Ice melting system and method for mixed wire diameter distribution network line

Abstract

The invention provides a mixed-wire-diameter distribution network line ice melting system and method, and relates to the technical field of line ice melting, and the system comprises an ice melting power supply, an ice melting cable, a voltage and current transformation device, an ice melting line, a short circuit device, a reactive power absorption device, and a reactive power compensation device. The ice melting circuit comprises a first sub-section, a second sub-section and a third sub-section, and the wire diameter of the first sub-section and the wire diameter of the third sub-section are larger than the wire diameter of the second sub-section; the reactive absorption device is used for absorbing reactive current flowing from the first sub-section to the second sub-section; and the reactive power compensation device is used for compensating the ice melting current flowing from the second sub-section to the third sub-section. According to the invention, the reactive power absorption device and the reactive power compensation device are arranged between the lines with different line diameters, so that ice-melting current with appropriate magnitude flows through the lines with different line diameters, the situation that the current flowing through a thin line is greater than the maximum ice-melting current is avoided, and the occurrence of line breakage is reduced; and meanwhile, ice melting current with proper magnitude is provided for a line with a relatively large line diameter, so that the ice melting effect of the line is improved.

Description

Technical Field

[0001] The present disclosure relates to the technical field of line deicing, and in particular to a mixed-diameter distribution network line deicing system and method. Background Art

[0002] With the continuous development of the economy, the requirements for the reliability of power supply of distribution lines are getting higher and higher. Some distribution lines are located in mountainous areas, where the humidity is high and ice is prone to occur in low temperature weather. Icing of distribution lines will affect the safe and reliable operation of the lines, and in severe cases, it will also cause pole collapse and line breakage accidents. Line ice melting is an effective means to solve the problem of icing of distribution lines.

[0003] The principle of line ice melting is to make the conductor generate a large amount of Joule heat, thereby melting the ice on the line. When the heat generated by the conductor is greater than the heat dissipation, the conductor temperature will rise. The larger the conductor cross-section, the stronger its heat dissipation capacity, and the greater the current required to melt the ice. Based on the above principle, different sizes of ice melting currents are required for wires of different wire diameters. The industry standard DLT5511-2016 "Technical Specifications for Design of DC Ice Melting Systems" clarifies the ice melting current ranges for various types of conductors under different conditions, ensuring smooth ice melting while ensuring that the conductors will not be damaged due to overheating.

[0004] At present, most distribution network lines are of mixed wire diameters, and there are working conditions with non-uniform wire diameters. For mixed wire diameter conditions, conventional ice-melting devices are used to melt the lines, but it is impossible to select appropriate ice-melting current for ice-melting, and the ice-melting effect and line stability are both poor.

[0005] Therefore, how to solve the above-mentioned technical problems has become one of the technical problems that need to be solved urgently at this stage. Summary of the invention

[0006] In order to solve the above technical problems, the present disclosure provides a mixed-diameter distribution network line de-icing system and method, which are used to provide appropriate de-icing current for lines with different wire diameters.

[0007] In a first aspect, the present disclosure provides a mixed-diameter distribution network line de-icing system, including: a de-icing power supply, a de-icing cable, a voltage and current conversion device, a de-icing line, a short-circuiting device, a reactive power absorbing device, and a reactive power compensating device;

[0008] The ice-melting cable is electrically connected between the ice-melting power supply and the input end of the transformer and current converter, and the ice-melting line is electrically connected between the output end of the transformer and current converter and the short-circuit device; the ice-melting power supply is used to provide the power required by the mixed-line distribution network line ice-melting system, and the transformer and current converter is used to output an adjustable ice-melting voltage and current;

[0009] The ice melting line includes a first sub-segment, a second sub-segment and a third sub-segment, and the wire diameter of the first sub-segment and the wire diameter of the third sub-segment are greater than the wire diameter of the second sub-segment;

[0010] The reactive power absorption device is connected to the connection between the first sub-segment and the second sub-segment through a knife switch, and is used to absorb the reactive current flowing from the first sub-segment to the second sub-segment;

[0011] The reactive power compensation device is connected to the connection between the second sub-segment and the third sub-segment through a knife switch, and is used to compensate for the ice-melting current flowing from the second sub-segment to the third sub-segment.

[0012] Optionally, where:

[0013] The ice-melting circuit is a three-phase circuit, and the reactive absorption device includes an inductance element group corresponding to each phase circuit in the ice-melting circuit. The first ends of the inductance element groups are connected, and the second ends are connected in parallel to the connection between the first sub-segment and the second sub-segment through knife switches.

