Transformers and transformer systems

Abstract

The present application relates to a transformer and a transformer system. The transformer includes an iron core, a winding, a through-the-window lead, and a compensation coil. The compensation coil surrounds an iron core side yoke arranged on the iron core. The terminals of the compensation coil and the through-the-window lead on the same side of the iron core have the same polarity, and the second end of the through-the-window lead is connected to a terminal of the same polarity in the compensation coil. The first end of the winding is arranged on the first side of the iron core, and the second end of the winding is led out to the second side of the iron core through the through-the-window lead, which saves the layout space of the transformer. The through-the-window lead and the compensation coil both induce an electromotive force. The terminals of the compensation coil and the through-the-window lead on the same side of the iron core have the same polarity, and the second end of the through-the-window lead is connected to a terminal of the same polarity in the compensation coil, so that the electromotive force induced by the through-the-window lead and the compensation coil can be offset, eliminating the zero-sequence current of the transformer, avoiding the problems of transformer no-load loss, high noise and vibration levels, local overheating, etc. caused by the zero-sequence current, and improving the reliability of the transformer.

Description

Technical Field

[0001] The present application relates to the technical field of electrical equipment, and in particular to a transformer and a transformer system. Background Art

[0002] Power transformers are the core equipment for energy transmission in power grids. Their safe, reliable, and economical operation has a crucial impact on the entire grid. In the transformer manufacturing industry, some transformers employ a method where the first and last leads of the windings are arranged on opposite sides of the core. This has the advantage of facilitating the placement of the first and last bushings on opposite sides, saving overall transformer layout space. However, this also results in the formation of lead wires through windows.

[0003] The magnetic flux in the side yokes of the window-through lead turns causes a zero-sequence component in the induced voltage on the high-voltage side. When the transformer is operating under load, the zero-sequence loop conducts, generating a large neutral-point current. This neutral-point current injects zero-sequence current into the ground grid, reducing the sensitivity of the zero-sequence protection and exacerbating the imbalance in the magnetic flux distribution between the left and right side yokes of the transformer core. This in turn leads to problems such as no-load losses, high noise and vibration levels, and localized overheating. Therefore, traditional transformers with opposite-side lead arrangements pose a risk of compromising the safe and reliable operation of the power grid. Summary of the Invention

[0004] Based on this, it is necessary to provide a transformer and a transformer system to address the above-mentioned defects of traditional transformers in which the first and last leads are arranged on different sides.

[0005] A transformer includes an iron core, a winding, a window lead and a compensation coil, wherein the winding is arranged around an iron core main column of the iron core, the first end and the second end of the winding are both arranged on the first side of the iron core, the second end of the winding is connected to the first end of the window lead, the window lead passes through the iron core window of the iron core, the second end of the window lead is arranged on the second side of the iron core opposite to the first side, the compensation coil is arranged around an iron core side yoke of the iron core, the terminals of the compensation coil and the window lead on the same side of the iron core have the same polarity, and the second end of the window lead is connected to the terminal of the compensation coil with the same polarity.

[0006] The above-mentioned transformer includes an iron core, a winding, a window lead and a compensation coil. The winding is wrapped around the iron core main column arranged on the iron core. The first end and the second end of the winding are both arranged on the first side of the iron core. The second end of the winding is connected to the first end of the window lead. The window lead passes through the iron core window of the iron core. The second end of the window lead is arranged on the second side of the iron core opposite to the first side. The compensation coil is wrapped around the iron core side yoke arranged on the iron core. The terminals of the compensation coil and the window lead on the same side of the iron core have the same polarity. The second end of the window lead is connected to the terminal with the same polarity in the compensation coil. The iron core and the winding can produce electromagnetic induction to realize voltage and current conversion. The first end of the winding is arranged on the first side of the iron core, and the second end of the winding is led out to the second side of the iron core through the window lead, which is convenient for arranging the first and end bushings on opposite sides, saving the layout space of the transformer. The window lead passes through the iron core window to induce an electromotive force, and the compensation coil is arranged on the iron core side yoke to induce an electromotive force. The terminals of the compensation coil and the window lead on the same side of the iron core have the same polarity. The second end of the window lead is connected to the terminal with the same polarity in the compensation coil, so that the electromotive force induced by the window lead and the compensation coil can be offset, eliminating the zero-sequence current of the transformer, avoiding the problems of transformer no-load loss, high noise and vibration levels, local overheating, etc. caused by zero-sequence current, and improving the reliability of the transformer.

