Current grounding line selection debugging method

Abstract

The invention provides a current grounding line selection debugging method. The method comprises the step of debugging a voltage transformer, a current transformer, a grounding transformer, an automatic tuning type arc suppression coil, a selective installation device and a zero sequence transformer in slave system equipment one by one. A voltage transformer, a current transformer, a grounding transformer, an automatic tuning type arc suppression coil, a selective installation device, a zero sequence transformer and the like in system equipment are decomposed, refined and explained one by one, and the purposes and the mutual relation are explained through debugging methods such as checking and testing; the debugging method of the small-current grounding line selection equipment and device of the 10kV transformer substation system is completely embodied, the problems of wrong selection and missing selection of small-current grounding line selection are systematically debugged, simulated and solved, and the situation that due to the fact that the number of feed-out cables of the 10kV transformer substation is large, the ground capacitance current is increased, and the fault rate of the small-current grounding line selection equipment and device is reduced is avoided. And after single-phase grounding, the current flowing through a fault point is relatively large, the arc is not easy to extinguish, and overvoltage is caused to cause tripping of a circuit breaker of the switch cabinet.

Description

Technical Field

[0001] The present invention relates to the technical field of electrical engineering, and more particularly, to a debugging method for current grounding line selection. Background Art

[0002] Currently, for systems composed of 3 - 10 kV overhead lines and all 35 and 66 kV power grids, when the single - phase grounding fault current is greater than 10 A, an arc suppression coil should be installed at the neutral point; for systems composed of 3 - 10 kV cable lines, when the single - phase grounding fault current is greater than 30 A, an automatic tuning arc suppression coil and a small - current line selection device should be installed at the neutral point.

[0003] Due to a 10 kV substation under construction in an engineering project, considering safety and other factors, the neutral - point grounding method of the system is designed to operate in an ungrounded mode. However, for the consideration of the grounding fault current, a neutral point is artificially added to the substation bus system, and small - current grounding line selection for the faulty phase of the substation is carried out through the automatic tuning of the arc suppression coil and the control panel.

[0004] Currently, problems such as mis - selection and missed - selection occur during the operation of the substation, resulting in a relatively high accident tripping rate of the substation lines, and even phenomena of personal injury and equipment damage. Summary of the Invention

[0005] In view of this, the present invention proposes a debugging method for current grounding line selection, aiming to solve the problems that mis - selection and missed - selection occur during the operation of the existing substation, resulting in a relatively high accident tripping rate of the substation lines, and even personal injury and equipment damage.

[0006] The present invention provides a current grounding line selection debugging method, which uses a current grounding line selection debugging system for line selection debugging; the current grounding line selection debugging system includes: an arc suppression coil control panel, a first voltage transformer, a second voltage transformer, a on-load arc suppression coil, a damping resistor, a current transformer, a grounding transformer, a circuit breaker, a unidirectional circuit breaker, a parallel middle resistor, and a thyristor; wherein, the arc suppression coil control panel is respectively connected to the first voltage transformer, the current transformer, the on-load arc suppression coil, the damping resistor, and the current transformer, the arc suppression coil control panel and the first voltage transformer are connected to the bus, the current transformer, the damping resistor, the on-load arc suppression coil, the grounding transformer, and the circuit breaker are connected in series and connected to the bus, and a lightning arrester is also connected to this series circuit; one side of the second voltage transformer is connected to the arc suppression coil control panel, and the other side is connected to the unidirectional circuit breaker and the parallel middle resistor and grounded; the current grounding line selection debugging method includes the following steps: a transformer debugging step, performing insulation, DC resistance of the winding, and AC withstand voltage debugging on the grounding transformer, and judging the debugging results during the debugging process to determine whether the selected grounding transformer meets the preset transformer selection criterion; an arc suppression coil debugging step, performing insulation, DC resistance, and AC withstand voltage debugging on the on-load arc suppression coil, and judging the debugging results during the debugging process to determine whether the selected grounding transformer meets the preset arc suppression coil selection criterion; a transformer debugging step, performing insulation, DC resistance, turns ratio, polarity / excitation characteristics, and AC withstand voltage debugging on the neutral point transformer, and judging the debugging results during the debugging process to determine whether the selected grounding transformer meets the preset transformer selection criterion; a circuit breaker debugging step, performing insulation, loop resistance, and switch mechanical characteristics debugging on the unidirectional circuit breaker, and judging the debugging results during the debugging process to determine whether the selected circuit breaker meets the preset circuit breaker selection criterion; a resistor debugging step, measuring the resistance values of the parallel middle resistor and the damping resistor, and judging based on the resistance values to determine whether the selected resistor meets the preset resistor criterion; a thyristor trigger debugging step, debugging the thyristor to obtain its trigger voltage and cut-off voltage to determine whether the thyristor meets the preset thyristor criterion; an on-load switch debugging step, debugging the on-load switch of the arc suppression coil to determine whether it meets the preset switch criterion; a control panel line selection debugging step, performing zero-sequence current sampling, bus voltage sampling, neutral point voltage and current sampling, control panel, and secondary circuit sampling of the 10kV switch cabinet once, and judging the results to determine whether it meets the preset line selection debugging criterion.

[0007] Furthermore, the above-mentioned current grounding line selection and debugging method performs insulation debugging on the grounding transformer, on-load arc suppression coil, neutral point mutual inductor, and one-way circuit breaker, specifically including: first check the meter, turn on the switch, the pointer should be "∞" in the open circuit state, and "0" in the short circuit state; the grounding terminal "E" is grounded, and the high-voltage output terminal "L" is connected to the test object for measurement. After the measurement, it is first disconnected from the test object, and the test instrument is turned off. After the test, the test object is fully discharged; a 2500V insulation resistance tester is used to measure the high-voltage side winding of the grounding transformer to the ground; a 500V insulation resistance tester is used to measure the low-voltage side winding, iron core and clamp of the grounding transformer to the ground.

