CN110299932B - On-line identification method of power distribution network and equipment operating status based on power line signal - Google Patents

Abstract

The present invention provides an on-line identification method for power distribution network and equipment operation status based on power line signals, comprising: installing power line carrier communication equipment at the positions of distribution network transformers and power distribution switches, and a background master station system coordinates the power line carrier equipment to establish a communication connection, The power line carrier communication equipment measures the high frequency impedance of the installation location, the power line carrier communication equipment measures the signal noise of the installation location, the power line carrier communication equipment uploads the characteristic information of the background master station system, and the background master station system identifies equipment and network faults. The invention identifies the distribution network and equipment status based on the high-frequency impedance and signal noise analysis of power line communication. Compared with the prior art, the system mining improves the implicit rich information of the power line signal, which is an advanced informatization and intelligent power distribution network. Provide new technical support means for the development of chemical technology.

Description

On-line identification method of power distribution network and equipment operating status based on power line signal

technical field

The invention belongs to the technical field of electric power, relates to power distribution network fault detection, and is an on-line identification method of power distribution network and equipment operation state based on power line signals.

Background technique

The cables are mainly buried underground, which does not affect the appearance and avoids various interferences from the external environment. It is gradually replacing the original overhead lines and is widely used in distribution network reconstruction and construction projects. The probability of failure increases with the increase of cable usage time. The reasons for failure include cable manufacturing process level, external force damage, and deterioration caused by operation. The operating environment of the cable is hidden, which makes it difficult to observe the fault directly. If the early warning cannot be better and eliminated in time, it will have a potentially significant impact on the reliability of the power supply of the distribution network.

Chinese patent application "Fault Locating Device for Distribution Network Line Condition Monitoring, Fault Early Warning and Location Technology Based on Distributed Phasor Measurement", CN201721158291.2, relates to a distribution network line condition monitoring and fault early warning based on distributed phasor measurement And the fault location device of location technology, which includes a current monitoring unit, a voltage monitoring unit, a collection unit and a master station; during normal operation, the voltage and current monitoring unit will collect the load voltage and current fixed-point data of the line every 15min. Collecting unit, the collecting unit analyzes and processes and uploads it to the master station, and displays the line status of the distribution network line intuitively in the master station through interface display methods such as graphs, curves, and tables. The utility model has the advantages of low cost, high cost performance, convenient live installation, and maintenance-free; the current and voltage waveforms of each monitoring point can be recorded; This application is mainly implemented by distributed phasor measurement units, and does not involve the high-frequency impedance measurement and power line communication noise measurement proposed in this application.

The Chinese patent "Distribution Network Cable Operation Status Monitoring and Fault Recording Diagnosis Device", ZL201520098241.4, discloses a distribution network cable operation status monitoring and fault recording diagnosis device, which has a coil box, a processing part and a connecting part. The coil box is used for accommodating the Rogowski coil, the processing part is used for accommodating the signal processing device, and the connecting part accommodates the connecting wire, wherein the coil box can be divided into two halves, so as to be sheathed on the cable to be tested, and the Rogowski coil housed in the coil box The coil can also be divided into corresponding halves, the two parts of the Rogowski coil are connected from the outside with a flexible wire, the connecting flexible wire is accommodated in the connecting part, and the lead wire from the part of the Rogowski coil accommodated in the coil box with the processing part is connected to the Corresponding signal processing devices in the processing section. The utility model mainly realizes the diagnosis through the fault recording device offline, and does not involve the high-frequency impedance measurement and the power line communication noise measurement proposed in the present application.

