Loss and gain monitoring system and method for unloading vehicle-mounted oil tank based on standard volume characteristics

Abstract

The present application belongs to fuel transportation technology, and relates to a vehicle-mounted oil tank unloading profit and loss monitoring method and system based on standard volume characteristics. According to the longitudinal and lateral inclination angles of the vehicle-mounted oil tank before and after unloading at an oil station, the original liquid level height of oil, and the oil temperature in the tank, combined with the oil tank volume characteristic data and the types of oil carried under different working conditions, the virtual volume of oil in the tank before and after unloading at the oil station and the volume correction coefficient of oil at 20 DEG C are respectively calculated. The standard volume of oil at 20 DEG C is calculated according to the virtual volume and the volume correction coefficient. The standard volume characteristic data of the oil tank are obtained according to the standard tank volume table of the vehicle-mounted oil tank. The liquid level height without inclination angle corresponding to the standard volume of oil at 20 DEG C of the vehicle-mounted oil tank is calculated, and the real standard volume of oil is obtained according to the standard volume characteristic data without inclination angle. The unloading profit and loss of the vehicle-mounted oil tank is calculated according to the real standard volume of unloaded oil and the standard volume of unloaded oil at 20 DEG C measured at the oil station. The present application can accurately obtain the unloading profit and loss.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of fuel transportation, and relates to a rail-mounted oil tank loss and gain monitoring technology, in particular to an oil tank unloading loss and gain monitoring system and method based on standard volume characteristics. BACKGROUND

[0002] The safe transportation of fuel products has always been a problem of concern in the management of oil transportation enterprises. In the transportation of fuel products, theft and non-standard behavior of employees can cause varying degrees of loss to the enterprise, and ordinary computer information management systems cannot solve this problem. Having a set of real-time monitoring of the measurement of fuel transportation vehicles becomes an indispensable auxiliary means in the management of oil transportation enterprises.

[0003] The transportation status of tank trucks is difficult to grasp in real time, which to some extent restricts the improvement of enterprise operating efficiency. When the oil truck is used to transport oil from the oil depot to the oil station, it involves oil receiving loss and gain (the difference between the oil depot oil delivery quantity and the tank measurement quantity), oil unloading loss and gain (the difference between the tank measurement quantity and the oil station unloading oil quantity), and transportation loss and gain (the difference between the oil depot oil receiving quantity and the oil station unloading quantity). The tank is based on the liquid level meter installed therein to measure the oil quantity, and when calibrating the tank volume, only the change of the volume of the tank in the completely horizontal state with the liquid level height is calibrated. However, the oil truck cannot guarantee that the tank is in a completely horizontal state when it is in the oil depot and the oil station, that is, the tank will have a longitudinal inclination (-7°-7°) and a transverse inclination (-7°-7°), resulting in a difference between the liquid level height read by the liquid level meter and the liquid level height in the completely horizontal state, so the real oil quantity in the tank cannot be measured by the liquid level meter. In the fuel transportation industry, how to dynamically and accurately measure the oil quantity in the tank has been a problem plaguing the industry for many years.

[0004] Fuel transportation process involves oil depot, transportation, oil station three parties. When the oil truck unloads oil at the oil station, it may involve multiple oil station unloading conditions, and the measurement instruments of each oil station unloading may also have different degrees of measurement error. If the error is too large, it will cause the oil transportation party to have a large loss on the transported oil. Therefore, when the oil tank truck unloads oil, the on-board oil monitoring system must be able to calculate the unloaded oil volume according to the real-time temperature of the oil in the tank, the transverse and longitudinal inclination angles of the tank, and the liquid level of the oil in the tank, and convert the unloaded oil volume into the standard volume at 20℃, and compare the standard volume with the value measured by the oil station unloading measurement instrument. At present, there is no good solution for the oil tank truck to obtain the standard volume of the oil in the tank in real time and high precision. The existing method has low precision and poor applicability (only applicable to a certain narrow range of liquid level), and cannot meet the requirements of the fuel transportation industry. At the same time, due to the processing and manufacturing process of the oil tank, it is impossible to ensure that the size and shape of the processed oil tank completely match the drawings, so there is a certain difference between the actual oil tank volume and the volume of the oil tank mathematical model established according to the drawings. This difference leads to the inability to accurately know the unloading loss and gain during fuel transportation, which is also a difficult problem faced by oil transportation managers. SUMMARY

[0005] The present application provides a vehicle-mounted oil tank unloading loss and gain monitoring method and system based on standard volume characteristics, which can accurately obtain the unloading loss and gain, has high precision and good applicability, to solve the above-mentioned problems that the prior art cannot accurately obtain the unloading loss and gain.

[0006] In order to achieve the above-mentioned purpose, the present application provides a vehicle-mounted oil tank unloading loss and gain monitoring method based on standard volume characteristics, and the specific steps are as follows:

[0007] S 1, obtain the oil tank volume data under different working conditions based on the three-dimensional mathematical model of the oil tank constructed based on the oil tank drawings, and perform nonlinear regression analysis to obtain the oil tank volume characteristic data under different working conditions;

[0008] S2, based on the unit shape function interpolation method and the oil tank volume characteristic data under different working conditions, calculate the virtual volume of the oil in the vehicle-mounted oil tank before and after unloading at the oil station according to the longitudinal inclination angle, the transverse inclination angle and the original liquid level of the oil before and after unloading at the oil station;

[0009] S3, based on the calculation model of VCF 15 at 15℃ in the ISO-91 / 1 international standard, the iterative calculation method and the type of oil carried by the vehicle-mounted oil tank, calculate the volume correction coefficient of the oil at 20℃ according to the temperature of the oil in the vehicle-mounted oil tank before and after unloading at the oil station;

[0010] S4, multiplying the virtual volume of the oil in the tank obtained in step S2 with the volume correction coefficient obtained in step S3 to obtain the standard volume of the oil at 20℃;

[0011] S5, performing nonlinear regression analysis on the standard tank volume table of the vehicle-mounted oil tank to obtain standard volume characteristic data of the oil tank at no inclination angle;

[0012] S6, calculating the liquid level height corresponding to the standard volume of the oil in the vehicle-mounted oil tank at 20℃ before and after unloading at the oil station based on the improved advance and retreat method, and obtaining the real standard volume of the oil in the tank before and after unloading at the oil station according to the standard volume characteristic data at no inclination angle;

[0013] S7, subtracting the real standard volume of the oil in the tank after unloading from the real standard volume of the oil in the tank before unloading to obtain the real standard volume of the unloaded oil at the oil station; subtracting the standard volume of the unloaded oil at 20℃ measured at the oil station from the real standard volume of the unloaded oil to obtain the unloading loss and gain of the vehicle-mounted oil tank; and dividing the unloading loss and gain of the vehicle-mounted oil tank by the real standard volume of the unloaded oil to obtain the unloading loss and gain rate of the vehicle-mounted oil tank.

[0014] Further, the method further comprises the following steps: calculating the average unloading loss and gain during the operation period according to the data during the operation period, then determining the correction value of the liquid level height according to the standard volume characteristic data at no inclination angle, and correcting the measured liquid level height according to the correction value, and recalculating the unloading loss and gain of the vehicle-mounted oil tank according to the corrected liquid level height.

[0015] Preferably, the specific method for correcting the liquid level height is: calculating the average unloading loss and gain during the operation period according to the data during the operation period; performing linear fitting on the standard volume characteristic data within the set range at no inclination angle to obtain the slope of the fitting straight line; the ratio of the average unloading loss and gain to the slope is the correction value of the liquid level height, if the correction value is negative, it indicates that the liquid level height is too small, then the corrected liquid level height = original liquid level height of the oil + |correction value|, if the correction value is positive, it indicates that the liquid level height is too large, then the corrected liquid level height = original liquid level height of the oil - correction value.

