this is the ppt on modeling and simulation of a dynamic voltage restorer you can present.

1. D E P A R T M E N T O F E L E C T R I C A L
E N G I N E E R I N G
S U B M I T T E D B Y -
P U N I T
K U M A R

2. INTRODUCTION:
 Among the power quality problems (sags, swells, harmonics…) voltage sags
are the most severe disturbances.
 In order to overcome these problems the concept of custom power devices is
introduced recently. One of those devices is the Dynamic Voltage Restorer
(DVR), which is the most efficient and effective modern custom power
device used in power distribution networks.
 DVR is a recently proposed series connected solid state device and is
normally installed in a distribution system between the supply and the
critical load feeder at the point of common coupling (PCC). It employs a
series of voltage boost technology using solid (static) state switches of 3-
PHASE VSC that injects voltage into the system; to restore the load side
voltage for compensating voltage sags/swells.
 Other than voltage sags and swells compensation, DVR can also added other
features like: line voltage harmonics compensation, reduction of transients in
voltage and fault current limitations
2

3. 40kV/13.2kV 40kV/13.2kV
NONC
40kV Bus
Industrial Substation
40kV Bus
Custom Power
Device
Input Waveform
Output To
Customer• A voltage sag/swell in the utility
waveform is seen by the customer
without a Custom Power Device in the
substation
• Sags and swells can have severe affects
on the Customer Load
• Implementing the Customer Power
Devices into the substations will correct
the waveform
3

4. Filter
Charger
Q1 Q2
Q3
T1
TL
Control
VG
VB VL
Distribution
Bus
Load
Bus
DVR
IB= IG
• Power electronic converter injects
appropriate voltage
• Acts as a buffer, used for injecting
or absorbing
• Can Compensate a 50% three
phase voltage dip for up to 50
cycles
• Cover a power range from 3MVA
up to 50 MVA
Dynamic
Voltage
Restorer
4

5. FEATURES OF DVR:
 Lower cost, smaller size, and its fast dynamic
response to the disturbance.
 Ability to control active power flow.
 Higher energy capacity and lower costs
compared to the SMES device.
 Less maintenance required. UPS is costly, it also
requires a high level of maintenance because
batteries leak and have to be replaced as often as
every five years.
Fig. Location of DVR
5

6. When a fault occurs on the line feeding Load 1, its voltage collapses to
zero. Load 2 experiences sag equals to the voltage at the PCC and the
voltage of sensitive load protected by the DVR is restored to its pre-fault
value.
6
Fig. Basic structure of DVR

7. 7
Basic Configuration of DVR:
The general configuration of the DVR consists of:
i. An Injection/ Booster transformer
ii. A Harmonic filter
iii. Storage Devices
iv. A Voltage Source Converter (VSC)
v. DC charging circuit
vi. A Control and Protection system
Fig. Schematic diagram of DVR

8. 8
INJECTION/BOOSTER TRANSFORMER:
The Injection / Booster transformer is a specially designed transformer that attempts to limit the coupling of noise and
transient energy from the primary side to the secondary side.
Its main tasks are:
connects the DVR to the distribution network via the HV-windings and transforms and couples the injected compensating
voltages generated by the voltage source converters to the incoming supply voltage.
serves the purpose of isolating the load from the system (VSC and control mechanism).
HARMONIC FILTER:
This can cause voltage drop and phase shift in the fundamental component of the inverter output and has to be
accounted for in the compensation voltage.
VOLTAGE SOURCE CONVERTER:
-consists of a storage device and switching devices
-generate a sinusoidal voltage at any required frequency, magnitude, and phase angle.
-In the DVR application, the VSC is used to temporarily replace the supply voltage or to generate the part of the supply
voltage which is missing.
DC Charging Circuit:
The dc charging circuit has two main tasks:
- The first task is to charge the energy source after a sag compensation event.
- The second task is to maintain dc link voltage at the nominal dc link voltage
CONTROL AND PROTECTION:
The control mechanism of the general configuration typically consists of hardware with programmable logic.
All protective functions of the DVR should be implemented in the software. Differential current protection of the
transformer, or short circuit current on the customer load side are only two examples of many protection functions
possibility.

9. 9
OPERATING MODES OF DVR:
1. PROTECTION MODE:
If the over current on the load side exceeds a permissible limit due
to short c
circuit on the load or large inrush current, the DVR will be isolated
from the systems by using the bypass switches (S2 and S3 will
open) and supplying another path for current (S1 will be closed)
2. STANDBY MODE: (VDVR= 0)
-In the standby mode the booster transformer’s low voltage
winding is shorted through the converter.
-No switching of semiconductors occurs in this mode of operation
and the full load
-Current will pass through primary
3.INJECTION/BOOST MODE: (VDVR>0)
the DVR is injecting a compensating voltage through the booster
transformer due to the detection of a disturbance in the supply voltage

10. 10
TEST SYSTEM OF DVR
The test system for DVR is composed by a 13 kV, 50 Hz Generation system, feeding transmission line
through a 2- winding transformer connected in Y/ Δ,13/115KV. Such transmission line feed distribution
network through step down transformer connected in Δ/Y, 115/11 kV. To verify the working of DVR for
voltage compensation a fault is applied at point X at resistance 0.66 U for time duration of 200 ms. The
DVR is simulated to be in operation only for the duration of the fault.
Simulink model of DVR controller

11. 11
Sr.
no.
System quantities Standards
1. Three phase source 13KV, 50Hz.
2. Step-up transformer Y-Δ , 13/115KV
3. Transmission line parameter R=0.001 ohms,L=0.005 H
4. Step-down transformer Δ-Y, 115/11KV
5. Load 1 &2 10KW, 400VAR
6. Inverter IGBT based,3 arms ,
6 Pulse,
Carrier Frequency =1080 Hz,
Sample Time= 5 μs
7. PI controller Kp=0.5
Ki=50
Sample time=50 μs
8. DC battery 6.5 KV
9. C2 750 μF
10. Linear/Isolation transformer 1:1 turns ratio, 11/11KV
SYSEM PARAMETERS

12. 12
SIMULATION AND RESULT

13. D E E P A K G U P T A 13
System without DVR & with fault

14. 14
Phase –phase, three-phase and p.u. voltages at load point for a-
b-c fault
sag

15. 15
System with DVR & fault

16. 16
Phase –phase and three-phase voltages at load point for a-b-c
fault
p.u voltages at load point for a-b-c fault