Ice melting system and ice melting method for mixed linear ground wire of ultra-high voltage transmission line

Abstract

The invention provides an ultra-high voltage transmission line hybrid line type ground wire ice melting system and an ice melting method. The system comprises a first section ground wire, a second section ground wire, an ice melting device, an ice melting access switch, an ice melting current increasing switch, a parallel reactive current increasing unit and an ice melting grounding unit. The first section ground wire and the second section ground wire respectively comprise two ground wires with the same or similar specifications, and the ground wires in the first section ground wire and the second section ground wire are electrically isolated from an iron tower through the ground wire insulation unit. Through-flow ice melting of two kinds of mixed line type ground wires can be realized at the same time without changing the existing ground wires and towers, ice melting currents in different sections can be decoupled mutually, and the application range of ground wire ice melting and the ice melting implementation efficiency are improved.

Description

Technical Field

[0001] This invention relates to the field of de-icing technology for power transmission lines, and in particular to a de-icing system and method for a hybrid ground wire of an ultra-high voltage power transmission line. Background Technology

[0003] In response to the problem of icing on the ground wires of ultra-high voltage (UHV) transmission lines, domestic technologies for uninterrupted ground wire de-icing have been developed and applied in recent years. For example, existing technologies include a segmented de-icing system for UHV transmission line ground wires. This system involves partially insulating the ground wires in icy sections of the UHV transmission line, connecting a de-icing device to one end, and using two ground wires short-circuited at the other end to form a de-icing current-carrying loop. Then, localized current-carrying de-icing is performed on the section of the UHV line ground wire between the de-icing device connection point and the short-circuit point.

[0004] Because the grounding wires and meteorological conditions along ultra-high voltage (UHV) transmission lines often vary significantly, the anti-icing design levels also differ in different sections. In severely iced sections, the lines are typically designed and constructed using conductors, grounding wires, towers, and spans with stronger anti-icing capabilities but higher costs. Conversely, in lightly iced sections, conductors, grounding wire types, and tower spans with weaker anti-icing capabilities and lower costs are often used. Therefore, in UHV grounding wire de-icing systems, mixed-type grounding wires, i.e., grounding wires of different types and specifications within the same line, are frequently encountered, which can easily create current flow bottlenecks in the upstream de-icing flow section.

[0005] To address the de-icing requirements of this type of mixed ground wire, there are generally two existing de-icing methods. One is to try to select the expected de-icing current within the intersection range of different specifications of ground wires, but this can easily lead to poor de-icing current controllability or even failure to implement current-driven de-icing. The other method is to replace the original small-section ground wire with a ground wire of the same specification as the ground wire in the heavy icing area when upgrading the ground wire de-icing system. This method is difficult to implement due to its large workload, long time, and high cost.

[0006] Therefore, how to achieve de-icing of mixed-type ground wires and decouple the de-icing currents of different specifications of ground wires without changing the existing ground wires and towers has become a technical problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0007] To address the aforementioned technical problems, this invention provides a ground wire de-icing system and method for mixed-type ground wires in ultra-high voltage transmission lines. This system enables simultaneous de-icing of ground wires of different specifications without altering the existing ground wire and tower specifications, and the de-icing currents of different ground wire specifications can be decoupled from each other.

[0008] In a first aspect, the present invention provides a hybrid linear ground wire de-icing system for ultra-high voltage transmission lines, comprising: a section group, wherein the section group includes a first section ground wire, a second section ground wire, a de-icing device, a de-icing access switch, a de-icing current booster switch, and a parallel reactive current booster unit; The first section ground wire and the second section ground wire each include two ground wires of the same or similar specifications. The two ground wires in the first section ground wire are respectively connected to the two ground wires in the second section ground wire at the corresponding boundary point. The corresponding ground wires are respectively connected to the two ends of the parallel reactive current boosting unit at the boundary point via the ice melting current boosting switch. The parallel reactive current boosting unit is used for reactive current compensation, so that the currents of the first section ground wire and the second section ground wire are different, so as to achieve decoupling control of the ice melting current of the first section ground wire and the second section ground wire. In the second section of the ground wire, the end of the two ground wires that is furthest from the first section of the ground wire is short-circuited and grounded; The two ends of the ice-melting device are respectively connected to the two ground wires of the first section ground wire via the ice-melting access switch. The ice-melting device is used to provide power for the first section ground wire and the second section ground wire during ice melting.

