CN201234125Y - Single-phase grounding failure automatic processing equipment for low current grounding system - Google Patents

Abstract

A single-phase grounding fault automatic processing device for a small-current grounding system relates to the field of electric power system, in particular to the single-phase grounding fault automatic processing and control field for the small-current grounding system. The signal output terminal of a PT analog quantity input module is connected with a signal input terminal of an A/D conversion module; the signal output terminal of the A/D conversion module is connected with the first input terminal of a data buffer module; the first output terminal of the data buffer module is connected with the input terminal of a trip output module; the second output terminal of the data buffer module is connected with the input terminal of a blocking circuit protection reclosure output module; and the third output terminal of the data buffer module is connected with the input terminal of a host computer. The single-phase grounding fault automatic processing device can be used for compensating for the trip result simultaneously in combination with the automatic reclosure function in the circuit protection so as not to influence the users from the switch tripping to the closing of the protection reclosure switch when the tripped circuit is non-fault circuit.

Description

Automatic processing device for single-phase grounding fault in small current grounding system

technical field

The utility model relates to the field of power systems, in particular to the field of automatic processing and control of single-phase grounding faults in small current grounding systems.

Background technique

There are some relatively mature automatic line selection devices for small current ground faults in our country. The principles and methods adopted by each manufacturer are different. In summary, there are mainly two types: Type I mainly uses the fault amount generated by the system when the line ground fault occurs, such as The zero-sequence voltage generated by the busbar, the zero-sequence current of the grounding line and the zero-sequence current and zero-sequence voltage of the non-grounding line are equal to each other to analyze that the grounding fault occurs in a certain line. Type II mainly uses the external input signal method, that is, when a ground fault occurs in the system, an external device is used to input the signal source, and by detecting the feedback signal of each line, it is analyzed that the ground fault occurs in a certain line. Although the principles of the two methods are different, they have one thing in common, which is to first select the ground fault line, and then send out a line grounding alarm signal to notify the dispatcher and operating personnel to deal with it.

The disadvantages of the above two types of methods:

1. Due to the complexity of the ground fault, especially in the small current grounding system, when the line is short and the overall zero-sequence current is small, sometimes the line selection result is not accurate. In the early 1990s, the small current line selection device was widely used in China. However, due to the low sensitivity and accuracy of the products, most line selection devices were withdrawn from operation in the late 1990s. Because it often happens that when the dispatcher pulls the corresponding line according to the line selection result during operation, he needs to send the line again after finding that it is incorrect, and the power will be cut off for about 3 minutes before and after, causing unnecessary power outages for users.

2. When the on-duty dispatcher is busy with operating tasks, due to the large number of substations under his jurisdiction, he often cannot find the alarm information in time, thus delaying the processing time. Although the ground fault can run for about 2 hours (when the cable length is short), it often causes long-term overvoltage in the system and causes busbar PT damage. fault range.

3. Now the substations implement the unattended mode. When the communication network fails, remote control operation will not be possible. Operators need to go to the substation site to pull the faulty line. Although the fault can be isolated, the time for troubleshooting is delayed.

Contents of the invention

The purpose of the utility model is to provide an automatic reclosing function that can cooperate with the line protection to remedy the tripping result. When the jumping line is a non-fault line, it only takes 2 seconds from the switch trip to the protection reclosing switch closing, which is basically wrong. Users are affected; the capacitor does not use reclosing to remedy, and the single-phase grounding fault automatic processing device of the small current grounding system is manually restored.

For realizing the above object, the utility model adopts the following technical solutions:

The signal output terminal of the PT analog quantity input module of the utility model is connected with the signal input terminal of the A/D conversion module, and the system parameter analog quantity collected by the PT analog quantity input module is converted into a digital quantity; the signal output of the A/D conversion module end is connected with the first input end of the data buffer module to realize buffer processing; the output end of the switch position input module is connected with the second input end of the buffer module to realize the buffer processing of the switch position signal; the first output end of the data buffer module is connected with The input terminal of the trip output module is connected to realize the trip protection of the line switch; the second output terminal of the data buffer module is connected to the input terminal of the blocking line protection reclosing output module to realize the blocking and reclosing command of the protection switch; the data buffering The third output terminal of the module is connected with the input terminal of the host computer to realize the data exchange between the host computer and the data buffer module; the first input terminal of the host computer is connected with the output terminal of the 4M crystal oscillator to provide the working frequency for the host computer; the second input terminal of the host computer The terminal is connected to the output terminal of the external trigger module to realize the software operation as required; the third input terminal of the host is connected to the output terminal of the remote data transmission module to transmit the grounding alarm signal; the host is respectively connected to the keyboard module and the liquid crystal display module The connection realizes the input and real-time display of the control signal.

