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S2 example for PV

Ewoud Werkman edited this page Dec 6, 2024 · 27 revisions

S2 example for PV installations

This page serves as a guide for implementing an S2 RM for a PV installation. It provides example S2 messages that help developers to understand how to interact with PV installations and what kind of flexibility they can offer.

Flexibility of a PV installation

A PV installation produces electricity by converting solar energy into electricity. This electricity can be used for several purposes, such as self-consumption or earning money by delivering electricity to the grid.

Usually a PV installation is not flexible at all, as it only produces electricity when there is sun and depending on weather circumstances (e.g. such as cloud coverage) it will produce more or less, i.e. its production is intermittent. But many PV inverters also allow to control the maximum output power of the PV installation, also known as curtailment. This curtailment is for example needed when too much installations are connected to the same local grid and produce at high power, pushing the voltage of the network above its acceptable limits, or when prices for delivering electricity back to the grid become to low (or even negative) to be profitable.

Choosing the S2 control type

S2 supports five different control types for flexibility (and one for no control possibility), each supporting a different way of modelling flexibility of a device. For PV installations the choice is somehow simple, as the capabilities of these installations are limited:

Control capability Control type Remark
No control possible NOT_CONTROLABLE As there is no way to control this PV installation, the NOT_CONTROLABLE ControlType should be selected. Although nothing can be controlled, devices can still send PowerMeasurements and PowerForecasts
Set maximum output power POWER_ENVELOPE_BASED_CONTROL (PEBC) Based on the constraints of the PV installation (e.g. the minimum and maximum power output of the inverter), the CEM can provide the Resource Manager of the PV installation to implement a PowerEnvelope that describes the minimum (usually 0) and maximum (e.g. 2kW) that the inverter of the PV installation should produce

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