Channel gain calculation method and system of digital substation wireless monitoring system

Abstract

The invention discloses a channel gain calculation method of a digital substation wireless monitoring system. The method comprises the following steps: acquiring data information of a target digital substation; defining the geometrical shape of the target digital substation; determining a range of each geometry; determining the distribution type of the scatterer in each range; determining a spatial distribution area of each scatterer and a probability density function in the area; setting data parameters of the transmitting antenna and the receiving antenna; calculating the geometric length and wireless channel gain of a direct / reflection path of each electromagnetic wave path; obtaining the power of the wireless signal propagated through each electromagnetic wave propagation path, superposing the power on a receiving antenna to obtain the total receiving power, and calculating the channel gain of superposing all the paths at a receiving end. The invention also discloses a system for realizing the channel gain calculation method of the digital substation wireless monitoring system. The method is high in reliability, good in accuracy and relatively high in efficiency.

Description

Technical Field

[0001] The invention belongs to the field of electrical automation, and in particular relates to a channel gain calculation method and system of a wireless monitoring system for a digital substation. Background Art

[0002] With the development of economy and technology and the improvement of people's living standards, electricity has become an indispensable secondary energy source in people's production and life, bringing endless convenience to people's production and life. Therefore, ensuring the stable and reliable supply of electricity has become one of the most important tasks of the power system.

[0003] At present, digital substations have been widely used in power systems. In digital substations, the communication between the control center and the field equipment is carried out by wireless communication. Wireless communication has the characteristics of wide coverage, multiple access points, low investment and maintenance costs, and good scalability; however, the propagation channel of wireless communication is an open space and is easily interfered by the external environment; moreover, there are a large number of electrical equipment in digital substations, and they are usually made of metal. Metal materials are strong anti-scatterers for electromagnetic waves and will change the propagation path of electromagnetic waves. Therefore, the calculation of the channel gain of the wireless monitoring system of the digital substation is of great significance to the design and operation of the digital substation.

[0004] At present, the calculation scheme of the channel gain of the wireless monitoring system of the digital substation adopts a simplified scheme, that is, it is assumed that the internal structure and configuration of the substation are rectangular in site selection, its control center is set at the vertex of the rectangle, the transmitting antenna is at any position inside the rectangle, the scatterers are distributed in the rectangular area, the influence of scatterers outside the rectangular area is not considered, the scatterers are uniformly distributed, the propagation of radio waves in non-direct paths is mainly based on single reflection on the scatterers, each scatterer in the scatterer area generates a radio wave reflection path with the same probability of 1, each scatterer is a full radiation element and has the same reflection coefficient, and the radio wave signal transmitted by the transmitting antenna is reflected once by the scatterer to the receiving antenna. However, these assumed conditions will make the existing channel gain calculation scheme less reliable and accurate. Therefore, the existing channel gain calculation scheme of the wireless monitoring system of the digital substation has gradually ceased to be applicable to the high-precision requirements of today's power system. Summary of the invention

[0005] One of the purposes of the present invention is to provide a channel gain calculation method for a digital substation wireless monitoring system with high reliability, good accuracy and high efficiency.

[0006] A second object of the present invention is to provide a system for implementing the channel gain calculation method of the digital substation wireless monitoring system.

[0007] The channel gain calculation method of the digital substation wireless monitoring system provided by the present invention comprises the following steps:

[0008] S1. Obtain data information of the target digital substation;

[0009] S2. Delineate the geometric shape of the target digital substation according to the data information obtained in step S1;

[0010] S3. Determine the range of each geometric shape according to the geometric shape defined in step S2;

[0011] S4. Determine the distribution type of scatterers within each range according to the range defined in step S3;

[0012] S5. Determine the spatial distribution area of ​​each scatterer and the probability density function within the area according to the distribution type of each scatterer determined in step S4;

[0013] S6. Set the data parameters of the transmitting antenna and the receiving antenna;

[0014] S7. Consider and track all electromagnetic wave paths, calculate the geometric lengths of the direct path and the reflected path of each electromagnetic wave path, and calculate the wireless channel gain on each electromagnetic wave path;

[0015] S8. Obtain the power of the wireless signal transmitted through each electromagnetic wave propagation path, superimpose it on the receiving antenna to obtain the total received power, and calculate the channel gain of all superimposed paths at the receiving end to complete the calculation of the channel gain of the wireless monitoring system of the target digital substation.

[0016] Delineating the geometric shape of the target digital substation in step S2 specifically includes the following steps:

[0017] S21. Data collection and analysis: Collect geographic information of the target substation; the geographic information includes topographic maps, building distribution and equipment layout;

[0018] S22. Geometric model construction: Based on the collected data, a geometric model of the substation is constructed to determine the geometric shape of the structure and incorporate each device in the substation into the model;

[0019] S23. Area division: Divide the entire substation area into several sub-areas, and set a corresponding geometric shape for each sub-area;

[0020] S24. Geometric shape parameterization: define parameters for each geometric shape and record the coordinate information of each shape; the parameters include length, width, height, volume and surface area.

