Converter station auxiliary device, method and converter station

Abstract

The present application relates to a converter station auxiliary device, method and converter station, including a control protection device, and a first branch and a second branch connected in parallel; the first end of the first branch and the second branch after being connected in parallel is connected to the neutral point of the converter station connection transformer, and the second end is grounded; the first branch includes a first circuit breaker; the second branch includes a first load; when a single-pole grounding fault occurs, the fault current forms a fault loop through the first load. Because the first load is large, the short-circuit current flowing through is small in the case of a single-pole grounding fault, which can meet the requirement that the converter station can continue to operate for a period of time in the case of a single-pole grounding fault, so as to provide power supply reliability of the system. The control 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 switches to a closed state after receiving the closing signal, thereby increasing the short-circuit current, which facilitates the control protection device to locate the fault branch and the fault position.

Description

Technical Field

[0001] The present application relates to the field of electrical automation technology, and in particular to a converter station auxiliary device, method and converter station. Background Art

[0002] In recent years, the development of flexible DC technology has become an important direction for the development of power grid technology. Scientific 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 the field of substation and distribution. In the future, the power grid will surely develop into a coexistence of AC and DC. An important field in the flexible DC technology of the distribution network is the design of the main electrical circuit 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 the input and removal of the electrical circuit and the mode conversion during normal operation. It should also be able to quickly remove the fault point during the fault process to protect the electrical equipment from damage.

[0003] During the implementation process, the inventors found that there are at least the following problems in the conventional technology: in the conventional method for locating the fault position, the fault current is relatively small and the fault location is relatively difficult. Summary of the invention

[0004] Based on this, it is necessary to provide a converter station auxiliary device, method and converter station that can increase the fault current in order to solve the above technical problems.

[0005] In order to achieve the above-mentioned object, on the one hand, an embodiment of the present invention provides a converter station auxiliary device, including a control protection device, and a first branch and a second branch connected in parallel;

[0006] The first end of the first branch and the second branch connected in parallel is connected to the neutral point of the converter station connection transformer, and the second end is grounded; the first branch includes a first circuit breaker; the second branch includes a first load;

[0007] The control protection device is used to output a closing signal to the first circuit breaker when a fault current in the second branch is detected; the first circuit breaker switches to a closed state after receiving the closing signal.

[0008] In one of the embodiments, a second load is further included; the second load is connected in series with the first branch.

[0009] In one embodiment, 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.

[0010] In one 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.

[0011] In one of the embodiments, it further includes a first current transformer; the first current transformer is connected in series between the second end of the first branch and the second branch connected in parallel and the ground.

[0012] In one of the embodiments, a lightning arrester is also included; one end of the lightning arrester is connected to the neutral point, and the other end is grounded.

[0013] The embodiment of the present invention further provides a converter station auxiliary method, comprising the following steps:

[0014] Detect whether there is a fault current in the second branch; wherein the second branch is connected in parallel with the first branch, the first end of the first branch and the second branch connected in parallel is connected to the neutral point of the transformer of the converter station, and the second end is grounded; the first branch includes a first circuit breaker; the second branch includes a first load;

[0015] If so, a closing signal is output to the first circuit breaker; the closing signal is used to control the first circuit breaker to close.

[0016] On the other hand, an embodiment of the present invention further provides a converter station, comprising a converter valve, a connection transformer and a converter station auxiliary device as described above;

[0017] The high voltage side of the connection transformer is used to connect to 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 to the DC positive line, and the lower bridge arm of the converter valve is used to connect to the DC negative line.

[0018] In one embodiment, it further includes a station power branch; a first end of the station power branch is connected to the high voltage side of the transformer, and a second end of the station power branch is used to connect to an external line;

[0019] The station power branch circuit 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, and 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 to the external line.

[0020] In one embodiment, the breaking device includes a second circuit breaker and an isolating switch; the second circuit breaker and the isolating switch are connected in series to the station power branch.

