CN108205088A - A kind of parallel radio interference of high voltage ac/dc circuit calculates and optimization method - Google Patents

Abstract

The present invention is a radio interference calculation and optimization method for parallel high-voltage AC-DC lines. According to the relevant information of existing actual high-voltage AC-DC parallel transmission lines, including AC line voltage level, number of circuits, DC circuit voltage level, line structure, etc., Establish a two-dimensional hybrid radio interference calculation model; for the input model parameters, when considering the interaction of AC and DC, use the empirical formula method and the excitation function method to calculate the radio interference under the interaction of AC and DC lines, and perform geometric superposition to obtain the transmission line At the same time, through the calculation of mixed radio interference of different line heights and parallel distances, the optimization method of radio interference is obtained by screening. The invention reduces the radio interference intensity of the high-voltage AC-DC parallel transmission line and achieves the purpose of optimizing the electromagnetic environment of the high-voltage AC-DC parallel line.

Description

A Calculation and Optimization Method of Radio Interference in Parallel High Voltage AC and DC Lines

technical field

The invention belongs to the technical field of radio interference environment evaluation of power transmission lines, and in particular relates to a radio interference calculation and optimization method for parallel high-voltage AC and DC lines.

Background technique

With the continuous construction of ultra-high voltage and ultra-high voltage transmission lines in my country, the implementation of projects such as national grid connection of power systems, north-south interconnection, and west-to-east power transmission, the AC-DC parallel transmission pattern of my country's power grid has basically formed. The development of the power grid has made the transmission corridors increasingly scarce, especially in economically developed areas, and the parallel erection of AC and DC lines is inevitable. With the emergence of AC-DC parallel lines, AC-DC hybrid radio interference has attracted more and more attention.

Scholars and research institutions at home and abroad have found that for high-voltage AC-DC parallel lines, the radio interference is different from that of AC lines and DC lines running alone. When AC-DC parallel, the corona discharge of each wire has a certain change. This affects the generation of radio interference, and the radio interference superposition between parallel spaces is obvious, so it is different from the situation when running alone, which makes it difficult to predict mixed radio interference when AC and DC are parallel. At present, the research on radio interference is mainly to study the radios of AC lines and DC lines respectively, and the research on radio interference prediction is mainly to obtain empirical formulas by summarizing the data of corona cage experiments. The Electric Power Research Institute (EPRI), the International Committee on Radio Interference (CISPR), the Quebec Hydropower Research Institute (IREQ), and the International Power Grid (CIGRE) have also successively proposed their own excitation function formulas. The excitation function method also uses the corona cage experiment to obtain the excitation function, and through the calculation of the corona current, analyzes its propagation process, and finally obtains the field strength of the radio interference caused by the corona current. The excitation function method is suitable for four-split and above transmission lines. There are still few researches on the radio interference of DC lines, mainly based on empirical formulas obtained from experiments.

Through the foregoing, the inventors found that although domestic and foreign researches have already been able to calculate the method of AC-DC hybrid radio interference, they are mainly calculated separately. In the calculation process, the influence between the AC line and the DC line is ignored, and then superimposed. This makes the calculation accuracy of radio interference of AC and DC parallel lines lacking, and needs to be improved in these aspects.

With the increasing demand for transmission lines in our country, the research on hybrid radio interference of high-voltage AC-DC parallel lines also needs to be further improved. At this time, it is very necessary to study the hybrid radio interference calculation of high-voltage AC lines and DC lines in parallel.

Contents of the invention

The present invention aims to solve the above problems of the prior art. A hybrid radio interference calculation and optimization method for parallel high-voltage AC-DC lines to reduce radio interference of high-voltage AC-DC parallel lines is proposed. Technical scheme of the present invention is as follows:

