Variable frequency induction electric heating energy storage system and control method thereof

Abstract

The application relates to the technical field of electric heat energy storage, in particular to a variable-frequency induction electric heat energy storage system and a control method thereof, which comprises a multi-pulse rectification module, a variable-frequency circuit, an induction heating coil and a heat storage and power generation module, wherein the multi-pulse rectification module converts the electric energy of a three-phase alternating current power grid into stable direct current, the variable-frequency circuit converts the direct current into medium-frequency alternating current, the induction heating coil heats the working medium in a heat storage tank, and the heat storage and power generation module utilizes the heated working medium to generate steam to drive a steam turbine generator to generate power and output the power to the three-phase alternating current power grid. The application has the effects of improving the heating efficiency and response speed of the electric heat energy storage system and improving the stability and reliability of the system.

Description

Technical Field

[0001] The present application relates to the technical field of electrothermal energy storage, and in particular to a variable frequency induction electrothermal energy storage system and a control method thereof. Background Art

[0002] As an important energy storage method, electrothermal energy storage technology plays a key role in power systems. Especially with the widespread adoption of unstable power sources like photovoltaics and wind power, electrothermal energy storage can effectively balance supply and demand, improve energy efficiency, and reduce power curtailment, thereby promoting the widespread use and development of clean energy. Furthermore, electrothermal energy storage can also help smooth peak demand and fill valleys in power systems, helping to optimize grid scheduling and improve power system stability and reliability.

[0003] Currently, electric thermal energy storage is primarily achieved through resistance heating, which converts electrical energy into heat and stores it in a medium such as molten salt. Common methods include direct resistance heating and indirect resistance heating. Direct resistance heating involves heating by inserting electrodes directly into the heat storage medium and is suitable for media with good electrical conductivity. Indirect resistance heating, in which heat energy is transferred to the heat storage medium via a heating element, is widely used and applicable to a variety of heat storage media. In addition, there are also new heating methods, such as electromagnetic induction heating, which uses high-frequency electromagnetic fields to generate eddy currents in the heat storage medium, thereby achieving rapid heating.

[0004] However, existing electric thermal energy storage systems still face several challenges in practical application. While traditional resistive heating methods are simple and reliable, they suffer from low heating efficiency and slow response times in large-capacity energy storage systems. This is particularly true for applications requiring fast response and high power density, where traditional methods struggle to meet these requirements. Furthermore, the uneven distribution of heat generated during resistive heating can lead to localized overheating, shortening the lifespan of the heat storage medium. Therefore, there is room for improvement. Summary of the Invention

[0005] In order to improve the heating efficiency and response speed of the electrothermal energy storage system and enhance the stability and reliability of the system, the present application provides a variable frequency induction electrothermal energy storage system and a control method thereof.

[0006] In a first aspect, the present application provides a variable frequency induction electric thermal energy storage system, which adopts the following technical solutions:

[0007] A variable frequency induction electrothermal energy storage system comprises a multi-pulse rectifier module, a frequency conversion circuit, an induction heating coil, and a heat storage and power generation module. The input end of the multi-pulse rectifier module is connected to a three-phase AC power grid, and the output end is connected to a DC bus. The input end of the frequency conversion circuit is connected to the DC bus, and the output end is connected to a medium frequency induction heating coil. The induction heating coil is used to heat the working fluid in a heat storage tank in the heat storage and power generation module. The heat storage and power generation module comprises a heat storage tank, a steam turbine generator, a condenser, and a feedwater pump. The working fluid in the heat storage tank is heated to generate steam, which drives the steam turbine generator to generate electricity. The output end of the steam turbine generator is connected to the three-phase AC power grid. The condenser is used to condense the steam to generate water, and the feedwater pump is used to return the water to the heat storage tank.

[0008] By implementing the above technical solution, the multi-pulse rectifier module effectively converts power from the three-phase AC grid into stable DC power and transmits it to the DC bus. The frequency conversion circuit converts the DC power on the DC bus into medium-frequency AC power for the induction heating coil. The induction heating coil quickly and efficiently heats the working fluid in the heat storage tank, rapidly raising its temperature and generating steam. The working fluid in the heat storage tank can be conventional molten salt or iron alloys, which have excellent thermal stability and high heat storage density. The steam turbine generator converts the steam generated by the heat storage tank into electricity and outputs it to the three-phase AC grid, achieving efficient storage and release of electrical energy. The condenser condenses the steam into water, which is then returned to the heat storage tank via a feedwater pump, forming a closed-loop circulation system. The system also integrates exhaust gas waste heat recovery, transferring heat from the high-temperature exhaust gas to the working fluid in the heat storage tank via a heat exchanger, further improving energy efficiency. The synergistic effect of various technical measures throughout the system not only improves energy conversion efficiency, but also reduces operating costs and enhances overall system performance.