[0009] Optionally, the first section ground wire includes a first ground wire and a second ground wire, the second section ground wire includes a third ground wire and a fourth ground wire, wherein the first ground wire and the third ground wire are connected at a first dividing point, and the second ground wire and the fourth ground wire are connected at a second dividing point. The first dividing point between the first ground wire and the third ground wire is connected to one end of the parallel reactive power boosting unit via a first ice-melting boosting switch, and the second dividing point between the second ground wire and the fourth ground wire is connected to the other end of the parallel reactive power boosting unit via a second ice-melting boosting switch.

[0010] It includes multiple segment groups and multiple ground wire separation units. In two adjacent segment groups, the end of the ground wire of the first segment of one segment group that is far from the ground wire of the second segment is electrically disconnected from the end of the ground wire of the second segment of another segment group that is far from the ground wire of the first segment through the ground wire separation unit.

[0011] Optionally, the first ground wire of the first segment ground wire in a segment group is connected to the third ground wire of the second segment ground wire in another segment group through the ground wire separation unit, and the second ground wire of the first segment ground wire in a segment group is connected to the fourth ground wire of the second segment ground wire in another segment group through the ground wire separation unit.

[0012] Optionally, the AC de-icing device is a three-phase to single-phase power frequency transformer or an inverter power supply.

[0013] Optionally, the parallel reactive power booster unit includes a groupable capacitor bank.

[0014] Optionally, the grounding insulation unit includes an insulator or surge arrester with parallel discharge gaps.

[0015] Optionally, the system may further include a monitoring unit, which is used to detect the current flowing through the first section ground wire and the second section ground wire and the ground wire temperature in real time, and adjust the output voltage and current of the de-icing device and the operating parameters of the parallel reactive power booster unit in real time according to the monitored current and the ground wire temperature, so that the current flowing through the first section ground wire and the second section ground wire is within their respective suitable de-icing current ranges.

[0016] Based on the same inventive concept, this invention provides a method for de-icing the ground wire of a mixed-type UHV transmission line, applied to the aforementioned UHV transmission line mixed-type ground wire de-icing system. The UHV transmission line mixed-type ground wire de-icing method includes: The required de-icing current is calculated based on the specifications of the ground wires in the first and second sections of the ultra-high voltage transmission line, meteorological parameters along the line, and the expected de-icing time. , ; For applications where this de-icing method is applicable, the parameters of the required parallel reactive power booster unit should be determined based on the line parameters. After determining the parameters of the parallel reactive power booster unit, the required de-icing current for the first section ground wire and the second section ground wire, the rated parameters of the de-icing device are designed. The rated parameters of the de-icing device and the parameters of the parallel reactive power booster unit are applied to the de-icing system of the hybrid linear ground wire of the UHV transmission line, and the de-icing access switch and the de-icing booster switch are closed to carry out de-icing.

[0017] Optionally, the applicability of this de-icing method can be evaluated based on the de-icing current and AC impedance parameters of the first and second grounding sections. Specifically, the parameters must meet the following conditions:

[0018] in, This indicates the expected de-icing current value of the ground wire in the first section. This indicates the expected de-icing current value of the ground wire in the second section. , These represent the total resistance and total inductive reactance of the ground wire in the second section, respectively.

[0019] Optionally, the parameters of the parallel reactive power booster unit include the rated voltage of the parallel reactive power booster unit. Rated current and impedance parameters The calculation formula for the parameters of the parallel reactive power booster unit is as follows:

[0020] in, This indicates the active load factor corresponding to the ground wire impedance of the second section. ; This indicates the reactive load factor corresponding to the ground wire impedance of the second section. .

