A DC deicing method for distribution network lines

Abstract

The present invention relates to the technical field of distribution network line safety, and discloses a distribution network line DC ice melting method, comprising the following steps: S1: erecting a protective cabin, arranging an ice melting device in the protective cabin, erecting the protective cabin at two sections of the line to be ice-melted, and arranging a switching unit, a rectifier unit and a control unit in the cabin, the ice melting device comprising a first ice melting device and a second ice melting device, and the first ice melting device and the second ice melting device are connected in series; S2: short-circuit modification, short-circuit modification of the line to be ice-melted, specifically, powering off the line to be ice-melted, and using an ice-melting short-circuit wire at the end of the line to short-circuit the line to be ice-melted; S3: collecting data. The present invention realizes the switching between the first ice melting device and the second ice melting device by adjusting the switch or wiring on the DC side of the DC ice melting device, which can meet the needs of different ice-melting scenarios, save the investment in power grid equipment, and improve the utilization rate of the equipment and the efficiency of ice-melting work.

Description

Technical Field

[0001] The invention relates to the technical field of distribution network line safety, and in particular to a direct current ice melting method for a distribution network line. Background Art

[0002] Among all the natural disasters suffered by the power system, ice disasters are the most serious damage to the power system. The losses caused by ice disasters to the power grid are often more serious. At the least, ice flash will occur, and at the worst, it will cause tower collapse and disconnection, or even paralysis of the power grid. The existing de-icing treatment for the power grid uses DC de-icing technology, which is achieved through high-power DC de-icing devices.

[0003] The original DC ice melting device is mobile or fixed, with a maximum output current of 2500A. In actual ice melting, due to the long line and the need to complete the line ice melting within the specified time, the ice melting device can only melt the ice in a single group. If a DC ice melting device for melting the ice of AC transmission lines is used to melt the ice of overhead ground wires, the length of the overhead ground wire to be melted is short, and the practicality of the ice melting device is not strong. Therefore, a DC ice melting method for distribution network lines is proposed. Summary of the invention

[0004] 1. Technical issues to be resolved

[0005] In view of the shortcomings of the prior art, the present invention provides a DC ice-melting method for distribution network lines. By adjusting the switch or wiring on the DC side of the DC ice-melting device, switching between a first ice-melting device and a second ice-melting device is achieved, thereby meeting the needs of different ice-melting scenarios, saving power grid equipment investment, and improving equipment utilization and ice-melting work efficiency.

[0006] (II) Technical solution

[0007] To achieve the above object, the present invention provides the following technical solutions:

[0008] A method for melting ice on a distribution network line DC includes the following steps:

[0009] S1: erecting a protective cabin, arranging an ice melting device in the protective cabin, erecting the protective cabin at two sections of the line to be ice-melted, and arranging a switching unit, a rectifying unit and a control unit in the cabin, wherein the ice melting device includes a first ice melting device and a second ice melting device, and the first ice melting device and the second ice melting device are connected in series;

[0010] S2: Short-circuit transformation: short-circuit the line to be de-iced, specifically shut down the line to be de-iced, and use an ice-melting short-circuit wire at the end of the line to short-circuit the line to be de-iced;

[0011] S3: Collect data, collect the length of the ice-melting line and the actual output current value of the rectifier unit, obtain the line impedance, and calculate its actual output voltage value;

[0012] S4: Calculate the ice-melting current value, and calculate the ice-melting current value required for the ice-melting line according to the impedance;

[0013] S5: regulating the current to melt ice, controlling the actual output current of the ice-melting device through the control unit to make it the same as the ice-melting current value required by the ice-melting line, and performing ice-melting.

[0014] As a further solution of the present invention, the rectifier unit and the switch unit in S1 are connected in series, the control unit is used to control the rectifier unit to rectify and output a DC ice-melting current, and the switch unit loads the DC ice-melting current output by the rectifier unit to the line to be melted.

[0015] Furthermore, the first ice melting device in S1 is an LCC DC ice melting device, and the second ice melting device is a VSC ice melting device. The LCC DC ice melting device includes an AC circuit breaker, an excitation controller, a filter, a converter valve and a DC side switch, and the VSC DC ice melting device includes an AC circuit breaker, a charging resistor, a bridge arm reactor and a flexible DC converter valve.

[0016] On the basis of the above scheme, the switching unit in S2 is electrically connected to the ice-melting line through a knife switch, and the ice-melting device connects the DC output side of the rectifier unit in parallel to the ice-melting line through the switching unit.

[0017] Furthermore, in S3, the line impedance of the ice-melting line is obtained by looking up a table according to the length of the line, and the actual output voltage value is calculated according to the output power of the ice-melting device.

