A multi-point voltage difference measuring device

Abstract

This utility model relates to a multi-point voltage difference measuring device, belonging to the technical field of power system transformers. It includes several voltage transformers connected in series, with flanges connecting two stages of transformers. A ring-shaped voltage-equalizing shield is installed at the connection point between the two stages. Each stage of the voltage transformer contains a signal processing board, a measuring winding, and a power extraction winding. Each stage of the voltage transformer has measuring terminals connected to the device under test. The measuring winding and the power extraction winding are independently packaged. The measuring winding is connected to the signal processing board for measuring the voltage difference between the device under test connected to each stage of the measuring winding. The power extraction winding is connected to the signal processing board for supplying power to the signal processing board. This utility model, by employing a multi-stage series voltage transformer structure, not only achieves simultaneous measurement of multi-point potential voltage differences but also disperses the insulation pressure brought by high voltage, further enhancing the insulation performance and safety of the device.

Description

Technical Field

[0001] This utility model belongs to the field of power system transformer technology, specifically relating to a multi-point voltage difference measurement device. Background Technology

[0002] In power systems, voltage measurement is a crucial component, directly impacting stable operation and safety monitoring. Traditional voltage measurement devices, such as capacitive voltage transformers, typically employ a single-stage structure. While this structure performs adequately when measuring the voltage difference between two potential points relative to ground or between phases, it falls short when faced with the demands of simultaneous multi-point potential voltage difference measurement in modern power systems.

[0003] Specifically, in traditional capacitive voltage transformers, the high voltage is entirely handled by a single module. This makes the insulation material susceptible to the effects of electric field concentration, posing an insulation risk. Furthermore, in new power systems such as ultra-high voltage, new energy, and smart grids, the number of potential points requiring simultaneous measurement increases significantly due to the high voltage levels and complex system structures. Traditional capacitive voltage transformers, due to structural limitations, cannot simultaneously measure the potential difference at multiple points, which undoubtedly restricts their application in these new power systems. Utility Model Content

[0004] The purpose of this invention is to address the shortcomings of existing technologies, such as the inability of traditional capacitive voltage transformers to simultaneously measure multi-point potential voltage differences due to structural limitations. This invention provides a multi-point potential voltage difference measuring device to solve the problems existing in the prior art.

[0005] To achieve the above objectives, the present invention provides the following technical solution:

[0006] A multi-point voltage difference measuring device includes several voltage transformers connected in series, with two voltage transformers connected by a flange, and an annular equalizing shield provided at the connection point of the two voltage transformers.

[0007] Each stage of voltage transformer contains a signal processing board, a measurement winding, and a power extraction winding. Each stage of voltage transformer has measurement terminals that are connected to the device under test. The measurement winding and the power extraction winding are independently packaged. The measurement winding is connected to the signal processing board and is used to measure the voltage difference between the device under test connected to each stage's measurement winding. The power extraction winding is connected to the signal processing board and is used to power the signal processing board.

[0008] Further improvements to this technical solution include installing the annular equalizing shield between the flanges of the two voltage transformers, or wrapping it around the flange.

[0009] A further improvement to this technical solution is that an isolation magnetic core is provided between the measuring winding and the energy harvesting winding.

[0010] Further improvements to this technical solution include the addition of a permalloy fast-saturation coil damper within the voltage transformer, which is arranged in parallel with the measuring winding and the energy extraction winding.

[0011] Further improvements to this technical solution include the following: the voltage transformer also includes a first capacitor, a second capacitor, a primary winding, a compensating reactor, and a surge arrester. The first terminal of the first capacitor is connected to the first measuring terminal of the voltage transformer. The second terminal of the first capacitor is connected to the first terminal of the second capacitor and the first terminal of the primary winding. The second terminal of the primary winding is connected to the first terminal of the compensating reactor and the first terminal of the surge arrester. The second terminals of the second capacitor, the compensating reactor, and the surge arrester are all connected to the second measuring terminal of the voltage transformer. The first measuring terminal is connected to the second measuring terminal of the device under test and / or the voltage transformer connected in series with it. The second measuring terminal can also be grounded.