[0007] In one embodiment, the core is a three-phase five-column core, the number of the windings is three, the windings are connected in a star-connected manner, and the common end of each winding is connected to the window lead.

[0008] In one embodiment, the transformer further includes a high-voltage bushing and a neutral point bushing, the number of the high-voltage bushings is three, the end of each winding away from the common end is respectively arranged in a different high-voltage bushing, and the second end of the window lead and the compensation coil are both arranged in the neutral point bushing.

[0009] In one embodiment, one end of the compensation coil not connected to the window lead is grounded.

[0010] In one embodiment, the transformer further includes a grounding copper busbar, and the end of the compensation coil not connected to the window lead is grounded through the grounding copper busbar.

[0011] In one embodiment, the compensation coil and the window lead are both wrapped by an insulating layer.

[0012] In one embodiment, the cross-sectional dimensions of the compensation coil match the cross-sectional dimensions of the window lead.

[0013] A transformer system comprises an oil tank and the above-mentioned transformer, wherein the transformer is arranged in the oil tank.

[0014] The above-mentioned transformer system includes an iron core, a winding, a window lead and a compensation coil. The winding is wrapped around the iron core main column arranged on the iron core. The first end and the second end of the winding are both arranged on the first side of the iron core. The second end of the winding is connected to the first end of the window lead. The window lead passes through the iron core window of the iron core. The second end of the window lead is arranged on the second side of the iron core opposite to the first side. The compensation coil is wrapped around the iron core side yoke arranged on the iron core. The terminals of the compensation coil and the window lead on the same side of the iron core have the same polarity. The second end of the window lead is connected to the terminal with the same polarity in the compensation coil. The iron core and the winding can produce electromagnetic induction to realize voltage and current conversion. The first end of the winding is arranged on the first side of the iron core, and the second end of the winding is led out to the second side of the iron core through the window lead, which is convenient for arranging the first and end bushings on opposite sides, saving the layout space of the transformer. The window lead passes through the iron core window to induce an electromotive force, and the compensation coil is arranged on the iron core side yoke to induce an electromotive force. The terminals of the compensation coil and the window lead on the same side of the iron core have the same polarity. The second end of the window lead is connected to the terminal with the same polarity in the compensation coil, so that the electromotive force induced by the window lead and the compensation coil can be offset, eliminating the zero-sequence current of the transformer, avoiding the problems of transformer no-load loss, high noise and vibration levels, local overheating, etc. caused by zero-sequence current, and improving the reliability of the transformer.

[0015] In one embodiment, an inspection window is provided at a position corresponding to the oil tank and the core side yoke, and the terminal of the compensation coil is led out to the outside of the oil tank through the inspection window.

[0016] In one embodiment, a connection terminal is provided at the inspection window, the connection terminal is insulated from the inspection window, and the compensation coil is connected to the connection terminal. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 is a structural diagram of a transformer in one embodiment;

[0018] Figure 2 is a structural diagram of a transformer in another embodiment;

[0019] Figure 3 is a structural diagram of a transformer system in one embodiment;

[0020] Figure 4 is a structural diagram of a transformer system in another embodiment;

[0021] Figure 5 A partial structural diagram of a transformer system in one embodiment;

[0022] Figure 6 is a wiring schematic diagram of a transformer in one embodiment;

[0023] Figure 7FIG1 is a circuit connection diagram of a transformer in an embodiment. DETAILED DESCRIPTION

[0024] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention will be described more comprehensively below with reference to the following embodiments and the accompanying drawings. It should be understood that the specific embodiments described herein are only intended to explain the present invention and are not intended to limit the present invention.