A parallel radio interference calculation and optimization method for high-voltage AC and DC lines, comprising the following steps:

a. Establish a two-dimensional hybrid radio interference calculation model based on the relevant information of the existing actual high-voltage AC-DC parallel transmission lines, including the voltage level of the AC line, the number of circuits, the voltage level of the DC circuit, and the line structure;

b. For the hybrid radio interference calculation model established in step a, input the model parameters such as the voltage level of the AC line and the DC line, the line height, the parallel spacing, the number of split wires, and the radius of the split wires, taking into account the interaction between the AC line and the DC line Under the influence of DC, the empirical formula method is used to calculate the radio interference of the AC line under the influence of DC when the split number is less than 4 and the excitation function method is used to calculate the radio interference of the AC line under the influence of DC when the split number is greater than 4, and the empirical formula method is used to calculate the radio interference of the DC line radio interference. And carry out geometric superposition to obtain the mixed radio interference value of the transmission line, at the same time, calculate the mixed radio interference of different line heights and parallel distances;

c. In the calculation process of step b, compare and analyze the height, separation distance, and mixed radio interference of different high-voltage AC and DC lines, so as to obtain an optimization method for reducing the radio interference intensity of high-voltage AC-DC parallel transmission lines, and achieve the optimization of high-voltage AC-DC The purpose of parallel line electromagnetic environment is to provide reference for the reconstruction of current transmission lines.

Further, in the step a) the relevant information of the actual high-voltage AC-DC parallel transmission line specifically includes: AC transmission line voltage level, DC transmission line voltage level, wire splitting distance, wire splitting number, sub-conductor radius, phase sequence arrangement, pitch The line height of the ground and the parallel spacing of the AC and DC lines.

Further, the empirical formula and activation function of the step b) are as follows:

1) When the number of splits of the AC conductor is less than or equal to 4, use the empirical formula method to calculate

The formula recommended by the International Special Committee on Radio Interference is adopted

In the formula, E represents the radio interference field strength, dB(μV/m); r—the radius of the conductor, cm; D—the distance between the observation point and a certain phase transmission line, m; g _max —the maximum potential gradient on the surface of the conductor, kV/cm , this formula calculates the radio interference value with 50% time probability in good weather, and the double 80%//80% value can be increased by 6~10dB(uV/m);

2) When the AC conductor splitting number is greater than 4, use the excitation function method to calculate

The excitation function under the heavy rain condition proposed by the American Electric Power Research Institute is specifically:

Γ＝70-585/g _max +35lgd-10lgn

In the formula, g _max is the effective value of the maximum potential gradient on the surface of the wire, kV/cm; d is the diameter of the sub-wire, cm; n represents the number of split wires;

3) DC radio interference calculation formula

Formula for calculating radio interference values in bipolar DC transmission lines:

E _dc is the calculated radio interference value, dB, g _max is the maximum potential gradient kV/cm on the surface of the wire; r is the radius of the sub-wire, cm; n is the number of split wires; D is the distance between the calculation point and the positive wire, m; ΔE _w is the meteorological correction item, with an altitude of 500m as the benchmark, an increase of 3.3dB per 1000m; ΔE _f is the interference frequency correction item, ΔE _f =5(1-2(lg(10f)) ² ); f is the required Calculated frequency, MHz.

Further, the calculation of the mixed radio interference value of the transmission line in the step b) specifically includes the following steps:

1) First, put the AC line and the DC line in the same system, and use the simulated charge method to calculate the surface field strength of each wire;

2) Determine the number of splits of the AC wires. If the number of AC wires is less than or equal to 4, use the AC empirical formula to calculate. If the number of splits is greater than 4, use the excitation function method to calculate the radio interference value on the AC side. At the same time, according to the standard Corrected for radio interference values on sunny days;

3) The DC side is calculated using the DC radio interference empirical formula to obtain the radio interference value in sunny days;

4) Geometrically superpose the AC radio interference value and the DC radio interference value at the same point below the line to obtain the mixed radio interference value in sunny days.

Further, obtaining the line height and parallel spacing when meeting the mixed radio interference environment evaluation standard is specifically: when the minimum mixed radio interference intensity is selected, the corresponding AC and DC line height and parallel spacing.

Further, the height of the line needs to be changed within the relevant line construction standard interval, and the parallel distance is found between 60m-120m.

Further, the method of using geometric superposition specifically includes:

The total interference level is obtained by adding the same-frequency interference generated by the AC line and the DC line according to the sum of squares:

The electric field unit of the above formula is μV/m. If the unit is dB(μV/m), it can be synthesized by the following formula:

In the formula, E is the hybrid radio interference field strength, E _ac is the radio interference field strength of the AC line considering the influence of DC, and E _dc is the radio interference field strength of the DC line considering the influence of the branch circuit.

