A single-phase grounding time household number increasing system and method

Abstract

The application provides a single-phase grounding time and household number increasing system and method, the single-phase grounding time and household number increasing system comprises a control module, a fault state reading module, a plurality of controlled line reading modules and a lockout reclosing outlet loop, the fault state reading module, each controlled line reading module and the lockout reclosing outlet loop are connected with the control module. The time and household number increasing method is specifically as follows: single-phase grounding fault detection is carried out based on zero sequence voltage, and the zero sequence voltage relay contact state is taken as the single-phase grounding fault state, whether permanent single-phase grounding fault occurs is judged, after judging that permanent single-phase grounding fault occurs, manual trial pulling is carried out on each controlled line, and the fault line is judged based on the contact state of the controlled line and the contact state of the zero sequence voltage relay, and the reclosing lockout treatment is carried out on the fault line. The application can reduce the time of restoring power supply of non-fault lines and increase the time and household number when single-phase grounding occurs.

Description

Technical Field

[0001] This invention relates to the field of power system technology, and in particular to a system and method for increasing the number of households affected by a single-phase ground fault. Background Technology

[0002] In my country's power systems below 110kV, the neutral point of transformers is often ungrounded or grounded via an arc suppression coil, which can be specifically referred to as a low-current grounding system. During the operation of a low-current grounding system, when a single-phase ground fault occurs, the voltage of the faulty phase drops to 0, while the voltage of the non-faulty phases rises to √3 times the phase voltage. However, the line voltages between the three phases remain symmetrical, and the fault current is only the system-to-ground capacitance current, often much smaller than the load current, having little impact on the power supply load. Therefore, relevant regulations allow low-current grounding systems to continue operating for 1-2 hours under single-phase ground fault conditions. However, in actual operation, the arc overvoltage caused by a ground fault may lead to power cable explosions, fuse blowouts or even burnouts, busbar short circuits, and other accidents. Therefore, quickly identifying the faulty line and eliminating the single-phase ground fault is of paramount importance for the safe operation of the power system.

[0003] On the other hand, people's production and daily life are inseparable from a continuous and reliable power supply. Power outages or voltage fluctuations and other unstable power supply factors can have varying degrees of impact on users, making power supply reliability management increasingly important. The number of households affected by power outages, as an important indicator of power supply reliability, can intuitively show whether the power supply is stable and whether the power grid is operating smoothly. Therefore, when identifying faulty lines and eliminating single-phase grounding faults, the goal is to increase the number of households affected by power outages and reduce the number of households affected by power outages.

[0004] Currently, the traditional method for handling single-phase grounding faults is manual circuit breaking. This involves sequentially opening the circuit breakers of each outgoing line. If the faulty line is opened, the system voltage returns to normal and the grounding signal disappears; otherwise, the search continues. This method causes temporary power outages for fault-free lines during the testing process. Furthermore, opening and closing the switches remotely or by operators alters the closed position of the circuit breakers, preventing reclosing. Both opening and closing require dispatch orders, resulting in lengthy operations. For fault-free lines, this leads to additional time loss and an increase in the number of customers affected by power outages. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art and provide a system and method for increasing the number of users during a single-phase ground fault. By acquiring the contact status of the controlled line and the contact status of the voltage relay, the faulty line and the non-faulty line are distinguished. This allows for the blocking of reclosing of the faulty line and ensures that the non-faulty line can automatically reclose. This solves the problem that existing methods for handling single-phase ground faults require the execution of dispatch orders for the opening and closing process regardless of whether the line is faulty or non-faulty, resulting in long operation time, additional loss of users during the power outage, and an increase in the number of users during the power outage. This invention effectively increases the number of users during the power outage.

