CN101916979B - Graded insulating neutral point integrated sealing clearance device of power transformer - Google Patents

Abstract

The invention discloses a power transformer graded insulation neutral point integrated sealing gap device, comprising a contact (1), a transmission mechanism (2), a motor (3), a zero-sequence current transformer (4) and a motor control circuit ( 5), characterized in that: a device control circuit (6) and an operation panel (7) are provided, and the control elements in the device control circuit (6) are provided externally through the operation panel (7); the contact (1), the transmission The mechanism (2), the motor (3), the motor control circuit (5), the device control circuit (6) and the operation panel (7) are sequentially connected, and the contact (1) directly passes through the center of the zero-sequence current transformer (4) , the zero-sequence current transformer (4) is connected to the operation panel (7) through a cable, and the motor control circuit (5) is connected to the operation panel (7). The invention has the functions of protecting the gap and the grounding switch, is packaged as a whole, has simple structure, accurate action and automatic operation.

Description

Power Transformer Graded Insulation Neutral Point Integrated Sealing Gap Device

technical field

The invention relates to the field of overvoltage protection for a neutral point of a power system transformer, in particular to an integrated sealing gap device for a graded insulation neutral point of a power transformer, which is suitable for overvoltage protection for an ungrounded neutral point of a transformer.

Background technique

The voltage in the power supply network is very high, and the neutral point is usually directly grounded. Due to the requirements of relay protection setting configuration and communication interference prevention, in order to limit the single-phase short-circuit current, some transformers use the neutral point ungrounded method. . In this mode of operation, the overvoltage at the neutral point will be caused by lightning strikes, single-phase grounding short-circuit faults, etc., and most of the transformers are graded insulation, so the overvoltage poses a great threat to the insulation of the neutral point, and protection must be provided for it. device to prevent accidents.

So far, the relevant research achievements at home and abroad mainly include the following two types.

1 bar clearance

State Power Corporation Document No. 589 "Twenty-five Key Requirements for Preventing Major Accidents in Electric Power Production" Chapter 17 "Preventing Grounding Grid Accidents", Section 17.9 stipulates: "In order to prevent the occurrence of isolated ungrounded systems in effective grounding systems And produce high power frequency overvoltage abnormal working conditions, the neutral point overvoltage of 110 ~ 220kV ungrounded transformers should adopt the rod gap protection method. The rod gap structure is simple, easy to maintain, and is generally installed outdoors. However, operating experience shows that when the system operates in an effective grounding mode and a single-phase ground fault occurs, factors such as inaccurate adjustment of the gap distance, poor technology of the gap contact, and the influence of the external environment will easily cause the gap to operate, which will change the zero-sequence impedance parameter of the system. Changes in zero-sequence current will cause relay protection to malfunction and cause unnecessary power outages.

2 Claw horn new compound gap

Peng Fei from Northeast Power Grid Co., Ltd., Chen Weijiang from Wuhan High Voltage Research Institute of State Grid, Li Chengrong from North China Electric Power University, etc., to solve the problem of inaccurate distance adjustment when installing rod-rod gap electrodes for neutral point protection of 110 and 220kV transformers. Due to inherent defects such as unstable discharge voltage, the technical conditions of the gap are determined according to the gap protection principle, the structure of the gap is designed, and a new type of protection gap for horns is developed. The new type of gap is mechanically supported by a composite insulator, and the horn electrodes are fixed at both ends of the insulator. The discharge electrode is separated from the arc electrode. It has good concentricity, accurate distance adjustment, convenient installation and debugging, strong ablation resistance, and stable discharge. advantage. However, because the gap is exposed to the outdoors, it is easy to be accidentally touched by foreign objects such as insects, birds or rain, causing a short circuit in the gap, resulting in a malfunction of the protection. At the same time, the electrodes fixed at both ends of the composite insulator occupy a large lateral area and can only be used as a protective gap.

Contents of the invention

In view of the above problems, the present invention proposes a power transformer graded insulation neutral point integrated sealing gap device.

