Photovoltaic direct current direct drive molten salt heating device and molten salt heat storage system

Abstract

The application relates to the technical field of heat storage regulation, in particular to a photovoltaic direct-current electric direct-drive molten salt heating device and a molten salt heat storage system. The heating device comprises a data acquisition module, a first judgment module, a second judgment module, a first amplitude determination module and a second amplitude determination module. The specific execution steps are as follows: when the temperature change rate meets the preset stable condition, it is judged whether to stop PID regulation; when the temperature change rate does not meet the preset stable condition or PID regulation is carried out, the trend intensity, the trend direction value and the temperature direction value are determined respectively; when the signs of the trend direction value and the temperature direction value are consistent, the parameter adjustment amplitude of the PID regulation is determined by combining the temperature change rate at the starting moment in the PID regulation temperature and the trend intensity; otherwise, the parameter adjustment amplitude is determined according to the difference between the PID regulation temperature and the target regulation temperature. The application improves the accuracy of PID regulation parameter adjustment in the molten salt temperature regulation process.

Description

Technical Field

[0001] This invention relates to the field of thermal energy storage and regulation technology, specifically to a photovoltaic DC direct-drive molten salt heating device and a molten salt thermal energy storage system. Background Technology

[0002] The photovoltaic DC direct-drive molten salt heating and thermal storage system is a novel energy system that deeply couples photovoltaic power generation with molten salt thermal storage. Its core principle is to bypass the DC-AC-DC power conversion process, directly utilizing the DC electricity generated by the photovoltaic modules to drive a dedicated molten salt electric heater. This converts electrical energy into thermal energy in the molten salt and stores it in a high-temperature molten salt tank. When energy output is needed, the heat exchange system converts the molten salt's thermal energy into steam or directly supplies it to the thermal load, achieving "storage-on-demand release" of electrical energy. Its core components include: a photovoltaic array, a DC molten salt electric heater, a dual-tank molten salt thermal storage unit, a heat exchange / power generation system, and an intelligent control system.

[0003] Energy coupling and system integration issues exist in molten salt thermal energy storage, making it difficult to effectively control the output heat. Unstable heat affects multiple dimensions, including steam parameters, equipment safety, system efficiency, and production processes. For example, the hot rolling process in a steel plant requires a stable steam temperature of 25 degrees Celsius. Unstable temperatures impact equipment, necessitating real-time adjustments to production processes and related parameters, ultimately reducing production efficiency. Ensuring the stability of the supplied thermal energy is crucial, such as through temperature monitoring to provide a basis for temperature regulation. However, the analysis of thermal energy storage systems relies on the current system stability and the assessment of temperature stability. For instance, if the temperature is unstable, the transmitted control signals may not guarantee the stability of the thermal energy storage system. Furthermore, the actual control process takes time to manifest, making it prone to adjustment errors during molten salt temperature regulation. Summary of the Invention

[0004] To address the technical problem of potential adjustment errors during molten salt temperature regulation, this invention aims to provide a photovoltaic DC direct-drive molten salt heating device and a molten salt thermal storage system. The specific technical solution adopted is as follows: In a first aspect, embodiments of the present invention provide a photovoltaic DC direct-drive molten salt heating device, the method comprising: The data acquisition module is used to acquire the temperature difference between the molten salt temperature and the target temperature in the high-temperature storage tank of the thermal storage system, as well as the rate of temperature change of the molten salt temperature. The first judgment module is used to analyze the temperature change rate and temperature difference when the temperature change rate meets the preset stability conditions, and to determine whether to stop PID control. The second judgment module is used to determine the changes in the positive and negative segments of the temperature change rate curve when the temperature change rate does not meet the preset stability conditions or when PID control is performed; and to determine the trend intensity, trend direction value, and temperature direction value based on the temperature difference and the changes in the positive and negative segments. The first amplitude determination module is used to determine the control direction value by combining the temperature change rate at the initial and final moments in the PID control of temperature when the trend direction value and the temperature direction value have the same sign; and to determine the parameter adjustment amplitude of the PID control based on the control direction value and the trend intensity. The second amplitude determination module is used to determine the adjustment amplitude of the PID control parameters based on the difference between the PID-controlled temperature and the target controlled temperature when the signs of the trend direction value and the temperature direction value are inconsistent.

[0005] Furthermore, the analysis of temperature change rate and temperature difference to determine whether to stop PID control includes: When the temperature change rate at the current moment meets the preset stability condition, analyze the temperature change rate and temperature difference at historical moments to determine the target stability probability of the molten salt at the current moment; determine whether to stop PID control based on the target stability probability of the temperature.