[0021] Determining the range of each geometric shape in step S3 specifically includes the following steps:

[0022] S31. Calculation of geometric shape extension: Determine the extension of each geometric shape according to the geometric model established in step S2; the extension is the smallest cube or cylinder surrounding the geometric shape;

[0023] S32. Create range model: In three-dimensional space, construct a range model for each geometric shape to obtain a visualization graph containing the signal propagation area.

[0024] The step S4 of determining the distribution type of scatterers within each range specifically includes the following steps:

[0025] S41. Definition of scatterer types: Different types of scatterers are defined according to the characteristics of substation equipment; scatterer types include circular scatterers, semicircular scatterers and elliptical scatterers;

[0026] S42. Construction of scatterer distribution model: marking different types of scatterers in the three-dimensional model, and setting characteristic parameters for each type, wherein the characteristic parameters include shape and size.

[0027] The step S5 of determining the spatial distribution area of ​​each scatterer and the probability density function within the area specifically includes the following steps:

[0028] S51. Determine the spatial distribution area of ​​each scatterer: determine the volume range of the scatterer space according to the geometric characteristics of the scatterer; use geometric figures to represent the occupied space of each scatterer;

[0029] S52. Calculation of probability density function: For different types of scatterers, establish corresponding probability density functions to describe their distribution in space.

[0030] A. In the circular model, the transmitting antenna is located at the center of the circle, the receiving antenna is outside the circle, and the scatterers are evenly distributed inside the circle;

[0031] The azimuth angle of the signal arriving at the receiving antenna is θ; when θ=α, α is any angle between 0-90°, the line between the scatterer and the receiving antenna and the circle have two intersection points, and the distance between the first intersection point and the receiving antenna is ρ 1 , the distance between the second intersection point and the receiving antenna is ρ 2 , then there is the following relationship:

[0032] ρ 1 sinα=y 1

[0033] ρ 2 sinα=y 2

[0034] ρ 1 cosα=x 1 +D

[0035] ρ 2 cosα=x 2 +D

[0036] Chinese Chinese 1 is the coordinate of the first intersection point in the vertical coordinate system; y 2 is the coordinate of the second intersection point in a vertical coordinate system; x 1 is the coordinate of the first intersection point in the horizontal coordinate system; x 2 is the coordinate of the second intersection point in the horizontal coordinate system; D is the distance between the receiving antenna and the transmitting antenna;

[0037] The cumulative distribution function of the azimuth angle θ of the receiving antenna wave arrival signal is expressed as

[0038]

[0039] Where R is the radius of the circle in the circular model;

[0040] ρ 1 and ρ 2 Using variable α, we can get the cumulative distribution function of the azimuth angle θ of the receiving antenna wave arrival signal, which is expressed as

[0041]

[0042] Taking the derivative of the cumulative distribution function F(θ) with respect to θ, we get the probability density function of the azimuth angle:

[0043]

[0044] Where k is an intermediate variable, and

[0045] B. In the semicircular model, the transmitting antenna is located at one end of the semicircle diameter, the receiving antenna is located at the other end of the semicircle diameter, and the scatterers are evenly distributed in the semicircle;

[0046] The azimuth angle of the signal arriving at the receiving antenna is θ; when θ = α, there is an intersection point between the line between the scatterer and the receiving antenna and the semicircle, and ρ is the distance between the receiving antenna and the intersection point, then there is a relationship

[0047] ρsinα=y

[0048] ρcosα=x+R

[0049] Where y is the coordinate of the intersection point in the vertical coordinate system; x is the coordinate of the intersection point in the horizontal coordinate system; R is the radius of the semicircle of the semicircular model;

[0050] The cumulative distribution function of the azimuth angle θ of the receiving antenna wave arrival signal is expressed as

[0051] Representing ρ with the variable α, we can obtain the cumulative distribution function of the azimuth angle θ of the receiving antenna wave arrival signal, which is expressed as

[0052] Taking the derivative of the cumulative distribution function F(θ) with respect to θ, we get the probability density function of the azimuth angle:

[0053] C. In the ellipse model, the transmitting antenna is located at one focus of the ellipse, the receiving antenna is located at the other focus of the ellipse, and the scatterers are evenly distributed in the ellipse and symmetrical about the x-axis; only the probability density function in the upper half of the ellipse is considered;

[0054] The azimuth angle of the signal arriving at the receiving antenna is θ; when θ = α, the line between the scatterer and the receiving antenna intersects the ellipse, and ρ is the distance between the receiving antenna and the intersection. Then there is a relationship:

[0055] ρsinα=y

[0056] ρcosα=x+c

[0057]

