How to improve the short-circuit resistance of transformer
- Release on :2018-04-12
How to improve the short-circuit resistance of transformer
Energy can determine whether the entire line is safe. How to ensure the stability of the transformer equipment needs to be started from the aspects of raw materials, design feasibility, timely production and maintenance, and appropriate objective environment. This article elaborates on the significance of the above factors for the project and tries to explain where it can be promoted.
Electronic power transformers are mainly implemented using power electronics technology, as shown in the implementation process. The basic principle is that the power frequency signal is converted into a high-frequency signal through the power electronic circuit in the original way, ie, up-converted, then coupled to the secondary through an intermediate high-frequency isolation transformer, and then reduced to a power frequency signal, ie, down-converted. By using appropriate control schemes to control the operation of power electronic devices, a frequency, voltage, waveform power can be transformed into another frequency, voltage, waveform power. Since the volume of the intermediate isolation transformer depends on the saturation flux density of the core material and the maximum allowable temperature rise of the core and the winding, the saturation flux density is inversely proportional to the operating frequency, so that raising the operating frequency can improve the utilization of the core. Rate, thereby reducing the size of the transformer and increasing its overall efficiency.
2 Measures to improve the ability of power transformers to withstand short-circuits The safe, economical, reliable operation and output of transformers depends on their own manufacturing quality and operating environment as well as the quality of maintenance. This chapter attempts to answer the measures to effectively prevent sudden transformer failures during the operation and maintenance of transformers. The power grid often causes short circuits due to lightning strikes, relay protection malfunctions or refusal to move, and the strong impact of short-circuit currents may damage the transformer. Therefore, efforts should be made to improve the short-circuit withstand capability of the transformer in all aspects. The statistical results of transformer short-circuit shock accidents indicate that the manufacturing causes account for about 80%, while the operation and maintenance causes only about 10%. The measures related to design and manufacturing have already been discussed in Chapter 2. This chapter focuses on the measures that should be taken during the operation and maintenance.
In the course of operation and maintenance, on the one hand, short-circuit faults should be minimized, so as to reduce the number of shocks to the transformer; on the other hand, the deformation of the transformer windings should be tested in a timely manner to prevent problems.
2.1 Fan design, pay attention to the axial compaction process of coil manufacturing In addition to considering the transformer to reduce losses and improve the insulation level, manufacturers must also consider improving the transformer's mechanical strength and short-circuit fault tolerance. In terms of manufacturing process, since many transformers use insulated pressure plates and the high and low voltage coils share a pressure plate, this structure requires a high level of manufacturing process. The pads should be densified and processed after the coils are processed. The single coil is subjected to constant pressure drying and the height of the coil after compression is measured; after the coils of the same pressure plate are processed by the above process, they are adjusted to the same height, and the assembly pressure is applied to the coil by the oil pressure device. Meet the design and process requirements. In the overall assembly, in addition to paying attention to the compression of the high voltage coil, special attention must be paid to the control of the compression of the low voltage coil. Due to the radial force, the inner coil is often pressed toward the core. Therefore, the support between the inner coil and the core column should be strengthened. The coil can be increased by increasing the number of stays and using a thicker paper tube as the coil skeleton. Radial dynamic stability.
2.2 Conduct short-circuit test on transformers to prevent the quality of the large-scale equipment of the transformers from relying on its scientific and reasonable materials and production levels, and then relying on inspection links. Various circumstances should be tested in various circumstances.
Understand its strengths and weaknesses to fully understand its performance. The short-circuit problem is inspected, and defects are repaired in time to ensure that the design and manufacturing principles are understood and the finished product performance is known.
2.3 The use of reliable relay protection and automatic reclosing system short circuit is a recurring problem, although the frequency of occurrence is relatively high, a wide range, but so far no particularly effective measures can be completely avoided or solved. The most prominent problem among these is 10KV. The cause of the short circuit is that there are human errors in running, mistakes in rats, weather damage, and improper use of household appliances such as home appliances. These are usually the most common reasons. The main response method is the necessary assembly of the DC power supply. Pay attention to the sequence when operating. More attention should be paid to the repair method must have a certain basis, can not be tampered with, otherwise not only can not complete the repair, but contrary to the opposite, it is likely to cause the entire scrapped transformer, even the opportunity to repair again.
Since the short-circuit problem is likely to self-dissolve, some organizations will consider the possibility of this self-destruction to determine whether it is necessary to choose to use coincidence between the cables, and can avoid the same by lengthening the pause between the two joints. Injuries continue to occur, damage transformers, transformers associated with short-circuit events, to do inspection records, prevention and protection combined.
4 Actively carry out deformation test and diagnosis of transformer windings After a short circuit is passed, the insulation and over-current performance of transformers that have been subjected to abnormally impinging currents are different from the original ones. It may not happen in a short time, but internal problems have already occurred. . First, the insulation performance is different. It is already unstable and may transmit electricity at any time. Once the weather is abnormal, such as lightning and thunder, it is prone to accidents, transformer damage or insulation breakdown. Secondly, its own substation capacity has been weakened. If the short circuit occurs for the second time, there will be no strong enough to support the current and burn it on itself, which will seriously endanger the surrounding things.
For the current situation, it is expensive to check whether the instrument is deformed inside the circuit. And there are certain requirements on the operation, so it is not universal enough to be suitable for large-scale use. At this time, the degree of internal deformation is often inferred by checking how much the capacitance changes, which is a simple method. Generally, this method is adopted when the conditions are poor and the normal detection method fails to meet the standards. This method is relatively easy to implement and can also reduce the variation more effectively. The emergence of pressure accidents is an extremely effective and universal form of maintaining the normal operation of the circuit and is worth considering.
2.4 Intensify the inspection during on-site construction and operation and maintenance, and use a reliable short-circuit protection system. The installation procedures of the transformer must also comply with the instructions and requirements of the instructions. Before installation, check whether the quality and specifications of the transformer are in compliance with the requirements. Do not be careless and will act accordingly. During the trial period, periodic inspections shall be carried out, maintenance work shall be well done, and small cases shall be dealt with promptly to avoid expansion, and other factors that may cause short circuits shall be given protection against transformers operating in excellent objective conditions. The preparation of direct current should be promptly put in place. This is an effective measure to protect the transformer. It advocates the logic of the program. After the operation is performed first, follow the steps. In addition, the frequency response method can detect short-circuit conditions, and should be checked frequently to help prevent it. Furthermore, it can be used to extrapolate the situation of hanging hoods. The frequency and degree of accidents can be successfully reduced, and the longest transformer life can be achieved.
Short circuit is the most prominent cause of transformer damage. A high-quality transformer is related from design to material, structure and production conditions. It is also an indispensable measure for its installation and operation and late protection. The benign operation of the transformer can indirectly drive the entire power grid to operate stably and complete the power transmission work. Therefore, protecting the voltage regulator is closely related to the protection of the power grid. It is necessary to brainstorm, obtain more preventive measures for the short circuit of the voltage regulator, and protect the voltage regulator from damage.