Method and device for low-frequency ice melting of power distribution network and medium

Abstract

The invention relates to the technical field of ice melting, and discloses a low-frequency ice melting method and device for a power distribution network and a medium. The method comprises the following steps: selecting a 10kV power distribution network ice-melting line section, determining a power taking point and a short-circuit tail end of an ice-melting three-phase line, and obtaining line parameters to determine ice-melting power and total ice-melting power of a wire per unit length; calculating the low-frequency impedance characteristic of the power distribution network line according to the line cross section area, and determining a power-frequency ice-melting current effective value; calculating a power frequency ice melting voltage required by the line based on the ice melting power; determining the lowest ice melting frequency according to a preset proportion based on the power frequency ice melting voltage by taking no over-excitation of the branch line distribution transformer as a constraint; determining a voltage output and a power output of the ice melting device based on the minimum ice melting frequency; and judging whether the load side of the branch transformer has an electric shock risk or not, and carrying out power distribution network line ice melting operation. Reactive power output can be effectively saved, phase line switching operation of direct current ice melting is avoided, and ice melting efficiency is effectively improved.

Description

Technical Field

[0001] This invention relates to the field of de-icing technology, and in particular to a method, equipment and medium for low-frequency de-icing in power distribution networks. Background Technology

[0002] In the past decade, extreme snow and ice weather has become increasingly frequent. Icing and snow accumulation on transmission lines often cause accidents such as line tripping, power outages, pole collapse, conductor galloping, insulator flashover, and communication interruptions. In order to reduce the incidence of transmission line icing disasters and the losses they cause, researchers around the world are actively studying line anti-icing and de-icing technologies to improve the reliability and safety of power grid operation. The mainstream de-icing methods in power grids include DC de-icing, on-load de-icing, and short-circuit de-icing.

[0003] Currently, mainstream de-icing methods are mainly used for de-icing transmission lines, and their applicability to distribution lines is not strong. Distribution network lines have many branches, and DC de-icing requires disconnecting all branches, making the operation quite complex. Load-bearing de-icing and short-circuit de-icing both have certain configuration requirements for the load side and short-circuit point of the distribution network, and are generally not suitable for field use. Summary of the Invention

[0004] In view of the aforementioned existing problems, the present invention is proposed.

[0005] Therefore, the technical problem solved by the present invention is that current de-icing methods are not very applicable to power distribution lines, and both load-bearing de-icing and short-circuit de-icing have configuration requirements for the load side and short-circuit point of the distribution network, and DC de-icing is complicated to operate.

[0006] To solve the above-mentioned technical problems, the present invention provides the following technical solution: In a first aspect, the present invention provides a method for low-frequency de-icing in a power distribution network, comprising: Select a section of the 10kV distribution network ice melting line, determine the power take-off point and the short-circuit end of the three-phase ice melting line, and obtain the corresponding line parameter information; The ice-melting power per unit length of conductor and the total ice-melting power are determined based on the obtained line parameter information; The low-frequency impedance characteristics of the distribution network line are calculated based on the line cross-sectional area, and the effective value of the power frequency de-icing current is determined based on the low-frequency impedance characteristics. Calculate the required power frequency ice-melting voltage for the circuit based on the ice-melting power; With the constraint that the branch distribution transformer does not overexcite, the minimum de-icing frequency is determined according to a preset ratio based on the power frequency de-icing voltage. The minimum voltage output and minimum power output of the ice-melting device are determined based on the minimum ice-melting frequency. Based on the lowest voltage output and lowest power output, determine whether there is a risk of electric shock on the load side of the branch transformer, and implement de-icing operation on the distribution network line based on the judgment result.

