CN111766472A - Fault locating system and method for small resistance grounded power grid - Google Patents

Abstract

The present application provides a fault location system and method for a small resistance grounded power grid. The system includes the circuit to be tested and the main power distribution station. The segmented circuit breaker is preset with the voltage-time feeder automation function, the closing-to-zero-voltage opening function, and the blocking closing function; the outlet circuit breaker is preset with the steady-state zero-sequence overcurrent stage I Protective function. The outlet circuit breaker, when the zero-sequence current of the main feeder connected to itself is greater than the preset value, performs the tripping action and performs the reclosing action; the segmented circuit breaker is used to send its own status to the main power distribution station; the main power distribution station, It is used to receive the status of the target section breaker, and determine the location of the ground fault according to the position of the first section breaker and the position of the second section breaker. The application sets the reclosing function of the outlet circuit breaker, combined with the mechanical characteristics of the segmented circuit breaker, to achieve rapid isolation of ground faults and accurately locate the position of the ground fault.

Description

Fault locating system and method for small resistance grounded power grid

technical field

The present application relates to the field of electrical technology, and in particular, to a fault location system and method for small-resistance grounded power grids.

Background technique

The general transmission process of the power transmission system is that the generator generates electricity, and the generated electricity is boosted or stepped down by the transformer, and then transmitted to the main feeder, and then distributed to the branch feeder by the main feeder until it is transmitted to the user end. In order to ensure the reliability of power transmission, the neutral point of the transformer can be grounded with a small resistance to improve the reliability of the power transmission system.

As shown in FIG. 1 , it is a schematic diagram of a circuit structure of a small-resistance grounded power grid in the prior art. The circuit 1 to be tested is a part of the power transmission system; the circuit 1 to be tested includes a small resistor 18, a line selection device 11, a bus bar 10, a trunk feeder (such as the trunk feeder 121 and trunk feeder 122 shown in the figure) and branch feeders ( branch feeder 131 and branch feeder 132 as shown in the figure); bus bar 10 is connected to one or more trunk feeders (eg trunk feeder 121 and trunk feeder 122 shown in the figure); each trunk feeder (eg as shown in the figure) The outgoing trunk feeder 121 and trunk feeder 122) can be connected to one or more branch feeders. The line selection device 11 is arranged near the transformer 14 , and the transformer 14 is connected to the bus bar 10 . Taking the trunk feeder 121 as an example, the end of the trunk feeder 121 that is closer to the line selection device 11 is the head end of the trunk feeder 121. On the contrary, the end of the trunk feeder 121 that is farther from the line selection device 11 is the end of the trunk feeder. Each trunk feeder is provided with an outlet circuit breaker 15, and the outlet circuit breaker 15 is arranged close to the head end of the trunk feeder. The small resistance 18 is arranged between the small resistance connection point (point C shown in the figure) and the ground point (point D shown in the figure), and the small resistance connection point (point C shown in the figure) is located at on busbar 10. A plurality of sectional breakers (eg sectional breaker 161 , sectional breaker 162 , sectional breaker 163 shown in FIG. 1 ) are provided between the outlet breaker 15 and the end of the main feeder 121 . The branch feeder is connected to the main feeder 121 through a branch connection point (point A or point B as shown in FIG. 1 ); the branch connection point (point A or B) is set between the outlet circuit breaker 15 and the end of the main feeder 121 (Excluding the outlet circuit breaker 15 and the end of the trunk feeder 121); the branch feeder takes the branch connection point (point A or B) as the head end, on the contrary, the other end of the branch feeder is the end; each branch feeder is provided with There is at least one branch breaker (eg, branch breaker 171 or branch breaker 172 as shown in the figure). Since the power transmission system of the small-resistance grounded grid is large and complex, failures are prone to occur in the power transmission system. Among them, the ground fault in the feeder is one of the main types of faults in the power transmission system of the small resistance grounded grid. Once a ground fault occurs, it is necessary to find the location of the ground fault as soon as possible, repair the ground fault, and restore the normal power supply.

At present, if a ground fault occurs in the power transmission system of the small-resistance grounded grid, the outlet circuit breaker usually performs a tripping action to cut off the faulty line, and then the operation and maintenance personnel check one by one in the area where the fault may occur, until the ground fault is found. Location. Due to the complex structure of the power transmission system of the small-resistance grounded grid and the numerous branch lines, this ground fault location method based on human judgment is inefficient, and there is even a possibility that the ground fault location cannot be found.

Based on this, there is an urgent need for a fault location method for a small-resistance grounded power grid, which is used to solve the problem of low efficiency in locating a ground fault in the prior art.

SUMMARY OF THE INVENTION

The present application provides a fault location system and method for a low-resistance grounded power grid, which can be used to solve the problem of low efficiency in locating a ground fault in the prior art.

