CN104764970A - Power distribution fault judgment method based on real-time topology - Google Patents

Abstract

The invention discloses a power distribution fault judgment method based on real-time topology. The method includes: when the current load current is twice the normal load current, judging whether the current load current is greater than the magnitude of the quick-break threshold current within t1 time; if so, Then it is determined that a short-circuit fault has occurred; otherwise, it is further judged within the time t2 whether the current load current is greater than the overcurrent threshold current; , it is determined that a ground fault has occurred; after a delay of t3, a different frequency signal is injected into the line and the fault current is detected after a time delay of t4; after a short circuit fault or a ground fault is determined, the fault indicator sends the fault information and The current information is sent to the monitoring master station to analyze the fault point. It can monitor the load and fault information of each sub-line of the distribution network in real time, and judge whether there is a short-circuit fault or a ground fault in the distribution line.

Description

A Real-time Topology-Based Power Distribution Fault Judgment Method

technical field

The invention relates to the field of electronic power technology, in particular to a real-time topology-based power distribution fault judgment method.

Background technique

The power line is the lifeblood of the power grid operation. It is quite fragile while transmitting electric energy. Any damage from external forces and wrong operations by the staff may cause large-scale power outages, or even the collapse of the power grid. cause great harm. Therefore, research on online detection and diagnosis methods of power lines is of great significance for timely handling of faults, restoring the normal operation of the system, maintaining the safety of the power system and the economic interests of users. At home and abroad, there are many researches on the online detection and diagnosis of transmission lines, but less research on distribution lines, and the emphasis is on the diagnosis and location of line faults, which belongs to offline fault diagnosis. Existing monitoring devices and positioning devices cannot monitor the operating status of distribution lines in real time, nor can they effectively detect and diagnose instantaneous faults in the line, let alone predict early faults in the line. If some early faults of distribution lines cannot be eliminated in time, they are likely to develop into short-circuit faults and cause harm to the safe operation of the power system.

Contents of the invention

The purpose of the present invention is to solve the defects existing in the prior art, monitor the operating state of the distribution line in real time, make effective detection and diagnosis of the instantaneous fault of the line, and eliminate the early fault of the line in time.

An embodiment of the present invention provides a real-time topology-based power distribution fault judgment method, including:

The load current is detected in real time by multiple fault indicators installed on the three-phase lines of the distribution network; when the current load current is twice the normal load current, it is judged within t1 whether the current load current is greater than the magnitude of the quick-break threshold current; if so , it is determined that a short-circuit fault has occurred; otherwise, it is further judged within the time t2 whether the current load current is greater than the overcurrent threshold current; if so, it is determined that a short-circuit fault has occurred;

The three-phase circuit voltage is detected in real time through the special frequency source injection device; when it is detected that the voltage of the two-phase line increases and the voltage of the third phase line decreases, it is determined that a ground fault occurs; after a delay of t3, it is injected through the special frequency source The device injects a different frequency signal into the line and detects the fault different frequency current through the fault indicator after a time delay of t4; wherein, t3<t4;

After determining that a short-circuit fault or a ground fault occurs, the fault indicator sends fault information and load current information to the monitoring master station, and the monitoring master station analyzes the fault point.

Further, during the time delay t3, the special frequency source injecting device is used to regularly detect whether the line voltage is abnormal.

Further, during the time delay t4, whether the line voltage is abnormal is regularly detected by the special frequency source injection device.

Further, t1=40 milliseconds, t2=200 milliseconds, 3.5≤t3≤4 minutes, 4≤t4≤4.5 minutes, and the injection time of each special frequency signal is 2 minutes.

Further, the detection of the fault variable frequency current through the fault indicator specifically includes: continuously detecting multiple sets of data through the fault indicator, and using the group with the smallest value of the variable frequency as the fault variable frequency current.

Further, the inter-frequency signal is a low-frequency signal of a special frequency.

Further, the fault indicator is a digital judger.

Further, the fault indicator sending the fault information and load current information to the monitoring master station specifically includes: the fault indicator transmits the fault information and load current information to the data centralized transmitter through wireless radio frequency, and the data centralized The transmitter packs the data and communicates with the monitoring master station in the background through the repeater through the mobile public network.

Further, the centralized data transmitter includes a high-voltage energy harvesting device, a data storage device, and a storage battery; the high-voltage energy harvesting device is used for directly inductively harvesting energy on the distribution network line to supply power for the centralized data transmitter, and through the storage battery storing electric energy; the data memory is used for storing fault information and load current.