[0007] As a preferred embodiment of the low-frequency de-icing method for power distribution networks described in this invention, the method involves determining the de-icing power per unit length of conductor and the total de-icing power based on the acquired line parameter information, including determining the de-icing power per unit length of conductor by line type parameters, specifically including bare conductors and insulated conductors. The de-icing power per unit length of the bare conductor is calculated based on the de-icing heat flux density of the bare conductor, the outer radius of the bare conductor, and the ice layer thickness. The ice-melting power per unit length of the insulated conductor is calculated based on the ice-melting heat flux density of the insulated conductor, the outer radius of the insulated conductor, and the ice layer thickness. The total de-icing power of both bare conductors and insulated conductors is calculated based on the de-icing power per unit length of each conductor and the length of the de-icing line.

[0008] In a preferred embodiment of the low-frequency de-icing method for distribution networks described in this invention, the calculation of the low-frequency impedance characteristics of the distribution network lines based on the line cross-sectional area includes: By combining the values ​​of the low-frequency self-impedance of the corresponding conductor, the external self-inductance of the distribution network line, and the resistance and inductive components of the low-frequency positive sequence impedance of the distribution network line with different cross-sectional areas, the low-frequency positive sequence impedance per kilometer of different distribution network lines is calculated. Among them, the low-frequency self-impedance is calculated by combining the magnetic permeability and conductivity of the conductor, the equivalent radius of the conductor of the distribution network line, and the first-order zero-order modified Bezier function and the first-order modified Bezier function with imaginary parameters.

[0009] As a preferred embodiment of the low-frequency de-icing method for power distribution networks described in this invention, determining the effective value of the power frequency de-icing current based on low-frequency impedance characteristics includes: Power heat balance equations for power frequency de-icing current are established for both bare conductors and insulated conductors. The effective values ​​of the power frequency de-icing current for bare conductors and insulated conductors are determined based on power thermal balance.

[0010] As a preferred embodiment of the low-frequency de-icing method for power distribution networks described in this invention, the method includes: determining the minimum de-icing frequency based on a preset ratio according to the power frequency de-icing voltage, with the constraint that the branch distribution transformer does not experience overexcitation; and including: Obtain the peak value of the core magnetic flux density of the distribution transformer at 50Hz rated voltage; Obtain the peak value of the core magnetic flux density of the distribution transformer during low-frequency ice melting; Based on the two core flux density peak values ​​obtained, the low frequency range is determined by the fact that the branch distribution transformer does not experience overexcitation. The effective value of the low-frequency de-icing voltage is obtained by using the power frequency de-icing voltage. Based on the low-frequency range and a margin of more than double, the minimum de-icing frequency is obtained by taking the proportion of the effective value of the low-frequency de-icing voltage as 1%.

[0011] As a preferred embodiment of the low-frequency de-icing method for power distribution networks described in this invention, determining the minimum voltage output and minimum power output of the de-icing device based on the minimum de-icing frequency includes: Update the line positive sequence impedance according to the lowest ice melting frequency; The minimum voltage output and minimum power output of the ice melting device are calculated based on the minimum ice melting frequency and the updated line positive sequence impedance. The power supply of the low-frequency ice-melting power module is set based on the lowest voltage output and lowest power output, with voltage and power margins reserved.

[0012] As a preferred embodiment of the low-frequency de-icing method for power distribution networks described in this invention, the method for determining whether there is a risk of electric shock on the load side of the branch transformer based on the lowest voltage output and the lowest power output includes: Based on the low-frequency de-icing line section of the distribution network, determine the distribution transformers on all branches within the section and their line distances relative to the de-icing end; Iterate through all the distribution transformers on the branches, and take the line distance from each distribution transformer to the de-icing end as... If the first judgment rule is true, then there is a risk of electric shock, and the branch distribution transformer with the risk of electric shock is removed; otherwise, the branch distribution transformer does not need to be removed. The first judgment rule is expressed as follows: ; In the formula, and These are the primary rated voltage and secondary rated voltage of the distribution transformer, respectively. This refers to the effective value of the low-frequency de-icing voltage on the high-voltage side of the distribution transformer. The distance between each distribution transformer and the de-icing end of the line; This refers to the length of the ice-melting line.

[0013] In a second aspect, the present invention provides a computer device, comprising: Memory and processor; The memory is used to store computer-executable instructions, and the processor is used to execute the computer-executable instructions, which, when executed by the processor, implement the steps of a method for low-frequency de-icing in a power distribution network.

