Single-bus segmented PT system and device for preventing reverse power transmission during parallel connection of single-bus segmented PT system

Abstract

The utility model discloses a single-bus segmented PT system and a device for preventing reverse power transmission in parallel, and the system comprises a first PT which is provided with a first repeat relay, a second PT which is provided with a second repeat relay, and a third PT which is provided with a second repeat relay. A second PT having a second repeat relay; 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 the parallel relay; 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; and the first branch and the second branch which are connected in parallel, the PT parallel change-over switch, the normally open contact of the bus tie switch and the parallel relay are connected in series on a bus. According to the utility model, the isolating switch 1QS and the isolating switch 2QS are used for bidirectional locking, so that PT reverse power transmission caused by improper operation of the PT parallel change-over switch SA is avoided.

Description

Technical Field

[0001] The utility model relates to the technical field of single busbar segmented PT systems, in particular to a single busbar segmented PT system and a device for preventing reverse power transmission when the single busbar segmented PT systems are connected in parallel. Background Art

[0002] In conventional substations, there are usually two sections of incoming lines. Figure 1 The diagram shows a common scheme of single-mother sectionalizing switch for primary main circuit. 2QF is the incoming breaker of busbar Ⅰ on the incoming cabinet of busbar 1# of section Ⅰ, 3QF is the incoming breaker of busbar Ⅱ on the incoming cabinet of busbar 2# of section Ⅱ, disconnector 3QS and circuit breaker 1QF are the bus tie switches on the sectionalizing switch cabinet, and disconnector 4QS is the bus tie switch on the sectionalizing isolation cabinet. The low voltage electricity from the upper transformer is driven by the closing of 2QF and 3QF respectively to drive the load to run; when 2QF or 3QF fails or opens, the bus tie switch needs to be closed to drive all loads to run. The system is equipped with 2 PT cabinets to provide detection and protection voltage for the protection devices of the corresponding sections.

[0003] like Figure 1 As shown, 1# PT cabinet is the voltage detection equipment for section I bus, 2# PT cabinet is the voltage detection equipment for section II bus, 1# PT cabinet corresponds to disconnector 1QS, 2# PT cabinet corresponds to disconnector 2QS.

[0004] When one section of the PT is under maintenance, the isolating switch at the upper end of the PT is separated. At this time, the protection of this section of the busbar still needs to continue to operate. The protection device will malfunction due to voltage loss. In this case, the PT voltage of another section of the busbar needs to be connected in parallel and provided to this section for protection.

[0005] The current PT parallel quadratic conventional design method can be found in Figure 2 As shown: first parallel, that is, close the disconnector 3QS of the sectionalizing switch cabinet and the disconnector 4QS of the sectionalizing disconnector cabinet, close the circuit breaker 1QF of the sectionalizing switch cabinet (that is, the disconnector 3QS, the disconnector 4QS and the circuit breaker 1QF are collectively referred to as the primary parallel switch), then turn the PT parallel transfer switch SA to the parallel position, the parallel relay BLJ is energized, and the auxiliary contact of the parallel relay BLJ changes from normally open to normally closed (see Figure 3 ).

[0006] When 1#PT is under maintenance, disconnect the isolating switch 1QS corresponding to 1#PT. At this time, the auxiliary normally open contact of isolating switch 1QS remains normally open, and the heavy relay 1PTJ of 1#PT cabinet is not energized, so the auxiliary contact of 1PTJ remains normally open. At this time, the isolating switch 2QS corresponding to 2#PT is in the closed position. At this time, the auxiliary normally open contact of isolating switch 2QS becomes normally closed, and the heavy relay 2PTJ of 2#PT cabinet is energized, so the auxiliary contact of 2PTJ changes from normally open to normally closed (see Figure 3), thereby realizing the secondary parallel connection of PT, and the I bus protection device uses the detection voltage from the II bus parallel connection to enable the protection device of the maintenance section to operate continuously.