[0006] The objective of this invention is achieved through the following technical solution:

[0007] A system for increasing the number of users affected by a single-phase ground fault includes a control module, a fault status reading module, several controlled line reading modules, and a reclosing blocking output circuit. The fault status reading module, each controlled line reading module, and the reclosing blocking output circuit are all connected to the control module. The fault status reading module acquires the single-phase ground fault status and transmits it to the control module. The reclosing blocking output circuit and the controlled line reading modules are all connected to the controlled lines. The controlled line reading modules acquire the contact status of the corresponding controlled lines during manual contact testing. The control module is used to determine whether a single-phase grounding fault has occurred after determining the single-phase grounding fault status based on the single-phase grounding fault status. It uses the contact status of the corresponding controlled line obtained by the controlled line reading module and the contact status of the zero-sequence voltage relay to determine whether the line is faulty or not. When the contact status of the corresponding controlled line is determined to be faulty, the control module controls the reclosing output circuit to perform reclosing blocking processing on the corresponding controlled line. When the contact status of the corresponding controlled line is determined to be non-faulty, the corresponding controlled line is automatically reclosed.

[0008] Furthermore, the fault status reading module includes a zero-sequence voltage relay, which detects the zero-sequence voltage in real time. When the zero-sequence voltage exceeds the set value, the zero-sequence voltage relay contacts close and the contact status is taken as a single-phase grounding fault status.

[0009] Furthermore, the lockout reclosing output circuit includes a decoder, a comparator, a power switch, and a lockout reclosing circuit. The input terminal of the decoder is connected to the control module, and the output terminal of the decoder is connected to the power switch through the comparator. The drain and source of the power switch are connected to the lockout reclosing circuit as conducting nodes.

[0010] Furthermore, it also includes a protection trip circuit, which trips the controlled line during manual testing.

[0011] Furthermore, the controlled line reading module includes a relay coil, which is connected in series between the protection device operation positive power supply and the protection trip circuit of each controlled line. During manual pull-out, the controlled line reading module acquires the contact state of the relay coil and uses the contact state of the relay coil as the contact state of the controlled line.

[0012] A method for increasing the number of households affected by single-phase grounding includes:

[0013] The fault status reading module acquires the zero-sequence voltage in real time and performs single-phase grounding fault detection based on the zero-sequence voltage and the zero-sequence voltage relay setting value. When the zero-sequence voltage exceeds the zero-sequence voltage setting value, it acquires the contact status of the zero-sequence voltage relay and transmits the contact status of the zero-sequence voltage relay as a single-phase grounding fault status to the control module.

[0014] The control module determines whether a permanent single-phase grounding fault has occurred based on the single-phase grounding fault status. After determining that a permanent single-phase grounding fault has occurred, it enters the blocking reclosing signal transmission preparation state and continuously reads the contact status of the zero-sequence voltage relay to manually test each controlled line.

[0015] During the manual pull test, the controlled circuit reading module acquires the contact status of the corresponding controlled circuit and the contact status of the zero-sequence voltage relay. The control module determines the faulty circuit and the non-faulty circuit based on the contact status of the corresponding controlled circuit and the contact status of the zero-sequence voltage relay.

[0016] When the control module determines that the controlled line corresponding to the manual test is a faulty line, it sends a reclosing blocking signal. The reclosing blocking output circuit performs reclosing blocking processing on the controlled line corresponding to the manual test. If the controlled line corresponding to the manual test is determined to be a non-faulty line, the control module does not send a reclosing blocking signal, and the reclosing is performed normally.

[0017] Furthermore, the specific process by which the control module determines whether a permanent single-phase grounding fault has occurred based on the single-phase grounding fault status is as follows: After receiving the single-phase grounding fault status, the control module enters a timing delay, and after the delay, it rereads the zero-sequence voltage relay contact status through the fault status reading module. If the zero-sequence voltage relay contact status is still in the closed state, it is determined that a permanent single-phase grounding fault has occurred; if the zero-sequence voltage relay contact status is in the open state, it is determined that no permanent single-phase grounding fault has occurred.

[0018] Furthermore, when manually testing each controlled line, the priority of the manual testing of the controlled line is also divided.

