Digital interface with built-in time domain integration function and time domain next-time voltage acquisition method

文档序号:1859918 发布日期:2021-11-19 浏览:4次 中文

阅读说明:本技术 内置时域积分功能的数字接口及时域下一次电压采集方法 (Digital interface with built-in time domain integration function and time domain next-time voltage acquisition method ) 是由 张小庆 刘军成 刘坤雄 段建东 李丰仪 锁军 赵铭 于 2021-08-18 设计创作,主要内容包括:本发明公开了一种内置时域积分功能的数字接口及时域下一次电压采集方法,数字接口主要包括由信号适配器、信号采集板、时域积分模块及I/O口;其连接结构为:信号适配器与信号采集板适配;信号采集板采集的数据传输至时域积分模块;时域积分模块与I/O口连接输出电压信号。本发明主要解决目前利用CVT测量谐波电压多采用的频域下只能进行谐波电压测量,不具备电压偏差、电压三相不平衡、负序电压等连续型和电压暂降、电压暂升等事件型等电能质量指标的测量,结果分析空间小,且检测系统现场改造难度高的问题。(The invention discloses a digital interface with a built-in time domain integration function and a time domain next voltage acquisition method, wherein the digital interface mainly comprises a signal adapter, a signal acquisition board, a time domain integration module and an I/O port; the connection structure is as follows: the signal adapter is matched with the signal acquisition board; the data collected by the signal collecting board is transmitted to the time domain integration module; and the time domain integration module is connected with the I/O port to output a voltage signal. The invention mainly solves the problems that at present, the harmonic voltage is measured by using the CVT mostly in a frequency domain, only harmonic voltage measurement can be carried out, continuous types such as voltage deviation, voltage three-phase unbalance and negative sequence voltage and event types such as voltage sag and the like are not provided for measuring electric energy quality indexes, the analysis space of results is small, and the field reconstruction difficulty of a detection system is high.)

1. A digital interface with a built-in time domain integration function is characterized by comprising a signal adapter (1), a signal acquisition board (2), a time domain integration module (3) and an I/O port (4); the signal adapter (1) is matched with the signal acquisition board (2), and the output end of the signal acquisition board (2) is connected with the input end of the time domain integration module (3); the output end of the time domain integration module (3) is connected with the I/O port (4) and outputs a voltage signal;

the signal adapter (1) is used for realizing the adaptation of an input signal and an A/D sampling link; the signal sampling plate (2) is used for sampling the input current signal of the signal adapter (1) to obtain a sampling pulse, and adjusting the sampling frequency of the sampling pulse to enable the sampling pulse to meet the actual engineering signal sampling requirement; and the time domain integration module (3) receives the sampling signal from the signal acquisition board (2), performs time domain integration on the sampling signal to obtain a voltage signal, and outputs the voltage signal to the I/O port (4).

2. The digital interface with built-in time domain integration function according to claim 1, wherein the I/O port (4) comprises an optical fiber data transmission interface, and the optical fiber data transmission interface is connected with an external digital electric energy quality analysis device to realize voltage monitoring.

3. The digital interface with built-in time domain integration function of claim 1, wherein the I/O port (4) comprises a clock calibration interface, and the clock calibration interface is connected with a clock source and used for calibrating the output signal clock with a standard signal clock.

4. The digital interface with built-in time domain integration function according to claim 1, wherein the I/O port (4) comprises a B-code pair port, and the B-code pair port is connected with a clock source or an external signal source for signal synchronization.

5. The digital interface with built-in time domain integration function according to claim 1, wherein the collection unit is installed below a base of a capacitor voltage transformer.

6. A time domain next voltage acquisition method based on the digital interface of claim 1, comprising the steps of:

s1, collecting an analog capacitance current signal from a primary side of a CVT (constant voltage transformer) in a net hanging operation to a signal adapter (1);

s2, the signal adapter (1) adapts the input analog capacitance current signal to A/D sampling, the signal acquisition board (2) converts the analog capacitance current signal sampled at one time into a digital signal to obtain a digital capacitance current, and the digital capacitance current is sent to the time domain integration module (3);

s3, the time domain integration module (3) calculates CVT primary side voltage according to the received digital capacitance current and in combination with the capacitance value of the CVT capacitor;

s4, transmitting the primary side voltage to the I/O port (4), and transmitting the voltage waveform to the power quality terminal through the I/O port (4) according to a communication protocol.