[0014] Optionally, where:

[0015] The single-phase impedance of the reactive absorption device is X L ;

[0016]

[0017] in,

[0018] I1 represents the ice melting current of the first sub-segment;

[0019] I2 represents the ice melting current of the second sub-segment;

[0020] I3 represents the ice melting current of the third sub-segment;

[0021] Z2 represents the impedance of the second sub-segment;

[0022] Z3 represents the impedance of the third sub-segment.

[0023] Optionally, where:

[0024] The inductor element group includes a plurality of inductors connected in parallel and having the same parameters.

[0025] Optionally, where:

[0026] The ice-melting line is a three-phase line, and the reactive compensation device includes a capacitor element group corresponding to each phase line in the ice-melting line. The first end of the capacitor element group is connected, and the second end is connected in parallel to the connection between the second sub-segment and the third sub-segment through a knife switch.

[0027] Optionally, where:

[0028] The single-phase impedance of the reactive power compensation device is X C ;

[0029]

[0030] in,

[0031] I2 represents the ice melting current of the second sub-segment;

[0032] I3 represents the ice melting current of the third sub-segment;

[0033] Z3 represents the impedance of the third sub-segment.

[0034] Optionally, where:

[0035] The capacitor element group includes a plurality of capacitors connected in parallel and having the same parameters.

[0036] Optionally, where:

[0037] The ice melting circuit is a three-phase circuit;

[0038] The short-circuit device comprises three conducting wires, the first ends of the conducting wires are connected, and the second ends of the conducting wires are respectively connected and fixed to each phase circuit of the three-phase circuit.

[0039] In a second aspect, based on the same inventive concept, the present disclosure provides a mixed-line diameter distribution network line deicing method, which uses the mixed-line diameter distribution network line deicing system described in the first aspect to deiced the line;

[0040] The mixed-diameter distribution network line deicing method comprises:

[0041] Determine whether the ice thickness of the ice-melting line reaches the ice-melting start condition, and apply for ice melting when the ice thickness of the ice-melting line reaches the ice-melting start condition;

[0042] Performing a power outage operation on the ice-melting line;

[0043] Closing the knife switch, connecting the reactive power absorption device and the reactive power compensation device to the ice melting line;

[0044] Start the ice melting power supply;

[0045] The voltage-to-current converter outputs an adjustable ice-melting voltage and current to melt the ice.

[0046] Compared with the prior art, the technical solution provided by the embodiments of the present disclosure has the following advantages:

[0047] The present invention provides a mixed-line distribution network line de-icing system and method, wherein the de-icing system includes: de-icing power supply, de-icing cable, voltage and current conversion device, de-icing line, short-circuit device, reactive absorption device and reactive compensation device; the de-icing line includes a first sub-segment, a second sub-segment and a third sub-segment, the wire diameter of the first sub-segment and the wire diameter of the third sub-segment are larger than the wire diameter of the second sub-segment; the reactive absorption device is connected to the connection of the first sub-segment and the second sub-segment through a knife switch, and is used to absorb the reactive current flowing from the first sub-segment to the second sub-segment; the reactive compensation device is connected to the connection of the second sub-segment and the third sub-segment through a knife switch, and is used to compensate for the de-icing current flowing from the second sub-segment to the third sub-segment. The present invention arranges reactive absorption devices and reactive compensation devices between lines with different wire diameters, so that the lines with different wire diameters flow through de-icing currents of appropriate sizes, which is conducive to avoiding the current flowing through the thinner line being greater than its maximum de-icing current, thereby helping to improve the higher temperature rise caused by line overcurrent and reduce the occurrence of line disconnection. At the same time, providing a suitable ice-melting current for thicker wires is conducive to improving the ice-melting effect of the lines. For mixed-diameter distribution lines, only one ice-melting operation is needed to deal with the ice coverage of the entire mixed-diameter line. Operators do not need to repeat the ice-melting operation many times, which greatly reduces the power outage time of the line and is conducive to ensuring the power supply to electricity users. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present disclosure and, together with the description, serve to explain the principles of the present disclosure.

[0049] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0050] Figure 1 The figure is a schematic diagram of the principle of a mixed-line-diameter distribution network line ice melting system provided by an embodiment of the present disclosure;

[0051] Figure 2 The figure shows a schematic diagram of a single-line principle of ice melting for a distribution network provided by an embodiment of the present disclosure;

[0052] Figure 3 The figure shows a schematic diagram of another mixed-line-diameter distribution network line ice melting system provided by an embodiment of the present disclosure;

[0053] Figure 4 The figure is a schematic flow chart of a mixed-diameter distribution network line de-icing method provided by an embodiment of the present disclosure. DETAILED DESCRIPTION

[0054] In order to more clearly understand the above-mentioned objectives, features and advantages of the present disclosure, the scheme of the present disclosure will be further described below. It should be noted that the embodiments of the present disclosure and the features in the embodiments can be combined with each other without conflict.