[0008] Furthermore, the above-mentioned current grounding line selection and debugging method performs DC resistance debugging on the windings, on-load arc suppression coils, and neutral point mutual inductor of the grounding transformer, specifically including: checking the connecting instrument lines, the voltage terminal is close to the winding during wiring, and the current terminal is outside the voltage terminal; checking the stability of the instrument power supply to ensure accurate detection of the instrument and reliable grounding of the instrument.

[0009] Furthermore, the above-mentioned current grounding line selection and debugging method performs AC withstand voltage debugging on the grounding transformer, on-load arc suppression coil, and neutral point transformer, specifically including: external construction frequency withstand voltage test, the repetitive test voltage is 80% of the factory test voltage; the test equipment is subjected to air boost to check whether it can reach the test voltage value, and then the overvoltage protection value of the test equipment is adjusted, and the reliability of the protection action is checked; the grounding transformer is short-circuited between phases to the high-voltage output terminal of the AC withstand voltage device; the secondary side and the casing are reliably grounded; the AC withstand voltage device power supply is closed, the voltage is increased to 28kV test voltage, and maintained for 1min; then the voltage is returned to zero, and the AC withstand voltage device power supply is turned off; the test equipment and the short-circuit wire are removed.

[0010] Furthermore, in the above-mentioned current grounding line selection and debugging method, the preset transformer selection criteria include: the coil insulation resistance test value high voltage-low voltage and ground is greater than or equal to 5000MΩ, and the low voltage-high voltage and ground is greater than or equal to 0.4MΩ; the core insulation resistance test value core-clamp and ground is greater than or equal to 2MΩ, and the through screw-ground and core is greater than or equal to 2MΩ; the grounding transformer winding, the measured data conforms to the DC resistance change law of each gear; during the withstand voltage process, there is no visible abnormal phenomenon such as discharge, breakdown, smoke, abnormal sound, etc.; the insulation resistance after withstand voltage is greater than or equal to the insulation resistance before withstand voltage.

[0011] Further, for the above current grounding line selection debugging method, the preset arc suppression coil selection criteria include: the insulation resistance value of the high voltage - auxiliary and ground resistance value is greater than or equal to 1600 MΩ; the core - to - ground resistance value is greater than or equal to 2 MΩ; the measured data conforms to the variation law of the DC resistance of each gear, and the data from gear 1 to gear 9 gradually decreases; when the data of gear 9 has a jump and does not follow the resistance variation law, it is determined that the on - load tap - changer wiring is incorrect; the variation law of the measured value is consistent with the factory value; the response change compared with the factory value at the same temperature is less than or equal to 2%; the measured data conforms to the variation law of the DC resistance of each gear; during the withstand voltage process, there are no visible abnormal phenomena; the insulation resistance after withstand voltage is greater than or equal to the insulation resistance before withstand voltage.

[0012] Further, for the above current grounding line selection debugging method, the loop resistance debugging of the single - phase circuit breaker specifically includes: closing the circuit breaker, connecting the test wires to both sides of the moving contact and the static contact respectively, adjusting the current of the contact resistance tester to 100 A, and reading the resistance value, with the unit of ; The switch mechanical characteristic debugging method specifically includes: the two connecting test wires are respectively the closing and opening coil signal wires; connecting the closing and opening signals to both ends of the closing and opening coils respectively; clamping the lead - out wires of the contact signal socket to the upper port of the switch static contact and the upper and lower ports of the moving contact according to the color respectively; closing the power supply, pressing the measurement key, measuring the closing time and bounce, and displaying them on the display screen; then measuring the time in the opening state; conducting AC withstand voltage debugging on it, and the single - phase to - ground and circuit breaker break - point test voltages are 30 kV.

[0013] Further, for the above current grounding line selection debugging method, the preset circuit breaker selection criteria include: the main contact opening distance is within the range of 5.0 - 5.5 mm; the contact closing bounce time ≤ 5 ms; the closing time ≤ 120 ms is determined as a qualified test; there is no obvious difference in the loop resistance compared with the product factory test value; the measured data conforms to the variation law of the DC resistance of each gear; during the withstand voltage process, there are no visible abnormal phenomena such as discharge, breakdown, smoking, abnormal sounds, etc.; the insulation resistance after withstand voltage is greater than or equal to the insulation resistance before withstand voltage.

[0014] Further, for the above current grounding line selection debugging method, the debugging of the thyristor specifically includes: The 750 multi-functional tester selects the voltage output gear, and the voltage output ports are respectively connected to the thyristor control stage G and the cathode K; A voltmeter is connected in parallel on the output ports to monitor the output voltage; Before the voltage output, use the ohmmeter range test leads of the multimeter to test both ends of the damping resistor, and the measured resistance value is the damping resistor value; When the voltage applied to the thyristor control stage G and the cathode K ports reaches 370V, use the ohmmeter range test leads of the multimeter to test both ends of the damping resistor and there is no resistance and it is in a conducting state, indicating that the thyristor is already conducting at this time; After the thyristor conducts, the applied voltage slowly drops. When it reaches 368V, use the ohmmeter range test leads of the multimeter to test both ends of the damping resistor and there is resistance and it is in a blocking state to obtain the trigger voltage and the cut-off voltage.

[0015] Further, for the above current grounding line selection debugging method, the on-load tap-changer debugging steps specifically include: Use a 500V insulation resistance tester to test the power supply of the control and operating mechanism and the secondary circuit for insulation, and the test values are all greater than 1MΩ. In a relatively humid place, it is greater than 0.5MΩ; Check that the signal cable connection between the arc suppression coil automatic tap-changing device and the line selection control panel is reliable; The shielded wire is grounded regularly, and the device shell is firmly connected to the PE row; Check the AC220V and DC220V power supply voltage lines, measure the voltage value, and check the DC voltage polarity; Before the arc suppression coil automatic tap-changing device is powered on, manually test 7 gears continuously for 5 times; After the incoming line switch DC power supply of the arc suppression coil control cabinet is charged, close the main switch, and at this time the cabinet door power indicator light is always on; Close the control power supply and the tap-changing motor power supply in sequence, and the arc suppression coil automatic tap-changing returns to the zero position; Test the tap-changing device in the electric state. Each time the N+1 or N-1 button is pressed, the arc suppression coil gear automatically upshifts or downshifts; Check the arc suppression coil gear action DI and DO signal status signals inside the line selection control panel device; The preset switch criteria include: Use a multimeter to measure the working voltage of the control panel. The allowable deviation of the AC 220V is -20%~ +15%, and the allowable deviation of the DC voltage is ±10%; During the tap-changing process of the arc suppression coil on-load adjustment device in the manual and automatic states, the tension is constant and the switching is smooth, and there is no abnormal sound between the mechanical stranding components; The DI and DO signal status signals, the action and the feedback are consistent.