[0021] One of the above technical solutions has the following advantages and beneficial effects:

[0022] The converter station auxiliary device of the present application includes a control protection device, and a first branch and a second branch connected in parallel; the first end of the first branch and the second branch after being connected in parallel is connected to the neutral point of the converter station connection transformer, and the second end is grounded; the first branch includes a first circuit breaker; the second branch includes a first load; when a single-pole grounding fault occurs, the fault current forms a fault loop through the first load. Because the first load is large, the short-circuit current flowing through is small when a single-pole grounding fault occurs, which can meet the requirement that the converter station can continue to operate for a period of time under the condition of a single-pole grounding fault, so as to provide power supply reliability of the system. The control protection device is used to output a closing signal to the first circuit breaker when detecting the fault current of the second branch; the first circuit breaker switches to a closed state after receiving the closing signal. Since the short-circuit current is small, it is not conducive to the control 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 to short-circuit the first resistor, thereby increasing the short-circuit current, which is convenient for the control protection device to locate the fault branch and the fault location. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The above and other purposes, features and advantages of the present application will become clearer through a more specific description of the preferred embodiments of the present application shown in the accompanying drawings. The same reference numerals indicate the same parts in all the accompanying drawings, and the drawings are not deliberately scaled to the actual size, and the focus is on illustrating the subject matter of the present application.

[0024] Figure 1 is a first schematic circuit structure block diagram of a converter station auxiliary device in one embodiment;

[0025] Figure 2 is a second schematic circuit structure block diagram of a converter station auxiliary device in one embodiment;

[0026] Figure 3 is a third schematic circuit structure block diagram of a converter station auxiliary device in one embodiment;

[0027] Figure 4 is a fourth schematic circuit structure block diagram of a converter station auxiliary device in one embodiment;

[0028] Figure 5 is a schematic flowchart of a converter station auxiliary method in an embodiment;

[0029] Figure 6 is a first schematic circuit structure block diagram of a converter station in an embodiment;

[0030] Figure 7 is a second schematic circuit structure block diagram of a converter station in one embodiment;

[0031] Figure 8is a schematic circuit structure block diagram of a breaking device in one embodiment;

[0032] Fig. 9 is a schematic circuit structure block diagram of a station power branch circuit in an embodiment;

[0033] Fig.10 FIG. 4 is a third schematic circuit structure block diagram of a converter station in an embodiment. DETAILED DESCRIPTION

[0034] In order to facilitate understanding of the present application, the present application will be described more fully below with reference to the relevant drawings. The preferred embodiments of the present application are given in the drawings. However, the present application can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present application more thorough and comprehensive.

[0035] It should be noted that when an element is considered to be "connected" to another element, it may be directly connected to the other element and integrated therewith, or there may be an intermediate element at the same time. The terms "high pressure side", "low pressure side", "one end", "the other end" and similar expressions used herein are for illustrative purposes only.

[0036] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which this application belongs. The terms used in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application. The term "and / or" used herein includes any and all combinations of one or more of the related listed items.

[0037] In one embodiment, Figure 1 As shown, a converter station auxiliary device includes a control protection device 10, and a first branch 20 and a second branch 30 connected in parallel;

[0038] The first end of the first branch 20 and the second branch 30 connected in parallel is connected to the neutral point of the converter station connection transformer, and the second end is grounded; the first branch 20 includes a first circuit breaker CB1; the second branch 30 includes a first load 301;

[0039] The control protection device 10 is used to output a closing signal to the first circuit breaker CB1 when a fault current in the second branch 30 is detected; the first circuit breaker switches to a closed state after receiving the closing signal.

[0040] The control and protection device 10 is a secondary device of the converter station, which is used to monitor and troubleshoot abnormalities in the operation of the converter station line. The neutral point is a common connection point where the head ends (or tail ends) of the three-phase coils are connected together when the connection transformer is star-connected. The first load 301 can be any component with resistance.

