Ground wire de-icing circuit suitable for de-icing ground wires of power transmission lines without power outages

Abstract

The present invention discloses a ground conductor de-icing circuit for non-stop de-icing of power grid transmission lines. An A-phase busbar, a B-phase busbar, and a C-phase busbar are connected to an A-phase conductor, a B-phase conductor, and a C-phase conductor, respectively. An induced voltage suppression circuit and an overvoltage protection circuit are respectively provided on the A-phase busbar, the B-phase busbar, and the C-phase busbar. The induced voltage suppression circuit reduces the induced voltage of the power grid transmission line and limits the induced voltage to within the insulation level of the DC side of the de-icing power supply. The overvoltage protection circuit reduces the overvoltage of the lightning intrusion wave of the transmission line, the disconnection of the de-icing circuit, and the resonant overvoltage that may occur in the de-icing system, thereby solving the technical problem that the existing de-icing device for transmission lines has poor performance in suppressing the induced voltage and protecting the overvoltage in the de-icing circuit.

Description

Technical Field

[0001] The present invention relates to the technical field of ice-melting circuits for power grid transmission lines, and in particular to a ground wire ice-melting circuit suitable for melting ice on ground wires of power grid transmission lines without power outages. Background Art

[0002] Overhead transmission lines are the primary channels for long-distance power transmission and are crucial for ensuring the safe operation of power grids. In rainy and snowy weather, transmission line ground wires are prone to ice buildup, causing transmission line outages or tripping. Severe ice buildup can cause tower collapse and line disconnection, seriously threatening the safe operation of the power grid. Therefore, timely de-icing of transmission line ground wires is crucial for ensuring safe power grid operation.

[0003] Existing transmission line de-icing devices primarily include grid-commutated converter DC de-icing devices, modular multilevel converter DC de-icing devices using full-bridge submodules, fully controlled current source converter DC de-icing devices, variable frequency current source low-frequency de-icing devices, and uncontrolled DC de-icing devices using diode rectification. De-icing devices typically have insulation levels significantly lower than the de-icing lines. Lightning intrusion wave overvoltages caused by lightning strikes on the de-icing lines can endanger the safety of the de-icing devices. Protection also requires protection against resonant overvoltages in the de-icing system and operational overvoltages caused by disconnections in the de-icing lines. Furthermore, the induced voltage and current in the de-icing circuit also need to be suppressed. Existing transmission line de-icing devices have poor performance in suppressing induced voltage and overvoltage protection in the de-icing circuit. Improving the induced voltage suppression and overvoltage protection performance in the de-icing circuit of the ground conductor of a transmission line is a technical problem that needs to be urgently addressed by those skilled in the art. Summary of the Invention

[0004] The present invention provides a ground wire de-icing circuit suitable for de-icing ground wires of power grid transmission lines without power outages, and is used to solve the technical problems of poor induced voltage suppression and overvoltage protection performance of existing transmission line de-icing devices in de-icing circuits.

[0005] In view of this, the present invention provides a ground wire de-icing circuit suitable for de-icing ground wires of power grid transmission lines without power outages, comprising an de-icing power supply, an induced voltage suppression circuit, an overvoltage protection circuit, an A-phase busbar, a B-phase busbar, a C-phase busbar, an A-phase conductor, a B-phase conductor, a C-phase conductor, and a ground wire;

[0006] The ice-melting power supply is used to convert AC power into DC power. There is no grounding point on the DC side of the ice-melting power supply.

