Tower head design and configuration method for realizing high-altitude heavy ice area

Abstract

The invention relates to the technical field of ultra-high voltage transmission line tower head design, and particularly discloses a tower head design configuration method for realizing a high-altitude heavy ice area, which specifically comprises the following steps: S1, selecting a minimum tower head size according to electric clearance control; s2, calculating the phase spacing, and enabling the phase spacing to tend to be minimum when the audible noise and radio interference limit values are met; s3, the distance between the horizontally-arranged wires is determined; s4, determining the height of the ground wire support under the deicing condition; s5, calculating the maximum electric field intensity Em and the corona critical electric field intensity E0 of different ground wire surfaces, and calculating the minimum ground wire support height; s6, the minimum ground wire support height meeting the requirement is selected; and S7, determining the distance between the span central wire and the ground wire. According to the invention, the problems of electromagnetic environment, deicing jump, corona and the like in the high-altitude heavy ice area are effectively solved, and the safety of the power transmission line in the high-altitude heavy ice area is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of tower head design for ultra-high voltage transmission lines, and more specifically to a tower head design configuration method for implementing high-altitude heavy ice areas. Background Art

[0002] For UHV transmission lines in heavy icing areas, they often pass through high altitudes and areas with large elevation differences. The terrain is more severe than before, and electromagnetic environmental problems such as conductor corona audible noise and radio interference are particularly prominent. In recent years, domestic winter transmission line disconnections and flashovers between conductors and ground wires have occurred frequently. According to fault analysis, the main cause is heavy icing.

[0003] Due to factors such as ice coverage, ice shedding, radio interference, audible noise, and corona, the tower head design in plain light ice areas can no longer meet the tower head design requirements for transmission lines in high altitude and heavy ice areas. With the increase in UHV transmission lines in recent years, this phenomenon can no longer be ignored.

[0004] Therefore, an improved tower head design is needed to effectively solve the problems of electromagnetic environment, ice shedding jumping, corona, etc. in high-altitude heavy ice areas, improve the safety of transmission lines in high-altitude heavy ice areas, and provide technical support for building a "strong power grid" and a new power system. Summary of the invention

[0005] The technical problem to be solved by the present invention is to provide a tower head design and configuration method for realizing high-altitude heavy ice areas, effectively solve the electromagnetic environment, ice shedding jump, corona and other problems existing in high-altitude heavy ice areas, and improve the safety of power transmission lines in high-altitude heavy ice areas;

[0006] The solution adopted by the present invention to solve the technical problem is:

[0007] A tower head design and configuration method for realizing high-altitude heavy ice areas specifically comprises the following steps:

[0008] Step S1: Select the minimum tower head size according to the electrical clearance control;

[0009] Step S2: Calculate the phase spacing according to the electromagnetic environment requirements, and make the phase spacing tend to be minimum when meeting the audible noise and radio interference limits;

[0010] Step S3: Determine the distance between the horizontally arranged wires so that the tower head spacing is not less than the distance between the horizontally arranged wires;

[0011] Step S4: Under de-icing conditions, determine the height of the ground wire support;

[0012] Step S5: Calculate the maximum electric field strength E on the surface of different ground wires mand the corona critical electric field strength E0, calculate the minimum ground wire support height;

[0013] Step S6: Select the minimum ground wire support height that meets the requirements;

[0014] Step S7: Determine the distance between the center conductor of the span and the ground wire.

[0015] In some possible implementations, step S2 specifically refers to:

[0016] Through multiple combinations of tower head phase spacing and conductor-to-ground distance, the electromagnetic environment of the maximum electric field strength on the conductor surface, radio interference, audible noise, and the ratio of the maximum electric field strength on the conductor surface to the corona critical electric field strength are calculated to obtain the value of the phase spacing.

[0017] When meeting the audible noise and radio interference limits, select the minimum phase spacing value.