Chinese patent application "Condition Monitoring System for Ring Main Unit of Intelligent Distribution Network", CN201310165573.5, relates to a condition monitoring system for ring main unit of intelligent distribution network, including a data acquisition, analysis and processing unit, a Closing current sensor, opening and closing voltage sensor, operating pressure sensor, travel sensor, vibration sensor, temperature sensor, partial discharge sensor, among which the data acquisition and analysis processing unit is connected to the opening and closing current sensor, the opening and closing voltage sensor, the operating pressure Sensors, travel sensors, vibration sensors, temperature sensors, partial discharge sensors. The present invention proposes a unified platform for the online monitoring system of switchgear in distribution network, through which the on-line monitoring device collects the opening and closing current, operating voltage, operating pressure, joint temperature, contact travel, and partial discharge of the access switch to realize matching. The online monitoring and global analysis of the overall situation of the power grid switch enables it to provide an online monitoring system for power distribution network switches with unified data, unified interface, unified deployment, and effective data exchange. However, this application mainly realizes monitoring through a variety of sensors, and does not involve the high-frequency impedance measurement and power line communication noise measurement proposed in this patent.

None of the above-mentioned documents involve high-frequency impedance measurement and power line communication noise measurement, and none of the prior art considers identifying the operating state of the power distribution network through high-frequency impedance and power line communication noise.

SUMMARY OF THE INVENTION

The purpose of the present invention is: there are many power distribution equipments in the power distribution network and few fault monitoring means. At present, mainly external sensors and data transmission methods based on wireless communication are used. The economic cost of monitoring is low, and external sensors, including temperature sensors, humidity sensors, conventional Voltage transformers, current transformers, etc., to reflect equipment fault information. However, the distribution network network faults, including grounding, short circuit, disconnection, etc., and equipment faults, including the abnormality of main equipment such as transformers and switches, require new monitoring technical means. The present invention proposes a high-frequency impedance measurement based on power line carrier equipment. A method for identifying faults in distribution networks and equipment that combines various high-frequency noise measurements.

The technical scheme of the invention is: an on-line identification method of power distribution network and equipment operation state based on power line signal, power line carrier communication equipment is installed at the position of distribution network transformer and power distribution switch, and the background master station system coordinates the establishment of communication between the power line carrier equipment Connect, the power line carrier communicates with the communication equipment to measure the high-frequency impedance and signal noise at the installation location, and upload the measured high-frequency impedance characteristic information and noise characteristic information to the background master station system, and the background master station system identifies the equipment and network according to the characteristic information. In the event of a fault, the background main master station system stores the high-frequency impedance and noise information measured by each carrier device, analyzes the time-varying characteristics of high-frequency impedance and noise characteristic information, and the correlation of characteristic information between adjacent nodes, and judges the distribution network network. and equipment operating status.

Install power line carrier communication equipment at the transformer and distribution switch positions of the distribution network. The carrier communication equipment installed at the distribution transformer is connected to a total of 7 carrier signal coupling devices with three-phase and four-wire on the high-voltage side of the transformer and three-phase four-wire on the low-voltage side. The carrier communication equipment installed at the switch is respectively connected to the three-phase incoming line and the three-phase outgoing line of the switch, a total of six carrier signal coupling devices.

The background master station system coordinates the power line carrier communication to establish a communication connection, and the background master station system manages the power line carrier communication network, which is used for remote configuration of equipment and network networking settings, and monitoring equipment operation status, and coordinates the power line carrier communication equipment through the background system. Establish a communication connection.

The measurement of the high-frequency impedance of the installation location refers to the impedance of the discrete frequency points configured in the range of 30kHz-100MHz scanned by the power line carrier communication device.

The measurement of the signal noise at the installation location means that the power line carrier communication equipment analyzes the noise frequency band of the installation location, analyzes and identifies the operating status of the equipment in the distribution network, and uploads the analysis results to the background master station system. Analyze the noise correlation between points.

Compared with the closest prior art, the technical solution provided by the present invention has the following beneficial effects:

In the prior art, the power line carrier communication equipment is mainly used for data transmission, and the purpose of noise measurement is mainly to eliminate noise and reduce the impact on communication, all of which are considered in the application of communication quality. The invention makes full use of the signal analysis in the power line carrier communication, applies the high frequency impedance measurement and the power line communication noise measurement results to the state identification of the equipment, especially analyzes and identifies the equipment and network state information implied by the noise information, and makes full use of the carrier equipment to The high-frequency impedance measurement function measures high-frequency impedance and communication noise, and realizes the online identification of the operating status of the power distribution network and equipment.

