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

Abstract

The invention relates to the technical field of electric heating energy storage, in particular to a frequency conversion induction electric heating energy storage system and a control method thereof.The frequency conversion induction electric heating energy storage system comprises a multi-pulse rectification module, a frequency conversion circuit, an induction heating coil and a heat storage and power generation module, the frequency conversion circuit converts direct current into medium-frequency alternating current, the induction heating coil heats a working medium in the heat storage tank, and the heat storage and power generation module generates steam through the heated working medium to drive a steam turbine generator to generate power and outputs electric energy to a three-phase alternating current power grid. The heating efficiency and the response speed of the electric heating energy storage system are improved, and the stability and the reliability of the system are improved.

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, electric thermal energy storage technology plays a key role in the power system. Especially in the context of the widespread application of new energy sources such as photovoltaics, wind power and other unstable power sources, electric thermal energy storage can effectively balance the supply and demand relationship, improve energy utilization efficiency, reduce power abandonment, and thus promote the popularization and development of clean energy. In addition, electric thermal energy storage can also play a role in peak shaving and valley filling in the power system, which helps to optimize grid dispatching and improve the stability and reliability of the power system.

[0003] At present, electric thermal energy storage is mainly achieved through resistance heating, that is, converting electrical energy into thermal energy and storing it in a medium such as molten salt. Common methods include direct resistance heating and indirect resistance heating. Direct resistance heating is heating by directly inserting electrodes into the heat storage medium, which is suitable for media with good conductivity. Indirect resistance heating is to transfer heat energy to the heat storage medium through heating elements. This method is widely used and suitable for a variety of heat storage media. In addition, there are some 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 some challenges in practical applications. Although the traditional resistance heating method is simple and reliable, it has problems such as low heating efficiency and slow response speed in large-capacity energy storage systems. Especially for application scenarios that require fast response and high power density, traditional methods are difficult to meet the needs. In addition, the heat generated during resistance heating is unevenly distributed, which may cause local overheating and affect the service life 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 an electric thermal energy storage system and enhance the stability and reliability of the system, the present application provides a variable frequency induction electric thermal 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 solution: A variable frequency induction electric thermal 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, wherein 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 medium 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 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 steam to generate water, and the feed water pump is used to return the water to the heat storage tank.

[0007] By adopting the above technical solution, the multi-pulse rectifier module can effectively convert the electric energy of the 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 medium-frequency AC power for use by the induction heating coil. The induction heating coil quickly and efficiently heats the working fluid in the heat storage tank, causing the working fluid to heat up rapidly and generate steam. The working fluid in the heat storage tank can be selected from conventional molten salt or ferroalloy, which have 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, realizing the effective storage and release of electrical energy. The condenser is responsible for condensing the steam into water, and sending the water back to the heat storage tank through the feed water pump to form a closed-loop circulation system. In addition, the system also integrates the exhaust gas waste heat recovery function, which transfers the heat in the high-temperature exhaust gas to the working fluid in the heat storage tank through the heat exchanger, further improving the energy utilization efficiency. During the operation of the entire system, through the synergistic effect of various technical means, not only the energy conversion efficiency is improved, but also the operating cost is reduced, and the overall performance of the system is improved.

[0008] 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 generators. The solar photovoltaic panels and wind generators are respectively connected to the DC bus through DC-DC converters, and the DC-DC converter is used to adjust and stabilize the DC bus voltage.

[0009] 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 electric energy to the DC bus, reducing the energy conversion links, improving the utilization rate of new energy and the overall efficiency of the system, and adjusting 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 new energy power generation system is directly connected in parallel with the DC bus, which simplifies the system architecture and reduces the construction and maintenance costs.

[0010] Optionally, the three-phase AC power grid is a system local power grid, 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, and the AC-DC converter is used to adjust and stabilize the voltage of the three-phase AC power grid.

[0011] By adopting the above technical solutions, the effective integration of the local power grid and the new energy power generation system is achieved. Specifically, the solar photovoltaic panels and wind turbines are connected to the three-phase AC power grid through AC-DC converters, which can not only adjust and stabilize the voltage of the three-phase AC power grid, but also improve the utilization rate of new energy and the stability of the system. This configuration enables the system to operate independently without the large power grid, further reducing construction and operation costs and improving economic benefits.