[0025] In one embodiment, see Figure 1 and Figure 2 , provides a transformer, including an iron core 2, a winding 3, a window lead 5 and a compensation coil 7, the winding 3 is wrapped around the iron core main column 4 arranged on the iron core 2, the first end and the second end of the winding 3 are both arranged on the first side of the iron core 2, the second end of the winding 3 is connected to the first end of the window lead 5, the window lead 5 passes through the iron core window of the iron core 2, the second end of the window lead 5 is arranged on the second side of the iron core 2 opposite to the first side, the compensation coil 7 is wrapped around the iron core side yoke 6 arranged on the iron core 2, the terminals of the compensation coil 7 and the window lead 5 on the same side of the iron core 2 have the same polarity, and the second end of the window lead 5 is connected to the terminal with the same polarity in the compensation coil 7. The iron core 2 and the winding 3 can produce electromagnetic induction to realize voltage and current conversion. The first end of the winding 3 is arranged on the first side of the iron core 2, and the second end of the winding 3 is led out to the second side of the iron core 2 through the window lead 5, which is convenient for arranging the first and end bushings on opposite sides, saving the layout space of the transformer. The window lead 5 passes through the iron core window to induce an electromotive force, and the compensation coil 7 is arranged on the iron core side yoke 6 to induce an electromotive force. The terminals of the compensation coil 7 and the window lead 5 on the same side of the iron core 2 have the same polarity. The second end of the window lead 5 is connected to the terminal with the same polarity in the compensation coil 7, so that the electromotive force induced by the window lead 5 and the compensation coil 7 can be offset, eliminating the zero-sequence current of the transformer, avoiding the problems of transformer no-load loss, high noise and vibration levels, local overheating, etc. caused by zero-sequence current, and improving the reliability of the transformer.

[0026] Specifically, the transformer includes an iron core 2 and a winding 3. The iron core 2 includes an iron core main column 4 and a side yoke 6. The winding 3 generally includes a primary winding and a secondary winding. The portion of the iron core 2 equipped with the primary and secondary windings is the iron core main column 4, and the other portion not equipped with the primary and secondary windings to form a closed magnetic flux path is the iron yoke. The upper and lower iron yokes of the iron core 2 are called upper and lower yokes, and the left and right iron yokes are called side yokes. The side yokes are arranged parallel to the iron core main column 4. The space defined by the iron core main column 4 and the iron yoke is the iron core window. The winding 3 is arranged around the iron core 2, specifically on the iron core main column 4. The first end of the winding 3 can be understood as the head end of the winding 3, and the second end of the winding 3 can be understood as the end end of the winding 3. The head end of the winding 3 is located at the upper end of the winding 3, and the end end of the winding 3 is located at the lower end of the winding 3.

[0027] In this embodiment, to better illustrate the orientation of the core 2, a three-phase five-leg core is used as an example. The three-phase five-leg core includes three core legs 4, two side yokes, and upper and lower yokes. The side yokes are arranged parallel to the core legs 4. The side yokes are arranged on the left and right sides of the core 2, respectively. The upper yoke is arranged on the upper side of the core 2, and the lower yoke is arranged on the lower side of the core 2. The first side of the core 2 is the front side of the core 2, and the second side of the core 2 is the rear side of the core. The front and rear sides are arranged opposite each other. In the figure, the side of the core 2 closer to the paper is the front side, and the side farther from the paper is the rear side. The first and second ends of the winding 3 are both arranged on the front side of the core 2. The second end of the winding 3 is connected to the first end of the window lead 5. The window lead 5 passes through the core window of the core 2. The second end of the window lead 5 is arranged on the second side of the core 2 opposite the first side. The window lead 5 passes through the core window. The two ends of the window lead 5 are respectively located on the front and rear sides of the core 2. The window lead 5 leads the second end of the winding 3 to the rear side of the core 2, so that the first end and the second end of the winding 3 are respectively arranged on the front and rear sides of the core 2, realizing the arrangement of the two ends of the winding 3 on different sides, which can save the layout space of the transformer.

