Controllable arrester based on self-triggered air-gap switch

Abstract

The application is suitable for the technical field of over-voltage protection device of super-high voltage and extra-high voltage transmission system, and provides a controllable arrester based on self-triggering air-gap switch, which comprises an arrester fixed part, an arrester controllable part, a bypass capacitor high-voltage part, a bypass capacitor low-voltage part, an air-gap switch and an intermediate bridge valve group; the arrester fixed part, the arrester controllable part, the bypass capacitor high-voltage part, the bypass capacitor low-voltage part and the intermediate bridge valve group form an electric bridge structure, and the air-gap switch is connected in parallel with the bypass low-voltage part; the capacitance ratio of the bypass capacitor low-voltage part to the bypass capacitor high-voltage part is less than the rated voltage ratio of the arrester fixed part and the arrester controllable part. The short circuit of the arrester controllable part is realized through the cooperation of electrical parameters, the over-voltage can be protected in time, the influence caused by the dispersion of the air-gap switch action is avoided, a complex control system is not needed, and the device is less and the structure is simple.

Description

Technical Field

[0001] This invention belongs to the technical field of overvoltage protection devices for ultra-high voltage and extra-high voltage power transmission systems, and particularly relates to a controllable surge arrester based on an autonomously triggered air gap switch. Background Technology

[0002] Surge arresters are important overvoltage protection devices in power systems. Early surge arresters used gaps to limit overvoltage. Later, with the development of materials science, valve-type surge arresters made of metal resistance elements using silicon carbide as raw material have been widely used. Today, the resistance elements of surge arresters are mainly made of zinc oxide (ZnO).

[0003] Ultra-high voltage (UHV) and extra-high voltage (EHV) substation systems have high voltage levels and long transmission lines, making switching overvoltages a decisive factor in the insulation level of transmission and transformation equipment. Under fixed-load conditions, the ratio of switching overvoltage to operating voltage is constant. However, as the system voltage increases, the impact of switching overvoltage levels on the insulation design of transmission and transformation equipment becomes increasingly severe. Limiting the switching overvoltage multiple is a crucial function of surge arresters; however, in UHV and EHV systems, surge arresters using only high-performance resistive elements are insufficient to limit switching overvoltage levels to the specified limits.

[0004] Currently, for ultra-high voltage (UHV) systems with long transmission lines, limiting operational overvoltage is mainly achieved through two methods: one is using metal oxide (ZnO) surge arresters in conjunction with circuit breakers and adding closing resistors; the other is using controllable surge arresters. The scheme using metal oxide surge arresters with closing resistors is the most widely used. However, the closing resistor itself experiences significant electrical stress under the UHV electric field and has a complex structure, resulting in significant shortcomings in terms of economy and reliability. Circuit breakers using closing resistors are one of the major sources of equipment hazard in substations. Controllable surge arresters connect some valve plates in parallel with controllable switches, short-circuiting some valve plates before operation to further reduce operational overvoltage. According to the type of controllable switch, controllable surge arresters can be divided into mechanical switch type, power electronic switch type, and gap switch type. Among them, mechanical switch type and power electronic switch type require relatively complex control systems, while gap switch type has a certain degree of decentralization. Furthermore, existing controllable surge arresters, in addition to primary equipment such as valve plates and controllable switches, require complete secondary equipment for measurement, control, and triggering, which significantly increases the complexity of the equipment and raises the failure rate. Summary of the Invention

[0005] This invention provides a controllable surge arrester based on an autonomously triggered air gap switch to solve the problems of complex equipment and control systems in existing controllable surge arresters.

[0006] This invention is achieved through the following technical solution:

[0007] In a first aspect, the embodiments of the present application provide a controllable lightning arrester based on an autonomous trigger air gap switch, comprising: a lightning arrester fixed part, a lightning arrester controllable part, a bypass capacitor high-voltage part, a bypass capacitor low-voltage part, an air gap switch, and an intermediate bridge valve group; wherein the intermediate bridge valve group is a lightning arrester.

[0008] One end of the lightning arrester fixed part is connected to one end of the bypass capacitor high-voltage part, and the other end of the lightning arrester fixed part is connected to one end of the lightning arrester controllable part and one end of the intermediate bridge valve group, respectively; the other end of the intermediate bridge valve group is connected to the other end of the bypass capacitor high-voltage part and one end of the bypass capacitor low-voltage part, respectively; the other end of the lightning arrester controllable part is connected to the other end of the bypass capacitor low-voltage part and grounded; the air gap switch is connected in parallel with the bypass capacitor low-voltage part; wherein the ratio of the capacitances of the bypass capacitor low-voltage part and the bypass capacitor high-voltage part is less than the ratio of the rated voltages of the lightning arrester fixed part and the lightning arrester controllable part.

