Voltage transformer loop disconnection fault processing method

Abstract

The invention discloses a voltage transformer loop disconnection fault processing method, which comprises the steps of judging whether a voltage transformer loop is disconnected or not, acquiring voltage transformer disconnection fault alarm information, and checking according to PT disconnection alarm information on a feed-out wire switch cabinet microcomputer protection measurement and control device. According to the method, the property of a broken line fault is quickly judged and corresponding maintenance is made by checking the alarm of a protection device of a certain feed line cabinet or all feed line cabinets of a bus and testing the voltage of two sides of a PT secondary side fuse according to the insulation check action alarm information of the bus of the transformer. According to the voltage transformer loop disconnection fault processing method, the fault property can be judged in time, a basis can be provided for analysis and processing of various faults of disconnection of the voltage transformer, the disconnection faults of the voltage transformer can be quickly found, the disconnection fault processing efficiency of the voltage transformer is effectively improved, and the stability of a power supply system is ensured.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of voltage transformer fault processing, and particularly relates to a voltage transformer loop breakage fault processing method. BACKGROUND

[0002] Voltage transformer (also known as PT) breakage refers to any type of loop breakage fault in the three-phase voltage loop of the primary side (high voltage) or secondary side (low voltage) of the voltage transformer. It is a relatively common fault in power systems. According to voltage level, voltage transformer breakage can be divided into primary side breakage and secondary side breakage of the voltage transformer; according to voltage phase, voltage transformer breakage can be divided into single-phase breakage, two-phase breakage and three-phase breakage (also known as three-phase voltage loss). Once the voltage transformer breaks down and loses voltage, it will affect the normal operation of the relay protection, electric energy metering and voltage measurement equipment of the electrical equipment, and if the breakage is caused by secondary side short circuit, the short circuit current generated thereby may burn out the voltage transformer, thereby affecting the safe operation of the primary power supply equipment. SUMMARY

[0003] To at least partially solve the technical problems existing in the prior art, the present application provides a voltage transformer loop breakage fault processing method.

[0004] The voltage transformer loop breakage fault processing method of the present application comprises: S1: determining whether the voltage transformer loop is broken and obtaining voltage transformer breakage fault alarm information; S2: first check the alarm information on the microcomputer protection measurement and control device of the high voltage feeder line switch cabinet, if only the "PT breakage" alarm information is sent from the microcomputer protection measurement and control device of the high voltage feeder line switch cabinet of the bus, the fault point is in the secondary loop of the voltage transformer of the high voltage feeder line cabinet, check whether the connection of the voltage transformer secondary conductor from the top voltage small bus to the feeder line cabinet and to the microcomputer protection measurement and control device voltage loop is poor or loose, and restore normal after processing; S3: if the microcomputer protection measurement and control device of each feeder line switch cabinet on the bus sends voltage transformer breakage alarm information, the fault point is the primary side fuse body of the voltage transformer or the secondary side fuse body and its secondary loop fault; S4: check whether the microcomputer protection measurement and control device of the transformer supplying the bus has bus insulation check action alarm information, if not, first check whether the secondary fuse body of the voltage transformer is fused, test the three-phase voltage on both sides of the secondary fuse with the AC voltage range of the multimeter, if the test voltage values are inconsistent, it is confirmed that the secondary fuse body is fused, and the fuse can be replaced after the cause is investigated; S5: If the busbar insulation check operation alarm is reported, it is confirmed that the fuse of the primary side of the voltage transformer is blown, and the three-phase voltage is tested on the power supply and load sides of the secondary fuse of the voltage transformer using the AC voltage range of the multimeter. If the values are basically the same, it is further confirmed, and it is determined whether it is a one-phase or two-phase fuse blown fault according to the test values; S6: A primary side fuse of the same type of voltage transformer is prepared, and the resistance test is normal; S7: The transformer high backup overcurrent protection trip plunger is disconnected on the transformer microcomputer protection measurement and control screen. S8: The secondary side fuse of the voltage transformer is disconnected, the voltage transformer isolation knife switch is pulled out, safety measures such as checking the voltage and hanging the ground wire are taken, the fault phase fuse of the primary side of the voltage transformer is replaced, the safety measures are removed, the voltage transformer isolation knife switch is closed, the power supply is restored, the secondary side fuse of the voltage transformer is closed, and the voltage transformer is tested to be normal. The transformer high backup overcurrent protection trip plunger is closed. The voltage transformer works normally.