[0009] Optionally, the three-phase AC power grid is a large power grid, and the new energy power generation system is connected in parallel with the DC bus. The new energy power generation system includes solar photovoltaic panels and wind turbines. The solar photovoltaic panels and wind turbines are respectively connected to the DC bus through DC-DC converters. The DC-DC converter is used to adjust and stabilize the DC bus voltage.

[0010] By adopting the above technical solution, the new energy power generation system (including solar photovoltaic panels and wind turbines) is connected in parallel with the DC bus, so that the new energy can directly provide electricity to the DC bus, reducing the energy conversion link, improving the utilization rate of new energy and the overall efficiency of the system, and regulating and stabilizing the DC bus voltage through the DC-DC converter to ensure the stability of the voltage on the DC bus, thereby improving the stability and reliability of the entire system. The direct parallel connection of the new energy power generation system and the DC bus simplifies the system architecture and reduces construction and maintenance costs.

[0011] Optionally, the three-phase AC power grid is a system local power grid, and the new energy power generation system is connected in parallel with the three-phase AC power grid. The new energy power generation system includes solar photovoltaic panels and wind turbines. The solar photovoltaic panels and wind turbines are respectively connected to the three-phase AC power grid through AC-DC converters. The AC-DC converter is used to adjust and stabilize the voltage of the three-phase AC power grid.

[0012] By implementing this technical solution, the system's local power grid and renewable energy generation system are effectively integrated. Specifically, the solar photovoltaic panels and wind turbines are connected to the three-phase AC grid via AC-DC converters. This not only regulates and stabilizes the voltage of the three-phase AC grid, but also improves renewable energy utilization and system stability. This configuration enables the system to operate independently without being connected to the main grid, further reducing construction and operating costs and improving economic benefits.

[0013] Optionally, the three-phase AC power grid is a system local power grid, and the new energy power generation system is connected in parallel with the DC bus. The new energy power generation system includes solar photovoltaic panels and wind turbines. The solar photovoltaic panels and wind turbines are respectively connected to the DC bus through DC-DC converters. The DC-DC converter is used to adjust and stabilize the DC bus voltage.

[0014] By adopting the above technical solution, the system uses a local power grid, reducing dependence on the large power grid, lowering construction and operation costs, and improving economic benefits. The DC-DC converter can regulate and stabilize the DC bus voltage, ensuring the stability and reliability of the system.

[0015] Optionally, the frequency conversion circuit is an IGBT-based bridge inverter circuit, which includes multiple IGBT switches connected in series and parallel. The IGBT switches are switched by PWM control signals, and the PWM control signals are generated by a controller. The controller adjusts the duty cycle of the PWM signal according to the system load demand and energy storage status; the multi-pulse rectifier module has a three-phase input and a 24-pulse transformer rectifier output. The multi-pulse rectifier module includes multiple rectifier bridges, each rectifier bridge receives a different phase of the three-phase AC power grid, and the DC power output by the rectifier bridge is output to the DC bus after filtering and voltage stabilization.

[0016] By adopting this technical solution, the frequency conversion circuit uses an IGBT-based bridge inverter circuit. PWM control signals precisely regulate the operation of the IGBT switches, enabling the system to operate efficiently across a wide frequency range and adapt to diverse operating conditions. The multi-pulse rectifier module utilizes a three-phase input and 24-pulse transformer-rectifier output design, significantly improving the power factor on the AC grid side, reducing harmonic interference, and enhancing the system's power quality and reliability.

[0017] Optionally, the heat storage and power generation module is connected to an exhaust gas waste heat recovery system, which includes a heat exchanger, which is used to transfer heat in the high-temperature exhaust gas to the working medium in the heat storage tank. The inlet and outlet of the heat exchanger are provided with temperature sensors for monitoring the intake and exhaust temperatures of the exhaust gas; the heat storage and power generation module also includes a cooling device for cooling the heat storage tank, the cooling device includes a water-cooled radiator and a fan, the water-cooled radiator is used to transfer heat in the heat storage tank to cooling water, and the fan is used for forced ventilation to accelerate the cooling rate of the cooling water; the heat storage and power generation module also includes a pressure regulating valve for regulating the pressure in the heat storage tank, the pressure regulating valve is installed on the top of the heat storage tank, and the pressure regulating valve automatically adjusts the opening according to the feedback signal of the pressure sensor to keep the pressure in the heat storage tank within a set range.

[0018] By adopting the above technical solution, the heat storage and power generation module is connected to the exhaust gas waste heat recovery system, which can effectively utilize the heat in the high-temperature exhaust gas, further improve the energy utilization rate of the system, and reduce energy waste. The design of the heat exchanger makes the heat transfer more uniform and efficient, and the temperature sensor monitors the intake and exhaust temperatures of the exhaust gas in real time to ensure the stable operation of the system. The cooling device includes a water-cooled radiator and a fan, which can quickly and effectively transfer the heat in the heat storage tank to the cooling water, and accelerate the cooling rate of the cooling water through the fan to keep the temperature in the heat storage tank within the set range and prevent overheating. The pressure regulating valve automatically adjusts the opening according to the feedback signal of the pressure sensor to keep the pressure in the heat storage tank within a safe range, ensuring the safety and reliability of the system.