[0007] However, this method of directly giving the voltage signal derived from the secondary side of the PT to the maintenance PT for protection can easily cause the maintenance PT to be affected by the PT parallel connection, and the secondary side voltage of the maintenance PT will rise sharply. Then, the primary side of the maintenance PT will induce high voltage electricity, which will bring harm to the maintenance work.

[0008] A Chinese patent with authorization announcement number CN208094189U discloses a device for preventing reverse power supply during PT maintenance. The method disclosed in the patent is consistent with the principle of the conventional design method described above, except that the auxiliary contacts of the heavy-duty relay are replaced by the auxiliary contacts of the isolating switch.

[0009] However, if the conventional design method is followed, improper operation will also cause PT back-current transmission: charging Ⅱ bus through Ⅰ bus. If at this time the isolating switch 1QS of 1#PT and the isolating switch 2QS of 2#PT are both in the closed position, and the PT parallel transfer switch SA is in the parallel position, when the circuit breaker 1QF of the section switch cabinet is closed, because the normally open auxiliary contacts of the circuit breaker are closed before the moving and static contacts of the circuit breaker, the normally open auxiliary contacts of the heavy relay 1PTJ / 2PTJ and the parallel relay BLJ are all changed to normally closed, and Ⅱ bus is not yet energized, the secondary voltage of 1#PT is connected in parallel to the secondary circuit of 2#PT, 2#PT generates back-current transmission, and generates a large no-load excitation surge current, which causes the secondary small air switches of 1#PT and 2#PT to trip, and causes saturation and heating of the iron core, affecting the insulation performance of the PT. Utility Model Content

[0010] In order to solve the above technical problems, one of the purposes of the utility model is to provide a single busbar segmented PT system, which adopts the isolating switch 1QS of the first PT and the isolating switch 2QS of the second PT for bidirectional interlocking, so as to avoid the problem of PT reverse power supply caused by improper operation of the PT parallel transfer switch SA, and improve the safety and reliability of the single busbar segmented PT system.

[0011] In order to achieve the above-mentioned utility model purpose, the utility model adopts the following technical solutions:

[0012] The present application relates to a single busbar segmented PT system, comprising:

[0013] A first PT having a first heavy-duty relay connected in series with a normally open auxiliary contact of a disconnector 1QS of the first PT on a bus;

[0014] a second PT having a second heavy-duty relay connected in series on the bus with a normally open auxiliary contact of a disconnector 2QS of the second PT;

[0015] The signal output circuit of the secondary side of the first PT is connected to the signal output circuit of the secondary side of the second PT via a normally open auxiliary contact of a parallel relay;

[0016] The signal output circuit of the secondary side of the first PT is connected in series with the normally open auxiliary contact of the first heavy-duty relay, and the signal output circuit of the secondary side of the second PT is connected in series with the normally open auxiliary contact of the second heavy-duty relay;

[0017] 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;

[0018] The first branch and the second branch connected in parallel, the PT parallel change-over switch, the normally open contact of the bus tie switch and the parallel relay are connected in series on the bus.

[0019] In some embodiments of the present application, the secondary small busbar corresponding to the first PT is connected between the normally open auxiliary contact of the first heavy-duty relay and the normally open auxiliary contact of the parallel relay;

[0020] The secondary busbar corresponding to the second PT is connected between the normally open auxiliary contact of the second heavy relay and the normally open auxiliary contact of the parallel relay.

[0021] In some embodiments of the present application, a first miniature circuit breaker is provided between the signal output circuit of the secondary side of the first PT and the normally open auxiliary contact of the first heavy relay;

[0022] A second miniature circuit breaker is provided between the signal output line of the secondary side of the second PT and the normally open auxiliary contact of the second heavy relay.

[0023] In some embodiments of the present application, the single busbar segmented PT system further includes:

[0024] Sectional switch cabinet, which is connected to the busbar of section I and is provided with disconnector 3QS and circuit breaker 1QF arranged in series;

[0025] A sectional isolating cabinet, which is connected to the II-section busbar and connected to the sectional switch cabinet, and the sectional isolating cabinet is provided with an isolating switch 4QS;

[0026] The busbar switch includes an isolating switch 3QS, a circuit breaker 1QF and an isolating switch 4QS.