[0058] Where y is the coordinate of the intersection point in the vertical coordinate system; x is the coordinate of the intersection point in the horizontal coordinate system; a is the length of the major semi-axis of the ellipse; b is the length of the minor semi-axis of the ellipse; c is the focal length of the ellipse;

[0059] The cumulative distribution function of the azimuth angle θ of the receiving antenna wave arrival signal is expressed as

[0060] Representing ρ with the variable α, we can obtain the cumulative distribution function of the azimuth angle θ of the receiving antenna wave arrival signal, which is expressed as

[0061] Taking the derivative of the cumulative distribution function F(θ) with respect to θ, we get the probability density function of the azimuth angle: Among them, k is an intermediate variable, and

[0062] The step S6 of setting the data parameters of the transmitting antenna and the receiving antenna specifically includes the following steps:

[0063] S61. Set the transmitting antenna parameters: Set the operating frequency f: usually the frequency specified by the wireless communication standard (such as 2.4GHz, 5GHz, etc.); Set the gain G of the transmitting antenna t: The unit is dBi, which indicates the gain of the antenna in a specific direction compared to the ideal antenna; sets the radiation pattern of the transmitting antenna, including the main lobe width and side lobe level; sets the output power P t : Usually expressed in milliwatts (mW) or decibel milliwatts (dBm);

[0064] S62. Set the receiving antenna parameters: Set the operating frequency f: the same as the transmitting antenna; Set the gain G of the receiving antenna r : The unit is dBi; set the receiving sensitivity S r : The minimum signal strength that the receiving system can handle, measured in dBm; Sets the noise factor NF of the receiving antenna: Usually expressed in dB, it affects the quality of the received signal.

[0065] The method of considering and tracking all electromagnetic wave paths, calculating the geometric lengths of the direct paths and the reflected paths of each electromagnetic wave path, and calculating the wireless channel gain on each electromagnetic wave path described in step S7 specifically includes the following steps:

[0066] S71. Calculate the geometric length of the direct path: Set the transmitting antenna position to L t (x t ,y t ), the receiving antenna position is L r (x r ,y r );The geometric length d of the direct path is calculated using the following formula direct :

[0067]

[0068] S72. Calculate the geometric length of the reflection path: Consider the scatterer S(x s ,y s ), then the geometric length of the reflection path is d reflected include:

[0069] The path length d from the transmitting antenna to the scatterer ts :

[0070]

[0071] The path length d from the scatterer to the receiving antenna sr :

[0072]

[0073] Get the geometric length d of the reflection path reflected is d reflected =d ts +d sr ;

[0074] S73. Calculate the wireless channel gain: Consider the gains of the direct and reflected paths, assume that there are N paths, and the paths include the direct path and the reflected path. Then, the wireless channel gain G is calculated using the following formula:

[0075] G=G t +G r -L path

[0076] In the formula, G t is the transmitting antenna gain; G r is the receiving antenna gain; L path is the path loss and L path =20log 10 (d)+20log 10 (f)+K, where d is the path length, f is the operating frequency, and K is a set constant that is related to the environment and antenna characteristics.

[0077] The power of the wireless signal propagated through each electromagnetic wave propagation path is obtained in step S8, and the total received power is superimposed on the receiving antenna, and the channel gain of all paths superimposed at the receiving end is calculated to complete the calculation of the channel gain of the wireless monitoring system of the target digital substation, which specifically includes the following steps:

[0078] S81. Calculate the wireless signal power propagated along each electromagnetic wave propagation path: For each path i, use the following formula to calculate the received power at the receiving end:

[0079]

[0080] Where P t is the transmitting power; is the loss of path i, calculated based on distance and environmental characteristics; is other losses of path i, such as connection loss, interference, etc.;

[0081] S82. Calculate the total received power: At the receiving end, the following formula is used to calculate the received power of all paths:

[0082]

[0083] Where: N is the number of paths;

[0084] S83. Calculate channel gain: Calculate the channel gain G channel for

[0085] The present invention also provides a system for implementing the channel gain calculation method of the digital substation wireless monitoring system, comprising a data acquisition module, a shape delineation module, a range determination module, a distribution determination module, a function calculation module, a parameter setting module, a path calculation module and a gain calculation module; the data acquisition module, the shape delineation module, the range determination module, the distribution determination module, the function calculation module, the parameter setting module, the path calculation module and the gain calculation module are connected in series in sequence; the data acquisition module is used to acquire data information of the target digital substation, and upload the data information to the shape delineation module; the shape delineation module is used to delineate the geometric shape of the target digital substation according to the received data information and the acquired data information, and upload the data information to the range determination module; the range determination module is used to determine the range of each geometric shape according to the received data information and the delineated geometric shape, and upload the data information to the distribution determination module; the distribution determination module is used to determine the scatterer within each range according to the received data information and the delineated range. The distribution type is determined, and the data information is uploaded to the function calculation module; the function calculation module is used to determine the spatial distribution area of ​​each scatterer and the probability density function in the area according to the received data information and the determined distribution type of each scatterer, and upload the data information to the parameter setting module; the parameter setting module is used to set the data parameters of the transmitting antenna and the receiving antenna according to the received data information, and upload the data information to the path calculation module; the path calculation module is used to consider and track all electromagnetic wave paths according to the received data information, calculate the geometric length of the direct path and the reflected path of each electromagnetic wave path, and calculate the wireless channel gain on each electromagnetic wave path, and upload the data information to the gain calculation module; the gain calculation module is used to obtain the power of the wireless signal propagated through each electromagnetic wave propagation path according to the received data information, superimpose it on the receiving antenna to obtain the total received power, and calculate the channel gain of all paths superimposed at the receiving end, so as to complete the calculation of the channel gain of the wireless monitoring system of the target digital substation.