[0007] The induced voltage suppression circuit includes a first resistor, a second resistor, and a capacitor, wherein the second resistor and the capacitor are connected in series and then in parallel with the first resistor, one end of the first resistor is connected to one end of the second resistor, the other end of the first resistor is grounded, the other end of the second resistor is connected to one end of the capacitor, and the other end of the capacitor shares a common ground with the ground end of the first resistor;

[0008] The overvoltage protection circuit includes a zinc oxide lightning arrester and a protection gap, wherein the zinc oxide lightning arrester and the protection gap are connected in parallel and have one end thereof shared by a common ground;

[0009] A first isolating switch and a second isolating switch are provided in parallel at one DC output end of the ice-melting power supply, and a third isolating switch and a fourth isolating switch are provided in parallel at another DC output end of the ice-melting power supply;

[0010] The first isolating switch is connected to one end of the A-phase busbar, the other end of the A-phase busbar is connected to one end of the A-phase conductor, and the A-phase busbar is connected to an induced voltage suppression circuit and an overvoltage protection circuit;

[0011] The second isolating switch is connected to one end of the B-phase busbar, the other end of the B-phase busbar is connected to one end of the B-phase conductor, and the B-phase busbar is connected to an induced voltage suppression circuit and an overvoltage protection circuit;

[0012] The third disconnector is connected to one end of the B-phase busbar;

[0013] The fourth isolating switch is connected to one end of the C-phase busbar, the other end of the C-phase busbar is connected to one end of the C-phase conductor, and the C-phase busbar is connected to an induced voltage suppression circuit and an overvoltage protection circuit;

[0014] The other end of the A-phase conductor is connected to the other end of the B-phase conductor through the fifth isolating switch, the other end of the B-phase conductor is connected to the other end of the C-phase conductor through the sixth isolating switch, the A-phase conductor is connected to the ground wire through the seventh isolating switch, and the C-phase conductor is connected to the ground wire through the eighth isolating switch.

[0015] Optionally, the other end of the A-phase busbar is connected to one end of the A-phase conductor through a first ice-melting line disconnector, the other end of the B-phase busbar is connected to one end of the B-phase conductor through a second ice-melting line disconnector, and the other end of the C-phase busbar is connected to one end of the C-phase conductor through a third ice-melting line disconnector.

[0016] Optionally, the connection end between the first ice-melting line disconnector and the A-phase busbar, the connection end between the second ice-melting line disconnector and the B-phase busbar, and the connection end between the third ice-melting line disconnector and the C-phase busbar are respectively grounded through the ice-melting busbar grounding switch.

[0017] Optionally, the two DC output terminals of the ice-melting power supply are grounded respectively through DC bus grounding switches.

[0018] Optionally, the value of the second resistor in the induced voltage suppression circuit is:

[0019]

[0020] Among them, R C is the resistance of the second resistor, k is the coefficient, L is the equivalent inductance of the AC side of the ice-melting power supply, and C is the capacitance of the capacitor.

[0021] Optionally, the capacitance of the capacitor is 1.0 to 3.0 times the total capacitance of the conductors and ground wires in the same tower section as the non-stop power section in the ice melting line where the capacitor is located, and the coefficient k is in the range of 1.0 to 2.0.

[0022] Optionally, the value of the first resistor is:

[0023] R H =U dc / I ds

[0024] Among them, R H is the resistance of the first resistor, U dc is the rated voltage of the busbar connected to the first resistor, I ds is the discharge current of the first resistor.

[0025] Optionally, the rated voltage of the zinc oxide lightning arrester in the overvoltage protection circuit is 1.05 to 1.10 times the maximum continuous operating voltage of the installation location of the zinc oxide lightning arrester.

[0026] Optionally, both ends of the A-phase conductor, both ends of the B-phase conductor, and both ends of the C-phase conductor are grounded through conductor grounding switches, respectively.

[0027] Optionally, the ground wire is grounded via a ground wire grounding switch.

