# Overview

> How grid operators remotely monitor and control your installation through the Voltmasters EMS, and how Voltmasters delivers and certifies that link.

Source: https://voltmasters.io/en/docs/dso-rtu/

**DSO RTU** is the mechanism by which a distribution system operator (DSO) remotely monitors and controls a decentralized energy installation, through a Remote Terminal Unit (RTU) on site, in order to keep the electricity grid within its physical limits.

> **Note**
>
> Some grid operators have their own name for this mechanism. Fluvius calls it **telecontrole**. The operator-independent term used throughout this section is **DSO RTU**.

Voltmasters is the **interface between the grid operator and the installation**. The grid operator sends limits, control modes and, when needed, emergency stops. The EMS turns those signals into immediate actions on the connected assets (PV, battery, EV charging, flexible loads) and continuously reports back what the installation is doing. DSO RTU is increasingly a **connection requirement** for larger installations, and the certification the grid operator performs is what clears the installation for operation.

### What the grid operator can do

Through the DSO RTU link the grid operator can, in real time:

-   **Limit active power (P)**: cap injection and consumption, at the grid connection point and as a share of the registered asset power.
-   **Control reactive power (Q)**: switch between local and remote Q control and impose a reactive-power band.
-   **Trigger an emergency stop**: stop production, stop consumption, or both, immediately.
-   **State a reason**: normal operation, grid congestion, or test.

In return the EMS **confirms** every command, **mirrors** the state it applies, and sends **measurements** per asset category, so the grid operator can verify that the installation complies.

### How the EMS responds

Every command is enforced in **software** on every control cycle (about once per second): setpoints to zero, batteries to 0 kW, loads off. For emergency stops a **relay output** on an [IO module](https://voltmasters.io/en/docs/dso-rtu/io-module/) adds a physical disconnection, independent of the asset's own communication. Some operators, Fluvius among them, expect that physical layer.

What the EMS does with each instruction, in which order the laws are applied and what happens when the link is lost is described in [How DSO RTU works](https://voltmasters.io/en/docs/dso-rtu/how-dso-rtu-works/).

### Grid operators

DSO RTU is **operator-specific**: each grid operator has its own protocol, data model and certification. The EMS hides that behind one *DSO RTU provider* setting per project, so the asset side is the same for every operator. See [Grid operators](https://voltmasters.io/en/docs/dso-rtu/grid-operators/) for the operators supported today and how they differ.

### How this section is organized

-   [How DSO RTU works](https://voltmasters.io/en/docs/dso-rtu/how-dso-rtu-works/): the control model and the data flow, end to end.
-   [Grid operators](https://voltmasters.io/en/docs/dso-rtu/grid-operators/): what each operator steers and how.
    -   [Fluvius](https://voltmasters.io/en/docs/dso-rtu/grid-operators/fluvius/), with its [configuration](https://voltmasters.io/en/docs/dso-rtu/grid-operators/fluvius/configuration/), the [asset setpoints](https://voltmasters.io/en/docs/dso-rtu/grid-operators/fluvius/asset-setpoints/), [Fall-Back Flex](https://voltmasters.io/en/docs/dso-rtu/grid-operators/fluvius/fall-back-flex/) and the [EME eCON+ panel](https://voltmasters.io/en/docs/dso-rtu/grid-operators/fluvius/eme-econ-plus/).
    -   [Sibelga](https://voltmasters.io/en/docs/dso-rtu/grid-operators/sibelga/) and [ORES](https://voltmasters.io/en/docs/dso-rtu/grid-operators/ores/).
-   [RTU connection](https://voltmasters.io/en/docs/dso-rtu/rtu-connection/): the network link between the grid operator's RTU and the EMS.
-   [IO module](https://voltmasters.io/en/docs/dso-rtu/io-module/): the module that gives the EMS relay outputs and digital inputs, with [placement and cabling](https://voltmasters.io/en/docs/dso-rtu/io-module/placement-and-cabling/), the [emergency stop](https://voltmasters.io/en/docs/dso-rtu/io-module/emergency-stop/) and the [technical specifications](https://voltmasters.io/en/docs/dso-rtu/io-module/technical-specifications/).
-   [Commissioning and certification](https://voltmasters.io/en/docs/dso-rtu/commissioning-and-certification/): how Voltmasters validates the link, and how to follow the grid operator's certification on the platform.

What you see in the platform is documented with the rest of the application: the [DSO RTU dashboard](https://voltmasters.io/en/docs/voltmasters-platform/dashboards/dso-rtu-dashboard/) for the live constraint status and the RTU history, and [DSO RTU settings](https://voltmasters.io/en/docs/voltmasters-platform/project-settings/dso-rtu/) under project settings.