[0055] In the following description, many specific details are set forth to facilitate a full understanding of the present disclosure, but the present disclosure may also be implemented in other ways different from those described herein; it is obvious that the embodiments in the specification are only part of the embodiments of the present disclosure, rather than all of the embodiments.

[0056] The inventors found in their research that most of the current distribution network lines are composite wire diameters, and there are operating conditions where the wire diameters of the wires at the ends of the line are relatively thick, and the wire diameters in the middle are relatively thin. In view of this operating condition, the conventional ice-melting device in the prior art is used to melt the lines, but it is impossible to select a suitable ice-melting current and melt the lines with thick ends and thin middle at the same time. If an ice-melting current that matches the thicker wire diameter is selected for ice-melting, an overcurrent will occur in the thinner line in the middle section, resulting in a high temperature rise, and the line temperature will exceed the extreme value it can withstand, thereby causing damage to the line and even causing the line to break; if an ice-melting current that matches the thinner wire is selected, the ice covering the thicker part will be difficult to melt.

[0057] Therefore, how to solve the above technical problems has become one of the technical problems that need to be solved urgently at this stage.

[0058] In view of this, the present disclosure provides a mixed-diameter distribution network line de-icing system and method, so as to provide appropriate de-icing current for lines with different wire diameters.

[0059] Figure 1 FIG. 1 is a schematic diagram showing the principle of a mixed-line distribution network line de-icing system provided by an embodiment of the present disclosure. Figure 2 The figure shows a schematic diagram of a single-line principle of ice melting in a distribution network provided by an embodiment of the present disclosure. Please refer to Figure 1 and Figure 2 The present disclosure provides a mixed-line distribution network line de-icing system 100, comprising: a de-icing power supply 1, a de-icing cable 2, a voltage and current conversion device 3, a de-icing line 00, a short-circuit device 7, a reactive absorption device 8 and a reactive compensation device 9;

[0060] The ice-melting cable 2 is electrically connected between the ice-melting power supply 1 and the input end of the transformer and current converter 3, and the ice-melting line 00 is electrically connected between the output end of the transformer and current converter 3 and the short-circuit device 7; the ice-melting power supply 1 is used to provide the power required by the mixed-line distribution network line ice-melting system 100, and the transformer and current converter 3 is used to output an adjustable ice-melting voltage and current;

[0061] The ice melting line 00 includes a first sub-segment 4, a second sub-segment 5 and a third sub-segment 6, and the wire diameter of the first sub-segment 4 and the wire diameter of the third sub-segment 6 are greater than the wire diameter of the second sub-segment 5;

[0062] The reactive power absorption device 8 is connected to the connection between the first sub-segment 4 and the second sub-segment 5 through the switches 41-43, and is used to absorb the reactive current flowing from the first sub-segment 4 to the second sub-segment 5;

[0063] The reactive power compensation device 9 is connected to the connection between the second sub-segment 5 and the third sub-segment 6 through the switches 61 - 63 , and is used to compensate for the ice-melting current flowing from the second sub-segment 5 to the third sub-segment 6 .

[0064] Specifically, the present disclosure provides a mixed wire diameter distribution network line deicing system 100, which is used to deicer mixed wire diameter distribution network lines. It should be noted that mixed wire diameters refer to wires in the line that need to be deiced and are located in the same branch and electrically connected have different wire diameters. Figure 1 The description is made by taking three branches with mixed line diameters as an example, but this is not a limitation.

[0065] The mixed-line distribution network line de-icing system 100 includes a de-icing power supply 1, a de-icing cable 2, a transformer and current converter 3, a de-icing line 00, a short-circuit device 7, a reactive absorption device 8, and a reactive compensation device 9. Among them, the de-icing power supply 1 is used to provide the power required by the mixed-line distribution network line de-icing system 100, the transformer and current converter 3 is used to output an adjustable de-icing voltage and current, and the de-icing power supply 1 and the transformer and current converter 3 are connected through the de-icing cable 2. The de-icing line 00 is a line that needs to be de-iced, and the de-icing line 00 is a mixed-line distribution network line. The de-icing line 00 is connected between the transformer and current converter 3 and the short-circuit device 7, and the short-circuit device 7 is used to realize line short-circuiting to form an de-icing circuit.