[0019] In a second aspect, the present application provides a control method for the above-mentioned variable frequency induction electric thermal energy storage system, which adopts the following technical solutions:

[0020] A variable frequency induction electrothermal energy storage control method, the variable frequency induction electrothermal energy storage control method comprising the steps of:

[0021] Obtaining grid parameters output by a three-phase AC grid, and obtaining operating parameters of the induction heating coil based on the grid parameters;

[0022] Starting the induction heating coil according to the working parameters of the induction heating coil to heat the working fluid in the heat storage tank and obtaining the working fluid temperature in real time;

[0023] Inputting the working fluid heating data into a preset heating analysis model to obtain a working fluid heating result, and generating an electric energy conversion instruction according to the working fluid heating result;

[0024] In response to the electric energy conversion instruction, the steam in the heat storage tank is converted into electric energy, and the output value is sent to the three-phase AC power grid.

[0025] By adopting the above technical solution, the voltage and current of the three-phase AC power grid are monitored to ensure that the grid parameters meet the system requirements, thereby ensuring the normal operation of subsequent components. The power of the three-phase AC power grid is converted into stable DC power, improving the system's power factor, reducing harmonic pollution, and ensuring the quality of the power. The DC power is converted into medium-frequency AC power, which improves the efficiency of induction heating and enables the working fluid in the heat storage tank to heat up quickly. The induction heating coil directly heats the working fluid in the heat storage tank using the medium-frequency AC power. Compared with traditional resistance heating methods, this induction heating method can convert electrical energy into heat more quickly and evenly. Real-time acquisition of working fluid heating data can dynamically adjust the operating parameters of the induction heating coil to ensure that the working fluid heats up according to the predetermined curve, avoiding overheating or underheating. The heating analysis model can accurately predict the heating effect of the working fluid and determine whether it has reached the ideal temperature. If the working fluid temperature reaches a preset value, the system automatically generates an electrical energy conversion instruction, preparing for the next energy conversion process. When the working fluid temperature in the thermal storage tank reaches the preset value, the working fluid is heated to a sufficiently high temperature, generating high-pressure steam. This steam drives a steam turbine generator, efficiently converting thermal energy into electrical energy. Ultimately, this electrical energy is output through the three-phase AC power grid for user use or fed back into the grid, achieving efficient energy utilization. This not only enables efficient electric thermal energy storage and energy conversion, but also ensures system stability and safety.

[0026] In a preferred example of the present application, before obtaining the operating parameters of the induction heating coil based on the grid parameters, the variable frequency induction electric heating energy storage control method further includes:

[0027] Detect the voltage and current output of the three-phase AC power grid and obtain the power grid output data detection results;

[0028] Grid parameters are determined based on the detection result of the grid output data, and the grid parameters are converted into operating parameters of the induction heating coil through a multi-pulse rectifier module and a frequency conversion circuit.

[0029] By adopting this technical solution, the voltage and current of the three-phase AC grid can be monitored in real time, ensuring that grid parameters meet system operating requirements. Based on the grid output data detection results, the grid parameters are accurately determined. Then, through the coordinated action of the multi-pulse rectifier module and the frequency conversion circuit, the grid parameters are converted to parameters suitable for the induction heating coil. This improves the stability and reliability of the system and ensures that the working fluid in the heat storage tank can be heated efficiently and safely.

[0030] In a preferred example of the present application, the inputting of the working fluid heating data into a preset heating analysis model to obtain the working fluid heating result specifically includes:

[0031] A safety threshold line is set in the preset heating analysis model, and the working medium heating data is input into the heating analysis model to obtain the area of ​​the region exceeding the safety threshold line;

[0032] The area of ​​the region is compared with a preset area value, and a working medium heating result is obtained based on the comparison result.

[0033] By adopting the above technical solution, the working fluid heating data obtained in real time is input into a preset heating analysis model. A safety threshold line is set in the heating analysis model. The area of ​​the region where the working fluid heating data exceeds the safety threshold line is calculated. The size of the regional area is used to identify whether the working fluid heating process in the heat storage tank has reached the preset situation, ensuring the safety and controllability of the heating process and avoiding overheating or overpressure.

[0034] In a preferred example of the present application, after responding to the electric energy conversion instruction, converting the steam in the heat storage tank into electric energy, and outputting the electric energy to the three-phase AC grid, the variable frequency induction electric thermal energy storage control method further includes:

[0035] Start the condenser to condense the steam into water, and send the water back to the heat storage tank through the feed water pump;

[0036] Start the exhaust gas waste heat recovery system to transfer the heat in the high-temperature exhaust gas to the working fluid in the heat storage tank, while monitoring the intake and exhaust temperatures of the exhaust gas;

[0037] Start the cooling device to transfer the heat in the heat storage tank to the cooling water, and start the fan to accelerate the cooling rate of the cooling water to keep the temperature in the heat storage tank within the set range.

