CN210092867U - Converter station auxiliary device and converter station - Google Patents

Abstract

The application relates to a converter station auxiliary device and a converter station, which comprise a control protection device, a first branch circuit and a second branch circuit, wherein the first branch circuit and the second branch circuit are connected in parallel; the first end of the first branch circuit and the second end of the second branch circuit after being connected in parallel are connected with a neutral point of a converter station connecting transformer, and the second end of the first branch circuit is grounded; the first branch comprises a first circuit breaker; the second branch comprises a first load; when a single-pole ground fault occurs, fault current forms a fault loop through the first load. Due to the fact that the first load is large, the short-circuit current flowing in the single-pole ground fault is small, and the condition that the converter station can continuously operate for a period of time under the condition of the single-pole ground fault can be met, so that power supply reliability of the system is improved. The control protection device is used for outputting a closing signal to the first circuit breaker when the fault current of the second branch circuit is detected; the first circuit breaker is switched to a closed state after receiving the closing signal, so that the short-circuit current is increased, and the protection device is conveniently controlled to position the fault branch and the fault position.

Description

Converter station auxiliary device and converter station

technical field

The present application relates to the technical field of electrical automation, and in particular, to an auxiliary device of a converter station and a converter station.

Background technique

In recent years, the development of flexible DC technology has become an important direction for the development of power grid technology. Research and demonstration projects of related flexible DC projects have been carried out in the distribution network. DC will become a development trend, especially in substation and distribution. There is great potential in the field, and in the future, the power grid will surely develop into a business form with coexistence of AC and DC. An important field in the flexible DC technology of the distribution network is the electrical main circuit design of the flexible DC converter station suitable for the characteristics of the distribution network. The main electrical circuit should be able to meet the functional requirements of switching on and off the electrical circuit during normal operation. It should also be able to quickly remove the fault point and protect the electrical equipment from damage during the fault process.

During the implementation process, the inventor found that there are at least the following problems in the traditional technology: in the traditional method for locating the fault location, the fault current is small and the fault location is difficult.

Utility model content

Based on this, it is necessary to provide a converter station auxiliary device and a converter station that can increase the fault current in view of the above technical problems.

In order to achieve the above purpose, on the one hand, an embodiment of the present invention provides an auxiliary device for a converter station, including a control and protection device, and a first branch and a second branch connected in parallel;

After the first branch and the second branch are connected in parallel, the first end is connected to the neutral point of the converter station and the transformer, and the second end is grounded; the first branch includes the first circuit breaker; the second branch includes the first load;

The control and protection device is used for transmitting a closing signal to the first circuit breaker when the fault current of the second branch is detected; when the first circuit breaker receives the closing signal, it switches to a closed state.

In one of the embodiments, a second load is further included; the second load is connected in series with the first branch.

In one of the embodiments, the first load is a first resistor, and the second load is a second resistor; the resistance value of the first resistor is greater than the resistance value of the second resistor.

In one embodiment, the first resistor is a resistor with a resistance value greater than 1000Ω and less than 10000Ω, and the second resistor is a resistor with a resistance value greater than 100Ω and less than 1000Ω.

In one of the embodiments, a first current transformer is further included; the first current transformer is connected in series between the second end and the ground after the first branch and the second branch are connected in parallel.

In one of the embodiments, a surge arrester is also included; one end of the surge arrester is connected to the neutral point, and the other end is grounded.

On the other hand, the embodiment of the present invention also provides a converter station including a converter valve, a connecting transformer and the auxiliary device of the converter station according to any one of the above;

The high-voltage side of the connecting transformer is used to connect the AC power supply, and the low-voltage side is connected to the converter valve; the upper bridge arm of the converter valve is used to connect the DC positive line, and the lower bridge arm of the converter valve is used to connect the DC negative line.

In one of the embodiments, it also includes a station electricity branch; the first end of the station electricity branch is connected to the high-voltage side of the connection transformer, and the second end of the station electricity branch is used to connect external lines;

The power branch of the station includes a disconnecting device and a station transformer connected in series; one end of the disconnecting device is connected to the high voltage side of the station transformer, the other end is connected to the high voltage side of the connection transformer, and the low voltage side of the station transformer is connected to the external line.