[0066] The ice melting line 00 includes a first sub-segment 4, a second sub-segment 5 and a third sub-segment 6, wherein the wire diameter of the first sub-segment 4 is larger than the wire diameter of the second sub-segment 5, and the wire diameter of the third sub-segment 6 is larger than the wire diameter of the second sub-segment 5. The embodiment of the present application takes the first sub-segment 4 and the second sub-segment 5 connected, the second sub-segment 5 and the third sub-segment 6 connected, the first sub-segment 4 connected to the output end of the voltage and current conversion device 3, and the third sub-segment 6 connected to the short-circuit device 7 to form an ice melting line 00 with a thicker end and a thinner middle as an example for explanation, but is not limited thereto.

[0067] The reactive absorption device 8 is connected between the first sub-segment 4 and the second sub-segment 5. Since the wire diameter of the first sub-segment 4 is larger than that of the second sub-segment 5, the ice-melting current required by the first sub-segment 4 is larger than that required by the second sub-segment 5. If the ice-melting current corresponding to the first sub-segment 4 is used to melt the second sub-segment 5, an overcurrent may occur in the second sub-segment 5, resulting in a high temperature rise. The temperature of the second sub-segment 5 may exceed the extreme value it can withstand, thereby causing damage to the line and even causing the line to be disconnected. Therefore, the present disclosure sets a reactive absorption device 8 between the first sub-segment 4 and the second sub-segment 5 to realize the shunting of the ice-melting current of the first sub-segment 4, thereby reducing the ice-melting current flowing through the second sub-segment 5, which is conducive to improving the high temperature rise caused by the line overcurrent and reducing the occurrence of line disconnection.

[0068] The reactive power compensation device 9 is connected between the second sub-segment 5 and the third sub-segment 6. Since the wire diameter of the second sub-segment 5 is smaller than that of the third sub-segment 6, the ice-melting current required by the third sub-segment 6 is greater than that required by the second sub-segment 5. If the ice-melting current corresponding to the second sub-segment 5 is used to melt the ice of the third sub-segment 6, the ice on the line may be difficult to melt, and the ice-melting effect is poor. Therefore, the present disclosure sets a reactive power compensation device 9 between the second sub-segment 5 and the third sub-segment 6. The reactive power compensation device 9 transmits the compensation current to the third sub-segment 6, and the second sub-segment 5 transmits the ice-melting current corresponding to the second sub-segment 5 to the third sub-segment 6. The ice-melting current of the second sub-segment 5 and the ice-melting current of the reactive power compensation device 9 are superimposed, so that the ice-melting current flowing through the third sub-segment 6 is greater than the ice-melting current flowing through the second sub-segment 5, which is conducive to improving the ice-melting effect of the third sub-segment 6.

[0069] The reactive absorption device 8 and the reactive compensation device 9 are both connected to the line through knife switches. When ice melting is required, the knife switches 41 to 43 and 61 to 63 are closed, and the reactive absorption device 8 and the reactive compensation device 9 are connected to the circuit. After the ice melting is completed, the knife switches 41 to 43 and 61 to 63 are opened, and the reactive absorption device 8 and the reactive compensation device 9 are disconnected from the line.

[0070] It should be noted that the present disclosure does not limit the specific positions and quantities of the first sub-segment 4, the second sub-segment 5 and the third sub-segment 6. The reactive absorption device 8 is connected to the connection between the first sub-segment 4 and the second sub-segment 5, and the ice melting current flows from the first sub-segment 4 to the second sub-segment 5. The reactive compensation device 9 is connected to the connection between the second sub-segment 5 and the third sub-segment 6, and the ice melting current flows from the second sub-segment 5 to the third sub-segment 6.

[0071] The mixed-diameter distribution network line de-icing system 100 provided by the present disclosure sets reactive absorption devices 8 and reactive compensation devices 9 between lines with different diameters, so that lines with different diameters flow through de-icing currents of appropriate sizes, which is beneficial to avoid the current flowing through the thinner lines being greater than its maximum de-icing current, thereby helping to improve the high temperature rise caused by line overcurrent and reduce the occurrence of line disconnection. At the same time, providing a suitable de-icing current for lines with thicker diameters is beneficial to improving the de-icing effect of the lines. For mixed-diameter distribution network lines, only one de-icing operation is required to handle the icing situation of the entire mixed-diameter line, and the operating personnel do not need to repeat the de-icing operation many times, which greatly reduces the power outage time of the line and is beneficial to ensuring the power supply to electricity users.