[0016] The current grounding line selection debugging method provided by the present invention decomposes, refines, and explains each component in the system equipment, such as voltage transformers, current transformers, grounding transformers, automatic tuning arc suppression coils, selection devices, and zero-sequence current transformers, one by one, and uses debugging methods such as inspections and tests to illustrate their uses and the relationships between them; it completely embodies the debugging method of the small current grounding line selection equipment and devices in the 10kV substation system, as well as systematic debugging, simulates and solves the problems of misselection and omission of small current grounding line selection, and avoids the problem of circuit breaker tripping in the switchgear caused by large current flowing through the fault point, difficult extinguishing of the arc, and overvoltage after single-phase grounding due to a large number of outgoing cables in the 10kV substation, which increases the capacitive current to the ground. Thus, it reduces the accident tripping rate of the substation lines, reduces personal injuries and equipment damage, and improves the safe operation and power supply reliability of the substation system. This method also has the following effects: 1. Increase the power supply reliability of urban power supply and distribution; 2. Prevent the further expansion of power outage accidents; 3. Be able to adapt to complex environments; 4. Add the function of automatic power supply restoration for small current grounding line selection; 5. Reduce manual intervention in the whole system.

[0017] 6. The debugging of the small current grounding line selection system is convenient, the method is simple, and the practicability is strong. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] By reading the detailed description of the preferred embodiments below, various other advantages and benefits will become clear to those of ordinary skill in the art. The drawings are only for the purpose of showing the preferred embodiments and are not considered to be a limitation of the present invention. Moreover, throughout the drawings, the same reference numerals are used to represent the same components. In the drawings: Figure 1 is the structural block diagram of the current grounding line selection debugging system provided by the embodiment of the present invention; Figure 2 is the flow block diagram of the current grounding line selection debugging method provided by the embodiment of the present invention; Figure 3 is the schematic diagram of the operating parameters of the arc suppression coil provided by the embodiment of the present invention; Figure 4 is the schematic diagram of the line selection parameter numbering provided by the embodiment of the present invention; Figure 5 is the schematic diagram of using an error table for the voltage transformer and current transformer provided by the embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0019] Exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. Although the exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided so that the present disclosure can be more thoroughly understood and the scope of the present disclosure can be completely conveyed to those skilled in the art. It should be noted that, without conflict, the embodiments in the present invention and the features in the embodiments can be combined with each other. The present invention will be described in detail below with reference to the drawings and in conjunction with the embodiments.

[0020] Refer to Figure 1 , which is a structural block diagram of a current grounding line selection debugging system provided by an embodiment of the present invention. As shown in the figure, the system includes: an arc suppression coil control panel 1, a first voltage transformer 2, a second voltage transformer 3, a on-load arc suppression coil 4, a damping resistor 5, a current transformer 6, a lightning arrester 7, a grounding transformer 8, a circuit breaker 9, a one-way circuit breaker 10, a shunt intermediate resistor 11, and a thyristor 12. The arc suppression coil control panel 1 is respectively connected to the first voltage transformer 2, the current transformer 6, the on-load arc suppression coil 4, the damping resistor 5, and the current transformer 6. The arc suppression coil control panel 1 and the first voltage transformer 2 are connected to the bus. The current transformer 6, the damping resistor 5, the on-load arc suppression coil 4, the grounding transformer 8, and the circuit breaker 9 are connected in series and connected to the bus. A lightning arrester 7 is also connected to this series circuit. One side of the second voltage transformer 3 is connected to the arc suppression coil control panel 1, and the other side is connected to the one-way circuit breaker 10 and the shunt intermediate resistor 11 and grounded.

[0021] Refer to Figure 2 , which is a flow block diagram of a current grounding line selection debugging method provided by an embodiment of the present invention. As shown in the figure, the current grounding line selection debugging method includes the following steps: A routine inspection step S1, where each component is subjected to a routine inspection.

[0022] Specifically, a general inspection can be carried out, which specifically includes: (1) Check whether the product specifications, models, technical parameters, etc. are consistent with the design according to the nameplate; (2) Whether all fasteners are tightened and whether the insulating parts are in good condition; (3) Whether there is rust or damage to the metal parts and whether there is multi-point grounding of the iron core; (4) Check whether the winding of the dry-type grounding transformer is in good condition, whether there is deformation, displacement, damage, and whether there are sundries inside; the surface should be smooth and without cracks; (5) Connect the shell of the grounding transformer to the grounding main line; (6) Check the mechanical connection reliability of the multi-step tap of the on-load adjustable turn arc suppression coil; (7) Check the connection reliability between the neutral end and the grounding main line.

[0023] The transformer debugging step S2 is to debug the insulation, DC resistance and AC withstand voltage of the grounding transformer, and judge the debugging results in the debugging process to determine whether the selected grounding transformer meets the preset transformer selection criteria.

[0024] Specifically, insulation commissioning of the grounding transformer includes: 1) Check the meter first, turn on the switch, the pointer should be "∞" in the open circuit state, and "0" in the short circuit state. Connect the ground terminal "E" to the ground, and the high voltage output terminal "L" to the object under test for measurement. After the measurement, disconnect the object under test first, and then turn off the test meter. After the test, fully discharge the object under test; 2) Use a 2500V insulation resistance tester to measure the insulation resistance between the high-voltage side winding of the grounding transformer and the ground; 3) Use a 500V insulation resistance tester to measure the low-voltage side winding, core and clamps of the grounding transformer to ground.