In one of the embodiments, the breaking device includes a second circuit breaker and an isolating switch; the second circuit breaker and the isolating switch are connected in series in the station power branch.

In one of the embodiments, the station power branch further includes a second current transformer; one end of the second current transformer is connected to the high voltage side of the station transformer, and the other end is connected to the breaking device.

A technical scheme in the above-mentioned technical scheme has the following advantages and beneficial effects:

The auxiliary device of the converter station of the present application includes a control and protection device, and a first branch circuit and a second branch circuit connected in parallel; The neutral point, the second end is grounded; the first branch circuit includes a first circuit breaker; the second branch circuit includes a first load; when a single-pole grounding fault occurs, the fault current forms a fault circuit through the first load. Because the first load is large, the short-circuit current flowing through the single-pole grounding fault is small, which can meet the requirement that the converter station can continue to operate for a period of time under the single-pole grounding fault, so as to provide the reliability of the power supply of the system. The control and protection device is used for outputting a closing signal to the first circuit breaker when the fault current of the second branch is detected; the first circuit breaker switches to a closed state after receiving the closing signal. Because the short-circuit current is small, it is not conducive to the control and protection device to judge the fault location. Therefore, after the fault occurs, if the system does not need to continue to operate, the first circuit breaker will be automatically closed and the first resistor will be short-circuited, so that the short-circuit current increases. Large, easy to control and protect the device to locate the fault branch and fault location.

Description of drawings

The above and other objects, features and advantages of the present application will become more apparent from a more detailed description of the preferred embodiments of the present application shown in the accompanying drawings. The same reference numerals refer to the same parts throughout the drawings, and the drawings are not intentionally drawn to scale, the emphasis being placed on illustrating the subject matter of the present application.

FIG. 1 is a block diagram of a first schematic circuit structure of an auxiliary device of a converter station in an embodiment;

FIG. 2 is a block diagram of a second schematic circuit structure of an auxiliary device of a converter station in an embodiment;

3 is a block diagram of a third schematic circuit structure of an auxiliary device of a converter station in an embodiment;

FIG. 4 is a fourth schematic block diagram of the circuit structure of the auxiliary device of the converter station in one embodiment;

5 is a block diagram of a first schematic circuit structure of a converter station in an embodiment;

6 is a block diagram of a second schematic circuit structure of a converter station in one embodiment;

7 is a schematic block diagram of a circuit structure of a breaking device in an embodiment;

FIG. 8 is a schematic block diagram of the circuit structure of a station power branch in an embodiment.

Detailed ways

In order to facilitate understanding of the present application, the present application will be described more fully below with reference to the related drawings. Preferred embodiments of the present application are shown in the accompanying drawings. However, the application may be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete.

It should be noted that when an element is referred to as being "connected" to another element, it can be directly connected to and integrated with the other element, or intervening elements may also be present. The terms "high side", "low side", "one end", "the other end" and similar expressions are used herein for illustrative purposes only.

Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the technical field to which this application belongs. The terms used in the specification of the present application are for the purpose of describing specific embodiments only, and are not intended to limit the present application. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items.

In one embodiment, as shown in FIG. 1, an auxiliary device for a converter station includes a control and protection device 10, and a first branch 20 and a second branch 30 connected in parallel;

After the first branch 20 and the second branch 30 are connected in parallel, the first end is connected to the neutral point of the connecting transformer of the converter station, and the second end is grounded; the first branch 20 includes the first circuit breaker CB1; the second branch 30 including a first load 301;

The control and protection device 10 is configured to transmit a closing signal to the first circuit breaker CB1 when the fault current of the second branch 30 is detected; when the first circuit breaker CB1 receives the closing signal, it switches to a closed state.

Among them, the control and protection device 10 is the secondary equipment of the converter station, and its function is to monitor and check the abnormality of the line operation of the converter station, and to control the equipment in the converter station. The neutral point is a common contact where the head ends (or tail ends) of the three-phase coils are connected together when the connecting transformer is star-connected. The first load 301 can be any component with resistance value.

