CN106556754A - A kind of online acquisition method of distribution line failure waveform - Google Patents

Abstract

The invention relates to an online acquisition method of distribution line fault waveform, which belongs to the detection field. It sets a fault indicator on the three-phase lines of several towers along the overhead line of the distribution network, and sets a monitoring communication terminal on the tower where the fault indicator is located; between the three fault indicators, and between the fault indicator and the A short-distance wireless communication network is set between the monitoring communication terminals on the same tower; the monitoring communication terminal is connected to the system main station via the GPRS wireless network for long-distance wireless network connection. It synchronously collects the fault data of the fault current of each section of the line through the fault indicator, and reproduces the three-phase current waveform at the time of the fault. It can calculate the zero-sequence voltage and current through the protection algorithm, and assist in the judgment of the ground fault, which greatly improves the accuracy of the ground fault judgment. accuracy. The technical scheme of the invention is particularly suitable for the automatic construction mode of distribution network in small and medium cities or the supplementary project for automatic transformation of distribution network in large cities.

Description

A Method of Online Acquisition of Distribution Line Fault Waveform

technical field

The invention belongs to the detection field, in particular to a monitoring method for distribution line faults.

Background technique

In the power system, the power comes from the power plant, and is transmitted to the load side through the high-voltage or ultra-high-voltage transmission network, and then the power is distributed to users of different voltage levels by the network with a lower voltage level, which mainly plays the role of power distribution in the power grid. The network is called the distribution network, referred to as the distribution network.

The distribution network is at the core of the smart grid. In recent years, power companies have vigorously developed the distribution network industry and are committed to establishing an efficient, stable and reliable distribution network.

Nowadays, the development of distribution network encounters the problem of line fault detection and troubleshooting, especially in remote mountainous areas and areas with extremely complex terrain.

As an effective auxiliary means of fault location in distribution network, fault indicators are increasingly recognized by power grid companies, and will be installed in large numbers in distribution network lines in the future.

The types of faults that frequently occur in the distribution network are mainly short-circuit faults and ground faults; short-circuit faults are divided into three-phase and two-phase short-circuits; there are many types of ground faults, generally single-phase ground faults, and its judgment and location have always been A worldwide problem; when a ground fault occurs in a three-phase line, although the current, voltage and vector synthesis in the three-phase line are still symmetrical and will not affect the normal operation of the entire distribution network, a small current ground fault will cause overvoltage. It is very easy to cause serious power accidents. When the distribution network is in the low-current ground fault operation state for a long time, there will be great potential safety hazards.

The short-circuit fault can be indicated by a simple fault indicator to locate the fault point, and the ground fault can be judged according to the threshold value of the capacitance current to determine the fault. However, the capacitance of the ground fault of the overhead line has been affected by other factors for a long time. Generally, the grounding current is small, and it is difficult to determine and locate the grounding fault by judging the threshold value.

Contents of the invention

The technical problem to be solved by the present invention is to provide an online acquisition method for distribution line fault waveforms, which synchronously collects the fault data of each section of line fault current through the fault indicator, and reproduces the three-phase current waveform at the time of the fault. The protection algorithm calculates the zero-sequence voltage and current, assists in judging the ground fault, and greatly improves the accuracy of the ground fault judgment.

The technical solution of the present invention is to provide an online acquisition method for distribution line fault waveforms, including fault indicators installed at each monitoring point of the overhead line of the distribution network and a system master station installed in the monitoring center, characterized in that:

On the three-phase lines A, B, and C of several towers along the overhead lines of the distribution network, a fault indicator is set correspondingly, and the three fault indicators are respectively used for fault monitoring of the three-phase lines A, B, and C and fault indication;

Set up a monitoring communication terminal on the tower where the fault indicator is located;

The three fault indicators are set correspondingly to the monitoring communication terminals on the same tower, forming a group of distribution network fault on-site monitoring units;

A short-distance wireless communication network is set between the three fault indicators, and between the fault indicators and the monitoring communication terminal on the same tower;

The monitoring communication terminal carries out long-distance wireless network connection with the system master station through the GPRS wireless network;

On each overhead line of the distribution network from the substation to the power user, there are multiple groups of on-site fault monitoring units of the distribution network;