[0028] It can be seen from the above technical solutions that the embodiments of the present invention have the following advantages:

[0029] The present invention provides a ground wire de-icing circuit suitable for de-icing ground wires of power grid transmission lines without power outages. The A-phase busbar, B-phase busbar, and C-phase busbar of the de-icing power supply are connected to the A-phase conductor, B-phase conductor, and C-phase conductor, respectively. The A-phase busbar, B-phase busbar, and C-phase busbar are respectively provided with an induced voltage suppression circuit and an overvoltage protection circuit. The induced voltage suppression circuit reduces the induced voltage of the power grid transmission line and limits the induced voltage to within the insulation level of the DC side of the de-icing power supply. The overvoltage protection circuit reduces the overvoltage of the lightning intrusion wave of the transmission line, the operating overvoltage caused by the disconnection of the de-icing circuit, and the resonant overvoltage that may occur in the de-icing system, thereby solving the technical problem that the existing de-icing device for transmission line has poor induced voltage suppression and overvoltage protection performance in the de-icing circuit.

[0030] At the same time, the ground wire de-icing circuit provided by the present invention is suitable for de-icing the ground wire of the power grid transmission line without power outage. It does not require the power grid transmission line to be shut down before de-icing the ground wire, thus solving the technical problem that the existing de-icing device requires the transmission line to be shut down before de-icing the ground wire. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying any creative work.

[0032] Figure 1 The circuit principle diagram of a ground wire de-icing circuit provided in an embodiment of the present invention is suitable for de-icing ground wires of power grid transmission lines without power outages. DETAILED DESCRIPTION

[0033] In order to enable those skilled in the art to better understand the solutions of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts shall fall within the scope of protection of the present invention.

[0034] For easier understanding, see Figure 1 The present invention provides an embodiment of a ground wire de-icing circuit suitable for de-icing ground wires of power grid transmission lines without power outages, including an de-icing power supply 1, an induced voltage suppression circuit 2, an overvoltage protection circuit 3, an A-phase busbar MA, a B-phase busbar MB, a C-phase busbar MC, an A-phase conductor DA, a B-phase conductor DB, a C-phase conductor DC, and a ground wire LD.

[0035] The ice-melting power supply 1 is used to convert alternating current into direct current. The direct current side of the ice-melting power supply 1 has no grounding point.

[0036] The induced voltage suppression circuit 2 includes a first resistor R H , the second resistor R C and capacitor C, second resistor R C After being connected in series with the capacitor C and the first resistor R H In parallel, the first resistor R H One end of the second resistor R C One end of the first resistor R H The other end of the second resistor R CThe other end of the capacitor C is connected to one end of the first resistor R H The ground terminals are connected to the common ground.

[0037] The overvoltage protection circuit 3 includes a zinc oxide lightning arrester F and a protection gap G. The zinc oxide lightning arrester F and the protection gap G are connected in parallel and have one end connected to a common ground.

[0038] A first isolating switch S1 and a second isolating switch S2 are connected in parallel to one DC output end of the ice-melting power supply 1 , and a third isolating switch S3 and a fourth isolating switch S4 are connected in parallel to the other DC output end of the ice-melting power supply 1 .

[0039] The first isolating switch S1 is connected to one end of the A-phase busbar MA, the other end of the A-phase busbar MA is connected to one end of the A-phase conductor DA, and the A-phase busbar MA is connected to an induced voltage suppression circuit 2 and an overvoltage protection circuit 3.

[0040] The second isolating switch S2 is connected to one end of the B-phase busbar MB, the other end of the B-phase busbar MB is connected to one end of the B-phase conductor DB, and the B-phase busbar DB is connected to the induced voltage suppression circuit 2 and the overvoltage protection circuit 3.

[0041] The third isolating switch S3 is connected to one end of the B-phase busbar MB.

[0042] The fourth isolating switch S4 is connected to one end of the C-phase busbar MC, the other end of the C-phase busbar MC is connected to one end of the C-phase conductor DC, and the C-phase busbar MC is connected to the induced voltage suppression circuit 2 and the overvoltage protection circuit 3.