[0006] Furthermore, the method for determining the positive and negative segments in the temperature change rate curve is as follows: Fit the temperature change rate curve based on the temperature change rate; The portion of the temperature change rate curve that is greater than 0 is taken as a positive segment; the portion of the temperature change rate curve that is less than 0 is taken as a negative segment.

[0007] Furthermore, the method for obtaining the trend strength is as follows: taking the change in the positive segment as the numerator, the sum of the change in the negative segment and the preset zero-prevention parameter as the denominator, and taking the corresponding ratio as the positive-negative change ratio; calculating the normalized value of the difference between the positive-negative change ratio and the preset constant as the trend strength.

[0008] Furthermore, the method for obtaining the trend direction value is as follows: when the trend strength is greater than 0, the trend direction value is 1; when the trend strength is equal to 0, the trend direction value is 0; when the trend strength is less than 0, the trend direction value is -1.

[0009] Furthermore, the method for obtaining the temperature direction value is as follows: When the temperature difference is greater than 0, the temperature relationship direction value is 1; when the temperature difference is equal to 0, the temperature relationship direction value is 0; when the temperature difference is less than 0, the temperature relationship direction value is -1. The proportion of positive and negative signs in the time series formed by the temperature relationship direction values ​​is obtained. When the proportion of positive signs is greater than the proportion of negative signs, the temperature direction value is 1; when the proportion of positive signs is less than the proportion of negative signs, the temperature direction value is -1.

[0010] Furthermore, determining the control direction value by combining the temperature change rates at the initial and final moments in the PID control of the temperature includes: Based on PID control technology, the PID-controlled temperature curve is obtained; Obtain the PID temperature change rate at the initial and final moments in the PID control temperature timing curve; When the signs of the PID temperature change rate at the initial and final times are the same, the PID temperature control is judged to be abnormal, and the control direction value is set to 1; when the signs of the PID temperature change rate at the initial and final times are different, the PID temperature control is judged to be normal, and the control direction value is -1; when at least one of the temperature change rates at the initial and final times is 0, the control direction value is 0.

[0011] Further, determining the parameter adjustment range of PID control based on the control direction value and trend strength includes: By performing negative correlation normalization mapping on the product of the absolute value of the trend strength and the value of the control direction, the parameter adjustment range of PID control can be obtained.

[0012] Furthermore, determining the adjustment range of the PID control parameters based on the difference between the PID-controlled temperature and the target controlled temperature includes: Obtain the PID-controlled temperature at the current moment; The temperature difference between the PID control temperature and the target control temperature is normalized and mapped to obtain the parameter adjustment range of the PID control.

[0013] In a second aspect, a photovoltaic DC direct-drive molten salt thermal energy storage system is provided, comprising: a memory and a processor; the memory is connected to the processor; the memory is used to store program instructions; the processor is used to execute the method of the first aspect or any possible implementation thereof when the program instructions are executed.

[0014] Thirdly, embodiments of the present invention provide a computer program product comprising: computer program code, which, when run on a computer, causes the computer to perform the method described in the first aspect or any possible implementation thereof.

[0015] Fourthly, embodiments of the present invention provide a computer-readable storage medium having a computer program stored thereon, which, when executed in a computer, causes the computer to perform the various possible implementations of the first aspect.

[0016] The embodiments of the present invention have at least the following beneficial effects: This invention monitors the molten salt temperature in a high-temperature storage tank and controls the molten salt output and reheating of the peak-shaving tank, thereby ensuring the stability of the high-temperature molten salt temperature and achieving molten salt heat storage. This invention combines the changing trends of the molten salt temperature with the trends of temperature regulation to determine whether the rate of temperature change meets the preset stable regulation. This is used to determine whether the current instability of the thermal storage system is within the scope of normal temperature regulation, thus enabling the determination of the adjustment parameters during PID control and further determining whether the system's operating state is normal. Attached Figure Description

[0017] To more clearly illustrate the technical solutions and advantages in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is a schematic diagram of a photovoltaic DC direct-drive molten salt heating device according to an embodiment of the present invention; Figure 2 This is a schematic diagram of a photovoltaic DC direct-drive molten salt thermal energy storage system provided in one embodiment of the present invention. Detailed Implementation

[0019] To further illustrate the technical means and effects adopted by the present invention to achieve the intended purpose, the following detailed description, in conjunction with the accompanying drawings and preferred embodiments, details the specific implementation, structure, features, and effects of a photovoltaic DC direct-drive molten salt heating device and molten salt thermal storage system proposed according to the present invention.