[0009] In combination with the first aspect, in some embodiments, the end of the lightning arrester fixed part connected to the bypass capacitor high-voltage part is used to connect a power transmission line; when the length of the power transmission line is greater than a first preset length and less than or equal to a second preset length, the rated voltage percentage of the lightning arrester controllable part increases with the increase of the length of the power transmission line.

[0010] The rated voltage percentage of the lightning arrester controllable part is the percentage of the rated voltage of the lightning arrester controllable part in the total rated voltage of the controllable lightning arrester; the total rated voltage of the controllable lightning arrester is the sum of the rated voltage of the lightning arrester fixed part and the rated voltage of the lightning arrester controllable part.

[0011] In combination with the first aspect, in some embodiments, the rated voltage percentage of the lightning arrester controllable part ranges from 20% to 25%.

[0012] In combination with the first aspect, in some embodiments, when the length of the power transmission line is less than or equal to the first preset length, the rated voltage percentage of the lightning arrester controllable part is a first preset percentage.

[0013] When the length of the power transmission line is greater than the first preset length and less than or equal to a third preset length, the rated voltage percentage of the lightning arrester controllable part is a second preset percentage.

[0014] When the length of the power transmission line is greater than the third preset length and less than or equal to the second preset length, the rated voltage percentage of the lightning arrester controllable part is a third preset percentage.

[0015] The ratio of the rated voltage of the arrester controllable part to the total rated voltage of the controllable arrester is the rated voltage ratio of the arrester controllable part, and the total rated voltage of the controllable arrester is the sum of the rated voltage of the arrester fixed part and the rated voltage of the arrester controllable part.

[0016] In combination with the first aspect, in some embodiments, the first preset length is 250 km, the third preset length is 300 km, and the second preset length is 350 km.

[0017] The first preset percentage is 20%, the second preset percentage is 22%, and the third preset percentage is 25%.

[0018] In combination with the first aspect, in some embodiments, the ratio of the capacitances of the bypass capacitor low-voltage part and the bypass capacitor high-voltage part is 0.5 times the first ratio.

[0019] The first ratio is the ratio of the rated voltages of the arrester fixed part and the arrester controllable part.

[0020] In combination with the first aspect, in some embodiments, the operating voltage of the air gap switch is a preset multiple of the rated voltage of the arrester controllable part, and the preset multiple is greater than 1 and less than 2.

[0021] In combination with the first aspect, in some embodiments, the rated voltage of the intermediate bridge valve group is 5% of the sum of the rated voltages of the arrester fixed part and the arrester controllable part.

[0022] In combination with the first aspect, in some embodiments, the arrester fixed part and the arrester controllable part are both metal oxide arrester resistors.

[0023] In combination with the first aspect, in some embodiments, the power transmission line is an extra-high voltage power transmission line or an ultra-high voltage power transmission line.

[0024] The embodiment of the present application provides a controllable lightning arrester based on self-triggering air gap switch, which comprises a lightning arrester fixed part, a lightning arrester controllable part, a bypass capacitor high-voltage part, a bypass capacitor low-voltage part and an intermediate bridge valve group, the air gap switch is connected in parallel with the bypass capacitor low-voltage part, and the ratio of capacitance values between the bypass capacitor low-voltage part and the bypass capacitor high-voltage part is less than the ratio of rated voltages of the lightning arrester fixed part and the lightning arrester controllable part, so that the voltage division ratio of the bypass capacitor low-voltage part is greater than the voltage division ratio of the lightning arrester controllable part. In this way, when an operating overvoltage or a lightning overvoltage occurs, the voltage rising speed of the bypass capacitor low-voltage part is obviously faster than that of the lightning arrester controllable part under high-frequency voltage, when the voltage value of the bypass capacitor low-voltage part reaches the value set by the parallel air gap switch, the air gap switch breaks down, the lightning arrester controllable part is replaced by the intermediate bridge valve group to be grounded, and the overvoltage flows into the ground through the lightning arrester fixed part, the intermediate bridge valve group and the air gap switch. That is, the present application adopts passive devices, and realizes short circuit of the lightning arrester controllable part through cooperation of electrical parameters, can timely protect the overvoltage, avoids influence caused by dispersion of the air gap switch, ensures that the ultra-high voltage and the special high voltage operating and lightning overvoltage are within a safe range, and does not need a complex control system, has few devices and simple structure. BRIEF DESCRIPTION OF DRAWINGS

[0025] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed to be used in the embodiments or related description will be briefly introduced. Obviously, the drawings in the following description only some embodiments of the present application, and for those skilled in the art, other drawings can be obtained without creative labor.

