Ultra-high voltage direct current insulation ground wire ice melting line and ice melting method

Abstract

The invention relates to an extra-high voltage direct current insulation ground wire ice melting line and an ice melting method, and relates to the technical field of extra-high voltage direct current power transmission, the extra-high voltage direct current insulation ground wire ice melting line comprises a tower, a ground wire, a ground wire insulator and an ice melting device; a tower is connected with a ground wire through a ground wire insulator, one end of the ground wire is short-circuited and grounded, the other end of the ground wire is connected with an ice melting device, an electrostatic induction voltage suppression device is arranged between the ice melting device and the ground wire and comprises an electrostatic induction voltage absorption circuit and a protection circuit which are connected in parallel, and the electrostatic induction voltage absorption circuit is used for stabilizing voltage. And the protection circuit is used for discharging partial overvoltage, preventing the overvoltage from locking or damaging the ice melting device, and controlling the rectification converter within a safe operation voltage range.

Description

Technical Field

[0001] The present disclosure relates to the technical field of ultra-high voltage direct current power transmission, and in particular to an ultra-high voltage direct current insulated ground wire de-icing line and de-icing method. Background Art

[0002] Since the ground wire of the UHV DC transmission line is generally located above the transmission line, the transmission span is large and no current is passed through it. Compared with the transmission line conductor, the ground wire is more prone to ice disasters in winter, which can easily cause power outages such as line breakage and tower damage, posing a great threat to the safety of UHV transmission lines connecting large energy bases. In terms of ice melting, the ground wire is different from the conductor, which can be directly applied with DC current to melt the ice. Since the ground wire is directly connected to the tower, DC current cannot be directly applied to melt the ice.

[0003] In order to facilitate the de-icing of the ground wire, in the prior art, the ground wire is generally insulated, the end of the ground wire is short-circuited and then connected in series to a DC de-icing circuit, and the de-icing device provides a DC current to heat and de-icer. However, when the ground wire is de-iced, if the UHV transmission line is not stopped, there will be a very high electrostatic induced voltage on the UHV transmission line that is not stopped. The excessively high electrostatic induced voltage will exceed the safe voltage range of the de-icing device, causing the de-icing device to lock or be damaged, which will reduce the safety of de-icing and cause huge economic losses. Summary of the invention

[0004] In order to solve the above technical problems, the present invention provides a UHV DC insulated ground wire ice-melting line and an ice-melting method, which are used to suppress the electrostatic induction voltage of the ground wire within a certain safety range when the ground wire is ice-melted, thereby ensuring the safe and stable operation of the ice-melting device.

[0005] In a first aspect, the present disclosure provides an ultra-high voltage direct current insulated ground wire ice melting line, comprising: a first side pole tower, a second side pole tower, a first ground wire, a second ground wire, a ground wire insulator, and an ice melting device;

[0006] The first ground wire is connected to the first side pole tower through the ground wire insulator, and the second ground wire is connected to the second side pole tower through the ground wire insulator; the first ends of the first ground wire and the second ground wire are connected to the ice melting device, and the second ends of the first ground wire and the second ground wire are short-circuited and grounded;

[0007] The ice melting device includes an electrostatic induction voltage suppression device, and the electrostatic induction voltage suppression device includes an isolating switch; the electrostatic induction voltage suppression device includes an electrostatic induction voltage absorption circuit and a protection circuit, the protection circuit is connected in parallel with the electrostatic induction voltage absorption circuit, the electrostatic induction voltage absorption circuit includes a first resistor and a first capacitor connected in parallel, and the protection circuit includes a nonlinear resistor.

[0008] Optionally, a resistance range of the first resistor is greater than or equal to 7KΩ and less than or equal to 20KΩ.

[0009] Optionally, the nonlinear resistor comprises a zinc oxide resistor.

[0010] Optionally, the protection circuit includes a parallel gap, and the nonlinear resistor is connected in parallel with the parallel gap.