The first branch 20 is used to increase the current in the loop, and the second branch 30 is used to limit the current in the loop. The first branch 20 includes a first circuit breaker CB1, and the second branch 30 includes a first load 301. When the line of the converter station is working normally, the first circuit breaker CB1 is in an open state. When a single-pole grounding fault occurs, the fault current passes through the first load to form a fault loop. Because the resistance of the first load 301 is relatively large, the current limiting effect is achieved. Therefore, in the event of a single-pole grounding fault, the short-circuit current flowing through is larger than that of the first load. It is small and can continue to operate for a period of time under the condition of single-pole grounding fault of the converter station. The control and protection device 10 can detect the fault current of the second branch 30. Specifically, the fault current can be detected by any technical means in the field. When the fault current of the second branch 30 is detected, it can control to close the first branch. The circuit breaker CB1 short-circuits the first load 301, thereby increasing the current in the circuit. In a specific example, the first circuit breaker CB1 can be a relay, one end of the coil of the relay is grounded, and the other end is connected to the control and protection device 10 , and the moving contact and the static contact of the relay are connected to the first branch. When the device 10 detects the fault current of the second branch 30, it outputs a high-level signal to the coil, and makes the movable contact and the static contact contact by magnetic force, so that the first branch is turned on and the second branch is connected. Short-circuit to achieve the effect of increasing the current, so as to facilitate the control and protection device 10 to locate and check the faulty branch and fault location.

The auxiliary device of the converter station includes a control and protection device, and a first branch circuit and a second branch circuit connected in parallel; the first end of the parallel connection of the first branch circuit and the second branch circuit is connected to the neutral point of the connection transformer of the converter station. point, the second end is grounded; the first branch circuit includes the first circuit breaker; the second branch circuit includes the first load; when a single-pole grounding fault occurs, the fault current forms a fault circuit through the first load. Because the first load is large, the short-circuit current flowing through the single-pole grounding fault is small, which can meet the requirement that the converter station can continue to operate for a period of time under the single-pole grounding fault, so as to provide the reliability of the power supply of the system. The control and protection device is used for outputting a closing signal to the first circuit breaker when the fault current of the second branch is detected; the first circuit breaker switches to a closed state after receiving the closing signal. Because the short-circuit current is small, it is not conducive to the control and protection device to judge the fault location. Therefore, after the fault occurs, if the system does not need to continue to operate, the first circuit breaker will be automatically closed and the first resistor will be short-circuited, so that the short-circuit current increases. Large, easy to control and protect the device to locate the fault branch and fault location.

In one of the embodiments, as shown in FIG. 2 , a second load 203 is further included; the second load is connected to the first branch 20 in series.

Wherein, the second load 203 can be any component with resistance value; the second load is connected in series in the first branch. The first branch 20 is connected in series with the second load 203. When the control and protection device 10 detects the fault current, the resistance of the parallel equivalent resistance can be reduced when the first branch 20 is turned on. In the case of increasing the current, the current size of the control loop is not too large to ensure the safety of the components.

In one embodiment, the first load 301 is a first resistor, and the second load 203 is a second resistor; the resistance value of the first resistor is greater than the resistance value of the second resistor.

Specifically, the first resistor is used as the first load, and the second resistor is used as the second load. The first resistor is used to limit the current in the loop, and the second resistor is used to connect in parallel with the first resistor in the case of a single-pole ground fault, thereby reducing the parallel equivalent resistance value and increasing the current.

Wherein, as a preferred embodiment, the resistance value of the first resistor is greater than 1000Ω and less than 10000Ω, and the resistance value of the second resistor is greater than 100Ω and less than 1000Ω. Considering the actual voltage of the converter station, the resistance range of the first resistor used for current limiting is greater than 1000Ω and less than 10000Ω, which can achieve a reasonable current limiting effect. The resistance range of the second resistor is greater than 100Ω and less than 1000Ω. During fault detection, the equivalent resistance value after parallel connection makes the increased current more reasonable, which is easy to troubleshoot and locate the fault.

