CN112366664A - Method and system for improving relay protection based on 3/2 wiring mode - Google Patents
Method and system for improving relay protection based on 3/2 wiring mode Download PDFInfo
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- CN112366664A CN112366664A CN202011117626.2A CN202011117626A CN112366664A CN 112366664 A CN112366664 A CN 112366664A CN 202011117626 A CN202011117626 A CN 202011117626A CN 112366664 A CN112366664 A CN 112366664A
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H7/00—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions
- H02H7/26—Sectionalised protection of cable or line systems, e.g. for disconnecting a section on which a short-circuit, earth fault, or arc discharge has occured
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H7/00—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions
- H02H7/22—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions for distribution gear, e.g. bus-bar systems; for switching devices
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y04—INFORMATION OR COMMUNICATION TECHNOLOGIES HAVING AN IMPACT ON OTHER TECHNOLOGY AREAS
- Y04S—SYSTEMS INTEGRATING TECHNOLOGIES RELATED TO POWER NETWORK OPERATION, COMMUNICATION OR INFORMATION TECHNOLOGIES FOR IMPROVING THE ELECTRICAL POWER GENERATION, TRANSMISSION, DISTRIBUTION, MANAGEMENT OR USAGE, i.e. SMART GRIDS
- Y04S10/00—Systems supporting electrical power generation, transmission or distribution
- Y04S10/50—Systems or methods supporting the power network operation or management, involving a certain degree of interaction with the load-side end user applications
- Y04S10/52—Outage or fault management, e.g. fault detection or location
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Abstract
The invention discloses a method and a system for improving relay protection based on 3/2 wiring mode, wherein the method comprises the following steps: after a fault is detected in the differential protection range of the circuit breaker, the circuit breaker performs small-difference protection action, and simultaneously sends a locking signal to line protection and bus protection; after the breaker is disconnected, judging a fault area according to current information on two sides of the disconnected breaker, acquiring a judgment result, and determining a fault position in a small differential protection range; and sending the judgment result to the line protection or the bus protection corresponding to the fault position in the small differential protection range, sending a locking releasing signal to the line protection or the bus protection corresponding to the fault position, and carrying out corresponding line protection action or bus differential protection action.
Description
Technical Field
The invention relates to the technical field of power systems and automatic relay protection thereof, in particular to a method and a system for improving relay protection based on 3/2 wiring mode.
Background
At present, 3/2 circuit breaker wiring modes are widely adopted for main wiring in 500kV transformer substations in China, and the main wiring modes are high in power supply reliability, strong in operation flexibility and convenient to operate and overhaul. When the current transformer is arranged on one side of the circuit breaker in the wiring mode, the protection range with the circuit breaker as the boundary cannot be completely overlapped with the KCL generalized node formed by the current transformer, namely, an area without main protection coverage exists, and the area is called as a protection dead area. When a protection dead zone fails, main protection cannot be removed instantaneously, breaker failure protection is required to be removed, according to the existing regulations, the failure action delay setting range is 200-250 ms, the failure removal time may exceed 400ms, when the dead zone failure occurs in the ultrahigh voltage direct current concentrated feed-in near zone, multiple direct currents are likely to have more than two continuous phase change failures, huge transient energy impact can cause serious influence on a transmitting end power grid and a receiving end power grid, and even grid collapse risk exists. When the current transformers are arranged on both sides of the circuit breaker, partial or all protection dead zones can be eliminated, but the problem of enlarged power failure range when faults are removed can be caused.
3/2 breaker wiring of a typical 3CT configuration is shown in FIG. 1, where the fault measurement ranges of bus differential protection and line protection are crossed but the ranges of both are not crossed, resulting in a dead zone of protection, the A, B, C region shown in the figure, i.e., the connection between the breaker and the set of current transformers, where no primary protection can be removed instantaneously in the event of a fault. Taking a fault of an area a in the figure as an example, when the area a has a fault, the area a is located in a bus differential protection range of an I bus, the bus differential protection of the I bus operates, circuit breakers QF 11-QF 1n trip, but the fault is not completely removed at this time, the area a belongs to an out-of-area fault for an outgoing line L1, the line protection of an L1 does not operate, and all devices on the L1, the L2 and a bus II continue to provide short-circuit current to a fault point at this time. After the QF11 failure protection action, the circuit breaker is instantly and repeatedly tripped, the QF21 circuit breaker is tripped after the delay, and the circuit breaker on the opposite side of the long-trip outlet L1 is tripped, so that the fault is removed. According to the prior art, the fault clearing time may exceed 400ms, and the required time is too long, which may cause serious threat to the power system.