[0014] Thirdly, the present invention provides a computer-readable storage medium storing computer-executable instructions that, when executed by a processor, implement the steps of the method for low-frequency de-icing of the power distribution network.

[0015] Compared with existing technologies, the beneficial effects of this invention are as follows: By rationally configuring the de-icing frequency, this invention prevents over-excitation of the branch distribution transformers throughout the de-icing section; the proposed low-frequency de-icing scheme effectively reduces reactive power loss of the de-icing device; by disconnecting risky branch lines under personal safety voltage limits, the personal safety of the distribution network is ensured; by comparing the current at the beginning and end of the circuit to identify and disconnect the shunt branches of the de-icing current within the de-icing section, this invention more effectively serves the de-icing of distribution network lines with numerous branches; this invention can achieve three-phase de-icing of the line, avoiding the phase switching operation of DC de-icing, and effectively improving de-icing efficiency. Attached Figure Description

[0016] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the following description of the embodiments will be briefly introduced. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 This is a schematic diagram of the overall process of a low-frequency de-icing method for a power distribution network according to an embodiment of the present invention.

[0018] Figure 2 This is a schematic diagram of the topology of the low-frequency de-icing power module in a method for low-frequency de-icing of a power distribution network according to an embodiment of the present invention.

[0019] Figure 3 This is a schematic diagram of the line structure in a low-frequency de-icing method for a power distribution network according to an embodiment of the present invention. Detailed Implementation

[0020] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the protection scope of the present invention.

[0021] Example 1, referring to Figure 1 As an embodiment of the present invention, a method for low-frequency de-icing in a power distribution network is provided, comprising: S100: Select the 10kV distribution network ice melting line section, determine the power take-off point and the short-circuit end of the three-phase ice melting line, and obtain the corresponding line parameter information; S200: Determine the ice-melting power per unit length of conductor and the total ice-melting power based on the acquired line parameter information; S300: Calculate the low-frequency impedance characteristics of the distribution network line based on the line cross-sectional area, and determine the effective value of the power frequency de-icing current based on the low-frequency impedance characteristics. S400: Calculates the required power frequency ice-melting voltage for the circuit based on ice-melting power; S500: The minimum de-icing frequency is determined based on the power frequency de-icing voltage according to a preset ratio, with the constraint that the branch distribution transformer does not over-excite. S600: Determines the minimum voltage output and minimum power output of the ice-melting device based on the minimum ice-melting frequency; S700: Based on the lowest voltage output and lowest power output, determine whether there is a risk of electric shock on the load side of the branch transformer, and implement de-icing operation on the distribution network line based on the judgment result.

[0022] It should be noted that this invention selects a 10kV distribution network de-icing line section. The low-frequency de-icing device is connected to the power take-off point at the beginning of the de-icing line section, and the de-icing switch is short-circuited to the three-phase line at the end of the de-icing line section. First, the low-frequency impedance characteristics of the distribution line are analyzed, and the de-icing current is rationally selected. The de-icing frequency is determined with the constraint that the branch transformers of the entire de-icing line section will not experience over-excitation. The output voltage and power of the low-frequency de-icing device are also preliminarily determined. Second, the minimum de-icing frequency is determined based on the power frequency de-icing voltage according to a preset ratio, and the low-frequency de-icing output voltage and power are configured to effectively save reactive power output. Finally, the low-frequency de-icing operation of the de-icing line section is implemented. Risky branch lines are disconnected through personal safety voltage verification. The current comparison at the beginning and end of the line section is used to identify and disconnect the shunt branches of the de-icing current within the de-icing line section, and finally, the de-icing of the distribution line is achieved.

[0023] Example 2, refer to Figures 1-2 As an embodiment of the present invention, based on the above embodiment, a method for low-frequency de-icing of power distribution networks is provided.

