WO2023020633A1

WO2023020633A1 - Capacitive voltage transformer, monitoring device, and signal processing method

Info

Publication number: WO2023020633A1
Application number: PCT/CN2022/125678
Authority: WO
Inventors: 刘坤雄; 张小庆; 刘军成; 段建东
Original assignee: 国网陕西省电力有限公司电力科学研究院; 西安博宇电气有限公司; 西安理工大学
Priority date: 2021-08-18
Filing date: 2022-10-17
Publication date: 2023-02-23
Also published as: CN113671245A

Abstract

A capacitive voltage transformer, a monitoring device (6), and a signal processing method, belonging to the technical field of electrical signal processing. The capacitive voltage transformer comprises: a capacitive voltage divider (1), an electromagnetic unit (2), and a junction box (3). A current transformer(4) and a carrier accessory (5) are provided in the junction box (3). One end of the capacitive voltage divider (1) is used for connecting to a preset AC power supply, and the other end of the capacitive voltage divider (1) is connected to a carrier communication terminal (N). The voltage division connection point of the capacitive voltage divider (1) is connected to a medium voltage terminal (A) on the primary side of the electromagnetic unit (2). The medium voltage terminal (A) on the primary side of the electromagnetic unit is connected to the output end of the carrier accessory (5). The carrier communication terminal (N) is also grounded. The positive input terminal (NI), the common terminal (X) and the negative input terminal (G) of the current transformer (4) are respectively connected to the carrier communication terminal (N), and the low voltage terminal (XL) and the ground terminal of the primary side of the electromagnetic unit (2). The output terminal of the current transformer (4) is used to be connected to the monitoring device (6). By means of using the current transformer (4) to obtain the capacitor current signal, online collection and processing are achieved, errors generated in the collection process are reduced, and collection precision is improved.

Description

Capacitive voltage transformer, monitoring device and signal processing method

Cross References to Related Applications

This application claims the priority of the Chinese patent application with the application number CN202110951413.8 and titled "Digital Interface with Built-in Time Domain Integration Function Time Domain Next Voltage Acquisition Method" submitted to the Chinese Patent Office on August 18, 2021. The entire contents are incorporated by reference in this application.

technical field

The application belongs to the technical field of electrical signal processing, and in particular relates to a capacitive voltage transformer, a monitoring device and a signal processing method.

Background technique

At present, in the high-voltage power grid of 110kV and above, the number of capacitive voltage transformers (CVT) and electromagnetic voltage transformers (IVT) used in the harmonic monitoring and analysis module of the national grid is 2710 and 1155 respectively. It can be seen that CVT It occupies an absolute position in the provision of data sources for power quality monitoring. Therefore, how to use CVT to accurately measure harmonics has become a key issue in the field of power quality measurement, and to achieve the goal of high-quality, low-cost, and high-efficiency online operation, and to be able to monitor its own operation.

For the above problems, there are three commonly used solutions: frequency characteristic correction method, new C3 method and capacitance current method. The frequency characteristic correction method is to correct the secondary voltage according to the frequency characteristic curve. This method can obtain a more accurate primary side voltage, but the disadvantage is that this method cannot realize online monitoring, and is affected by the model of the CVT itself. The amount of experimental data is large. The cycle is long. The newly added C3 capacitor method is to add capacitor C3 to the low-voltage terminal of the capacitor voltage divider. According to the principle of voltage division, the voltage at both ends of the C3 capacitor is obtained, and then the primary side voltage is derived. This method can realize online monitoring, but ignores the influence of the electromagnetic unit on The impact of measurement results, and the need to modify the existing CVT, the cost is relatively high. The capacitive current method is to calculate the voltage by taking the capacitive current flowing through the capacitive voltage divider and combining the capacitance of the capacitor itself. However, in the current calculation voltage method, the capacitor is regarded as an ideal capacitor, and the capacitor in the capacitive voltage divider is in the The ideal capacitance condition is not satisfied during actual operation, and the calculated primary side voltage has low accuracy.

To sum up, the currently commonly used capacitive current monitoring method has the problems of incapability of real-time monitoring, high cost, and neglect of the equivalent resistance of the capacitor. It is difficult to obtain real-time and reliable capacitive current signals, and it is even more difficult to obtain accurate primary side voltage.

application content

The purpose of the present invention is to address the shortcomings of the above-mentioned prior art, and the present application provides a capacitive voltage transformer, a monitoring device and a signal processing method to solve the problem of low accuracy of the primary side voltage calculated in the prior art, etc. question.

In order to achieve the above purpose, the technical solution adopted in the embodiment of the present application is as follows:

In the first aspect, the embodiment of the present application provides a capacitive voltage transformer, which is characterized in that the capacitive voltage transformer includes: a capacitive voltage divider, an electromagnetic unit, and a junction box; the junction box is provided with a current transformer device, carrier accessories; the shell of the junction box is provided with: the carrier communication terminal of the carrier accessory, the low-voltage terminal of the primary side of the electromagnetic unit, the ground terminal, and the output terminal of the current transformer;

One end of the capacitive voltage divider is used to connect to the preset AC power supply, the other end of the capacitive voltage divider is connected to the carrier communication terminal, and the voltage dividing connection point of the capacitive voltage divider is connected to the primary The medium voltage terminal on the primary side of the electromagnetic unit is connected to the output end of the carrier accessory, and the carrier communication terminal is also grounded;

The positive input terminal, the common terminal and the negative input terminal of the current transformer are respectively connected to the carrier communication terminal, the low-voltage terminal on the primary side of the electromagnetic unit and the ground terminal, so as to collect the The capacitive current signal; the output terminal of the current transformer is used to connect the monitoring device;

The casing of the junction box is also provided with: a secondary side connection terminal of the electromagnetic unit to output a voltage signal converted from the electromagnetic voltage.

Optionally, the output terminal of the current transformer is connected to the monitoring device through a transmission line.

Optionally, the carrier accessory includes: a drain coil and a pressure limiting device, the end of the parallel connection of the drain coil and the pressure limiting device is the output end of the carrier accessory, the drain coil and the The other end of the parallel connection of the pressure limiting device is the carrier communication terminal of the carrier accessory.