The communication monitoring terminal and the fault indicator use an ultrasonic or infrared auxiliary synchronous timing device to perform synchronous timing; when the communication monitoring terminal sends a timing command, the fault indicator on the three-phase line receives the trigger signal at the same time, and starts synchronous timing ;During the running process, periodically synchronize the time to keep the clock in the three-phase fault indicator under the condition of long-term operation of the fault indicator to maintain synchronization accuracy;

During normal operation, the CPU of the fault indicator is in a dormant state. In this state, the AD module of the fault indicator performs high-speed sampling, and the real-time sampling data is transmitted to the internal memory of the fault indicator through the DMA module. The buffer area of the internal memory passes through The latest data is always saved in a cyclical rotation mode. The CPU is woken up within T intervals through a timing interrupt. After the CPU is woken up, it processes a large number of stored sampling data and obtains the telemetry value of the three-phase line operation data;

During normal operation, the fault indicator detects the line fault of the corresponding phase line. When a fault occurs in one of the three-phase lines, the current of the faulty phase changes significantly, and the fault indicator immediately wakes up the CPU and records the fault at the current moment. Time scale and corresponding real-time sampling data; at this time, the fault indicator of the faulty phase line triggers the fault indicators of the other two phase lines, records the fault time scale and real-time sampling data of the corresponding phase line, starts data "wave recording", and Actively report the sampling data of the three-phase fault indicator with the fault time scale to the monitoring communication terminal; after the communication monitoring terminal calculates the deviation between the time scale reference of the line fault phase time scale and the time scale of the other two non-fault phase lines, it calls the time scale deviation phase again. The cycle sampling data of the fault indicator where it is located is transmitted to the communication monitoring terminal; the communication detection terminal transmits the sampled fault data to the system master station through the remote communication system, and the master station system reproduces the three-phase current waveform at the time of the fault through data fusion, and calculates Generate zero-sequence voltage and zero-sequence current to distinguish whether the line at the fault point is a ground fault or a short-circuit fault. According to the type of fault, corresponding measures are taken to effectively isolate the line fault and improve the accuracy of ground fault judgment.

Specifically, the buffer can store 10s of three-phase line operation data.

Specifically, the T interval is less than 10s.

Specifically, the short-distance wireless communication network includes at least a Zigbee network or a Wi-Fi wireless local area network.

Further, the fault indicator monitors the current of the line and the electric field to the ground in real time, detects the short circuit fault on the spot, and triggers the wave recording when the line current or voltage changes abnormally, and detects the short circuit through the communication detection terminal installed on the tower The fault remote signaling signal and recorded waveform are uploaded to the system master station in the form of remote signaling signal. The software of the system master station performs short-circuit fault location according to the remote signaling signal, and detects and locates the ground fault of the overhead line of the distribution network according to the recorded waveform. Guide the operation, maintenance and repair work to improve the reliability of the power grid.

Further, the fault indicator judges whether a short-circuit fault has occurred in the overhead line according to the following judgment conditions:

For a fault indicator:

1) The line in front of the fault indicator has power;

2) There is an abrupt current It ≥ 200A in the line where the fault indicator is located, and It is the sudden current start;

3) The duration of high current in the line of the phase where the fault indicator is located is 0.02s≤△T≤3s, and △T is the current mutation time;

4) The line behind the fault indicator is powered off;

When the above four conditions are met at the same time, the fault indicator detection determines that a short-circuit fault occurs in the line behind the location of the fault indicator.

Further, the fault indicator judges whether a ground fault has occurred in the overhead line according to the following judgment conditions:

For a fault indicator:

1) There is a sudden increase in transient capacitive current in the line of the phase where the fault indicator is located: the transient capacitive current at the moment of detection of grounding is greater than a certain value;

2) The grounding line voltage of the phase where the fault indicator is located drops by more than 3kV;

3) The line of the phase where the fault indicator is located is not powered off.

When the above three conditions are met at the same time, the fault indicator judges that a ground fault occurs behind the line where the fault indicator is located.

