An inverted wideband voltage transformer

Abstract

This invention provides an inverted wideband voltage transformer suitable for transmission lines / high-voltage busbars. It includes a measuring electrode (1), a shielding electrode (2), a support rod (3), and a measuring electrode. The shielding electrode (2) is a hollow cylindrical shape. The measuring electrode (1) is fixed inside the shielding electrode (2) by the support rod (3), and the sum of the thickness of the measuring electrode (1) and the height of the support rod (3) is less than the height of the shielding electrode (2). The transformer is used to measure the wideband voltage of power electronic equipment based on the stray capacitance to ground of the measuring electrode (1) and the shielding electrode (2). It has strong environmental adaptability and can achieve wideband voltage measurement. The voltage division ratio is stable and the measurement accuracy is high. Moreover, it does not require complex insulation and support structures and can be directly suspended under high-voltage equipment such as transmission lines and busbars. The structure is simple, the volume and weight are significantly reduced, and the installation is convenient.

Description

Technical Field

[0001] This invention relates to the field of power system automation technology, and specifically to an inverted wideband voltage transformer. Background Technology

[0002] Voltage transformers are used to provide measurement signals to measuring instruments on the low-voltage side. According to their principles, they can be divided into electromagnetic voltage transformers, voltage divider voltage transformers, and electronic voltage transformers. In high-voltage power grids, voltage transformers composed of voltage dividers and measuring units are mainly used.

[0003] Existing voltage transformer dividers generally use resistive dividers, RC dividers, or capacitive dividers. 1) For resistive and RC dividers, due to the large resistance and capacitance of the resistive divider, the potential distribution of the power electronic equipment will be changed after it is connected. In addition, the longitudinal dimensions and volume of the resistive / RC divider, which is composed of physical resistors / capacitors, are large, requiring complex insulation support structures, resulting in high cost and poor environmental adaptability. 2) Capacitive dividers are composed of high-voltage arm capacitors and low-voltage arm capacitors connected in series. Due to the large capacitance of the high-voltage arm capacitor, which is generally in the range of several hundred to several thousand pF, the transient performance of the capacitive divider is poor, making it difficult to achieve wide-frequency voltage measurement. It also requires insulation support, resulting in high price and cost, and is not suitable for distributed measurement. Summary of the Invention

[0004] To overcome the shortcomings of the prior art, such as inconvenience in installation, poor environmental adaptability, and difficulty in measuring wideband voltage, the present invention provides an inverted wideband voltage transformer, which is fixed on a transmission line / high-voltage bus. It includes a measuring electrode (1), a shielding electrode, a support rod, and a measuring electrode (3). The shielding electrode (2) is a hollow cylindrical shape. The measuring electrode (1) is fixed inside the shielding electrode (2) by the support rod (3), and the sum of the thickness of the measuring electrode (1) and the height of the support rod (3) is less than the height of the shielding electrode (2). The transformer is used to measure the wideband voltage of power electronic equipment based on the stray capacitance to ground of the measuring electrode (1) and the shielding electrode (2), which is easy to install, has strong environmental adaptability, and can achieve wideband voltage measurement.

[0005] To achieve the above-mentioned objectives, the present invention adopts the following technical solution:

[0006] On the one hand, the present invention provides an inverted wideband voltage transformer, fixed on a transmission line / high voltage bus, which includes a measuring electrode (1), a shielding electrode (2) and a support rod (3);

[0007] The shielding electrode (2) is a hollow cylindrical shape; the measuring electrode (1) is fixed inside the shielding electrode (2) by a support rod (3), and the sum of the thickness of the measuring electrode (1) and the height of the support rod (3) is less than the height of the shielding electrode (2);

[0008] The current transformer is used to measure the broadband voltage of power electronic equipment based on the stray capacitance to ground of the measuring electrode (1) and the shielding electrode (2).

[0009] The measuring electrode (1) is circular.

[0010] It also includes the measuring capacitor C, the harmonic suppression resistor R, the first shielding lead, and the second shielding lead;

[0011] One end of the harmonic suppression resistor R is connected to the measuring electrode (1) through the first shielding lead, and the other end is connected to the positive terminal of the measuring capacitor C. The negative terminal of the measuring capacitor C is connected to the shielding electrode (2) through the second shielding lead.

[0012] It also includes a signal output board;

[0013] The measuring capacitor C and the harmonic suppression resistor R are both fixed on the signal output board.

[0014] The measuring electrode (1) and the shielding electrode (2) are both made of metal, and the support rod (3) is made of insulating material.

