Grid integration of renewable sources – MCQs – EE

1. Grid integration refers to:
(A) Connecting renewable energy sources to the power grid
(B) Isolating renewable systems from the grid
(C) Disconnecting loads from the grid
(D) Reducing grid voltage

2. The main challenge in grid integration of renewable energy is:
(A) High voltage
(B) Intermittency and variability of power generation
(C) Low cost
(D) Constant output

3. The power electronic device commonly used in renewable grid integration is:
(A) Transformer
(B) Inverter
(C) Inductor
(D) Relay

4. The function of an inverter in renewable energy systems is to:
(A) Convert AC to DC
(B) Convert DC to AC
(C) Store electrical energy
(D) Step up voltage

5. Grid synchronization ensures that:
(A) Frequency and voltage of the renewable source match the grid
(B) The power system operates in isolation
(C) The power output remains DC
(D) The load is disconnected from the source

6. Which renewable source requires a maximum power point tracking (MPPT) controller for grid integration?
(A) Wind energy
(B) Solar PV systems
(C) Hydro power
(D) Geothermal power

7. Reactive power control in grid-connected systems helps maintain:
(A) Power factor and voltage stability
(B) Mechanical speed
(C) Frequency deviation
(D) Energy storage

8. A grid-tied solar inverter must have:
(A) Isolated operation capability
(B) Anti-islanding protection
(C) Mechanical linkage
(D) DC excitation

9. Islanding occurs when:
(A) The renewable system continues to supply power after grid failure
(B) The system is connected to the grid
(C) The inverter shuts down
(D) The voltage is regulated

10. Which renewable energy source produces AC power directly?
(A) Solar PV
(B) Fuel cells
(C) Wind turbine (with generator)
(D) Battery

11. The grid frequency in most countries is:
(A) 25 Hz
(B) 50 or 60 Hz
(C) 100 Hz
(D) 400 Hz

12. Power quality issues due to renewable energy integration include:
(A) Harmonics
(B) Voltage fluctuation
(C) Frequency deviation
(D) All of the above

13. The device used to control the power flow from renewables to the grid is:
(A) Converter
(B) Controller
(C) Transformer
(D) Switchgear

14. Smart grids help in renewable energy integration by:
(A) Increasing energy losses
(B) Enabling real-time monitoring and control
(C) Reducing automation
(D) Disconnecting renewables

15. Net metering is a system that:
(A) Measures only energy consumed from the grid
(B) Allows export of excess renewable energy to the grid
(C) Blocks reverse power flow
(D) Measures only solar generation

16. The synchronization of voltage, frequency, and phase angle is required for:
(A) Grid connection
(B) Battery charging
(C) Load reduction
(D) Transformer operation

17. The power output of wind turbines is highly dependent on:
(A) Air pressure
(B) Wind speed
(C) Temperature
(D) Blade color

18. Distributed generation refers to:
(A) Centralized large-scale power plants
(B) Small-scale renewable power sources near load centers
(C) Long-distance transmission systems
(D) High-voltage substations only

19. Which control strategy helps stabilize voltage during grid disturbances?
(A) Frequency droop control
(B) MPPT control
(C) PID temperature control
(D) Power limiting control

20. Power factor correction in grid-connected systems is achieved using:
(A) Capacitor banks
(B) Inductors
(C) Resistors
(D) Transformers

21. Inverters used for grid integration are required to comply with:
(A) IEC and IEEE standards
(B) Mechanical standards
(C) Safety-only guidelines
(D) Local voltage color codes

22. Grid codes define:
(A) Electrical, voltage, and frequency requirements for grid connection
(B) Computer network protocols
(C) Transmission line layouts
(D) Renewable fuel types

23. The power flow from the grid to renewable sources is controlled by:
(A) Bidirectional converters
(B) Step-down transformers
(C) Rectifiers only
(D) Relays

24. Which renewable source typically uses a doubly-fed induction generator (DFIG) for grid integration?
(A) Solar PV
(B) Wind turbine
(C) Geothermal
(D) Biomass plant

25. Voltage dips and flicker in the grid are caused by:
(A) Sudden change in renewable power output
(B) Stable grid frequency
(C) Constant generation
(D) Balanced load

26. Grid stability during renewable integration is enhanced by using:
(A) Energy storage systems
(B) Resistive loads
(C) Low voltage cables
(D) Transformers only

27. The term “ancillary services” in grid integration refers to:
(A) Backup services that support grid stability
(B) Transmission losses
(C) Metering services only
(D) Power billing

28. Power fluctuations from renewable sources can be smoothed by:
(A) Flywheels and batteries
(B) Mechanical filters
(C) Voltage dividers
(D) Step-up transformers

29. The main advantage of grid-connected renewable systems is:
(A) No need for energy storage
(B) No transmission losses
(C) Continuous backup from the grid
(D) Both (A) and (C)

30. The ultimate goal of grid integration of renewable sources is to:
(A) Increase carbon emissions
(B) Ensure reliable, clean, and stable power supply
(C) Disconnect conventional power plants
(D) Eliminate grid frequency