The technical solution provided by the invention is a power transformer graded insulation neutral point integrated sealing gap device, contact (1), transmission mechanism (2), motor (3), through-type zero-sequence current transformer (4) and the motor control circuit (5), the device control circuit (6) and the operation panel (7) are provided, and the control elements in the device control circuit (6) are provided externally through the operation panel (7);

The contact (1), the transmission mechanism (2), the motor (3), the motor control circuit (5), the device control circuit (6) and the operation panel (7) are sequentially connected, and the contact (1) directly passes through the core Type zero-sequence current transformer (4) center, through-core type zero-sequence current transformer (4) joins with operation panel (7) by cable, and motor control circuit (5) joins with operation panel (7).

Moreover, the feedthrough zero-sequence current transformer (4) is provided with a feedthrough zero-sequence current transformer winding output terminal (4.1) and an auxiliary travel switch normally open node (4.2);

When the device is used as a protective gap, the output terminal (4.1) of the feedthrough zero-sequence current transformer winding is connected to the operation panel (7) through a cable; when the device is used as a grounding switch, the output terminal (4.1) of the feedthrough zero-sequence current transformer winding ( 4.1) The normally open node (4.2) of the auxiliary travel switch is automatically shorted, and there is no signal output.

Moreover, the device control circuit (6) is composed of air switch QF2 (8), interlock (9), stop button KA (10), thermal relay RJ (11), rotary switch SA (12), closing branch and The opening branch circuit is composed of the closing branch circuit, and the closing branch circuit includes a remote control closing switch (13), a closing button HA (14), a contactor JLC1 normally open contact (15), a contactor JLC1 energized coil (16), Contactor JLC2 normally closed contact (17), travel switch CK1 (18), the opening branch includes travel switch CK2 (19), contactor JLC1 normally closed contact (20), contactor JLC2 energized coil (21 ), contactor JLC2 normally open contact (24), remote control opening switch (22) and opening button TA (23);

Air switch QF2 (8), interlock (9), stop button KA (10), thermal relay RJ (11), and rotary switch SA (12) are connected in sequence, and rotary switch SA (12) is respectively connected to the closing branch Connected with the opening branch, the remote control closing switch (13) in the closing branch and the closing button HA (14) are linked to the contactor JLC1 normally open contact (15), and the contactor JLC1 normally open contact ( 15), contactor JLC1 energization coil (16), contactor JLC2 normally closed contact (17) and travel switch CK1 (18) are connected in sequence; the remote control opening switch (22) in the opening branch circuit is connected with the opening Button TA (23) linkage contactor JLC2 normally open contact (24), contactor JLC2 normally open contact (24), contactor JLC2 energized coil (21), contactor JLC1 normally closed contact (20), travel switch CK2 (19) are connected successively.

Moreover, the operation panel (7) is provided with a device control circuit power switch (26) connected with the device control circuit (6), a temperature and humidity controller (27) connected with the motor control circuit (5), and a terminal block ( 25), the control elements provided externally through the operation panel (7) in the device control circuit (6) include air switch QF2 (8), rotary switch SA (12), closing button HA (14), opening button TA ( 23), stop button KA (10).

Moreover, the contact (1) adopts the SN-1000A oil-less circuit breaker contact, and the discharge probability is 97.04%; Feedthrough zero-sequence current transformer with accuracy level 10P10.

The present invention has following advantage and effect:

1) The device has both gap and grounding switch functions: when the contact is disconnected, it can be used as a protective gap, with accurate action and small discharge dispersion; when the contact is closed, it can be used as a grounding switch, and can withstand 40kA/3s power frequency current .

2) Adopting the patented technology, the graded insulation neutral point of the transformer is integrated to seal the gap, the overall package, the temperature and humidity are controllable, the gap distance is accurate, and the stability of the discharge is guaranteed.

3) The contact of the present invention is the contact of a circuit breaker with less oil, which has good ablation resistance and improves the accuracy of gap action; the contact resistance is small, and the reliability of grounding is guaranteed when used as a grounding switch.