[0041] 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 a disconnected 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 large, the current limiting effect is achieved. Therefore, when a single-pole grounding fault occurs, the short-circuit current flowing through is small, which can meet the requirement that the converter station can continue to operate for a period of time under the condition of a single-pole grounding fault. The control 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 art. When the fault current of the second branch 30 is detected, a closing signal can be output to the first circuit breaker CB1, thereby closing the first circuit breaker CB1, so that the first load 301 is short-circuited, thereby achieving the effect of increasing the current in the loop. In a specific example, the first circuit breaker can be a relay. When the control protection device 10 detects the fault current of the second branch 30, the electromagnet is energized, and the contacts of the circuit are brought into contact through magnetic force, thereby making the first branch conductive and short-circuiting the second branch to achieve the effect of increasing the current, so as to facilitate the control protection device 10 to locate and troubleshoot the faulty branch and fault location.

[0042] The converter station auxiliary device includes a control protection device, and a first branch and a second branch connected in parallel; the first end of the first branch and the second branch connected in parallel is connected to the neutral point of the converter station connection transformer, and the second end is grounded; the first branch includes a first circuit breaker; the second branch includes a first load; when a single-pole grounding fault occurs, the fault current forms a fault loop through the first load. Because the first load is large, the short-circuit current flowing through is small in the case of a single-pole grounding fault, which can meet the requirement that the converter station can continue to operate for a period of time in the case of a single-pole grounding fault, so as to provide power supply reliability of the system. The control protection device is used to output a closing signal to the first circuit breaker when detecting the fault current of the second branch; the first circuit breaker switches to a closed state after receiving the closing signal. Since the short-circuit current is small, it is not conducive to the control 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 to short-circuit the first resistor, thereby increasing the short-circuit current, which is convenient for the control protection device to locate the fault branch and the fault location.

[0043] In one embodiment, if Figure 2 As shown, a second load 203 is also included; the second load is connected in series with the first branch 20.

[0044] The second load 203 can be any component with resistance; 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 protection device 10 detects a fault current, the first branch 20 is in a conducting state, and the resistance of the equivalent resistance after parallel connection can be reduced, so that when the current is increased, the current size of the control loop is not too large, so as to ensure the safety of the components.

[0045] 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.

[0046] Specifically, a first resistor is used as the first load, and a 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 be connected in parallel with the first resistor in the case of a single-pole grounding fault, thereby reducing the parallel equivalent resistance value and achieving the effect of increasing the current.

[0047] Among them, as a preferred implementation, the resistance value of the first resistor is between 1000Ω and 10000Ω, and the resistance value of the second resistor is between 100Ω and 1000Ω. Considering the actual voltage of the converter station, the resistance value range of the first resistor used for current limiting is greater than 1000Ω and less than 10000Ω, which can achieve a more reasonable current limiting effect. The resistance value 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 faults.

[0048] In one embodiment, if Figure 3 As shown, a first current transformer CT1 is also included; the first current transformer CT1 is connected in series between the second end of the first branch 20 and the second branch 30 connected in parallel and the ground.

[0049] The current transformer 40 is used to detect the current value of the loop, and can provide the current value of the current loop to the staff for relay protection and measurement and metering.

[0050] In one embodiment, if Figure 4 As shown, it also includes a lightning arrester 50; one end of the lightning arrester 50 is connected to the neutral point, and the other end is grounded. The lightning arrester 50 plays a role of voltage protection in the auxiliary device of the converter station.

[0051] In one embodiment, Figure 5 As shown, a converter station auxiliary method based on the above converter station auxiliary device is also provided, comprising the following steps:

[0052] Step S510, detecting whether there is a fault current in the second branch; wherein the second branch is connected in parallel with the first branch, a first end of the first branch and the second branch connected in parallel is connected to the neutral point of the converter station connection transformer, and a second end is grounded; the first branch includes a first circuit breaker; and the second branch includes a first load;

[0053] Specifically, whether a single-pole grounding fault occurs in the detection circuit is detected. Further, when a single-pole grounding fault occurs, a fault current is generated in the second branch. When the control protection device detects the fault current in the second branch, a closing signal is output to the first circuit breaker. In a specific example, the first circuit breaker can be a relay, and the control protection device energizes the electromagnet in the relay.