[0086] The channel gain calculation method and system of the digital substation wireless monitoring system provided by the present invention are combined with the distribution of scatterers in the digital substation, and carry out refined modeling and analysis according to the positional relationship between the transmitting antenna, the receiving antenna and the scatterers. Not only the channel gain calculation of the digital substation wireless monitoring system is completed, but also the reliability, accuracy and efficiency are higher. BRIEF DESCRIPTION OF THE DRAWINGS

[0087] Figure 1 The figure is a schematic diagram of the method flow of the present invention.

[0088] Figure 2 Schematic diagram of the functional modules of the system of the present invention. DETAILED DESCRIPTION

[0089] like Figure 1 The method flow chart of the method of the present invention is shown as follows: the channel gain calculation method of the digital substation wireless monitoring system disclosed in the present invention comprises the following steps:

[0090] S1. Obtain data information of the target digital substation;

[0091] S2. Delineate the geometric shape of the target digital substation according to the data information obtained in step S1; specifically, the steps include:

[0092] S21. Data collection and analysis: Collect geographic information of the target substation; the geographic information includes topographic maps, building distribution and equipment layout, etc.;

[0093] S22. Geometric model construction: Based on the collected data, a geometric model of the substation is constructed to determine the geometric shape of the structure and incorporate each device in the substation into the model;

[0094] S23. Area division: Divide the entire substation area into several sub-areas, and set a corresponding geometric shape for each sub-area;

[0095] S24. Geometric shape parameterization: define parameters for each geometric shape and record the coordinate information of each shape; the parameters include length, width, height, volume and surface area, etc.;

[0096] S3. Determine the range of each geometric shape according to the geometric shape defined in step S2; specifically comprising the following steps:

[0097] S31. Calculation of geometric shape extension: Determine the extension of each geometric shape according to the geometric model established in step S2; the extension is the smallest cube or cylinder surrounding the geometric shape;

[0098] S32. Create a range model: construct a range model of each geometric shape in three-dimensional space to obtain a visualization graph containing a signal propagation area;

[0099] S4. According to the range defined in step S3, determine the distribution type of scatterers within each range; specifically comprising the following steps:

[0100] S41. Definition of scatterer types: Different types of scatterers are defined according to the characteristics of substation equipment; scatterer types include circular scatterers, semicircular scatterers and elliptical scatterers;

[0101] S42. Scatter distribution model construction: marking different types of scatterers in the three-dimensional model and setting characteristic parameters for each type, wherein the characteristic parameters include shape and size;

[0102] S5. According to the distribution type of each scatterer determined in step S4, determine the spatial distribution area of ​​each scatterer and the probability density function within the area; specifically comprising the following steps:

[0103] S51. Determine the spatial distribution area of ​​each scatterer: determine the volume range of the scatterer space according to the geometric characteristics of the scatterer; use geometric figures to represent the occupied space of each scatterer;

[0104] S52. Calculation of probability density function: For different types of scatterers, establish corresponding probability density functions to describe their distribution in space.

[0105] A. In the circular model, the transmitting antenna is located at the center of the circle, the receiving antenna is outside the circle, and the scatterers are evenly distributed inside the circle;

[0106] The azimuth angle of the signal arriving at the receiving antenna is θ; when θ=α, α is any angle between 0-90°, the line between the scatterer and the receiving antenna and the circle have two intersection points, and the distance between the first intersection point and the receiving antenna is ρ 1 , the distance between the second intersection point and the receiving antenna is ρ 2 , then there is the following relationship:

[0107] ρ 1 sinα=y 1

[0108] ρ 2 sinα=y 2

[0109] ρ 1 cosα=x 1 +D

[0110] ρ 2 cosα=x 2 +D

[0111] Chinese Chinese 1 is the coordinate of the first intersection point in the vertical coordinate system; y 2 is the coordinate of the second intersection point in a vertical coordinate system; x 1 is the coordinate of the first intersection point in the horizontal coordinate system; x 2 is the coordinate of the second intersection point in the horizontal coordinate system; D is the distance between the receiving antenna and the transmitting antenna;