Optionally, the electromagnetic unit includes: a medium-voltage transformer, a compensating reactor, a protection device, a damping device, and an oil tank;

The compensation reactor and the protection device are connected in parallel between one terminal of the primary winding of the medium voltage transformer and the low voltage terminal of the primary side of the electromagnetic unit, and the other terminal of the primary winding of the medium voltage transformer The terminal is connected to the medium voltage terminal of the primary side of the electromagnetic unit;

The damping device is connected in the secondary winding of the medium voltage transformer, and the medium voltage transformer, the compensating reactor and the damping device are all arranged in the oil tank.

In the second aspect, the embodiment of the present application provides a monitoring device, including: a digital interface, an electric energy monitoring terminal; the digital interface includes: a signal adapter, a signal acquisition board, a time domain integration module, and a communication module; the input of the signal adapter The terminal is the input terminal of the digital interface, which is used to connect the output terminal of the current transformer in the capacitive voltage transformer described in any one of the above first aspects, so as to obtain the capacitive current signal;

The output of the signal adapter is connected to the input of the signal acquisition board to perform adaptation processing on the capacitive current signal; the output of the signal acquisition board is connected to the input of the time domain integration module to process the The current signal after adaptation processing is subjected to analog-digital sampling to obtain a digital capacitive current signal; the output end of the time domain integration module is connected to the communication module, so that the time domain integration module performs the digital capacitive current signal time domain integration to obtain a digital voltage signal; the communication module is connected to the electric energy monitoring terminal so that the digital voltage signal can be analyzed for electric energy.

Optionally, the communication module includes a B code time synchronization port, and the B code time connection port is connected to a clock source or an external signal source to perform signal synchronization processing on the digital voltage signal.

Optionally, the digital interface is arranged under the base of the capacitive voltage transformer.

In the third aspect, the embodiment of the present application provides a signal processing method, which is characterized in that the digital interface in the monitoring device described in any one of the above-mentioned second aspects is applied, and the method includes:

Obtain the capacitive current signal from the current transformer in the capacitive voltage transformer by the signal adapter in the digital interface;

The signal adapter performs adaptive processing on the capacitive current signal and outputs it to the signal acquisition board in the digital interface;

The signal acquisition board performs analog-to-digital sampling on the capacitive current signal after adaptation processing, and outputs the digital capacitive current signal to the time domain integration module in the digital interface;

The time domain integration module performs time domain integration on the digital capacitive current signal to obtain a digital voltage signal, and outputs it to the electric energy monitoring terminal in the monitoring device, and the digital voltage signal is used to represent the capacitive voltage The voltage on the primary side of the transformer;

The electric energy analysis is performed by the electric energy monitoring terminal based on the digital voltage signal.

Optionally, the time-domain integration of the digital capacitive current signal by the time-domain integration module to obtain a digital voltage signal includes:

calculating the primary side voltage value of the capacitive voltage transformer by the time domain integration module according to the capacitance value of the voltage divider in the voltage transformer and the digital capacitive current signal;

The calculated primary-side voltage value is re-sampled by the time domain integration module to obtain the digital voltage signal within a preset time domain period.

Optionally, the capacitance value of the voltage divider includes: a high-voltage capacitance value and a low-voltage capacitance value, and the digital capacitance current signal includes: a high-voltage capacitance current signal and a low-voltage capacitance current signal, and the time-domain integration module According to the capacitance value of the voltage divider in the voltage transformer, and the digital capacitance current signal, calculate the primary side voltage value of the capacitance voltage transformer, including:

The primary side voltage value of the capacitive voltage transformer is calculated by the time domain integration module according to the high voltage capacitance value, the low voltage capacitance value, the high voltage capacitance current signal, and the low voltage capacitance current signal.

Compared with the prior art, the present application has the following beneficial effects:

The application provides a capacitive voltage transformer, a monitoring device and a signal processing method. The capacitive voltage transformer includes: a capacitive voltage divider, an electromagnetic unit, and a junction box; the junction box is provided with a current transformer and a carrier accessory; The shell of the box is provided with: the carrier communication terminal of the carrier accessory, the low-voltage terminal of the primary side of the electromagnetic unit, the grounding terminal and the output terminal of the current transformer; one end of the capacitor voltage divider is used to connect the preset AC power supply, The other end of the transformer is connected to the carrier communication terminal, the voltage dividing connection point of the capacitor voltage divider is connected to the medium voltage terminal on the primary side of the electromagnetic unit, the medium voltage terminal on the primary side of the electromagnetic unit is connected to the output end of the carrier accessory, and the carrier communication terminal is also grounded ; The positive input terminal, the common terminal and the negative input terminal of the current transformer are respectively connected to the carrier communication terminal, the low-voltage terminal and the ground terminal of the primary side of the electromagnetic unit, so as to collect the capacitive current signal in the capacitor voltage divider; The output terminal is used to connect the monitoring device; the outer casing of the junction box is also provided with: a secondary side connection terminal of the electromagnetic unit to output a voltage signal converted from the electromagnetic voltage. Therefore, using the input terminal of the current transformer built in the junction box facilitates the acquisition of the capacitive current signal, saves the transformation cost, realizes the online collection and processing of the capacitive current signal, and makes the operating environment more stable through the current transformer, reducing the collection process. Errors generated in and suitable for on-site operation and measurement.

Description of drawings

In order to illustrate the technical solutions of the embodiments of the present invention more clearly, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention, and thus It should be regarded as a limitation on the scope, and those skilled in the art can also obtain other related drawings based on these drawings without creative work.

Fig. 1 is the schematic diagram of the principle of a kind of capacitive voltage transformer provided by the present application;

Fig. 2 is the structural representation of a kind of capacitive voltage transformer provided by the present application;

Fig. 3 is a structural wiring diagram in a junction box provided by the present application;

FIG. 4 is a schematic structural diagram of a carrier accessory in a capacitive voltage transformer provided by the present application;

5 is a schematic structural diagram of an electromagnetic unit in a capacitive voltage transformer provided by the present application;

6 is a schematic diagram of the principle of a current transformer in a capacitive voltage transformer provided by the present application;

FIG. 7 is a schematic structural diagram of a monitoring device provided by the present application;

Fig. 8 is a schematic structural view of a monitoring device comprising a B code time port provided by the present application;

FIG. 9 is a schematic flowchart of a signal processing method provided by the present application;

FIG. 10 is a schematic flowchart of a method for calculating a digital voltage signal provided by an embodiment of the present application.

