Voltage harmonic mitigation using DVR

Voltage Harmonic Mitigation using DVR

based on MATLAB/SIMULINK

Presented by:Aniket Naugariya(Roll no.1130921011)Udgam Tiwari(Roll no.1130921038)Shivam Pandey(Roll no.1130921040)Santosh Kumar(Roll no.1130921031)

Under the supervision of: Mr. Priyank Agarwal

Electrical & Electronics Deptt.

Table of contents1. Introduction to Power Quality2. Power Quality problems3. Harmonics4. Introduction of custom power devices5. DVR(Dynamic voltage Restorers)6. DVR Circuit diagram7. DVR power circuit8. About MATLAB9. DVR control strategy (based on SRF)10. Control Diagram11. Advantages12. References

INTRODUCTION OF POWER QUALITY

• The IEEE defines Power Quality is defined as “Any power problem manifested in voltage, current, and/or frequency deviations that results in the failure and/or mal-operation of end user’s equipment”.

PQ mainly deals with 1. Continuity of the supply. 2. “Quality” of the voltage.

Power Quality Problems

Voltage Sag/Dip:-•Description: A decrease of the normal voltage level between 90% to 10% of the nominal rms voltage at the rated power frequency, for durations of 0.5 cycle to 1 minute(IEEE).•Causes: 1.Faults on the transmission or distribution network.2.Connection of heavy loads and start-up of large motors.

Voltage Swell• Description: It is defined as an increase in RMS voltage b/w 110%-180% at

the rated power frequency for duration ½ cycle to 1min(IEEE) • Causes:1.Single line to ground fault in the system2.Abruptly increase in load3.Switching off large capacitor bank• Consequences:1.Data loss.2.Flickering of light and screen

Harmonics

●Harmonic waveform is a periodic distortion of the normal Sine wave

Introduction of Custom power devices

• Custom power devices are designed to improve the quality of power at their point of installation of power distribution systems. They are not primarily designed to improve power quality of the entire system.

• Custom power devices are of three types:1.DVR2.D-STATCOM3.UPQC

DVR(Dynamic voltage restorers)

• A DVR is a voltage-source converter (VSC)-based power electronics device.

• Connected in series between the supply and the critical loads.

• If fault occur it provides certain amount of compensating voltage into the distribution line.

• Restore Balanced sinusoidal load voltage even if source voltage is unbalanced or distorted.

Circuit diagram

DVR Power circuit

• DVR Power circuit contains three single-phase H-bridge VSCs along with a common dc capacitor (Cdc).

• The three H-bridge VSCs is connected through a ripple filter(Lr,Cr,Rr) and an injection transformer.

• The shunt capacitor filter Cf is used to provide a low impedance path to higher order harmonics of load voltage when the load is nonlinear.

Power circuit of DVR

MATLAB

MATLAB(matrix laboratory) is a fourth-generation high-level programming

language and interactive environment for numerical computation, visualization and programming. •MATLAB is developed by MathWorks. •It allows matrix manipulations; plotting of functions and data; implementation of algorithms; creation of user interfaces; interfacing with programs written in other languages, including C, C++, Java, and Fortran; analyze data; develope algorithms; and create models and applications. •It has numerous built-in commands and math functions that help you in mathematical calculations, generating plots and performing numerical methods.

DVR Control strategy based on SRF

• In steady state, the phase difference between instantaneous DVR voltages and instantaneous line currents must be 90◦.

• Generally DVR control strategy can be divided into three parts:i. Under Balanced Sinusoidal Supply Condition with Balanced Linear

Load.ii.Under Unbalanced and/or Distorted Supply Condition With

Unbalanced Linear Load.iii.Fundamental Positive-Sequence Extractor

Advantages

1. Capability to adapt by itself to changes that may occur in the power system. Such as Voltage flickers &harmonics generated by electric arc furnace.

2. Minimizes the possible occurrence of Resonances.3. Reduce harmonics.4. Balance the voltage at the PCC.

Thank You

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