4) Using automation technology, the sealing gap can be electrically operated locally or remotely, and the operation is simple. After the operation is completed, the motor will automatically power off, effectively preventing misoperation.

5) The current measurement and control part of the device uses the auxiliary travel switch to automatically realize the short circuit of the secondary side of the through-type zero-sequence current transformer, which ensures the reliability of the zero-sequence protection of the transformer.

Description of drawings

Fig. 1 is a schematic diagram of the overall structure of the present invention;

Fig. 2 is the schematic diagram of the device control circuit of the embodiment of the present invention;

Fig. 3 is a schematic diagram of a feedthrough zero-sequence current transformer according to an embodiment of the present invention;

Fig. 4 is a schematic diagram of the operation panel of the embodiment of the present invention;

FIG. 5 is a schematic diagram of a package structure of an embodiment of the present invention.

Detailed ways

According to the industry custom, the power transformer graded insulation neutral point integrated sealing gap device provided by the present invention can also be called the power transformer graded insulation neutral point integrated sealing gap. The technical solution of the present invention will be described in detail below in conjunction with the drawings and embodiments.

Figure 1 shows the structural block diagram of the power transformer graded insulation neutral point integrated sealing gap device, and its connection relationship and functions are as follows.

The contact (1), the transmission mechanism (2), the motor (3), the motor control circuit (5), the device control circuit (6) and the operation panel (7) are sequentially connected, that is, the contact (1) and the transmission mechanism ( 2) connected, the motor (3) is connected with the transmission mechanism (2) and the motor control circuit (5) respectively, and the device control circuit (6) is connected with the motor control circuit (5) and the operation panel (7) respectively. The contact (1) directly passes through the center of the feed-through zero-sequence current transformer (4), and the feed-through zero-sequence current transformer (4) is connected to the operation panel (7) through a cable, and the motor control circuit (5) is connected to the The operation panel (7) is connected. Among them, the transmission mechanism (2) adopts the conventional screw drive mode, the motor control circuit (5) adopts the motor conventional control circuit, the contact (1), the motor (3), and the through-hole zero-sequence current transformer (4) can all be used Purchase conventional products. The center of the through-type zero-sequence current transformer has a round hole for the primary side to pass through the current measurement signal, and the contact (1) can directly pass through the round hole during implementation. The conventional circuit adopted by the motor control circuit (5) in the prior art is provided with an air switch QF1 and a motor M, and the work of the motor M is controlled by a thermal relay RJ, a contactor JLC1, and JLC2; the circuit also provides a temperature and humidity control function, It is realized by the condensation controller WSK and the heater DJR; QF1 is an air switch, which provides the working power of the motor and the temperature and humidity controller; RJ is a thermal relay, which will cut off the power supply of the motor when the motor fails and generates heat; the contactors JLC1, JLC2 It is a switch that can frequently close, carry and break the normal current and the specified overload current, and is used to control the closing circuit and the opening circuit respectively. The motor (3) and the corresponding motor control circuit (5) of the embodiment are products of Shenyang Dongmu Electric Manufacturing Co., Ltd., and the motor control circuit (5) can be set according to the product instructions. The present invention designs a precise device control circuit (6) structure, and the motor control circuit (5) responds to the operation of the control elements in the device control circuit (6) by the operator through the operation panel (7). The operation panel (7) is arranged in conjunction with the device control circuit (6). It is suggested that the operation panel (7) adopt the operation panel described in the utility model patent (application number 201020170035.7).

As shown in Figure 2, the device control circuit (6) of the embodiment consists of air switch QF2 (8), interlock (9), stop button KA (10), thermal relay RJ (11), rotary switch SA (12), Closing branch and opening branch, the closing branch includes remote control closing switch (13), closing button HA (14), contactor JLC1 normally open contact (15), contactor JLC1 energized Coil (16), contactor JLC2 normally closed contact (17), travel switch CK1 (18), the opening branch includes travel switch CK2 (19), contactor JLC1 normally closed contact (20), contactor JLC2 energizing coil (21), contactor JLC2 normally open contact (24), remote control opening switch (22) and opening button TA (23). The air switch QF2 (8) is the power supply of the control circuit provided by the device control circuit (6).

