# Day-ahead planning

> How the Voltmasters controller reads the Fluvius day-ahead plan for Fall-Back Flex: polling and read receipts, the stricter of plan and live limit, programs and reference powers, and the battery preparation.

Source: https://voltmasters.io/en/docs/dso-rtu/grid-operators/fluvius/fall-back-flex/day-ahead-planning/

In some congested zones Fluvius also publishes its limits **one day ahead**, per quarter hour, through its planning API. The zone sheet states whether that applies: *Mandatory implementation of day-ahead steering: yes*. The controller then knows the limits in advance and prepares the battery for them.

## What the controller does

| Step | What happens |
| --- | --- |
| **Fetch** | Polls the Fluvius planning API every minute, authenticated with the client certificate. |
| **Confirm** | Sends Fluvius one read receipt per new version of the plan. A failed receipt is retried four times over about 7 minutes. |
| **Keep** | Stores the plan locally. It stays valid during an internet outage and after a restart. |
| **Apply** | Per quarter hour, the **stricter** of the planned limit and the live Netflex limit applies. |
| **Prepare** | Hands the planned quarter hours to the battery schedule (see below). |

A plan version that cannot be read is refused. The previous version then stays in force. Fluvius withdraws a planned limit by publishing the quarter hour again at 100 %.

## Battery preparation

-   Before a planned limit, the battery **charges** in the cheapest earlier quarter hours that have room, whatever the price.
-   During the planned limit, the battery **discharges** to cover the expected excess.
-   Controllable loads are not switched in advance. They are only held back when the live measurement asks for it.
-   The preparation takes precedence over trading signals. With the **Self supply** strategy the battery is not prepared.

## Programs

Fluvius publishes one **program** per steering product. The plan does not say which reference power its percentages use, so you map every program id in the [settings](https://voltmasters.io/en/docs/dso-rtu/grid-operators/fluvius/fall-back-flex/configuration/#day-ahead-planning):

| Reference power | Typical program | Pairs with |
| --- | --- | --- |
| **Connection point** | Fall-Back Flex | `MAXSETP` (consumption) and `MINSETP` (injection) |
| **Assets** | T-Flex day-ahead | `MAXSETAP` and `MINSETAP` |

A program that is not mapped follows a default:

-   only Fall-Back Flex is imposed: connection point;
-   only technical flex is imposed: assets;
-   both or neither: the controller reads a program id starting with `tflex` as assets and anything else as connection point, and raises **Day-ahead planning program without a configured reference power**.

> **Warning**
>
> Ask Fluvius for the program ids when you register the certificate, and map them before the first plan arrives. Two programs that limit the same quarter hour in the same direction: the lowest limit applies.

## Where you see the plan

The **Day-ahead planning** block on the [Fall-Back Flex page](https://voltmasters.io/en/docs/dso-rtu/grid-operators/fluvius/fall-back-flex/monitoring/) and on the DSO RTU page lists the limits for the rest of today and for tomorrow. The chart on the Fall-Back Flex page draws the planned limit as a purple dotted line.

![Voltmasters EMS: Day-ahead planning block with a consumption limit of 350 kW from 16:30 to 18:30 today and two limits tomorrow, each with its program and reference power](https://voltmasters.io/assets/docs/fall-back-flex-day-ahead-planning.webp)

*The planned limits per day, with program and reference power.*

## Certificate

The planning API only accepts a client certificate (OV, at least 2048 bits, at most one year valid) that Fluvius has linked to the asset point id of the connection. [Planning certificate](https://voltmasters.io/en/docs/dso-rtu/grid-operators/fluvius/fall-back-flex/planning-certificate/) explains how to order, register and renew it.