[0020] In the following description, different "one embodiment" or "another embodiment" do not necessarily refer to the same embodiment. Furthermore, specific features, structures, or characteristics in one or more embodiments may be combined in any suitable form.

[0021] In the description of the embodiments of the present invention, unless otherwise stated, " / " means "or". For example, A / B can mean A or B. The "and / or" in the text is merely a description of the relationship between related objects, indicating that there can be three relationships. For example, A and / or B can mean: A exists alone, A and B exist simultaneously, and B exists alone. In addition, in the description of the embodiments of the present invention, "multiple" means two or more.

[0022] Hereinafter, the terms "first" and "second" are used for descriptive purposes only and should not be construed as implying or suggesting relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature.

[0023] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0024] The embodiments of the present invention will now be described with reference to the accompanying drawings. Those skilled in the art will recognize that, with technological advancements and the emergence of new scenarios, the technical solutions provided by the embodiments of the present invention are also applicable to similar technical problems.

[0025] This invention provides a specific implementation method for a photovoltaic DC direct-drive molten salt heating device and a molten salt thermal energy storage system, applicable to molten salt heating and thermal energy storage scenarios. The invention includes a photovoltaic DC direct-drive molten salt heating device, which is the core connection unit of the photovoltaic-energy storage link. Its main function is to directly convert photovoltaic electrical energy into molten salt thermal energy, reducing energy loss. This device is directly coupled to a primary buffer tank to absorb photovoltaic DC power in real time, avoiding AC / DC conversion losses during photovoltaic power grid connection.

[0026] The invention also includes a photovoltaic DC direct-drive molten salt thermal energy storage system, which is the core of the "storage-heat-steam" process. This system includes molten salt medium, thermal energy storage structure, heat exchange equipment, etc., and solves the problems of low efficiency, large heat loss and unstable steam supply in traditional thermal energy storage.

[0027] The molten salt thermal energy storage system consists of three tanks: The first stage is a buffer tank, which converts photovoltaic DC power into heat energy to directly heat the molten salt inside. This buffer tank acts as a real-time energy storage unit, temporarily storing the heat generated by the photovoltaic system. Simultaneously, it absorbs photovoltaic energy, ensuring the stability of photovoltaic energy output and preventing sudden temperature changes in the molten salt due to large fluctuations in photovoltaic energy. The second stage is a peak-shaving tank, connected to the energy output of the first stage. This tank is also connected to a valley-electricity supplementary heating system to supplement the heat of the molten salt in the second stage, thus mitigating photovoltaic fluctuations through valley-electricity supply. The third stage is a high-temperature storage tank, where the molten salt from the second-stage peak-shaving tank is transported to maintain a constant temperature of 680 degrees Celsius. A dynamic heat flow distribution algorithm allocates the high-temperature molten salt from the third-stage storage tank to the heat exchanger according to demand. The heat exchanger ensures the stability of steam pressure and temperature.

[0028] In this embodiment of the invention, a high-temperature corrosion-resistant nickel-based alloy shell-and-tube heat exchanger is used, and a surface aluminizing process is employed to improve corrosion resistance. Under the conditions that the heat transfer coefficient is higher than 200 W / (m²·K) and the pressure drop on the molten salt side is less than 0.15 MPa, the molten salt-steam heat exchange efficiency is greater than 98%.

[0029] When photovoltaic power output exceeds the demand for molten salt heating, the excess electricity is fed back to the grid. The green electricity consumption ratio is tracked in real time through a blockchain-based green electricity traceability platform, providing data support for carbon accounting and green certificate revenue.

[0030] This invention addresses the pain points of traditional steam supply—characterized by "high carbon emissions, high energy consumption, and inefficient operation"—by integrating a photovoltaic DC direct-drive molten salt heating device with a molten salt thermal storage system. The core logic is: to smooth out photovoltaic fluctuations with a three-tiered thermal storage architecture, to achieve economical and low-carbon scheduling with efficient algorithms, and to support system optimization with comprehensive data acquisition, ultimately forming a zero-carbon solution encompassing "photovoltaic absorption, off-peak electricity peak shaving, high-efficiency thermal storage, and stable steam supply."

[0031] The following description, in conjunction with the accompanying drawings, details the specific scheme of the photovoltaic DC direct-drive molten salt heating device and molten salt thermal storage system provided by the present invention.

[0032] Please see Figure 1 The diagram illustrates a module schematic of a photovoltaic DC direct-drive molten salt heating device according to an embodiment of the present invention, which includes the following modules: The data acquisition module 10 is used to acquire the temperature difference between the molten salt temperature and the target temperature in the high-temperature storage tank of the thermal storage system, as well as the temperature change rate of the molten salt temperature.