[0025] Conduct DC resistance debugging on the winding of the grounding transformer, including: Check the instrument connection lines. When wiring, the voltage terminal is close to the winding, and the current terminal is outside the voltage terminal. Check the stability of the instrument power supply to ensure accurate detection of the instrument and reliable grounding of the instrument.

[0026] Perform AC withstand voltage commissioning on the grounding transformer, including: For the external construction frequency withstand voltage test, the repetitive test voltage is 80% of the factory test voltage, which can be seen in the product test report; First, perform an empty boost to the test equipment to check whether it can reach the test voltage value, then adjust the overvoltage protection value of the test equipment and check the reliability of the protection action; Short-circuit the phases of the grounding transformer to the high-voltage output terminal of the AC withstand voltage device; the secondary side and the shell are reliably grounded; Turn on the power supply of the AC withstand voltage device, increase the voltage to 28kV test voltage, and maintain it for 1 minute; then return the voltage to zero, turn off the power supply of the AC withstand voltage device; remove the test equipment and short-circuit wire.

[0027] During the voltage withstand test, the voltage must be increased from zero and impact closing is not allowed.

[0028] The preset transformer selection criteria specifically include, that is, the grounding transformer debugging result determination: The coil insulation resistance test value of high voltage-low voltage and ground is greater than or equal to 5000MΩ, and the low voltage-high voltage and ground is greater than or equal to 0.4MΩ; The core insulation resistance test value of the core-clamp and ground is greater than or equal to 2MΩ, and the through screw-ground and core is greater than or equal to 2MΩ; For the grounding transformer winding, the measured data conforms to the variation law of DC resistance at each gear position; During the withstand voltage test, there are no visible abnormal phenomena such as discharge, breakdown, smoking, abnormal sounds, etc.; after the withstand voltage test, the insulation resistance is greater than or equal to the insulation resistance before the withstand voltage test.

[0029] At the same time, the insulation resistance test of the winding and the iron core is generally carried out at a temperature of 20~30°C and a humidity of less than or equal to 80%; similarly, in a relatively humid environment, this value will decrease, and as long as its resistance value ≥ 0.1 MΩ, it can operate; generally, it can reach the requirements through drying treatment.

[0030] For the arc suppression coil commissioning step S3, conduct insulation, DC resistance, and AC withstand voltage commissioning on the on-load arc suppression coil, and determine the commissioning results during the commissioning process to determine whether the selected grounding transformer meets the preset arc suppression coil selection criteria.

[0031] Specifically, for the insulation commissioning of the on-load arc suppression coil, the insulation commissioning of the grounding transformer can be referred to; for the DC resistance commissioning of the on-load arc suppression coil, the DC resistance commissioning of the grounding transformer can be referred to; for the AC withstand voltage commissioning of the on-load arc suppression coil, the AC withstand voltage commissioning of the grounding transformer can be referred to. Among them, the preset arc suppression coil selection criteria include, that is, the arc suppression coil commissioning judgment criteria: The insulation resistance value of the high voltage - auxiliary and ground resistance value is greater than or equal to 1600 MΩ; The iron core - to - ground resistance value is greater than or equal to 2 MΩ; The measured data conforms to the variation law of DC resistance at each gear position, and the data from gear 1 to gear 9 gradually decreases; the measured data of gear 9 has a jump in gear and does not follow the resistance variation law, and it is determined that the on-load tap changer wiring is incorrect; The variation law of the measured value is consistent with the factory value; the response change compared with the factory value at the same temperature is less than or equal to 2%; The measured data conforms to the variation law of DC resistance at each gear position; During the withstand voltage test, there are no visible abnormal phenomena such as discharge, breakdown, smoking, abnormal sounds, etc.; after the withstand voltage test, the insulation resistance is greater than or equal to the insulation resistance before the withstand voltage test.

[0032] For the instrument transformer commissioning step S4, conduct insulation, DC resistance, turns ratio, polarity / excitation characteristics, and AC withstand voltage commissioning on the neutral point instrument transformer, and determine the commissioning results during the commissioning process to determine whether the selected grounding transformer meets the preset instrument transformer selection criteria.

[0033] Specifically, for the insulation and DC resistance commissioning of the neutral point instrument transformer, the insulation and DC resistance commissioning of the grounding transformer can be referred to in sequence, and the turns ratio, polarity / excitation characteristics test of the neutral point instrument transformer is carried out, specifically including: 1) Conduct the transformation ratio test of the voltage transformer. The two interfaces A-X of the instrument respectively correspond to the head and tail terminals A-X of the primary side of the transformer; the two interfaces a-x of the instrument respectively correspond to the head and tail terminals a-x of the secondary side of the transformer; select the voltage (PT) transformer menu on the human-machine interface of the instrument, and turn on the "power" switch to conduct the test.

[0034] 2) Conduct the transformation ratio test of the current transformer. The two interfaces P1-P2 of the instrument respectively correspond to the head and tail terminals P1-P2 of the primary side of the transformer; the two interfaces S1-S2 of the instrument respectively correspond to the head and tail terminals S1-S2 of the secondary side of the transformer; select the current (CT) transformer menu on the human-machine interface of the instrument, and turn on the "power" switch to conduct the test.

[0035] 3) Conduct the excitation characteristic test of the transformer. The two interfaces K1-K2 of the instrument respectively correspond to the coil S1-S2 or a-x terminals of the secondary side of the transformer; select the excitation characteristic menu of the transformer on the human-machine interface of the instrument, and turn on the "power" switch to conduct the test.

[0036] 4) For the AC withstand voltage test, refer to the AC withstand voltage commissioning of the grounding transformer.

