CN105932658A - Arc-extinction apparatus for power distribution network and arc-extinction method for power distribution network by arc-extinction apparatus - Google Patents

Abstract

The invention provides an arc suppression device and method for a distribution network. The device includes a primary switch, a secondary switch, a voltage transformer, a voltage sampling unit, a current transformer, a monitoring unit, and a high-voltage fuse. The fuse is connected between the busbar and the ground grid; the high-voltage ends of the three single-phase high-voltage switches of the primary switch are respectively connected to the three-phase busbar, and the low-voltage ends are connected in parallel to the high-voltage end of the secondary switch. The terminal series current transformer is connected to the ground grid, and the voltage sampling unit is connected between the high-voltage end of the secondary switch and the current transformer. The monitoring unit is used to monitor and monitor the secondary side phase voltage and the open triangle voltage output by the voltage transformer. Analyze the fault judgment result, output opening and closing commands, and control the action of the primary switch and the secondary switch. The invention can effectively eliminate the single-phase arc-light grounding fault of the distribution network caused by lightning flashover and the like, and has a protection function, and can effectively prevent phase-to-phase short-circuit when performing the arc-extinguishing action.

Description

Arc suppression device for distribution network and arc suppression method for distribution network using the device

technical field

The invention relates to the technical field of power system grounding fault processing, in particular to a distribution network arc suppression device and a method for using the device to perform distribution network arc suppression.

Background technique

my country's distribution network is an indirect neutral point grounding system, and arc suppression devices are required to eliminate single-phase grounding faults such as lightning flashovers. At present, the arc suppression devices of my country's distribution network are mainly arc suppression coils. The principle is that when a single-phase ground fault occurs in the power grid, an inductor current is provided to compensate the ground capacitance current, so that the current at the fault point is reduced, and the fault is connected The recovery voltage speed at both ends of the ground arc is reduced to achieve the purpose of extinguishing the arc. However, with the development of urban distribution networks and the application of high-voltage cables, the single-phase ground fault current continues to increase, and the capacity and cost of supporting arc suppression coils increase and increase significantly, and its price can sometimes reach hundreds of thousands of yuan; on the other hand If the power line is newly expanded, the change of the capacitance of the grid to ground will increase the single-phase ground fault current. When it exceeds the compensation range of the installed arc suppression coil, it is necessary to replace or add a new arc suppression coil, which will reduce the investment and cost of distribution network equipment. The management workload has increased significantly.

Contents of the invention

The object of the present invention is to provide a distribution network arc suppression device and a method for using the device to carry out distribution network arc suppression. Fault, and there is no strict limit on the magnitude of the fault current, even if the power grid expands the new line, the device does not need to be adjusted, and it has a protection function, which can effectively prevent phase-to-phase short circuit when performing arc suppression action.

To achieve this goal, the present invention provides a distribution network arc suppression device, including a primary switch, a secondary switch, a voltage transformer, a voltage sampling unit, a current transformer, a monitoring unit and a high-voltage fuse, the voltage transformer A series of high-voltage fuses is connected between the busbar and the ground network; the first-level switch is three single-phase high-voltage switches, the second-level switch is a single-phase high-voltage switch, and the first-level switch is three single-phase high-voltage switches The high-voltage end is connected to the three-phase busbar respectively, and the low-voltage end is connected in parallel to the high-voltage end of the secondary switch. Between the current transformers, the monitoring unit is used to obtain the secondary side phase voltage and open triangle voltage output by the voltage transformer, the voltage between the high-voltage end of the secondary switch and the ground grid output by the voltage sampling unit, and the voltage monitored by the current transformer. The current of the circuit formed by the ground network is monitored and analyzed according to the secondary side phase voltage and the open triangle voltage of the voltage transformer to obtain the fault judgment result, and the opening and closing instructions are output according to the fault judgment result to control the primary switch and the secondary switch. stage switching action.

Further, the withstand voltage level of the single-phase high-voltage switch is the same as the voltage level of the distribution network.

Further, the withstand voltage level of the voltage transformer is the same as the voltage level of the distribution network, and the voltage transformer has a secondary side phase voltage winding and an open delta winding.

