Setting method of power supply system anti-bypass tripping protection

Abstract

This invention discloses a method for setting up protection against cascading tripping in a power supply system, comprising: S1: acquiring protection tripping fault information from the microprocessor-based protection devices of each level of switchgear; S2: converting the secondary operating current values ​​of each level of microprocessor-based protection devices to primary short-circuit current values, comparing and analyzing them, and preliminarily determining the location of the short-circuit fault point in the field equipment based on the primary short-circuit current value; S3: checking the protection settings of each microprocessor-based protection device, the short-circuit fault situation of the field equipment, and the configuration of the power supply and distribution lines; S4: analyzing the causes of cascading tripping faults; S5: changing the 0s instantaneous overcurrent protection of the busbar feeder switchgear in the primary switchgear room and the busbar incoming power switchgear in the secondary switchgear room to 0.2s, and simultaneously checking and verifying the current value and time limit of the backup overcurrent protection on the low-voltage side of the transformer. This invention's method for setting up protection against cascading tripping in a power supply system ensures the reliability and accuracy of power supply system protection and effectively prevents cascading tripping accidents.

Description

Technical Field

[0001] This invention belongs to the field of power supply system technology, and in particular relates to a method for setting up anti-over-level tripping protection for power supply systems. Background Technology

[0002] A substation is a power facility in a power system that transforms voltage, receives and distributes electrical energy, controls the flow of power, and adjusts voltage. It provides the required voltage levels to user equipment through transformers and high-voltage switchgear. The busbar of the high-voltage switchgear room (referred to as the primary switchgear room), which supplies power to user-side distribution transformers, motors, fans, and other power equipment loads through various feeder switchgear lines, is located on the low-voltage side of the transformer. Some production units, due to space constraints and a large number of equipment, often construct secondary high-voltage switchgear rooms (referred to as secondary switchgear rooms) in other areas to rationally allocate power and meet the configuration needs of the construction site or building interior. A feeder line (usually a power cable line) from the primary switchgear room busbar serves as the incoming power supply line for the secondary switchgear room, and the secondary switchgear room busbar typically has multiple feeder lines. In actual field operation, there have been multiple instances where a phase-to-phase short circuit fault occurred in a feeder switchgear on the busbar of the secondary switch room, causing the circuit breaker of that switchgear to trip. Simultaneously, this caused the circuit breakers of the incoming power supply switchgear of the secondary switch room and the circuit breakers of the feeder switchgear of the primary switchgear supplying power to the secondary switch room to trip, resulting in large-scale power outages, causing many pieces of equipment to shut down, and significantly impacting production stability. Summary of the Invention

[0003] To at least partially solve the technical problems existing in the prior art, the present invention provides a method for setting up anti-overcurrent tripping protection in a power supply system, comprising: S1: Obtain protection tripping fault information from the microcomputer protection devices of each level of switchgear; S2: Based on the fault information, the secondary operating current values ​​of each level of microprocessor protection device are converted to the primary short-circuit current values, and comparative analysis is performed. Based on the primary short-circuit current values, the location of the short-circuit fault point of the field equipment is preliminarily determined. S3: Based on the location of the equipment short circuit fault point, check the protection settings of each microprocessor protection device at the location of the equipment short circuit fault point, and at the same time check the short circuit fault situation of the equipment on site and the configuration of the power supply and distribution lines. S4: Based on the protection settings of each microcomputer protection device, the short circuit fault conditions of the equipment, and the configuration of the power supply and distribution lines, analyze the causes of protection tripping faults and determine the causes of protection tripping faults. S5: Based on the cause of the over-trip fault, change the 0s of the instantaneous overcurrent protection of the bus feeder switchgear in the primary switch room and the bus incoming power switchgear in the secondary switch room to 0.2s. At the same time, check and verify the current value and time limit of the backup overcurrent protection on the low-voltage side of the transformer. Confirm that the primary current value of the backup overcurrent protection on the low-voltage side of the transformer is greater than the sum of the primary current value set by the instantaneous overcurrent protection of the bus feeder switchgear in the primary switch room and the total load current value of the bus in the primary switch room. Also, the time limit of the backup overcurrent protection on the low-voltage side of the transformer must be greater than the time limit of the instantaneous overcurrent protection of the bus feeder switchgear in the primary switch room by 0.2s.