[0054] Step S520: If yes, output a closing signal to the first circuit breaker; the closing signal is used to control the first circuit breaker to close.

[0055] Specifically, after receiving the closing signal, the first circuit breaker switches to a closed state, so that the loop resistance becomes smaller, thereby achieving the effect of increasing the current, and further better locating the fault branch and the fault position. In a specific example, the first circuit breaker can be a relay. When the control protection device 10 detects the fault current of the second branch 30, the electromagnet is energized, and the contacts of the circuit are brought into contact through magnetic force, so that the first branch is turned on and the second branch is short-circuited, so as to achieve the effect of increasing the current, so as to facilitate the control protection device 10 to locate and troubleshoot the fault branch and the fault position.

[0056] It should be understood that although Figure 5 The steps in the flowchart are shown in sequence as indicated by the arrows, but these steps are not necessarily executed in the order indicated by the arrows. Unless otherwise specified in this document, there is no strict order restriction for the execution of these steps, and these steps can be executed in other orders. Moreover, Figure 5 At least part of the steps may include multiple sub-steps or multiple stages. These sub-steps or stages are not necessarily executed at the same time, but can be executed at different times. The execution order of these sub-steps or stages is not necessarily sequential, but can be executed in turn or alternately with other steps or at least part of the sub-steps or stages of other steps.

[0057] In one embodiment, Figure 6 As shown, a converter station is provided, comprising a converter valve 60, a connection transformer 70 and a converter station auxiliary device 80 as described above;

[0058] The high voltage side of the connection transformer 70 is used to connect to 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 to the DC positive line, and the lower bridge arm of the converter valve 60 is used to connect to the DC negative line;

[0059] When the control protection device 10 detects the fault current of the second branch 30 , it outputs a closing signal to the first circuit breaker CB1 ; after receiving the closing signal, the first circuit breaker CB1 switches to a closed state.

[0060] The converter valve 60 is used to convert AC power into DC power.

[0061] Specifically, the AC power supply outputs the initial AC current to the connecting transformer 70; the connecting transformer 70 converts the initial AC current into a 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 into a positive DC current and a negative DC current, and outputs the positive DC current to the DC positive line through the upper bridge arm, and outputs the negative DC current to the DC negative line through the lower bridge arm.

[0062] The control protection device 10 is used to detect whether a single-pole grounding fault occurs in the circuit. Further, when a single-pole grounding fault occurs, a fault current will be generated in the second branch 30. When the control protection device 10 detects the fault current in the second branch 30, it outputs a closing signal to the first circuit breaker CB1.

[0063] The above converter station includes a converter valve, a connecting transformer and a converter station auxiliary device such as any of the above items; the high voltage side of the connecting transformer is used to connect to 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 to the DC positive line, and the lower bridge arm of the converter valve is used to connect to the DC negative line; the control 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 switches to a closed state after receiving the closing signal. Since the short-circuit current is small, it is not conducive to the control 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, which is convenient for the control protection device to locate the fault branch and the fault location.

[0064] In one embodiment, if Figure 7 As shown, it also includes a station power branch 90; the first end of the station power branch is connected to the first end of the transformer 70, and the second end of the station power branch 90 is used to connect to an external line;

[0065] The station power 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, and 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 to the external line.

[0066] The station power branch 90 is used to provide power to the converter station equipment, the disconnecting device 901 is used to isolate the station power branch from the main line, and the station transformer 903 is used to adjust the input voltage.

