Short Answer:

A transformer is a static electrical device used to transfer electrical energy from one circuit to another without any physical connection. It works on the principle of electromagnetic induction and is widely used to increase (step-up) or decrease (step-down) voltage levels in alternating current (AC) systems. It plays a vital role in electrical power transmission and distribution systems by ensuring efficient energy transfer over long distances.

The basic function of a transformer is to change the voltage level as per the requirement of the electrical load, while keeping the frequency constant. It consists of two coils—primary and secondary—wound around a magnetic core. When an AC voltage is applied to the primary coil, it generates a magnetic field that induces a voltage in the secondary coil, thus transferring energy from one side to the other without any direct electrical contact.

Detailed Explanation:

Islanding in power systems

Islanding is an important concept in modern power systems, especially with the increased use of distributed energy resources such as solar panels, wind turbines, and local generators. When the main grid fails or is disconnected due to faults, protection operations, or maintenance, some portions of the network with their own generation sources can become isolated and continue to operate. This condition is known as islanding.

What is Islanding

Islanding occurs when a portion of the electrical grid that includes both generators and loads continues to operate even though it is electrically separated from the larger utility grid. The local generators supply power to the local loads, forming a self-sustained “island” of electricity.

Types of Islanding

• Intentional Islanding
  This is planned and controlled. It is used in microgrids, remote areas, or critical facilities like hospitals, data centers, and military bases where the power must stay on even during grid failures.
• Unintentional Islanding
  This happens accidentally when the grid fails but local generators keep working without realizing the loss of the main supply. This is dangerous and must be detected quickly to shut down the generators and prevent accidents.

How Islanding Works

• During normal operation, local generation and loads are synchronized with the utility grid.
• If the grid fails or a breaker opens due to a fault, the local section may get disconnected.
• If the local generator output closely matches the load demand, it may continue running without detection.
• This creates an islanded condition where the local system runs independently from the grid.

Risks and Problems with Islanding

• Safety Hazard
  Utility workers may be exposed to electric shock if lines thought to be de-energized are still powered from an islanded source.
• Equipment Damage
  Fluctuations in voltage and frequency can damage sensitive electrical appliances and industrial machines.
• Synchronization Issues
  Reconnecting an unsynchronized island to the grid can cause large current surges and blackouts.

Islanding Detection Methods

• Passive Methods
  These methods monitor system parameters like voltage, frequency, and phase. Sudden changes can indicate islanding.
• Active Methods
  These involve injecting a small disturbance or signal into the system to check if the grid is present or not.
• Communication-Based Methods
  These methods rely on signals or commands between the utility and the generation units to detect disconnection.

Role of Inverters and Smart Devices

Modern solar inverters are designed to detect islanding and disconnect within 2 seconds as per IEEE 1547 standards. Smart grid technologies and advanced communication systems help in early detection and safe handling of islanding conditions.

Islanding in Microgrids and Renewable Systems

• Use in Microgrids
  In some smart power systems, intentional islanding is used to keep critical loads powered during grid failures. This is common in areas powered by renewable energy or battery storage.
• Renewable Integration
  With more solar and wind systems being installed, islanding awareness and prevention become even more critical to ensure grid safety and power quality.

Conclusion

Islanding in power systems refers to the condition where a section of the power network continues to operate independently after being cut off from the main grid. While it can be useful in planned microgrids, unintentional islanding poses safety and stability risks. That’s why detecting islanding quickly and shutting it down when necessary is very important. With the rise of renewable energy and distributed generation, understanding and managing islanding is crucial for a safe and reliable power system.