[0011] Optionally, the ice melting device further comprises: a rectifier converter, a positive terminal switch, and a negative terminal switch;

[0012] The input end of the rectifier-converter is connected to an AC power supply, the positive output end of the rectifier-converter is connected to a positive terminal switch, the positive terminal switch is coupled to a positive outlet cable, and the positive outlet cable is coupled to a first ground wire; the negative output end of the rectifier-converter is connected to a negative terminal switch, the negative terminal switch is coupled to a negative outlet cable, and the negative outlet cable is coupled to a second ground wire;

[0013] The electrostatic induction voltage suppression device is respectively connected between the positive terminal switch and the positive outlet cable, and between the negative terminal switch and the negative outlet cable, and the other end of the electrostatic induction voltage suppression device is grounded.

[0014] Optionally, a DC reactor is connected in series between the positive output end of the rectifier-converter and the positive terminal switch, and a DC reactor is connected in series between the negative output end of the rectifier-converter and the negative terminal switch.

[0015] Optionally, the capacitance range of the first capacitor is greater than or equal to 20 μF.

[0016] Optionally, the ground wire insulator is any one of a composite insulator, a glass insulator and a ceramic insulator; and the discharge gaps connected in parallel at both ends of the insulator are used for lightning protection.

[0017] In a second aspect, based on the same inventive concept, the present disclosure provides a method for melting ice of an ultra-high voltage direct current insulated ground wire, which is applied to the ultra-high voltage direct current insulated ground wire melting ice line as described in the first aspect, comprising:

[0018] Connect the AC power supply to the input terminal of the rectifier converter;

[0019] Close the positive terminal switch to connect the positive output terminal of the rectifier converter and the first ground wire, and close the negative terminal switch to connect the negative output terminal of the rectifier converter and the second ground wire;

[0020] The rectifier inverter is operated to detect whether the electrostatic induction voltage meets the safety voltage range of the ice-melting device. If so, the rectifier inverter is made to output an ice-melting DC voltage.

[0021] Compared with the prior art, the technical solution provided by the embodiments of the present disclosure has the following advantages: by adding an electrostatic induction voltage suppression device to the ice-melting device of the ultra-high voltage DC insulated ground wire, the electrostatic induction voltage absorption circuit in the electrostatic induction voltage suppression device plays a voltage stabilizing role, absorbs peak overvoltage, and ensures the safe and stable operation of the rectifier inverter; the protection circuit in the electrostatic induction voltage suppression device is used to discharge part of the overvoltage when lightning strikes or other situations cause overvoltage, suppress the electrostatic induction voltage within a certain safety range, reduce the locking or damage of the ice-melting device, and ensure the safe and stable operation of the ice-melting device. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present disclosure and, together with the description, serve to explain the principles of the present disclosure.

[0023] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0024] Figure 1 The figure shows a schematic diagram of an ultra-high voltage direct current insulated ground wire ice melting circuit provided by an embodiment of the present disclosure;

[0025] Figure 2 Shown is a connection diagram of an electrostatic induction voltage suppression device provided by an embodiment of the present disclosure;

[0026] Figure 3 Shown is a connection schematic diagram of another electrostatic induction voltage suppression device provided by an embodiment of the present disclosure;

[0027] Figure 4 The figures show the electrostatic induction voltage simulation experiment results of an embodiment of the present disclosure with and without an electrostatic induction voltage suppression device. DETAILED DESCRIPTION

[0028] In order to more clearly understand the above-mentioned objectives, features and advantages of the present disclosure, the scheme of the present disclosure will be further described below. It should be noted that the embodiments of the present disclosure and the features in the embodiments can be combined with each other without conflict.

[0029] In the following description, many specific details are set forth to facilitate a full understanding of the present disclosure, but the present disclosure may also be implemented in other ways different from those described herein; it is obvious that the embodiments in the specification are only part of the embodiments of the present disclosure, rather than all of the embodiments.

