Direct-current ice melting device

Abstract

The invention discloses a direct-current deicing device which comprises an alternating-current transformer, a power grid commutation converter, a smoothing reactor and a line to be deiced. The alternating-current transformer is connected with the power grid commutation converter; after being connected in series with the smoothing reactor, the power grid commutation converter is connected with a line to be de-iced through a first isolating switch on the side of the de-icing device; one end of the ice-melting device side ice-melting tubular bus of the first isolation switch is provided with an ice-melting lightning arrester, and the other end is provided with a discharge gap used for protecting the ice-melting tubular bus in a stepped manner. An ice melting lightning arrester and a discharge gap are installed on the ice melting device side at the same time, stepped reliable protection is carried out on equipment on the ice melting device side in two modes, and two protection mechanisms are arranged at the same time to carry out cooperative protection, so that the resonance overvoltage and lightning stroke overvoltage conditions can be effectively coped with. The technical problem that resonance overvoltage and lightning stroke overvoltage are difficult to effectively protect in the prior art can be solved.

Description

Technical Field

[0001] The present application relates to the technical field of power systems, and in particular to a direct current ice melting device. Background Art

[0002] Among the various natural disasters that the power system suffers, ice disasters are one of the most serious threats. Compared with other accidents, ice disasters often cause more serious losses to the power grid, ranging from ice flash to tower collapse and line disconnection, or even power grid paralysis.

[0003] At present, a high-power DC ice melting device with completely independent intellectual property rights has been successfully developed, mainly including a DC ice melting device with a dedicated rectifier transformer and a DC ice melting device without a dedicated rectifier transformer. However, these DC ice melting devices still have some problems, such as excessive resonance energy, which may cause the arrester to overheat and fail; lightning overvoltage may cause damage to high-voltage transmission lines; in addition, it may not be able to effectively protect the pipe mother and other equipment on the ice melting device. Summary of the invention

[0004] The present application provides a direct current ice melting device, which is used to solve the technical problem that it is difficult to effectively protect against resonant overvoltage and lightning overvoltage in the prior art.

[0005] In view of this, the present application provides a DC ice melting device, including: an AC transformer, a grid phase-commutation converter, a smoothing reactor, and a line to be ice-melted;

[0006] The AC transformer is connected to the grid phase-commutation converter;

[0007] After the grid phase-commutation converter is connected in series with the smoothing reactor, it is connected to the line to be de-iced through the first isolating switch on the de-icing device side;

[0008] An ice-melting arrester is arranged at one end of the ice-melting pipe mother on the ice-melting device side of the first isolating switch, and a discharge gap is arranged at the other end for step-by-step protection of the ice-melting pipe mother.

[0009] Preferably, after the grid phase-commutation converter is connected in series with the smoothing reactor, the grid phase-commutation converter is connected with the line to be de-iced through a first isolating switch on the de-icing device side, including:

[0010] The grid phase-commutation converter is connected in series with the smoothing reactor;

[0011] The smoothing reactor is connected in parallel with a plurality of first isolating switches on the ice melting device side;

[0012] The first isolating switch is connected to the line to be de-iced via an ice-melting busbar and a second isolating switch.

[0013] Preferably, it also includes: a DC pole line arrester;

[0014] The DC pole line arrester is connected between the grid phase-commutating converter and the ground line, and is used to protect the grid phase-commutating converter.

[0015] Preferably, it also includes: an AC lightning arrester;

[0016] One end of the AC lightning arrester is connected to the AC bus and the converter transformer at the same time, and the other end is grounded, so as to protect the AC line.

[0017] Preferably, the ice-melting arrester and the discharge gap match the number of AC lines, and three are provided.

[0018] Preferably, the continuous operating voltage of the ice melting arrester is defined as:

[0019]

[0020] in, is the commutation overshoot coefficient, is the induced voltage coefficient per unit length of the double circuit on the same tower, is the peak value of the phase voltage on the valve side of the converter valve transformer, is the peak value of the phase voltage of the AC line, It is the length of double-circuit line on the same tower.

[0021] Preferably, the rated voltage of the ice melting arrester is defined as:

[0022] .