A hybrid radio interference calculation and optimization method system based on the method for high-voltage AC lines and DC lines in parallel, the system includes:

A calculation model building unit, used for the relevant information of the high-voltage AC-DC parallel line, and constructing a calculation model according to the determined relevant information;

Line height and parallel spacing screening unit, for different line heights and parallel spacing of transmission lines, use the empirical formula of radio interference or excitation function method to calculate, and superimpose, to obtain the mixed radio interference corresponding to different line heights and parallel spacing, and in Among the mixed radio interference corresponding to different line heights and parallel spacings obtained, the mixed radio interference intensity and the corresponding line height and parallel spacing satisfying certain conditions are selected;

The line height and parallel spacing revision unit is used to obtain the line height and parallel spacing when meeting the mixed radio interference environmental evaluation standards, and provide reference for the reconstruction of current transmission lines.

Advantage of the present invention and beneficial effect are as follows:

In the embodiment of the present invention, due to the calculation of the above scheme for each type of line height and parallel spacing, the mixed radio interference that meets certain conditions and the corresponding line heights and parallel spacing are screened out, thereby reducing the high-voltage AC/DC parallel lines. Radio interference, to achieve the purpose of optimizing the mixed radio interference field strength of AC and DC parallel lines.

Description of drawings

Fig. 1 is an overall implementation process diagram of a high-voltage AC/DC line parallel radio interference calculation and optimization method provided by a preferred embodiment of the present invention;

Fig. 2 is a calculation flowchart of a parallel radio interference calculation and optimization method for high-voltage AC and DC lines provided by an embodiment of the present invention;

Fig. 3 is a schematic diagram of measurement points and wire positions of a parallel radio interference calculation and optimization method for high-voltage AC and DC lines provided by an embodiment of the present invention;

Fig. 4 is a schematic diagram of a distributed circuit for corona current propagation in a high-voltage AC/DC line parallel radio interference calculation and optimization method provided by an embodiment of the present invention

FIG. 5 is a calculation system diagram of a high-voltage AC-DC line parallel radio interference calculation and optimization method provided by an embodiment of the present invention.

Detailed ways

The technical solutions in the embodiments of the present invention will be described clearly and in detail below with reference to the drawings in the embodiments of the present invention. The described embodiments are only some of the embodiments of the invention.

The technical scheme that the present invention solves the problems of the technologies described above is:

As shown in Figure 1, it is a diagram of the overall implementation process of a high-voltage AC-DC line parallel radio interference calculation and optimization method:

Step 1. Determine the relevant information of the high-voltage AC-DC parallel transmission line, and construct a two-dimensional hybrid radio interference calculation model based on the relevant information.

The specific process is to determine the relevant information of the high-voltage AC-DC parallel transmission line, including the voltage level of the AC transmission line, the voltage level of the DC transmission line, the distance between the conductor splits, the number of conductor splits, the radius of the sub-conductors, the phase sequence arrangement, the height of the line from the ground, and Parallel spacing of AC and DC lines.

Step 2. For the voltage level of the corresponding high-voltage AC-DC transmission circuit, the distance between the AC line and the DC line, the calculation model is solved by using the meshless method, and the mixed radio interference field strength when the high-voltage AC-DC parallel is obtained, and changed Line height and parallel spacing. Calculated using the above method.

The specific process is that the calculation of the radio interference is divided into calculating the maximum potential gradient of the wire surface under mutual influence in the same system, and then using the calculation formulas of the AC line and the DC line to calculate respectively, and then superimposing. As for changing the line height and parallel spacing, the line height needs to be changed within the relevant line construction standard range, and the parallel distance needs to be found between 60m-120m.

Step 3. Obtain the line height and parallel spacing when meeting the mixed electric field environmental evaluation standard, and provide reference for the reconstruction of the current transmission line.

The specific process is that the acquisition of the line height and parallel spacing when meeting the mixed radio interference environment evaluation standard is: screening out the minimum mixed radio interference intensity and its corresponding AC and DC line height and parallel spacing.

In the embodiment of the present invention, the main calculation of the present invention is specifically as follows:

I Calculation of Maximum Surface Potential Gradient of AC and DC Parallel Lines

The electric field intensity on the surface of the conductor of the transmission line is the decisive factor for the occurrence of corona discharge on the line. Therefore, the calculation of the surface electric field strength and the inception field strength of the transmission line conductor is a necessary calculation before calculating the radio interference of the line.