Compared with prior art, the advantages of the present invention are:

1. It can accurately calculate the data of the three-phase current and reproduce the current waveform at the time of the fault;

2. Compared with the traditional fault indicator, adding synchronous wave recording function and reproducing the current waveform at the time of fault can judge the ground fault more accurately;

3. It has a synchronous timing trigger device, more accurate synchronous timing, and more accurate calculation of zero-sequence voltage and current.

Description of drawings

Fig. 1 is a schematic diagram of the system structure of the present invention;

Fig. 2 is the schematic flow chart of fault recording of wireless synchronization technology of the present invention;

Fig. 3 is a schematic diagram of short-circuit current fault criterion;

Fig. 4 is a schematic diagram of ground fault detection criteria;

Figure 5 is a schematic diagram of a short circuit fault;

Fig. 6 is a schematic diagram of the wave recording result of a short-circuit fault;

Fig. 7 is a topological view of the line operation mode;

Figure 8 is a diagram of the line operation mode.

In the figure, 1 is the fault indicator, 2 is the monitoring communication terminal, 3 is the overhead line of the distribution network, 4 is the GPRS wireless network, 5 is the system master station, and 6 is the fault point.

detailed description

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

The traditional fault repair mainly learns that there is a fault on the line through dispatching or user repair, and then spends a lot of manpower and material resources on the line to check the line or arrange the fault point step by step, and then restore the power supply after the fault is processed. The blind distribution network fault handling method makes fault repair more passive, and it takes a lot of time to determine the fault point, which is time-consuming and laborious; especially for single-phase ground faults in the distribution network system, single-phase ground faults are difficult to find, and the accuracy of fault detection methods It is not high, and becomes the main factor affecting power outages.

In Fig. 1 and Fig. 2, this technical solution provides an online acquisition method of distribution line fault waveforms, including fault indicators installed on each monitoring point of distribution network overhead lines and a system master station set in the monitoring center, Its characteristics are:

On the A, B, C three-phase overhead lines 3 of several towers along the distribution network overhead lines, a fault indicator 1 is respectively set correspondingly, and the three fault indicators are respectively for the A, B, C three-phase lines Carry out fault monitoring and fault indication;

On the tower where the fault indicator is located, a monitoring communication terminal 2 is set;

The three fault indicators are set correspondingly to the monitoring communication terminals on the same tower, forming a group of distribution network fault on-site monitoring units;

A short-distance wireless communication network is set between the three fault indicators, and between the fault indicators and the monitoring communication terminal on the same tower;

Described monitoring communication terminal carries out long-distance wireless network connection with system main station 5 through GPRS wireless network 4;

On each overhead line of the distribution network from the substation to the power user, there are multiple groups of on-site fault monitoring units of the distribution network;

The communication monitoring terminal and the fault indicator use an ultrasonic or infrared auxiliary synchronous timing device to perform synchronous timing; when the communication monitoring terminal sends a timing command, the fault indicator on the three-phase line receives the trigger signal at the same time, and starts synchronous timing ;During the running process, periodically synchronize the time to keep the clock in the three-phase fault indicator under the condition of long-term operation of the fault indicator to maintain synchronization accuracy;

In Figure 2, during normal operation, the CPU of the fault indicator is in a dormant state. In this state, the AD module of the fault indicator performs high-speed sampling, and the real-time sampling data is transmitted to the internal memory of the fault indicator through the DMA module. The cache area keeps the latest data in a circular way, and the CPU is woken up within T intervals through a timing interrupt. After the CPU is woken up, it processes the sampled data stored in large quantities, and obtains the telemetry value of the three-phase line operation data;

During normal operation, the fault indicator detects the line fault of the corresponding phase line. When a fault occurs in one of the three-phase lines, the current of the faulty phase changes significantly, and the fault indicator immediately wakes up the CPU and records the fault at the current moment. Time scale and corresponding real-time sampling data; at this time, the fault indicator of the faulty phase line triggers the fault indicators of the other two phase lines, records the fault time scale and real-time sampling data of the corresponding phase line, starts data "wave recording", and Actively report the sampling data of the three-phase fault indicator with the fault time scale to the monitoring communication terminal; after the communication monitoring terminal calculates the deviation between the time scale reference of the line fault phase time scale and the time scale of the other two non-fault phase lines, it calls the time scale deviation phase again. The cycle sampling data of the fault indicator where it is located is transmitted to the communication monitoring terminal; the communication detection terminal transmits the sampled fault data to the system master station through the remote communication system, and the system master station reproduces the three-phase current waveform at the time of the fault through data fusion, and calculates Generate zero-sequence voltage and zero-sequence current to distinguish whether the line at the fault point is a ground fault or a short-circuit fault. According to the type of fault, corresponding measures are taken to effectively isolate the line fault and improve the accuracy of ground fault judgment.