[0015] The metal material is made of iron, copper or aluminum, and the insulating material is made of epoxy resin or PVC.

[0016] The measuring electrode (1) and the support rod (3) are connected by bolts, as are the shielding electrode (2) and the support rod (3).

[0017] The height of the measuring electrode (1) above the horizontal plane is greater than 10 times the diameter of the measuring electrode (1).

[0018] The stray capacitance to ground of the shielding electrode (2) and the stray capacitance to ground of the measuring electrode (1) satisfy the following relationship:

[0019] C a / C b =C m / C s

[0020] Among them, C a C is the capacitance value of the matching capacitor set in the shielded branch. b C is the capacitance of the stray capacitance to ground of the shielding electrode (2). m To measure the capacitance value of the measuring capacitor in the branch, C s The capacitance value of the stray capacitance to ground of the measuring electrode (1) is used.

[0021] Compared with the closest existing technology, the technical solution provided by the present invention has the following beneficial effects:

[0022] The inverted wideband voltage transformer provided by this invention is suitable for transmission lines / high-voltage busbars. It includes a measuring electrode (1), a shielding electrode (2), and a support rod (3). The shielding electrode (2) is a hollow cylindrical shape. The measuring electrode (1) is fixed inside the shielding electrode (2) by the support rod (3). The sum of the thickness of the measuring electrode (1) and the height of the support rod (3) is less than the height of the shielding electrode (2). The transformer is used to measure the wideband voltage of power electronic equipment based on the stray capacitance to ground of the measuring electrode (1) and the shielding electrode (2). It is easy to install, has strong environmental adaptability, and can realize the measurement of wideband voltage.

[0023] The inverted wideband voltage transformer provided by this invention has a small capacitance value and a simple measurement branch. It can directly measure voltage without the need for an additional electromagnetic unit, and can realize wideband voltage measurement, thus meeting the requirements of power systems for transient voltage measurement.

[0024] The inverted wideband voltage transformer provided by this invention uses the stray capacitance to ground as the high-voltage arm. Under the condition of satisfying the isolated conductor effect, the stray capacitance to ground is only related to the size of the measuring electrode and the height above the ground, and is not related to external factors such as ambient temperature. The overall voltage division ratio of the voltage divider is more stable and the measurement accuracy is high.

[0025] The inverted wideband voltage transformer provided by this invention does not require complex insulation and support structures and can be directly suspended under high-voltage equipment such as transmission lines and busbars. It has a simple structure, significantly reduced size and weight, and low cost. Attached Figure Description

[0026] Figure 1 This is a structural diagram of the inverted wideband voltage transformer in an embodiment of the present invention;

[0027] Figure 2 This is a schematic diagram of the inverted wideband voltage transformer in an embodiment of the present invention;

[0028] In the diagram, 1 is the measuring electrode, 2 is the shielding electrode, and 3 is the support rod. Detailed Implementation

[0029] The present invention will now be described in further detail with reference to the accompanying drawings.

[0030] This invention provides an inverted wideband voltage transformer, fixed to a transmission line / high-voltage busbar, such as... Figure 1 As shown, it includes a measuring electrode 1, a shielding electrode 2, and a support rod 3;

[0031] Measuring electrode 1 is circular, and shielding electrode 2 is a hollow cylindrical shape;

[0032] The measuring electrode 1 is fixed inside the shielding electrode 2 by the support rod 3, and the sum of the thickness of the measuring electrode 1 and the height of the support rod 3 is less than the height of the shielding electrode 2, that is, the height of the measuring electrode 1 from the ground is greater than the height of the lower edge of the shielding electrode 2 from the ground.

[0033] The current transformer is used to measure the broadband voltage of power electronic equipment based on the stray capacitance to ground of each of the measuring electrode 1 and the shielding electrode 2.

[0034] In field applications, the measured objects are often complex environments with multiple conductors and potentials on their surfaces, such as parallel three-phase lines. There are also stray capacitances between adjacent lines and the measuring electrodes, and the voltage of adjacent lines will also generate coupling voltage on the measuring electrodes, affecting the measurement accuracy. Therefore, the shielding electrode 2 in this embodiment of the invention is used to protect the measuring electrode 1 and avoid the impact of live bodies around the transmission line / high voltage bus on the measurement accuracy of the transformer.

[0035] It also includes the measuring capacitor C, the harmonic suppression resistor R, the first shielding lead, and the second shielding lead;

[0036] One end of the harmonic suppression resistor R is connected to the measuring electrode 1 through the first shielding lead, and the other end is connected to the positive terminal of the measuring capacitor C. The negative terminal of the measuring capacitor C is connected to the shielding electrode 2 through the second shielding lead.

