CN222147154U - Single bus segment PT system and device for preventing reverse power transmission during parallel operation - Google Patents

Abstract

The utility model discloses a single bus segment PT system and a device for preventing reverse power transmission during parallel connection, wherein the single bus segment PT system comprises a first PT, a second PT, a normally open auxiliary contact, a normally closed auxiliary contact and a normally open auxiliary contact, wherein the first PT is provided with a first reclosing relay, the second PT is provided with a second reclosing relay, a signal output line of a secondary side of the first PT is connected with a signal output line of a secondary side of the second PT through the normally open auxiliary contact of the parallel relay, the normally open auxiliary contact of a disconnecting switch 1QS and the normally closed auxiliary contact of a disconnecting switch 2QS are connected in series to form a first branch, the normally closed auxiliary contact of the disconnecting switch 1QS and the normally open auxiliary contact of the disconnecting switch 2QS are connected in series to form a second branch, and the first branch and the second branch after parallel connection, the normally open contact of a parallel transfer switch and the parallel relay of the bus switch are connected in series on a bus. The utility model adopts the isolating switch 1QS and the isolating switch 2QS to perform bidirectional locking, thereby avoiding PT reverse power transmission caused by improper operation of the PT parallel change-over switch SA.

Description

Single bus segment PT system and device for preventing reverse power transmission during parallel operation

Technical Field

The utility model relates to the technical field of single bus segment PT systems, in particular to a single bus segment PT system and a device for preventing reverse power transmission when the single bus segment PT systems are parallel.

Background

In a conventional transformer substation, there are often two incoming lines, and fig. 1 illustrates a common scheme of primary main loop single bus segment switches. 2QF is I female inlet wire circuit breaker on the 1# inlet wire cabinet of I section generating line, and 3QF is II female inlet wire circuit breaker on the 2# inlet wire cabinet of II section generating line, and isolator 3QS and circuit breaker 1QF are the female switch that allies oneself with on the sectional switch cabinet, and isolator 4QS is the female switch that allies oneself with on the sectional switch cabinet. The upper-level transformer is powered by 2QF and 3QF to drive the load to operate, and when 2QF or 3QF fails or breaks down, the master-linkage switch is required to drive all loads to operate. The system is provided with 2 PT cabinets, and detection and protection voltage are provided for the protection device of corresponding section.

As shown in fig. 1, the 1#pt cabinet is a voltage detection device for the I-section bus, the 2#pt cabinet is a voltage detection device for the II-section bus, the 1#pt cabinet corresponds to the disconnecting switch 1QS, and the 2#pt cabinet corresponds to the disconnecting switch 2QS.

When one section of PT is overhauled, the isolating switch at the upper end of the PT is separated, and the protection of the section of bus still needs to continue to operate at the moment, and misoperation can occur when the protection device loses voltage, so that the other section of bus PT is needed to be used for protection after being parallel to the other section of bus PT.

The current PT parallel secondary conventional design method is shown in fig. 2, namely, the primary parallel is firstly carried out, namely, the disconnecting switch 3QS of the sectional switch cabinet and the disconnecting switch 4QS of the sectional switch cabinet are closed, the breaker 1QF of the sectional switch cabinet is closed (namely, the disconnecting switch 3QS, the disconnecting switch 4QS and the breaker 1QF are collectively called as primary parallel switches), then the PT parallel change-over switch SA is arranged at a parallel position, the parallel relay BLJ is powered on, and an auxiliary contact of the parallel relay BLJ is normally opened and normally closed (see fig. 3).

When 1#PT overhauls, disconnect 1#PT corresponding isolator 1QS, isolator 1QS auxiliary normally open contact keeps normally open this moment, 1#PT cabinet heavy relay 1PTJ is unable to be electrified, then 1PTJ auxiliary contact keeps normally open, isolator 2QS that 2#PT corresponds this moment is the close position, isolator 2QS auxiliary normally open contact becomes normally closed this moment, 2#PT cabinet heavy relay 2PTJ gets the electricity, then 2PTJ auxiliary contact is normally open to become normally closed (see FIG. 3) to realize PT secondary side by side, I female protection device uses the detection voltage that II female side by side of coming, make the protection device of maintenance section can continue to operate.