7. The time-domain next voltage acquisition method according to claim 6, wherein before step S4, the real-time CVT primary voltage is sub-sampled to obtain a full-period time-domain CVT primary voltage signal.

8. The time domain next voltage acquisition method according to claim 7, wherein the secondary sampling is performed by a Lagrangian interpolation method.

9. The time-domain next-time voltage acquisition method according to claim 6, wherein the primary-side voltage of the CVT is calculated by the formula:

wherein u isin(t) is the primary side voltage of CVT, C1、C2The capacitance values of the set CVT high-voltage capacitor and the set low-voltage capacitor uC1、uC2The voltages across the high-voltage capacitor and the low-voltage capacitor, iC1、iC2The capacitance currents flowing through the high-voltage capacitor and the low-voltage capacitor are respectively.

Technical Field

The invention belongs to the technical field of signal timely processing, and particularly relates to a digital interface with a built-in time domain integration function and a time domain next voltage acquisition method.

Background

In recent years, the construction of extra-high voltage direct current and flexible power transmission projects is accelerated, the number of interference sources of electrified railways, smelting, new energy, urban rail transit and the like is increased, the non-linear load permeability in a power grid is increased year by year, the problems of electric energy quality such as harmonic waves and the like in a public power grid are increasingly highlighted, great threat is caused to the normal operation of various sensitive devices in the power grid based on the power frequency design, and the operation cost of the devices and the power grid is greatly increased. In recent years, the harmonic voltage problem in the power system presents new characteristics and new requirements which are different from those recognized by the traditional technology, so that the improvement of the monitoring capability of the power grid harmonic is urgently needed.

When a Capacitive Voltage Transformer (CVT) which is widely applied to a high-Voltage grade field at present measures harmonic signals, a working point of a power frequency series resonance loop consisting of an equivalent Capacitor of a capacitive Voltage divider and an inductance of a compensation reactor deviates, amplitude-frequency and phase-frequency characteristics of a transformation ratio present serious nonlinearity, and transmission of harmonic waves has serious distortion, so that the national standard GB/T14549 and 1993 'electric energy quality public power grid harmonic wave' clearly indicates that the Capacitive Voltage Transformer (CVT) cannot be used for harmonic wave measurement. Various classical harmonic voltage measurement methods based on CVT have certain problems in the aspects of accuracy and economy, and accurate measurement of harmonic voltage cannot be realized. At present, most of CVT harmonic voltage measurement and calculation methods are realized under the condition of frequency domains, the final obtained result is a harmonic voltage value under each frequency domain, harmonic voltage measurement can only be carried out under the frequency domains, and the measurement method can not provide a basis for measuring electric energy quality indexes such as voltage deviation, voltage three-phase imbalance, negative sequence voltage and the like continuous types, voltage sag and the like event types, and the like, and the problem of high difficulty in field modification of the existing measurement system is also to be solved.

In summary, the analysis space of the CVT harmonic measurement result in the current frequency domain is small, the detection system is not suitable for field experiments, the field transformation difficulty is high, and the improved space is provided.

Disclosure of Invention

The invention mainly solves the problems that the harmonic voltage measured by using the CVT can only be measured in a frequency domain, the measured result is the voltage amplitude and the phase angle of each harmonic, and compared with the continuous voltage waveform in a time domain, the measurement of the electric energy quality indexes such as the continuous type of subsequent voltage deviation, frequency deviation, voltage fluctuation and flicker, three-phase voltage unbalance and the like, the event type of voltage sag, short-time interruption and the like is not facilitated, the result analysis space is small, and the field modification difficulty of a detection system is high.

In order to achieve the above object, the digital interface with built-in time domain integration function of the present invention comprises a signal adapter, a signal acquisition board, a time domain integration module and an I/O port; the signal adapter is matched with the signal acquisition board, and the output end of the signal acquisition board is connected with the input end of the time domain integration module; the output end of the time domain integration module is connected with the I/O port and outputs a voltage signal; the signal adapter is used for realizing the adaptation of an input signal and an A/D sampling link; the signal sampling plate is used for sampling the input current signal of the signal adapter to obtain a sampling pulse, and adjusting the sampling frequency of the sampling pulse to enable the sampling pulse to meet the sampling requirement of an actual engineering signal; and the time domain integration module receives the sampling signal from the signal acquisition board, performs time domain integration on the sampling signal to obtain a voltage signal, and outputs the voltage signal to the I/O port.