[0027] Compared with the prior art, the advantages and beneficial effects of the single busbar segmented PT system of this embodiment are as follows:

[0028] (1) The normally open and normally closed auxiliary contacts of the disconnector 1QS and the disconnector 2QS are bidirectionally locked. When the normally open auxiliary contacts of the disconnector 1QS of the first PT and the normally open auxiliary contacts of the disconnector 2QS of the second PT are both closed, even if the PT parallel transfer switch is turned to the parallel position due to improper operation, the PT cannot be paralleled due to the bidirectional locking of the disconnector 1QS and the disconnector 2QS, thereby avoiding PT reverse power transmission, reducing equipment failures, protecting the safety of operation and maintenance personnel, and reducing economic losses;

[0029] (2) The PT system has fewer wiring connections, saves costs, is easy to produce, simple to operate, and has high safety and reliability.

[0030] The present application also relates to a device for preventing reverse power transmission of a single busbar segmented PT system when the system is in parallel, which is used to avoid the problem of poor reliability and safety of the single busbar segmented PT system caused by improper operation of the PT parallel transfer switch.

[0031] A device for preventing reverse power transmission when a single busbar segmented PT system is connected in parallel, which is used for a single busbar segmented PT system. The single busbar segmented PT system includes a first PT and a second PT. The first PT has a first heavy-duty relay and is connected in series with the normally open auxiliary contact of the isolating switch 1QS of the first PT on the busbar, and the second PT has a second heavy-duty relay and is connected in series with the normally open auxiliary contact of the isolating switch 2QS of the second PT on the busbar; the signal output circuit on the secondary side of the first PT is connected to the signal output circuit on the secondary side of the second PT through the normally open auxiliary contact of the parallel relay; the signal output circuit on the secondary side of the first PT is connected in series with the normally open auxiliary contact of the first heavy-duty relay, and the signal output circuit on the secondary side of the second PT is connected in series with the normally open auxiliary contact of the second heavy-duty relay. The device for preventing reverse power transmission when a single busbar segmented PT system is connected in parallel includes:

[0032] A two-way locking switch, which is connected in series with the PT parallel transfer switch, the normally open contacts of the bus tie switch and the parallel relay on the bus, and the two-way locking switch includes a first branch and a second branch in parallel, the normally open auxiliary contacts of the isolating switch 1QS and the normally closed auxiliary contacts of the isolating switch 2QS are connected in series on the first branch, and the normally closed auxiliary contacts of the isolating switch 1QS and the normally open auxiliary contacts of the isolating switch 2QS are connected in series on the second branch.

[0033] In some embodiments of the present application, the secondary small busbar corresponding to the first PT is connected between the normally open auxiliary contact of the first heavy-duty relay and the normally open auxiliary contact of the parallel relay;

[0034] The secondary busbar corresponding to the second PT is connected between the normally open auxiliary contact of the second heavy relay and the normally open auxiliary contact of the parallel relay.

[0035] In some embodiments of the present application, a first miniature circuit breaker is provided between the signal output circuit of the secondary side of the first PT and the normally open auxiliary contact of the first heavy relay;

[0036] A second miniature circuit breaker is provided between the signal output line of the secondary side of the second PT and the normally open auxiliary contact of the second heavy relay.

[0037] In some embodiments of the present application, the single busbar segmented PT system further includes:

[0038] Sectional switch cabinet, which is connected to the busbar of section I and is provided with disconnector 3QS and circuit breaker 1QF arranged in series;

[0039] A sectional isolating cabinet, which is connected to the II-section busbar and connected to the sectional switch cabinet, and the sectional isolating cabinet is provided with an isolating switch 4QS;

[0040] The busbar switch includes an isolating switch 3QS, a circuit breaker 1QF and an isolating switch 4QS.