[0021] Optionally, the rated parameters of the ice-melting device include rated output current, rated output voltage, and rated capacity. The rated output current of the ice-melting device is designed according to the ice-melting current required by the ground wire in the first section. The rated output voltage of the ice-melting device is designed according to the equivalent impedance of the current-carrying section through which the ice-melting current required by the ground wire in the first section flows, taking into account the compensation effect of the parallel reactive power boosting unit. The rated capacity of the ice-melting device is designed based on the rated voltage and rated current of the ice-melting device.

[0022] Optionally, under the non-ice-melting state of the ground wire of the UHV transmission line during normal operation, the ice-melting connection switch and the ice-melting current-boosting switch are disconnected, and the UHV line operates normally. When the ice accumulation on the ground wire reaches the thickness required to initiate ice melting, the UHV transmission line hybrid ground wire ice melting system is activated to prepare for the hybrid ground wire. Before ice melting, while keeping the ice melting device de-energized, the ice melting connection switch and the ice melting current booster switch are closed, and the parallel reactive current booster unit is adjusted to the expected parameters and status. Power is supplied to the ice-melting device and its output voltage is adjusted so that the current of the ground wire in the first section and the current of the ground wire in the second section reach their expected design values. When the line parameters deviate from the design values ​​and adjusting the voltage of the ice-melting device alone cannot make the two currents reach their expected design values ​​at the same time, the parameters of the parallel reactive power booster unit can also be adjusted so that the two currents reach their expected design values ​​at the same time. Maintain the current in the two sections at the expected design value and continue to operate until all the ice on the ground wires of the two sections falls off; Turn off the power to the de-icing device, disconnect the de-icing connection switch and the de-icing current booster switch, and restore the UHV line to normal operation.

[0023] Compared with the prior art, the technical solution provided by the embodiments of the present invention has the following advantages: The present invention provides a hybrid ground wire de-icing system and de-icing method for transmission lines. For hybrid ground wires in icing sections of ultra-high-voltage lines, it can achieve simultaneous current flow de-icing of two hybrid ground wires without changing the existing ground wires and towers. Moreover, the de-icing currents of different sections can be decoupled from each other, avoiding the problem that the de-icing currents of different specifications of ground wires are different, which may prevent simultaneous current flow de-icing or require the existing ground wires of different specifications to be modified to a unified specification before de-icing can be carried out. This improves the applicability of ground wire de-icing and the efficiency of de-icing implementation. Attached Figure Description

[0024] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with the invention and, together with the description, serve to explain the principles of the invention.

[0025] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0026] Figure 1 The diagram shown is a structural schematic of a hybrid linear ground wire de-icing system for ultra-high voltage transmission lines according to an embodiment of the present invention. Figure 2 The diagram shown is a schematic flowchart of a method for melting ice on a hybrid ground wire of an ultra-high voltage transmission line according to an embodiment of the present invention. Detailed Implementation

[0027] To better understand the above-mentioned objectives, features, and advantages of the present invention, the solutions of the present invention will be further described below. It should be noted that, unless otherwise specified, the embodiments of the present invention and the features thereof can be combined with each other.

[0028] Many specific details are set forth in the following description in order to provide a full understanding of the invention, but the invention may also be practiced in other ways different from those described herein; obviously, the embodiments in the specification are only some embodiments of the invention, and not all embodiments.