Icons: 1-capacitor voltage divider, 2-electromagnetic unit, 3 junction box, 4-current transformer, 5-carrier accessories, 6-monitoring device, N-carrier communication terminal, XL-low voltage terminal, A-medium voltage terminal , C1-high voltage capacitor, C2-low voltage capacitor, NI-positive input terminal, X-common terminal, G-negative input terminal, 51-drain coil, 52-voltage limiting device, T-medium voltage transformer, L-compensation reactance Device, P-protection device, D-damping device, 7-digital interface, 8-power monitoring terminal, 71-signal adapter, 72-signal acquisition board, 73-time domain integration module, 74-communication module.

Detailed ways

In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments It is a part of the embodiments of this application, not all of them. The components of the embodiments of the application generally described and illustrated in the figures herein may be arranged and designed in a variety of different configurations.

Accordingly, the following detailed description of the embodiments of the application provided in the accompanying drawings is not intended to limit the scope of the claimed application, but merely represents selected embodiments of the application. Based on the embodiments in this application, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts belong to the protection scope of this application.

It should be noted that like numerals and letters denote similar items in the following figures, therefore, once an item is defined in one figure, it does not require further definition and explanation in subsequent figures.

In addition, terms such as "first" and "second" are used only for distinguishing descriptions, and should not be understood as indicating or implying relative importance.

It should be noted that, in the case of no conflict, the features in the embodiments of the present invention may be combined with each other.

In order to obtain a reliable capacitor current signal in real time and obtain an accurate primary side voltage. The application provides a capacitive voltage transformer, a monitoring device and a signal processing method.

A capacitive voltage transformer provided by the present application will be explained firstly through a specific example as follows. FIG. 1 is a schematic diagram of the principle of a capacitive voltage transformer provided by the present application, and FIG. 2 is a schematic structural diagram of a capacitive voltage transformer provided by the present application. As shown in FIG. 1 and FIG. 2 , the capacitive voltage transformer includes: a capacitive voltage divider 1 , an electromagnetic unit 2 , and a junction box 3 .

The junction box 3 is provided with a current transformer 4 and a carrier accessory 5; the shell of the junction box 3 is provided with: the carrier communication terminal N of the carrier accessory 5, the low-voltage terminal XL of the primary side of the electromagnetic unit 2, the ground terminal and the current transformer 4 output terminals.

One end of the capacitor voltage divider 1 is used to connect to the preset AC power supply, the other end of the capacitor voltage divider 1 is connected to the carrier communication terminal N, and the voltage dividing connection point of the capacitor voltage divider 1 is connected to the medium voltage terminal on the primary side of the electromagnetic unit 2 A, the medium voltage terminal A on the primary side of the electromagnetic unit 2 is connected to the output end of the carrier accessory 5, and the carrier communication terminal N is also grounded.

Capacitive voltage divider 1 consists of one or several capacitors connected in series. Exemplarily, the capacitive voltage divider 1 includes: a high-voltage capacitor C1 and a low-voltage capacitor C2. The medium of the high-voltage capacitor C1 and the low-voltage capacitor C2 is a composite material of polypropylene film and capacitor paper.

The input end of the high-voltage capacitor C1 serves as one end of the capacitor voltage divider 1 and is connected to the preset AC power supply, and the input end of the high-voltage capacitor C1 can be used as a high-voltage terminal of the capacitor voltage divider 1 for obtaining electrical signals of the preset AC power supply. Exemplarily, the preset AC power source may be a power grid, so that the capacitor voltage transformer is connected to the power grid. The high-voltage capacitor C1 and the low-voltage capacitor C2 are arranged in series, and the connection point between the high-voltage capacitor C1 and the low-voltage capacitor C2 is provided with a voltage-dividing connection point of the capacitor voltage divider 1, and the voltage-dividing connection point of the capacitor voltage divider 1 can be used as a capacitor voltage divider The low-voltage terminal of the device 1 is connected to the medium-voltage terminal A of the primary side of the electromagnetic unit 2. The electrical signal collected through the voltage-dividing connection point only passes through the high-voltage capacitor C1. This electrical signal can be used to further characterize the high-voltage capacitor current signal flowing through the high-voltage capacitor C1, and is transmitted to the medium-voltage terminal A on the primary side of the electromagnetic unit 2. . The output end of the low-voltage capacitor C2 serves as the other end of the capacitor voltage divider 1 and is connected to the carrier communication terminal N. The electrical signal collected through the output terminal of the low-voltage capacitor C2 passes through the low-voltage capacitor C2, and the electrical signal can be used to further characterize the low-voltage capacitor current signal flowing through the low-voltage capacitor C2.

For example, the voltage dividing connection point of the capacitive voltage divider 1 and the other end of the capacitive voltage divider 1 can be drawn out through a small porcelain sleeve on the bottom cover of the capacitive voltage divider 1, and are respectively connected to the corresponding medium voltage terminal A in the electromagnetic unit 2. And the carrier communication terminal N is connected. The electromagnetic unit 2 can be grounded via the grounding bolt.

The carrier accessory 5 injects a carrier signal through the carrier communication terminal N, and adds the carrier signal to the electrical signal received by the medium voltage terminal A on the primary side of the electromagnetic unit 2, so that the electrical signal is more stable.

The positive input terminal NI, the common terminal X and the negative input terminal G of the current transformer 4 are respectively connected to the carrier communication terminal N, the low-voltage terminal XL and the ground terminal of the primary side of the electromagnetic unit 2 to collect the capacitance in the capacitor voltage divider 1 Current signal; the output terminal of the current transformer 4 is used to connect the monitoring device 6 .

