Power grid deep peak regulation and peak regulation method and system using fused salt heat storage

Abstract

The invention provides a power grid deep peak regulation and peak regulation method and system using fused salt heat storage, and relates to the technical field of power grids, and the method comprises the steps: building a fused salt heat storage system, receiving power grid load prediction data and renewable energy power generation prediction data, and according to the power grid load prediction data and the renewable energy power generation prediction data, carrying out peak regulation on the power grid deep peak regulation and peak regulation. Determining peak regulation requirements of the power grid; according to the peak regulation requirement of the power grid, a fused salt heat storage system operation strategy is formulated, and the fused salt heat storage system operation strategy comprises a heat storage mode and a heat release mode; monitoring the load change of the power grid in real time, and starting a peak adjustment mode when detecting that the load of the power grid reaches a preset peak threshold value; in the peak adjusting mode, the flow of the molten salt circulating pump is increased, the hot molten salt conveying rate is increased, meanwhile, the heat exchange efficiency of the molten salt heat exchanger is adjusted, and more high-temperature and high-pressure steam is generated; and controlling the steam turbine generator unit to increase the power generation power, and merging extra power into the power grid to realize power grid peak load adjustment.

Description

Technical Field

[0001] The present invention relates to power grid technology, and in particular to a method and system for deep peak regulation and peak regulation of a power grid using molten salt heat storage. Background Art

[0002] As the proportion of renewable energy in the power system continues to increase, the power grid is facing increasing peak load pressure and system stability challenges. Although traditional thermal power units have certain peak load regulation capabilities, due to their inherent technical characteristics, they are difficult to meet the needs of deep peak load regulation and rapid peak load regulation of the power grid. At the same time, the intermittent and volatile nature of renewable energy also brings new challenges to the safe and stable operation of the power grid. At present, the common power grid peak load regulation methods mainly include the following:

[0003] Thermal power generation peak load regulation: The load of the power grid is balanced by adjusting the output of thermal power generation units. However, the regulation speed of thermal power generation units is slow, and frequent deep peak load regulation will lead to reduced unit efficiency and shortened life.

[0004] Pumped storage: Use electricity during off-peak hours to pump water to a high reservoir, and release hydropower during peak hours. However, the construction of pumped storage power stations is limited by geographical conditions and requires a large initial investment.

[0005] Electrochemical energy storage: such as lithium-ion batteries, has the advantage of fast response speed, but large-scale applications still face problems such as high cost and limited cycle life.

[0006] Demand-side response: Balancing the supply and demand of the power grid by adjusting the electricity load, but it is difficult to implement and the adjustable capacity is limited.

[0007] In this context, molten salt heat storage technology has gradually attracted attention due to its large capacity, low cost, and environmental friendliness. The molten salt heat storage system can store excess electrical energy in the form of thermal energy and convert it back into electrical energy when needed, which has significant scale effects and economic advantages. However, the existing molten salt heat storage system is mainly used in the field of solar thermal power generation, and its potential in grid peak regulation and peak regulation has not yet been fully utilized.

[0008] At present, the molten salt heat storage system has the following problems in the peak load regulation application of power grid:

[0009] The system response speed is slow, and it is difficult to meet the needs of rapid grid regulation. The heat storage-power generation conversion efficiency needs to be improved, which affects the overall economy of the system. The coordinated control strategy with the grid is not perfect, and it is difficult to give full play to the regulation potential of the heat storage system. The system operation is not flexible enough, and it is difficult to adapt to the complex and changeable grid operation needs. There is a lack of specialized optimization design for deep peak regulation and peak regulation, and the system performance needs to be improved. Summary of the invention

[0010] The embodiments of the present invention provide a method and system for deep peak regulation and peak regulation of a power grid using molten salt heat storage, which can solve the problems in the prior art.

[0011] According to a first aspect of the embodiments of the present invention,

[0012] Provides a method for deep peak regulation and peak regulation of power grid using molten salt heat storage, including:

[0013] Establish a molten salt heat storage system, the molten salt heat storage system includes a hot molten salt storage tank, a cold molten salt storage tank, a molten salt heat exchanger and a molten salt circulation pump; the hot molten salt storage tank and the cold molten salt storage tank are connected through the molten salt circulation pump and the molten salt heat exchanger to form a molten salt circulation loop; receive power grid load forecast data and renewable energy power generation forecast data, and determine the power grid peak load demand according to the power grid load forecast data and the renewable energy power generation forecast data; formulate a molten salt heat storage system operation strategy according to the power grid peak load demand, the molten salt heat storage system operation strategy includes a heat storage mode and a heat release mode;

[0014] In the heat storage mode, the electric power during the off-peak period of the power grid or the period of surplus power generation from renewable energy is used to drive the electric heater to heat the molten salt, and the hot molten salt is stored in the hot molten salt storage tank; in the heat release mode, the hot molten salt in the hot molten salt storage tank is pumped into the molten salt heat exchanger to perform heat exchange with the working fluid to generate high-temperature and high-pressure steam; the high-temperature and high-pressure steam is transported to the steam turbine generator set to generate electricity, and the generated electricity is incorporated into the power grid to achieve deep peak regulation of the power grid;

[0015] Monitor the changes in the grid load in real time, and start the peak regulation mode when it is detected that the grid load reaches a preset peak threshold; in the peak regulation mode, increase the flow rate of the molten salt circulation pump, improve the hot molten salt delivery rate, and adjust the heat exchange efficiency of the molten salt heat exchanger to generate more high-temperature and high-pressure steam; control the steam turbine generator set to increase the power generation, and integrate the additional electricity into the grid to achieve grid peak load regulation.

[0016] In an optional embodiment,

[0017] Receiving grid load forecast data and renewable energy generation forecast data, and determining grid peak load demand according to the grid load forecast data and the renewable energy generation forecast data includes:

[0018] Receive grid load forecast data and renewable energy power generation forecast data, calculate a net load curve, wherein the time resolution of the net load curve is 15 minutes and the forecast duration is 24 hours; calculate the first-order derivative and the second-order derivative of the net load curve, and identify the inflection point and the extreme point of the net load curve;

[0019] Select Daubechies wavelet basis function, perform 5-layer wavelet decomposition on the net load curve, and obtain low-frequency approximate coefficients and detail coefficients of 5 different scales; reconstruct the fluctuation components of 5 different scales by using the low-frequency approximate coefficients and the detail coefficients of 5 different scales; calculate the standard deviation of the fluctuation components of 5 different scales, and determine the peak-shaving thresholds of 5 different scales according to the preset adjustment coefficient; compare the fluctuation components of 5 different scales with the corresponding peak-shaving thresholds, and mark the time period requiring peak-shaving on each scale;

[0020] Calculate the 24-point moving average benchmark load curve, and for each period requiring peak shaving, calculate the integral difference between the net load curve and the benchmark load curve to obtain the peak shaving energy demand; integrate the peak shaving energy demands of 5 different scales, and select the maximum value at each moment as the final peak shaving energy demand; calculate the duration, peak power and average power of each peak shaving demand; calculate the priority score of each peak shaving demand based on the peak shaving energy demand, peak power, duration and preset weight coefficient;

[0021] According to the priority score, the peak-shaving demand is sorted in descending order to generate a peak-shaving demand descriptor including the start time, end time, peak-shaving energy demand, peak power, average power and priority score; the sorted peak-shaving demand descriptor is used as the output result to guide the formulation of the subsequent operation strategy of the molten salt heat storage system.

[0022] In an optional embodiment,

[0023] According to the peak load energy demand, peak power, duration and preset weight coefficient, the priority score of each peak load demand is calculated including:

[0024]

[0025] Among them, S represents the priority score, E represents the energy demand of the current peak load demand, and E max represents the historical maximum peak load energy demand, P p Indicates the peak power of the current peak load demand, P max Indicates the historical maximum peak power, T d Indicates the duration of the current peak load demand, T max represents the longest peak load duration in history, w1, w2, and w3 represent the weight coefficients corresponding to energy demand, peak power, and duration, respectively;

[0026] t e Indicates the end time of peak load regulation, t s represents the start time of peak load regulation, N(t) represents the net load value at time t, and B(t) represents the benchmark load value at time t.