When a single-phase line fault occurs, trigger the fault indicator on the faulty phase line to record the fault wave, collect the fault time scale and real-time sampling data, and simultaneously trigger the fault indicators on the other two-phase lines to record the fault time scale and real-time sampling data. The wave recording data is transmitted wirelessly according to the specified communication format. After the monitoring communication terminal receives the data frame, it extracts the non-fault current sampling data at the fault time from the previously sampled data with time stamps, and reproduces the current waveform at the fault time in time to judge the line more accurately. Fault. In the process of synchronously triggering the wave recording, it must be ensured that the fault indicator is in the wireless receiving state. Use the specified response mechanism to ensure that the link between the fault indicator and the monitoring communication terminal is normal.

This technical solution adopts short-distance wireless and long-distance wireless hybrid networking technology when monitoring the working conditions of the line, uses various network topologies, actively and regularly reports the fault status, and communicates and transmits bidirectional confirmation and retransmission, which has ensured the data transmission process. reliability. The fault transmission time of the fault indicator can be manually set, so that the real-time operation status of the line can be grasped more flexibly, and at the same time, it can effectively reduce the wireless communication traffic fee and ensure cost control.

The monitoring communication terminal is a bridge for the interaction between the fault indicator and the system master station. With the help of short-distance wireless and long-distance wireless hybrid networking technology, the monitoring communication terminal has the ability of channel monitoring, switching and fault alarm, and supports system diagnosis, self-healing and communication interruption. Data resume function after recovery. The monitoring communication terminal has wireless communication capability, and can modify equipment parameters and setting values through remote control. The highly reliable power supply system using solar energy and maintenance-free battery primary and backup power supplies ensures a stable and reliable system, and the staff of the main station can monitor the working condition information and fault information of the line in real time.

Specifically, the monitoring communication terminal uses the short-distance wireless network technology to receive the line fault information and load current data sent by the fault indicator, and supports the star topology network structure; with the help of the current VPN private network based on 2.5G/3G wireless network and the system main The station establishes communication, uploads the line operation data information to the main station, and realizes the monitoring of fault information and operating conditions of the power distribution network. The unit supports IEC101, IEC104 and other protocols, and can be extended. The industrial design of the communication module adopts industrial-grade wireless communication chips from international mainstream manufacturers. It has the functions of channel monitoring, channel switching and fault alarm, supports system diagnosis and self-healing, and supports data transmission after communication interruption and recovery to prevent data loss.

The master station software platform located in the monitoring master station relies on the big data comprehensive processing system to process and analyze the high-precision, high-sampling-rate current recording data and load current detection data by software, and obtain the results of power supply transfer and line topology adjustment. Harmonic current monitoring curve, and then analyze the process of fault occurrence and evolution, trace the source of the fault, accurately identify short-circuit and ground faults, and accurately locate the fault section. The monitoring master station will send the processed fault information and locate the fault section to the line inspection staff through GPRS communication to guide the fault inspection, operation and maintenance work, so as to improve the reliability of power supply.

With the help of the distribution line waveform comprehensive monitoring method and analysis technology based on big data, this technical solution can analyze line conditions including line faults, line losses, and power quality, and improve comprehensive and reliable data support for optimizing distribution network results.

It adopts analog and digital data acquisition and integration functions, and integrates online monitoring application software to realize telemetry, remote signaling, remote control and fault line protection functions.

Research has found that sampling via DMA can significantly increase system power consumption.

The technical solution combines the low power consumption characteristics of the CPU, and achieves a balance between system sampling and CPU power consumption through the method of time division multiplexing.