[0029] Figure 1 The diagram shown is a structural schematic of a hybrid linear ground wire de-icing system for ultra-high voltage transmission lines according to an embodiment of the present invention. Please refer to it. Figure 1This invention provides a hybrid ground wire de-icing system 100 for ultra-high voltage transmission lines, comprising: a section group, the section group including a first section ground wire 01, a second section ground wire 02, a de-icing device 06, a de-icing access switch 05, a ground wire separation unit 03, a ground wire insulation unit 04, a de-icing current booster switch 07, a parallel reactive current booster unit 08, and a de-icing grounding unit 09; wherein, the first section ground wire 01 and the second section ground wire 02 each include two parallel ground wires 00 with the same or similar specifications, the ground wires 00 in the first section ground wire 01 and the second section ground wire 02 are electrically isolated from the tower 10 by the ground wire insulation unit 04, the side of the first section ground wire 01 away from the second section ground wire 02 is electrically disconnected from other sections by the ground wire separation unit 03, and the second section ground wire 02 is away from the first section ground wire One side of 01 is electrically disconnected from other sections via ground wire separation unit 03; the two ground wires 00 of the second section ground wire 02 are directly short-circuited at the end and grounded via de-icing grounding unit 09; the two ends of the de-icing device 06 are connected to the two ground wires 00 of the first section ground wire 01 via de-icing access switch 05, and the de-icing device 06 is used to provide power for de-icing of the entire ground wire section; the two ground wires 00 of the first section ground wire 01 and the second section ground wire 02 are connected at the junction point, and the corresponding ground wires are connected to the de-icing current booster switch 07 via cables at the junction point and then connected to the two ends of the parallel reactive current booster unit 08. The parallel reactive current booster unit 08 is used for reactive current compensation, so that the current of the first section ground wire 01 and the second section ground wire 02 is different, thereby realizing the decoupling control of the de-icing current of the two sections.

[0030] Specifically, in the ground wire section after insulation modification, in a mixed-type ground wire structure containing two or more specifications of ground wires 00, all ground wires 00 in this section are supported by insulators and are no longer directly grounded. The de-icing device 06 is installed at one end of the ground wire 00 corresponding to the smaller de-icing current, providing the AC power required for de-icing the entire ground wire section. The reactive power compensation device, including reactive power regulation equipment such as capacitor banks, is T-connected at the junction of the mixed-type ground wires 00 to generate an additional reactive current, thus allowing a difference in current between the first section ground wire 01 and the second section ground wire 02. The de-icing grounding unit 09 is installed at the end of the ground wire section corresponding to the larger de-icing current, short-circuiting and grounding the two ground wires 00 to form a de-icing current loop.

[0031] Thus, the UHV transmission line mixed-type ground wire de-icing system 100 provided by the present invention can simultaneously de-ic two types of mixed-type ground wires 00 without changing the existing ground wires and towers, and the de-icing currents of different sections can be decoupled from each other, avoiding the problem that the de-icing currents of different specifications of ground wires 00 are different and cannot be induced to de-ic at the same time, or that the existing ground wires 00 of different specifications must be modified to a uniform specification in order to de-ic. This improves the applicability and efficiency of ground wire 00 de-icing.

[0032] The first section ground wire 01 includes a first ground wire and a second ground wire, and the second section ground wire 02 includes a third ground wire and a fourth ground wire. The first ground wire and the third ground wire are connected at the first dividing point, and the second ground wire and the fourth ground wire are connected at the second dividing point. The first dividing point between the first ground wire and the third ground wire is connected to one end of the parallel reactive power boosting unit 08 via a first ice-melting current boosting switch, and the second dividing point between the second ground wire and the fourth ground wire is connected to the other end of the parallel reactive power boosting unit 08 via a second ice-melting current boosting switch.

[0033] The UHV transmission line hybrid line type ground wire de-icing system 100 includes multiple section groups and multiple ground wire separation units 03. In two adjacent section groups, the end of the ground wire 01 of the first section of one section group that is far away from the ground wire 02 of the second section is electrically disconnected from the end of the ground wire 02 of the second section of another section group that is far away from the ground wire 01 of the first section through the ground wire separation unit 03.

[0034] The first ground wire of the first segment ground wire 01 in a segment group is connected to the third ground wire of the second segment ground wire 02 in another segment group through the ground wire separation unit 03, and the second ground wire of the first segment ground wire 01 in a segment group is connected to the fourth ground wire of the second segment ground wire in another segment group through the ground wire separation unit.

[0035] Please refer to Figure 1 The present invention provides a hybrid linear ground wire de-icing system 100 for ultra-high voltage transmission lines, wherein the de-icing device 06 includes a three-phase to single-phase power frequency transformer or an inverter power supply.

[0036] The ice-melting device 06 can use a power frequency transformer whose output voltage matches the required ice-melting voltage to reduce the cost of the device. Alternatively, a non-power frequency inverter can be used to facilitate matching of line impedance parameters. The ice-melting device 06 is a single-phase AC ice-melting device.