[0027] In an optional embodiment,

[0028] In the heat storage mode, using the power during the off-peak period of the power grid or the surplus period of renewable energy generation to drive the electric heater to heat the molten salt, and storing the hot molten salt in the hot molten salt storage tank includes:

[0029] Monitor the load of the power grid in real time and calculate the load rate, which is the ratio of the current load to the maximum load capacity; set a valley period judgment threshold, and when the load rate is less than the valley period judgment threshold, determine that the valley period has arrived; monitor the power generation of renewable energy and calculate the surplus power, which is the difference between the power generation of renewable energy and the current load;

[0030] Determine whether the heat storage system startup conditions are met, the heat storage system startup conditions are that the system is in a low period or the surplus power is greater than zero, and the molten salt storage tank is not full; when the heat storage system startup conditions are met, execute the system startup sequence, the system startup sequence includes molten salt pump preheating, electric heater preheating, pipeline system inspection and valve opening sequence execution;

[0031] Determine the maximum allowable power of the electric heater according to the grid capacity and the heat storage demand; adjust the power of the electric heater in real time, the power of the electric heater being the smaller value between the maximum allowable power and the surplus power;

[0032] Control the power ramp rate of the electric heater so that it does not exceed 10% of the maximum allowable power per minute;

[0033] Calculating an optimal molten salt flow rate, where the optimal molten salt flow rate is equal to the power of the electric heater divided by the product of the specific heat capacity of the molten salt and the set temperature rise; adjusting the operating frequency of the molten salt pump through frequency conversion control according to the optimal molten salt flow rate;

[0034] The target outlet temperature of the hot molten salt is set, and the power of the electric heater is adjusted by a PID controller so that the actual outlet temperature is equal to the target outlet temperature;

[0035] Monitor the actual temperature of the hot molten salt in real time, and when the actual temperature exceeds the preset maximum temperature, perform emergency shutdown processing;

[0036] Calculate the instantaneous heat storage power, which is equal to the product of the mass flow rate of the molten salt, the specific heat capacity of the molten salt, and the temperature difference between the inlet and outlet of the molten salt; integrate the instantaneous heat storage power to obtain the total heat storage capacity;

[0037] The heat storage percentage is calculated and updated based on the ratio of the total heat storage amount to the system heat storage capacity.

[0038] In an optional embodiment,

[0039] In the heat release mode, the hot molten salt in the hot molten salt storage tank is pumped into the molten salt heat exchanger to perform heat exchange with the working medium to generate high-temperature and high-pressure steam, including:

[0040] Receive grid dispatch instructions to obtain the required peak-shaving power and duration; evaluate the capacity of the heat storage system, calculate the total heat storage of the system, and determine whether the total heat storage is greater than or equal to the product of the required peak-shaving power and duration; when the total heat storage is less than the product of the required peak-shaving power and duration, calculate the maximum peak-shaving time;

[0041] Execute a heat release system startup sequence, which includes molten salt pump startup, steam generator preheating, turbine warm-up, and generator synchronization; initialize key system parameters, which include molten salt initial temperature, steam initial temperature, steam initial pressure, and turbine initial speed;

[0042] Establishing a relationship model between molten salt flow and power generation, wherein the relationship model indicates that power generation is a function of molten salt flow, molten salt temperature and steam pressure; according to the relationship model, inversely solving the optimal molten salt flow to meet the required peak-shaving power;

[0043] The molten salt pump speed is adjusted in real time to make the actual molten salt flow rate equal to the optimal molten salt flow rate; the steam temperature and steam pressure are monitored, and when the steam temperature is lower than the preset minimum temperature, the molten salt flow rate is increased; when the steam temperature is higher than the preset maximum temperature, the molten salt flow rate is reduced;

[0044] Regulate the steam turbine inlet valve to control the steam pressure; monitor the generated power in real time and calculate the power error between the generated power and the required peak-shaving power; use the PID controller to adjust the opening of the steam turbine inlet valve and adjust the generated power in real time according to the power error; control the generated power ramp rate so that it does not exceed 15% of the rated power per minute;

[0045] Calculating the thermoelectric conversion efficiency, where the thermoelectric conversion efficiency is the ratio of the generated power to the molten salt thermal power;

[0046] Calculate the cumulative power generation and update the remaining heat storage, where the remaining heat storage is the total heat storage minus the quotient of the cumulative power generation and the average thermoelectric conversion efficiency;

[0047] Determine whether the termination condition of the heat release process is met, wherein the termination condition includes any one of the following: the running time reaches the required duration, the remaining heat storage is less than or equal to the preset minimum heat storage, and the molten salt outlet temperature is lower than the preset minimum temperature;

[0048] When the termination condition is met, the system safety shutdown sequence is executed, and the safety shutdown sequence includes reducing the turbine load, closing the main steam valve, decoupling the generator, slowing down and shutting down the molten salt pump, and recovering the system waste heat; when the termination condition is not met, the molten salt flow control, steam parameter control and generator set output control continue to be executed.

[0049] In an optional embodiment,

[0050] In the peak regulation mode, the flow rate of the molten salt circulation pump is increased to improve the hot molten salt delivery rate, and the heat exchange efficiency of the molten salt heat exchanger is adjusted to generate more high-temperature and high-pressure steam; the steam turbine generator set is controlled to increase the power generation power, and the additional power is incorporated into the power grid to achieve the peak load regulation of the power grid, including:

[0051] Conduct grid connection preparations, including:

[0052] Verify the parameters of the generator set, the status of the molten salt circulation system and the operating status of the steam turbine; analyze the status of the power grid, monitor the power grid frequency and bus voltage, and obtain the power grid load curve; set the grid connection conditions, including the voltage deviation range, frequency deviation range and phase angle synchronization error range;

[0053] Perform grid-connected operations, including:

[0054] Adjust the generator excitation current and use the automatic voltage regulator to achieve dynamic voltage fine-tuning; adjust the turbine speed governor and use the digital synchronization device to control the frequency error; use the phase comparator to align the phase and start the grid connection procedure when the phase difference is less than the preset threshold; perform soft grid connection operation and control the initial grid connection power and power increase rate;

[0055] Implement load regulation strategies, including:

[0056] A proportional-integral-differential controller is used to dynamically adjust the opening of the steam turbine steam inlet valve; a primary frequency modulation controller is configured to automatically adjust the power generation outside the set frequency dead zone; the generator excitation current is adjusted to provide reactive power support, and a dynamic reactive power compensation device is used to achieve rapid reactive power regulation; the power factor is optimized by coordinating active and reactive power output;

[0057] Perform system coordination and optimization, including:

[0058] Establish a dynamic model of molten salt flow and power generation, predict the required molten salt flow and adjust the speed of the molten salt circulation pump in advance; calculate the thermal efficiency of the steam turbine in real time and optimize the extraction parameters; obtain real-time electricity price information, establish a rolling power generation plan, and formulate the optimal power generation curve considering the equipment start-up and shutdown costs and life loss.

[0059] In an optional embodiment,

[0060] The method further comprises:

[0061] According to the real-time grid load data and the operating status of the molten salt heat storage system, the operating parameters of the molten salt heat storage system are dynamically adjusted, including the molten salt circulation flow, the heat exchange efficiency of the heat exchanger and the output power of the steam turbine generator set; an efficiency evaluation model for the molten salt heat storage system is established, and the comprehensive efficiency of the system is calculated according to the operating data of the molten salt heat storage system, and the operating strategy of the molten salt heat storage system is optimized according to the comprehensive efficiency of the system.

[0062] According to a second aspect of the embodiments of the present invention,

[0063] Provide deep peak regulation and peak regulation systems for power grids using molten salt heat storage, including:

[0064] The first unit is used to establish a molten salt heat storage system, the molten salt heat storage system includes a hot molten salt storage tank, a cold molten salt storage tank, a molten salt heat exchanger and a molten salt circulation pump; the hot molten salt storage tank and the cold molten salt storage tank are connected through the molten salt circulation pump and the molten salt heat exchanger to form a molten salt circulation loop; receive power grid load forecast data and renewable energy power generation forecast data, and determine the power grid peak load demand according to the power grid load forecast data and the renewable energy power generation forecast data; formulate a molten salt heat storage system operation strategy according to the power grid peak load demand, and the molten salt heat storage system operation strategy includes a heat storage mode and a heat release mode;

[0065] The second unit is used to drive the electric heater to heat the molten salt in the heat storage mode by using the electricity during the off-peak period of the power grid or the surplus period of renewable energy generation, and store the hot molten salt in the hot molten salt storage tank; in the heat release mode, pump the hot molten salt in the hot molten salt storage tank into the molten salt heat exchanger to exchange heat with the working fluid to generate high-temperature and high-pressure steam; transport the high-temperature and high-pressure steam to the steam turbine generator set to generate electricity, and the generated electricity is incorporated into the power grid to achieve deep peak regulation of the power grid;

[0066] The third unit is used to monitor the changes in the grid load in real time. When it is detected that the grid load has reached a preset peak threshold, the peak regulation mode is started; in the peak regulation mode, the flow rate of the molten salt circulation pump is increased to improve the hot molten salt delivery rate, and the heat exchange efficiency of the molten salt heat exchanger is adjusted to generate more high-temperature and high-pressure steam; the steam turbine generator set is controlled to increase the power generation capacity, and the additional electricity is incorporated into the grid to achieve grid peak load regulation.

[0067] According to a third aspect of the embodiments of the present invention,

[0068] An electronic device is provided, comprising:

[0069] processor;

[0070] a memory for storing processor-executable instructions;

[0071] The processor is configured to call the instructions stored in the memory to execute the aforementioned method.

[0072] According to a fourth aspect of the embodiments of the present invention,

[0073] A computer-readable storage medium is provided, on which computer program instructions are stored. When the computer program instructions are executed by a processor, the aforementioned method is implemented.