[0018] In some possible implementations, the method for calculating the audible noise in step S2 is:

[0019] L w.i =-177.6+120lg(g max i )+26.4lg(n)+55lg(d);

[0020] Among them, g maxi is the effective value of the maximum potential gradient on the conductor surface;

[0021] d is the wire diameter;

[0022] n is the number of wire splits;

[0023] L w.i is the A-weighted sound power level of the audible noise per unit length of the i-th phase conductor.

[0024] In some possible implementations, the radio interference calculation method is:

[0025] Γ=55-576.5 / g maxi +42.4lg(2r)-0.714lg(n);

[0026] Where, Γ is the excitation function;

[0027] n is the number of wire splits, the valid range is 4 to 12;

[0028] r is the wire radius, and the effective range is 2.4cm to 4cm.

[0029] In some possible implementations, the maximum electric field strength E of different ground lines is calculated in step S5. mSpecifically, it means: using Markt and Mendel method, Successive Images method, Simulator Charges method or Moment Methods method to calculate the maximum electric field strength E on the surface of different ground wires. m .

[0030] In some possible implementations, the calculation of the corona critical electric field strength E0 in step S5 specifically refers to:

[0031]

[0032] Among them, E0 is the critical electric field strength of wire corona;

[0033] m is the conductor surface coefficient;

[0034] σ is the relative air density;

[0035] r is the wire radius;

[0036] p is the air pressure;

[0037] t is the temperature.

[0038] In some possible implementations, step S4 specifically includes:

[0039] Select typical tension sections in typical ice areas for modeling;

[0040] Perform de-ice jump calculations;

[0041] According to the de-icing jump calculation results, the height of the ground wire bracket is determined when the static approach distance and dynamic approach distance are met and the horizontal offset value of the ground wire is taken into account.

[0042] In some possible implementations, the minimum ground wire support height that meets the requirements is selected based on multiple combinations of the protection angle of the ground wire to the conductor and the horizontal displacement of the ground wire.

[0043] Compared with the prior art, the present invention has the following beneficial effects:

[0044] The present invention effectively solves the problems of electromagnetic environment, ice shedding jumping, corona, etc. in high-altitude heavy ice areas, improves the safety of power transmission lines in high-altitude heavy ice areas, and provides technical support for new power systems. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Figure 1 It is a work flow chart of the present invention;

[0046] Figure 2 This is a static diagram of the conductor being 100% de-iced in the present invention;

[0047] Figure 3It is a static schematic diagram of 80% de-icing of the conductor in the present invention. DETAILED DESCRIPTION

[0048] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral body; it can be directly connected, or indirectly connected through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. The "first", "second" and similar words mentioned in this application do not indicate any order, quantity or importance, but are only used to distinguish different components. Similarly, "one" or "one" and other similar words do not indicate a quantity restriction, but indicate the existence of at least one. In the implementation of this application, "and / or" describes the association relationship of the associated objects, indicating that there can be three relationships, for example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. In the description of the embodiments of the present application, unless otherwise specified, the meaning of "multiple" refers to two or more. For example, multiple positioning columns refer to two or more positioning columns. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0049] The present invention is described in detail below.

[0050] like Figure 1 As shown:

[0051] A tower head design and configuration method for realizing high-altitude heavy ice areas specifically comprises the following steps:

[0052] Step S1: Select the minimum tower head size according to the electrical clearance control;

[0053] The minimum clearance between the conductor windage trajectory and the tower components and the operating and maintenance personnel under the working conditions of power frequency voltage, operation and lightning overvoltage, and live maintenance in the tower head clearance circle belongs to the electrical clearance between the conductor and the tower or relative to the ground; the electrical clearance must meet the requirements of the regulations and specifications; the electrical clearance circle can be drawn according to the altitude, pollution area, V-string angle, insulator hardware string size, and the clearance requirements of the regulations; the minimum tower head size controlled by the electrical clearance is obtained according to the optimal arrangement of the clearance circle on the tower window.