[0037] Please refer to Figure 1The present invention provides a hybrid line type ground wire de-icing system 100 for ultra-high voltage transmission lines, and a parallel reactive power boosting unit 08 including a groupable capacitor bank, so as to more flexibly adjust the input capacitor parameters, adapt to the design error caused by inaccurate line parameters, and adjust the input capacitor parameters when it is found that the current in different sections is difficult to reach the expected value at the same time during the de-icing process, thereby controlling the difference in current before and after.

[0038] Please refer to Figure 1 The present invention provides a hybrid linear ground wire de-icing system 100 for ultra-high voltage transmission lines, wherein the ground wire insulation unit 04 includes an insulator or a surge arrester with a parallel discharge gap.

[0039] As a lightning protection device, the parallel discharge gap, through its unique structural design, can quickly break down and discharge during lightning overvoltage, diverting the lightning current to the ground. This avoids the direct impact of the lightning current on the ground wire and insulators, effectively extending the service life of the insulators and reducing line faults caused by lightning strikes.

[0040] Surge arresters, with their excellent nonlinear volt-ampere characteristics, exhibit a high resistance state under normal operating voltage, allowing only microampere current to pass through; however, under overvoltage conditions, the arrester resistance drops sharply, dissipating overvoltage energy and achieving the purpose of protecting equipment. The use of surge arresters can enhance the lightning protection capability of ground wire insulation unit 04.

[0041] The present invention provides a hybrid ground wire de-icing system 100 for ultra-high voltage transmission lines. The system may also include a monitoring unit (not shown in the figure). The monitoring unit is used to detect the current flowing through the ground wire 01 in the first section and the ground wire 02 in the second section and the temperature of the ground wire 00 in real time. Based on the monitored current and ground wire temperature, the system adjusts the output voltage and current of the de-icing device 06 and the operating parameters of the parallel reactive power boosting unit 08 in real time, so that the current flowing through the ground wire 01 in the first section and the ground wire 02 in the second section is within their respective suitable de-icing current range, thereby avoiding faults caused by overcurrent or overheating of the ground wire 00.

[0042] The monitoring unit is used to monitor the de-icing current and icing status of each section of the ground wire 00 in real time, and adjust the output voltage and current of the de-icing device 06 and the operating parameters of the parallel reactive power boosting unit 08 so that the current flowing through the ground wires 00 of different specifications is exactly within their respective suitable de-icing current range, thereby achieving simultaneous de-icing of different wire types of mixed conductors at the same time.

[0043] Figure 2 The diagram shown is a schematic flow chart of a hybrid ground wire de-icing method for ultra-high voltage transmission lines according to an embodiment of the present invention. Please refer to it. Figure 1 and Figure 2This invention provides a method for de-icing the ground wire of a mixed-type UHV transmission line, used for parameter matching design and de-icing implementation in the UHV transmission line mixed-type ground wire de-icing system 100 as described above, including: Step S1: Calculate the required de-icing current based on the specifications of ground wire 00 for the first section (ground wire 01) and the second section (ground wire 02) of the UHV transmission line, the meteorological parameters along the line, and the expected de-icing time. , ; Specifically, the applicability of this de-icing method is evaluated based on the de-icing current and AC impedance parameters of ground wire 01 in the first section and ground wire 02 in the second section. The parameters are required to meet the following conditions:

[0044] in, This indicates the expected de-icing current value for the first section ground wire 01. This indicates the expected de-icing current value for the second section ground wire 02. , These represent the total resistance and total inductive reactance of the ground wire 02 in the second section, respectively. In the second step S2, for situations where this de-icing method is applicable, the required parameters for the parallel reactive power booster unit 08 are designed based on the line parameters.