[0019] Furthermore, when prioritizing manual testing of controlled lines, the operating data, maintenance records, and load conditions of each controlled line are first obtained, along with corresponding environmental data and location information. Based on the operating data, maintenance records, and environmental data of each controlled line, the probability of single-phase grounding faults is predicted. Simultaneously, the fault impact range of each controlled line is defined, and the degree of fault impact of each controlled line is determined in conjunction with the corresponding load conditions. Based on the degree of fault impact, the predicted probability of single-phase grounding faults, and the location information, the priority of manual testing of controlled lines is determined.

[0020] The beneficial effects of this invention are:

[0021] In the event of a single-phase ground fault, the system can reduce the time required to restore power to non-faulty lines during the test pull, thereby increasing the number of users served. It can accurately identify the specific line being manually tested based on the contact status of the relay coil, thus accurately distinguishing between faulty and non-faulty lines. It can also promptly reclose and block faulty lines, while automatically reclosing non-faulty lines, improving the efficiency of handling non-faulty lines and effectively reducing the time required for their reclosing process, thus increasing the number of users served. Furthermore, during manual test pulls, the system can prioritize controlled lines, further improving the efficiency of handling and judging faulty lines and ensuring the reliability of the power system. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the structure of the present invention;

[0023] Figure 2 This is a circuit diagram of a blocking reclosing output circuit according to an embodiment of the present invention;

[0024] Figure 3 This is a flowchart of the present invention.

[0025] The components include: 1. Control module, 2. Fault status reading module, 3. Controlled line reading module, 4. Interlocking reclosing output circuit, 5. Protection tripping circuit, and 6. Controlled line. Detailed Implementation

[0026] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0027] Example:

[0028] A single-phase ground fault-prone system for increasing the number of households, such as Figure 1As shown, the system includes a control module 1, a fault status reading module 2, several controlled line reading modules 3, and a reclosing blocking output circuit 4. The fault status reading module, each controlled line reading module, and the reclosing blocking output circuit are all connected to the control module. The fault status reading module acquires the single-phase grounding fault status and transmits it to the control module. The reclosing blocking output circuit and the controlled line reading modules are all connected to the controlled lines. The controlled line reading modules acquire the contact status of the corresponding controlled line and the contact status of the zero-sequence voltage relay during manual testing. After determining that a single-phase grounding fault has occurred based on the single-phase grounding fault status, the control module uses the contact status of the corresponding controlled line and the contact status of the zero-sequence voltage relay acquired by the controlled line reading modules to determine whether the line is faulty or not. When the contact status of the corresponding controlled line is determined to be faulty, the control module controls the reclosing blocking output circuit to perform reclosing blocking processing on the corresponding controlled line. When the contact status of the corresponding controlled line is determined to be non-faulty, the corresponding controlled line automatically recloses.

[0029] Each controlled line reading module corresponds to one controlled line, and the blocking reclosing output circuit is connected to each controlled line to realize the reclosing blocking control of the controlled line. The circuit is only turned on when the control module sends a blocking reclosing signal.

[0030] The control module specifically uses an STM32F103ZET6 microcontroller manufactured by STMicroelectronics.

[0031] Furthermore, it can set the time from when the control module determines that a single-phase ground fault has occurred until it issues a blocking reclosing command. This is specifically achieved by editing the touch screen. In this embodiment, the USART HMI smart serial port screen produced by Crystal Technology is used to input the setting value.

[0032] The fault status reading module includes a zero-sequence voltage relay, which detects the zero-sequence voltage in real time. When the zero-sequence voltage exceeds the set value, the zero-sequence voltage relay contacts close and the contact status is taken as a single-phase grounding fault status.

[0033] The zero-sequence voltage relay is a voltage relay with an adjustable operating value. It determines whether a fault exists by judging the current zero-sequence voltage. If the voltage exceeds the set value, the contacts of the voltage relay will be connected accordingly, thereby determining the existence of a fault.