[0016] Preferably, in step S2, the specific method for calculating the virtual volume of the oil in the tank of the vehicle-mounted oil tank before and after unloading at the oil station is:

[0017] The volume of the arbitrary four points i, j, m, n forming a rectangle at the original liquid level height of the oil is calculated by interpolation to obtain the virtual volume of the oil in the tank:

[0018]

[0019] wherein,

[0020]

[0021] In the formula, V is the virtual volume of oil in the tank, V i , V j , V m , V n are the virtual volumes of oil at i, j, m, n points respectively, a, b are the lengths of the rectangle formed by i, j, m, n points, x is the transverse inclination angle, and y is the longitudinal inclination angle.

[0022] Preferably, in step S3, the specific method for calculating the volume correction coefficient of oil at 20℃ is as follows:

[0023] The calculation model of VCF15 at 15℃ in ISO-91 / 1 international standard is as follows:

[0024] VCF15 = exp[-α 15 ΔT(1+0.8α 15 ΔT)] (3)

[0025] In the formula, VCF15 is the volume correction coefficient of oil at standard temperature 15℃, α 15 is the volume expansion coefficient of oil at standard temperature 15℃, and ΔT is the difference between the current temperature and the standard temperature 15℃;

[0026] Given the density of oil at 20℃ ρ 20 , unit: Kg / m 3 , there is the equation:

[0027]

[0028] In the formula, ρ 15 is the density of oil at 15℃, unit: Kg / m 3 ;

[0029] From formula (3) and formula (4), we have:

[0030]

[0031] ρ 15 is calculated by using the iterative calculation method;

[0032] When the temperature of oil in the tank is t, at temperature t, we have:

[0033]

[0034] In the formula, ρ t is the density of oil at temperature t, and VCF20 is the volume correction coefficient of oil at 20℃;

[0035] From formula (6), we have:

[0036]

[0037] VCF20 is calculated by formula (7).

[0038] Preferably, in step S6, the specific method for calculating the liquid level height corresponding to the standard volume of the oil in the vehicle-mounted oil tank at 20°C without the tilt angle before and after the oil station unloading based on the improved advance and retreat method is as follows:

[0039] (1) Take the initial search step αs, set the initial liquid level height α3, calculate the function value according to formula (8) to obtain E3=f(α3), and set kk=0. Formula (8) is expressed as:

[0040]

[0041] In the formula, p i , i=1, 2, 3,..., 8 are the volume characteristic coefficients obtained when all the tilt angles of the vehicle-mounted oil tank are zero; V 20 is the standard volume of the vehicle-mounted oil tank at 20°C, unit: liter; h is the oil height, unit: mm;

[0042] (2) Set the liquid level height α=α3+αs, calculate the function value according to formula (8) to obtain E=f(α), and set kk=kk+1;

[0043] (3) If E×E3>0, compare the sizes of E and E3; if |E|<|E3| arbitrarily, set αs=2.0×αs, α3=α, E3=E, and go to step (2); if |E|>|E3|, set αs=-αs, and go to step (2); if E×E3≤0, go to step (4);

[0044] (4) Set α l =min{α,α3}, α r =max{α,α3}, E l =min{E,E3}, E r =min{E,E3};

[0045] (5) Set E according to formula (8) to obtain E=E(α); if E×E3>0, set E l =E, α l =α, kk=kk+1; otherwise, set E r =E, α r =α, kk=kk+1;

[0046] (6) If α r -α lIf ≥0.01, go to step (5); otherwise, stop the calculation to obtain the liquid level height of the oil in the tank at 20℃ when all the inclination angles of the on-board tank are zero

[0047] To achieve the above purpose, the application further provides an on-board tank oil unloading loss and gain monitoring system based on standard volume characteristics, which is used for implementing the on-board tank oil unloading loss and gain monitoring method, and comprises:

[0048] A model construction module is configured to construct a three-dimensional mathematical model of the tank based on tank drawings.

[0049] A characteristic data acquisition module is configured to acquire tank volume data in different working conditions based on the three-dimensional mathematical model of the tank, to perform nonlinear regression analysis on the tank volume data, and to obtain tank volume characteristic data in different working conditions; and to perform nonlinear regression analysis on a standard tank volume table of the on-board tank, and to obtain standard volume characteristic data of the tank without inclination angle.

[0050] A tank data acquisition device is configured to acquire the longitudinal inclination angle, the transverse inclination angle, the original liquid level height of the oil, and the temperature of the oil in the tank of the on-board tank before and after oil unloading at the oil station.

[0051] A virtual volume calculation module is configured to calculate the virtual volume of the oil in the tank of the on-board tank before and after oil unloading at the oil station based on the unit shape function interpolation method and the tank volume characteristic data in different working conditions according to the longitudinal inclination angle, the transverse inclination angle, and the original liquid level height of the oil of the on-board tank acquired before and after oil unloading at the oil station.

[0052] A volume correction coefficient calculation module is configured to calculate the volume correction coefficient of the oil at 20℃ based on the calculation model of VCF 15 at 15℃ in the ISO-91 / 1 international standard, the iterative calculation method, and the type of the oil carried by the on-board tank according to the temperature of the oil in the tank of the on-board tank acquired before and after oil unloading at the oil station.

[0053] A standard volume calculation module is configured to multiply the virtual volume of the oil in the tank calculated by the virtual volume calculation module and the volume correction coefficient calculated by the volume correction coefficient calculation module to obtain the standard volume of the oil at 20℃.

[0054] A real standard volume calculation module is configured to calculate the liquid level height corresponding to the standard volume of the oil in the tank of the on-board tank at 20℃ before and after oil unloading at the oil station based on the improved advance and retreat method, and to obtain the real standard volume of the oil in the tank before and after oil unloading at the oil station according to the standard volume characteristic data without inclination angle.

[0055] The profit and loss calculation module obtains the real standard volume of the oil unloaded from the tank by subtracting the real standard volume of the oil in the tank after unloading from the real standard volume of the oil in the tank before unloading; obtains the profit and loss volume of the tank by subtracting the standard volume of the oil unloaded at 20℃ from the real standard volume of the oil unloaded; and obtains the profit and loss rate of the tank by dividing the profit and loss volume of the tank by the real standard volume of the oil unloaded.

[0056] Further, the application further comprises a correction module, which calculates the average profit and loss of the oil unloaded during the operation according to the data during the operation, then determines the correction value of the liquid level height according to the standard volume characteristic data at no inclination angle, and corrects the measured liquid level height according to the correction value, so as to recalculate the profit and loss of the oil unloaded from the tank according to the corrected liquid level height.

[0057] Preferably, the specific method for calculating the virtual volume of the oil in the tank before and after unloading from the tank by the virtual volume calculation module is as follows:

[0058] The virtual volume of the oil in the tank is calculated by interpolating the volume of the arbitrary four points i, j, m, n of the rectangle formed by the original liquid level height of the oil at different working conditions, and is as follows:

[0059]

[0060] Wherein,

[0061]

[0062] In the formula, V is the virtual volume of the oil in the tank, V i , V j , V m , V n are the virtual volumes of the oil at the four points i, j, m, n, respectively, a and b are the lengths of the sides of the rectangle formed by the four points i, j, m, n, x is the transverse inclination angle, and y is the longitudinal inclination angle.

