Energy recovery system of power station

Abstract

The utility model discloses an energy recovery system of a power station, which relates to the technical field of power generation equipment and comprises a first high-voltage switch group, and one end of a first high-voltage switch and one end of a second high-voltage switch of the first high-voltage switch group are connected with a bus output end of a water-turbine generator set; the other end of the first high-voltage switch of the first high-voltage switch group is connected with the input end of the flywheel energy storage device, and the other end of the second high-voltage switch of the first high-voltage switch group is connected with the input end of the electric braking device. In the braking process, short-circuit current of a generator stator is guided to a flywheel energy storage system, a flywheel is driven to rotate, mechanical energy is stored, and energy recovery in the braking process is achieved through storage of the mechanical energy. When power supply is needed, mechanical energy stored in the flywheel is converted into electric energy, and the electric energy is supplied to a station power system through a power transmission system and used for supplying power to internal equipment of a power station. The energy utilization rate can be remarkably increased, the operation cost is reduced, and support is provided for development of green energy.

Description

Technical Field

[0001] This utility model relates to the field of power generation equipment technology, and in particular to an energy recovery system for a power plant. Background Technology

[0002] In pumped storage and hydropower stations, the generating units need to engage electrical braking when shutting down. During the braking process, existing technologies have the following problems:

[0003] 1. Energy loss: During braking, the power station's electrical energy is not effectively recovered, resulting in energy waste and energy loss in the form of heat.

[0004] 2. Additional power supply requirements: To achieve electric braking, additional electrical energy is sometimes required, which increases the system's energy consumption.

[0005] Existing technologies have not effectively recovered and utilized energy losses during braking. Therefore, there is an urgent need for a technical solution that can recover and utilize the unit's energy losses during braking to improve energy efficiency and reduce operating costs. Utility Model Content

[0006] The purpose of this invention is to provide an energy recovery system for power plants that can significantly improve energy utilization, reduce operating costs, and support the development of green energy.

[0007] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0008] One aspect of this utility model provides an energy recovery system for a power plant, the energy recovery system comprising: a hydro-generator set for generating electricity; a switching circuit comprising a first high-voltage switch group, the first high-voltage switch group comprising a first high-voltage switch and a second high-voltage switch, one end of the first high-voltage switch and one end of the second high-voltage switch of the first high-voltage switch group being connected to the bus output terminal of the hydro-generator set, the first high-voltage switch of the first high-voltage switch group being normally closed, and the second high-voltage switch of the first high-voltage switch group being normally open; a flywheel energy storage device and an electric braking device, the other end of the first high-voltage switch of the first high-voltage switch group being connected to the input terminal of the flywheel energy storage device, and the other end of the second high-voltage switch of the first high-voltage switch group being connected to the input terminal of the electric braking device; a control module and a detection circuit, the control module being connected to the switching circuit and the detection circuit respectively, the detection circuit being used to detect the initial power supply converted by the flywheel energy storage device; when the electrical signal of the initial power supply exceeds a set value, the control module controls the first high-voltage switch of the first high-voltage switch group to open and the second high-voltage switch of the first high-voltage switch group to close.

[0009] In some embodiments, the switching circuit further includes a first transistor and a first resistor. The collector of the first transistor is connected to one end of the control loop of the first high-voltage switch group, the base of the first transistor is connected to the control module, the emitter of the first transistor is connected to a second location, the other end of the control loop of the first high-voltage switch group is connected to one end of the first resistor, and the other end of the first resistor is connected to a second power supply.

[0010] In some embodiments, the switching circuit further includes a first diode, the anode of the first diode being connected to the collector of the first transistor and one end of the control circuit terminal of the first high-voltage switch group, and the cathode of the first diode being connected to one end of the first resistor and the other end of the control circuit terminal of the first high-voltage switch group.

[0011] In some embodiments, the detection circuit includes a detection winding, a step-down transformer, a rectifier and filter circuit, a first optocoupler, a second resistor, a third resistor, a fourth resistor, a fifth resistor, and a sixth resistor. The detection winding is used to detect the initial power supply converted by the flywheel energy storage device. The output terminal of the detection winding is connected to the primary coil of the step-down transformer. The input terminal of the rectifier and filter circuit is connected to the secondary coil of the step-down transformer. The output terminal of the rectifier and filter circuit outputs a first power supply and a first ground point. One end of the second resistor is connected to the first power supply. The other end of the second resistor is connected to one end of the third resistor and the light-emitting input terminal of the first optocoupler. The other end of the third resistor is connected to one end of the fourth resistor. The other end of the fourth resistor is connected to the first ground point. The light-emitting output terminal of the first optocoupler is connected to the first ground point through the fifth resistor. The light-receiving input terminal of the first optocoupler is connected to the second power supply. The light-receiving output terminal of the first optocoupler is connected to the control module through the sixth resistor.