The positive input terminal of the current transformer 4 is connected to the carrier communication terminal N, the common terminal X of the current transformer 4 is connected to the low-voltage terminal XL of the primary side of the electromagnetic unit 2, and the negative input terminal G of the current transformer 4 is connected to the ground terminal. The current signal flowing through the primary side of the electromagnetic unit 2 can be obtained through the low-voltage terminal XL on the primary side of the electromagnetic unit 2. The current signal represents the high-voltage capacitor current signal after carrier processing, and the low-voltage capacitor current can be obtained through the carrier communication terminal N. signal electrical signal. Therefore, the current transformer 4 can collect the capacitive current signal in the capacitive voltage divider 1 by connecting the carrier communication terminal N, the low-voltage terminal XL of the primary side of the electromagnetic unit 2, and the ground terminal; and divide the capacitive voltage through the output terminal The capacitive current signal in the device 1 is transmitted to the monitoring device 6.

Using the input terminal of the current transformer 4 built in the junction box 3, without modifying the structure of the capacitive voltage transformer itself, the capacitive voltage transformer itself has the ability to output capacitive current signals, which is convenient for obtaining capacitive current signals. It saves the transformation cost, realizes the online acquisition and processing of the capacitance current signal, and makes the operating environment relatively stable through the current transformer 4, reduces the error generated in the acquisition process, and is suitable for on-site operation and measurement.

The shell of junction box 3 is also provided with: the connection terminal of the secondary side of electromagnetic unit 2 (for example, among Fig. 2:

connection terminal

1a, 1n, 2a, 2n, 3a, 3n, da, dn), to output by The voltage signal after the electromagnetic voltage conversion. The connection terminal is led out through the junction box 3, and outputs a voltage signal converted from the electromagnetic voltage.

Further, the present application also provides a structural wiring diagram in the junction box. Fig. 3 is a structural wiring diagram in a junction box provided by the present application. As shown in FIG. 3 , it shows the specific positional relationship between the connection terminal of the secondary side of the electromagnetic unit 2 and the input end of the current transformer 4 .

In summary, in this embodiment, the capacitive voltage transformer includes: a capacitor voltage divider, an electromagnetic unit, and a junction box; the junction box is provided with a current transformer and a carrier accessory; the outer shell of the junction box is provided with: a carrier accessory The carrier communication terminal of the electromagnetic unit, the low-voltage terminal of the primary side of the electromagnetic unit, the ground terminal and the output terminal of the current transformer; one end of the capacitor voltage divider is used to connect the preset AC power supply, and the other end of the capacitor voltage divider is connected to the carrier communication terminal. The voltage dividing connection point of the capacitor voltage divider is connected to the medium-voltage terminal on the primary side of the electromagnetic unit, and the medium-voltage terminal on the primary side of the electromagnetic unit is connected to the output terminal of the carrier accessory, and the carrier communication terminal N is also grounded; the positive input terminal of the current transformer , the common terminal and the negative input terminal are respectively connected to the carrier communication terminal N, the low-voltage terminal and the ground terminal on the primary side of the electromagnetic unit to collect the capacitive current signal in the capacitor voltage divider; the output terminal of the current transformer is used to connect the monitoring device ; The shell of the junction box is also provided with: the secondary side connection terminal of the electromagnetic unit to output the voltage signal converted from the electromagnetic voltage. Therefore, using the input terminal of the current transformer built in the junction box facilitates the acquisition of the capacitive current signal, saves the transformation cost, realizes the online collection and processing of the capacitive current signal, and makes the operating environment more stable through the current transformer, reducing the collection process. The error generated in the method improves the acquisition accuracy and is suitable for field operation and measurement.

In another embodiment, the output terminal of the current transformer 4 is connected to the monitoring device 6 through a transmission line. For example, the transmission line may be an anti-interference transmission line, and the transmission through the anti-interference transmission line can avoid the influence of electromagnetic interference and obtain accurate capacitive current signals. However, it is not limited here, and the transmission line may also be a transmission line that can realize the transmission task.

On the basis of the above embodiment corresponding to FIG. 1 , the present application further provides a carrier accessory in a capacitive voltage transformer. FIG. 4 is a schematic structural diagram of a carrier accessory in a capacitive voltage transformer provided by the present application. As shown in FIG. 4 , the carrier accessory 5 includes: a drain coil 51 and a pressure limiting device 52 .

One end of the parallel connection of the drain coil 51 and the voltage limiting device 52 is the output end of the carrier accessory 5 , and the other end of the parallel connection of the drain coil 51 and the voltage limiting device 52 is the carrier communication terminal N of the carrier accessory 5 . Receive the carrier signal through the carrier communication terminal N, and inject the carrier signal into the electrical signal received by the medium voltage terminal A on the primary side of the electromagnetic unit 2 through the drain coil 51 and the voltage limiting device 52, so that the electrical signal is more stable.

To sum up, in this embodiment, the carrier accessory includes: a drain coil and a pressure limiting device; one end of the parallel connection of the drain coil and the pressure limiting device is the output end of the carrier accessory, and the other end of the parallel connection of the drain coil and the pressure limiting device One end is the carrier communication terminal of the carrier accessory. Therefore, the electrical signal is more stable.

On the basis of the above embodiment corresponding to FIG. 1 , the present application also provides an electromagnetic unit in a capacitive voltage transformer. FIG. 5 is a schematic structural diagram of an electromagnetic unit in a capacitive voltage transformer provided by the present application. As shown in FIG. 5 , the electromagnetic unit 2 includes: a medium voltage transformer T, a compensating reactor L, a protection device P, a damping device D and an oil tank.

The compensating reactor L and the protector P are connected in parallel between one terminal of the primary winding of the medium voltage transformer T and the low voltage terminal XL on the primary side of the electromagnetic unit 2, and the other terminal of the primary winding of the medium voltage transformer T is connected to the electromagnetic Medium voltage terminal A on the primary side of unit 2.

The damping device D is connected to the secondary winding of the medium voltage transformer T, and the medium voltage transformer T, compensation reactor L and damping device D are all arranged in the oil tank. The oil tank is filled with transformer oil, so that the medium-voltage transformer T, compensating reactor L and damping device D are all immersed in the transformer oil, which plays the role of insulation, heat dissipation, and arc suppression.