[0063] Preferably, the specific method for calculating the volume correction coefficient of the oil at 20℃ by the volume correction coefficient calculation module is as follows:

[0064] The calculation model of VCF15 at 15℃ in the ISO-91 / 1 international standard is as follows:

[0065] VCF15=exp[-α 15 ΔT(1+0.8α 15 ΔT)] (3)

[0066] In the formula, VCF15 is the volume correction coefficient of the oil at 15℃, α 15 is the volume expansion coefficient of the oil at 15℃, and ΔT is the difference between the current temperature and the standard temperature 15℃.

[0067] Density of oil at 20℃, ρ 20 , unit: Kg / m 3 , equation:

[0068]

[0069] In the formula, ρ 15 is the density of oil at 15℃, unit: Kg / m 3 ;

[0070] From formula (3) and formula (4), we have:

[0071]

[0072] ρ 15 is calculated by using iterative calculation method;

[0073] When the temperature of oil in the tank is t, at temperature t, we have:

[0074]

[0075] In the formula, ρ t is the density of oil at temperature t, VCF20 is the volume correction factor of oil at 20℃;

[0076] From formula (6), we have:

[0077]

[0078] VCF20 is calculated from formula (7).

[0079] Compared with the prior art, the application has the advantages and positive effects that:

[0080] (1) The on-vehicle tank oil unloading loss and gain monitoring method and system based on standard volume characteristics has high accuracy of on-vehicle tank oil unloading loss and gain, and meets the requirements of fuel transportation: the single unloading loss and gain rate is not more than 0.5%, and the monthly average unloading loss and gain rate is not more than 0.1%. The dynamic measurement of unloading loss and gain, which has plagued the industry for many years, is solved.

[0081] (2) The on-vehicle tank oil unloading loss and gain monitoring method and system based on standard volume characteristics also calculates the average value of unloading loss and gain during the operation period according to the data during the operation period, then determines the height correction value of the liquid level according to the standard volume characteristic data when there is no inclination angle, and corrects the liquid level height measured by the liquid level instrument, so as to recalculate the on-vehicle tank oil unloading loss and gain through the corrected liquid level height, and further improve the accuracy of on-vehicle tank oil unloading loss and gain. DETAILED DESCRIPTION

[0082] Figure 1 Flow chart of the oil loss and gain monitoring method for the vehicle-mounted oil tank based on the standard volume characteristics according to the embodiment of the present application;

[0083] Figure 2 Structural block diagram of the oil loss and gain monitoring system for the vehicle-mounted oil tank based on the standard volume characteristics according to the embodiment of the present application;

[0084] Figure 3 Schematic diagram of the three-dimensional mathematical model of the oil tank constructed according to the embodiment of the present application;

[0085] Figure 4 Volume isochromatic map of different inclination angles according to the embodiment of the present application;

[0086] Figure 5 Schematic diagram of the oil level at 20℃ in the search interval determined based on the improved advance and retreat method according to the embodiment of the present application;

[0087] Figure 6 Schematic diagram of the volume of the No. 1 tank of the oil tank and the fitting curve according to the embodiment of the present application;

[0088] Figure 7 Schematic diagram of the volume of the No. 2 tank of the oil tank and the fitting curve according to the embodiment of the present application;

[0089] Figure 8 Flow chart of the oil loss and gain monitoring method for the vehicle-mounted oil tank based on the standard volume characteristics according to the embodiment of the present application.

[0090] In the figure, 1, model construction module, 2, characteristic data acquisition module, 3, oil tank data acquisition device, 4, virtual volume calculation module, 5, volume correction coefficient calculation module, 6, standard volume calculation module, 7, real standard volume calculation module, 8, loss and gain calculation module, 9, correction module. DETAILED DESCRIPTION

[0091] The present application will be described in detail below through exemplary embodiments. However, it should be understood that the elements, structures and features in one embodiment can also be beneficially combined into other embodiments without further description.

[0092] When the oil truck is unloading at the oil station, multiple oil stations may be involved in the unloading, and the measuring instruments of each oil station may also have different degrees of measurement error. If the error is too large, it will result in a large loss of oil transportation on the transported oil, that is, the unloading loss and gain (the difference between the oil tank measurement and the oil station unloading) monitoring needs to be monitored. The oil tank measures the oil volume based on the liquid level meter installed in it, and when calibrating the volume of the oil tank, only the change of the volume of the oil tank in the completely horizontal state with the liquid level height is calibrated. However, the oil truck cannot guarantee that the oil tank is in a completely horizontal state when it is at the oil station, that is, the oil tank will have a longitudinal inclination (such as -7°-7°) and a transverse inclination (such as -7°-7°), resulting in a difference between the liquid level height read by the liquid level meter and the liquid level height in the completely horizontal state. The real oil volume in the oil tank cannot be measured by the liquid level meter, which makes the calculated unloading loss and gain error large and inaccurate. In order to accurately detect the unloading loss and gain of the vehicle-mounted oil tank, the present application provides a vehicle-mounted oil tank unloading loss and gain monitoring method and system based on standard volume characteristics, which can accurately obtain the unloading loss and gain, has high precision and good applicability. The following will be described in detail in combination with the drawings.

[0093] Referring to Figure 1 , the present application provides a vehicle-mounted oil tank unloading loss and gain monitoring method based on standard volume characteristics, and the specific steps are as follows:

[0094] S1, an oil tank three-dimensional mathematical model is constructed based on the oil tank drawing (see Figure 3 ) to obtain the oil tank volume data under different working conditions, and nonlinear regression analysis is performed thereon to obtain the oil tank volume characteristic data under different working conditions.

[0095] S2, based on the longitudinal inclination, transverse inclination and original liquid level height of the vehicle-mounted oil tank obtained before and after unloading at the oil station, the virtual volume of the oil in the tank before and after unloading at the oil station is calculated based on the unit shape function interpolation method and the oil tank volume characteristic data under different working conditions.

[0096] Referring to Figure 4 , the isochromatic surface shown in the figure represents the volume value at the same liquid level height, and the liquid level height (for example: 1600mm) of point P is obtained by the liquid level meter. The volume of the oil at point P is calculated by interpolation of the volumes of i, j, m and n. Based on this principle, specifically, the specific method for calculating the virtual volume of the oil in the tank before and after unloading at the oil station is as follows:

[0097] The volumes of any four points i, j, m and n in the form of a rectangle are calculated by interpolation from the volume characteristic data under different working conditions at the original liquid level height (measured by the liquid level meter installed in the oil tank), and the virtual volume of the oil in the tank is obtained as follows:

[0098]

[0099] wherein,

[0100]

[0101] wherein, V is the virtual volume of oil in the tank, V i , V j , V m , V n are the virtual volumes of oil at i, j, m, n points respectively, a, b are the lengths of the rectangle formed by i, j, m, n points, x is the lateral inclination angle, and y is the longitudinal inclination angle.

[0102] S3, based on the calculation model of VCF15 at 15℃ in the ISO-91 / 1 international standard, the iterative calculation method, and the type of oil carried by the vehicle-mounted oil tank, the volume correction coefficient of the oil at 20℃ is calculated according to the temperature of the oil in the tank obtained before and after unloading at the oil station (which can be measured by the temperature sensor arranged in the oil tank).