Under the current configuration, the operating conditions of each breaker when each zone on the string has a fault are shown in table 1. The fourth column in the table indicates a circuit breaker that is not necessarily opened for clearing a current fault, among circuit breakers that are opened after the main protection and near backup protection (circuit breaker failure protection or dead zone protection) actions are completed.
Table 13 CT configuration for each breaker operating condition for each zone fault on the string
An 3/2 open circuit breaker wiring of a typical 4CT configuration is shown in fig. 2, where there are two areas of protection dead space a and D, which are in failure and which act in a manner similar to that of the 3CT configuration. Under the current configuration, the operating conditions of each breaker when each zone on the string has a fault are shown in table 2.
Table 24 CT arrangement of breaker operating conditions of faults in each area of the string
If two groups of CTs are directly added on the basis of 3/2 wiring typical string 3CT protection configuration to form 5CT protection configuration as shown in fig. 3, a protection dead zone E still exists under the configuration condition, when a fault occurs in the zone, the outgoing line L2 performs protection action, the circuit breakers QF21 and QF31 trip and simultaneously jump far from the circuit breaker on the opposite side of L2, but the fault is not completely removed at this time, and at this time, all devices on the L1 and I bus continue to provide short-circuit current to the fault point. And (3) QF21 failure protection action, after time delay, the breaker is instantly and repeatedly tripped, the QF11 breaker is tripped, and the breaker on the opposite side of the outgoing line L1 is tripped, so that the fault is removed. In the current configuration, the operation of each breaker when each area fails is shown in table 3.
Table 35 CT arrangement for each breaker operating condition of each zone fault on the string
With two additional sets of CTs on top of the 4CT configuration, or with a tank circuit breaker, the 3/2 wiring is typically strung in a 6CT protection configuration, as shown in fig. 4. In this configuration, there is no protection dead zone, but there is a problem that the fault removing range is enlarged, and the operation of each breaker at the time of the fault of each zone in the figure is shown in table 4.
Table 46 CT arrangement for each breaker operating condition for each zone fault on the string
When 3/2 wiring adopts an open circuit breaker to match with a traditional electromagnetic current transformer, improper distribution of internal windings of the current transformer sometimes causes the problem of enlarging the power failure range during protection dead zone or fault removal. The internal outline of the U-shaped current transformer is shown in FIG. 5. The windings are connected to the circuit for double protection, and the winding is connected to the bus for protection. Under the condition of winding distribution, if the bottom of the transformer is subjected to flashover grounding at a point K due to rain, water accumulation and the like, the whole bus can be tripped off, and the fault power failure range is enlarged; in part of sites, in order to avoid jumping off the whole bus to expand the fault range when the bottom of the transformer is in fault, a winding II is connected into bus protection, and windings I and II are connected into line protection; when wiring in the field, the windings are sometimes wrongly distributed, so that a protection dead zone is caused.
Current transformers are arranged in two sides of the tank type circuit breaker, and are not matched with independent porcelain knob type current transformers, and the internal TA configuration brief structure of the tank type circuit breaker is shown in figure 6. When the tank type circuit breaker is adopted, the problems of protection dead zones and the like can occur when TA windings in the tank type circuit breaker are not distributed properly. In field application, TA3 and TA4 should be connected to the bus for double protection, and TA1 and TA2 should be connected to the line side for double protection, but in the field, TA distribution error causes fault conditions, namely double protection of TA1 and TA2 connected to the bus, and double protection of TA3 and TA4 connected to the line, so that the inside of the breaker, such as a point K, becomes a protection dead zone.
By synthesizing the situations of the above tables 1, 2, 3 and 4, the problems of the 3/2 configuration number of the connection current transformers, the expansion of the dead zone and the fault removal range are summarized in table 5, so that the increase of the configuration number of the current transformers can effectively reduce the protection dead zone, but the area of the power failure range expansion caused by fault removal is also increased; meanwhile, the problem of dead protection area caused by wrong distribution of the internal windings of the mutual inductor cannot be solved by the conventional main protection configuration.
TABLE 5 influence of TA configured quantities on Relay protection
| Number of TA configurations | Protecting the number of dead zones | Removing fault and power cut range expanded |
| Group | ||
| 3 | 3 | 3 |
| 4 groups of | 2 | 4 |
| 5 groups of | 1 | 5 |
| 6 groups of | 0 | 6 |
Therefore, a new protection coordination scheme under 3/2 wiring needs to be provided, which can reduce the power failure range when the main protection removes the fault while increasing the configuration number of the current transformers to eliminate the protection dead zone, and give consideration to the quick action and the selectivity of the relay protection.
