Synthesis of unsymmetrical phasors from their symmetrical components
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The document discusses the synthesis of unsymmetrical phasors from their symmetrical components in electrical power systems, explaining the importance of analyzing unbalanced systems due to faults or short circuits. It outlines two main methods for analysis: Kirchhoff’s law, which is complex for unbalanced systems, and Fortescue’s theorem, which allows the conversion of unbalanced voltages or currents into balanced symmetrical components. The summary includes details on positive, negative, and zero sequence components, describing their characteristics and relationships.
![Positive Sequence components
• A positive sequence set of three symmetrical voltages which are
equal in magnitude and have 120 degree phase displacement in
positive phase sequence are known as positive sequence components
• The phase sequence is given by a to b to c and denoted by Va1,Vb1 and
Vc1.
• Vb1=α2
Va1
• Vc1=αVa1
• [|Va1|=|Vb1|=|Vc1|]](https://image.slidesharecdn.com/synthesisofunsymmetricalphasorsfromtheirsymmetricalcomponents-170402161943/85/Synthesis-of-unsymmetrical-phasors-from-their-symmetrical-components-7-320.jpg)
![Negative Sequence components
• A negative sequence set of three symmetrical voltages which are
equal in magnitude and have 120 degree phase displacement in
negative phase sequence are known as negative sequence
components
• The phase sequence is opposite given by a to c to b and denoted by
Va2,Vb2 and Vc2.
• Vb2=αVa2
• Vc2=α2
Va2
• [|Va2|=|Vb2|=|Vc2|]
• Va2+Vb2+Vc2=0](https://image.slidesharecdn.com/synthesisofunsymmetricalphasorsfromtheirsymmetricalcomponents-170402161943/85/Synthesis-of-unsymmetrical-phasors-from-their-symmetrical-components-8-320.jpg)
Synthesis of unsymmetrical phasors from their symmetrical components
- 1. 6th Sem Electrical Engineering Department Batch – B1 (2014 Batch) Abhishek Choksi (140120109005) Electrical Power System-2 (2160908) ALA Presentation On “Synthesis of unsymmetrical phasors from their symmetrical components” Prepared By: Guided By: Prof. Abhishek Harit Gandhinagar Institute Of Technology
- 2. Synthesis of unsymmetrical phasors from their symmetrical components
- 3. Introduction • Power systems are large and complex three phase system • In normal operating conditions , electrical power system operate in balanced condition. • But sometimes certain situation occurs like fault or short circuit which make the system to be unstable. • Single phase equivalent system method of analysis cannot be applied to such system.
- 4. • So, two method available for such an analysis 1)kirchhoff’s law 2)Symmetrical Components method
- 5. 1)kirchhoff’s law •This method is very difficult to analysis unbalanced system. 2)Symmetrical Components method •This method is known as fortescue’s theorem •This theorem states that a system of n unbalanced set of phasors can be resolved into sets of (n-1) balanced phasor systems of different phase sequences plus one zero phase sequence system
- 6. • In this technique the three unbalanced voltages or current are converted into three sets of balanced voltages or currents which are known as symmetrical components
- 7. Positive Sequence components • A positive sequence set of three symmetrical voltages which are equal in magnitude and have 120 degree phase displacement in positive phase sequence are known as positive sequence components • The phase sequence is given by a to b to c and denoted by Va1,Vb1 and Vc1. • Vb1=α2 Va1 • Vc1=αVa1 • [|Va1|=|Vb1|=|Vc1|]
- 8. Negative Sequence components • A negative sequence set of three symmetrical voltages which are equal in magnitude and have 120 degree phase displacement in negative phase sequence are known as negative sequence components • The phase sequence is opposite given by a to c to b and denoted by Va2,Vb2 and Vc2. • Vb2=αVa2 • Vc2=α2 Va2 • [|Va2|=|Vb2|=|Vc2|] • Va2+Vb2+Vc2=0
- 9. Zero Sequence Components • A zero sequence set of three voltages which are equal to magnitude and have same phase are known as zero sequence components • Va0=Vb0=Vc0 • Va0+Vb0+Vc0=3Va0
- 11. Reference • Elements of power system analysis by Willian D Stevenson Jr. International student edition. • Power system analysis by JB Gupta • http://elearning.vtu.ac.in/P2/EE61/Ch03/html/0019.htm • http://nptel.iitm.ac.in/courses/Webcourse-contents/IIT- KANPUR/power-system/chapter_8/8_5.html
- 12. Thank You