However, the mode of directly protecting and using the overhaul PT by the voltage signal led out from the secondary side of the PT easily leads to the influence of the parallel arrangement of the overhaul PT on the PT, and the voltage of the secondary side of the overhaul PT greatly rises, so that the primary side of the overhaul PT can induce high-voltage electricity, and the overhaul work is endangered.

The chinese patent with publication number CN208094189U discloses a device for preventing reverse power transmission during PT overhaul, which is consistent with the principle of the conventional design method described above, except that the auxiliary contacts of the isolating switch are used instead of the auxiliary contacts of the reclosing relay.

However, if the conventional design method is used, the reverse power transmission of PT is also caused when the operation is improper, namely, the II parent is charged through the I parent, if the isolating switches 1QS and 2QS of the 1#PT are both in the closed position and the PT parallel transfer switch SA is in the parallel position, when the breaker 1QF of the sectional switch cabinet is closed, the normally open auxiliary contacts of the breaker are closed before the moving and static contacts of the breaker, the normally open auxiliary contacts of the heavy relay 1PTJ/2PTJ and the parallel relay BLJ are both normally closed, the II parent is not electrified, the secondary voltage of the 1#PT is parallel to the secondary circuit of the 2#PT, the 2#PT generates reverse power transmission, larger no-load excitation surge current is generated, and the secondary small air switches of the 1#PT and the 2#PT are tripped, so that the iron core is saturated and heated, and the insulating performance of the PT is affected.

Disclosure of utility model

In order to solve the technical problems, one of the purposes of the present utility model is to provide a single bus segment PT system, which adopts the isolating switch 1QS of the first PT and the isolating switch 2QS of the second PT to perform bidirectional locking, so as to avoid the problem of reverse power transmission of the PT caused by improper operation of the parallel transfer switch SA, and improve the safety and reliability of the single bus segment PT system.

In order to achieve the aim of the utility model, the utility model is realized by adopting the following technical scheme:

the application relates to a single busbar segmented PT system, comprising:

The first PT is provided with a first heavy-duty relay, and is connected with a normally open auxiliary contact of a disconnecting switch 1QS of the first PT in series on a bus;

a second PT having a second recloser connected in series with a normally open auxiliary contact of a disconnector 2QS of the second PT on a bus bar;

The signal output line of the secondary side of the first PT is connected with the signal output line of the secondary side of the second PT through a normally open auxiliary contact of a parallel relay;

A normally open auxiliary contact of the first reclosing relay is connected in series with a signal output line of the second PT, and a normally open auxiliary contact of the second reclosing relay is connected in series with a signal output line of the second PT;

the normally open auxiliary contact of the isolating switch 1QS and the normally closed auxiliary contact of the isolating switch 2QS are connected in series to form a first branch, and the normally closed auxiliary contact of the isolating switch 1QS and the normally open auxiliary contact of the isolating switch 2QS are connected in series to form a second branch;

The parallel connection of the first branch and the second branch, the PT parallel change-over switch, the normally open contact of the bus switch and the parallel relay is connected in series on the bus.

In some embodiments of the present application, the secondary busbar corresponding to the first PT is connected between the normally open auxiliary contact of the first reclosing relay and the normally open auxiliary contact of the parallel relay;

And the secondary small bus corresponding to the second PT is connected between the normally open auxiliary contact of the second reclosing relay and the normally open auxiliary contact of the parallel relay.

In some embodiments of the present application, a first miniature circuit breaker is disposed between a signal output line of the secondary side of the first PT and a normally open auxiliary contact of the first reclosing relay;

And a second miniature circuit breaker is arranged between a signal output line of the secondary side of the second PT and a normally open auxiliary contact of the second reclosing relay.

In some embodiments of the application, the single bus segment PT system further comprises:

The sectional switch cabinet is connected to the I-section bus and is provided with a disconnecting switch 3QS and a breaker 1QF which are arranged in series;

The sectional isolation cabinet is connected to the section II bus and is connected with the sectional switch cabinet, and an isolation switch 4QS is arranged on the sectional isolation cabinet;

The bus bar switch comprises a disconnecting switch 3QS, a breaker 1QF and a disconnecting switch 4QS.

