Hi all,


Firstly thanks for the replies and apologies for not coming back for far too long.

 

When comissioning on site however I would have thought it would be difficult simulate many of those conditions (you obviously can't mess with the real grid so you'd almost need your own little power plant with controllable frequency to simulate nasty grid conditions) - so would have imagined that the test would be just to open a handy disconnector between the inverter and the grid and time how long it takes the inverter to notice and disconnect - in effect simulating an extreme case for all the monitored variables all at the same time. So in a way the on-site test produces a time, but it can't be related to any particular detection method.

As an aside, an example of what I've normally seen used for commissioning external LOM protection relays. I've never seen it done for type-tested kit though, and only with VS or ROCOF for the LOM.

 

Indeed, and this is the reason behind the certificated “type tested” inverters, whether they are certified to G.59, G.83, or the newer G.98 or G.99 standards. If however you modify one or more of the inverter parameters, the type-test certificate becomes invalid and my understanding is that the inverter can no longer be legally connected to the public supply without re-certification. 

There has been a change to the Grid Code that requires all mid-sized generators to change their settings, retroactively. Yes, the DNO requires notification, and yes there are specific considerations re type tested units. Finding out what the LOM method is just the first step!

It will be stated on the type-test certificate, either directly, or due to the values quoted. 

That's what I had thought! But for example, see the attached test certificate... I can see that it remains stable for certain VS and ROCOF events, but the actual detection method isn't stated, insofar as I can tell. If I'm looking in the wrong place, please say!


Needless to say, I have heard nothing back from this manufacturer.


Thanks,

Jam

Hi all,


Firstly thanks for the replies and apologies for not coming back for far too long.

 

When comissioning on site however I would have thought it would be difficult simulate many of those conditions (you obviously can't mess with the real grid so you'd almost need your own little power plant with controllable frequency to simulate nasty grid conditions) - so would have imagined that the test would be just to open a handy disconnector between the inverter and the grid and time how long it takes the inverter to notice and disconnect - in effect simulating an extreme case for all the monitored variables all at the same time. So in a way the on-site test produces a time, but it can't be related to any particular detection method.

As an aside, an example of what I've normally seen used for commissioning external LOM protection relays. I've never seen it done for type-tested kit though, and only with VS or ROCOF for the LOM.

 

Indeed, and this is the reason behind the certificated “type tested” inverters, whether they are certified to G.59, G.83, or the newer G.98 or G.99 standards. If however you modify one or more of the inverter parameters, the type-test certificate becomes invalid and my understanding is that the inverter can no longer be legally connected to the public supply without re-certification. 

There has been a change to the Grid Code that requires all mid-sized generators to change their settings, retroactively. Yes, the DNO requires notification, and yes there are specific considerations re type tested units. Finding out what the LOM method is just the first step!

It will be stated on the type-test certificate, either directly, or due to the values quoted. 

That's what I had thought! But for example, see the attached test certificate... I can see that it remains stable for certain VS and ROCOF events, but the actual detection method isn't stated, insofar as I can tell. If I'm looking in the wrong place, please say!


Needless to say, I have heard nothing back from this manufacturer.


Thanks,

Jam