[0033] The high-temperature chamber of the thermal storage system facilitates the conversion of molten salt and steam. To ensure stable heat conversion, a stable molten salt temperature and stable steam output are required. The regulation strategy at this time is as follows: First, calculate the temperature of the molten salt in the high-temperature chamber of the monitoring thermal storage system. With target temperature Differences It is used to determine whether the current molten salt needs to be heated or stored, ensuring the stability of the output molten salt temperature.

[0034] It should be noted that the molten salt needs to be heated when the temperature is too low, and heat storage is required when the temperature is too high. In this embodiment of the invention, the target temperature is 680°C. In other embodiments, the implementer may adjust this target temperature according to the actual situation.

[0035] The rate of change of molten salt temperature in the high-temperature chamber is determined and denoted as the temperature change rate. Specifically, the difference in molten salt temperature at different times in the time series is obtained, resulting in a temperature difference curve. The slope of the temperature difference curve at each moment is calculated as the rate of temperature change of the molten salt temperature. The rate of temperature change reflects the change in thermal energy.

[0036] The first judgment module 20 is used to analyze the temperature change rate and temperature difference when the temperature change rate meets the preset stability conditions, and to determine whether to stop PID control.

[0037] The preset stability condition is set to a temperature change rate of 0, that is, when At that time, the rate of temperature change meets the preset stability conditions.

[0038] When the temperature change rate at the current moment meets the preset stability condition, analyze the temperature change rate and temperature difference at historical moments to determine the target stability probability of the molten salt at the current moment, and determine whether to stop PID control based on the target stability probability.

[0039] when At this time, it indicates that the temperature of the molten salt in the high-temperature chamber is basically stable, but there may be temperature anomalies, such as the temperature stabilizing at 600 degrees, which is significantly different from the target temperature.

[0040] Furthermore, by analyzing the temperature change rate and temperature difference at historical moments, the target stability probability of the molten salt temperature at the current moment is determined: First, the target stability of the molten salt temperature in the high-temperature reservoir is determined by combining the temperature change rate and temperature difference. The smaller the temperature difference, the closer the molten salt temperature at previous historical moments is to the target temperature, which indicates higher stability of the molten salt temperature at the current moment and higher target stability of the molten salt temperature at the current moment. Therefore, temperature difference and target stability are negatively correlated. When the temperature change rate is smaller, the closer the molten salt temperature is to adjacent moments, which indicates better target stability of the molten salt temperature. Therefore, temperature change rate is also negatively correlated with target stability.

[0041] The target stability reflects whether the molten salt temperature of the current high-temperature chamber needs to be adjusted. The greater the target stability, the closer the molten salt temperature is to the target temperature. If the actual molten salt temperature is relatively stable, the target stability can be used to determine whether to stop the PID control.

[0042] In this embodiment of the invention, when Calculate the target stability for all times up to time t. Taking the molten salt temperature at time c as an example, calculate the corresponding target stability. The calculation formula is: Where norm is the normalization function; Let be the absolute value of the rate of temperature change of the molten salt at time c; Let be the temperature difference of the molten salt at time c; The function is the absolute value function. In this embodiment of the invention, norm can be a linear normalization function.

[0043] If the target stability remains high and consistent across multiple consecutive time points, it indicates that the PID control has achieved temperature stabilization of the molten salt, and PID control should be stopped in this case. If the stability is low, or if there are significant fluctuations in the timing stability, it indicates poor temperature stability of the molten salt, and PID control of the molten salt temperature in the high-temperature chamber is still required.

[0044] Therefore, further, if When analyzing the current time, taking the t-th time as the current time, the stability probability of the temperature target at the t-th time is determined based on the fluctuation of the target stability at historical times before the t-th time. The higher the stability probability of the temperature target, the more stable the corresponding temperature, and the greater the probability that PID control can be stopped.

[0045] The mean of the target stability of historical moments within a preset historical range at the current moment is used as the numerator, and the standard deviation of the target stability of historical moments within the preset historical range at the current moment is used as the denominator. The ratio of the numerator to the denominator is taken as the temperature target stability probability at the current moment. This temperature target stability probability is then positively correlated and normalized, and the mapped value is taken as the new temperature target stability probability. In this embodiment of the invention, the preset historical range is set to the previous 180 historical moments. In other embodiments, the implementer can adjust this reference preset historical range according to the time situation.

[0046] The temperature target stability probability reflects whether the current PID control process has reached stability. It is used to determine whether to stop the PID control of the molten salt temperature to ensure the stability of heat storage in the high-temperature storage chamber.