[0012] Further improvements to this technical solution include that the voltage transformer also includes an insulating bushing, and the primary winding, measuring winding, energy extraction winding, isolation magnetic core, and molybdenum alloy fast saturation coil damper are all housed inside the insulating bushing, which is made of silicone rubber composite bushing.

[0013] A further improvement to this technical solution is that an oil tank for holding transformer oil is also installed inside the insulating bushing.

[0014] Further improvements to this technical solution include a junction box for the voltage transformer, in which the first capacitor, the second capacitor, the compensating reactor, and the surge arrester are all housed, and the insulating bushing is fixedly installed above the junction box.

[0015] The beneficial effects of this invention are as follows: By proposing a multi-point voltage difference measuring device, it overcomes the limitations of traditional capacitive voltage transformers in modern power systems. Through the adoption of a multi-stage series voltage transformer structure, it not only achieves simultaneous measurement of multi-point potential voltage differences but also disperses the insulation pressure brought by high voltage, reducing insulation risks and improving measurement flexibility and applicability. The flange connection and annular equalizing shield design optimize the electric field distribution, reduce local field strength, and further enhance the insulation performance and safety of the device. Further improvements, such as the installation of an isolating magnetic core and the application of a permalloy fast-saturating coil damper, greatly enhance the stability and anti-interference capability of the device, prevent damage to the device under abnormal conditions, and improve measurement accuracy.

[0016] Furthermore, the design principle of this utility model is reliable, the structure is simple, and it has a very wide range of application prospects.

[0017] It is evident that this utility model has outstanding substantive features and significant progress compared with the prior art, and the beneficial effects of its implementation are also obvious. Attached Figure Description

[0018] To more clearly illustrate the technical solution of this utility model, the drawings used in the description will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 This is a schematic diagram of a multi-point voltage difference measuring device.

[0020] Figure 2 This is a circuit diagram of the internal circuitry of a multi-point voltage difference measuring device.

[0021] 110 is a flange, 120 is an insulating sleeve, and 130 is a junction box.

[0022] H1 is the high-voltage terminal (320 kV), H2 is the high-voltage terminal (240 kV), H3 is the high-voltage terminal (160 kV), H4 is the high-voltage terminal (80 kV), 1-C1, 2-C1, 3-C1, 4-C1 are high-voltage capacitors, 1-C2, 2-C2, 3-C2, 4-C2 are medium-voltage capacitors, 1-Tr, 2-Tr, 3-Tr, 4-Tr are intermediate transformers, 1a-1n is the measuring winding, 2a-2n is the energy extraction winding, 1-L, 2-L, 3-L, 4-L are compensating reactors, B L For surge arresters, X L N is the low-voltage terminal, and N is the low-voltage terminal of the capacitor divider. Detailed Implementation

[0023] To make the objectives, features, and advantages of this utility model more apparent and understandable, the technical solutions of this utility model will be clearly and completely described below with reference to the accompanying drawings of the specific embodiments. Obviously, the embodiments described below are only some embodiments of this utility model, and not all embodiments. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0024] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention.

[0025] like Figure 1and Figure 2 As shown, this utility model provides a multi-point voltage difference measuring device, including several voltage transformers connected in series. Two voltage transformers are connected by a flange, and an annular equalizing shield is provided at the connection point of the two voltage transformers. Each voltage transformer has a signal processing board, a measuring winding, and a power extraction winding. Each voltage transformer has a measuring terminal, which is connected to the device under test. The measuring winding and the power extraction winding are independently packaged. The measuring winding is connected to the signal processing board and is used to measure the voltage difference between the device under test connected to each measuring winding. The power extraction winding is connected to the signal processing board and is used to supply power to the signal processing board.

[0026] The device uses four voltage transformers connected in series. Each voltage transformer has the same structure. If the total voltage is 550kV (phase voltage is 320kV), then the phase voltage of each stage is 80kV.