[0012] 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, and the DC-DC converter is used to adjust and stabilize the DC bus voltage.

[0013] By adopting the above technical solution, the system adopts a local power grid, reduces dependence on the large power grid, reduces construction and operation costs, and improves economic benefits. The DC-DC converter can adjust and stabilize the DC bus voltage, ensuring the stability and reliability of the system.

[0014] Optionally, the frequency conversion circuit is an IGBT-based bridge inverter circuit, the IGBT inverter circuit includes multiple IGBT switches connected in series and in parallel, the IGBT switch is switched by a PWM control signal, 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 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 different phases of a three-phase AC power grid, and the DC power output by the rectifier bridge is filtered and stabilized before being output to the DC bus.

[0015] By adopting the above technical solutions, the frequency conversion circuit adopts an IGBT-based bridge inverter circuit, and the operation of the IGBT switch is accurately adjusted through the PWM control signal, so that the system can operate efficiently in a wide frequency range and adapt to different working conditions. The multi-pulse rectifier module adopts a three-phase input and 24-pulse transformer rectifier output design, which significantly improves the power factor on the AC grid side, reduces harmonic interference, and improves the power quality and reliability of the system.

[0016] 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, and 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, and the cooling device includes a water-cooled radiator and a fan, and 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 adjusting the pressure in the heat storage tank, and the pressure regulating valve is installed on the top of the heat storage tank, and the pressure regulating valve automatically adjusts the opening through the feedback signal of the pressure sensor to keep the pressure in the heat storage tank within a set range.

[0017] 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 through 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.

[0018] In a second aspect, the present application provides a control method applied to the above-mentioned variable frequency induction electric thermal energy storage system, which adopts the following technical solution: A variable frequency induction electric heating energy storage control method, the variable frequency induction electric heating energy storage control method comprising the steps of: Acquire grid parameters output by a three-phase AC grid, and acquire working 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 fluid in the heat storage tank and obtain the working fluid 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 according to the working fluid heating result; 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 supplied to the three-phase AC power grid.

[0019] By adopting the above technical solution, by detecting the voltage and current of the three-phase AC power grid, ensuring that the grid parameters meet the requirements of the system, thereby ensuring the normal operation of subsequent components, converting the electric energy of the three-phase AC power grid into stable DC power, improving the power factor of the system, reducing harmonic pollution, ensuring the quality of electric energy, converting DC power into medium-frequency AC power, improving the efficiency of induction heating, and enabling the working fluid in the heat storage tank to heat up quickly, converting DC power into medium-frequency AC power, improving the efficiency of induction heating, and enabling the working fluid in the heat storage tank to heat up quickly, and the induction heating coil directly heats the working fluid in the heat storage tank through medium-frequency AC power. Compared with the traditional resistance heating method, this induction heating method can convert electric energy into heat energy faster and more evenly. Real-time acquisition of working fluid heating data can dynamically adjust the working parameters of the induction heating coil to ensure that the working fluid heating rises according to the predetermined curve to avoid overheating or insufficient heating. Through the heating analysis model, the heating effect of the working fluid can be accurately predicted to determine whether the ideal temperature has been reached. 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. When the working fluid temperature in the heat storage tank reaches the preset value, the working fluid will be heated to a sufficiently high temperature to generate high-pressure steam. These steams drive 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 users to use or fed back to the grid, realizing the effective use of energy. It can not only achieve efficient electric thermal energy storage and energy conversion, but also ensure the stability and safety of the system.

[0020] In a preferred example of the present application, before obtaining the working 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 by the three-phase AC power grid and obtain the power grid output data detection results; The grid parameters are determined based on the grid output data detection result, and the grid parameters are converted into working parameters of the induction heating coil through a multi-pulse rectification module and a frequency conversion circuit.

[0021] By adopting the above technical solution, the voltage and current of the three-phase AC power grid can be monitored in real time to ensure that the power grid parameters meet the system operation requirements. Based on the power grid output data detection results, the power grid parameters are accurately determined, and then through the synergy of the multi-pulse rectifier module and the frequency conversion circuit, the power grid parameters are converted into parameters suitable for the operation of the induction heating coil, which improves the stability and reliability of the system and ensures that the working medium in the heat storage tank can be heated efficiently and safely.