[0005] Further, in the above voltage transformer loop open circuit fault processing method, in the S1 step, the voltage transformer loop open circuit determination basis is: First, the three-phase phase voltage is less than 8V, the self-produced 3U0 is less than 8V, the secondary protection current is greater than the no-flow threshold value, and it is determined that the voltage transformer three-phase voltage loss occurs; Second, the minimum line voltage is less than 16V, and the self-produced 3U0 is greater than or equal to 8V, which is determined as voltage transformer two-phase open circuit; Third, the difference between the maximum line voltage and the minimum line voltage is greater than 16V, and the self-produced 3U0 is greater than or equal to 8V, which is determined as voltage transformer single-phase open circuit; Any one of the above three conditions lasts for more than 9s, which is determined as voltage transformer loop open circuit.

[0006] Further, in the above voltage transformer loop open circuit fault processing method, in the S1 step, the voltage transformer open circuit fault alarm information obtained is: voltage transformer three-phase voltage loss, voltage transformer two-phase open circuit, or voltage transformer single-phase open circuit.

[0007] Further, in the above voltage transformer loop open circuit fault processing method, the zero sequence voltage 3U0 is self-produced by the microcomputer protection measurement and control device; The secondary protection current is the secondary protection current collected by the microcomputer protection measurement and control device of the feeder outgoing line switch cabinet; The no-flow threshold value is by default Wherein, In is the secondary protection rated current collected by the microcomputer protection device of the feeder outgoing line switch cabinet, which is 5A.

[0008] Furthermore, in the above-mentioned method for handling voltage transformer circuit disconnection faults, in step S8, if the voltage transformer primary side fuse blows, it may be due to a small animal entering the PT cabinet, water entering, or a fault in the PT itself. Under this fault, the bus incoming circuit breaker will generally trip and lose power simultaneously. If the PT itself is damaged, disconnect the high-voltage side isolating switch and the low-voltage side circuit breaker of the PT cabinet. If the two bus PTs in the station are equipped with voltage parallel switching devices, the secondary voltage of the PTs can be connected in parallel. After the power supply to the bus system is restored, the PTs that are working normally on the other bus will provide secondary protection, measurement, and metering voltage to the switchgear equipment of each feeder on the bus where the faulty PT is located.

[0009] The voltage transformer circuit open circuit fault handling method of the present invention has the following advantages and beneficial effects: The voltage transformer circuit open circuit fault handling method of the present invention can promptly determine the nature of the fault, provide a basis for the analysis and handling of various voltage transformer open circuit faults, realize the rapid location of voltage transformer open circuit faults, effectively improve the efficiency of voltage transformer open circuit fault location and handling, and ensure the stability of the power supply system. Attached Figure Description

[0010] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only for further understanding of the embodiments of the present invention and constitute a part of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. In the drawings: Fig. 1 This is the logic diagram for determining whether the voltage transformer circuit is disconnected according to the present invention; Fig. 2 This is a flowchart of the voltage transformer circuit open circuit fault handling method of the present invention. Detailed Implementation

[0011] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below in conjunction with specific embodiments and corresponding drawings. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0012] To provide protection, metering, and measurement functions for the high-voltage busbar equipment, a set of voltage transformers is installed on each busbar section. The secondary side of the voltage transformer is connected via control cables to the small voltage busbar at the top of the busbar switchgear. From there, the cables connect to the terminal blocks inside the control cabinet doors of each feeder switchgear, and finally to the secondary voltage terminals of the microprocessor-based protection and control device. Furthermore, fuses are installed on the primary side of the voltage transformer to provide short-circuit protection for the transformer itself and the main line, while fuses or automatic air switches are installed on the secondary side to provide short-circuit protection for the secondary circuit. When a voltage transformer disconnects, a potential difference appears between the neutral point on the secondary side and ground. This potential difference activates a voltage relay, thus determining that the voltage transformer is disconnected and triggering the connected alarm circuit. The alarm circuit is powered by a DC power supply, ensuring stable and reliable operation.