[0018] As a further solution of the present invention, in S5, as the temperature rises, the impedance of the ice-melting circuit becomes larger, and the output current needs to be increased. When the existing device cannot continue to increase the current, the number of protective cabins is increased to achieve the desired ice-melting effect.

[0019] (III) Beneficial effects

[0020] Compared with the prior art, the present invention provides a DC deicing method for distribution network lines, which has the following features:

[0021] Beneficial effects:

[0022] 1. In the present invention, the provision of a protective cabin can facilitate the movement of the ice melting device, protect it, and increase its service life.

[0023] 2. In the present invention, the switching between the first ice melting device and the second ice melting device is achieved by adjusting the switch or connection on the DC side of the DC ice melting device, which can meet the needs of different ice melting scenarios, save power grid equipment investment, and improve equipment utilization and ice melting efficiency.

[0024] 3. In the present invention, the current is adjusted by adjusting the excitation controller, and the total ice-melting current is achieved by controlling the output current of each ice-melting device, so as to ensure that the output current of each group of ice-melting devices is consistent and realize unified control, thereby preventing the damage of the ice-melting equipment and excessive harmonic current caused by the unbalanced output current. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 The present invention provides a schematic flow chart of the steps of a method for DC ice melting in a distribution network line. DETAILED DESCRIPTION

[0026] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0027] Example 1

[0028] Reference Figure 1 , a distribution network line DC de-icing method, comprising the following steps:

[0029] S1: erect a protective cabin, arrange the ice melting device in the protective cabin, erect the protective cabin at two sections of the line to be melted, and arrange a switching unit, a rectifying unit and a control unit in the cabin. The ice melting device includes a first ice melting device and a second ice melting device, and the first ice melting device and the second ice melting device are connected in series. In S1, the rectifying unit and the switching unit are connected in series. The control unit is used to control the rectifying unit to rectify and output a DC ice melting current. The switching unit loads the DC ice melting current output by the rectifying unit to the line to be melted. The setting of the protective cabin can facilitate the movement of the ice melting device, protect it, and increase its service life. The first ice melting device in S1 is an LCC DC ice melting device, and the second ice melting device is a VSC ice melting device. The LCC DC ice melting device in S1 includes an AC circuit breaker, an excitation controller, a filter, a converter valve and a DC side switch, and the VSC DC ice melting device includes an AC circuit breaker, a charging resistor, a bridge arm reactor and a flexible DC converter valve. The current is adjusted by adjusting the excitation controller, and the switch or wiring on the DC side of the DC ice melting device is adjusted to achieve the switching between the first ice melting device and the second ice melting device. The needs of different ice melting scenarios can be met, saving power grid equipment investment and improving equipment utilization and ice melting efficiency.

[0030] S2: Short-circuit modification, short-circuit modification of the ice-melting line, specifically, shut down the ice-melting line, and use an ice-melting short-circuit wire at the end of the line to short-circuit the ice-melting line. The switching unit in S2 is electrically connected to the ice-melting line through a knife switch, and the ice-melting device connects the DC output side of the rectifier unit in parallel to the ice-melting line through the switching unit;

[0031] S3: Collect data, collect the length of the ice-melting line and the actual output current value of the rectifier unit, obtain the line impedance, and calculate its actual output voltage value. In S3, the line impedance of the ice-melting line is obtained by looking up a table according to the length of the line, and the actual output voltage value is calculated according to the output power of the ice-melting device;

[0032] S4: Calculate the ice-melting current value, and calculate the ice-melting current value required for the ice-melting line according to the impedance;

[0033] S5: Adjust the current to melt the ice. The actual output current of the ice-melting device is controlled by the control unit to make it the same as the ice-melting current value required by the ice-melting line to be melted. The total ice-melting current is achieved by controlling the output current of each ice-melting device to ensure that the output current of each group of ice-melting devices is consistent and unified control is achieved to prevent damage to the ice-melting equipment and excessive harmonic current caused by an unbalanced output current.

[0034] Example 2

[0035] Reference Figure 1 , a distribution network line DC de-icing method, comprising the following steps:

[0036] S1: erect a protective cabin, arrange the ice melting device in the protective cabin, erect the protective cabin at two sections of the line to be melted, and arrange a switching unit, a rectifying unit and a control unit in the cabin. The ice melting device includes a first ice melting device and a second ice melting device, and the first ice melting device and the second ice melting device are connected in series. In S1, the rectifying unit and the switching unit are connected in series. The control unit is used to control the rectifying unit to rectify and output a DC ice melting current. The switching unit loads the DC ice melting current output by the rectifying unit to the line to be melted. The setting of the protective cabin can facilitate the movement of the ice melting device, protect it, and increase its service life. The first ice melting device in S1 is an LCC DC ice melting device, and the second ice melting device is a VSC ice melting device. The LCC DC ice melting device in S1 includes an AC circuit breaker, an excitation controller, a filter, a converter valve and a DC side switch, and the VSC DC ice melting device includes an AC circuit breaker, a charging resistor, a bridge arm reactor and a flexible DC converter valve. The current is adjusted by adjusting the excitation controller, and the switch or wiring on the DC side of the DC ice melting device is adjusted to achieve the switching between the first ice melting device and the second ice melting device. The needs of different ice melting scenarios can be met, saving power grid equipment investment and improving equipment utilization and ice melting efficiency.