[0037] It also includes a signal output board;

[0038] The measuring capacitor C and the harmonic suppression resistor R are both fixed on the signal output board.

[0039] Both measuring electrode 1 and shielding electrode 2 are made of metal, and support rod 3 is made of insulating material.

[0040] The metal material is made of iron, copper or aluminum, and the insulating material is made of epoxy resin or PVC.

[0041] The measuring electrode 1 and the support rod 3, as well as the shielding electrode 2 and the support rod 3, are all connected by bolts.

[0042] When there are no other charged bodies or conductors nearby, a conductor can be considered an isolated conductor. Its stray capacitance to ground is only related to the conductor size and height above ground, and is independent of the conductor's charge and potential. When the height above ground is greater than 10 times its maximum size, its stray capacitance to ground is basically fixed, and it does not change significantly due to environmental changes (laboratory or outdoor). In this embodiment of the invention, the height of the measuring electrode 1 above the horizontal plane is greater than 10 times the diameter of the measuring electrode 1. The measuring electrode 1 is equivalent to an isolated conductor. The stray capacitance to ground of an isolated conductor is relatively fixed and is basically independent of factors such as temperature. Therefore, the stray capacitance can be used to form the high-voltage arm of a capacitive voltage divider. At the same time, the stray capacitance to ground of the measuring electrode 1 is connected in series with the measuring capacitor in the measuring branch to form the measuring branch. The stray capacitance to ground of the shielding electrode 2 is connected in series with the matching capacitor to form the shielding branch. In order to shield the influence of the adjacent measuring electrode 1 and the electric field on the measuring electrode, a shielding branch is set on the outside of the measuring circuit, thereby forming an equipotential shielding structure and further enhancing the accuracy of the measuring branch.

[0043] The working principle of the wideband voltage transformer provided in this embodiment of the invention is as follows: Figure 2 As shown, the inter-electrode capacitance between measuring electrode 1 and shielding electrode 2 is C. r The capacitance of the stray capacitance to ground of measuring electrode 1 is C. s The stray capacitance to ground of shielding electrode 2 is C. b The capacitance of the matching capacitor set in the shielded branch is C. a Assume the capacitance of the measuring capacitor in the measuring branch is C. m The stray capacitance to ground of measuring electrode 1 is connected in series with the measuring capacitor in the measuring branch to form the measuring branch. The stray capacitance to ground of shielding electrode 2 is connected in series with the matching capacitor to form the shielding branch. Then, the capacitance values ​​of the stray capacitance to ground of shielding electrode 2 and the stray capacitance to ground of measuring electrode 1 satisfy the following relationship:

[0044] C a / C b =C m / C s

[0045] Among them, C a C is the capacitance value of the matching capacitor set in the shielded branch. b C is the capacitance of the stray capacitance to ground of shielding electrode 2. m To measure the capacitance value of the measuring capacitor in the branch, C s The value of the stray capacitance to ground of electrode 1 is measured.

[0046] Due to the protection of the shielded branch, the stray capacitance to ground of measuring electrode 1 is under equipotential shielding protection. The stray capacitance between the surrounding charged body and the capacitor voltage divider only affects the value of the matching capacitance (since the capacitance between adjacent conductors and the shield is generally in the pF range, while the matching capacitance is generally in the nF range, the change in the matching capacitance is also very small), and does not affect the stray capacitance to ground of measuring electrode 1, thus ensuring the stability of the stray capacitance to ground of measuring electrode 1.

[0047] By measuring the capacitance value C m The high-voltage side voltage of the broadband voltage transformer can then be obtained, with the voltage division ratio being: U1 is the voltage across the measuring capacitor, and U0 is the high-voltage side voltage of the broadband voltage transformer. To prevent stray capacitance to ground of measuring electrode 1, the measuring capacitor, and the high-voltage lead from forming series, a harmonic suppression resistor is added to the measuring branch. To maintain the turns ratio, the harmonic suppression resistor is divided into R1 and R2, where R2 / R1 = C. m / C s .

[0048] In this embodiment, the measuring electrode 1 is a circular electrode with a diameter of 500mm and a thickness of 2mm, made of aluminum. When its height above the ground exceeds 5 meters, its stray capacitance to ground remains relatively stable at around 1.5pF. If the installation height differs from the calculated distance by 1m, the resulting transformation ratio error is approximately 0.4%. The shielding electrode 2 is cylindrical with a diameter of 1000mm and a height of 500mm. The installation depth of the measuring electrode 1 is 150mm, meaning the measuring electrode 1 is 150mm from the lower edge of the shielding electrode 2. Both the measuring electrode 1 and the shielding electrode 2 have anti-corona measures along their edges. The obtained C... s Approximately 1.45 pF, C b Approximately 56.45 pF, C r It is approximately 27 pF. Based on the required ratio, the corresponding Cm and Ca can be obtained.