[0022] 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: 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 exceeding the safety threshold line; The area of ​​the region is compared with a preset area value, and a working fluid heating result is obtained based on the comparison result.

[0023] By adopting the above technical solution, the working fluid heating data acquired 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 reaches the preset situation, thereby ensuring the safety and controllability of the heating process and avoiding overheating or overpressure.

[0024] 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 value to the three-phase AC power 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, and monitor the intake and exhaust temperatures of the exhaust gas at the same time; 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.

[0025] 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 feed pump, forming a closed-loop water circulation system, reducing the consumption of water resources, transferring the heat in the high-temperature exhaust gas to the working fluid in the heat storage tank, and monitoring 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.

[0026] In summary, the present application includes at least one of the following beneficial technical effects: The multi-pulse rectifier module can effectively convert the electric energy of the three-phase AC 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 medium-frequency AC power for use by the induction heating coil. The induction heating coil quickly and efficiently heats the working fluid in the heat storage tank, causing the working fluid to heat up rapidly and generate steam. The working fluid in the heat storage tank can be made of conventional molten salt or ferroalloy, which have 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 grid, realizing the effective storage and release of electrical energy. The condenser is responsible for condensing the steam into water, and sending the water back to the heat storage tank through the feed water pump to form a closed-loop circulation system. In addition, the system also integrates the exhaust gas waste heat recovery function, which transfers the heat in the high-temperature exhaust gas to the working fluid in the heat storage tank through the heat exchanger, further improving the energy utilization efficiency. During the operation of the entire system, through the synergistic effect of various technical means, not only the energy conversion efficiency is improved, but also the operating cost is reduced, and the overall performance of the system is improved; By detecting the voltage and current of the three-phase AC power grid, ensuring that the grid parameters meet the requirements of the system, thereby ensuring the normal operation of subsequent components, converting the electric energy of the three-phase AC power grid into stable DC power, improving the power factor of the system, reducing harmonic pollution, and ensuring the quality of electric energy, converting DC power into medium-frequency AC power, improving the efficiency of induction heating, and enabling the working fluid in the heat storage tank to heat up quickly, converting DC power into medium-frequency AC power, improving the efficiency of induction heating, and enabling the working fluid in the heat storage tank to heat up quickly, and the induction heating coil directly heats the working fluid in the heat storage tank through medium-frequency AC power. Compared with the traditional resistance heating method, this induction heating method can convert electric energy into heat energy faster and more evenly. Real-time acquisition of working fluid heating data can dynamically adjust the working parameters of the induction heating coil to ensure that the working fluid heating rises according to the predetermined curve to avoid overheating or insufficient heating. Through the heating analysis model, the heating effect of the working fluid can be accurately predicted to determine whether the ideal temperature has been reached. 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. When the working fluid temperature in the heat storage tank reaches the preset value, the working fluid will be heated to a sufficiently high temperature to generate high-pressure steam. These steams drive 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 users to use or fed back to the grid, realizing the effective use of energy. It can not only achieve efficient electric thermal energy storage and energy conversion, but also ensure the stability and safety of the system. Start the condenser to condense the steam into water, and send the water back to the heat storage tank through the water pump, forming a closed-loop water circulation system, reducing the consumption of water resources, transferring the heat in the high-temperature exhaust gas to the working fluid in the heat storage tank, and monitoring 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, transferring the heat in the heat storage tank to the cooling water, and starting the fan 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. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a circuit diagram of a variable frequency induction electric thermal energy storage system according to an embodiment of the present application.

[0028] Figure 2 It is a flow chart for implementing a variable frequency induction electric thermal energy storage control method in an embodiment of the present application.

[0029] Figure 3 This is another implementation flow chart of a variable frequency induction electric thermal energy storage control method according to an embodiment of the present application.

[0030] Figure 4 It is a flow chart for implementing step S30 in a variable frequency induction electric thermal energy storage control method in an embodiment of the present application.

[0031] Figure 5 This is another implementation flow chart of a variable frequency induction electric thermal energy storage control method according to an embodiment of the present application.

[0032] Explanation of the accompanying drawings: 1. Multi-pulse rectifier module; 2. Frequency conversion circuit; 3. Induction heating coil; 4. Heat storage and power generation module; 5. DC bus. DETAILED DESCRIPTION

[0033] In order to make the purpose, technical solutions and advantages of this application more clear, the following Figure 1-5 This application is described in further detail.