[0074] The system effectively improves the peak-shaving capacity of the power grid by storing thermal energy during the off-peak period of the power grid or the period of surplus renewable energy generation, and releasing thermal energy to generate electricity during the peak period of the power grid. This can not only smooth out the fluctuations in the load of the power grid, but also improve the stability and reliability of the power grid. The system can use the electricity during the surplus period of renewable energy generation for heat storage, effectively solving the intermittent and volatility problems of renewable energy generation, and improving the absorption rate and utilization efficiency of renewable energy. By storing energy when the electricity price is low and releasing energy to generate electricity during the peak period, the system can maximize the benefits by using the price difference of electricity, and improve the economic benefits of energy utilization.

[0075] The system can dynamically adjust the operation mode and parameters according to the real-time grid load changes, especially in the peak regulation mode, it can quickly respond to grid demand and provide greater peak regulation capacity. By formulating operation strategies in advance and monitoring the grid load in real time, the system can quickly start the peak regulation mode, improving the response speed to sudden grid demand. By adjusting the flow rate of the molten salt circulation pump and the efficiency of the heat exchanger, the system can optimize the energy conversion process according to actual needs and improve the overall system efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0076] Figure 1 A schematic diagram of a flow chart of a method for deep peak regulation and peak regulation of a power grid using molten salt heat storage according to an embodiment of the present invention;

[0077] Figure 2 It is a schematic diagram of the structure of a power grid deep peak regulation and peak regulation system using molten salt heat storage according to an embodiment of the present invention. DETAILED DESCRIPTION

[0078] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0079] The technical solution of the present invention is described in detail with specific embodiments below. The following specific embodiments can be combined with each other, and the same or similar concepts or processes may not be described in detail in some embodiments.

[0080] Figure 1 FIG. 1 is a flow chart of a method for deep peak regulation and peak regulation of a power grid using molten salt heat storage according to an embodiment of the present invention. Figure 1 As shown, the method includes:

[0081] S101. Establish a molten salt heat storage system, the molten salt heat storage system comprising a hot molten salt storage tank, a cold molten salt storage tank, a molten salt heat exchanger and a molten salt circulation pump; the hot molten salt storage tank and the cold molten salt storage tank are connected through the molten salt circulation pump and the molten salt heat exchanger to form a molten salt circulation loop; receive power grid load forecast data and renewable energy power generation forecast data, and determine the power grid peak load demand according to the power grid load forecast data and the renewable energy power generation forecast data; formulate a molten salt heat storage system operation strategy according to the power grid peak load demand, the molten salt heat storage system operation strategy includes a heat storage mode and a heat release mode;

[0082] S102. In the heat storage mode, the electric power during the off-peak period of the power grid or the surplus period of renewable energy generation is used to drive the electric heater to heat the molten salt, and the hot molten salt is stored in the hot molten salt storage tank; in the heat release mode, the hot molten salt in the hot molten salt storage tank is pumped into the molten salt heat exchanger to perform heat exchange with the working fluid to generate high-temperature and high-pressure steam; the high-temperature and high-pressure steam is transported to the steam turbine generator set to generate electricity, and the generated electricity is incorporated into the power grid to achieve deep peak regulation of the power grid;

[0083] S103. Monitor the changes in the grid load in real time. When it is detected that the grid load has reached a preset peak threshold, start the peak regulation mode; in the peak regulation mode, increase the flow rate of the molten salt circulation pump, improve the hot molten salt delivery rate, and adjust the heat exchange efficiency of the molten salt heat exchanger to generate more high-temperature and high-pressure steam; control the steam turbine generator set to increase the power generation capacity, integrate the additional electricity into the grid, and realize the peak load regulation of the grid.

[0084] In an optional embodiment,

[0085] Receiving grid load forecast data and renewable energy generation forecast data, and determining grid peak load demand according to the grid load forecast data and the renewable energy generation forecast data includes:

[0086] Receive grid load forecast data and renewable energy power generation forecast data, calculate a net load curve, wherein the time resolution of the net load curve is 15 minutes and the forecast duration is 24 hours; calculate the first-order derivative and the second-order derivative of the net load curve, and identify the inflection point and the extreme point of the net load curve;

[0087] Select Daubechies wavelet basis function, perform 5-layer wavelet decomposition on the net load curve, and obtain low-frequency approximate coefficients and detail coefficients of 5 different scales; reconstruct the fluctuation components of 5 different scales by using the low-frequency approximate coefficients and the detail coefficients of 5 different scales; calculate the standard deviation of the fluctuation components of 5 different scales, and determine the peak-shaving thresholds of 5 different scales according to the preset adjustment coefficient; compare the fluctuation components of 5 different scales with the corresponding peak-shaving thresholds, and mark the time period requiring peak-shaving on each scale;

[0088] Calculate the 24-point moving average benchmark load curve, and for each period requiring peak shaving, calculate the integral difference between the net load curve and the benchmark load curve to obtain the peak shaving energy demand; integrate the peak shaving energy demands of 5 different scales, and select the maximum value at each moment as the final peak shaving energy demand; calculate the duration, peak power and average power of each peak shaving demand; calculate the priority score of each peak shaving demand based on the peak shaving energy demand, peak power, duration and preset weight coefficient;

[0089] According to the priority score, the peak-shaving demand is sorted in descending order to generate a peak-shaving demand descriptor including the start time, end time, peak-shaving energy demand, peak power, average power and priority score; the sorted peak-shaving demand descriptor is used as the output result to guide the formulation of the subsequent operation strategy of the molten salt heat storage system.

[0090] In an optional embodiment,

[0091] According to the peak load energy demand, peak power, duration and preset weight coefficient, the priority score of each peak load demand is calculated including:

[0092]

[0093] Among them, S represents the priority score, E represents the energy demand of the current peak load demand, and E max represents the historical maximum peak load energy demand, P p Indicates the peak power of the current peak load demand, P max Indicates the historical maximum peak power, T d Indicates the duration of the current peak load demand, T max represents the longest peak load duration in history, w1, w2, and w3 represent the weight coefficients corresponding to energy demand, peak power, and duration, respectively;

[0094] t e Indicates the end time of peak load regulation, t s represents the start time of peak load regulation, N(t) represents the net load value at time t, and B(t) represents the benchmark load value at time t.

[0095] For example, the key to using molten salt heat storage system for deep peak load regulation and peak load regulation of power grid is to accurately predict and analyze the peak load demand of power grid. To this end, we have developed a peak load demand identification method based on wavelet analysis and multi-scale feature extraction. This method first receives power grid load forecast data and renewable energy generation forecast data, and then through a series of complex data processing and analysis steps, it finally outputs a detailed peak load demand descriptor, which provides an important basis for the formulation of operation strategy of molten salt heat storage system.

[0096] First, the system receives grid load forecast data and renewable energy generation forecast data. These data usually come from the grid dispatch center and the meteorological department, and contain forecast values ​​every 15 minutes for the next 24 hours. For example, the grid load forecast data for a certain day may show that the load at 6:00 in the morning is 20GW, while the renewable energy generation forecast data at the same time may be 5GW.

[0097] Next, the system calculates the net load curve. Net load is equal to grid load minus renewable energy generation. Continuing with the above example, the net load at 6:00 in the morning is 15GW. The system generates a net load curve with 96 data points (24 hours x 4 15-minute intervals).

[0098] In order to identify the key characteristic points of the net load curve, the system calculates the first and second derivatives of the curve. The first derivative reflects the rate of change of the load, and the second derivative reflects the change in the rate of change. By analyzing these derivatives, the system can identify the inflection points and extreme points of the curve. For example, it may be found that there is a positive inflection point at 7:30 in the morning, indicating that the load begins to rise rapidly; and there is a negative inflection point at 22:00 in the evening, indicating that the load begins to drop rapidly.

[0099] Subsequently, the system selects the Daubechies wavelet basis function to perform a 5-layer wavelet decomposition on the net load curve. The Daubechies wavelet basis function is selected for its good localization characteristics and multi-resolution analysis capabilities. Through the 5-layer wavelet decomposition, the system obtains a low-frequency approximation coefficient and 5 detail coefficients of different scales. These coefficients represent the characteristics of the net load curve at different time scales.

[0100] Using the obtained low-frequency approximation coefficients and the detail coefficients of five different scales, the system reconstructs the fluctuation components of five different scales. These fluctuation components correspond to time scales of about 15 minutes, 30 minutes, 1 hour, 2 hours, and 4 hours. For example, the fluctuation component of the first scale may reflect short-term load fluctuations, while the fluctuation component of the fifth scale may reflect longer-term load trends.

[0101] Next, the system calculates the standard deviation of the five different scale fluctuation components and determines the peak-shaving thresholds of the five different scales according to the preset adjustment coefficients. The setting of the adjustment coefficients is based on the grid operation experience and specific needs. For example, the adjustment coefficient of the first scale can be set to 2.5, and the adjustment coefficient of the fifth scale can be set to 1.5. The peak-shaving threshold of each scale is obtained by multiplying the standard deviation by the corresponding adjustment coefficient.

[0102] The system then compares the fluctuation components of the five different scales with the corresponding peak-shaving thresholds, marking the time periods that require peak-shaving on each scale. If the fluctuation amplitude at a certain moment exceeds the threshold of the corresponding scale, it will be marked as a time period that requires peak-shaving. For example, on the first scale, it may be found that 9:00-9:30 in the morning needs to be adjusted upward, while 14:00-14:30 in the afternoon needs to be adjusted downward.