Disclosure of Invention
The technical scheme of the invention provides a method and a system for improving relay protection based on 3/2 wiring mode, which are used for solving the problem of enlarged power failure range when a main protection action cuts off partial region faults on a string.
In order to solve the above problems, the present invention provides a method for improving relay protection based on 3/2 wiring method, the method includes:
after a fault is detected in the differential protection range of the circuit breaker, the circuit breaker performs small-difference protection action, and simultaneously sends a locking signal to line protection and bus protection;
after the breaker is disconnected, judging a fault area according to current information on two sides of the disconnected breaker, acquiring a judgment result, and determining a fault position in a small differential protection range;
and sending the judgment result to the line protection or the bus protection corresponding to the fault position in the small differential protection range, sending a locking releasing signal to the line protection or the bus protection corresponding to the fault position, and carrying out corresponding line protection action or bus differential protection action.
Preferably, the method further comprises the step of determining the fault occurrence area in the string:
when the bus differential protection acts and the line protection does not act after the breaker small differential protection acts, judging that a fault occurs in a superposed region of the breaker small differential protection and the bus differential protection;
and after the small-difference protection of the circuit breaker acts, when the line protection acts and the bus differential protection does not act, judging that the fault occurs in the superposed region of the small-difference protection and the line protection of the circuit breaker.
Preferably, the method comprises the following steps:
when the circuit breaker is an interrupt circuit breaker and the small-difference protection action signal of the medium circuit breaker is detected, a locking signal is sent to the line protection of the serial outgoing line;
and when the current value of the current transformer at one side of the middle breaker is greater than a preset setting value and the current value of the current transformer at the side of the middle breaker is greater than a preset multiple of the current value of the current transformer at the other side of the breaker, a locking releasing signal is sent to the line protection of the outgoing line corresponding to the side of the middle breaker.
Preferably, the method comprises the following steps:
when the circuit breaker is a side circuit breaker and a small-difference protection action signal of the side circuit breaker is detected, a locking signal is sent to the bus protection and the line protection of a bus corresponding to the side circuit breaker;
when the current transformer current of the side breaker near bus side is greater than a preset setting value and the current transformer current of the side breaker near bus side is greater than a preset multiple of the current transformer current of the side breaker near bus side, a unblocking signal is sent to the bus protection of the bus corresponding to the side breaker; or
And when the current of the current transformer at the side close to the line of the side circuit breaker is greater than a preset setting value and the current of the current transformer at the side close to the line of the side circuit breaker is greater than a preset multiple of the current transformer at the side close to the bus of the side circuit breaker, sending unlocking to the line protection of the side circuit breaker.
Preferably, the method further comprises the following steps: and sending the judgment result to line protection or bus protection in an input quantity form.
Based on another aspect of the present invention, the present invention provides a system for improving relay protection based on 3/2 wiring manner, the system comprising:
the detection unit is used for detecting that the breaker has small differential protection action after a fault occurs in the differential protection range of the breaker, and simultaneously sending a locking signal to line protection and bus protection;
the first judgment unit is used for judging a fault area according to current information on two sides of the disconnected circuit breaker after the circuit breaker is disconnected, acquiring a judgment result and determining a fault position in a small differential protection range;
and the execution unit is used for sending the judgment result to the line protection or the bus protection corresponding to the fault position in the small differential protection range, sending a locking releasing signal to the line protection or the bus protection corresponding to the fault position, and sending the corresponding line protection action or bus differential protection action.
Preferably, the system further comprises a second judging unit, configured to judge the intra-string fault occurrence area:
when the bus differential protection acts and the line protection does not act after the breaker small differential protection acts, judging that a fault occurs in a superposed region of the breaker small differential protection and the bus differential protection;
and after the small-difference protection of the circuit breaker acts, when the line protection acts and the bus differential protection does not act, judging that the fault occurs in the superposed region of the small-difference protection and the line protection of the circuit breaker.
Preferably, further for:
when the circuit breaker is an interrupt circuit breaker and the small-difference protection action signal of the medium circuit breaker is detected, a locking signal is sent to the line protection of the serial outgoing line;
and when the current value of the current transformer at one side of the middle breaker is greater than a preset setting value and the current value of the current transformer at the side of the middle breaker is greater than a preset multiple of the current value of the current transformer at the other side of the interrupt breaker, a unblocking signal is sent to the line protection of the line corresponding to the side of the middle breaker.