[0112] The cumulative distribution function of the azimuth angle θ of the receiving antenna wave arrival signal is expressed as

[0113]

[0114] Where R is the radius of the circle in the circular model;

[0115] ρ 1 and ρ 2 Using variable α, we can get the cumulative distribution function of the azimuth angle θ of the receiving antenna wave arrival signal, which is expressed as

[0116]

[0117] Taking the derivative of the cumulative distribution function F(θ) with respect to θ, we get the probability density function of the azimuth angle:

[0118]

[0119] Where k is an intermediate variable, and

[0120] B. In the semicircular model, the transmitting antenna is located at one end of the semicircle diameter, the receiving antenna is located at the other end of the semicircle diameter, and the scatterers are evenly distributed in the semicircle;

[0121] The azimuth angle of the signal arriving at the receiving antenna is θ; when θ = α, there is an intersection point between the line between the scatterer and the receiving antenna and the semicircle, and ρ is the distance between the receiving antenna and the intersection point, then there is a relationship

[0122] ρsinα=y

[0123] ρcosα=x+R

[0124] Where y is the coordinate of the intersection point in the vertical coordinate system; x is the coordinate of the intersection point in the horizontal coordinate system; R is the radius of the semicircle of the semicircular model;

[0125] The cumulative distribution function of the azimuth angle θ of the receiving antenna wave arrival signal is expressed as

[0126] Representing ρ with the variable α, we can obtain the cumulative distribution function of the azimuth angle θ of the receiving antenna wave arrival signal, which is expressed as

[0127] Taking the derivative of the cumulative distribution function F(θ) with respect to θ, we get the probability density function of the azimuth angle:

[0128] C. In the ellipse model, the transmitting antenna is located at one focus of the ellipse, the receiving antenna is located at the other focus of the ellipse, and the scatterers are evenly distributed in the ellipse and symmetrical about the x-axis; only the probability density function in the upper half of the ellipse is considered;

[0129] The azimuth angle of the signal arriving at the receiving antenna is θ; when θ = α, the line between the scatterer and the receiving antenna intersects the ellipse, and ρ is the distance between the receiving antenna and the intersection. Then there is a relationship:

[0130] ρsinα=y

[0131] ρcosα=x+c

[0132]

[0133] Where y is the coordinate of the intersection point in the vertical coordinate system; x is the coordinate of the intersection point in the horizontal coordinate system; a is the length of the major semi-axis of the ellipse; b is the length of the minor semi-axis of the ellipse; c is the focal length of the ellipse;

[0134] The cumulative distribution function of the azimuth angle θ of the receiving antenna wave arrival signal is expressed as

[0135] Representing ρ with the variable α, we can obtain the cumulative distribution function of the azimuth angle θ of the receiving antenna wave arrival signal, which is expressed as

[0136] Taking the derivative of the cumulative distribution function F(θ) with respect to θ, we get the probability density function of the azimuth angle: Among them, k is an intermediate variable, and

[0137] S6. Setting the data parameters of the transmitting antenna and the receiving antenna; specifically comprising the following steps:

[0138] S61. Set the transmitting antenna parameters: Set the operating frequency f: usually the frequency specified by the wireless communication standard (such as 2.4GHz, 5GHz, etc.); Set the gain G of the transmitting antenna t : The unit is dBi, which indicates the gain of the antenna in a specific direction compared to the ideal antenna; sets the radiation pattern of the transmitting antenna, including the main lobe width and side lobe level; sets the output power P t : Usually expressed in milliwatts (mW) or decibel milliwatts (dBm);

[0139] S62. Set the receiving antenna parameters: Set the operating frequency f: the same as the transmitting antenna; Set the gain G of the receiving antenna r : The unit is dBi; set the receiving sensitivity S r : The minimum signal strength that the receiving system can handle, in dBm; Set the noise factor NF of the receiving antenna: usually expressed in dB, affects the quality of the received signal;

[0140] S7. Consider and track all electromagnetic wave paths, calculate the geometric lengths of the direct paths and the reflected paths of each electromagnetic wave path, and calculate the wireless channel gain on each electromagnetic wave path; specifically, the steps include:

[0141] S71. Calculate the geometric length of the direct path: Set the transmitting antenna position to L t(x t ,y t ), the receiving antenna position is L r (x r ,y r );The geometric length d of the direct path is calculated using the following formula direct :

[0142]

[0143] S72. Calculate the geometric length of the reflection path: Consider the scatterer S(x s ,y s ), then the geometric length of the reflection path is d reflected include:

[0144] The path length d from the transmitting antenna to the scatterer ts :

[0145]

[0146] The path length d from the scatterer to the receiving antenna sr :

[0147]

[0148] Get the geometric length d of the reflection path reflected is d reflected =d ts +d sr ;