[0034] The lockout reclosing output circuit includes a decoder, a comparator, a power switch, and a lockout reclosing circuit. The input terminal of the decoder is connected to the control module, and the output terminal of the decoder is connected to the power switch through the comparator. The drain and source of the power switch are connected to the lockout reclosing circuit as conducting nodes.

[0035] The substation has a large number of 10kV outgoing line bays. If the I / O ports on the microcontroller are used one-to-one to design the blocking outgoing circuit, the amount of I / O port resources required is too large, resulting in unnecessary waste of the microcontroller's on-chip resources. It may even require an additional microcontroller to complete the workload that could originally be handled by a single chip. Therefore, a decoder was added, and the blocking reclosing of 8 outgoing lines can be controlled with 3 I / O ports, which can improve the control efficiency of the control module.

[0036] The decoder uses a 74HC138 chip. The control module can change the level state of its eight output pins (7, 9-15) by inputting different level states to pins 1, 2, and 3 of the 74HC138 chip. It can maintain only one output low level at a time, while the rest are high level. Based on this feature, each output pin corresponds to a line state, which can be used to drive the corresponding power switch to conduct and connect as a contact to the reclosing circuit as the input signal for the reclosing circuit.

[0037] The lockout reclosing output circuit specifically includes comparator A1, optocoupler U1, power switch Q1, Zener diode D1, resistors R1, R2, R3, and R4, as shown in the circuit diagram below. Figure 2 As shown.

[0038] Depend on Figure 2 It can be seen that the control module can input the control signal of the corresponding line to the decoder. The output pin of the decoder corresponding to the line outputs a low level to the comparator. The comparator outputs a high level to drive the optocoupler to conduct, so that the corresponding power switch is turned on. Its drain and source are connected to the reclosing blocking circuit as the conducting node, so that it is turned on, thereby realizing the blocking of reclosing and disconnecting the faulty line.

[0039] It also includes a protection trip circuit, which trips the controlled line during manual testing.

[0040] The controlled line reading module includes a relay coil, which is connected in series between the positive power supply for the protection device and the protection trip circuit of each controlled line. During manual pull-out, the controlled line reading module acquires the contact state of the relay coil and uses the contact state of the relay coil as the contact state of the controlled line.

[0041] The corresponding controlled line being tested can be obtained by monitoring the contact status of the relay coil. When the faulty line is tested and opened, the zero-sequence voltage of the corresponding controlled line decreases. After the fault status reading module reads that the zero-sequence voltage relay contacts are open, it can determine that the faulty line being tested is correct, and the control module can send the corresponding reclosing lockout command. If the faulty line being tested is incorrect, i.e., the current line is not faulty, the control module will not send the reclosing lockout command, and the line not faulty can be reclosed normally.

[0042] A method to increase the number of households affected by single-phase grounding, such as Figure 3 As shown, it includes:

[0043] The fault status reading module acquires the zero-sequence voltage in real time and performs single-phase grounding fault detection based on the zero-sequence voltage and the zero-sequence voltage relay setting value. When the zero-sequence voltage exceeds the zero-sequence voltage setting value, it acquires the contact status of the zero-sequence voltage relay and transmits the contact status of the zero-sequence voltage relay as a single-phase grounding fault status to the control module.

[0044] The control module determines whether a permanent single-phase grounding fault has occurred based on the single-phase grounding fault status. After determining that a permanent single-phase grounding fault has occurred, it enters the blocking reclosing signal transmission preparation state and continuously reads the contact status of the zero-sequence voltage relay to manually test each controlled line.

[0045] During the manual pull test, the controlled circuit reading module acquires the contact status of the corresponding controlled circuit and the contact status of the zero-sequence voltage relay. The control module determines the faulty circuit and the non-faulty circuit based on the contact status of the corresponding controlled circuit and the contact status of the zero-sequence voltage relay.

[0046] When the control module determines that the controlled line corresponding to the manual test is a faulty line, it sends a reclosing blocking signal. The reclosing blocking output circuit performs reclosing blocking processing on the controlled line corresponding to the manual test. If the controlled line corresponding to the manual test is determined to be a non-faulty line, the control module does not send a reclosing blocking signal, and the reclosing is performed normally.