[0037] Among them, the preset criteria for transformer selection include, that is, the commissioning result determination of the neutral point transformer: 1) For the neutral point voltage transformer, the measured value of the DC resistance of the primary winding is compared with the factory value converted to the same temperature, and the difference should not be greater than 10%; the measured value of the DC resistance of the secondary winding is compared with the factory value converted to the same temperature, and the difference should not be greater than 15%. 2) For the neutral point current transformer, the difference between the DC resistance of the windings of the current transformers of the same model, same specification, and same batch and the average value should not be greater than 10%. 3) The same-name terminals of the transformer are based on the subtractive polarity. If the tested polarity is the + polarity, check whether the wiring of the primary and secondary sides of the transformer is correct and correct it at the test terminal. 4) The measurement points of the excitation curve include 20%, 50%, 80%, 100%, and 120% of the rated voltage. For the voltage transformer with the neutral point directly grounded, the highest measurement point should be 150%. 5) For the excitation characteristic of the current transformer, the changes of current and voltage follow a non-linear curve, tending to magnetic saturation, and draw the excitation characteristic curve to observe its inflection point and whether the curve is smooth, so as to judge whether the inside of the winding is normal. 6) The measured data conform to the change law of the DC resistance of each gear. 7) During the withstand voltage process, there are no visible abnormal phenomena such as discharge, breakdown, smoking, abnormal sounds, etc.; after the withstand voltage, the insulation resistance is greater than or equal to the insulation resistance before the withstand voltage.

[0038] For the circuit breaker commissioning step S5, perform insulation, loop resistance, and switch mechanical characteristic commissioning on the unidirectional circuit breaker, and determine the commissioning results during the commissioning process to determine whether the selected circuit breaker meets the preset circuit breaker selection criteria.

[0039] Specifically, for the insulation commissioning of the unidirectional circuit breaker, the insulation commissioning of the grounding transformer can be referred to. For the loop resistance commissioning of the unidirectional circuit breaker, it specifically includes: close the circuit breaker, connect the test leads to both sides of the moving contact and the static contact respectively, adjust the current of the contact resistance tester to 100 A, and read the resistance value, with the unit of ; The switch mechanical characteristic commissioning specifically includes: The two connecting test wires are the closing and opening coil signal wires respectively; Connect the closing and opening signals to both ends of the closing and opening coils correspondingly; Clip the lead-out wires of the contact signal socket to the upper port of the switch static contact and the upper and lower ports of the moving contact according to the color respectively; Close the power supply (AC220V), press the measurement button, measure the closing time and bounce, and display them on the display screen; Then measure the time in the opening state; For its AC withstand voltage commissioning, the insulation commissioning of the grounding transformer can be referred to. The single-phase to ground and circuit breaker contact test voltage is 30 kV.

[0040] The preset circuit breaker selection criteria include: The main contact opening distance is within the range of 5.0 - 5.5 mm; The contact closing bounce time ≤ 5 ms; The closing time ≤ 120 ms is judged as a qualified test; The loop resistance has no obvious difference compared with the product factory test value; Among them, no obvious difference means that the difference between the two is within a certain range, and the difference can be determined according to the actual situation; The measured data conforms to the DC resistance change law of each gear; During the withstand voltage process, there are no visible abnormal phenomena such as discharge, breakdown, smoking, abnormal sounds, etc.; After the withstand voltage, the insulation resistance is greater than or equal to the insulation resistance before the withstand voltage.

[0041] For the resistor commissioning step S6, measure the resistance values of the parallel resistor and the damping resistor, and determine them based on the resistance values to determine whether the selected resistor meets the preset resistor criteria.

[0042] Specifically, measure the resistance value. Use an LCR tester, adjust it to the resistance R mode, use the positive and negative test leads to test the two ends of the resistor respectively, and record the data. The measured resistance value should have no obvious difference from the factory value or the nameplate.

[0043] For the thyristor trigger commissioning step S7, commission the thyristor to obtain its trigger voltage and cut-off voltage to determine whether the thyristor meets the preset thyristor criteria.

[0044] Specifically, the debugging of the thyristor specifically includes: The 750 multi-functional tester selects the voltage output gear, and the voltage output ports are respectively connected to the control stage G and the cathode K of the thyristor; A voltmeter is connected in parallel on the output port to monitor the output voltage; Before the voltage output, use the ohm gear of the multimeter to test both ends of the damping resistor with the test leads, and the measured resistance value is the damping resistor value; When the voltage applied to the control stage G and the cathode K ports of the thyristor reaches 370V, use the ohm gear of the multimeter to test both ends of the damping resistor and there is no resistance value and it is in a conducting state, indicating that the thyristor is conducting at this time; After the thyristor conducts, the applied voltage slowly decreases. When it is 368V, use the ohm gear of the multimeter to test both ends of the damping resistor and there is a resistance value, indicating that the thyristor is cut off and in a blocking state, and the trigger voltage and cut-off voltage are obtained. The determination of whether the thyristor meets the preset thyristor criterion specifically includes: 1) A series resistor is connected to the thyristor trigger circuit to protect the trigger circuit and prevent voltage short-circuit; 2) Record the thyristor conduction voltage value; when the voltage decreases, the thyristor is immediately blocked and the voltage value is recorded. The applied trigger voltage and cut-off voltage should have no obvious difference from the voltage in the factory data.

[0045] The on-load tap-changer debugging step S8 is to debug the on-load tap-changer of the arc suppression coil to determine whether it meets the preset switch criterion.

[0046] Specifically, the debugging of the on-load tap-changer of the arc suppression coil specifically includes: (1) Use a 500V insulation resistance tester to test the insulation of the control and operating mechanism power supply and the secondary circuit. The test values should not be less than 1MΩ. In a relatively humid place, it should not be less than 0.5MΩ; (2) Check that the signal cable connection between the arc suppression coil automatic tap-changing device and the line selection control panel is reliable; the shielded wire is grounded regularly, and the device shell is firmly connected to the PE row; (3) Check the AC220V and DC220V power supply voltage lines, measure the voltage value, and check the DC voltage polarity; (4) Before the arc suppression coil automatic tap-changing equipment is powered on, manually test 7 gears continuously for 5 times; (5) After the DC power supply of the incoming line switch of the arc suppression coil control cabinet is energized, close the main switch. At this time, the cabinet power indicator light is always on; successively close the control power supply and the tap-changing motor power supply, and the arc suppression coil automatic tap-changing returns to the zero position; (6) Test the tap-changing device in the electric state. Each time the N+1 or N-1 button is pressed, the arc suppression coil gear automatically shifts up or down.