[0024] In this embodiment of the invention, step S100 involves selecting a 10kV distribution network ice-melting line section, determining the power take-off point and the short-circuit end of the three-phase ice-melting line, and obtaining the corresponding line parameter information. Specifically, the relevant line parameter information may include the conductor cross-sectional area of ​​the ice-melting line. (mm) 2 ) and the length of the ice melting line Basic information such as (km).

[0025] In this embodiment of the invention, step S200, which determines the de-icing power per unit length of conductor and the total de-icing power based on the acquired line parameter information, includes the following steps A1-A4: A1: The ice-melting power per unit length of conductor is determined by the line type parameters, specifically including bare conductors and insulated conductors; The de-icing power per unit length of the bare conductor is calculated based on the de-icing heat flux density of the bare conductor, the outer radius of the bare conductor, and the ice layer thickness. Specifically, it is expressed as: (1) In the formula, The melting power per unit length of bare conductor (W); The melting heat flux density of the bare conductor (W / m) 2 ); and These represent the outer radius of the conductor and the thickness of the ice layer (mm), respectively. Let π be the mathematical constant pi. When the thickness of the ice layer is unknown, Take 10-15 units. Take 250~350.

[0026] The ice-melting power per unit length of the insulated conductor is calculated based on the ice-melting heat flux density of the insulated conductor, the outer radius of the insulated conductor, and the ice layer thickness. Specifically, it is expressed as: (2) In the formula, The ice-melting power per unit length of insulated wire (W); The melting heat flux density of insulated conductors (W / m) 2 ); Let be the outer radius of the insulated conductor. When the thickness of the ice layer is unknown, Take 10-15 units. Select 220~300.

[0027] A2: The total de-icing power of bare conductors and insulated conductors is calculated based on the de-icing power per unit length of each conductor and the length of the de-icing line; Specifically, for bare conductors, the total de-icing power is: (3) In the formula, The total de-icing power (kW) of the bare conductor line.

[0028] For insulated wires, the total de-icing power is: (4) In the formula, The total de-icing power (kW) of the insulated conductor line.

[0029] For example, 70mm 2 bare wire, =5mm, =15mm, =300; (5) In this embodiment of the invention, step S300, which calculates the low-frequency impedance characteristics of the distribution network line based on the line cross-sectional area, includes: By combining the values ​​of the low-frequency self-impedance of the corresponding conductor, the external self-inductance of the distribution network line, and the resistance and inductive components of the low-frequency positive sequence impedance of the distribution network line with different cross-sectional areas, the low-frequency positive sequence impedance per kilometer of different distribution network lines is calculated. Specifically, the low-frequency positive-sequence impedance per unit length of distribution network line The calculation formula is: (6) In the formula, For frequency, The low-frequency positive sequence impedance per unit length of the distribution network line; The low-frequency self-impedance per unit length of distribution network line; The external self-inductance per unit length of distribution network line; and These are the resistive and inductive components of the low-frequency positive sequence impedance per unit length of a distribution network line, respectively. represents an imaginary number, =-1.

[0030] Among them, the low-frequency self-impedance is calculated by combining the permeability and conductivity of the conductor, the equivalent radius of the conductor of the distribution network line, and the first-order zero-order modified Bezier function and the first-order modified Bezier function with imaginary arguments. Specifically, the low-frequency self-impedance per unit length of distribution network line for: (7) In the formula, and These are the magnetic permeability and electrical conductivity of the conductor, respectively. The equivalent radius of the conductor in the distribution network line. and These are the zeroth-order modified Bezier function and the first-order modified Bezier function of the first kind with imaginary arguments, respectively.

[0031] Among them, the equivalent radius of the conductors of the distribution network lines The calculation formula is: (8) In the formula, The cross-sectional area of ​​the conductor (mm²) 2 ).

[0032] External self-inductance per unit length of distribution network line for: (9) In the formula, The permeability of free space, The geometric mean distance of the three-phase lines ( , , and These represent the distances from phase A to phase B conductor, phase B to phase C conductor, and phase C to phase A conductor, respectively. It is a logarithmic function with the natural constant as its base.