[0028] The compensation coil 7 is wrapped around the iron core side yoke 6 arranged on the iron core 2. The number of turns of the compensation coil 7 is not unique. In this embodiment, the number of turns of the compensation coil 7 is one turn, the first end and the second end of the compensation coil 7 are not connected, and the compensation coil 7 is an unclosed compensation coil 7. The first end and the second end of the compensation coil 7 are respectively located on the first side and the second side of the iron core 2. Taking the example where the first end of the compensation coil 7 is located on the first side of the iron core 2 and the second end of the compensation coil 7 is located on the second side of the iron core 2, the second end of the compensation coil 7 is specifically connected to the second end of the window lead 5. The terminals of the compensation coil 7 and the window lead 5 on the same side of the iron core 2 have the same polarity, and the second end of the window lead 5 is connected to the terminal with the same polarity in the compensation coil 7, that is, the first end of the compensation coil 7 has the same polarity as the first end of the window lead 5, and the second end of the compensation coil 7 has the same polarity as the second end of the window lead 5, so that the compensation coil 7 and the window lead 5 are connected in series in reverse, and the direction of the electromotive force generated by the compensation coil 7 is opposite to the direction of the zero-sequence voltage induced by the window lead 5, thereby canceling each other out and eliminating the zero-sequence current of the transformer caused by the window lead 5.

[0029] In one embodiment, see Figure 1 and Figure 2 The core 2 is a three-phase five-column core, the number of windings 3 is three, each winding 3 is connected in a star connection manner, and the common end of each winding 3 is connected to the window lead 5.

[0030] Specifically, a three-phase five-column core is a common core 2. The three-phase five-column core includes three main columns and two side yokes, as well as an upper yoke and a lower yoke. There are three windings 3, which are respectively arranged around different main columns of the core. Each winding 3 has a head end and an end end, the head end being the first end of the winding 3, and the end end being the second end of the winding 3. The three windings 3 are connected in a star-connected manner. For example, the connection terminal of the winding 3 close to the upper side of the core 2 is the head end, and the connection terminal close to the lower side of the core 2 is the end end. The head ends of the three windings 3 are each led out, and the ends of the three windings 3 are connected together to form a common connection end. The head ends and the common connection end of the three windings 3 are all located on the first side of the core 2. A conductor is set on the first side of the core 2. The ends of the three windings 3 are all conductively connected to the same conductor to connect the ends of the three windings 3 to form a common connection end of the three windings 3. The common end of each winding 3 is connected to the window lead 5, specifically to one terminal of the window lead 5. The window lead 5 is conductively connected to the common end of each winding 3, and can be conductively connected to any position of the wire as long as a person skilled in the art considers it achievable.

[0031] In one embodiment, see Figure 3 and Figure 4 The transformer also includes a high-voltage bushing 10 and a neutral-point bushing 11. There are three high-voltage bushings 10, with the end of each winding 3, remote from the common terminal, mounted on a different high-voltage bushing 10. The second end of the window lead 5 and the compensation coil 7 are both mounted on the neutral-point bushing 11. The high-voltage bushing 10 and the neutral-point bushing 11 are the transformer's primary insulation devices. The lead wires of the transformer windings 3 are routed through these bushings, insulating the lead wires from each other and from the transformer casing. They also secure the lead wires, improving the transformer's safety.

[0032] Specifically, the number of high-voltage bushings 10 corresponds to the number of windings 3. Taking the core 2 as a three-phase five-column core, the number of windings 3 is three, and each winding 3 is connected in a star-connected manner. The common end of each winding 3 is connected to the through-window lead 5. For example, the number of high-voltage bushings 10 is three, and the end of each winding 3 away from the common end is the first end of the winding 3. The first end of each winding 3 is respectively set on a high-voltage bushing 10, leading to the terminals of three windings 3. The common end of the three windings 3 is connected to the first end of the through-window lead 5, and the first end of the through-window lead 5 is located on the first side of the core 2. The through-window lead 5 passes through the core window and connects the first and second sides of the core 2. The second end of the through-window lead 5 is set on the second side of the core 2. The first and second sides of the core 2 are opposite, which is equivalent to the front and rear sides of the core 2. The common end of the three windings 3 is connected to the first end of the through-window lead 5. The through-window lead 5 can transfer the current in the winding 3 from the first end to the second end, reaching the second side of the core 2. The second end of the window lead 5 is equivalent to the neutral point of the transformer. The second end of the window lead 5 is connected to the compensation coil 7. The second end of the window lead 5 and the compensation coil 7 are both arranged in the neutral point bushing 11. The connection end of the window lead 5 and the compensation coil 7 is led out through the neutral point bushing 11. The terminal at the high-voltage bushing 10 is equivalent to the positive pole, and the terminal out of the neutral point bushing 11 is equivalent to the negative pole.

