Heliostat energy flow scheduling method and system based on absorber heating curve

Abstract

The present application belongs to the technical field of heliostat energy flow scheduling, and specifically relates to a heliostat energy flow scheduling method and system based on a heat absorber heating curve. According to a model of the heat absorber, a curve of the temperature change of the heat absorber in each working condition is drawn. According to the temperature curve, the heat absorber parameters and meteorological conditions are converted into an energy curve. According to the energy curve, the heliostats in the mirror field are scheduled to meet the energy requirements of various working conditions of the heat absorber, so as to ensure that the temperature parameters of the heat absorber can be kept within a safe range under various working conditions, start-stop and preheating conditions, and at the same time, the light spot remains uniform, reducing the possibility of local overheating.

Description

Technical Field

[0001] The present application belongs to the technical field of heliostat energy flow scheduling, and specifically relates to a heliostat energy flow scheduling method and system based on a heat absorber heating curve. Background Art

[0002] The working conditions of the tower molten salt photothermal power generation mirror field receiver are generally divided into preheating, salt melting, temperature increase, power increase, salt thinning and other working conditions. The current energy flow scheduling method is basically based on the total power demand of the receiver under different working conditions or the heat flux density on the receiver surface for energy scheduling. Both methods can meet the energy demand of the receiver under different working conditions, but do not consider the parameter requirements of the receiver under various working conditions, and do not fully consider the factors that affect the safe operation and life of the receiver. For example, the parameter requirements of the receiver for the temperature gradient, the over-temperature pipe burst due to the rapid temperature rise, and the risk of molten salt freezing and blocking due to the rapid temperature drop in winter, all of which have an adverse effect on the safe operation and life of the receiver, and the uneven light spot during the energy scheduling process will also cause local over-temperature or local temperature drop too fast. Summary of the invention

[0003] The present invention proposes a method for scheduling the energy of heliostats according to the temperature curve of the absorber under different working conditions, ensuring that the temperature parameters of the absorber can be kept within a safe range under various working conditions, start-stop and preheating conditions, while maintaining uniformity of the light spot and reducing the possibility of local overheating. The technical solution is:

[0004] A method for scheduling energy flow of a heliostat based on a heat absorber heating curve comprises the following steps:

[0005] S1. Get the current absorber tube screen temperature and solar radiation , meteorological parameters, heliostat location information;

[0006] S2. Load the design parameters of the heat absorber, including the temperature, temperature rise parameters, energy change rate, heat receiving area of ​​the heat absorber, and heat absorber panel division at each operating stage;

[0007] S3. Calculate the temperature curve and the corresponding energy curve in the preheating stage according to the preheating stage requirements, the current absorber temperature and meteorological conditions;

[0008] S4. According to the temperature curve and energy demand curve, Interpolate the curve for each time interval to obtain Time interval heat sink temperature rise Energy power required ;

[0009] S5. Update the optical efficiency and power of all heliostats according to the ray tracing method;

[0010] S6.Yes The target points of the heliostats in the small rectangular face screen are sorted uniformly. This sorting only needs to be done once and can be used directly in the future;

[0011] S7. dispatching the heliostat selected in S6 to focus and track the sun.

[0012] Preferably, in step S2, the heat absorber panel is divided into A small rectangular face screen. Different absorbers require different energies for different areas of the absorber face screen at different stages.

[0013] Preferably, in step S3, according to the design parameters of the heat absorber: preheating to a temperature , temperature rise gradient per minute during the preheating phase , draw the time t-temperature curve T curve, the fitting formula is:

[0014] ;

[0015] is the current temperature of the heat absorber; through heat transfer theory, we can calculate the temperature of the heat absorber when the temperature rises Energy, draw temperature curve and energy demand curve; according to the classic heat transfer formula, make a fitting estimate, the formula is as follows:

[0016] ;

[0017] in: Temperature rise of the absorber Energy required;

[0018] is the specific heat of the absorber tube panel;

[0019] is the heat exchange area of ​​the absorber;

[0020] is the convective heat transfer coefficient;

[0021] is the absorption rate of the absorber tube panel surface.

[0022] Preferably, in step S4, each small rectangular screen sets a power coefficient ,ensure ,in is the average power value of each small rectangular panel, and After confirmation, you can find For the The energy power required for a small rectangular panel.

[0023] Preferably, in step S5, the first The heliostat is Power on a small rectangular panel , the calculation formula is as follows:

[0024] ;

[0025] Refers to normal direct irradiance;

[0026] Refers to The reflecting area of ​​the heliostat;

[0027] Refers to Whether the heliostat is blocked by the heat absorbing tower; is equal to 0 or 1; When , it means that the heliostat is blocked. When , it indicates that the heliostat is not blocked;

[0028] Refers to The cosine efficiency of each heliostat;

[0029] Refers to The spillover efficiency of each heliostat;

[0030] Refers to The shading efficiency of a heliostat caused by the surrounding heliostats;

[0031] Refers to Atmospheric projection efficiency of a heliostat.