[0033] Furthermore, it can be based on common cross-sectional areas such as 50, 70, 95, and 120 mm. 2 For distribution network lines, calculate the low-frequency positive sequence impedance per kilometer of the line.

[0034] In this embodiment of the invention, step S300, which determines the effective value of the power frequency de-icing current based on low-frequency impedance characteristics, includes: B1: Establish power heat balance equations for power frequency de-icing current for both bare conductors and insulated conductors; specifically, for bare conductors: (10) In the formula, The effective value of the power frequency de-icing current for bare conductors ( ); The resistance component of the power frequency impedance of a 1km long conductor.

[0035] For insulated wires: (11) In the formula, The effective value of the power frequency de-icing current of the insulated conductor ( ).

[0036] B2: Determine the effective value of power frequency de-icing current for bare conductors and insulated conductors based on power thermal balance; Specifically, for bare conductors: (12) For insulated wires: (13) For example, 70mm 2 bare wire, =37.7, =0.420202; (14) In this embodiment of the invention, step S400 involves calculating the required power frequency de-icing voltage for the circuit based on the de-icing power. Specifically, for bare conductors: (15) In the formula, The effective value (V) of the power frequency de-icing voltage of the bare conductor. The inductive component of the power frequency impedance of a 1km long conductor.

[0037] For insulated wires: (16) In the formula, This is the effective value (V) of the power frequency de-icing voltage for insulated conductors.

[0038] For example, 70mm 2 bare wire, =5km, =299.53A, =0.420202Ω, =0.180767Ω; (17) In this embodiment of the invention, step S500, constrained by the fact that the branch distribution transformer does not experience overexcitation, determines the minimum de-icing frequency based on the power frequency de-icing voltage according to a preset ratio, including the following steps C1-C4: C1: Obtain the peak value of the core magnetic flux density of the distribution transformer at 50Hz rated voltage; Specifically, for distribution transformers, based on their basic operating characteristics: (18) In the formula, The effective value (V) of the 50Hz rated voltage on the high-voltage side of the distribution transformer; The frequency is 50Hz. This refers to the number of turns in the high-voltage winding of the distribution transformer. The peak value (T) of the core flux density at 50Hz rated voltage.

[0039] C2: Obtain the peak value of the core magnetic flux density of the distribution transformer during low-frequency de-icing; Specifically, for distribution transformers, during low-frequency de-icing: (19) In the formula, The effective value (V) of the low-frequency de-icing voltage on the high-voltage side of the distribution transformer is given by bare conductors. or insulated wires Decide; This refers to the ice melting frequency; T represents the peak value of the core magnetic flux density during low-frequency ice melting.

[0040] C3: Based on the two core flux density peak values ​​obtained, the low frequency range is determined by ensuring that the branch distribution transformer does not experience overexcitation; Specifically, for branch distribution transformers to avoid overexcitation during low-frequency de-icing, the following conditions must be met: (20) Right now: (twenty one) For example, a 10kV distribution transformer, if =10500V, =50Hz, the specific formula (21) is as follows: (twenty two) C4: Obtain the effective value of the low-frequency de-icing voltage through the power frequency de-icing voltage. Based on the low-frequency range and the setting of more than double the margin, take the proportion of the effective value of the low-frequency de-icing voltage as 1% to obtain the minimum de-icing frequency. Specifically, to maintain more than double the margin, the minimum ice melting frequency is selected as follows: (twenty three) It should be noted that the coefficient 0.01 (i.e. 1%) is twice the coefficient 0.0048 in formula (22) and rounded down, in order to ensure that the excitation current of low-frequency de-icing is less than 50% of the normal 50Hz excitation current.

[0041] Selecting the de-icing frequency according to formula (23) can effectively prevent the branch distribution transformer from being over-excited, so as to prevent the branch distribution transformer from occupying the de-icing current of the main line.