[0030] Figure 1 The figure shows a schematic diagram of an ultra-high voltage direct current insulated ground wire ice melting circuit provided by an embodiment of the present disclosure. Figure 2 FIG. 1 is a connection diagram of an electrostatic induction voltage suppression device provided by an embodiment of the present disclosure. Figure 3 FIG. 1 is a schematic diagram showing another electrostatic induction voltage suppression device provided by an embodiment of the present disclosure; please refer to FIG. Figures 1 to 3 The present disclosure provides a UHV DC insulated ground wire de-icing line 100, comprising: a first side tower 10, a second side tower 20, a first ground wire 11, a second ground wire 21, a ground wire insulator 00 and an de-icing device 30;

[0031] The first ground wire 11 is connected to the first side pole tower 10 through the ground wire insulator 00, and the second ground wire 21 is connected to the second side pole tower 20 through the ground wire insulator 00; the first ends of the first ground wire 11 and the second ground wire 21 are connected to the ice melting device 30 through the outdoor knife switch, and the second ends of the first ground wire 11 and the second ground wire 21 are short-circuited and grounded;

[0032] The ice melting device 30 includes an electrostatic induction voltage suppression device 31, which includes an isolating switch 32; the electrostatic induction voltage suppression device 31 includes an electrostatic induction voltage absorption circuit 311 and a protection circuit 312, the protection circuit 312 is connected in parallel with the electrostatic induction voltage absorption circuit 311, the electrostatic induction voltage absorption circuit 311 includes a first resistor R1 and a first capacitor C1 connected in parallel, and the protection circuit 312 includes a nonlinear resistor BL.

[0033] Specifically, the first side pole tower 10 and the second side pole tower 20 are arranged opposite to each other, the first side pole tower 10 includes at least two pole towers, each pole tower is coupled to the first ground wire 11, and a ground wire insulator 00 is included between each pole tower and the first ground wire 11, the second side pole tower 20 includes at least two pole towers, each pole tower is coupled to the second ground wire 21, and a ground wire insulator 00 is included between each pole tower and the second ground wire 21, and the ground wire insulator 00 is used to keep the ground wire insulated from the surrounding environment to ensure the safe and stable operation of the power system.

[0034] It should be noted that the pole tower also includes a conductor (not shown in the figure), which is used to transmit electrical energy.

[0035] One end of the first ground wire 11 is connected to the ice melting device 30 , and the other end of the first ground wire 11 is grounded; one end of the second ground wire 21 is connected to the ice melting device 30 , and the other end of the second ground wire 21 is short-circuited with the other end of the first ground wire 11 and grounded. Optionally, a first outdoor knife switch 12 is further included between the first ground wire 11 and the ice-melting device 30, and a second outdoor knife switch 22 is further included between the second ground wire 21 and the ice-melting device 30; when the first ground wire 11 and the second ground wire 21 do not need to be de-iced, the first outdoor knife switch 12 is grounded, and the second outdoor knife switch 22 is grounded, and the ground wires are used to protect the conductors on the pole tower from lightning strikes; when the first ground wire 11 and the second ground wire 21 need to be de-iced, the first outdoor knife switch 12 is closed to connect the first ground wire 11 to the ice-melting device 30, the second outdoor knife switch 22 is closed to connect the second ground wire 21 to the ice-melting device 30, and the ice-melting device 30 outputs an ice-melting current. Since the ground wire has a certain resistance, the current will generate heat when it passes through, and the thermal effect of the current is used to melt the ice layer on the ground wire, thereby achieving the purpose of de-icing.

[0036] The ice-melting device 30 includes an electrostatic induction voltage suppression device 31, and the electrostatic induction voltage suppression device 31 includes an isolating switch 32; when it is not necessary to melt the ice on the ground wire, the isolating switch 32 is disconnected and the first outdoor knife switch 12 is grounded; when it is necessary to melt the ice on the ground wire, the isolating switch 32 is closed, and the electrostatic induction voltage suppression device 31 is connected to the ground wire in parallel to suppress the high-amplitude electrostatic induction voltage generated by a fault during the melting of the ground wire, thereby ensuring the safe and stable operation of the ice-melting device 30.