[0047] (7) Check the DI and DO signal status signals of the arc suppression coil gear action in the line selection control panel device; among them, determining whether the preset switch criteria are met specifically includes: 1) Use a multimeter to measure the working voltage of the control panel: AC 220V, allowable deviation -20%~ +15%, DC 220 / 100V±10%; 2) The tension of the arc suppression coil on-load adjustment device is constant during the gear adjustment process in manual and automatic states, and the switching is smooth, and there is no abnormal sound between the mechanical twisted parts; 3) DI and DO signal status signals, actions and feedback should be consistent.

[0048] The control panel line selection and debugging step S9 performs zero-sequence current sampling, bus voltage sampling, neutral point voltage and current sampling, control panel, and 10kV switch cabinet secondary circuit sampling at one time, and makes a judgment on the results to determine whether the preset line selection and debugging criteria are met.

[0049] Specifically, the test items required for the control panel line selection and debugging include: 1) parameter setting; 2) line number setting; 3) zero-sequence current sampling; 4) bus voltage adoption; 5) neutral point voltage and current sampling; 6) control panel and 10kV switch cabinet secondary circuit sampling. The test methods and result judgments specifically include: 1) After turning on the power switch of the line selection control panel, check the LCD display, control keys, printer, and communication interface connections one by one and test them; then set the parameters of the line selection device, save them, and restart the machine to continue testing; 2) Operation parameters can be found at Figure 3 Setting up 3) Line numbering: The numbering should follow the principle of one-to-one correspondence, that is, the line number and the line number correspond one-to-one. Empty line numbers can be reserved for spare system expansion, but the numbering cannot be repeated. Figure 4 Line selection parameter number is shown as follows; 4) Use the 750 multi-function tester to apply 5V and 10V voltages to the test terminals of the bus voltage transformer cabinet, and then check whether the sampled voltages are consistent on the control panel device; 5) The voltage transformer and current transformer at the neutral point are sampled and error detected, such as Figure 5 Sampling table. The sampling data of the neutral point voltage transformer and current transformer should be close to the factory value without major differences.

[0050] 6) Check the zero-sequence current wiring of the relay protection and the zero-sequence current wiring of the line selection control panel device on the switch cabinet test terminal to confirm that the two are connected in series; ensure that the wiring is not loose or weak, and there is no parallel wiring between the two; 7) The 750 multi-functional tester selects the 0 - 100V AC output terminal, and it is convenient to monitor the magnitude of the output voltage. The voltage output terminal is connected in parallel to the tester's detection voltmeter with a short wire; on the secondary side of the neutral point voltage transformer, 20V voltage is output to the control panel.

[0051] 8) The control panel collects the secondary circuit value of the zero-sequence current of the 10kV switch feeder cabinet; using the transformer tester, select the line numbered 1011. Inside the corresponding 10kV switchgear feeder cabinet, in accordance with the normal cable current direction, pass the red (+) cable clamp of the tester's current output through the zero-sequence current transformer and short it together with the black (-) cable clamp of the tester to form a current loop. 9) After checking that the instrument connections are correct, apply 25A and 50A "fault" currents respectively on the primary side of the zero-sequence current transformer. According to the zero-sequence current transformer ratio of 50 / 1, 0.5A and 1A currents are induced on the secondary side. 10) Check the neutral point voltage value collected by the control panel and the "fault" current value of the 10kV switch feeder cabinet corresponding to the selected line number respectively. 11) After the "fault" zero-sequence current of the 10kV switchgear is output, first check the zero-sequence current value on the switchgear's relay protection device to see if it is consistent with the applied current value. When the "fault" current is greater than the set parameter, the relay protection function is activated to issue an alarm or trip command. 12) Finally, view the fault line selection number in the "Function Selection" → "Grounding Information" of the selection control panel menu; if the fault line number is consistent with the control panel number, it indicates that the line selection and the selection number are correct; if the fault phase selection number does not match, it is necessary to check the control panel device number parameter and the zero-sequence current sampling secondary line from the switchgear to the control panel device; after finding the cause of the problem, repeat the above steps until the selection numbers of each outgoing line cabinet and the control panel correspond one by one. 13) After the selection control panel device collects the zero-sequence current, according to the following formula, assuming that ⅠC is the capacitance current of the 10kV system equal to 15A and the detuning degree ε is set to 1% - 12%, then calculate Ⅰ according to the maximum detuning degree L The inductive current of the arc suppression coil is 16.8A and the residual current is 1.8A; the on-load tap-changing type arc suppression coil starts the remote control of the arc suppression coil gear according to the system logic and implements the inductive current compensation action. ε ; Ⅰ & =Ⅰ L -Ⅰ C ; Among them, ε is the detuning degree, Ⅰ & is the residual current, ⅠL is the inductive current of the arc suppression coil, Ⅰ C is the capacitive current of the 10 kV system.

[0052] 14) The zero-sequence current line selection and regulation principle is that the control panel device uses the "detuning degree" and "residual current" as references, and whether to adjust the compensation current of the arc suppression coil as a judgment means. The device parameters set the detuning degree and zero-sequence residual current within a certain range. When the detuning degree or zero-sequence residual current of the system exceeds this range, the controller issues a command to adjust the tap position of the arc suppression coil to meet the requirements of the detuning degree and residual current after compensation.