In a first aspect, the present application provides a fault location system for a small resistance grounded power grid, the system includes a circuit to be tested and a main power distribution station, the circuit to be tested includes a small resistance, a busbar and a main feeder; the busbar and The main feeder is connected; the main feeder is provided with an outlet circuit breaker and a sectional circuit breaker; the sectional circuit breaker is arranged between the outlet circuit breaker and the end of the main feeder; the small resistance is arranged in Between the small resistance connection point and the grounding point, the small resistance connection point is located on the bus; the main power distribution station is connected to the segment circuit breaker through the network; the segment circuit breaker is preset with voltage and time type feeder automation function, closing to zero-voltage opening function and blocking closing function; the outlet circuit breaker is preset with the first stage protection function of steady-state zero-sequence overcurrent;

The outlet circuit breaker is used to judge whether the zero-sequence current of the main feeder connected to itself is greater than the preset value, and if the zero-sequence current is greater than the preset value, the tripping action is performed; and, after the preset reclosing time period When power is on, the reclosing action is performed;

The sectional circuit breaker is used to perform corresponding actions according to the voltage-time feeder automation function, the closing-to-zero-voltage opening function, and the blocking closing function after the outlet circuit breaker is reclosed After that, send its own status to the power distribution master station;

The main power distribution station is used to receive the state of the segment circuit breaker, and determine whether there is a first segment circuit breaker that is in the closed-to-zero-voltage open state and the latched closed state, if there is the first segment circuit breaker. If the segment circuit breaker is selected, the position of the first segment circuit breaker is determined, and the second segment circuit breaker in the residual voltage lockout state is determined, and the position of the second segment circuit breaker is determined; and according to the first segment circuit breaker The location of the first segment circuit breaker and the location of the second segment circuit breaker determine the location of the ground fault.

With reference to the first aspect, in an implementation manner of the first aspect, the system further includes a branch feeder; the branch feeder is connected to the trunk feeder through a branch connection point, and the branch connection point is located at the outlet Between the circuit breaker and the end of the main feeder; the branch feeder is provided with a branch circuit breaker; the main power distribution station is connected to the branch circuit breaker through a network; the branch circuit breaker is preset with a steady-state zero-sequence Flow section I protection function;

The branch circuit breaker is used to send its own state to the main power distribution station after performing the first stage protection of the steady-state zero-sequence overcurrent;

The main power distribution station is also used to receive the state of the branch circuit breaker, and determine whether there is a first branch circuit breaker in the steady state zero-sequence overcurrent stage I protection state, and if there is the first branch circuit breaker, Then the position of the first branch circuit breaker is determined, and according to the position of the first branch circuit breaker, the position of the ground fault is determined.

With reference to the first aspect, in an implementation manner of the first aspect, the main power distribution station is further configured to:

If the first section circuit breaker does not exist, and the first branch circuit breaker does not exist, an instruction is issued to initiate other ground fault location methods.

With reference to the first aspect, in an implementation manner of the first aspect, the location of the ground fault is determined according to the location of the first branch circuit breaker, and is obtained by the following steps:

Based on the location of the first branch breaker, it is determined that the ground fault is located in an area between the first branch breaker and the end of the branch feeder.

With reference to the first aspect, in an implementation manner of the first aspect, the main power distribution station determines the ground fault according to the position of the first section circuit breaker and the position of the second section circuit breaker. position, obtained by the following steps:

Based on the position of the first section breaker and the position of the second section breaker, determine the area where the ground fault is located between the first section breaker and the second section breaker Inside.

With reference to the first aspect, in an implementation manner of the first aspect, the small resistor is in a grounded state.

In combination with the first aspect, in an implementation manner of the first aspect, the preset power-on delay closing time period in the voltage-time feeder automation function is 7 seconds, and the preset power-on hold time period is 5 seconds. , the preset voltage loss delay opening time period is 0.5 seconds.

With reference to the first aspect, in an implementation manner of the first aspect, the preset reclosing time period is greater than or equal to 1 second and less than or equal to 10 seconds.

In a second aspect, the present application provides a fault location method for a small-resistance grounded power grid, and the method is applied in a fault system for a small-resistance grounded power grid; the system includes a circuit to be tested and a main power distribution station, and the The circuit to be tested includes a small resistance, a bus bar and a trunk feeder; the bus bar is connected to the trunk feeder; an outlet circuit breaker and a sectional circuit breaker are arranged on the trunk feeder, and the sectional circuit breaker is arranged on the outlet circuit breaker and the end of the main feeder; the small resistance is arranged between the small resistance connection point and the grounding point, and the small resistance connection point is located on the bus; the main power distribution station is disconnected from the segment through the network The sectional circuit breaker is preset with the voltage-time feeder automation function, the closing-to-zero-voltage opening function, and the blocking closing function; The methods described include:

The outlet circuit breaker judges whether the zero-sequence current of the main feeder connected to itself is greater than a preset value;

If the outlet circuit breaker determines that the zero-sequence current is greater than the preset value, the tripping action is performed;

The outlet circuit breaker is powered on after the preset reclosing time period, and performs the reclosing action;

After the outlet circuit breaker is reclosed, the sectional circuit breaker performs corresponding actions according to the voltage-time feeder automation function, the closing-to-zero-voltage opening function, and the blocking closing function. The power distribution master station sends its own status;

the power distribution master station receives the status of the segment circuit breaker;

The main power distribution station judges whether there is a first segment circuit breaker that is in a closed-to-zero-voltage open state and a latched closed state;

If the main power distribution station determines that the first segment circuit breaker exists, determine the position of the first segment circuit breaker, determine the second segment circuit breaker in a residual voltage blocking state, and determine the The location of the second segment circuit breaker;

The main power distribution station determines the position of the ground fault according to the position of the first section breaker and the position of the second section breaker.

