Transformers are crucial equipment in power systems, responsible for converting high-voltage electrical energy into low-voltage electrical energy for user consumption. During normal operation, some faults can cause impacts on the equipment and even severely affect the power system. Therefore, the design and operation of transformer protection devices are extremely important. This article will detail the principles and methods of transformer impulse energization protection.

First, let's understand the concept of transformer impulse energization. Impulse energization refers to the phenomenon where, during transformer operation, the voltage of a substation or power line suddenly increases due to external factors (such as lightning strikes, ground flashes, equipment failures, etc.). Such voltage surges often cause significant damage or even paralysis to transformers and the power system. Therefore, a series of protective measures must be taken to ensure the stable operation of the system.

The core objective of impulse energization protection is to protect the safe operation of the transformer and prevent it from being damaged by electrical surges. Common impulse energization protection devices include overvoltage protection, overcurrent protection, differential protection, and power flow protection.

The first protection device is overvoltage protection. Overvoltage refers to a transient voltage exceeding the rated voltage in a power system. Overvoltage can cause insulation breakdown in equipment, leading to internal short circuits. Overvoltage protection devices typically consist of surge arresters, winding-grounded circuit breakers, and voltage transformers. Surge arresters protect transformers by absorbing overvoltage energy, winding-grounded circuit breakers automatically disconnect the circuit when voltage is too high, and voltage transformers detect voltage waveforms to determine if overvoltage exists.

The second protection device is overcurrent protection. Overcurrent refers to a transient current exceeding the rated current in a power system. Overcurrent can cause equipment overload, overheating, or even burnout. Common overcurrent protection devices include current transformers, overcurrent protectors, and current relays. Current transformers detect current magnitude, overcurrent protectors determine the presence of overcurrent based on the current transformer signal, and current relays trigger fault signals or disconnect the circuit.

The third protection device is differential protection. Differential protection uses the difference in current between the two windings of a transformer to determine if a fault has occurred. When a transformer is operating normally, the difference in current between the two windings is very small. Once a fault occurs, the difference in current between the two windings will increase significantly. Commonly used differential protection devices include differential relays and differential current transformers. Differential relays can determine whether a transformer fault has occurred based on the differential current signal and trigger corresponding actions.

The last protection device is power flow protection. Power flow protection is a method of determining whether a fault has occurred based on the analysis of the direction and magnitude of the power system current. Commonly used power flow protection devices include current relays and current sensors. Current relays can determine whether the current exceeds the rated value based on the signal from the current sensor and trigger corresponding actions.

In summary, the protection devices for transformers during impulse energization mainly include overvoltage protection, overcurrent protection, differential protection, and power flow protection. These protection devices can determine the presence of a fault by detecting the magnitude and direction of voltage and current and trigger corresponding actions to protect the safe operation of the transformer. Furthermore, to enhance the protection effect, these protection devices can be combined to form a multi-layer protection system, thereby improving the transformer's resistance to impulse energization.

In conclusion, the protection devices for transformers during impulse energization are a crucial part of the power system, playing a vital role in protecting the safe operation of transformers and the stable operation of the power system. By operating devices such as overvoltage protection, overcurrent protection, differential protection, and power flow protection, it is possible to monitor, diagnose, and handle surge power transmission in real time, thereby ensuring the safe and reliable operation of transformers and power systems.