1. Fault analysis of transformers in power systems

A transformer is a device that utilizes the principle of electromagnetic induction to change current. It is widely used in the electric power system. Experiments and investigations have confirmed that faults caused by short circuits in transformers have been seriously affecting the safety and stability of power transmission. Therefore, in order to reduce the probability of faults in the electric power system, it is necessary to conduct a focused analysis and research on the short-circuit capability of transformers. The following provides a specific analysis of the causes leading to short-circuit accidents in transformers:

(1) Defects in the structural design of the transformer

The weakness in the short-circuit resistance of transformers is largely attributed to defects in their structural design. Currently, transformer manufacturers in China use static theory to calculate the mechanical forces on transformers. According to static theory, for copper-conductor transformers, the calculated conductor stress should be less than 1600kg/cm2. However, in actual use, the internal dynamics of transformers are complex and variable. Common theoretical values cannot intuitively reflect the actual operating conditions of transformers, making it difficult to meet the requirements for short-circuit resistance. Analyzing the currently common transformer models, low-loss transformers remain the mainstream products. However, there is no consensus among manufacturers on how to achieve low loss in transformers. Additionally, in the design of low-voltage leads for large-capacity transformers, if the fulcrum of the lead is not adequately considered, resulting in a cantilever beam formation, a phase-to-phase short-circuit fault may occur when subjected to the impact of short-circuit current.

(II) Poor material quality

The insulation pressing plate and laminated wood board of the transformer, if not meeting the standard requirements in terms of processing quality and mechanical strength, can also lead to frequent short-circuit failures. Some transformer manufacturers, in order to minimize the loss of winding eddy current, processing difficulties, and production and operation costs, often use thinner wires or ordinary and cheap transposed conductors instead of semi-rigid conductors with stronger mechanical properties during the design process. Although these ordinary and cheap materials can help enterprises reduce production and operation costs, they are unable to meet the anti-short-circuit capability of transformer windings due to the limitations of their material properties. Furthermore, due to the uneven level of domestic manufacturers and the significant gap between their production processes and some advanced foreign technologies, the density of insulation boards is insufficient, which can easily lead to natural shrinkage phenomena and trigger transformer short-circuit failures.

(III) There are serious structural issues

Serious structural issues in transformers can also lead to short-circuit faults. Since transformers undergo a series of transportation, lifting, and disassembly processes from manufacturing to deployment, they are inevitably subjected to some impacts. If the internal structure of the transformer is not sturdy, impacts can cause structural issues such as winding displacement and insulation damage, which pose significant safety hazards for future operation.

(IV) Issues of transformers operating in a 220kV environment

For 220kv high-capacity transformers, the connection status of the inner coil is also an important determinant of short-circuit faults. Although the tapping of the inner coil can provide many conveniences for the operation of high-capacity transformers, if the tapping design is not reasonable enough, it can lead to local electric field disorder in the tapping leads, resulting in partial discharge of the transformer.

(V) Problems in technology and equipment

If the manufacturing process and equipment of the transformer cannot effectively ensure the tight winding, pressing, and sheathing of the coil, it will also result in a decrease in short-circuit resistance, thereby causing faults. Moreover, if the insulating pads of the transformer are not sealed or the sealing work is not done properly, the electrodynamic force generated during a short circuit may damage the wire insulation and cause it to break down.

When winding the transformer coil, if the tension of the wire is insufficient or due to limitations in technology and equipment, the coil may be wound loosely, leading to a suspended state. This reduces the transformer's resistance to short circuits. If the coil ends are not bound tightly and securely, it can also easily cause short-circuit faults in the transformer. If the gap between the wound coils is too large, resulting in insufficient internal support of the coil, it can cause deformation or collapse of the winding coil, posing significant safety hazards for future operation. Additionally, if the clamping force of the transformer core is insufficient, and effective measurements and appropriate adjustments to the pressure are not made after the core is stacked, it can lead to loose clamping of the core, which is prone to displacement during transportation and collision, causing uneven internal stress in the transformer and resulting in serious consequences.

II. Ways to enhance the short-circuit resistance of transformers

Due to the crucial role of transformers in the power system, it is imperative to conduct in-depth research on their quality and performance. This article delves into the common causes of transformer short-circuit faults and proposes targeted technical methods to enhance the short-circuit resistance of transformers. The following provides a detailed analysis:

(1) Mechanical force calculation and product structure design for improved transformers

The physical structure of a transformer determines its operational performance. Therefore, it is necessary to optimize and improve the mechanical force calculation and product structure design of the transformer, so that the mechanical force distribution of its internal wires can better meet practical requirements and enhance its short-circuit resistance. When designing the structural design of the transformer, a pressure sensor calibrator installed between the pressure plate and the clamping piece can be used to measure the impact force on the winding structure inside the transformer, providing a reliable guarantee for the structural design of the transformer.

(II) Short-circuit test of transformer

By conducting short-circuit tests on transformers and analyzing relevant data parameters, a solid foundation is laid for improving the product structure of transformers and enhancing their resistance to short circuits. It is worth noting in this process that conducting short-circuit tests is not only to ensure that the manufacturer's products are qualified, but more importantly, to apply safe and reliable technology to actual production, avoiding the situation where some manufacturers only test and reinforce transformers without promoting technology in actual production.

In summary, with the continuous advancement of science and technology, the continuous improvement of power system operation quality, and the widespread operation of ultra-high voltage power transmission and transformation methods, the short-circuit resistance of transformers and the huge losses caused by short circuits have become an important issue that transformer manufacturers and operation units face and urgently need to address. In order to effectively enhance the short-circuit resistance of power system transformers, in addition to requiring manufacturers to make *** improvements in mechanical force calculation and product structural design, attention should also be paid to potential quality hazards in process operations. These issues require high attention from transformer manufacturers and operation units, so as to *** enhance the safety and stability of power system operation.

In summary, as the transformation of the power grid progresses, it is imperative to enhance the short-circuit resistance of transformers in the power system to meet development needs. Improving the short-circuit resistance of transformers in the power system not only effectively enhances the safety of mining area power grid operations but also reduces the time required for fault handling, maximizes loss reduction, and prevents accidents, ensuring the safe and stable operation of the power system.