[0103] To quantify the peak demand, the system calculates the 24-point moving average of the benchmark load curve. For each period of time that requires peak demand, the integral difference between the net load curve and the benchmark load curve is calculated to obtain the peak demand. For example, for the upward demand from 9:00 to 9:30 in the morning, it may be calculated that 0.5GWh of peak demand is required.

[0104] The system comprehensively considers the peak-shaving energy demands of five different scales and selects the maximum value at each moment as the final peak-shaving energy demand. This ensures that the system can cope with load fluctuations of various time scales.

[0105] For each peak load demand, the system also calculates its duration, peak power, and average power. For example, a peak load demand may last for 1 hour, with a peak power of 2GW and an average power of 1.5GW.

[0106] In order to reasonably allocate peak-shaving resources, the system calculates the priority score of each peak-shaving demand based on the peak-shaving energy demand, peak power, duration and preset weight coefficient. The setting of the weight coefficient reflects the importance of different factors. For example, the weight of the peak-shaving energy demand can be set to 0.4, the weight of the peak power can be set to 0.3, and the weight of the duration can be set to 0.3.

[0107] Finally, the system sorts the peak-shaving demands in descending order according to the priority score, and generates a peak-shaving demand descriptor containing the start time, end time, peak-shaving energy demand, peak power, average power, and priority score. For example, the first peak-shaving demand descriptor after sorting may be: start time 18:00, end time 20:00, peak-shaving energy demand 3GWh, peak power 2.5GW, average power 1.5GW, and priority score 0.85.

[0108] These sorted peak-shaving demand descriptors are used as output results, providing detailed and targeted guidance for the subsequent operation strategy formulation of the molten salt heat storage system. Based on these descriptors, the operation and dispatching personnel can reasonably arrange the charging and discharging process of the molten salt heat storage system to achieve precise peak-shaving and peak regulation of the power grid.

[0109] In an optional embodiment,

[0110] In the heat storage mode, using the power during the off-peak period of the power grid or the surplus period of renewable energy generation to drive the electric heater to heat the molten salt, and storing the hot molten salt in the hot molten salt storage tank includes:

[0111] Monitor the load of the power grid in real time and calculate the load rate, which is the ratio of the current load to the maximum load capacity; set a valley period judgment threshold, and when the load rate is less than the valley period judgment threshold, determine that the valley period has arrived; monitor the power generation of renewable energy and calculate the surplus power, which is the difference between the power generation of renewable energy and the current load;

[0112] Determine whether the heat storage system startup conditions are met, the heat storage system startup conditions are that the system is in a low period or the surplus power is greater than zero, and the molten salt storage tank is not full; when the heat storage system startup conditions are met, execute the system startup sequence, the system startup sequence includes molten salt pump preheating, electric heater preheating, pipeline system inspection and valve opening sequence execution;

[0113] Determine the maximum allowable power of the electric heater according to the grid capacity and the heat storage demand; adjust the power of the electric heater in real time, the power of the electric heater being the smaller value between the maximum allowable power and the surplus power;

[0114] Control the power ramp rate of the electric heater so that it does not exceed 10% of the maximum allowable power per minute;

[0115] Calculating an optimal molten salt flow rate, where the optimal molten salt flow rate is equal to the power of the electric heater divided by the product of the specific heat capacity of the molten salt and the set temperature rise; adjusting the operating frequency of the molten salt pump through frequency conversion control according to the optimal molten salt flow rate;

[0116] The target outlet temperature of the hot molten salt is set, and the power of the electric heater is adjusted by a PID controller so that the actual outlet temperature is equal to the target outlet temperature;

[0117] Monitor the actual temperature of the hot molten salt in real time, and when the actual temperature exceeds the preset maximum temperature, perform emergency shutdown processing;

[0118] Calculate the instantaneous heat storage power, which is equal to the product of the mass flow rate of the molten salt, the specific heat capacity of the molten salt, and the temperature difference between the inlet and outlet of the molten salt; integrate the instantaneous heat storage power to obtain the total heat storage capacity;

[0119] The heat storage percentage is calculated and updated based on the ratio of the total heat storage amount to the system heat storage capacity.

[0120] For example, the key to the application of molten salt heat storage system in power grid peak regulation is to efficiently use the power during the off-peak period of the power grid or the surplus period of renewable energy generation for heat storage. To achieve this goal, a set of complex control strategies and operating procedures have been developed to ensure the safe and efficient operation of the system.

[0121] First, the system needs to monitor the load of the power grid in real time. By calculating the load rate, which is the ratio of the current load to the maximum load capacity, it can be determined whether the power grid is in a low period. For example, if the maximum load capacity of the power grid is 100GW and the current load is 60GW, the load rate is 60%. Set a low period judgment threshold, such as 65%. When the load rate is lower than this threshold, the system determines that it has entered a low period.

[0122] At the same time, the system also needs to monitor the renewable energy generation and calculate the surplus power. The surplus power is equal to the renewable energy generation minus the current load. For example, if the renewable energy generation is 70GW at a certain moment and the current load is 60GW, the surplus power is 10GW.

[0123] The system determines whether the thermal storage system startup conditions are met. The startup conditions include two aspects: one is that it is in a low period or has surplus electricity, and the other is that the hot molten salt storage tank is not full. When these two conditions are met at the same time, the system starts to execute the startup sequence.

[0124] The startup sequence includes several key steps: First, the molten salt pump is preheated, which usually takes 10-15 minutes to ensure that the molten salt flows smoothly in the pump. The second is the electric heater preheating, which may take 20-30 minutes to allow the heater to reach normal operating temperature. Then there is a piping system inspection to ensure that all pipelines are leak-free and unblocked. Finally, the valve opening operation is performed in a preset order.

[0125] After the startup sequence is completed, the system determines the maximum allowable power of the electric heater based on the grid capacity and the heat storage demand. For example, if the grid capacity is 100GW and the heat storage demand is 10GW, the maximum allowable power may be set to 8GW to take into account the safety margin. The system adjusts the power of the electric heater in real time, taking the smaller value of the maximum allowable power and the surplus power. If the surplus power is 6GW, the actual power of the electric heater is 6GW.

[0126] In order to protect the equipment and maintain grid stability, the system strictly controls the electric heater power ramp rate. It is usually limited to 10% of the maximum allowed power per minute. For example, if the maximum allowed power is 8GW, the power increase per minute does not exceed 0.8GW.

[0127] The system calculates the optimal molten salt flow rate to achieve the best heat transfer efficiency. The optimal molten salt flow rate is equal to the electric heater power divided by the product of the molten salt specific heat capacity and the set temperature rise. Assuming the molten salt specific heat capacity is 1.5kJ / (kg·K), the set temperature rise is 100K, and the electric heater power is 6GW, the optimal molten salt flow rate is about 40,000kg / s. The system adjusts the operating frequency of the molten salt pump through variable frequency control to achieve this optimal flow rate.

[0128] In order to accurately control the temperature of the molten salt, the system sets the target outlet temperature of the molten salt, such as 550°C. The PID controller is used to adjust the power of the electric heater so that the actual outlet temperature is equal to the target temperature. The parameters of the PID controller need to be optimized according to the system characteristics. For example, the proportional coefficient may be set to 0.5, the integral time to 60 seconds, and the differential time to 10 seconds.

[0129] The system monitors the actual temperature of the hot molten salt in real time and sets a safety threshold, such as 565°C. When the actual temperature exceeds this threshold, the system immediately performs emergency shutdown processing, including cutting off the power supply of the electric heater, stopping the molten salt pump, closing related valves, etc.

[0130] The system continuously calculates the instantaneous heat storage power, which is the product of the molten salt mass flow rate, the molten salt specific heat capacity, and the molten salt inlet and outlet temperature difference. For example, if the molten salt flow rate is 40,000kg / s, the specific heat capacity is 1.5kJ / (kg·K), and the inlet and outlet temperature difference is 100K, the instantaneous heat storage power is 6GW. The system integrates the instantaneous heat storage power to obtain the total heat storage capacity. Assuming the system runs continuously for 2 hours, the total heat storage capacity is 43.2GJ.

[0131] Finally, the system calculates and updates the heat storage percentage based on the ratio of total heat storage to system heat storage capacity. If the total heat storage capacity of the system is 300GJ and 43.2GJ is currently stored, the heat storage percentage is 14.4%. This percentage will be displayed in real time on the control interface for the operator's reference.

[0132] Through the above detailed control strategies and operation procedures, the molten salt heat storage system can effectively utilize the power during the off-peak period of the power grid or the surplus period of renewable energy generation for heat storage, providing reliable energy support for subsequent power grid peak regulation and peak regulation. This refined control not only improves the operating efficiency of the system, but also ensures the safety and reliability of the equipment, making an important contribution to the stable operation of the power grid.

