CN116338377A - Method and system for online real-time data acquisition and grounding grid fault monitoring - Google Patents

Abstract

The invention discloses a method and a system for acquiring data on line in real time and realizing ground network fault monitoring, and belongs to the technical field of ground network fault monitoring. The invention injects exciting current, and measures the grounding resistance and the accessible node voltage of the grounding network based on the multichannel self-adaptive variable frequency measurement technology in real time; establishing an annual data set of the grounding resistance based on the grounding resistance monitoring data obtained by annual real-time monitoring, analyzing the resistance change of each branch node of the grounding network by utilizing the theorem related to the electric network theory based on the accessible node voltage obtained in real time, the established grounding network model and the fault equation, and obtaining the non-accessible node voltage and the resistance for judging the operation state of the branch; and judging the fault of the grounding network based on the non-accessible node voltage and the resistor of the branch running state so as to determine fault point position information, wherein the fault point position information comprises fault positioning and fault types. The method is used for monitoring the faults of the grounding network.

Description

Method and system for online real-time data acquisition and grounding grid fault monitoring

technical field

A method and system for acquiring data online in real time and realizing grounding grid fault monitoring are used for grounding grid fault monitoring and belong to the technical field of grounding grid fault monitoring.

Background technique

The ground grid is an important part of the electronic and electrical system, and good grounding is an important guarantee for the safety of people and equipment. However, it is difficult to know its true status in a long-term operation. Once a lightning strike or system failure occurs, a high fault voltage will be generated, affecting the normal operation of electrical and electronic information equipment, and the social impact caused is difficult to dispel in a short time. The operation of electronic information equipment is highly dependent on the stability of power supply and signal transmission. If there are problems such as poor connection and corrosion of the grounding grid, the performance of the equipment will be reduced or even damaged due to the decrease of the dissipation performance, and the occurrence of lightning and operating overvoltage. Therefore, it is of great engineering significance to realize the timely detection and troubleshooting of grounding grid faults and realize the intelligent detection and fault diagnosis technology of grounding grids for industries such as electric power, flammable and explosive, and electronic information.

Research on grounding grid monitoring and fault diagnosis technology began in the 1980s. There are few foreign studies, because most foreign countries use copper as the grounding material. In my country, steel is mostly used as the grounding grid. In the same soil, the corrosion rate of steel is about 7 times that of copper. However, foreign scholars have made major contributions in the theoretical research of grounding grid analysis. F. Dawalibi1984 proposed the method of moments to analyze the grounding performance of the grounding grid, and developed the CDEGS grounding system analysis software.

According to different principles, domestic scholars have realized the grounding grid fault diagnosis method in three aspects.

Electromagnetic analysis method: use the measured electric field or magnetic field distribution on the surface of the grounding grid combined with the numerical simulation of the grounding grid to diagnose faults. Jiang Mingliang proposed a substation grounding grid conductor and grid structure detection method in the absence of grounding grid drawings, and realized the detection of the grounding grid status by using the distribution characteristics and laws of the measured ground surface magnetic induction intensity.

Electric network analysis method: Based on the electric network theory, the fault diagnosis equation is established to solve the corrosion situation of the branch conductor. Liu Jian made full use of the voltage information of the accessible nodes, and adopted the method of alternating the excitation position of the current source in the accessible nodes and measuring the node voltage at multiple locations during each excitation, which reduced the underdetermination of the fault equations. Cheng Hongli used the taboo search algorithm on the basis of electrical network theory to realize the partition location of grounding grid faults.

Electrochemical analysis method: According to the principle of direct current generated when the conductor undergoes a chemical reaction in the soil, the breakpoint detection is realized by using the corrosion electrochemical detection technology. Han Lei has developed an on-site portable rapid corrosion detection system, which measures the corrosion status through a constant current step method, and obtains the polarization resistance value of the electrode according to the charging curve to judge the corrosion status of the grounding grid.