[0103] Specifically, the specific method for calculating the volume correction coefficient of the oil at 20℃ is as follows:

[0104] The calculation model of VCF15 at 15℃ in the ISO-91 / 1 international standard is represented as:

[0105] VCF15 = exp[-α 15 ΔT(1+0.8α 15 ΔT)] (3)

[0106] wherein, VCF15 is the volume correction coefficient of the oil at the standard temperature of 15℃, α 15 is the volume expansion coefficient of the oil at the standard temperature of 15℃, and ΔT is the difference between the current temperature and the standard temperature of 15℃;

[0107] Given the density of the oil at 20℃ ρ 20 , unit: Kg / m 3 , there is the equation:

[0108]

[0109] wherein, ρ 15 is the density of the oil at 15℃, unit: Kg / m 3 ;

[0110] From equation (3) and equation (4), we have:

[0111]

[0112] ρ 15 is calculated by using the iterative calculation method, and the process is as follows: ①ρ 20= p 15 ; 2 p' 15 = p 20 + 0.05; 3 if abs(p 15 - p' 15 )> = 0.0001, then use to calculate a 15 , where K0, K1, A are constants; 4 p 15 = p' 15 , and calculate p 15 according to equation 5; 5 repeat the calculation and compare according to step 3 until the required calculation accuracy is reached.

[0113] When the oil temperature in the tank is t, at temperature t, there is:

[0114]

[0115] In the formula, p t is the density of the oil at temperature t, and VCF20 is the volume correction factor of the oil at 20°C;

[0116] From equation (6), we get:

[0117]

[0118] VCF20 is calculated from equation (7).

[0119] S4, multiply the virtual volume of the oil in the tank obtained in step S2 by the volume correction factor obtained in step S3 to obtain the standard volume of the oil at 20°C.

[0120] S5, perform non-linear regression analysis on the standard tank volume table of the vehicle-mounted oil tank to obtain the standard volume characteristic data of the oil tank at no inclination angle.

[0121] S6, based on the improved advance and retreat method, calculate the liquid level height corresponding to the standard volume of the oil in the vehicle-mounted oil tank at 20°C before and after unloading at the oil station at no inclination angle, and obtain the true standard volume of the oil in the tank before and after unloading at the oil station according to the standard volume characteristic data at no inclination angle.

[0122] Specifically, referring to Figure 5 , the specific method for calculating the liquid level height corresponding to the standard volume of the oil in the vehicle-mounted oil tank at 20°C before and after unloading at the oil station at no inclination angle based on the improved advance and retreat method is as follows:

[0123] (1) Take the initial search step aS, set the initial liquid level height a3, calculate the function value according to equation (8) to get E3 = f(a3), and set kk = 0, equation (8) is expressed as:

[0124]

[0125] wherein p i , i = 1, 2, 3,..., 8 are the volume characteristic coefficients obtained when all the inclination angles of the vehicle-mounted oil tank are zero; V 20 is the standard volume of the vehicle-mounted oil tank at 20°C, unit: liter; h is the oil height, unit: mm;

[0126] (2) Set the liquid level height α = α3+ αs, calculate the function value according to formula (8), obtain E = f(α), and set kk = kk + 1;

[0127] (3) If E × E3> 0, compare the sizes of E and E3; if |E| < |E3| arbitrarily, set αs= 2.0 × αs, α3= α, E3= E, and go to step (2); if |E| > |E3|, set αs= -αs, and go to step (2); if E × E3≤ 0, go to step (4);

[0128] (4) Set α l = min{α, α3}, α r = max{α, α3}, E l = min{E, E3}, E r = min{E, E3};

[0129] (5) Set Calculate the function value according to formula (8), obtain E = E(α); if E × E3> 0, set E l = E, α l = α, kk = kk + 1; otherwise, set E r = E, α r = α, kk = kk + 1;

[0130] (6) If α r - α l ≥ 0.01, go to step (5); otherwise, stop the calculation, and obtain the liquid level height α of the oil in the vehicle-mounted oil tank at 20°C when all the inclination angles of the vehicle-mounted oil tank are zero

[0131] S7, subtract the real standard volume of the oil in the vehicle-mounted oil tank after unloading from the real standard volume of the oil in the vehicle-mounted oil tank before unloading, obtain the real standard volume of the oil unloaded at the oil station; subtract the standard volume of the oil unloaded at the oil station at 20°C from the real standard volume of the oil unloaded, obtain the unloading loss and gain amount of the vehicle-mounted oil tank; divide the unloading loss and gain amount of the vehicle-mounted oil tank by the real standard volume of the oil unloaded, obtain the unloading loss and gain rate of the vehicle-mounted oil tank.

[0132] Specifically, the calculation method of the standard volume of the oil unloaded at the oil station at 20°C is as follows: multiply the volume of the oil unloaded at the oil station by the volume correction coefficient obtained in step S3 to obtain the standard volume of the oil unloaded at the oil station at 20°C.

[0133] In a specific embodiment, the above-mentioned test method further comprises the following steps: calculating the average value of the oil unloading loss and gain during the operation period according to the data during the operation period, then determining the correction value of the liquid level height according to the standard volume characteristic data when there is no inclination, and correcting the measured liquid level height according to the correction value, and recalculating the oil unloading loss and gain of the vehicle-mounted oil tank according to the corrected liquid level height. By recalculating the oil unloading loss and gain of the vehicle-mounted oil tank according to the corrected liquid level height, the calculation accuracy of the oil unloading loss and gain of the vehicle-mounted oil tank is further improved.

[0134] Specifically, the specific method for correcting the liquid level height is as follows: calculating the average value of the oil unloading loss and gain during the operation period according to the data during the operation period; performing linear fitting on the standard volume characteristic data within the set range when there is no inclination to obtain the slope of the fitted straight line; the ratio of the average value of the oil unloading loss and gain to the slope is the correction value of the liquid level height, if the correction value is negative, it indicates that the liquid level height is too small, then the corrected liquid level height = original liquid level height of the oil + |correction value|, if the correction value is positive, it indicates that the liquid level height is too large, then the corrected liquid level height = original liquid level height of the oil - correction value.

[0135] The above-mentioned monitoring method of the present application establishes a three-dimensional mathematical model according to the oil tank drawings, obtains the corresponding relationship between the volume and the liquid level height of the oil tank at different inclination angles, and further obtains the volume characteristic data of the oil tank. Based on the oil temperature, the transverse inclination angle, the vertical inclination angle and the liquid level height of the oil tank at the oil station, the virtual volume of the oil in the oil tank at the real-time temperature before and after unloading at the oil station is calculated according to the volume characteristic data of the oil tank. The volume compensation coefficient of the oil at the real-time temperature is iteratively calculated according to the real-time temperature of the oil in the oil tank. Based on the virtual volume and the volume compensation coefficient, the standard volume of the oil in the oil tank at 20℃ is obtained. The liquid level height at no inclination corresponding to the standard volume of the oil in the oil tank before and after unloading at the oil station is calculated based on the improved forward and backward method, and the true standard volume of the oil in the oil tank is obtained according to the standard volume characteristic data of the oil tank volume calibration data (calibrated volume at no inclination). The unloading loss and gain of the oil transportation process is calculated according to the true standard volume of the oil in the tank before and after unloading and the standard volume of the unloaded oil at 20℃ measured at the oil station. The calculation result of the unloading loss and gain of the above-mentioned monitoring method of the present application is accurate, which meets the expected target requirement of the fuel transportation industry: the unloading loss and gain rate of a single time is not more than 0.5%, and the monthly average unloading loss and gain rate is not more than 0.1%, which solves the dynamic measurement problem of unloading loss and gain that has plagued the industry for many years.