[0038] By adopting the above technical solution, the condenser is started to condense the steam into water, and the water is returned to the heat storage tank through the water pump, forming a closed-loop water circulation system, which reduces the consumption of water resources, transfers the heat in the high-temperature exhaust gas to the working fluid in the heat storage tank, and monitors the intake and exhaust temperatures of the exhaust gas at the same time, further improving the energy utilization rate of the system and reducing energy consumption. The heat in the heat storage tank is transferred to the cooling water, and the fan is started to accelerate the cooling rate of the cooling water, keeping the temperature in the heat storage tank within the set range, ensuring the stable operation of the system in a high-temperature environment, and extending the life of the equipment.

[0039] In summary, this application includes at least one of the following beneficial technical effects:

[0040] The multi-pulse rectifier module can effectively convert the power of a three-phase AC power grid into stable DC power and transmit it to the DC bus. The frequency conversion circuit converts the DC power on the DC bus into intermediate frequency AC power for the induction heating coil. The induction heating coil rapidly and efficiently heats the working medium in the heat storage tank, causing the working medium to rapidly heat up and produce steam. The working medium in the heat storage tank can be selected from conventional molten salt or iron alloy, which has good thermal stability and high heat storage density. The steam turbine generator converts the steam generated by the heat storage tank into electrical energy and outputs it to the three-phase AC power grid, achieving efficient storage and release of electrical energy. The condenser is responsible for condensing the steam into water, which is then pumped back to the heat storage tank, forming a closed loop circulation system. In addition, the system also integrates a tail gas waste heat recovery function, which transfers heat from high-temperature tail gas to the working medium in the heat storage tank through a heat exchanger, further improving energy utilization efficiency. Through the synergistic effect of various technical means during the operation of the entire system, not only the energy conversion efficiency is improved, but also the operating cost is reduced, and the overall performance of the system is improved;

[0041] By detecting the voltage and current of the three-phase AC power grid, it is ensured that the grid parameters meet the requirements of the system, thereby ensuring the normal operation of the subsequent components. The electrical energy of the three-phase AC power grid is converted into stable DC power, which improves the power factor of the system, reduces harmonic pollution, and ensures the quality of electrical energy. The DC power is converted into intermediate frequency AC power, which improves the efficiency of induction heating and allows the working medium in the heat storage tank to heat up quickly. The DC power is converted into intermediate frequency AC power, which improves the efficiency of induction heating and allows the working medium in the heat storage tank to heat up quickly. The induction heating coil directly heats the working medium in the heat storage tank through intermediate frequency AC power, which can convert electrical energy into heat energy more quickly and uniformly compared to traditional resistance heating methods. Real-time acquisition of working medium heating data allows dynamic adjustment of the working parameters of the induction heating coil to ensure that the working medium heating follows the predetermined curve and avoids overheating or insufficient heating. Through the heating analysis model, the heating effect of the working medium can be accurately predicted to determine whether the ideal temperature has been reached. If the working medium temperature reaches the preset value, the system will automatically generate an electrical energy conversion command to prepare for the next energy conversion process. When the working medium temperature in the heat storage tank reaches the preset value, the working medium will be heated to a high enough temperature to generate high-pressure steam. These steam drives the steam turbine generator to efficiently convert thermal energy into electrical energy. Finally, the electrical energy is output through the three-phase AC power grid for user use or feedback to the grid, achieving efficient utilization of energy. Not only can it achieve efficient electrical energy storage and energy conversion, but it can also ensure the stability and safety of the system;

[0042] The condenser is started, steam is condensed into water, and the water is sent back to the heat storage tank through the feed water pump, forming a closed water circulation system, reducing the consumption of water resources, transferring the heat in the high-temperature tail gas to the working medium in the heat storage tank, monitoring the inlet and outlet temperatures of the tail gas, further improving the energy utilization rate of the system, reducing the energy consumption, transferring the heat in the heat storage tank to the cooling water, starting the fan to speed up the cooling speed of the cooling water, keeping the temperature in the heat storage tank within the set range, ensuring the stable operation of the system in the high-temperature environment, and prolonging the service life of the equipment. BRIEF DESCRIPTION OF DRAWINGS

[0043] Figure 1 is a circuit diagram of a variable frequency induction electric heating energy storage system according to an embodiment of the present application.

[0044] Figure 2 is an implementation flowchart of a variable frequency induction electric heating energy storage control method according to an embodiment of the present application.

[0045] Figure 3 is another implementation flowchart of a variable frequency induction electric heating energy storage control method according to an embodiment of the present application.

[0046] Figure 4 is an implementation flowchart of step S30 in a variable frequency induction electric heating energy storage control method according to an embodiment of the present application.

[0047] Figure 5 is another implementation flowchart of a variable frequency induction electric heating energy storage control method according to an embodiment of the present application.