[0037] The electrostatic induction voltage suppression device 31 includes an electrostatic induction voltage absorption circuit 311 and a protection circuit 312. The protection circuit 312 is connected in parallel with the electrostatic induction voltage absorption circuit 311. The electrostatic induction voltage absorption circuit 311 includes a first resistor R1 and a first capacitor C1 connected in parallel. The first capacitor C1 includes a self-contained resistor, which refers to the equivalent series resistance of the first capacitor C1, which is the sum of all resistances inside the first capacitor C1, including the resistance of the electrode, the resistance of the lead wire, and the resistance between the medium and the plate of the first capacitor C1. The first resistor R1 and the first capacitor C1 are used to stabilize the voltage during the ground line ice melting process, absorb the overvoltage in the peak state, and thus protect the rectifier converter 34.

[0038] The electrostatic induction voltage suppression device 31 also includes a protection circuit 312, which includes a nonlinear resistor BL. The nonlinear resistor BL is used to conduct when an overvoltage occurs due to lightning strike or other reasons, discharge part of the overvoltage, and suppress the electrostatic induction voltage within a certain safety range, thereby ensuring the safe and stable operation of the ice melting device.

[0039] In this way, an electrostatic induction voltage suppression device 31 is arranged between the rectifier inverter 34 and the ground wire. The electrostatic induction voltage suppression device 31 includes an electrostatic induction voltage absorption circuit 311 and a protection circuit 312 connected in parallel. The electrostatic induction voltage absorption circuit 311 is used to stabilize the voltage of the ice melting device to ensure the safe and stable operation of the ice melting device 30.

[0040] Please continue to refer to Figures 1 to 3 The resistance range of the first resistor R1 is greater than or equal to 7KΩ and less than or equal to 20KΩ.

[0041] Specifically, the electrostatic induction voltage suppression device 31 includes an electrostatic induction voltage absorption circuit 311 and a protection circuit 312 connected in parallel. The electrostatic induction voltage absorption circuit 311 includes a first resistor R1 and a first capacitor C1 connected in parallel. The first resistor R1 is used for voltage stabilization. By connecting the first resistor R1 in parallel, the voltage stability in the DC ice melting line can be enhanced, voltage mutations can be prevented, and overvoltage in a peak state can be absorbed, thereby protecting the rectifier inverter 34.

[0042] Optionally, the resistance range of the first resistor R1 is greater than or equal to 7KΩ and less than or equal to 15KΩ; or, the resistance range of the first resistor R1 is greater than or equal to 8KΩ and less than or equal to 16KΩ... and so on, which are not listed here one by one, and it is only necessary to satisfy that the resistance range of the first resistor R1 is within the range of greater than or equal to 7KΩ and less than or equal to 20KΩ. If the resistance value of the first resistor R1 is less than 7KΩ, the resistance value of the first resistor R1 is too small and cannot play a voltage stabilizing role. When the ice-melting line generates a high-amplitude electrostatic induced voltage due to a fault, the high-amplitude electrostatic induced voltage is easy to damage the rectifier converter 34; if the resistance value of the first resistor R1 is greater than 20KΩ, the resistance value of the first resistor R1 is too large, which slows down the circuit response speed, affects the stability of the ice-melting line 100, and increases the cost. In this way, by setting the resistance value of the first resistor in the electrostatic induced voltage absorption circuit 311 to be greater than or equal to 7KΩ and less than or equal to 20KΩ, voltage mutation can be prevented, the voltage stability in the DC ice-melting line can be enhanced, and the rectifier converter 34 can be protected.

[0043] Please continue to refer to Figures 1 to 3As shown in the figure, the nonlinear resistor BL includes a zinc oxide resistor. Specifically, the electrostatic induction voltage suppression device 31 includes an electrostatic induction voltage absorption circuit 311 and a protection circuit 312 connected in parallel. The protection circuit 312 includes a nonlinear resistor BL. The nonlinear resistor BL is used to prevent the electrostatic induction voltage absorption circuit 311 from being damaged by overvoltage when an overvoltage is caused by lightning strike or other reasons. Optionally, the nonlinear resistor BL includes a zinc oxide resistor. The resistance value of the zinc oxide resistor can change with the change of voltage. Under normal operating voltage, the zinc oxide resistor exhibits a high resistance characteristic and can limit the flow of current. Under overvoltage conditions, the zinc oxide resistance drops sharply, allowing a large current to pass, thereby protecting the ice melting line from damage.