[0047] The specific process by which the control module determines whether a permanent single-phase grounding fault has occurred based on the single-phase grounding fault status is as follows: After receiving the single-phase grounding fault status, the control module enters a timing delay, and after the delay, it rereads the zero-sequence voltage relay contact status through the fault status reading module. If the zero-sequence voltage relay contact status is still in the closed state, it is determined that a permanent single-phase grounding fault has occurred; if the zero-sequence voltage relay contact status is in the open state, it is determined that no permanent single-phase grounding fault has occurred.

[0048] Since transient faults can also cause the zero-sequence voltage relay contacts to close, it is necessary to judge the fault situation. Only when a permanent single-phase ground fault occurs should subsequent reclosing blocking be carried out to avoid affecting the normal operation of the power distribution line.

[0049] When manually testing each controlled line, the priority of the manual testing of the controlled line is also divided.

[0050] When prioritizing manual testing of controlled lines, the operating data, maintenance records, and load conditions of each controlled line are first obtained, along with the corresponding environmental data and location information. Based on the operating data, maintenance records, and environmental data of each controlled line, the probability of single-phase grounding faults is predicted. At the same time, the fault impact range of each controlled line is defined, and the degree of fault impact of each controlled line is determined in conjunction with the corresponding load conditions. Based on the degree of fault impact, the single-phase grounding fault probability prediction results, and the location information, the priority of manual testing of controlled lines is determined.

[0051] Because different lines have different levels of importance, it is necessary to prioritize the handling of these lines in order to minimize the impact of faults and improve the reliability of the power supply system.

[0052] When prioritizing manual testing of controlled lines based on the degree of fault impact, the probability prediction of single-phase grounding faults, and location information, the three types of data are weighted, and each line is comprehensively evaluated based on the weights. The priority is determined based on the comprehensive evaluation results.

[0053] The probability of a single-phase ground fault can be predicted using a neural network algorithm based on historical data. However, if manual ground fault testing requires on-site human intervention, location information must be taken into account to improve processing speed. Conversely, if manual ground fault testing is performed remotely, location information does not need to be considered; this can be achieved by setting the weight of location information to 0 to exclude it from the system.

[0054] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the present invention in any way. Other variations and modifications are possible without departing from the technical solutions described in the claims.

Claims

1. A system for increasing the number of households in case of single-phase grounding, characterized in that, The system includes a control module, a fault status reading module, several controlled line reading modules, and a reclosing blocking output circuit. The fault status reading module, each controlled line reading module, and the reclosing blocking output circuit are all connected to the control module. The fault status reading module acquires the status of a single-phase grounding fault and transmits it to the control module. The reclosing blocking output circuit and the controlled line reading modules are all connected to the controlled lines. The controlled line reading modules acquire the contact status of the corresponding controlled line and the contact status of the zero-sequence voltage relay during manual testing. After determining that a single-phase grounding fault has occurred based on the fault status, the control module uses the contact status of the corresponding controlled line and the contact status of the zero-sequence voltage relay acquired by the controlled line reading modules to determine whether the line is faulty or not. When the contact status of the corresponding controlled line is determined to be faulty, the control module controls the reclosing blocking output circuit to perform reclosing blocking processing on the corresponding controlled line. When the contact status of the corresponding controlled line is determined to be non-faulty, the corresponding controlled line automatically recloses. The lockout reclosing output circuit includes a decoder, a comparator, a power switch, and a lockout reclosing circuit. The input terminal of the decoder is connected to the control module, and the output terminal of the decoder is connected to the power switch through the comparator. The drain and source of the power switch are connected to the lockout reclosing circuit as conducting nodes.

2. The system for increasing the number of households during single-phase grounding as described in claim 1, characterized in that, The fault status reading module includes a zero-sequence voltage relay, which detects the zero-sequence voltage in real time. When the zero-sequence voltage exceeds the set value, the zero-sequence voltage relay contacts close and the contact status is taken as a single-phase grounding fault status.