[0026] Figure 1 is a structure schematic diagram of the controllable lightning arrester based on self-triggering air gap switch provided by an embodiment of the present application;

[0027] Figure 2 is an equivalent circuit diagram of the controllable lightning arrester based on self-triggering air gap switch provided by an embodiment of the present application;

[0028] Figure 3 is a voltage direction schematic diagram of the controllable lightning arrester based on self-triggering air gap switch provided by an embodiment of the present application when the air gap switch does not act;

[0029] Figure 4 is a schematic diagram of overvoltage discharge path of the controllable lightning arrester based on self-triggering air gap switch provided by an embodiment of the present application after the air gap switch acts;

[0030] Figure 5 is a waveform schematic diagram of voltage across the air gap switch in the overvoltage process provided by an embodiment of the present application. DETAILED DESCRIPTION

[0031] In the following description, for purposes of explanation and not limitation, specific details are set forth such as particular architectures, technologies, techniques, etc. in order to provide a thorough understanding of the embodiments of the present application. However, it will be apparent to those skilled in the art that the present application can be practiced in other embodiments that depart from these specific details. In other instances, detailed descriptions of well-known systems, devices, circuits, and methods are omitted so as not to obscure the description of the present application with unnecessary detail.

[0032] It is to be understood that the terminology "including", "comprising", "consisting" or "consisting essentially of" used in the specification and the appended claims, indicates the presence of the described features, integers, steps, operations, elements, and / or components, but does not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof.

[0033] In addition, the terms "first", "second", "third", etc. are used herein only to describe different aspects of the application, and are not intended to denote relative importance of the different aspects.

[0034] Reference in the specification to "one embodiment" or "some embodiments" or "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the application. The appearances of the phrases "in one embodiment" or "in some embodiments" or "in other embodiments" or "in still other embodiments" in various places in the specification are not necessarily all referring to the same embodiment, nor are they necessarily referring to some, but not all embodiments. The terms "including", "comprising", "having" and variations thereof are meant to encompass the terms "including but not limited to".

[0035] The dispersion of the air gap switch action refers to that the actual action voltage of the air gap switch can have a large fluctuation around the set action voltage, for example, the action voltage of an air gap switch is set to be 100kV, that is, the air gap switch breaks down when the voltage reaches 100kV, 100 breakdown tests are performed on the air gap switch, and during the tests, the actual breakdown voltage of the air gap switch can be 90kV, 100kV or 110kV, that is, the action of the air gap switch has dispersion.

[0036] The embodiment of the present application provides a controllable arrester based on an autonomous trigger air gap switch, a bypass capacitor is introduced into the air gap switch type controllable arrester, and the capacitor characteristic is used to make the voltage of the capacitor in parallel with the air gap switch reach the action voltage of the air gap switch in advance of the controllable part of the arrester, so as to timely suppress the overvoltage and avoid the influence of the dispersion of the air gap switch action.

[0037] The controllable surge arrester based on an autonomously triggered air gap switch provided by the present invention will be described in detail below with reference to the accompanying drawings and specific embodiments:

[0038] See Figure 1 The controllable surge arrester based on an autonomously triggered air gap switch provided in this embodiment of the invention includes: a fixed part R1 of the surge arrester, a controllable part R2 of the surge arrester, a high-voltage part C1 of the bypass capacitor, a low-voltage part C2 of the bypass capacitor, an air gap switch S, and an intermediate bridge valve plate group R3.

