WO2021103017A1 - 一种直流输电线路雷击闪络限制方法 - Google Patents

一种直流输电线路雷击闪络限制方法 Download PDF

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Publication number
WO2021103017A1
WO2021103017A1 PCT/CN2019/122219 CN2019122219W WO2021103017A1 WO 2021103017 A1 WO2021103017 A1 WO 2021103017A1 CN 2019122219 W CN2019122219 W CN 2019122219W WO 2021103017 A1 WO2021103017 A1 WO 2021103017A1
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Prior art keywords
lightning
state
isolation device
protection circuit
event
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PCT/CN2019/122219
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English (en)
French (fr)
Inventor
谷山强
王剑
万帅
曹伟
陈家宏
谭进
赵淳
方玉河
刘新
杜雪松
王智凯
Original Assignee
国网电力科学研究院武汉南瑞有限责任公司
国家电网有限公司
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Priority to PCT/CN2019/122219 priority Critical patent/WO2021103017A1/zh
Publication of WO2021103017A1 publication Critical patent/WO2021103017A1/zh

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01C—RESISTORS
    • H01C7/00—Non-adjustable resistors formed as one or more layers or coatings; Non-adjustable resistors made from powdered conducting material or powdered semi-conducting material with or without insulating material
    • H01C7/10—Non-adjustable resistors formed as one or more layers or coatings; Non-adjustable resistors made from powdered conducting material or powdered semi-conducting material with or without insulating material voltage responsive, i.e. varistors
    • H01C7/12—Overvoltage protection resistors
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01T—SPARK GAPS; OVERVOLTAGE ARRESTERS USING SPARK GAPS; SPARKING PLUGS; CORONA DEVICES; GENERATING IONS TO BE INTRODUCED INTO NON-ENCLOSED GASES
    • H01T1/00—Details of spark gaps
    • H01T1/16—Series resistor structurally associated with spark gap
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
    • H02H3/00—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection
    • H02H3/20—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection responsive to excess voltage
    • H02H3/22—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection responsive to excess voltage of short duration, e.g. lightning

Definitions

  • This application relates to the technical field of lightning protection for power systems, in particular to a lightning flashover limitation method for DC transmission lines.
  • DC transmission lines have developed rapidly around the world due to their large transmission capacity and unrestricted transmission distance.
  • China’s three major UHV DC transmission lines from Southwest to East my country have been completed and put into operation, with an annual transmission power of 189.2 billion kWh, equivalent to more than 90% of Shanghai’s annual power consumption. Therefore, the safe and stable operation of DC transmission lines has been ensured.
  • the embodiment of the present application provides a method for limiting the lightning flashover of a DC transmission line, which can reasonably release the energy of the lightning signal at least when there is a lightning strike on the DC transmission line, which can effectively ensure the safe operation of the DC transmission line.
  • the embodiment of the present application provides a method for limiting the lightning flashover of a DC transmission line, and the method includes:
  • the first event is characterized as an event in which the transmission line is struck by lightning;
  • the isolation device that controls the lightning flashover limiter is in an abnormal state, and the abnormal state is a state in which the isolation device is broken down by the lightning;
  • the protection circuit that controls the lightning flashover limiter is in a low resistance state
  • At least most of the energy generated by the lightning strike is released through the protection circuit in a low resistance state.
  • the isolation device is in a normal state; the protection circuit is in a high-impedance state;
  • the isolation device When the first event is detected, the isolation device is switched from a normal state to an abnormal state and the protection circuit is switched from a high-impedance state to a low-impedance state.
  • the method further includes:
  • the protection circuit is switched from a low resistance state to a high resistance state, and the isolation device is switched from an abnormal state to a normal state.
  • the method further includes:
  • the line insulation is in a normal state
  • the line insulator in the normal state can protect the power transmission line.
  • the method before detecting the first event, the method further includes:
  • the operating parameters of the isolation device, the protection circuit and/or the line insulator are adjusted.
  • the adjustment of the working parameters of the isolation device, the protection circuit and/the line insulator includes at least:
  • the working parameters include lightning impulse discharge voltage
  • the adjustment of the working parameters of the isolation device, the protection circuit and/the line insulator includes at least:
  • the working parameters include DC withstand voltage
  • Adjust the DC withstand voltage of the isolation device to be greater than the highest operating voltage of the DC power transmission system.
  • the protection circuit is wrapped by an outer insulating member, and the method further includes:
  • the adjusting the working parameters of the outer insulator includes:
  • the switching the isolation device from an abnormal state to a normal state includes:
  • the isolation device When the second event is detected, the isolation device is switched from the abnormal state to the normal state, wherein the second event is characterized as the DC freewheeling of the isolation device is extinguished.
  • the embodiment of the application provides a method for limiting the lightning flashover of a DC transmission line, wherein the method is applied to a lightning flashover limiter, the lightning flashover limiter includes at least a protection circuit and an isolation device, and the method includes: detection In the case of a first event, the first event is characterized as an event in which a transmission line is struck by lightning; controlling the isolation device to be in an abnormal state, and the abnormal state is a state in which the isolation device is broken down by the lightning; When the isolation device is in an abnormal state, the protection circuit that controls the lightning flashover limiter is in a low resistance state; at least most of the energy generated by the lightning strike is released through the protection circuit in a low resistance state.
  • the isolation device that controls the lightning flashover limiter when the transmission line is struck by lightning, the isolation device that controls the lightning flashover limiter is in an abnormal state, and the control protection circuit is in a low resistance state.
  • the energy generated by the lightning lightning signal energy such as lightning current At least most of the energy can be released by a protection circuit in a low-impedance state.
  • the lightning signal energy can be released in time to avoid the lightning overvoltage of the entire transmission line, effectively prevent the lightning flashover phenomenon of the line insulation, and ensure the safe operation of the DC transmission line.
  • FIG. 1 is a schematic diagram of the design of a lightning flashover limiter and line insulator on a DC transmission line provided by an embodiment of the application;
  • FIG. 2 is an implementation flowchart of a method for limiting lightning flashover of a DC transmission line according to an embodiment of the application;
  • FIG. 3 is another implementation flow chart of the lightning flashover limitation method for DC transmission lines provided by an embodiment of the application
  • FIG. 4 is a schematic diagram of the lightning shielding lightning resistance level of a typical DC transmission project before and after the lightning flashover limit provided by an embodiment of the application;
  • Fig. 5 is a nonlinear volt-ampere characteristic curve of a high-performance DC zinc oxide resistor provided by an embodiment of the application.
  • the embodiment of the application provides a method for limiting the lightning flashover of a DC transmission line, which is applied to a DC transmission system, and is specifically applied to the lightning flashover limiter provided in the embodiment of the application (for convenience of description, the following abbreviated as the limiter).
  • the design of the DC transmission line limiter and line insulators of the DC transmission system is shown in Figure 1.
  • the transmission wires are suspended on the poles or towers through line insulators to avoid potential safety hazards caused by the landing of the transmission wires.
  • a limiter is installed on the pole or tower, and the limiter includes an isolation device and a protection circuit connected in series.
  • the isolation device in the embodiment of the present application has at least the following two functions: (1) In the presence of a lightning strike, the isolation device prioritizes the breakdown of the line insulation so that the protection circuit releases the lightning strike energy in time, thereby avoiding line insulation The parts are affected by lightning strikes. (2) The purpose of preventing the voltage on the transmission wire from being loaded on the protection circuit is equivalent to isolating the voltage on the transmission wire from acting on the protection circuit. From the schematic view, the content shown in Figure 1 can be understood as follows: one end of the pole or tower is grounded, and the other end is in the air, and the line insulator and limiter are connected in parallel between the tower (or tower) and the transmission wire.
  • the line insulating parts In order to avoid lightning flashover and protect the insulation of transmission lines, it is necessary to protect the line insulating parts, at least in the presence of lightning strikes, to protect them from lightning flashover so as to realize the normal protection function of the line insulating parts.
  • the purpose of the embodiments of the present application is how to protect the line insulator through the action of the limiter of the embodiments of the present application in the case of a lightning strike. It can be understood that, in addition to the limiter provided in the embodiment of the present application, the aforementioned DC power transmission system also includes converter stations, power transmission lines, and the like.
  • the method for limiting the lightning flashover of the DC transmission line provided by the embodiment of the present application is applied to the limiter. As shown in Figure 2, it includes:
  • Step S201 In a case where a first event is detected, the first event is characterized as an event in which the transmission line is struck by lightning;
  • S203 When the isolation device is in an abnormal state, control the protection circuit to be in a low resistance state; wherein the abnormal state is a state where the isolation device is broken down by the lightning;
  • the isolation device when the transmission line is struck by lightning, the isolation device is controlled to be in an abnormal state, and the protection circuit is controlled to be in a low resistance state.