[0041] After reading the specific embodiments of the present invention in conjunction with the accompanying drawings, other features and advantages of the present invention will become more clear. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, a brief introduction will be given below to the drawings required for use in the embodiments. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0043] Figure 1 This is the principle block diagram of the existing single busbar segmented PT system;

[0044] Figure 2 This is the circuit principle of the existing single busbar segmented PT system when PTs are connected in parallel Figure 1 ;

[0045] Figure 3 This is the circuit principle of the existing single busbar segmented PT system when PTs are connected in parallel Figure 2 ;

[0046] Figure 4 It is a circuit principle diagram of a single busbar segmented PT system when PTs are connected in parallel. DETAILED DESCRIPTION

[0047] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0048] In the description of the present application, it should be understood that the terms "center", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.

[0049] The terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of this application, unless otherwise specified, "plurality" means two or more.

[0050] In the description of this application, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0051] In the present utility model, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may include that the first and second features are in direct contact, or may include that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, a first feature being "above", "above" and "above" a second feature includes that the first feature is directly above and obliquely above the second feature, or simply indicates that the first feature is higher in level than the second feature. A first feature being "below", "below" and "below" a second feature includes that the first feature is directly below and obliquely below the second feature, or simply indicates that the first feature is lower in level than the second feature.

[0052] The disclosure below provides many different embodiments or examples for realizing different structures of the utility model. In order to simplify the disclosure of the utility model, the components and settings of specific examples are described below. Of course, they are merely examples, and the purpose is not to limit the utility model. In addition, the utility model may repeat reference numbers and / or reference letters in different examples, and such repetition is for the purpose of simplification and clarity, and does not itself indicate the relationship between the various embodiments and / or settings discussed. In addition, the utility model provides various specific examples of processes and materials, but those of ordinary skill in the art may be aware of the application of other processes and / or the use of other materials.

[0053] In some embodiments of the present application, 1#PT is denoted as the first PT, and 2#PT is denoted as the second PT.

[0054] In order to avoid the problem of PT reverse power transmission caused by the PT parallel transfer switch SA being turned to the parallel position due to improper operation when the disconnectors of the first PT and the second PT are both in the closed position, the present application relates to a single busbar segmented PT system.

[0055] As mentioned above, see Figure 1 The busbar includes segmented busbar I and busbar II.

[0056] There is a first PT under busbar I, and the first PT has an isolating switch 1QS; there is a second PT under busbar II, and the second PT has an isolating switch 2QS; there is a section switch cabinet under busbar I, and there is a section isolating cabinet under busbar II.

[0057] The section switch cabinet has a disconnector 2QS and a circuit breaker 1QF, and the section isolation cabinet has a disconnector 4QS.

[0058] When paralleling, the disconnector 2QS and disconnector 4QS are closed first, and then the circuit breaker 1QF is closed. Therefore, the bus tie switch (see Figure 2 The switches shown at the sections QF and QS positions shown in the figure include disconnector 2QS, disconnector 4QS and circuit breaker 1QF. When the main coupling switch is closed, it means that disconnector 2QS and disconnector 4QS are closed first, and then circuit breaker 1QF is closed, that is, after circuit breaker 1QF is closed, the main coupling switch is closed.

[0059] As mentioned above, see Figure 2 and Figure 3 , charge bus II through bus I. If at this time the isolating switch 1QS of the first PT and the isolating switch 2QS of the second PT are both in the closed position, and the PT parallel transfer switch SA is in the parallel position.

[0060] When the circuit breaker 1QF is closed (i.e., the busbar switch is closed), the normally open auxiliary contacts of the circuit breaker are closed before the moving and static contacts of the circuit breaker. Therefore, the normally open auxiliary contacts of the first heavy-duty relay 1PTJ, the second heavy-duty relay 2PTJ, and the parallel relay BLJ all become normally closed (see Figure 3 ), and bus II is not yet energized. At this time, the secondary voltage of the first PT is connected in parallel to the secondary circuit of the second PT, and the second PT generates reverse power.