[0053] In summary, the current grounding line selection debugging method provided in this embodiment decomposes, refines, and explains the voltage transformer, current transformer, grounding transformer, automatic tuning arc suppression coil, selection device, and zero-sequence transformer in the system equipment one by one, and uses debugging methods such as inspection and test to illustrate their uses and the relationships between them; it completely reflects the debugging method of the small current grounding line selection equipment and device in the 10 kV substation system, as well as the systematic debugging, simulates and solves the problems of misselection and omission of small current grounding line selection, and avoids the problem of the circuit breaker tripping of the switch cabinet caused by the large current flowing through the fault point, the difficult extinguishment of the arc, and the overvoltage after single-phase grounding due to the increase of the capacitance current to the ground caused by the large number of outgoing cables in the 10 kV substation. Thereby reducing the accident tripping rate of the substation line, reducing personal injuries and equipment damage, and improving the safe operation and power supply reliability of the substation system. This method also has the following effects: 1. Increase the power supply reliability of urban power supply and distribution; 2. Prevent the further expansion of power outage accidents; 3. Be able to adapt to complex environments; 4. Increase the automatic power supply restoration function of small current grounding line selection; 5. Reduce manual intervention in the whole system.

[0054] 6. The debugging of the small current grounding line selection system is convenient, the method is simple, and the practicability is strong.

[0055] It should be noted that in the description of the present invention, the terms indicating the direction or position relationship such as "upper", "lower", "left", "right", "inner", "outer", etc. are based on the direction or position relationship shown in the drawings. This is only for convenience of description, rather than indicating or implying that the device or element must have a specific orientation, be constructed and operated in a specific orientation, so it should not be construed as a limitation of the present invention.

[0056] In addition, it should be noted that in the description of the present invention, unless otherwise clearly specified and defined, the terms "installed", "connected", and "coupled" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be directly connected, or indirectly connected through an intermediate medium, and it can be the communication inside two components. For those skilled in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0057] Obviously, those skilled in the art can make various modifications and variations to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalent technologies, the present invention also intends to include these modifications and variations.

Claims

1. A current grounding line selection and debugging method, characterized in that: Use current grounding line selection and debugging system to carry out line selection and debugging; The current grounding line selection and debugging system includes: an arc suppression coil control panel, a first voltage transformer, a second voltage transformer, an on-load arc suppression coil, a damping resistor, a current transformer, a grounding transformer, a circuit breaker, a one-way circuit breaker, a parallel resistor and a thyristor; wherein, the arc suppression coil control panel is respectively connected to the first voltage transformer, the current transformer, the on-load arc suppression coil, the damping resistor and the current transformer, the arc suppression coil control panel and the first voltage transformer are connected to the bus, the current transformer, the damping resistor, the on-load arc suppression coil, the grounding transformer and the circuit breaker are connected in series and connected to the bus, and a lightning arrester is also connected to the series line; one side of the second voltage transformer is connected to the arc suppression coil control panel, and the other side is connected to the one-way circuit breaker and the parallel resistor, and is grounded; The current grounding line selection debugging method comprises the following steps: The transformer debugging step is to debug the insulation, DC resistance and AC withstand voltage of the grounding transformer, and judge the debugging results in the debugging process to determine whether the selected grounding transformer meets the preset transformer selection criteria; Arc suppression coil debugging steps: conduct insulation, DC resistance, and AC withstand voltage debugging on the loaded arc suppression coil, and judge the debugging results during the debugging process to determine whether the selected grounding transformer meets the preset arc suppression coil selection criteria; The transformer debugging step is to debug the insulation, DC resistance, ratio, polarity / excitation characteristics, and AC withstand voltage of the neutral point transformer, and judge the debugging results during the debugging process to determine whether the selected grounding transformer meets the preset transformer selection criteria; The circuit breaker debugging step is to debug the insulation, loop resistance and switch mechanical characteristics of the one-way circuit breaker, and judge the debugging results during the debugging process to determine whether the selected circuit breaker meets the preset circuit breaker selection criteria; The resistor debugging step is to measure the resistance value of the parallel resistor and the damping resistor, and judge them based on the resistance value to determine whether the selected resistor meets the preset resistance criterion; The thyristor triggering debugging step is to debug the thyristor and obtain its triggering voltage and cut-off voltage to determine whether the thyristor meets the preset thyristor criterion; On-load switch debugging steps: debug the on-load switch of the arc suppression coil to determine whether the preset switch criteria are met; The control panel line selection and debugging steps include performing zero-sequence current sampling, bus voltage sampling, neutral point voltage and current sampling, control panel, and 10kV switch cabinet secondary circuit sampling at one time, and judging the results to determine whether the preset line selection and debugging criteria are met.

2. The current grounding line selection and debugging method according to claim 1 is characterized in that: Conduct insulation commissioning on grounding transformer, on-load arc suppression coil, neutral point transformer and one-way circuit breaker, including: First check the meter, turn on the switch, the pointer should be "∞" in the open circuit state, and "0" in the short circuit state; connect the ground terminal "E" to the ground, and connect the high voltage output terminal "L" to the object under test for measurement. After the measurement is completed, disconnect the object under test and turn off the test instrument. After the test, fully discharge the object under test; Use a 2500V insulation resistance tester to measure the high voltage side winding of the grounding transformer to ground; Use a 500V insulation resistance tester to measure the insulation resistance between the low-voltage winding, core and clamps of the grounding transformer and the ground.

3. The current grounding line selection and debugging method according to claim 1 or 2, characterized in that: Conduct DC resistance debugging on the windings, on-load arc suppression coils, and neutral point transformers of the grounding transformer, including: Check the instrument connection lines. When wiring, the voltage terminal is close to the winding, and the current terminal is outside the voltage terminal. Check the stability of the instrument power supply to ensure accurate detection of the instrument and reliable grounding of the instrument.

4. The current grounding line selection and debugging method according to claim 1 or 2, characterized in that: Conduct AC withstand voltage commissioning on grounding transformer, on-load arc suppression coil and neutral point transformer, including: For external construction frequency withstand voltage test, the repetitive test voltage is 80% of the factory test voltage; Perform an empty boost to check whether the test equipment can reach the test voltage value, then adjust the overvoltage protection value of the test equipment and check the reliability of the protection action; Short-circuit the phases of the grounding transformer to the high-voltage output terminal of the AC withstand voltage device; the secondary side and the shell are reliably grounded; Turn on the power supply of the AC withstand voltage device, increase the voltage to 28kV test voltage, and maintain it for 1 minute; then return the voltage to zero, turn off the power supply of the AC withstand voltage device; remove the test equipment and short-circuit wire.