[0004] Furthermore, in the above-mentioned method for setting up over-level trip protection for power supply systems, the fault information obtained in step S1 includes the fault action type, secondary action current value, and current ratio.

[0005] Furthermore, in the above-mentioned method for setting up over-level trip protection in the power supply system, in step S2, the comparison and analysis method for each level of microprocessor protection device is as follows: the primary short-circuit current value of the microprocessor protection device of the feeder switch cabinet of the primary switch room bus is slightly higher than the primary short-circuit current value of the microprocessor protection device of the incoming power switch cabinet of the secondary switch room, and the two are close to the same in value; the primary short-circuit current value of the microprocessor protection device of the feeder switch cabinet of the secondary switch room bus is much smaller than the above two values.

[0006] Furthermore, in the above-mentioned method for setting up over-level trip protection for the power supply system, in step S3, the protection settings of the microcomputer protection devices of each switchgear are checked as follows: the secondary switchgear bus feeder switchgear adopts three-stage protection, namely, instantaneous trip protection without time limit, instantaneous trip protection with time limit, and overcurrent protection; the secondary switchgear bus incoming switchgear and the primary switchgear bus feeder switchgear both adopt two-stage protection, namely, instantaneous trip protection without time limit and overcurrent protection. The short circuit fault in the equipment on site was as follows: a two-phase short circuit in the stator winding of the high-voltage motor; The power supply and distribution line configuration is as follows: the distance from the short circuit fault point to the bus feeder switch cabinet of the secondary switch room and the incoming power switch cabinet of the secondary switch room is relatively short, with a cable line length of 250 meters; the distance from the incoming power switch cabinet of the secondary switch room to the bus feeder switch cabinet of the primary switch room is relatively short, with a cable line length of 300 meters.

[0007] Furthermore, in the above-mentioned method for setting up over-level trip protection in the power supply system, in step S4, the reason for the over-level trip fault is: the bus feeder switch cabinet of the first-level switch room, the bus incoming power switch cabinet of the second-level switch room, and the bus feeder switch cabinet of the second-level switch room are all set to 0s instantaneous overcurrent protection without time limit, and the relevant switch cabinets are close to each other. When a two-phase or three-phase short circuit fault occurs in the field load equipment or line, the protection of the short circuit current is not selective, which easily leads to two-level over-level trip power loss accident.

[0008] Furthermore, in the above-mentioned method for setting the protection against overcurrent tripping in the power supply system, in step S5, according to the principle of matching protection time limits between upper and lower level power grids, the protection time limit for the transformer low backup overcurrent protection is set to 0.5s.