The utility model adopts the above-mentioned technical scheme, and has the following advantages compared with the prior art:

1. All line microcomputer protection devices of this utility model have the function of non-corresponding start reclosing.

2. The switch is in the opening or closing position. Because the switch is in a high voltage state, the power system is judged by detecting the position of the auxiliary contact of the switch. The position of the auxiliary contact is strictly consistent with the position of the switch. When the switch is in the closed position, the auxiliary normally open contact of the switch is in the off position, and the auxiliary normally closed contact is in the closed position; when the switch is in the closed position, the auxiliary normally open contact of the switch is in the closed position, and the auxiliary normally closed contact is in the closed position.

3. All 10kV, 20kV, 35kV line microcomputer protections in the power system have two functions related to this device. ①. The trip command of the external protection device or other automatic device can be connected to its own opening circuit. The line protection device only needs a pair of empty contacts provided by the external protection device or other automatic device, and the power supply is provided by the line protection itself. When the external protective device or other automatic device's empty contact is closed, the power supply will connect the protective opening circuit through the empty contact to trip the switch. The purpose of this is to avoid multiple sets of devices independently controlling the same switch, causing wiring It is very complicated and increases the security risk at the same time. ② After the line switch is opened, the protection device of the line itself does not trip at the outlet, and there is no manual hand jump (including remote operation) signal, and at the same time, no blocking and reclosing commands input by external protection devices or other automatic devices are received, and the protection of the line itself The device considers the switch to be tripping secretly, and will start the "non-corresponding reclosing" to close the switch 2 seconds after the switch trips.

4. Capacitor switch protection device in power system without reclosing function. Because after the capacitor protection action trips, it means that the capacitor or cable must be faulty, and there is no instantaneous fault such as lightning strike on the line that needs to be reclosed once. All capacitor protections do not use the recloser function.

Compared with the prior art, the utility model uses the zero-sequence overvoltage generated by the busbar during the ground fault as the only characteristic quantity for tripping, and uses the zero-sequence overvoltage as the fault action quantity for tripping of all lines. If the line selection idea is not used, the zero-sequence overvoltage value is greater than the action value (generally 40V ~ 60V), and the delay requirement is met, then the line will be tripped, and the tripping result will be remedied with the automatic reclosing function in the line protection; Capacitor does not use reclosing remedy, it is restored manually. The device realizes the function of automatic tripping and isolation of ground faults, real-time and rapid processing of ground faults, and ensures the safe and stable operation of non-fault systems.

Description of drawings

Fig. 1 is a kind of structural representation of the utility model.

Fig. 2 is a schematic circuit diagram of the utility model.

Detailed ways

As shown in Figure 1, the utility model device mainly has the following several functional modules. PT analog input module 1 is responsible for collecting system AC parameters; A/D conversion module 2 is responsible for converting analog quantities into digital quantities; switch position input module 4 is responsible for inputting switch position signals, allowing the device to identify whether the switch of the corresponding line is on It is used as the basis for judging whether the switch is actually tripped after the device outputs the trip command. Prevent the switch from refusing to move, causing the device to mistakenly judge that the switch is tripped, and the grounding still exists and jump off a line; the trip output module 5 is responsible for outputting a trip command to the line switch; the blocking line protection reclosing output module 6 is responsible for correct tripping of the device Finally, output the blocking reclosing command to the protective device of the switched switch to prevent the protective device of the switch from outputting the reclosing command to close the switch; the data buffer module 3 is responsible for buffering the input and output data; the host computer and software control program 7 are responsible for providing relevant Hardware support and software analysis and processing; 4M crystal oscillator 8, responsible for providing the working frequency; single-step, software, and external trigger module 9, responsible for performing software execution control as required; remote data transmission module 10, responsible for outputting grounding alarm signals through the remote control device sent to relevant user terminals; the keyboard part 11 provides a manual control terminal; the liquid crystal display part 12 provides manual reading and checking.

The device of the utility model adopts a multi-thread structure in the program design. When the device starts to detect, the sampling thread is started. When the number of zero-sequence voltages exceeding the threshold reaches a certain number, the transient data is stored, and a message a is sent, and then stored Steady-state data, and send message b. After receiving messages a and b, the main thread will record the fault and display the fault information to the window. After a delay of 2 minutes, if the number of zero-sequence voltages less than the threshold reaches a certain number , the sampling sub-thread will send a message c to the main thread. If the main thread receives the message c within this period, it proves that the ground fault has disappeared, and the device clears the temporary data and resets automatically; if the main thread does not receive the message c within this period Message c, the device will drive the trip exit to jump to the first line. After the trip command is issued for 0.8 seconds, it will detect whether the switch has tripped. If the switch has not tripped, the device will jump the exit to the next line and send the first line switch rejection signal. And repeat the above process; if the switch has been tripped, if the main thread does not receive the message c within the period of 0.5 seconds, the device does not output the blocking protection reclosing command (the protection device will reclose the switch), and the device exit jumps down a line; If the main thread receives message c within 0.5 seconds, it proves that the fault disappears, and the jumped line is the ground fault line, the device will output a blocking reclosing command (blocking protection reclosing switch), the device will clear the temporary data and reset automatically.