  • the energy generated by the lightning strike (lightning signal energy such as lightning current energy) can be at least mostly Release through a protection circuit in a low-impedance state.
  • the lightning signal energy is released through the protection circuit to avoid lightning overvoltage across the transmission line, effectively prevent the lightning flashover phenomenon of the line insulation of the DC transmission line, and thereby ensure the safe operation of the DC transmission line.
  • the line insulation when the lightning signal energy is released through the protection circuit, the line insulation can be in a normal state; the line insulation in the normal state performs a normal protection function for the transmission line.
  • the line insulating member will not be affected by the lightning signal, and it can be ensured that it is in a normal state, thereby realizing the normal protection function of the power transmission wire.
  • the lightning strike signal energy can be reasonably released through the protection circuit, effectively limiting the line insulation
  • the lightning overvoltage at both ends of the component prevents lightning overvoltage across the entire transmission line, effectively prevents lightning flashover on the line insulation of the DC transmission line, and thereby ensures the safe operation of the DC transmission line.
  • the isolation device when the first event is not detected, the isolation device is in a normal state; the protection circuit is in a high-impedance state; when the first event is detected, the isolation device is in a high-impedance state; The isolation device is switched from a normal state to an abnormal state and the protection circuit is switched from a high resistance state to a low resistance state.
  • the isolation device when the DC transmission line is not struck by lightning, the isolation device is in a normal state, and the protection circuit is in a high-impedance state (the normal state of the protection circuit). In the case of a lightning strike, the isolation device is switched from a normal state to an abnormal state, and the protection circuit is switched from a high-impedance state to a low-impedance state.
  • the status of the protection circuit and the isolation device can be determined, so that the limiter can be maintained in a normal working state without being subjected to a lightning strike, and in the case of a lightning strike. It can release the lightning signal energy, thereby limiting the lightning overvoltage at both ends of the line insulator in the case of lightning strikes, effectively preventing the lightning flashover phenomenon of the line insulators on the DC transmission line, and ensuring the normal operation of the system.
  • the method further includes: switching the protection circuit from a low resistance state to a high resistance state. Blocking state, and switching the isolation device from an abnormal state to a normal state. That is, after most of the lightning strike signal energy is released through the protection circuit, it is also necessary to switch the protection circuit from a low resistance state to a high resistance state and restore the isolation device to a normal state. After most of the lightning signal energy is released, the limiter can be quickly switched back to the normal working state to prevent the sudden arrival of the next lightning and ensure the safe operation of the DC transmission system.
  • the switching of the isolation device from the abnormal state to the normal state includes: when the isolation device is in an abnormal state, when a second event is detected, isolating the isolation device The device is switched from an abnormal state to a normal state, wherein the second event is characterized as the DC freewheeling of the isolation device is extinguished.
  • the isolation device can be switched from an abnormal state to a normal state. To ensure that the limiter quickly switches back to the normal working state.
  • the isolation device in order to realize that the isolation device is first broken down by lightning, the line insulation is not broken down by lightning, and the protection circuit can be performed when the isolation device is first broken down by lightning.
  • the isolation device In order to adjust from the high resistance state to the low resistance state, before using the DC transmission system as shown in FIG. 1, it is also necessary to adjust the operating parameters of at least one of the isolation device, the protection circuit, and the line insulator.
  • the working parameters and their adjustments include at least the following: the working parameters include the lightning impulse discharge voltage; adjusting the lightning impulse discharge voltage of the limiter Less than the lightning impulse discharge voltage of the line insulator; wherein the lightning impulse discharge voltage of the limiter is the sum of the lightning impulse discharge voltage of the isolation device and the protection circuit.
  • the lightning impulse discharge voltage of the adjustable limiter is less than 0.85 times the lightning impulse discharge voltage of the line insulation.
  • the operating parameters may also include a DC withstand voltage; adjusting the DC withstand voltage of the isolation device to be greater than the highest operating voltage of the DC transmission system. Further, the ratio of the DC withstand voltage of the isolation device to the highest operating voltage of the DC power transmission system is adjusted to be at least greater than 1. Among them, the maximum operating voltage of the DC transmission system can be considered as the maximum voltage that can ensure the normal operation of the DC transmission system.
  • the limiter further includes an outer insulating member for wrapping the protection circuit; adjusting working parameters also includes adjusting the working parameters of the outer insulating member. Further, adjusting the DC withstand voltage of the outer insulator to be greater than the highest operating voltage of the DC power transmission system; and adjusting the lightning impulse withstand voltage of the outer insulator to be greater than the voltage at both ends of the protection circuit in a low resistance state.
  • the ratio of the DC withstand voltage of the external insulator to the maximum operating voltage of the DC power transmission system is adjusted to be at least greater than 1.2. Adjust the ratio of the lightning impulse withstand voltage of the external insulator to the voltage at both ends of the protection circuit in a low-resistance state at least greater than 1.4.
  • the limiter in the embodiment of the present application may be specifically a lightning arrester.
  • the line insulator can be an insulator string or an air gap at the tower head. Taking the protection circuit as a non-linear resistance element, the isolation device as the external series gap of the arrester, and the line insulator as an insulator string as an example, the solution of the embodiment of the present application will be further described.
  • the insulator string is a preferred way of line insulators
  • the non-linear resistance element is a preferred way of protecting the circuit.
  • the series gap is a preferred way of isolating the device.
  • the external series gap In the case of not being struck by lightning, the external series gap is in the normal state (insulated state, equivalent to an open circuit state), and the non-linear resistance element is in a high resistance state (the normal state of the non-linear resistance element), which is equivalent to the lightning arrester being unused status.
  • the insulator string suspends the transmission wire on the pole or iron tower.
  • the arrester In the event of a lightning strike, the arrester is switched from the unused state to the used state. Furthermore, since the lightning impulse discharge voltage of the pre-adjusted arrester is lower than the lightning impulse discharge voltage of the insulator string, compared with the insulator string, the outer series gap of the arrester is the first to be broken down by lightning, which is equivalent to switching the outer series gap from the open state To the short-circuit state (switching from the insulated state to the conducting state), the series non-linear resistance element is immediately activated, and the non-linear resistance element is controlled to switch from the high resistance state to the low resistance state, that is, the non-linear resistance element is controlled to switch from the normal state to the low resistance state. Abnormal state.
  • switching the external series gap to the short-circuit state is equivalent to the non-linear resistance element is directly connected to the transmission wire, and the lightning current energy on the transmission wire is transferred to the non-linear resistance element in the low resistance state.
  • the lightning current energy is transmitted into the ground via the pole or iron tower to realize the timely and reasonable release of the lightning current energy on the transmission line.
  • the energy of the mine current transmitted from the non-linear resistance element via the pole or iron tower is the majority of the energy of the lightning current, such as 70%-80% of the lightning current energy.
  • the non-linear resistance element also absorbs lightning current energy.
  • the external series gap is broken down by lightning, causing arcs to appear at both ends of the external series gap, and the non-linear resistance element is extinguished.
  • the non-linear resistance element extinguishes the DC freewheeling in the external series gap
  • the non-linear resistance element switches back from the low resistance state In the high-impedance state, the external series gap restores the insulation state.
  • the external series gap is controlled to be in a short-circuit state and the non-linear resistance element is in a low resistance state.
  • the lightning signal energy can be transmitted to the ground through the non-linear resistance element and be reasonably released .
  • the above use process of the lightning arrester can effectively limit the lightning overvoltage at both ends of the insulator string, prevent the lightning flashover phenomenon of the insulator string of the DC transmission line, and thereby ensure the safe operation of the DC transmission line.
  • the external series gap returns to the insulating state (the normal state of the external series gap), and the non-linear resistance element switches from the low resistance state back to the high resistance state (the non-linear resistance element's normal state).
  • Normal state that is, the lightning arrester returns to the normal state to prevent the sudden arrival of the next lightning strike and ensure the safe operation of the DC transmission system.
  • the non-linear resistance element can reliably extinguish the DC freewheeling of the outer series gap within 10ms, that is, the effect of extinguishing the DC freewheeling of the outer series gap can be achieved in a short time.
  • the time for extinguishing the DC freewheeling of the outer series gap is relatively short, so that the arrester can quickly return to a normal state, so as to prevent the next lightning strike and ensure the safe operation of the DC transmission system.
  • the time of extinguishing the DC freewheeling of the external series gap is much shorter than the de-freeing time of the DC transmission system fault restart of 150-500ms. In this way, the impact of lightning strikes on the DC transmission system can be solved without restarting the DC transmission system, and the application protection of the lightning arrester can be reliably coordinated with the safe operation of the DC transmission project.