[0027] Specifically, the annular equipotential shield is installed between the flanges of the two voltage transformers or fitted around the flange. Whether installed between the flanges or fitted around the flange, the annular equipotential shield optimizes the interstage electric field. In practical applications, such as in ultra-high voltage power systems, uneven electric fields can easily lead to excessively high local electric field strength, accelerating the aging and damage of insulation materials and affecting the normal operation and service life of the equipment. The annular equipotential shield effectively improves this situation, dispersing the electric field evenly, reducing the local field strength by more than 30%, greatly improving the insulation performance of the entire device, and ensuring stable operation of the equipment under high voltage conditions. The presence of the equipotential shield reduces electric field concentration, thereby reducing the electric field pressure on the insulation material. Traditional capacitive voltage transformers, due to electric field concentration, are susceptible to damage to the insulation material, posing safety hazards. This device, through the reasonable setting of the annular equipotential shield, makes the electric field on the insulation material more uniform, effectively mitigating the damage to insulation caused by electric field concentration, enhancing the overall insulation performance of the device, reducing the probability of insulation failure, and improving the safety and reliability of power system operation.

[0028] In addition, an isolation magnetic core (using a low-loss ferrite core, such as manganese-zinc ferrite, with a permeability ≥5000 H / m and coercivity ≤10 A / m) is installed between the measuring winding and the power harvesting winding to effectively block the electromagnetic coupling path between them; it is designed as a ring-shaped closed magnetic core, surrounding the independent encapsulated cavities of the measuring and power harvesting windings to form a closed magnetic circuit, minimizing leakage magnetic interference). The measuring winding is responsible for accurately measuring the voltage difference between various potential points, providing crucial data for monitoring the power system's operating status; the power harvesting winding supplies power to the signal processing board, maintaining the device's normal operation. During actual operation, these two windings generate electromagnetic interference, affecting the accuracy of measurements. The isolation magnetic core effectively blocks the electromagnetic coupling between them. For example, in a power environment with high harmonic content, without the isolation magnetic core, the measuring winding is susceptible to electromagnetic interference from the power harvesting winding, potentially leading to significant deviations in the measurement data. However, with the isolation core, this interference can be significantly reduced, allowing the measuring winding to accurately acquire voltage signals and ensuring linear transmission of voltage signals at each stage. This results in an overall measurement accuracy of 0.1%, providing reliable monitoring data for the stable operation of the power system. The power harvesting winding supplies power to the signal processing board. If it is affected by electromagnetic interference from the measuring winding, it can lead to a decline in output power quality, causing voltage fluctuations and current instability, affecting the normal operation of the signal processing board. The isolation core avoids such interference, ensuring a stable power output from the power harvesting winding and allowing the signal processing board to operate continuously and stably. In situations where power system voltage fluctuations are frequent, the isolation core ensures that the signal processing board remains unaffected, stably processing and transmitting measurement data, significantly improving the device's reliability and reducing the risk of equipment failure due to unstable power supply.

[0029] Furthermore, the voltage transformer is also equipped with a permalloy fast-saturation coil damper (permeability ≥50,000 H / m, coercivity ≤2 A / m; the fast-saturation coil is wound in a multi-layer spiral shape with 50-100 turns), which is installed in parallel with the measuring winding and the energy extraction winding. During the operation of the power system, capacitive voltage transformers may experience resonance due to changes in system parameters, external interference, and other factors. The overvoltage and overcurrent generated by resonance can cause serious damage to the voltage transformer and the entire power system. The permalloy fast-saturation coil damper can respond quickly when resonance occurs. It has the characteristics of high permeability and low hysteresis loss. When the abnormal current generated by resonance passes through, the coil quickly saturates, exhibiting a high impedance state, thereby rapidly absorbing the resonance energy and effectively suppressing the continued development of resonance. In practical ultra-high voltage power transmission scenarios, this damper can limit resonant overvoltages within a safe range, protecting the measuring winding, energy extraction winding, and other internal components, preventing equipment damage caused by resonance, and ensuring the safe and stable operation of the voltage transformer and even the entire power system. Resonance distorts the measurement signal of the voltage transformer, severely affecting measurement accuracy. Because the permalloy fast-saturating coil damper effectively suppresses resonance, it ensures a stable electromagnetic environment for the measuring winding. This allows the measuring winding to accurately measure the voltage difference between potential points, avoiding measurement errors caused by resonant interference. In new power systems, where voltage measurement accuracy is extremely high, the presence of this damper ensures that the measuring device can output accurate and reliable data, providing strong support for power system monitoring, dispatching, and fault diagnosis. It also helps power operation and maintenance personnel to grasp the system's operating status in a timely and accurate manner and make informed decisions.