In one of the embodiments, as shown in FIG. 3 , a first current transformer CT1 is further included; the first current transformer CT1 is connected in series between the second end and the ground after the first branch 20 and the second branch 30 are connected in parallel. between.

Among them, the current transformer 40 is used to detect the current value of the loop, and can provide the staff with the current value of the current loop for use in relay protection and measurement and metering.

In one embodiment, as shown in FIG. 4 , a surge arrester 50 is further included; one end of the surge arrester 50 is connected to the neutral point, and the other end is grounded. The arrester 50 plays the role of voltage protection in the auxiliary device of the converter station.

In one embodiment, as shown in FIG. 5, a converter station is provided, comprising a converter valve 60, a coupling transformer 70 and a converter station auxiliary device 80 as described above;

The high voltage side of the connection transformer 70 is used to connect the AC power supply, and the low voltage side is connected to the converter valve; the upper bridge arm of the converter valve 60 is used to connect the DC positive line, and the lower bridge arm of the converter valve 60 is used to connect the DC negative line.

Among them, the converter valve 60 is used to convert alternating current into direct current.

Specifically, the AC power source outputs the initial AC current to the connection transformer 70; the connection transformer 70 converts the initial AC current into the current AC current of the corresponding voltage level, and transmits the current AC current to the converter valve; the converter valve 60 converts the current AC current The current is converted into positive DC current and negative DC current, and the positive DC current is output to the DC positive line through the upper bridge arm, and the negative DC current is output to the DC negative line through the lower bridge arm.

The control and protection device 10 is used to detect whether a single-pole grounding fault occurs in the loop. Further, when a single-pole grounding fault occurs, the second branch circuit 30 will generate a fault current. When the control and protection device 10 detects the fault current of the second branch 30, it outputs a closing signal to the first circuit breaker CB1.

The above converter station includes a converter valve, a connecting transformer and an auxiliary device for the converter station as described above; the high-voltage side of the connecting transformer is used to connect the AC power supply, and the low-voltage side is connected to the converter valve; the upper bridge arm of the converter valve It is used to connect the DC positive line, and the lower arm of the converter valve is used to connect the DC negative line; the control and protection device is used to output a closing signal to the first circuit breaker when the fault current of the second branch is detected; the first circuit breaker The device switches to the closed state after receiving the closing signal. Since the short-circuit current is small, it is not conducive to the control and protection device to judge the fault location. Therefore, after a fault occurs, if the system does not need to continue to operate, the first circuit breaker will be automatically closed, thereby increasing the short-circuit current and facilitating the positioning of the control and protection device. Fault branch and fault location.

In one of the embodiments, as shown in FIG. 6 , it also includes a station electricity branch 90 ; the first end of the station electricity branch is connected to the first end of the connection transformer 70 , and the second end of the station electricity branch 90 for connecting external lines;

The station electricity branch 90 includes a disconnecting device 901 and a station transformer 903 connected in series; one end of the disconnecting device 901 is connected to the high voltage side of the station transformer, the other end is connected to the high voltage side of the connecting transformer, and the low voltage side of the station transformer is connected external line.

Among them, the station power branch 90 is used to provide power to the converter station equipment, the breaking device 901 is used to isolate the station power branch and the main line, and the station transformer 903 is used to adjust the input voltage.

Specifically, the station electrical branch 90 includes a breaking device 901 and a station transformer 903 . When the breaking device 901 is closed, the station transformer 903 starts to work, and outputs the voltage converted by the station transformer to the outside. When the breaking device 901 is turned off, the station transformer 903 stops working.

The above-mentioned converter station includes a branch circuit for power consumption of the station, so that the converter station provided by the present application does not require external power supply, thereby reducing the cost caused by laying external power supply lines.

In one embodiment, as shown in FIG. 7 , the breaking device 901 includes a second circuit breaker CB2 and a disconnecting switch DS1; the second circuit breaker CB2 and the disconnecting switch DS1 are connected in series in the station electrical branch.

Specifically, the breaking device 901 includes a second circuit breaker CB2 and an isolating switch DS1, the second circuit breaker CB2 is used to disconnect the line, and the isolating switch DS1 is used to open the line contacts, through the second circuit breaker CB2 and the isolating switch DS1, can effectively ensure the disconnection of the line.