[0042] because Since the frequency is unknown, the minimum melting frequency can be determined by the 50Hz melting voltage. : (twenty four) In this embodiment of the invention, step S600, which determines the minimum voltage output and minimum power output of the ice-melting device based on the minimum ice-melting frequency, includes: D1: Update the line positive sequence impedance according to the lowest ice melting frequency; Specifically, it can be expressed as: (25) In the formula, The low-frequency positive sequence impedance of a 1km line. and They are respectively The real and imaginary parts.

[0043] D2: Calculate the minimum voltage output of the de-icing device based on the minimum de-icing frequency and the updated line positive sequence impedance. and minimum power output ; Specifically, based on the lowest ice melting frequency Determine the minimum voltage output of the ice-melting device. : (26) In the formula, This is the lowest current output.

[0044] Based on the lowest ice melting frequency Determine the minimum power output of the ice-melting device : (27) For example, 70mm 2 bare wire, =12Hz, =5km, =299.5A, impedance of a 1km conductor at 12Hz =0.420017+ 0.043385 = 0.422252Ω, voltage output and power output The calculation formula is: (28) (29) For example, 70mm 2 bare wire, =50Hz, =5km, = =1186.6V, =299.5A, impedance of a 1km conductor at 50Hz = 0.420202+ 0.180767Ω; Power output The calculation formula is: (30) Comparing formulas (29) and (30), the low-frequency de-icing method can save 184.9 kvar of de-icing reactive power and 7.4% of the output power of the de-icing equipment.

[0045] D3: Set the power supply of the low-frequency ice-melting power module based on voltage output and power output, and reserve voltage margin and power margin.

[0046] For example, the topology of a low-frequency de-icing power module is as follows: Figure 2 As shown; The supercapacitor can be 6800μF, and the power supply outputs at the lowest voltage. and minimum power output The design includes a 10% voltage margin and a 20% power margin.

[0047] In this embodiment of the invention, step S700, based on voltage output and power output, determines whether there is a risk of electric shock on the load side of the branch transformer, including: E1: Determine the distribution transformers and their line distances relative to the ice-melting end on all branch lines within the low-frequency ice-melting line section of the distribution network. E2: Traverse all branch line distribution transformers, and take the line distance from each distribution transformer to the de-icing end as... If the first judgment rule is true, then there is a risk of electric shock, and the branch distribution transformer with the risk of electric shock is removed; otherwise, the branch distribution transformer does not need to be removed. The first judgment rule is expressed as follows: (31) In the formula, and These are the primary rated voltage and secondary rated voltage of the distribution transformer, respectively. The distance between each distribution transformer and the de-icing end of the line; This refers to the length of the ice-melting line.

[0048] Optionally, the criterion for determining the risk of electric shock on the load side of the branch transformer can be modified as follows: (32) In this embodiment of the invention, step S700 involves performing de-icing operations on the power distribution network lines based on the judgment result. For example, this specifically includes: When the low-frequency de-icing line section is de-energized, the first end is connected to the low-frequency de-icing power supply and the end is connected to the de-icing switch. The de-icing switch is short-circuited to the three-phase power distribution line. The low-frequency de-icing device operates at the lowest de-icing frequency. and preset de-icing current The ice melt has begun.

[0049] It should be noted that, Allow users to define custom values.

[0050] like <0.90 This indicates that there are branches drawing ice-melting current within the ice-melting section, and all branches need to be disconnected before proceeding with the preset ice-melting current. Melt the ice; otherwise, use a low-frequency ice-melting device at 1.05. Output ice-melting current.

[0051] The terminal three-phase current detection device returns the average value of the three-phase current. .

[0052] 40 minutes after the ice melt begins, a line inspection is started. Once it is confirmed that the ice on the line in the ice melt section has melted, the ice melt power output is stopped, and the ice melt process ends. If no obvious signs of melting of ice appear on the line in the ice-melting section within 90 minutes, the low-frequency ice melting operation will fail and the ice melting process will end.

[0053] Example 3, referring to Figure 3 Based on the above embodiments and Table 1, this embodiment provides an illustrative scheme for a low-frequency de-icing method for power distribution networks to verify its feasibility and beneficial effects.