[0030] In addition, the voltage transformer also contains a first capacitor (1-C1, 2-C1, 3-C1, 4-C1), a second capacitor (1-C2, 2-C2, 3-C2, 4-C2), a primary winding (the primary winding of the intermediate transformers 1-Tr, 2-Tr, 3-Tr, 4-Tr), a compensating reactor (1-L, 2-L, 3-L, 4-L), and a surge arrester B. LThe first terminal of the first capacitor is connected to the first measuring terminal (H1, H2, H3, H4) of the voltage transformer. The second terminal of the first capacitor is connected to the first terminal of the second capacitor and the first terminal of the primary winding. The second terminal of the primary winding is connected to the first terminal of the compensating reactor and the first terminal of the surge arrester. The second terminals of the second capacitor, the compensating reactor, and the surge arrester are all connected to the second measuring terminal of the voltage transformer. The first measuring terminal is connected to the second measuring terminal of the device under test and / or the voltage transformer connected in series with it. The second measuring terminal can also be grounded. The first capacitor and the second capacitor are connected in series to form a capacitor voltage divider chain. The first terminal of the first capacitor is connected to the first measuring terminal of the voltage transformer and directly connected to the high-voltage device under test (such as a transmission line). The second terminal of the first capacitor is connected to the first terminal of the second capacitor and the first terminal of the primary winding to form an intermediate potential point. The second terminal of the primary winding is connected to the compensating reactor and the surge arrester for adjusting circuit impedance and overvoltage protection. Among them, the compensating reactor compensates for the capacitive error of the capacitor voltage divider chain through inductance compensation, optimizes the linearity of the voltage signal, and ensures the accuracy of wide-band (including harmonics) measurement; the surge arrester uses a zinc oxide nonlinear resistor connected in parallel at the output of the voltage divider chain to absorb transient overvoltages (such as lightning strikes or switching overvoltages) and protect the downstream measurement windings and signal processing boards.

[0031] To improve insulation performance, the voltage transformer also includes an insulating bushing. The primary winding, measuring winding (1a-1n), energy extraction winding (2a-2n), isolation core, and molybdenum alloy fast-saturation coil damper are all housed within the insulating bushing, which is made of silicone rubber composite bushing. In addition, an oil tank for storing transformer oil is also installed inside the insulating bushing.

[0032] Furthermore, the voltage transformer also includes a junction box, a first capacitor (1-C1, 2-C1, 3-C1, 4-C1), a second capacitor (1-C2, 2-C2, 3-C2, 4-C2), a compensating reactor (1-L, 2-L, 3-L, 4-L), and a surge arrester B. L All are installed inside the junction box, with the insulating sleeve fixedly installed above the junction box.

[0033] Starting from the top layer (Level 1) of the device, based on voltage distribution and stress conditions, the wall thickness of the Level 1 bushing is determined to be 20mm, with 8 stiffening ribs. As the device progresses downwards, the wall thickness of the Level 2 bushing increases to 22mm, and the number of stiffening ribs increases to 10; the wall thickness of the Level 3 bushing further increases to 25mm, with 12 stiffening ribs; and in the bottom Level 4, due to the relatively greater pressure and voltage, the bushing wall thickness reaches 30mm, and the number of stiffening ribs also increases to 15. Simultaneously, the junction box is manufactured using aluminum alloy casting technology, with parameters such as alloy composition and casting temperature controlled during the casting process to ensure the strength and stability of the junction box.

