Power transmission line anti-icing and ice-melting checking and evaluating method

Abstract

The invention relates to an anti-icing and ice-melting checking and evaluating method for a power transmission line. The method comprises the following steps: collecting power transmission line information according to anti-icing and ice-melting troubleshooting key points and technical routes; according to the collected power transmission line information, anti-icing performance evaluation and ice melting condition checking are carried out; and finally formulating a special ice melting scheme for the power transmission line according to an evaluation result and a checking result. Wherein the anti-icing performance evaluation comprises anti-icing flashover performance verification and icing load analysis, and the line ice melting condition verification comprises two parts of power transmission professional verification and power transformation professional verification. According to the invention, line anti-icing and ice-melting short plates can be found in time, the line anti-icing and ice-melting capabilities are improved in a targeted manner, and safe and stable operation of the power transmission line is ensured.

Description

Technical Field

[0001] The invention belongs to the technical field of power grid operation assessment, and in particular to a method for evaluating anti-icing and ice-melting verification of power transmission lines. Background Art

[0002] In recent years, as the zero-degree line moves northward, the temporal and spatial distribution of rain, snow and freezing disasters has changed significantly, becoming one of the important factors affecting the safe operation of the power grid. It is necessary to further enhance the ability of transmission lines to resist rain, snow and freezing disasters, carry out anti-icing and ice-melting verification of transmission lines, formulate a plan for ice-melting, improve the reliability of the power grid under extreme weather conditions, and ensure power supply safety. Summary of the invention

[0003] The purpose of the present invention is to overcome the shortcomings of the prior art and propose a method for checking and evaluating the anti-icing and ice-melting of power transmission lines, which can timely discover the shortcomings of the anti-icing and ice-melting of the lines, improve the anti-icing and ice-melting capabilities of the lines in a targeted manner, and ensure the safe and stable operation of the transmission lines.

[0004] The present invention solves the technical problem by adopting the following technical solutions:

[0005] A method for evaluating anti-icing and ice-melting of a power transmission line comprises the following steps:

[0006] Step 1: Collect transmission line information based on anti-icing and ice-melting inspection priorities and technical routes;

[0007] Step 2: Perform anti-icing performance evaluation based on the transmission line information collected in step 1;

[0008] Step 3: Check ice melting conditions based on the transmission line information collected in step 1;

[0009] Step 4: Develop a special plan for ice melting on transmission lines based on the evaluation results of steps 2 and 3.

[0010] Moreover, the anti-icing performance evaluation in step 2 includes anti-icing flash performance verification and ice load analysis.

[0011] Moreover, the anti-ice flash performance test measures the anti-ice flash performance of the insulator string by calculating the average potential gradient:

[0012]

[0013] Among them, E is the average potential gradient of the insulator string; U is the nominal phase voltage of the line; L is the structural height of the insulator string.

[0014] Furthermore, the ice load analysis verifies whether the stress conditions of the conductor under different ice thicknesses meet the requirements by calculating the percentage of the conductor's lowest point tension to the breaking force and the percentage of the conductor's longitudinal unbalanced tension.

[0015] Moreover, the ice melting condition verification in step 3 includes power transmission professional verification and power transformation professional verification.

[0016] Furthermore, the power transmission professional verification includes station entry method inspection and ice melting current calculation.

[0017] Moreover, the specific implementation method of the entry method is as follows: if it is a cable entry, check the distance between the terminal tower and the substation; obtain the conductor model, line length, calculate the total line resistance, select the ice melting method, calculate the ice melting current and select the ice melting voltage.

[0018] Moreover, the ice melting current calculation method is:

[0019] Rectification components are connected in series internally, and ice melting is done in a single-way and single-way manner:

[0020] I=2U*1.25 / 2R

[0021] Rectification components are connected in series internally, and ice melting mode is single-way and double-way:

[0022] I=2U*1.25 / 1.5R

[0023] Rectification components are connected in parallel internally, and ice melting is done in single-way and single-way mode:

[0024] I=U*1.25 / 2R

[0025] Rectification components are connected in parallel internally, and ice melting mode is single-way and double-circuit:

[0026] I=U*1.25 / 1.5R

[0027] Among them, U is the AC output voltage of the ice-melting vehicle, I is the DC output current of the ice-melting vehicle, and R is the resistance of the ice-melting line.

[0028] Moreover, the professional verification of substation includes verification of in-station infrastructure and in-station electrical facilities.

