Gas-insulated transformer, gas-insulated transformer system, and voltage estimation method

Abstract

The present invention realizes a gas-insulated transformer, a gas-insulated transformer system, and a voltage estimation method capable of estimating a primary voltage with high precision. The transformer includes: a core; a secondary winding (12) wound around the core; a primary winding (11) wound coaxially around the outer periphery of the secondary winding; a high-voltage shield (13) covering the outer periphery of the primary winding; a low-voltage shield (14) facing the high-voltage shield; a grounding terminal (23); and a capacitor (21) having one end connected to the low-voltage shield and the other end connected to the grounding terminal.

Description

Technical Field

[0001] The present invention relates to a gas-insulated transformer, a gas-insulated transformer system, and a method for estimating the voltage of a primary winding in the gas-insulated transformer and the gas-insulated transformer system. Background Art

[0002] There is known a gas-insulated transformer that is connected to a bus or a line in a substation or the like to change the voltage and supply it. An example of such a gas-insulated transformer is disclosed in Patent Document 1.

[0003] Prior Art Documents

[0004] Patent Documents

[0005] Patent Document 1: Japanese Unexamined Patent Publication "JP-A-2004-22557" Summary of the Invention

[0006] Problems to be Solved by the Invention

[0007] In a power system using the gas-insulated transformer, it is desired to detect the primary voltage supplied to the gas-insulated transformer. And when it is desired to be able to detect the primary voltage, it is ideal to avoid unnecessarily complicating and enlarging the structure of the machine. Moreover, it is ideal to be able to detect the primary voltage without causing an error due to a change in the load connected to the secondary side.

[0008] An object of an embodiment of the present invention is to realize a gas-insulated transformer or the like that can detect the primary voltage without unnecessarily complicating and enlarging the structure of the machine or causing an error due to a change in the load connected to the secondary side.

[0009] Technical Means for Solving the Problems

[0010] To solve the above problems, a gas-insulated transformer according to an embodiment of the present invention includes: a core; a secondary winding wound around the core; a primary winding wound coaxially around the outer periphery of the secondary winding; a high-voltage shield covering the outer periphery of the primary winding; a low-voltage shield facing the high-voltage shield; a grounding terminal; and a circuit element having one end connected to the low-voltage shield and the other end connected to the grounding terminal.

[0011] Moreover, a voltage estimation method according to an embodiment of the present invention is a voltage estimation method for estimating a primary voltage of a gas-insulated transformer, the gas-insulated transformer including: a core; a secondary winding wound around the core; a primary winding coaxially wound around an outer periphery of the secondary winding; a high-voltage shield covering an outer periphery of the primary winding; a low-voltage shield facing the high-voltage shield; a grounding terminal; and a circuit element having one end connected to the low-voltage shield and the other end connected to the grounding terminal, the voltage estimation method including: a step of detecting a voltage applied to the circuit element; and a step of estimating the primary voltage based on an electrostatic capacitance between the high-voltage shield and the low-voltage shield, a circuit constant of the circuit element, and the voltage applied to the circuit element.

[0012] Effects of the Invention

[0013] With a gas-insulated transformer or the like according to an embodiment of the present invention, the structure of the machine is not unnecessarily complicated or enlarged, and errors are not caused by changes in a load connected to a secondary side, and a voltage applied to a primary winding can be detected. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 FIG. is a diagram showing a structure of a gas-insulated transformer system according to Embodiment 1.

[0015] Figure 2 FIG. is a diagram showing Figure 1 a cross section taken along line X-X in

[0016] Figure 3 FIG. is a diagram showing Figure 2 a cross section taken along line Y-Y in

[0017] Figure 4 FIG. is a circuit diagram showing a circuit structure of a transformer according to Embodiment 1.

[0018] Figure 5 FIG. is a block diagram showing a structure of a main part of a primary voltage estimation device.

[0019] Figure 6 FIG. is a flowchart showing a process of the primary voltage estimation device estimating the primary voltage.