[0013] like Figs. 1-2 As shown, the voltage transformer circuit open circuit fault handling method of the present invention includes: S1: Determine whether the voltage transformer circuit is open and obtain voltage transformer open circuit fault alarm information; Specifically, the determination of whether the voltage transformer circuit is open is based on the following criteria: First, if all three phase voltages are less than 8V, and the self-generated 3U0 is less than 8V, and the secondary protection current is greater than the no-current threshold, it is determined that the voltage transformer is undervoltage in three phases. Second, if the minimum line voltage is less than 16V, and the self-generated 3U0 is greater than or equal to 8V, it is determined that the voltage transformer is open in two phases. Third, if the difference between the maximum and minimum line voltages is greater than 16V, and the self-generated 3U0 is greater than or equal to 8V, it is determined that the voltage transformer is open in one phase. If any of the above three conditions lasts for more than 9 seconds, it is determined that the voltage transformer circuit is open, thereby driving the voltage transformer alarm signal contact to close, illuminating the alarm light on the panel of the microcomputer protection and control device, and both the microcomputer protection and control device and the background monitoring microcomputer issue a voltage transformer circuit open message and alarm flashing information, thereby providing fault information to the maintenance personnel. S2: First, check the alarm information on the microcomputer protection and control device of the high-voltage feeder switchgear. If only the microcomputer protection and control device of a certain high-voltage feeder switchgear of the busbar issues a "PT disconnection" alarm, the fault point is the secondary circuit of the voltage transformer of the high-voltage feeder switchgear. Check whether there is poor contact or looseness in the wiring of the voltage small busbar from the top of the cabinet to the secondary conductor of the voltage transformer of the feeder switchgear, and the wiring to the voltage circuit of the microcomputer protection and control device. After handling, the system will be restored to normal. S3: If the microcomputer protection and control device of each feeder switch cabinet on the busbar reports a voltage transformer disconnection alarm, the fault point is either the primary fuse of the voltage transformer blown or the secondary fuse blown and its secondary circuit fault. S4: Check if the microcomputer protection and control device of the transformer supplying power to the busbar has a busbar insulation check alarm message. If not, first check if the secondary fuse of the voltage transformer is blown. Use a multimeter in AC voltage mode to test the three-phase voltage on both sides of the secondary fuse. If the test voltage values ​​are inconsistent, it is confirmed that the secondary fuse is blown. After troubleshooting, replace the fuse. S5: If a bus insulation check alarm is triggered, it is confirmed that the primary fuse of the voltage transformer has blown. Use a multimeter in AC voltage mode to perform three-phase voltage tests on the power supply side and load side of the secondary fuse of the voltage transformer. If the values ​​are basically consistent, it is further confirmed. Based on the test values, it can be determined whether it is one or two phases of the fuse that has blown. S6: Prepare a primary-side fuse of the same model of voltage transformer; the resistance test is normal. S7: Disconnect the transformer high backup overcurrent protection trip plate on the transformer microcomputer protection and control panel; S8: Disconnect the secondary fuse of the voltage transformer, open the isolating switch of the voltage transformer, perform safety measures such as voltage testing and grounding, replace the faulty phase fuse on the primary side of the voltage transformer, remove the safety measures, close the isolating switch of the voltage transformer, restore power, close the secondary fuse of the voltage transformer, check that the voltage transformer indicator is working normally, and close the high-voltage backup overcurrent protection trip plate of the transformer.

[0014] Furthermore, in the voltage transformer circuit open circuit fault handling method of the present invention, in step S1, the obtained voltage transformer open circuit fault alarm information is: three-phase voltage loss of voltage transformer, two-phase open circuit of voltage transformer, or single-phase open circuit of voltage transformer.

[0015] Furthermore, in the voltage transformer circuit open circuit fault handling method of the present invention, the zero-sequence voltage 3U0 is generated by the microcomputer protection and control device. The secondary protection current is the secondary protection current collected by the microcomputer protection and control device of this feeder switchgear; The no-flow threshold value is set to the default value. Where In is the rated secondary protection current collected by the microcomputer protection device of this feeder switchgear, which is 5A.

[0016] Furthermore, in the above-mentioned method for handling voltage transformer circuit disconnection faults, in step S8, if the voltage transformer primary side fuse blows, it may be due to a small animal entering the PT cabinet, water entering, or a fault in the PT itself. Under this fault, the bus incoming circuit breaker will generally trip and lose power simultaneously. If the PT itself is damaged, disconnect the high-voltage side isolating switch and the low-voltage side circuit breaker of the PT cabinet. If the two bus PTs in the station are equipped with voltage parallel switching devices, the secondary voltage of the PTs can be connected in parallel. After the power supply to the bus system is restored, the PTs that are working normally on the other bus will provide secondary protection, measurement, and metering voltage to the switchgear equipment of each feeder on the bus where the faulty PT is located.

[0017] In summary, compared with the prior art, the voltage transformer circuit open circuit fault handling method of the present invention has the following advantages and beneficial effects: The voltage transformer circuit open circuit fault handling method of the present invention can promptly determine the nature of the fault, provide a basis for the analysis and handling of various voltage transformer open circuit faults, realize the rapid location of voltage transformer open circuit faults, effectively improve the efficiency of voltage transformer open circuit fault handling, and ensure the stability of the power supply system.

[0018] It should be noted that, unless otherwise expressly specified and limited, the term "connection" or its synonyms should be interpreted broadly in this document. For example, "connection" can be a fixed connection or a detachable connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium; it can be the internal communication of two elements or the interaction between two elements. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances. Furthermore, expressions such as "first" and "second" are merely used to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Meanwhile, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. In addition, the terms "front," "rear," "left," "right," "upper," and "lower" in this document refer to the placement states shown in the accompanying drawings.