[0039] Figure 2 This is an equivalent circuit diagram of a controllable surge arrester based on an autonomously triggered air gap switch, provided in an embodiment of the present invention. Figure 2 As shown, one end of the fixed portion R1 of the surge arrester is connected to one end of the high-voltage portion C1 of the bypass capacitor. The other end of the fixed portion R1 is connected to one end of the controllable portion R2 of the surge arrester and one end of the intermediate bridge valve plate group R3. The other end of the intermediate bridge valve plate group R3 is connected to the other end of the high-voltage portion C1 of the bypass capacitor and one end of the low-voltage portion C2 of the bypass capacitor. The other end of the controllable portion R2 of the surge arrester is connected to the other end of the low-voltage portion C2 of the bypass capacitor and grounded. The air gap switch S is connected in parallel with the low-voltage portion C2 of the bypass capacitor. Furthermore, the capacitance ratio Cn2:Cn1 of the low-voltage portion C2 of the bypass capacitor to the high-voltage portion C1 of the bypass capacitor is less than the ratio Un1:Un2 of the rated voltages of the fixed portion R1 of the surge arrester and the controllable portion R2 of the surge arrester.

[0040] In this embodiment of the invention, the surge arrester fixed portion R1, the surge arrester controllable portion R2, the bypass capacitor high-voltage portion C1, the bypass capacitor low-voltage portion C2, the air gap switch S, and the intermediate bridge valve plate group R3 form a bridge structure. It should be understood that the end of the surge arrester fixed portion R1 connected to the bypass capacitor high-voltage portion C1 is used to connect to the transmission line.

[0041] Under power frequency conditions, the impedance of the bypass capacitor is much greater than that of the surge arrester. The voltage distribution between the fixed part R1 and the controllable part R2 of the surge arrester depends on the ratio of the rated voltage Un1:Un2 of the surge arrester. At this time, the high-voltage part C1 of the bypass capacitor, the low-voltage part C2 of the bypass capacitor, and the intermediate bridge valve plate group R3 do not function. When the air gap switch S does not operate, the voltage direction in the controllable surge arrester is as follows: Figure 3 As shown.

[0042] When the operating overvoltage or lightning overvoltage occurs, the voltage boosting speed of the bypass capacitor low-voltage part C2 under high-frequency voltage (the frequency of the overvoltage is usually much higher than the power frequency of 50 Hz) is obviously faster than that of the controllable part R2 of the surge arrester, that is, at this time, the voltage division ratio in the controllable surge arrester mainly depends on the voltage division ratio of the bypass capacitor high-voltage part C1 and the bypass capacitor low-voltage part C2. When the voltage division value of the bypass capacitor low-voltage part C2 reaches the operating voltage value set by the parallel air gap switch S, the air gap switch breaks down and operates, the controllable part R2 of the surge arrester is replaced by the middle bridge valve group R3 to be grounded, and the overvoltage flows into the ground through the fixed part R1 of the surge arrester, the middle bridge valve group R3 and the air gap switch S. The overvoltage discharge path after the air gap switch S operates is shown in Figure 4 .

[0043] For the series capacitors, the voltage ratio is equal to the inverse ratio of the capacitance values. In the embodiment, since the capacitance ratio Cn2:Cn1 of the bypass capacitor low-voltage part C2 to the bypass capacitor high-voltage part C1 is less than the rated voltage ratio Un1:Un2 of the fixed part R1 of the surge arrester to the controllable part R2 of the surge arrester, the voltage division ratio UCn1:UCn2 of the bypass capacitor high-voltage part C1 to the bypass capacitor low-voltage part C2 is less than the rated voltage ratio Un1:Un2 of the fixed part R1 of the surge arrester to the controllable part R2 of the surge arrester. It can be further deduced that, when the bypass capacitor divides the voltage, the voltage division proportion of the bypass capacitor low-voltage part C2 is greater than the voltage division proportion of the controllable part R2 of the surge arrester when the surge arrester divides the voltage. Therefore, under high-frequency voltage, the voltage division value of the bypass capacitor low-voltage part C2 can reach the operating voltage of the air gap switch S earlier than the voltage division value of the controllable part R2 of the surge arrester, so as to cut off the controllable part R2 of the surge arrester in advance.

[0044] In the embodiment of the application, the fixed part R1 of the surge arrester and the controllable part R2 of the surge arrester are both metal oxide surge arrester resistors. According to the length of the load-carrying line at the installation position, the percentage k of the rated voltage Un2 of the controllable part R2 of the surge arrester to the total rated voltage (Un1+Un2) of the surge arrester can be between 20% and 25%. The load-carrying line can be an ultrahigh-voltage transmission line or an extra-high-voltage transmission line.