[0032] Preferably, in step S6, the steps of uniformity sorting of the target points of the heliostat are as follows:

[0033] S61. Get the The coordinates of all target points in a small rectangular panel , the target points correspond one to one with the heliostats;

[0034] S62. Setting uniformity standards , the initial value can be set to The average density value of a small rectangular panel area;

[0035] S63. Pre-sort the target points and calculate the score of each target point, which is the distance to the nearest point and the uniformity standard The difference is used for subsequent sorting;

[0036] S64. Perform a preliminary sorting of the target points according to the scores from large to small through a sorting algorithm ;

[0037] S65. Select the first point as the seed point and add it to the final sorting result set middle;

[0038] S66. For Each unselected target point , detection and The distance of all selected points in ;if Greater than or equal to the current uniformity standard , then Add to ;

[0039] S67. Dynamic adjustment, based on the distribution of the currently selected points and the remaining candidate points :Calculate the selected point , if the number of selected points is greater than the threshold And the uniformity meets the requirements, try to gradually increase ; If the uniformity of the selected points does not meet the requirements and the number of remaining candidate points is less than the threshold , should be reduced To increase the selection of candidate points.

[0040] A heliostat energy flow scheduling system based on a heat absorber heating curve comprises a data acquisition module, a data processing module and an output module; wherein:

[0041] Data acquisition module: obtain the current absorber tube screen temperature and solar radiation , meteorological parameters, heliostat location information;

[0042] Data processing module: Calculate the optical efficiency of the heliostat to obtain the The heliostat is Power on a small rectangular panel and uniformity sorting of the target points of the heliostats;

[0043] Output module: Visualize the results as required.

[0044] Compared with the prior art, the present invention has the following beneficial effects:

[0045] The present invention starts from the perspective of the heat absorber, converts the heat absorber temperature parameter requirements into energy requirements, and then performs uniform focusing scheduling of the heliostat, which can avoid heat absorber failures caused by excessively fast temperature gradients or temperature change rates, such as pipe bursts due to excessively rapid temperature rises, freezing and blockage due to excessively rapid temperature drops, and other abnormal problems, thereby increasing the safety and life of the heat absorber. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Figure 1 This is the flow chart of this application.

[0047] Figure 2 It is the control curve diagram. DETAILED DESCRIPTION

[0048] In order to enable those skilled in the art to better understand the technical solution of the present invention, the present invention is further described below in conjunction with the accompanying drawings and specific implementation methods.

[0049] A method for scheduling energy flow of a heliostat based on a heat absorber heating curve comprises the following steps:

[0050] S1. Get the current absorber tube screen temperature and solar radiation , meteorological parameters, and heliostat location information.

[0051] S2. Load the design parameters of the heat sink, including the temperature, temperature rise parameters, energy change rate, heat sink heating area, and heat sink panel division at each operating stage; the heat sink panel is divided into A small rectangular face screen. It should be noted that different absorbers may require different energies for different areas of the absorber face screen at different stages.

[0052] S3. Calculate the temperature curve and the corresponding energy curve in the preheating stage according to the preheating stage requirements, the current absorber temperature and meteorological conditions;

[0053] Note that the preheating stage uses empty tube preheating, and other working conditions involve the specific heat of the medium in the tube and the medium flow rate. The curve generation needs to consider the design parameter requirements of the temperature rise gradient of the heat absorber. According to the design parameters of the heat absorber: preheating reaches temperature , temperature rise gradient per minute during the preheating phase Draw the time-temperature curve, and the fitting formula is:

[0054] ;

[0055] is the current temperature of the heat absorber;

[0056] Through heat transfer theory, we can find out the temperature rise of the heat absorber. energy, draw the temperature curve and energy demand curve.

[0057] According to the classical heat transfer formula, the fitting estimate is as follows:

[0058] ;

[0059] Temperature rise of the absorber Energy required; is the specific heat of the absorber tube panel; is the heat exchange area of ​​the absorber; is the convective heat transfer coefficient; (affected by wind speed), this coefficient needs to be tested according to the on-site conditions to obtain a more accurate relationship formula between wind speed and ambient temperature; is the absorption rate of the absorber tube panel surface.

[0060] For example, according to the environmental operating point (1.6℃, 5.6m / s wind speed), the initial temperature of the absorber is 1.6℃. The temperature rise gradient is , the temperature rise curve of the preheating process and the energy input are drawn as follows Figure 2 shown.

[0061] S4. According to the temperature curve and energy demand curve, the time interval Interpolate the curve for each time interval to obtain Time interval heat sink temperature rise Energy power required .

