ABSTRACT
For a high penetration
micro-grid, improving its low-voltage ride-through (LVRT) capability under some
minor or temporary faults can contribute to reinforcing power support and reducing
network instability. In this paper, the comparison of a superconducting fault
current limiter (SFCL) and a dynamic voltage restorer (DVR) for LVRT capability
enhancement of a 10 kV micro-grid is conducted. Concerning the micro-grid which
includes distributed photovoltaic (PV) generation, energy storage and loads,
the effects of the SFCL and the DVR are compared in detail, and related
theoretical analysis, simulation study, and economical evaluation are carried
out. From the demonstrated results, the suggested two devices can both assist
the micro-grid to achieve the LVRT operation, but the economics of the DVR are weaker
than the SFCL. Moreover, compared to the DVR, the SFCL enables the energy
storage unit to offer better control effects in power stabilization. From
technical and economic perspectives, the SFCL is a more preferable choice than
the DVR.
KEYWORDS:
1.
Dynamic voltage restorer (DVR)
2.
Low-voltage ride-through (LVRT)
3.
Micro-grid
4.
Superconducting fault current limiter (SFCL)
5.
Techno-economic.
SOFTWARE:
MATLAB/SIMULINK
BLOCK
DIAGRAM:
Fig. 1.
Configuration structure of the flux-coupling type SFCL.
EXPECTED SIMULATION RESULTS:
Fig 2. Three-phase PCC voltages under
the short-circuit fault. (a) Without auxiliary, (b) with the SFCL and (c) with
the DVR.
Fig. 3. Operation characteristics of the
micro-grid under the short-circuit fault. (a) PCC current and (b) frequency
fluctuation.
Fig.
4. Power characteristics of the micro-grid under the short-circuit fault. (a) Exchange
power Pex, (b) DG total power PDG-total and (c) load power PLoad.
Fig. 5. Operation characteristics of the
three DG units under the short-circuit fault. (a) DG1, (b) DG 2 and (c) DG3.
CONCLUSION
Based
on the theoretical analysis, simulation study, and economic evaluation, this
paper carries out the comparison of the SFCL and the DVR for enhancing the
micro-grid’s LVRT capability, and the following conclusions can be obtained. 1)
The SFCL and the DVR can both assist the micro-grid to meet the LVRT
requirements. 2) Regardless of the full-compensation or non-full-compensation
DVR, its total cost is more than the SFCL. Although the full-compensation DVR is
able to offer better transient performance indexes, there may be a tradeoff
between performance contribution and device cost. 3) Applying the SFCL enables
the energy storage unit to offer better control effects in power stabilization.
From technical and economic perspectives, the SFCL will be a more preferable choice
than the DVR. In the near future, the detailed optimization design and
experimental test of the SFCL will be conducted, and the results will be
reported later.
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