[0045] In a possible implementation, when the length of the transmission line is greater than a first preset length and less than or equal to a second preset length, the percentage k of the rated voltage of the controllable part R2 of the surge arrester increases with the increase of the length of the transmission line. That is, the longer the load-carrying line, the greater the proportion of the controllable part.

[0046] In the embodiment of the application, the fixed part R1 of the surge arrester and the controllable part R2 of the surge arrester are both metal oxide surge arrester resistors. According to the length of the load-carrying line at the installation position, the percentage k of the rated voltage Un2 of the controllable part R2 of the surge arrester to the total rated voltage (Un1+Un2) of the surge arrester can be between 20% and 25%. The load-carrying line can be an ultrahigh-voltage transmission line or an extra-high-voltage transmission line.

[0047] In another possible implementation, when the length of the power transmission line is less than or equal to a first preset length, the ratio of the rated voltage of the controllable part R2 of the surge arrester is a first preset percentage; when the length of the power transmission line is greater than the first preset length and less than or equal to a third preset length, the ratio of the rated voltage of the controllable part R2 of the surge arrester is a second preset percentage; when the length of the power transmission line is greater than the third preset length and less than or equal to a second preset length, the ratio of the rated voltage of the controllable part R2 of the surge arrester is a third preset percentage.

[0048] Optionally, the first preset length is 250 km, the third preset length is 300 km, and the second preset length is 350 km; the first preset percentage is 20%, the second preset percentage is 22%, and the third preset percentage is 25%.

[0049] In the above implementation, when the length of the ultra-high voltage power transmission line is less than or equal to 250 km, the ratio of the rated voltage of the controllable part R2 of the surge arrester is set to 20%; when the length of the ultra-high voltage power transmission line is greater than 250 km and less than or equal to 300 km, the ratio of the rated voltage is set to 22%; and when the length of the ultra-high voltage power transmission line is greater than 300 km and less than or equal to 350 km, the ratio of the rated voltage is set to 25%.

[0050] In some embodiments, the ratio of the capacitances of the bypass capacitor low-voltage part C2 and the bypass capacitor high-voltage part C1 is 0.5 times the ratio of the rated voltages of the surge arrester fixed part R1 and the surge arrester controllable part R2.

[0051] In this embodiment, it is known from the voltage ratio of the series capacitors that the voltage ratio UCn2:UCn1 of the bypass capacitor low-voltage part C2 and the bypass capacitor high-voltage part C1 is 2 times the ratio Un2:Un1 of the rated voltages of the surge arrester controllable part R2 and the surge arrester fixed part R1.

[0052] In some embodiments, the intermediate bridge valve group R3 is a surge arrester valve, and the rated voltage thereof is 5% of the sum of the rated voltages of the surge arrester fixed part R1 and the surge arrester controllable part R2.

[0053] In this embodiment, the intermediate bridge valve group R3 with a smaller rated voltage is provided, so that after the air gap switch S is broken down and turned on, the overvoltage can be smoothly introduced into the ground through the surge arrester fixed part R1, the intermediate bridge valve group R3, and the air gap switch S. When the air gap switch S is turned on, the total rated voltage of the new surge arrester composed of the surge arrester fixed part R1 and the intermediate bridge valve group R3 is only 80% to 85% of the total rated voltage of the surge arrester composed of the surge arrester fixed part R1 and the surge arrester controllable part R2, so that the overvoltage can be effectively suppressed.

[0054] In some embodiments, the action voltage of the air gap switch S is a preset multiple of the rated voltage of the controllable part R2 of the arrester; wherein the preset multiple is greater than 1 and less than 2.

[0055] In one possible implementation, the preset multiple is 1.2. In this implementation, when the controllable arrester is impacted by an overvoltage, the maximum withstand voltage of the low-voltage part C2 of the bypass capacitor can reach 1.2 times or even higher of the rated voltage Un2 of the controllable part R2 of the arrester, depending on the dispersion of the action of the air gap switch. For example, if the action voltage of the air gap switch S is set to be 1.2Un2, the actual action voltage of the air gap switch S can fluctuate around 1.2Un2; if the actual action voltage of the air gap switch S at one time is 1.25Un2, the maximum withstand voltage of the low-voltage part C2 of the bypass capacitor can reach 1.25Un2.

[0056] Next, the present application provides a specific embodiment to describe the controllable arrester based on the self-triggered air gap switch.