[0044] Please refer to Figure 3 The protection circuit 312 includes a parallel gap X1, and a nonlinear resistor BL is connected in parallel with the parallel gap X1.

[0045] Specifically, when the voltage of the nonlinear resistor BL is small, the resistance value is very large, which is equivalent to being disconnected; when an overvoltage is caused by lightning strike or other reasons, the nonlinear resistor BL is turned on and is almost short-circuited. In an optional embodiment provided in the present disclosure, parallel gaps X1 can be installed at both ends of the nonlinear resistor BL to play a protective role. Since the nonlinear resistor BL will explode when the voltage is very large, the parallel gap X1 can protect the nonlinear resistor BL. When a high-amplitude overvoltage occurs, the high-amplitude overvoltage will break down the parallel gap X1 and turn it on. The parallel gap X1 can discharge the high-amplitude overvoltage energy to limit the voltage amplitude on the nonlinear resistor BL, thereby protecting the nonlinear resistor BL.

[0046] It should be noted that the gap distance in the parallel gap X1 can be designed according to the required breakdown voltage, and the present disclosure does not impose any specific limitation on this.

[0047] Thus, by adding a parallel gap X1 at both ends of the nonlinear resistor BL, when the overvoltage is too large, the parallel gap X1 breaks down and conducts to limit the voltage amplitude on the nonlinear resistor BL, thereby reducing the risk of the nonlinear resistor BL exploding when the voltage is too large.

[0048] Please continue to refer to Figure 1The ice melting device 30 also includes: a rectifier inverter 34, a positive terminal switch 51, and a negative terminal switch 52; the input end 341 of the rectifier inverter 34 is connected to the AC power supply 33, the positive output end 342 of the rectifier inverter 34 is connected to the positive terminal switch 51, the positive terminal switch 51 is coupled to the positive outlet cable 41, and the positive outlet cable 41 is coupled to the first ground wire 11; the negative output end 343 of the rectifier inverter 34 is connected to the negative terminal switch 52, the negative terminal switch 52 is coupled to the negative outlet cable 42, and the negative outlet cable 42 is coupled to the second ground wire 21; the electrostatic induction voltage suppression device 31 is respectively connected between the positive terminal switch 51 and the positive outlet cable 41, and between the negative terminal switch 52 and the negative outlet cable 42, and the other end of the electrostatic induction voltage suppression device 31 is grounded.

[0049] Specifically, in an optional embodiment provided by the present disclosure, an input end 341 of the rectifier-converter 34 is connected to an AC power source 33, and the rectifier-converter 34 is used to convert AC power into DC power and output it through the output end. A positive terminal switch 51 is also provided between the positive output end 342 of the rectifier-converter 34 and the positive outlet cable 41, and an electrostatic induction voltage suppression device 31 is provided between the positive terminal switch 51 and the positive outlet cable 41. The other end of the electrostatic induction voltage suppression device 31 is grounded, and the positive outlet cable 41 is also connected to the first ground wire 11. The positive outlet cable 41 Used to transmit the ice-melting current output by the positive output terminal 342 of the rectifier-inverter 34 to the first ground wire 11; a negative terminal switch 52 is also provided between the negative output terminal 343 of the rectifier-inverter 34 and the negative outlet terminal cable 42, and an electrostatic induction voltage suppression device 31 is provided between the negative terminal switch 52 and the negative outlet terminal cable 42, the other end of the electrostatic induction voltage suppression device 31 is grounded, and the negative outlet terminal cable 42 is also connected to the second ground wire 21, and the negative outlet terminal cable 42 is used to transmit the ice-melting current output by the negative output terminal 343 of the rectifier-inverter 34 to the second ground wire 21.

