I have a self-consumption system consisting of a Victron Multiplus II 48/5000/50-70 AC-coupled to the grid, three Hoymiles HMS-2000-4T microinverters, one HMS-1000-2T, and a 15 kW Felicity battery. The peak power is 7 kW, but I rarely exceed 6 kW (a complicated roof with several orientations and inclinations. Hence my decision to use microinverters).
The thing is, I’ve been testing frequency shifting for some time to ensure that the power is adjusted in the event of a grid failure, when the battery is full and the loads are low, but I still can’t get it to work properly.
Can anyone tell me whether this function is enabled in the microinverters with the grid-Profile ES-RD1699 file, and which parameters I should set in the Victron ESS under Frequencies?
Good morning,
You should contact the inverter manufacturer to confirm whether they support frequency shifting and, if so, what the appropriate parameters are.
I’ve already done that, and it hasn’t made any difference.
It supports it, but the parameters defined in the Grid file are far too restrictive. It starts at 50.2 Hz, and for microinverters at 51 Hz. It turns out that the damping curve is defined (at a maximum of 100%/Hz), which means that it needs one hertz to modulate production fully.
If you have 5 kW of production, with the batteries full and a load consumption of 250 W, you need the full modulation range to prevent the microinverters from shutting down, because otherwise they enter a loop (the microinverters stop; when there is no production, the Victron lowers the frequency, and the cycle starts again).
In other words, the parameters they have defined are inconsistent!!
I have exchanged surreal emails with technical support, where they basically tell me that this is indeed how it is, but that I should be understanding.
So, they simply can’t be bothered to fix it.
It would be as simple as modifying the file, getting it certified again and making it available. But… that seems to be a lot of work!!!
Hi, I don’t understand: “If you have 5 kW of production, it would be full, and consumption by the load would be 250 W, you need the total modulation so that the micros don’t come to a stop, because otherwise they enter a loop (the micros stop; when there is no production, the Victron lowers the frequency and it starts all over again).”
The RD parameters cannot be modified, because otherwise the system would be out of compliance.
Frequency shifting works based on the battery voltage. In other words, it starts increasing the frequency when the battery voltage reaches the absorption voltage, and finishes raising it to the configured limit when the battery enters the float stage.
I don’t know or understand how microinverters work. R
Frequency Shift cannot operate based on battery voltage values. Let me give you an example:
I have 5 kW of generation at my installation. My battery is at 90% SoC and starts reducing the charging current, as all LFP batteries do. As a result, it consumes 800 W from the PV generation. In my house, I have another 2 kW of consumption, and I feed the remainder into the grid (that is, 2.2 kW).
Suddenly, the electricity grid goes down. The battery voltage and its charging current remain the same, as does the household consumption.
What does the inverter do with the 2.2 kW that it was previously feeding into the grid, but now cannot because the grid is unavailable due to the lack of a reference voltage? (In other words, we switch to island mode.)
Well, it increases the frequency of its internal grid in an attempt to make my microinverters reduce their output until generation and consumption are equal, thereby preventing overvoltage. And that is where the incompatibility between Victron and Hoymiles arises.
But this is not something I have discovered myself. There are numerous cases on this very channel reporting the same thing.
The problem lies in the parameters Hoymiles has defined in the *_RD file, since from its start frequency to its stop frequency (for this function), you would need to define a ramp of at least 110 or 120, whereas you only have 100. As a result, because it cannot modulate the generation (especially at the end of that ramp with low consumption), it keeps increasing the frequency until it shuts down the microinverters. When the microinverters stop, the overvoltage temporarily disappears. The Victron lowers the frequency, and the whole process starts again.
But I am surprised that you are unfamiliar with the issue.
If you configure the ESS assistant correctly, it should reduce smoothly as you need. I don’t think I’m understanding you, but if you set 50.2, 51 and 51.5 in the frequency section of the ESS assistant, it should regulate it. What values do you have set here:
The problem isn’t the Victron; it’s the microinverters, whose parameters are inconsistent in the grid profile file they use (the one that activates the Frequency function in them, the one ending in _RD).
The inconsistent parameters are:
Start frequency: 50.2 Hz
Stop frequency: 51.0 Hz
Derating slope: 100%/Hz (This means that, to derate by 100%, they need at least a 1 Hz difference between the stop and start frequencies.)
Do you realise that, no matter how you configure the Victron, there’s no solution to this problem? And you can’t modify those parameters in that file (the stop and start values, so that there’s that 1 Hz difference). Another solution would be to set the slope to 120%/Hz, but the maximum value is 100.
Hoymiles needs to provide the solution by generating and certifying another file, but they DON’T WANT TO.
I can show you countless replies from first- and second-level support saying that the file is like that and appealing to my understanding.
And if you want, I can send you a PDF copy of that profile and you can see it for yourself (although in that format you can’t see the ranges within which those same parameters vary).
Good morning, and sorry for the delay. I’ve had very little free time.
The parameters I’ve entered are the same as those in the microinverters’ grid profile file: the start frequency, the maximum curtailment frequency and the shutdown frequency.
I then tried increasing and decreasing the shutdown frequency slightly, but in every test either it shut down due to overvoltage (it didn’t stop in time), or it completely shut down the microinverters (between 500 and 800 W of output).
As I said, this problem only occurs when the microinverters have to operate at low output.
So, you say at the lower part it starts to be unstable.
Set the Victron from 50.05 or 50.10Hz to 51.00Hz, and test again, maybe that helps.
Are you absolutely sure that the hoymiles micro inverters are programmed as you say, as they might be programmed for another region or install (grid connected only) and might not reduce at all, as that sometimes happens when you buy over the internet and not in your local country, or the vendor bought such batch oversees.
If the problem persists, contact your vendor and let them send the correct ones.
Good evening.
That configuration you mentioned has already been tested.
As for the microinverter parameters, I already told you in previous comments that I contacted Hoymiles support, both first- and second-line. If the microinverters were unsuitable, or had inappropriate firmware or a faulty grid file, they would have told me.
However, they limit themselves to asking for my understanding.
In any case, there are several threads on this very forum reporting the same issue, both in English and German.