[0057] In this embodiment, the arrester fixed part R1, the arrester controllable part R2 and the intermediate bridge valve group R3 are all composed of ordinary zinc oxide varistors in series. Among them, the rated voltage of the arrester fixed part R1 is 1000kV, the rated voltage of the arrester controllable part R2 is 250kV, and the rated voltage of the intermediate bridge valve group R3 is 62.5kV. That is, the rated voltage ratio k of the arrester controllable part R2 is 20%. The action voltage of the air gap switch S is 300kV, which is 1.2 times of the rated voltage of the arrester controllable part R2. The ratio of the capacitance of the low-voltage part C2 of the bypass capacitor to the high-voltage part of the bypass capacitor is 2.5.

[0058] When the lightning overvoltage and the operating overvoltage are applied to the controllable arrester, the voltage across the air gap switch S is:

[0059]

[0060] wherein, U p (t) is the overvoltage signal, and the value of C2 / C1 is k / 2.

[0061] When U S (t) reaches the action voltage of the air gap switch S, the air gap switch S is broken down and turned on, and the schematic diagram of the voltage waveform is as shown in Figure 5 Since the rated voltage of the intermediate bridge valve group R3 is only one fifth to one fourth of the rated voltage of the arrester controllable part R2, the arrester controllable part R2 is in a failure state at this time, and the operating and lightning overvoltage can flow into the ground through the path composed of the arrester fixed part R1, the intermediate bridge valve group R3 and the air gap switch S. Figure 5It can be seen that the air gap switch S can act quickly when the overvoltage comes, so as to timely cut off the controllable part R2 of the arrester, and effectively suppress the overvoltage.

[0062] In the embodiment, when U S When the operating voltage of the air gap switch S is 300 kV, the voltage across the high-voltage part C1 of the bypass capacitor is 750 kV, that is, the air gap switch S can act when the operating overvoltage of 750 kV exists. In this way, even if the action of the air gap switch S has dispersion, when the overvoltage of 1000 kV or above comes, the controllable arrester can be conducted in any case. It should be noted that, generally, when the overvoltage (operating overvoltage or lightning overvoltage) of the extra-high voltage equipment occurs, the overvoltage can reach 1000 kV or above.

[0063] If the bypass capacitor is not arranged in the controllable arrester (the middle bridge valve group also does not need to be arranged), that is, the air gap switch is directly connected in parallel with the controllable part of the arrester. In this case, if the rated voltages of the fixed part and the controllable part of the arrester are the same as those in the above embodiment, that is, 1000 kV and 250 kV respectively, and the operating voltage of the air gap switch is set to 250 kV (if it is still 300 kV, the controllable part of the arrester will be conducted to 250 kV, and the switch cannot function), in this way, only when the voltage of the entire controllable arrester reaches 1250 kV, the air gap switch can be conducted, if the dispersion of the action of the air gap switch is considered, the air gap switch can be conducted when the voltage reaches 1260 kV. In this way, for the overvoltage below 1260 kV, the controllable arrester cannot effectively suppress the overvoltage. Therefore, compared with this design, the controllable arrester based on the self-triggering air gap switch provided in the embodiment can make the air gap switch S act in advance, and prepare for the overvoltage, so as to ensure that the overvoltage is effectively suppressed.

[0064] The controllable arrester based on the self-triggering air gap switch in the above embodiment is composed of all passive devices, the short circuit of the controllable part of the arrester is realized through the cooperation of electrical parameters, the protection action of the overvoltage can be timely performed, the influence of the dispersion of the action of the air gap switch is avoided, and the overvoltage of the extra-high voltage operation and lightning strike is ensured to be in a safe range. The controllable arrester does not need a complex control system, has few devices and a simple structure. Compared with the existing controllable arrester, the use of a large number of secondary devices such as measurement, control and triggering is avoided, and the reliability of the arrester is significantly improved.

[0065] In the above embodiments, the description of each embodiment has its own emphasis, and the part not described or recorded in a certain embodiment can be referred to the related description of other embodiments.

[0066] The above-described embodiments are only used to illustrate the technical solutions of the present application, and are not intended to limit the present application; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that: it can still modify the technical solutions recorded in the foregoing embodiments, or make equivalent replacement for part of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application, and should be included in the protection scope of the present application.