The above research has brought good results to the fault diagnosis of the grounding grid, but there are the following technical problems:

1. Using the electromagnetic analysis method, electrical network analysis method and electrochemical analysis method still needs to shut down the power and stop the fault diagnosis of the grounding grid, which is expensive;

2. The use of electromagnetic analysis, electrical network analysis and electrochemical analysis still requires large-scale excavation for fault diagnosis, which has a certain degree of blindness, resulting in poor fault diagnosis accuracy and high cost;

3. It is necessary to obtain data on the basis of electromagnetic analysis, electrical network analysis or electrochemical analysis, and perform complex calculation and analysis in the laboratory, which cannot realize automatic collection and intelligent processing of required parameters.

Contents of the invention

In view of the above-mentioned research problems, the purpose of the present invention is to provide a method and system for online real-time data acquisition and grounding grid fault monitoring, and solve the problem that the existing technology still needs to shut down the grounding grid for fault diagnosis, which is expensive.

In order to achieve the above object, the present invention adopts following technical scheme:

A method for obtaining data online in real time and realizing grounding grid fault monitoring, comprising the following steps:

Step 1: Inject the excitation current, and measure the grounding resistance of the grounding network and the voltage of the accessible nodes based on the multi-channel adaptive frequency conversion measurement technology in real time; the measurement range of the grounding resistance is 0-1000 ohms, and the measurement accuracy is 3%± within 2d. Step 2: Establish an annual data set of grounding resistance based on the grounding resistance monitoring data obtained from real-time monitoring across the year, and analyze the change characteristics of the monitoring data, and obtain the result of whether the grounding performance of the grounding grid has declined based on the change characteristics. If it declines, go to step 3. At the same time, judge whether it reaches the warning value. If it reaches the warning value, the state will give a warning, otherwise, it will prompt for aging;

Step 3: Based on the real-time accessible node voltage, the established grounding grid network model and fault equation, and using Tellegen's theorem and Kirchhoff's law to analyze the resistance change of each branch node of the grounding grid, Obtain the voltage and resistance of the non-accessible nodes used to judge the operating state of the branch;

Step 4: Based on the voltage and resistance of the non-accessible nodes in the operation state of the branch, the fault judgment of the grounding network is performed to determine the location information of the fault point, which includes fault location and fault type.

Further, the multi-channel self-adaptive frequency conversion measurement technique in the step 1 refers to changing the measurement frequency of the grounding network to obtain the amplitude in the ground resistance measurement mode and the node voltage measurement mode, wherein the frequency range is 40HZ-60HZ.

Further, the step 2 is based on the annual data set of grounding resistance, artificially analyzing the change characteristics and trends, so as to obtain the change characteristics of the corrosion degree of the grounding grid, which is used for subsequent judgment on the specific fault location of the grounding grid.

Further, the grounding grid electrical network model in the step 3 is based on the real structure of the grounding grid, and the equivalent circuit model of the grounding grid is established according to Tellegen's theorem and electrical network theory;

The number of fault equations is the same as the ports of the grounding grid, and a mathematical model is established based on Tellegen's theorem and the relationship between the resistance change of the grounding grid port and the branch resistance change.

Further, the step 3 is assuming that the grounding resistance of each segment of the grounding grid is bad, and based on the real-time accessible node voltage, the established grounding grid network model and the corresponding fault equation, using Tellegen's theorem and the basic Erhoff's law calculates the voltage distribution and resistance of non-accessible nodes in the network with different resistance values according to the step size.

Further, the specific steps of the step 4 are:

Compare the resistance of non-accessible nodes with the nominal value of the resistance of the grounding grid, and then determine the degree of corrosion of the grounding grid by comparing the resistance change multiples, that is, according to Tellegen's theorem, compare the calculated and analyzed branch resistance with the nominal value Values are compared to judge the degree of corrosion, that is, to judge the type of fault;

The calculated non-accessible node voltage distribution is compared with the measured accessible node voltage distribution to obtain the corresponding square error, and then the minimum value of the square error is used as the fault location. The nominal value of the grounding resistance is Refers to the resistance value of each conductor of the grounding grid without corrosion.

Further, step 5 is also included: the terminal software platform based on the Internet + GIS visually displays the fault judgment results and annual data sets. The software platform can control the working status of the grounding grid intelligent detector in real time and control the remote acquisition of data.