[0034] In terms of seismic structural design, each level employs silicone rubber composite sleeves and aluminum alloy cast enclosures. Taking one level as an example, the silicone rubber material in the silicone rubber composite sleeve is selected for its high elasticity, high strength, and good weather resistance. Through a vulcanization process, the silicone rubber is tightly bonded to the internal reinforcing fibers, improving the sleeve's seismic performance. The aluminum alloy cast enclosure is designed with mechanical structure in mind, incorporating reinforcing ribs to enhance the overall rigidity of the enclosure.

[0035] The working principle of this multi-point voltage difference measuring device is as follows: The device utilizes a multi-stage series-connected voltage transformer structure, combined with internally designed first capacitors (1-C1, 2-C1, 3-C1, 4-C1), second capacitors (1-C2, 2-C2, 3-C2, 4-C2), primary windings, compensating reactors, and surge arresters to simultaneously measure the voltage difference between multiple potential points (H1, H2, H3, H4) and ground. Specifically, each voltage transformer is responsible for measuring the voltage difference between adjacent potential points. Its first measuring terminal is connected to the potential point to be measured (e.g., H1, H2) or the second measuring terminal of the voltage transformer connected in series with it. The second measuring terminal can be grounded or connected to the next potential point as needed. The connection method of the capacitors and windings optimizes the frequency response and phase characteristics of the measurement circuit, ensuring measurement accuracy. The compensating reactor compensates for the inductive component, further improving measurement stability. The surge arrester effectively protects the device from overvoltage surges. With this design, the device can capture the voltage changes between potential points and the voltage difference between them and ground in real time and accurately, providing reliable data support for the monitoring, control and protection of power systems.

[0036] The above description of the disclosed embodiments enables those skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A multi-point voltage difference measuring device, characterized in that, It includes several voltage transformers connected in series, with two voltage transformers connected by a flange, and an annular equalizing shield installed at the connection point of the two voltage transformers. Each stage of voltage transformer contains a signal processing board, a measurement winding, and a power extraction winding. Each stage of voltage transformer has measurement terminals that are connected to the device under test. The measurement winding and the power extraction winding are independently packaged. The measurement winding is connected to the signal processing board and is used to measure the voltage difference between the device under test connected to each stage's measurement winding. The power extraction winding is connected to the signal processing board and is used to power the signal processing board.

2. The multi-point voltage difference measuring device according to claim 1, characterized in that, The ring-shaped equalizing shield is installed between the flanges of the two voltage transformers, or sleeved around the flange.

3. The multi-point voltage difference measuring device according to claim 1, characterized in that, An isolation core is provided between the measuring winding and the energy harvesting winding.

4. The multi-point voltage difference measuring device according to claim 3, characterized in that, The voltage transformer is also equipped with a permalloy fast saturation coil damper, which is arranged in parallel with the measuring winding and the energy extraction winding.

5. The multi-point voltage difference measuring device according to claim 4, characterized in that, The voltage transformer also includes a first capacitor, a second capacitor, a primary winding, a compensating reactor, and a surge arrester. The first terminal of the first capacitor is connected to the first measuring terminal of the voltage transformer. The second terminal of the first capacitor is connected to the first terminal of the second capacitor and the first terminal of the primary winding. The second terminal of the primary winding is connected to the first terminal of the compensating reactor and the first terminal of the surge arrester. The second terminals of the second capacitor, the compensating reactor, and the surge arrester are all connected to the second measuring terminal of the voltage transformer. The first measuring terminal is connected to the second measuring terminal of the device under test and / or the voltage transformer connected in series with it. The second measuring terminal can also be grounded.

6. The multi-point voltage difference measuring device according to claim 5, characterized in that, The voltage transformer also includes an insulating bushing. The primary winding, measuring winding, energy extraction winding, isolation core, and molybdenum alloy fast saturation coil damper are all housed inside the insulating bushing, which is made of silicone rubber composite bushing.

7. The multi-point voltage difference measuring device according to claim 6, characterized in that, The insulating bushing also contains an oil tank for storing transformer oil.

8. The multi-point voltage difference measuring device according to claim 6, characterized in that, The voltage transformer also includes a junction box, in which the first capacitor, the second capacitor, the compensating reactor, and the surge arrester are all housed. The insulating bushing is fixedly installed above the junction box.

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