With reference to the second aspect, in an implementation manner of the second aspect, the system further includes a branch feeder; the branch feeder is connected to the trunk feeder through a branch connection point, and the branch connection point is located at the outlet Between the circuit breaker and the end of the main feeder; the branch feeder is provided with a branch circuit breaker; the main power distribution station is connected to the branch circuit breaker through a network; the branch circuit breaker is preset with a steady-state zero-sequence Flow I section protection function; the method further includes:

After the branch circuit breaker performs the steady-state zero-sequence overcurrent stage I protection, it sends its state to the main power distribution station;

The main power distribution station receives the state of the branch circuit breaker, determines whether there is a first branch circuit breaker in the steady state zero-sequence overcurrent stage I protection state, and if the first branch circuit breaker exists, determines the The location of the first branch circuit breaker is determined, and the location of the ground fault is determined according to the location of the first branch circuit breaker.

With reference to the second aspect, in an implementation manner of the second aspect, the main power distribution station is further configured to:

If the first section circuit breaker does not exist, and the first branch circuit breaker does not exist, an instruction is issued to initiate other ground fault location methods.

With reference to the second aspect, in an implementation manner of the second aspect, the location of the ground fault is determined according to the location of the first branch circuit breaker, and is obtained by the following steps:

Based on the location of the first branch breaker, it is determined that the ground fault is located in an area between the first branch breaker and the end of the branch feeder.

With reference to the second aspect, in an implementation manner of the second aspect, the main power distribution station determines the ground fault according to the position of the first section circuit breaker and the position of the second section circuit breaker. position, obtained by the following steps:

Based on the position of the first section breaker and the position of the second section breaker, determine the area where the ground fault is located between the first section breaker and the second section breaker Inside.

With reference to the second aspect, in an implementation manner of the second aspect, the small resistor is in a ground state.

In combination with the second aspect, in an implementation manner of the second aspect, the preset power-on delay closing time period in the voltage-time feeder automation function is 7 seconds, and the preset power-on hold time period is 5 seconds. , the preset voltage loss delay opening time period is 0.5 seconds.

With reference to the second aspect, in an implementation manner of the second aspect, the preset reclosing time period is greater than or equal to 1 second and less than or equal to 10 seconds.

The application sets the reclosing function of the outlet circuit breaker, combined with the mechanical characteristics of the sectional circuit breaker, to realize the rapid isolation of the ground fault and accurately locate the ground fault position. Before realizing the function of locating the ground fault, the application needs to make limited changes to the circuit to be tested, and the original functions of the components in the circuit to be tested are utilized to the greatest extent. The solution of the application is economical and effective, and can achieve a wide promotion.

Description of drawings

1 is a schematic diagram of the circuit structure of a small resistance grounded grid in the prior art;

2 is a diagram of a fault location system for a small-resistance grounded power grid provided by an embodiment of the present application;

FIG. 3 is a structural diagram of a fault location system with a ground fault occurring according to an embodiment of the present application;

FIG. 4 is a structural diagram of another fault location system where a ground fault has occurred, according to an embodiment of the present application;

FIG. 5 is a flowchart of a fault location method for a small-resistance grounded power grid according to an embodiment of the present application.

Detailed ways

In order to make the objectives, technical solutions and advantages of the present application clearer, the embodiments of the present application will be further described in detail below with reference to the accompanying drawings.

As shown in FIG. 2 , it is a diagram of a fault location system for a small-resistance grounded power grid according to an embodiment of the present application. It can be seen from FIG. 2 that the system includes a circuit to be tested 1 and a main power distribution station 2 , and the circuit to be tested 1 includes a small resistor 18 , a bus bar 10 and a main feeder 12 .

The bus bar 10 is connected to a trunk feeder (eg trunk 121 and trunk feeder 122 as shown in FIG. 2 ).

The bus bar 10 can be connected with a plurality of trunk feeders, and the structures of the trunk feeders are basically similar. For convenience of description, the following description takes the trunk feeder 121 as an example.

The main feeder 12 is provided with outlet circuit breakers 15 and section circuit breakers.

A section breaker is provided between the outlet breaker 15 and the end of the main feeder 121 . It can be seen from FIG. 2 that a plurality of segment breakers are distributed on the trunk feeder 121 from the outlet circuit breaker 15 to the end of the trunk feeder 121 , such as the segment circuit breaker 161 and the segment circuit breaker 162 shown in FIG. 2 . , segment breakers 163 . . . These segment breakers divide the main feeder 121 into sections.

The small resistance 18 is arranged between the small resistance connection point C and the ground point D, and the small resistance connection point C is located on the bus bar 10 .

The main power distribution station 2 is connected with the sectional circuit breaker through the network.

The system also includes branch feeders. The branch feeder is connected to the main feeder 121 through the branch connection point. The branch connection point is located between the outlet breaker 15 and the end of the main feeder 121 . Specifically, a plurality of branch connection points are distributed on the trunk feeder 121 from the outlet circuit breaker 15 to the end of the trunk feeder 121 (excluding the outlet circuit breaker 15 and the end of the trunk feeder 121 ) (as shown in FIG. 2 ) points A and B). Each branch connection point is correspondingly connected to a branch feeder. For example, the branch connection point A in FIG. 2 is connected to the branch feeder 131 , and the branch connection point B is connected to the branch feeder 132 .

A branch circuit breaker is provided on the branch feeder. Each branch feeder is provided with at least one branch circuit breaker. For example, the branch feeder 131 in FIG. 2 is provided with a branch circuit breaker 171 , and the branch feeder 132 is provided with a branch circuit breaker 172 .

The main power distribution station 2 is connected with the branch circuit breaker through the network.

In this embodiment of the present application, the small resistor is in a grounded state. If a ground fault occurs in the circuit under test, the ground fault and the small resistance are both grounded, forming a loop. The current signal and voltage signal detected in the circuit to be tested 1 are amplified in the loop and can be more easily detected.

