The most important facts
- More stringent requirements on distributed power generating plants provide for integration of future generation capacity using new grid-supporting properties.
- The Application Rule implements the European Network Code "Requirements for Generators" for the low-voltage level
- A new basic set of rules for this voltage level comes about together with "TCR Low-voltage" (VDE-AR-N 4100).
System relevance of the power generating plants in the lowest voltage levels is further on the rise. Therefore, newly erected power generating plants have to support the grid in future. The Forum Network Technology/Network Operation in the VDE (VDE|FNN) has revised the "Power Generating Plants Connected to the Low-voltage Grid" Code of Practice (VDE-AR-N 4105) for this. The Code of Practice will impose more stringent requirements on distributed power generating plants than hitherto. The framework with the new proactive requirements comes about to integrating further generation capacity in the low-voltage grids. A further driver for revision is the implementation of the European Network Code "Requirements for Generators" for the low-voltage grid in Germany. New plants that are to be connected according to the "Power Generating Plants Connected to the Low-Voltage Grid" Code of Practice will also meet all technical requirements from this European Network Code.
Photovoltaic plants with many of them in private households make the largest portion of power generating plants connected to the low-voltage grid. But this also includes block heating and generating plants (BHKW), hydroelectric power plants, small wind turbines and fuel cells. The new Code of Practice also includes, for the first time, requirements on accumulators which should behave like power generating plants in the discharging process.
Key Innovations are among others:
- Dynamic network support: In future, new power generating plants will have to remain on grid during short voltage drops or increases thus supporting it.
- Feeding in reactive power depending on voltage (Q(U) control) can be used: Thus, more power generating plants can be integrated in an existing grid depending on local circumstances.
- Active-power output at underfrequency: When power is lacking in the system, power generating plants and accumulators will in future feed in to a greater degree thus supporting the system.
In future, power generating plants connected to the low-voltage grid will be able to provide dynamic network support. This means that plants would remain on the grid also during short-term voltage drops or increases instead of switching off as hitherto. This will prevent unwanted generation capacity shutdown and risking grid stability.
Since 2011, power generating plants in the low voltage grid have been supporting voltage optionally using two proven methods but they do not react on the voltage at the connection point. A further technique, viz. feeding in reactive power depending on voltage (so-called Q(U) control) has proven successful at the high-voltage and medium-voltage level for a long time now. This method should be used in the low voltage grid into the future, too. Depending on local circumstances, this allows connecting more power generating plants to an existing distribution network. VDE|FNN transfers with this requirement and dynamic network support as well essential results of the FNN studies "Response in the Event of a Fault" and "Static Voltage Level Maintenance" of 2015/2016 into practice.
Lastly, power generating plants have to counteract drop of the grid frequency by increasing their feed-in power. This also applies for accumulators in particular. Underfrequency means that there is too little generation capacity in the grid with simultaneously too high loss.
• Planners, erectors, operators and manufacturers of distributed power generating plants for low voltagereceive clear, nationwide uniform rules and, hence, more planning safety and investment certainty
• Network operators: In future, power generating plants connected to the low-voltage grid will behave more grid and system assistive thanks to further developed requirements.
Together with the "Technical Connection Rules Low Voltage" (VDE-AR-N 4100) a new basic set of rules has been generated. Both documents are part of the VDE|FNN activities to safeguarding the continually safe plant operation with rising current consumption from renewable energies.
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