[0009] The setting method for power supply system anti-over-trip protection of the present invention has the following advantages and beneficial effects: The present invention provides a method for setting up over-level trip protection for power supply systems. It analyzes the causes of over-level trip faults in power supply systems, ensures the reliability and accuracy of power supply system protection, and effectively prevents over-level trip accidents from occurring. 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: Figure 1 Mileage diagram for the setting method of the power supply system anti-over-level tripping protection 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] The method for setting up power supply system anti-over-level tripping protection according to the present invention includes: S1: Obtain protection tripping fault information of microcomputer protection devices at all levels of switchgear. The obtained fault information includes fault action type, secondary action current value and current ratio. S2: Based on the fault information, the secondary operating current values ​​of each level of microprocessor protection device are converted to the primary short-circuit current values ​​for comparison and analysis. Based on the primary short-circuit current values, the location of the short-circuit fault point in the field equipment is preliminarily determined. The comparison and analysis method for each level of microprocessor protection device is as follows: the primary short-circuit current value of the microprocessor protection device of the feeder switch cabinet of the primary switch room bus is slightly higher than that of the microprocessor protection device of the incoming power switch cabinet of the secondary switch room, and the two are close to the same in value; the primary short-circuit current value of the microprocessor protection device of the feeder switch cabinet of the secondary switch room bus is much smaller than the above two values. It should be noted that the primary short-circuit current value of the microprocessor protection device of the bus feeder switchgear in the secondary switch room is much smaller than that of the microprocessor protection device of the bus feeder switchgear in the primary switch room and the incoming power switchgear in the secondary switch room. This is because when a short-circuit fault occurs, a large short-circuit current value is generated instantaneously. Since the current transformer ratio of the current transformer in the bus feeder switchgear of the secondary switch room is small (configured according to the load capacity), the current transformer will undergo magnetic saturation at the moment of short circuit, exhibiting a nonlinear relationship and failing to accurately reflect the primary side short-circuit current value. S3: Based on the location of the equipment short-circuit fault point, check the protection settings of each microprocessor protection device at the equipment short-circuit fault point location. At the same time, check the short-circuit fault situation of the equipment on site and the configuration of the power supply and distribution lines. Check the protection settings of the microprocessor protection devices of each switch cabinet as follows: the secondary switch room bus feeder switch cabinet adopts three-stage protection, namely, instantaneous overcurrent protection without time limit, time-limited instantaneous overcurrent protection, and overcurrent protection. The secondary switch room bus incoming switch cabinet and the primary switch room bus feeder switch cabinet both adopt two-stage protection, namely, instantaneous overcurrent protection without time limit and overcurrent protection. Check and confirm that the current setting values ​​of each level of protection are properly matched, and confirm that the bus feeder switchgear of the first-level switch room and the bus incoming switchgear of the second-level switch room are both set to instantaneous overcurrent protection without time limit. The short circuit fault in the equipment on site was as follows: a two-phase short circuit in the stator winding of the high-voltage motor; The power supply and distribution line configuration is as follows: the distance from the short circuit fault point to the bus feeder switch cabinet of the secondary switch room and the incoming power switch cabinet of the secondary switch room is relatively short, with a cable line length of 250 meters; the distance from the incoming power switch cabinet of the secondary switch room to the bus feeder switch cabinet of the primary switch room is relatively short, with a cable line length of 300 meters. S4: Based on the protection settings of each microcomputer protection device, the short-circuit fault conditions of the equipment, and the configuration of the power supply and distribution lines, the cause of the protection tripping over-level fault is analyzed, and the cause of the protection tripping over-level fault is found to be: the bus feeder switch cabinet of the first-level switch room, the bus incoming power switch cabinet of the second-level switch room, and the bus feeder switch cabinet of the second-level switch room are all set to 0s unlimited instantaneous overcurrent protection, and the relevant switch cabinets are close to each other. When a two-phase or three-phase short-circuit fault occurs in the load equipment or line on site, the protection of the short-circuit current is not selective, which easily leads to two-level over-level tripping and power loss accidents. S5: Based on the cause of the over-trip fault, change the 0s of the instantaneous overcurrent protection of the bus feeder switchgear in the primary switch room and the bus incoming power switchgear in the secondary switch room to 0.2s. At the same time, check and verify the current value and time limit of the backup overcurrent protection on the low-voltage side of the transformer. Confirm that the primary current value of the backup overcurrent protection on the low-voltage side of the transformer is greater than the sum of the primary current value set by the instantaneous overcurrent protection of the bus feeder switchgear in the primary switch room and the total load current value of the bus in the primary switch room. Also, the time limit of the backup overcurrent protection on the low-voltage side of the transformer must be greater than the time limit of the instantaneous overcurrent protection of the bus feeder switchgear in the primary switch room by 0.2s.

[0013] Furthermore, in the setting method of the power supply system anti-overcurrent tripping protection of the present invention, in step S5, according to the principle of matching protection time limits between upper and lower level power grids, the transformer low backup overcurrent protection time limit is set to 0.5s. In summary, compared with the prior art, the setting method for power supply system anti-over-level tripping protection of the present invention has the following advantages and beneficial effects: The setting method for power supply system anti-over-level tripping protection of the present invention analyzes the causes of over-level tripping faults in the power supply system, ensures the reliability and accuracy of power supply system protection, and effectively prevents the occurrence of over-level tripping accidents.

[0014] 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.