Compared with the prior art, the single bus segment PT system of the embodiment has the following advantages:

(1) The normally open and normally closed auxiliary contacts of the isolating switch 1QS and the isolating switch 2QS are locked in two directions, when the normally open auxiliary contact of the isolating switch 1QS of the first PT and the normally open auxiliary contact of the isolating switch 2QS of the second PT are both closed, even if the PT parallel change-over switch is in a parallel position due to improper operation, PT parallel cannot be carried out due to the two-way locking of the isolating switch 1QS and the isolating switch 2QS, so that PT reverse power transmission is avoided, equipment faults are reduced, the safety of operation and maintenance personnel is protected, and economic loss is reduced;

(2) The PT system has the advantages of less wiring, cost saving, convenient production, simple operation, high safety and reliability.

The application also relates to a device for preventing reverse power transmission when the single bus segment PT system is parallel, which is used for avoiding the problems of poor reliability and safety of the single bus segment PT system caused by improper operation of the PT parallel change-over switch.

The device for preventing reverse power transmission when the single bus segment PT system is parallel is used for the single bus segment PT system, the single bus segment PT system comprises a first PT and a second PT, the first PT is provided with a first reclosing relay and is connected with a normally open auxiliary contact of a disconnecting switch 1QS of the first PT in series on a bus, the second PT is provided with a second reclosing relay and is connected with a normally open auxiliary contact of a disconnecting switch 2QS of the second PT in series on the bus, a signal output line of a second side of the first PT is connected with a signal output line of a second side of the second PT through the normally open auxiliary contact of a parallel relay, the signal output line of the second side of the first PT is connected with the normally open auxiliary contact of the first reclosing relay in series, and the signal output line of the second side of the second PT is connected with the normally open auxiliary contact of the second reclosing relay in series, and is characterized in that the device for preventing reverse power transmission when the single bus segment PT system is parallel comprises:

The bidirectional locking switch is connected with the PT parallel change-over switch, the normally open contact of the bus connection switch and the parallel relay in series on a bus, the bidirectional locking switch comprises a first branch and a second branch which are connected in parallel, the normally open auxiliary contact of the isolating switch 1QS and the normally closed auxiliary contact of the isolating switch 2QS are connected in series on the first branch, and the normally closed auxiliary contact of the isolating switch 1QS and the normally open auxiliary contact of the isolating switch 2QS are connected in series on the second branch.

In some embodiments of the present application, the secondary busbar corresponding to the first PT is connected between the normally open auxiliary contact of the first reclosing relay and the normally open auxiliary contact of the parallel relay;

And the secondary small bus corresponding to the second PT is connected between the normally open auxiliary contact of the second reclosing relay and the normally open auxiliary contact of the parallel relay.

In some embodiments of the present application, a first miniature circuit breaker is disposed between a signal output line of the secondary side of the first PT and a normally open auxiliary contact of the first reclosing relay;

And a second miniature circuit breaker is arranged between a signal output line of the secondary side of the second PT and a normally open auxiliary contact of the second reclosing relay.

In some embodiments of the application, the single bus segment PT system further comprises:

The sectional switch cabinet is connected to the I-section bus and is provided with a disconnecting switch 3QS and a breaker 1QF which are arranged in series;

The sectional isolation cabinet is connected to the section II bus and is connected with the sectional switch cabinet, and an isolation switch 4QS is arranged on the sectional isolation cabinet;

The bus bar switch comprises a disconnecting switch 3QS, a breaker 1QF and a disconnecting switch 4QS.

Other features and advantages of the present utility model will become apparent upon review of the detailed description of the utility model in conjunction with the drawings.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present utility model, the drawings that are needed in the embodiments will be briefly described below, and it is obvious that the drawings in the following description are some embodiments of the present utility model, and other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.

FIG. 1 is a functional block diagram of a prior art single bus segment PT system;

FIG. 2 is a schematic circuit diagram of a prior art single bus segment PT system PT in parallel;

FIG. 3 is a schematic diagram II of a prior art single bus segment PT system PT in parallel;

fig. 4 is a schematic circuit diagram of the single bus segment PT system PT according to the present utility model when the single bus segment PT system PT is juxtaposed.

Detailed Description

The following description of the embodiments of the present application will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present application, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the application without making any inventive effort, are intended to be within the scope of the application.