Further, the voltage sampling unit is used to obtain the voltage between the high-voltage end of the secondary switch and the ground grid, the voltage sampling unit is a high-voltage divider or a single-phase voltage transformer, and the withstand voltage level is the same as the distribution network voltage The grades are the same.

Further, the voltage level of the high-voltage fuse is the same as that of the distribution network.

Further, the monitoring unit is also used to display voltage and current data and state information, the display data includes the secondary side phase voltage and open triangle voltage output by the voltage transformer, the voltage at both ends of the secondary switch output by the voltage sampling unit, and the current mutual inductance The circuit current value output by the device, and the status information includes the phase difference of the fault phase, the execution status of the first-level switching action command, and the execution status of the second-level switching command.

A method for arc suppression of distribution network using the above-mentioned device. The monitoring unit obtains the secondary side phase voltage and open delta voltage output by the voltage transformer, and performs data analysis. When an arc ground fault occurs in the distribution network, the secondary side When the phase voltage and open delta voltage change abnormally, the monitoring unit judges the fault phase through the fault phase identification program, and issues an instruction to control the primary switch and secondary switch to perform closing action, and after a certain time delay, issue an opening command , to control the primary switch and the secondary switch to perform the opening action, thus completing the arc suppression function.

Further, if the fault phase judgment of the monitoring unit is correct, and the high-voltage switch connected to the fault phase by the primary switch is closed, the voltage applied to the voltage sampling unit is a low voltage for the fault phase, and the secondary switch is not locked when the voltage is low. After receiving the command from the monitoring unit, the switch can be closed, so that the faulty phase of the busbar is connected to the ground grid. After a certain delay, the air insulation at the fault point will be restored, and the monitoring unit will issue another command to control the opening of the first-level switch and the second-level switch. If the judgment of the faulty phase is wrong, the monitoring unit sends an instruction to control the first-level switch to be connected to the high-voltage switch on the faulty phase judged by the program. The first-level switch is in the locked state, and the second-level switch will refuse to close after receiving the closing command, so as to avoid the misjudgment of the faulty phase and cause the phase-to-phase short circuit accident. After a certain time delay, the monitoring unit will issue an instruction to control the first-level switch and the second-level switch. Opening.

The present invention adopts above-mentioned technical scheme to have following beneficial effect and advantage:

The present invention is composed of a conventional single-phase high-voltage switch, a voltage transformer, a current transformer and a monitoring unit, so it has the advantages of simple structure and low cost; since the high-voltage switch is the only switching device to realize the transfer of the fault current path, the conventional high-voltage switch The current capacity can reach more than 1000A, and the fault current is generally below 100A, so the present invention has no strict limit on the size of the fault current, even if the power grid expands and expands new lines, the device does not need to be adjusted, which greatly reduces the investment and management workload of distribution network equipment , the economic benefit is obvious.

The present invention adds a safety protection device composed of a high-voltage divider or a single-phase voltage transformer to the control circuit. If a fault phase judgment error occurs, the protection device can keep the high-voltage switch in a locked state and does not execute the closing command. Therefore, the present invention The invention can prevent phase-to-phase short-circuit accidents and ensure the safety of the power grid, thereby facilitating popularization and application.

Description of drawings

Fig. 1 is a schematic diagram of the circuit structure of the arc suppressing device for distribution network of the present invention.

In the figure: 1—first-level switch, 2—secondary switch, 3—voltage transformer, 4—voltage sampling unit, 5—current transformer, 6—monitoring unit, 7—high voltage fuse.

detailed description

The technical solutions in the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the present invention.

Figure 1 is a schematic diagram of the circuit structure of a distribution network arc suppression device according to the present invention. The distribution network arc suppression device includes a primary switch 1, a secondary switch 2, a voltage transformer 3, a voltage sampling unit 4, a current Transformer 5, monitoring unit 6 and high voltage fuse 7.

The primary switch 1 is three single-phase high-voltage switches, their high-voltage terminals are respectively connected to the three-phase bus, and the low-voltage terminals are connected in parallel to the high-voltage terminal of the secondary switch 2 .

The secondary switch 2 is a single-phase high-voltage switch, the high-voltage end of which is connected to the low-voltage end of the primary switch 1 , and the low-voltage end is connected to the ground network through a current transformer 5 .

