Coupled power generators require stability buffers in addition to inertia.

Area of Science:

• Electrical Engineering
• Power Systems Analysis
• Renewable Energy Integration

Background:

• The phase-out of traditional generators reduces power grid inertia, necessitating solutions like Virtual Synchronous Generators (VSGs).
• High system inertia is generally considered crucial for stabilizing power grids with coupled oscillators.

Purpose of the Study:

• To analyze the impact of coordinated and uncoordinated controls of VSGs and traditional generators on power grid stability.
• To determine the optimal and maximum number of VSGs that can be safely integrated into the power grid.
• To propose a novel market mechanism, 'stability storage,' to enhance grid stability during the transition to renewable energy.

Main Methods:

• System modeling to simulate the energy and inertia contributions of both VSGs and rotating generators.
• Small-signal stability analysis to identify potential instabilities under various VSG penetration levels.
• Concept development and demonstration of 'stability storage' using VSGs as decentralized buffers.

Main Results:

• Uncoordinated controls between VSGs and rotating generators can lead to small-signal instabilities, even with high overall system inertia.
• The study reveals specific optimal and maximum numbers of VSGs that can be safely incorporated into the grid.
• The proposed 'stability storage' concept effectively mitigates instabilities across diverse energy scenarios.

Conclusions:

• System-level coordination of generator controls is essential for maintaining power grid stability when integrating VSGs.
• Identifying optimal VSG limits is critical for utilities in planning and contracting.
• The 'stability storage' concept offers a viable short-term solution for grid stabilization and supports the transition to a 100% renewable energy grid.