In the description of the present application, it should be understood that the terms "center," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," and the like indicate orientations or positional relationships based on the orientation or positional relationships shown in the drawings, merely to facilitate describing the present application and simplify the description, and do not indicate or imply that the devices or elements referred to must have a specific orientation, be configured and operated in a specific orientation, and thus should not be construed as limiting the present application.

The terms "first," "second," and the like, are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defining "a first" or "a second" may explicitly or implicitly include one or more such feature. In the description of the present application, unless otherwise indicated, the meaning of "a plurality" is two or more.

In the description of the present application, unless explicitly stated or limited otherwise, the terms "mounted," "connected," and "connected" are to be construed broadly, and may be, for example, fixedly connected, detachably connected, or integrally connected, mechanically connected, electrically connected, directly connected, indirectly connected via an intervening medium, or in communication between two elements. The specific meaning of the above terms in the present application will be understood in specific cases by those of ordinary skill in the art.

In the present utility model, unless expressly stated or limited otherwise, a first feature "above" or "below" a second feature may include both the first and second features being in direct contact, as well as the first and second features not being in direct contact but being in contact with each other through additional features therebetween. Moreover, a first feature being "above," "over" and "on" a second feature includes the first feature being directly above and obliquely above the second feature, or simply indicating that the first feature is higher in level than the second feature. The first feature being "under", "below" and "beneath" the second feature includes the first feature being directly under and obliquely below the second feature, or simply means that the first feature is less level than the second feature.

The following disclosure provides many different embodiments, or examples, for implementing different features of the utility model. In order to simplify the present disclosure, components and arrangements of specific examples are described below. They are, of course, merely examples and are not intended to limit the utility model. Furthermore, the present utility model may repeat reference numerals and/or letters in the various examples, which are for the purpose of brevity and clarity, and which do not themselves indicate the relationship between the various embodiments and/or arrangements discussed. In addition, the present utility model provides examples of various specific processes and materials, but one of ordinary skill in the art will recognize the application of other processes and/or the use of other materials.

In some embodiments of the present application, 1#pt is denoted as a first PT and 2#pt is denoted as a second PT.

In order to avoid the problem that when the disconnecting switch of the first PT and the second PT is in the closed position, the PT parallel change-over switch SA is wrongly operated to the parallel position to cause PT reverse power transmission, the application relates to a single bus segment PT system.

As described above, referring to fig. 1, the bus bars include segmented I and II bus bars.

The first PT is arranged under the I bus, the first PT is provided with a disconnecting switch 1QS, the second PT is arranged under the II bus, the second PT is provided with a disconnecting switch 2 QS, the sectional switch cabinet is arranged under the I bus, and the sectional switch cabinet is arranged under the II bus.

The sectional switchgear has a disconnector 2QS and a circuit breaker 1QF, and the sectional switchgear has a disconnector 4QS.

When the parallel operation is performed once, the disconnecting switch 2QS and the disconnecting switch 4QS are closed first, and then the breaker 1QF is closed, so that the bus bar switch (see the switch shown in the subsection QF and the QS position in fig. 2) comprises the disconnecting switch 2QS, the disconnecting switch 4QS and the breaker 1QF, and when the bus bar switch is closed, the closing of the disconnecting switch 2QS and the disconnecting switch 4QS is performed first, and then the closing of the breaker 1QF is performed, that is, after the closing of the breaker 1QF, the closing of the bus bar switch is indicated.

As described above, referring to fig. 2 and 3, the II bus is charged through the I bus, and if the disconnecting switch 1QS of the first PT and the disconnecting switch 2QS of the second PT are both in the closed position at this time, the PT parallel changeover switch SA is in the parallel position.

When the breaker 1QF is closed (i.e., the busbar switch is closed), the normally open auxiliary contacts of the breaker are closed before the moving and static contacts of the breaker, so that at this time, the normally open auxiliary contacts of the first recloser 1PTJ, the second recloser 2PTJ and the parallel relay BLJ are both normally closed (see fig. 3), while the II busbar is not electrified, at this time, the secondary voltage of the first PT is juxtaposed to the second PT secondary circuit, and the second PT generates reverse power.