[0062] At this time, it should be noted that different absorbers may require different energy for different areas of the absorber faceplate at different stages. For example, the energy requirements of the small rectangular faceplate at the top or bottom of the absorber are different from those of the small rectangular faceplate in the middle of the absorber. The total energy is not evenly distributed to Small rectangular panels, so the power coefficient can be set for each small rectangular panel Generally, requirements are given when designing the heat absorber to ensure ,in is the average power value of each small rectangular panel, and After confirmation, you can find out For the The energy power required for a small rectangular panel.

[0063] S5. Update the optical efficiency and power of all heliostats according to the ray tracing method.

[0064] The first The heliostat is Power on a small rectangular panel :

[0065] ;

[0066] Refers to normal direct irradiance;

[0067] Refers to The reflecting area of ​​the heliostat;

[0068] Refers to Whether the heliostat is blocked by the heat absorbing tower; is equal to 0 or 1; When , it means that the heliostat is blocked. When , it indicates that the heliostat is not blocked;

[0069] Refers to Cosine efficiency of a heliostat; Cosine efficiency = cosine value of incident light × cosine value of reflected light;

[0070] The cosine value of the incident light refers to the cosine value of the angle between the sunlight and the mirror normal, while the cosine value of the reflected light refers to the cosine value of the angle between the reflected light and the mirror normal. Alternatively, only the cosine value of the incident light may be considered.

[0071] Refers to The overflow efficiency of a heliostat is the loss caused by the fact that the aiming point of the heliostat is too close to the edge of the heat absorbing plane or the divergence of the light itself causes a part of the light reflected by the mirror to not fall on the heat absorbing surface. The proportion of the lost part to the total amount of mirror reflection is the overflow efficiency. The calculation of the overflow efficiency is usually based on the Monte Carlo ray tracing method, which simulates the propagation path of the light reflected by the heliostat in space to determine whether the light intersects with the absorber. If the light is not in the absorber, it is regarded as overflow light, and the number of overflow light of the corresponding heliostat increases. By counting all reflected light, the total amount of overflow light can be obtained, and then the overflow efficiency can be calculated.

[0072] Refers to The shading efficiency of a heliostat is caused by the influence of the surrounding heliostats. The light reflected from the part of the mirror surface on the heliostat cannot reach the heat absorption surface due to the shading of the heliostats in front of it or around it. The ratio of this part of the mirror surface to the area of ​​the heliostat is called the shading efficiency. This parameter can also be estimated in advance through the simulation of the mirror field model. The shading efficiency is estimated according to the shading time and shading area of ​​the heliostat. The formula is: shading efficiency = shading time / sunshine time × shading area / heliostat area.

[0073] Refers to The atmospheric projection efficiency of a heliostat is used to indirectly evaluate the atmosphere's ability to transmit sunlight through the solar radiation data (such as total radiation, direct radiation, and scattered radiation) measured by the meteorological station in the mirror field.

[0074] S6.Yes The target points of the heliostats in the small rectangular face screen are sorted uniformly. This sorting only needs to be done once and can be used directly in the future;

[0075] The steps for uniformity sorting of the heliostat target points are as follows:

[0076] S61. Get the The coordinates of all target points in a small rectangular panel , the target points correspond one to one with the heliostats;

[0077] S62. Setting uniformity standards , the initial value can be set to The average density value of a small rectangular panel area;

[0078] S63. Pre-sort the target points and calculate the score of each target point, which is the distance to the nearest point and the uniformity standard The difference is used for subsequent sorting;

[0079] S64. Perform a preliminary sorting of the target points according to the scores from large to small through a sorting algorithm ;

[0080] S65. Select the first point as the seed point and add it to the final sorting result set middle;

[0081] S66. For Each unselected target point , detection and The distance of all selected points in ;if Greater than or equal to the current uniformity standard , then Add to ;

[0082] S67. Dynamic adjustment, based on the distribution of the currently selected points and the remaining candidate points :Calculate the selected point , if the number of selected points is greater than the threshold And the uniformity meets the requirements, try to gradually increase ; If the uniformity of the selected points does not meet the requirements and the number of remaining candidate points is less than the threshold , should be reduced To increase the selection of candidate points.

[0083] A heliostat energy flow scheduling system based on a heat absorber heating curve comprises a data acquisition module, a data processing module and an output module; wherein:

[0084] Data acquisition module: obtain the current absorber tube screen temperature and solar radiation , meteorological parameters, heliostat location information;

[0085] Data processing module: Calculate the optical efficiency of the heliostat to obtain the The heliostat is Power on a small rectangular panel and uniformity sorting of the target points of the heliostats;

[0086] Output module: Visualize the results as required.

[0087] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention. It should be noted that similar numbers and letters represent similar items in the following drawings. Therefore, once an item is defined in one drawing, it does not need to be further defined and explained in the subsequent drawings.