5. The current grounding line selection and debugging method according to claim 1 or 2, characterized in that: The preset transformer selection criteria include: The coil insulation resistance test value of high voltage-low voltage and ground is greater than or equal to 5000MΩ, and the low voltage-high voltage and ground is greater than or equal to 0.4MΩ; The core insulation resistance test value of the core-clamp and ground is greater than or equal to 2MΩ, and the through screw-ground and core is greater than or equal to 2MΩ; The measured data of the grounding transformer winding conforms to the variation law of DC resistance at each gear; During the voltage withstand process, there is no visible abnormal phenomenon such as discharge, breakdown, smoke, abnormal sound, etc.; the insulation resistance after voltage withstand is greater than or equal to the insulation resistance before voltage withstand.

6. The current grounding line selection and debugging method according to claim 1 or 2, characterized in that: The preset arc suppression coil selection criteria include: Insulation resistance value high voltage-auxiliary and ground resistance value is greater than or equal to 1600MΩ; The core-to-ground resistance is greater than or equal to 2MΩ; The measured data conforms to the variation law of DC resistance in each gear, and the data of gears 1-9 gradually decreases; the measured data of gear 9 has a jump and does not follow the variation law of resistance, which indicates that the wiring of the on-load tap changer is wrong; The measured value and the factory value have the same change pattern; the response change compared with the factory value at the same temperature is less than or equal to 2%; The measured data conforms to the variation law of DC resistance in each gear; During the withstand voltage process, there is no visible abnormal phenomenon; the insulation resistance after withstand voltage is greater than or equal to the insulation resistance before withstand voltage.

7. The current grounding line selection and debugging method according to claim 1 or 2, characterized in that: The circuit resistance debugging of the one-way circuit breaker specifically includes: closing the circuit breaker, connecting the test wires to both sides of the moving contact and the static contact, adjusting the current of the contact resistance tester to 100A, and reading the resistance value in units of ; The switch mechanical characteristic debugging method specifically includes: The two connection test wires are the closing and opening coil signal wires respectively; connect the closing and opening signals to the two ends of the closing and opening coils respectively; Clamp the lead wires of the contact signal socket to the upper port of the static contact and the upper and lower ports of the moving contact of the switch according to their colors; Turn on the power, press the measurement button, measure the closing time and bounce, and display them on the display; then measure the time in the opening state; The AC withstand voltage is debugged and the single-phase to ground and circuit breaker test voltage is 30kV.

8. The current grounding line selection and debugging method according to claim 1 or 2, characterized in that: The preset circuit breaker selection criteria include: The main contact opening distance is within the range of 5.0-5.5mm; the contact closing bounce time is ≤5ms; the closing time is ≤120ms to determine the test is qualified; There is no significant difference between the loop resistance and the product's factory test value; The measured data conforms to the variation law of DC resistance in each gear; During the voltage withstand process, there is no visible abnormal phenomenon such as discharge, breakdown, smoke, abnormal sound, etc.; the insulation resistance after voltage withstand is greater than or equal to the insulation resistance before voltage withstand.

9. The current grounding line selection and debugging method according to claim 1 or 2, characterized in that: The debugging of the thyristor specifically includes: The 750 multi-function tester selects the voltage output gear, and the voltage output port is connected to the thyristor control level G and cathode K respectively; Connect a voltmeter in parallel to the output port to monitor the output voltage; Before the voltage is output, use the multimeter's ohmmeter probe to test both ends of the damping resistor respectively. The measured resistance is the damping resistor value. When the voltage applied to the thyristor control stage G and cathode K ports reaches 370V, use the multimeter ohmmeter probe to test that there is no resistance at both ends of the damping resistor, indicating that the thyristor is turned on. After the thyristor is turned on, the applied voltage decreases slowly. When it is 368V, the resistance at both ends of the damping resistor is tested with the ohmmeter probe of the multimeter and it is in a blocked state. The trigger voltage and cut-off voltage are obtained.

10. The current grounding line selection and debugging method according to claim 1 or 2, characterized in that: The on-load switch debugging steps specifically include: The 500V insulation resistance tester tests the control and operating mechanism power supply and secondary circuit for insulation testing. The test values ​​are all greater than 1MΩ. In a relatively humid place, the values ​​are greater than 0.5MΩ. Check that the wiring of the arc suppression coil automatic gear adjustment device and the signal cable of the line selection control panel is reliable; the shielding wire is grounded in accordance with the regulations, and the connection between the device housing and the PE row is tight and reliable; Check the AC220V and DC220V power supply voltage circuits, measure the voltage value, and check the DC voltage polarity; Before the arc suppression coil automatic gear adjustment device is powered on, the 7 gears are tested manually for 5 consecutive times; After the DC power supply of the incoming switch of the arc suppression coil control cabinet is energized, close the main switch, and the power indicator light on the cabinet door will be on; turn on the control power supply and the gear adjustment motor power supply in turn, and the arc suppression coil will automatically adjust and return to zero position; Test the gear shifting device in the electric state. Each time the N+1 or N-1 button is pressed, the arc extinguishing coil gear position automatically shifts up or down. Check the DI and DO signal status signals of the arc suppression coil gear action in the line selection control panel device; The preset switch criteria include: Use a multimeter to measure the working voltage of the control panel. The allowable deviation of AC 220V is -20%~ +15%, and the allowable deviation of DC voltage is ±10%; The tension of the arc suppression coil on-load adjustment device is constant in the manual and automatic gear adjustment process, and the switching is smooth, and there is no abnormal sound between the mechanical twisted parts; DI and DO signal status signals, actions and feedback are consistent.

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