A system for online real-time data acquisition and grounding grid fault monitoring, including:

Import data module: inject excitation current, measure the grounding resistance of the grounding grid and the measurement of the accessible node voltage in real time based on the multi-channel adaptive frequency conversion measurement technology;

Model building module: When the grounding performance of the grounding grid is degraded, based on the real-time accessible node voltage, the established grounding grid network model and fault equation, and using Tellegen's theorem and Kirchhoff's law to analyze the grounding grid's branches Analyze the resistance changes of road nodes to obtain the voltage and resistance of inaccessible nodes used to judge the operating state of the branch;

Corrosion prediction module: Based on the operating status of each node and the analyzed change characteristics, the fault judgment of the grounding grid is performed to determine the location information of the fault point and the fault type.

Further, the terminal software platform of the Internet+GIS also includes a remote control module, a database, a visual alarm and data display module, a data analysis and diagnosis module, a user management module, a report generation module, and a data statistics and query module.

Compared with the prior art, the present invention has beneficial effects as follows:

1. The present invention utilizes multi-channel frequency conversion measurement technology to realize automatic acquisition of electrical network equation parameters, intelligent analysis of aging status, and intelligent and automatic grounding grid fault diagnosis. Through online diagnosis, the grounding grid resistance value can be obtained in real time, and real-time Intelligently judge the status and characteristics of the grounding grid, avoiding the randomness and discontinuity of manual detection, and also avoiding the problem that faults that occur during the interval of manual detection cannot be discovered in time. At the same time, it provides real-time operating status information and uses intelligent diagnosis of grounding grid faults Technology, combined with the measurement parameter set (the voltage value of the accessible node and the resistance value of the grounding grid, as well as the calculated voltage value of other nodes and the resistance value of each conductor) and the fault discrimination method, to realize the state of the grounding grid without human intervention Aging early warning and fault intelligent diagnosis method, and the regional monitoring network can be formed by laying out multiple measurement stations, which improves the level of informatization and intelligence, and lays the foundation for big data mining and application; in particular, it can realize the grounding network fault diagnosis required Real-time monitoring and acquisition of parameters, and intelligent judgment of the location of the fault point of the grounding grid through the fault diagnosis method, does not require manual measurement of various or multiple measuring equipment during power outages, and does not require long-term analysis and calculation in the laboratory ;

2. The present invention utilizes long-time series real-time monitoring data as the grounding grid aging criterion, that is, utilizes the change curve of the long-time series grounding resistance measurement value to realize a good prediction of the changing trend of the grounding grid resistance value, thereby realizing grounding Network aging status judgment;

Three, the present invention utilizes online monitoring data to realize in real time the solution of the fault equation of the grounding grid and the discrimination of the fault type (corrosion, fracture, etc.), which solves the long-term analysis after the data is manually obtained at present;

Real-time monitoring and alarming of the status of the grounding grid by using long-term series grounding parameter values (the overall resistance value of the grounding grid);

4. The present invention can overcome power frequency current interference through frequency conversion measurement, obtain the overall grounding resistance value of the grounding grid, and judge whether the performance of the grounding system has declined;

5. The present invention realizes the online detection of the resistance voltage value of the grounding grid through the research of the fault diagnosis model of the grounding grid, thereby judging the fault state and location of the grounding grid through data analysis, and avoiding the occurrence of large-scale excavation.

Description of drawings

Fig. 1 is a schematic diagram of the technical route of the present invention;

Fig. 2 is overall structure and functional block diagram of the present invention;

Fig. 3 is the schematic diagram of modeling and solving thereof of grounding grid electrical network in the present invention, wherein, in the grounding grid, be the node numbers "i, j" that can be reached, and in the electrical network model, measure the branch circuit voltage value "branch b+1 , b+2, node p, node q, node m, node n";

Fig. 4 is a schematic diagram of multi-channel measurement in the present invention;

Fig. 5 is a flow chart of grounding grid fault diagnosis in the present invention, wherein the fault type specifically refers to the aging degree of the grounding grid, the degree of corrosion of the grounding grid, and the grounding resistance increases or breaks.

Detailed ways

The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments.

Combined with the current research status, further development will be required in the following aspects: first, the research on grounding grid fault diagnosis model, through the establishment of a reasonable model, to achieve a comprehensive diagnosis of ground grid corrosion without excavation; Research, combined with the comprehensive consideration of ground potential rise, internal potential difference, and contact potential difference; the third is real-time online monitoring and fault diagnosis technology to detect and analyze grounding grid faults in time.