[0050] When it is not necessary to melt the ice on the ground wire, the positive terminal switch 51 and the negative terminal switch 52 are opened, and the ice melting device 30 is disconnected from the ground wire; when it is necessary to melt the ice on the ground wire, the positive terminal switch 51 is closed, the positive output terminal 342 of the rectifier inverter 34 is connected to the positive outlet terminal cable 41, the negative terminal switch 52 is closed, the negative output terminal 343 of the rectifier inverter 34 is connected to the negative outlet terminal cable 42, the first ground wire 11 and the second ground wire 21 input the ice melting current, an electrostatic induction voltage suppression device 31 is connected to the ground in parallel with the positive output terminal 342 of the rectifier inverter 34, and an electrostatic induction voltage suppression device 31 is connected to the ground in parallel with the negative output terminal 343 of the rectifier inverter 34, which is used to absorb the high-amplitude electrostatic induction voltage generated by the fault, control the ice melting device 30 within the voltage range of safe operation, and reduce the locking or damage of the ice melting device 30.

[0051] In this way, by electrically connecting the ground wire to the ice melting device 30, the ice on the ground wire can be melted by utilizing the thermal effect of the current, and by providing the electrostatic induction voltage suppression device 31 between the ground wire and the ice melting device 30, the ice melting device 30 can be controlled within a safe operating voltage range.

[0052] Please continue to refer to Figure 1 A DC reactor 61 is connected in series between the positive output terminal 342 of the rectifier-converter 34 and the positive terminal switch 51 , and a DC reactor 61 is connected in series between the negative output terminal 343 of the rectifier-converter 34 and the negative terminal switch 52 .

[0053] Specifically, in an optional embodiment provided by the present disclosure, the positive output terminal 342 and the negative output terminal 343 of the rectifier inverter 34 in the ice melting device 30 are respectively connected to the DC inductor 61, one DC inductor 61 is connected in series between the positive output terminal 342 of the rectifier inverter 34 and the positive terminal switch 51, and one DC inductor 61 is connected in series between the negative output terminal 343 of the rectifier inverter 34 and the negative terminal switch 52. The DC inductor 61 can filter out the AC component in the DC current, reduce electromagnetic interference and noise, and improve the efficiency and reliability of the circuit.

[0054] In this way, by connecting the DC reactor 61 to the output side of the rectifier-converter 34, harmonic fluctuations can be reduced, the quality of electric energy can be improved, and the efficiency and reliability of the ice-melting circuit can be increased.

[0055] Please refer to Figure 2 and Figure 3 , the capacitance range of the first capacitor C1 is greater than or equal to 20μF. Optionally, the capacitance range of the first capacitor C1 is greater than or equal to 25μF; or, the capacitance range of the first capacitor C1 is greater than or equal to 30μF; or, the capacitance range of the first capacitor C1 is greater than or equal to 35μF... and so on, which are not listed here one by one, and it is only necessary to satisfy that the capacitance range of the first capacitor C1 is within the interval greater than or equal to 20μF. If the capacitance of the first capacitor C1 is less than 20μF, the capacitance of the first capacitor C1 is too small. When the ice-melting line 100 generates a high-amplitude electrostatic induced voltage due to a fault, the high-amplitude electrostatic induced voltage can easily break down the first capacitor C1. In this way, by setting the capacitance of the first capacitor C1 in the electrostatic induced voltage absorption circuit 311 to a range greater than or equal to 20μF, the peak state overvoltage can be absorbed, the voltage mutation can be prevented, the voltage stability in the DC ice-melting line can be enhanced, and the rectifier converter 34 can be protected.

[0056] Please refer to Figure 1 The ground wire insulator 00 is any one of a composite insulator, a glass insulator and a ceramic insulator; the parallel discharge gaps at both ends of the insulator are used for lightning protection.

[0057] Specifically, the ground wire is connected to the tower through the ground wire insulator 00, which can keep the ground wire insulated from the surrounding environment, prevent ground wire current leakage, and ensure the normal operation of the power system. Composite insulators have high mechanical strength, light weight, good insulation performance, arc resistance, and can adapt to complex and changing use environments; glass insulators have high mechanical strength, light weight, stable performance, good transparency, and easy detection of internal defects; ceramic insulators have high mechanical strength, high temperature resistance, high resistivity, good electrical strength, corrosion resistance, and excellent self-cleaning performance.