[0034] The present application embodiment discloses a variable frequency induction electric thermal energy storage system. 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 end of the multi-pulse rectifier module 1 is connected to the three-phase AC power grid, and the output end is connected to the 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 includes 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, 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, the condenser is used to condense steam to generate water, and the feed water pump is used to return the water to the heat storage tank.

[0035] Specifically, the multi-pulse rectifier module 1 includes a plurality of rectifier bridges, each rectifier bridge receives different phases of the three-phase AC power grid, and the DC power output by the rectifier bridge is filtered and stabilized before being output to the DC bus 5. The multi-pulse rectifier module 1 can use three-phase input and 24-pulse transformer rectifier output. In addition, the multi-pulse rectifier module 1 can also use three-phase input and 12-pulse transformer rectifier output to meet the needs of different application scenarios.

[0036] The frequency conversion circuit 2 adopts an IGBT-based bridge inverter circuit, including multiple IGBT switches connected in series and in parallel. The IGBT switches are switched by PWM control signals. The PWM control signals are 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 frequency conversion circuit 2 can operate in a wide frequency range, such as 50Hz~2000Hz, and can select a suitable induction power supply frequency according to different working conditions and different working fluids to better adapt to the operation of the system. In addition, the frequency conversion circuit 2 can also adopt a MOSFET-based bridge inverter circuit to improve the switching frequency and efficiency.

[0037] The induction heating coil 3 is used to heat the working fluid in the heat storage tank. The induction heating coil 3 can adopt a single-layer or multi-layer spiral coil structure, and the diameter and number of turns of the coil can be adjusted according to the size of the heat storage tank and the characteristics of the working fluid. For example, for a large heat storage tank, a multi-layer spiral coil can be used to increase the heating area and efficiency. In addition, the induction heating coil 3 can also adopt a planar coil or a toroidal coil to adapt to different heat storage tank shapes and layouts.

[0038] The heat storage and power generation module 4 includes a heat storage tank, a steam turbine generator, a condenser and a feed water pump. The working fluid in the heat storage tank can be selected from conventional molten salt or ferroalloy. Conventional molten salt includes a mixture of potassium nitrate, sodium nitrate and sodium nitrite. The ferroalloy includes low carbon steel, stainless steel or other iron-based alloys. The design of the heat storage tank should take into account high temperature resistance and corrosion resistance. Commonly used materials include stainless steel, nickel-based alloys, etc. A stirring device can be set inside the heat storage tank to ensure uniform heating of the working fluid. In addition, the heat storage tank can also be provided with a temperature sensor and a pressure sensor for real-time monitoring of the temperature and pressure of the working fluid.

[0039] The steam turbine generator is used to convert the steam generated by the heat storage tank into electrical energy and output it to the three-phase AC power grid. The design of the steam turbine generator should take into account efficient energy conversion and stability. Common types include back pressure steam turbines and condensing steam turbines. Back pressure steam turbines are suitable for occasions where continuous energy supply is required, while condensing steam turbines are suitable for occasions where efficient energy conversion is required. The output end of the steam turbine generator can be connected to the three-phase AC power grid through a transformer and a circuit breaker to achieve efficient transmission of electrical energy. The condenser is used to condense steam to generate water. Common condenser types include surface condensers and jet condensers. The surface condenser condenses steam into water through a condensing tube bundle, while the jet condenser condenses steam by spraying cold water. The design of the condenser should take into account cooling efficiency and maintenance convenience. Common materials include metals with good thermal conductivity such as copper and aluminum. The feed pump is used to return water to the heat storage tank. The selection of the feed pump should consider the flow and head requirements. Common feed pump types include centrifugal pumps and plunger pumps. Centrifugal pumps are suitable for large flow and low head applications, while plunger pumps are suitable for small 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.