[0012] In some embodiments, the detection circuit further includes a second optocoupler, a seventh resistor, and an eighth resistor. The light-emitting input terminal of the second optocoupler is connected to the other end of the third resistor and one end of the fourth resistor. The light-emitting output terminal of the second optocoupler is connected to a first location through the seventh resistor. The light-receiving input terminal of the second optocoupler is connected to a second power supply. The light-receiving output terminal of the second optocoupler is connected to a control module through the eighth resistor.

[0013] In some embodiments, the detection circuit further includes a first capacitor and a second capacitor, one end of the first capacitor is connected to the other end of the second resistor and one end of the third resistor, one end of the second capacitor is connected to the other end of the third resistor and one end of the fourth resistor, and the other ends of the first capacitor and the other ends of the second capacitor are connected to a first location.

[0014] In some embodiments, the detection circuit further includes a second transistor, a second relay, a ninth resistor, a tenth resistor, and an eleventh resistor. The second relay is a double-pole double-throw relay. One end of the ninth resistor is connected to the other end of the third resistor and one end of the fourth resistor. The other end of the ninth resistor is connected to one end of the tenth resistor and the base of the second transistor. The emitter of the second transistor and the other end of the tenth resistor are connected to a first ground point. The collector of the second transistor is connected to one end of the coil of the second relay. The other end of the coil of the second relay is connected to the other end of the second resistor, one end of the third resistor, and one end of the first contactor of the second relay through the eleventh resistor. The other end of the first contactor of the second relay is connected to the light-emitting input terminal of the first optocoupler. One end of the second contactor of the second relay is connected to the other end of the third resistor and one end of the fourth resistor. The other end of the second contactor of the second relay is connected to the light-emitting input terminal of the second optocoupler. The first contactor of the second relay is normally closed, and the second contactor of the second relay is normally open.

[0015] In some embodiments, the detection circuit further includes a second diode, the anode of which is connected to the collector of the second transistor and one end of the coil of the second relay, and the cathode of which is connected to the other end of the coil of the second relay and the eleventh resistor.

[0016] In some embodiments, the rectifier-filter circuit includes a rectifier bridge, a twelfth resistor, a third capacitor, and a fourth capacitor. The input terminal of the rectifier bridge is connected to the secondary coil of the step-down transformer. The positive output terminal of the rectifier bridge outputs a first power supply through the twelfth resistor, and the negative output terminal of the rectifier bridge outputs a first ground point. One end of the third capacitor and one end of the fourth capacitor are connected to the first power supply, and the other ends of the third capacitor and the fourth capacitor are connected to the first ground point. The capacitance value of the third capacitor is greater than the capacitance value of the fourth capacitor.

[0017] An energy recovery system for a power plant according to an embodiment of this utility model has at least the following beneficial effects: During braking, the short-circuit current of the generator stator is guided to the flywheel energy storage system, driving the flywheel to rotate and storing mechanical energy, thereby recovering energy during braking through the storage of mechanical energy. When power is needed, the mechanical energy stored in the flywheel is converted into electrical energy and supplied to the plant's auxiliary power system through the power transmission system for powering the equipment inside the power plant. This application can significantly improve energy utilization efficiency, reduce operating costs, and support the development of green energy.

[0018] It should be understood that the above general description and the following detailed description are merely exemplary and do not limit this disclosure. Attached Figure Description

[0019] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 This is a block diagram of an energy recovery system according to an embodiment;

[0021] Figure 2 This is a schematic diagram of the detection circuit according to an embodiment;

[0022] Figure 3 This is a schematic diagram of a switching circuit according to an embodiment. Detailed Implementation

[0023] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0024] The terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first," "second," or "third" may explicitly or implicitly include one or more of that feature. In the description of this utility model, unless otherwise stated, "a plurality of" means two or more.