Furthermore, the I/O port comprises an optical fiber data transmission interface, and the optical fiber data transmission interface is connected with an external digital power quality analysis device to realize voltage monitoring.

Furthermore, the I/O port includes a clock calibration interface, and the clock calibration interface is connected to the clock source and is used for calibrating the output signal clock and the standard signal clock.

Furthermore, the I/O port comprises a B code time-setting port, and the B code time-setting port is connected with a clock source or an external signal source and used for signal synchronization.

Furthermore, the acquisition unit is arranged below the base of the capacitor voltage transformer.

A time domain next voltage acquisition method based on the digital interface comprises the following steps:

s1, collecting analog capacitance current signals from the primary side of the CVT running in the net hanging mode to a signal adapter;

s2, the signal adapter realizes the adaptation of the input analog capacitance current signal and the A/D sampling, the signal acquisition board converts the analog capacitance current signal of the primary sampling into a digital signal to obtain a digital capacitance current, and the digital capacitance current is sent to the time domain integration module;

s3, the time domain integration module calculates CVT primary side voltage according to the received digital capacitance current and in combination with the capacitance value of the CVT capacitor;

s4, transmitting the primary side voltage to the I/O port, and transmitting the voltage waveform to the power quality terminal through the I/O port according to a communication protocol.

Further, before step S4, the real-time CVT primary voltage is subsampled to obtain a full-period time-domain CVT primary voltage signal.

Further, a Lagrange interpolation method is adopted for secondary sampling.

Further, the primary side voltage of the CVT is calculated as:

wherein u isin(t) is the primary side voltage of CVT, C1、C2The capacitance values of the set CVT high-voltage capacitor and the set low-voltage capacitor uC1、uC2The voltages across the high-voltage capacitor and the low-voltage capacitor, iC1、iC2The capacitance currents flowing through the high-voltage capacitor and the low-voltage capacitor are respectively.

Compared with the prior art, the invention has at least the following beneficial technical effects:

(1) the signal acquisition unit, the analog-to-digital conversion module, the time domain integrator and the voltage signal processing and analyzing module are combined in a unified manner, the capacitance current integral calculation is realized to realize the primary side voltage reduction integration of the CVT, the real-time monitoring of the power grid voltage is effectively realized, the continuous primary voltage waveform in the time domain is obtained, and the measurement of the following continuous types of voltage deviation, frequency deviation, voltage fluctuation and flicker, three-phase voltage unbalance and the like and the measurement of the electric energy quality indexes of event types such as voltage sag, short-time interruption and the like are facilitated.

(2) The signal adapter directly collects the capacitance current transmitted by the current transformer, outputs a digital time domain primary voltage signal meeting the IEC61850-9-2 protocol, and transmits the voltage signal to the power quality terminal, and the whole measurement link can realize the operation of hanging a network.

(3) Compared with the conventional common harmonic voltage measurement technology, the method provided by the invention has the advantages that the obtained result is a continuous primary voltage waveform, and continuous measurement under a time domain condition can be realized; the continuous waveform is analyzed, so that a foundation can be provided for more harmonic index evaluations, and the integrated micro-current transformer can be used in cooperation with an integrated micro-current transformer for collecting capacitance current of a CVT (constant voltage transformer), so that analog current signals can be directly collected and processed, and the field reconstruction difficulty of harmonic voltage detection in engineering practice is reduced.

(4) According to the invention, the analog current signal of the primary side capacitor of the CVT is directly collected as the input signal, the input signal and the output time domain primary side continuous voltage signal are not influenced by the structure of the internal electromagnetic unit of the CVT, and the accuracy of the measurement result is higher. The output time domain lower primary side continuous voltage signal is analyzed by an external power quality analyzer, and results such as a harmonic voltage value, a phase angle, a distortion rate and the like can be obtained.

Drawings

FIG. 1 is a schematic diagram of the operation of a digital interface incorporating time domain integration of the present invention;

FIG. 2 is a schematic diagram of the digital interface structure including the time domain integration function according to the present invention;

fig. 3 is a flow chart of the operation of the digital interface including the time domain integration function according to the present invention.