The fault indicator detects the fault of the line, which can prevent false operation and refusal to operate. After identifying the fault condition of the line, it can accurately detect phase-to-phase short-circuit, single-phase grounding, etc., and automatically determine the fault current alarm action value through signal processing and calculation; effectively prevent malfunctions and refusals caused by load fluctuations and closing excitation inrush currents; With inverse time-limit action characteristics, it cooperates with the protection characteristics of substations to the maximum extent, avoids instantaneous disturbances, and ensures correct actions.

When a fault occurs, use the ultra-bright LED installed inside the fault indicator to display the current working condition of the line through its 360° full-vision status indication and a combination of various flashing frequencies, reasonably judge the fault situation, and give feedback to the staff Do accordingly. After the line fault is eliminated and the power supply is restored, various reset methods can be used to automatically reset and reset the fault.

The fault indicator performs data processing and calculation on the collected data through the integrated monitoring software, and realizes the remote telemetry function. Its functional characteristics are as follows:

a) Direct collection of remote measurements: including analog quantities such as Ua, Ub, Uc, Ia, Ib, and Ic.

b) Calculate the following telemetry:

(1) Three-phase line electric field strength, load current, sudden change current, temperature, backup battery voltage, power supply voltage; zero-sequence current, zero-sequence voltage;

(2) frequency;

(3) Signal strength;

(4) The function can be set for the telemetry dead zone range;

(5) It has the function of storing historical data, the minimum storage interval is 30 seconds, and the storage capacity is greater than 30 days.

Under the condition of line autonomous operation, the fault indicator maintains operating parameters through remote wireless, updates fault criteria or upgrades software programs. This is convenient, flexible and maintainable.

The monitoring communication terminal in this technical solution mainly relies on 20W solar panels, super capacitors and maintenance-free lead-acid batteries to form a high-redundancy, high-reliability power supply system, and its communication with the main station mainly relies on the power 101 and 104 protocols. Support distributed feeder automation, and support switch remote signaling, telemetry, remote control semaphore and DC24V controllable remote signaling power supply/remote control power supply, switching power supply operation. When the monitoring communication terminal is in working condition, it is recommended to use AC power supply for power supply.

The monitoring communication terminal adopts low-power CPU and industrial-grade radio communication module, which realizes the communication and information exchange between the monitoring communication terminal and the fault indicator, the monitoring communication terminal and the system master station, and the real-time two-way communication function with extremely low power consumption .

The monitoring communication terminal has an optional built-in GPS timing module, which is equipped with a high-gain active antenna, and the timing accuracy can reach 1us. By using short-distance wireless for wireless timing and automatically calibrating the device clock, the line monitor can obtain an accuracy of ±100us Absolute time scale. When the time synchronization command cannot be received, it has the function of keeping time. Support GPS time synchronization, adaptive second pulse/minute pulse/B format.

The monitoring communication terminal can synthesize the current and electric field signals based on the three-phase current and electric field sampled by AC, and can realize accurate detection of ground faults on the spot, locate fault waveforms and upload them to the main station system for line fault analysis, inversion and traceability; Perform simple calculations such as merging of remote signaling signals.

The monitoring communication terminal samples solar panels as the main power supply, and uses a maintenance-free long-life rechargeable battery as a backup power supply. In the case of solar power supply, the priority is to use the solar power panel for power supply; in the absence of solar energy, use the backup power supply for power supply. The backup power supply can support the monitoring communication terminal to work continuously for 15 days in the communication state (the number of days and the selected backup battery Capacity related), no need to add energy. The built-in high-performance processor switches between main power and backup power based on real-time monitoring results of solar power panels and gel batteries.

The equipment for monitoring communication terminals can be easily upgraded through the remote maintenance master station, which supports batch and one-by-one automatic maintenance and upgrading of multiple monitoring communication terminals, and is safe and easy to operate. At the same time, it supports SMS management function. Each autonomous local autonomous feeder automation terminal system model can only contain a partial model, that is, it has and can only contain the switch information corresponding to the access distribution terminal and the adjacent switch information. When adding, deleting or adding a power distribution network, only the controller parameters of the corresponding site and the parameters of the electrical adjacent controllers need to be modified, and other controller parameters should not be changed.

