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ms-ust asked

Loss of Mains Settings remain active eventhough they have been disabled

We have a three phase Multi setup. We mostly control it in external mode. Using the VE.Bus Quick Configure we diabled the loss of mains protection yet we observe this setting to be inherent. For any deviation in ROCOF greater than 0.2Hz/s, the multi's disconnect from the network. Could you please provide some further infroamtion on how this can be completely disabled? Is this a software bug or some additional settings need to be changed?

ESS
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Johannes Boonstra (Victron Energy Staff) avatar image
Johannes Boonstra (Victron Energy Staff) answered ·

As the switchable LOM detection is a add on to the default detection and is there to have the system comply to local grid certification. This added on prtection can be changed/switched off. The basic loss off mains protection will always be active as otherwise there can be power on the input, even with nothing connected there.

There is/will be no option to disable the standard algorythm

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ms-ust avatar image ms-ust commented ·

Thanks Johannes. We understand the issue with backfeed that you have raised.

As the website states "Besides choosing Type A and B, it is also possible to disable the LOM entirely. Note disabling the LOM on an input connected to the grid is only allowed when other external safety equipment is installed." We can confirm that we have external safety equipment installed.

In addition, we would also like to understand if the RoCoF protection can be relaxed rather than being totally disabled. As the current protection stands at 0.2Hz/s, can this be relaxed to 1Hz/s for example? As you might be aware, the more recently proposed grid codes require for smaller generation to have more relaxed LOM as stated below:

"The NIE Networks D-Code now requires all Small Scale Generators to amend their Interface Protection (G59) Settings in line with paragraph CC7.11, the new settings are given in Table 1 below, and in summary the main changes are: · Amendment of Loss of Mains (LoM) protection to a RoCoF setting of 1Hz/s with a 500ms time delay, Vector Shift is no longer allowed as a LoM protection. " Link: https://www.nienetworks.co.uk/documents/d-code/nto-3002-generator-interface-protection-%28guidance.aspx

"According to CENELEC TS50549-1/-2 generating units connected to LV networks with rated current above 16A as well as those connected to MV networks shall be able to operate with rates of change of frequency up to 2,5 Hz/s " Link: https://docstore.entsoe.eu/Documents/Network%20codes%20documents/Implementation/CNC/IGD-RoCoF_withstand_capability.pdf

@egs.ust

Thanks again for your prompt response and look forward to hearing from you.

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ehsab avatar image ehsab commented ·
@Johannes Boonstra (Victron Energy Staff)

What are the default limits when LOM is disabled?

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