WorksheetsElectrical Grid Situational-Based MCQs-Basic to Intermediate
Total questions: 40
Worksheet time: 20mins
If the frequency in the electrical grid drops significantly, what should be done?
Increase reactive power
Increase generation to match demand
Disconnect all consumers
Increase transformer tap
During peak hours, the load on the grid increases. What is the typical operator response?
Disconnect a power plant
Start peaker plants or load shedding
Lower voltage
Shut down grid
What does a grid-connected solar plant do when the grid fails?
Keeps operating
Switches to battery
Trips off for safety (anti-islanding)
Increases power
Why is 50 Hz commonly used in power systems?
To match electronic devices
Historical and engineering compromise between size and efficiency
Because of lightning
To avoid voltage drop
What is a consequence of high reactive power in the grid?
Increased power factor
Overvoltage
Reduced efficiency and heating in lines
Reduced current
What is the function of SCADA in electrical grid monitoring?
Cooling transformers
Real-time data acquisition and remote control
Wireless charging
Phase synchronization
The grid frequency in India is:
60 Hz
50 Hz
45 Hz
55 Hz
What is the role of substations in the grid?
Lighting
Voltage transformation and switching
Energy storage
Noise removal
A fault in one transmission line leads to increased load on adjacent lines. This is known as:
Load shedding
Islanding
Cascading failure
Frequency trip
What device protects the grid from overcurrents?
Reactor
Circuit breaker
Voltage regulator
Capacitor
How is power factor improved in distribution grids?
Use of resistors
Use of capacitors or synchronous condensers
Increase transmission voltage
Reduce frequency
What is the function of load dispatch center?
Billing
Real-time control and balancing generation-demand
Transmitting electricity
Monitoring cables only
Why are high voltages used for power transmission?
Less transformer use
Reduce I²R losses
Better synchronization
Lower generation costs
A lightning strike on a transmission line is managed by:
Fuses
Earth wires and lightning arrestors
Increase voltage
Shut down grid
What causes voltage sag in a grid?
Fault or sudden large load
High power factor
Capacitor bank
Load shedding
Grid harmonics cause:
Better efficiency
Distortion, overheating of equipment
Voltage increase
Low frequency
What type of system ensures uninterrupted power in industries during grid failure?
VFD
UPS or DG backup
Transformer
Capacitor bank
Reactive power is measured in:
kWh
kVA
kVAr
Ampere
Why are transformers rated in kVA?
Because they store energy
Independent of power factor; accounts for both active and reactive
Because they regulate frequency
For uniformity
Why are busbars used in substations?
For lighting
For flexible power distribution among different feeders
For voltage transformation
For insulation
A sudden disconnection of a large generator from the grid results in:
Frequency increase
Frequency drop and underfrequency protection activation
Voltage overshoot
Synchronization
In an interconnected grid, a tie-line helps:
Store power
Transfer power between regions and maintain frequency balance
Lower frequency
Protect SCADA
In case of fault current exceeding the rating of a circuit breaker, what system is added?
Relay
Current transformer
Backup breaker or series reactor
Fuse
What is the key parameter monitored by an Automatic Generation Control (AGC)?
Power factor
Frequency deviation and tie-line power
Line voltage
Breaker status
In real-time grid operations, Area Control Error (ACE) refers to:
Energy difference
Difference in scheduled and actual power flow and frequency
Power loss
Voltage error
A wind turbine generator connected to the grid must synchronize:
Only voltage
Voltage, frequency, and phase angle
Just current
Temperature
A large-scale solar PV plant output is fluctuating due to cloud cover. How does the grid handle this?
Disconnect PV
Use spinning reserves or battery storage
Increase fault level
Bypass transformer
Frequency relays in the grid are used to:
Control voltage
Shed load during underfrequency to avoid blackout
Detect overcurrent
Maintain PF
What is load frequency control responsible for?
Voltage control
Managing real power balance and system frequency
Reactive power sharing
Ground fault detection
What type of compensation is applied to long transmission lines to prevent voltage drop?
Series capacitive compensation
Shunt inductance
Line reactor
Open circuit
In a smart grid, Advanced Metering Infrastructure (AMI) enables:
Voltage transformation
Bi-directional communication and real-time monitoring of usage
Harmonic elimination
Load dumping
The function of a synchrophasor (PMU) in grid monitoring is:
Load switching
Real-time phasor measurement of voltage and current for dynamic stability monitoring
Energy billing
Transformer tap change
In case of islanding detection, what method is most commonly used?
Overcurrent
Voltage sag
ROCOF (Rate of Change of Frequency) or impedance measurement
Thermal overload
If a grid suffers low voltage due to high demand, how is it mitigated?
Add shunt capacitors or reduce load
Lower frequency
Disconnect generators
Turn off SCADA
In an HVDC link, the power flow is controlled by:
Transformers
Phase angle
Converter control (alpha angle or firing angle)
AVR
The typical communication protocol in substation automation is:
Modbus
IEC 61850
BACnet
RS-232
What does the term 'grid inertia' refer to?
Load flow stability
Resistance to change in frequency due to stored kinetic energy in rotating machines
Synchronizing torque
Voltage regulation
What is the disadvantage of a weak grid?
Easier to control
Prone to voltage and frequency instability under fluctuating loads or renewable integration
Less fault current
More efficiency
In reactive power compensation, STATCOM is used for:
Power measurement
Dynamic reactive power injection for voltage control
Short circuit detection
Power theft monitoring
A transformer under high load has reduced voltage at the secondary. What compensates it automatically?
Earth wire
On Load Tap Changer (OLTC)
Overcurrent relay
SCADA