The utility model uses the zero-sequence overvoltage generated by the busbar during the grounding fault as the only characteristic quantity for tripping, and uses the zero-sequence overvoltage as the fault action quantity for tripping of all lines. The faulty line is selected without comparing the phase relationship between the zero-sequence current and the zero-sequence voltage. Because in a small power distribution network, the zero-sequence current of the faulty line and the non-faulty line is small, and the zero-sequence current of the faulty line and the non-faulty line is small due to the small magnitude of the zero-sequence current and the complexity of most ground faults. The phase relationship between the sequence current and the zero-sequence voltage of the bus is often not easy to determine, and the fault line and non-fault line are often "unclear", which will cause line selection errors. After the device senses the zero-sequence voltage generated by the busbar, it will trip in the order of 1#, 2#, 3#, ... N# lines, 1# capacitors, and 2# capacitors corresponding to the connected devices, and cooperate with the line protection The automatic reclosing function remedies the tripping result; the capacitor does not use the reclosing remedy, and it is restored manually. The device mainly includes base plate, main board, PT filter board, data acquisition card, switch position input board, switch value output board, trip output module, locking reclosing output circuit module, AC and DC power supply, LCD large screen, keyboard, metal chassis, etc. . The auxiliary contact of the switch position is connected to the switch position input module of the device, the trip outlet of the device is connected to the opening operation circuit of the protection, and the blocking reclosing output circuit of the device is connected to the external blocking reclosing input circuit of the protection device. It is characterized in that: the zero-sequence overvoltage generated by the busbar during the grounding fault is used as the only characteristic quantity for tripping, and the idea of line selection is not adopted. As long as the zero-sequence overvoltage meets the delay requirement, the line will be tripped. Connect the tripping circuit of the device to the opening circuit of the protection. If the tripping is correct and the switch actually trips (the device can judge whether the switch is actually tripping through the switch position input module, so as to prevent the switch from refusing to move and cause the device to misjudge) then the device will not detect zero. If the sequence overvoltage occurs, it will output a blocking reclosing signal to the line protection device. If the tripping is incorrect, the device can still detect the zero-sequence overvoltage, and will not output the blocking reclosing signal, and the protection device will activate the uncorresponding reclosing function. Once the switch is closed, the device will then jump to the next line. If the switch of the device is a capacitor switch, since all reclosing functions of the capacitor are disabled, there is no problem of blocking reclosing. The device is especially suitable for the distribution network where the ground fault must be isolated quickly.

The working principle of the utility model: the zero-sequence voltage of the busbar of the system is input to the device of the utility model after PT transformation, the voltage signal is further transformed by high-precision PT, the voltage signal is input into a low-pass filter to remove interference, and a voltage analog signal with a smooth waveform is output; The device uses the AC 1820A data acquisition card to sample the voltage signal, and the sampled data is stored in the register on the bus through PC/AT. The switch position input is input through the switch input terminal on the rear panel, and after photoelectric isolation, it is input to the PCL-734 switch card 1 and sent to the PC/AT bus. PCA-6153 is used as the motherboard of the industrial computer, which is responsible for calling real-time data from the PC/AT on the bus and performing algorithm processing; at the same time, the trip command is transmitted to the PCL-734 switching card 2 through the PC/AT on the bus, and the switching card is photoelectrically isolated Finally, it is connected to the protection trip circuit through the switch output terminal on the rear panel. If the jumping line is correct, the device will output the blocking reclosing command, which is transmitted to the PCL-734 switching value card 3 through the PC/AT on the bus, and the switching value card passes through the switching value output terminal on the rear panel after being photoelectrically isolated Connect to the external blocking reclosing input circuit of the protection device. Faults and other relevant information are displayed directly through the LCD screen. If the switch of the device is a capacitor switch, since all reclosing functions of the capacitor are disabled, there is no problem of blocking reclosing. The device is also equipped with an anti-crash watchdog circuit, which effectively overcomes the crash problem in the operation of the industrial computer; the device uses a modem to communicate with other computers through serial ports, and realizes remote management of the device.

