Transmission and Distribution

EE25401:

Transmission and Distribution

Course objective:

This course introduces fundamental concepts and analysis of electrical power transmission and distribution systems. It covers modeling of transmission lines for AC and DC, including calculation of inductance and capacitance for various conductor configurations. Sag and tension calculations under different environmental conditions are discussed in detail. The course also examines types overhead line insulators used for different voltage levels, potential distribution, corona effects with mitigation techniques and underground cables. Overall, this course equips students with essential analytical skills for reliable power delivery.

Modeling of Transmission Lines: AC and DC transmission systems, Resistance, Inductance and Capacitance Calculations, Single phase transmission lines, two wire system and composite conductors, Three phase transmission lines with unsymmetrical spacing, transposition of conductors, double circuit line, Bundled conductors Skin effect, Proximity effect.

Performance of Transmission Lines: Short, Medium and Long transmission lines with Nominal-T, π and rigorous methods, ABCD constants, Power Circle diagram, Ferranti effect, Compensators - Series and Shunt.

Sag and Tension Calculations: Overview of mechanical design aspects, Line Supports, Types of poles and towers, Classification and selection criteria, Sag and Tension Calculations: Supports at equal heights, Supports at unequal heights, Effects of wind and ice loading on conductor weight, Use of sag templates and safety clearances.

Insulators and Concepts of Corona: Overhead line insulators, Types of Insulators, Methods of Improving String Efficiency. Corona – mitigation methods, Grounding

Underground Cables: Underground cables - Construction and types - Single core and multi core cables -Capacitance, Insulation resistance, Electric stresses and Dielectric loss – Grading of Cables, Capacitance Grading and Inter-sheath Grading.

AC Distribution Systems: Voltage Drop Calculations in AC Distributors for the following cases: Power Factors referred to receiving end voltage and with respect to respective load voltages.

Tasks:

T1: CompareAC and DC transmission systems with advantages and disadvantages.

T2: Derive inductance equations for:

• Single-phase two-wire systems

• Composite conductors

• Three-phase lines

T3: Derive and calculate ABCD constants for different line models.

T4: Study different types of transmission line supports and towers.

T5: Study thermal behavior and current carrying capacity of cables.

Weightage: Continuous Assessment: 40%, End Semester Examinations: 60%.

Assessment Methodology: Assignments (20%), Solution to application-oriented problems using software (20%), Solving of GATE questions (20%), Internal

Examinations (40%).

References

1. Kothari, D. P., & Nagrath, I. J. (2019). Power system engineering (3rd ed.). McGraw-Hill Publishing Company Limited.

2. Singh, S. N. (2008). Electric power generation, transmission and distribution (2nd ed.). Prentice Hall of India. https://doi.org/978-81-203-36508

3. Wadhwa, C. L. (2010). Electrical power system (6th ed.). New Age International.

4. Hardy, J. B., & Bayliss, C. R. (2011). Transmission and distribution in electrical engineering (4th ed.). Newnes Publication.

5. Wadhwa, C. L. (2006). Generation, distribution and utilization of electrical

energy (2nd ed.). New Age International Publishers.