In order to solve the problem of reverse power transmission generated by PT, referring to FIG. 4, a disconnecting switch 1QS and a disconnecting switch 2QS are adopted for bidirectional locking, specifically, a normally open auxiliary contact of the disconnecting switch 1QS and a normally closed auxiliary contact of the disconnecting switch 2QS are connected in series to form a first branch, a normally closed auxiliary contact of the disconnecting switch 1QS and a normally open auxiliary contact of the disconnecting switch 2QS form a second branch, and after the first branch and the second branch are connected in parallel, the first branch and the normally open contact of the PT parallel switch SA and a normally open contact of a bus switch are connected in series on a bus +/-KM.

Specifically, one point of the first branch and the second branch which are connected in parallel is connected to a busbar +KM, the other point is connected to one end of a PT parallel change-over switch SA, the other end of the PT parallel change-over switch SA is connected to one end of a bus switch, the other end of the bus switch is connected to one end of a coil of a parallel relay BLJ, and the other end of the coil is connected to the busbar-KM.

When the isolating switch 1QS of the first PT and the isolating switch 2QS of the second PT are both in the closed position, the normally open auxiliary contact of the isolating switch 1QS and the normally open auxiliary contact of the isolating switch 2QS are both normally closed, the normally closed auxiliary contact is normally open, and at this time, the first reclosing relay 1PTJ and the second reclosing relay 2PTJ are both powered on, and the corresponding normally open auxiliary contacts are closed (see fig. 3).

However, since the bidirectional latching circuit is not turned on at this time, even if the PT parallel changeover switch SA is not properly operated and is put in the PT parallel position in advance, the instant when the disconnecting switch and the circuit breaker (i.e., the bus-tie switch) are combined at the sectionalized position, the normally open auxiliary contact of the circuit breaker is closed before the moving contact of the circuit breaker, the parallel relay BLJ cannot get electricity, that is, the normally open auxiliary contact of the parallel relay BLJ cannot be closed (see fig. 3), PT parallel cannot be realized, the secondary voltage of the first PT cannot be put in parallel to the secondary side of the second PT, thereby avoiding reverse power transmission of the PT and ensuring the safety of the device.

Referring to fig. 4, when the first PT needs to be overhauled, the isolating switch 1QS of the first PT is separated, at this time, the normally open auxiliary contact of the isolating switch 1QS is kept normally open, the normally closed auxiliary contact is kept normally closed, the first reclosing relay 1PTJ of the first PT is not powered, and the normally open auxiliary contact corresponding to the first reclosing relay 1PTJ is kept normally open.

And the isolating switch 2QS of the second PT is kept closed, at this time, the normally open auxiliary contact of the isolating switch 2QS becomes normally closed, the normally closed auxiliary contact becomes normally open, the second reclosing relay 2PTJ of the second PT is powered on, and the normally open auxiliary contact corresponding to the second reclosing relay 2PTJ becomes normally closed.

At the moment, the circuit of the bidirectional locking part is conducted, the isolating switch 3QS/4QS and the breaker 1QF at the subsection are closed, the corresponding normally open auxiliary contact is changed to be normally closed, the PT parallel change-over switch SA is arranged at the parallel position, the parallel relay BLJ is electrified, the normally open auxiliary contact corresponding to the parallel relay BLJ is changed to be normally closed, and PT secondary parallel is realized (see figure 3), so that the I bus protection device normally operates.

Similarly, when the second PT needs to be overhauled, the isolating switch 2QS of the second PT is separated, at this time, the normally open auxiliary contact of the isolating switch 2QS is kept normally open, the normally closed auxiliary contact is kept normally closed, the second reclosing relay 2PTJ of the second PT is not powered, and the normally open auxiliary contact corresponding to the second reclosing relay 2PTJ is kept normally open.

And the isolating switch 1QS of the first PT is kept closed, at the moment, the normally open auxiliary contact of the isolating switch 1QS is changed into normally closed, the normally closed auxiliary contact is changed into normally open, the first reclosing relay 1PTJ of the first PT is powered on, and the normally open auxiliary contact corresponding to the first reclosing relay 1PTJ is changed into normally closed.

At the moment, the circuit of the bidirectional locking part is conducted, the isolating switch 3QS/4QS and the breaker 1QF at the subsection are closed, the corresponding normally open auxiliary contact is changed to be normally closed, the PT parallel change-over switch SA is arranged at the parallel position, the parallel relay BLJ is electrified, the normally open auxiliary contact corresponding to the parallel relay BLJ is changed to be normally closed, and PT secondary parallel is realized (see figure 3), so that the II busbar protection device normally operates.