[0019] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A voltage transformer loop disconnection fault handling method, characterized by, The voltage transformer loop disconnection fault processing method comprises: S1: determining whether the voltage transformer loop is disconnected, and obtaining voltage transformer disconnection fault alarm information; S2: first check the alarm information on the microcomputer protection measurement and control device of the high-voltage outgoing line switch cabinet, if only the "PT disconnection" alarm information is sent on the microcomputer protection measurement and control device of the high-voltage outgoing line switch cabinet of the bus, the fault point is in the secondary loop of the voltage transformer of the high-voltage outgoing line cabinet, check whether the connection of the secondary lead of the voltage transformer of the outgoing line cabinet and the voltage loop of the microcomputer protection measurement and control device is poor or loose, and restore normal after processing; S3: if the microcomputer protection measurement and control devices of the outgoing line switch cabinets on the bus all report voltage transformer disconnection alarm information, the fault point is the primary side fuse body of the voltage transformer or the secondary side fuse body of the voltage transformer and its secondary loop fault; S4: check whether the microcomputer protection measurement and control device of the transformer supplying the bus has bus insulation check action alarm information, if not, first check whether the secondary fuse body of the voltage transformer is fused, test the three-phase voltage on both sides of the secondary fuse with the AC voltage range of the multimeter, if the test voltage values are inconsistent, it is confirmed that the secondary fuse body is fused fault, and the fuse body is replaced after troubleshooting; S5: if there is bus insulation check action alarm, it is confirmed that the primary side fuse body of the voltage transformer is fused fault, test the three-phase voltage on both sides of the secondary fuse of the voltage transformer with the AC voltage range of the multimeter, the values are basically consistent, then it is further confirmed, and it is determined whether it is one-phase or two-phase fuse body fused fault according to the test values; S6: prepare the same type of primary side fuse of the voltage transformer, and the resistance test is normal; S7: disconnect the high backup overcurrent protection trip platen of the transformer on the microcomputer protection measurement and control screen; S8: disconnect the secondary side fuse of the voltage transformer, pull out the isolation knife switch of the voltage transformer, take safety measures such as checking the voltage and hanging the ground wire, replace the fault phase fuse of the primary side of the voltage transformer, remove the safety measures, close the isolation knife switch of the voltage transformer, restore power supply, close the secondary side fuse of the voltage transformer, and check that the voltage transformer is working normally, close the high backup overcurrent protection trip platen of the transformer, and the voltage transformer is working normally.

2. The voltage transformer loop open fault handling method of claim 1, wherein, In the S1 step, the determination basis of whether the voltage transformer loop is disconnected is: First, the three-phase phase voltage is less than 8V, the self-produced 3U0 is less than 8V, and the secondary protection current is greater than the no-flow threshold value, which is determined as voltage transformer three-phase voltage loss; Second, the minimum line voltage is less than 16V, and the self-produced 3U0 is greater than or equal to 8V, which is determined as voltage transformer two-phase disconnection; Third, the difference between the maximum line voltage and the minimum line voltage is greater than 16V, and the self-produced 3U0 is greater than or equal to 8V, which is determined as voltage transformer single-phase disconnection; Any one of the above three conditions for more than 9s is determined as voltage transformer loop disconnection.

3. The voltage transformer loop open fault handling method of claim 2, wherein, In the S1 step, the obtained voltage transformer disconnection fault alarm information is: voltage transformer three-phase voltage loss, voltage transformer two-phase disconnection or voltage transformer single-phase disconnection.

4. The voltage transformer loop open fault handling method of claim 2, wherein, The zero sequence voltage 3U0 is generated by the microcomputer protection and control device; The secondary protection current is the secondary protection current collected by the microcomputer protection and control device of the feeder switch cabinet; The no-flow threshold value is the default In is the rated current of the secondary protection collected by the microcomputer protection device of the feeder outgoing line switchgear, and is 5 A.

5. The voltage transformer loop open fault handling method of claim 1, wherein, In the S8 step, if the primary side fuse of the voltage transformer is fused, it is possible that the PT cabinet enters small animals or is flooded, or the PT body is faulty, and the bus feeder circuit breaker will generally trip off power at the same time. If the PT body is damaged, the high-voltage side disconnector of the PT cabinet and the low-voltage side circuit breaker are disconnected, and the two-section bus PT is provided with a voltage parallel switching device, which can be put into the PT secondary voltage parallel. After the bus system is restored to power, the normal PT of the other section of bus provides secondary protection, measurement and metering voltage for each feeder switch cabinet of the bus where the faulty PT is located.

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