[0054] Step S2: Calculate the phase spacing according to the electromagnetic environment requirements, and make the phase spacing tend to be minimum when meeting the audible noise and radio interference limits;

[0055] Through multiple combinations of tower head phase spacing and conductor-ground distance, the electromagnetic environment of the maximum electric field strength on the conductor surface, radio interference, audible noise, and the ratio of the maximum electric field strength on the conductor surface to the corona critical electric field strength is calculated to obtain the value of the phase spacing; and the value is minimized when the audible noise and radio interference limits are met.

[0056] Specifically, the electromagnetic environment of an AC transmission line refers to the sum of all electromagnetic phenomena existing in a given place, mainly involving aspects such as power frequency electric field, power frequency magnetic field, radio interference and audible noise. In line design and construction, these electromagnetic environment factors must meet environmental protection requirements, such as the power frequency electric field, power frequency magnetic induction intensity, radio interference limit, audible noise limit of an AC line, and the ground synthetic electric field strength and ion flow density limit of a DC line.

[0057] The larger the phase (pole) spacing at the tower head, the better the electromagnetic environment such as the radio interference limit and audible noise limit, and vice versa.

[0058] The electromagnetic environment such as the maximum electric field strength on the conductor surface, radio interference, audible noise, the ratio of the maximum electric field strength on the conductor surface to the critical electric field strength of corona, etc. is calculated by combining the tower head phase (pole) spacing and the conductor distance to the ground, and the optimal phase (pole) spacing value is obtained. Generally, the change of the average distance of the conductor to the ground has little effect on the audible noise and radio interference values. In practical applications, the optimization is mainly carried out through the phase (pole) spacing.

[0059] Specifically, the calculation method of audible noise is:

[0060] L w.i =-177.6+120lg(g max i )+26.4lg(n)+55lg(d);

[0061] Among them, g maxi is the effective value of the maximum potential gradient on the conductor surface;

[0062] d is the wire diameter;

[0063] n is the number of wire splits;

[0064] L w.i is the A-weighted sound power level of the audible noise per unit length of the i-th phase conductor.

[0065] Specifically, the radio interference calculation method is:

[0066] Γ=55-576.5 / g maxi +42.4lg(2r)-0.714lg(n);

[0067] Where, Γ is the excitation function;

[0068] n is the number of wire splits, the valid range is 4 to 12;

[0069] r is the wire radius, and the effective range is 2.4cm to 4cm.

[0070] Step S3: Determine the distance between the horizontally arranged conductors so that the distance between the tower heads should not be less than the distance between the horizontally arranged conductors;

[0071] That is: the distance between horizontally arranged conductors should meet the requirements of the "Electrical Design Code for Overhead Transmission Lines" (DL / T 5582-2020); the tower head phase spacing should not be less than the distance between horizontally arranged conductors.

[0072] Step S4: Under de-icing conditions, determine the height of the ground wire support; specifically including:

[0073] Select typical tension sections in typical ice areas for modeling;

[0074] Perform de-ice jump calculations;

[0075] According to the de-icing jump calculation results, the height of the ground wire bracket is determined when the static approach distance and dynamic approach distance are met and the horizontal offset value of the ground wire is taken into account.

[0076] Specifically, according to the Technical Specification for the Design of Overhead Transmission Lines with Heavy Ice (DL / T5440-2020), in order to reduce or avoid flashover accidents between conductors, when non-horizontal arrangement is adopted, there should be sufficient vertical line spacing and horizontal displacement on the tower to meet the static and dynamic approach electrical clearance requirements between the conductor and the ground wire or between the conductors when de-icing at different stages. The static approach distance should not be less than the clearance value of the operating overvoltage, and the dynamic approach distance should not be less than the clearance value of the power frequency (working) voltage; in addition to meeting the overvoltage protection requirements, the distance between the conductor and the ground wire of the heavily iced line in the center of the span should also be verified for the dynamic and static approach distance between the conductor and the ground wire when de-icing at different stages. Verification conditions: Calculated based on the de-icing of the conductor in the middle of the continuous span, and the conductors and ground wires in the other spans are not de-iced. The de-icing rate of the middle span should be determined based on operating experience. When data is lacking, the lines in the heavy ice zone of 330kV and above can be selected to be not less than 80% of the design ice weight.