By arranging the bidirectional locking part, the parallel connection of the PTs can be performed only when the state of the isolating switch 1QS of the first PT of the I-section bus and the state of the isolating switch 2QS of the second PT of the II-section bus are one-to-one, and when the isolating switches 1QS and 2QS are both closed, the parallel connection of the PTs can not be performed even if the PT parallel change-over switch SA is arranged at the parallel position due to improper operation, so that the reverse power transmission of the PTs is avoided.

Referring to fig. 3, a secondary busbar (1 YMa, 1YMb, 1 YMc) corresponding to the first PT is connected between a normally open auxiliary contact of the first reclosing relay 1PTJ and a normally open auxiliary contact of the parallel relay BLJ, and the secondary busbar corresponding to the first PT outputs a voltage acquisition signal to the I busbar protection device for protection judgment.

The secondary small buses (2 YMa, 2YMb and 2 YMc) corresponding to the second PT are connected between the normally open auxiliary contact of the second reclosing relay 2PTJ and the normally open auxiliary contact of the parallel relay BLJ, and the secondary small buses corresponding to the second PT output voltage acquisition signals to the II bus protection device for protection judgment.

In some embodiments of the present application, in order to protect the signal output line to a certain extent, a first protection switch (not shown) may be disposed between the secondary busbar (1 YMa, 1YMb, 1 YMc) corresponding to the first PT and the normally open auxiliary contact of the first recloser 1PTJ, and a second protection switch (not shown) may be disposed between the secondary busbar (2 YMa, 2YMb, 2 YMc) corresponding to the second PT and the normally open auxiliary contact of the second recloser 2 PTJ.

A first miniature circuit breaker DK1 is provided between the signal output lines of the secondary sides (1 TV1, 1TV2, 1TV 3) of the first PT and the normally open auxiliary contact of the first recloser relay 1 PTJ.

A second miniature circuit breaker DK2 is arranged between the signal output line of the secondary side (2 TV1, 2TV2, 2TV 3) of the second PT and the normally open auxiliary contact of the second recloser 2 PTJ.

Therefore, the PT secondary side is connected to the secondary busbar of the upper corresponding section behind the protection switch through the normally open auxiliary signal corresponding to the miniature circuit breaker and the reclosing relay.

The application also relates to a device for preventing reverse power transmission when the single bus segment PT system is in parallel, which mainly relates to a bidirectional locking switch (see fig. 4), wherein the bidirectional locking switch is a bidirectional locking part, so that when the isolating switches 1QS and 2QS are both closed, the PT parallel change-over switch SA cannot be in parallel even if the PT parallel change-over switch SA is in a parallel position due to improper operation, and the reverse power transmission of the PT is avoided, and the use safety and reliability of the single bus segment PT system are ensured.

The bidirectional locking switch added above has the advantages of simple structure, easy realization, convenient realization and wiring, and reduced input cost on the basis of ensuring the use safety of the single bus segment PT system.

The above embodiments are only for illustrating the technical solution of the present utility model, but not for limiting the same, and although the present utility model has been described in detail with reference to the above embodiments, it will be apparent to those skilled in the art that modifications may be made to the technical solution described in the above embodiments or equivalents may be substituted for some of the technical features thereof, and the modifications or substitutions do not depart from the spirit and scope of the technical solution as claimed in the present utility model.

Claims (8)

1. A single bus segment PT system, comprising:

The first PT is provided with a first heavy-duty relay, and is connected with a normally open auxiliary contact of a disconnecting switch 1QS of the first PT in series on a bus;

a second PT having a second recloser connected in series with a normally open auxiliary contact of a disconnector 2QS of the second PT on a bus bar;

The signal output line of the secondary side of the first PT is connected with the signal output line of the secondary side of the second PT through a normally open auxiliary contact of a parallel relay;

A normally open auxiliary contact of the first reclosing relay is connected in series with a signal output line of the second PT, and a normally open auxiliary contact of the second reclosing relay is connected in series with a signal output line of the second PT;

the normally open auxiliary contact of the isolating switch 1QS and the normally closed auxiliary contact of the isolating switch 2QS are connected in series to form a first branch, and the normally closed auxiliary contact of the isolating switch 1QS and the normally open auxiliary contact of the isolating switch 2QS are connected in series to form a second branch;

The parallel connection of the first branch and the second branch, the PT parallel change-over switch, the normally open contact of the bus switch and the parallel relay is connected in series on the bus.

