Voltage regulating transformer lead structure for electric furnace system

Abstract

The utility model relates to a kind of voltage regulating transformer lead structure for electric furnace system, mainly by main transformer, auxiliary transformer, voltage regulating assembly and control unit composition. Main transformer provides first fixed voltage output, auxiliary transformer is connected with main transformer, and output adjustable voltage. Voltage regulating assembly includes coarse adjustment unit and fine adjustment unit, coarse adjustment unit is realized by no-load switching multiple state excitation, and fine adjustment unit is realized by on-load switching multiple step arithmetic progression voltage regulation. Control unit coordinates the switching of coarse adjustment unit and fine adjustment unit, realizes voltage regulation in wide range. Main transformer provides constant magnetic flux excitation, voltage regulating assembly and main transformer jointly form combined excitation path, adjust auxiliary transformer input voltage, to expand voltage regulating series.

Description

Technical Field

[0001] This utility model relates to a voltage regulating transformer lead structure for an electric furnace system. Background Technology

[0002] Electric furnaces are key thermal equipment in modern industry, widely used in metallurgy, chemical industry, and building materials industry. For example, they are used in metallurgy to smelt alloy steel, in chemicals to produce yellow phosphorus and calcium carbide, and in building materials for glass and ceramics manufacturing.

[0003] As the core power supply component of an electric furnace, the transformer is responsible for converting high-voltage electrical energy into low-voltage electrical energy suitable for the furnace and providing stable voltage regulation capabilities. Existing transformer lead structures mainly include concentric, interleaved, series, and autotransformer types, but all have certain shortcomings.

[0004] Concentric structures save materials, but the use of variable flux voltage regulation results in uneven secondary voltage levels, affecting constant current control and product quality. Interleaved structures are suitable for short-circuit conditions and allow impedance adjustment, but the interleaved arrangement of high and low voltage coils leads to large potential differences, easy creepage, high cost, and poor reliability. Series structures combine the constant flux of the main transformer with the variable flux of the auxiliary transformer to achieve differential voltage regulation, but the number of regulation levels is limited to a maximum of 35. Autotransformer voltage regulation structures can achieve 63 voltage levels, offering a wide range, but due to low impedance, they have poor short-circuit and overload resistance, making them prone to transformer damage due to secondary short circuits during electric furnace operation, resulting in economic losses.

[0005] In summary, the existing lead structure of electric furnace transformers still has limitations in terms of voltage regulation range, safety and stability, making it difficult to meet the operational requirements under complex working conditions. There is an urgent need to optimize the design to improve system performance and reliability. Utility Model Content:

[0006] The purpose of this invention is to overcome the shortcomings of the prior art and provide a voltage regulating transformer lead structure for an electric furnace system.

[0007] A voltage regulating transformer lead structure for an electric furnace system, the main transformer being used to provide a first fixed voltage output;

[0008] An auxiliary transformer, connected to the main transformer, is used to output an adjustable voltage;

[0009] The voltage regulating component includes a coarse adjustment unit and a fine adjustment unit. The coarse adjustment unit achieves multi-state excitation through no-load switching, and the fine adjustment unit achieves multi-stage differential voltage regulation through on-load switching.

[0010] The control unit coordinates the switching between the coarse adjustment unit and the fine adjustment unit to achieve output voltage regulation over a wide range.

[0011] The main transformer provides constant magnetic flux excitation, and the voltage regulating component forms a combined excitation path with the main transformer to adjust the input voltage of the auxiliary transformer, thereby realizing the expansion of the voltage regulation stage.

[0012] Furthermore, the high-voltage winding of the main transformer is connected in a delta configuration to form a third harmonic current loop to accommodate unbalanced loads.

[0013] Furthermore, the low-voltage windings of both the main transformer and the auxiliary transformer are of an "8-shaped" structure to enhance mechanical strength and short-circuit withstand capability.

[0014] Furthermore, the coarse adjustment unit includes three operating states: forward excitation, reverse excitation, and no excitation, which are used to achieve voltage boost, voltage reduction, and voltage neutralization, respectively.

[0015] Furthermore, the fine-tuning unit employs a four-helix coil to improve the coil's manufacturability and adjustment accuracy.

[0016] Furthermore, the control unit includes an off-load tap changer and an on-load tap changer, which respectively control the switching of the coarse adjustment unit and the fine adjustment unit.

[0017] Furthermore, the voltage regulating component is configured to achieve 90 levels of differential voltage regulation.

[0018] Beneficial Effects: This voltage regulating transformer lead structure for electric furnace systems offers significant advantages in voltage control accuracy and response efficiency. By introducing a constant flux operating mode for the main transformer, a stable output reference voltage can be achieved. The auxiliary transformer receives an adjustable input voltage from the voltage regulating components, enabling continuous and precise voltage control. The fine-tuning unit employs a four-helix coil design, greatly improving the precision and response sensitivity of the voltage regulation process, achieving up to 90 levels of differential voltage adjustment, fully meeting the needs of high-precision voltage regulation scenarios.