[0033] The types of high-voltage bushings 10 and neutral point bushings 11 are not limited. Different types of high-voltage bushings 10 and neutral point bushings 11 can be selected according to the voltage level of the transformer. For example, when the voltage range of a general transformer is 10-35 kV, an air-filled or oil-filled bushing can be used. When the voltage range of the transformer is above 110 kV, a capacitor bushing can be used. When the transformer is low voltage, a solid porcelain bushing can be used. The specific type can be adjusted according to actual needs.

[0034] In one embodiment, the end of the compensation coil 7 not connected to the window lead 5 is grounded. The second end of the window lead 5 is equivalent to the neutral point of the transformer. The second end of the window lead 5 is connected to the compensation coil 7. The second end of the window lead 5 and the compensation coil 7 are both connected to the neutral point bushing 11. The end of the compensation coil 7 connected to the window lead 5 is equivalent to the negative pole of the compensation coil 7. The end of the compensation coil 7 not connected to the window lead 5 is equivalent to the positive pole of the compensation coil 7. The positive pole of the compensation coil 7 is grounded, so that the direction of the electromotive force on the compensation coil 7 is opposite to the direction of the electromotive force on the window lead 5, and the direction of the electromotive force on the compensation coil 7 is equal to the magnitude of the electromotive force on the window lead 5, so that the electromotive force on the compensation coil 7 can offset the electromotive force on the window lead 5, thereby eliminating the zero-sequence current of the transformer.

[0035] In one embodiment, see Figure 3 and Figure 4The transformer also includes a grounding copper bus 16, and the end of the compensation coil 7 that is not connected to the window lead 5 is grounded through the grounding copper bus 16. The grounding copper bus 16 provides a grounding conductor and connects to various metal parts in the system to establish an equipotential system. The voltage of this equipotential system is almost zero, which can protect the safety of personnel and equipment in the event of overcurrent or fault. The end of the compensation coil 7 that is not connected to the window lead 5 is grounded through the grounding copper bus 16. The voltage on the grounding copper bus 16 is approximately zero, which can prevent the occurrence of ground potential rebound accidents. The type of grounding copper bus 16 is not unique and can be selected according to actual needs. In an extensible way, the grounding copper bus 16 can also be used to connect other devices, which can be determined according to actual needs, as long as those skilled in the art believe that it can be achieved.

[0036] In one embodiment, the compensation coil 7 and the window lead 5 are both wrapped in an insulating layer. The compensation coil 7 and the window lead 5 are both conductive wires that can transmit current and generate electromotive force. The compensation coil 7 includes an inner conductor and an outer insulating layer. The inner conductor is used to transmit current, and the outer insulating layer wraps around the inner conductor, insulating the inner conductor and ensuring the electrical safety of the compensation coil 7. The structure of the window lead 5 is similar to that of the compensation coil 7. The window lead 5 includes an inner conductor and an outer insulating layer. The inner conductor is used to transmit current, and the outer insulating layer wraps around the inner conductor, thereby ensuring the electrical safety of the window lead 5. It will be understood that in this embodiment, the connection between the compensation coil 7 and the window lead 5 is a conductive connection, that is, the inner conductor of the compensation coil 7 is connected to the inner conductor of the window lead 5 to form a current path. The type of insulation layer is not limited to one type and can be insulating paper, that is, insulating paper is wrapped around the outer surface of the inner conductors of the compensation coil 7 and the window lead 5. The thickness of the insulating paper can be adjusted according to actual needs. In an expandable manner, a certain thickness of insulating paper can also be wrapped around the outside of the transformer coil to ensure the electrical safety of the transformer.

[0037] In one embodiment, the cross-sectional dimensions of the compensation coil 7 match the cross-sectional dimensions of the window lead 5. When the cross-sectional dimensions of the compensation coil 7 match the cross-sectional dimensions of the window lead 5, the compensation coil 7 and the window lead 5 can be better connected, thereby improving the operating performance of the transformer.