Preferably, further for:
when the circuit breaker is a side circuit breaker and a small-difference protection action signal of the side circuit breaker is detected, a locking signal is sent to the bus protection and the line protection of the side circuit breaker;
when the current transformer current of the side breaker near bus side is greater than a preset setting value and the current transformer current of the side breaker near bus side is greater than a preset multiple of the current transformer current of the side breaker near line protection side, a locking releasing signal is sent to the bus protection of the side breaker; or
And when the current transformer current at the side close to the line of the side circuit breaker is greater than a preset setting value and the current transformer current at the side close to the line of the side circuit breaker is greater than the current transformer current at the side close to the bus of the side circuit breaker by a preset multiple, the current transformer current is sent to the line protection corresponding to the side circuit breaker to remove the blocking.
Preferably, the execution unit is further configured to: and sending the judgment result to line protection or bus protection in an input quantity form.
The technical scheme of the invention provides a method and a system for improving relay protection based on 3/2 wiring mode, wherein the method comprises the following steps: after a fault is detected in the differential protection range of the circuit breaker, the circuit breaker performs small-difference protection action, and simultaneously sends a locking signal to line protection and bus protection; after the breaker is disconnected, judging a fault area according to current information on two sides of the disconnected breaker, acquiring a judgment result, and determining a fault position in a small differential protection range; and sending the judgment result to the line protection or the bus protection corresponding to the fault position in the small differential protection range, sending a locking releasing signal to the line protection or the bus protection corresponding to the fault position, and carrying out corresponding line protection action or bus differential protection action. According to the technical scheme, the current information on two sides of the single-string internal circuit breaker is matched with the line protection, and the current information on two sides of the station internal circuit breaker is matched with the bus protection, so that the accurate positioning of the fault in the string is realized, and the problem of enlarging the cutting range during the fault is solved.
Drawings
A more complete understanding of exemplary embodiments of the present invention may be had by reference to the following drawings in which:
FIG. 1 is a schematic diagram of an 3/2 wiring typical string 3CT protection configuration according to the prior art;
FIG. 2 is a schematic diagram of an 3/2 wiring typical string 4CT protection configuration according to the prior art;
FIG. 3 is a schematic diagram of an 3/2 wiring exemplary string 5CT protection configuration, according to the prior art;
FIG. 4 is a schematic diagram of an 3/2 wiring exemplary string 6CT protection configuration, according to the prior art;
FIG. 5 is a schematic diagram of an internal winding configuration of a U-shaped current transformer according to the prior art;
fig. 6 is a schematic diagram of a CT configuration of a tank circuit breaker according to the prior art;
fig. 7 is a schematic diagram of a substation protection configuration with added string breaker protection functionality according to a preferred embodiment of the present invention;
FIG. 8 is a logic diagram of an improved bus differential protection operation according to a preferred embodiment of the present invention;
FIG. 9 is a logic diagram of the improved line differential protection operation according to the preferred embodiment of the present invention;
fig. 10 is a logic diagram of a protection action after protection of a lead-in string circuit breaker according to a preferred embodiment of the present invention;
fig. 11 is a flow chart of a method for improving relay protection based on 3/2 wiring mode according to the preferred embodiment of the invention;
fig. 12 is a diagram illustrating a system for improving relay protection based on 3/2 connection according to a preferred embodiment of the present invention;
FIG. 13 is a timing diagram illustrating a protection operation according to a preferred embodiment of the present invention; and
FIG. 14 is a timing diagram of the protection operation according to the preferred embodiment of the present invention.
Detailed Description
The exemplary embodiments of the present invention will now be described with reference to the accompanying drawings, however, the present invention may be embodied in many different forms and is not limited to the embodiments described herein, which are provided for complete and complete disclosure of the present invention and to fully convey the scope of the present invention to those skilled in the art. The terminology used in the exemplary embodiments illustrated in the accompanying drawings is not intended to be limiting of the invention. In the drawings, the same units/elements are denoted by the same reference numerals.
Unless otherwise defined, terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Further, it will be understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and will not be interpreted in an idealized or overly formal sense.
Fig. 11 is a flow chart of a method for improving relay protection based on 3/2 wiring mode according to the preferred embodiment of the invention. Aiming at the problem that the power failure range is expanded when the main protection action cuts off the fault in the upper part of the string under the current transformer configuration of the 3/2 breaker wiring mode, the scheme of additionally arranging the string breaker protection is provided.
The invention provides a novel relay protection improvement method based on 3/2 wiring and added series circuit breaker protection, which specifically comprises the following steps:
according to the invention, the current information on two sides of the single-string internal circuit breaker is matched with the line protection, and the current information on two sides of the station internal circuit breaker is matched with the bus protection, so that the accurate positioning of the fault in the string is realized, and the problem of expanded cutting range during the fault is solved.
