(SEM VIII) THEORY EXAMINATION 2021-22 INTRODUCTION TO SMART GRID

SECTION A

(Attempt all questions in brief – 10 × 2 = 20 marks)

(a) Need of Smart Meters

Smart meters are required for accurate energy measurement, real-time billing, remote meter reading, demand management, and reduction of power theft.

(b) Smart Grid

A smart grid is an advanced electricity network that uses digital communication, automation, and control technologies to improve reliability, efficiency, and sustainability of power systems.

(c) Concept of Smart Grid Technologies

Smart grid technologies include smart meters, sensors, communication networks, automation systems, and data analytics that enable two-way flow of power and information.

(d) Smart Substations

Smart substations use digital devices, intelligent electronic devices (IEDs), and communication systems to monitor, protect, and control power flow automatically and efficiently.

(e) Self-Healing Grid

A self-healing grid can automatically detect faults, isolate affected sections, and restore power supply without human intervention.

(f) Power Quality in Smart Grid

Power quality refers to maintaining voltage, frequency, and waveform within acceptable limits to ensure reliable and disturbance-free power supply.

(g) Microgrids

Microgrids are small-scale power systems with local generation, storage, and loads that can operate independently or connected to the main grid.

(h) Feeder Automation

Feeder automation uses sensors and control devices to monitor and automatically manage distribution feeders for faster fault detection and restoration.

(i) Energy Resources

Energy resources include conventional sources (coal, gas) and renewable sources (solar, wind, hydro) used for electricity generation.

(j) Power Quality Management

Power quality management involves monitoring, controlling, and improving power parameters to reduce disturbances and improve system performance.

SECTION B

(Attempt any THREE – 10 × 3 = 30 marks)

2(a) Power Quality Issues of Grid-Connected Renewable Energy Sources

Renewable energy sources such as solar and wind introduce power quality issues like voltage fluctuations, harmonics, flicker, frequency variation, and poor power factor. These issues arise due to intermittent nature of renewables and power electronic converters. Power quality conditioners, energy storage, and smart control techniques are used to mitigate these problems and ensure grid stability.

2(b) Real-Time Pricing under Smart Grid Technologies

Real-time pricing allows electricity prices to vary based on demand and supply conditions. Smart meters and communication systems inform consumers about current prices, encouraging load shifting during off-peak hours. This improves energy efficiency, reduces peak demand, and benefits both utilities and consumers.

2(c) Intelligent Electronic Devices (IEDs) and Applications

IEDs are microprocessor-based devices used for protection, control, and monitoring in smart grids. They perform functions like fault detection, relay protection, data logging, and communication with control centers. IEDs enhance system reliability and reduce outage time.

2(d) Need and Application Areas of Microgrids

Microgrids are needed for reliable power supply, integration of renewable energy, and energy security. They are used in hospitals, campuses, military bases, rural electrification, and industrial areas. Microgrids reduce transmission losses and improve power quality.

2(e) Concept and Evolution of Electric Grid

The electric grid evolved from a conventional centralized system to a smart grid with digital control. Earlier grids allowed one-way power flow, while smart grids support two-way power and information flow, automation, renewable integration, and active consumer participation.

SECTION C

3(a) Power Quality Conditioners for Smart Grid

Power quality conditioners such as STATCOM, DVR, UPQC, and active filters are used to control voltage sag, harmonics, and power factor issues. These devices improve stability, efficiency, and reliability of smart grids by maintaining quality power supply.

3(b) Automatic Meter Reading (AMR) & Outage Management System (OMS)

Automatic Meter Reading (AMR):
AMR automatically collects consumption data from smart meters and sends it to utilities, reducing manual errors and billing delays.

Outage Management System (OMS):
OMS identifies power outages, locates faults, and helps utilities restore power quickly, improving service reliability.

4(a) Opportunities and Barriers of Smart Grid

Smart grids offer opportunities like improved reliability, renewable integration, reduced losses, and consumer participation. Barriers include high initial cost, cybersecurity concerns, lack of standards, and need for skilled workforce.

4(b) WAMS and Compressed Air Energy Storage

Wide Area Measurement System (WAMS):
WAMS uses PMUs and communication networks to monitor large power systems in real time.

Compressed Air Energy Storage:
It stores energy by compressing air and releases it to generate electricity during peak demand.

5(a) Protection and Control of Microgrids

Microgrid protection involves adaptive relays, communication systems, and control strategies to manage islanded and grid-connected modes safely and reliably.

5(b) Web-Based Power Quality Monitoring

Web-based monitoring systems use sensors and internet platforms to continuously track power quality parameters and provide remote access to data.

6(a) PHEVs and Smart Sensors

Plug-in Hybrid Electric Vehicles (PHEVs):
PHEVs use both electric motors and IC engines and can interact with smart grids for charging and energy management.

Smart Sensors:
Smart sensors measure electrical parameters and send real-time data for monitoring and control.

6(b) Difference between Conventional Grid and Smart Grid

Conventional grid has one-way power flow and manual control, while smart grid has two-way communication, automation, self-healing, and renewable integration.

7(a) PMUs in Monitoring and Control of Power System

Phasor Measurement Units (PMUs) measure voltage and current phasors in real time. They help in stability analysis, fault detection, and wide-area monitoring.

7(b) Integration of Renewable Energy Sources

Renewable integration involves connecting solar, wind, and other clean sources to the grid using power electronics, storage systems, and smart control to ensure reliable and stable operation.