[0149] S73. Calculate the wireless channel gain: Consider the gains of the direct and reflected paths, assume that there are N paths, and the paths include the direct path and the reflected path. Then, the wireless channel gain G is calculated using the following formula:

[0150] G=G t +G r -L path

[0151] In the formula, G t is the transmitting antenna gain; G r is the receiving antenna gain; L path is the path loss and L path =20log 10 (d)+20log 10 (f)+K, where d is the path length, f is the operating frequency, and K is a set constant that is related to the environment and antenna characteristics;

[0152] S8. Obtain the power of the wireless signal propagated through each electromagnetic wave propagation path, superimpose it on the receiving antenna to obtain the total received power, and calculate the channel gain of all paths superimposed at the receiving end to complete the calculation of the channel gain of the wireless monitoring system of the target digital substation; specifically, the following steps are included:

[0153] S81. Calculate the wireless signal power propagated along each electromagnetic wave propagation path: For each path i, use the following formula to calculate the received power at the receiving end:

[0154]

[0155] Where P t is the transmitting power; is the loss of path i, calculated based on distance and environmental characteristics; is other losses of path i, such as connection loss, interference, etc.;

[0156] S82. Calculate the total received power: At the receiving end, the following formula is used to calculate the received power of all paths:

[0157]

[0158] Where: N is the number of paths;

[0159] S83. Calculate channel gain: Calculate the channel gain G channel for

[0160] like Figure 2The functional module schematic diagram of the system of the present invention is shown as follows: the system disclosed in the present invention for realizing the channel gain calculation method of the digital substation wireless monitoring system comprises a data acquisition module, a shape delineation module, a range determination module, a distribution determination module, a function calculation module, a parameter setting module, a path calculation module and a gain calculation module; the data acquisition module, the shape delineation module, the range determination module, the distribution determination module, the function calculation module, the parameter setting module, the path calculation module and the gain calculation module are connected in series in sequence; the data acquisition module is used to acquire data information of the target digital substation and upload the data information to the shape delineation module; the shape delineation module is used to delineate the geometric shape of the target digital substation according to the received data information and the acquired data information, and upload the data information to the range determination module; the range determination module is used to determine the range of each geometric shape according to the received data information and the delineated geometric shape, and upload the data information to the distribution determination module; the distribution determination module is used to determine the range of each geometric shape according to the received data information and the delineated range, and upload the data information to the distribution determination module; The distribution type of scatterers within each range is determined, and the data information is uploaded to the function calculation module; the function calculation module is used to determine the spatial distribution area of ​​each scatterer and the probability density function within the area according to the received data information and the determined distribution type of each scatterer, and upload the data information to the parameter setting module; the parameter setting module is used to set the data parameters of the transmitting antenna and the receiving antenna according to the received data information, and upload the data information to the path calculation module; the path calculation module is used to consider and track all electromagnetic wave paths according to the received data information, calculate the geometric length of the direct path and the reflected path of each electromagnetic wave path, and calculate the wireless channel gain on each electromagnetic wave path, and upload the data information to the gain calculation module; the gain calculation module is used to obtain the power of the wireless signal propagated through each electromagnetic wave propagation path according to the received data information, superimpose it on the receiving antenna to obtain the total received power, and calculate the channel gain of all paths superimposed at the receiving end to complete the calculation of the channel gain of the wireless monitoring system of the target digital substation.

Claims

1. A channel gain calculation method for a digital substation wireless monitoring system, comprising the following steps: S1. Obtain data information of the target digital substation; S2. Delineate the geometric shape of the target digital substation according to the data information obtained in step S1; S3. Determine the range of each geometric shape according to the geometric shape defined in step S2; S4. Determine the distribution type of scatterers within each range according to the range defined in step S3; S5. Determine the spatial distribution area of ​​each scatterer and the probability density function within the area according to the distribution type of each scatterer determined in step S4; S6. Set the data parameters of the transmitting antenna and the receiving antenna; S7. Consider and track all electromagnetic wave paths, calculate the geometric lengths of the direct path and the reflected path of each electromagnetic wave path, and calculate the wireless channel gain on each electromagnetic wave path; S8. Obtain the power of the wireless signal transmitted through each electromagnetic wave propagation path, superimpose it on the receiving antenna to obtain the total received power, and calculate the channel gain of all superimposed paths at the receiving end to complete the calculation of the channel gain of the wireless monitoring system of the target digital substation.

2. The channel gain calculation method of the digital substation wireless monitoring system according to claim 1 is characterized in that Delineating the geometric shape of the target digital substation in step S2 specifically includes the following steps: S21. Data collection and analysis: Collect geographic information of the target substation; the geographic information includes topographic maps, building distribution and equipment layout; S22. Geometric model construction: Based on the collected data, a geometric model of the substation is constructed to determine the geometric shape of the structure and incorporate each device in the substation into the model; S23. Area division: Divide the entire substation area into several sub-areas, and set a corresponding geometric shape for each sub-area; S24. Geometric shape parameterization: define parameters for each geometric shape and record the coordinate information of each shape; the parameters include length, width, height, volume and surface area.