[0019] In terms of structural design, this invention successfully forms an effective harmonic current loop through the delta connection of the high-voltage winding of the main transformer, significantly suppressing the influence of third harmonics. This is particularly suitable for unbalanced load conditions commonly found in electric furnace systems, enhancing system stability and power quality. Simultaneously, the low-voltage windings of both the main and auxiliary transformers adopt an "8-shaped" structure, effectively improving short-circuit withstand capability and mechanical strength, preventing winding deformation caused by electromagnetic force impact, extending equipment lifespan, and enhancing overall system reliability.

[0020] In terms of voltage regulation, the coarse adjustment unit in this structure can switch between three states: forward excitation, reverse excitation, and no excitation. Combined with no-load tap changer control, it can achieve fast and precise coarse voltage adjustment control, improving the response speed of voltage adjustment. The fine adjustment unit works with the on-load tap changer to continuously switch voltage levels, ensuring the stability and linearity of voltage control. The synergistic effect of coarse and fine adjustment gives the overall system a wide-range, precise, and efficient voltage regulation capability.

[0021] Furthermore, in terms of voltage regulation accuracy and level expansion capability, this voltage regulating component forms a three-level voltage state combination through a combination of coarse and fine adjustment control. Each level is further divided through fine adjustment to achieve a refined 90-level differential voltage output, which greatly expands the system's voltage adaptability under different operating conditions and load changes.

[0022] Overall, this invention has significant improvements and enhancements in many aspects, including system stability, voltage regulation response speed, voltage control accuracy, equipment structural strength, and operational safety, and is suitable for widespread application in industrial systems such as electric furnaces that require high-frequency voltage regulation.

[0023] Furthermore, this structure successfully expands the voltage regulation ratio of the series transformer from a maximum of 250% to 530%. The number of voltage regulation stages has also increased from 35 to 90, and the main transformer's high-voltage base coil and voltage regulation coil are independent, resulting in strong short-circuit withstand capability. This invention reduces user investment. Previously, in ceramic smelting, to achieve the same function, users needed to order two transformers—one for raw material production and one for finishing. Now, only one is needed, reducing the footprint and potentially reducing user investment by approximately 45%. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the lead structure of a voltage regulating transformer;

[0025] In the diagram, 1 is the on-load tap changer, 2 is the off-load tap changer, 3 is the coarse adjustment unit, 4 is the fine adjustment unit, and 5 is the low-voltage winding. Detailed Implementation

[0026] To enhance understanding of this utility model, the present utility model will be further described in detail below with reference to the embodiments and accompanying drawings. These embodiments are only used to explain the present utility model and do not constitute a limitation on the scope of protection of the present utility model.

[0027] A voltage regulating transformer lead structure for an electric furnace system includes a main transformer, an auxiliary transformer, a voltage regulating assembly, and a control unit. The main transformer provides a fixed voltage, while the auxiliary transformer receives the regulated input voltage and provides an adjustable output voltage. Specifically, the main transformer operates in a constant flux mode and works in conjunction with the coarse and fine adjustment units 4 of the voltage regulating assembly. The coarse adjustment unit 3 switches the excitation state through no-load switching, while the fine adjustment unit 4 performs fine voltage adjustments through on-load switching, thereby controlling the input voltage of the auxiliary transformer to meet the wide-range voltage regulation requirements of the electric furnace system. This structure expands the number of voltage regulation stages through combined excitation paths, providing highly efficient voltage regulation capabilities.

[0028] In this example, the high-voltage winding of the main transformer adopts a delta connection. In practice, the harmonic current loop formed by this delta-connected winding can effectively suppress the impact of third harmonics on the transformer and the system, making it suitable for the frequently occurring unbalanced load conditions in electric furnace systems, thereby improving the stability and load adaptability of the transformer operation.

[0029] In this example, both the low-voltage windings 5 ​​of the main transformer and the auxiliary transformer adopt an "8-shaped" structural design. In practice, this design, through the special arrangement of the windings, significantly enhances mechanical strength and short-circuit withstand capability, effectively prevents winding deformation caused by electromagnetic forces, extends the service life of the equipment, and ensures the safe operation of the transformer.

[0030] In this example, the coarse adjustment unit 3 is specifically implemented with three states: forward excitation, reverse excitation, and no excitation. In actual operation, when a voltage increase is needed, the coarse adjustment unit 3 enters the forward excitation state; when a voltage decrease is needed, it enters the reverse excitation state; and when no adjustment is needed, it remains in the no-excitation state. This method achieves fast and efficient voltage coarse adjustment, improving the voltage adjustment response speed.

[0031] In this example, the fine-tuning unit 4 uses a four-helix coil. During implementation, this structure enhances the coil's manufacturability and precision control capabilities, making coil manufacturing more convenient and voltage regulation more precise, thereby improving the overall fine voltage regulation effect of the transformer system and meeting the requirements for high-precision voltage control.