[0045] The rated voltage of the parallel reactive power booster unit 08 is... Rated current and impedance parameters The design values ​​are as follows:

[0046] in, This indicates the power factor corresponding to the impedance of the ground wire 02 in the second section. ; This indicates the reactive load factor corresponding to the impedance of the ground wire 02 in the second section. ; In step S3, after determining the parameters of the parallel reactive power booster unit 08, the required de-icing current for the first section ground wire 01 and the second section ground wire 02, the rated parameters of the de-icing device 06 are designed. The rated parameters of the de-icing device 06 include the rated output current, the rated output voltage, and the rated capacity. The rated output current of the de-icing device 06 is designed according to the de-icing current of the first section ground wire 01. Its rated output voltage is designed according to the equivalent impedance of the current-carrying section through which the de-icing current of the first section ground wire 01 flows, taking into account the compensation effect of the parallel reactive power booster unit 08. Its rated capacity is designed according to the aforementioned rated voltage and rated current. In step S4, the rated parameters of the de-icing device 06 and the parameters of the parallel reactive power boosting unit 08 are applied to the de-icing system 100 of the UHV transmission line hybrid linear ground wire, and the de-icing access switch 05 and the de-icing boosting switch 07 are closed to perform de-icing.

[0047] Specifically, the above parameters are applied to the UHV transmission line hybrid ground wire de-icing system 100, and the relevant hardware installation and modification of the system are completed before the line is covered with ice. Under the non-de-icing state of the ground wire of the UHV transmission line in normal operation, the de-icing access switch 05 and the de-icing current booster switch 07 are disconnected, and the UHV line operates normally.

[0048] When the ice accumulation on the ground wire 00 reaches the ice melting start thickness, the UHV transmission line mixed-type ground wire ice melting system 100 is started to prepare for the mixed-type ground wire; before ice melting, while keeping the ice melting device 06 de-energized, the ice melting connection switch 05 is closed, the ice melting current booster switch 07 is closed, and the parallel reactive current booster unit 08 is adjusted to the expected parameters and status. Powering the ice-melting device 06 and adjusting its output voltage will make the current of the first section ground wire 01 and the current of the second section ground wire 02 reach their expected design values. When the line parameters deviate from the design values ​​and adjusting the voltage of the ice-melting device 06 alone cannot make the two currents reach their expected design values ​​at the same time, the parameters of the parallel reactive current booster unit 08 can also be adjusted to make the two currents reach their expected design values ​​at the same time. Maintain the current in the two sections at the expected design value and continue to operate until all the ice on the ground wire 00 of the two sections falls off; Turn off the power supply to the de-icing device 06, stop the current flow through the ground wire 00, and disconnect the de-icing connection switch 05 and the de-icing current booster switch 07 to restore the normal operation of the UHV line.

[0049] This method is applicable to working conditions with mixed ground wire configurations and does not require changing the ground wire specifications. This method allows for simultaneous current flow to melt ice on both front and rear ground wires of different cross-sections in a single operation; furthermore, the melting current of the two types of ground wires can be adjusted by regulating the capacitor bank parameters.

[0050] Specific Cases In an optional embodiment of the present invention, the second section ground wire 02 of a section of a certain ultra-high voltage transmission line with particularly severe icing on the mountaintop (30mm ice zone) is model JLB20B-240 and has a length of 1.364km; while the first section ground wire 01 of the adjacent section at the foot of the mountain with the conditions for connecting the ice melting device is model JLBGJ-150-20AC and has a length of 1.679km.

[0051] The following examples illustrate the de-icing method for the ground wire of ultra-high voltage transmission lines proposed according to the present invention.

[0052] Based on the ground wire specifications and local meteorological parameters, and referring to the de-icing current calculation method in "GB / T 31487.1-2015 DC De-icing Device Part 1: System Design and Application Guidelines", the de-icing currents of the first section ground wire 01 (specification JLB20B-240) and the second section ground wire 02 (specification LBGJ-150-20AC) are calculated to be 350A and 450A, respectively.

[0053] The applicability of this method is evaluated based on the line de-icing current and parameters. The de-icing current of ground wire 01 in the first section (350A) is less than that of ground wire 02 in the second section (450A), indicating that there is a current-carrying bottleneck when the original mixed ground wires are directly connected together, making it impossible to de-ic the ground wire 02 in the second section. The de-icing current of ground wire 01 in the first section (350A) is greater than the active component of the de-icing current of ground wire 02 in the second section (319A), indicating that the hybrid ground wire de-icing system and method for transmission lines proposed in this invention are applicable.

