> For the complete documentation index, see [llms.txt](https://docs.voltmasters.io/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.voltmasters.io/dso-rtu/fall-back-flex.md).

# Fall-Back Flex (Fluvius)

**Fall-Back Flex** is a temporary connection formula from Fluvius for new or reinforced connections (from 100 kVA) in areas with grid congestion. The customer connects at the **full requested capacity**; in return, the installation must temporarily reduce its offtake to a **setpoint** whenever Fluvius signals local congestion. The formula lapses once the planned grid investment in the zone is completed, or it is converted into a flexible connection agreement (FAO).

Fall-Back Flex is not a separate connection to the EMS: it runs **on top of the Fluvius Netflex telecontrole connection**. Fluvius sends the setpoint through the same RTU and the same IEC 60870-5-104 interface described in [Fluvius](/dso-rtu/grid-operators/fluvius.md).

{% hint style="info" %}
Whether a connection qualifies for Fall-Back Flex is determined by the Fluvius zone sheets. The commercial parameters (the reduced power the customer committed to) come from the bid form agreed with Fluvius.
{% endhint %}

### The two power levels

A Fall-Back Flex connection is defined by two power levels:

| Level       | Meaning                                                                                             |
| ----------- | --------------------------------------------------------------------------------------------------- |
| **P\_base** | The full contractual capacity of the grid connection. Outside activations this is the only limit.   |
| **P\_red**  | The reduced power from the awarded bid: the maximum net offtake during a Fall-Back Flex activation. |

Everything between P\_red and P\_base is the **flexible volume**: the share of the connection the installation must be able to give up when Fluvius activates.

### How an activation works

1. Fluvius detects local congestion and sends a **max consumption setpoint at the connection point** (`MAXSETP`, as a percentage of the contractual capacity) with reason code `1` (grid congestion) through the Netflex RTU.
2. The EMS treats the setpoint as a hard constraint and reduces net offtake **within 3 minutes**, following the project's [load shedding priorities](#load-shedding-priorities).
3. The installation stays at or below the setpoint for the **entire control period**, while the EMS keeps reporting feedback and measurements back to Fluvius every 30 seconds.
4. When Fluvius releases the signal (reason code back to normal, setpoint back to 100%), the EMS restores normal operation.

Activations are possible **24/7**. Because the controller runs locally and the RTU link does not depend on an internet connection, activations are also executed correctly during connectivity problems.

### Enabling Fall-Back Flex

Fall-Back Flex is enabled inside the telecontrole configuration:

1. Go to **Settings → Project settings → Telecontrol** and select **Fluvius** as the DSO RTU provider (or open the existing Fluvius configuration).
2. Enable the **Fall-Back Flex** option.
3. Enter **P\_red**, the reduced power from the awarded Fluvius bid.

P\_base is taken from the project's grid settings, so only the reduced power needs to be entered. The form shows the resulting flexible volume so you can verify it against the bid form.

<div data-with-frame="true"><figure><img src="/files/XypNm3JZzvDjX7hPlxT5" alt="Voltmasters EMS: Fall-Back Flex option in the Fluvius telecontrole settings"><figcaption><p>Fall-Back Flex is enabled inside the Fluvius telecontrole configuration: P_base comes from the grid settings, only P_red is entered.</p></figcaption></figure></div>

### Load shedding priorities

During an activation the EMS must remove the difference between the current net offtake and the setpoint. Which assets are used for that, and in which order, is configured under **Settings → Project settings → Load shedding priorities**.

* The list contains every controllable asset with its **controllable power** and its **control capability**: assets that can *modulate* are limited gradually; assets that can only *switch* are turned off entirely.
* Drag assets (or use the arrow buttons) to change the order. Assets can also be excluded from shedding.
* By default the **battery** is first: blocking charging and discharging to cover offtake is invisible to the site's operation. EV charging typically follows, and switched loads (boilers, heat pumps, process loads via the IO module) come last.
* A coverage indicator compares the total controllable power against the required reduction (P\_base minus P\_red), so you can see whether the priority list can always honour an activation.