The workflow of the fault location system in the embodiment of the present application is described in detail below.

The outlet circuit breaker is used to judge whether the zero-sequence current of the main feeder connected to itself is greater than the preset value, and if the zero-sequence current is greater than the preset value, the tripping action is performed.

Specifically, the outlet circuit breaker 15 is preset with the steady-state zero-sequence overcurrent stage I protection function, so the outlet circuit breaker 15 detects zero-sequence current when the main feeder 121 does not have a ground fault. If the main feeder 121 fails and the detected zero-sequence current is greater than the preset value, the outlet circuit breaker 15 performs a tripping action. If the outlet circuit breaker 15 determines that the zero-sequence current of the main feeder 121 connected to itself is zero, the outlet circuit breaker maintains the current state and does not perform the tripping action.

It should be noted that the preset action time of the steady-state zero-sequence overcurrent stage I protection function of the outlet circuit breaker 15 is greater than or equal to 0.4 seconds and less than or equal to 0.8 seconds.

Since the outlet circuit breaker 15 performs the tripping action, the trunk feeder 121 connected to the outlet circuit breaker 15 is de-energized, and the corresponding sectional circuit breaker on the trunk feeder 121, such as the sectional circuit breaker 161 shown in FIG. The segment circuit breaker 162, the segment circuit breaker 163... correspond to power failure opening.

The outlet circuit breaker 15 is powered on after a preset reclosing time period, and performs the reclosing action.

In the embodiment of the present application, the outlet circuit breaker 15 may set a preset reclosing time period in advance. Generally, the preset reclosing time period is greater than or equal to 1 second and less than or equal to 10 seconds. After the preset reclosing time period has elapsed, the outlet circuit breaker 15 will automatically perform the reclosing action.

After the outlet circuit breaker 15 automatically performs the reclosing action, the trunk feeder 121 corresponding to the outlet circuit breaker 15 is re-energized.

After the outlet circuit breaker 15 performs the reclosing action, for the sectional circuit breakers corresponding to the outlet circuit breaker 15 (ie the sectional circuit breaker 161 , the sectional circuit breaker 162 and the sectional circuit breaker 163 shown in FIG. 2 ) ), according to the voltage-time feeder automation function, the closing-to-zero-voltage opening function, and the blocking closing function, after performing the corresponding actions, it sends its own status to the main power distribution station.

It should be noted that there are multiple sectional circuit breakers in the circuit 1 to be tested, and only the sectional circuit breaker affected by the ground fault will perform the corresponding actions in the embodiments of the present application.

Specifically, each segmented circuit breaker is preset with a voltage-time feeder automation function, a closing-to-zero-voltage opening function, and a blocking closing function.

Among them, in the automatic function of the voltage-time feeder, the preset power-on delay closing time period is 7 seconds, that is, the sectional circuit breaker delays for 7 seconds after power-on before closing; the preset power-on hold time period It is 5 seconds, that is, the sectional circuit breaker will keep the power-on state for 5 seconds after it is energized; the preset voltage loss delay opening time period is 0.5 seconds, that is, the sectional circuit breaker will open after 0.5 seconds in the voltage loss state. . The closing to zero-voltage opening function of the sectional circuit breaker enables the sectional circuit breaker to automatically open if it is in a zero-voltage state after closing. If the sectional circuit breaker performs the blocking and closing function, it can isolate the nearby feeder.

After the outlet circuit breaker 15 is re-energized, since the sectional circuit breaker is preset with the voltage-time feeder automation function, the sectional circuit breaker is closed in sequence from the head end to the end of the main feeder 121 through a preset power-on delay. The closing action is performed after the time period.

Specifically, as shown in FIG. 2 , the sectional circuit breakers are respectively closed in the order of sectional circuit breaker 161 , sectional circuit breaker 162 , sectional circuit breaker 163 . . . Whenever a sectional circuit breaker performs the closing action, all the sectional circuit breakers that have performed the closing action perform zero-sequence voltage detection.

If the zero-sequence voltage detected by the latest segment circuit breaker performing the closing action is zero, the next segment circuit breaker in sequence from the head end to the end along the main feeder 121 continues to perform the closing action.

If the sectional circuit breaker that performs the closing action newly detects a zero-sequence voltage greater than zero, the sectional circuit breaker that performs the closing action latest performs the closing to zero-voltage opening action and the blocking closing action, and keeps the closing to zero-voltage opening action. It also uploads its closed-to-zero-voltage open state and latched closed state to the main power distribution station 2. The next segment circuit breaker in the sequence from the head end to the end of the main feeder 121 uses the residual voltage to perform the residual voltage blocking action within the preset power-on delay closing time period, maintains the residual voltage blocking state, and transfers its own residual voltage. The voltage blocking state is uploaded to the main power distribution station 2.

For example, as shown in FIG. 2 , after the sectional circuit breaker 161 performs the closing action, because only the sectional circuit breaker 161 is currently closed, the sectional circuit breaker 161 performs zero-sequence voltage detection. If the zero sequence voltage is zero, the sectional circuit breaker 162 continues to perform the closing action. If the zero-sequence voltage is greater than zero, the segment circuit breaker 161 performs the closing to zero-voltage opening action and the blocking closing action, maintains the closing-to-zero-voltage opening state and the latching closing state, and closes to zero-voltage opening of its own. The gate status and the blocking and closing status are uploaded to the main power distribution station 2. The next sectional circuit breaker 162 of the sectional circuit breaker 161 uses the residual voltage to perform the residual voltage blocking action within the preset power-on delay closing time period, maintains the residual voltage blocking state, and uploads its own residual voltage blocking state to the Power distribution master station 2.