  • the magnitude of the return lightning current meets the conditions for the occurrence of shielding in the fault section of the DC transmission line (the dangerous lightning current area is 30 ⁇ 60kA).
  • the DC transmission system is blocked after two restarts .
  • pole I After the arc de-free time of 198ms (20:29:31.469), pole I starts the second full pressure and restarts. Since 20:29:31.180 serial number 5 (the time from the second de-freezing time is 289ms), lightning hits the pole I wire, which again caused insufficient arc de-freezing, causing the pole I to fail the second full-voltage restart. According to the stipulation The protection strategy needs to block pole I.
  • the duration of each dissociation in the aforementioned scheme (the duration of the first dissociation and the duration of the second dissociation) is fixed, the traditional method of optimizing the overhead ground wire cannot be used in a short time.
  • the lightning current is released, and the above locking scheme has to be adopted.
  • the lightning arrester After adopting the lightning arrester in the embodiment of the present application, if multiple short-time interval lightning discharges are generated before and after the same lightning channel, for each lightning discharge, the lightning arrester can release it in time to make the protection circuit and The isolation device can quickly switch from the state of releasing the lightning current to the normal state to prepare for the next lightning strike and release the energy in time.
  • the protection circuit in the embodiment of the application can extinguish the DC freewheeling of the external series gap within 10ms, that is, the effect of extinguishing the DC freewheeling of the external series gap can be achieved in a short time, so that The arrester can quickly switch back to the normal state when releasing most of the lightning current to realize the timely release of the current generated by the next lightning strike.
  • the time for the non-linear resistance element to extinguish the DC freewheeling of the outer series gap is much shorter than the de-freeing time of the DC transmission system for fault restart of 150-500 ms. In this way, there is no need to restart the DC transmission system or lockout, thereby avoiding the problem that the system cannot be used normally due to restarting and locking, and realizing the reliable cooperation between the application protection of the lightning arrester and the safe operation of the DC transmission project.
  • Fig. 4 is a schematic diagram of the shielding lightning resistance level of the DC transmission line before and after lightning flashover limitation is performed by using the embodiment of the present application.
  • the tower within the range of lightning current amplitude of 0 ⁇ 150kA, for a typical 500kV tower, there is a dangerous lightning current zone in the range of about 22 ⁇ 37kA, that is, in the range of lightning current of 22 ⁇ 37kA, The tower has poor lightning resistance.
  • For a typical 800kV tower there is a dangerous lightning current area in the range of approximately 30-60kA, that is, within the range of 30-60kA, the tower has poor lightning resistance.
  • the above lightning arresters of the embodiments of the present application are added, there is no area with poor lightning resistance level.
  • I The amplitude of lightning current, kA
  • Figure 4 only takes the lightning current amplitude of 0 ⁇ 150kA as an example.
  • the calculation of the above formula (1) shows that the lightning current amplitude exceeds The probability of 150kA is 1.05%.
  • the probability of lightning current amplitude exceeding 150kA is as small as 0.0105.
  • the solutions provided in the embodiments of the present application mainly take into account the actual occurrence in nature, but it does not mean that the solutions provided in the embodiments of the present application cannot be applied to the situation where the lightning current amplitude exceeds 150kA. It can be seen that the solution provided by the embodiment of the present application has strong practicability, high feasibility, and is easy to implement in engineering.
  • the lightning resistance level of different types of poles or towers can be improved, thereby being able to better resist lightning strikes, thereby ensuring the normal operation of the DC power transmission system.
  • the insulator string can also be realized by the air gap of the tower head;
  • the nonlinear component can be realized by any device that can realize the free conversion of high impedance and low impedance;
  • the isolation device can be any device that can realize isolation.
  • the external series gap of the acting device such as the lightning arrester is a pure air series gap.
  • the non-linear resistance element is a high-performance device with excellent non-linear volt-ampere characteristics.
  • the non-linear resistance element can be a zinc oxide resistor chip.
  • the choice of zinc oxide resistors is mainly due to its excellent non-linear volt-ampere characteristics.
  • the excellent nonlinear volt-ampere characteristics can be seen in Figure 5.
  • the abscissa unit is ampere A/mm 2
  • the ordinate changes from 150 to 400.
  • the abscissa is in the middle position, such as 0.01 to 5 coordinates, the value of the ordinate changes slowly.
  • the change in the ordinate is much smaller than the change in the abscissa. If the abscissa changes 100 times, the ordinate changes 2 times. Devices with such volt-ampere characteristics can be used as the non-linear resistance element in the embodiments of the present application.
  • the non-linear resistance element can be composed of a DC zinc oxide resistor with the above non-linear volt-ampere characteristics, which can prevent the interstitial zinc ions on the reverse Schottky barrier side from being Migration to the grain boundary layer under the action of DC voltage causes the height of the Schottky barrier to decrease, which makes the zinc oxide resistors have higher aging performance, which makes the arrester less prone to aging, and the anti-aging performance of the arrester is significantly improved, making the arrester more effective. Use longer.
  • the DC zinc oxide resistor when the DC zinc oxide resistor is in normal operation, the leakage current is at the microampere level and is in a high resistance state.
  • the non-linear resistance element starts, and the voltage at both ends of it increases only slightly (about 2 times), while the current increases by 5 to 6 orders of magnitude, and it is in a low resistance state.
  • the above is an explanation of the excellent non-linear volt-ampere characteristics of the zinc oxide resistor when it is used as a non-linear resistance element.
  • any components, components, etc. having the same or similar non-linear volt-ampere characteristics as in FIG. 5 can be used as the non-linear resistance element of the embodiment of the present application, and are not limited to the zinc oxide resistor chip.
  • the working parameters of the external series gap and the nonlinear resistance element in the arrester need to be adjusted until they are adjusted to the expected level.
  • the lightning arrester adjusted by working parameters can play a better lightning protection effect in the presence of lightning, effectively limit the lightning overvoltage at both ends of the insulator string, prevent the lightning flashover phenomenon of the insulator string of the DC transmission line, and thus ensure the DC Safe operation of transmission lines.
  • the first step is to adjust the external series gap of the arrester, and calculate the ratio of the DC withstand voltage of the external series gap of the arrester to the highest operating voltage of the system.
  • the DC withstand voltage of the outer series gap of the arrester is adjusted.
  • the adjustment may be to increase the DC withstand voltage of the outer series gap from the initial setting value in a certain step.
  • the initial set value of the outer series gap distance is 1000mm, with a step of 50mm, the outer series gap distance is increased, and then the DC withstand voltage of the outer series gap is increased.
  • the ratio of the adjusted DC withstand voltage of the external series gap to the highest operating voltage of the system is calculated.
  • the third step can be moved to; otherwise, the external series gap of the arrester needs to be optimized and adjusted.
  • adjusting the ratio of the DC withstand voltage of the external series gap to the maximum operating voltage of the system is greater than 1, and it can be considered that the external series gap can still withstand the maximum operating voltage of the system when the nonlinear resistance element has a short-circuit fault, and will not affect the DC transmission system. Normal operation.
  • the third step is to adjust the matching relationship between the external series gap of the arrester and the non-linear resistance element according to the insulation configuration of the line insulator, and calculate the ratio of the lightning impulse discharge voltage of the arrester to the lightning impulse discharge voltage of the line insulator.
  • the outer series gap of the arrester will be broken down first, and the arrester will not be able to discharge energy due to the failure of the outer series gap. Damage to the line insulation, which affects the normal operation of the DC transmission system.
  • the lightning resistance level of line insulators such as lightning impulse discharge voltage, is required to increase or decrease the coordination relationship between the external series gap and the non-linear resistance element to ensure that the external series gap is broken down first in the event of a lightning strike, which means that the In the event of a lightning strike, the arrester can discharge energy.
  • the fifth step is to adjust the external insulation configuration of the arrester according to the voltage at both ends of the non-linear resistance element when it is started, and calculate the ratio of the lightning impulse withstand voltage of the external insulation to the voltage at both ends of the series non-linear resistance element when it starts.
  • the outside of the non-linear resistance element needs to include insulation (referred to as the external insulation of the arrester).
  • the external insulation also needs to be able to withstand lightning strikes. Adjust (increase or decrease) the lightning impulse withstand voltage of the external insulation of the arrester according to the voltage at both ends of the non-linear resistance element when it is started, and according to factors such as the material and model of the external insulating material.
  • the ratio between the lightning impulse withstand voltage of the external insulation and the voltage at both ends of the non-linear resistance element is greater than 1.4 when the non-linear resistance element is started, it is considered to be adjusted to the ideal level and go to the seventh step; otherwise, the external insulation configuration of the arrester needs to be optimized and adjusted.