A method for obtaining data online in real time and realizing grounding grid fault monitoring, comprising the following steps:

Step 1: Inject the excitation current, and measure the grounding resistance of the grounding grid and the measurement of the accessible node voltage in real time based on the multi-channel adaptive frequency conversion measurement technology; In the working mode, change the measurement frequency of the ground grid to obtain the amplitude, where the frequency range is 40HZ-60HZ.

System control: The system uses a STM32f103 series ARM controller as the core to coordinate the work between various modules. In order to avoid the impact of the harsh environment on the line monitoring circuit, physical isolation is required between the channels during standby. During the sampling test, the relay pulls in to make the test line connected to the measurement system.

Frequency adjustment: Use SPWM waveform to control the on-off of the switching device in the inverter circuit, so that the area of the output pulse voltage is equal to the area of the output sine wave in the corresponding interval, and the inverter is adjusted by changing the frequency and amplitude of the modulating wave The frequency and amplitude of the output voltage of the circuit.

Current control: The constant current source module is a software self-feedback adjustment method, which uses digital PID incremental control to adjust the current to make it gradually constant. Increase the current, thereby improving the test accuracy of the system.

Signal acquisition and processing: use 2 pieces of CS5460A power IC, one is used to measure the AC current value in the current channel, and the other is used to measure the voltage between the ground electrode P and ES. The CS5460A energy IC is a highly integrated ΔΣ analog-to-digital converter including two ΔΣ ADCs, high-speed energy calculation functions and a serial interface. The controller ARM can easily communicate with the chip. With high-speed digital low-pass filtering, digital compensation filtering, digital high-pass filtering functions, it can eliminate clutter very well.

Measurement and communication circuit: use the relay as an electronic switch to realize the switching of two channels, one is the switching of the current channel, and the current injection of the variable frequency constant current source to different measurement channels makes C-E (1-5) form a current loop; the other is to realize the P and Switching between PVs, when measuring the node voltage, complete the switching from P to PV.

The communication module is based on 4G/5G wireless communication technology, and the measurement data is sent to the GPRS module through the RS232 serial interface, and the seamless connection with the Internet is realized on the computer terminal.

Switching circuit design principle:

Use SPWM technology to inject sine wave signal into the grounding system, and start sampling current and voltage signals at the same time.

The system has two working modes. One is the grounding resistance measurement mode. At this time, the accessible node E4 or E3 in the middle of the grounding grid is selected as the test electrode, and C-P forms a grounding resistance measurement circuit. The second is the node voltage measurement mode. The voltage measurement mode is formed between PV-E (1-5). After a measurement is completed, switch the measurement channel and repeat the last measurement. Finally, obtain the voltage value of the grounding resistance of the grounding grid and the accessible node.

Switching circuit design instructions:

There are four poles in the switching circuit test part, which are test pole E, test pole Es-OUT, voltage pole P, and current pole C.

Among them, the test pole E (this pole is used in the three-pole method measurement and is short-circuited with the Es-OUT pole) is divided into six channels: E1, E2, E3, E4, E5, and E6;

The test pole Es-OUT (used in the three-pole four-wire method measurement) is divided into Es-OUT1, Es-OUT2,

Es-0UT3, Es-0UT4, Es-0UT5, Es-0UT6 six channels;

The voltage pole P is divided into six channels: P1, P2, P3, P4, P5, and P6;

The current electrode C is divided into six channels: C1, C2, C3, C4, C5, and C6.

A total of 24 channels of four poles can be combined arbitrarily and time-division multiplexed, which not only is compatible with the test scheme required by this design, but also enhances the flexibility in actual testing.

Step 2: Establish an annual data set of grounding resistance based on the grounding resistance monitoring data obtained from real-time monitoring across the year, and analyze the change characteristics of the monitoring data, and obtain the result of whether the grounding performance of the grounding grid has declined based on the change characteristics. If it declines, go to step 3. At the same time, judge whether it reaches the warning value. If it reaches the warning value, if it reaches it, the status will be given a warning, otherwise it will be prompted for aging; according to the annual data set of grounding resistance, artificially analyze the change characteristics and trends, so as to obtain the change characteristics of the corrosion degree of the grounding grid, which will be used for subsequent monitoring. The judgment of the specific fault location of the grounding grid.