As an example, the medium-voltage transformer T adopts a three-column iron core with an outer yoke and an inner iron type. The core is made of high-quality cold-rolled silicon steel sheets. The winding sequence is the core column-auxiliary winding-secondary winding-high voltage winding. The secondary winding of the medium-voltage transformer T has four windings, namely: 1a-1n, 2a-2n, 3a-3n, da-dn, and corresponding terminals: 1a, 1n, 2a, 2n, 3a, 3n, da, dn.

For example, the compensating reactor L adopts a C-shaped iron core. During design, the inductive reactance of the compensating reactor L is equal to the capacitive reactance of the parallel connection of the high-voltage capacitor C1 and the low-voltage capacitor C2 in the capacitive voltage divider 1 . The protection device P may be a zinc oxide valve arrester.

Exemplarily, the damping device D is a fast-saturation damper, which uses a Permalloy iron core and is connected to a residual voltage winding in the secondary winding to suppress ferromagnetic resonance, for example, winding: da-dn.

To sum up, in this embodiment, the electromagnetic unit includes: a medium voltage transformer, a compensation reactor, a protection device, a damping device, and an oil tank; the compensation reactor and the protection device are connected in parallel to one terminal of the primary winding of the medium voltage transformer and the electromagnetic Between the low-voltage terminals on the primary side of the unit, the other terminal of the primary winding of the medium-voltage transformer is connected to the medium-voltage terminal on the primary side of the electromagnetic unit; the damping device is connected to the secondary winding of the medium-voltage transformer, the medium-voltage transformer, the compensation reactance Both the regulator and the damper are set in the oil tank. Therefore, the accuracy of obtaining the current signal can be improved.

On the basis of the above embodiment corresponding to FIG. 1 , the present application also provides the principle of the current transformer in the capacitive voltage transformer. FIG. 6 is a schematic diagram of a current transformer in a capacitive voltage transformer provided in the present application. As shown in Figure 6.

The current transformer 4 adopts a core-through structure, which does not change the original wiring mode of the device under test, and has higher safety in measurement and strong anti-interference ability. The current transformer 4 utilizes the traditional ferromagnetic current transformer principle, including a primary side and two secondary sides, the input port of the primary side is the positive input terminal NI, the common terminal X and the negative input terminal G, and the output port of the secondary side is P1 , P2, P3 and P4. The input port NI-X on the primary side corresponds to the output ports P3-P4 on the secondary side, and the input port X-G on the primary side corresponds to the output ports P1-P2 on the secondary side.

The current transformer 4 senses the current signal of the capacitive voltage transformer in real time, and its secondary side has 4 output ports. Among them, the current flowing through the input port X-G of the primary side is the current of the electromagnetic unit 2, and the corresponding output pin of the secondary side is P1-P2; the current flowing through the input port NI-X of the primary side is the current of the low-voltage capacitor C2, and the corresponding output pins of the secondary side are P3-P4.

For example, under normal circumstances, the current of the high-voltage capacitor C1 and the low-voltage capacitor C2 in the 35kV-750kV CVT is in the range of 60mA-700mA, and the small signal used in the measurement in the project is 1mA, so the primary current of the micro-current transformer is 1000:1 The transformation ratio is transmitted to the secondary side, and the range is 0~1A. The overall size of the built-in current transformer 4 is small, and the appearance size is only 64mm×58mm×35mm (width×height×depth), so it can be completely built into the junction box 3 to replace the original secondary terminal of the capacitive voltage transformer The connection between them not only realizes the function of interconnecting the secondary terminals of the capacitive voltage transformer, but also realizes the function of current measurement.

A monitoring device provided by the present application is explained as follows through a specific example. FIG. 7 is a schematic structural diagram of a monitoring device provided by the present application. As shown in Figure 7, the monitoring device includes: a digital interface 7, a power monitoring terminal 8;

Digital interface 7 comprises: signal adapter 71, signal acquisition board 72, time domain integration module 73 and communication module 74; The input end of signal adapter 71 is the input end of digital interface 7, is used to connect any capacitive type in the above-mentioned embodiment The output terminal of the current transformer 4 in the voltage transformer to obtain the capacitive current signal.

The output of the signal adapter 71 is connected to the input of the signal acquisition board 72 to perform adaptation processing on the capacitive current signal; the output of the signal acquisition board 72 is connected to the input of the time domain integration module 73 to adapt the current The signal is subjected to analog-to-digital sampling to obtain a digital capacitor current signal; the output terminal of the time domain integration module 73 is connected to the communication module 74 so that the time domain integration module 73 performs time domain integration on the digital capacitor current signal to obtain a digital voltage signal; the communication module 74 is connected to the power monitoring terminal 8, so that the monitoring terminal 8 performs power analysis on the digital voltage signal.

The signal adapter 71 adapts the capacitive current signal and inputs it to the signal acquisition board 72 . Signal acquisition board 72 comprises analog-to-digital converter (ADC, Analog-to-Digital Converter) and micro control unit (MCU, Microcontroller Unit), and ADC comprises A/D sampling, hold, coding and quantization link, and signal acquisition board 72 is in MCU Under the control of the signal adapter 71, realize the equal interval modulus sampling of the capacitance current signal input by the signal adapter 71, obtain the sampling pulse, and adjust the sampling frequency of the sampling pulse to make it meet the actual engineering signal sampling requirements, obtain the digital capacitance current signal, and The digital capacitive current signal is transmitted to the time domain integration module 73 . The time domain integration module 73 receives the digital capacitive current signal from the signal acquisition board 72 , and performs time domain integration on the digital capacitive current signal to obtain a digital voltage signal (harmonic voltage signal), and outputs the digital voltage signal to the communication module 74 . The communication module 74 is connected to the electric energy monitoring terminal 8, and the communication module 74 transmits the digital voltage signal to the electric energy monitoring terminal 8, so that the monitoring terminal 8 performs electric energy analysis on the digital voltage signal.