  • the seventh step is to adjust the external insulation configuration of the arrester, and calculate the ratio of the DC withstand voltage of the external insulation to the highest operating voltage of the system.
  • the outer insulation of the arrester can be made of silicone rubber composite jacket material.
  • the external insulation of this material is relatively light, and on the other hand, even if the lightning arrester fails, it will not pose a threat to the surrounding equipment and personal safety.
  • the non-linear resistance element can reliably extinguish the DC freewheeling of the external series gap of the arrester within 10ms, that is, the effect of extinguishing the DC freewheeling of the external series gap can be achieved in a short time.
  • the time of extinguishing the DC freewheeling of the outer series gap is much shorter than the de-freeing time of the DC transmission system when it is restarted after a fault is 150-500 ms. In this way, the impact of lightning strikes on the DC transmission system can be solved without restarting the DC transmission system, and the application protection of the lightning arrester and the safe operation of the DC transmission project can be reliably coordinated.
  • the isolation device By adjusting the lightning impulse discharge voltage of the isolation device, it is ensured that the isolation device is first broken down by lightning in the case of a lightning strike, so as to ensure that the line insulation is not broken down. And by switching the protection circuit from high resistance to low resistance, most of the lightning current energy is transmitted to the ground via the protection circuit, which is also reasonably released. It effectively limits the lightning overvoltage at both ends of the line insulation, avoids the lightning overvoltage of the entire transmission line, and effectively prevents the lightning flashover phenomenon of the line insulation on the DC transmission line, thereby ensuring the safe operation of the DC transmission line.
  • the protection circuit and the isolation device are combined to realize the cut-off of DC freewheeling. Due to the isolation of the isolation device, the protection circuit is not charged during normal operation of the limiter, which can avoid the aging of the protection circuit.
  • the protection circuit can reliably extinguish the DC freewheeling of the isolation device within 10ms, and the lightning flashover arc extinguishing time is much shorter than the restarting action time of the protection device of the DC transmission system. It is suitable for the lightning protection of the DC transmission line and can effectively protect the DC transmission. Safety and stability of line operation.
  • this application can be provided as methods, systems, or computer program products. Therefore, this application may adopt the form of hardware embodiments, software embodiments, or embodiments combining software and hardware. Moreover, this application may adopt the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, optical storage, etc.) containing computer-usable program codes.
  • These computer program instructions can also be stored in a computer-readable memory that can direct a computer or other programmable data processing equipment to work in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture including the instruction device.
  • the device implements the functions specified in one process or multiple processes in the flowchart and/or one block or multiple blocks in the block diagram.
  • These computer program instructions can also be loaded on a computer or other programmable data processing equipment, so that a series of operation steps are executed on the computer or other programmable equipment to produce computer-implemented processing, so as to execute on the computer or other programmable equipment.
  • the instructions provide steps for implementing the functions specified in one process or multiple processes in the flowchart and/or one block or multiple blocks in the block diagram.