The monitoring communication terminal can automatically realize fault location and fault online monitoring without the participation of the system master station, and has corresponding automatic action mechanisms for different feeder protection and primary equipment.

When the line is short-circuited, grounding, power failure, power transmission and other operating conditions change, the fault indicator detects the changed signal and judges whether the line is faulty. Instructions are given on the spot.

The monitoring communication terminal adopts short-distance wireless and long-distance wireless hybrid networking technology to support complex network line topology; it actively and regularly reports the line working status at regular intervals (the reporting time can be set by itself), and has two-way confirmation and resetting of communication transmission. Transfer function to ensure reliability during data transmission. Control the real-time running status of the line at any time, prevent the phenomenon of waking up every day and sleeping all day, and at the same time reduce the GPRS traffic charges. At the same time, the line displays the current working condition through a combination of multiple flashing frequencies, and it can be automatically reset after the power supply is eliminated; the fault status can be automatically reset and set by manual or wireless networking.

The fault indicator transmits the monitored information such as short circuit, grounding, power failure, power supply, current and temperature to the monitoring communication terminal through short-distance radio frequency signals, and then sends the information to the working master station through the monitoring communication terminal through GSM/GPRS. Through the flickering of the color of the line, it is visually displayed to determine the section where the fault is located, and at the same time, a dialog box pops up to prompt an alarm, and the fault point information is sent to the mobile phone of the inspector in the form of a short message.

In Figure 3, when a phase-to-phase short circuit occurs in the distribution line, a large current will flow in the circuit between the substation and the fault point, the relay protection device will start protection, and the line will trip. Based on the above circumstances, the short-circuit fault criterion has the following four conditions:

For a fault indicator:

1) The line in front of the fault indicator has power;

2) There is an abrupt current It ≥ 200A in the line where the fault indicator is located, and It is the sudden current start;

3) The duration of high current in the line of the phase where the fault indicator is located is 0.02s≤△T≤3s, and △T is the current mutation time;

4) The line behind the fault indicator is powered off;

When the above four conditions are satisfied at the same time, the distribution network fault monitoring method detects and judges that a short-circuit fault occurs in the line behind the fault indicator.

The concept of "front" and "back" of the fault indicator here is to describe the line between the substation and a certain fault indicator as the "front" of the fault indicator, and connect a certain fault indicator to the power consumption It is customary in the industry to describe the line between the terminals as being "behind" the fault indicator.

It adopts the principle of quick-break overcurrent two-stage current protection, and simultaneously detects the operating status of the line, which can effectively suppress the closing, reclosing inrush current and feedback power transmission misoperation. The parameters can be adjusted online, and the detection is more sensitive and reliable. If the parameters of quick-break and over-current setting are set to 700A, and the parameters of quick-break and over-current delay remain unchanged, it will be converted into an over-current mutation criterion for adaptive load current.

In Figure 4, when the line is single-phase grounded, a variety of complex transient phenomena will appear according to different grounding conditions (such as metallic grounding, high-impedance grounding, etc.), including the distributed capacitance discharge current of the line to ground, grounding Line-to-ground voltage drops. Based on the above circumstances, the grounding criterion is as follows:

For a fault indicator:

1) There is a sudden increase in transient capacitive current in the line of the phase where the fault indicator is located: the transient capacitive current at the moment of detection of grounding is greater than a certain value;

2) The grounding line voltage of the phase where the fault indicator is located drops by more than 3kV;

3) The line of the phase where the fault indicator is located is not powered off.

When the above three conditions are satisfied at the same time, the distribution network fault monitoring method detects and judges that a ground fault occurs behind the line where the fault indicator is located.

After a grounding fault occurs on the line, it will turn over and display on the spot, and transmit the fault information to the main station of the system.

By obtaining the zero-sequence current on the entire distribution network line before and after the fault moment, and performing network analysis, it is possible to detect and locate single-phase ground faults in small current grounding systems.

When the single phase-to-ground electric field suddenly rises or falls and exceeds a certain ratio, and the phase current changes in a special mode, the wave recording will be triggered.