It should be noted that the sectional circuit breaker 161 performs the closing to zero voltage opening action and the blocking closing action, and the sectional circuit breaker 162 performs the residual voltage blocking action within the preset power-on delay closing time period, which is equivalent to The ground fault is isolated outside the circuit under test 1, and the voltage transmitted in other places in the power grid will not be affected by the ground fault again, thereby avoiding the possibility of malfunction of the segment circuit breaker or other components near the ground fault location, and at the same time. The accuracy of the information collected by the main power distribution station 2 is guaranteed.

In the embodiment of the present application, the value of the zero-sequence voltage of the segment circuit breaker that can be detected and set in advance by the segment circuit breaker is set to be greater than or equal to 18V and less than or equal to 20V, which is smaller than the value that can be detected by the line selection device 11 . The zero-sequence voltage value of the outlet circuit breaker 15. This arrangement is to prevent the line selection device 11 from issuing a trip command to disconnect the entire main feeder 121 before the sectional circuit breaker operates.

It should be noted that the target segment circuit breaker will be affected by the ground fault only when the location of the ground fault is on the main feeder 121 or the ground fault occurs between the branch connection point and the branch circuit breaker corresponding to the branch connection point. The corresponding action, otherwise, the corresponding action will not be executed.

The location of the ground fault may occur not only on the main feeder 121 or between the branch connection point and the branch circuit breaker corresponding to the branch connection point, but also between the branch circuit breaker and the end of the branch feeder corresponding to the branch circuit breaker. between.

As shown in FIG. 2, if a ground fault occurs between the branch breaker 171 and the end of the branch feeder 131, the outlet breaker 15 and the section breaker corresponding to the outlet breaker 15 (the section shown in FIG. 2 The circuit breaker 161, the sectional circuit breaker 162 and the sectional short circuit 163) are all inactive. At this time, it will be affected by the ground fault, and the branch circuit breaker 131 is actuated.

In the following, the branch circuit breaker 131 is taken as an example for description.

In the embodiment of the present application, the branch circuit breaker 131 is preset with the first stage protection function of steady-state zero-sequence overcurrent.

The branch circuit breaker 131 is used to send its own status to the main power distribution station after performing the first stage protection of the steady state zero-sequence overcurrent.

Specifically, when the branch feeder connected to the branch breaker 131 has no ground fault, the detected zero-sequence current is zero. If the branch feeder connected to the branch breaker 131 has a ground fault, the detected zero-sequence current If the current is greater than zero, the branch feeder performs tripping action.

It should be further noted that the preset action time of the steady-state zero-sequence overcurrent stage I protection function of the branch circuit breaker is greater than or equal to 0 seconds and less than or equal to 0.2 seconds. The maximum action time of the steady-state zero-sequence overcurrent stage I protection function of the branch circuit breaker is less than the minimum action time of the steady-state zero-sequence overcurrent stage I protection function of the outlet circuit breaker. Therefore, before the outlet circuit breaker 15 detects the zero-sequence current, the branch circuit breaker has performed the opening action and completed the isolation of the ground fault. This arrangement can prevent the outlet circuit breaker from operating before the branch circuit breaker, thereby causing the main feeder to lose power.

Since both the sectional circuit breaker and the branch circuit breaker are connected to the main power distribution station through the network, and both the sectional circuit breaker and the branch circuit breaker send the status maintained after the action to the main power distribution station, the location of the ground fault is determined by the distribution main station. The electrical master station is completed.

The main power distribution station 2 is used to receive the status of the target segment circuit breaker, and determine whether there is a first segment circuit breaker that is in the closed-to-zero-voltage open state and the latched closed state. If there is a first segment circuit breaker, Then determine the position of the first section circuit breaker, and determine the second section circuit breaker in the residual voltage blocking state, and determine the position of the second section circuit breaker; and according to the position of the first section circuit breaker and the second section circuit breaker The location of the sectional circuit breaker to determine the location of the ground fault.

Specifically, the main power distribution station 2 can determine that the ground fault is located in the area between the first sectional circuit breaker and the second sectional circuit breaker according to the position of the first sectional circuit breaker and the position of the second sectional circuit breaker .

It should be noted that the area between the first section breaker and the second section breaker referred to in the embodiments of the present application does not only include the trunk between the first section breaker and the second section breaker. The feeder 121 also includes the main feeder 121 between the first section breaker and the second section breaker, the branch connection point connected to the branch connection point corresponding to the branch feeder line between the first branch breaker. area.

Taking FIG. 2 as an example, if the section breaker 161 is the first section breaker, and the section breaker 162 is the second section breaker, then the connection between the first section breaker and the second section breaker is The area includes not only the main feeder between the section breaker 161 and the section short circuit 162 , but also the area between the branch connection point A and the branch breaker 171 .

In the embodiment of the present application, the main power distribution station is also used to receive the status of the branch circuit breaker, and determine whether there is a first branch circuit breaker in the steady state zero-sequence overcurrent stage I protection state, and if there is a first branch circuit breaker, then The location of the first branch circuit breaker is determined, and based on the location of the first branch circuit breaker, the location of the ground fault is determined.

Specifically, the ground fault is located in the area between the first branch circuit breaker and the end of the branch feeder.