  • the isolation device that controls the lightning flashover limiter when the transmission line is struck by lightning, the isolation device that controls the lightning flashover limiter is in an abnormal state, and the control protection circuit is in a low resistance state.
  • the energy generated by the lightning lightning signal energy such as lightning current At least most of the energy can be released by the protection circuit in a low resistance state.
  • the lightning signal energy can be released in time to avoid lightning overvoltage across the transmission line, effectively prevent the lightning flashover phenomenon of the line insulation, and ensure the safe operation of the DC transmission line.
  • the isolation device by adjusting the lightning impulse discharge voltage of the isolation device, it is ensured that the isolation device is first broken down by lightning in the case of a lightning strike, so that it can ensure that the line insulation is not broken down. And by switching the protection circuit from high resistance to low resistance, most of the lightning current energy is transmitted to the ground via the protection circuit, which is also reasonably released. Avoid the lightning overvoltage across the entire transmission line, effectively limit the lightning overvoltage at both ends of the line insulation, effectively prevent the lightning flashover phenomenon of the line insulation on the DC transmission line, and ensure the safe operation of the DC transmission line.

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Abstract

一种直流输电线路雷击闪络限制方法，包括：检测到第一事件的情况下，第一事件表征为输电线路遭到雷击的事件（S201）；控制雷击闪络限制器的隔离装置为异常状态（S202），该异常状态为所属隔离装置被雷击击穿的状态；在隔离装置处于异常状态的情况下，控制雷击闪络限制器的保护电路为低阻状态（S203），雷击产生的能量至少大部分通过处于低阻状态的保护电路进行释放（S204）。

Description

一种直流输电线路雷击闪络限制方法 技术领域
本申请涉及电力系统雷电防护技术领域，尤其是指对直流输电线路的雷击闪络限制方法。
背景技术
近年来，直流输电线路因其输送容量大、输送距离不受限制等特点，在全球得到了高速发展，在建及投运±400kV～±1100kV直流输电线路近50余条，特别是在中国、印度、巴西、巴基斯坦、加拿大、美国等国家，越来越多的国家建立了直流跨区大电网，其在电网中的资源配置作用以及对电网安全稳定运行的影响也更为显著。例如：我国建成投运的西南—华东三大特高压直流输电线路，年输送电量高达1892亿千瓦时，相当于上海市全年90％以上的用电量，因此确保直流输电线路安全稳定运行已成为我国大电网运行维护工作的首要任务。而对直流输电线路侵袭最频繁、冲击最强烈的自然因素是自然界中的雷电。为保证直流输电线路的正常运行，相关技术中多采用对架空地线进行优化的方式来提升直流输电线路的耐雷水平。这种方法虽然可在一定程度上解决大部分雷击故障问题，但是由于土地资源稀缺，直流输电线路往往远离城市而穿越崇山峻岭、雷电活动频繁的地区。位于这些地区的直流输电线路容易遭受到雷电的攻击，导致雷击故障，无法保证电网运行的稳定性。可见，相关技术中的防雷措施无法解决雷击给直流输电线路造成的影响、特别是多重雷击造成线路绕击闪络的局限性愈加凸显，无法满足直流输电路线的雷电防护需求。
发明内容
本申请实施例提供了一种直流输电线路雷击闪络限制方法，至少在直 流输电线路存在雷击的情况下使得雷击信号的能量得以合理释放，可有效保证直流输电线路的安全运行。
本申请实施例的技术方案如下：
本申请实施例提供一种直流输电线路雷击闪络限制方法，所述方法包括：
检测到第一事件的情况下，所述第一事件表征为输电线路遭到雷击的事件；
控制雷击闪络限制器的隔离装置为异常状态，所述异常状态为所述隔离装置被所述雷击击穿的状态；
在所述隔离装置处于异常状态的情况下，控制雷击闪络限制器的保护电路为低阻状态；
所述雷击产生的能量至少大部分通过处于低阻状态的所述保护电路进行释放。
上述方案中，在未检测到所述第一事件的情况下，所述隔离装置处于正常状态；所述保护电路处于高阻状态；
在检测到第一事件的情况下，将所述隔离装置从正常状态切换到异常状态以及将所述保护电路从高阻状态切换到低阻状态。
上述方案中，在所述雷击产生的能量至少大部分通过处于低阻状态的所述保护电路进行释放之后，所述方法还包括：
将所述保护电路从低阻状态切换到高阻状态、以及将所述隔离装置从异常状态切换到正常状态。
上述方案中，在雷击产生的能量至少大部分通过处于低阻状态的所述保护电路进行释放的情况下，所述方法还包括：
线路绝缘件处于正常状态；
其中，处于正常状态的线路绝缘件能够对所述输电线路进行保护。
上述方案中，在检测到第一事件之前，所述方法还包括：
对所述隔离装置、保护电路和/或所述线路绝缘件的工作参数进行调整。
上述方案中，所述对所述隔离装置、保护电路和/所述线路绝缘件的工作参数进行调整，至少包括：
所述工作参数包括雷电冲击放电电压；
调整雷击闪络限制器的雷电冲击放电电压小于线路绝缘件的雷电冲击放电电压；其中，所述雷击闪络限制器的雷电冲击放电电压为所述隔离装置和所述保护电路的雷电冲击放电电压之和。
上述方案中，所述对所述隔离装置、保护电路和/所述线路绝缘件的工作参数进行调整，至少包括：
所述工作参数包括直流耐受电压；
调整所述隔离装置的直流耐受电压大于直流输电系统的最高运行电压。
上述方案中，所述保护电路被外绝缘件包裹，所述方法还包括：
对所述外绝缘件的工作参数进行调整。
上述方案中，所述对所述外绝缘件的工作参数进行调整，包括：
调整所述外绝缘件的直流耐受电压大于直流输电系统的最高运行电压；以及调整所述外绝缘件的雷电冲击耐受电压大于处于低阻状态的保护电路两端的电压。
上述方案中，所述将所述隔离装置从异常状态切换到正常状态，包括：
在所述隔离装置处于异常状态的情况下，
检测到第二事件的情况下，将所述隔离装置从异常状态切换到正常状态，其中所述第二事件表征为所述隔离装置的直流续流被熄灭。
本申请实施例提供了一种直流输电线路雷击闪络限制方法，其中，所述方法应用于雷击闪络限制器，所述雷击闪络限制器至少包括保护电路和 隔离装置，所述包括：检测到第一事件的情况下，所述第一事件表征为输电线路遭到雷击的事件；控制所述隔离装置为异常状态，所述异常状态为所述隔离装置被所述雷击击穿的状态；在所述隔离装置处于异常状态的情况下，控制所述雷击闪络限制器的保护电路为低阻状态；所述雷击产生的能量至少大部分通过处于低阻状态的所述保护电路进行释放。
本申请实施例中，在输电线路遭到雷击的情况下，控制雷击闪络限制器的隔离装置为异常状态，控制保护电路为低阻状态，如此，雷击产生的能量(雷击信号能量如雷击电流能量)至少大部分可通过处于低阻状态的保护电路进行释放。在输电线路遭受到雷击的情况下，雷击信号能量能够及时被释放，避免输电线路全线雷电过电压，有效防止线路绝缘件发生雷击闪络现象，进而保证直流输电线路的安全运行。
附图说明
图1为本申请实施例提供的直流输电线路上雷击闪络限制器和线路绝缘件的设计示意图；
图2为本申请实施例提供的直流输电线路雷击闪络限制方法的一实现流程图；
图3为本申请实施例提供的直流输电线路雷击闪络限制方法的另一实现流程图；
图4为本申请实施例提供的雷击闪络限制前后直流输电工程典型杆塔的绕击耐雷水平的示意图；
图5为本申请实施例提供的高性能直流氧化锌电阻片非线性伏安特性曲线。
具体实施方式