Using the simulated charge method to calculate the maximum potential gradient on the surface of AC and DC parallel lines in the same system, the specific calculation steps are as follows:

a) Input line data, including transmission line voltage level, wire split radius, number of wire splits, sub-wire radius, and position coordinates of each wire. Calculate the equivalent radius of each wire,

Where Ri is the equivalent radius of the i-th wire, m, R is the radius of the split wire, m, n is the number of splits, and r is the radius of the secondary wire, m.

b) Calculate the charge Q on each wire by the potential coefficient method

In the formula, P _ii is the self-potential coefficient, and P _ij is the potential value generated by the analog charge of the j-th wire on the matching point of the i-th wire, which is called the potential coefficient. Potential coefficient through Calculate, where h _i is the height of the i-th wire to the ground, R _i is the equivalent radius of the wire, L _ij is the distance from the i-th wire to the j-th wire, and L' _ij is the mirror image from the i-th wire to the j-th wire wire distance. Qn is the analog charge of the nth wire, is the potential of the nth wire. ε ₀ is the dielectric constant of vacuum.

c) Calculate the maximum electric field intensity on the wire surface

Where g _max is the maximum electric field intensity on the surface of the wire, kV/cm, Q is the simulated charge of the wire, _ε0 is the vacuum dielectric constant, r is the radius of the secondary wire, cm, N is the number of wire splits, and R is the equivalent radius of the wire , cm. II Calculation of Radio Interference on AC Lines Considering DC Effects

Through the calculation of the maximum surface potential gradient of the AC and DC parallel lines in I, the maximum surface potential gradient of the conductors of the AC line and the DC line in the same system is obtained.

For the calculation method of transmission line radio interference, when the splitting number of the wire changes, the calculation method of the radio interference value will be different, there are two main methods: empirical formula method and excitation function method. The empirical formula is derived from the measurement results when the conductor splitting number is 1-4, the operating voltage is 200-750kV, and the surface field strength of the conductor is 12-20kV/cm. Generally, it is only suitable for calculating the radio interference of high-voltage transmission lines with the number of conductor splits not greater than 4. When the number of split wires is greater than 4, the excitation function method is usually used for calculation.

For radio interference generated by AC wires, the calculation procedure is as follows:

a) When the number of splits of the AC conductor is less than or equal to 4, use the empirical formula method to calculate

To calculate the field strength of 0.5MHz radio interference generated by each phase of the three-phase conductor of a single-circuit AC overhead line at a certain point, the power industry standard in my country adopts the formula recommended by the International Special Committee on Radio Interference (CISPR)

In the formula, E represents the radio interference field strength, dB(μV/m); r—the radius of the conductor, cm; D—the distance between the observation point and a certain phase transmission line, m; g _max —the maximum potential gradient on the surface of the conductor, kV/cm . What this formula calculates is the radio interference value of 50% time probability under good weather, for double 80%//80% value can be increased by 6～10dB (uV/m) by this value.

b) When the wire splitting number is greater than 4, use the excitation function method for calculation

The excitation function method is to obtain the excitation function through the corona cage test under heavy rain conditions, determine the corona pulse current in the wire, and then calculate the interference field strength level according to the current. The excitation function method is suitable for AC overhead lines with single circuit, multiple circuits, and any number of splits, and is an ideal method for calculating radio interference.

The excitation function under heavy rain conditions proposed by the Electric Power Research Institute (EPRI) is a more appropriate excitation function, specifically:

Γ＝70-585/g _max +35lgd-10lgn\*MERGEFORMAT(5)

In the formula, g _max is the effective value of the maximum potential gradient on the surface of the wire, kV/cm; d is the diameter of the sub-wire, cm; n represents the number of split wires. The national standard also stipulates that according to the Γ value under heavy rain, the excitation function of light rain and good weather can be obtained, and the specific relationship is:

Γlight _rain ＝Γheavy _rain +δ ₀ +δ _c \*MERGEFORMAT(6)

_{Γgood weather} =Γheavy _rain -17\*MERGEFORMAT(7)

Where δ ₀ and δ _c are correction values when calculating the excitation function under light rain conditions, which can be determined from the correction curve in the standard.

