supply real power when the grid is off. If you run the generator with both solar and grid disconnected, driving only the load, does it still hum? Is the hum just a mechanical resonance? Which bit is humming? Are the voltage and current figures reasonable? Is the load reactive, if so how much? Does it seem to be overheating?
With a high probability, the mentioned symptoms are evidences of voltage and current waveform distortions. You need to measure (or to simulate) the used inverter(s) to see the levels of individual harmonics, and the THD. Harmonics filtering device(s) may be required to restore the waveforms to acceptable shapes with the inverter(s) connected. For a safe choice, you may need to refer to a suitable standard.
We have Measured data at the Main Bus (Sub Station ) of our institute taken through the Power Quality analyzer ..But the harmonic contents are less than 1% . Even harmonics are absent...only 3rd and 5th are present .higher order odd harmonics are absent.we have 50KW * 4 inverters of Delta. but analysis at the ...
Inverter terminals we have not taken.
I suggest checking the levels of harmonics at the terminals of individual components instead of the PCC. In addition, you may also check the synchronisation between the DG and the solar-PV generator; there might be some slip.
Soorya, you said " When the solar was disconnected DG alone was good . " - when the solar was disconnected was the grid also disconnected? How much power was the DG supplying in this condition? I still think this is a non-problem; the DG naturally makes more noise under full load.
Actually on that day there was a Power Cut from the Grid, hence the system was in Islanded mode . Initially we operated both Solar and DG for about 01 Hour and found that , the DG was also making some different noise and big fume release for some duration . After that it is ok for sometine...then again repetition .
In the absence of solar ,the DG alone was connected to about 40% of its capacity. Finally, The Solar of 100KW was again added for small trial duration of 10 minutes ...as soon as it was connected ..same problem occurred with DG ....though Solar was taking about 108 Ampere of 503 amperes of the total load .
Also the cap. bank was not working...which works well when Grid-Solar combination works and the pf remains about 1.0 .
While analyzing we found following :
1. The DG terminal voltage is about 405 to 410 (somewhat less than the rated voltege ) which further decreases with rise in load.
2. The phase sequence of DG and the Solar Inverters have a mismatch ...
.....we hope to resolve this as soon as cloudy season is over ...
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