Claims

1. A controllable surge arrester based on an autonomously triggered air-gap switch, characterized in that The device comprises a lightning arrester fixed part, a lightning arrester controllable part, a bypass capacitor high-voltage part, a bypass capacitor low-voltage part, an air gap switch and an intermediate bridge valve group; wherein the intermediate bridge valve group is a lightning arrester; One end of the lightning arrester fixed part is connected with one end of the bypass capacitor high-voltage part, and the other end of the lightning arrester fixed part is connected with one end of the lightning arrester controllable part and one end of the intermediate bridge valve group respectively; the other end of the intermediate bridge valve group is connected with the other end of the bypass capacitor high-voltage part and one end of the bypass capacitor low-voltage part respectively; the other end of the lightning arrester controllable part is connected with the other end of the bypass capacitor low-voltage part and grounded; the air gap switch is connected with the bypass capacitor low-voltage part in parallel; wherein the ratio of the capacitance of the bypass capacitor low-voltage part to the bypass capacitor high-voltage part is less than the ratio of the rated voltage of the lightning arrester fixed part to the lightning arrester controllable part. The end of the lightning arrester fixed part and the bypass capacitor high-voltage part is used for connecting a power transmission line; when the length of the power transmission line is greater than a first preset length and less than or equal to a second preset length, the ratio of the rated voltage of the lightning arrester controllable part increases with the increase of the length of the power transmission line; 2. The controllable surge arrester based on an autonomous triggered gas gap switch according to claim 1, characterized in that, The ratio of the rated voltage of the lightning arrester controllable part is the percentage of the rated voltage of the lightning arrester controllable part in the total rated voltage of the controllable lightning arrester; the total rated voltage of the controllable lightning arrester is the sum of the rated voltage of the lightning arrester fixed part and the rated voltage of the lightning arrester controllable part. The ratio of the rated voltage of the lightning arrester controllable part ranges from 20% to 25%.

3. The controllable surge arrester based on an autonomous triggered gas gap switch according to claim 2, characterized in that, The end of the lightning arrester fixed part and the bypass capacitor high-voltage part is used for connecting a power transmission line; when the length of the power transmission line is less than or equal to a first preset length, the ratio of the rated voltage of the lightning arrester controllable part is a first preset percentage; 4. The controllable surge arrester based on an autonomous triggered gas gap switch according to claim 1, characterized in that, When the length of the power transmission line is greater than the first preset length and less than or equal to a third preset length, the ratio of the rated voltage of the lightning arrester controllable part is a second preset percentage; When the length of the power transmission line is greater than the third preset length and less than or equal to a second preset length, the ratio of the rated voltage of the lightning arrester controllable part is a third preset percentage; The ratio of the rated voltage of the lightning arrester controllable part is the percentage of the rated voltage of the lightning arrester controllable part in the total rated voltage of the controllable lightning arrester; the total rated voltage of the controllable lightning arrester is the sum of the rated voltage of the lightning arrester fixed part and the rated voltage of the lightning arrester controllable part. The first preset length is 250km, the third preset length is 300km, and the second preset length is 350km; 5. The controllable surge arrester based on an autonomously triggered gas gap switch according to claim 4, characterized in that The first preset percentage is 20%, the second preset percentage is 22%, and the third preset percentage is 25%. The power transmission line is an extra-high voltage power transmission line or an ultra-high voltage power transmission line.

6. A controllable surge arrester based on an autonomously triggered gas gap switch according to any of claims 2 to 5, characterized in that The ratio of the capacitance of the bypass capacitor low-voltage part to the bypass capacitor high-voltage part is 0.5 times of a first ratio; 7. A controllable surge arrester based on an autonomous triggered gas gap switch according to any of claims 1 to 5, characterized in that, ​ The first ratio is a ratio of rated voltages of the fixed part of the surge arrester and the controllable part of the surge arrester.

8. A controllable surge arrester based on an autonomous triggered gas gap switch according to any of claims 1 to 5, characterized in that, The operating voltage of the air gap switch is a preset multiple of the rated voltage of the controllable part of the surge arrester, and the preset multiple is greater than 1 and less than 2.

9. The controllable surge arrester based on an autonomous triggered gas gap switch according to any of claims 1 to 5, characterized in that, The rated voltage of the intermediate bridge valve plate group is 5% of a sum of the rated voltages of the fixed part of the surge arrester and the controllable part of the surge arrester.

10. The controllable surge arrester based on an autonomous triggered gas gap switch according to claim 1, characterized in that, The fixed part of the surge arrester and the controllable part of the surge arrester are both metal oxide surge arrester valve plates.

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