[0061] To solve the problem of reverse power transmission generated by PT, refer to Figure 4 , use isolating switch 1QS and isolating switch 2QS for bidirectional interlocking. Specifically, the normally open auxiliary contact of isolating switch 1QS and the normally closed auxiliary contact of isolating switch 2QS are connected in series to form a first branch, and the normally closed auxiliary contact of isolating switch 1QS and the normally open auxiliary contact of isolating switch 2QS form a second branch. After the first branch and the second branch are connected in parallel, the normally open contacts of the PT parallel conversion switch SA and the bus tie switch are connected in series on the bus ±KM.

[0062] Specifically, one point where the first branch and the second branch are connected in parallel is connected to the bus +KM, and another point is connected to one end of the PT parallel transfer switch SA, the other end of the PT parallel transfer switch SA is connected to one end of the bus tie switch, the other end of the bus tie switch is connected to one end of the coil of the parallel relay BLJ, and the other end of the coil is connected to the bus -KM.

[0063] When the disconnector 1QS of the first PT and the disconnector 2QS of the second PT are both in the closed position, the normally open auxiliary contacts of the disconnector 1QS and the normally open auxiliary contacts of the disconnector 2QS become normally closed, and the normally closed auxiliary contacts become normally open. At this time, the first heavy-duty relay 1PTJ and the second heavy-duty relay 2PTJ are both energized, and the corresponding normally open auxiliary contacts are closed (see Figure 3 ).

[0064] However, since the bidirectional interlocking circuit is not conducting at this time, even if the PT parallel transfer switch SA is placed in the PT parallel position in advance due to improper operation, at the moment when the disconnector and circuit breaker (i.e., busbar switch) at the merging section are combined, although the normally open auxiliary contacts of the circuit breaker are closed before the moving and static contacts of the circuit breaker, the parallel relay BLJ cannot be energized, that is, the normally open auxiliary contacts of the parallel relay BLJ cannot be closed (see Figure 3 ), PTs cannot be connected in parallel, and the secondary voltage of the first PT cannot be connected in parallel to the secondary side of the second PT, thereby avoiding PT reverse power transmission and ensuring equipment safety.

[0065] See also Figure 4When 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 remains normally open, the normally closed auxiliary contact remains normally closed, the first heavy-duty relay 1PTJ of the first PT shall not be energized, and the normally open auxiliary contact corresponding to the first heavy-duty relay 1PTJ remains normally open.

[0066] And the isolating switch 2QS of the second PT remains 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 heavy relay 2PTJ of the second PT is energized, and the normally open auxiliary contact corresponding to the second heavy relay 2PTJ becomes normally closed.

[0067] At this time, the bidirectional locking circuit is turned on, the disconnector 3QS / 4QS and the circuit breaker 1QF at the section are closed, the corresponding normally open auxiliary contacts become normally closed, the PT parallel transfer switch SA is turned to the parallel position, the parallel relay BLJ is energized, and the normally open auxiliary contacts corresponding to the parallel relay BLJ become normally closed, realizing the secondary paralleling of the PT (see Figure 3 ), so that the bus protection device I operates normally.

[0068] Similarly, when the second PT needs maintenance, the isolating switch 2QS of the second PT is separated. At this time, the normally open auxiliary contacts of the isolating switch 2QS remain normally open, the normally closed auxiliary contacts remain normally closed, the second heavy relay 2PTJ of the second PT is not energized, and the normally open auxiliary contacts corresponding to the second heavy relay 2PTJ remain normally open.

[0069] And the isolating switch 1QS of the first PT remains closed, at this time the normally open auxiliary contact of the isolating switch 1QS becomes normally closed, the normally closed auxiliary contact becomes normally open, the first heavy-duty relay 1PTJ of the first PT is energized, and the normally open auxiliary contact corresponding to the first heavy-duty relay 1PTJ becomes normally closed.

[0070] At this time, the bidirectional locking circuit is turned on, the disconnector 3QS / 4QS and the circuit breaker 1QF at the section are closed, the corresponding normally open auxiliary contacts become normally closed, the PT parallel transfer switch SA is turned to the parallel position, the parallel relay BLJ is energized, and the normally open auxiliary contacts corresponding to the parallel relay BLJ become normally closed, realizing the secondary paralleling of the PT (see Figure 3 ), so that the II busbar protection device operates normally.