Further, the high-voltage energy harvesting device is an LC series induction energy harvesting device.

Implementing the embodiment of the present invention has the following beneficial effects: a real-time topology-based power distribution fault judgment method provided by the embodiment of the present invention can monitor the distribution network by using multiple fault indicators installed on the three-phase lines of the distribution network The load and fault information of each sub-line can be judged whether there is a short-circuit fault in the distribution line through the quick-break overcurrent method, and the grounding fault can be intelligently judged by the method of special frequency injection and detection of line voltage change; the load information and fault information are sent back to the monitoring master station to realize the collection of load information and fault information of power distribution; by monitoring the main station to analyze the load current information and fault information, the location of the fault point can be obtained, so that the relevant line operation and maintenance personnel can be notified in time to isolate the fault section in time, so as to achieve The purpose of quick troubleshooting.

Description of drawings

Fig. 1 is a flowchart of a power distribution fault judgment method based on real-time topology provided by an embodiment of the present invention;

Fig. 2 is a schematic structural diagram of a distribution network fault monitoring system implementing a real-time topology-based power distribution fault judgment method according to an embodiment of the present invention;

Fig. 3 is a short-circuit fault circuit diagram of a distribution network provided by an embodiment of the present invention;

Fig. 4 is a circuit diagram of a single-phase ground fault in a distribution network provided by an embodiment of the present invention.

Detailed ways

The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only some, not all, embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without creative efforts fall within the protection scope of the present invention.

Referring to FIG. 1, it is a flow chart of a real-time topology-based power distribution fault judgment method provided by an embodiment of the present invention, including the following steps:

S1: Real-time detection of load current through multiple fault indicators installed on the three-phase lines of the distribution network;

S2: When the current load current is greater than double the normal load current, judge whether the current load current is greater than the magnitude of the quick-break threshold current within t1; if so, determine that a short-circuit fault has occurred; otherwise, enter step S3;

S3: Determine whether the current load current is greater than the overcurrent threshold current within the time t2; if so, determine that a short circuit fault has occurred; enter step S7;

S4: Real-time detection of three-phase circuit voltage through the special frequency source injection device;

S5: When it is detected that the voltage of two phase lines increases and the voltage of the third phase line decreases, it is determined that a ground fault occurs;

S6: After a time delay of t3, inject a different frequency signal into the line through the special frequency source injection device and detect the fault different frequency current through the fault indicator after a time delay of t4; wherein, t3<t4;

S7: After determining that a short-circuit fault or a ground fault occurs, the fault indicator sends fault information and load current information to the monitoring master station, and the monitoring master station analyzes the fault point.

Referring to FIG. 2 , it is a schematic structural diagram of a distribution network fault monitoring system implementing a real-time topology-based power distribution fault judgment method according to an embodiment of the present invention.

In this embodiment, the distribution network fault monitoring system includes: a plurality of fault indicators, a centralized data transmitter 100 , a repeater 200 , a monitoring master station 300 and a special frequency source injection device 400 .

The fault monitoring system shown in FIG. 2 shows at least 15 fault indicators, and the fault indicators are installed on the three-phase lines of the distribution network one by one.

Each fault indicator is equipped with a set of wireless radio frequency devices, and each wireless radio frequency device can form a wireless local area network, and transmit fault information and load current information to the data centralized transmitter 100 through wireless radio frequency, and the data centralized transmitter 100 transmits the data Packing, through the repeater 200 through the mobile public network to communicate with the monitoring master station 300 in the background.

In specific implementation, each fault indicator installed on the three-phase line of the distribution network is preferably a digital judger, and an insulated operating rod is used for live loading and unloading, no special tools are required, and the construction and maintenance are simple and convenient. In addition, each fault indicator can detect the load current of the line, and is equipped with a timing automatic sending device and a recalling device to facilitate the acquisition of load changes in the distribution network, accurate fault judgment, and reduce the blindness of fault finding. Furthermore, each fault indicator preferably adopts a maintenance-free self-charging power supply, which has a long service life.

The centralized data transmitter 100 and the repeater 200 are integrated devices, which are integrated into one hardware device to facilitate the receiving and sending of distribution network data.

