EXAMPLE 9.1 Power-system sequence networks and their Thévenin equivalents A single-line diagram of the power system considered in Example 7.3 is shown in Figure 9.3, where negative- and zero-sequence reactances are also given. The neutrals of the generator and A-Y transformers are solidly grounded. The motor neutral is grounded through a reactance X, = 0.05 per unit on the motor base. (a) Draw the per-unit zero-, positive-, and negative- sequence networks on a 100-MVA, 13.8-kV base in the zone of the generator. (b) Reduce the sequence networks to their Thévenin equivalents, as viewed from bus 2. Prefault voltage is VF = 1.05/0° per unit. Prefault load current and A-Y transformer phase shift are neglected. FIGURE 9.3 т, 2 M Line Single-line diagram for Example 9.1 X2 - 20 0 X, = 60 N X, 100 MVA 13.8 kV 100 MVA 100 MVA X" - 0.15 13.8-kVA/138-kVY 138-kV Y/13.8-kVA 100 MVA X, = 0.17 X = 0.10 per unit X = 0.10 per unit 13.8 kV Xo = 0.05 per unit X" = 0.20 %3D X2 = 0.21 Xo = 0.10 X, = 0.05 per unit

EXAMPLE 9.1 Power-system sequence networks and their Thévenin equivalents A single-line diagram of the power system considered in Example 7.3 is shown in Figure 9.3, where negative- and zero-sequence reactances are also given. The neutrals of the generator and A-Y transformers are solidly grounded. The motor neutral is grounded through a reactance X, = 0.05 per unit on the motor base. (a) Draw the per-unit zero-, positive-, and negative- sequence networks on a 100-MVA, 13.8-kV base in the zone of the generator. (b) Reduce the sequence networks to their Thévenin equivalents, as viewed from bus 2. Prefault voltage is VF = 1.05/0° per unit. Prefault load current and A-Y transformer phase shift are neglected. FIGURE 9.3 т, 2 M Line Single-line diagram for Example 9.1 X2 - 20 0 X, = 60 N X, 100 MVA 13.8 kV 100 MVA 100 MVA X" - 0.15 13.8-kVA/138-kVY 138-kV Y/13.8-kVA 100 MVA X, = 0.17 X = 0.10 per unit X = 0.10 per unit 13.8 kV Xo = 0.05 per unit X" = 0.20 %3D X2 = 0.21 Xo = 0.10 X, = 0.05 per unit

Introductory Circuit Analysis (13th Edition)

13th Edition

ISBN:9780133923605

Author:Robert L. Boylestad

Publisher:Robert L. Boylestad

Chapter1: Introduction

Section: Chapter Questions

Problem 1P: Visit your local library (at school or home) and describe the extent to which it provides literature...

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