[0072] Please continue to refer to Figure 1 The present disclosure provides an optional implementation scheme in which the ice-melting line 00 is a three-phase line, and the reactive absorption device 8 includes an inductance element group 81-83 corresponding to each phase line in the ice-melting line 00, and the first ends of the inductance element groups 81-83 are connected, and the second ends are connected in parallel to the connection between the first sub-segment 4 and the second sub-segment 5 through the knife switches 41-43 respectively.

[0073] Specifically, the present embodiment provides a specific embodiment of a reactive absorption device 8, wherein the reactive absorption device 8 includes an inductance element group 81 to 83. If the ice-melting line 00 is a three-phase circuit, the reactive absorption device 8 includes three inductance element groups, and the inductance element groups 81 to 83 correspond one to one to each phase line in the ice-melting line 00. The first ends of the inductance element groups 81 to 83 are connected, and the second ends are connected in parallel to the connection between the first sub-segment 4 and the second sub-segment 5 through the knife switches 41 to 43, that is, the inductance element groups 81 to 83 are connected to the line in a Y-type connection. Optionally, the inductance element groups 81 to 83 include a plurality of inductances connected in parallel and having the same parameters. In actual applications, the corresponding inductance element groups can be designed according to the required impedance size, so as to realize the diversion of the ice-melting current flowing from the first sub-segment 4 to the second sub-segment 5.

[0074] Please continue to refer to Figure 1 The present disclosure provides an optional implementation mode in which the single-phase impedance of the reactive absorption device 8 is X L ;

[0075]

[0076] Among them, I1 represents the ice-melting current of the first sub-segment 4; I2 represents the ice-melting current of the second sub-segment 5; I3 represents the ice-melting current of the third sub-segment 6; Z2 represents the impedance of the second sub-segment 5; and Z3 represents the impedance of the third sub-segment 6.

[0077] Specifically, the present disclosure provides a single-phase impedance X of a reactive absorption device 8 LThe calculation method is based on Kirchhoff's voltage law and combined with Figure 1 , the sum of the voltages across the reactive absorption device 8, the second sub-segment 5 and the third sub-segment 6 is zero, and formula (2) can be obtained:

[0078] I2Z2+I3Z3-I L X L =0 (2)

[0079] according to Figure 1 We can also obtain formula (3):

[0080] I1=I L +I2 (3)

[0081] Formula (2) and formula (3) can be used together to calculate formula (1). According to formula (1), the single-phase impedance of the reactive absorption device 8 can be calculated, that is, the single-phase impedance of the reactive absorption device 8 can be calculated through the ice-melting current I1 of the first sub-segment 4, the ice-melting current I2 of the second sub-segment 5, the ice-melting current I3 of the third sub-segment 6, the impedance Z2 of the second sub-segment 5 and the impedance Z3 of the third sub-segment 6, which is further beneficial to improve the high temperature rise caused by line overcurrent and reduce the occurrence of line disconnection.

[0082] It should be noted that Kirchhoff's Voltage Law (KVL) is a basic law in circuit analysis. It states that in any closed loop, along the loop direction, the algebraic sum of the potential differences (voltages) across all components is equal to zero. In simple terms, in a closed circuit, the sum of the power supply electromotive force is equal to the sum of the voltage drops of each part of the circuit.

[0083] Please continue to refer to Figure 1 The present disclosure provides an optional implementation scheme in which the ice-melting line 00 is a three-phase line, and the reactive power compensation device 9 includes a capacitor element group 91-93 corresponding to each phase line in the ice-melting line 00, and the first ends of the capacitor element groups 91-93 are connected, and the second ends are connected in parallel to the connection between the second sub-segment 5 and the third sub-segment 6 through the knife switches 61-63 respectively.

[0084] Specifically, this embodiment provides a specific embodiment of a reactive compensation device 9, wherein the reactive compensation device 9 includes capacitor element groups 91 to 93. If the ice-melting line 00 is a three-phase circuit, the reactive compensation device 9 includes three groups of capacitor element groups, and the capacitor element groups 91 to 93 correspond one to one to each phase line in the ice-melting line 00. The first ends of the capacitor element groups 91 to 93 are connected, and the second ends are connected in parallel to the connection between the second sub-segment 5 and the third sub-segment 6 through the knife switches 61 to 63, that is, the capacitor element groups 91 to 93 are connected to the line in a Y-type connection. Optionally, the capacitor element groups 91 to 93 include a plurality of capacitors in parallel with the same parameters. In practical applications, the corresponding capacitor element groups can be designed according to the required impedance size, so as to facilitate the accurate compensation of the ice-melting current flowing from the second sub-segment 5 to the third sub-segment 6.