The voltage transformer 3 series high-voltage fuse 7 is connected between the bus bar and the ground grid, and the voltage transformer 3 has a secondary side phase voltage winding and an open delta winding.

The voltage sampling unit 4 is connected between the high-voltage end of the secondary switch 2 and the current transformer 5 , and is used to obtain a voltage signal and output it to the monitoring unit 6 .

The current transformer 5 is connected in series in the loop between the secondary switch 2 and the ground grid for monitoring the loop current.

The input terminals of the monitoring unit 6 are respectively connected with the output terminals of the voltage transformer 3 , the voltage sampling unit 4 and the current transformer 5 , and the output terminals of the monitoring unit 6 are connected with the primary switch 1 and the secondary switch 2 respectively. The monitoring unit 6 is used to monitor and analyze the secondary side phase voltage and the open delta voltage of the voltage transformer 3, and if it is analyzed that there is a faulty phase, then control the primary switch 1 and the secondary switch 2 to perform closing action, In order to realize functions such as arc suppression and information display.

Working principle of the present invention:

When the power grid is in normal operation, both the primary switch 1 and the secondary switch 2 are in the open state. When a single-phase arc-flash ground fault occurs in the distribution network due to lightning flashover, the monitoring unit 6 detects abnormal changes in the phase voltage and open-delta voltage on the secondary side of the voltage transformer 3, and the monitoring unit 6 first analyzes the voltage through the fault phase identification program The voltage on the secondary side of the transformer 3 automatically determines the faulty phase, and then sends a closing command to the primary switch 1 and the secondary switch 2 in sequence. At this time, if the judgment of the faulty phase is correct, and the high-voltage switch connected to the faulty phase by primary switch 1 is closed, the voltage applied to the voltage sampling unit 4 is the faulty phase voltage (less than the non-faulty phase voltage), which is low voltage, low voltage At this time, the secondary switch 2 is not locked, and the switch can be realized after receiving the instruction from the monitoring unit 6, so that the busbar fault phase is connected to the ground network. Because the grounding resistance of the ground network is much smaller than the grounding resistance of the line fault point, the power frequency continuous flow of the line fault point Most of them are shunted to the ground grid, and the remaining residual current is very small. After the current crosses zero, the arc is extinguished, and the power frequency continuous current forms a loop through the ground grid to realize current transfer. After a delay of Δt (several seconds), the air insulation at the fault point has disappeared. After being recovered, the monitoring unit 6 issues an instruction to control the opening of the primary switch 1 and the secondary switch 2. The entire arc suppression process is completed, and the power grid can resume normal operation. At this time, the arc suppression device returns to the initial state.

If the judgment of the faulty phase is wrong, the monitoring unit 6 issues an instruction to control the primary switch 1 to be connected to the high-voltage switch on the faulty phase judged by the program. Voltage) is a high voltage. Due to the existence of the high voltage, the secondary switch 2 is in a locked state. Therefore, even if the secondary switch 2 receives the closing command, it will refuse to close and not close, thereby avoiding misjudgment of the faulty phase and causing short-circuit accidents between phases. After a delay of Δt (several seconds), the monitoring unit 6 issues an instruction to control the opening of the primary switch 1 and the secondary switch, the entire arc suppression device returns to the initial state, and restarts the signal collection, fault phase identification and arc suppression device control procedures.

The secondary side signal of the current transformer 5 reflects the fault current flowing through the arc suppression device, and its data collection and information display are completed by the monitoring unit 6 .

The above is only a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto, any changes or substitutions that can be easily imagined by those skilled in the art within the technical scope disclosed in the present invention, All should be covered within the protection scope of the present invention. Therefore, the protection scope of the present invention should be determined by the protection scope of the claims.

