A coupled contact switch with variable electrode shape and method

Abstract

The present invention provides a coupled contact switch with a variable electrode shape and a method, and relates to the technical field of high-voltage electrical appliances. The contact switch includes a moving contact end a, a static contact end b, a moving contact end c, a static contact end d, and a double-acting device. The present invention breaks through the design concept of mechanical switches in DC circuit breakers, and the contacts on both sides of the switch are composed of a moving end and a static end coupled. The operating speed of the entire switch is increased to twice the original. Through the designed coupled contact switch structure with a variable electrode shape and the proposed new double-acting operation mode, the overtravel is reduced, the opening speed is increased, and the breakdown voltage is also increased. The double-sided contact structure changes continuously with the switch operation process: when the contacts are turned on, there are three positions between the contacts to provide closing force, which ensures reliable contact while reducing the switch overtravel to 1 / 3 of the original. After the contacts move to the opening position, the regular electrode structure between the plates greatly improves the uniformity of the electric field between the contacts and the breakdown voltage.

Description

Technical Field

[0001] The invention belongs to the technical field of high-voltage electrical appliances, and in particular relates to a coupling contact switch with variable electrode shapes and a method. Background Art

[0002] With the emergence of the first DC transmission project based on voltage source converter (VSC) technology in 1997, flexible DC transmission technology has outstanding advantages in large power grid interconnection, new energy and long-distance large-capacity transmission, which has led to the rapid development of high-voltage DC transmission projects and attracted great attention from various countries. At present, there are 14 flexible DC transmission projects in operation in 16 countries in Europe, America, Asia, Oceania and Africa, of which 4 projects are used for wind power access, 7 projects are used for grid interconnection, 1 project is used for large-scale urban power supply, and 2 projects are used for offshore drilling platform power supply. my country has also planned and built a number of multi-terminal DC power grid projects to solve the problem of large-scale clean energy collection and transmission caused by weak power grids in northwest and coastal areas: in July 2011, China's first ±30kV / 20MW flexible DC transmission demonstration project was built in Nanhui, Shanghai; in 2014, a ±200kV / 400MW five-terminal flexible DC transmission project was built in Zhoushan, Zhejiang; in December 2015, the world's highest voltage level and largest transmission capacity true bipolar flexible DC transmission project, Xiamen ±320kV / 1000MW flexible DC transmission technology demonstration project was built; on December 14, 2017, the 500kV / 3000MW Zhangbei flexible DC transmission test demonstration project was approved by the state, and on February 28, 2018, the project officially started construction. It can be seen that whether it is to meet the consumption of new energy, promote the interconnection of AC power grids, or realize long-distance large-capacity power transmission, high-voltage DC transmission is the development direction of the future power grid.

[0003] However, the most important technical bottleneck restricting the development of high-voltage DC power grids is the rapid isolation technology of DC faults. The main difficulties in fault isolation of DC power grids are manifested in the following aspects: (1) There is no polarity change in the short-circuit current during the fault process, there is no zero crossing, and it is difficult for the circuit breaker to extinguish the arc. (2) The requirements for rapid fault removal are extremely high. The fault removal time of the DC power grid generally needs to be controlled within 5ms, otherwise it will pose a serious threat to the safety of the equipment. In order to ensure the safe, reliable and stable operation of the future high-voltage, large-capacity flexible DC power grid, research on high-voltage DC circuit breakers that can realize the rapid isolation function of DC power grid faults is one of the current problems that need to be solved urgently.

[0004] At present, high-voltage DC circuit breakers can be divided into three categories according to the type of key breaking devices in DC circuit breakers: mechanical DC circuit breakers, all-solid-state DC circuit breakers, and hybrid high-voltage DC circuit breakers. Hybrid DC circuit breakers have outstanding advantages such as fast opening speed, arc-free breaking, strong load capacity, and insulation performance. In recent years, they have become a research hotspot and development direction of DC circuit breakers. In order to break the fault current of the DC transmission system in a very short time (within 5ms), the fast mechanical switch in the hybrid DC circuit breaker is required to have extremely high action performance and insulation performance. Therefore, the design of mechanical switches in hybrid DC circuit breakers and the study of fast isolation mechanisms are the key to realizing this technology.