When the wire corona occurs, the corona current will flow through itself, and the current will also be induced on the other phase wires. The corona current on the three-phase line can be obtained by the excitation function, as shown in formula (1)

In the formula: I is the current matrix of the transmission line, and the off-diagonal elements reflect the current coupling between phases; C is the capacitance matrix per unit length of the transmission line, _ε0 is the vacuum dielectric constant; Γ is the excitation function matrix of the transmission line.

An overhead conductor can be represented by a unit length series distributed impedance Z and a unit length parallel distributed admittance Y. For the current cell shown in Figure 4, there are the following relationships (v, i, x, respectively, along the line voltage, current, line length):

From the formula, the second order differential equation can be obtained:

The formula is the characteristic equation of current propagation along the line.

For the three-phase line, you can directly replace the i in the formula with the three-phase current vector, and replace Y and Z with the corresponding matrix, and the result is still valid. Multiply both sides of the formula by a phase-mode conversion matrix to make the original differential equations into three independent differential equations, and the problem can be easily solved.

If input λ ² is a diagonal matrix generated by the eigenvalues of matrix YZ, and S is the corresponding eigenvector matrix, then λ ² =S ^-1 YZS, write i ^(m) = S ^-1 i, get (7 ) multiply both sides of the formula by S ^-1 , and get

Substituting the current calculated by the formula into i ₀ ^(m) = S ^-1 i, combined with the boundary conditions, the solution of the formula can be obtained

The phase-mode inverse transformation is performed on the solution of the formula, and the corona current propagation formula can be obtained as:

i＝Si ^(m) \*MERGEFORMAT(14)

After calculating the corona current propagating on the line, the next step is to calculate the interference field strength. As mentioned earlier, radio interference is mainly the electromagnetic field formed in the surrounding space when high-frequency corona current flows on the transmission line. The height of the current-carrying conductor is square, and the magnetic field intensity H and the current i generated at the measuring point (as shown in Figure 3) with the height of h ₁ and the horizontal coordinate of y satisfy

The electric field strength and magnetic field strength satisfy

In the formula: ε ₀ is the vacuum permittivity; μ ₀ is the magnetic permeability of air.

Therefore, the radio interference intensity caused by the corona current microelement of the i-th phase wire is:

In the formula: i _ji (x) is the corona current generated by the i-phase conductor; z _j and y _i are the height and horizontal coordinates of the j-th phase conductor respectively;

Assuming that the entire wire is uniformly corona, the radio interference field strength at the measuring point is integrated according to formula (18):

The above model can be used to calculate the radio interference level of each phase wire during corona, and synthesize it according to the national standard to obtain the total radio interference generated by the AC line.

III Calculation of Radio Interference of DC Lines Considering AC Influence

The maximum potential gradient on the surface of the DC line considering the AC influence is calculated in step 1.

Calculated using the formula recommended by CISPR.

In 1982, CISPR deduced the formula for calculating the radio interference value in bipolar direct current transmission lines:

E _dc is the calculated DC radio interference value, dB. g _max is the maximum potential gradient kV/cm on the surface of the conductor; r is the radius of the sub-conductor, cm; n is the number of split conductors; _D is the distance between the calculation point and the positive conductor, m; As a benchmark, increase 3.3dB every 1000m; ΔE _f is the interference frequency correction item, ΔE _f =5(1-2(lg(10f)) ² ); f is the frequency to be calculated, MHz.

IV Computation of Hybrid Radio Interference

Radio interference from superimposed AC and DC lines.

After calculating the radio interference of the AC and DC lines separately, they are synthesized as follows. The synthesis principle is to try to ensure that the synthesized interference value is the same as the measured value using the CISPR standard interference measuring instrument, that is, the characteristics of the peak detector should be considered. Therefore, the method of geometric superposition is adopted here.

This method can be considered that the radio interference generated by the AC and DC lines is random, and the relationship coefficient between the two is zero. The total interference level is obtained by adding the same frequency interference generated by the AC line and the DC line by the sum of squares:

The unit of the electric field in the above formula is μV/m. If the unit is dB (μV/m), it can be synthesized by the following formula:

In the formula, E is the hybrid radio interference field strength, E _ac is the radio interference field strength of the AC line considering the influence of DC, and E _dc is the radio interference field strength of the DC line considering the influence of the branch circuit.