The following is an analysis of a specific ground fault device isolation fault as an example:

Taking the occurrence of the ground fault of line 2 as an example to describe the device isolation fault process in detail, the sampling sub-thread of the program creates a 5000×32 two-dimensional array, stores the data in quasi-real time, and overwrites the original data from the beginning of the array after the storage is full. After a fault occurs (6 points greater than the starting voltage), the first 100 points and the last 100 points of the fault point are used as transient data, and the last 400 points are used as steady-state data, and these 600 points are submitted to the main thread. After one second, if the fault does not disappear, continue to extract 400 points as steady-state data and submit to the main thread. After the main thread receives these data, it thinks that a certain line has a ground fault, and will record the fault and display it in the window. After a delay of 2 minutes, the fault still exists, the main thread will not receive the message c, the device will output the command to jump the first line, and the trip command is sent to the PCL-734 switch card 2 through the PC/AT on the bus, the switch After the card is photoelectrically isolated, it is connected to the protection trip circuit through the switch output terminal TZ1 on the rear panel. After the switch trips, within 0.8 seconds after the trip command is issued, the photoelectric isolation board will detect the position change of the DL1 switch (from close to open), which proves that the switch of line 1 has tripped, and the device can still detect zero at this time. Sequence overvoltage, the main thread does not receive message c, the device will not output the blocking and reclosing command (the protection device will reclose the switch of line 1), the device will output the command of jumping the second line, and the tripping command will be sent to the bus through PC/AT PCL-734 switching value card 2, the switching value card is connected to the protection trip circuit through the switching value output terminal TZ2 on the rear panel after being photoelectrically isolated. After the line 2 switch trips, within 0.8 seconds after the trip command is issued, the photoelectric isolation board will detect the position change of the DL2 switch (from close to open), which proves that the line switch of line 2 has tripped, and the device will not detect at this time. When the zero-sequence voltage is reached, the device will output the protection reclosing command of the blocking line 2, and the blocking reclosing command is transmitted to the PCL-734 switch card 3 through the PC/AT on the bus, and the switch card passes through the switch on the rear panel The output terminal BS2 is connected to the external input of the protection device of line 2 to block the reclosing circuit, and the blocking switch is reclosed. The device displays line 2 as a fault line and related grounding trip information at the foreground. After the fault is tripped and isolated, the device detects that the zero-sequence voltage is lower than the startup threshold, and the program jumps out of the main thread and returns to the monitoring state.

It is characterized in that: the zero-sequence overvoltage generated by the busbar during the ground fault is taken as the only characteristic quantity for tripping, and the line selection idea is not adopted. The zero-sequence overvoltage value is greater than the action value (generally 40V~60V) If the delay is required, the line is tripped, and the tripping circuit of the device is connected to the protection opening circuit. If the tripping is correct, the switch actually trips (the device can judge whether the switch is actually tripped through the switch position input module, so as to prevent the switch from refusing to move, causing Device misjudgment), if the device can not detect the zero-sequence voltage, it will output a blocking reclosing signal to the line protection device. If the tripping is incorrect, the device can still detect the zero-sequence voltage, and will not output the blocking reclosing signal, and the protection device will start the uncorresponding reclosing function. Once the switch is closed, the device will jump off a line. If the switch of the device is a capacitor switch, since all reclosing functions of the capacitor are disabled, there is no problem of blocking reclosing. The device is especially suitable for the distribution network where the ground fault must be isolated quickly.

Claims (1)

1. An automatic processing device for single-phase grounding faults in small current grounding systems, characterized in that: the signal output terminal of the PT analog input module (1) is connected to the signal input terminal of the A/D conversion module (2), and the PT analog input The system parameter analog quantity collected by the module (1) is converted into a digital quantity; the signal output terminal of the A/D conversion module (2) is connected with the first input terminal (31) of the data buffer module (3) to realize buffer processing; the switch position The output terminal of the input module (4) is connected with the second input terminal (32) of the buffer module (3) to realize the buffering process of the switch position signal; the first output terminal (33) of the data buffer module (3) is connected with the trip output module The input end of (5) is connected, realizes the tripping protection to line switch; The second output end (34) of data buffer module (3) is connected with the input end of blocking line protection reclosing output module (6), has realized protection to The locking and reclosing command of the switch; the third output end (35) of the data buffer module (3) is connected with the input end of the host computer (7), realizing the data exchange between the host computer (7) and the data buffer module (3); the host computer ( 7) the first input end (71) is connected with the output end of 4M crystal oscillator (8), has provided operating frequency for main frame (7); The second input end (72) of main frame (7) is connected with external trigger module (9) connected to the output end of the remote data transmission module (10), and the third input end (73) of the host computer (7) is connected to the output end of the remote data transmission module (10) to transmit the grounding alarm signal; the host computer (7) respectively It is connected with the keyboard module (11) and the liquid crystal display module (12) to realize the input and real-time display of control signals.

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