The centralized data transmitter 100 includes a high voltage energy harvesting device 101 , a data storage 102 and a storage battery 103 . The combined power supply mode of the high-voltage energy harvesting device 101 and the storage battery 103 can effectively guarantee the continuous and uninterrupted normal operation of the data centralized transmitter 100 . Wherein, the high-voltage energy harvesting device is preferably an LC (inductance/capacitance) series inductive energy harvesting device, and the LC series inductive energy harvesting device also includes a backup power supply; the backup power supply is a disposable high-capacity lithium battery . The centralized data transmitter 100 can directly induct energy from the distribution network line for power supply through the LC series inductive energy harvesting device, and the storage battery 103 can be used as a backup power source, which can be activated when the distribution network line fails and the power is cut off. The LC series induction energy harvesting device has the advantages of not being affected by the weather, not being affected by the line load, small size and low cost, and also has the function of voltage measurement. The entire energy harvesting device is safe, reliable, and maintenance-free for life.

The data storage 102 may preferably be a DataLog database, which can locally cache second-level data of more than one month and minute-level data of more than one year. When the communication is abnormal, the data stored in the local data storage 102 will not be lost, and after the recovery of the communication is detected, the untransmitted data will be transmitted step by step, ensuring the high reliability of communication and data.

The repeater 200 communicates with the fault indicator through a radio frequency device, and communicates with the monitoring master station 300 through a mobile communication transceiver terminal P.

The centralized data transmitter 100 and the repeater 200 can be integrated into a repeater in a broad sense, which can communicate with the front-end fault indicator through RF (radio frequency) mode, and can also be connected with the background monitoring master station 300 by mobile Communication connection via public network, small size, light weight, easy loading and unloading.

The main functions of the monitoring master station 300 in the background are data collection, monitoring and control. The monitoring master station 300 locates data such as single-phase ground fault and phase-to-phase short-circuit fault section by receiving the line load and voltage transmitted by the front-end collector, and can send control commands to read real-time data, remotely control the opening and closing of the circuit breaker, and remotely modify Protection setting value, parameters of front-end acquisition device.

The monitoring master station 300 can be independently installed in the distribution network dispatching center, or it can be combined with the original main network dispatching system through a standard communication protocol, and a man-machine interface is added. The dispatcher can fully grasp the operation of the distribution network through the man-machine interface Condition.

The special frequency source injection device 400 is used to detect single-phase ground fault conditions in the distribution network.

Referring to FIG. 3 , it is a circuit diagram of a short-circuit fault circuit of a distribution network provided by an embodiment of the present invention.

When judging a short-circuit fault, each fault indicator in Figure 2 detects the load current respectively. When the sudden change of the load current is greater than twice the normal load (such as greater than 100A), continue to judge by the quick-break overcurrent method: at t1 (such as 40ms) time to judge whether the current load current is greater than the magnitude of the quick-break threshold current; Short circuit fault.

In Figure 3, if a short-circuit fault occurs at point D, the fault indicators 2, 5, 8 and 3, 6, and 9 of the circuit where the short-circuit fault point D is located will indicate that a short-circuit fault occurs in the circuit in this area, and report to the fault information 1. The load current information will be transmitted to the centralized data transmitter 100 through wireless radio frequency, and the centralized data transmitter 100 will pack the data, and communicate with the monitoring master station 300 in the background through the repeater 200 through the mobile public network. The station 300 analyzes the short-circuit fault point.

Referring to FIG. 4 , it is a single-phase-to-ground fault circuit diagram of a distribution network provided by an embodiment of the present invention.

When the special frequency source injection device 400 detects that the voltage of the two-phase line increases and the voltage of the other phase line decreases, it is considered that the line has a single-phase grounding, and after a certain time delay (such as 3.5 to 4 minutes), the signal generating device is used to inject 220Hz into the line Inter-frequency signal, the inter-frequency signal is a low-frequency signal of a special frequency (the low-frequency signal is mainly used to reduce the attenuation of the detection signal by the distributed capacitance of the line), and the data concentration and transmission unit will also detect voltage changes, delay After another period of time (such as 4 to 4.5 minutes), send a command to detect the different frequency signal to the fault indicator. After the fault indicator continuously detects multiple groups (such as 5 groups) of data, it will use the group with the smallest value of the frequency difference as the fault frequency. The current is sent to the centralized data transmitter 100. After a ground fault power outage, the special frequency source injection device 400 can be forcibly ordered to output a different frequency signal to check for a line fault again.

As shown in Figure 4, if a ground fault occurs at point D, after the special frequency source injection device 400 injects different frequencies, the different frequency currents detected by No. 3, 6, and 9 fault indicators constitute a fault circuit; After sending back to the monitoring master station 300, the monitoring master station 300 judges the fault point after intelligently analyzing the fault data.