[0048] Reference signs: 1, multi-pulse rectification module; 2, variable frequency circuit; 3, induction heating coil; 4, heat storage and power generation module; 5, DC bus. DETAILED DESCRIPTION

[0049] In order to make the purpose, technical scheme and advantages of the present application clearer, the following will combine the drawings of the present application with specific embodiments of the present application to make a better understanding of the present application. Figures 1-5 The present application will be further described in detail.

[0050] The present application discloses a variable frequency induction electric heating energy storage system. Referring to Figure 1The variable frequency induction electric thermal energy storage system includes a multi-pulse rectifier module 1, a frequency conversion circuit 2, an induction heating coil 3, and a heat storage and power generation module 4. The input of the multi-pulse rectifier module 1 is connected to the three-phase AC grid, and the output is connected to the DC bus 5. The input of the frequency conversion circuit 2 is connected to the DC bus 5, and the output is connected to the medium-frequency induction heating coil 3. The induction heating coil 3 is used to heat the working fluid in the heat storage tank of the heat storage and power generation module 4. The heat storage and power generation module 4 includes a heat storage tank, a steam turbine generator, a condenser, and a feedwater pump. The working fluid in the heat storage tank is heated to generate steam, which drives the steam turbine generator to generate electricity. The output of the steam turbine generator is connected to the three-phase AC grid. The condenser is used to condense the steam to generate water, and the feedwater pump is used to return the water to the heat storage tank.

[0051] Specifically, the multi-pulse rectifier module 1 includes multiple rectifier bridges, each receiving a different phase of the three-phase AC grid. The DC power output by the rectifier bridges is filtered and stabilized before being output to the DC bus 5. The multi-pulse rectifier module 1 can utilize a three-phase input with a 24-pulse transformer-rectifier output. Alternatively, the multi-pulse rectifier module 1 can utilize a three-phase input with a 12-pulse transformer-rectifier output to accommodate different application scenarios.

[0052] Frequency conversion circuit 2 utilizes an IGBT-based bridge inverter circuit, comprising multiple IGBT switches connected in series and parallel. The IGBT switches are switched on and off using PWM control signals generated by a controller, which adjusts the PWM signal's duty cycle based on system load requirements and energy storage status. Frequency conversion circuit 2 can operate over a wide frequency range, such as 50Hz to 2000Hz, allowing the appropriate induction power supply frequency to be selected based on different operating conditions and working fluids, ensuring optimal adaptation to system operation. Furthermore, frequency conversion circuit 2 can utilize a MOSFET-based bridge inverter circuit to increase switching frequency and efficiency.

[0053] The induction heating coil 3 is used to heat the working fluid within the heat storage tank. The induction heating coil 3 can utilize a single-layer or multi-layer spiral coil structure. The coil diameter and number of turns can be adjusted based on the size of the heat storage tank and the characteristics of the working fluid. For example, for large heat storage tanks, a multi-layer spiral coil can be used to increase the heating area and efficiency. Furthermore, the induction heating coil 3 can be a planar coil or a toroidal coil to accommodate different heat storage tank shapes and layouts.

[0054] The heat storage and power generation module 4 includes a heat storage tank, a steam turbine generator, a condenser, and a feedwater pump. The working fluid in the heat storage tank can be conventional molten salt or ferroalloy. Conventional molten salt includes a mixture of potassium nitrate, sodium nitrate, and sodium nitrite. Ferroalloys include mild steel, stainless steel, or other iron-based alloys. The design of the heat storage tank should take into account high-temperature and corrosion resistance. Commonly used materials include stainless steel and nickel-based alloys. A stirring device can be installed inside the heat storage tank to ensure uniform heating of the working fluid. In addition, the heat storage tank can also be equipped with a temperature sensor and a pressure sensor for real-time monitoring of the working fluid temperature and pressure.

[0055] The steam turbine generator converts steam generated by the heat storage tank into electrical energy and outputs it to the three-phase AC grid. The design of the turbine generator should consider efficient energy conversion and stability. Common types include back-pressure and condensing turbines. Back-pressure turbines are suitable for applications requiring continuous power supply, while condensing turbines are suitable for applications requiring efficient energy conversion. The output of the turbine generator can be connected to the three-phase AC grid via a transformer and circuit breaker to achieve efficient transmission of electrical energy. The condenser condenses steam to produce water. Common condenser types include surface condensers and jet condensers. Surface condensers condense steam into water using a condensing tube bundle, while jet condensers condense steam by injecting cold water. The condenser design should consider cooling efficiency and ease of maintenance. Common materials include copper, aluminum, and other metals with good thermal conductivity. The feedwater pump returns water to the heat storage tank. The feedwater pump selection should consider flow rate and head requirements. Common feedwater pump types include centrifugal pumps and plunger pumps. Centrifugal pumps are suitable for high flow and low head applications, while plunger pumps are suitable for low flow and high head applications. Filters and check valves should be installed at the inlet and outlet of the water pump to prevent impurities from entering the system and to avoid water backflow.