[0020] DESCRIPTION OF SYMBOLS

[0021] 1: Transformer

[0022] 9: Primary voltage estimation device

[0023] 10: Core

[0024] 11: Primary winding

[0025] 11a: Terminal

[0026] 11b: Connecting conductor

[0027] 12: Secondary winding

[0028] 12a: Lead wire

[0029] 13: High-voltage shielding cover

[0030] 14: Low-voltage shielding cover

[0031] 15: Virtual capacitor

[0032] 16: Lead wire connection part

[0033] 21: Capacitor (circuit element)

[0034] 22: Voltage detection terminal

[0035] 23: Grounding terminal

[0036] 24: Voltage detector

[0037] 31: Container

[0038] 32: Terminal box

[0039] 33: Bushing

[0040] 34: Pull-out member

[0041] 91: Circuit element voltage detection part

[0042] 92: Primary voltage estimation part

[0043] 100: Gas-insulated transformer system

[0044] C1, C2: Capacitance

[0045] U, u, V, v: Terminals

[0046] V1: Primary voltage

[0047] Vm: Voltage Detailed implementation mode

[0048] 〔Embodiment 1〕

[0049] Hereinafter, an embodiment of the present invention will be described in detail.

[0050] (Structure of gas-insulated transformer system 100)

[0051] Figure 1 is a diagram showing the structure of the gas-insulated transformer system 100 of Embodiment 1. As Figure 1As shown, the gas-insulated transformer system 100 includes a transformer 1 (gas-insulated transformer) and a primary voltage estimation device 9. Figure 2 and Figure 3 represents a cross-section at a specific cut position of the main components disposed inside the container 31 of the transformer 1.

[0052] Figure 2 represents Figure 1 the cross-section on the X-X line in Figure 3 represents Figure 2 the cross-section on the Y-Y line in. Such a gas-insulated transformer system 100 is provided, for example, for the purpose of converting high-voltage electricity and supplying it in the form of in-station electricity, and is installed in a power plant or a substation. Moreover, Figure 4 is a circuit diagram showing the schematic structure of the circuit of the transformer 1.

[0053] (Structure of Transformer 1)

[0054] The transformer 1 is a single-phase grounded transformer. The transformer 1 includes a core 10, a primary winding 11, a secondary winding 12, a high-voltage shield 13, a low-voltage shield 14, a lead connection part 16, a capacitor 21 (circuit element), a voltage detection terminal 22, a ground terminal 23, a voltage detector 24, a container 31, and a terminal box 32.

[0055] The core 10 is a core material around which the primary winding 11 and the secondary winding 12 are wound. The core 10 is formed of a material containing a magnetic body. In Embodiment 1, the core 10 is formed of iron. The secondary winding 12 is wound around the core 10. The primary winding 11 is wound around the outer periphery of the secondary winding 12 coaxially with the secondary winding 12.

[0056] In the transformer 1, by inputting a primary voltage V1 to the input terminals of the primary winding 11 ( Figure 4 terminals U and V in the circuit diagram of Figure 4 ), a secondary voltage corresponding to the turns ratio of the primary winding 11 and the secondary winding 12 is output from the output terminals of the secondary winding 12 (

[0057] terminals u and v in the circuit diagram of

[0058] The low-voltage shielding cover 14 is arranged at the said position to reduce the influence of components such as the edge of the core 10 and the fixing members of the core 10 on the electric field formed by the primary winding 11. Moreover, the axial direction of the secondary winding 12 is longer than that of the primary winding 11. Therefore, in the transformer 1, the secondary winding 12 also functions as a shielding cover to reduce the influence of components such as the edge of the core 10 and the fixing members of the core 10 on the electric field formed by the primary winding 11.

[0059] Both the high-voltage shielding cover 13 and the low-voltage shielding cover 14 are formed of a conductor. Moreover, there is no case where the high-voltage shielding cover 13 and the low-voltage shielding cover 14 are connected to each other through a conductor. Since the low-voltage shielding cover 14 is arranged at a position facing the high-voltage shielding cover 13, there is an electrostatic capacitance C1 between the high-voltage shielding cover 13 and the low-voltage shielding cover 14 in the transformer 1. In the following description, it is regarded that the high-voltage shielding cover 13 and the low-voltage shielding cover 14 are connected to each other via a virtual capacitor 15 having the said electrostatic capacitance C1.