Step 3. Obtain the line height and parallel spacing when meeting the mixed electric field environmental evaluation standard, and provide reference for the reconstruction of the current transmission line.

The specific process is to repeatedly apply the calculation method to calculate the mixed radio interference by changing the line height and parallel spacing in step 2, and obtain the line height and line parallel spacing corresponding to the smaller mixed radio interference, so as to provide a reference for the reconstruction of transmission lines the goal of.

As shown in Figure 4, it is a high-voltage AC/DC line parallel radio interference calculation and optimization method system provided in an embodiment of the present invention, the system includes:

Calculation model construction unit 210, used for relevant information of high-voltage AC/DC parallel lines, and constructing a calculation model according to the determined relevant information;

The line height and parallel spacing screening unit 220, for different line heights and parallel spacing of the transmission line, uses the empirical formula of radio interference or the excitation function method to calculate, and superimposes, to obtain the mixed radio interference corresponding to different line heights and parallel spacing, and In the mixed radio interference corresponding to the obtained different line heights and parallel spacings, the mixed radio interference intensity and the corresponding line heights and parallel spacings satisfying certain conditions are selected;

The line height and parallel spacing revision unit 230 is used to obtain the line height and parallel spacing when meeting the mixed radio interference environment evaluation standard, so as to provide reference for the reconstruction of current transmission lines.

It is worth noting that in the above system embodiments, the system units included are only divided according to functional logic, but are not limited to the above division, as long as the corresponding functions can be realized; in addition, the specific functions of each functional unit The names are only for the convenience of distinguishing each other, and are not used to limit the protection scope of the present invention.

Those of ordinary skill in the art can understand that all or part of the steps in the method of the above-mentioned embodiments can be completed by instructing related hardware through a program, and the program can be stored in a computer-readable storage medium, and the storage Media such as ROM/RAM, magnetic disk, optical disk, etc.

The above embodiments should be understood as only for illustrating the present invention but not for limiting the protection scope of the present invention. After reading the contents of the present invention, skilled persons can make various changes or modifications to the present invention, and these equivalent changes and modifications also fall within the scope defined by the claims of the present invention.

Claims (8)

1. a kind of parallel radio interference of high voltage ac/dc circuit calculates and optimization method, which is characterized in that including following step Suddenly：

A, according to the relevant information of existing actual high-voltage AC/DC parallel powerline, including AC line voltage grade, circuit Number, DC circuit voltage grade and line construction establish the hybrid radio interference calculation model of two dimension；

B, voltage of the hybrid radio interference calculation model established for step a, input AC circuit and DC line etc. Grade, line levels, and line space, split conductor number, the model parameter including split conductor radius consider alternating current circuit and direct current It is wireless under the influence of direct current when calculating exchange conducting wire division number less than 4 using empirical formula method under the influence of circuit is mutual Electrical interference and the radio interference that alternating current circuit when division number is more than 4 under the influence of direct current is calculated using excitation function method, are used in combination Empirical formula method calculates the radio interference of DC line, and carries out geometric superposition and obtain the hybrid wireless electrical interference of transmission line of electricity Value, at the same time, to different line levels and the simultaneously hybrid radio interference calculation of row distance；

C, in the calculating process of step b, the height of comparative analysis difference high voltage ac/dc circuit, spacing distance, hybrid wireless Electrical interference size so as to obtain the optimization method for the radio interference intensity for reducing high voltage ac/dc parallel powerline, reaches Optimize the purpose of high voltage ac/dc parallel line electromagnetic environment, the reconstruction for current transmission line of electricity provides reference.

2. the parallel hybrid radio interference calculation of high voltage ac/dc circuit according to claim 1 and optimization method, It is characterized in that, the relevant information of step a) the actual high-voltage AC/DC parallel powerlines is specially：Transmission line of alternation current electricity Grade, DC power transmission line voltage class, conducting wire division spacing, conducting wire division number, sub-conductor radius, phase sequence is pressed to arrange, away from ground Line levels and ac and dc circuit and line space.

