The dynamic voltage restorer(DVR) is a
multifunction device used in distribution system to control
voltage disturbances. In this paper , a multifunctional DVR
protects the load voltage by posi-cast and P+ Resonant
controllers when the source of disturbance is the parallel
feeders. This posi-cast and P+ Resonance controllers improve
the transient response and eliminate the steady state error in
DVR response, respectively. The DVR acts as a virtual
impedance with the main aim of protecting the Point of
common coupling (PCC) voltage during downstream fault .
The proposed algorithm is applied to some disturbances in
load voltage caused by induction motors starting, and a
three-phase short circuit fault. Also, the capability of the
proposed DVR has been tested to limit the downstream fault
current. Simulation results show the performance of the DVR
to control the emergency conditions of the distribution
systems.
V.S.V.S Pravallika : M.Tech Student, KITS College of Engineering- Divili
T.Lakshminarayana : Asst.Professor, KITS College of Engineering- Divili
Dynamic voltage restorer (DVR)
emergency
con-trol
voltage sag
voltage swell
In this paper, a multifunctional DVR is proposed, and a
closed-loop control system is used for its control to
improve the damping of the DVR response. Also, for
further improving the transient response and eliminating
the steady-state error, the Posicast and P+Resonant
controllers are used. As the second function of this DVR,
using the flux-charge model, the equipment is controlled
so that it limits the downstream fault currents and protects
the PCC voltage during these faults by
acting as a variable impedance. The problem of absorbed
active power is solved by entering an impedance just at the
start of this kind of fault in parallel with the dc-link
capacitor and the battery being connected in series with a
diode so that the power does not enter it. The simulation
results verify the effectiveness and capability of the
proposed DVR in compensating for the voltage sags
caused by short circuits and the large induction motor
starting and limiting the downstream fault currents and
protecting the PCC voltage.
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