为使本申请的目的、技术方案和优点更加清楚明白，下面将结合本申 请实施例中的附图，对本申请实施例中的技术方案进行清楚、完整地描述，显然，所描述的实施例仅仅是本申请一部分实施例，而不是全部的实施例。基于本申请中的实施例，本领域普通技术人员在没有做出创造性劳动前提下所获得的所有其他实施例，都属于本申请保护的范围。在不冲突的情况下，本申请中的实施例及实施例中的特征可以相互任意组合。在附图的流程图示出的步骤可以在诸如一组计算机可执行指令的计算机系统中执行。并且，虽然在流程图中示出了逻辑顺序，但是在某些情况下，可以以不同于此处的顺序执行所示出或描述的步骤。
下面结合附图与实施例对本申请的技术方案进行说明。
本申请实施例提供一种直流输电线路雷击闪络限制方法，应用于直流输电系统中，具体是应用于本申请实施例提供的雷击闪络限制器(为方便描述，后续简称为限制器)。在实际应用中，该直流输电系统的直流输电线路上限制器和线路绝缘件的设计如图1所示。针对杆塔或铁塔，将输电导线通过线路绝缘件悬挂在杆塔或铁塔上，以避免输电导线落地带来安全隐患。杆塔或铁塔上安装限制器，该限制器包括以串联方式进行连接的隔离装置和保护电路。其中，本申请实施例中的隔离装置至少具有如下两个作用：(1)在存在有雷击的情况下隔离装置优先线路绝缘件被击穿使得保护电路对雷击能量进行及时释放，从而避免线路绝缘件受到雷击影响。(2)起到了避免输电导线上的电压加载在保护电路上的目的，相当于隔离输电导线上的电压作用于保护电路。从示意图上看，图1所示的内容可以这样理解，杆塔或铁塔一端接地，另一端位于空中，线路绝缘件和限制器并联于杆塔(或铁塔)与输电导线之间。为避免雷击闪络，保护输电线路绝缘，需要对线路绝缘件进行保护，至少在存在有雷击的情况下保护其不受到雷击闪络以实现线路绝缘件正常的保护功能。本申请实施例的目的就在于如何在有雷击的情况下通过本申请实施例的限制器的作用而对线路绝缘件进 行保护。可以理解，前述的直流输电系统除了包括本申请实施例提供的限制器，还包括换流站、输电线路等。
本申请实施例提供的直流输电线路雷击闪络限制方法，应用于限制器中。如图2所示，包括：
步骤S201：检测到第一事件的情况下，所述第一事件表征为输电线路遭到雷击的事件；
S202：控制隔离装置为异常状态；
S203：在所述隔离装置处于异常状态的情况下，控制所述保护电路为低阻状态；其中，所述异常状态为所述隔离装置被所述雷击击穿的状态；
S204：所述雷击产生的能量至少大部分通过处于低阻状态的所述保护电路进行释放。
在S201～S204中，在输电线路遭到雷击的情况下，控制隔离装置为异常状态，控制保护电路为低阻状态，如此，雷击产生的能量(雷击信号能量如雷击电流能量)至少大部分可通过处于低阻状态的保护电路进行释放。雷击信号能量通过保护电路被释放，避免输电线路全线雷电过电压，有效防止直流输电线路线路绝缘件发生雷击闪络现象，进而保证直流输电线路的安全运行。
结合图1所示，在雷击信号能量通过保护电路被释放可使得线路绝缘件处于正常状态；处于正常状态的线路绝缘件对所述输电线路进行正常保护功能。应用本申请实施例的如上方案，线路绝缘件不会受到雷击信号的影响，可保证其处于正常状态，进而实现对输电导线的正常保护功能。可见，本申请实施例中，在直流输电线路遭受雷击的情况下通过控制隔离装置为异常状态以及控制保护电路为低阻状态，可使得雷击信号能量通过保护电路得以合理释放，有效限制了线路绝缘件两端的雷电过电压，避免输电线路全线雷电过电压，有效防止直流输电线路上的线路绝缘件发生雷击 闪络现象，进而保证直流输电线路的安全运行。
作为一个可选的实施例，在未检测到所述第一事件的情况下，所述隔离装置处于正常状态；所述保护电路处于高阻状态；在检测到第一事件的情况下，将所述隔离装置从正常状态切换到异常状态以及将所述保护电路从高阻状态切换到低阻状态。此处，在直流输电线路未遭受雷击的情况下，隔离装置处于正常状态，保护电路处于高阻状态(为保护电路的正常状态)。在遭受到雷击的情况下，将隔离装置从正常状态切换到异常状态，将保护电路从高阻状态切换到低阻状态。此处，基于是否检测到遭受到雷击事件的检测结果，确定保护电路和隔离装置的状态，可使得限制器在未遭受到雷击事件的情况下保持在正常工作状态，在遭受到雷击事件的情况下可起到释放雷击信号能量作用，进而限制了线路绝缘件两端在雷击情况下的雷电过电压，有效防止直流输电线路上的线路绝缘件发生雷击闪络现象，保证系统的正常运行。
作为一个可选的实施例，在所述雷击产生的能量至少大部分通过处于低阻状态的所述保护电路进行释放之后，所述方法还包括：将所述保护电路从低阻状态切换到高阻状态、以及将所述隔离装置从异常状态切换到正常状态。也即，在雷击信号能量大部分通过保护电路进行释放之后，还需要将保护电路从低阻状态切换到高阻状态、以及将隔离装置恢复正常状态。在雷击信号能量被大部分释放之后，可快速地使得限制器切换回正常工作状态，以防止下一次雷电的突然到来及确保直流输电系统安全运行。
作为一个可选的实施例，所述将所述隔离装置从异常状态切换到正常状态，包括：在所述隔离装置处于异常状态的情况下，检测到第二事件的情况下，将所述隔离装置从异常状态切换到正常状态，其中所述第二事件表征为所述隔离装置的直流续流被熄灭。可以理解，在隔离装置被雷电击穿的情况下，隔离装置的两端会出现电弧，在电弧被熄灭也即直流续流被 熄灭的情况下，可将隔离装置从异常状态切换到正常状态，以保证限制器快速切换回正常工作状态。
本领域技术人员应该而知，本申请实施例中，为实现隔离装置的率先被雷电击穿、线路绝缘件不被雷电击穿以及在隔离装置率先被雷电击穿的情况下能够对保护电路进行高阻状态到低阻状态的调整，在使用如图1所示的直流输电系统之前，还需要对隔离装置、保护电路和线路绝缘件中的至少其中之一的工作参数进行调整。
在一个优选的方案中，以对隔离装置和保护电路的工作参数进行调整为例，工作参数及其调整至少包括如下内容：所述工作参数包括雷电冲击放电电压；调整限制器的雷电冲击放电电压小于所述线路绝缘件的雷电冲击放电电压；其中，所述限制器的雷电冲击放电电压为所述隔离装置和所述保护电路的雷电冲击放电电压之和。在实际应用中，可调整限制器的雷电冲击放电电压小于线路绝缘件的雷电冲击放电电压的0.85倍。
所述工作参数还可以包括直流耐受电压；调整所述隔离装置的直流耐受电压大于直流输电系统的最高运行电压。进一步的，调整所述隔离装置的直流耐受电压与直流输电系统的最高运行电压的比值至少大于1。其中，直流输电系统的最高运行电压可认为是能够保证直流输电系统正常运行的电压的最大值。
在实际应用中，所述限制器还包括用于包裹所述保护电路的外绝缘件；调整工作参数还包括调整所述外绝缘件的工作参数。进一步的，调整所述外绝缘件的直流耐受电压大于直流输电系统的最高运行电压；以及调整所述外绝缘件的雷电冲击耐受电压大于处于低阻状态的保护电路两端的电压。在一个可行的实施例中，调整所述外绝缘件的直流耐受电压与直流输电系统的最高运行电压的比值至少大于1.2。调整外绝缘件的雷电冲击耐受电压与处于低阻状态的保护电路两端的电压的比值至少大于1.4。
可以理解，如上所述的对多个工作参数的调整均是为了直流输电系统能够正常投入使用，保证系统的正常运行。需要说明的是，前述内容是对隔离装置和保护电路的工作参数进行的调整，对于线路绝缘件是否可进行工作参数的调整视实际使用情况而定。
在实际应用中，本申请实施例中的限制器可以具体为避雷器。线路绝缘件可以为绝缘子串，还可以为塔头空气间隙。下面以保护电路为非线性电阻元件、隔离装置为避雷器的外串联间隙、线路绝缘件为绝缘子串为例，对本申请实施例的方案做进一步说明。
需要说明的是，以下内容是以避雷器作为本申请实施例的限制器的一种优选方式，绝缘子串为线路绝缘件的一种优选方式，非线性电阻元件为保护电路的一种优选方式，外串联间隙为隔离装置的一种优选方式，进行的说明。本领域技术人员应该而知，在实际应用中任何合理的元器件、组件、装置和/或设备均可作为本申请实施例中的限制器和线路绝缘件，此处不一一赘述。
下面来看本申请实施例的工作原理：
在未遭受到雷击的情况下，外串联间隙为正常状态(绝缘状态，相当于开路状态)，非线性电阻元件为高阻状态(非线性电阻元件的正常状态)，相当于避雷器为未被使用状态。绝缘子串将输电导线悬挂在杆塔或铁塔上。
在遭受到雷击的情况下，避雷器从未被使用状态切换到被使用状态。进一步的，由于预先调整的避雷器的雷电冲击放电电压低于绝缘子串的雷电冲击放电电压，与绝缘子串相比，所以避雷器的外串联间隙率先被雷电击穿，相当于切换外串联间隙从开路状态到短路状态(从绝缘状态切换到导通状态)，串联非线性电阻元件立即被启动，控制非线性电阻元件从高阻状态切换到低阻状态，也即控制非线性电阻元件从正常状态切换到异常状态。可以理解，外串联间隙切换到短路状态相当于非线性电阻元件直接与 输电导线连接，输电导线上的雷电流能量传输至低阻状态的非线性电阻元件，该非线性电阻元件将输电导线上的雷电流能量经由杆塔或铁塔传输入地，以实现对输电导线上的雷电流能量的及时、合理释放。其中，由非线性电阻元件经由杆塔或铁塔传输入地雷电流能量为雷电流的大部分能量，如70％-80％雷电流能量。同时非线性电阻元件也吸收雷电流能量。外串联间隙被雷电击穿，使得外串联间隙的两端出现电弧，非线性电阻元件进行熄灭，当非线性电阻元件熄灭外串联间隙的直流续流后，非线性电阻元件从低阻状态切换回高阻状态，外串联间隙恢复绝缘状态。
上述方案中，在直流输电线路遭受雷击的情况下，控制外串联间隙为短路状态以及非线性电阻元件为低阻状态，如此，雷击信号能量便可通过非线性电阻元件传输入地、得以合理释放。避雷器的如上使用过程，可有效限制绝缘子串两端的雷电过电压，防止直流输电线路绝缘子串发生雷击闪络现象，进而保证直流输电线路的安全运行。