{% hint style="info" %}
The same priority list is used for the standard grid-limit protection of the project, so the shedding behaviour is consistent whether the constraint comes from Fluvius or from the project's own grid settings.
{% endhint %}

<div data-with-frame="true"><figure><img src="/files/8z1jbatEwUbMp3QMf18y" alt="Voltmasters EMS: project-wide load shedding priorities with drag-and-drop ordering and a coverage indicator"><figcaption><p>The project-wide load shedding priorities: battery first, with per-asset control capability and a coverage check against the required reduction.</p></figcaption></figure></div>

### Monitoring

Projects with Fall-Back Flex enabled get a dedicated **Fall-Back Flex dashboard** in the project menu:

* **Status banner**: whether an activation is currently running, since when, and the measured response time.
* **Grid connection bar**: the contracted capacity, the currently enforced limit and the actual net offtake in one view, including the share of the connection that is temporarily unavailable.
* **Power chart**: net offtake versus the enforced limit over time, showing the ramp-down at the start of an activation.
* **Shedding execution**: per asset, in priority order, how much power was removed and how (limited, switched off or blocked).
* **Activation history**: past activations with duration, deepest setpoint, response time and the number of quarter hours the installation stayed below the setpoint.

<div data-with-frame="true"><figure><img src="/files/jdIr3o0fHSCPX4etmmAA" alt="Voltmasters EMS: Fall-Back Flex dashboard with status banner, grid connection bar, power chart and shedding execution"><figcaption><p>The Fall-Back Flex dashboard during an activation: status banner, grid connection bar, net offtake versus the enforced limit, and the shedding execution per asset.</p></figcaption></figure></div>

The **EMS dashboard** also shows a Fall-Back Flex tile with the live status and a per-asset icon row, so an ongoing activation is visible at a glance without opening the dedicated dashboard.

<div data-with-frame="true"><figure><img src="/files/AKpVmnP0Rf4KHA0qOQ10" alt="Voltmasters EMS: Fall-Back Flex tile on the EMS dashboard showing an active modulation and per-asset icons"><figcaption><p>The Fall-Back Flex tile on the EMS dashboard: live status, the enforced setpoint and per-asset icons.</p></figcaption></figure></div>

### Frequently asked questions

<details>

<summary><strong>Is Fall-Back Flex the same as telecontrole?</strong></summary>

No. Telecontrole (DSO RTU) is the generic control link with the grid operator. Fall-Back Flex is a specific connection formula that uses that link: Fluvius sends its congestion setpoints through the same Netflex RTU. A project can have Fluvius telecontrole without Fall-Back Flex, but not the other way around.

</details>

<details>

<summary><strong>Where do P_base and P_red come from?</strong></summary>

P\_base is the contractual capacity of the grid connection and is taken from the project's grid settings. P\_red is the reduced power the customer committed to in the Fluvius bid form; it is entered once when enabling Fall-Back Flex.

</details>

<details>

<summary><strong>What if the controllable power does not cover the required reduction?</strong></summary>

The load shedding priorities page compares the total controllable power of the included assets against the required reduction (P\_base minus P\_red) and warns when it falls short. In that case, add more assets to the list (for example loads switched through the IO module) or review which assets are excluded.

</details>

<details>

<summary><strong>Does an activation switch everything off?</strong></summary>

No. The EMS removes only the power needed to reach the setpoint, in the configured priority order. Assets that can modulate are limited rather than switched off, and assets lower in the list are left untouched when the reduction is already covered.

</details>

<details>

<summary><strong>How long does Fall-Back Flex apply?</strong></summary>

The formula is explicitly temporary: it lapses once Fluvius has completed the planned grid investment in the zone, or it is converted into a flexible connection agreement (FAO). The telecontrole connection itself remains in use afterwards.

</details>


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