[0037] S2: Short-circuit modification, short-circuit modification of the ice-melting line, specifically, shut down the ice-melting line, and use an ice-melting short-circuit wire at the end of the line to short-circuit the ice-melting line. The switching unit in S2 is electrically connected to the ice-melting line through a knife switch, and the ice-melting device connects the DC output side of the rectifier unit in parallel to the ice-melting line through the switching unit;

[0038] S3: Collect data, collect the length of the ice-melting line and the actual output current value of the rectifier unit, obtain the line impedance, and calculate its actual output voltage value. In S3, the line impedance of the ice-melting line is obtained by looking up a table according to the length of the line, and the actual output voltage value is calculated according to the output power of the ice-melting device;

[0039] S4: Calculate the ice-melting current value, and calculate the ice-melting current value required for the ice-melting line according to the impedance;

[0040] S5: Adjust the current to melt the ice. The actual output current of the ice-melting device is controlled by the control unit to make it the same as the ice-melting current value required by the ice-melting line to be melted. The total ice-melting current is achieved by controlling the output current of each ice-melting device to ensure that the output current of each group of ice-melting devices is consistent and unified control is achieved to prevent damage to the ice-melting equipment and excessive harmonic current caused by an unbalanced output current.

[0041] S6: As the temperature rises, the impedance of the ice-melting circuit increases, and the output current needs to be increased. When the existing device cannot continue to increase the current, the number of protective cabins can be increased to achieve the desired ice-melting effect.

[0042] In the description of this article, it should be noted that relational terms such as first and second, etc. 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", "comprises" or any other variations 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.

[0043] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A DC de-icing method for distribution network lines, characterized in that: The following steps are involved: S1: erecting a protective cabin, arranging an ice melting device in the protective cabin, erecting the protective cabin at two sections of the line to be ice-melted, and arranging a switching unit, a rectifying unit and a control unit in the cabin, wherein the ice melting device includes a first ice melting device and a second ice melting device, and the first ice melting device and the second ice melting device are connected in series; S2: Short-circuit transformation: short-circuit the line to be de-iced, specifically shut down the line to be de-iced, and use an ice-melting short-circuit wire at the end of the line to short-circuit the line to be de-iced; S3: Collect data, collect the length of the ice-melting line and the actual output current value of the rectifier unit, obtain the line impedance, and calculate its actual output voltage value; S4: Calculate the ice-melting current value, and calculate the ice-melting current value required for the ice-melting line according to the impedance; S5: regulating the current to melt ice, controlling the actual output current of the ice-melting device through the control unit to make it the same as the ice-melting current value required by the ice-melting line, and then melting ice.

2. A distribution network line DC de-icing method according to claim 1, characterized in that: In the S1, the rectifier unit and the switch unit are connected in series, the control unit is used to control the rectifier unit to rectify and output a DC ice-melting current, and the switch unit loads the DC ice-melting current output by the rectifier unit onto the circuit to be melted.

3. A distribution network line DC de-icing method according to claim 2, characterized in that: The first ice melting device in S1 is an LCC DC ice melting device, and the second ice melting device is a VSC ice melting device. The LCC DC ice melting device includes an AC circuit breaker, an excitation controller, a filter, a converter valve and a DC side switch, and the VSC DC ice melting device includes an AC circuit breaker, a charging resistor, a bridge arm reactor and a flexible DC converter valve.

4. A distribution network line DC de-icing method according to claim 3, characterized in that: The switching unit in S2 is electrically connected to the ice-melting line through a knife switch, and the ice-melting device connects the DC output side of the rectifier unit in parallel to the ice-melting line through the switching unit.

5. A distribution network line DC de-icing method according to claim 1, characterized in that: In S3, the line impedance of the ice-melting line is obtained by looking up a table according to the length of the line, and the actual output voltage value is calculated according to the output power of the ice-melting device.

6. A distribution network line DC de-icing method according to claim 1, characterized in that: In S5, as the temperature rises, the impedance of the ice-melting circuit increases, and the output current needs to be increased. When the existing device cannot continue to increase the current, the number of protective cabins is increased to achieve the desired ice-melting effect.

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