CN103683227A - Method for matching two-section protection level difference of alternating current power supply for transformer substation - Google Patents

Abstract

The invention provides a method for coordinating the two-stage protection level difference of an AC power supply for a substation station, including: the overcurrent protection time and overcurrent setting value of the I stage protection of the substation AC incoming switch, and the overcurrent protection time and overcurrent protection time of the II stage protection Over-current setting value, the over-current protection time of the set stage I protection and the over-current protection time of stage II protection are shorter than the protection time of the upper high-voltage switch of the station transformer; when an over-current fault occurs, if the over-current If the current is within the overcurrent setting range of stage II protection, jump into the line switch according to the set overcurrent protection time delay of stage II protection; if the overcurrent is within the overcurrent setting range of stage I protection, then follow the The overcurrent protection time delay of the set I-section protection jumps into the line switch; at the same time, the II-section protection also starts the jump-in line switch, and the I-section and II-section protections output successively. The implementation of the present invention can effectively prevent the switch from refusing to move, and realize The level difference coordination protection of the AC incoming line switch of the station transformer and the high-voltage switch of the station transformer.

Description

A method for coordination of two-stage protection levels of AC power supplies for substations

technical field

The invention relates to the field of electric power technology, in particular to a method for coordinating the two-stage protection level difference of an AC power supply used in a substation.

Background technique

In the prior art, the existing substation AC power incoming switch is inverse time-limit protection. When the overcurrent multiple does not reach the instantaneous trip protection, it may take 10 seconds or 100 seconds to break the switch. At this time, the station Use the definite time protection trip of the upper-level high-voltage switch, which belongs to the leapfrog trip protection.

In recent years, leapfrog trip protection faults have occurred frequently, such as:

Case 1: On March 6, 2005, a 220kV substation had a live load ground fault, the AC feeder switch and the AC incoming line switch did not trip, and the substation substation zero-sequence overcurrent protection leapfrog action tripped #1 station substation, and the 380V backup self-injection action switched, Because the fault is still there, the zero-sequence overcurrent protection of station #2 is tripped by leapfrog action. After the AC power failure of the whole station, the air-cooled motor of the main transformer was affected, and the main transformer was forced to shut down, resulting in a large-scale power outage.

Cause of the accident:

The life load switch is not equipped with leakage protection, which cannot reflect the ground fault for isolation;

After the substation substation zero-sequence overcurrent protection leapfrog action tripped, the 380V standby automatic switchover expanded the scope of the accident.

Case 2: A feeder branch BN short circuit occurred in a 220kV substation in July 2011. The feeder switch did not trip, and the station AC incoming switch did not trip. The protection does not cooperate and the wiring principle is that the grounding protection does not operate. After the substation substation zero-sequence overcurrent protection leapfrog action trips, the 380V standby automatic switchover expands the scope of the accident, causing the AC power loss of the entire station.

Cause of the accident:

The thermal magnetic protection action curve of the switch does not cooperate with the substation protection after the phase zero fault, and the fault cannot be isolated in time;

After the substation substation zero-sequence overcurrent protection leapfrog action tripped, the 380V standby automatic switchover expanded the scope of the accident.

Case 3: In January 2012, a feeder branch ABC phase-to-phase short circuit occurred in a 110kV substation, the feeder switch did not trip, the station AC incoming switch did not trip, the station substation over-current protection leapfrogged, and the 380V standby automatic switching action was not blocked, resulting in The AC power supply for all stations has lost power.

Cause of the accident:

(1) After the ABC phase-to-phase short-circuit fault of the switch, the thermal-magnetic protection action curve does not cooperate with the station substation protection, and the fault cannot be isolated in time;

(2) After the substation transformer overcurrent protection leapfrog action tripped, the 380V standby automatic switchover expanded the scope of the accident.

It can be seen from the above accidents that the entire substation will be blacked out when the leapfrog tripping protection operates, which will bring huge losses to the entire power system.