And constructing a series circuit breaker protection device, inputting current information on two sides of each circuit breaker in a single series into the series circuit breaker protection device, and forming differential protection. And the judgment result of the string breaker protection device is sent to the related line protection, transformer protection and bus protection of the string in the form of the input amount. The above-mentioned opening content is the logic signal for line protection, transformer protection and blocking of bus protection. The newly added circuit breaker differential protection adopts a half-wave Fourier algorithm, and a differential calculation result is obtained in a 10ms data window, so that the condition of circuit breaker differential protection can be obtained in advance when a cycle data window is used for bus protection and line protection. In order to reduce calculation errors, when the differential current on the two sides of the circuit breaker is calculated, the current sampling points on the two sides of the circuit breaker can be used for directly calculating the differential current sampling points, and then the amplitude of the differential current is obtained by utilizing a Fourier half-wave algorithm. An example of a typical string 6TA protection arrangement wired at 3/2 is shown in fig. 7 with the addition of a string breaker protection device.
The areas covered by a plurality of main protections under the original 3/2 wiring typical string, namely the areas which can cause the expansion of the power failure range of protection cutting after the fault occurs, are all in the small difference protection range of the newly added circuit breaker. When the area has a fault, the circuit breaker small differential protection operates preferentially, and simultaneously, a locking signal is sent to the line protection and the bus differential protection. After the circuit breaker is disconnected, the specific position of a fault is judged by combining current information on two sides of the circuit breaker, then a locking releasing signal is sent to corresponding protection, after corresponding protection action is completed, the circuit breaker is connected in series for protection, fault removal is judged successfully, and the locking releasing signal is sent to the protection locked before.
After the original 3/2 wiring protection configuration is improved by the above scheme, the bus differential protection action logic is shown in fig. 8, the line differential protection action logic is shown in fig. 9, and both the bus differential protection action logic and the line differential protection action logic add the blocking and opening signal of the series circuit breaker protection device on the basis of the original protection action logic: when the fault is not detected in the protection range of the series circuit breaker protection device, the blocking signal of the series circuit breaker protection device is kept open, and the action of original protection when other positions have faults is not influenced; when a fault occurs within the protection range of the string breaker protection device, the string breaker protection device sends out a blocking signal. The intra-station overall protection coordination logic is shown in fig. 9.
As shown in fig. 11, the present invention provides a method for improving relay protection based on 3/2 wiring method, the method includes:
step 101: and after a fault is detected in the differential protection range of the circuit breaker, the circuit breaker performs small-difference protection action, and simultaneously sends a locking signal to the line protection and the bus protection.
Step 102: and after the breaker is disconnected, judging the fault area according to the current information of two sides of the disconnected breaker, acquiring a judgment result and determining the fault position in the small differential protection range.
Step 103: and sending the judgment result to the line protection or the bus protection corresponding to the fault position in the small differential protection range, sending a locking releasing signal to the line protection or the bus protection corresponding to the fault position, and carrying out corresponding line protection action or bus differential protection action. Preferably, the method further comprises the following steps: and sending the judgment result to line protection or bus protection in the form of the input amount.
The invention provides a method for judging fault positions in a small difference range of a circuit breaker. Taking the fault occurring in the small difference protection range of the circuit breaker QF11 in fig. 7 as an example, after the fault occurrence is detected, the small difference protection of the QF11 circuit breaker acts, and the signaling blocking I bus protection and the L1 outgoing line protection are simultaneously performed, and after the QF11 circuit breaker is tripped, the fault region is judged according to the current information on the two sides of the circuit breaker: after the QF11 is tripped, if the formula (1) is satisfied, namely the breaker is disconnected, and a fault current flows through TA1, the fault of the B area can be judged, at the moment, the serial breaker protection sends a signal to the bus protection to release the locking, and the bus differential protection acts; if equation (1) is not satisfied but equation (2) is satisfied, that is, the circuit breaker is opened and a fault current flows through TA2, it can be determined that a C-zone fault occurs, and at this time, the series circuit breaker protection transmits a signal to the line protection circuit to release the lock, and the line protection circuit operates. If neither of the two formulas is satisfied, the circuit breaker is judged to be out of order.
(ITA1>Iset)&(ITA1>3*ITA2)＝1 (1)
(ITA2>Iset)&(ITA2>3*ITA1)＝1 (2)
In the two formulae IsetSetting values for avoiding the maximum load current and the unbalanced current and considering the margin; according to the existing research and related data of the prior art, due to the influence of the trailing current of the circuit breaker, the current value of the current transformer on one side of the circuit breaker after the circuit breaker is disconnected is 0.2 times of the fault current before the circuit breaker is disconnected, so that when the circuit breaker is judged to be disconnected, the judgment value is 3 times of the current value on one side of the circuit breaker to the current value on the other side of the circuit breaker, the circuit breaker is not influenced by the trailing current, the condition that the opening and closing state of the circuit breaker is judged through time delay is avoided, the judgment time of a fault area is shortened, and meanwhile, a.