[0060] The lead connection part 16 is a member for connecting the lead 12a of the secondary winding 12. As Figure 1 shown, in the transformer 1, the low-voltage shielding cover 14 is arranged between the high-voltage shielding cover 13 and the lead connection part 16. Therefore, the low-voltage shielding cover 14 also reduces the influence of the lead connection part 16 on the electric field formed by the primary winding 11.

[0061] The capacitor 21 is a circuit element with one end connected to the low-voltage shielding cover 14 and the other end connected to the ground terminal 23. The ground terminal 23 is a terminal for grounding the capacitor 21. Therefore, the potential of the low-voltage shielding cover 14 is in a state of floating from the ground potential by the amount of the voltage applied to the capacitor 21.

[0062] The voltage detection terminal 22 is a terminal for detecting the voltage Vm applied to the capacitor 21. The voltage detection terminal 22 is connected to one end of the capacitor 21 connected to the low-voltage shielding cover 14. Therefore, in the transformer 1, the voltage Vm applied to the capacitor 21 can be detected by the voltage detection terminal 22 and the ground terminal 23.

[0063] The voltage detector 24 detects the voltage Vm applied to the capacitor 21. The voltage detector 24 is connected between the voltage detection terminal 22 and the ground terminal 23. In other words, the voltage detector 24 is connected between one end of the capacitor 21 connected to the low-voltage shielding cover 14 and the ground terminal 23. Thus, the voltage detector 24 can detect the voltage Vm applied to the capacitor 21. As the voltage detector 24, a known detector can be used. In the first embodiment, since the transformer 1 includes a voltage detector, there is no need to connect a voltage detector separately.

[0064] The container 31 houses the core 10, the primary winding 11, the secondary winding 12, the high-voltage shield 13, and the low-voltage shield 14 in a sealed state. For example, SF6 gas at 0.55 MPa is filled in the container 31 as the insulating gas. However, the pressure and type of the gas filled in the container 31 are not limited to this.

[0065] The non-grounded terminal 11a for inputting the primary voltage V1 to the primary winding 11 is provided at a position pulled out from the container 31 via a bushing 33. Moreover, an insulating spacer including a body formed of an insulating resin and a buried conductor provided through the body can be used instead of the bushing 33. The terminal 11a is connected to the primary winding 11 through a connection conductor 11b.

[0066] The terminal box 32 also houses other input / output terminals for the primary winding 11 and the secondary winding 12. In the terminal box 32, an input terminal on the opposite side of the above terminal 11a of the primary winding 11 ( Figure 4 terminal V in the circuit diagram), and output terminals ( Figure 4 terminals u and v in the circuit diagram) connected to the respective leads 12a of the secondary winding 12 through the lead connection portion 16 are housed.

[0067] To avoid complexity, Figure 1 these terminals and the leads connecting the terminals to the primary winding 11 and the secondary winding 12 are not shown. Different from the container 31, it is not necessary to fill the terminal box 32 with insulating gas.

[0068] Moreover, a pulling member 34 is provided in the container 31 for pulling out the lead connected to the low-voltage shield 14 from inside the container 31 to inside the terminal box 32. The capacitor 21 is disposed inside the terminal box 32. That is, the capacitor 21 is disposed outside the container 31. Therefore, in the case of an abnormality in the capacitor 21, the abnormality can be dealt with without opening the container 31 filled with insulating gas.

[0069] (Detection of primary voltage)

[0070] As Figure 4 shown, in the transformer 1, a voltage dividing circuit of the primary voltage V1 induced by the non-grounded high-voltage shield 13 is formed by a virtual capacitor 15 having a capacitance C1 and a capacitor 21 having a capacitance C2.

[0071] The value of the capacitance C1 is a known value uniquely determined according to the size and shape of the high-voltage shield 13 and the low-voltage shield 14, and the type and pressure of the gas filled in the container 31. Moreover, of course, the value of the capacitance C2 is known.