[0077] Based on the safety concept, differentiated designs are carried out for special areas such as heavy ice areas to improve the safety and reliability of the power grid in the new era. The ground wire is checked for 5mm and 10mm more ice than the conductor, and both the static approach and dynamic approach clearances take into account the wind speed at the same time as the ice.

[0078] Select typical tension sections in typical ice areas for modeling, and calculate the static deicing situation: consider the ground wire sag as 100% uniform ice sag in all sections, and the conductor deicing sag as 100% deicing in a certain section and 100% uniform ice sag in the remaining sections. Dynamic deicing situation: consider the ground wire sag as 100% uniform ice sag in all sections, and the conductor deicing sag as 80% deicing in a certain section and 100% uniform ice sag in the remaining sections;

[0079] According to the de-icing jump calculation results, the height of the ground wire bracket must meet the static approach distance and dynamic approach distance; at the same time, the horizontal offset value of the ground wire must be taken into account.

[0080] Step S5: The height of the ground wire support is generally controlled by the ground wire corona; calculate the maximum electric field strength E on the surface of different ground wires m and the corona critical electric field strength E0, calculate the minimum ground wire support height;

[0081] Specifically, according to the "1000kV Overhead Transmission Line Design Specifications": In addition to meeting the short-circuit current thermal power requirements, the ground wire (including OPGW) should be calibrated according to the corona initiation conditions. The ratio of the maximum surface field strength of the AC line ground wire to the corona critical electric field strength should not be greater than 0.8; the ground wire is in the strong electric field environment of the conductor. Excessive field strength on the ground wire surface will cause comprehensive corona of the ground wire, which will not only increase the corona loss sharply, but also bring many other problems; therefore, a reasonable ground wire bracket height must be obtained in conjunction with the conductor.

[0082] According to the phase spacing, ice area, altitude, and multiple combinations of ground wire models, the maximum electric field intensity E on the surface of different ground wires is calculated. m And the corona critical electric field strength E0, calculate the minimum ground wire bracket height that meets the requirements.

[0083] Specifically, the maximum electric field strength E on the wire surface m The calculation method can be Markt and Mendel method, Successive Images method, Simulator Charges method or Moment Methods method, and its main factors are operating voltage, wire diameter, wire splitting form, etc.; specifically, Markt and Mendel method can only calculate four splits and below.

[0084] Calculate the corona critical electric field strength E0, specifically:

[0085]

[0086] Among them, E0 is the critical electric field strength of wire corona;

[0087] m is the conductor surface coefficient;

[0088] σ is the relative air density;

[0089] r is the wire radius;

[0090] p is the air pressure;

[0091] t is the temperature.

[0092] Step S6: According to the protection angle of the ground wire to the conductor and the combination of the horizontal displacement of the ground wire, select the minimum ground wire bracket height that meets the requirements.

[0093] Specifically, according to the Technical Regulations for the Design of Overhead Transmission Lines in Heavy Ice Conditions (DL / T 5440-2020), "a negative protection angle should be adopted for the ground wire on the tower to the conductor, which should not be greater than -4° in mountainous areas."

[0094] Based on the protection angle of the ground wire to the conductor and multiple combinations of the horizontal displacement of the ground wire, the minimum ground wire bracket height that meets the requirements is calculated.

[0095] Step S7: Determine the distance between the center conductor of the span and the ground wire.