[0038] Specifically, the cross-sectional dimensions of the compensation coil 7 are generally referred to as the wire gauge of the compensation coil 7, and the cross-sectional dimensions of the window lead 5 are generally referred to as the wire gauge of the window lead 5. The wire gauge of the compensation coil 7 matches the wire gauge of the window lead 5, which generally means that the wire gauge of the compensation coil 7 is equal to the wire gauge of the window lead 5. When the compensation coil 7 and the window lead 5 both include an internal conductor and an external insulation layer, the cross-sectional dimensions of the internal conductor of the compensation coil 7 are equal to the cross-sectional dimensions of the internal conductor of the window lead 5, which is conducive to welding the window lead 5 to the compensation coil 7 lead, the cross-sectional dimensions of the external insulation layer of the compensation coil 7 are equal to the cross-sectional dimensions of the external insulation layer of the window lead 5, and the insulation level of the compensation coil 7 is consistent with the insulation level of the window lead 5. It can be understood that in other embodiments, the cross-sectional dimensions of the compensation coil 7 and the cross-sectional dimensions of the window lead 5 can also be approximately equal, as long as those skilled in the art consider it achievable.

[0039] In order to better understand the above embodiment, the following is a detailed explanation in conjunction with a specific embodiment. In one embodiment, see Figure 3 and Figure 4 The transformer is a three-phase, five-leg iron core. A compensating coil 7 is added to the transformer's core side yoke 6, connected in antiphase series with the through-window lead 5. The compensating coil 7 is mounted on the core side yoke 6, and its wire gauge and insulation are consistent with those of the neutral lead. The negative pole of the compensating coil 7 is connected to the neutral bushing 11, and the positive pole of the compensating coil 7 is grounded. The positive and negative poles of the compensating coil 7 are connected through terminals on the inspection window 17 of the transformer oil tank 12. The terminals are insulated from the inspection window 17. The zero-sequence current in the transformer is eliminated by the principle that the zero-sequence voltage induced by the compensating coil 7 and the through-window lead 5 cancel each other out.

[0040] When the compensation coil 7 is not provided, the yoke magnetic flux of the 5 turns of the window lead induces a zero-sequence voltage e0, and the neutral point injects a zero-sequence current into the ground grid. The zero-sequence current calculation formula is as follows:

[0041]

[0042] In formula (1), i0 is the zero-sequence current, e0 is the zero-sequence voltage, and Z S 0 is the system zero-sequence impedance, Z T 0 is the transformer zero-sequence impedance. After adding the compensation coil 7, see Figure 6 and Figure 7 The zero-sequence voltages induced by the compensation coil 7 and the window lead 5 cancel each other out. Please refer to formula (2). The zero-sequence current is zero, eliminating the transformer zero-sequence current.

[0043]

[0044] The above-mentioned transformer includes an iron core 2, a winding 3, a window lead 5 and a compensation coil 7. The winding 3 is wrapped around the iron core main column 4 arranged on the iron core 2. The first end and the second end of the winding 3 are both arranged on the first side of the iron core 2. The second end of the winding 3 is connected to the first end of the window lead 5. The window lead 5 passes through the iron core window of the iron core 2. The second end of the window lead 5 is arranged on the second side of the iron core 2 opposite to the first side. The compensation coil 7 is wrapped around the iron core side yoke 6 arranged on the iron core 2. The terminals of the compensation coil 7 and the window lead 5 on the same side of the iron core 2 have the same polarity. The second end of the window lead 5 is connected to the terminal with the same polarity in the compensation coil 7. The iron core 2 and the winding 3 can produce electromagnetic induction to realize voltage and current conversion. The first end of the winding 3 is arranged on the first side of the iron core 2, and the second end of the winding 3 is led out to the second side of the iron core 2 through the window lead 5, which is convenient for arranging the first and end bushings on opposite sides, saving the layout space of the transformer. The window lead 5 passes through the iron core window to induce an electromotive force, and the compensation coil 7 is arranged on the iron core side yoke 6 to induce an electromotive force. The terminals of the compensation coil 7 and the window lead 5 on the same side of the iron core 2 have the same polarity. The second end of the window lead 5 is connected to the terminal with the same polarity in the compensation coil 7, so that the electromotive force induced by the window lead 5 and the compensation coil 7 can be offset, eliminating the zero-sequence current of the transformer, avoiding the problems of transformer no-load loss, high noise and vibration levels, local overheating, etc. caused by zero-sequence current, and improving the reliability of the transformer.