[0133] In an optional embodiment,

[0134] In the heat release mode, the hot molten salt in the hot molten salt storage tank is pumped into the molten salt heat exchanger to perform heat exchange with the working medium to generate high-temperature and high-pressure steam, including:

[0135] Receive grid dispatch instructions to obtain the required peak-shaving power and duration; evaluate the capacity of the heat storage system, calculate the total heat storage of the system, and determine whether the total heat storage is greater than or equal to the product of the required peak-shaving power and duration; when the total heat storage is less than the product of the required peak-shaving power and duration, calculate the maximum peak-shaving time;

[0136] Execute a heat release system startup sequence, which includes molten salt pump startup, steam generator preheating, turbine warm-up, and generator synchronization; initialize key system parameters, which include molten salt initial temperature, steam initial temperature, steam initial pressure, and turbine initial speed;

[0137] Establishing a relationship model between molten salt flow and power generation, wherein the relationship model indicates that power generation is a function of molten salt flow, molten salt temperature and steam pressure; according to the relationship model, inversely solving the optimal molten salt flow to meet the required peak-shaving power;

[0138] The molten salt pump speed is adjusted in real time to make the actual molten salt flow rate equal to the optimal molten salt flow rate; the steam temperature and steam pressure are monitored, and when the steam temperature is lower than the preset minimum temperature, the molten salt flow rate is increased; when the steam temperature is higher than the preset maximum temperature, the molten salt flow rate is reduced;

[0139] Regulate the steam turbine inlet valve to control the steam pressure; monitor the generated power in real time and calculate the power error between the generated power and the required peak-shaving power; use a PID controller to adjust the opening of the steam turbine inlet valve and adjust the generated power in real time according to the power error; control the generated power ramp rate so that it does not exceed 15% of the rated power per minute;

[0140] Calculating the thermoelectric conversion efficiency, where the thermoelectric conversion efficiency is the ratio of the generated power to the molten salt thermal power;

[0141] Calculate the cumulative power generation and update the remaining heat storage, where the remaining heat storage is the total heat storage minus the quotient of the cumulative power generation and the average thermoelectric conversion efficiency;

[0142] Determine whether the termination condition of the heat release process is met, wherein the termination condition includes any one of the following: the running time reaches the required duration, the remaining heat storage is less than or equal to the preset minimum heat storage, and the molten salt outlet temperature is lower than the preset minimum temperature;

[0143] When the termination condition is met, the system safety shutdown sequence is executed, and the safety shutdown sequence includes reducing the turbine load, closing the main steam valve, decoupling the generator, slowing down and shutting down the molten salt pump, and recovering the system waste heat; when the termination condition is not met, the molten salt flow control, steam parameter control and generator set output control continue to be executed.

[0144] For example, the heat release mode of the molten salt heat storage system is a key link in the peak load regulation of the power grid, which meets the needs of the power grid by converting the stored thermal energy into electrical energy. Achieving this process requires a set of complex and sophisticated control strategies and operating procedures to ensure the efficient and safe operation of the system.

[0145] First, the system receives instructions from the grid dispatch center to obtain the required peak-shaving power and duration. For example, the grid may require 100MW of peak-shaving power for 4 hours. The system then evaluates its own heat storage capacity and calculates the current total heat storage. Assume that the total heat storage capacity of the system is 1600MWh and the current heat storage is 1200MWh. The system determines whether the total heat storage is sufficient to meet the dispatch demand, that is, whether it is greater than or equal to the product of the required peak-shaving power and the duration. In this example, the demand is 400MWh, which is less than the current heat storage, so the system can meet the demand. If the heat storage is insufficient, the system will calculate the maximum peak-shaving time, which is about 12 hours in this case.

[0146] After confirming that the dispatch requirements can be met, the system begins to execute the heat release system startup sequence. This sequence includes several key steps: First, start the molten salt pump, which usually takes 5-10 minutes to ensure that the molten salt flow is stable. Then preheat the steam generator, which may take 20-30 minutes to avoid thermal shock. Next is the turbine warm-up, which may take 1-2 hours, depending on the degree of cooling of the turbine. Finally, the generator is synchronized and the generator is connected to the grid, which usually takes a few minutes.

[0147] The system also initializes key parameters. For example, the initial temperature of the molten salt may be 550°C, the initial temperature of the steam may be 540°C, the initial pressure of the steam may be 16MPa, and the initial speed of the turbine may be 3000rpm (for a 50Hz grid).

[0148] Next, the system establishes a relationship model between molten salt flow and power generation. This model shows that power generation is a function of molten salt flow, molten salt temperature and steam pressure. Through this model, the system can reversely calculate the optimal molten salt flow required to achieve the required peak power. For example, to achieve 100MW of power generation, a molten salt flow of 400kg / s may be required at a given molten salt temperature and steam pressure.

[0149] The system adjusts the molten salt pump speed in real time to make the actual molten salt flow equal to the calculated optimal flow. At the same time, the system continuously monitors the steam temperature and pressure. If the steam temperature is lower than the preset minimum temperature (such as 530°C), the system will increase the molten salt flow; if it is higher than the preset maximum temperature (such as 550°C), the flow will be reduced. This dynamic adjustment ensures the stability of steam parameters.

[0150] The system controls the steam pressure by adjusting the turbine inlet valve. At the same time, the power generation is monitored in real time and the error with the required peak power is calculated. The PID controller is used to adjust the opening of the turbine inlet valve and adjust the power generation in real time according to the power error. For example, if the proportional coefficient of the PID controller is 0.5, the integral time is 60 seconds, and the differential time is 10 seconds, when the power error is 2MW, the system will adjust the valve opening accordingly. The system also strictly controls the power generation ramp rate, which usually does not exceed 15% of the rated power per minute to protect the equipment and maintain grid stability.

[0151] The system continuously calculates the thermoelectric conversion efficiency, which is the ratio of the power generation to the molten salt thermal power. For example, if the power generation is 100MW and the molten salt thermal power is 250MW, the thermoelectric conversion efficiency is 40%. At the same time, the system calculates the cumulative power generation and updates the remaining heat storage. Assuming that the system runs for 1 hour, the cumulative power generation is 100MWh, and the average thermoelectric conversion efficiency is 40%, the heat storage consumed is 250MWh, and the remaining heat storage is 950MWh.

[0152] The system continuously determines whether the termination conditions of the heat release process are met. The termination conditions include: the operation time reaches the required duration (4 hours in this case), the remaining heat storage is less than or equal to the preset minimum heat storage (such as 200MWh), and the molten salt outlet temperature is lower than the preset minimum temperature (such as 290℃).

[0153] When the termination conditions are met, the system executes a safe shutdown sequence. This sequence includes several key steps: First, gradually reduce the turbine load, usually at a rate of 5-10% per minute. Then close the main steam valve to cut off the steam supply. Then decouple the generator and separate the generator from the grid. After that, the molten salt pump begins to slow down and stop, which may take 10-15 minutes. Finally, the system recovers waste heat and uses the remaining heat to heat molten salt or other purposes to improve overall efficiency.

[0154] If the termination condition is not met, the system will continue to execute molten salt flow control, steam parameter control and generator set output control to keep the system running stably until the termination condition is met or a new dispatch instruction is received.

[0155] Through this set of detailed control strategies and operation procedures, the molten salt thermal storage system can effectively convert the stored thermal energy into electrical energy and accurately respond to the peak load demand of the power grid. This refined control not only improves the operating efficiency of the system, but also ensures the safety and reliability of the equipment, providing strong support for the stable operation of the power grid and the large-scale application of renewable energy.

[0156] In an optional embodiment,

[0157] In the peak regulation mode, the flow rate of the molten salt circulation pump is increased to improve the hot molten salt delivery rate, and the heat exchange efficiency of the molten salt heat exchanger is adjusted to generate more high-temperature and high-pressure steam; the steam turbine generator set is controlled to increase the power generation power, and the additional power is incorporated into the power grid to achieve the peak load regulation of the power grid, including:

[0158] Conduct grid connection preparations, including:

[0159] Verify the parameters of the generator set, the status of the molten salt circulation system and the operating status of the steam turbine; analyze the status of the power grid, monitor the power grid frequency and bus voltage, and obtain the power grid load curve; set the grid connection conditions, including the voltage deviation range, frequency deviation range and phase angle synchronization error range;

[0160] Perform grid-connected operations, including:

[0161] Adjust the generator excitation current and use the automatic voltage regulator to achieve dynamic voltage fine-tuning; adjust the turbine speed governor and use the digital synchronization device to control the frequency error; use the phase comparator to align the phase and start the grid connection procedure when the phase difference is less than the preset threshold; perform soft grid connection operation and control the initial grid connection power and power increase rate;

[0162] Implement load regulation strategies, including:

[0163] A proportional-integral-differential controller is used to dynamically adjust the opening of the steam turbine steam inlet valve; a primary frequency modulation controller is configured to automatically adjust the power generation outside the set frequency dead zone; the generator excitation current is adjusted to provide reactive power support, and a dynamic reactive power compensation device is used to achieve rapid reactive power regulation; the power factor is optimized by coordinating active and reactive power output;

[0164] Perform system coordination and optimization, including:

[0165] Establish a dynamic model of molten salt flow and power generation, predict the required molten salt flow and adjust the speed of the molten salt circulation pump in advance; calculate the thermal efficiency of the steam turbine in real time and optimize the extraction parameters; obtain real-time electricity price information, establish a rolling power generation plan, and formulate the optimal power generation curve considering the equipment start-up and shutdown costs and life loss.