[0085] Please continue to refer to Figure 1 The present disclosure provides an optional implementation mode in which the single-phase impedance of the reactive power compensation device 9 is X C ;

[0086]

[0087] Wherein, I2 represents the ice-melting current of the second sub-segment 5 ; I3 represents the ice-melting current of the third sub-segment 6 ; and Z3 represents the impedance of the third sub-segment 6 .

[0088] For more information, see Figure 1 Combined with Figure 2 It can be seen that the third subsection 6 is equivalent to being connected in parallel with the reactive power compensation device 9, so:

[0089]

[0090] The third sub-section 6 is connected in parallel with the reactive power compensation device 9 and then connected in series with the second sub-section 5. According to Ohm's law, it can be obtained that:

[0091] I2=I c +I3 (6)

[0092] Formula (5) and formula (6) can be used together to calculate formula (4). According to formula (4), the single-phase impedance of the reactive power compensation device 9 can be calculated. That is, the single-phase impedance of the reactive power compensation device 9 can be calculated through the ice-melting current I2 of the second sub-segment 5, the ice-melting current I3 of the third sub-segment 6 and the impedance Z3 of the third sub-segment 6, which is further conducive to accurately compensating the ice-melting current of the third sub-segment 6, thereby further improving the ice-melting effect.

[0093] Figure 3 FIG. 1 is a schematic diagram showing another mixed-line distribution network line de-icing system provided by an embodiment of the present disclosure. Please refer to FIG. Figure 3The present disclosure provides an optional implementation mode in which the ice melting line 00 is a three-phase line; the short-circuit device 7 includes three wires 70, the first ends of the wires 70 are connected, and the second ends are respectively connected and fixed to each phase line in the three-phase line.

[0094] Specifically, the short-circuit device 7 is a group of wires, which includes three wires, the first ends of which are connected together in a Y-shaped manner, and the second ends are respectively connected and fixed to each phase line in the three-phase line, so as to achieve a three-phase short circuit at the end of the line. Optionally, the wires can be copper wires, and the wires can be respectively connected and fixed to the three-phase line through hardware.

[0095] Please continue to refer to Figure 1 In an optional embodiment of the present disclosure, the mixed wire diameter distribution network line deicing system 100 provided by the present disclosure is described by taking deicing of a 10kV distribution line with a total length of 4km as an example, wherein the wire diameter of the first sub-segment 4 is 120mm 2 , the length is 1km, the wire diameter of the second sub-segment 5 is 50mm 2 , the length is 2km, the wire diameter of the third sub-segment 6 is 120mm 2 , length is 1km, total length of ice melting line 00 is 4km, within the ice melting system, line parameters are based on GB / T 31487.1 "DC ice melting device Part 1: System design and application guidelines". 120mm 2 The unit impedance of the line is 0.2346+j 0.502Ω / km, 50mm 2 The unit impedance of the line is 0.5599Ω+j0.418Ω / km. The ice-melting current of the first sub-segment 4 and the third sub-segment 6 is selected as I1=I3=500A, the ice-melting current of the second sub-segment 5 is selected as I2=300A, and the voltage U3 direction across the third sub-segment 6 is selected as the reference direction. According to the line length and unit impedance, the impedance Z1 of the first sub-segment 4, the impedance Z2 of the second sub-segment 5, and the impedance Z3 of the third sub-segment 6 can be calculated:

[0096] Z1=Z3=0.2346+j0.502 (7)

[0097] Z2=(0.5599+j0.418)×2=1.1198+j0.836 (8)

[0098] Given the ice melting current I3 of the third sub-segment 6 and the impedance Z3 of the third sub-segment 6, the voltage U3 across the third sub-segment 6 can be calculated:

[0099] U3=I3Z3=500*0.554=277V (9)

[0100] The ice melting current I3 of the third sub-segment 6 and the current I flowing through the reactive absorption device can be calculated by formula (5): C :

[0101]

[0102] In formula (11), X C = modulus of ja.

[0103] It is known that the modulus of the ice-melting current I2 of the second sub-segment 5 is 300. By combining equations (6), (10) and (11), we can obtain:

[0104] X C =-1.153j (12)

[0105] I2=211.6-j212.7 (13)

[0106] Substitute the ice melting current I2 of the second subsection 5, the ice melting current I3 of the third subsection 6, the impedance Z2 of the second subsection 5 and the impedance Z3 of the third subsection 6 into formula (2), and use Z L =jb, we can get:

[0107]

[0108] Knowing the modulus of the ice-melting current I1 of the first subsection 4 and the ice-melting current I2 of the second subsection 5, by combining equations (1) and (14), we can obtain:

[0109]

[0110] Through the above calculation, the single-phase impedance X of the reactive absorption device 8 can be calculated. L and the single-phase impedance X of the reactive power compensation device 9 C The parameters of are shown in formula (12) and formula (15) respectively. The reactive absorption device 8 and the reactive compensation device 9 are configured according to the parameters, and ice melting can be started when ice melting is needed, so that a more suitable ice melting current is provided to the second sub-segment.