[0067] Specifically, the station power branch 90 includes a disconnecting device 901 and a station transformer 903. One end of the disconnecting device 901 is connected to the high-voltage side of the station transformer 903, and the other end is connected to the high-voltage side of the connection transformer 70. When the disconnecting device 901 is closed, the station transformer 903 starts to work and outputs the voltage converted by the station transformer. When the disconnecting device 901 is opened, the station transformer 903 stops working.

[0068] The above-mentioned converter station includes a station power branch, so that the converter station provided by the present application does not need to be connected to an external power supply, thereby reducing the cost of laying external power supply lines.

[0069] In one embodiment, if Figure 8 As shown, the breaking device 901 includes a second circuit breaker CB2 and an isolating switch DS1; the second circuit breaker CB2 and the isolating switch DS1 are connected in series to the station power branch.

[0070] 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 pull the line contacts apart. The second circuit breaker CB2 and the isolating switch DS1 can effectively ensure the disconnection of the line.

[0071] In one embodiment, if Fig. 9 As shown, the station power branch 90 also 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.

[0072] Among them, the second current transformer CT2 is used to detect the current value of the loop, and can provide the current value of the current loop to the staff for relay protection and measurement and metering. In a specific example, an earth knife ES1 is set to connect to the high-voltage side of the station transformer 903 to provide power to the station transformer. 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 operate the input and removal of the station power branch. The earth knife ES1 is closed for maintenance.

[0073] In order to further illustrate the converter station auxiliary device, method and specific implementation method of the converter station of the present invention, the actual circuit diagram of a specific converter station is particularly combined, as shown in FIG. Fig.10 As shown, the working principle of the present invention is described, which can be specifically as follows:

[0074] The converter station includes a trunk line 100 and a station power branch line 90. The first end (end a) of the station power branch line is connected to the third circuit breaker CB3 in the trunk line 100, and the second end (end b) is used to connect to an external line.

[0075] The station power branch 90 includes a second circuit breaker CB2, a disconnector DS1, a second current transformer CT2, an earth switch ES1 and a station transformer 903. The second circuit breaker CB2, the disconnector DS1, the second current transformer CT2 and the station transformer 903 are connected in series, the earth switch ES1 is connected to the high voltage side of the station transformer 903, and the low voltage side of the station transformer 903 is connected to the second end (end b) of the station power branch.

[0076] The trunk line 100 includes a second lightning arrester 400, a voltage transformer 500, a third circuit breaker CB3, a second isolating switch DS2, a third current transformer CT3, a connection transformer 70 and a converter valve 60. The third circuit breaker CB3, the second isolating switch DS2 and the third current transformer CT3 are connected in series in sequence, and the voltage transformer 500 is used to detect the voltage on the high-voltage side of the connection transformer 70. The second lightning arrester 400 is used to perform voltage protection on the high-voltage side of the connection transformer 70. The high-voltage side of the connection transformer 70 is connected to the output end of the third current transformer CT3, and the low-voltage side is connected to the converter valve 60. The high-voltage side of the connection transformer 70 adopts a delta connection, and the low-voltage side of the connection transformer 70 adopts a star connection. The first end (end c) of the first branch 20 and the second branch 30 after being connected in parallel is connected to the neutral point of the connection transformer, and the first current transformer CT1 is connected in series between the second end (end d) and the ground. The first branch 20 includes a first circuit breaker CB1 and a second load 203 connected in series, and the second branch 30 includes a first load 301. The resistance of the first load 301 is greater than the resistance of the second load 203. In a specific embodiment, the resistance of the first load 301 is several thousand ohms, and the resistance of the second load 203 is several hundred ohms. When the first load and the second load are connected in parallel, the equivalent resistance is in the range of several tens to several hundred ohms.