In the drawings: 1-a signal adapter; 2-a signal acquisition board; 3-a time domain integration module; 4-I/O port.

Detailed Description

In order to make the objects and technical solutions of the present invention clearer and easier to understand. The present invention will be described in further detail with reference to the following drawings and examples, wherein the specific examples are provided for illustrative purposes only and are not intended to limit the present invention.

In the description of the present invention, it is to be understood that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", and the like, indicate orientations or positional relationships based on those shown in the drawings, and are used only for convenience in describing the present invention and for simplicity in description, and do not indicate or imply that the referenced devices or elements must have a particular orientation, be constructed and operated in a particular orientation, and thus, are not to be construed as limiting the present invention. Furthermore, the terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of the present invention, "a plurality" means two or more unless otherwise specified. In the description of the present invention, it should be noted that, unless otherwise explicitly specified or limited, the terms "mounted," "connected," and "connected" are to be construed broadly, e.g., as meaning either a fixed connection, a removable connection, or an integral connection; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meanings of the above terms in the present invention can be understood in specific cases to those skilled in the art.

Referring to fig. 2, a digital interface with a built-in time domain integration function is composed of a signal adapter 1, a signal acquisition board 2, a time domain integration module 3 and an I/O port 4. The connection structure is as follows: the signal adapter 1 is matched with the signal acquisition board 2; the output end of the signal acquisition board 2 is connected with the input end of the time domain integration module 3; the output end of the time domain integration module 3 is connected with the I/O port 4 and outputs a voltage signal;

under the synchronous action of IRIG-B (B code) clock signals, the signal adapter 1 realizes synchronous adaptation of analog current signals acquired by the micro-current transformer and signals of an A/D sampling link of an analog-digital converter (ADC); the signal sampling plate 2 comprises an analog-digital converter ADC and a micro control unit MCU, the analog-digital converter ADC comprises A/D sampling, holding, coding and quantizing links, the signal sampling plate 2 realizes equal-interval sampling of the input current signal of the signal adapter 1 under the control of the micro control unit MCU to obtain sampling pulses, and the sampling frequency of the sampling pulses is adjusted to meet the sampling requirements of actual engineering signals; the time domain integration module 3 receives the sampling signal from the signal acquisition board 2, performs time domain integration on the sampling signal to obtain a continuous voltage signal, and outputs the voltage signal to the I/O port 4; the I/O port 4 mainly comprises a clock calibration interface, a B code time-setting port and an optical fiber data transmission interface, and the optical fiber data transmission interface is connected with an external digital power quality analysis device, so that harmonic voltage monitoring is completed. The clock calibration interface is connected with the clock source and used for calibrating the output signal clock and the standard signal clock; the B code time pair port is connected with a clock source or an external signal source and used for signal synchronization;

the digital interface is fixedly arranged on a cement upright post below a base of a capacitor voltage transformer CVT, receives current analog quantity sent by an integrated micro-current sensor, converts analog capacitance current into digital quantity, performs time domain integration on digital capacitance current signals, reduces primary voltage digital signals of a power grid, and outputs the primary voltage digital signals in an IEC61850-9-2 message format; and the digital signal uploads the data to the digital power quality on-line monitoring terminal through the optical fiber.

The time domain integration module output voltage is calculated by equation (1),

wherein C is1、C2Respectively a set CVT high-voltage capacitance value, a set low-voltage capacitance value uC1、uC2Voltage i across the high-voltage capacitor and the low-voltage capacitor of the CVTC1、iC2The capacitor currents respectively flow through the high-voltage capacitor and the low-voltage capacitor of the CVT. The signal sampling plate samples the current, the time domain integrator integrates the current in the time interval after the digital signal of the capacitance current is obtained, voltage values at two ends of a CVT high-voltage capacitor and a low-voltage capacitor are obtained, and the voltage values at the primary side of the CVT are added and reduced. Taking the voltage flicker in the power quality index as an example, according to the obtained primary side voltage value of the CVT in the time domain, the instantaneous flicker visual sensitivity in the observation period can be calculated, and the grid voltage flicker can be evaluated according to the calculated value.

The invention is described in further detail below with reference to the figures and the embodiments, which are only for illustrative purposes, and the scope of the invention is subject to the scope of the claims.