Contents of the invention

In order to solve the above-mentioned technical problems, the present invention provides a method for coordinating the two-stage protection level difference of an AC power supply used in a substation, including:

Set the overcurrent protection time and overcurrent setting value of the I section protection of the station substation AC incoming line switch that matches the substation station high voltage switch, and the overcurrent protection time and overcurrent setting value of the II section protection, said The overcurrent protection time of the set stage I protection and the overcurrent protection time of stage II protection are shorter than the protection time of the upper high-voltage switch of the station transformer;

When a fault occurs, if the overcurrent is within the overcurrent setting range of stage II protection, it will jump into the line switch according to the set overcurrent protection time delay of stage II protection;

If the over-current is within the over-current setting range of stage I protection, the jump-in line switch will be delayed according to the set over-current protection time of stage I protection; at the same time, stage II protection will also start the jump-in line switch, and stage I and II Segment protection is output successively to prevent the switch from refusing to move.

Among them, if the overcurrent is within the overcurrent setting range of the I-stage protection, the step of jumping into the line switch is delayed according to the set overcurrent protection time of the I-stage protection, including:

Step 1, judge whether the I-stage overcurrent protection control word is enabled or not, and if enabled, perform step 2;

Step 2: Determine whether the maximum value of the three-phase currents of A, B, and C is greater than the overcurrent setting value of the I-stage protection; if so, continue to judge whether the over-current delay time of the I-stage protection is greater than the set I-stage protection overcurrent setting flow protection time, if yes, go to step 3.

Step 3: Overcurrent protection action, switch the blocking signal, and the relay opens to act, prompting the occurrence of external overcurrent, and the overcurrent blocking switch.

Step 4: Determine whether the control word of the I-stage protection overcurrent jump-in line is enabled; if enabled, perform step 5;

Step 5: Remotely control the relay, send out a pulse signal for 3 seconds, and jump off the two incoming line switches.

Wherein, if the overcurrent is within the overcurrent setting range of the II stage protection, the steps of jumping into the line switch according to the overcurrent protection time delay of the set II stage protection include:

Step 1: Determine whether the overcurrent protection control word of stage II protection is enabled or not, and if enabled, go to step 2;

Step 2: Determine whether the maximum value of the three-phase phase currents of A, B, and C is greater than the overcurrent setting value of the second stage protection; if so, continue to judge whether the overcurrent delay time of the second stage protection is greater than the set II stage protection Overcurrent protection time, if so, go to step 3;

Step 3: Overcurrent protection action, switch the blocking signal, and the relay opens to act, prompting the occurrence of external overcurrent, and the overcurrent blocking switch;

Step 4: Determine whether the control word of the stage II protection overcurrent jump-in line is turned on; if turned on, go to step 5;

Step 5: Remotely control the relay, send out a pulse signal for 3 seconds, and jump off the two incoming line switches.

Implementation of the present invention provides a method for coordinating the two-stage protection of AC power supplies in substations. By setting the I-stage and II-stage definite time protections, the setting time and current setting of the two-stage protections are matched with the high-voltage switch of the substation transformer. And the set protection time is shorter than the protection time set by the superior switch. When an over-current fault occurs, if the over-current is within the protection setting value of Section II, then jump into the line switch according to the time delay set by Section II protection; if the over-current is within the setting value of Section I protection (including the setting value of Section II protection ), the jump-in line switch is delayed according to the set time of the I-section protection, and the II-section protection also starts the jump-in line, and the I-section and II-section protection output successively to prevent the switch from refusing to move. Realize the level differential coordination protection of the AC incoming line switch of the station substation and the upper high-voltage switch of the station substation.

Description of drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings that need to be used in the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description are only These are some embodiments of the present invention. Those skilled in the art can also obtain other drawings based on these drawings without creative work.

Fig. 1 is a schematic flow chart of Embodiment 1 of a method for coordinating two-stage protection levels of AC power supplies for substations provided by the present invention;

Fig. 2 is a schematic flow chart of the second embodiment of the method for the coordination of two-stage protection levels of AC power supplies for substations provided by the present invention;

Fig. 3 is a schematic flow chart of Embodiment 3 of the method for coordinating two-stage protection levels of an AC power supply used in a substation according to the present invention.