[0058] Please combine Figures 1 to 3 The present disclosure provides a method for melting ice of an ultra-high voltage direct current insulated ground wire, which is applied to the ultra-high voltage direct current insulated ground wire melting ice line 100 as described above, comprising:

[0059] The AC power supply 33 is connected to the input terminal 341 of the rectifier inverter 34; the rectifier inverter 34 is used to convert the AC power supply 33 into an ice-melting DC current and output it. The output terminal of the rectifier inverter 34 is connected in series with a DC reactor 61, which can filter out the AC component in the ice-melting DC current.

[0060] The positive terminal switch 51 is closed, and the first outdoor switch 12 connected to the first ground line 11 is switched to be connected to the positive outlet cable 41, so that the de-icing DC current can be transmitted from the positive output terminal 342 of the de-icing rectifier converter 34 to the first ground line 11 through the positive outlet cable 41. The negative terminal switch 52 is closed, and the second outdoor switch 22 connected to the second ground line 21 is switched to be connected to the negative outlet cable 42, so that the de-icing DC current can be transmitted from the negative output terminal 343 of the de-icing rectifier converter 34 to the second ground line 21 through the negative outlet cable 42. The isolating switch 32 and the positive terminal switch 51 are closed, so that an electrostatic induction voltage suppression device 31 is connected to the ground in parallel with the positive output terminal 342 of the rectifier converter 34, and the isolating switch 32 and the negative terminal switch 52 are closed, so that an electrostatic induction voltage suppression device 31 is connected to the ground in parallel with the negative output terminal 343 of the rectifier converter 34.

[0061] The rectifier inverter 34 is operated to detect whether the electrostatic induction voltage meets the safety voltage range of the ice-melting device 30 . If it meets the safety voltage range, the rectifier inverter 34 is made to output an ice-melting DC voltage.

[0062] Simulation Verification

[0063] Figure 4 The results of the electrostatic induction voltage simulation experiment using an electrostatic induction voltage suppression device and not using an electrostatic induction voltage suppression device provided by the embodiment of the present disclosure are shown in FIG. Figure 4, (a) is the induced overvoltage amplitude change curve in the UHV DC insulated ground wire ice-melting line 100 after adopting the electrostatic induction voltage suppression device 31 provided by the embodiment of the present disclosure, (b) is the induced overvoltage amplitude change curve of the ground wire in the ice-melting line after insulation transformation using the traditional strategy. It can be seen from the figure that the overvoltage amplitude in (a) is close to 50kV at 0.001s, and the ice-melting line equipped with the electrostatic induction voltage suppression device 31 can significantly reduce the overvoltage amplitude to close to 0kV within the time range of 0.001s to 0.0015s. The overvoltage amplitude in (b) is close to 200kV at 5s. When the electrostatic induction voltage suppression device 31 is not provided in the ice-melting line, the overvoltage amplitude is still in the range of 200kV within the time range of 5s to 10s. It can be seen that the electrostatic induction voltage suppression device 31 provided by the embodiment of the present disclosure is applied to the UHV DC insulated ground wire ice-melting line and can significantly reduce the overvoltage amplitude in a short time to protect the ice-melting line from damage.

[0064] In summary, the present disclosure provides a UHV DC insulated ground wire de-icing circuit and de-icing method. By setting an electrostatic induction voltage suppression device between the de-icing device and the ground wire, the electrostatic induction voltage suppression device includes a parallel electrostatic induction voltage absorption circuit and a protection circuit. The electrostatic induction voltage absorption circuit is used to stabilize the voltage during the de-icing process, and control the de-icing device within a safe operating voltage range. The protection circuit is used to prevent overvoltage from breaking down the electrostatic induction voltage absorption device. By adding parallel gaps at both ends of the nonlinear resistor, when the overvoltage is too large, the parallel gaps can be broken down and turned on to limit the voltage amplitude on the nonlinear resistor, thereby reducing the risk of the nonlinear resistor bursting when the voltage is too large. By electrically connecting the ground wire to the de-icing device, the thermal effect of the current can be used to melt the ice on the ground wire. By setting an electrostatic induction voltage suppression device between the ground wire and the de-icing device, the de-icing device can be controlled within a safe operating voltage range. By connecting a DC reactor on the output side of the rectifier converter, harmonic fluctuations can be reduced, the power quality can be improved, and the efficiency and reliability of the de-icing circuit can be improved.