[0054]

[0055] Design parameters for a parallel current-boosting capacitor, including its rated voltage. Rated current and impedance parameters The design values ​​are as follows:

[0056]

[0057]

[0058]

[0059] The rated current required from the parallel capacitor bank can be calculated using the above formula. 174A, rated voltage 769V, impedance parameters It is 4.4Ω, rated capacity It is 143kvar.

[0060] The above description is merely a specific embodiment of the present invention, enabling those skilled in the art to understand or implement the invention. Various modifications to these embodiments will be readily 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 invention. Therefore, the present invention is not to be limited to the embodiments described herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A hybrid linear ground wire de-icing system for ultra-high voltage transmission lines, characterized in that, include: The section group includes a first section ground wire, a second section ground wire, an ice melting device, an ice melting access switch, an ice melting current booster switch, and a parallel reactive current booster unit; The first section ground wire and the second section ground wire each include two ground wires of the same or similar specifications. The two ground wires in the first section ground wire are respectively connected to the two ground wires in the second section ground wire at the corresponding boundary point. The corresponding ground wires are respectively connected to the two ends of the parallel reactive current boosting unit at the boundary point via the ice melting current boosting switch. The parallel reactive current boosting unit is used for reactive current compensation, so that the currents of the first section ground wire and the second section ground wire are different, so as to achieve decoupling control of the ice melting current of the first section ground wire and the second section ground wire. In the second section of the ground wire, the end of the two ground wires that is furthest from the first section of the ground wire is short-circuited and grounded; The two ends of the ice-melting device are respectively connected to the two ground wires of the first section ground wire via the ice-melting access switch. The ice-melting device is used to provide power for the first section ground wire and the second section ground wire during ice melting.

2. The UHV transmission line hybrid linear ground wire de-icing system as described in claim 1, characterized in that, The first section ground wire includes a first ground wire and a second ground wire, and the second section ground wire includes a third ground wire and a fourth ground wire, wherein the first ground wire and the third ground wire are connected at a first dividing point, and the second ground wire and the fourth ground wire are connected at a second dividing point. The first dividing point between the first ground wire and the third ground wire is connected to one end of the parallel reactive power boosting unit via a first ice-melting boosting switch, and the second dividing point between the second ground wire and the fourth ground wire is connected to the other end of the parallel reactive power boosting unit via a second ice-melting boosting switch.

3. The UHV transmission line hybrid linear ground wire de-icing system as described in claim 2, characterized in that, It includes multiple segment groups and multiple ground wire separation units. In two adjacent segment groups, the end of the ground wire of the first segment of one segment group that is far from the ground wire of the second segment is electrically disconnected from the end of the ground wire of the second segment of another segment group that is far from the ground wire of the first segment through the ground wire separation unit.

4. The UHV transmission line hybrid linear ground wire de-icing system as described in claim 3, characterized in that, The first ground wire of the first segment ground wire in a segment group is connected to the third ground wire of the second segment ground wire in another segment group through the ground wire separation unit, and the second ground wire of the first segment ground wire in a segment group is connected to the fourth ground wire of the second segment ground wire in another segment group through the ground wire separation unit.

5. The UHV transmission line hybrid linear ground wire de-icing system as described in claim 1, characterized in that, The ice-melting device is a three-phase to single-phase power frequency transformer or an inverter power supply.

6. The UHV transmission line hybrid linear ground wire de-icing system as described in claim 1, characterized in that, The parallel reactive power booster unit includes a capacitor bank that can be switched in groups.

7. The UHV transmission line hybrid linear ground wire de-icing system as described in claim 1, characterized in that, The grounding insulation unit includes an insulator or surge arrester with a parallel discharge gap.