Preferably, the method further comprises determining an in-string fault occurrence area:
when the bus differential protection acts and the line protection does not act after the breaker small differential protection acts, judging that a fault occurs in a superposed region of the breaker small differential protection and the bus differential protection;
and after the small-difference protection of the circuit breaker acts, when the line protection acts and the bus differential protection does not act, judging that the superposed region of the small-difference protection and the line protection of the circuit breaker breaks down.
After the relay protection coordination logic in the station is improved based on the above embodiment, the fault area in the string can be accurately positioned according to the protection action condition after the fault.
If the bus differential protection action is performed after the breaker small differential protection action is completed, and the line protection is not performed, the fault can be judged to occur in the superposed region of the breaker small differential protection and the bus differential protection; if the line protection is performed after the small difference protection operation of the circuit breaker is completed, and the bus differential protection is not performed, it can be determined that a fault occurs in the overlapping region of the small difference protection and the line protection of the circuit breaker.
Preferably, the method further comprises:
when the circuit breaker is a middle circuit breaker and a small-difference protection action signal of the middle circuit breaker is detected, a locking signal is sent to the line protection of the serial outgoing line;
and when the current value of the current transformer at one side of the middle breaker is greater than a preset setting value and the current value of the current transformer at the side of the middle breaker is greater than a preset multiple of the current value of the current transformer at the other side of the breaker, a unblocking signal is sent to the line protection of the outgoing line corresponding to the side of the middle breaker.
Preferably, the method further comprises:
when the circuit breaker is a side circuit breaker and a side circuit breaker small-difference protection action signal is detected, a locking signal is sent to the bus protection and the line protection of a bus corresponding to the side circuit breaker;
when the current transformer current of the side breaker near bus side is greater than a preset setting value and the current transformer current of the side breaker near bus side is greater than the current transformer current of the side breaker near bus side by a preset multiple, a unblocking signal is sent to the bus protection of the corresponding bus of the side breaker; or
And when the current of the current transformer at the side close to the line of the side circuit breaker is greater than a preset setting value and the current of the current transformer at the side close to the line of the side circuit breaker is greater than the current of the current transformer at the side close to the bus of the side circuit breaker by a preset multiple, the current transformer sends unlocking to the line protection of the side circuit breaker.
The invention can effectively solve the problem that the power failure range of protection action cutting is enlarged when a plurality of main protection coverage areas have faults under 3/2 breaker wiring, thereby improving the selectivity while ensuring the relay protection speed; the problem of the dead zone of protection that causes when the inside winding of mutual-inductor misdistributes is solved, improve the reliability of protection.
The invention mainly solves the problem that the power failure range is expanded when a plurality of main protection coverage areas are subjected to fault removal when a substation adopts 3/2 breaker wiring, and takes the case that part of the areas are subjected to fault during 3/2 wiring typical 6TA configuration as an example, namely when B, C area in fig. 7 is subjected to fault, the fault removal range under the original protection configuration is I bus and outlet L1. After the method is adopted for improvement, a specific fault area can be determined when a fault is removed, when the fault occurs in an area B, the protection removal range is only a bus I, and a protection action timing diagram is shown in FIG. 13; when it is determined that the C region has failed, the protection cutoff range is only the outgoing line L1, and the protection operation timing chart is shown in fig. 14. Meanwhile, as can be seen from the timing diagram, after the improvement of the scheme, the corresponding fault can be removed within 200 ms. The action conditions are similar when faults occur in the protection ranges of the other series breakers. The fault clearing non-essential circuit breakers listed in table 4 will not miscut after the protection configuration is modified by this scheme.
The invention can accurately judge the specific fault position in the string by utilizing the action condition of each protection in the fault while solving the problem of enlarged power failure range in the fault, thereby facilitating accident analysis and fault equipment maintenance. Taking 3/2 wiring exemplary string 6TA configuration as an example, the decision is shown in Table 6.
Table 6 increases the fault protection action condition of each area after the protection of the series circuit breaker
Fig. 12 is a block diagram of a system for improving relay protection based on 3/2 wiring method according to the preferred embodiment of the present invention. As shown in fig. 12, the present invention provides a system for improving relay protection based on 3/2 wiring method, the system includes:
the detection unit 1201 is configured to detect that a fault occurs within a differential protection range of the circuit breaker, and send a blocking signal to line protection and bus protection simultaneously.
The first judging unit 1202 is configured to, after the circuit breaker is disconnected, judge a fault region according to current information on two sides of the disconnected circuit breaker, obtain a judgment result, and determine a fault position within a small differential protection range.