[0015] 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 method for setting up anti-overcurrent tripping protection in a power supply system, characterized in that, The method for setting the power supply system's anti-over-level tripping protection includes: S1: Obtain protection tripping fault information from the microcomputer protection devices of each level of switchgear; S2: Based on the fault information, the secondary operating current values ​​of each level of microprocessor protection device are converted to the primary short-circuit current values, and comparative analysis is performed. Based on the primary short-circuit current values, the location of the short-circuit fault point of the field equipment is preliminarily determined. S3: Based on the location of the equipment short circuit fault point, check the protection settings of each microprocessor protection device at the location of the equipment short circuit fault point, and at the same time check the short circuit fault situation of the equipment on site and the configuration of the power supply and distribution lines. S4: Based on the protection settings of each microcomputer protection device, the short circuit fault conditions of the equipment, and the configuration of the power supply and distribution lines, analyze the causes of protection tripping faults and determine the causes of protection tripping faults. S5: Based on the cause of the over-trip fault, change the 0s of the instantaneous overcurrent protection of the bus feeder switchgear in the primary switch room and the bus incoming power switchgear in the secondary switch room to 0.2s. At the same time, check and verify the current value and time limit of the backup overcurrent protection on the low-voltage side of the transformer. Confirm that the primary current value of the backup overcurrent protection on the low-voltage side of the transformer is greater than the sum of the primary current value set by the instantaneous overcurrent protection of the bus feeder switchgear in the primary switch room and the total load current value of the bus in the primary switch room. Also, the time limit of the backup overcurrent protection on the low-voltage side of the transformer must be greater than the time limit of the instantaneous overcurrent protection of the bus feeder switchgear in the primary switch room by 0.2s.

2. The method for setting up anti-over-level tripping protection in a power supply system according to claim 1, characterized in that, In step S1, the fault information obtained includes the fault action type, secondary action current value, and current ratio.

3. The method for setting up anti-over-level tripping protection in a power supply system according to claim 1, characterized in that, In step S2, the comparative analysis method for each level of microprocessor protection device is as follows: the primary short-circuit current value of the microprocessor protection device of the feeder switch cabinet of the primary switch room bus is slightly higher than that of the microprocessor protection device of the incoming power switch cabinet of the secondary switch room, and the two are close to the same in value; the primary short-circuit current value of the microprocessor protection device of the feeder switch cabinet of the secondary switch room bus is much smaller than the above two values.

4. The method for setting up anti-over-level tripping protection in a power supply system according to claim 1, characterized in that, In step S3, the protection settings of the microcomputer protection devices of each switchgear are checked as follows: the secondary switchgear bus feeder switchgear adopts three-stage protection, namely instantaneous overcurrent protection, time-limited instantaneous overcurrent protection, and overcurrent protection; the secondary switchgear bus incoming switchgear and the primary switchgear bus feeder switchgear adopt two-stage protection, namely instantaneous overcurrent protection and overcurrent protection. The short circuit fault in the equipment on site was as follows: a two-phase short circuit in the stator winding of the high-voltage motor; The power supply and distribution line configuration is as follows: the distance from the short circuit fault point to the bus feeder switch cabinet of the secondary switch room and the incoming power switch cabinet of the secondary switch room is relatively short, with a cable line length of 250 meters; the distance from the incoming power switch cabinet of the secondary switch room to the bus feeder switch cabinet of the primary switch room is relatively short, with a cable line length of 300 meters.

5. The method for setting up anti-over-level tripping protection in a power supply system according to claim 1, characterized in that, In step S4, the reason for the protection tripping fault is that the bus feeder switch cabinets of the first-level switch room, the bus incoming power switch cabinets of the second-level switch room, and the bus feeder switch cabinets of the second-level switch room are all set to 0s instantaneous overcurrent protection, and the relevant switch cabinets are close to each other. When a two-phase or three-phase short circuit fault occurs in the field load equipment or line, the short circuit current protection is not selective, which easily leads to a two-level tripping power loss accident.

6. The method for setting up anti-over-level tripping protection in a power supply system according to claim 1, characterized in that, In step S5, based on the principle of matching protection time limits between upper and lower level power grids, the low backup overcurrent protection time limit of the transformer is set to 0.5s.

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