[0043] The other end of the A-phase conductor DA is connected to the other end of the B-phase conductor DB through the fifth isolating switch S5, the other end of the B-phase conductor DB is connected to the other end of the C-phase conductor DC through the sixth isolating switch S6, the A-phase conductor DA is connected to the ground wire LD through the seventh isolating switch S7, and the C-phase conductor DC is connected to the ground wire LD through the eighth isolating switch S8.

[0044] It should be noted that if Figure 1 As shown, the induced voltage suppression circuit 2 includes a first resistor R H , the second resistor R C and capacitor C, second resistor R C After being connected in series with the capacitor C, it is connected in parallel with the first resistor. The first resistor R H One end of the second resistor R C One end of the first resistor R H The other end of the second resistor R C The other end of the capacitor is connected to one end of the capacitor C, and the other end of the capacitor is connected to the first resistor R HThe A-phase busbar MA, the B-phase busbar MB and the C-phase busbar MC are connected to the ground through the first resistor R of the induced voltage suppression circuit 2. H and the second resistor R C The common end of the induced voltage suppression circuit 2 is connected to the induced voltage suppression circuit 2. The induced voltage suppression circuit 2 is used to reduce the induced voltage of the power transmission line of the power grid to limit the induced voltage to the insulation level of the DC side of the ice melting power supply. H It is used to discharge the induced charge of the DC line. When the DC line melts ice, there is ion flow field charge accumulation, which is passed through the first resistor R H When ice melting is required, the ground wire LD can be connected to the positive and negative poles of the ice-melting power supply 1 through the seventh isolating switch S7, the eighth isolating switch S8, the A-phase conductor DA, and the C-phase conductor DC, or it can be connected to the positive and negative poles of the ice-melting power supply 1 through other means.

[0045] In one embodiment, the second resistor R in the induced voltage suppression circuit C The value of is:

[0046]

[0047] Among them, R C is the resistance of the second resistor, k is the coefficient, L is the equivalent inductance of the AC side of the ice-melting power supply, and C is the capacitance of the capacitor.

[0048] The capacitance value of capacitor C is 1.0 to 3.0 times the total capacitance of the conductor and ground wire to the ground in the same tower section as the non-stop power section in the ice melting line where capacitor C is located, and the coefficient k ranges from 1.0 to 2.0.

[0049] The first resistor R H The value of is:

[0050] R H =U dc / I ds

[0051] Among them, R H is the resistance of the first resistor, U dc is the rated voltage of the busbar connected to the first resistor, I ds is the discharge current of the first resistor, the range of the discharge current is 10mA-50mA, the first resistor R H It is smaller than the equivalent resistance of the ion flow field of the conductor section on the same tower as the non-stop power line in the ice melting circuit, and smaller than the total resistance of the insulators on the ground wire section on the same tower as the non-stop power line in the ice melting circuit. R H The value is in the range of 50kΩ-1000kΩ.

[0052] The overvoltage protection circuit 3 includes a zinc oxide lightning arrester F and a protective gap G. The A-phase busbar MA, the B-phase busbar MB, and the C-phase busbar MC are connected to the overvoltage protection circuit 3 through the common terminals of the zinc oxide lightning arrester F and the protective gap G of the overvoltage protection circuit 3. The overvoltage protection circuit 3 is used to reduce the overvoltage of lightning intrusion waves on the transmission line, the operating overvoltage caused by disconnection of the ice melting circuit, and the resonant overvoltage that may occur in the ice melting system. Among them, the protective gap G is mainly used to prevent resonance and protect the zinc oxide lightning arrester F to avoid damage to the zinc oxide lightning arrester F. In one embodiment, the rated voltage of the zinc oxide lightning arrester F in the overvoltage protection circuit 3 is 1.05 to 1.10 times the maximum continuous operating voltage of the zinc oxide lightning arrester F installation location. The protective gap length of the protective gap G should be selected according to the gap corresponding to the 90% operating impulse protection level and the 90% lightning impulse protection level of the lightning arrester.