[0111] Based on the same inventive concept, the present invention provides a mixed-diameter distribution network line deicing method. Figure 4 The figure is a flow chart of a mixed wire diameter distribution network line deicing method provided by the embodiment of the present disclosure, please refer to Figure 1 and Figure 4 In the mixed line diameter distribution network line deicing method, the mixed line diameter distribution network line deicing system 100 provided by the embodiment of the present disclosure is used to deicing the line;

[0112] Methods for melting ice on mixed-diameter distribution network lines include:

[0113] Step S01, determining whether the ice thickness of the ice melting line 00 reaches the ice melting start condition, and applying for ice melting when the ice thickness of the ice melting line 00 reaches the ice melting start condition;

[0114] Step S02, performing a power outage operation on the ice-melting line 00;

[0115] Step S03, close the switch, and connect the reactive power absorption device 8 and the reactive power compensation device 9 to the ice melting line 00;

[0116] Step S04, starting the ice-melting power supply 1;

[0117] Step S05: the voltage-current converter 3 outputs an adjustable ice-melting voltage and current to melt ice.

[0118] Specifically, the present disclosure provides a method for melting ice on a mixed-diameter distribution network line, including but not limited to steps S01 to S05, specifically, the line operator observes the ice covering the line, and when it is observed that the ice covering thickness of the line reaches the ice melting start condition, applies for ice melting. After the application is approved, the ice melting line 00 is powered off. After the power outage, the knife switches 41 to 43 and knife switches 61 to 63 are closed, and the reactive absorption device 8 and the reactive compensation device 9 are connected to the ice melting line 00. The ice melting power supply 1 is started to supply power to the transformer and current converter 3, and the line begins to flow, and the ice melting line 00 is melted. After observing that all the ice covering the line has fallen off, the ice melting power supply 1 is turned off, the knife switch is disconnected, the power supply to the line is restored, and the ice melting implementation is completed. The mixed-diameter distribution network line de-icing method provided by the present disclosure connects a reactive absorption device 8 and a reactive compensation device 9 between lines with different diameters, so that the lines with different diameters flow through the de-icing current of appropriate size, which is beneficial to avoid the current flowing through the thinner line being greater than its maximum de-icing current, thereby helping to improve the high temperature rise caused by line overcurrent and reduce the occurrence of line disconnection. At the same time, providing a suitable de-icing current for lines with thicker diameters is beneficial to improving the de-icing effect of the line. For mixed-diameter distribution network lines, only one de-icing operation is required to handle the icing situation of the entire mixed-diameter line, and the operating personnel do not need to repeat the de-icing operation many times, which greatly reduces the power outage time of the line and is beneficial to ensuring the power supply to electricity users.

[0119] It can be seen from the above embodiments that the mixed-diameter distribution network line ice melting system and method provided by the present disclosure achieves at least the following beneficial effects:

[0120] The present invention provides a mixed-line distribution network line de-icing system and method, wherein the de-icing system includes: de-icing power supply, de-icing cable, voltage and current conversion device, de-icing line, short-circuit device, reactive absorption device and reactive compensation device; the de-icing line includes a first sub-segment, a second sub-segment and a third sub-segment, the wire diameter of the first sub-segment and the wire diameter of the third sub-segment are larger than the wire diameter of the second sub-segment; the reactive absorption device is connected to the connection of the first sub-segment and the second sub-segment through a knife switch, and is used to absorb the reactive current flowing from the first sub-segment to the second sub-segment; the reactive compensation device is connected to the connection of the second sub-segment and the third sub-segment through a knife switch, and is used to compensate for the de-icing current flowing from the second sub-segment to the third sub-segment. The present invention arranges reactive absorption devices and reactive compensation devices between lines with different wire diameters, so that the lines with different wire diameters flow through de-icing currents of appropriate sizes, which is conducive to avoiding the current flowing through the thinner line being greater than its maximum de-icing current, thereby helping to improve the higher temperature rise caused by line overcurrent and reduce the occurrence of line disconnection. At the same time, providing a suitable ice-melting current for thicker wires is conducive to improving the ice-melting effect of the lines. For mixed-diameter distribution lines, only one ice-melting operation is needed to deal with the ice coverage of the entire mixed-diameter line. Operators do not need to repeat the ice-melting operation many times, which greatly reduces the power outage time of the line and is conducive to ensuring the power supply to electricity users.