Referring to fig. 1 and 2, the digital interface with the built-in time domain integration function of the present invention is specifically a CVT integrated digital interface based on CVT capacitance current measurement and time domain integration primary side voltage reduction, and is composed of a signal adapter 1, a signal acquisition board 2, a time domain integration module 3, and an I/O port 4, so as to realize measurement, calculation and reduction of the CVT primary side voltage time domain signal. The signal adapter 1 is used for adapting an input signal to A/D sampling, and the signal acquisition board 2 is used for converting a current analog signal acquired by an AD sampling link into a digital signal.

The time domain integration module 3 is configured to integrate the collected current signal to obtain a primary side voltage waveform of the CVT in the period:

wherein C is1、C2The capacitance values of the set CVT high-voltage capacitor and the set low-voltage capacitor uC1、uC2The voltages across the high-voltage capacitor and the low-voltage capacitor, iC1、iC2The capacitance currents flowing through the high-voltage capacitor and the low-voltage capacitor are respectively. Considering that the monitoring of frequency deviation, voltage deviation, harmonic (inter-harmonic) and unbalance all need to process the whole periodic signal, the real-time voltage signal is subjected to secondary sampling by an interpolation method.

Referring to fig. 3, the time domain next voltage acquisition method includes the following steps:

(1) referring to fig. 1 and 2, the digital interface is installed as shown in fig. 1: analog capacitance current signals are collected from a primary side of a CVT (constant voltage transformer) running in a net hanging mode to a signal adapter, and digital primary voltage signals are output to an external digital power quality terminal through an I/O (input/output) port 4.

(2) The signal adapter 1 realizes the adaptation of an input analog capacitance current signal and A/D sampling, and the signal acquisition board 2 completes the conversion from the analog capacitance current signal of one-time sampling to a digital signal to obtain a digital capacitance current and sends the digital capacitance current to the time domain integration module 3.

(3) The time domain integration module 3 calculates the primary side voltage u of the CVT according to the following formula by combining the capacitance value of the CVT capacitor according to the digital capacitance current sent by the signal acquisition board 2in(t):

Wherein C is1、C2The capacitance values of the set CVT high-voltage capacitor and the set low-voltage capacitor uC1、uC2The voltages across the high-voltage capacitor and the low-voltage capacitor, iC1、iC2The capacitance currents flowing through the high-voltage capacitor and the low-voltage capacitor are respectively.

(4) Considering that the frequency deviation, the voltage deviation, the harmonic (inter-harmonic) and the unbalance monitoring need to process the whole-period signal, and the actual power grid frequency may fluctuate around 50Hz, so that the fixed sampling point number may not correspond to the whole-period signal, the time domain integration module 3 performs secondary sampling on the real-time CVT primary side voltage signal to obtain the whole-period time domain CVT primary side voltage signal. The secondary sampling adopts a Lagrange interpolation method.

(5) The time domain integration module integrates the obtained whole-period time domain CVT primary side voltage signal uinAnd (t) transmitting the voltage waveform to an I/O port 4, and transmitting the voltage waveform to an external power quality terminal by the I/O port 4 according to an IEC61850 communication protocol.

Theory of operation analysis

The invention is composed of a signal adapter 1, a signal acquisition board 2, a time domain integration module 3 and an I/O port 4. The signal adapter 1 realizes the adaptation of input signals and A/D sampling, the signal acquisition board completes the conversion from current analog signals to digital signals, the time domain integration module calculates and reduces CVT primary side voltage by using a time domain integration method according to capacitance current received by the signal acquisition board and in combination with the capacitance value of a CVT capacitor, so as to obtain continuous voltage waveform signals in a time domain, and performs secondary sampling on the signals. And finally, the voltage waveform is transmitted to an external power quality terminal through an I/O (input/output) port according to an IEC61850 communication protocol. The invention integrates the measuring, collecting and calculating links, reduces the intermediate operation links, has simple site construction and small engineering quantity, and saves manpower and material resources. The voltage signal output by the invention is a time domain continuous voltage signal, and the multi-index analysis of the power quality can be realized.

The above-mentioned contents are only for illustrating the technical idea of the present invention, and the protection scope of the present invention is not limited thereby, and any modification made on the basis of the technical idea of the present invention falls within the protection scope of the claims of the present invention.

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