[0166] For example, the operation of a molten salt thermal storage system in peak regulation mode is a complex and sophisticated process involving the coordinated work and precise control of multiple subsystems. This process can be divided into four main stages: pre-grid preparation, grid connection operation, implementation of load regulation strategy, and system coordination and optimization.

[0167] In the pre-grid preparation stage, it is first necessary to fully verify the parameters of the generator set, the status of the molten salt circulation system, and the operating status of the turbine. This includes checking the excitation current, rotor temperature, stator temperature and other parameters of the generator to ensure that they are within the normal range. For example, the excitation current of the generator should be maintained between 95% and 105% of the rated value, and the rotor and stator temperatures should not exceed the designed maximum temperature. For the molten salt circulation system, it is necessary to check the molten salt temperature, pressure and flow rate to ensure that they meet the operating requirements. For example, the molten salt temperature may need to be maintained at around 550°C, the pressure below 0.5MPa, and the flow rate may be between 400-600kg / s according to the system design. The operating status check of the turbine includes speed, vibration, bearing temperature, etc., to ensure that they are all within the safe range. For example, the turbine speed should be maintained within ±0.5% of the rated speed, and the vibration amplitude should not exceed 30μm.

[0168] At the same time, the system needs to analyze the grid status in real time, monitor the grid frequency and bus voltage, and obtain the grid load curve. The normal range of grid frequency is usually ±0.2Hz of the rated frequency, and the allowable deviation of bus voltage is usually within ±5% of the rated voltage. The analysis of the grid load curve can predict the load change trend in the next few hours and provide a basis for the subsequent power generation plan.

[0169] Based on the grid status analysis, the system sets the grid connection conditions. This usually includes the voltage deviation range, frequency deviation range and phase angle synchronization error range. For example, the voltage deviation range may be set to ±0.5%, the frequency deviation range to ±0.1Hz, and the phase angle synchronization error range to ±5°. Only when the actual parameters fall within these ranges will the system perform grid connection operation.

[0170] When entering the grid-connected operation stage, the system first adjusts the generator excitation current. This is achieved through the automatic voltage regulator, which can dynamically fine-tune the voltage within milliseconds. For example, if it detects that the voltage is slightly low, the automatic voltage regulator will increase the excitation current, usually at a rate of 0.5% per second, until the voltage reaches the target value.

[0171] At the same time, the system adjusts the turbine governor and uses a digital synchronizer to control the frequency error. The digital synchronizer can accurately control the frequency error within ±0.01Hz through high-speed sampling and digital signal processing technology. When the frequency error exceeds the set threshold, the governor will automatically adjust the steam intake of the turbine, thereby changing the speed and frequency.

[0172] The system also uses a phase comparator to align the phase. The phase comparator continuously monitors the phase difference between the generator output and the grid. When the phase difference is less than the preset threshold (such as 2°), the grid connection procedure is started. The grid connection process uses soft grid connection technology to control the initial grid connection power to usually not exceed 10% of the rated power, and gradually increase the power at a rate of not more than 5% of the rated power per minute.

[0173] During the implementation of the load regulation strategy, the system uses a proportional-integral-derivative (PID) controller to dynamically adjust the opening of the turbine steam inlet valve. The parameters of the PID controller need to be optimized according to the system characteristics. For example, the proportional coefficient may be set to 0.5, the integral time to 60 seconds, and the differential time to 10 seconds. Such settings can achieve a faster response speed while ensuring system stability.

[0174] The system is also equipped with a primary frequency controller to automatically adjust the power generation outside the set frequency dead zone (such as ±0.05Hz). When the grid frequency deviates from the rated value and exceeds the dead zone range, the primary frequency controller will automatically adjust the power generation according to the preset frequency modulation characteristic curve. For example, in a 50Hz system, the power generation may need to increase by 2% for every 0.1Hz drop in frequency.

[0175] To provide reactive power support, the system adjusts the generator excitation current and uses a dynamic reactive compensation device to achieve fast reactive regulation. The dynamic reactive compensation device can complete reactive power regulation within a few cycles, and its response speed is much faster than that of traditional mechanical switch capacitor banks. The system optimizes the power factor by coordinating active and reactive power output, usually maintaining the power factor above 0.95.

[0176] In the system coordination and optimization stage, a dynamic model of molten salt flow and power generation is first established. This model takes into account multiple factors such as molten salt temperature, steam parameters, turbine efficiency, etc., and can predict the molten salt flow required for a given power generation. For example, the model may show that at a molten salt temperature of 550°C, a molten salt flow of 400kg / s is required to achieve a power generation of 100MW. Based on this model, the system adjusts the speed of the molten salt circulation pump in advance to ensure that the molten salt flow can meet the power generation demand in a timely manner.

[0177] The system also calculates the turbine thermal efficiency in real time and optimizes the extraction parameters. By monitoring the pressure and flow of each stage of extraction, the system can calculate the current thermal efficiency and optimize the efficiency by adjusting the extraction volume. For example, when operating at part load, it may be necessary to reduce the extraction volume of some stages to improve the overall efficiency.

[0178] Finally, the system obtains real-time electricity price information and establishes a rolling power generation plan. This plan takes into account the equipment start-up and shutdown costs and life loss, as well as the predicted changes in electricity prices, to develop the optimal power generation curve. For example, if it is predicted that electricity prices will rise significantly in the next 4 hours, the system may choose to slightly reduce power generation in the current period to retain more heat storage for power generation during high electricity price periods.

[0179] Through this series of sophisticated control and optimization measures, the molten salt thermal storage system can effectively cope with the peak load of the power grid and provide flexible and reliable peak load regulation services. This not only improves the economic benefits of the system, but also provides important support for the stable operation of the power grid and promotes the large-scale application of renewable energy.

[0180] In an optional embodiment,

[0181] The method further comprises:

[0182] According to the real-time grid load data and the operating status of the molten salt heat storage system, the operating parameters of the molten salt heat storage system are dynamically adjusted, including the molten salt circulation flow, the heat exchange efficiency of the heat exchanger and the output power of the steam turbine generator set; an efficiency evaluation model for the molten salt heat storage system is established, and the comprehensive efficiency of the system is calculated according to the operating data of the molten salt heat storage system, and the operating strategy of the molten salt heat storage system is optimized according to the comprehensive efficiency of the system.

[0183] For example, the dynamic adjustment and efficiency optimization of the molten salt thermal storage system is a complex and delicate process involving the coordinated work and precise control of multiple subsystems. This process mainly includes two core parts: dynamically adjusting operating parameters and establishing an efficiency evaluation model.

[0184] In terms of dynamically adjusting operating parameters, the system first needs to collect and analyze grid load data in real time. This is usually achieved through a real-time data interface with the grid dispatch center, updating the grid load data every second. At the same time, the system also needs to continuously monitor its own operating status, including molten salt temperature, pressure, flow, and operating parameters of each key equipment. For example, the molten salt temperature may fluctuate around 550°C, the pressure is below 0.5MPa, and the flow rate varies between 400-600kg / s.

[0185] Based on these real-time data, the system uses a predictive control algorithm to dynamically adjust operating parameters. The predictive control algorithm usually uses a rolling time domain method, performing optimization calculations every 5 minutes to predict the optimal operating strategy for the next hour. This algorithm takes into account multiple factors, including predicted changes in grid load, current molten salt storage, and equipment operating limitations.

[0186] The adjustment of the molten salt circulation flow rate is a key parameter. When it is predicted that the grid load is about to increase, the system will increase the molten salt circulation flow rate in advance. For example, if it is predicted that the grid load will increase by 10% in 15 minutes, the system may gradually increase the molten salt flow rate from 400kg / s to 440kg / s within 5 minutes to prepare for the upcoming load increase.

[0187] The adjustment of the heat exchange efficiency of the heat exchanger is mainly achieved by controlling the working parameters of the heat exchanger. This includes adjusting the flow ratio on both sides of the heat exchanger, controlling the working pressure of the heat exchanger, etc. For example, when the heat exchange efficiency needs to be improved, the system may increase the flow on the molten salt side while slightly reducing the pressure on the water / steam side to increase the temperature difference driving force. Specifically, the flow on the molten salt side may be increased from 400kg / s to 420kg / s, while the pressure on the water / steam side may be reduced from 10MPa to 9.8MPa.

[0188] The adjustment of the output power of the steam turbine generator set is a direct means of responding to the needs of the power grid. The system controls the output power by adjusting the opening of the steam inlet valve of the steam turbine. For example, when the output power needs to be increased, the system may gradually increase the opening of the steam inlet valve from 80% to 90% within 2 minutes, thereby increasing the output power from 90MW to 100MW.

[0189] In terms of establishing the efficiency evaluation model, the system adopts a multi-level evaluation method. First, a separate efficiency model is established for each subsystem. For example, the efficiency model of the molten salt heat storage tank takes into account the heat loss rate, which is usually expressed as the percentage of heat lost per hour to the total stored heat. A well-designed heat storage tank may have a heat loss rate of about 0.5% / day.