Air switch QF2 (8), interlock (9), stop button KA (10), thermal relay RJ (11), and rotary switch SA (12) are connected in sequence, and rotary switch SA (12) is respectively connected to the closing branch Connected with the opening branch, the remote control closing switch (13) in the closing branch and the closing button HA (14) are linked to the contactor JLC1 normally open contact (15), and the contactor JLC1 normally open contact ( 15), contactor JLC1 energization coil (16), contactor JLC2 normally closed contact (17) and travel switch CK1 (18) are connected in sequence; the remote control opening switch (22) in the opening branch circuit is connected with the opening Button TA (23) linkage contactor JLC2 normally open contact (24), contactor JLC2 normally open contact (24), contactor JLC2 energized coil (21), contactor JLC1 normally closed contact (20), travel switch CK2 (19) are connected successively. The so-called linkage means that after the remote control closing switch (13) or the closing button HA (14) is activated, the normally open contact (15) of the contactor JLC1 will also operate; the remote control opening switch (22) or the opening button TA After (23) action, contactor JLC2 normally open contact (24) also can action equally.

Its working principle is: close the air switch QF2 (8), turn on the power, select local or remote operation through the rotary switch SA (12), and press the closing button HA (14) or the opening button TA ( 23) Make the contactor JLC1 normally open contact (15) or the contactor JLC2 normally open contact (24) closed, and the remote control closing switch (13) or the remote control opening switch (22) can also be closed remotely, so that The device control circuit (6) is energized, the motor (3) rotates forward and reverse, drives the transmission mechanism (2) to work, and the transmission mechanism (2) controls the upward or downward movement of the contact (1); when the contact (1) reaches the designated position Finally, the travel switch CK1 (18) or CK2 (19) disconnects the device control circuit (6) power supply, and the contactor JLC1 energization coil (16) or contactor JLC2 energization coil (21) loses power, making the motor control circuit (5 ) automatically cuts off the power, and the motor (3) stops working. It is also possible to make the motor (3) emergency stop working by the stop button KA (10) on the operation panel (7).

As shown in Figure 3, when the power transformer graded insulation neutral point integrated gap device provided by the present invention is used for the protection gap, the output terminal (4.1) of the through-hole zero-sequence current transformer winding is connected to the operation panel (7) through a cable ; When the device is used as a grounding switch, the output terminal (4.1) of the feedthrough zero-sequence current transformer winding is automatically shorted through the normally open node (4.2) of the auxiliary travel switch, and there is no signal output.

A large number of power frequency and lightning voltage impulse discharge test results show that: under power frequency and lightning impulse overvoltage, the contact (1) can reliably operate when disconnected and used as a gap, and protect the neutral point insulation of the transformer graded insulation.

For 110kV transformer neutral point:

The contact (1) adopts SN-1000A oil-less circuit breaker contact, the discharge probability is 97.04%; the measurement part adopts the through-hole zero-sequence current mutual inductance with a primary side withstand current of 40kA/3s, a transformation ratio of 100/5, and an accuracy level of 10P10 The overall package adopts the package structure of a 110kV class power transformer graded insulation neutral point protection device (utility model patent application number 201020170035.7), forming an integrated sealing gap with a gap distance of 75-90mm. For the convenience of implementation, the packaging structure of the embodiment is provided, referring to Fig. 5, wherein the left side is a front view, and the right side is a rear view of the left side: the device includes a top junction plate (28), a silicone rubber composite insulating jacket (29), a grounding copper plate ( 30), column (31), operation box (35), base (32), position indicating window (33), handle (34) and column door (36). Its position and connection relationship are: top junction plate (28), silicone rubber composite insulation jacket (29), column (31) and base (32) are connected up and down in sequence; Grounding copper plate (30), position indication window (33), operation box (35) and column door (36); Handle (34) is respectively provided with on operation box (35) and column door (36). The functional parts are described as follows:

1. Top terminal block (28)

The top terminal block (28) is a metal circular plate on which terminals are arranged;

Its function is to act as an electrical connection.