[0121] It should be noted that, in this article, relational terms such as "first" and "second" are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "comprise a ..." do not exclude the existence of other identical elements in the process, method, article or device including the elements.

[0122] The above description is only a specific embodiment of the present disclosure, so that those skilled in the art can understand or implement the present disclosure. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present disclosure. Therefore, the present disclosure will not be limited to the embodiments described herein, but will conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A mixed-diameter distribution network line ice melting system, characterized in that: include: Ice-melting power supply, ice-melting cable, voltage-converting and current-converting device, ice-melting line, short-circuiting device, reactive power absorbing device and reactive power compensating device; The ice-melting cable is electrically connected between the ice-melting power supply and the input end of the transformer and current converter, and the ice-melting line is electrically connected between the output end of the transformer and current converter and the short-circuit device; the ice-melting power supply is used to provide the power required by the mixed-line distribution network line ice-melting system, and the transformer and current converter is used to output an adjustable ice-melting voltage and current; The ice melting line includes a first sub-segment, a second sub-segment and a third sub-segment, and the wire diameter of the first sub-segment and the wire diameter of the third sub-segment are greater than the wire diameter of the second sub-segment; The reactive power absorption device is connected to the connection between the first sub-segment and the second sub-segment through a knife switch, and is used to absorb the reactive current flowing from the first sub-segment to the second sub-segment; The reactive power compensation device is connected to the connection between the second sub-segment and the third sub-segment through a knife switch, and is used to compensate for the ice-melting current flowing from the second sub-segment to the third sub-segment.

2. The mixed-diameter distribution network line ice melting system according to claim 1, characterized in that: The ice-melting circuit is a three-phase circuit, and the reactive absorption device includes an inductance element group corresponding to each phase circuit in the ice-melting circuit. The first ends of the inductance element groups are connected, and the second ends are connected in parallel to the connection between the first sub-segment and the second sub-segment through knife switches.

3. The mixed-diameter distribution network line ice melting system according to claim 2, characterized in that: The single-phase impedance of the reactive absorption device is X L ; in, I1 represents the ice melting current of the first sub-segment; I2 represents the ice melting current of the second sub-segment; I3 represents the ice melting current of the third sub-segment; Z2 represents the impedance of the second sub-segment; Z3 represents the impedance of the third sub-segment.

4. The mixed-diameter distribution network line ice melting system according to claim 2, characterized in that: The inductor element group includes a plurality of inductors connected in parallel and having the same parameters.

5. The mixed-line distribution network line ice melting system according to claim 1, characterized in that: The ice-melting line is a three-phase line, and the reactive compensation device includes a capacitor element group corresponding to each phase line in the ice-melting line. The first end of the capacitor element group is connected, and the second end is connected in parallel to the connection between the second sub-segment and the third sub-segment through a knife switch.

6. The mixed-diameter distribution network line ice melting system according to claim 5, characterized in that: The single-phase impedance of the reactive power compensation device is X C ; in, I2 represents the ice melting current of the second sub-segment; I3 represents the ice melting current of the third sub-segment; Z3 represents the impedance of the third sub-segment.

7. The mixed-diameter distribution network line ice melting system according to claim 5, characterized in that: The capacitor element group includes a plurality of capacitors connected in parallel and having the same parameters.

8. The mixed-diameter distribution network line ice melting system according to claim 1, characterized in that: The ice melting circuit is a three-phase circuit; The short-circuit device comprises three conducting wires, the first ends of the conducting wires are connected, and the second ends of the conducting wires are respectively connected and fixed to each phase circuit of the three-phase circuit.

9. A method for melting ice on mixed-diameter distribution network lines, characterized in that: Using the mixed line diameter distribution network line deicing system according to any one of claims 1 to 8 to deicing the line; The mixed-diameter distribution network line deicing method comprises: Determine whether the ice thickness of the ice-melting line reaches the ice-melting start condition, and apply for ice melting when the ice thickness of the ice-melting line reaches the ice-melting start condition; Performing a power outage operation on the ice-melting line; Closing the knife switch, connecting the reactive power absorption device and the reactive power compensation device to the ice melting line; Start the ice melting power supply; The voltage-to-current converter outputs an adjustable ice-melting voltage and current to melt the ice.

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