Claims (8)

1. An arc suppressing device for distribution network, characterized in that it includes a primary switch (1), a secondary switch (2), a voltage transformer (3), a voltage sampling unit (4), and a current transformer (5) , a monitoring unit (6) and a high-voltage fuse (7), the voltage transformer (3) series high-voltage fuse (7) is connected between the busbar and the ground network; the first-level switch (1) is three single phase high-voltage switch, the secondary switch (3) is a single-phase high-voltage switch, the high-voltage ends of the three single-phase high-voltage switches of the primary switch (1) are respectively connected with the three-phase busbar, and the low-voltage end is connected in parallel with the secondary The high-voltage end of the switch (2) is connected, the low-voltage end of the secondary switch (2) is connected in series with the current transformer (5) to the ground network, and the voltage sampling unit (4) is connected to the high-voltage end of the secondary switch (2) and the current Between the transformers (5), the monitoring unit (6) is used to obtain the secondary side phase voltage and the open triangle voltage output by the voltage transformer (3), and the high voltage of the secondary switch (2) output by the voltage sampling unit (4) The voltage between the terminal and the ground grid and the current formed by the ground grid monitored by the current transformer (5) are monitored and analyzed according to the secondary side phase voltage and the open triangle voltage of the voltage transformer (3) to obtain a fault According to the judgment result, the opening and closing commands are output according to the fault judgment result, and the actions of the primary switch (1) and the secondary switch (2) are controlled. 2. The arc suppressing device for distribution network according to claim 1, characterized in that: the single-phase high-voltage switch withstand voltage level is the same as the distribution network voltage level. 3. The arc suppression device for distribution network according to claim 1, characterized in that: the withstand voltage level of the voltage transformer (3) is the same as the voltage level of the distribution network, and the voltage transformer (3) has Secondary side phase voltage winding and open delta winding. 4. The arc suppression device for distribution network according to claim 1, characterized in that: the voltage sampling unit (4) is used to obtain the voltage between the high voltage end of the secondary switch (2) and the ground network, the The voltage sampling unit (4) is a high-voltage voltage divider or a single-phase voltage transformer, and its withstand voltage level is the same as that of the distribution network. 5. The arc suppressing device for distribution network according to claim 1, characterized in that: the voltage level of the high voltage fuse (7) is the same as that of the distribution network. 6. The arc suppression device for distribution network according to claim 1, characterized in that: the monitoring unit (6) is also used to display voltage and current data and status information, and the voltage and current data includes voltage transformer (3) The output secondary side phase voltage and open triangle voltage, the voltage across the secondary switch (2) output by the voltage sampling unit (4) and the loop current value output by the current transformer (5), the state information includes the fault phase Phase difference, the execution state of the first-level switch action command, and the execution state of the second-level switch command. 7. A method for using the device described in any one of claims 1-6 to perform arc suppression in a distribution network, characterized in that: the monitoring unit (6) obtains the secondary side phase voltage output by the voltage transformer (3) and open delta voltage, and conduct data analysis. When an arc ground fault occurs in the distribution network, the phase voltage on the secondary side and the open delta voltage change abnormally. The monitoring unit (6) judges the fault phase through the fault phase identification program and sends command to control the first-level switch (1) and second-level switch (2) to perform the closing action, and after a certain time delay, issue an opening command to control the first-level switch and the second-level switch to perform the opening action, thereby completing arc suppression Features. 8. The method for arc suppression of distribution network as claimed in claim 7, characterized in that: if the monitoring unit (6) judges the faulty phase correctly, and the primary switch (1) is connected to the high-voltage switch on the faulty phase to switch on, then The voltage applied to the voltage sampling unit (4) is the fault phase voltage is a low voltage, the secondary switch (2) is not locked when the voltage is low, and can be closed after receiving the instruction from the monitoring unit (6), so that the bus fault phase Connected to the ground network, after a certain time delay, the air insulation at the fault point is restored, and the monitoring unit (6) sends out an instruction to control the opening of the primary switch (1) and secondary switch (2); if the fault phase is judged incorrectly, the monitoring The unit (6) issues an instruction to control the primary switch (1) after the high-voltage switch connected to the faulty phase judged by the program is closed, because the voltage applied to the voltage sampling unit (4) is a non-faulty phase voltage and is a high voltage, The secondary switch (2) is in the locked state, and the secondary switch (2) will refuse to close the switch after receiving the closing command, so as to avoid misjudgment of the faulty phase and cause a short circuit accident between phases. After a certain time delay, the monitoring unit (6) will An instruction is issued to control the opening of the primary switch (1) and the secondary switch (2).