[0040] The three-phase AC power grid can be a large power grid or a system local power grid. The new energy power generation system is connected in parallel with the DC bus 5 or 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 connected to the DC bus 5 or the three-phase AC power grid through DC-DC converters or AC-DC converters respectively. The DC-DC converter or AC-DC converter is used to adjust and stabilize the voltage of the DC bus 5 or the three-phase AC power grid. The selection of solar photovoltaic panels and wind turbines should take into account environmental conditions and installation locations. Solar photovoltaic panels should select high-efficiency, weather-resistant single-crystal silicon or thin-film solar cells, and wind turbines should select vertical axis or horizontal axis wind turbines with a wide wind speed adaptability range and low noise. The design of DC-DC converters or AC-DC converters should take into account efficiency and reliability. Common types include boost converters, buck converters, single-phase full-bridge converters, and three-phase full-bridge converters.

[0041] The heat storage and power generation module 4 can also be connected to the exhaust gas waste heat recovery system. The exhaust gas waste heat recovery system includes a heat exchanger. 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. 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 the cooling water. 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 adjusting the pressure in the heat storage tank. The pressure regulating valve is installed on the top of the heat storage tank. The pressure regulating valve automatically adjusts the opening through the feedback signal of the pressure sensor to keep the pressure in the heat storage tank within the set range.

[0042] The implementation principle of a variable frequency induction electric thermal energy storage system in the embodiment of the present application is: 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 power 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, 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 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, which is suitable for large-scale energy storage and new energy power generation.

[0043] In one embodiment, if Figure 2 As shown, the present application also discloses a variable frequency induction electric thermal energy storage control method, which comprises the following steps: S10: Obtain grid parameters output by the three-phase AC grid, and obtain working parameters of the induction heating coil based on the grid parameters.

[0044] 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, converting the electric energy of the three-phase AC power grid into stable DC power, improving the power factor of the system, reducing harmonic pollution, and ensuring the quality of electric energy. The DC power is converted into medium-frequency AC power, which improves the efficiency of induction heating, so that the working fluid in the heat storage tank can be quickly heated up. The DC power is converted into medium-frequency AC power, which improves the efficiency of induction heating, so that the working fluid in the heat storage tank can be quickly heated up. The induction heating coil directly heats the working fluid in the heat storage tank through medium-frequency AC power. Compared with the traditional resistance heating method, this induction heating method can convert electrical energy into heat energy faster and more evenly.

[0045] S20: starting the induction heating coil according to the working parameters of the induction heating coil, heating the working fluid in the heat storage tank, and acquiring working fluid heating data in real time.

[0046] 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.

[0047] S30: inputting the working fluid heating data into a preset heating analysis model, obtaining a working fluid heating result, and generating an electric energy conversion instruction according to the working fluid heating result.

[0048] Specifically, the heating analysis model can accurately predict the heating effect of the working fluid and determine whether the ideal temperature has been reached. 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.

[0049] 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.

[0050] Specifically, when the working fluid temperature in the heat storage tank reaches the preset value, the working fluid will be heated to a sufficiently high temperature to generate high-pressure steam. This steam drives the steam turbine generator to efficiently convert thermal energy into electrical energy. Ultimately, the electrical energy is output through the three-phase AC power grid for use by users or fed back to the grid, achieving efficient use of energy.

[0051] In one embodiment, if Figure 3 As shown, before obtaining the working parameters of the induction heating coil based on the grid parameters, the variable frequency induction electric heating energy storage control method further includes: S101: Detect the voltage and current output by the three-phase AC power grid, and obtain the power grid output data detection result.

[0052] S102: Determine grid parameters based on the grid output data detection result, and convert the grid parameters into working parameters of the induction heating coil through a multi-pulse rectification module and a frequency conversion circuit.

[0053] Specifically, the voltage and current of the three-phase AC power grid are monitored in real time to ensure that the power grid parameters meet the system operation requirements. Based on the power grid output data detection results, the power grid parameters are accurately determined, and then through the synergy of the multi-pulse rectifier module and the frequency conversion circuit, the power grid parameters are converted into parameters suitable for the operation of the induction heating coil, which improves the stability and reliability of the system and ensures that the working medium in the heat storage tank can be heated efficiently and safely.

[0054] In one embodiment, if Figure 4 As shown, the working fluid heating data is input into a preset heating analysis model to obtain the working fluid heating result, which specifically includes: S31: 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.

[0055] S32: Compare the area of ​​the region with a preset area value, and obtain a working fluid heating result based on the comparison result.

[0056] Specifically, the working fluid heating data acquired 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 reaches the preset situation, thereby ensuring the safety and controllability of the heating process and avoiding overheating or overpressure.