[0029] The advantages and positive effects of the present invention are:

[0030] The present invention collects transmission line information based on the key points and technical routes of anti-icing and ice-melting inspections; and based on the collected transmission line information, performs anti-icing performance evaluation and ice-melting condition verification; and finally formulates a special plan for transmission line ice melting based on the evaluation results and verification results. Among them, the anti-icing performance evaluation includes anti-icing flash performance verification and ice load analysis, and the line ice-melting condition verification includes two parts: power transmission professional verification and substation professional verification. The present invention can timely discover the shortcomings of line anti-icing and ice-melting, improve the line anti-icing and ice-melting capabilities in a targeted manner, and ensure the safe and stable operation of the transmission line. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 This is a schematic diagram of the power transformation professional verification of the present invention. DETAILED DESCRIPTION

[0032] The present invention is further described in detail below with reference to the accompanying drawings.

[0033] A method for evaluating anti-icing and ice-melting of a power transmission line comprises the following steps:

[0034] Step 1: Collect transmission line information based on anti-icing and ice-melting inspection priorities and technical routes.

[0035] Step 2: Perform anti-icing performance evaluation based on the transmission line information collected in step 1. The anti-icing performance evaluation includes anti-icing flash performance verification and ice load analysis.

[0036] The ice flash protection performance check measures the ice flash protection performance of the insulator string by calculating the average potential gradient:

[0037]

[0038] Among them, E is the average potential gradient of the insulator string; U is the nominal phase voltage of the line; L is the structural height of the insulator string.

[0039] To ensure the anti-ice flashover performance of the insulator string under different pollution levels, the average potential gradient of the insulator string should not be higher than that shown in Table 1. If it is higher than the upper limit of the average potential gradient, the anti-ice flashover performance is unqualified.

[0040] Table 1 Upper limit of average potential gradient for ice flash protection of insulator string

[0041]

[0042] The ice load analysis verifies whether the stress conditions of the conductor under different ice thicknesses meet the requirements by calculating the percentage of the conductor's lowest point tension to the breaking force and the percentage of the conductor's longitudinal unbalanced tension.

[0043] On the one hand, when there is a rare wind speed or rare icing weather conditions, the maximum tension at the lowest point of the sag should not exceed 70% of the breaking force of the conductor and ground wire.

[0044] On the other hand, the value of the conductor and ground wire breaking tension (or longitudinal unbalanced tension of split conductors) in ice areas of 10mm or less should comply with the percentage of the maximum use tension of the conductor and ground wire specified in Table 2. The ice level of the UHV lines in Tianjin is 0-5mm, the terrain is flat hills, the lines are 8 splits, the longitudinal unbalanced tension of the straight tower conductor cannot exceed 20% of the maximum tension, and the longitudinal unbalanced tension of the tension tower conductor cannot exceed 70% of the maximum tension.

[0045] Table 210mm and below ice area conductor and ground wire break tension (or split conductor longitudinal unbalanced tension) (%)

[0046]

[0047] Step 3: Check the ice melting conditions based on the transmission line information collected in step 1. The ice melting conditions check includes power transmission professional check and substation professional check.

[0048] Power transmission verification includes checking of access methods and calculation of ice-melting current.

[0049] The station entry method (cable, overhead). If the station is entered by cable, check the distance between the terminal tower and the substation.

[0050] Collect conductor model (if marked in sections, including overhead and cable), line length (km) (if marked in sections, including the unit resistance of overhead and cable (Ω / km)), calculate total line resistance, select ice melting method, calculate ice melting current, and select ice melting voltage.

[0051] When selecting different internal wiring methods of rectifier components and different ice melting methods, the calculation formulas for each type are as follows:

[0052] Rectification components are connected in series internally, and ice melting mode is single-way and single-way.

[0053] I=2U*1.25 / 2R

[0054] Rectification components are connected in series internally, and ice melting mode is single-way and double-way.

[0055] I=2U*1.25 / 1.5R

[0056] Rectification components are connected in parallel internally, and ice melting mode is single-way and single-way

[0057] I=U*1.25 / 2R

[0058] Rectification components are connected in parallel internally, and ice melting mode is single-way double-circuit

[0059] I=U*1.25 / 1.5R

[0060] Among them, U is the AC output voltage of the ice-melting vehicle, with a total of six gears to choose from (4010V, 3573V, 3208V, 2479V, 1604V, 1094V); I is the DC output current of the ice-melting vehicle, and R is the resistance of the ice-melting line.

[0061] The calculation method of ice melting current is as follows: According to the maximum and minimum ice melting current I and unit resistance corresponding to different types of conductors:

[0062] 1. Calculate R using the wire length and unit resistance;

[0063] 2. Take the middle value of the maximum and minimum ice-melting currents as I, and substitute it into the first formula to calculate the AC output voltage U of the ice-melting vehicle;

[0064] 3. Select a voltage that is closest to U, and substitute the voltage value into formula 1 to calculate the actual output current value;

[0065] 4. Check whether the current meets the maximum allowable working current of the conductor and the corresponding ice melting current range;

[0066] If it is satisfied, the calculation ends; if it is not satisfied, I take the middle value and substitute it into the second formula and perform subsequent calculations. If it is still not satisfied, substitute it into the third formula... and so on.