[0071] In this way, by setting up the two-way locking part, PT paralleling can only be performed when the states of the disconnector 1QS of the first PT of the I section bus and the disconnector 2QS of the second PT of the II section bus are one open and one closed. When the disconnectors 1QS and 2QS are both closed, even if the PT parallel transfer switch SA is in the parallel position due to improper operation, the PT paralleling cannot be performed, thereby avoiding PT reverse power supply.

[0072] See also Figure 3 The secondary busbar (1YMa, 1YMb, 1YMc) corresponding to the first PT is connected between the normally open auxiliary contact of the first heavy relay 1PTJ and the normally open auxiliary contact of the parallel relay BLJ. The secondary busbar corresponding to the first PT outputs the voltage acquisition signal to the I busbar protection device for protection judgment.

[0073] The secondary small busbar (2YMa, 2YMb, 2YMc) corresponding to the second PT is connected between the normally open auxiliary contact of the second heavy relay 2PTJ and the normally open auxiliary contact of the parallel relay BLJ. The secondary small busbar corresponding to the second PT outputs the voltage acquisition signal to the II busbar protection device for protection judgment.

[0074] In some embodiments of the present application, in order to provide a certain degree of protection for the signal output line, a first protection switch (not shown) may be provided between the secondary busbar (1YMa, 1YMb, 1YMc) corresponding to the first PT and the normally open auxiliary contact of the first heavy-duty relay 1PTJ, and a second protection switch (not shown) may be provided between the secondary busbar (2YMa, 2YMb, 2YMc) corresponding to the second PT and the normally open auxiliary contact of the second heavy-duty relay 2PTJ.

[0075] Furthermore, a first miniature circuit breaker DK1 is provided between the signal output line of the secondary side (1TV1, 1TV2, 1TV3) of the first PT and the normally open auxiliary contact of the first heavy relay 1PTJ.

[0076] A second miniature circuit breaker DK2 is provided between the signal output line of the secondary side (2TV1, 2TV2, 2TV3) of the second PT and the normally open auxiliary contact of the second heavy relay 2PTJ.

[0077] Therefore, the secondary side of the PT is connected to the secondary busbar of the corresponding section behind the protection switch through the normally open auxiliary signal of the corresponding miniature circuit breaker and heavy-duty relay.

[0078] The present application also relates to a device for preventing reverse power transmission when a single busbar segmented PT system is connected in parallel, mainly involving a bidirectional locking switch (see Figure 4 ), the two-way locking switch is the two-way locking part as mentioned above, which can prevent the PT from being paralleled when the disconnectors 1QS and 2QS are both closed, even if the PT parallel transfer switch SA is in the parallel position due to improper operation, thereby avoiding PT reverse power transmission and ensuring the safety and reliability of the single busbar segmented PT system.

[0079] The bidirectional locking switch added as above has a simple structure and is easy to implement, convenient to implement and wire, and reduces investment costs while ensuring the safety of the single-busbar segmented PT system.

[0080] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the above embodiments, it is still possible for a person skilled in the art to modify the technical solutions described in the above embodiments, or to replace some of the technical features therein with equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions claimed to be protected by the present invention.

Claims

1. A single busbar segmented PT system, It is characterized in that include: A first PT having a first heavy-duty relay connected in series with a normally open auxiliary contact of a disconnector 1QS of the first PT on a bus; a second PT having a second heavy-duty relay connected in series on the bus with a normally open auxiliary contact of a disconnector 2QS of the second PT; The signal output circuit of the secondary side of the first PT is connected to the signal output circuit of the secondary side of the second PT via a normally open auxiliary contact of a parallel relay; The signal output circuit of the secondary side of the first PT is connected in series with the normally open auxiliary contact of the first heavy-duty relay, and the signal output circuit of the secondary side of the second PT is connected in series with the normally open auxiliary contact of the second heavy-duty relay; 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 first branch and the second branch connected in parallel, the PT parallel change-over switch, the normally open contact of the bus tie switch and the parallel relay are connected in series on the bus.