[0190] The efficiency model of the heat exchange system takes into account the effectiveness of the heat exchanger, which is usually expressed as the ratio of the actual heat exchange rate to the theoretical maximum heat exchange rate. An efficient heat exchanger may have an effectiveness of more than 0.9.

[0191] The efficiency model of steam turbine power generation system focuses on thermal efficiency, that is, the ratio of output electrical energy to input thermal energy. The thermal efficiency of modern steam turbine power generation system may reach about 40%.

[0192] The calculation of the overall system efficiency takes into account the efficiency of each of the above subsystems and their mutual influence. For example, the efficiency of the thermal storage system affects the heat available for power generation, which in turn affects the output power of the entire system. The system uses a weighted average method to calculate the overall efficiency, in which the weight of each subsystem is determined according to its importance in the entire system.

[0193] Based on the calculated system overall efficiency, the system will optimize the operation strategy. This optimization process uses a machine learning algorithm, specifically a reinforcement learning method. The system takes the operating data of the past 24 hours as input, including the operating parameters and the corresponding system efficiency at each time point, and then uses this data to train the reinforcement learning model.

[0194] The trained model can give optimization suggestions for different operating scenarios. For example, the model may find that under certain load conditions, slightly reducing the molten salt circulation flow rate can improve the overall efficiency of the system. Specifically, at 70% of the rated load, reducing the molten salt flow rate from 400kg / s to 380kg / s may increase the overall efficiency of the system by 0.5 percentage points.

[0195] The system will re-evaluate the current operation strategy regularly (e.g. every hour) and make adjustments based on the latest efficiency evaluation results and the recommendations of the optimization model. This continuous optimization process ensures that the system always operates near the optimal efficiency point.

[0196] Through this dynamic adjustment and continuous optimization method, the molten salt thermal storage system can flexibly respond to changing grid demands while maintaining efficient operation. This not only improves the economic benefits of the system, but also provides important support for the stable operation of the grid and the large-scale application of renewable energy.

[0197] Figure 2 Schematic diagram of the structure of the power grid deep peak regulation and peak regulation system using molten salt heat storage in an embodiment of the present invention. Figure 2 As shown, the system comprises:

[0198] The first unit is used to establish a molten salt heat storage system, the molten salt heat storage system includes a hot molten salt storage tank, a cold molten salt storage tank, a molten salt heat exchanger and a molten salt circulation pump; the hot molten salt storage tank and the cold molten salt storage tank are connected through the molten salt circulation pump and the molten salt heat exchanger to form a molten salt circulation loop; receive power grid load forecast data and renewable energy power generation forecast data, and determine the power grid peak load demand according to the power grid load forecast data and the renewable energy power generation forecast data; formulate a molten salt heat storage system operation strategy according to the power grid peak load demand, and the molten salt heat storage system operation strategy includes a heat storage mode and a heat release mode;

[0199] The second unit is used to drive the electric heater to heat the molten salt in the heat storage mode by using the electricity during the off-peak period of the power grid or the surplus period of renewable energy generation, and store the hot molten salt in the hot molten salt storage tank; in the heat release mode, pump the hot molten salt in the hot molten salt storage tank into the molten salt heat exchanger to exchange heat with the working fluid to generate high-temperature and high-pressure steam; transport the high-temperature and high-pressure steam to the steam turbine generator set to generate electricity, and the generated electricity is incorporated into the power grid to achieve deep peak regulation of the power grid;

[0200] The third unit is used to monitor the changes in the grid load in real time. When it is detected that the grid load has reached a preset peak threshold, the peak regulation mode is started; in the peak regulation mode, the flow rate of the molten salt circulation pump is increased to improve the hot molten salt delivery rate, and the heat exchange efficiency of the molten salt heat exchanger is adjusted to generate more high-temperature and high-pressure steam; the steam turbine generator set is controlled to increase the power generation capacity, and the additional electricity is incorporated into the grid to achieve grid peak load regulation.

[0201] According to a third aspect of the embodiments of the present invention,

[0202] An electronic device is provided, comprising:

[0203] processor;

[0204] a memory for storing processor-executable instructions;

[0205] The processor is configured to call the instructions stored in the memory to execute the aforementioned method.

[0206] According to a fourth aspect of the embodiments of the present invention,

[0207] A computer-readable storage medium is provided, on which computer program instructions are stored. When the computer program instructions are executed by a processor, the aforementioned method is implemented.

[0208] The present invention may be a method, an apparatus, a system and / or a computer program product. The computer program product may include a computer-readable storage medium carrying computer-readable program instructions for executing various aspects of the present invention.

[0209] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for deep peak regulation and peak regulation of a power grid using molten salt heat storage, characterized in that: include: Establish a molten salt heat storage system, the molten salt heat storage system includes a hot molten salt storage tank, a cold molten salt storage tank, a molten salt heat exchanger and a molten salt circulation pump; the hot molten salt storage tank and the cold molten salt storage tank are connected through the molten salt circulation pump and the molten salt heat exchanger to form a molten salt circulation loop; receive power grid load forecast data and renewable energy power generation forecast data, and determine the power grid peak load demand according to the power grid load forecast data and the renewable energy power generation forecast data; formulate a molten salt heat storage system operation strategy according to the power grid peak load demand, the molten salt heat storage system operation strategy includes a heat storage mode and a heat release mode; In the heat storage mode, the electric power during the off-peak period of the power grid or the period of surplus power generation from renewable energy is used to drive the electric heater to heat the molten salt, and the hot molten salt is stored in the hot molten salt storage tank; in the heat release mode, the hot molten salt in the hot molten salt storage tank is pumped into the molten salt heat exchanger to perform heat exchange with the working fluid to generate high-temperature and high-pressure steam; the high-temperature and high-pressure steam is transported to the steam turbine generator set to generate electricity, and the generated electricity is incorporated into the power grid to achieve deep peak regulation of the power grid; Monitor the changes in the grid load in real time, and start the peak regulation mode when it is detected that the grid load reaches a preset peak threshold; in the peak regulation mode, increase the flow rate of the molten salt circulation pump, improve the hot molten salt delivery rate, and adjust the heat exchange efficiency of the molten salt heat exchanger to generate more high-temperature and high-pressure steam; control the steam turbine generator set to increase the power generation, and integrate the additional electricity into the grid to achieve grid peak load regulation.

2. The method according to claim 1, characterized in that Receiving grid load forecast data and renewable energy generation forecast data, and determining grid peak load demand according to the grid load forecast data and the renewable energy generation forecast data includes: Receive grid load forecast data and renewable energy power generation forecast data, calculate a net load curve, wherein the time resolution of the net load curve is 15 minutes and the forecast duration is 24 hours; calculate the first-order derivative and the second-order derivative of the net load curve, and identify the inflection point and the extreme point of the net load curve; Selecting Daubechies wavelet basis function, performing 5-layer wavelet decomposition on the net load curve, obtaining low-frequency approximate coefficients and detail coefficients of 5 different scales; reconstructing the fluctuation components of 5 different scales by using the low-frequency approximate coefficients and the detail coefficients of the 5 different scales; calculating the standard deviation of the fluctuation components of the 5 different scales, and determining the peak-shaving thresholds of 5 different scales according to the preset adjustment coefficients; comparing the fluctuation components of the 5 different scales with the corresponding peak-shaving thresholds, and marking the time period requiring peak-shaving at each scale; Calculate the 24-point moving average benchmark load curve, and for each period requiring peak shaving, calculate the integral difference between the net load curve and the benchmark load curve to obtain the peak shaving energy demand; integrate the peak shaving energy demands of 5 different scales, and select the maximum value at each moment as the final peak shaving energy demand; calculate the duration, peak power and average power of each peak shaving demand; calculate the priority score of each peak shaving demand based on the peak shaving energy demand, peak power, duration and preset weight coefficient; According to the priority score, the peak-shaving demand is sorted in descending order to generate a peak-shaving demand descriptor including the start time, end time, peak-shaving energy demand, peak power, average power and priority score; the sorted peak-shaving demand descriptor is used as the output result to guide the formulation of the subsequent operation strategy of the molten salt heat storage system.

3. The method according to claim 2, characterized in that According to the peak load energy demand, peak power, duration and preset weight coefficient, the priority score of each peak load demand is calculated including: Among them, S represents the priority score, E represents the energy demand of the current peak load demand, and E max represents the historical maximum peak load energy demand, P p Indicates the peak power of the current peak load demand, P max Indicates the historical maximum peak power, T d Indicates the duration of the current peak load demand, T max represents the longest peak load duration in history, w1, w2, and w3 represent the weight coefficients corresponding to energy demand, peak power, and duration, respectively; t e Indicates the end time of peak load regulation, t s represents the start time of peak load regulation, N(t) represents the net load value at time t, and B(t) represents the benchmark load value at time t.