Detailed ways

Fig. 1 is a schematic flow chart of Embodiment 1 of a method for coordinating two-stage protection levels of AC power supplies for substations provided by the present invention;

As shown in Figure 1, the present invention provides a method for coordinating the two-stage protection level difference of an AC power supply used in a substation, including:

Step 100, setting the overcurrent protection time and overcurrent setting value of the stage I protection of the substation substation AC incoming switch matching the substation substation transformer upper level high voltage switch, and the overcurrent protection time and overcurrent setting value of the II stage protection , the overcurrent protection time of the set stage I protection and the overcurrent protection time of stage II protection are shorter than the protection time of the upper high voltage switch of the station transformer;

Step 101, when a fault occurs, if the overcurrent is within the overcurrent setting range of stage II protection, delay jumping into the line switch according to the set overcurrent protection time of stage II protection;

Step 102, if the overcurrent is within the overcurrent setting range of the I-stage protection, then jump into the line switch according to the overcurrent protection time delay of the set I-stage protection; meanwhile, the II-stage protection also starts the jump-in line switch, and the I Stage and stage II protections are output successively to prevent the switch from refusing to move.

Fig. 2 is a schematic flow chart of the second embodiment of the method for the coordination of two-stage protection levels of AC power supplies for substations provided by the present invention;

This embodiment two will describe the specific implementation process of the step of jumping into the line switch according to the overcurrent protection time delay of the set I-stage protection if the over-current is within the over-current setting range of the I-stage protection, including:

Step 200, judge whether the I-stage overcurrent protection control word is enabled or not, if enabled, execute step 201; otherwise, return to execute step 200.

Step 201: Determine whether the maximum value of the A, B, and C three-phase phase currents is greater than the overcurrent setting value of the I-stage protection; if so, continue to judge whether the over-current delay time of the I-stage protection is greater than the set I-stage protection. flow protection time, if yes, execute step 202; if no, return to step 200.

Step 202: The overcurrent protection is activated, the blocking signal is switched, and the relay is switched on to indicate that an external overcurrent occurs, and the overcurrent blocking is switched.

Step 203: Determine whether the control word of the I-stage protection overcurrent jump-in line is enabled; if enabled, execute step 204; otherwise, return to execute step 200.

Step 204: Remotely control the relay, send out a pulse signal for 3 seconds, and jump off the two incoming line switches.

Fig. 3 is a schematic flow chart of Embodiment 3 of the method for coordinating two-stage protection levels of an AC power supply used in a substation according to the present invention.

The third embodiment will describe the implementation process of the step of jumping into the line switch according to the overcurrent protection time delay of the set II stage protection if the overcurrent is within the overcurrent setting range of the stage II protection, including:

Step 300: Determine whether the overcurrent protection control word of stage II protection is enabled or not, if enabled, execute step 301; otherwise, return to execute step 300.

Step 301: Judging whether the maximum value of the three-phase currents of A, B, and C is greater than the overcurrent setting value of the stage II protection; if so, continue to judge whether the overcurrent delay time of the stage II protection is greater than the set stage II protection Overcurrent protection time, if yes, execute step 302; otherwise, return to execute step 300.

Step 302: the overcurrent protection is activated, the blocking signal is switched, the relay is switched on, and the external overcurrent is prompted, and the overcurrent blocking is switched;

Step 303: Determine whether the control word of the stage II protection overcurrent jump-in line is enabled; if enabled, execute step 304; otherwise, return to execute step 300.

Step 304: Remotely control the relay, send out a pulse signal for 3 seconds, and jump off the two incoming line switches.