And the executing unit 1203 is configured to send the determination result to the line protection or the bus protection corresponding to the fault location within the small differential protection range, send a unblocking signal to the line protection or the bus protection corresponding to the fault location, and send a corresponding line protection action or a corresponding bus differential protection action. Preferably, the execution unit is further configured to: and sending the judgment result to line protection or bus protection in the form of the input amount.
Preferably, the system further includes a second determination unit, configured to determine an intra-string fault occurrence region:
when the bus differential protection acts and the line protection does not act after the breaker small differential protection acts, judging that a fault occurs in a superposed region of the breaker small differential protection and the bus differential protection;
and after the small-difference protection of the circuit breaker acts, when the line protection acts and the bus differential protection does not act, judging that the superposed region of the small-difference protection and the line protection of the circuit breaker breaks down.
Preferably, the system is further adapted to:
when the circuit breaker is a middle circuit breaker and a small-difference protection action signal of the middle circuit breaker is detected, a locking signal is sent to the line protection of the serial outgoing line;
and when the current value of the current transformer at one side of the middle breaker is greater than a preset setting value and the current value of the current transformer at the side of the middle breaker is greater than a preset multiple of the current value of the current transformer at the other side of the interrupt circuit, a unblocking signal is sent to the line protection of the line corresponding to the side of the interrupt circuit.
Preferably, the system is further adapted to:
when the circuit breaker is a side circuit breaker and a side circuit breaker small-difference protection action signal is detected, a locking signal is sent to the bus protection and the line protection of the side circuit breaker;
when the current of a current transformer at the side of the breaker close to the bus is larger than a preset setting value and the current of the current transformer at the side of the breaker close to the bus is larger than a preset multiple of the current transformer at the side of the breaker close to the line protection, a locking releasing signal is sent to the bus protection of the side breaker; or
And when the current of the current transformer at the side close to the line of the side circuit breaker is greater than a preset setting value and the current of the current transformer at the side close to the line of the side circuit breaker is greater than the current of the current transformer at the side close to the bus of the side circuit breaker by a preset multiple, the current transformer sends unlocking to the line protection of the line corresponding to the side circuit breaker.
The system 1200 for improving relay protection based on the 3/2 wiring method in the preferred embodiment of the present invention corresponds to the method 1100 for improving relay protection based on the 3/2 wiring method in another preferred embodiment of the present invention, and is not described herein again.
The invention has been described with reference to a few embodiments. However, other embodiments of the invention than the one disclosed above are equally possible within the scope of the invention, as would be apparent to a person skilled in the art from the appended patent claims.
Generally, all terms used in the claims are to be interpreted according to their ordinary meaning in the technical field, unless explicitly defined otherwise herein. All references to "a/an/the [ device, component, etc ]" are to be interpreted openly as referring to at least one instance of said device, component, etc., unless explicitly stated otherwise. The steps of any method disclosed herein do not have to be performed in the exact order disclosed, unless explicitly stated.
Claims (10)
1. A method for improving relay protection based on 3/2 wiring mode, the method comprising:
after a fault is detected in the differential protection range of the circuit breaker, the circuit breaker performs small-difference protection action, and simultaneously sends a locking signal to line protection and bus protection;
after the breaker is disconnected, judging a fault area according to current information on two sides of the disconnected breaker, acquiring a judgment result, and determining a fault position in a small differential protection range;
and sending the judgment result to the line protection or the bus protection corresponding to the fault position in the small differential protection range, sending a locking releasing signal to the line protection or the bus protection corresponding to the fault position, and carrying out corresponding line protection action or bus differential protection action.
2. The method of claim 1, further comprising determining an intra-string fault occurrence area:
when the bus differential protection acts and the line protection does not act after the breaker small differential protection acts, judging that a fault occurs in a superposed region of the breaker small differential protection and the bus differential protection;
and after the small-difference protection of the circuit breaker acts, when the line protection acts and the bus differential protection does not act, judging that the fault occurs in the superposed region of the small-difference protection and the line protection of the circuit breaker.
3. The method of claim 1, comprising:
when the circuit breaker is an interrupt circuit breaker and the small-difference protection action signal of the medium circuit breaker is detected, a locking signal is sent to the line protection of the serial outgoing line;
and when the current value of the current transformer at one side of the middle breaker is greater than a preset setting value and the current value of the current transformer at the side of the middle breaker is greater than a preset multiple of the current value of the current transformer at the other side of the breaker, a locking releasing signal is sent to the line protection of the outgoing line corresponding to the side of the middle breaker.