[0032] In this example, the control unit specifically includes an off-load tap changer 2 and an on-load tap changer. In practice, the off-load tap changer 2 is specifically used for switching the excitation state of the coarse adjustment unit 3, and the on-load tap changer is specifically used for switching the voltage level of the fine adjustment unit 4. The two work together to achieve precise voltage regulation control, ensuring the safety and stability of the transformer under different load conditions.

[0033] In this example, the voltage regulating component can achieve 90 levels of differential voltage regulation. In actual operation, through the multi-state switching of the coarse adjustment unit 3 and the multi-level precision adjustment of the fine adjustment unit 4, a fine 90-level voltage adjustment can be achieved, greatly expanding the voltage adjustment range of the electric furnace system, improving its adaptability to different operating conditions and loads, and ensuring the stable and reliable operation of the system.

[0034] Working principle: The main grid voltage connected to the transformer's base coil is typically 15KV, remaining essentially constant. Therefore, the main transformer operates in a constant flux state. The number of turns in the low-voltage coil of the main transformer is fixed, resulting in a constant induced voltage U21. The no-load tap changer 2 has three positions, and the voltage regulation process mainly consists of the following three stages:

[0035] (1) When the no-load tap changer 2 is in the first position, the on-load tap changer 1K is connected to the "+" terminal, and the moving contact is in position ①. The coarse adjustment coil and fine adjustment coil of the main transformer are simultaneously in a positive energized state. Their voltages are superimposed and applied to the high-voltage coil of the auxiliary transformer. At this time, the input voltage borne by the auxiliary transformer reaches its maximum value, and the voltage U22 induced in the low-voltage coil of the auxiliary transformer reaches its maximum value, thus the transformer outputs the highest voltage. When the on-load tap changer 1 is adjusted from position ① to position ② step by step, since the main transformer is in a constant flux state and the number of turns in each stage is equal, the voltage difference applied to the high-voltage coil of the auxiliary transformer is consistent. The induced voltage U22 on the secondary side of the auxiliary transformer decreases arithmetically, and the transformer output voltage decreases step by step.

[0036] (2) When the no-load tap changer 2 is in the second position, the high-voltage coil of the auxiliary transformer is only connected to the fine-tuning coil of the main transformer, which is equivalent to a conventional series transformer. At this time, the coarse-tuning coil is not working. When the on-load tap changer 1K is in the "+" position, the transformer output voltage is relatively high; while when it is in the "-" position, the output voltage is relatively low, thereby realizing voltage regulation in the medium range.

[0037] (3) When the no-load tap changer 2 is in the third position, the back EMF generated by the coarse adjustment coil and the fine adjustment coil of the main transformer connected in series is applied to the high-voltage coil of the auxiliary transformer. At this time, the secondary output voltage of the auxiliary transformer is caused by the back EMF, and the transformer output voltage is maintained at the lowest level. By using different connection methods of the coarse adjustment coil, the overall voltage regulation level of the transformer is effectively three times that of the voltage regulation level of the on-load tap changer 1, which greatly improves the voltage regulation accuracy and flexibility.

[0038] The above description is only a preferred embodiment of the present utility model and is not intended to limit the present utility model. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present utility model should be included within the protection scope of the present utility model.

Claims

1. A voltage regulating transformer lead structure for an electric furnace system, characterized in that, The main transformer is used to provide the first fixed voltage output. An auxiliary transformer, connected to the main transformer, is used to output an adjustable voltage; The voltage regulating component includes a coarse adjustment unit and a fine adjustment unit. The coarse adjustment unit achieves multi-state excitation through no-load switching, and the fine adjustment unit achieves multi-stage differential voltage regulation through on-load switching. The control unit coordinates the switching between the coarse adjustment unit and the fine adjustment unit to achieve output voltage regulation over a wide range. The main transformer provides constant magnetic flux excitation, and the voltage regulating component forms a combined excitation path with the main transformer to adjust the input voltage of the auxiliary transformer, thereby realizing the expansion of the voltage regulation stage.

2. The voltage regulating transformer lead structure according to claim 1, characterized in that, The high-voltage winding of the main transformer is connected in a delta configuration to form a third harmonic current loop to accommodate unbalanced loads.

3. The voltage regulating transformer lead structure according to claim 1, characterized in that, The low-voltage windings of both the main transformer and the auxiliary transformer have an "8-shaped" structure to enhance mechanical strength and short-circuit withstand capability.

4. The voltage regulating transformer lead structure according to claim 1, characterized in that, The coarse adjustment unit includes three operating states: forward excitation, reverse excitation, and no excitation, which are used to achieve voltage boost, voltage reduction, and voltage neutralization, respectively.

5. The voltage regulating transformer lead structure according to claim 1, characterized in that, The fine-tuning unit uses a four-helix coil to improve the coil's manufacturability and adjustment accuracy.

6. The voltage regulating transformer lead structure according to claim 1, characterized in that, The control unit includes an off-load tap changer and an on-load tap changer, which respectively control the switching of the coarse adjustment unit and the fine adjustment unit.

7. The voltage regulating transformer lead structure according to claim 1, characterized in that, The voltage regulating component is configured to achieve 90 levels of differential voltage regulation.

Images