- 1. Seminar Topic on:- SYMMETRICAL COMPONENT OF POWER SYSTEMS Presented By:- Devendra Mishra Branch:- EN-1 Roll No:-1401421020
- 2. OUTLINE OF THE PRESENTATION INTRODUCTION NEED FOR THE SYMMETRICAL COMPONENET METHOD TECHINQUES USED TO ANALYSIS SYMMETRICAL CONCLUSION
- 3. INTRODUCTION A three-phase system is said to be symmetrical when the system viewed from any phase is similar. Thus, in a three-phase symmetrical system the impedances of all the three phases are equal and the mutual impedances, if any, between the three phases are the same. The three phase voltages(or currents) are said to be balanced if the magnitude of the three voltages(or currents) are equal and they separated from each other by 120º(electrical) in phase. When the system is unbalance the voltages, current and the phase impedances are in general unequal. Such a system can be solved by a symmetrical per phase technique known as the method of symmertical component.
- 4. This method was proposed by Fortescue in 1981 and is often called the three-component method. According to Fortescue, An unbalance set of n phasors may be resolved in to (n-1) balanced n- phase system of different phase sequence and one zero-phase sequence system. A zero-phase sequence system is one in which all phasors are of equal magnitude and identical angle,
- 5. PHASE SEQUENCE Phase-Sequence of the phasors is the order in which they pass through a positive maximum. Thus, a phase sequence a b c implies that the maxima occur in order a, b, c. If a, b, c is taken as the positive phase sequence then a, c, b represents the negative phase sequence. It should be noted that for both positive & negative phase sequence, the direction of rotation of phaser is taken to be anticlockwise
- 6. The phasor representation of three phase system
- 7. Need for the symmetrical component analysis Negative sequence relay in generator has helped in protecting the generator from over heating in the event of unbalanced loads. The positive sequence network is used to supply the sensing voltage to generator voltage regulators Certain connections of CT and PT develop zero sequence components that are used in protective ground relaying scheme
- 8. Method of adopted for symmetrical component analysis Mathematically: Va= Va0+ Va1+ Va2 Vb= Vb0+ Vb1+ Vb2 Vc= Vc0+ Vc1+ Vc2 Va Vb Vc are unbalance set of phasor Va1, VbVc1 are set of positive sequence phasor Va2, Vb2Vc2 are negative sequence phasor Va0 Vb0 Vc0 are zero sequence phasor
- 10. Vp=A Vs Then Vs=[ adjA÷|A|] Vp
- 11. Symmetrical components of generator
- 13. Conclusion Power system analysis using symmetrical component is very helpful in improving the reliability of the power system. The principle adopted for the analysis of unbalanced fault system is symmetrical component method