[0045] In one embodiment, a transformer system is provided, see Figure 3 and Figure 4 , including an oil tank 12 and the above-mentioned transformer, the transformer is arranged in the oil tank 12. The oil tank 12 is the outer shell of the transformer, which contains the iron core 2 and the winding 3 and is filled with transformer oil, so that the iron core 2 and the winding 3 are immersed in the oil, and the transformer oil plays the role of insulation and heat dissipation. Furthermore, depending on the structure of the transformer, it can be adjusted according to actual needs whether all the components of the transformer are arranged inside the oil tank 12. For example, when the transformer includes the iron core 2, the winding 3, the window lead 5 and the compensation coil 7, the iron core 2 and the winding 3 are all arranged in the oil tank 12, and the window lead 5 and the compensation coil 7 are mostly also arranged in the oil tank 12. The lead terminal can be led out of the oil tank 12 for easy connection with other components. When the transformer also includes a high-voltage bushing 10, a neutral point bushing 11 and a grounding copper busbar 16, the high-voltage bushing 10, the neutral point bushing 11 and the grounding copper busbar 16 are all arranged outside the oil tank 12. It is understandable that in other embodiments, if the transformer further includes other components, the components included in the transformer can be arranged inside or outside the oil tank 12, which can be selected according to actual needs, as long as those skilled in the art consider it feasible.

[0046] In one embodiment, see Figure 3 and Figure 4An inspection window 17 is provided at the position corresponding to the oil tank 12 and the core side yoke 6, and the terminal of the compensation coil 7 is led out to the outside of the oil tank 12 through the inspection window 17. The inspection window 17 allows the staff to check the working status of the components inside the oil tank 12 and facilitate maintenance.

[0047] Specifically, there is no single method for providing inspection window 17. In this embodiment, a cover plate is provided at the position corresponding to the core side yoke 6 on the fuel tank 12, which is removably connected to the wall of the fuel tank 12. When inspection window 17 is needed, the cover plate can be removed, and the window formed by the removal of the cover plate serves as inspection window 17. When inspection window 17 is no longer needed, the cover plate can be installed on the wall of the fuel tank 12, thus making the fuel tank 12 more complete. The terminals of the compensation coil 7 are connected to the outside of the fuel tank 12 through the inspection window 17, facilitating connection of the terminals of the compensation coil 7 to other components.

[0048] In one embodiment, see Figure 5 The inspection window 17 is provided with a terminal block 15, which is insulated from the inspection window 17. The terminals of the compensation coil 7 are connected to the terminal block. The terminal block at the inspection window 17 can be led out to the outside of the oil tank 12 to facilitate the connection of the terminals of the compensation coil 7 with other devices. The terminal block is insulated from the inspection window 17, thereby ensuring its electrical safety. Furthermore, the transformer system may also include other devices, for example, see Figure 3 and Figure 4 The transformer system includes high-voltage lead, iron core 2, high-voltage winding 3, iron core main column 4, neutral point lead (window lead) 5, side yoke 6, compensation coil 7, compensation coil negative pole 8, compensation coil positive pole 9, high-voltage bushing 10, neutral point bushing 11, oil tank 12, external connection copper bus 13, terminal insulation 14, terminal 15, grounding copper bus 16, inspection window 17, base 18, insulator 19, among which the base plays a fixing role and the insulator plays an insulating role, thereby ensuring its electrical safety.