4. The method of claim 1, comprising:
when the circuit breaker is a side circuit breaker and a small-difference protection action signal of the side circuit breaker is detected, a locking signal is sent to the bus protection and the line protection of a bus corresponding to the side circuit breaker;
when the current transformer current of the side breaker near bus side is greater than a preset setting value and the current transformer current of the side breaker near bus side is greater than a preset multiple of the current transformer current of the side breaker near bus side, a unblocking signal is sent to the bus protection of the bus corresponding to the side breaker; or
And when the current of the current transformer at the side close to the line of the side circuit breaker is greater than a preset setting value and the current of the current transformer at the side close to the line of the side circuit breaker is greater than a preset multiple of the current transformer at the side close to the bus of the side circuit breaker, sending unlocking to the line protection of the side circuit breaker.
5. The method of claim 1, further comprising: and sending the judgment result to line protection or bus protection in an input quantity form.
6. A system for improving relay protection based on 3/2 wiring, the system comprising:
the detection unit is used for detecting that the breaker has small differential protection action after a fault occurs in the differential protection range of the breaker, and simultaneously sending a locking signal to line protection and bus protection;
the first judgment unit is used for judging a fault area according to current information on two sides of the disconnected circuit breaker after the circuit breaker is disconnected, acquiring a judgment result and determining a fault position in a small differential protection range;
and the execution unit is used for sending the judgment result to the line protection or the bus protection corresponding to the fault position in the small differential protection range, sending a locking releasing signal to the line protection or the bus protection corresponding to the fault position, and sending the corresponding line protection action or bus differential protection action.
7. The system according to claim 6, further comprising a second determination unit configured to determine an in-string fault occurrence area:
when the bus differential protection acts and the line protection does not act after the breaker small differential protection acts, judging that a fault occurs in a superposed region of the breaker small differential protection and the bus differential protection;
and after the small-difference protection of the circuit breaker acts, when the line protection acts and the bus differential protection does not act, judging that the fault occurs in the superposed region of the small-difference protection and the line protection of the circuit breaker.
8. The system of claim 6, further to:
when the circuit breaker is an interrupt circuit breaker and the small-difference protection action signal of the medium circuit breaker is detected, a locking signal is sent to the line protection of the serial outgoing line;
and when the current value of the current transformer at one side of the middle breaker is greater than a preset setting value and the current value of the current transformer at the side of the middle breaker is greater than a preset multiple of the current value of the current transformer at the other side of the interrupt breaker, a unblocking signal is sent to the line protection of the line corresponding to the side of the middle breaker.
9. The system of claim 6, further to:
when the circuit breaker is a side circuit breaker and a small-difference protection action signal of the side circuit breaker is detected, a locking signal is sent to the bus protection and the line protection of the side circuit breaker;
when the current transformer current of the side breaker near bus side is greater than a preset setting value and the current transformer current of the side breaker near bus side is greater than a preset multiple of the current transformer current of the side breaker near line protection side, a locking releasing signal is sent to the bus protection of the side breaker; or
And when the current transformer current at the side close to the line of the side circuit breaker is greater than a preset setting value and the current transformer current at the side close to the line of the side circuit breaker is greater than the current transformer current at the side close to the bus of the side circuit breaker by a preset multiple, the current transformer current is sent to the line protection corresponding to the side circuit breaker to remove the blocking.
10. The system of claim 6, the execution unit to further: and sending the judgment result to line protection or bus protection in an input quantity form.
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| CN202011117626.2A CN112366664B (en) | 2020-10-19 | 2020-10-19 | Method and system for improving relay protection based on 3/2 wiring mode |
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| CN112366664B CN112366664B (en) | 2023-08-18 |
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| CN114137337A (en) * | 2021-11-17 | 2022-03-04 | 中国南方电网有限责任公司超高压输电公司广州局 | Automatic inspection method for inspection of converter station CT configuration dead zone |
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| CN105429111A (en) * | 2015-12-07 | 2016-03-23 | 许继集团有限公司 | Method for preventing differential protection maloperation of optical fiber caused by single CT saturation of 3/2 connection |
| CN107404109A (en) * | 2016-05-18 | 2017-11-28 | 河南第火电建设公司 | The failure of bus and blind area guard method |
| CN106786426A (en) * | 2017-01-17 | 2017-05-31 | 北京四方继保自动化股份有限公司 | The comprehensive distinguishing method of one Ge Ban main electrical schemes transformer station dead-zone fault |
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| CN114137337B (en) * | 2021-11-17 | 2023-11-10 | 中国南方电网有限责任公司超高压输电公司广州局 | Automatic checking method for CT configuration dead zone check of convertor station |
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| CN112366664B (en) | 2023-08-18 |
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