In the embodiment of the present application, the main power distribution station is further configured to issue an instruction to start other ground fault location methods if there is no first segment circuit breaker and no first branch circuit breaker.

It should be noted that, if there is no first segment circuit breaker and there is no first branch circuit breaker, it is highly probable that the fault occurs at the first segment circuit breaker starting from the outlet circuit breaker 15 and the head end of the main feeder 121 . between 161. In this case, the ground fault cannot affect any breaking circuit breakers and branch circuit breakers, so there are no first branch circuit breakers and first branch circuit breakers. At this time, the command issued by the main power distribution station 2 to start other ground fault location methods can be regarded as reminding the staff to check between the exit circuit breaker 15 and the first segment circuit breaker 161 from the head end of the main feeder 121, Find the ground fault location.

The following describes the embodiments of the present application through two examples.

Example 1

As shown in FIG. 3 , it is a structural diagram of a fault location system in which a ground fault occurs according to an embodiment of the present application. In the circuit 1 to be tested, a ground fault 31 occurs, and under the influence of the ground fault 31, the outlet circuit breaker 15 opens and then performs the reclosing action. Correspondingly, the sectional circuit breaker 161 performs the closing action, the sectional circuit breaker 162 performs the closing to zero voltage opening action and the blocking closing action, maintains the closed to zero voltage opening state and the latching closing state, and will close to the zero voltage opening state and the latching closing state. The zero-voltage opening state and the blocking closing state are uploaded to the main power distribution station 2, and the sectional circuit breaker 163 performs the residual voltage blocking action, maintains the residual voltage blocking state, and uploads the residual voltage blocking to the main power distribution station 2. The main power distribution station 2 receives the closed-to-zero-voltage open state and the blocking closed state of the sectional circuit breaker 161, as well as the residual voltage blocking state of the sectional circuit breaker 163, and determines that the location of the ground fault is between the sectional circuit breaker 162 and the sectional circuit breaker 163. On the main feeder 121 between the segment breakers 163, or between the end of the branch feeder 132 connected to the main feeder 121 between the segment breakers 162 and 163 and the branch breaker 172, after further The investigation determined that the ground fault occurred on the main feeder 121 between the sectional breaker 162 and the sectional breaker 163 .

Example 2

As shown in FIG. 4 , which is a structural diagram of another fault location system in which a ground fault has occurred, provided in this embodiment of the present application, a fault 32 has occurred in the circuit 1 under test. Affected by the ground fault 32 , the branch circuit breaker 171 performs the steady-state zero-sequence overcurrent stage I protection function, performs opening action, isolates the ground fault 32 , and uploads its state to the main power distribution station 2 . The main power distribution station 2 receives the status of the branch breaker 171 and determines that the ground fault 32 occurs between the branch breaker 171 and the end of the branch feeder 131 .

Combining the above two examples, if there is no first segment circuit breaker and first branch circuit breaker, the high probability is because the fault occurs between the outlet circuit breaker 15 and the first segment circuit breaker 161 from the head end of the main feeder 121. between. In this case, the command issued by the main power distribution station 2 to activate other ground fault location methods can be regarded as a reminder to the staff between the outlet circuit breaker 15 and the first segment circuit breaker 161 at the head end of the main feeder 121 Check to find the location of the ground fault.

In the present application, the reclosing function of the outlet circuit breaker 15 is provided, and combined with the mechanical characteristics of the sectional circuit breaker, the rapid isolation of the ground fault can be realized, and the position of the ground fault can be accurately located. Before realizing the function of locating the ground fault, the application needs to make limited changes to the circuit to be tested, and the original functions of the components in the circuit to be tested are utilized to the greatest extent. The solution of the application is economical and effective, and can achieve a wide promotion.

The following are the method embodiments of the present application, which can be used in the system embodiments of the present application. For details not disclosed in the method embodiments of the present application, please refer to the system embodiments of the present application.

FIG. 5 exemplarily shows a flowchart of a fault location method for a small-resistance grounded power grid provided by an embodiment of the present application. The method is applied in a fault location system for small-resistance grounded power grids. The system includes a circuit to be tested and a main power distribution station. The circuit to be tested includes a small resistance, a busbar and a trunk feeder; the busbar is connected to the trunk feeder; the trunk feeder is provided with an outlet circuit breaker and a segment circuit breaker. The segment circuit breaker is provided on the outlet circuit breaker. The small resistance is set between the small resistance connection point and the grounding point, and the small resistance connection point is located on the busbar; Voltage time type feeder automation function, closing to zero voltage opening function and blocking closing function; the outlet circuit breaker is preset with the protection function of the first stage of steady-state zero-sequence overcurrent. The specific flow of the method provided by the embodiment of the present application is as follows:

Step 501 , the outlet circuit breaker determines whether the zero sequence current of the main feeder connected to itself is greater than the preset value; if the zero sequence current of the main feeder connected to the outlet circuit breaker itself is greater than the preset value, go to step 502 , otherwise go to step 511 .

In step 502, the outlet is disconnected and the tripping action is performed.

Step 503, the outlet circuit breaker is powered on after the preset reclosing time period, and performs the reclosing action.

Step 504: After the outlet circuit breaker is reclosed, the sectional circuit breaker performs corresponding actions according to the voltage-time feeder automation function, the closing-to-zero-voltage opening function, and the blocking closing function, and then sends its own status to the main power distribution station. .

Step 505, the main power distribution station receives the status of the target segment breaker.