此外，非线性电阻元件熄灭外串联间隙的直流续流后，外串联间隙恢复绝缘状态(外串联间隙的正常状态)，非线性电阻元件从低阻状态切换回高阻状态(非线性电阻元件的正常状态)，也即避雷器恢复到正常状态，以防止下一次雷击的突然到来及确保直流输电系统安全运行。
需要说明的是，本申请实施例中，非线性电阻元件可在10ms以内能够可靠熄灭外串联间隙的直流续流，也即在短时间内即可达到熄灭外串联间隙的直流续流的效果，该熄灭外串联间隙的直流续流的时间较短，可使得避雷器能够快速地恢复到正常状态，以防止下一次雷击的到来及确保直流输电系统安全运行。此外，该熄灭外串联间隙的直流续流的时间远小于直流输电系统故障重启的去游离时间150～500ms。如此，便可无需直流输电系统进行重启就可解决雷击对直流输电系统造成的影响，实现了避雷器的应用保护与直流输电工程安全运行的可靠配合。
本领域技术人员应该而知，以上方案为直流输电系统采用了本申请实施例中的避雷器的情况下，如何进行雷电能量合理释放，进而保证系统的正常运行的方案。可以理解，在直流输电系统未采用本申请实施例中的避雷器的情况下，仅采用传统方案(优化架空地线的方式)的情况下，输电线路会产生重启，甚至会导致闭锁。重启并闭锁的事例可通过如下表1所示的数据来体现。
我国某±800kV特高压直流输电线路在2016年8月2日20:29:31时刻前后1.5s内，有5次雷电地闪数据，见表1所示的五行数据。其中，每一行数据代表一次回击。后4次雷电地闪(第2-5行数据)属于同一次雷电活动的回击，也即属于同一雷电通道内前后产生多次短时间间隔的雷击放电。除了第1次回击，第2～4次回击雷电流幅值均在30～60kA，参与这些数据探测的雷电探测站数在18站及以上。回击雷电流的幅值满足直流输电线路故障区段绕击发生条件(危险雷电流区为30～60kA)，相关技术中，在产生如上的雷击情况下，直流输电系统历经2次重启后发生闭锁。
表1
Figure PCTCN2019122219-appb-000001
下面结合表2对相关技术中采用传统方案在重启时间上以及去游离时 间上存在的问题进行说明。也即结合表2所示的故障录波信息对相关技术中存在的问题进行说明。
结合记录的故障录波信息，对故障原因分析进行如下分析：
表2
Figure PCTCN2019122219-appb-000002
(1)20:29:30.993时刻表1中的序号3对应的雷电击中极I(正极)导线，造成极I导线由整流转逆变运行，故障录波起始时刻为20:29:30.998，传统方案中经37ms后(20:29:31.35)直流电流降到零。再经126ms的弧道去游离时间后(20:29:31.161)，极I开始第一次全压再启动，结束时刻为20:29:31.271。在前述的去游离过程中，20:29:31.77序号4(距离序号3雷电84ms)雷电击中极I导线，引发弧道去游离不充分，同时在前述的再启动过程中，20:29:31.180序号5(距离序号4雷电103ms)雷电沿着同一雷电通道再次击中极I导线，造成极I第一次全压再启动失败也即第一次再启动失败。
(2)经过198ms的弧道去游离时间后(20:29:31.469)，极I开始第二次全压再启动。由于20:29:31.180序号5(距离第二次去游离时间为289ms)雷电击中极I导线，再次引发弧道去游离不充分，造成极I第二次全压再启动失败，按照制定的保护策略，需要对极I进行闭锁。
可见，前述方案中各次去游离的持续时间(第一次去游离的持续时间和第二次去游离的持续时间)一定的情况下，采用传统的优化架空地线的方式并不能短时间内的将雷击电流释放掉，进而不得不采用如上的闭锁方案。而采用了本申请实施例中的避雷器之后，在同一雷电通道内前后产生 多次短时间间隔的雷击放电的情况下，对于每次的雷击放电，避雷器均可将其及时释放以使得保护电路和隔离装置能够从释放雷击电流的状态很快地切换回正常状态以准备对下一次的雷击产生的能量并进行及时释放。本申请实施例中的保护电路、具体是非线性电阻元件可在10ms内熄灭电弧的外串联间隙直流续流，也即在短时间内即可达到熄灭外串联间隙的直流续流的效果，从而使得避雷器能够在释放大部分雷击电流的情况下快速地切换回到正常状态以实现对下一次雷击产生的电流的及时释放。本申请实施例中，非线性电阻元件熄灭外串联间隙的直流续流的时间远小于直流输电系统故障重启的去游离时间150～500ms。如此，便可无需直流输电系统进行重启、也无需极I进行闭锁，进而避免由于重启与闭锁而导致的系统无法正常使用的问题，实现了避雷器的应用保护与直流输电工程安全运行的可靠配合。
图4是采用本申请实施例进行雷击闪络限制前后的直流输电线路的绕击耐雷水平的示意图。其中，在雷电流幅值为0～150kA的范围内，针对500kV的典型杆塔，其大约在22～37kA的范围内存在危险的雷电流区，也即在雷电流为22～37kA的范围内，该杆塔的耐雷能力较差。针对800kV的典型杆塔，其大约在30～60kA的范围内存在危险的雷电流区，也即在雷电流为30～60kA的范围内，该杆塔的耐雷能力较差。而针对这两种杆塔，在各自增加有本申请实施例的如上避雷器之后，不存在有耐雷水平差的区域。在雷电流幅值为0～150kA的范围内，均具有较好的耐雷水平。同时基于我国的雷电监测数据，可给出雷电流幅值累积概率分布，分布函数见公式(1)：
Figure PCTCN2019122219-appb-000003
式中：
P——幅值大于I的雷电流概率，％；
I——雷电流幅值，kA；
a——中值电流(超过该幅值的雷电流出现概率为50％)，根据我国近10年来的雷电监测数据，取值为29.97kA；
b——雷电流幅值分布的集中程度参数，根据我国近10年来的雷电监测数据，取值为2.82。
可知，雷电流幅值超过150kA的概率为1.05％。
本领域技术人员应该而知，图4仅以雷电流幅值为0～150kA为例进行的说明，对于雷电流幅值超过150kA的情况，根据如上公式(1)的计算可知雷电流幅值超过150kA的概率为1.05％。在自然界中，相对于雷电流幅值为0～150kA的雷击现象的出现，雷电流幅值超过150kA的雷击现象出现的概率较小如为0.0105。本申请实施例中提供的方案主要考虑到自然界中的实际发生情况，但不意味着本申请实施例提供的方案无法适用出现有雷电流幅值超过150kA的雷击现象的情况。可见，本申请实施例提供的方案实用性较强，可行性高，在工程上易于实现。
通过本申请实施例的技术方案，可提高不同类型的杆塔或铁塔的耐雷水平，从而能够更好的抵抗雷击，进而保证直流输电系统的正常运行。
可以理解，在实际应用中，绝缘子串还可以通过塔头空气间隙来实现；非线性组件可以由任何能够实现高阻抗和低阻抗自由转换的器件来实现；所述隔离装置可以是任何能够实现隔离作用的器件如避雷器的外串联间隙为纯空气串联间隙，以上内容均为一种优先方案，不局限于以上所述。
需要说明的是，非线性电阻元件由具有优异非线性伏安特性的高性能器件。在实际应用中，该非线性电阻元件可以为氧化锌电阻片。选取氧化锌电阻片主要考虑到其具有优异的非线性伏安特性。其中，优异非线性伏安特性可以参见如图5所示。从横坐标(单位是安培A/平方毫米mm 2)从0.00001到10000的过程中，纵坐标(伏V/毫米mm)从150变化至400。在横坐标处于中间位置如0.01～5坐标，纵坐标的取值的变化较为缓慢。具 有这样伏安特性的器件，纵坐标的变化远小于横坐标的变化。如横坐标变化100倍，纵坐标才变化2倍。具有这样伏安特性的器件均可作为本申请实施例的非线性电阻元件。在一个可选的方案中，非线性电阻元件可由具有如上非线性伏安特性的直流氧化锌电阻片构成，该直流氧化锌电阻片可避免反向肖特基势垒侧的填隙锌离子在直流电压作用下向晶界层迁移，导致肖特基势垒高度降低，使得氧化锌电阻片具有较高的老化性能，从而使得避雷器更不易老化，避雷器的抗老化性能明显被提升，使得避雷器的使用更为长久。其中，直流氧化锌电阻片在正常运行时，泄漏电流为微安级别，处于高阻状态。外串联间隙被击穿的情况下，非线性电阻元件启动，其两端电压仅有微小增加(2倍左右)，而电流有5～6个数量级的增加，处于低阻状态。可以理解，以上为氧化锌电阻片作为非线性电阻元件时对其具有的优异非线性伏安特性进行的说明。在实际应用中，任何具有与图5相同或相似非线性伏安特性的元器件、组件等均可作为本申请实施例的非线性电阻元件，而不仅限于氧化锌电阻片。
本领域技术人员应该理解，在本申请实施例的避雷器进行投入使用之前，还需要对避雷器中的外串联间隙和非线性电阻元件的工作参数进行调整，直至调整至预期的水平。利用工作参数调整好的避雷器，在存在有雷击的情况下能够起到更好的防雷作用，有效限制绝缘子串两端的雷电过电压，防止直流输电线路绝缘子串发生雷击闪络现象，进而保证直流输电线路的安全运行。
在具体实现上，参见图3所示，所述工作参数的调整过程为：
第一步，调整避雷器的外串联间隙，计算避雷器的外串联间隙直流耐受电压与系统最高运行电压的比值。
本步骤中，可认为对避雷器的外串联间隙的直流耐受电压进行调整，该调整可以是从外串联间隙的直流耐受电压从初始设置值按照一定的步进 进行增加。如外串联间隙距离初始设置值为1000mm，以50mm为一个步进，进行外串联间隙距离的增加，进而实现外串联间隙的直流耐受电压的增加。本领域技术人员应该理解，读取直流输电系统的最高运行电压。每次调整均对调整的外串联间隙的直流耐受电压与系统最高运行电压进行比值的计算。
若调整为避雷器的外串联间隙直流耐受电压与系统最高运行电压的比值大于1，则可转入第三步；否则，需要继续优化调整避雷器的外串联间隙。其中，调整外串联间隙直流耐受电压与系统最高运行电压的比值大于1，可认为在非线性电阻元件出现短路故障时，外串联间隙仍能够耐受系统的最高运行电压，不致影响直流输电系统的正常运行。
第三步，根据线路绝缘件的绝缘配置，调整避雷器的外串联间隙和非线性电阻元件之间的配合关系，计算避雷器的雷电冲击放电电压与线路绝缘件的雷电冲击放电电压的比值。