2. The single busbar segmented PT system according to claim 1, It is characterized in that The secondary busbar corresponding to the first PT is connected between the normally open auxiliary contact of the first heavy-duty relay and the normally open auxiliary contact of the parallel relay; The secondary busbar corresponding to the second PT is connected between the normally open auxiliary contact of the second heavy relay and the normally open auxiliary contact of the parallel relay.

3. The single busbar segmented PT system according to claim 1, It is characterized in that A first miniature circuit breaker is provided between the signal output circuit of the secondary side of the first PT and the normally open auxiliary contact of the first heavy relay; A second miniature circuit breaker is provided between the signal output line of the secondary side of the second PT and the normally open auxiliary contact of the second heavy relay.

4. The single busbar segmented PT system according to claim 1, It is characterized in that The single busbar segmented PT system further comprises: Sectional switch cabinet, which is connected to the busbar of section I and is provided with disconnector 3QS and circuit breaker 1QF arranged in series; A sectional isolating cabinet, which is connected to the II-section busbar and connected to the sectional switch cabinet, and the sectional isolating cabinet is provided with an isolating switch 4QS; The busbar switch includes an isolating switch 3QS, a circuit breaker 1QF and an isolating switch 4QS.

5. A device for preventing reverse power transmission when a single-busbar segmented PT system is paralleled, which is used for a single-busbar segmented PT system, wherein the single-busbar segmented PT system comprises a first PT and a second PT, wherein the first PT has a first heavy-duty relay and is connected in series with the normally open auxiliary contact of the isolating switch 1QS of the first PT on the bus, and the second PT has a second heavy-duty relay and is connected in series with the normally open auxiliary contact of the isolating switch 2QS of the second PT on the bus; the signal output circuit on the secondary side of the first PT is connected to the signal output circuit on the secondary side of the second PT via the normally open auxiliary contact of the parallel relay; the signal output circuit on the secondary side of the first PT is serially provided with the normally open auxiliary contact of the first heavy-duty relay, and the signal output circuit on the secondary side of the second PT is serially provided with the normally open auxiliary contact of the second heavy-duty relay, It is characterized in that The device for preventing reverse power transmission when the single busbar segmented PT systems are connected in parallel comprises: A two-way locking switch, which is connected in series with the PT parallel transfer switch, the normally open contacts of the bus tie switch and the parallel relay on the bus, and the two-way locking switch includes a first branch and a second branch in parallel, the normally open auxiliary contacts of the isolating switch 1QS and the normally closed auxiliary contacts of the isolating switch 2QS are connected in series on the first branch, and the normally closed auxiliary contacts of the isolating switch 1QS and the normally open auxiliary contacts of the isolating switch 2QS are connected in series on the second branch.

6. The device for preventing reverse power transmission when single busbar segmented PT systems are connected in parallel according to claim 5, It is characterized in that The secondary busbar corresponding to the first PT is connected between the normally open auxiliary contact of the first heavy-duty relay and the normally open auxiliary contact of the parallel relay; The secondary busbar corresponding to the second PT is connected between the normally open auxiliary contact of the second heavy relay and the normally open auxiliary contact of the parallel relay.

7. The device for preventing reverse power transmission when single busbar segmented PT systems are connected in parallel according to claim 5, It is characterized in that A first miniature circuit breaker is provided between the signal output circuit of the secondary side of the first PT and the normally open auxiliary contact of the first heavy relay; A second miniature circuit breaker is provided between the signal output line of the secondary side of the second PT and the normally open auxiliary contact of the second heavy relay.

8. The device for preventing reverse power transmission when single busbar segmented PT systems are connected in parallel according to claim 5, It is characterized in that The single busbar segmented PT system further comprises: Sectional switch cabinet, which is connected to the busbar of section I and is provided with disconnector 3QS and circuit breaker 1QF arranged in series; A sectional isolating cabinet, which is connected to the II-section busbar and connected to the sectional switch cabinet, and the sectional isolating cabinet is provided with an isolating switch 4QS; The busbar switch includes an isolating switch 3QS, a circuit breaker 1QF and an isolating switch 4QS.

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