To sum up, in this embodiment, the monitoring device includes: a digital interface, a power monitoring terminal; the digital interface includes: a signal adapter, a signal acquisition board, a time domain integration module and a communication module; the input end of the signal adapter is the input of the digital interface end, for connecting the output terminal of the current transformer in any capacitive voltage transformer in the above-mentioned embodiment, to obtain the capacitive current signal; matching processing; the output end of the signal acquisition board is connected to the input end of the time-domain integration module to perform analog-digital sampling on the current signal after adaptation processing to obtain a digital capacitance current signal; the output end of the time-domain integration module is connected to the communication module , so that the time-domain integration module performs time-domain integration on the digital capacitor current signal to obtain a digital voltage signal; the communication module is connected to the power monitoring terminal, so that the digital voltage signal can be analyzed for power energy. The integrated calculation of capacitor current realizes the integration of first-order harmonic voltage restoration of capacitor voltage transformer, effectively realizes real-time monitoring of grid harmonic voltage, and obtains continuous harmonic voltage waveform in time domain, which is convenient for subsequent voltage deviation, voltage three-phase difference Measurement of power quality indicators such as continuous type such as balance and negative sequence voltage, and event type such as voltage sag and voltage swell. The signal adapter directly collects the capacitive current transmitted by the current transformer in the capacitive voltage transformer, so that the whole measurement link can be connected to the grid; the obtained result is a continuous harmonic voltage waveform, which can realize continuous measurement under time domain conditions; By analyzing the continuous waveform, it can provide a basis for more harmonic index evaluation, and the monitoring device is used in conjunction with the current transformer that collects the capacitive current of the capacitive voltage transformer, and can directly collect and process the analog current signal. Reduce the difficulty of on-site transformation of the actual harmonic voltage detection in the project.

On the basis of the above-mentioned embodiment corresponding to FIG. 7 , the present application also provides a monitoring device including a B-code time synchronization port. FIG. 8 is a schematic structural diagram of a monitoring device including a B-code time synchronization port provided by the present application. As shown in Figure 8: the communication module (4) includes: an optical fiber data transmission interface, a clock calibration interface, and a B code time synchronization port, such as the TRIG-B port in Figure 8.

The communication module 74 includes an optical fiber data transmission interface, and the optical fiber data transmission interface is connected to the electric energy monitoring terminal 8, and transmits the digital voltage signal to the electric energy monitoring terminal 8, and outputs a digital time domain first harmonic voltage signal that meets the IEC61850-9-2 stipulation. This completes the harmonic voltage monitoring, so that the monitoring terminal 8 performs power analysis on the digital voltage signal.

The clock calibration interface is connected to the clock source, and is used for calibration of the output signal clock and the standard signal clock.

The B code timing port is connected to the clock source or an external signal source to perform signal synchronization processing on the digital voltage signal. The signal after synchronous processing can be transmitted to the electric energy monitoring terminal 8 through the optical fiber data transmission interface.

Exemplarily, the external signal source can be the current transformer 4 in any capacitive voltage transformer in the above-mentioned embodiments, and the B code time port is also connected with the signal adapter 71, and the signal adapter 71 is under the synchronization of the B code clock signal , to realize the synchronous adaptation of the analog current signal collected by the current transformer and the signal of the A/D sampling link of the ADC.

Further, the communication module (4) also includes: a clock calibration interface, which is connected to a clock source and used for calibration of the output signal clock and the standard signal clock.

To sum up, in this embodiment, the communication module (4) includes: a B code time synchronization port, and the B code time connection port is connected to a clock source or an external signal source to perform signal synchronization processing on the digital voltage signal. Therefore, the digital voltage signal is more accurate.

On the basis of the above embodiment corresponding to FIG. 7 , the digital interface 7 is arranged under the base of the capacitive voltage transformer to facilitate the collection of electrical signals. For example, the digital interface 7 is fixedly installed on the cement column under the base of the capacitive voltage transformer, and receives the current analog quantity sent by the current transformer 4,

A signal processing method provided by the present application is explained by using specific examples as follows. FIG. 9 is a schematic flowchart of a signal processing method provided by the present application, which applies the digital interface in the monitoring device in the above-mentioned embodiment. As shown in Figure 9, the method includes:

S101. Obtain a capacitive current signal from a current transformer in the capacitive voltage transformer by a signal adapter in the digital interface.

The capacitive current signal characterizes the current signal on the primary side of the voltage transformer.

S102. The signal adapter performs adaptation processing on the capacitive current signal and outputs it to the signal acquisition board in the digital interface.

Adapt the capacitive current signal through the signal adapter, so that the input analog capacitive current signal is adapted to the A/D sampling in the signal acquisition board, and output the adapted analog capacitive current signal to the signal in the digital interface acquisition board.

S103. The signal acquisition board performs analog-digital sampling on the adapted capacitive current signal, obtains a digital capacitive current signal, and outputs it to the time-domain integration module in the digital interface.

The signal acquisition board 2 performs analog-to-digital sampling on the capacitive current signal after adaptation processing to obtain a digital capacitive current, and samples the capacitive current signal input from the signal adapter 1 at equal intervals to obtain a sampling pulse, and performs a sampling frequency on the sampling pulse. Adjustment to make it meet the actual engineering signal sampling requirements, and transmit the digital capacitor current signal to the time domain integration module 3.

S104. Time-domain integration is performed on the digital capacitor current signal by the time-domain integration module to obtain a digital voltage signal, and output to the power monitoring terminal in the monitoring device.

Digital voltage signals are used to characterize the primary voltage in capacitor voltage transformers.

The digital capacitive current signal represents the primary side current in the capacitive voltage transformer, and the time domain integration module performs time domain integration on the digital capacitive current signal to obtain a digital voltage signal, which can also represent the primary side voltage in the capacitive voltage transformer. The obtained digital voltage signal is more accurate, and the digital voltage signal is a continuous harmonic voltage signal in the time domain. And output to the electric energy monitoring terminal in the monitoring device.

S105. The electric energy monitoring terminal performs electric energy analysis based on the digital voltage signal.