[0072] As a result, the voltage Vm applied to the capacitor 21 detected by the voltage detector 24 becomes a value obtained by dividing the primary voltage V1 induced by the high-voltage shield 13 according to the impedance ratio of the virtual capacitor 15 and the capacitor 21. That is, taking ω as the angular frequency of the primary voltage V1, the relational expression Vm = V1 × {1 / (j×ω×C2)} / {1 / (j×ω×C1) + 1 / (j×ω×C2)} holds. From this, the primary voltage V1 can be calculated by the relational expression V1 = Vm × (C1 + C2) / C1. Therefore, in the transformer 1, by measuring the voltage Vm applied to the capacitor 21 using the voltage detection terminal 22, the primary voltage V1 applied to the primary winding 11 can be estimated.

[0073] Figure 5 is a block diagram showing the structure of the main part of the primary voltage estimation device 9. The primary voltage estimation device 9 estimates the magnitude of the primary voltage V1 based on the voltage detected by the voltage detector 24. As Figure 5 shown, the primary voltage estimation device 9 includes a circuit element voltage detection unit 91 and a primary voltage estimation unit 92.

[0074] The circuit element voltage detection unit 91 detects the voltage Vm applied to the capacitor 21 through the voltage detector 24. The circuit element voltage detection unit 91 outputs a signal representing the voltage Vm to the primary voltage estimation unit 92.

[0075] The primary voltage estimation unit 92 calculates the primary voltage V1 through the above relational expression based on the capacitance C1 of the virtual capacitor 15, the capacitance (circuit constant) C2 of the capacitor 21, and the voltage Vm applied to the capacitor 21. Therefore, in the gas-insulated transformer system 100, the primary voltage V1 can be estimated by the primary voltage estimation device 9.

[0076] Figure 6 is a flowchart showing the process of the primary voltage estimation device 9 estimating the primary voltage V1. In the process of estimating the primary voltage V1, first, the circuit element voltage detection unit 91 detects the voltage Vm applied to the capacitor 21 (S1). Next, the primary voltage estimation unit 92 estimates the primary voltage V1 (S2).

[0077] As described above, in the transformer 1 of the first embodiment, by measuring the voltage Vm applied to the capacitor 21, the primary voltage V1 can be estimated. The voltage Vm applied to the capacitor 21 is constant and independent of the load connected to the secondary winding 12.

[0078] In a transformer, it is studied to wind a voltage detection winding around the core independently of the output secondary winding, and detect the primary voltage based on the voltage applied to the voltage detection winding. However, the voltage applied to the voltage detection winding also varies according to the load current flowing in the secondary winding.

[0079] For example, in a method where the structure is the same as that of transformer 1 but a winding for voltage detection is provided to detect the primary voltage, it has been found that under actual usage conditions, the load will cause an error of approximately 5% to 10%.

[0080] However, the transformer 1 of the present embodiment does not generate an error due to load variation because the primary voltage V1 is detected by the above method. Therefore, in transformer 1, the primary voltage V1 can be estimated with high precision. Moreover, there is no need to include a winding for voltage measurement, and the structure of the transformer can be simplified.

[0081] Alternatively, in a transformer, a mutual inductor for measuring the primary voltage V1 is also studied to be integrally provided in parallel on the primary side of transformer 1. However, the structure of such a transformer is complex and the device is large-sized.

[0082] Moreover, of course, even if a mutual inductor for measuring the primary voltage V1 is additionally provided in parallel on the primary side of transformer 1 in addition to the transformer, the gas-insulated transformer system 100 will also be large-sized and costly. On the other hand, according to the present embodiment, as the gas-insulated transformer system 100, the primary voltage V1 can be detected by a compact and low-cost structure.

[0083] In addition, the gas-insulated transformer system 100 may include an output device that outputs to the user one or more of the voltage Vm detected by the circuit element voltage detection unit 91 and the primary voltage V1 estimated by the primary voltage estimation unit 92. As an example of the output device, a display device that displays an image can be cited.

[0084] Moreover, the gas-insulated transformer system 100 may include an alarm device that determines whether the primary voltage V1 estimated by the primary voltage estimation unit 92 is within a specified range, and issues an alarm to the user when it is not within the specified range. The alarm is formed by, for example, an image, light, or sound.