[0023] Preferably, the rated voltage of the discharge gap is defined as:

[0024]

[0025] in, , They are the lightning protection level value and the operation protection level value of the arrester respectively.

[0026] Preferably, the length of the discharge gap is calculated as follows:

[0027]

[0028] in, is the highest submarine cable withstand voltage level, is the gap coefficient, is the standard deviation.

[0029] It can be seen from the above technical solutions that the embodiments of the present application have the following advantages:

[0030] In the present application, a DC ice-melting device is provided, including: an AC transformer, a grid phase-commutating converter, a smoothing reactor and a line to be ice-melted; the AC transformer is connected to the grid phase-commutating converter; after the grid phase-commutating converter and the smoothing reactor are connected in series, they are connected to the line to be ice-melted through a first isolating switch on the ice-melting device side; an ice-melting arrester is provided at one end of the ice-melting pipe mother on the ice-melting device side of the first isolating switch, and a discharge gap is provided at the other end for step-by-step protection of the ice-melting pipe mother.

[0031] The present application provides a DC ice melting device, in which an ice melting arrester and a discharge gap are installed on the ice melting device side at the same time, and the equipment on the ice melting device side is reliably protected in a stepped manner in two ways, and the two protection mechanisms are deployed at the same time for coordinated protection, which can effectively deal with the situation of resonant overvoltage and lightning overvoltage, and can meet the existing protection needs. Therefore, the present application can solve the technical problem that the existing technology is difficult to achieve effective protection against resonant overvoltage and lightning overvoltage. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 A schematic structural diagram of a DC ice melting device provided in an embodiment of the present application. DETAILED DESCRIPTION

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

[0034] For easier understanding, see Figure 1 , an embodiment of a DC ice melting device provided by the present application includes: an AC transformer, a grid phase-commutating converter, a smoothing reactor and a line to be ice-melted;

[0035] The AC transformer is connected to the grid phase-commutation converter;

[0036] After the grid phase-commutation converter is connected in series with the smoothing reactor, it is connected to the line to be de-iced through the first isolating switch on the de-icing device side;

[0037] An ice-melting arrester is arranged at one end of the ice-melting pipe mother on the ice-melting device side of the first isolating switch, and a discharge gap is arranged at the other end for step-by-step protection of the ice-melting pipe mother.

[0038] Furthermore, after the grid phase-commutation converter is connected in series with the smoothing reactor, it is connected to the line to be de-iced through the first isolating switch on the de-icing device side, including:

[0039] The grid phase-commutating converter is connected in series with the smoothing reactor;

[0040] The smoothing reactor is connected in parallel with a plurality of first isolating switches on the ice melting device side;

[0041] The first isolating switch is connected to the line to be de-iced through the de-icing busbar and the second isolating switch.

[0042] Furthermore, it also includes: a DC pole line arrester;

[0043] The DC pole line arrester is connected between the grid phase-commutating converter and the ground wire to protect the grid phase-commutating converter.

[0044] Further, it also includes: an AC lightning arrester;

[0045] One end of the AC lightning arrester is connected to the AC bus and the converter transformer at the same time, and the other end is grounded, which is used to protect the AC line.

[0046] Furthermore, the ice-melting arresters and discharge gaps are matched with the number of AC lines, and three are provided for each.

[0047] It should be noted that in this embodiment, the lightning arrester protecting the ice melting line is installed on the first isolating switch, that is, Figure 1 The line side of the switch 2 in the circuit is the ice melting arrester DL, and according to the AC line requirements, an ice melting arrester DL is installed on each line. Installing the ice melting arrester on the ice melting device side instead of the smoothing reactor 5 side can provide more effective protection for the busbar on the ice melting device side, especially the protection of the transformer substation from lightning strikes.

[0048] In addition, in this embodiment, a discharge gap DG is provided on the other side of the de-icing busbar on the de-icing device side, and the de-icing arrester and the discharge gap are respectively installed on both sides of the de-icing busbar 3. The discharge gap DG can effectively protect against resonant overvoltage and lightning overvoltage; and by placing the arrester and the discharge gap at both ends of the busbar, the two protective devices can be isolated by the length of the de-icing busbar, so that the arrester and the discharge gap form a step-type protection, avoiding the simultaneous triggering of the protection action after the two are connected in parallel at one point. Figure 1 The smoothing reactor is 5, the second disconnector is 4, and the converter transformer is 6.