The power monitoring terminal performs power analysis based on accurate digital voltage signals. Through the integration of measurement, acquisition and calculation, the intermediate operation links are reduced, the on-site construction is simple, the engineering quantity is small, and manpower and material resources are saved; the output digital voltage signal is a time-domain continuous harmonic voltage signal, which can realize multi-index analysis of power quality.

To sum up, in this embodiment, the signal adapter in the digital interface obtains the capacitive current signal from the current transformer in the capacitive voltage transformer; the signal adapter performs adaptation processing on the capacitive current signal and outputs it to the signal in the digital interface Acquisition board; the signal acquisition board performs analog-digital sampling on the capacitive current signal after adaptation processing, and outputs the digital capacitive current signal to the time domain integration module in the digital interface; the time domain integration module performs time domain integration on the digital capacitive current signal domain integration to obtain a digital voltage signal and output it to the power monitoring terminal in the monitoring device. The digital voltage signal is used to represent the voltage on the primary side of the voltage transformer; the power monitoring terminal performs power analysis based on the digital voltage signal. Therefore, by integrating the measurement, acquisition and calculation links, the intermediate operation links are reduced, the on-site construction is simple, the engineering volume is small, and manpower and material resources are saved; the output digital voltage signal is a continuous harmonic voltage signal in the time domain, which can realize multiple indicators of power quality analyze.

On the basis of the above embodiment corresponding to FIG. 9 , the present application further provides a method for calculating a digital voltage signal. FIG. 10 is a schematic flowchart of a method for calculating a digital voltage signal provided by an embodiment of the present application. As shown in Figure 10, the time-domain integration module in S104 performs time-domain integration on the digital capacitor current signal to obtain a digital voltage signal, including:

S201. The time domain integration module calculates the primary side voltage value of the capacitor voltage transformer according to the capacitance value of the voltage divider in the capacitor voltage transformer and the digital capacitor current signal.

The digital capacitive current signal is the current flowing through the voltage divider in the capacitive voltage transformer. Through the capacitance value of the voltage divider in the capacitive voltage transformer and the digital capacitive current signal, the primary side voltage value of the capacitive voltage transformer can be accurately calculated.

S202. The time-domain integration module performs secondary sampling on the calculated primary-side voltage value to obtain a digital voltage signal within a preset time-domain period.

Considering the monitoring of frequency deviation, voltage deviation, harmonics (inter-harmonics), and unbalance all need to process the entire cycle signal, and the actual grid frequency may fluctuate around 50Hz, resulting in fixed sampling points that may not correspond to The whole cycle signal, so the time domain integration module 3 re-samples the real-time capacitor voltage transformer primary side voltage signal to obtain the full cycle time domain capacitor voltage transformer primary side harmonic voltage signal.

Exemplarily, the sub-sampling may adopt a method of Lagrangian interpolation.

To sum up, in this embodiment, by using the time domain integration module to calculate the primary side voltage value of the capacitor voltage transformer according to the capacitance value of the voltage divider in the capacitor voltage transformer and the digital capacitor current signal, the time domain The domain integration module performs secondary sampling on the calculated primary side voltage value to obtain a digital voltage signal within a preset time domain period. Thus, an accurate full-period time-domain capacitive voltage transformer primary side harmonic voltage signal is obtained.

On the basis of the above embodiment corresponding to FIG. 10 , the present application also provides a method for calculating the primary side voltage value of the capacitive voltage transformer.

The capacitance value of the capacitor voltage transformer includes: high-voltage capacitance value, low-voltage capacitance value, and the digital capacitance current signal includes: high-voltage capacitance current signal, low-voltage capacitance current signal.

Further, the time-domain integration module in S201 calculates the primary-side voltage value of the capacitor voltage transformer according to the capacitance value of the voltage divider in the capacitor voltage transformer and the digital capacitor current signal, including:

The primary voltage value of the capacitive voltage transformer is calculated by the time domain integration module according to the high-voltage capacitance value, the low-voltage capacitance value, the high-voltage capacitance current signal, and the low-voltage capacitance current signal.

The calculation method of the primary side voltage value u _in (t) of the capacitive voltage transformer is shown in the following formula (1):

Among them, C ₁ and C ₂ are the set high-voltage capacitor value and low-voltage capacitor value respectively; u _C1 and u _C2 are the voltages at both ends of the high-voltage capacitor and low-voltage capacitor respectively; i _C1 and i _C2 are the high-voltage capacitor current signal and the low-voltage capacitor current signal respectively. Signal.

To sum up, in this embodiment, the time domain integration module calculates the primary side voltage value of the capacitor voltage transformer according to the high voltage capacitance value, the low voltage capacitance value, the high voltage capacitance current signal, and the low voltage capacitance current signal. Thus, the primary side voltage value of the capacitive voltage transformer is obtained.

In another embodiment, the dielectric loss angle of the capacitor in the capacitor voltage divider can also be obtained through the analysis and calculation of the capacitor current signal, and the equivalent resistance of the capacitor in series can be calculated, and the calculation method of the primary side voltage value can be corrected. The specific calculation method is as follows

The monitoring device 7 includes a current acquisition module, a data processing module and a monitoring module, the current acquisition module is connected to the data processing module, the current acquisition module receives the current signal transmitted by the anti-interference transmission line 6, and the data processing module analyzes and calculates it to obtain the capacitance partial pressure The dielectric loss angle of the capacitor in the device is calculated to obtain the equivalent resistance of the capacitor in series, and the primary side voltage restoration formula is corrected. The monitoring module is connected with the current acquisition module and the data processing module to monitor the data. The corrected results are shown in formulas (2)-(4):

Among them, R _C1 is the equivalent resistance of the high-voltage capacitor, R _C2 is the equivalent resistance of the low-voltage capacitor, δ _C1 is the dielectric loss angle of the high-voltage capacitor C1, δ _C2 is the dielectric loss angle of the low-voltage capacitor, f is the measurement frequency, C ₁ , C ₂ are the set high-voltage capacitor value and low-voltage capacitor value respectively, u _C1 and u _C2 are the voltages across the high-voltage capacitor and low-voltage capacitor respectively, i _C1 and i _C2 are the high-voltage capacitor current signal and the low-voltage capacitor current signal respectively.