Implementation of the present invention provides a method for coordinating the two-stage protection of AC power supplies in substations. By setting the I-stage and II-stage definite time protections, the setting time and current setting of the two-stage protections are matched with the high-voltage switch of the substation transformer. And the set protection time is shorter than the protection time set by the superior switch. When an over-current fault occurs, if the over-current is within the protection setting value of Section II, then jump into the line switch according to the time delay set by Section II protection; if the over-current is within the setting value of Section I protection (including the setting value of Section II protection ), the jump-in line switch is delayed according to the set time of the I-section protection, and the II-section protection also starts the jump-in line, and the I-section and II-section protection output successively to prevent the switch from refusing to move. Realize the level differential coordination protection of the AC incoming line switch of the station substation and the upper high-voltage switch of the station substation.

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

The above content is a further detailed description of the present invention in conjunction with specific preferred embodiments, and it cannot be assumed that the specific implementation of the present invention is limited to these descriptions. For those of ordinary skill in the technical field of the present invention, without departing from the concept of the present invention, some simple deduction or replacement can be made, which should be regarded as belonging to the protection scope of the present invention.

Claims (3)

1. A method for coordinating the two-stage protection level difference of an AC power supply in a substation, characterized in that it comprises: Set the overcurrent protection time and overcurrent setting value of the I section protection of the station substation AC incoming line switch that matches the substation station high voltage switch, and the overcurrent protection time and overcurrent setting value of the II section protection, said The overcurrent protection time of the set stage I protection and the overcurrent protection time of stage II protection are shorter than the protection time of the upper high-voltage switch of the station transformer; When a fault occurs, if the overcurrent is within the overcurrent setting range of stage II protection, it will jump into the line switch according to the set overcurrent protection time delay of stage II protection; If the over-current is within the over-current setting range of stage I protection, the jump-in line switch will be delayed according to the set over-current protection time of stage I protection; at the same time, stage II protection will also start the jump-in line switch, and stage I and stage II The protection is sequentially output to prevent the switch from refusing to move. 2. the method for substation as claimed in claim 1 uses two sections of protection level difference of AC power supply to cooperate, it is characterized in that, if described overcurrent is in the overcurrent fixed value range of I section protection, then according to the I section of setting The steps of the over-current protection time-delay jump-in line switch for protection include: Step 1, judge whether the I-stage overcurrent protection control word is enabled or not, and if enabled, perform step 2; Step 2: Determine whether the maximum value of the three-phase phase current of A, B, and C is greater than the overcurrent setting value of the I-stage protection; if so, continue to judge whether the over-current delay time of the I-stage protection is greater than the set I-stage protection overcurrent setting flow protection time, if yes, go to step 3. Step 3: Overcurrent protection action, switch the blocking signal, and the relay opens to act, prompting the occurrence of external overcurrent, and the overcurrent blocking switch. Step 4: Determine whether the control word of the I-stage protection overcurrent jump-in line is enabled; if enabled, perform step 5; Step 5: Remotely control the relay, send out a pulse signal for 3 seconds, and jump off the two incoming line switches. 3. The method for realizing step-by-step coordination between the AC incoming line switch and the upper-level high-voltage switch in the substation as claimed in claim 2, wherein if the overcurrent is within the overcurrent setting value range of II section protection, then according to Steps for setting the overcurrent protection time delay of stage II protection and jumping into the line switch include: Step 1: Determine whether the overcurrent protection control word of stage II protection is enabled or not, and if enabled, go to step 2; Step 2: Determine whether the maximum value of the three-phase phase currents of A, B, and C is greater than the overcurrent setting value of the second stage protection; if so, continue to judge whether the overcurrent delay time of the second stage protection is greater than the set II stage protection Overcurrent protection time, if so, go to step 3; Step 3: Overcurrent protection action, switch the blocking signal, and the relay opens to act, prompting the occurrence of external overcurrent, and the overcurrent blocking switch; Step 4: Determine whether the control word of the stage II protection overcurrent jump-in line is turned on; if turned on, go to step 5; Step 5: Remotely control the relay, send out a pulse signal for 3 seconds, and jump off the two incoming line switches.

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