[0053] In one embodiment, the other end of the A-phase busbar MA is connected to one end of the A-phase conductor DA via a first de-icing circuit disconnector S9, the other end of the B-phase busbar MB is connected to one end of the B-phase conductor DB via a second de-icing circuit disconnector S10, and the other end of the C-phase busbar MC is connected to one end of the C-phase conductor DC via a third de-icing circuit disconnector S11. The connection between the first de-icing circuit disconnector S9 and the A-phase busbar MA, the connection between the second de-icing circuit disconnector S10 and the B-phase busbar MB, and the connection between the third de-icing circuit disconnector S11 and the C-phase busbar MC are each grounded via a de-icing busbar grounding switch S12. When the A-phase busbar MA, B-phase busbar MB, and C-phase busbar MC require inspection and maintenance, the de-icing busbar grounding switch S12 is closed to ensure personnel safety. The two DC output terminals of ice-melting power supply 1 are grounded via DC busbar grounding switch S13. This switch should be closed when disconnectors S1, S2, S3, and S4 are open. It should be closed when ice-melting power supply 1 requires inspection or maintenance to ensure personnel safety. The ends of phase A conductor DA, phase B conductor DB, and phase C conductor DC are grounded via conductor grounding switch S14. This switch should be closed when inspection or maintenance is required to ensure personnel safety. Ground conductor LD is grounded via grounding switch S15. This switch should be closed when the ground conductor is not melting to ensure unimpeded transmission line operation.

[0054] The present invention provides a ground wire de-icing circuit suitable for de-icing ground wires of power grid transmission lines without power outages. The A-phase busbar, B-phase busbar, and C-phase busbar of the de-icing unit are connected to the A-phase conductor, B-phase conductor, and C-phase conductor, respectively. The A-phase busbar, B-phase busbar, and C-phase busbar are respectively provided with an induced voltage suppression circuit and an overvoltage protection circuit. The induced voltage suppression circuit reduces the induced voltage of the power grid transmission line and limits the induced voltage to within the insulation level of the DC side of the de-icing power supply. The overvoltage protection circuit reduces the overvoltage of the lightning intrusion wave of the transmission line, the operating overvoltage caused by the disconnection of the de-icing circuit, and the resonant overvoltage that may occur in the de-icing system, thereby solving the technical problem that the existing de-icing device for transmission line has poor induced voltage suppression and overvoltage protection performance in the de-icing circuit.

[0055] At the same time, the ground wire de-icing circuit provided by the present invention is suitable for de-icing the ground wire of the power grid transmission line without power outage. It does not require the power grid transmission line to be shut down before de-icing the ground wire, thus solving the technical problem that the existing de-icing device requires the transmission line to be shut down before de-icing the ground wire.