Step 3: Based on the real-time accessible node voltage, the established grounding grid network model and fault equation, and using Tellegen's theorem and Kirchhoff's law to analyze the resistance change of each branch node of the grounding grid, Obtain the voltage and resistance of non-accessible nodes for judging the operating state of the branch; the grounding grid network model is based on the real structure of the grounding grid, and the equivalent circuit model of the grounding grid is established according to Tellegen's theorem and electrical network theory;

The failure equation looks like this:

Among them, p is the port group under test, ΔR _K is the resistance variation of the k-th branch, ΔR _jj is the resistance variation of the accessible node i and j ports, I _k is the current matrix of the k-th branch, and I ₀ is the excitation current , I _K ′ represents the current matrix of the kth branch after the fault;

The number of fault equations is the same as the ports of the grounding grid, and a mathematical model is established based on Tellegen's theorem and the relationship between the resistance change of the grounding grid port and the branch resistance change.

Specifically: the step 3 is to assume that the grounding resistance of each segment of the grounding grid is bad, and based on the real-time accessible node voltage, the established grounding grid network model and the corresponding fault equation, using Tellegen's theorem and Kirchhoff's law calculates the voltage distribution and resistance of inaccessible nodes in the network with different resistance values according to the step size.

Step 4: Based on the voltage and resistance of the non-accessible nodes in the operation state of the branch, the fault judgment of the grounding network is performed to determine the location information of the fault point, which includes fault location and fault type.

The specific steps are:

Compare the resistance of non-accessible nodes with the nominal value of the resistance of the grounding grid, and then determine the degree of corrosion of the grounding grid by comparing the resistance change multiples, that is, according to Tellegen's theorem, compare the calculated and analyzed branch resistance with the nominal value Values are compared to judge the degree of corrosion, that is, to judge the type of fault;

The calculated non-accessible node voltage distribution is compared with the measured accessible node voltage distribution to obtain the corresponding square error, and then the minimum value of the square error is used as the fault location. The nominal value of the grounding resistance is Refers to the resistance value of each conductor of the grounding grid without corrosion.

It also includes step 5: the terminal software platform based on the Internet + GIS visually displays the fault judgment results and annual data sets. The software platform can control the working status of the grounding grid intelligent detector in real time and control the remote acquisition of data.

A system for online real-time data acquisition and grounding grid fault monitoring, including:

Import data module: inject excitation current, measure the grounding resistance of the grounding grid and the measurement of the accessible node voltage in real time based on the multi-channel adaptive frequency conversion measurement technology;

Model building module: when the grounding performance of the grounding grid is degraded, the resistance change of each branch node of the grounding grid is calculated based on the real-time obtained accessible node voltage, the established grounding grid network model and the fault equation, and using the relevant theorems of the electrical network theory Perform analysis to obtain the voltage and resistance of inaccessible nodes used to judge the operating state of the branch;

Corrosion prediction module: Based on the operating status of each node and the analyzed change characteristics, the fault judgment of the grounding grid is performed to determine the location information of the fault point and the fault type.

The terminal software platform of the Internet+GIS also includes a remote control module, a database, a visual alarm and data display module, a data analysis and diagnosis module, a user management module, a report generation module, and a data statistics and query module.

The above are only representative examples among numerous specific application scopes of the present invention, and do not constitute any limitation to the protection scope of the present invention. All technical solutions formed by transformation or equivalent replacement fall within the protection scope of the present invention.

Claims (9)

1. The method for acquiring data on line in real time and realizing the fault monitoring of the grounding grid is characterized by comprising the following steps:

step 1: injecting exciting current, and measuring the grounding resistance and the accessible node voltage of a grounding grid in real time by frequency conversion based on a multichannel self-adaptive frequency conversion measurement technology; the measurement range of the grounding resistance is 0-1000 ohms, and the measurement accuracy is within 3% +/-2 d.