[0049] The above-mentioned transformer system includes an iron core 2, a winding 3, a window lead 5 and a compensation coil 7. The winding 3 is wrapped around the iron core main column 4 arranged on the iron core 2. The first end and the second end of the winding 3 are both arranged on the first side of the iron core 2. The second end of the winding 3 is connected to the first end of the window lead 5. The window lead 5 passes through the iron core window of the iron core 2. The second end of the window lead 5 is arranged on the second side of the iron core 2 opposite to the first side. The compensation coil 7 is wrapped around the iron core side yoke 6 arranged on the iron core 2. The terminals of the compensation coil 7 and the window lead 5 on the same side of the iron core 2 have the same polarity. The second end of the window lead 5 is connected to the terminal with the same polarity in the compensation coil 7. The iron core 2 and the winding 3 can produce electromagnetic induction to realize voltage and current conversion. The first end of the winding 3 is arranged on the first side of the iron core 2, and the second end of the winding 3 is led out to the second side of the iron core 2 through the window lead 5, which is convenient for arranging the first and end bushings on opposite sides, saving the layout space of the transformer. The window lead 5 passes through the iron core window to induce an electromotive force, and the compensation coil 7 is arranged on the iron core side yoke 6 to induce an electromotive force. The terminals of the compensation coil 7 and the window lead 5 on the same side of the iron core 2 have the same polarity. The second end of the window lead 5 is connected to the terminal with the same polarity in the compensation coil 7, so that the electromotive force induced by the window lead 5 and the compensation coil 7 can be offset, eliminating the zero-sequence current of the transformer, avoiding the problems of transformer no-load loss, high noise and vibration levels, local overheating, etc. caused by zero-sequence current, and improving the reliability of the transformer.

[0050] The technical features of the above-mentioned embodiments can be combined arbitrarily. In order to make the description concise, not all possible combinations of the technical features in the above-mentioned embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0051] The above-described embodiments merely illustrate several implementations of the present invention, and while their descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent. It should be noted that a person skilled in the art would be able to make numerous variations and improvements without departing from the spirit of the present invention, all of which fall within the scope of protection of the present invention. Therefore, the scope of protection of the patent for this invention shall be determined by the appended claims.

Claims

1. A transformer, characterized in that: The present invention comprises an iron core, a winding, a window lead and a compensation coil, wherein the winding is arranged around an iron core main column of the iron core, the first end and the second end of the winding are both arranged on the first side of the iron core, the second end of the winding is connected to the first end of the window lead, the window lead passes through the iron core window of the iron core, the second end of the window lead is arranged on the second side of the iron core opposite to the first side, the compensation coil is arranged around an iron core side yoke of the iron core, the compensation coil is an unclosed compensation coil, the first end and the second end of the compensation coil are respectively located on the first side and the second side of the iron core, the terminals of the compensation coil and the window lead on the same side of the iron core have the same polarity, the second end of the window lead is connected to the terminal with the same polarity in the compensation coil, and the compensation coil and the window lead are connected in series in reverse order; The core is a three-phase five-column core, the number of the windings is three, each winding is connected in a star connection, and the common end of each winding is connected to the window lead; It also includes a high-voltage bushing and a neutral point bushing. The number of the high-voltage bushings is three. The end of each winding away from the common end is respectively arranged on a different high-voltage bushing. The second end of the window lead and the compensation coil are both arranged on the neutral point bushing. The terminal at the high-voltage bushing is equivalent to the positive pole, and the terminal at the neutral point bushing is equivalent to the negative pole.

2. The transformer according to claim 1, characterized in that One end of the compensation coil that is not connected to the window lead is grounded.

3. The transformer according to claim 2, characterized in that It also includes a grounding copper busbar, through which the end of the compensation coil not connected to the window lead is grounded.

4. The transformer according to claim 1, characterized in that The compensation coil and the window lead are both wrapped by an insulating layer.

5. The transformer according to claim 1, characterized in that The cross-sectional dimensions of the compensation coil match the cross-sectional dimensions of the window lead.

6. A transformer system, characterized in that: The utility model comprises an oil tank and a transformer according to any one of claims 1 to 5, wherein the transformer is arranged in the oil tank.

7. The transformer system according to claim 6, characterized in that Inspection windows are provided at positions corresponding to the oil tank and the core side yoke, and the terminals of the compensation coil are led out to the outside of the oil tank through the inspection windows.

8. The transformer system according to claim 7, characterized in that: The inspection window is provided with a wiring terminal, the wiring terminal is insulated from the inspection window, and the compensation coil is connected to the wiring terminal.

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