[0005] With the development of DC transmission technology, requirements such as high withstand voltage, fast opening, high mechanical life, and stable operation are put forward for DC circuit breakers. However, due to the limitations of mechanical switch operation speed, operating mechanism travel, and break insulation performance, multiple mechanical switches must be connected in series in the current high-voltage DC circuit breakers, which greatly increases the operating cost of the power grid and the risk of switch operation failures. Therefore, breaking through the technical bottlenecks of the opening speed, operating mechanism travel, switch mechanical life, break insulation performance, and operation reliability of mechanical switches in previous hybrid DC circuit breakers, and studying new switches and fast isolation mechanisms are of great significance for improving the operation reliability, mechanical life, and voltage level of DC circuit breakers, and promoting the safe and stable operation of power systems.

[0006] In 2012, ABB took the lead in developing the world's first 80kV IGBT-based direct series hybrid DC circuit breaker prototype with engineering application significance, with a breaking time of 5ms and a breaking current of 9kA; relying on the National 863 Project "Research on Key Technologies of DC Circuit Breakers", China Southern Power Grid Co., Ltd. developed a DC circuit breaker prototype with a rated voltage of 55kV, a breaking current of 16kA and a breaking time of 5ms at the end of 2014, which has passed the experiment and is currently actively promoting the demonstration application of the circuit breaker in South Australia projects. In 2014, ALSTOM developed a hybrid DC circuit breaker with a rated voltage of 120kV, a rated current of 1.5kA, a breaking time of 5.5ms and a breaking current of 5.2kA, and passed the test verification. With the support of the State Grid Corporation of China's scientific and technological projects, the State Grid Smart Grid Research Institute adopted the independently proposed full-bridge cascade hybrid DC circuit breaker topology and developed the world's first DC circuit breaker with a rated voltage of 200kV, a rated current of 2kA, a breaking current of 15kA and a breaking time of 3ms in 2014. It was demonstrated in the Zhoushan five-terminal DC project in December 2016.

[0007] In summary, the fault isolation technology of the current DC transmission system has made certain progress. However, the research field of hybrid DC circuit breakers still has the following technical limitations: (1) Limited by the operating speed of mechanical switches, hybrid DC circuit breakers with voltage levels above 160kV must use 4-10 switch modules in series operation, requiring multiple switches to complete the opening action simultaneously in a very short time, which increases the construction cost. Long-term operation will bring problems such as the dispersion of multiple switch actions; (2) Due to the large overtravel of the gas switch, which affects the opening time of the switch, the mechanical switch in the hybrid DC circuit breaker currently uses a vacuum break for isolation. The vacuum isolation break has the limitation of insulation saturation. In order to improve the insulation performance of the switch, the current solution generally uses multiple vacuum breaks in series to create a sufficient insulation distance, which inevitably brings the problem of multiple break insulation coordination synchronization, greatly reducing the reliability of the switch. Therefore, the current mechanical switch and isolation operation technology in the hybrid DC circuit breaker is difficult to meet the construction needs and development trends of DC transmission. With the development of DC transmission technology, requirements such as high withstand voltage, fast opening, and stable operation are put forward for DC circuit breakers. Therefore, in order to meet the needs of high-voltage DC transmission projects, it is necessary to overcome the difficulties of the opening speed, insulation performance and operation reliability of the mechanical switches in hybrid DC circuit breakers. Summary of the invention

[0008] In view of the shortcomings of the prior art, the present invention provides a coupling contact switch with a variable electrode shape and a method. Breaking through the design concept of mechanical switches in DC circuit breakers, a coupling contact switch with a variable electrode shape of a mechanical switch and a new double-acting operation mode are proposed. The contacts on both sides of the switch are composed of a moving end and a static end coupled. The operation speed of the entire switch is increased to twice the original. Through the designed coupling contact switch structure with a variable electrode shape and the proposed new double-acting operation mode, the overtravel is reduced, the opening speed is increased, and the breakdown voltage is also increased. The switch meets the DC grid operation tasks of higher voltage levels. The double-sided contact structure changes continuously with the switch operation process: when conducting, there are three positions between the contacts to provide closing force, which ensures reliable contact while reducing the switch overtravel to 1 / 3 of the original. After the contact moves to the opening position, the original irregular electrode structure between the ring and the rod becomes a regular electrode structure between the plate and the plate, which greatly improves the uniformity of the electric field between the contacts and the breakdown voltage.