[0077] Under normal operating conditions, the first circuit breaker CB1 is in the disconnected state. The neutral point of the connection transformer refers to the voltage balance point of each phase of the power equipment in which the windings or coils are connected in a star shape in a three-phase power system, and its potential to the ground is zero or close to zero when the power system is operating normally. When a single-pole grounding fault occurs, that is, when the line is struck by lightning and arc grounding occurs, the voltage of the healthy phase will suddenly increase, and a large excitation surge current will flow through the coil, causing the core to be magnetically saturated, resulting in a decrease in coil inductance and a decrease in inductive reactance. When the inductive reactance is less than the capacitive reactance, the core of the healthy mutual inductor will be magnetically saturated, which will increase the neutral point voltage. The lightning fault point, the neutral point and the second branch 30 will generate a loop to form a fault current. The first load 301 has a large resistance value, which can make the fault current flowing through smaller, so that the converter station equipment can continue to operate for a period of time in the case of a single-pole fault, so as to provide the power supply reliability of the system. When the control protection device 10 detects the fault current, it can control the first circuit breaker CB1 to switch to a closed state, so that the circuit resistance after parallel connection is reduced to tens to hundreds of ohms. Because the single-pole grounding fault has not been eliminated, the voltage caused by the fault will not change. When the resistance value is reduced, the fault current value will increase to several to dozens of times the original fault current value. At the same time, the increased current value will not damage the converter station equipment, which is convenient for the control and protection equipment to locate the fault branch and fault position.

[0078] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0079] The above-mentioned embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A converter station auxiliary device, characterized in that: It includes a control protection device, and a first branch and a second branch connected in parallel; The first end of the first branch and the second branch connected in parallel is connected to the neutral point of the converter station connection transformer, and the second end is grounded; the first branch includes a first circuit breaker; the second branch includes a first load; The control protection device is used to output a closing signal to the first circuit breaker when a fault current of the second branch is detected; The first circuit breaker switches to a closed state after receiving the closing signal; The converter station auxiliary device also includes a second load; the second load is connected in series to the first branch, wherein the first branch is used to increase the current in the loop, and the second branch is used to limit the current in the loop; 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; the resistance value of the first resistor is greater than 1000 and less than 10000 .

2. The converter station auxiliary device according to claim 1, characterized in that: The first circuit breaker is a relay.

3. The converter station auxiliary device according to claim 2, characterized in that: The resistance of the second resistor is greater than 100 and less than 1000 .

4. The converter station auxiliary device according to claim 1, characterized in that: Also includes a first current transformer; The first current transformer is connected in series between the second end of the first branch and the second branch connected in parallel and the ground.

5. The converter station auxiliary device according to claim 1, characterized in that: It also includes lightning arresters; One end of the arrester is connected to the neutral point, and the other end is grounded.

6. A converter station auxiliary method, characterized in that: The method is based on the converter station auxiliary device according to any one of claims 1 to 5, and the method comprises the following steps: Detecting whether there is a fault current in the second branch; wherein the second branch is connected in parallel with the first branch, a first end of the first branch and the second branch connected in parallel is connected to the neutral point of the converter station connection transformer, and a second end is grounded; the first branch includes a first circuit breaker; and the second branch includes a first load; If so, a closing signal is output to the first circuit breaker; the closing signal is used to control the first circuit breaker to close.

7. A converter station, characterized in that: It comprises a converter valve, a connecting transformer and a converter station auxiliary device as claimed in any one of claims 1 to 5; The high voltage side of the connection transformer is used to connect to 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 to the DC positive line, and the lower bridge arm of the converter valve is used to connect to the DC negative line.

8. The converter station according to claim 7, characterized in that: It also includes a station power branch; a first end of the station power branch is connected to the high voltage side of the connection transformer, and a second end of the station power branch is used to connect to an external line; The station power branch 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, and the other end is connected to the high-voltage side of the connecting transformer; the low-voltage side of the station transformer is connected to the external line.

9. The converter station according to claim 8, characterized in that: The breaking device comprises a second circuit breaker and an isolating switch; The second circuit breaker and the isolating switch are connected in series to the station power branch circuit.

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