In this technical solution, the intelligent fault indicator of the overhead line of the distribution network detects the short-circuit fault on the spot, patrols the line and locates it, and the master station of the distribution network automation locates it according to the remote signal of the short-circuit fault. The short circuit fault location is shown in Figure 5.

The result of field recording of short-circuit fault is shown in Fig. 6.

In the process of ground fault processing, the wave recording results of the short-circuit fault of the ground fault line are shown in Figure 7. It can be seen that there is a high-frequency zero-sequence current in the phase line (called the fault phase) where the ground fault occurs in the overhead line. In the transient process, the fault indicator captures this high-frequency transient zero-sequence current signal, and cooperates with the zero-sequence electric field signal to realize the function of detecting small current grounding faults on the spot.

In this technical solution, regardless of whether the small-current grounding distribution network adopts the ungrounded mode or the arc-suppression coil grounding mode, a transient process with a duration of 5 to 20 milliseconds will be generated at the moment of fault occurrence. During the period, a high-frequency transient signal with a large amplitude will be generated on the zero-sequence current i ₀ .

According to the same method of locating short-circuit faults, the master station can locate the place where the small-current grounding fault occurs according to the remote signaling signal of the small-current grounding fault.

As shown in Figure 8, the transient zero-sequence current waveforms of the faulty line and the non-faulty line are not similar;

The transient zero-sequence current waveform on the fault current path on the fault line is similar;

The transient zero-sequence current waveforms on the fault current path and non-fault current path on the fault line are not similar.

Accordingly, the technical solution can realize the function of network detection and positioning.

In other words, when a short circuit occurs in a certain line, and the operating status of grounding, power failure, and power transmission changes, each fault indicator on the line detects the changed signal and judges whether the line is faulty. All indicators on the line along the fault circuit of the substation will act and give instructions on the spot.

This technical solution includes functional modules such as power signal acquisition, fault detection, fault recording, information remote transmission, always synchronous, and ultra-low power consumption control, which can realize fault recording and data remote transmission functions. Based on the online fault recording data of the device, it analyzes the different characteristics of the data waveforms of adjacent devices when a fault occurs, effectively judges short-circuit and ground faults, and locates the fault point. Using the single-phase ground fault location algorithm, a breakthrough has been made in the field of fault online detection. At the same time, this technical solution can greatly improve the reliability and efficiency of distribution network operation, improve power supply quality, reduce labor intensity and make full use of existing equipment. capacity, which can bring considerable benefits to both users and power companies.

This technical solution synchronously collects the fault data of the fault current of each section of the line through the fault indicator, and reproduces the three-phase current waveform at the time of the fault. It can calculate the zero-sequence voltage and current through the protection algorithm of the relay protection system, and assist in judging the ground fault, greatly Improve the accuracy of ground fault judgment, quickly locate and find protection line faults, and detect line operating loads; it can lay a technical foundation for the large-scale application of distribution automation, and has a great impact on improving the practical operation level of on-site distribution automation. theoretical research value and practical application value. It is especially suitable for the automation construction mode of distribution network in small and medium cities or the supplementary project of distribution network automation transformation in large cities.

Claims (7)

1. a kind of online acquisition method of distribution line failure waveform, including on each monitoring point of electric distribution network overhead wire Fault detector and be arranged on the system main website of Surveillance center, it is characterized in that：

On A, B, C three-phase overhead transmission line of electric distribution network overhead wire on the way several shaft towers, a failure is correspondingly arranged respectively Indicator, three described fault detectors carry out malfunction monitoring and indicating fault to A, B, C three-phase line respectively；

On the shaft tower that fault detector is located, a monitoring communication terminal is set；

Three described fault detectors are correspondingly arranged with the monitoring communication terminal on same tower bar, are constituted one and are assembled electric network fault now Field monitoring means；

Between three described fault detectors, and fault detector and between the monitoring communication terminal on tower bar, arrange There is short-distance wireless communication network；

Described monitoring communication terminal Jing GPRS wireless networks carry out remote-wireless network connection with system main website；

From transformer and distribution station to the electric distribution network overhead wire between power consumer, multigroup described power distribution network event is being provided with per bar Barrier field monitoring unit；