[0085] 〔Embodiment 2〕

[0086] The following describes other embodiments of the present invention. In addition, for convenience of explanation, components having the same functions as those described in the above embodiment are denoted by the same reference numerals, and their descriptions will not be repeated.

[0087] As described above, the transformer 1 of Embodiment 1 includes the capacitor 21 as a circuit element for detecting the voltage Vm. However, the transformer of the present invention may also include other types of circuit elements such as a resistor or an inductor instead of the capacitor 21.

[0088] In this transformer, a voltage dividing circuit is also formed by the virtual capacitor 15 and the circuit element. Therefore, the primary voltage V1 can be estimated based on the voltage Vm applied to the circuit element. However, from the viewpoint of simplifying the calculation of the primary voltage V1 using the above relationship, in order to prevent the primary voltage V1 from being affected by the exciting current of the iron core determined by the applied voltage and the load current determined by the magnitude of the load connected to the secondary, it is preferable that the circuit element be a capacitor.

[0089] 〔Implementation Example Using Software〕

[0090] The control block of the primary voltage estimation device 9 (especially the circuit element voltage detection unit 91 and the primary voltage estimation unit 92) can be implemented by a logic circuit (hardware) formed in an integrated circuit (Integrated Circuit, IC) chip or the like, or can also be implemented by software.

[0091] In the latter case, the primary voltage estimation device 9 includes a computer that executes commands of a program that is software for implementing each function. The computer includes, for example, at least one processor (control device), and includes at least one computer-readable recording medium that stores the program.

[0092] And, in the computer, the program is read from the recording medium by the processor and executed, thereby achieving the object of the present invention. As the processor, for example, a Central Processing Unit (CPU) can be used. As the recording medium, in addition to "non-transitory tangible media" such as a Read Only Memory (ROM), etc., a magnetic tape, a magnetic disk, a card, a semiconductor memory, a programmable logic circuit, etc. can also be used.

[0093] Moreover, a Random Access Memory (RAM) etc. for expanding the program may also be included. Moreover, the program can be supplied to the computer via any transmission medium (communication network or broadcast wave, etc.) capable of transmitting the program. In addition, an embodiment of the present invention can also be implemented by an embodiment of using an electronic transmission to implement a data signal in which the program is embedded in a carrier wave.

[0094] 〔Summary〕

[0095] The gas-insulated transformer according to Embodiment 1 of the present invention includes: a core; a secondary winding wound around the core; a primary winding wound coaxially around the outer periphery of the secondary winding; a high-voltage shield covering the outer periphery of the primary winding; a low-voltage shield facing the high-voltage shield; a ground terminal; and a circuit element having one end connected to the low-voltage shield and the other end connected to the ground terminal.

[0096] According to the above structure, a voltage dividing circuit is formed by a virtual capacitor formed by a high-voltage shield and a low-voltage shield, and a circuit element connected to the low-voltage shield and the ground terminal. By detecting the voltage applied to the circuit element, the primary voltage induced by the high-voltage shield can be calculated. Therefore, there is no situation of making the gas-insulated transformer large-sized, and it is not affected by the load current, and a function of estimating the primary voltage can be added.

[0097] Moreover, in the gas-insulated transformer of Embodiment 2 of the present invention, in Embodiment 1, the axial direction of the secondary winding is longer than the axial direction of the primary winding.

[0098] According to the above structure, the secondary winding functions as a shield to reduce the influence of components such as the core edge and fixing members on the electric field formed by the primary winding.

[0099] Moreover, in the gas-insulated transformer of Embodiment 3 of the present invention, in Embodiment 2, the low-voltage shield is disposed between the high-voltage shield and the region of the core that does not cover the secondary winding.

[0100] According to the above structure, through the low-voltage shield, the influence of components such as the core edge and fixing members on the electric field formed by the primary winding can be reduced.

[0101] Moreover, in the gas-insulated transformer of Embodiment 4 of the present invention, in Embodiment 2 or Embodiment 3, it further includes a lead connection part that connects the leads of the secondary winding, and the low-voltage shield is disposed between the high-voltage shield and the lead connection part.