[0049] It can be found that in addition to setting up a reasonable and reliable protection mechanism for the de-icing device side, the DC de-icing device of this embodiment also needs to set up lightning arresters for the AC bus 7 and the grid phase-changing converter 1 on the AC side, such as the AC lightning arrester A on the AC bus, to avoid equipment damage caused by overvoltage, thereby affecting the stable operation of the system. In addition, one end of all lightning arresters and discharge gaps is connected to the circuit, and the other end needs to be connected to the ground to form an effective protection circuit.

[0050] Since the lightning arrester and discharge gap are set at both ends of the ice-melting busbar in this embodiment, the two must be coordinated in parameters when the system generates overvoltage; if the discharge voltage of the discharge gap is configured too high, the energy of the ice-melting lightning arrester will exceed the design value, which may cause the lightning arrester to be damaged; if the discharge voltage of the discharge gap is configured too low, it may cause the ice-melting busbar to short-circuit due to the breakdown of the discharge gap during routine operations such as closing the system, affecting the safe operation of the system. Therefore, this embodiment also provides a method for determining the parameters of these key devices.

[0051] Furthermore, the continuous operating voltage of the ice melting arrester is defined as:

[0052]

[0053] in, is the commutation overshoot coefficient, is the induced voltage coefficient per unit length of the double circuit on the same tower, is the peak value of the phase voltage on the valve side of the converter valve transformer, is the peak value of the phase voltage of the AC line, It is the length of double-circuit line on the same tower.

[0054] Furthermore, the rated voltage of the ice melting arrester is defined as:

[0055] .

[0056] The selection of the rated voltage of the DL type arrester should fully consider the maximum continuous operating voltage of the arrester installation location. Therefore, in this embodiment, the continuous operating voltage needs to be determined before determining the rated voltage of the arrester. The continuous operating voltage here includes the commutation overshoot that may occur during the operation of the converter. At the same time, the influence of the induced voltage caused by the parallel line needs to be considered. Therefore, the induced voltage coefficient is used in the process of calculating the maximum continuous operating voltage. In addition, the commutation overshoot coefficient The value is usually 1.25~1.3; the induced voltage coefficient per unit length of double circuits on the same tower The value is usually between 0.01 and 0.05.

[0057] In the overvoltage electromagnetic transient calculation model, the lightning protection level value of the arrester can be obtained by considering faults such as DC bus grounding fault, DC positive and negative bus short circuit fault, and DC bus open circuit fault. and Operational Protection Level The overvoltage electromagnetic transient calculation model is an electromagnetic transient model constructed according to system characteristics. Different fault simulation calculation processes can be implemented based on existing technologies, so they will not be described here.

[0058] Further, the rated voltage of the discharge gap is defined as:

[0059]

[0060] in, , They are the lightning protection level value and the operation protection level value of the arrester respectively.

[0061] Furthermore, the length of the discharge gap is calculated as follows:

[0062]

[0063] in, is the highest submarine cable withstand voltage level, is the gap coefficient, is the standard deviation.

[0064] In order to prevent resonant overvoltage of the ice-melting system, lightning intrusion wave overvoltage caused by lightning striking the ice-melting line, and operating overvoltage caused by disconnection of the ice-melting line, a protective gap, i.e., a discharge gap, should be installed on the ice-melting busbar side of the phase-selective disconnector of the ice-melting device in the station.

[0065] The discharge gap needs to determine a suitable rated voltage to maintain system stability and effective protection. Therefore, this embodiment calculates and selects according to the lightning protection level value and the operation protection level value of the arrester. The discharge gap rated voltage obtained in this way is It is more accurate and reliable, and can fully ensure that the discharge gap operates accurately before the arrester energy exceeds the design value.

[0066] In addition, the discharge gap also needs to be set to a suitable length so that the overall discharge requirements can be met. In this embodiment, the gap length is calculated based on the highest submarine cable withstand voltage level, where the gap coefficient The general value is 1.15, standard deviation The value is 0.06.