[0057] In one embodiment, if Figure 5 As shown, 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 output to the three-phase AC power grid, and the variable frequency induction electric thermal energy storage control method also includes: 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.

[0058] S60: 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, and monitor the intake and exhaust temperatures of the exhaust gas at the same time.

[0059] 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 to keep the temperature in the heat storage tank within the set range.

[0060] Specifically, the condenser is started to condense the steam into water, and the water is returned to the heat storage tank through the water feed pump, forming a closed-loop water circulation system, reducing the consumption of water resources, transferring the heat in the high-temperature exhaust gas to the working fluid in the heat storage tank, and monitoring 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, transferring the heat in the heat storage tank to the cooling water, and starting the fan 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.

[0061] The above are all preferred embodiments of the present application, and the protection scope of the present application is not limited thereto. Therefore, any equivalent changes made according to the structure, shape, and principle of the present application should be included in the protection scope of the present application.

Claims

1. A variable frequency induction electric thermal energy storage system, characterized in that: 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); 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 a medium-frequency induction heating coil (3); the induction heating coil (3) is used to heat the working medium in a 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, and the steam drives the steam turbine generator to generate electricity; the output end of the steam turbine generator is connected to a 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.

2. A 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. A 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 the three-phase AC power grid. The new energy power generation system includes solar photovoltaic panels and wind generators. The solar photovoltaic panels and wind generators 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.

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, the IGBT inverter circuit comprises a plurality of IGBT switches connected in series and in parallel, the IGBT switches are switched by means of PWM control signals, the PWM control signals are generated by a controller, the controller adjusts the duty cycle of the PWM signal according to system load requirements and energy storage status; the multi-pulse rectifier module (1) is a three-phase input and 24-pulse transformer rectifier output, the multi-pulse rectifier module (1) comprises a plurality of rectifier bridges, each rectifier bridge receives a different phase of a three-phase AC power grid, and the DC power output by the rectifier bridge is filtered and stabilized before being output to a DC bus (5).

6. A variable frequency induction electric thermal energy storage system according to claim 1, characterized in that: The heat storage and power generation module (4) is connected to an exhaust gas waste heat recovery system, the exhaust gas waste heat recovery system comprising a heat exchanger, the heat exchanger being 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 being provided with temperature sensors for monitoring the intake and exhaust temperatures of the exhaust gas; the heat storage and power generation module (4) also comprises a cooling device for cooling the heat storage tank, the cooling device comprising a water-cooled radiator and a fan, the water-cooled radiator being used to transfer heat in the heat storage tank to cooling water, the fan being used for forced ventilation to accelerate the cooling speed of the cooling water; the heat storage and power generation module (4) also comprises a pressure regulating valve for regulating the pressure in the heat storage tank, the pressure regulating valve being installed on the top of the heat storage tank, the pressure regulating valve automatically adjusting the opening according to the feedback signal of the pressure sensor to keep the pressure in the heat storage tank within a set range.

7. A control method based on the variable frequency induction electric thermal energy storage system according to any one of claims 1 to 6, characterized in that: The variable frequency induction electric thermal energy storage control method comprises the following steps: Acquire grid parameters output by a three-phase AC grid, and acquire working 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 fluid in the heat storage tank and obtain the working fluid 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 according to the working fluid heating result; 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 supplied to the three-phase AC power grid.

8. A control method for a variable frequency induction electric thermal energy storage system according to claim 7, characterized in that: Before acquiring the working 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 by the three-phase AC power grid and obtain the power grid output data detection results; The grid parameters are determined based on the grid output data detection result, and the grid parameters are converted into working parameters of the induction heating coil through a multi-pulse rectification module and a frequency conversion circuit.

9. A control method for a variable frequency induction electric thermal energy storage system according to claim 7, characterized in that: The step of inputting the working fluid heating data into a preset heating analysis model to obtain the working fluid heating result specifically includes: 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 exceeding the safety threshold line; The area of ​​the region is compared with a preset area value, and a working fluid heating result is obtained based on the comparison result.

10. A control method for a variable frequency induction electric thermal energy storage system according to claim 7, 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 value to the three-phase AC power 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, and monitor the intake and exhaust temperatures of the exhaust gas at the same time; 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.

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