[0047] When the probability of temperature target stability is greater than or equal to the preset control threshold, PID control is stopped.

[0048] In this embodiment of the invention, the method for setting the preset control threshold is as follows: under multiple historical normal and stable conditions determined manually, the minimum value of the corresponding temperature target stability probability is calculated and used as the preset control threshold. It should be noted that stopping PID control refers to the implementer setting a set of special control parameters for the PID, under which the molten salt temperature in the high-temperature chamber can be balanced.

[0049] When the probability of temperature target stability is less than the preset control threshold, the PID parameters are adjusted, and the temperature change rate curve corresponding to the temperature change rate within the preset historical range at the current moment is input into the subsequent analysis of the second judgment module.

[0050] The second judgment module 30 is used to determine the change amount of the positive and negative segments in the temperature change rate curve when the temperature change rate does not meet the preset stability conditions or when PID control is performed; and to determine the trend intensity, trend direction value and temperature direction value based on the temperature difference, the change amount of the positive and negative segments.

[0051] When the rate of temperature change does not meet the preset stability condition, that is, when the rate of temperature change is not 0, it means that the current molten salt temperature has not reached a stable state.

[0052] When the first determination module 20 determines that PID control is being implemented, it indicates that the current molten salt temperature has not reached a stable state. Therefore, the second determination module 30 further analyzes the reason why the molten salt temperature has not reached a stable state.

[0053] A temperature change rate curve is fitted based on the temperature change rate. The horizontal axis of the temperature change rate curve represents the sampling time, and the vertical axis represents the temperature change rate at each sampling time.

[0054] The temperature change rate curve over time is segmented based on a zero value. The portion of the temperature change rate curve greater than 0 is designated as a positive segment, and the portion less than 0 is designated as a negative segment. The portions greater than 0 and less than 0 are allowed to be empty sets, meaning that either positive or negative segments are permitted to be absent. Positive segments indicate an increasing trend in the temperature change rate curve, while negative segments show the opposite increasing trend. If the temperature change rate curve is near 0, it indicates that the temperature remains stable.

[0055] Integrating the temperature change rate curves for both the positive and negative segments yields the changes in temperature change rate for each segment, denoted as [these two parts are not directly related to the previous sentence]. Under normal circumstances, if the molten salt temperature does not reach a stable state, it is usually due to inaccurate PID control parameters, causing an anomaly in the current control process, which is reflected in the molten salt temperature and results in abnormal heat storage. To quickly restore the abnormal state to normal, intervention in the PID control process is necessary.

[0056] If it is an abnormal PID control process, then the process itself has a certain trend. If there is a significant difference in the above changes, it indicates that the current molten salt temperature has a significant trend. Therefore, the ratio of the changes in the positive segment and the negative segment is determined as the positive-negative change ratio. The difference between the positive-negative change ratio and the preset constant is calculated as the trend strength, and the corresponding trend direction value and temperature direction value are obtained at the same time.

[0057] The method for obtaining the trend strength is as follows: The change in the positive segment is used as the numerator, and the sum of the change in the negative segment and the preset zero-prevention parameter is used as the denominator. The corresponding ratio is taken as the positive-negative change ratio. The normalized value of the difference between the positive-negative change ratio and the preset constant is calculated as the trend strength. In this embodiment of the invention, the preset constant is 1, and the preset zero-prevention parameter is 0.1. In this embodiment of the invention, the normalization function used when calculating the normalized value of the difference between the positive-negative change ratio and the preset constant is the hyperbolic tangent normalization function.

[0058] Trend direction value The method for obtaining the trend strength is as follows: when the trend strength is greater than 0, the trend direction value is 1; when the trend strength is equal to 0, the trend direction value is 0; when the trend strength is less than 0, the trend direction value is -1.

[0059] Temperature directional value The method for obtaining the temperature relationship direction value is as follows: when the temperature difference is greater than 0, the temperature relationship direction value is 1; when the temperature difference is equal to 0, the temperature relationship direction value is 0; when the temperature difference is less than 0, the temperature relationship direction value is -1; obtain the proportion of positive and negative signs in the time series formed by the temperature relationship direction values. When the proportion of positive signs is greater than the proportion of negative signs, the temperature relationship direction value is 1; when the proportion of positive signs is less than the proportion of negative signs, the temperature relationship direction value is -1.

[0060] The trend strength represents the increasing trend of the temperature change rate curve. A larger trend strength value, greater than 0, indicates a significant increase in the current temperature change, suggesting an anomaly in the current control process, and that this anomaly causes a greater change in the molten salt temperature. A smaller trend strength value, less than 0, indicates a significant increasing trend in the opposite direction of the current temperature difference. The corresponding direction is represented by the trend direction value.