[0009] The technical solution adopted by the present invention is:

[0010] On the one hand, the present invention provides a coupled contact switch with a variable electrode shape, comprising a contact moving end a, a contact static end b, a contact moving end c, a contact static end d, and a double-acting device;

[0011] One end of the moving end a of the contact is in sliding contact with the static end b of the contact, the other end of the moving end a of the contact is connected to one end of the double-acting device by a rotating bolt, the other end of the double-acting device is connected to one end of the moving end c of the contact by a fixing bolt, and one end of the moving end c of the contact is in sliding contact with the static end d of the contact;

[0012] The contact positions at the moving and static ends of the contacts on both sides are in a petal-shaped structure, and the closing position provides sufficient closing force to ensure that the four contacts on both sides are in reliable contact when the switch is turned on.

[0013] On the other hand, a coupling contact switch method with a variable electrode shape is implemented by the aforementioned coupling contact switch with a variable electrode shape:

[0014] When the switch is closed, the moving end a of the contact is in contact with the static end b of the contact, the moving end a of the contact is in contact with the moving end c of the contact, and the static end b of the contact is in contact with the moving end c of the contact; when the switch is closed, the contact closing position is in contact with the effective electrical contact area, and three contacts are in contact and conduction at the same time. When the contacts are in contact, the closing position of the contact provides a closing force for the moving end a of the contact and the static end b of the contact; the closing position of the contact provides a closing force for the moving end a of the contact and the moving end c of the contact; the closing position of the contact provides a closing force for the moving end c of the contact and the static end d of the contact;

[0015] During the closing process: the moving end a of the contact moves toward the double-acting device; the double-acting device is linked to move toward the moving end a of the contact; the fixing bolts of the double-acting device and the moving end c of the contact drive the moving end c of the contact to move toward the static end of the contact; thus, the moving end a of the contact drives the moving end of the contact to move relative to each other during the closing process, and the closing speed is increased to twice the previous speed;

[0016] During the opening process, the moving end a of the contact moves toward the static end of the contact; the linked double-acting device moves in the opposite direction of the moving end a of the contact; the fixing bolts of the double-acting device and the moving end c of the contact drive the moving end c of the contact to move in the direction of the double-acting device; thus, the moving end a of the contact drives the moving end of the contact to move in the opposite direction at the same time during the opening process, and the opening speed is increased to twice the previous speed;

[0017] In the open state: the moving end a of the contact moves to the open position, forming a flat electrode structure with the static end b of the contact; the moving end c of the contact moves to the open position, forming a flat electrode structure with the static end d of the contact; the original irregular electrode structure between the ring and the rod between the four contacts is transformed into a regular electrode structure between the plates, thereby optimizing the field strength between the contacts, reducing the overtravel while also increasing the breakdown voltage.

[0018] The beneficial effects of adopting the above technical solution are:

[0019] (1) A switch structure with dual-sided moving and static contact coupling is proposed to achieve closure of three positions of four contacts, ensuring reliable closure while reducing the switch overtravel to 1 / 3 of the original, thereby reducing the opening time of the gas switch.

[0020] (2) When closing the circuit breaker, the three contacts are in contact and conduction at the same time. Compared with the previous double-contact contact conduction, the conduction is more reliable, the contact area is larger, the contact resistance is smaller, and the closing is more stable.

[0021] (3) Invent a coupled contact structure and method with a variable electrode shape. At the maximum position of the fracture voltage, the contact structure is adaptively adjusted to form a regular electrode shape between the plates, which can optimize the electric field distribution of the fracture and increase the breakdown voltage.

[0022] (4) A new double-action operation mode of the mechanical switch is developed. By designing the double-action structure and operation mode inside the break, the opening speed of the entire switch is increased to twice the original speed.

