Abstract
The continuous increasing share of power-converter-based renewable energies weakens the power system inertia. The lack of inertia becomes a main challenge to small-scale modern power systems in terms of control and stability. To alleviate adverse effects from inertia reductions, e.g., undesirable load shedding and cascading failures, three-phase grid-connected power converters should provide virtual inertia upon system demands. This can be achieved by directly linking the grid frequency and voltage references of dc-link capacitors/ultracapacitors. This paper reveals that the virtual inertia control may possibly induce instabilities to the power converters under weak grid conditions, which is caused by the coupling between the d- and q-axes as well as the inherent differential operator introduced by the virtual inertia control. To tackle this instability issue, this paper proposes a modified virtual inertia control to mitigate the differential effect, and thus, alleviating the coupling effect to a great extent. Experimental verifications are provided, which demonstrate the effectiveness of the proposed control in stabilizing three-phase grid-connected power converters for inertia emulation even when connected to the weak grid.
Original language | English |
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Article number | 8567928 |
Journal | I E E E Transactions on Power Electronics |
Volume | 34 |
Issue number | 9 |
Pages (from-to) | 8660-8670 |
Number of pages | 11 |
ISSN | 0885-8993 |
DOIs | |
Publication status | Published - Sept 2019 |
Keywords
- Frequency regulation
- Power converter
- Renewable energy
- Stability
- Virtual inertia
- Weak grid