[0056] The three-phase AC power grid can be a large power grid or a local system grid. The renewable energy generation system is connected in parallel with the DC bus 5 or the three-phase AC grid. It includes solar photovoltaic panels and wind turbines, which are connected to the DC bus 5 or the three-phase AC grid via DC-DC converters or AC-DC converters, respectively. The DC-DC converters or AC-DC converters are used to regulate and stabilize the voltage of the DC bus 5 or the three-phase AC grid. The selection of solar photovoltaic panels and wind turbines should take into account environmental conditions and installation location. Solar photovoltaic panels should be made of high-efficiency, weather-resistant single-crystalline silicon or thin-film solar cells. Wind turbines should be vertical-axis or horizontal-axis wind turbines with a wide wind speed range and low noise. The design of the DC-DC converter or AC-DC converter should consider efficiency and reliability. Common types include boost converters, buck converters, single-phase full-bridge converters, and three-phase full-bridge converters.

[0057] The heat storage and power generation module 4 can also be connected to an exhaust gas waste heat recovery system. This exhaust gas waste heat recovery system includes a heat exchanger for transferring heat from the high-temperature exhaust gas to the working fluid in the heat storage tank. Temperature sensors are installed at the inlet and outlet of the heat exchanger to monitor the intake and exhaust temperatures of the exhaust gas. The heat storage and power generation module 4 also includes a cooling device for cooling the heat storage tank. The cooling device includes a water-cooled radiator and a fan. The water-cooled radiator transfers heat from the heat storage tank to cooling water, and the fan provides forced ventilation to accelerate the cooling rate of the cooling water. The heat storage and power generation module 4 also includes a pressure regulating valve for regulating the pressure in the heat storage tank. The pressure regulating valve is installed at the top of the heat storage tank and automatically adjusts its opening based on feedback from the pressure sensor to maintain the pressure in the heat storage tank within a set range.

[0058] The implementation principle of a variable frequency induction electric thermal energy storage system in an embodiment of the present application is as follows: the electric energy of the three-phase AC power grid is converted into stable direct current through a multi-pulse rectifier module 1, and then the direct current is converted into medium frequency AC through a frequency conversion circuit 2, and finally the working medium in the heat storage tank is heated by an induction heating coil 3. After the working medium in the heat storage tank is heated, steam is generated, and the steam drives the steam turbine generator to generate electricity. The output end of the steam turbine generator is connected to the three-phase AC power grid, thereby realizing the effective storage and release of electric energy. The design of the entire system fully considers the energy conversion efficiency and stability, and is suitable for large-scale energy storage and new energy power generation. The introduction of the new energy power generation system improves the flexibility and sustainability of the system, and is suitable for large-scale energy storage and new energy power generation. The addition of the exhaust gas waste heat recovery system further improves the energy utilization rate of the system and reduces energy waste. The setting of the cooling device and the pressure regulating valve ensures the safe and stable operation of the system, and is suitable for large-scale energy storage and new energy power generation.

[0059] In one embodiment, if Figure 2 As shown, the present application also discloses a variable frequency induction electrothermal energy storage control method, which includes the following steps:

[0060] S10: Obtain grid parameters output by the three-phase AC grid, and obtain operating parameters of the induction heating coil based on the grid parameters.

[0061] Specifically, the voltage and current of the three-phase AC power grid are detected to ensure that the grid parameters meet the requirements of the system, thereby ensuring the normal operation of subsequent components. The electric energy of the three-phase AC power grid is converted into stable DC power, which improves the power factor of the system, reduces harmonic pollution, and ensures the quality of electric energy. The DC power is converted into medium-frequency AC power, which improves the efficiency of induction heating and enables the working fluid in the heat storage tank to heat up quickly. The DC power is converted into medium-frequency AC power, which improves the efficiency of induction heating and enables the working fluid in the heat storage tank to heat up quickly. The induction heating coil directly heats the working fluid in the heat storage tank through medium-frequency AC power. Compared with traditional resistance heating methods, this induction heating method can convert electrical energy into heat energy faster and more evenly.

[0062] S20: starting the induction heating coil according to the working parameters of the induction heating coil, heating the working medium in the heat storage tank, and acquiring working medium heating data in real time.

[0063] Specifically, by acquiring the working fluid heating data in real time, the working parameters of the induction heating coil can be dynamically adjusted. The working fluid heating data includes the working fluid heating temperature and pressure, ensuring that the working fluid heating rises according to a predetermined curve to avoid overheating or insufficient heating.

[0064] S30: Inputting the working fluid heating data into a preset heating analysis model to obtain a working fluid heating result, and generating an electric energy conversion instruction according to the working fluid heating result.

[0065] Specifically, through the heating analysis model, the heating effect of the working fluid can be accurately predicted and whether the ideal temperature has been reached can be determined. If the working fluid temperature reaches the preset value, the system will automatically generate an electric energy conversion instruction to prepare for the next energy conversion process.

[0066] S40: In response to the electric energy conversion instruction, the steam in the heat storage tank is converted into electric energy, and the output value is sent to the three-phase AC power grid.