[0023] (5) Invent an SF6 double-acting switch with an improved contact structure to improve the insulation level of the switch break, breaking through the limitation of insulation saturation of the vacuum break of the mechanical switch in previous DC circuit breakers. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 A schematic diagram of a coupled contact switch structure with a variable electrode shape;

[0025] In the figure, 1-contact moving end a, 2-contact static end b, 3-contact moving end c, 4-contact static end d, 5-double-acting device, 6-contact closing position when closing, 7-contact closing position and effective electrical contact area when closing, 8-contact closing position when closing;

[0026] Figure 2 This is a schematic diagram of the electrode structure in the open position;

[0027] Figure 3 It is a schematic diagram of the double-sided contact petal-shaped contact structure. DETAILED DESCRIPTION

[0028] The specific implementation modes of the present invention are described in detail below with reference to the accompanying drawings.

[0029] A coupled contact switch with variable electrode shape, such as Figure 1 As shown, it includes 1-contact moving end a, 2-contact static end b, 3-contact moving end c, 4-contact static end d, 5-double-acting device;

[0030] One end of the 1-contact moving end a is in sliding contact with the 2-contact static end b, the other end of the 1-contact moving end a is connected to one end of the 5-double-action device by a rotating bolt, the other end of the 5-double-action device is connected to one end of the 3-contact moving end c by a fixing bolt, and one end of the 3-contact moving end c is in sliding contact with the 4-contact static end d;

[0031] The contact positions of the moving and static ends of the contacts on both sides are in a petal-shaped structure, and the closing position provides sufficient closing force to ensure that the four contacts on both sides are in reliable contact when the switch is turned on;

[0032] In the closed state: 1-contact moving end a and 2-contact static end b, 1-contact moving end a and 3-contact moving end c, 2-contact static end b and 3-contact moving end c are in contact and conduction. In the closed position of the contact and the effective electrical contact area when 7-is closed, three contacts are in contact and conduction at the same time. In this embodiment, the three contacts are in contact and conduction at the same time. Compared with the previous double-contact contact conduction, the conduction is more reliable, the contact area is larger, the contact resistance is smaller, and the closing is more stable. When the contacts are in contact, 6-the contact closing position when closing the circuit is 1-the moving contact end a and 2-the static contact end b provide closing force; 7-the contact closing position when closing the circuit is 1-the moving contact end a and 3-the moving contact end c provide closing force; 8-the contact closing position when closing the circuit is 3-the moving contact end c and 4-the static contact end d provide closing force; in this embodiment, there are three positions to provide closing force, compared with the previous one where only one position provided closing force, it avoids the previous contact method where the moving and static contacts provide closing force at a single plug-in position, which requires increasing the disadvantage of overtravel, and while ensuring the same closing force, reduces the overtravel to 1 / 3 of the original.

[0033] During the closing process: 1-contact moving end a moves toward the double-acting device; the 5-double-acting device is linked to move toward the contact moving end a; through the action of the 5-double-acting device and the 3-contact moving end c fixing bolts, the 3-contact moving end c is driven to move toward the contact static end; thus, the purpose of 1-contact moving end a driving 3-contact moving end to move relative to each other during the closing process is achieved, and the closing speed is increased to twice the previous speed.

[0034] During the opening process, the 1-contact moving end a moves toward the contact static end; the 5-double-acting device is linked to move in the opposite direction of the 1-contact moving end a; through the action of the fixing bolts of the 5-double-acting device and the 3-contact moving end c, the 3-contact moving end c is driven to move in the direction of the 5-double-acting device; thereby achieving the purpose of the 1-contact moving end a driving the 3-contact moving end to move in the opposite directions at the same time during the opening process, and increasing the opening speed to twice the previous speed.

[0035] In the open state: Figure 2As shown in the figure, the moving end a of the 1-contact moves to the opening position, forming a flat electrode structure with the static end b of the 2-contact; the moving end c of the 3-contact moves to the opening position, forming a flat electrode structure with the static end d of the 4-contact; the original irregular electrode structure between the ring and the rod between the four contacts is changed to a regular electrode structure between the plates. This optimizes the field strength between the contacts, reduces the overtravel and also increases the breakdown voltage.