Description of drawings

FIG. 1 is a flow chart of a method for online identification of power distribution network and equipment status based on power line signals according to the present invention.

FIG. 2 is a schematic diagram of the power line network access high-frequency impedance test according to the present invention.

FIG. 3 is the principle of extracting and classifying power line noise features according to the present invention.

Detailed ways

The invention proposes a power distribution network and equipment fault identification method based on the combination of high-frequency impedance measurement and high-frequency noise measurement of power line carrier equipment. The system composition realized by the method includes distribution lines, high-frequency cables, coupling equipment, power line carrier communication equipment, and a background master station system. The invention provides a new technical means for online identification of power distribution network and equipment faults.

The present invention will be further described in detail below in conjunction with the accompanying drawings.

As shown in FIG. 1 , an online identification method of power distribution network and equipment operating status based on power line signals of the present invention includes the steps of: installing power line carrier communication equipment at the positions of distribution network transformers and power distribution switches, and the background master station system coordinates the power lines. The communication connection is established between the carrier devices. The coordination content includes which carrier device communicates with which carrier device, when to communicate, etc., all of which are allocated and controlled by the background master station system. The power line carrier communicates with the communication device to measure the high frequency of the installation location. Impedance, the power line carrier communication equipment measures the signal noise at the installation location, the power line carrier communication equipment uploads the characteristic information of the background master station system, and the background master station system identifies the equipment and network operating status.

Figure 2 shows the schematic diagram of the power line network access high-frequency impedance test. The output AC of the power line carrier device on the left can generate a signal of 30kHz to 100MHz. The signal is injected into the power line from the AB terminal through the coupler, and the voltage U and current of the circuit are tested. I can calculate the access impedance of the power line. Among them, R1 is the current limiting resistance, R2 is the standard resistance, and Z is the access impedance of the power line network. _The access impedance of the power line network can be calculated by measuring the magnitude and phase difference of the voltages _UA and UB.

U _B = -IR ₂ (2)

Substitute I=-U _B /R ₂ into the above formula to get:

In this way, the value of the access impedance Z can be calculated from the known quantity.

Figure 3 is a schematic diagram of power line noise feature extraction and classification. Among them, S(t) is the transmitted signal, R(t) is the received signal, and the conversion of h(t) and h(f) reflects the transmission characteristics of the channel. The noise on the power line carrier channel is difficult to directly quantitatively express, and it also has its own characteristics. , the power line carrier channel noise has the characteristics of continuity, periodicity, randomness and variability. The characteristics of the power line carrier channel noise are closely related to the location, time, and power grid load equipment and other interference sources, and each noise is independent of each other. There are five main types of noise in the power line carrier channel, which are summarized as follows: colored background noise, narrow-band noise, power frequency synchronous periodic impulse noise, power frequency asynchronous periodic impulse noise and asynchronous impulse noise. Operating status:

The colored background noise spectrum occupies the entire power line communication bandwidth, and it is a combined interference signal formed by the accumulation of many low-power noise sources connected to the power line. Colored background noise usually persists for seconds or minutes, and sometimes hours without appreciable change. The main source of the noise is mostly the interference of a frequency of up to 30MHz generated by a large number of household electrical appliances (such as dimming lamps, computers, refrigerators, induction cookers or hair dryers, etc.).

Narrowband noise refers to the noise similar to sinusoidal amplitude modulation signals in the frequency range of power line carrier communication. Its power spectral density is high, mainly caused by the crosstalk of medium wave and short wave radio signals in the corresponding frequency domain. Narrowband noise is also generated by the scan synchronization signal with the computer.

