IEEE TRANSACTIONS ON SMART GRID, 2014
ABSTRACT
This paper proposes a new fault current limiting dynamic
voltage restorer (FCL-DVR) concept. The new topology uses a crowbar bidirectional
thyristor switch across the output terminals of a conventional back-to-back
DVR. In the event of a load short, the DVR controller will deactivate the
faulty phase of the DVR and activate its crowbar thyristor to insert the DVR filter
reactor into the grid to limit the fault current. A fault condition is detected
by sensing the load current and its rate of change. The FCL-DVR will operate
with different protection strategies under different fault conditions. Design
of the FCL-DVR involves selecting important parameters, such as DVR power
rating, dc link voltage of the DVR, output filter reactors and capacitors, and
grid-tied transformers is proposed. The design methodology of the proposed
FCL-DVR is fully discussed based on power systems computer aided design
(PSCAD)/electromagnetic transients including dc (EMTDC) simulation. A
scaled-down experimental verification is also carried out. Both modeling and
experimental results confirm the effectiveness of the new FCL-DVR concept for
performing both voltage compensation and fault current limiting functions.
KEYWORDS:
1.
Dynamic
voltage restorer (DVR)
2.
Fault current limiting
(FCL)
3.
Parameter
design method
4.
Voltage
compensation
SOFTWARE:
MATLAB/SIMULINK
CIRCUIT
DIAGRAM:
Fig. 1
Topology
of FCL-DVR.
EXPECTED SIMULATION
RESULTS:
Fig
2. Simulation results of voltage compensation operation of FCL-DVR. Waveforms
of grid voltages, PCC voltages, load currents FCL-DVR output voltages, and dc
link voltages of the FCL-DVR during voltage fluctuation event and (b)
unbalanced voltage event.
CONCLUSION
A new FCL-DVR concept is proposed to deal with both voltage
fluctuation and short current faults. The new topology uses a crowbar
bidirectional thyristor switch across the output terminals of a conventional
back-to-back DVR. In the event of load short, the DVR controller will
deactivate the faulty phase of the DVR and activate its crowbar thyristor to
insert the DVR filter reactor into the grid to limit the fault current. The
FCL-DVR will operate with different protection strategies under different fault
conditions. Based on theoretical analysis, PSCAD/EMTDC simulation and
experimental study, we conclude the following.
1) With the crowbar bidirectional thyristor across
the output terminal of the inverter, the proposed FCL-DVR can compensate
voltage fluctuation and limit fault current.
2) The FCL-DVR can be used to deal with different
types of short faults with minimum influence on nonfault phases. The FCL-DVR
has the same power rating as a conventional DVR.
3) The delta-connection mode of the shunt
transformers minimizes the influence of dc link voltage fluctuations and
suppresses the 3rd harmonics.
4) The proposed control method can detect faults
within two cycles.
5) The design methodology based on the analysis of
the relationship between main circuit parameters and compensation capacity
could be helpful to the design of FCL-DVR.
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