[0136] Referring to Figure 2 The present application also provides a vehicle-mounted oil tank unloading loss and gain monitoring system based on standard volume characteristics, which is used to realize the above-mentioned vehicle-mounted oil tank unloading loss and gain monitoring method, and comprises:

[0137] A model construction module 1 is used to construct a three-dimensional mathematical model of the oil tank based on the oil tank drawings (seeFigure 3

[0138] a characteristic data acquisition module 2, configured to acquire tank volume data of the tank under different working conditions based on a three-dimensional mathematical model of the tank, and perform nonlinear regression analysis on the tank volume data to obtain tank volume characteristic data under different working conditions; and perform nonlinear regression analysis on a standard tank volume table of the tank to obtain standard volume characteristic data of the tank without inclination angle;

[0139] a tank data acquisition device 3, configured to acquire a longitudinal inclination angle, a transverse inclination angle, an original liquid level height of oil, and a tank oil temperature of the tank before and after oil unloading at the oil station;

[0140] a virtual volume calculation module 4, configured to calculate, based on a unit function interpolation method and the tank volume characteristic data under different working conditions, virtual volumes of oil in the tank before and after oil unloading at the oil station according to the longitudinal inclination angle, the transverse inclination angle, and the original liquid level height of oil of the tank before and after oil unloading at the oil station;

[0141] a volume correction coefficient calculation module 5, configured to calculate, based on an iterative calculation method and a type of oil carried by the tank, a volume correction coefficient of oil at 20°C according to the tank oil temperature of the tank before and after oil unloading at the oil station based on a calculation model of VCF 15 at 15°C in the ISO-91 / 1 international standard;

[0142] a standard volume calculation module 6, configured to multiply the virtual volume of oil in the tank calculated by the virtual volume calculation module and the volume correction coefficient calculated by the volume correction coefficient calculation module to obtain a standard volume of oil at 20°C;

[0143] a real standard volume calculation module 7, configured to calculate, based on an improved advance and retreat method, a liquid level height without inclination angle corresponding to a standard volume of oil in the tank at 20°C before and after oil unloading at the oil station, and obtain real standard volumes of oil in the tank before and after oil unloading at the oil station according to the standard volume characteristic data without inclination angle;

[0144] a profit and loss calculation module 8, configured to subtract the real standard volume of oil in the tank after oil unloading from the real standard volume of oil in the tank before oil unloading to obtain a real standard volume of unloaded oil at the oil station, subtract a standard volume of the unloaded oil at 20°C from a standard volume of the unloaded oil measured at the oil station to obtain an unloading loss and gain amount of the tank, and divide the unloading loss and gain amount of the tank by the real standard volume of the unloaded oil to obtain an unloading loss and gain rate of the tank.

[0145] Specifically, the calculation method of the standard volume of the unloaded oil at 20°C measured at the oil station is that the volume of the unloaded oil measured at the oil station is multiplied by the volume correction coefficient obtained in step S3 to obtain the standard volume of the unloaded oil at 20°C measured at the oil station.

[0146] Referring to​Figure 4 The isochromatic surface shown in the figure represents the value of the volume at the same liquid level height, and the liquid level height (for example, 1600 mm) of point P is obtained by the liquid level meter, and the volume of the oil at point P is calculated by interpolation of the volumes of i, j, m, and n. Based on this principle, specifically, the specific method for calculating the virtual volume of the oil in the vehicle-mounted oil tank before and after unloading at the oil station by the virtual volume calculation module is as follows:

[0147] The virtual volume of the oil in the tank is calculated by interpolation of the volumes of the arbitrary four points i, j, m, and n of the rectangle formed by the original liquid level height of the oil at different working conditions.

[0148]

[0149] wherein,

[0150]

[0151] In the formula, V is the virtual volume of the oil in the tank, V i , V j , V m , and V n are the virtual volumes of the oil at points i, j, m, and n, respectively, a and b are the lengths of the sides of the rectangle formed by points i, j, m, and n, x is the transverse inclination angle, and y is the longitudinal inclination angle.

[0152] Specifically, the specific method for calculating the volume correction coefficient of the oil at 20°C by the volume correction coefficient calculation module is as follows:

[0153] The calculation model of VCF15 at 15°C in the ISO-91 / 1 international standard is represented as follows:

[0154] VCF15 = exp[-α 15 ΔT(1 + 0.8α 15 ΔT)] (3)

[0155] In the formula, VCF15 is the volume correction coefficient of the oil at the standard temperature of 15°C, α 15 is the volume expansion coefficient of the oil at the standard temperature of 15°C, and ΔT is the difference between the current temperature and the standard temperature of 15°C.

[0156] Given the density of the oil at 20°C ρ 20 , unit: Kg / m 3 , there is the equation:

[0157]

[0158] In the formula, ρ 15 is the density of the oil at 15°C, unit: Kg / m 3 ; and

[0159] From formulas (3) and (4), we get:

[0160]

[0161] Calculate ρ using iterative calculation method 15 The process is as follows: ①ρ 20 =ρ 15 ;②ρ' 15 =ρ 20 +0.05; ③ If abs(ρ 15 -ρ' 15 If )>=0.0001, then use Calculate α 15 Where K0, K1, and A are all constants; ④ρ 15 =ρ' 15 And calculate ρ according to Equation 5. 15 ⑤ Repeat the calculation and compare it with step 3 until the required calculation accuracy is achieved.

[0162] When the temperature of the oil in the tank is t, at temperature t we have:

[0163]

[0164] In the formula, ρ t Let be the density of the oil at temperature t, and VCF20 be the volume correction factor for the oil at 20℃.

[0165] From formula (6):

[0166]

[0167] VCF20 is calculated using formula (7).

[0168] Specifically, see Figure 5 The actual standard volume calculation module, based on an improved forward and backward method, calculates the liquid level height without tilt angle corresponding to the standard volume of oil in the vehicle's tank at 20°C before and after unloading at the gas station. The specific method is as follows:

[0169] (1) Take the initial search step size αs, set the initial liquid level height to α3, calculate the function value according to formula (8), obtain E3=f(α3), and set kk=0. Formula (8) is expressed as:

[0170]

[0171] In the formula, p i ,i=1,2,3,...,8 represents the volumetric characteristic coefficients obtained when all tilt angles of the vehicle-mounted fuel tank are zero; V 20is the standard volume of the tank at 20℃, unit: L; h is the oil height, unit: mm;

[0172] (2) Set liquid level height α = α3 + αs, calculate the function value according to formula (8), get E = f(α), and set kk = kk + 1;

[0173] (3) If E × E3 > 0, compare the size of E and E3; if |E| < |E3|, set αs = 2.0 × αs, α3 = α, E3 = E, and go to step (2); if |E| > |E3|, set αs = -αs, and go to step (2); if E × E3 ≤ 0, go to step (4);

[0174] (4) Set α l = min{α, α3}, α r = max{α, α3}, E l = min{E, E3}, E r = min{E, E3};

[0175] (5) Set Calculate the function value according to formula (8), get E = E(α); if E × E3 > 0, set E l = E, α l = α, kk = kk + 1; otherwise, set E r = E, α r = α, kk = kk + 1;

[0176] (6) If α r - α l ≥ 0.01, go to step (5); otherwise, stop calculation, get the liquid level height of the oil in the tank at 20℃ when all the inclination angles of the tank are zero

[0177] In a specific embodiment, continuing to refer to Figure 2 The monitoring system further comprises a correction module 9, which calculates the average value of the oil unloading loss and gain during the operation according to the data during the operation, then determines the correction value of the liquid level height according to the standard volume characteristic data when there is no inclination angle, and corrects the measured liquid level height according to the correction value, so as to recalculate the oil unloading loss and gain of the tank according to the corrected liquid level height. By recalculating the oil unloading loss and gain of the tank according to the corrected liquid level height, the calculation accuracy of the oil unloading loss and gain of the tank is further improved.