8. The UHV transmission line hybrid linear ground wire de-icing system as described in claim 1, characterized in that, The system may further include a monitoring unit, which is used to detect the current flowing through the first section ground wire and the second section ground wire and the ground wire temperature in real time. Based on the monitored current and ground wire temperature, the monitoring unit adjusts the output voltage and current of the de-icing device and the operating parameters of the parallel reactive power booster unit in real time, so that the current flowing through the first section ground wire and the second section ground wire is within their respective suitable de-icing current ranges.

9. A method for de-icing the ground wire of a hybrid type ultra-high voltage transmission line, characterized in that, Applied to the de-icing system for mixed-type ground wires of UHV transmission lines as described in any one of claims 1-8, the de-icing method for mixed-type ground wires of UHV transmission lines includes: The required de-icing current is calculated based on the specifications of the ground wires in the first and second sections of the ultra-high voltage transmission line, meteorological parameters along the line, and the expected de-icing time. , ; For applications where this de-icing method is applicable, the parameters of the required parallel reactive power booster unit should be determined based on the line parameters. After determining the parameters of the parallel reactive power booster unit, the required de-icing current for the first section ground wire and the second section ground wire, the rated parameters of the de-icing device are designed. The rated parameters of the de-icing device and the parameters of the parallel reactive power booster unit are applied to the de-icing system of the hybrid linear ground wire of the UHV transmission line, and the de-icing access switch and the de-icing booster switch are closed to carry out de-icing.

10. The method for de-icing the ground wire of a mixed-type ultra-high voltage transmission line as described in claim 9, characterized in that, The applicability of this de-icing method is evaluated based on the de-icing current and AC impedance parameters of the first and second section ground wires. Specifically, the parameters must meet the following conditions: in, This indicates the expected de-icing current value of the ground wire in the first section. This indicates the expected de-icing current value of the ground wire in the second section. , These represent the total resistance and total inductive reactance of the ground wire in the second section, respectively.

11. The method for de-icing the mixed-type ground wire of ultra-high voltage transmission lines as described in claim 9, characterized in that, The parameters of the parallel reactive power booster unit include the rated voltage of the parallel reactive power booster unit. Rated current and impedance parameters The calculation formula for the parameters of the parallel reactive power booster unit is as follows: in, This indicates the active load factor corresponding to the ground wire impedance of the second section. ; This indicates the reactive load factor corresponding to the ground wire impedance of the second section. .

12. The method for de-icing the ground wire of a mixed-type ultra-high voltage transmission line as described in claim 9, characterized in that, The rated parameters of the ice-melting device include rated output current, rated output voltage, and rated capacity. The rated output current of the ice-melting device is designed according to the ice-melting current required by the ground wire in the first section. The rated output voltage of the ice-melting device is designed according to the equivalent impedance of the current-carrying section through which the ice-melting current required by the ground wire in the first section flows, taking into account the compensation effect of the parallel reactive power boosting unit. The rated capacity of the ice-melting device is designed based on the rated voltage and rated current of the ice-melting device.

13. The method for de-icing the ground wire of a mixed-type ultra-high voltage transmission line as described in claim 9, characterized in that, Under the non-ice melting condition of the ground wire of the UHV transmission line during normal operation, the ice melting connection switch and the ice melting current booster switch are disconnected, and the UHV line operates normally. When the ice accumulation on the ground wire reaches the thickness required to initiate ice melting, the UHV transmission line hybrid ground wire ice melting system is activated to prepare for the hybrid ground wire. Before ice melting, while keeping the ice melting device de-energized, the ice melting connection switch and the ice melting current booster switch are closed, and the parallel reactive current booster unit is adjusted to the expected parameters and status. Power is supplied to the ice-melting device and its output voltage is adjusted so that the current in the first section ground wire and the current in the second section ground wire reach their expected design values. When the line parameters deviate from the design value, making it impossible to make the two currents reach the expected design value simultaneously by simply adjusting the voltage of the ice melting device, the parameters of the parallel reactive power booster unit can also be adjusted to make the two currents reach the expected design value simultaneously. Maintain the current in the two sections at the expected design value and continue to operate until all the ice on the ground wires of the two sections falls off; Turn off the power to the de-icing device, disconnect the de-icing connection switch and the de-icing current booster switch, and restore the UHV line to normal operation.

Images