[0096] According to the "Electrical Design Code for Overhead Transmission Lines" (DL / T 5582-2020), the distance between the two ground wires on a 1000kV line tower should not exceed 5 times the vertical distance between the ground wire and the conductor; preferably, the distance between the central conductor of the span and the ground wire is determined by numerical calculation.

[0097] The present invention is not limited to the above-mentioned specific embodiments, but extends to any new features or any new combination disclosed in this specification, as well as any new method or process steps or any new combination disclosed.

Claims

1. A tower head design and configuration method for realizing high-altitude heavy ice areas, characterized in that: The specific steps include: Step S1: Select the minimum tower head size according to the electrical clearance control; Step S2: Calculate the phase spacing according to the electromagnetic environment requirements, and make the phase spacing tend to be minimum when meeting the audible noise and radio interference limits; Step S3: Determine the distance between the horizontally arranged conductors so that the phase spacing of the tower head is not less than the value of the distance between the horizontally arranged conductors; Step S4: Under de-icing conditions, determine the height of the ground wire support; Step S5: Calculate the maximum electric field strength E on the surface of different ground wires m and the corona critical electric field strength E0, calculate the minimum ground wire support height; Step S6: Select the minimum ground wire support height that meets the requirements; Step S7: Determine the distance between the center conductor of the span and the ground wire.

2. A tower head design and configuration method for achieving high-altitude heavy ice areas according to claim 1, characterized in that: The step S2 specifically refers to: calculating the electromagnetic environment of the maximum electric field strength on the conductor surface, radio interference, audible noise, and the ratio of the maximum electric field strength on the conductor surface to the corona critical electric field strength through multiple combinations of the tower head phase spacing and the conductor ground distance, and obtaining the value of the phase spacing; and making the value tend to be minimum when meeting the audible noise and radio interference limits.

3. A tower head design and configuration method for achieving high-altitude heavy ice areas according to claim 2, characterized in that: The calculation method of the audible noise in step S2 is: L w.i =-177.6+120lg(g maxi )+26.4lg(n)+55lg(d); Among them, g maxi is the effective value of the maximum potential gradient on the conductor surface; d is the wire diameter; n is the number of wire splits; L w.i is the A-weighted sound power level of the audible noise per unit length of the i-th phase conductor.

4. A tower head design and configuration method for achieving high altitude heavy ice areas according to claim 3, characterized in that: The radio interference calculation method in step S2 is: Γ=55-576.5 / g maxi +42.4lg(2r)-0.714lg(n); Where, Γ is the excitation function; n is the number of wire splits, the valid range is 4 to 12; r is the wire radius, and the effective range is 2.4cm to 4cm.

5. The tower head design and configuration method for realizing high-altitude heavy ice areas according to claim 1 is characterized in that: In step S5, the maximum electric field strength E of different ground lines is calculated. m Specifically, it means: using Markt and Mendel method, Successive Images method, Simulator Charges method or Moment Methods method to calculate the maximum electric field strength E on the surface of different ground wires m .

6. A tower head design and configuration method for achieving high altitude heavy ice areas according to claim 5, characterized in that: The calculation of the corona critical electric field strength E0 in step S5 specifically refers to: Among them, E0 is the critical electric field strength of wire corona; m is the conductor surface coefficient; σ is the relative air density; r is the wire radius; p is the air pressure; t is the temperature.

7. The tower head design and configuration method for realizing high-altitude heavy ice areas according to claim 1 is characterized in that: The step S4 specifically includes: Select typical tension sections in typical ice areas for modeling; Perform de-ice jump calculations; According to the de-icing jump calculation results, the height of the ground wire bracket is determined when the static approach distance and dynamic approach distance are met and the horizontal offset value of the ground wire is taken into account.

8. A tower head design and configuration method for achieving high altitude heavy ice areas according to claim 6, characterized in that: According to the protection angle of the ground wire to the conductor and the horizontal displacement of the ground wire, select the minimum ground wire bracket height that meets the requirements.

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