Typical asynchronous impulse noise is caused by switching events on medium and low voltage grids, and their shape is usually similar to a damped sine wave or superimposed damped sine wave. The pulse strength is related to the strength of the noise source and the distance of the noise source from the receiver.

The periodic impulse noise of power frequency synchronization is mainly caused by the switching of switching devices and thyristor devices in the switching power supply on the grid. The impulse noise repetition frequency is 50Hz (60Hz in the United States, Japan, etc.) or its integer multiples, and the noise duration Longer, higher power, wider frequency coverage, power spectral density decreases with the increase of frequency.

The repetition frequency of power frequency asynchronous periodic impulse noise is generally 50-200kHz, which is mainly generated by computer monitors and television receivers. The periodic frequency of the noise depends on the scanning frequency standards of computer monitors and television receivers, and these frequencies will become higher and higher with the pursuit of high-resolution image quality.

As will be appreciated by those skilled in the art, the embodiments of the present application may be provided as a method, a system, or a computer program product. Accordingly, the present application may take the form of an entirely hardware embodiment, an entirely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present application may take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, etc.) having computer-usable program code embodied therein.

The present application is described with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the present application. It will be understood that each flow and/or block in the flowchart illustrations and/or block diagrams, and combinations of flows and/or blocks in the flowchart illustrations and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to the processor of a general purpose computer, special purpose computer, embedded processor or other programmable data processing device to produce a machine such that the instructions executed by the processor of the computer or other programmable data processing device produce Means for implementing the functions specified in a flow or flow of a flowchart and/or a block or blocks of a block diagram.

These computer program instructions may also be stored in a bootable computer or other programmable data processing device.

Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Those of ordinary skill in the art can still modify or equivalently replace the specific embodiments of the present invention with reference to the above embodiments. Any modifications or equivalent substitutions that depart from the spirit and scope of the present invention are all within the protection scope of the claims of the present invention for which the application is pending.

Claims (2)

1. an on-line identification method for power distribution network and equipment operating state based on power line signal, it is characterized in that power line carrier communication equipment is installed at the position of distribution network transformer and power distribution switch, and the background master station system coordinates the establishment of communication connection between the power line carrier equipment, The power line carrier communication equipment measures the high-frequency impedance and signal noise of the installation location, and uploads the measured high-frequency impedance characteristic information and noise characteristic information to the background master station system, and the background master station system according to the high-frequency impedance characteristic information and noise characteristic information Identify equipment and network faults. The background master station system stores the high-frequency impedance and noise information measured by each carrier device, analyzes the time-varying characteristics of high-frequency impedance characteristic information and noise characteristic information, and analyzes the high-frequency impedance characteristic information and noise characteristics between adjacent nodes. Correlation of noise characteristic information to judge the operation status of distribution network and equipment; Among them, power line carrier communication equipment is installed at the distribution network transformer and distribution switch positions, and the carrier communication equipment installed at the distribution transformer is connected to the three-phase high-voltage side and low-voltage side three-phase four-wire of the transformer, a total of 7 carrier signal coupling devices. The carrier communication equipment installed at the power distribution switch is respectively connected to the three-phase incoming line and the three-phase outgoing line of the switch, a total of six carrier signal coupling devices; The measurement of the high-frequency impedance at the installation location refers to the impedance of the power line carrier communication equipment scanning the discrete frequency points configured in the range of 30kHz-100MHz, and the measurement of the signal noise at the installation location refers to the analysis of the noise at the installation location by the power line carrier communication equipment. Frequency bands, analyze and identify the operating status of the equipment in the distribution network, upload the analysis results to the background master station system, and then analyze the noise correlation between the points. 2. The method for online identification of power distribution network and equipment operating state based on power line signals according to claim 1, characterized in that the background master station system coordinates power line carrier communication to establish a communication connection, and the background master station system manages the power line carrier communication network , used to perform remote configuration of equipment and network networking settings, monitor equipment running status, and coordinate power line carrier communication equipment to establish communication connections through the background master station system.

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