Implementing the embodiment of the present invention has the following beneficial effects: a real-time topology-based power distribution fault judgment method provided by the embodiment of the present invention can monitor the distribution network by using multiple fault indicators installed on the three-phase lines of the distribution network The load and fault information of each sub-line can be judged whether there is a short-circuit fault in the distribution line through the quick-break overcurrent method, and the grounding fault can be intelligently judged by the method of special frequency injection and detection of line voltage change; the load information and fault information are sent back to the monitoring master station to realize the collection of load information and fault information of power distribution; by monitoring the main station to analyze the load current information and fault information, the location of the fault point can be obtained, so that the relevant line operation and maintenance personnel can be notified in time to isolate the fault section in time, so as to achieve The purpose of quick troubleshooting.

Those of ordinary skill in the art can understand that all or part of the processes in the methods of the above embodiments can be implemented through computer programs to instruct related hardware, and the programs can be stored in a computer-readable storage medium. During execution, it may include the processes of the embodiments of the above-mentioned methods. Wherein, the storage medium may be a magnetic disk, an optical disk, a read-only memory (Read-Only Memory, ROM) or a random access memory (Random Access Memory, RAM), etc.

The above description is a preferred embodiment of the present invention, and it should be pointed out that for those skilled in the art, without departing from the principle of the present invention, some improvements and modifications can also be made, and these improvements and modifications are also considered Be the protection scope of the present invention.

Claims (10)

1. A power distribution fault judgment method based on real-time topology, characterized in that, comprising: The load current is detected in real time by multiple fault indicators installed on the three-phase lines of the distribution network; when the current load current is twice the normal load current, it is judged within t1 whether the current load current is greater than the magnitude of the quick-break threshold current; if so , it is determined that a short-circuit fault has occurred; otherwise, it is further judged within the time t2 whether the current load current is greater than the overcurrent threshold current; if so, it is determined that a short-circuit fault has occurred; The three-phase circuit voltage is detected in real time through the special frequency source injection device; when it is detected that the voltage of the two-phase line increases and the voltage of the third phase line decreases, it is determined that a ground fault occurs; after a delay of t3, it is injected through the special frequency source The device injects a different frequency signal into the line and detects the fault different frequency current through the fault indicator after a time delay of t4; wherein, t3<t4; After determining that a short-circuit fault or a ground fault occurs, the fault indicator sends fault information and load current information to the monitoring master station, and the monitoring master station analyzes the fault point. 2. The method for judging distribution faults based on real-time topology according to claim 1, characterized in that, within the time delay t3, whether the line voltage is abnormal is regularly detected by the special frequency source injection device. 3. The real-time topology-based power distribution fault judgment method according to claim 1 or 2, characterized in that, within the delay time t4, the special frequency source injection device is used to regularly detect whether the line voltage is abnormal. 4. The power distribution fault judgment method based on real-time topology as claimed in claim 3, characterized in that, t1=40 milliseconds, t2=200 milliseconds, 3.5≤t3≤4 minutes, 4≤t4≤4.5 minutes, and each time The time of inter-frequency signal injection is 2 minutes. 5. The method for judging distribution faults based on real-time topology as claimed in claim 4, wherein the detection of the fault-different-frequency current by the fault indicator specifically comprises: continuously detecting multiple sets of data by the fault indicator , take the group with the smallest difference frequency value as the fault difference frequency current. 6 . The real-time topology-based power distribution fault judgment method according to claim 1 , wherein the different-frequency signals are low-frequency signals of special frequencies. 7 . 7. The real-time topology-based power distribution fault judgment method according to claim 1, wherein the fault indicator is a digital judger. 8. The power distribution fault judgment method based on real-time topology as claimed in claim 1, wherein the fault indicator sending fault information and load current information to the monitoring master station specifically comprises: the fault indicator sending the fault information Information and load current information are transmitted to the centralized data transmitter through wireless radio frequency. The centralized data transmitter packs the data and communicates with the monitoring master station in the background through the mobile public network through the repeater. 9. The power distribution fault judgment method based on real-time topology as claimed in claim 8, wherein the centralized data transmitter includes a high-voltage energy harvesting device, a data storage device and a storage battery; The direct induction on the grid line provides power for the centralized data transmitter, and stores electric energy through the storage battery; the data memory is used to store fault information and load current. 10. The real-time topology-based power distribution fault judgment method according to claim 9, wherein the high-voltage energy harvesting device is an LC series inductive energy harvesting device.