Step 2: establishing an annual data set of the grounding resistance based on the grounding resistance monitoring data obtained by annual real-time monitoring, carrying out change characteristic analysis of monitoring data, obtaining a result of whether the grounding performance of the grounding network is reduced or not based on the change characteristic, if so, turning to step 3, judging whether the grounding performance of the grounding network reaches an early warning value or not, if so, carrying out state early warning, otherwise, carrying out aging prompt;

step 3: based on the available node voltage obtained in real time, an established grounding network model and a fault equation, analyzing the resistance change of each branch node of the grounding network by utilizing the Taylor theorem and the kirchhoff law to obtain non-available node voltage and resistance for judging the operation state of the branch;

step 4: and judging the fault of the grounding network based on the non-accessible node voltage and the resistor of the branch running state so as to determine fault point position information, wherein the fault point position information comprises fault positioning and fault types.

2. The method for acquiring data on line and monitoring faults of a ground network in real time according to claim 1, wherein the multichannel adaptive variable frequency measurement technology in the step 1 refers to changing the measurement frequency acquisition amplitude of the ground network in a ground resistance measurement working mode and a node voltage measurement working mode, and the frequency range is 40HZ-60HZ.

3. The method for acquiring data on line and realizing fault monitoring of the grounding network according to claim 2, wherein the step 2 is characterized in that the change characteristic and trend are manually analyzed according to the annual data set of the grounding resistance so as to obtain the change characteristic of the corrosion degree of the grounding network for judging the specific fault position of the subsequent grounding network.

4. The method for acquiring data and realizing ground network fault monitoring on line in real time according to claim 3, wherein the ground network model in step 3 is obtained by establishing an equivalent circuit model of the ground network according to the terylen theorem and the electric network theory based on the ground network real structure;

the number of the fault equations is the same as that of the ports of the grounding grid, and a mathematical model is established according to the relationship between the Taylor root theorem and the port resistance change and the branch resistance change of the grounding grid.

5. The method according to claim 4, wherein the step 3 is to assume that the resistance of each section of the grounding network is bad, and calculate the distribution and resistance of the non-accessible node voltages in the network with different resistance values according to step sizes by using the terylen theorem and kirchhoff law based on the accessible node voltages acquired in real time, the established grounding network model and the corresponding fault equations.

6. The method for acquiring data and implementing ground network fault monitoring on-line in real time according to claim 5, wherein the specific steps of step 4 are as follows:

comparing the non-accessible node resistance with the nominal value of the grounding grid resistance, and determining the corrosion degree of the grounding grid by comparing the resistance change multiples, namely comparing the branch resistance obtained by calculation and analysis with the nominal value according to the Taylor theorem, and judging the corrosion degree, namely judging the fault type;

and (3) performing corresponding voltage-to-voltage comparison between the calculated non-reachable node voltage distribution and the measured reachable node voltage distribution to obtain a corresponding square error, and taking the minimum square error value as fault location, wherein the nominal value of the grounding resistor refers to the resistance value of each section of conductor of the grounding grid under the condition of no corrosion.

7. The method for online real-time data acquisition and ground network fault monitoring according to claim 4, further comprising step 5: the terminal software platform based on the Internet + GlS carries out visual display on the fault judgment result and the annual data set, and the software platform can control the working state of the intelligent grounding grid detector in real time and control the remote acquisition of data.

8. A system for acquiring data on-line in real time and implementing ground network fault monitoring, comprising:

and (4) importing a data module: injecting exciting current, and measuring the grounding resistance and the accessible node voltage of a grounding grid in real time by frequency conversion based on a multichannel self-adaptive frequency conversion measurement technology;

and (3) establishing a model module: when the grounding performance of the grounding network is reduced, based on the available node voltage acquired in real time, an established grounding network model and a fault equation, and by utilizing the Taylor theorem and kirchhoff law, the resistance change of each branch node of the grounding network is analyzed, so as to obtain the non-available node voltage and resistance for judging the branch running state:

corrosion prediction module: and judging the fault of the grounding network based on the running state of each node and the analyzed change characteristics so as to determine the position information of the fault point and the fault type.

9. The system for acquiring data on line and monitoring faults of a ground network in real time according to claim 8, wherein the terminal software platform of the internet+gis further comprises a remote control module, a database, a visual alarm and data display module, a data analysis and diagnosis module, a user management module, a report generation module and a data statistics and query module.

Images