[0036] At the moving and stationary contact positions (6, 7 and 8) of the double-sided contacts, the design is as follows Figure 3 The petal-shaped structure shown provides sufficient closing force in the closed position, ensuring that the four contacts on both sides are in reliable contact when the switch is turned on.

[0037] In order to improve the opening speed, a new double-action operation mode of mechanical switch is proposed. Both contacts on both sides are composed of a static end and a dynamic end coupled, and a double-action device is set on the dynamic end drive rod of the contact on one side of the switch. When the switch is opened, the static ends of the contacts on both sides are stationary, and the dynamic ends are separated at high speed in opposite directions at the same time under the action of the operating mechanism and the double-action device. The original operation mode of single moving contact movement during switch operation is improved to simultaneous movement of both sides of the contact, which increases the operation speed of the entire switch to twice the original.

[0038] Since the moving contact of the contact switch has mechanical inertia, it drives a separate motion system to complete the isolation operation task in a very short time (within 5ms), and its response speed is close to the limit, that is, it is difficult to significantly increase the response speed by increasing the operating power of the operating mechanism, and reduce the response time of a single moving contact. To this end, the applicant proposed a new double-action operation mode for a mechanical switch, which improves the original operation mode in which the moving contact moves and the static contact is stationary during switch operation to a mode in which the static ends of both sides of the contact are stationary, and the moving end of one side of the contact moves while the moving end of the other side moves in the opposite direction, thereby increasing the operation speed of the entire switch to twice the original speed. Through the designed coupled contact switch structure with variable electrode shape and the proposed new double-action operation mode, the breakdown voltage is increased while reducing overtravel and increasing the opening speed. The switch can meet the operation tasks of DC power grids with higher voltage levels.

[0039] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope defined by the claims of the present invention.

Claims

1. A coupled contact switch with variable electrode shape, characterized in that: It includes a moving contact end a, a static contact end b, a moving contact end c, a static contact end d, and a double-acting device; One end of the contact moving end a is in sliding contact with the contact static end b, the other end of the contact moving end a is connected to one end of the double-acting device by a rotating bolt, the other end of the double-acting device is connected to one end of the contact moving end c by a fixing bolt, and one end of the contact moving end c is in sliding contact with the contact static end d; The contact positions of the moving and static ends of the contacts on both sides are in a petal-shaped structure, and the closing position provides sufficient closing force to ensure that the four contacts on both sides are in reliable contact when the switch is turned on; The coupled contact switch with variable electrode shape is used to implement the following method, specifically: When the switch is closed, the moving end a of the contact is in contact with the static end b of the contact, the moving end a of the contact is in contact with the moving end c of the contact, and the static end b of the contact is in contact with the moving end c of the contact; when the switch is closed, the contact closing position is in contact with the effective electrical contact area, and three contacts are in contact and conduction at the same time. When the contacts are in contact, the closing position of the contact provides a closing force for the moving end a of the contact and the static end b of the contact; the closing position of the contact provides a closing force for the moving end a of the contact and the moving end c of the contact; the closing position of the contact provides a closing force for the moving end c of the contact and the static end d of the contact; During the closing process: the moving end a of the contact moves toward the double-acting device; the double-acting device is linked to move toward the moving end a of the contact; the fixing bolts of the double-acting device and the moving end c of the contact drive the moving end c of the contact to move toward the static end of the contact; thus, the moving end a of the contact drives the moving end of the contact to move relative to each other during the closing process, and the closing speed is increased to twice the previous speed; During the opening process, the moving end a of the contact moves toward the static end of the contact; the linked double-acting device moves in the opposite direction of the moving end a of the contact; the fixing bolts of the double-acting device and the moving end c of the contact drive the moving end c of the contact to move in the direction of the double-acting device; thus, the moving end a of the contact drives the moving end of the contact to move in the opposite direction at the same time during the opening process, and the opening speed is increased to twice the previous speed; In the open state: the moving end a of the contact moves to the open position, forming a flat electrode structure with the static end b of the contact; the moving end c of the contact moves to the open position, forming a flat electrode structure with the static end d of the contact; the original irregular electrode structure between the ring and the rod between the four contacts is transformed into a regular electrode structure between the plates, thereby optimizing the field strength between the contacts, reducing the overtravel while also increasing the breakdown voltage.

Images