[0067] The embodiment of the present application provides a DC ice melting device, in which an ice melting arrester and a discharge gap are installed on the ice melting device side at the same time, and the equipment on the ice melting device side is reliably protected in a stepped manner in two ways, and the two protection mechanisms are deployed at the same time for coordinated protection, which can effectively deal with the situation of resonant overvoltage and lightning overvoltage, and can meet the existing protection needs. Therefore, the embodiment of the present application can solve the technical problem that the existing technology is difficult to achieve effective protection against resonant overvoltage and lightning overvoltage.

[0068] In the several embodiments provided in the present application, it should be understood that the disclosed devices and methods can be implemented in other ways. For example, the device embodiments described above are only schematic. For example, the division of the units is only a logical function division. There may be other division methods in actual implementation, such as multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be through some interfaces, indirect coupling or communication connection of devices or units, which can be electrical, mechanical or other forms.

[0069] The units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed on multiple network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0070] In addition, each functional unit in each embodiment of the present application may be integrated into one processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit. The above-mentioned integrated unit may be implemented in the form of hardware or in the form of software functional units.

[0071] If the integrated unit is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present application is essentially or the part that contributes to the prior art or all or part of the technical solution can be embodied in the form of a software product. The computer software product is stored in a storage medium, including a number of instructions for executing all or part of the steps of the method described in each embodiment of the present application through a computer device (which can be a personal computer, server, or network device, etc.). The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (full name in English: Read-Only Memory, English abbreviation: ROM), random access memory (full name in English: Random Access Memory, English abbreviation: RAM), disk or optical disk and other media that can store program codes.

[0072] As described above, the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. 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 application.

Claims

1. A direct current ice melting device, characterized in that: include: AC transformers, grid phase-commutation converters, smoothing reactors and lines to be de-iced; The AC transformer is connected to the grid phase-commutation converter; After the grid phase-commutation converter is connected in series with the smoothing reactor, it is connected to the line to be de-iced through the first isolating switch on the de-icing device side; An ice-melting arrester is arranged at one end of the ice-melting pipe mother on the ice-melting device side of the first isolating switch, and a discharge gap is arranged at the other end for step-by-step protection of the ice-melting pipe mother.

2. The DC ice melting device according to claim 1, characterized in that: After the grid phase-commutation converter is connected in series with the smoothing reactor, the grid phase-commutation converter is connected with the ice-melting line through the first isolating switch on the ice-melting device side, including: The grid phase-commutation converter is connected in series with the smoothing reactor; The smoothing reactor is connected in parallel with a plurality of first isolating switches on the ice melting device side; The first isolating switch is connected to the line to be de-iced via an ice-melting busbar and a second isolating switch.

3. The DC ice melting device according to claim 1, characterized in that: Also includes: DC pole line arrester; The DC pole line arrester is connected between the grid phase-commutating converter and the ground line, and is used to protect the grid phase-commutating converter.

4. The DC ice melting device according to claim 1, characterized in that: Also includes: AC lightning arrester; One end of the AC lightning arrester is connected to the AC bus and the converter transformer at the same time, and the other end is grounded, so as to protect the AC line.

5. The DC ice melting device according to claim 1, characterized in that: The ice-melting arrester and the discharge gap match the number of AC lines, and three of each are provided.

6. The DC ice melting device according to claim 1, characterized in that: The continuous operating voltage of the ice melting arrester is defined as: in, is the commutation overshoot coefficient, is the induced voltage coefficient per unit length of the double circuit on the same tower, is the peak value of the phase voltage on the valve side of the converter valve transformer, is the peak value of the phase voltage of the AC line, It is the length of double-circuit line on the same tower.

7. The DC ice melting device according to claim 6, characterized in that: The rated voltage of the ice melting arrester is defined as: 。 8. The DC ice melting device according to claim 1, characterized in that: The rated voltage of the discharge gap is defined as: in, , They are the lightning protection level value and the operation protection level value of the arrester respectively.

9. The DC ice melting device according to claim 1, characterized in that: The length of the discharge gap is calculated as follows: in, is the highest submarine cable withstand voltage level, is the gap coefficient, is the standard deviation.

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