[0067] The professional verification of substation includes the infrastructure and electrical facilities within the station.

[0068] like Figure 1 As shown, the infrastructure within the station includes whether there is a parking space for an ice-melting vehicle (the space required for a standard ice-melting vehicle is 4 meters wide and 25 meters long; the space required for a lightweight ice-melting vehicle is 4 meters wide and 15 meters long).

[0069] Whether the access road is suitable for ice-melting vehicles to pass (the dimensions of a standard ice-melting vehicle are: 19 meters long, 2.5 meters wide, and 4 meters high; the dimensions of a lightweight ice-melting vehicle are: 8 meters long, 2.5 meters wide, and 4 meters high;)

[0070] Are there any height-restricted facilities in the station? (If yes, indicate the height restriction)

[0071] The electrical facilities in the station include whether there is an outdoor maintenance power box (used to obtain 380V power supply, no more than 100 meters away from the parking place of the ice-melting vehicle), whether there is 10kV and 35kV power supply (including spare, surplus, capacitor bank, etc.) available for ice-melting device (used to obtain 10kV power supply, no more than 100 meters away from the parking place of the ice-melting vehicle), whether the distance of the power switch required by the corresponding ice-melting device meets the requirements (used to protect signal wiring, no more than 100 meters away from the parking place of the ice-melting vehicle. If it exceeds 100 meters, the distance needs to be noted), and whether there is a place for the placement of the supporting knife switch of the ice-melting device.

[0072] Whether the final output meets the ice melting conditions.

[0073] Step 4: Develop a special plan for ice melting on transmission lines based on the evaluation results of steps 2 and 3.

[0074] It should be emphasized that the embodiments described in the present invention are illustrative rather than restrictive. Therefore, the present invention includes but is not limited to the embodiments described in the specific implementation manner. Any other implementation manners derived by those skilled in the art based on the technical solution of the present invention also fall within the scope of protection of the present invention.

Claims

1. A method for evaluating anti-icing and ice melting of power transmission lines, characterized in that: The following steps are involved: Step 1: Collect transmission line information based on anti-icing and ice-melting inspection priorities and technical routes; Step 2: Perform anti-icing performance evaluation based on the transmission line information collected in step 1; Step 3: Check ice melting conditions based on the transmission line information collected in step 1; Step 4: Develop a special plan for ice melting on transmission lines based on the evaluation results of steps 2 and 3.

2. A power transmission line anti-icing and ice melting verification and evaluation method according to claim 1, characterized in that: The anti-icing performance evaluation in step 2 includes anti-icing flash performance verification and ice load analysis.

3. A power transmission line anti-icing and ice melting verification and evaluation method according to claim 2, characterized in that: The ice flash protection performance test measures the ice flash protection performance of the insulator string by calculating the average potential gradient: Among them, E is the average potential gradient of the insulator string; U is the nominal phase voltage of the line; L is the structural height of the insulator string.

4. A power transmission line anti-icing and ice melting verification and evaluation method according to claim 2, characterized in that: The ice load analysis verifies whether the stress conditions of the conductor under different ice thicknesses meet the requirements by calculating the percentage of the conductor's lowest point tension to the breaking force and the percentage of the conductor's longitudinal unbalanced tension.

5. A power transmission line anti-icing and ice melting verification and evaluation method according to claim 1, characterized in that: The ice melting condition verification in step 3 includes power transmission verification and substation verification.

6. A power transmission line anti-icing and ice melting verification and evaluation method according to claim 5, characterized in that: The power transmission professional verification includes the inspection of the station access method and the calculation of ice melting current.

7. A power transmission line anti-icing and ice melting verification and evaluation method according to claim 6, characterized in that: The specific implementation method of the station entry method is as follows: if it is a cable entering the station, check the distance between the terminal tower and the substation; obtain the conductor model, line length, calculate the total line resistance, select the ice melting method, calculate the ice melting current and select the ice melting voltage.

8. A power transmission line anti-icing and ice melting verification and evaluation method according to claim 6, characterized in that: The ice melting current calculation method is: Rectification components are connected in series internally, and ice melting is done in a single-way and single-way manner: I=2U*1.25 / 2R Rectification components are connected in series internally, and ice melting mode is single-way and double-way: I=2U*1.25 / 1.5R Rectification components are connected in parallel internally, and ice melting is done in single-way and single-way mode: I=U*1.25 / 2R Rectification components are connected in parallel internally, and ice melting mode is single-way and double-circuit: I=U*1.25 / 1.5R Among them, U is the AC output voltage of the ice-melting vehicle, I is the DC output current of the ice-melting vehicle, and R is the resistance of the ice-melting line.

9. A power transmission line anti-icing and ice melting verification and evaluation method according to claim 5, characterized in that: The professional verification of substation includes verification of infrastructure and electrical facilities within the station.

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