[0178] Specifically, the specific method for correcting the liquid level height is: according to the data during operation, calculating the average value of the oil unloading loss and gain during operation; performing linear fitting on the volume characteristic data of the oil tank volume calibration data within the set range when there is no inclination, to obtain the slope of the fitting straight line; the ratio of the average value of the oil unloading loss and gain to the slope is the correction value of the liquid level height, if the correction value is negative, it indicates that the liquid level height is too small, then the corrected liquid level height = original liquid level height of the oil + |correction value|, if the correction value is positive, it indicates that the liquid level height is too large, then the corrected liquid level height = original liquid level height of the oil - correction value.

[0179] In a specific embodiment, the oil tank data acquisition device includes a liquid level instrument and a temperature sensor, both of which are arranged in the oil tank body, the liquid level instrument is used to monitor the transverse inclination, vertical inclination and liquid level height of the oil in the oil tank, and the temperature sensor is used to monitor the oil temperature of the oil in the oil tank. In the present application, both the liquid level instrument and the temperature sensor use existing instruments on the market.

[0180] The above-mentioned monitoring system of the present application establishes a three-dimensional model according to the oil tank drawings, obtains the corresponding relationship between the volume and the liquid level height of the oil tank at different inclinations, and then obtains the volume characteristic data of the oil tank. Based on the oil temperature, transverse inclination, vertical inclination and liquid level height of the oil tank at the oil station, the virtual volume of the oil in the oil tank at the real-time temperature before and after unloading at the oil station is calculated according to the volume characteristic data of the oil tank. The volume compensation coefficient of the oil at the real-time temperature is iteratively calculated according to the real-time temperature of the oil in the oil tank. Based on the virtual volume and the volume compensation coefficient, the standard volume of the oil in the oil tank at 20℃ is obtained. The liquid level height at no inclination corresponding to the standard volume of the oil in the oil tank before and after unloading at the oil station is calculated based on the improved advance and retreat method, and the true standard volume of the oil in the oil tank is obtained according to the standard volume characteristic data of the oil tank volume calibration data (volume calibrated at no inclination). The unloading loss and gain of this oil transportation process is calculated according to the true standard volume of the oil in the tank before and after unloading and the standard volume of the oil unloaded at the oil station at 20℃. The calculation result of the unloading loss and gain of the above-mentioned monitoring system of the present application is accurate, which meets the expected target requirement of the fuel transportation industry: the unloading loss and gain rate of a single time is not more than 0.5%, and the monthly average unloading loss and gain rate is not more than 0.1%, solving the dynamic measurement problem of unloading loss and gain that has plagued the industry for many years.

[0181] It should be noted that the above-mentioned unloading loss and gain monitoring method and system of the present application can also be applied to the monitoring of oil receiving loss and gain according to the same principle. When monitoring the oil receiving loss and gain, the above-mentioned unloading loss and gain monitoring method and system need to be modified accordingly. Specifically as follows:

[0182] For the oil receiving loss and gain monitoring method, refer to Figure 8The steps thereof are basically the same as the oil unloading loss and gain monitoring method, and the difference from the oil unloading loss and gain monitoring method is that, since the oil receiving loss and gain is monitored, the parameters obtained are before and after the oil receiving in the oil depot, the volume of the oil in the tank at the oil depot is calculated, and finally the oil receiving loss and gain is obtained. That is: S2, based on the longitudinal inclination, the transverse inclination and the original liquid level height of the vehicle-mounted oil tank at the oil depot before and after the oil receiving in the oil depot, the volume of the oil in the tank at the oil depot is calculated based on the unit function interpolation method and the oil tank volume characteristic data under different working conditions; S3, based on the temperature of the oil in the tank before and after the oil receiving in the oil depot, the volume correction coefficient of the oil at 20°C is calculated based on the calculation model of VCF 15 at 15°C in the ISO-91 / 1 international standard, the iterative calculation method and the type of the oil in the vehicle-mounted oil tank; S6, based on the improved advance and retreat method, the standard volume of the oil in the tank at 20°C is calculated, and the true standard volume of the oil in the tank before and after the oil receiving in the oil depot is obtained according to the standard volume characteristic data without inclination; S7, the true standard volume of the oil in the tank before the oil receiving is subtracted from the true standard volume of the oil in the tank after the oil receiving, and the true standard volume of the oil received in the oil depot is obtained; the true standard volume of the oil received is subtracted from the standard volume of the oil received in the oil depot at 20°C, and the oil receiving loss and gain of the vehicle-mounted oil tank is obtained; the oil receiving loss and gain of the vehicle-mounted oil tank is divided by the true standard volume of the oil received, and the oil receiving loss and gain rate of the vehicle-mounted oil tank is obtained. Specifically, the calculation method of the standard volume of the oil received in the oil depot at 20°C is: multiplying the volume of the oil received in the oil depot by the volume correction coefficient obtained in step S3 to obtain the standard volume of the oil received in the oil depot at 20°C. Similarly, the correction step in the oil receiving loss and gain monitoring method is: calculating the average value of the oil receiving loss and gain during the operation period according to the data during the operation period, then determining the correction value of the liquid level height according to the standard volume characteristic data without inclination, and correcting the measured liquid level height according to the correction value, and recalculating the oil receiving loss and gain of the vehicle-mounted oil tank according to the corrected liquid level height. The oil receiving loss and gain monitoring method can realize the monitoring of the oil receiving loss and gain.

[0183] For the oil receiving loss and gain monitoring system, its structure is the same as the oil unloading loss and gain monitoring system, and the difference between the oil receiving loss and gain monitoring system and the oil unloading loss and gain monitoring system is that, in the oil receiving loss and gain monitoring system, the oil tank data acquisition device is configured to acquire the longitudinal inclination, the transverse inclination and the original liquid level height of the vehicle-mounted oil tank when the vehicle-mounted oil tank is in the oil depot before and after the oil receiving of the oil depot, and is configured to acquire the oil temperature in the vehicle-mounted oil tank before and after the oil receiving of the oil depot. The virtual volume calculation module is configured to calculate the virtual volume of the oil in the vehicle-mounted oil tank when the vehicle-mounted oil tank is in the oil depot based on the longitudinal inclination, the transverse inclination and the original liquid level height of the vehicle-mounted oil tank when the vehicle-mounted oil tank is in the oil depot before and after the oil receiving of the oil depot, the unit function interpolation method and the oil tank volume characteristic data in different working conditions. The volume correction coefficient calculation module is configured to calculate the volume correction coefficient of the oil at 20°C based on the oil temperature in the vehicle-mounted oil tank before and after the oil receiving of the oil depot, the calculation model of VCF 15 at 15°C in the ISO-91 / 1 international standard, the iterative calculation method and the type of the oil carried by the vehicle-mounted oil tank. The real standard volume calculation module is configured to calculate the standard volume of the oil in the vehicle-mounted oil tank at 20°C corresponding to the liquid level height without inclination before and after the oil receiving of the oil depot based on the improved advance and retreat method, and to obtain the real standard volume of the oil in the vehicle-mounted oil tank before and after the oil receiving of the oil depot based on the standard volume characteristic data without inclination. The loss and gain calculation module is configured to obtain the real standard volume of the oil received by the oil depot by subtracting the real standard volume of the oil in the vehicle-mounted oil tank after the oil receiving from the real standard volume of the oil in the vehicle-mounted oil tank before the oil receiving. The loss and gain of the oil received by the vehicle-mounted oil tank is obtained by subtracting the standard volume of the oil received by the oil depot at 20°C from the real standard volume of the oil received by the oil depot. The loss and gain rate of the oil received by the vehicle-mounted oil tank is obtained by dividing the loss and gain of the oil received by the vehicle-mounted oil tank by the real standard volume of the oil received by the oil depot. Specifically, the calculation method of the standard volume of the oil received by the oil depot at 20°C is that the standard volume of the oil received by the oil depot at 20°C is obtained by multiplying the volume of the oil received by the oil depot by the volume correction coefficient obtained in step S3. The correction module is configured to calculate the average value of the oil receiving loss and gain during the operation period based on the data during the operation period, to determine the correction value of the liquid level height based on the standard volume characteristic data without inclination, and to correct the measured liquid level height based on the correction value, so as to recalculate the oil receiving loss and gain of the vehicle-mounted oil tank based on the corrected liquid level height. The oil receiving loss and gain can be monitored by the above oil receiving loss and gain monitoring system.

