Asset setpoints (MAXSETAP / MINSETAP)

Fluvius steers the assets behind the connection with two setpoints, both expressed as a percentage. They do not apply at the grid connection point, but at the virtual asset coupling point: the sum of the measurement channels of the registered assets, direction sensitive.

The percentage on the wire means nothing on its own. It is a percentage of a reference power that Fluvius registers per site, and that reference power differs per direction.

The two reference powers

Fluvius records the aandrijfvermogen (drive power) of the installed assets in its DER register, based on the inspection reports that were submitted for the installation. Those registered values, and not the nameplate of the equipment on site, are the base of the percentages.

$$ P_{ref,consumption} = \sum P_{drive}(\text{batteries}) $$

$$ P_{ref,production} = \sum P_{drive}(\text{batteries}) + \sum P_{drive}(\text{PV}) $$

The formulas

Write the allowed net exchange of the asset group as:

$$ P_{allowed,consumption} = \frac{MAXSETAP}{100} \times P_{ref,consumption} $$

$$ P_{allowed,production} = \frac{MINSETAP}{100} \times P_{ref,production} $$

The measured value that is compared against them is the net exchange of the assets themselves:

$$ P_{assets} = P_{charge} - P_{discharge} - P_{PV} $$

A positive $$P_{assets}$$ is consumption and is limited by MAXSETAP; a negative one is production and is limited by MINSETAP.

Turned into a charging limit, which is what the EMS dispatches:

$$ P_{charge,max} = \frac{MAXSETAP}{100} \times P_{ref,consumption} + P_{PV} $$

The local production term is not a bonus: it follows from the setpoint applying to the net exchange. The asset group may always absorb what it produces itself, on top of the cap.

What does not count

The site's own consumption takes no part in it. The building load sits outside the virtual asset coupling point, so it neither raises nor lowers the allowed charging power. What the site draws from the grid is governed by the separate connection-point setpoints (MAXSETP / MINSETP).

Fluvius confirmed for a PV and battery installation that the measurement is the sum of the solar, wind, CHP, storage and other-production channels. The EV and flexible-consumption channels fall outside it: they carry the consumption side of the dossier, which the connection-point setpoints govern. On a Fall-Back Flex connection that is where the registered flexible consumption sits, the battery included when the zone sheet counts it as such, with EV charging always separate in channel 5. See what Fluvius watches during an activation.

Counted versus steered

The sum is taken over the assets registered with the operator, not over the assets the EMS happens to be able to steer. Fluvius decides registration from the single line diagram that shows the Netflex cabinet: an installation drawn behind the cabinet is registered, one drawn outside it is not. That diagram is leading during the certification, for the reference powers as much as for what the operator expects in each measurement channel.

Registration settles four things at once, and Fluvius does not allow them to be split:

• the installation is reported in its measurement channel (channel 1 for PV);
• it is part of the reference power;
• it is steered when the operator limits injection;
• it counts in the sum at the virtual asset coupling point.

A PV that is not drawn behind the cabinet is therefore in none of the four. It is not reported, not part of the reference power, never curtailed by the operator's laws, and it does not net against the battery under MAXSETAP. Reporting a PV in channel 1 only to let it offset the battery, while it is not steered and not in the reference power, is a hybrid form the operator rejects.

Fluvius confirmed: the asset channels carry only the installations that are subject to technical flex, those are the powers that make up the reference powers, and their sum is what happens at the virtual asset coupling point. Production or storage outside technical flex is not to be reported in those channels.

In the EMS that is two settings that have to agree:

A device behind the cabinet has to be steerable. Fluvius steers a registered asset on injection, so a registered PV in unmanaged mode is a configuration error: either enable control on the inverter, or take it out of the asset group and out of the diagram. The EMS raises a warning for every registered device it cannot steer.

While that situation lasts, the EMS keeps the group within the operator's limits as far as it can. A registered PV it cannot curtail still counts in the sum, and the battery is the only knob left:

• Under MAXSETAP the PV helps. Its production nets against the charging, so the battery may take in that much more on top of the cap.
• Under MINSETAP the PV costs room. Its injection fills up the allowed production and the battery has to give way: first by not discharging, and beyond that by charging to absorb the surplus.

At MINSETAP = 0 % that becomes literal: the battery absorbs exactly what the PV produces. If it cannot, because it is full or its power is too small, the limit is not attainable on that installation. This is a fallback that keeps the site as close to compliant as possible, not an arrangement to present at a certification.

The switch and the reference powers answer different questions about the same diagram. The reference power says what the percentage is measured against; the switch says who is in the sum. Both have to agree with the diagram Fluvius holds, otherwise the EMS caps the right group against the wrong base, or the wrong group against the right base. The measurement channels card warns when the switch and the channel of a device disagree, because that is the split the operator rejects.

Worked example

An installation with 1660 kW of registered battery drive power and 110 kW of registered PV:

• $$P_{ref,consumption} = 1660 \text{ kW}$$
• $$P_{ref,production} = 1770 \text{ kW}$$

The grid operator sends MAXSETAP = 8 %, the PV produces 20 kW, and the building consumes 20 kW.

So a battery setpoint of 250 kW charging is too high: with 20 kW of PV it puts 230 kW of net consumption on the virtual asset coupling point, well above the 132.8 kW allowed. The battery is capped at 152.8 kW instead.

Where the reference powers are configured

Both values are set under Configuration → Grid & market → DSO RTU settings, in the Asset reference powers section. It appears for the Fluvius Netflex provider and for the EME eCON+ panel, because both convert the same setpoints.

Which value belongs in each field

The power as Fluvius registered it, from their DER register, which they build from the inspection reports submitted for the installation. That is not the nameplate of the equipment on site, and it is not the access power of the connection.

For De Sweemer, Fluvius registered 1660 kW for consumption and 1770 kW for production, while the nameplates of the same installation add up to 1725 kW and 1825 kW. Ask the operator for the values in their register and enter exactly those.

Leaving a field empty

The EMS then falls back to the installed power of the assets it controls: the sum of the rated power of the batteries for consumption, and of the batteries plus PV for production. That fallback keeps the site steering safely, but it only agrees with the grid operator's arithmetic once the registered values are entered.

Checklist during a certification

1. Ask which reference power the inspector calculates with, and compare it with what is configured on the project. A percentage checks out only if both sides use the same base.
2. Read the reference powers off the platform before the test starts, so any discrepancy is found before a setpoint is sent.
3. Note the PV production at the moment of the test. The allowed charging power moves with it, so a measurement taken a minute later gives a different expected value.
4. Ignore the building load when computing the expected value. It is a common source of confusion during a test, because it does affect the meter at the connection point.
5. Compare against the measured asset power, not against the dispatched setpoint: it is what the assets deliver that Fluvius sees.

Related pages

• How the RTU setpoints are processed: the base of every percentage, the order of the laws and the formula behind each one.
• Fluvius: the Netflex interface, its commands and its measurements.
• Commissioning and certification: how Voltmasters validates and supports the inspection.