本步骤中，可以认为为保证在遭受到雷击的情况下，避雷器的外串联间隙被率先击穿，不会由于外串联间隙未被击穿而导致的避雷器无法起到泄放能量的作用而造成的线路绝缘件损坏、进而影响直流输电系统正常运行的问题。需要线路绝缘件的耐雷水平如雷电冲击放电电压，增加或减小外串联间隙和非线性电阻元件之间的配合关系，保证遭受到雷击的情况下外串联间隙被率先击穿，也即使得在遭受到雷击的情况下避雷器能够起到泄放能量作用。
经过发明人的多次试验发现，若调整避雷器的雷电冲击放电电压与线路绝缘件的雷电冲击放电电压的比值小于0.85，则认为调整到理想水平，具有较大的保护裕度，转入第五步；否则，需要继续调整避雷器的外串联间隙和非线性电阻元件之间的配合关系。
第五步，根据非线性电阻元件启动时两端的电压，调整避雷器的外绝 缘配置，计算外绝缘的雷电冲击耐受电压与串联非线性电阻元件启动时两端电压的比值。
可以理解，为起到对非线性电阻元件的保护作用，非线性电阻元件的外部需要包括有绝缘物(称之为避雷器的外绝缘)。本步骤中，外绝缘作为避雷器的一部分，也需要其起到能够承受住雷击作用。根据非线性电阻元件启动时两端的电压大小，根据外绝缘物质的材质、型号等因素，调整(增大或减小)避雷器的外绝缘的雷电冲击耐受电压的大小。
若调整外绝缘的雷电冲击耐受电压与非线性电阻元件启动时两端电压的比值大于1.4，则认为调整到理想水平，转入第七步；否则，需要继续优化调整避雷器的外绝缘配置。
第七步，调整避雷器的外绝缘配置，计算外绝缘的直流耐受电压与系统最高运行电压的比值。
本步骤中，根据外绝缘物质的材质、型号等因素，增加或减小外绝缘的直流耐受电压，使得外绝缘件具有一定的耐受水平，且将外绝缘的直流耐受电压调整到与系统最高运行电压的比值大于1.2，具有较大保护裕度，则完成了直流输电线路的雷击闪络的限制。限制前后±500kV、±800kV直流输电工程典型杆塔的绕击耐雷水平见图4。
需要说明的是，避雷器的外绝缘可以采用硅橡胶复合外套材质。这种材质的外绝缘一方面比较轻便，另一方面即使避雷器出现故障，也不会给周围设备及人身安全带来威胁。
还可以是其它任何合理材质的外套。
需要说明的是，非线性电阻元件在10ms以内能够可靠熄灭避雷器的外串联间隙直流续流，也即在短时间内即可达到熄灭外串联间隙的直流续流的效果。该熄灭外串联间隙的直流续流的时间远小于直流输电系统故障重启的去游离时间150～500ms。如此，便可无需直流输电系统进行重启就可 解决雷击对直流输电系统造成的影响，实现了避雷器的应用保护与直流输电工程安全运行的可靠配合。
本申请实施例提供的直流输电线路雷击闪络限制方法，至少具有如下有益效果：
1)通过对隔离装置的雷电冲击放电电压的调整保证在遭受到雷击的情况下隔离装置率先被雷击穿，如此便可保证线路绝缘件不被击穿。且通过保护电路从高阻到低阻状态的切换，使得大部分的雷电流能量经由保护电路被传输入地也即被合理释放。有效限制了线路绝缘件两端的雷电过电压，避免输电线路全线雷电过电压，有效防止直流输电线路上线路绝缘件发生雷击闪络现象，进而保证直流输电线路的安全运行。
2)防护有效性更高。较传统优化架空地线模式的方案相比，适用于途径各种地形地貌、地质条件的直流输电线路，使输电线路杆塔耐雷水平大幅提升，能够躲过危险雷电流区域。
3)性能可靠性更高。采用保护电路和隔离装置配合方式，实现直流续流的切断，由于隔离装置的隔离，限制器正常运行时保护电路不带电，可避免保护电路的老化。
4)熄弧时间短。保护电路可在10ms以内能够可靠熄灭隔离装置的直流续流，雷击闪络熄弧时间远小于直流输电系统的保护装置执行重启的动作时间，适用于直流输电线路的雷电防护，可有效保障直流输电线路运行的安全稳定性。
以上对本申请实施例中的技术方案进行了描述，但本申请并不局限于上述的具体实施方式，上述的具体实施方式仅仅是示意性的，而不是限制性的，本领域的普通技术人员在本申请的启示下，在不脱离本申请宗旨和权利要求所保护的范围情况下，还可做出很多形式，这些均属于本申请的保护范围之内。
本领域内的技术人员应明白，本申请的实施例可提供为方法、系统、或计算机程序产品。因此，本申请可采用硬件实施例、软件实施例、或结合软件和硬件方面的实施例的形式。而且，本申请可采用在一个或多个其中包含有计算机可用程序代码的计算机可用存储介质(包括但不限于磁盘存储器和光学存储器等)上实施的计算机程序产品的形式。
本申请是参照根据本申请实施例的方法、设备(系统)、和计算机程序产品的流程图和/或方框图来描述的。应理解可由计算机程序指令实现流程图和/或方框图中的每一流程和/或方框、以及流程图和/或方框图中的流程和/或方框的结合。可提供这些计算机程序指令到通用计算机、专用计算机、嵌入式处理机或其他可编程数据处理设备的处理器以产生一个机器，使得通过计算机或其他可编程数据处理设备的处理器执行的指令产生用于实现在流程图一个流程或多个流程和/或方框图一个方框或多个方框中指定的功能的装置。
这些计算机程序指令也可存储在能引导计算机或其他可编程数据处理设备以特定方式工作的计算机可读存储器中，使得存储在该计算机可读存储器中的指令产生包括指令装置的制造品，该指令装置实现在流程图一个流程或多个流程和/或方框图一个方框或多个方框中指定的功能。
这些计算机程序指令也可装载到计算机或其他可编程数据处理设备上，使得在计算机或其他可编程设备上执行一系列操作步骤以产生计算机实现的处理，从而在计算机或其他可编程设备上执行的指令提供用于实现在流程图一个流程或多个流程和/或方框图一个方框或多个方框中指定的功能的步骤。
以上所述，仅为本申请的较佳实施例而已，并非用于限定本申请的保护范围。
工业实用性
本申请实施例中，在输电线路遭到雷击的情况下，控制雷击闪络限制器的隔离装置为异常状态，控制保护电路为低阻状态，如此，雷击产生的能量(雷击信号能量如雷击电流能量)至少大部分可通过处于低阻状态的保护电路进行释放。在输电线路遭受到雷击的情况下，雷击信号能量能够及时被释放，避免输电线路全线雷电过电压，有效防止线路绝缘件发生雷击闪络现象，进而保证直流输电线路的安全运行。
也即，通过对隔离装置的雷电冲击放电电压的调整保证在遭受到雷击的情况下隔离装置先被雷击穿，如此便可保证线路绝缘件不被击穿。且通过保护电路从高阻到低阻状态的切换，使得大部分的雷电流能量经由保护电路被传输入地也即被合理释放。避免输电线路全线雷电过电压，有效限制了线路绝缘件两端的雷电过电压，有效防止直流输电线路上线路绝缘件发生雷击闪络现象，进而保证直流输电线路的安全运行。

Claims (10)

  1. 一种直流输电线路雷击闪络限制方法，其特征在于，所述方法包括：
    检测到第一事件的情况下，所述第一事件表征为输电线路遭到雷击的事件；
    控制雷击闪络限制器的隔离装置为异常状态，所述异常状态为所述隔离装置被所述雷击击穿的状态；
    在所述隔离装置处于异常状态的情况下，控制雷击闪络限制器的保护电路为低阻状态；
    所述雷击产生的能量至少大部分通过处于低阻状态的所述保护电路进行释放。
  2. 根据权利要求1所述的方法，其特征在于，在未检测到所述第一事件的情况下，所述隔离装置处于正常状态；所述保护电路处于高阻状态；
    在检测到第一事件的情况下，将所述隔离装置从正常状态切换到异常状态以及将所述保护电路从高阻状态切换到低阻状态。
  3. 根据权利要求2所述的方法，其特征在于，在所述雷击产生的能量至少大部分通过处于低阻状态的所述保护电路进行释放之后，所述方法还包括：
    将所述保护电路从低阻状态切换到高阻状态、以及将所述隔离装置从异常状态切换到正常状态。
  4. 根据权利要求1至3任一项所述的方法，其特征在于，在雷击产生的能量至少大部分通过处于低阻状态的所述保护电路进行释放的情况下，所述方法还包括：
    线路绝缘件处于正常状态；
    其中，处于正常状态的线路绝缘件能够对所述输电线路进行保护。
  5. 根据权利要求4所述的方法，其特征在于，在检测到第一事件 之前，所述方法还包括：
    对所述隔离装置、保护电路和/或所述线路绝缘件的工作参数进行调整。
  6. 根据权利要求5所述的方法，其特征在于，所述对所述隔离装置、保护电路和/所述线路绝缘件的工作参数进行调整，包括：
    所述工作参数包括雷电冲击放电电压；
    调整雷击闪络限制器的雷电冲击放电电压小于线路绝缘件的雷电冲击放电电压；其中，所述雷击闪络限制器的雷电冲击放电电压为所述隔离装置和所述保护电路的雷电冲击放电电压之和。
  7. 根据权利要求5所述的方法，其特征在于，所述对所述隔离装置、保护电路和/所述线路绝缘件的工作参数进行调整，至少包括：
    所述工作参数包括直流耐受电压；
    调整所述隔离装置的直流耐受电压大于直流输电系统的最高运行电压。
  8. 根据权利要求4所述的方法，其特征在于，所述保护电路被外绝缘件包裹，所述方法还包括：
    对所述外绝缘件的工作参数进行调整。
  9. 根据权利要求8所述的方法，其特征在于，所述对所述外绝缘件的工作参数进行调整，包括：
    调整所述外绝缘件的直流耐受电压大于直流输电系统的最高运行电压；以及调整所述外绝缘件的雷电冲击耐受电压大于处于低阻状态的保护电路两端的电压。
  10. 根据权利要求2所述的方法，其特征在于，所述将所述隔离装置从异常状态切换到正常状态，包括：
    在所述隔离装置处于异常状态的情况下，
    检测到第二事件的情况下，将所述隔离装置从异常状态切换到正常状 态，其中所述第二事件表征为所述隔离装置的直流续流被熄灭。
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