[0184] The effects of the above monitoring method and system will be described below in combination with an embodiment.

[0185] Embodiment: The oil tank of an oil transport vehicle has two compartments, namely No. 1 compartment and No. 2 compartment. Table 1 shows the operation data of No. 1 compartment, and Table 2 shows the operation data of No. 2 compartment. The oil products transported by the two compartments within a certain period of time are shown in the second column of Table 1 and Table 2. The oil temperature collected by the temperature sensor is shown in the fourth column and the eighth column of Table 1 and Table 2. The inclination and the liquid level height collected by the liquid level gauge are shown in the fifth to seventh columns and the ninth to eleventh columns of Table 1 and Table 2.

[0186] Table 1

[0187]

[0188] Table 2

[0189]

[0190] Table 3

[0191]

[0192]

[0193] Table 4

[0194]

[0195]

[0196] From the results of the profit and loss calculation of Table 3 and Table 4, it can be seen that there is a large calculation deviation in No. 1 warehouse and No. 2 warehouse, and the deviations are all in one direction; the calculation value of No. 1 warehouse is smaller, and the average is about 147.0 liters smaller; the calculation value of No. 2 warehouse is larger, and the average is about 79.5 liters larger.

[0197] The main reason for the deviation is that the height calibration of the liquid level instrument is problematic. Therefore, the readings of the liquid level instrument are compensated, and the compensation method is: with the help of the data of the oil transport vehicle running for a period of time, the average value of the oil unloading loss and gain and the average value of the oil receiving loss and gain are calculated; the standard tank volume characteristic data within a certain range (1300-1700 mm) of the standard tank volume data is linearly fitted, and the slope of the volume fitting straight line of No. 1 warehouse is about 12.8 (see Figure 6 ), and the slope of the volume fitting straight line of No. 2 warehouse is about 13.5 (see Figure 7 ); according to the average value of the oil unloading loss and gain and the slope of the fitting line, the correction value of the height reading of the liquid level instrument is calculated, and the correction value of No. 1 warehouse is -147.0 / 12.8=-11.5 (i.e. the height reading of the liquid level instrument of No. 1 warehouse is 11.5 mm less), and the correction value of No. 2 warehouse is 79.5 / 13.5=5.9 (i.e. the height reading of the liquid level instrument of No. 2 warehouse is 5.9 mm more). According to the average value of the oil receiving loss and gain and the slope of the fitting line, the correction value of the height reading of the liquid level instrument is calculated, and the correction value of No. 1 warehouse is -144.7 / 12.8=-11.3 (i.e. the height reading of the liquid level instrument of No. 1 warehouse is 11.3 mm less), and the correction value of No. 2 warehouse is 77.1 / 13.5=5.7 (i.e. the height reading of the liquid level instrument of No. 2 warehouse is 5.7 mm more). The correction value is added to the volume calculation, and the oil unloading loss and gain and the oil receiving loss and gain results calculated from the oil transport vehicle running data are shown in Table 5 and Table 6.

[0198] Table 5

[0199]

[0200]

[0201] Table 6

[0202]

[0203]

[0204] The above examples are used to explain the present application, but not to limit the present application, any modification and change made to the present application within the spirit and protection scope of the claims, all fall into the protection scope of the present application.

Claims

1. A method for monitoring the loss and gain of oil from a vehicle-mounted oil tank based on standard volume characteristics, characterized by, The specific steps are: S1, based on the oil tank drawing construction of oil tank three-dimensional mathematical model to obtain the oil tank volume data in different working conditions, and carries out nonlinear regression analysis, obtains the oil tank volume characteristic data in different working conditions; S2, according to the longitudinal inclination, transverse inclination and oil original liquid level of the vehicle-mounted oil tank obtained before and after unloading at the oil station, based on the unit function interpolation method and the oil tank volume characteristic data in different working conditions, the virtual volume of the oil in the vehicle-mounted oil tank before and after unloading at the oil station is calculated; S3. Based on the temperature of the fuel inside the vehicle's fuel tank obtained before and after unloading at the gas station, and according to the ISO-91 / 1 international standard of 15°C... The calculation model, iterative calculation method, and type of oil carried by the vehicle-mounted oil tanker were used to calculate the volume correction factor of the oil at 20℃. S4, the virtual volume of the oil in the tank obtained in step S2 is multiplied by the volume correction coefficient obtained in step S3 to obtain the standard volume of the oil at 20 DEG C; S5, the standard tank volume table of the vehicle-mounted oil tank is subjected to nonlinear regression analysis to obtain the standard volume characteristic data of the oil tank without inclination; S6, based on the improved advance and retreat method, the standard volume of the oil in the vehicle-mounted oil tank at 20 DEG C corresponding to the liquid level height without inclination before and after unloading at the oil station is calculated, and the true standard volume of the oil in the tank before and after unloading at the oil station is obtained according to the standard volume characteristic data without inclination; The specific method for calculating the standard volume of the oil in the vehicle-mounted oil tank at 20 DEG C corresponding to the liquid level height without inclination before and after unloading at the oil station based on the improved advance and retreat method is: (1) Take the initial search step αs , set the initial value of the liquid level , calculate the function value according to formula (8), get , and set , formula (8) is expressed as: （8） wherein is the volume characteristic factor for a tank with all inclination angles equal to zero; is the standard volume of the tank at 20°C, in liters; is the height of the oil, in mm; (2) Set the liquid level height , according to formula (8) to calculate the function value, get , and set ; (3) if then compare and ; if then set , , and go to step (2); if then set and go to step (2); if then go to step (4); (4) set , , , ; (5) set , the function value is calculated according to formula (8), and ; if , set , , ; otherwise, set , , ; (6) If , go to step (5); otherwise, stop the calculation and obtain the liquid level height of the oil in the tank at 20℃ when all the inclination angles of the tank are zero ; S7, the true standard volume of the oil in the tank before unloading is subtracted from the true standard volume of the oil in the tank after unloading to obtain the true standard volume of the unloaded oil at the oil station; The true standard volume of the unloaded oil is subtracted from the standard volume of the unloaded oil at 20 DEG C measured at the oil station to obtain the loss and gain of the vehicle-mounted oil tank during unloading; the loss and gain of the vehicle-mounted oil tank during unloading is divided by the true standard volume of the unloaded oil to obtain the loss and gain rate of the vehicle-mounted oil tank during unloading.