[0054] like Figure 3 As shown, a 70mm section over a length of 5km 2 For the route, select the lowest de-icing frequency. =12Hz, voltage output =1095.3V, power output Among them, the appendix Figure 3 The combination of "# + number" is an example of a node number.

[0055] The line distances at the de-icing ends of all branch distribution transformers (transformer 1 to transformer 13) are shown in Table 1. The disconnection distance is determined according to formula (31). =7.4km.

[0056] Table 1. Distance between distribution transformer and de-icing terminal and disconnection results

[0057] Therefore, there is no need to disconnect any branch distribution transformers, and the de-icing can be completed based on the steps of the above embodiments.

[0058] Example 4 illustrates a schematic scheme for a low-frequency de-icing method for power distribution networks. It should be noted that the technical solution for the low-frequency de-icing equipment in this example is based on the same concept as the technical solution for the low-frequency de-icing method described above. Details not described in detail in this example can be found in the description of the technical solution for the low-frequency de-icing method described above.

[0059] This embodiment also provides a computer device suitable for low-frequency de-icing in power distribution networks, comprising: a memory and a processor; the memory is used to store computer-executable instructions, and the processor is used to execute the computer-executable instructions to implement the method for low-frequency de-icing in power distribution networks as proposed in the above embodiment.

[0060] This embodiment also provides a storage medium storing a computer program that, when executed by a processor, implements the method for low-frequency de-icing of the power distribution network as proposed in the above embodiments.

[0061] The storage medium proposed in this embodiment and the method for realizing low-frequency de-icing of power distribution networks proposed in the above embodiments belong to the same inventive concept. Technical details not described in detail in this embodiment can be found in the above embodiments, and this embodiment has the same beneficial effects as the above embodiments.

[0062] From the above description of the implementation methods, those skilled in the art will clearly understand that the present invention can be implemented using software and necessary general-purpose hardware, and of course, it can also be implemented using hardware. Furthermore, the device for low-frequency de-icing in power distribution networks does not constitute a limitation on all components; for specific implementation methods, please refer to the above embodiments, which will not be repeated here.

[0063] Based on this understanding, the technical solution of the present invention, or the part that contributes to the prior art, can be embodied in the form of a software product. This computer software product can be stored in a computer-readable storage medium, such as a computer floppy disk, read-only memory (ROM), random access memory (RAM), flash memory, hard disk, or optical disk, etc., including several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute the methods of the various embodiments of the present invention.

[0064] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A method for low frequency ice melting of a power distribution network, characterized in that, The method comprises the steps of: selecting a 10kV distribution network ice-melting line section, determining a power supply point and a short-circuit end of the ice-melting three-phase line, and obtaining corresponding line parameter information; determining the ice-melting power per unit length of the conductor and the total ice-melting power based on the obtained line parameter information; calculating the low-frequency impedance characteristics of the distribution network line according to the cross-sectional area of the line, and determining the effective value of the power frequency ice-melting current based on the low-frequency impedance characteristics; calculating the power frequency ice-melting voltage required by the line based on the ice-melting power; determining the minimum ice-melting frequency based on the power frequency ice-melting voltage and a preset proportion, with the constraint that over-excitation of the branch distribution transformer does not occur; determining the minimum voltage output and the minimum power output of the ice-melting device based on the minimum ice-melting frequency; based on the minimum voltage output and the minimum power output, determining whether there is a risk of electric shock on the load side of the branch transformer, and implementing the ice-melting operation of the distribution network line based on the determination result.

2. The method for low frequency ice melting of a power distribution network according to claim 1, characterized in that, Determine the ice-melting power per unit length of the conductor and the total ice-melting power based on the obtained line parameter information, including: determine the ice-melting power per unit length of the conductor from the line parameters, including bare conductors and insulated conductors; The ice-melting power per unit length of the bare conductor is calculated based on the ice-melting heat flux density of the bare conductor and the outer radius of the bare conductor and the ice layer thickness; The ice-melting power per unit length of the insulated conductor is calculated based on the ice-melting heat flux density of the insulated conductor and the outer radius of the insulated conductor and the ice layer thickness; The total ice-melting power of the bare conductor and the insulated conductor is calculated based on the ice-melting power per unit length of the respective conductors and the length of the ice-melting line.