Step 506, the main power distribution station judges whether there is a first segment circuit breaker that is in the closed-to-zero-voltage open state and the closed state; if there is a first segment circuit breaker, go to step 507, otherwise, go to step 510 .

Step 507 , the power distribution master determines the position of the first section circuit breaker, determines the second section circuit breaker in the residual voltage blocking state, and determines the position of the second section circuit breaker.

Step 508, the main power distribution station determines the location of the ground fault according to the location of the first segment circuit breaker and the location of the second segment circuit breaker.

Step 509, the main power distribution station sends an instruction to start other positioning methods.

In step 510, the outlet circuit breaker remains in the current state.

The target segment circuit breaker is the segment circuit breaker corresponding to the outlet circuit breaker that performs the reclosing action.

Optionally, the system further includes a branch feeder; the branch feeder is connected to the main feeder through a branch connection point, and the branch connection point is located between the outlet circuit breaker and the end of the main feeder; the branch feeder is provided with a branch circuit breaker; The network is connected to the branch circuit breaker; the branch circuit breaker is preset with the first stage protection function of steady-state zero-sequence overcurrent; the method further includes:

After the branch circuit breaker performs the first stage protection of steady-state zero-sequence overcurrent, it sends its own status to the main power distribution station;

The main power distribution station receives the status of the branch circuit breaker, and determines whether there is a first branch circuit breaker in the steady state zero-sequence overcurrent stage I protection state. and determining the location of the ground fault according to the location of the first branch circuit breaker.

Optionally, the power distribution master is also used to:

If there is no first section circuit breaker, and no first branch circuit breaker, an instruction to initiate other ground fault location methods is issued.

Optionally, the location of the ground fault is determined according to the location of the first branch circuit breaker, and is obtained through the following steps:

Based on the location of the first branch breaker, it is determined that the ground fault is located in an area between the first branch breaker and the end of the branch feeder.

Optionally, the main power distribution station determines the position of the ground fault according to the position of the first section circuit breaker and the position of the second section circuit breaker, and obtains it through the following steps:

Based on the position of the first section breaker and the position of the second section breaker, it is determined that the ground fault is located in the area between the first section breaker and the second section breaker.

Optionally, the small resistor is in the ground state.

Optionally, in the voltage-time feeder automation function, the preset power-on delay closing time period is 7 seconds, the preset power-on hold time period is 5 seconds, and the preset voltage loss delay opening time period is 0.5 seconds.

Optionally, the preset reclosing time period is greater than or equal to 1 second and less than or equal to 10 seconds.

The application sets the reclosing function of the outlet circuit breaker, combined with the mechanical characteristics of the sectional circuit breaker, to realize the rapid isolation of the ground fault and accurately locate the ground fault position. Before realizing the function of locating the ground fault, the application needs to make limited changes to the circuit to be tested, and the original functions of the components in the circuit to be tested are utilized to the greatest extent. The solution of the application is economical and effective, and can achieve a wide promotion.

The present invention may be used in numerous general purpose or special purpose computing system environments or configurations. For example: personal computers, server computers, handheld or portable devices, tablet devices, multiprocessor systems, microprocessor-based systems, set-top boxes, programmable consumer electronics, network PCs, minicomputers, mainframe computers, including A distributed computing environment for any of the above systems or devices, and the like.

The invention may be described in the general context of computer-executable instructions, such as program modules, being executed by a computer. Generally, program modules include routines, programs, objects, components, data structures, etc. that perform particular tasks or implement particular abstract data types. The invention may also be practiced in distributed computing environments where tasks are performed by remote processing devices that are linked through a communications network. In a distributed computing environment, program modules may be located in both local and remote computer storage media including storage devices.

Other embodiments of the invention will readily occur to those skilled in the art upon consideration of the specification and practice of the invention disclosed herein. The present invention is intended to cover any variations, uses or adaptations of the present invention which follow the general principles of the present invention and include common knowledge or conventional techniques in the technical field not disclosed by the present invention . The specification and examples are to be regarded as exemplary only, with the true scope and spirit of the invention being indicated by the following claims.

It should be understood that the present invention is not limited to the precise structures described above and illustrated in the accompanying drawings, and that various modifications and changes may be made without departing from its scope. The scope of the present invention is limited only by the appended claims.

Claims (10)