2. The method for monitoring the loss and gain of the oil unloaded from the vehicle-mounted oil tank based on the standard volume characteristics according to claim 1, characterized in that, Further comprising the following steps: According to the data during operation, the average value of the unloading loss and gain during operation is calculated, then the correction value of the liquid level height is determined according to the standard volume characteristic data without inclination, and the measured liquid level height is corrected according to the correction value, and the unloading loss and gain of the vehicle-mounted oil tank is recalculated according to the corrected liquid level height.

3. The method for monitoring the loss and gain of the oil unloaded from the vehicle-mounted oil tank based on the standard volume characteristics according to claim 2, characterized in that, The specific method for correcting the liquid level height is: according to the data during operation, the average value of the unloading loss and gain during operation is calculated; the standard volume characteristic data within the set range without inclination is subjected to linear fitting to obtain the slope of the fitting straight line; the ratio of the average value of the unloading loss and gain to the slope is the correction value of the liquid level height, if the correction value is negative, it indicates that the liquid level height is too small, then the corrected liquid level height = oil original liquid level height + | correction value |, if the correction value is positive, it indicates that the liquid level height is too large, then the corrected liquid level height = oil original liquid level height - correction value.

4. The method for monitoring the loss and gain of the oil unloaded from the vehicle-mounted oil tank based on the standard volume characteristics according to claim 1, characterized in that, In step S2, the specific method for calculating the virtual volume of oil in the vehicle-mounted oil tank before and after unloading at the gas station is as follows: Take any four points from the volumetric characteristic data under different operating conditions, where the original oil level height forms a rectangle. , , , The volume is interpolated to obtain the virtual volume of oil inside the tank as follows: （1） Wherein, （2） wherein is the virtual volume of oil in the tank, , , , are respectively , , , the virtual volumes of oil at the four points, , is , , , the length of the rectangle formed by the four points, is the lateral tilt angle, is the longitudinal tilt angle.

5. The method for monitoring the loss and gain of the oil unloaded from the vehicle-mounted oil tank based on the standard volume characteristics according to claim 1, characterized in that, In step S3, the specific method for calculating the volume correction coefficient of the oil at 20 DEG C is: ISO-91 / 1 international standard at 15°C VCF The calculation model for 15 is represented as: （3） In the formula, is the volume correction factor of the oil at the standard temperature of 15°C, is the volume expansion factor of the oil at the standard temperature of 15°C, is the difference between the current temperature and the standard temperature of 15°C. Density of the oil at 20°C in Kg / m 3 with equation: （4） wherein is the density of the oil at 15°C in Kg / m 3 ; From formula (3) and formula (4): （5） Using an iterative calculation method to calculate ; When the oil temperature in the tank is at a temperature there is: （6） wherein is the density of the oil at a temperature of 15°C, is the volume correction factor of the oil at 20°C; From formula (6): （7） The formula (7) is calculated by .

6. A system for monitoring the loss and gain of oil in a vehicle-mounted oil tank based on a standard volume characteristic, for implementing the method for monitoring the loss and gain of oil in a vehicle-mounted oil tank according to any one of claims 1 to 5, characterized by, Including: The model construction module is used for constructing the oil tank three-dimensional mathematical model based on the oil tank drawing; The characteristic data acquisition module acquires the oil tank volume data under different working conditions based on the three-dimensional mathematical model of the oil tank, and performs nonlinear regression analysis on the oil tank volume data to obtain the oil tank volume characteristic data under different working conditions; and performs nonlinear regression analysis on the standard tank volume table of the vehicle-mounted oil tank to obtain the standard volume characteristic data of the oil tank without inclination angle; The oil tank data acquisition device is used to acquire the longitudinal inclination angle, the transverse inclination angle, the original liquid level height of oil and the oil temperature in the tank of the vehicle-mounted oil tank before and after oil unloading at the oil station; The virtual volume calculation module calculates the virtual volume of the oil in the tank of the vehicle-mounted oil tank before and after oil unloading at the oil station based on the unit shape function interpolation method and the oil tank volume characteristic data under different working conditions according to the longitudinal inclination angle, the transverse inclination angle and the original liquid level height of oil of the vehicle-mounted oil tank acquired before and after oil unloading at the oil station; The volume correction coefficient calculation module calculates the volume correction coefficient of the oil at 20℃ based on the oil temperature in the tank obtained before and after the oil is unloaded at the oil station, the calculation model of 15℃ in the ISO-91 / 1 international standard, the iterative calculation method, and the type of the oil carried by the tank truck. ​ The standard volume calculation module multiplies the virtual volume of the oil in the tank calculated by the virtual volume calculation module and the volume correction coefficient calculated by the volume correction coefficient calculation module to obtain the standard volume of the oil at 20°C; The real standard volume calculation module calculates the liquid level height without inclination angle corresponding to the standard volume of the oil in the tank of the vehicle-mounted oil tank at 20°C before and after oil unloading at the oil station based on the improved advance and retreat method, and obtains the real standard volume of the oil in the tank before and after oil unloading at the oil station according to the standard volume characteristic data without inclination angle; The profit and loss calculation module obtains the real standard volume of the unloaded oil at the oil station by subtracting the real standard volume of the oil in the tank after oil unloading from the real standard volume of the oil in the tank before oil unloading, obtains the oil unloading loss and gain amount of the vehicle-mounted oil tank by subtracting the standard volume of the unloaded oil at 20°C measured by the oil station from the real standard volume of the unloaded oil, and obtains the oil unloading loss and gain rate of the vehicle-mounted oil tank by dividing the oil unloading loss and gain amount of the vehicle-mounted oil tank by the real standard volume of the unloaded oil.

7. The standard volume property based on-board tank unloading gain and loss monitoring system as claimed in claim 6, wherein, The correction module calculates the average value of the oil unloading loss and gain during the operation period according to the data during the operation period, determines the correction value of the liquid level height according to the standard volume characteristic data without inclination angle, and corrects the measured liquid level height according to the correction value to recalculate the oil unloading loss and gain of the vehicle-mounted oil tank according to the corrected liquid level height.

8. The vehicle-mounted oil tank unloading benefit and loss monitoring system based on standard volume characteristics according to claim 6, characterized in that, The specific method for the virtual volume calculation module to calculate the virtual volume of the oil in the tank of the vehicle-mounted oil tank before and after oil unloading at the oil station is as follows: The four points are taken from the rectangular arbitrary four points of the original liquid level height of the oil material in the volume characteristic data at different working conditions , , , The virtual volume of the oil material in the tank is obtained by interpolation calculation （1） Wherein, （2） wherein is the virtual volume of oil in the tank, , , , are respectively , , , the virtual volume of oil at the four points, , is , , , the length of the rectangle formed by the four points, is the lateral tilt angle, is the longitudinal tilt angle.

9. The vehicle-mounted oil tank unloading benefit and loss monitoring system based on standard volume characteristics according to claim 6, characterized in that, The specific method for the volume correction coefficient calculation module to calculate the volume correction coefficient of the oil at 20°C is as follows: ISO-91 / 1 international standard at 15°C VCF The calculation model for 15 is represented as: （3） wherein is the volume correction factor of the oil at the standard temperature of 15°C, is the volume expansion factor of the oil at the standard temperature of 15°C, is the difference between the current temperature and the standard temperature of 15°C; Density of the oil at 20°C in Kg / m 3 , with equation: （4） wherein is the density of the oil at 15°C in Kg / m 3 ; From formula (3) and formula (4), we have: （5） Using an iterative calculation method to calculate ; When the oil temperature in the tank is at a temperature there is: （6） wherein is the density of the oil at a temperature of 15 °C, is the volume correction factor of the oil at 20 °C; From formula (6), we have: （7） The formula (7) is calculated by .

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