In one of the embodiments, as shown in FIG. 8 , the station power branch 90 further includes a second current transformer CT2; one end of the second current transformer CT2 is connected to the high voltage side of the station transformer, and the other end is connected to the breaking device 901.

Among them, the second current transformer CT2 is used to detect the current value of the loop, and can provide the staff with the current value of the current loop for relay protection and measurement and metering. In a specific example, the ground knife ES1 is set up, connected to the high voltage side of the station transformer 903, to provide power to the station transformer 903, and the low voltage side of the station transformer 903 outputs 380V AC to provide power to the entire station equipment. The second circuit breaker CB2 and the isolating switch DS1 are used to switch on and off the power branch of the operation station. The ground knife ES1 is closed for maintenance.

The technical features of the above embodiments can be combined arbitrarily. In order to make the description simple, all possible combinations of the technical features in the above embodiments are not described. However, as long as there is no contradiction in the combination of these technical features It is considered to be the range described in this specification.

The above examples only represent several embodiments of the present application, and the descriptions thereof are relatively specific and detailed, but should not be construed as a limitation on the scope of the utility model patent. It should be pointed out that for those skilled in the art, without departing from the concept of the present application, several modifications and improvements can be made, which all belong to the protection scope of the present application. Therefore, the protection scope of the patent for this utility model shall be subject to the appended claims.

Claims (10)

1. A converter station auxiliary device, characterized in that it comprises a control protection device, and a first branch and a second branch connected in parallel; The first end of the parallel connection of the first branch and the second branch is connected to the neutral point of the connecting transformer of the converter station, and the second end is grounded; the first branch includes a first circuit breaker; the first The second branch includes the first load; The control and protection device is used to transmit a closing signal to the first circuit breaker when the fault current of the second branch is detected; when the first circuit breaker receives the closing signal, it switches to a closed state . 2. The converter station auxiliary device according to claim 1, characterized in that, further comprising a second load; The second load is connected in series with the first branch. 3 . The auxiliary device of the converter station according to claim 2 , wherein the first load is a first resistor, and the second load is a second resistor; and the resistance value of the first resistor is greater than that of the The resistance value of the second resistor. 4 . The auxiliary device of the converter station according to claim 3 , wherein the first resistor is a resistor with a resistance value greater than 1000Ω and less than 10000Ω, and the second resistor is a resistor with a resistance value greater than 100Ω and less than 1000Ω . 5. The auxiliary device of the converter station according to claim 1, characterized in that, further comprising a first current transformer; The first current transformer is connected in series between the second end and the ground after the first branch and the second branch are connected in parallel. 6. The converter station auxiliary device according to claim 1, characterized in that, further comprising a lightning arrester; One end of the arrester is connected to the neutral point, and the other end is grounded. 7. A converter station, characterized in that it comprises a converter valve, a connection transformer and the converter station auxiliary device according to any one of claims 1 to 6; The high-voltage side of the connecting transformer is used to connect the AC power supply, and the low-voltage side is connected to the converter valve; the upper bridge arm of the converter valve is used to connect the DC positive line, and the lower bridge arm of the converter valve is used to connect DC negative line. 8 . The converter station according to claim 7 , further comprising a station electricity branch; the first end of the station electricity branch is connected to the high voltage side of the connection transformer, and the station electricity The second end of the branch is used to connect external lines; The power branch for the station includes a disconnecting device and a transformer for the station connected in series; one end of the disconnecting device is connected to the high-voltage side of the transformer for the station, and the other end is connected to the high-voltage side of the transformer for the station. The low voltage side of the connection to the external line. 9. The converter station according to claim 8, wherein the breaking device comprises a second circuit breaker and an isolating switch; The second circuit breaker and the isolating switch are connected in series in the power branch of the station. 10 . The converter station according to claim 8 , wherein the power branch of the station further comprises a second current transformer; 10 . One end of the current transformer is connected to the high voltage side of the station transformer, and the other end is connected to the breaking device.

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