[0067] Specifically, when the working fluid in the thermal storage tank reaches a preset temperature, it is heated to a sufficiently high temperature, generating high-pressure steam. This steam drives a turbine generator, efficiently converting thermal energy into electrical energy. Ultimately, this electrical energy is output through the three-phase AC grid for user use or fed back into the grid, achieving efficient energy utilization.

[0068] In one embodiment, if Figure 3 As shown, before obtaining the operating parameters of the induction heating coil based on the grid parameters, the variable frequency induction electric heating energy storage control method further includes:

[0069] S101: Detect the voltage and current output by the three-phase AC power grid and obtain the power grid output data detection result.

[0070] S102: Determine the grid parameter based on the grid output data detection result, and convert the grid parameter through the multi-pulse rectifier module and the frequency conversion circuit to form the working parameter of the induction heating coil.

[0071] Specifically, the voltage and current of the three-phase alternating current grid are monitored in real time to ensure that the grid parameter meets the system operation requirements. Based on the grid output data detection result, the grid parameter is accurately determined, and then through the synergistic effect of the multi-pulse rectifier module and the frequency conversion circuit, the grid parameter is converted into a parameter suitable for the working of the induction heating coil, thereby improving the stability and reliability of the system and ensuring that the working medium in the heat storage tank can be heated efficiently and safely.

[0072] In an embodiment, as shown in Figure 4 The working medium heating data is input into the preset heating analysis model to obtain the working medium heating result, specifically including:

[0073] S31: The preset heating analysis model is provided with a safety threshold line, the working medium heating data is input into the heating analysis model, and the area of the region exceeding the safety threshold line is obtained.

[0074] S32: Compare the area with a preset area value, and obtain the working medium heating result based on the comparison result.

[0075] Specifically, the working medium heating data obtained in real time is input into the preset heating analysis model, the heating analysis model is provided with a safety threshold line, the area of the region exceeding the safety threshold line is calculated, and whether the working medium heating process in the heat storage tank reaches the preset condition is identified according to the size of the area, so as to ensure the safety and controllability of the heating process and avoid overheating or overpressure.

[0076] In an embodiment, as shown in Figure 5 After responding to the electric energy conversion instruction, converting the steam in the heat storage tank into electric energy, and outputting the three-phase alternating current grid, the frequency conversion induction electric heating energy storage control method further includes:

[0077] S50: Start the condenser to condense the steam into water, and send the water back to the heat storage tank through the feed water pump.

[0078] S60: Start the tail gas waste heat recovery system to transfer the heat in the high-temperature tail gas to the working medium in the heat storage tank, and monitor the inlet and outlet temperatures of the tail gas.

[0079] S70: Start the cooling device to transfer the heat in the heat storage tank to the cooling water, and start the fan to accelerate the cooling speed of the cooling water, so as to keep the temperature in the heat storage tank within the set range.

[0080] Specifically, the condenser is started, steam is condensed into water, and the water is sent back to the heat storage tank through the feed water pump to form a closed water circulation system, which reduces the consumption of water resources, transfers the heat in the high-temperature tail gas to the working medium in the heat storage tank, monitors the inlet and outlet temperatures of the tail gas, further improves the energy utilization rate of the system, reduces the energy consumption, transfers the heat in the heat storage tank to the cooling water, starts the fan to speed up the cooling speed of the cooling water, keeps the temperature in the heat storage tank within the set range, ensures the stable operation of the system in the high-temperature environment, and prolongs the service life of the equipment.

[0081] The above are preferred embodiments of the present application, and are not intended to limit the protection scope of the present application, therefore: any equivalent changes made on the basis of the structure, shape, principle of the present application should be covered within the protection scope of the present application.

