1. Reactive Power and Voltage Control Problems Julio César Chinchilla Guarín 223141 Analysis of PowerSystems Universidad Nacional de Colombia

2. Agenda • Introduction. • EquivalentCircuit. • ThéveninEquivalentCircuit. • EquivalentCircuit of a TappedTransformer. • SomeConfigurations of AutomaticTap-Changers in PowerSystems. • Voltage Control of a Radial Load (Case I). • Tie-TransformerBetweenSystems of VariousStrengths (Case II). • TwoVeryStrongSystems. • TwoVeryWeakSystems. • OneVeryStrong and OneVeryWeakSystem. • Conclusions. • References.

3. Introduction

4. ThéveninEquivalentCircuit • EquivalentCircuit of a TappedTransformer • EquivalentCircuit Table 1. Effect of ‘n’ on Y1 and Y2. Y1=n(n-1)Y Y2=(1-n)Y

5. SomeConfigurations of AutomaticTap-Changers in PowerSystems

6. Case I – Voltage control of a radial load

7. Case I – Voltagecontrol of a radial load Y1=n(n-1)Y Y2=(1-n)Y

8. Case I – Voltagecontrol of a radial load

9. Case II – Tie-Transformerbetweensystems of variousstrengths

10. Differencesbetweensystems of variousstrengths Twoverystrongsystems Twoveryweaksystems Oneveryweaksystem and oneverystrongsystem

11. Differencesbetweensystems of variousstrenghts

12. Conclusions • Equivalentcircuitsallowtoanalyzesomeproblemsaboutvoltage and reactive power control associatedwithpowersystemoperation. Thesemodelsgiveinsightintosomephenomenaabout reactive power and voltage control. • Toadd a suplementary «minimumcurrent detector» to «out of voltagerange detector» can allowtooptimizeorminimizebranch «nY» loadingforanygiven load connectedtotransformer. Thisoptimumconditionisnearunitypower factor.

13. Conclusions • Tap-changers can be usedforstrategies as transfer reactive powerbetweentwostrongsystems, thisstrategy can be considered as voltage control. • Wecannot use tap-changers as voltageregulatorbecauseitcouldhaveundesirableconsequencelike as generatorfallsout of synchronism.

14. References • Smolinski, W. J., 1981, ‘Equivalent Circuit Analysis Of Power System - Reactive Power And Voltage Control Problems’, University of New Brunswick, Canada.

15. Are thereanyquestions?

16. Thanksforyourattention!