4. The method according to claim 1, characterized in that: In the heat storage mode, using the power during the off-peak period of the power grid or the surplus period of renewable energy generation to drive the electric heater to heat the molten salt, and storing the hot molten salt in the hot molten salt storage tank includes: Monitor the load of the power grid in real time and calculate the load rate, which is the ratio of the current load to the maximum load capacity; set a valley period judgment threshold, and when the load rate is less than the valley period judgment threshold, determine that the valley period has arrived; monitor the power generation of renewable energy and calculate the surplus power, which is the difference between the power generation of renewable energy and the current load; Determine whether the heat storage system startup conditions are met, the heat storage system startup conditions are that the system is in a low period or the surplus power is greater than zero, and the molten salt storage tank is not full; when the heat storage system startup conditions are met, execute the system startup sequence, the system startup sequence includes molten salt pump preheating, electric heater preheating, pipeline system inspection and valve opening sequence execution; Determine the maximum allowable power of the electric heater according to the grid capacity and the heat storage demand; adjust the power of the electric heater in real time, the power of the electric heater being the smaller value between the maximum allowable power and the surplus power; Control the power ramp rate of the electric heater so that it does not exceed 10% of the maximum allowable power per minute; Calculating an optimal molten salt flow rate, where the optimal molten salt flow rate is equal to the power of the electric heater divided by the product of the specific heat capacity of the molten salt and the set temperature rise; adjusting the operating frequency of the molten salt pump through frequency conversion control according to the optimal molten salt flow rate; The target outlet temperature of the hot molten salt is set, and the power of the electric heater is adjusted by a PID controller so that the actual outlet temperature is equal to the target outlet temperature; Monitor the actual temperature of the hot molten salt in real time, and when the actual temperature exceeds the preset maximum temperature, perform emergency shutdown processing; Calculate the instantaneous heat storage power, which is equal to the product of the mass flow rate of the molten salt, the specific heat capacity of the molten salt, and the temperature difference between the inlet and outlet of the molten salt; integrate the instantaneous heat storage power to obtain the total heat storage capacity; The heat storage percentage is calculated and updated based on the ratio of the total heat storage amount to the system heat storage capacity.

5. The method according to claim 1, characterized in that In the heat release mode, the hot molten salt in the hot molten salt storage tank is pumped into the molten salt heat exchanger to perform heat exchange with the working medium to generate high-temperature and high-pressure steam, including: Receive grid dispatch instructions to obtain the required peak-shaving power and duration; evaluate the capacity of the heat storage system, calculate the total heat storage of the system, and determine whether the total heat storage is greater than or equal to the product of the required peak-shaving power and duration; when the total heat storage is less than the product of the required peak-shaving power and duration, calculate the maximum peak-shaving time; Execute a heat release system startup sequence, which includes molten salt pump startup, steam generator preheating, turbine warm-up, and generator synchronization; initialize key system parameters, which include molten salt initial temperature, steam initial temperature, steam initial pressure, and turbine initial speed; Establishing a relationship model between molten salt flow and power generation, wherein the relationship model indicates that power generation is a function of molten salt flow, molten salt temperature and steam pressure; according to the relationship model, inversely solving the optimal molten salt flow to meet the required peak-shaving power; The molten salt pump speed is adjusted in real time to make the actual molten salt flow rate equal to the optimal molten salt flow rate; the steam temperature and steam pressure are monitored, and when the steam temperature is lower than the preset minimum temperature, the molten salt flow rate is increased; when the steam temperature is higher than the preset maximum temperature, the molten salt flow rate is reduced; Regulate the steam turbine inlet valve to control the steam pressure; monitor the generated power in real time and calculate the power error between the generated power and the required peak-shaving power; use a PID controller to adjust the opening of the steam turbine inlet valve and adjust the generated power in real time according to the power error; control the generated power ramp rate so that it does not exceed 15% of the rated power per minute; Calculating the thermoelectric conversion efficiency, where the thermoelectric conversion efficiency is the ratio of the generated power to the molten salt thermal power; Calculate the cumulative power generation and update the remaining heat storage, where the remaining heat storage is the total heat storage minus the quotient of the cumulative power generation and the average thermoelectric conversion efficiency; Determine whether the termination condition of the heat release process is met, wherein the termination condition includes any one of the following: the running time reaches the required duration, the remaining heat storage is less than or equal to the preset minimum heat storage, and the molten salt outlet temperature is lower than the preset minimum temperature; When the termination condition is met, the system safety shutdown sequence is executed, and the safety shutdown sequence includes reducing the turbine load, closing the main steam valve, decoupling the generator, slowing down and shutting down the molten salt pump, and recovering the system waste heat; when the termination condition is not met, the molten salt flow control, steam parameter control and generator set output control continue to be executed.

6. The method according to claim 1, characterized in that In the peak regulation mode, the flow rate of the molten salt circulation pump is increased to improve the hot molten salt delivery rate, and the heat exchange efficiency of the molten salt heat exchanger is adjusted to generate more high-temperature and high-pressure steam; Controlling the steam turbine generator set to increase the power generation, integrating the additional power into the power grid, and realizing the peak load regulation of the power grid includes: Conduct grid connection preparations, including: Verify the parameters of the generator set, the status of the molten salt circulation system and the operating status of the steam turbine; analyze the status of the power grid, monitor the power grid frequency and bus voltage, and obtain the power grid load curve; set the grid connection conditions, including the voltage deviation range, frequency deviation range and phase angle synchronization error range; Perform grid-connected operations, including: Adjust the generator excitation current and use the automatic voltage regulator to achieve dynamic voltage fine-tuning; adjust the turbine speed governor and use the digital synchronization device to control the frequency error; use the phase comparator to align the phase and start the grid connection procedure when the phase difference is less than the preset threshold; perform soft grid connection operation and control the initial grid connection power and power increase rate; Implement load regulation strategies, including: A proportional-integral-differential controller is used to dynamically adjust the opening of the steam turbine steam inlet valve; a primary frequency modulation controller is configured to automatically adjust the power generation outside the set frequency dead zone; the generator excitation current is adjusted to provide reactive power support, and a dynamic reactive power compensation device is used to achieve rapid reactive power regulation; the power factor is optimized by coordinating active and reactive power output; Perform system coordination and optimization, including: Establish a dynamic model of molten salt flow and power generation, predict the required molten salt flow and adjust the speed of the molten salt circulation pump in advance; calculate the thermal efficiency of the steam turbine in real time and optimize the extraction parameters; obtain real-time electricity price information, establish a rolling power generation plan, and formulate the optimal power generation curve considering the equipment start-up and shutdown costs and life loss.

7. The method according to claim 1, characterized in that The method further comprises: According to the real-time grid load data and the operating status of the molten salt heat storage system, the operating parameters of the molten salt heat storage system are dynamically adjusted, including the molten salt circulation flow, the heat exchange efficiency of the heat exchanger and the output power of the steam turbine generator set; an efficiency evaluation model for the molten salt heat storage system is established, and the comprehensive efficiency of the system is calculated according to the operating data of the molten salt heat storage system, and the operating strategy of the molten salt heat storage system is optimized according to the comprehensive efficiency of the system.

8. A power grid deep peak regulation and peak regulation system using molten salt heat storage, used to implement the method described in any one of claims 1 to 7, characterized in that: include: The first unit is used to establish a molten salt heat storage system, the molten salt heat storage system includes a hot molten salt storage tank, a cold molten salt storage tank, a molten salt heat exchanger and a molten salt circulation pump; the hot molten salt storage tank and the cold molten salt storage tank are connected through the molten salt circulation pump and the molten salt heat exchanger to form a molten salt circulation loop; receive power grid load forecast data and renewable energy power generation forecast data, and determine the power grid peak load demand according to the power grid load forecast data and the renewable energy power generation forecast data; formulate a molten salt heat storage system operation strategy according to the power grid peak load demand, and the molten salt heat storage system operation strategy includes a heat storage mode and a heat release mode; The second unit is used to drive the electric heater to heat the molten salt in the heat storage mode by using the electricity during the off-peak period of the power grid or the surplus period of renewable energy generation, and store the hot molten salt in the hot molten salt storage tank; in the heat release mode, pump the hot molten salt in the hot molten salt storage tank into the molten salt heat exchanger to exchange heat with the working fluid to generate high-temperature and high-pressure steam; transport the high-temperature and high-pressure steam to the steam turbine generator set to generate electricity, and the generated electricity is incorporated into the power grid to achieve deep peak regulation of the power grid; The third unit is used to monitor the changes in the grid load in real time. When it is detected that the grid load has reached a preset peak threshold, the peak regulation mode is started; in the peak regulation mode, the flow rate of the molten salt circulation pump is increased to improve the hot molten salt delivery rate, and the heat exchange efficiency of the molten salt heat exchanger is adjusted to generate more high-temperature and high-pressure steam; the steam turbine generator set is controlled to increase the power generation capacity, and the additional electricity is incorporated into the grid to achieve grid peak load regulation.

9. An electronic device, characterized in that: include: processor; a memory for storing processor-executable instructions; The processor is configured to call the instructions stored in the memory to execute the method described in any one of claims 1 to 7.

10. A computer-readable storage medium having computer program instructions stored thereon, characterized in that: When the computer program instructions are executed by a processor, the method according to any one of claims 1 to 7 is implemented.

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