2. Silicone rubber composite insulating jacket (29)

The silicone rubber composite insulating jacket (29) is a cylindrical jacket with umbrella skirts made of silicone rubber composite insulating material.

Its function is to play the role of electrical isolation.

3. Grounding bronze medal (30)

Grounding bronze medal (30) is a kind of copper block;

Its function is to act as an electrical ground.

4. Column (31)

Column (31) is a kind of metal square hollow column, and its length * width * height=0.3m * 0.3m * 2.5m.

Its function is to package related functional components, such as transmission mechanism (2), motor (3), through-hole zero-sequence current transformer (4), motor control circuit and (5) device control circuit (6).

5. Operation box (35)

Operation box (35) is a kind of metal square box, is provided with operation panel (7) on it;

Its function is to operate the relevant functional parts.

See Figure 4: Specifically, the operation panel is provided with a device control circuit power switch (26), air switch QF2 (8), temperature and humidity controller (27), rotary switch SA (12), closing button HA (14 ), opening button TA (23), stop button KA (10) and terminal block (25). The operator operates the device control circuit power switch (26) connected to the device control circuit (6), which can cut off or supply power to the device control circuit (6); the operator operates the motor control circuit ( 5) The connected temperature and humidity controller (27) controls the condensation controller WSK and the heater DJR. The control elements provided externally through the operation panel (7) in the device control circuit (6) include air switch QF2 (8), rotary switch SA (12), closing button HA (14), opening button TA (23), The stop button KA (10) can be operated by the operator and affected respectively. Through the terminal block (25), it is convenient to provide the electrical connection of each component, to connect the power supply and to lead out the signal. To the control room to collect signals. Specifically, when the device is used for protection gaps, the output terminal (4.1) of the feedthrough zero-sequence current transformer winding is connected to the terminal block (25) through a cable.

6. Base (32)

The base (32) is a metal plate;

Its function is to play the role of installation and fixation.

7. Position indication window (33)

The position indication window (33) is a kind of transparent plexiglass window;

Its function is to facilitate the observation of the opening and closing status of the protection device.

8. Handle(34)

Handle (34) is a kind of metal handle with lock commonly used

Its function is to lock the operation box (35) and the column door (36) to prevent misoperation by unrelated personnel.

9. Column door (36)

Column door (36) is a kind of metal door commonly used;

Its function is to play a security role.

In order to reduce the footprint of the device, make the device look beautiful, and achieve the purpose of convenient operation, the embodiment encapsulates the electrical operation and control part in the column (31), and the column (31) is installed on a silicone rubber composite insulation Below the jacket (29), the device occupies an area of only 0.09m ² . A handle (34) with a lock has been installed at the box door and the column door (36) of the operation box (35), which improves safety and prevents misoperation by unrelated personnel.

Embodiment Connect the neutral point lead-out line of the transformer to the top junction plate (28) during normal operation, and ground the copper plate (30) to the ground; the device control circuit power switch (26) and air switch QF2 on the panel of the operation box (35) (8) are all in the closed state, and the temperature and humidity controller (27) is in the working state at this time, which can automatically detect and adjust the temperature and humidity of the air inside the device.

When operating remotely, turn the rotary switch SA (12) to "remote", and send an action signal from a remote place, and the device will perform corresponding opening and closing or stop operations.

When operating locally, turn the rotary switch SA (12) to "local", press the closing button HA (14) on the operation panel, and the protection gap of the device will be closed under the control of the device control circuit (6), from The position indicating window (33) can see that the position of the pointer points to the closing position from the opening position. After reaching the designated position, the motor control circuit (5) and the device control circuit (6) are automatically powered off, and the operation ends. If the stop button KA (10) is pressed during the closing process, the closing action will stop immediately.

