JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY HYDERABAD

Prerequisite

Power Systems

Course Objectives:

• To understand the dependency of voltage on reactive power, factors affecting the voltage collapse.
• To know various graphical methods to understand voltage collapse phenomenon.
• To comprehend voltage stability analysis of simple systems.

Course Outcomes

Upon the completion of the subject, the student will be able to

• Have knowledge related to voltage collapse phenomenon and factors affecting it.
• Analyse various power system loads for voltage stability.
• emphasize reactive power compensation techniques & their practical importance

UNIT - I

Introduction to Voltage Stability: Definitions: Voltage Stability, Voltage Collapse, Voltage Security; Physical relation indicating dependency of voltage on reactive power flow; Factors affecting Voltage collapse and instability; Previous cases of voltage collapse incidences.

UNIT - II

Graphical Analysis of Voltage Stability: Comparison of Voltage and angular stability of the system; Graphical Methods describing voltage collapse phenomenon: P-V and Q-V curves; detailed description of voltage collapse phenomenon with the help of Q-V curves.

UNIT - III

Analysis of Voltage Stability: Analysis of voltage stability on SMLB system: Analytical treatment and analysis. Voltage Stability Indices: Voltage collapse proximity indicator; Determinant of Jacobin as proximity indicators; Voltage stability margin.

UNIT - IV

Power System Loads: Loads that influences voltage stability: Discharge lights, Induction Motor, Air- conditioning, heat pumps, electronic power supplies, OH lines, and cables. Reactive Power Compensation: Generation and Absorption of reactive power; Series and Shunt compensation; Synchronous condensers, SVC s; OLTC s; Booster Transformers.

UNIT - V

Voltage Stability Margin: Stability Margin: Compensated and un-compensated systems. Voltage Security: Definition; Voltage security; Methods to improve voltage stability and its practical aspects.

TEXT BOOKS:

• 1. “Performance, operation and control of EHV power transmission system”- A. Chakrabarthy, D. P. Kotari and A. K. Mukopadyay, A.H. Wheeler Publishing, I Edition, 1995.
• 2. “Power System Dynamics: Stability and Control” – K. R. Padiyar, II Edition, B.S. Publications.

REFERENCE:

• 1. “Power System Voltage Stability”- C.W. Taylor, McGraw Hill, 1994. M. TECH – I YEAR – I SEM. (PS H.V. Engg. / H.V. Engg.) ADVANCED POWER SYSTEM Protection (Professional Elective – II)

Prerequisite

Switch Gear and Protection

Course objectives:

• To know construction of static relays
• To understand the operation of amplitude and phase comparators
• To comprehend the concepts of Static over current, static differential and static distance relays.
• To understand multi-input comparators and concept of power swings on the distance relays.
• To know the operation of microprocessor based protective relays. Course outcomes: After the completion of this course, student will be able to
• Describe the construction of static relay and identify the advantages of static relay over electromagnetic relay.
• Explore the operation of rectifier bridge comparators, instantaneous comparators, phase comparators, multi input comparators, static differential and distance relays
• Describe instantaneous, definite time and inverse definite minimum time over current relays.
• Analyze the concept of power swings on distance relays and to identify the microprocessor based protective relays and their operation

UNIT - I

Static Relays: Advantages of static relays - Basic construction of static relays - Level detectors - Replica impedance – Mixing circuits - General equation for two input phase and amplitude comparators -Duality between amplitude and phase comparators. Amplitude Comparators: Circulating current type and opposed voltage type - rectifier bridge comparators, Direct and Instantaneous comparators.

UNIT - II

Phase Comparators: Coincidence circuit type - block spike phase comparator, techniques to measure the period of coincidence - Integrating type - Rectifier and Vector product type - Phase comparators. Static Over Current Relays: Instantaneous over-current relay - Time over-current relays-basic principles – definite time and Inverse definite time over-current relays.

UNIT - III

Static Differential Relays: Analysis of Static Differential Relays – Static Relay schemes – Duo bias transformer differential protection – Harmonic restraint relay. Static Distance Relays: Static impedance-reactance – MHO and angle impedance relay-sampling comparator – realization of reactance and MHO relay using sampling comparator.

UNIT - IV

Multi-Input Comparators: Conic section characteristics -Three input amplitude comparator – comparator-switched distance schemes – Poly phase distance schemes - phase fault scheme – three phase scheme – combined and ground fault scheme.

Power Swings: Effect of power swings on the performance of distance relays – Power swing analysis - Principle of out of step tripping and blocking relays - effect of line and length and source impedance on distance relays.

UNIT - V

Microprocessor Based Protective Relays: (Block diagram and flowchart approach only) - Over current relays – impedance relays - directional relay - reactance relay - Generalized mathematical expressions for distance relays -measurement of resistance and reactance – MHO and offset MHO relays - Realization of MHO characteristics - Realization of offset MHO characteristics - Basic principle of Digital computer relaying.

TEXT BOOK:

• 1. Badri Ram and D. N. Vishwakarma, “Power system protection and Switch gear “, TMH publication New Delhi 1995.

REFERENCES:

• 1. T.S. Madhav aRao , “Static relays”, TMH publication, second edition, 1989.
• 2. Protection and Switchgear, Bhavesh Bhalja, R. P. Maheshwari, Nilesh G. Chothani, Oxford University Press.
• 3. Electrical Power System Protection, C. Christopoulos and A. Wright, Springer International. M. Tech – I Year – I Sem. (PS H.V. Engg. / H.V. Engg.)