3. The method for low frequency ice melting of a power distribution network according to claim 2, characterized in that, Calculate the low-frequency impedance characteristics of the distribution network line according to the cross-sectional area of the line, including: Determine the values of the low-frequency self-impedance of the corresponding conductor, the external self-inductance of the distribution network line, and the resistance component and inductance component of the low-frequency positive sequence impedance for different cross-sectional area distribution network lines, and calculate the low-frequency positive sequence impedance per kilometer for different distribution network lines. The low-frequency self-impedance is calculated by combining the magnetic permeability and electrical conductivity of the conductor, the equivalent radius of the distribution network line conductor, and the first-order modified Bessel function and the first-order modified Bessel function with imaginary part.

4. The method for low frequency ice melting of a power distribution network according to claim 3, characterized in that, Determine the effective value of the power frequency ice-melting current based on the low-frequency impedance characteristics, including: Establish the power thermal balance equation of the power frequency ice-melting current for bare conductors and insulated conductors respectively; Determine the effective value of the power frequency ice-melting current of the bare conductor and the insulated conductor based on the power thermal balance.

5. The method for low frequency ice melting of a power distribution network according to claim 4, characterized in that, Determine the minimum ice-melting frequency based on the power frequency ice-melting voltage and a preset proportion, with the constraint that over-excitation of the branch distribution transformer does not occur, including: Obtain the peak value of the core magnetic flux density of the distribution transformer under 50Hz rated voltage; Obtain the peak value of the core magnetic flux density of the distribution transformer during low-frequency ice-melting; Determine the low-frequency range based on the two obtained core magnetic flux density peak values, with the constraint that over-excitation of the branch distribution transformer does not occur; Obtain the effective value of the low-frequency ice-melting voltage from the power frequency ice-melting voltage, based on the low-frequency range and the setting of a double or more margin, take the low-frequency ice-melting voltage effective value proportion of 1% to obtain the minimum ice-melting frequency.

6. The method for low frequency ice melting of a power distribution network according to claim 5, characterized in that, Determine the minimum voltage output and the minimum power output of the ice-melting device based on the minimum ice-melting frequency, including: update the line positive sequence impedance at the minimum ice-melting frequency; The minimum voltage output and the minimum power output of the ice-melting device are calculated based on the minimum ice-melting frequency and the updated line positive sequence impedance; The power supply of the low-frequency ice-melting power module is set based on the minimum voltage output and the minimum power output, and voltage margin and power margin are reserved.

7. The method for low frequency ice melting of a power distribution network according to claim 6, characterized in that, Based on the minimum voltage output and the minimum power output, it is determined whether there is a risk of electric shock on the load side of the branch transformer, including: From the low-frequency ice-melting line section of the power distribution network, the distribution transformers on all branches in the section and the line distance from the ice-melting end are determined. The line distance of each distribution transformer to the ice-melting terminal is taken as If the first judging rule is established, there is a risk of electric shock, and the branch line distribution transformer with the risk of electric shock is exited; otherwise, the branch line distribution transformer is not exited. The first determination rule is expressed as: ； In the formula, and are the rated voltage of the primary side and the rated voltage of the secondary side of the distribution transformer, respectively; is the effective value of the low-frequency ice-melting voltage on the high-voltage side of the distribution transformer; is the line distance of each distribution transformer to the ice-melting end; is the length of the ice-melting line.

8. A computer device, comprising: including: a memory and a processor; The memory is used to store computer executable instructions, and the processor is used to execute the computer executable instructions, which realize the steps of the method for low-frequency ice-melting of the power distribution network according to any one of claims 1 to 7.

9. A computer-readable storage medium, characterized in that, The memory has computer executable instructions stored therein, which realize the steps of the method for low-frequency ice-melting of the power distribution network according to any one of claims 1 to 7 when executed by the processor.

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