2. The single busbar segmented PT system of claim 1, wherein,

The secondary busbar corresponding to the first PT is connected between the normally open auxiliary contact of the first reclosing relay and the normally open auxiliary contact of the parallel relay;

And the secondary small bus corresponding to the second PT is connected between the normally open auxiliary contact of the second reclosing relay and the normally open auxiliary contact of the parallel relay.

3. The single busbar segmented PT system of claim 1, wherein,

A first miniature circuit breaker is arranged between a signal output line of the secondary side of the first PT and a normally open auxiliary contact of the first reclosing relay;

And a second miniature circuit breaker is arranged between a signal output line of the secondary side of the second PT and a normally open auxiliary contact of the second reclosing relay.

4. The single bus segment PT system of claim 1, the single bus segment PT system is characterized by further comprising:

The sectional switch cabinet is connected to the I-section bus and is provided with a disconnecting switch 3QS and a breaker 1QF which are arranged in series;

The sectional isolation cabinet is connected to the section II bus and is connected with the sectional switch cabinet, and an isolation switch 4QS is arranged on the sectional isolation cabinet;

The bus bar switch comprises a disconnecting switch 3QS, a breaker 1QF and a disconnecting switch 4QS.

5. The device for preventing reverse power transmission when the single bus segment PT system is parallel is used for the single bus segment PT system, the single bus segment PT system comprises a first PT and a second PT, the first PT is provided with a first reclosing relay and is connected with a normally open auxiliary contact of a disconnecting switch 1QS of the first PT in series on a bus, the second PT is provided with a second reclosing relay and is connected with a normally open auxiliary contact of a disconnecting switch 2QS of the second PT in series on the bus, a signal output line of a second side of the first PT is connected with a signal output line of a second side of the second PT through the normally open auxiliary contact of a parallel relay, the signal output line of the second side of the first PT is connected with the normally open auxiliary contact of the first reclosing relay in series, and the signal output line of the second side of the second PT is connected with the normally open auxiliary contact of the second reclosing relay in series, and is characterized in that the device for preventing reverse power transmission when the single bus segment PT system is parallel comprises:

The bidirectional locking switch is connected with the PT parallel change-over switch, the normally open contact of the bus connection switch and the parallel relay in series on a bus, the bidirectional locking switch comprises a first branch and a second branch which are connected in parallel, the normally open auxiliary contact of the isolating switch 1QS and the normally closed auxiliary contact of the isolating switch 2QS are connected in series on the first branch, and the normally closed auxiliary contact of the isolating switch 1QS and the normally open auxiliary contact of the isolating switch 2QS are connected in series on the second branch.

6. The apparatus for preventing reverse power transmission when single bus segment PT systems are juxtaposed according to claim 5,

The secondary busbar corresponding to the first PT is connected between the normally open auxiliary contact of the first reclosing relay and the normally open auxiliary contact of the parallel relay;

And the secondary small bus corresponding to the second PT is connected between the normally open auxiliary contact of the second reclosing relay and the normally open auxiliary contact of the parallel relay.

7. The apparatus for preventing reverse power transmission when single bus segment PT systems are juxtaposed according to claim 5,

A first miniature circuit breaker is arranged between a signal output line of the secondary side of the first PT and a normally open auxiliary contact of the first reclosing relay;

And a second miniature circuit breaker is arranged between a signal output line of the secondary side of the second PT and a normally open auxiliary contact of the second reclosing relay.

8. The apparatus for preventing reverse power transmission when single bus-section PT systems are juxtaposed as claimed in claim 5, further comprising:

The sectional switch cabinet is connected to the I-section bus and is provided with a disconnecting switch 3QS and a breaker 1QF which are arranged in series;

The sectional isolation cabinet is connected to the section II bus and is connected with the sectional switch cabinet, and an isolation switch 4QS is arranged on the sectional isolation cabinet;

The bus bar switch comprises a disconnecting switch 3QS, a breaker 1QF and a disconnecting switch 4QS.