[0061] The first amplitude determination module 40 is used to determine the control direction value by combining the temperature change rate at the initial and final moments in the PID control temperature when the signs of the trend direction value and the temperature direction value are consistent; and to determine the parameter adjustment amplitude of the PID control based on the control direction value and the trend intensity.

[0062] When the signs of the trend direction value and the temperature direction value are the same, that is... hour: The above explains that the current molten salt temperature direction is in the same direction as the temperature change direction, for example, if the current molten salt temperature is higher than the target temperature and the temperature is increasing. In this case, temperature control is a non-target control process, and temperature adjustment is performed in the opposite direction. The greater the difference between the molten salt temperature and the target temperature, and the greater the increase in temperature, the stronger the reverse adjustment needs to be.

[0063] Obtain the PID-controlled temperature at different historical moments within a preset historical range, and construct a PID-controlled temperature time-series curve in chronological order. Based on the PID-controlled temperature time-series curve, obtain the slopes corresponding to the initial and final moments within the preset historical range, which are used as the PID temperature change rates at the initial and final moments, respectively. and .

[0064] If they have the same slope direction, it indicates that there is an anomaly in the PID temperature control during that time period; otherwise, it indicates that the PID temperature control is normal and the current control has not reached a stable state.

[0065] In abnormal conditions, a larger adjustment to the PID parameters is required to ensure that subsequent temperature control meets the requirements of molten salt thermal storage, i.e., maintaining the molten salt temperature stably at 680 degrees Celsius. Conversely, in normal control conditions, the parameter adjustments are smaller, allowing for continued observation of the temperature while maintaining the current parameters to determine the temperature under equilibrium conditions and avoid over-regulation of the temperature.

[0066] Furthermore, by combining the temperature change rates at the initial and final moments in the PID temperature control, the control direction value is determined. Specifically: when the signs of the PID temperature change rates at the initial and final moments are the same, the PID temperature control is judged to be abnormal, and the control direction value is set to 1; when the signs of the PID temperature change rates at the initial and final moments are different, the PID temperature control is judged to be normal, and the control direction value is -1; when at least one of the temperature change rates at the initial and final moments is 0, the control direction value is 0. A control direction value of 1 indicates that the control is abnormal.

[0067] When the control direction value is 1, the stronger the trend of the molten salt temperature, the more serious the abnormal phenomenon is. Therefore, the required parameter adjustment range is also larger.

[0068] Conversely, when the control direction value is -1, the molten salt temperature is controlled towards the normal target temperature. At this time, the relevant parameters of the current PID can remain unchanged, so the required parameter adjustment range is smaller.

[0069] Based on the control direction value and trend strength, the parameter adjustment range of PID control is determined. More specifically, the product of the absolute value of the trend strength and the control direction value is negatively correlated and normalized to obtain the parameter adjustment range of PID control.

[0070] In some embodiments, the adjustment range of the PID control parameters The calculation formula is: Where v is the control direction value and d is the trend strength; if the adjustment range of this parameter is 0, it means that the current control parameter is maintained to control the temperature of the high-temperature tank and ensure the stability of the temperature.

[0071] The second amplitude determination module 50 is used to determine the parameter adjustment amplitude of PID control based on the difference between the PID-controlled temperature and the target controlled temperature when the signs of the trend direction value and the temperature direction value are inconsistent.

[0072] When the signs of the trend direction value and the temperature direction value are inconsistent, that is... hour: This situation indicates that the current direction of molten salt temperature change is opposite to the direction of temperature change. For example, the current molten salt temperature is higher than the target temperature, but the temporal trend of molten salt temperature change is towards the target molten salt temperature. This is within the normal PID control process and has not yet reached a steady state. In this case, the current PID control parameters can be maintained unchanged. To obtain the PID control temperature at the current moment, specifically, obtain the PID control temperature curve at this time. The temperature at which the system reaches stability under the given PID control parameters is taken as the PID control temperature in the stable state. .

[0073] The temperature difference between the PID control temperature and the target control temperature is normalized and mapped to obtain the parameter adjustment range of the PID control. Specifically, the difference between the theoretical PID control temperature and the target control temperature is calculated. ,in, The target control temperature refers to the temperature at which the molten salt temperature in the high-temperature chamber is stabilized at 680 degrees Celsius through PID control. It should be noted that due to heat transfer losses, the controlled temperature and the target temperature may not perfectly match. However, when the molten salt temperature remains stable, the corresponding controlled temperature also remains stable; otherwise, the temperature balance would be disrupted. The controlled temperature corresponding to a molten salt temperature of 680 degrees Celsius is denoted as the target control temperature. The greater the temperature difference, the greater the corresponding parameter adjustment range. Therefore, the parameter adjustment range in this case... for: .

