In the first installation we experienced this in, a 15 kW Proven turbine was connected to, amongst other load, a 6 kW Windy Boy inverter. This was one of the original 6 kW Windy Boys with the white lid. We noticed however, that as the power rose past 1.3 kW, the inverter would buzz loudly and the lights would flicker significantly. This condition would persist for a second or 2, until power reached about 2 kW, and then stabilised again. The power could drop to below 1 kW again with no problem, but the oscillation would return as it passed 1.3 kW on the way up again. We have not done any more with this one, as the turbine broke down in 2006 and has still not been re-instated. However, that is expected to happen next month, and we will have to deal with the buzzing inverter again....
In the second installation, a 6 kW Proven turbine is connected to a SMC6000A style Windy Boy, the one with the red lid. Soon after commisioning, the customer reported a similar problem in light winds, with the inverter "buzzing", the lights flickering, and also in this in this installation, activation of the mains powered smoke alarm (due to electrical noise rather than smoke!). Neither SMA, nor their UK importer were able to help (although they did propose a number of settings changes to try, the same as with installation 1 above), and the inverter was eventually replaced under warranty. However, this replacement inverter continues to exhibit the same problem, and it it doing the customers nut in, with the fire alarm going off regularly, often in the middle of the night.
The turbine in the second installation broke down recently, and it took a month to get spare parts from Proven. In that time, the fire alarm never went off once, and the lights burned steady, confirming the problem is inverter related.
Recently, we fitted an in line RFI filter in the mains supply to the fire alarm to see if that helps. It hasnt, and we are now having to look at either a power conditioner or even an online UPS in the feed to the smoke alarms. Both are not cheap options, and will only solve the fire alarm problem, not the flickering lights....
Hence the appeal to find out if anyone elese has had this problem with any variant of the SMA inverters, and how it was overcome.
I have again approached SMA and the UK Importer for help, but so far have heard nothing. As I think we drew a blank with both last time round, I'm not too hopeful again this time! In case 2 above, its doing my nut in as much as it is the customers! As an electrical engineer, I cannot see any likely scenario on the grid that could cause this, but would welcome any suggestions!
|SMA Inverter Oscillation||Bryan Rendall - 8/06|
|Re: SMA Inverter Oscillation||Ted Marynicz - 9/06|
|Re: SMA Inverter Oscillation||Stuart - 9/06|
|Re: SMA Inverter Oscillation||Bryan Rendall - 30/06|
|Re: SMA Inverter Oscillation||Ted Marynicz - 1/07|