In addition, each functional unit in each embodiment of the present invention may be integrated into one processing unit, each unit may exist separately physically, or two or more units may be integrated into one unit. The above-mentioned integrated units can be implemented in the form of hardware, or in the form of hardware plus software functional units.

Industrial Applicability

Claims

A capacitive voltage transformer, characterized in that the capacitive voltage transformer includes: a capacitor voltage divider, an electromagnetic unit, and a junction box; a current transformer and a carrier accessory are arranged in the junction box; the junction box The shell of the carrier is provided with: the carrier communication terminal of the carrier accessory, the low-voltage terminal of the primary side of the electromagnetic unit, the ground terminal, and the output terminal of the current transformer;

One end of the capacitive voltage divider is used to connect to the preset AC power supply, the other end of the capacitive voltage divider is connected to the carrier communication terminal, and the voltage dividing connection point of the capacitive voltage divider is connected to the primary The medium voltage terminal on the primary side of the electromagnetic unit is connected to the output end of the carrier accessory, and the carrier communication terminal is also grounded;

The positive input terminal, the common terminal and the negative input terminal of the current transformer are respectively connected to the carrier communication terminal, the low-voltage terminal on the primary side of the electromagnetic unit and the ground terminal, so as to collect the The capacitive current signal; the output terminal of the current transformer is used to connect the monitoring device;

The casing of the junction box is also provided with: a secondary side connection terminal of the electromagnetic unit to output a voltage signal converted from the electromagnetic voltage.
The capacitive voltage transformer according to claim 1, wherein the output terminal of the current transformer is connected to the monitoring device through a transmission line.
The capacitive voltage transformer according to claim 1, wherein the carrier accessory includes: a drain coil and a voltage limiting device, and one end of the parallel connection of the drain coil and the voltage limiting device is the carrier The output end of the accessory, the other end after the parallel connection of the drain coil and the pressure limiting device is the carrier communication terminal of the carrier accessory.
The capacitive voltage transformer according to claim 1, wherein the electromagnetic unit comprises: a medium voltage transformer, a compensating reactor, a protection device, a damping device, and an oil tank;

The compensation reactor and the protection device are connected in parallel between one terminal of the primary winding of the medium voltage transformer and the low voltage terminal of the primary side of the electromagnetic unit, and the other terminal of the primary winding of the medium voltage transformer The terminal is connected to the medium voltage terminal of the primary side of the electromagnetic unit;

The damping device is connected in the secondary winding of the medium voltage transformer, and the medium voltage transformer, the compensating reactor and the damping device are all arranged in the oil tank.
A monitoring device, characterized in that it includes: a digital interface, an electric energy monitoring terminal; the digital interface includes: a signal adapter, a signal acquisition board, a time domain integration module and a communication module; the input end of the signal adapter is the digital The input end of the interface is used to connect the output terminal of the current transformer in the capacitive voltage transformer described in any one of the above claims 1-4, so as to obtain the capacitive current signal;

The output of the signal adapter is connected to the input of the signal acquisition board to perform adaptation processing on the capacitive current signal; the output of the signal acquisition board is connected to the input of the time domain integration module to process the The current signal after adaptation processing is subjected to analog-digital sampling to obtain a digital capacitive current signal; the output end of the time domain integration module is connected to the communication module, so that the time domain integration module performs the digital capacitive current signal Time-domain integration to obtain a digital voltage signal; the communication module is connected to the electric energy monitoring terminal, so that the electric energy monitoring terminal performs electric energy analysis on the digital voltage signal.
The monitoring device according to claim 5, wherein the communication module comprises: an optical fiber data transmission interface, a clock calibration interface, and a B code time synchronization port;

The optical fiber data transmission interface is connected to the power monitoring terminal, so that the power monitoring terminal performs power analysis on the digital voltage signal;

The clock calibration interface is connected to a clock source for calibration of the output signal clock and the standard signal clock;

The B code timing port is connected to the clock source or an external signal source to perform signal synchronization processing on the digital voltage signal.
The monitoring device according to claim 5, wherein the digital interface is arranged under the base of the capacitive voltage transformer.
A signal processing method, characterized in that the digital interface in the monitoring device according to any one of claims 5-7 is applied, the method comprising:

Obtain the capacitive current signal from the current transformer in the capacitive voltage transformer by the signal adapter in the digital interface;

The signal adapter performs adaptive processing on the capacitive current signal and outputs it to the signal acquisition board in the digital interface;

The signal acquisition board performs analog-to-digital sampling on the capacitive current signal after adaptation processing, and outputs the digital capacitive current signal to the time domain integration module in the digital interface;

The time domain integration module performs time domain integration on the digital capacitive current signal to obtain a digital voltage signal, and outputs it to the electric energy monitoring terminal in the monitoring device, and the digital voltage signal is used to represent the capacitive voltage The voltage on the primary side of the transformer;

The electric energy analysis is performed by the electric energy monitoring terminal based on the digital voltage signal.
The method according to claim 8, wherein said time domain integration of said digital capacitive current signal by said time domain integration module to obtain a digital voltage signal comprises:

calculating the primary side voltage value of the capacitive voltage transformer by the time domain integration module according to the capacitance value of the voltage divider in the voltage transformer and the digital capacitive current signal;

The calculated primary-side voltage value is re-sampled by the time domain integration module to obtain the digital voltage signal within a preset time domain period.
The method according to claim 9, wherein the capacitance value of the voltage divider comprises: a high voltage capacitance value and a low voltage capacitance value, and the digital capacitance current signal comprises: a high voltage capacitance current signal, a low voltage capacitance current signal, The calculation of the primary side voltage value of the capacitive voltage transformer by the time domain integration module according to the capacitance value of the voltage divider in the voltage transformer and the digital capacitive current signal includes:

The primary side voltage value of the capacitive voltage transformer is calculated by the time domain integration module according to the high voltage capacitance value, the low voltage capacitance value, the high voltage capacitance current signal, and the low voltage capacitance current signal.