[0102] According to the above structure, through the low-voltage shield, the influence of the lead connection part on the electric field formed by the primary winding 11 can also be reduced.

[0103] Moreover, in the gas-insulated transformer of Embodiment 5 of the present invention, in any one of Embodiments 1 to 4, it further includes a voltage detector that is connected between one end of the circuit element and the ground terminal.

[0104] According to the above structure, there is no need to separately connect a voltage detector for detecting the voltage applied to the circuit element.

[0105] Moreover, the gas-insulated transformer system of Embodiment 6 of the present invention includes: the gas-insulated transformer of Embodiment 5; and a primary voltage estimation device that estimates the magnitude of the primary voltage based on the voltage detected by the voltage detector.

[0106] According to the above structure, the primary voltage can be estimated by the primary voltage estimation device.

[0107] Furthermore, the voltage estimation method of Embodiment 7 of the present invention is a voltage estimation method for estimating the primary voltage of a gas-insulated transformer, and the gas-insulated transformer includes: a core; a secondary winding wound around the core; a primary winding coaxially wound around the outer periphery of the secondary winding; a high-voltage shielding cover covering the outer periphery of the primary winding; a low-voltage shielding cover facing the high-voltage shielding cover; a grounding terminal; and a circuit element having one end connected to the low-voltage shielding cover and the other end connected to the grounding terminal. The voltage estimation method includes: a step of detecting the voltage applied to the circuit element; and a step of estimating the primary voltage based on the electrostatic capacitance between the high-voltage shielding cover and the low-voltage shielding cover, the circuit constant of the circuit element, and the voltage applied to the circuit element.

[0108] According to the above structure, in the voltage estimation method, first, the voltage of the circuit element connected to the low-voltage shielding cover and the grounding terminal is detected, and the primary voltage is estimated based on the voltage. Therefore, instead of directly measuring the primary voltage, it can be detected by estimation.

[0109] The present invention is not limited to the above-described embodiments, and various modifications can be made within the scope shown in the claims. Embodiments obtained by appropriately combining the technical means separately disclosed in different embodiments are also included in the technical scope of the present invention. Furthermore, by combining the technical means separately disclosed in each embodiment, new technical features can be formed.

Claims

1. A gas-insulated transformer, characterized in that, Comprising: A core; A secondary winding wound around the core; A primary winding coaxially wound around the outer periphery of the secondary winding; A high-voltage shield covering the outer periphery of the primary winding; A low-voltage shield facing the high-voltage shield; A grounding terminal; And A circuit element having one end connected to the low-voltage shield and the other end connected to the grounding terminal, wherein the axial direction of the secondary winding is longer than the axial direction of the primary winding, and the gas-insulated transformer further includes a lead connection portion that connects the lead of the secondary winding, and the low-voltage shield is disposed between the high-voltage shield and the lead connection portion.

2. The gas-insulated transformer according to claim 1, wherein: It further includes a voltage detector connected between the one end of the circuit element and the grounding terminal.

3. A gas-insulated transformer system, characterized in that Comprising: The gas-insulated transformer according to claim 2; And A primary voltage estimation device that estimates the magnitude of the primary voltage based on the voltage detected by the voltage detector.

4. A voltage estimation method, which is a voltage estimation method for estimating the primary voltage of a gas-insulated transformer, and the gas-insulated transformer includes: A core; A secondary winding wound around the core; A primary winding coaxially wound around the outer periphery of the secondary winding; A high-voltage shield covering the outer periphery of the primary winding; A low-voltage shield facing the high-voltage shield; A grounding terminal; And A circuit element having one end connected to the low-voltage shield and the other end connected to the grounding terminal, wherein the voltage estimation method is characterized by including: A step of detecting the voltage applied to the circuit element; And A step of estimating the primary voltage based on the electrostatic capacitance between the high-voltage shield and the low-voltage shield, the circuit constant of the circuit element, and the voltage applied to the circuit element, wherein in the gas-insulated transformer, the axial direction of the secondary winding is longer than the axial direction of the primary winding, and the gas-insulated transformer further includes a lead connection portion that connects the lead of the secondary winding, and the low-voltage shield is disposed between the high-voltage shield and the lead connection portion.

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