[0074] Please see Figure 2 , Figure 2 This invention provides a photovoltaic DC direct-drive molten salt thermal storage system, which includes a memory 610 and a processor 620. The memory 610 is connected to the processor 620. The memory 610 is used to store program instructions. The processor 620 is used to implement a photovoltaic DC direct-drive molten salt heating device when the program instructions are executed.

[0075] Alternatively, the transmission medium may be a wired link, such as, but not limited to, coaxial cable, fiber optic cable and digital subscriber line, or a wireless link, such as, but not limited to, wireless Fidelity (WIFI), Bluetooth and mobile device networks.

[0076] It should be noted that the device provided in the above embodiments is only an example of the division of the above functional modules. In actual applications, the above functions can be assigned to different functional modules as needed, that is, the internal structure of the computer device can be divided into different functional modules to complete all or part of the functions described above.

[0077] In this embodiment of the invention, the device can be divided into functional modules according to the above method example. For example, each module can correspond to a separate function, or two or more functions can be integrated into one processing module. The integrated module can be implemented in hardware. It should be noted that the module division in this embodiment is illustrative and is only a logical functional division. In actual implementation, there may be other division methods.

[0078] When each module is divided according to its function, the device may also include a signal uploading module, a determination module, and an adjustment module. It should be noted that all relevant content of each step involved in the above method embodiments can be referenced from the functional descriptions of the corresponding functional modules, and will not be repeated here.

[0079] This invention also provides a computer-readable storage medium storing computer program code. When the computer program code is run on a computer, the computer executes the aforementioned method steps to implement the photovoltaic DC direct-drive molten salt heating device provided in the above embodiments.

[0080] This invention also provides a computer program product that, when run on a computer, causes the computer to perform the aforementioned steps to realize the photovoltaic DC direct-drive molten salt heating device provided in the above embodiments.

[0081] In this invention, the system, computer-readable storage medium, computer program product, or chip provided in the embodiments are all used to execute the corresponding methods described above. Therefore, the beneficial effects they achieve can be referred to the beneficial effects in the corresponding methods described above, and will not be repeated here. Through the above description of the embodiments, those skilled in the art will understand that, for the sake of convenience and brevity, only the division of the above functional modules is used as an example. In practical applications, the above functions can be assigned to different functional modules as needed, that is, the internal structure of the device can be divided into different functional modules to complete all or part of the functions described above. In the embodiments provided by this invention, it should be understood that the disclosed device and method can be implemented in other ways.

[0082] The device embodiments described above are merely illustrative. For example, the division of modules or units is only a logical functional division. In actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another device, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be through some interfaces; the indirect coupling or communication connection between devices or units may be electrical, mechanical, or other forms.

[0083] It should also be noted that, in this document, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or terminal device that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or terminal device. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or terminal device that includes said element.

[0084] It should be noted that the order of the above embodiments of the present invention is merely for descriptive purposes and does not represent the superiority or inferiority of the embodiments. The processes depicted in the accompanying drawings do not necessarily require a specific or sequential order to achieve the desired result. In some embodiments, multitasking and parallel processing are also possible or may be advantageous.

[0085] The various embodiments in this specification are described in a progressive manner. The same or similar parts between the various embodiments can be referred to each other. Each embodiment focuses on describing the differences from other embodiments.

[0086] The above content is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the protection scope of the present invention.

Claims

1. A photovoltaic DC direct-drive molten salt heating device, characterized in that, The device includes the following modules: The data acquisition module is used to acquire the temperature difference between the molten salt temperature and the target temperature in the high-temperature storage tank of the thermal storage system, as well as the rate of temperature change of the molten salt temperature. The first judgment module is used to analyze the temperature change rate and temperature difference when the temperature change rate meets the preset stability conditions, and to determine whether to stop PID control. The second judgment module is used to determine the changes in the positive and negative segments of the temperature change rate curve when the temperature change rate does not meet the preset stability conditions or when PID control is performed. Based on the temperature difference and the changes in positive and negative segments, the trend strength, trend direction value, and temperature direction value are determined respectively. The trend strength is obtained by using the change in the positive segment as the numerator, the sum of the change in the negative segment and a preset zero-prevention parameter as the denominator, and using the corresponding ratio as the positive-to-negative change ratio. The normalized value of the difference between the positive-to-negative change ratio and a preset constant is calculated as the trend strength. The trend direction value is determined by the trend strength. The temperature direction value is determined by the proportion of positive and negative signs in the time series of temperature relationship direction values ​​formed by the temperature difference. The first amplitude determination module is used to determine the control direction value by combining the positive and negative sign relationship of the temperature change rate at the initial and final moments in the PID control when the trend direction value and the temperature direction value have the same sign; and to determine the parameter adjustment amplitude of the PID control based on the control direction value and the trend intensity. The second amplitude determination module is used to determine the adjustment amplitude of the PID control parameters based on the difference between the PID-controlled temperature and the target controlled temperature when the signs of the trend direction value and the temperature direction value are inconsistent.