3. The channel gain calculation method of the digital substation wireless monitoring system according to claim 2 is characterized in that Determining the range of each geometric shape in step S3 specifically includes the following steps: S31. Calculation of geometric shape extension: Determine the extension of each geometric shape according to the geometric model established in step S2; the extension is the smallest cube or cylinder surrounding the geometric shape; S32. Create range model: In three-dimensional space, construct a range model for each geometric shape to obtain a visualization graph containing the signal propagation area.

4. The channel gain calculation method of the digital substation wireless monitoring system according to claim 3 is characterized in that The step S4 of determining the distribution type of scatterers within each range specifically includes the following steps: S41. Definition of scatterer types: Different types of scatterers are defined according to the characteristics of substation equipment; scatterer types include circular scatterers, semicircular scatterers and elliptical scatterers; S42. Construction of scatterer distribution model: marking different types of scatterers in the three-dimensional model, and setting characteristic parameters for each type of scatterer, wherein the characteristic parameters include shape and size.

5. The channel gain calculation method of the digital substation wireless monitoring system according to claim 4 is characterized in that The step S5 of determining the spatial distribution area of ​​each scatterer and the probability density function within the area specifically includes the following steps: S51. Determine the spatial distribution area of ​​each scatterer: determine the volume range of the scatterer space according to the geometric characteristics of the scatterer; use geometric figures to represent the occupied space of each scatterer; S52. Calculation of probability density function: For different types of scatterers, establish corresponding probability density functions to describe their distribution in space. A. In the circular model, the transmitting antenna is located at the center of the circle, the receiving antenna is outside the circle, and the scatterers are evenly distributed inside the circle; The azimuth angle of the signal arriving at the receiving antenna is θ; when θ=α, α is any angle between 0-90°, the line between the scatterer and the receiving antenna and the circle have two intersection points, the distance between the first intersection point and the receiving antenna is ρ1, and the distance between the second intersection point and the receiving antenna is ρ2, then the following relationship exists: ρ1sinα=y1 ρ2sinα=y2 ρ1cosα=x1+D ρ2cosα=x2+D In the formula, y1 is the coordinate of the first intersection point in the vertical coordinate system; y2 is the coordinate of the second intersection point in a vertical coordinate system; x1 is the coordinate of the first intersection point in the horizontal coordinate system; x2 is the coordinate of the second intersection point in the horizontal coordinate system; D is the distance between the receiving antenna and the transmitting antenna; The cumulative distribution function of the azimuth angle θ of the receiving antenna wave arrival signal is expressed as Where R is the radius of the circle in the circular model; Representing ρ1 and ρ2 with the variable α, we can obtain the cumulative distribution function of the azimuth angle θ of the receiving antenna wave arrival signal, which is expressed as Taking the derivative of the cumulative distribution function F(θ) with respect to θ, we get the probability density function of the azimuth angle: Where k is an intermediate variable, and B. In the semicircular model, the transmitting antenna is located at one end of the semicircle diameter, the receiving antenna is located at the other end of the semicircle diameter, and the scatterers are evenly distributed in the semicircle; The azimuth angle of the signal arriving at the receiving antenna is θ; when θ = α, the line between the scatterer and the receiving antenna intersects the semicircle, and ρ is the distance between the receiving antenna and the intersection. Then there is a relationship: ρsinα=y ρcosα=x+R Where y is the coordinate of the intersection point in the vertical coordinate system; x is the coordinate of the intersection point in the horizontal coordinate system; R is the radius of the semicircle of the semicircular model; The cumulative distribution function of the azimuth angle θ of the receiving antenna wave arrival signal is expressed as Representing ρ with the variable α, we can obtain the cumulative distribution function of the azimuth angle θ of the receiving antenna wave arrival signal, which is expressed as Taking the derivative of the cumulative distribution function F(θ) with respect to θ, we get the probability density function of the azimuth angle: C. In the ellipse model, the transmitting antenna is located at one focus of the ellipse, the receiving antenna is located at the other focus of the ellipse, and the scatterers are evenly distributed in the ellipse and symmetrical about the x-axis; only the probability density function in the upper half of the ellipse is considered; The azimuth angle of the signal arriving at the receiving antenna is θ; when θ = α, the line between the scatterer and the receiving antenna intersects the ellipse, and ρ is the distance between the receiving antenna and the intersection. Then there is a relationship: ρsinα=y ρcosα=x+c Where y is the coordinate of the intersection point in the vertical coordinate system; x is the coordinate of the intersection point in the horizontal coordinate system; a is the length of the major semi-axis of the ellipse; b is the length of the minor semi-axis of the ellipse; c is the focal length of the ellipse; The cumulative distribution function of the azimuth angle θ of the receiving antenna wave arrival signal is expressed as Representing ρ with the variable α, we can obtain the cumulative distribution function of the azimuth angle θ of the receiving antenna wave arrival signal, which is expressed as Taking the derivative of the cumulative distribution function F(θ) with respect to θ, we get the probability density function of the azimuth angle: Among them, k is an intermediate variable, and 6. The channel gain calculation method of the digital substation wireless monitoring system according to claim 5 is characterized in that The step S6 of setting the data parameters of the transmitting antenna and the receiving antenna specifically includes the following steps: S61. Set the transmitting antenna parameters: set the operating frequency f; set the transmitting antenna gain G t ; Set the radiation pattern of the transmitting antenna, including the main lobe width and side lobe level; Set the output power P t ; S62. Set the receiving antenna parameters: Set the operating frequency f: Set the receiving antenna gain G r ; Set the receiving sensitivity S r ; Set the noise factor NF of the receiving antenna.