[0065] The above description is only a specific embodiment of the present disclosure, so that those skilled in the art can understand or implement the present disclosure. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present disclosure. Therefore, the present disclosure will not be limited to the embodiments described herein, but will conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A UHV DC insulated ground wire ice melting line, characterized in that: include: a first side pole tower, a second side pole tower, a first ground wire, a second ground wire, a ground wire insulator, and an ice melting device; The first ground wire is connected to the first side pole tower through the ground wire insulator, and the second ground wire is connected to the second side pole tower through the ground wire insulator; the first ends of the first ground wire and the second ground wire are connected to the ice melting device, and the second ends of the first ground wire and the second ground wire are short-circuited and grounded; The ice melting device includes an electrostatic induction voltage suppression device, and the electrostatic induction voltage suppression device includes an isolating switch; the electrostatic induction voltage suppression device includes an electrostatic induction voltage absorption circuit and a protection circuit, the protection circuit is connected in parallel with the electrostatic induction voltage absorption circuit, the electrostatic induction voltage absorption circuit includes a first resistor and a first capacitor connected in parallel, and the protection circuit includes a nonlinear resistor.

2. The ultra-high voltage direct current insulated ground wire ice-melting line according to claim 1, characterized in that: The resistance range of the first resistor is greater than or equal to 7KΩ and less than or equal to 20KΩ.

3. The ultra-high voltage direct current insulated ground wire ice-melting line according to claim 1, characterized in that: The nonlinear resistor includes a zinc oxide resistor.

4. The UHV DC insulated ground wire ice melting line according to claim 1, characterized in that: The protection circuit includes a parallel gap, and the nonlinear resistor is connected in parallel with the parallel gap.

5. The ultra-high voltage direct current insulated ground wire ice-melting line according to claim 1, characterized in that: The ice melting device also includes: a rectifier converter, a positive terminal switch, and a negative terminal switch; The input end of the rectifier-converter is connected to an AC power supply, the positive output end of the rectifier-converter is connected to a positive terminal switch, the positive terminal switch is coupled to a positive outlet cable, and the positive outlet cable is coupled to a first ground wire; the negative output end of the rectifier-converter is connected to a negative terminal switch, the negative terminal switch is coupled to a negative outlet cable, and the negative outlet cable is coupled to a second ground wire; The electrostatic induction voltage suppression device is respectively connected between the positive terminal switch and the positive outlet cable, and between the negative terminal switch and the negative outlet cable, and the other end of the electrostatic induction voltage suppression device is grounded.

6. The UHV DC insulated ground wire ice melting line according to claim 5, characterized in that: A DC reactor is connected in series between the positive output end of the rectifier-converter and the positive terminal switch, and a DC reactor is connected in series between the negative output end of the rectifier-converter and the negative terminal switch.

7. The ultra-high voltage direct current insulated ground wire ice-melting line according to claim 1, characterized in that: The capacitance range of the first capacitor is greater than or equal to 20 μF.

8. The ultra-high voltage direct current insulated ground wire ice-melting line according to claim 1, characterized in that: The ground wire insulator is any one of a composite insulator, a glass insulator and a ceramic insulator; and the discharge gaps connected in parallel at both ends of the insulator are used for lightning protection.

9. A method for melting ice of an ultra-high voltage direct current insulated ground wire, applied to an ultra-high voltage direct current insulated ground wire melting ice line as claimed in any one of claims 1 to 8, characterized in that: include: Connect the AC power supply to the input terminal of the rectifier converter; Close the positive terminal switch to connect the positive output terminal of the rectifier converter and the first ground wire, and close the negative terminal switch to connect the negative output terminal of the rectifier converter and the second ground wire; The rectifier inverter is operated to detect whether the electrostatic induction voltage meets the safety voltage range of the ice-melting device. If so, the rectifier inverter is made to output an ice-melting DC voltage.

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