[0049] This invention, based on the isolated conductor effect, utilizes the characteristic that the stray capacitance to ground of measuring electrode 1 is essentially fixed and largely unaffected by the environment. A high-voltage arm with a stable capacitance value is constructed using this stray capacitance, i.e., an inverted type, eliminating the need for complex insulation support structures. Furthermore, this invention utilizes shielding electrode 2 to construct equipotential shielding, suppressing the influence of adjacent conductors and electric fields on the measuring branch. Under the equipotential shielding structure, the stray capacitance between adjacent conductors and the shielded branch only affects the capacitance value of the matching capacitor, which, due to its larger capacitance value, has a relatively lower impact.

[0050] For ease of description, the various parts of the device described above are divided into modules or units according to their functions. Of course, in implementing this application, the functions of each module or unit can be implemented in one or more software or hardware components.

[0051] Those skilled in the art will understand that embodiments of this application can be provided as methods, systems, or computer program products. Therefore, this application can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, this application can take the form of a computer program product embodied on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0052] This application is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of this application. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart... Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0053] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0054] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0055] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Those skilled in the art can still make modifications or equivalent substitutions to the specific implementation of the present invention by referring to the above embodiments. Any modifications or equivalent substitutions that do not depart from the spirit and scope of the present invention are within the protection scope of the claims of the present invention pending approval.

Claims

1. An inverted wideband voltage transformer, characterized in that, Fixed to the transmission line / high voltage busbar, it includes a measuring electrode (1), a shielding electrode (2) and a support rod (3); The shielding electrode (2) is a hollow cylindrical shape; The measuring electrode (1) is fixed inside the shielding electrode (2) by a support rod (3), and the sum of the thickness of the measuring electrode (1) and the height of the support rod (3) is less than the height of the shielding electrode (2). The current transformer is used to measure the broadband voltage of power electronic equipment based on the stray capacitance to ground of each of the measuring electrode (1) and the shielding electrode (2); The stray capacitance to ground of the measuring electrode (1) is connected in series with the measuring capacitor to form a measuring branch. The stray capacitance to ground of the shielding electrode (2) is connected in series with the matching capacitor to form a shielding branch. The first end of the measuring branch is connected to the first end of the shielding branch. The second end of the measuring branch and the second end of the shielding branch are grounded to form an equipotential shielding structure. The stray capacitance to ground of the shielding electrode (2) and the stray capacitance to ground of the measuring electrode (1) satisfy the following relationship: C a / C b =C m / C s Among them, C a C is the capacitance value of the matching capacitor set in the shielded branch. b C is the capacitance of the stray capacitance to ground of the shielding electrode (2). m To measure the capacitance value of the measuring capacitor in the branch, C s The capacitance value of the stray capacitance to ground of the measuring electrode (1) is used.

2. The inverted wideband voltage transformer according to claim 1, characterized in that, The measuring electrode (1) is circular.

3. The inverted wideband voltage transformer according to claim 1, characterized in that, It also includes the measuring capacitor C, the harmonic suppression resistor R, the first shielding lead, and the second shielding lead; One end of the harmonic suppression resistor R is connected to the measuring electrode (1) through the first shielding lead, and the other end is connected to the positive terminal of the measuring capacitor C. The negative terminal of the measuring capacitor C is connected to the shielding electrode (2) through the second shielding lead.

4. The inverted wideband voltage transformer according to claim 3, characterized in that, It also includes a signal output board; The measuring capacitor C and the harmonic suppression resistor R are both fixed on the signal output board.

5. The inverted wideband voltage transformer according to claim 1, characterized in that, The measuring electrode (1) and the shielding electrode (2) are both made of metal, and the support rod (3) is made of insulating material.

6. The inverted wideband voltage transformer according to claim 5, characterized in that, The metal material is made of iron, copper or aluminum, and the insulating material is made of epoxy resin or PVC.

7. The inverted wideband voltage transformer according to claim 1, characterized in that, The measuring electrode (1) and the support rod (3) are connected by bolts, as are the shielding electrode (2) and the support rod (3).

8. The inverted wideband voltage transformer according to claim 1, characterized in that, The height of the measuring electrode (1) from the zero potential horizontal plane is greater than 10 times the diameter of the measuring electrode (1).

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