Claims

1. A heliostat energy flow scheduling method based on a heat absorber heating curve, characterized in that: The following steps are involved: S1. Obtain the current absorber tube screen temperature, solar radiation DNI, meteorological parameters, and heliostat position information; S2. Load the design parameters of the heat absorber, including the temperature, temperature rise parameters, energy change rate, heat receiving area of ​​the heat absorber, and heat absorber panel division at each operating stage; S3. Calculate the temperature curve and the corresponding energy curve in the preheating stage according to the preheating stage requirements, the current absorber temperature and meteorological conditions; S4. According to the temperature curve and the energy demand curve, the curve is interpolated with a time interval of Δt to obtain the energy power P required for the temperature rise ΔT on the heat absorber per time interval Δt; S5. Update the optical efficiency and power of all heliostats according to the ray tracing method; S6. sorting the target points of the heliostats in the m small rectangular panels according to their uniformity, and the uniformity sorting is performed once and then used directly; The steps for uniformity sorting of the heliostat target points are as follows: S61. Obtain the coordinates q (x, y, z) of all target points of the j-th small rectangular panel, where the target points correspond to the heliostats one by one; S62. Setting uniformity standards min , the initial value is set to the average density value of the j-th small rectangular panel area; S63. Pre-sort the target points and calculate the score of each target point, which is the distance to the nearest point and the uniformity standard d min The difference is used for subsequent sorting; S64. Preliminary sorting of the target points W is performed by a sorting algorithm according to the scores from large to small; S65. Select the first point as the seed point and add it to the final sorting result set Z; S66. For each unselected target point q in W i , detect the distance d to all selected points in Z; if d is greater than or equal to the current uniformity standard d min Then q i Add to Z; S67.d min Dynamic adjustment: adjust d according to the distribution of the currently selected points and the remaining candidate points min :Calculate the d of the selected point min If the number of selected points is greater than the threshold Ω and the uniformity meets the requirements, try to gradually increase d min ; If the uniformity of the selected points does not meet the requirements and the number of remaining candidate points is less than the threshold Should reduce d min To increase the selection of candidate points; S7. dispatching the heliostat selected in S6 to focus and track the sun.

2. The heliostat energy flow scheduling method based on the absorber heating curve according to claim 1 is characterized in that: In step S2, the absorber panel is divided into m small rectangular panels, and different absorbers require different energies for different areas of the absorber panel at different stages.

3. The heliostat energy flow scheduling method based on the absorber heating curve according to claim 1 is characterized in that: In step S3, according to the design parameters of the heat absorber: preheating to reach temperature T max , Temperature rise gradient per minute in the preheating stage K t , draw the time t-temperature curve T curve, the fitting formula is: T=K t t+T0 T0 is the current temperature of the heat absorber; Calculate the energy of the absorber at a temperature rise of ΔT through the heat transfer formula, and draw the temperature curve and energy demand curve; According to the classical heat transfer formula, the fitting estimate is as follows: Q=ΔT·λ·A·h·f. Where: Q is the energy required for the absorber to rise in temperature ΔT; λ is the specific heat of the absorber tube panel; A is the heat exchange area of ​​the absorber; h is the convective heat transfer coefficient; f is the absorption rate of the absorber tube panel surface.

4. The heliostat energy flow scheduling method based on the absorber heating curve according to claim 1 is characterized in that: In step S4, each small rectangular screen sets a power coefficient x j ,ensure in is the average power value of each small rectangular screen, x j After and P are determined, we can find is the energy power required for the jth small rectangular panel.

5. The heliostat energy flow scheduling method based on the absorber heating curve according to claim 1, characterized in that: In step S5, the power p of the i-th heliostat on the j-th small rectangular panel is calculated according to the optical efficiency of the heliostat. ij , p ij =S i *DNI*T i *C i *M i *A i *I i DNI refers to direct normal irradiance; S i refers to the reflection area of ​​the i-th heliostat; T i Refers to whether the i-th heliostat is blocked by the heat absorption tower; T i =0 or 1, C i refers to the cosine efficiency of the ith heliostat; I i refers to the spillover efficiency of the i-th heliostat; M i It refers to the shading efficiency of the i-th heliostat caused by the influence of surrounding heliostats; A i Refers to the atmospheric projection efficiency of the i-th heliostat.

6. A heliostat energy flow scheduling system based on a heat absorber heating curve, using the heliostat energy flow scheduling method based on a heat absorber heating curve according to any one of claims 1 to 5, characterized in that: It includes a data acquisition module, a data processing module and an output module; wherein: Data acquisition module: obtain the current absorber tube screen temperature, solar radiation DNI, meteorological parameters, and heliostat position information; Data processing module: Calculate the power p of the i-th heliostat on the j-th small rectangular panel according to the optical efficiency of the heliostat ij and uniformity sorting of the target points of the heliostats; Output module: Visualize the results as required.

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