3. the parallel hybrid radio interference calculation of high voltage ac/dc circuit according to claim 1 and optimization method, It is characterized in that, the step b) empirical equations and excitation function are as follows：

1) it when the division number for exchanging conducting wire is less than or equal to 4, is calculated using empirical formula method

Using International Special Committee on Radio Interference recommended formula

E represents radio interference field strength, dB (μ V/m) in formula；R-wire radius, cm；D-observation point is away from a certain phase power transmission line Distance, m；g_max- conductive line surfaces maximum potential gradient, kV/cm, what which calculated is the wireless of 50% time probability under fair weather Electrical interference value can increase by 6~10dB (uV/m) for double 80% // 80% values by the value；

2) it when exchanging conducting wire division number more than 4, is calculated using excitation function method

EPRI-Electric Power Research Institute propose heavy rain situation under excitation function be specially：

Γ=70-585/g_max+35lgd-10lgn

In formula, g_maxFor the maximum potential gradient virtual value of conductive line surfaces, kV/cm；D be sub-conductor diameter, cm；N represents that division is led Line number；

3) direct current radio interference calculates formula

The formula of radio interference value is calculated in bipolar direct current transmission line：

E_dcFor the radio interference value calculated, dB, g_maxMaximum potential gradient kV/cm for conductive line surfaces；R is sub-conductor half Diameter, cm；N is split conductor radical；D is to calculate distance of the point away from positive conductor, m；ΔE_wFor meteorological correction item, using height above sea level 500m as Benchmark increases 3.3dB per 1000m；ΔE_fFor interfering frequency correction term, Δ E_f=5 (1-2 (lg (10f))²)；F is required calculating Frequency, MHz.

4. the parallel radio interference of high voltage ac/dc circuit according to claim 3 calculates and optimization method, feature Be, in the step b) calculating of the hybrid radio interference value of transmission line of electricity specifically include following steps：

1) surface of each conducting wire is calculated using Analogue charge method in same system first by alternating current circuit and DC line Field strength；

2) division number of exchange conducting wire is determined, if exchange number of lead wires is less than or equal to 4, formula is counted using exchanging experience It calculates, if division number is more than 4, is calculated using excitation function method, obtain the radio interference value of exchange side, while basis Standard is modified to the radio interference value under fine day；

3) DC side is calculated using direct current radio interference empirical equation, obtains the radio interference value under fine day；

4) the exchange radio interference value at point same below circuit and direct current radio interference value are subjected to geometric superposition, obtained To hybrid radio interference value during fine day.

5. the parallel hybrid radio interference calculation of high voltage ac/dc circuit according to claim 3 and optimization method, It is characterized in that, obtains line levels when meeting hybrid radio interference environment evaluation criterion and simultaneously line space is specially：Screening When going out minimum hybrid radio interference strength, corresponding ac and dc circuit height and simultaneously line space.

6. the parallel hybrid radio interference calculation of high voltage ac/dc circuit according to claim 5 and optimization method, It is characterized in that, the line levels needs change, and row distance is between 60m-120m in line related construction criteria section It finds.

7. the parallel hybrid radio interference calculation of high voltage ac/dc circuit according to claim 3 and optimization method, It is characterized in that, it is described to be specifically included by the way of geometric superposition：

Alternating current circuit with the same frequency that DC line generates is interfered and is added to obtain total interference level by quadratic sum：

The electric field unit of above formula is μ V/m, if unit is dB, (μ V/m) can be synthesized with following formula：

In formula, E be hybrid radio interference field strength, E_acThe alternating current circuit radio interference field strength influenced to consider direct current, E_dcFor The DC line radio interference field strength of branches affect is in consideration.

8. the parallel hybrid wireless electrical interference meter of a kind of high-voltage alternating circuit and DC line based on claim 7 the method Calculation and optimization method system, the system comprises：

Computation model construction unit, for the relevant information of high voltage ac/dc parallel line, and according to the determining related letter Breath structure computation model；

Line levels and simultaneously line space screening unit, simultaneously different line levels for transmission line of electricity and line space, utilize nothing The empirical equation or excitation function method of line electrical interference are calculated, and be superimposed, and obtain different line levels and simultaneously line space corresponds to Hybrid wireless electrical interference, and in the obtained different line levels and the simultaneously corresponding hybrid wireless electrical interference of line space, Filter out the hybrid radio interference strength for meeting certain condition and its corresponding line levels and simultaneously line space；

Line levels and simultaneously line space revision unit, circuit during hybrid radio interference environment evaluation criterion is met for obtaining Highly and simultaneously line space, the reconstruction for current transmission line of electricity provide reference.