7. The channel gain calculation method of the digital substation wireless monitoring system according to claim 6 is characterized in that The method of considering and tracking all electromagnetic wave paths, calculating the geometric lengths of the direct paths and the reflected paths of each electromagnetic wave path, and calculating the wireless channel gain on each electromagnetic wave path described in step S7 specifically includes the following steps: S71. Calculate the geometric length of the direct path: Set the transmitting antenna position to L t (x t ,y t ), the receiving antenna position is L r (x r ,y r );The geometric length d of the direct path is calculated using the following formula direct : S72. Calculate the geometric length of the reflection path: Consider the scatterer S(x s ,y s ), then the geometric length of the reflection path is d reflected include: The path length d from the transmitting antenna to the scatterer ts : The path length d from the scatterer to the receiving antenna sr : Get the geometric length d of the reflection path reflected is d reflected =d ts +d sr ; S73. Calculate the wireless channel gain: Consider the gains of the direct and reflected paths, assume that there are N paths, and the paths include the direct path and the reflected path. Then, the wireless channel gain G is calculated using the following formula: G=G t +G r -L path In the formula, G t is the transmitting antenna gain; G r is the receiving antenna gain; L path is the path loss and L path =20log 10 (d)+20log 10 (f)+K, where d is the path length, f is the operating frequency, and K is a set constant.

8. The channel gain calculation method of the digital substation wireless monitoring system according to claim 7 is characterized in that The power of the wireless signal propagated through each electromagnetic wave propagation path is obtained in step S8, and the total received power is superimposed on the receiving antenna, and the channel gain of all paths superimposed at the receiving end is calculated to complete the calculation of the channel gain of the wireless monitoring system of the target digital substation, which specifically includes the following steps: S81. Calculate the wireless signal power propagated along each electromagnetic wave propagation path: For each path i, use the following formula to calculate the received power at the receiving end: Where P t is the transmitting power; is the loss of path i, calculated based on distance and environmental characteristics; is the other loss of path i; S82. Calculate the total received power: At the receiving end, the following formula is used to calculate the received power of all paths: Where N is the number of paths; S83. Calculate channel gain: Calculate the channel gain G channel for 9. A system for implementing the channel gain calculation method of the digital substation wireless monitoring system according to any one of claims 1 to 8, characterized in that It includes a data acquisition module, a shape delineation module, a range determination module, a distribution determination module, a function calculation module, a parameter setting module, a path calculation module and a gain calculation module; the data acquisition module, the shape delineation module, the range determination module, the distribution determination module, the function calculation module, the parameter setting module, the path calculation module and the gain calculation module are connected in series in sequence; the data acquisition module is used to acquire data information of the target digital substation and upload the data information to the shape delineation module; the shape delineation module is used to delineate the geometric shape of the target digital substation according to the received data information and the acquired data information, and upload the data information to the range determination module; The range determination module is used to determine the range of each geometric shape according to the received data information and the demarcated geometric shapes, and upload the data information to the distribution determination module; The distribution determination module is used to determine the distribution type of the scatterers in each range according to the received data information and the defined range, and upload the data information to the function calculation module; The function calculation module is used to determine the spatial distribution area of ​​each scatterer and the probability density function within the area according to the received data information and the distribution type of each scatterer, and upload the data information to the parameter setting module; The parameter setting module is used to set the data parameters of the transmitting antenna and the receiving antenna according to the received data information, and upload the data information to the path calculation module; The path calculation module is used to consider and track all electromagnetic wave paths according to the received data information, calculate the geometric lengths of the direct path and the reflected path of each electromagnetic wave path, and calculate the wireless channel gain on each electromagnetic wave path, and upload the data information to the gain calculation module; the gain calculation module is used to obtain the power of the wireless signal propagated through each electromagnetic wave propagation path according to the received data information, superimpose it on the receiving antenna to obtain the total received power, and calculate the channel gain of all paths superimposed at the receiving end to complete the calculation of the channel gain of the wireless monitoring system of the target digital substation.

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