2. The photovoltaic DC direct-drive molten salt heating device according to claim 1, characterized in that, The analysis of temperature change rate and temperature difference to determine whether to stop PID control includes: When the temperature change rate at the current moment meets the preset stability condition, analyze the temperature change rate and temperature difference at historical moments to determine the target stability probability of the molten salt at the current moment; determine whether to stop PID control based on the target stability probability of the temperature. The method for obtaining the temperature target stability probability is as follows: take the mean of the target stability of historical times within the preset historical range at the current time as the numerator, take the standard deviation of the target stability of historical times within the preset historical range at the current time as the denominator, take the ratio of the numerator and denominator as the temperature target stability probability at the current time, and perform positive correlation normalization mapping on the temperature target stability probability, and take the mapped value as the new temperature target stability probability. The target stability The calculation formula is: Where norm is the normalization function; Let be the absolute value of the rate of temperature change of the molten salt at time c; Let be the temperature difference of the molten salt at time c; This is the function for taking the absolute value.

3. The photovoltaic DC direct-drive molten salt heating device according to claim 1, characterized in that, The method for determining the positive and negative segments in the temperature change rate curve is as follows: Fit the temperature change rate curve based on the temperature change rate; The portion of the temperature change rate curve that is greater than 0 is taken as a positive segment; the portion of the temperature change rate curve that is less than 0 is taken as a negative segment.

4. The photovoltaic DC direct-drive molten salt heating device according to claim 1, characterized in that, The method for obtaining the trend direction value is as follows: when the trend strength is greater than 0, the trend direction value is 1; When the trend strength is equal to 0, the trend direction value is 0; When the trend strength is less than 0, the trend direction value is -1.

5. The photovoltaic DC direct-drive molten salt heating device according to claim 1, characterized in that, The method for obtaining the temperature direction value is as follows: When the temperature difference is greater than 0, the temperature relationship direction value is 1; when the temperature difference is equal to 0, the temperature relationship direction value is 0; when the temperature difference is less than 0, the temperature relationship direction value is -1. The proportion of positive and negative signs in the time series formed by the temperature relationship direction values ​​is obtained. When the proportion of positive signs is greater than the proportion of negative signs, the temperature direction value is 1; when the proportion of positive signs is less than the proportion of negative signs, the temperature direction value is -1.

6. The photovoltaic DC direct-drive molten salt heating device according to claim 1, characterized in that, The determination of the control direction value by combining the temperature change rates at the initial and final moments in PID temperature control includes: Based on PID control technology, the PID-controlled temperature curve is obtained; Obtain the temperature change rate at the initial and final moments in the PID control temperature timing curve; When the signs of the temperature change rates at the initial and final times are the same, the PID temperature control is judged to be abnormal, and the control direction value is set to 1; when the signs of the temperature change rates at the initial and final times are different, the PID temperature control is judged to be normal, and the control direction value is -1; when at least one of the temperature change rates at the initial and final times is 0, the control direction value is 0.

7. The photovoltaic DC direct-drive molten salt heating device according to claim 1, characterized in that, The step of determining the parameter adjustment range of PID control based on the control direction value and trend strength includes: By performing negative correlation normalization mapping on the product of the absolute value of the trend strength and the value of the control direction, the parameter adjustment range of PID control can be obtained.

8. A photovoltaic DC direct-drive molten salt heating device according to claim 6, characterized in that, The step of determining the adjustment range of the PID control parameters based on the difference between the PID-controlled temperature and the target controlled temperature includes: Obtain the PID-controlled temperature at the current moment; The temperature difference between the PID control temperature and the target control temperature is normalized and mapped to obtain the parameter adjustment range of the PID control.

9. A photovoltaic DC direct-drive molten salt thermal energy storage system, characterized in that, include: Memory and processor; The memory is connected to the processor; The memory is used to store program instructions; The processor is configured to implement, when program instructions are executed, a photovoltaic DC direct-drive molten salt heating device according to any one of claims 1-8.

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