blue'Log XM/XC
blue'Log XM/XC
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Mixed plants

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About mixed plants

In many PV systems today, the setup involves more than just feeding power into the medium or high-voltage grid. Increasingly, solar generation is combined with on-site energy use, such as in factories with a large electricity demand (load). These are known as mixed plants.

In such cases, grid operators typically require control of both active and reactive power at the grid connection point (POI, point of common coupling). If reactive power needs to be controlled depending on the voltage or power level, this measurement must be taken at the grid connection point.

Changes from firmware 34.3.6 on:

  • The blue’Log supports configurations for mixed plants with complex control concepts.

  • The feature complies with the German VDE-AR-N 4110 for mixed generation plants connected to the medium-voltage grid.

  • You can select separate measurement devices (meters, power analyzers) for active and reactive power.

  • This eliminates the need for an on-site PLC to simulate a virtual meter from multiple data sources, simplifying setup and reducing system complexity.

  • Changes from firmware 35.1.7 on: You can select separate measurement devices (meters, power analyzers) for deviating measured values (P and/or V) used in characteristic curves.

Note

If an earlier firmware is installed and power control is enabled on your blue’Log, note the following changes when you update to firmware 34.3.6. or higher:

  • The meters for active and reactive power control are identical. The configured meter for P is also used for Q by default.

  • The meters for reference values in characteristic curves (Q/cos phi) use the meter configured for Q​.


Schematic of measurement of reactive power Q in a mixed plant
Schematic: measurement of reactive power (Q) in a mixed plant


Configure separate meters for active and reactive power

Prerequisites

  • Firmware 34.3.6 or higher is installed

Steps

  1. Go to Power control > Operating data.

  2. In the section Plant data, go to Select meter for active power control.

  3. Select the relevant meter for active power control.

  4. Under Select meter for reactive power control, select the relevant meter for reactive power control.

    • It is possible to use the same meter for both.

    • By default, the meters using characteristic curves use the measured values of the reactive power meter.

    • If you need a separate measured value for active power, (e.g. Q(P)), proceed to the next step.

  5. Go to Power control > Reactive power > Meter selection for specific measured values.

  6. Define the relevant measured value (P and/or V) used in your characteristic curve.

The measured values for the selected meters will now be displayed under Power control > Overview.