3. The system for increasing the number of households during single-phase grounding as described in claim 1, characterized in that, It also includes a protection trip circuit, which trips the controlled line during manual testing.

4. The system for increasing the number of households in case of single-phase grounding as described in claim 3, characterized in that, The controlled line reading module includes a relay coil, which is connected in series between the positive power supply for the protection device and the protection trip circuit of each controlled line. During manual pull-out, the controlled line reading module acquires the contact state of the relay coil and uses the contact state of the relay coil as the contact state of the controlled line.

5. A method for increasing the number of households during a single-phase ground fault, applied to the single-phase ground fault household increase system according to any one of claims 1 to 4, characterized in that, include: The fault status reading module acquires the zero-sequence voltage in real time and performs single-phase grounding fault detection based on the zero-sequence voltage and the zero-sequence voltage relay setting value. When the zero-sequence voltage exceeds the zero-sequence voltage setting value, it acquires the contact status of the zero-sequence voltage relay and transmits the contact status of the zero-sequence voltage relay as a single-phase grounding fault status to the control module. The control module determines whether a permanent single-phase grounding fault has occurred based on the single-phase grounding fault status. After determining that a permanent single-phase grounding fault has occurred, it enters the blocking reclosing signal transmission preparation state and continuously reads the contact status of the zero-sequence voltage relay to manually test each controlled line. During the manual pull test, the controlled circuit reading module acquires the contact status of the corresponding controlled circuit and the contact status of the zero-sequence voltage relay. The control module determines the faulty circuit and the non-faulty circuit based on the contact status of the corresponding controlled circuit and the contact status of the zero-sequence voltage relay. When the control module determines that the controlled line corresponding to the manual test is a faulty line, it sends a reclosing blocking signal. The reclosing blocking output circuit performs reclosing blocking processing on the controlled line corresponding to the manual test. If the control module determines that the controlled line corresponding to the manual test is not a faulty line, the control module does not send a reclosing blocking signal, and the reclosing is performed normally. The fault status reading module, each controlled line reading module, and the lockout reclosing output circuit are all connected to the control module, and the lockout reclosing output circuit and the controlled line reading module are all connected to the controlled line. The lockout reclosing output circuit includes a decoder, a comparator, a power switch, and a lockout reclosing circuit. The input terminal of the decoder is connected to the control module, and the output terminal of the decoder is connected to the power switch through the comparator. The drain and source of the power switch are connected to the lockout reclosing circuit as conducting nodes.

6. The method for increasing the number of households during a single-phase ground fault, as described in claim 5, is characterized in that... The specific process by which the control module determines whether a permanent single-phase grounding fault has occurred based on the single-phase grounding fault status is as follows: After receiving the single-phase grounding fault status, the control module enters a timing delay, and after the delay, it rereads the zero-sequence voltage relay contact status through the fault status reading module. If the zero-sequence voltage relay contact status is still in the closed state, it is determined that a permanent single-phase grounding fault has occurred; if the zero-sequence voltage relay contact status is in the open state, it is determined that no permanent single-phase grounding fault has occurred.

7. The method for increasing the number of households during a single-phase ground fault, as described in claim 5, is characterized in that... When manually testing each controlled line, the priority of the manual testing of the controlled line is also divided.

8. The method for increasing the number of households during a single-phase ground fault, as described in claim 5, is characterized in that... When prioritizing manual testing of controlled lines, the operating data, maintenance records, and load conditions of each controlled line are first obtained, along with the corresponding environmental data and location information. Based on the operating data, maintenance records, and environmental data of each controlled line, the probability of single-phase grounding faults is predicted. At the same time, the fault impact range of each controlled line is defined, and the degree of fault impact of each controlled line is determined in conjunction with the corresponding load conditions. Based on the degree of fault impact, the single-phase grounding fault probability prediction results, and the location information, the priority of manual testing of controlled lines is determined.

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