1. A fault location system for small-resistance grounded power grids, characterized in that the system includes a circuit to be tested and a power distribution master station, and the circuit to be tested includes a small resistance, a busbar and a trunk feeder; the busbar and the The main feeder is connected; the main feeder is provided with an outlet circuit breaker and a sectional circuit breaker; the sectional circuit breaker is arranged between the outlet circuit breaker and the end of the main feeder; the small resistance is arranged between the small resistance Between the connection point and the grounding point, the small resistance connection point is located on the bus; the main power distribution station is connected to the segmented circuit breaker through the network; the segmented circuit breaker is preset with voltage-time feeder automation functions, Closing to zero-voltage opening function and blocking closing function; the outlet circuit breaker is preset with the protection function of the first stage of steady-state zero-sequence overcurrent; The outlet circuit breaker is used to judge whether the zero-sequence current of the main feeder connected to itself is greater than the preset value, and if the zero-sequence current is greater than the preset value, the tripping action is performed; and, after the preset reclosing time period When power is on, the reclosing action is performed; The sectional circuit breaker is used to perform corresponding actions according to the voltage-time feeder automation function, the closing-to-zero-voltage opening function, and the blocking closing function after the outlet circuit breaker is reclosed After that, send its own status to the power distribution master station; The main power distribution station is used to receive the state of the segment circuit breaker, and determine whether there is a first segment circuit breaker that is in the closed-to-zero-voltage open state and the latched closed state, if there is the first segment circuit breaker. If the segment circuit breaker is selected, the position of the first segment circuit breaker is determined, and the second segment circuit breaker in the residual voltage lockout state is determined, and the position of the second segment circuit breaker is determined; and according to the first segment circuit breaker The location of the first segment circuit breaker and the location of the second segment circuit breaker determine the location of the ground fault. 2 . The fault location system according to claim 1 , wherein the system further comprises a branch feeder; the branch feeder is connected to the trunk feeder through a branch connection point, and the branch connection point is located at the outlet. 3 . Between the circuit breaker and the end of the main feeder; the branch feeder is provided with a branch circuit breaker; the main power distribution station is connected to the branch circuit breaker through a network; the branch circuit breaker is preset with a steady-state zero-sequence Flow section I protection function; The branch circuit breaker is used to send its own state to the main power distribution station after performing the first stage protection of the steady-state zero-sequence overcurrent; The main power distribution station is also used to receive the state of the branch circuit breaker, and determine whether there is a first branch circuit breaker in the steady state zero-sequence overcurrent stage I protection state, and if there is the first branch circuit breaker, Then the position of the first branch circuit breaker is determined, and according to the position of the first branch circuit breaker, the position of the ground fault is determined. 3. The fault location system according to claim 2, wherein the main power distribution station is further used for: If the first section circuit breaker does not exist, and the first branch circuit breaker does not exist, an instruction is issued to initiate other ground fault location methods. 4. The fault location system according to claim 2, wherein the location of the ground fault is determined according to the location of the first branch circuit breaker, and is obtained through the following steps: Based on the location of the first branch breaker, it is determined that the ground fault is located in an area between the first branch breaker and the end of the branch feeder. 5 . The fault location system according to claim 1 , wherein the main power distribution station determines the ground fault according to the position of the first section circuit breaker and the position of the second section circuit breaker. 6 . position, obtained by the following steps: Based on the position of the first section breaker and the position of the second section breaker, determine the area where the ground fault is located between the first section breaker and the second section breaker Inside. 6. The fault location system according to claim 1, wherein the small resistance is in a grounded state. 7 . The fault location system according to claim 1 , wherein the preset power-on delay closing time period in the voltage-time feeder automation function is 7 seconds, and the preset power-on hold time period is 5 seconds. 8 . , the preset voltage loss delay opening time period is 0.5 seconds. 8 . The fault location system according to claim 1 , wherein the preset reclosing time period is greater than or equal to 1 second and less than or equal to 10 seconds. 9 . 9. A fault location method for small-resistance grounded power grids, characterized in that the method is applied in a fault system for small-resistance grounded power grids; the system includes a circuit to be tested and a power distribution master station, and the to-be-tested power distribution master station is The circuit includes a small resistance, a bus bar and a main feeder; the bus is connected to the main feeder; the main feeder is provided with an outlet circuit breaker and a sectional circuit breaker. The sectional circuit breaker is arranged between the outlet circuit breaker and the between the ends of the main feeder; the small resistance is arranged between the small resistance connection point and the grounding point, and the small resistance connection point is located on the bus; the main power distribution station is connected to the segmented circuit breaker through the network ;The section circuit breaker is preset with the voltage-time feeder automation function, the closing-to-zero-voltage opening function, and the blocking closing function; the outlet circuit breaker is preset with the steady-state zero-sequence overcurrent stage I protection function; The outlet circuit breaker judges whether the zero-sequence current of the main feeder connected to itself is greater than a preset value; If the outlet circuit breaker determines that the zero-sequence current is greater than the preset value, the tripping action is performed; The outlet circuit breaker is powered on after the preset reclosing time period, and performs the reclosing action; After the outlet circuit breaker is reclosed, the sectional circuit breaker performs corresponding actions according to the voltage-time feeder automation function, the closing-to-zero-voltage opening function, and the blocking closing function. The power distribution master station sends its own status; the power distribution master station receives the status of the segment circuit breaker; The main power distribution station judges whether there is a first segment circuit breaker that is in a closed-to-zero-voltage open state and a latched closed state; If the main power distribution station determines that the first segment circuit breaker exists, determine the position of the first segment circuit breaker, determine the second segment circuit breaker in a residual voltage blocking state, and determine the The location of the second segment circuit breaker; The main power distribution station determines the position of the ground fault according to the position of the first section breaker and the position of the second section breaker. 10 . The fault location method according to claim 9 , wherein the system further comprises a branch feeder; the branch feeder is connected to the trunk feeder through a branch connection point, and the branch connection point is located at the outlet. 11 . Between the circuit breaker and the end of the main feeder; the branch feeder is provided with a branch circuit breaker; the main power distribution station is connected to the branch circuit breaker through a network; the branch circuit breaker is preset with a steady-state zero-sequence Flow I section protection function; the method further includes: After the branch circuit breaker performs the steady-state zero-sequence overcurrent stage I protection, it sends its state to the main power distribution station; The main power distribution station receives the state of the branch circuit breaker, determines whether there is a first branch circuit breaker in the steady state zero-sequence overcurrent stage I protection state, and if the first branch circuit breaker exists, determines the The location of the first branch circuit breaker is determined, and the location of the ground fault is determined according to the location of the first branch circuit breaker.

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