[0056] As described above, the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that the technical solutions described in the above embodiments can still be modified, or some of the technical features thereof can be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A ground wire de-icing circuit for de-icing power transmission lines without power outages, characterized in that: It includes an ice melting power supply, an induced voltage suppression circuit, an overvoltage protection circuit, an A-phase busbar, a B-phase busbar, a C-phase busbar, an A-phase conductor, a B-phase conductor, a C-phase conductor, and a ground wire; The ice-melting power supply is used to convert AC power into DC power. There is no grounding point on the DC side of the ice-melting power supply. The induced voltage suppression circuit includes a first resistor, a second resistor, and a capacitor, wherein the second resistor and the capacitor are connected in series and then in parallel with the first resistor, one end of the first resistor is connected to one end of the second resistor, the other end of the first resistor is grounded, the other end of the second resistor is connected to one end of the capacitor, and the other end of the capacitor shares a common ground with the ground end of the first resistor; The overvoltage protection circuit includes a zinc oxide lightning arrester and a protection gap, wherein the zinc oxide lightning arrester and the protection gap are connected in parallel and have one end thereof shared by a common ground; A first isolating switch and a second isolating switch are provided in parallel at one DC output end of the ice-melting power supply, and a third isolating switch and a fourth isolating switch are provided in parallel at another DC output end of the ice-melting power supply; The first isolating switch is connected to one end of the A-phase busbar, the other end of the A-phase busbar is connected to one end of the A-phase conductor, and the A-phase busbar is connected to an induced voltage suppression circuit and an overvoltage protection circuit; The second isolating switch is connected to one end of the B-phase busbar, the other end of the B-phase busbar is connected to one end of the B-phase conductor, and the B-phase busbar is connected to an induced voltage suppression circuit and an overvoltage protection circuit; The third disconnector is connected to one end of the B-phase busbar; The fourth isolating switch is connected to one end of the C-phase busbar, the other end of the C-phase busbar is connected to one end of the C-phase conductor, and the C-phase busbar is connected to an induced voltage suppression circuit and an overvoltage protection circuit; The other end of the A-phase conductor is connected to the other end of the B-phase conductor through the fifth isolating switch, the other end of the B-phase conductor is connected to the other end of the C-phase conductor through the sixth isolating switch, the A-phase conductor is connected to the ground wire through the seventh isolating switch, and the C-phase conductor is connected to the ground wire through the eighth isolating switch.

2. The ground wire ice melting circuit for power grid transmission line non-stop ice melting according to claim 1, characterized in that: The other end of the A-phase busbar is connected to one end of the A-phase conductor through a first ice-melting line disconnector, the other end of the B-phase busbar is connected to one end of the B-phase conductor through a second ice-melting line disconnector, and the other end of the C-phase busbar is connected to one end of the C-phase conductor through a third ice-melting line disconnector.

3. The ground wire ice melting circuit for power grid transmission line non-stop ice melting according to claim 2, characterized in that: The connection end of the first ice-melting line disconnector and the A-phase busbar, the connection end of the second ice-melting line disconnector and the B-phase busbar, and the connection end of the third ice-melting line disconnector and the C-phase busbar are respectively grounded through the ice-melting busbar grounding switches.

4. The ground wire ice melting circuit for power grid transmission line non-stop ice melting according to claim 1, characterized in that: The two DC output terminals of the ice-melting power supply are grounded through DC bus grounding switches respectively.

5. The ground wire ice melting circuit for power grid transmission line non-stop ice melting according to any one of claims 1 to 4, characterized in that: The value of the second resistor in the induced voltage suppression circuit is: in, is the resistance of the second resistor, k is the coefficient, L is the equivalent inductance of the AC side of the ice-melting power supply, and C is the capacitance of the capacitor.

6. The ground wire ice melting circuit for power grid transmission lines without power outages according to claim 5, characterized in that: The capacitance value of the capacitor is 1.0~3.0 times the total capacitance of the conductor and ground wire to the ground in the same tower section as the non-stop power section in the ice melting line where the capacitor is located, and the coefficient k ranges from 1.0 to 2.

0.

7. The ground wire ice melting circuit for power transmission line non-stop ice melting according to claim 5, characterized in that: The value of the first resistor is: in, is the resistance of the first resistor, is the rated voltage of the busbar connected to the first resistor, is the discharge current of the first resistor.

8. The ground wire ice melting circuit for power grid transmission lines without power outage according to claim 1, characterized in that: The rated voltage of the zinc oxide lightning arrester in the overvoltage protection circuit is 1.05~1.10 times the maximum continuous operating voltage of the zinc oxide lightning arrester installation location.

9. The ground wire ice melting circuit for power grid transmission lines without power outage according to claim 1, characterized in that: Both ends of the A-phase conductor, both ends of the B-phase conductor, and both ends of the C-phase conductor are grounded through conductor grounding switches, respectively.

10. The ground wire ice melting circuit for power grid transmission lines without power outage according to claim 1, characterized in that: The ground wire is grounded through the ground wire grounding switch.

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