Described communication monitoring terminal is synchronized and is awarded using ultrasound wave or infrared assist in synchronization time service device with fault detector When；When communication monitoring terminal sends time service order, the fault detector on three-phase line receives trigger, and open simultaneously Begin synchronous pair when；In running, when periodically synchronizing pair, to keep three in the case of fault detector longtime running Clock in phase fault indicator keeps synchronization accuracy；

In normal operation, in a dormant state, under this state, the A/D module of fault detector carries out height to the CPU of fault detector Real-time sampled data is transmitted to the built-in storage of fault detector, the buffer area of built-in storage by speed sampling by dma module Preserve newest data by way of circulating rotation always, CPU is waken up in T intervals by Interruption, and CPU is waken up The sampled data stored in a large number by post processing, obtains the telemetry value of three-phase line service data；

In normal operation, the line fault of fault detector detection correspondence phase line has a phase in three-phase line is detected During line failure, there is significant change in faulted phase current, and fault detector wakes up CPU therein immediately, when recording current Carve failure markers and corresponding real-time sampling data；Now, the fault detector of failure phase line triggers other two phase line Fault detector, record failure markers and correspondence phase line real-time sampling data, start data " record ripple ", and will with it is faulty when Target three-phase fault indicator sampled data active reporting monitors communication terminal；Communication monitoring terminal-pair line fault phase markers base After the accurate markers with other biphase non-faulting phase line calculates deviation, markers deviation is called again to be mutually located fault detector Cycle sampled data is transmitted to communication monitoring terminal；The fault data sampled is passed by communication check terminal by telecommunication system System main website is transported to, main station system reappears the three-phase current waveform of fault moment by data fusion, and calculates residual voltage With zero-sequence current, it is earth fault or short trouble to distinguish trouble point circuit, according to the difference of failure mode, takes corresponding Measure is effectively isolated line fault, improves the accuracy that earth fault judges.

2., according to the online acquisition method of the distribution line failure waveform described in claim 1, described relief area it is characterized in that The three-phase line service data of 10s can be stored.

3., according to the online acquisition method of the distribution line failure waveform described in claim 1, it is characterized in that described T intervals are little In 10s.

4. according to the online acquisition method of the distribution line failure waveform described in claim 1, it is characterized in that described short distance without Line communication network at least includes Zigbee networkings or Wi-Fi WLANs.

5., according to the online acquisition method of the distribution line failure waveform described in claim 1, it is characterized in that described failure refers to Show the electric current of device real-time monitoring circuit and to earth electric field, detect short trouble on the spot, and in circuit curtage ANOMALOUS VARIATIONS When triggering record ripple, by the communication check terminal on the shaft tower, by short trouble remote signals and record waveform with remote signalling The form of signal is uploaded to system main website, and system Master Station Software carries out short trouble positioning according to remote signals, and according to record ripple Waveform carries out Earth Fault Detection positioning to electric distribution network overhead wire, instructs O＆M service work, improves the reliability of electrical network.

6., according to the online acquisition method of the distribution line failure waveform described in claim 1, it is characterized in that described failure refers to Show according to following Rule of judgment, device judges whether overhead transmission line there occurs short trouble：

For certain fault detector：

1) circuit before fault detector has electricity；

2) fault detector occurs being mutated electricity It >=200A in the line, and It is Sudden Changing Rate current start；

3) high current persistent period 0.02s≤Δ T≤3s in the circuit of fault detector place phase, Δ T are the current break time；

4) fault detector line outage below；

More than, four conditions meet simultaneously, and described fault detector detection judges the fault detector position below There is short trouble in circuit.

7., according to the online acquisition method of the distribution line failure waveform described in claim 1, it is characterized in that described failure refers to Show according to following Rule of judgment, device judges whether overhead transmission line there occurs earth fault：

For certain fault detector：

1) there is the transient state capacitance current of unexpected increase in the circuit of fault detector place phase：The transient state electric capacity of detection ground connection moment Electric current is more than certain numerical value；

2) the ground path voltage of fault detector place phase reduces more than 3kV；

3) circuit of fault detector place phase does not have a power failure.

When three above condition meets simultaneously, then after described fault detector judges the circuit of the fault detector position There is earth fault in face.