The document discusses the compensation of voltage sag and swell using Dynamic Voltage Restorers (DVRs) under the guidance of Mr. J. Vasanthkumar. It highlights the principle of DVRs in restoring load voltage and outlines the causes, consequences, and characteristics of voltage sags and swells, as well as the advantages and limitations of DVR technology. Additionally, the document presents a conclusion on the effectiveness of DVRs with various voltage injection schemes and suggests future directions for research in power quality issues.

1. UNDER THE GUIDNESS OF
Mr. J.VasanthKumar., M.Tech Asst.professor
Department of EEE
BY USING BESS THE COMPENSATION OF VOLTAGE
SAG&SWELL CAN BE CONTROLLED BY DVR
PRESENTED BY
K. Krishna reddy 14C25A0219
D. Swapna 14C25A0206
G. Ramu 13C21A0209
G. Rajashekar 13C21A0208

2. INTRODUCTION:
• POWER QUALITY problems in the present-day
distribution systems are due to the increased use of
sensitive and critical equipment pieces .
• Series-connected compensators known as dynamic voltage
restorers (DVRs)

3. DYNAMIC VOLTAGE RESTORER:
• The basic principle of a DVR is simple, by supplying a
voltage of desired magnitude and frequency, the DVR
restores the load voltage to a desired pre-sag voltage
quantity even when source voltage is not balanced.
CIRCUIT DIAGRAM :

4. BASIC CONFIGURATIONS OF DVR:
The general configuration of the DVR consists of:
• An Injection transformer
• Filter circuit
• A Voltage Source Converter
• A Control and Protection system

5. VOLTAGE SAG:
• Description: A decrease of the normal voltage level
between 10% and 90% of the nominal RMS voltage at the
power frequency, for durations of 0.5 cycle to 1 minute.

6. .
Voltage sag Consequences:
• Malfunction of microprocessor-based control systems(PCs,
PLCs, etc.)
• Tripping of contactors and relays.
• Disconnection and loss of efficiency in rotating machines.
• Dimming of lighting system.

7. THREE PHASE SAG VOLTAGES:

8. VOLTAGE SWELL:
• Description: Swell can be defined as, “An increase to
between 80% and 180% in rms voltage or current at the
power frequency durations from 0.5 to 1 minute

9. Voltage swell Consequences:
• Data loss, flickering of lighting and screen.
• stoppage or damage of sensitive equipment if the voltage
values are too high.
• Production rates fluctuates.
• Variable speed drives close down to prevent damage.

10. THREE PHASE SWELL VOLTAGES:

11. CIRCUIT DIAGRAM:

12. DYNAMIC PERFORMANCE OF DVR WITH IN-PHASE INJECTION DURING
VOLTAGE SAG AND SWELL APPLIED TO CRITICAL LOAD

13. ADVANTAGES:
• It is less expensive
• Small in size
• Better power effective device as compare to other links
UPS,SMES,DSTATCOM.
• Fast response
• Less Maintenances

14. APPLICATIONS:
• Transmission
• Distribution
• Non-Linear loads
• Communication Network
• Process industries
• Precise manufacturing process

15. LIMITATIONS:
• DVR, the energy storage size of DVR is kept low.
• DVR has a limited current conduction and voltage
injection capability.

16. FUTURE SCOPE:
• Study and control of power quality issues for deregulated
power system.
• Soft computing techniques developed can be further used
in various fields of power system like – power system
dynamics & stability, smart grid, power system state
estimation, economic dispatch and optimal power flow.

17. CONCLUSION:
 The operation of a DVR has been demonstrated with a
new control technique using various voltage injection
schemes. A comparison of the performance of the DVR
with different schemes has been performed with a reduced-
rating VSC, including a capacitor-supported DVR. The
SRF theory has been used for estimating the reference
DVR voltages. It is concluded that the voltage injection in-
phase with the PCC voltage results in minimum rating of
DVR but at the cost of an energy source at its dc bus.

18. REFERENCES:
• M. H. J. Bollen, Understanding Power Quality Problems—Voltage Sags
and Interruptions. New York, NY, USA: IEEE Press, 2000.
• A. Ghosh and G. Ledwich, Power Quality Enhancement Using Custom
Power Devices. London, U.K.: Kluwer, 2002.
• M. H. J. Bollen and I. Gu, Signal Processing of Power Quality
Disturbances. Hoboken, NJ, USA: Wiley-IEEE Press, 2006.
• IEEE Recommended Practices and Recommendations for Harmonics
Control in Electric Power Systems, IEEE Std. 519, 1992.
• M. Vilathgamuwa, R. Perera, S. Choi, and K. Tseng, “Control of energy
optimized dynamic voltage restorer,” in Proc. IEEE IECON, 1999, vol. 2,
pp. 873–878.
• J. G. Nielsen and F. Blaabjerg, “A detailed comparison of system
topologies for dynamic voltage restorers,” IEEE Trans. Ind. Appl., vol.
41, no. 5,pp. 1272–1280, Sep./Oct. 2005.