When operating locally, turn the rotary switch SA (12) to "local", press the opening button TA (23) on the operation panel, and the protection gap of the device will be closed under the control of the device control circuit (6), from The position indication window (33) can see that the pointer position points to the opening position from the closing position. After reaching the designated position, the motor control circuit (5) and the device control circuit (6) are automatically powered off, and the operation ends. If the stop button KA (10) is pressed during the opening process, the opening action will stop immediately.

Claims (5)

1. A power transformer graded insulation neutral point integrated sealing gap device, including contacts (1), transmission mechanism (2), motor (3), through-type zero-sequence current transformer (4) and motor control circuit (5), characterized in that: a device control circuit (6) and an operation panel (7) are provided, and the control elements in the device control circuit (6) are provided externally through the operation panel (7); The contact (1), the transmission mechanism (2), the motor (3), the motor control circuit (5), the device control circuit (6) and the operation panel (7) are sequentially connected, and the contact (1) directly passes through the center Type zero-sequence current transformer (4) center, the through-type zero-sequence current transformer (4) is connected with the operation panel (7) through the cable, and the motor control circuit (5) is connected with the operation panel (7). 2. The power transformer graded insulation neutral point integrated sealing gap device according to claim 1, characterized in that: the feed-through zero-sequence current transformer (4) is provided with a feed-through zero-sequence current transformer winding Output terminal (4.1) and auxiliary limit switch normally open node (4.2); When the device is used as a protective gap, the output terminal (4.1) of the feedthrough zero-sequence current transformer winding is connected to the operation panel (7) through a cable; when the device is used as a grounding switch, the output terminal (4.1) of the feedthrough zero-sequence current transformer winding ( 4.1) The normally open node (4.2) of the auxiliary travel switch is automatically shorted, and there is no signal output. 3. The power transformer graded insulation neutral point integrated sealing gap device according to claim 1 or 2, characterized in that: the device control circuit (6) consists of air switch QF2 (8), interlock (9), Stop button KA (10), thermal relay RJ (11), rotary switch SA (12), closing branch and opening branch, the closing branch includes remote control closing switch (13), closing Button HA (14), contactor JLC1 normally open contact (15), contactor JLC1 energized coil (16), contactor JLC2 normally closed contact (17), travel switch CK1 (18), the opening branch Including travel switch CK2 (19), contactor JLC1 normally closed contact (20), contactor JLC2 energized coil (21), contactor JLC2 normally open contact (24), remote control opening switch (22) and opening button ta(23); Air switch QF2 (8), interlock (9), stop button KA (10), thermal relay RJ (11), and rotary switch SA (12) are connected in sequence, and rotary switch SA (12) is respectively connected to the closing branch Connected with the opening branch, the remote control closing switch (13) in the closing branch and the closing button HA (14) are linked with the contactor JLC1 normally open contact (15), and the contactor JLC1 normally open contact ( 15), contactor JLC1 energizing coil (16), contactor JLC2 normally closed contact (17) and travel switch CK1 (18) are connected in sequence; the remote control opening switch (22) in the opening branch circuit and the opening Button TA (23) linkage contactor JLC2 normally open contact (24), contactor JLC2 normally open contact (24), contactor JLC2 energized coil (21), contactor JLC1 normally closed contact (20), travel switch CK2 (19) are connected successively. 4. The power transformer graded insulation neutral point integrated sealing gap device according to claim 3, characterized in that: the operation panel (7) is provided with a device control circuit power switch connected to the device control circuit (6) ( 26), the temperature and humidity controller (27) connected to the motor control circuit (5), and the terminal block (25), the control elements provided externally through the operation panel (7) in the device control circuit (6) include air switch QF2 (8), rotary switch SA (12), closing button HA (14), opening button TA (23), stop button KA (10). 5. The power transformer graded insulation neutral point integrated sealing gap device according to claim 1 or 2, characterized in that: The contact (1) adopts SN-1000A oil-less circuit breaker contact, and the discharge probability is 97.04%; the through-hole zero-sequence current transformer (4) adopts a primary side withstand current of 40kA/3s, a transformation ratio of 100/5 and an accuracy level 10P10 feedthrough zero-sequence current transformer.

Images