Claims

1. A variable frequency induction electric thermal energy storage system, characterized by: The invention comprises a multi-pulse rectifier module (1), a frequency conversion circuit (2), an induction heating coil (3) and a heat storage and power generation module (4), wherein the input end of the multi-pulse rectifier module (1) is connected to a three-phase AC power grid, and the output end is connected to a DC bus (5), the input end of the frequency conversion circuit (2) is connected to the DC bus (5), and the output end is connected to the medium-frequency induction heating coil (3), the induction heating coil (3) is used to heat the working medium in the heat storage tank in the heat storage and power generation module (4), the heat storage and power generation module (4) comprises a heat storage tank, a steam turbine generator, a condenser and a feed water pump, the working medium in the heat storage tank is heated to generate steam, the steam drives the steam turbine generator to generate electricity, the output end of the steam turbine generator is connected to the three-phase AC power grid, the condenser is used to condense the steam to generate water, and the feed water pump is used to return the water to the heat storage tank; The heat storage and power generation module (4) is connected to the exhaust gas waste heat recovery system, and the exhaust gas waste heat recovery system includes a heat exchanger, and the heat exchanger is used to transfer the heat in the high-temperature exhaust gas to the working medium in the heat storage tank. The inlet and outlet of the heat exchanger are provided with temperature sensors for monitoring the intake and exhaust temperatures of the exhaust gas; the heat storage and power generation module (4) also includes a cooling device for cooling the heat storage tank, and the cooling device includes a water-cooled radiator and a fan. The water-cooled radiator is used to transfer the heat in the heat storage tank to cooling water, and the fan is used for forced ventilation to accelerate the cooling rate of the cooling water; the heat storage and power generation module (4) also includes a pressure regulating valve for regulating the pressure in the heat storage tank, and the pressure regulating valve is installed on the top of the heat storage tank. The pressure regulating valve automatically adjusts the opening according to the feedback signal of the pressure sensor to keep the pressure in the heat storage tank within a set range; The control method based on the variable frequency induction electric thermal energy storage system is as follows: Obtaining grid parameters output by a three-phase AC grid, and obtaining operating parameters of the induction heating coil based on the grid parameters; The induction heating coil is started according to the working parameters of the induction heating coil to heat the working medium in the heat storage tank and obtain the working medium temperature in real time; Inputting the working fluid heating data into a preset heating analysis model to obtain a working fluid heating result, and generating an electric energy conversion instruction based on the working fluid heating result, specifically including: A safety threshold line is set in the preset heating analysis model, and the working medium heating data is input into the heating analysis model to obtain the area of ​​the region exceeding the safety threshold line; Comparing the area of ​​the region with a preset area value, and obtaining a working medium heating result based on the comparison result; In response to the electric energy conversion instruction, the steam in the heat storage tank is converted into electric energy and output to the three-phase AC power grid.

2. The variable frequency induction electric thermal energy storage system according to claim 1, characterized in that: The three-phase AC power grid is a large power grid, and a new energy power generation system is connected in parallel with a DC bus (5). The new energy power generation system includes a solar photovoltaic panel and a wind turbine generator. The solar photovoltaic panel and the wind turbine generator are respectively connected to the DC bus (5) via a DC-DC converter. The DC-DC converter is used to adjust and stabilize the voltage of the DC bus (5).

3. The variable frequency induction electric thermal energy storage system according to claim 1, characterized in that: The three-phase AC power grid is a local power grid of the system, and a new energy power generation system is connected in parallel with the three-phase AC power grid. The new energy power generation system includes solar photovoltaic panels and wind turbines. The solar photovoltaic panels and wind turbines are respectively connected to the three-phase AC power grid through AC-DC converters. The AC-DC converters are used to regulate and stabilize the voltage of the three-phase AC power grid.

4. The variable frequency induction electric thermal energy storage system according to claim 1, characterized in that: The three-phase AC power grid is a system local power grid, and a new energy power generation system is connected in parallel with a DC bus (5). The new energy power generation system includes a solar photovoltaic panel and a wind turbine generator. The solar photovoltaic panel and the wind turbine generator are respectively connected to the DC bus (5) via a DC-DC converter. The DC-DC converter is used to adjust and stabilize the voltage of the DC bus (5).

5. The variable frequency induction electric thermal energy storage system according to claim 1, characterized in that: The frequency conversion circuit (2) is an IGBT-based bridge inverter circuit, comprising a plurality of IGBT switches connected in series and in parallel, wherein the IGBT switches are switched on and off by means of a PWM control signal, wherein the PWM control signal is generated by a controller, and the controller adjusts the duty cycle of the PWM signal according to the system load demand and the energy storage state; the multi-pulse rectifier module (1) has a three-phase input and a 24-pulse transformer rectifier output, wherein the multi-pulse rectifier module (1) comprises a plurality of rectifier bridges, each rectifier bridge receiving a different phase of a three-phase AC power grid, and the DC power output by the rectifier bridge is output to a DC bus (5) after filtering and voltage stabilization.

6. The control method of a variable frequency induction electric thermal energy storage system according to claim 1, characterized in that: Before acquiring the operating parameters of the induction heating coil based on the grid parameters, the variable frequency induction electric heating energy storage control method further includes: Detect the voltage and current output of the three-phase AC power grid and obtain the power grid output data detection results; Grid parameters are determined based on the detection result of the grid output data, and the grid parameters are converted into operating parameters of the induction heating coil through a multi-pulse rectifier module and a frequency conversion circuit.

7. The control method of a variable frequency induction electric thermal energy storage system according to claim 1, characterized in that: After responding to the electric energy conversion instruction, converting the steam in the heat storage tank into electric energy, and outputting the electric energy to the three-phase AC grid, the variable frequency induction electric thermal energy storage control method further includes: Start the condenser to condense the steam into water, and send the water back to the heat storage tank through the feed water pump; Start the exhaust gas waste heat recovery system to transfer the heat in the high-temperature exhaust gas to the working fluid in the heat storage tank, while monitoring the intake and exhaust temperatures of the exhaust gas; Start the cooling device to transfer the heat in the heat storage tank to the cooling water, and start the fan to accelerate the cooling rate of the cooling water to keep the temperature in the heat storage tank within the set range.

Images