[0025] In the description of this utility model, it should be noted that, unless otherwise explicitly specified and limited, the terms "connecting," "installing," "connected," and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model based on the specific circumstances.

[0026] Exemplary embodiments will now be described more fully with reference to the accompanying drawings. However, these exemplary embodiments can be implemented in many forms and should not be construed as limited to the examples set forth herein; rather, they are provided so that the description of this disclosure will be more complete and fully convey the concept of the exemplary embodiments to those skilled in the art. The drawings are merely illustrative of this disclosure and are not necessarily drawn to scale. The same reference numerals in the drawings denote the same or similar parts, and therefore repeated descriptions of them will be omitted.

[0027] The technical solutions of the embodiments of this application are briefly described below:

[0028] According to some embodiments, such as Figure 1 As shown, this application provides an energy recovery system for a power plant, the energy recovery system comprising:

[0029] Hydroelectric generator sets are used for power generation;

[0030] The switching circuit includes a first high-voltage switch group K1, which includes a first high-voltage switch K11 and a second high-voltage switch K12. One end of the first high-voltage switch K11 and one end of the second high-voltage switch K12 are connected to the bus output terminal of the hydro-generator unit. The first high-voltage switch K11 of the first high-voltage switch group K1 is normally closed, and the second high-voltage switch K12 of the first high-voltage switch group K1 is normally open.

[0031] The flywheel energy storage device and the electric braking device are connected to the input terminal of the flywheel energy storage device by the other end of the first high-voltage switch K11 of the first high-voltage switch group K1 and the input terminal of the electric braking device by the other end of the second high-voltage switch K12 of the first high-voltage switch group K1.

[0032] The control module is connected to the switching circuit and the detection circuit respectively. The detection circuit is used to detect the initial power supply converted by the flywheel energy storage device.

[0033] The working principle of the above embodiment is as follows: during braking, the short-circuit current of the generator stator is guided to the flywheel energy storage system, driving the flywheel to rotate and store mechanical energy. Energy recovery during braking is achieved through the storage of mechanical energy. The control module detects the initial power supply converted by the flywheel energy storage device through a detection circuit. The rotational speed of the flywheel energy storage device is proportional to the initial power supply, which is used to determine the energy storage status of the flywheel energy storage device. When the electrical signal of the initial power supply exceeds a set value, it indicates that the flywheel energy storage device is fully charged. The control module then controls the first high-voltage switch K11 of the first high-voltage switch group K1 to open and the second high-voltage switch K12 of the first high-voltage switch group K1 to close, switching to the electric braking device for braking.

[0034] In some embodiments, if the flywheel energy storage device malfunctions, the control module controls the first high-voltage switch K11 of the first high-voltage switch group K1 to open and the second high-voltage switch K12 of the first high-voltage switch group K1 to close, switching to the electric braking device for braking.

[0035] Both the flywheel energy storage device and the electric braking device of this application can be used for generator set shutdown braking. Using the flywheel energy storage device for braking allows for energy recovery during the braking process. When power is needed, the mechanical energy stored in the flywheel is converted into electrical energy and supplied to the plant's auxiliary power system via a power transmission system for powering internal equipment, such as charging the plant's batteries. This application improves energy utilization, reduces operating costs, and supports the development of green energy.

[0036] The following is in conjunction with the appendix to this instruction manual. Figures 1 to 3 The preferred embodiments of this disclosure will be further described in detail below.

[0037] According to some embodiments, such as Figure 3 As shown, the switching circuit also includes a first transistor Q1 and a first resistor R1, and their specific connection method is as follows:

[0038] The collector of the first transistor Q1 is connected to one end of the control circuit of the first high-voltage switch group K1, the base of the first transistor Q1 is connected to the control module, the emitter of the first transistor Q1 is connected to the second ground, the other end of the control circuit of the first high-voltage switch group K1 is connected to one end of the first resistor R1, and the other end of the first resistor R1 is connected to the second power supply.

[0039] The working principle of the above embodiment is as follows: when it is necessary to switch to the electric braking device for braking, the control module outputs a high-level signal to the base of the first transistor Q1, the first transistor Q1 is turned on, the control circuit terminal of the first high-voltage switch group K1 is energized, the first high-voltage switch K11 of the first high-voltage switch group K1 is opened, and the second high-voltage switch K12 of the first high-voltage switch group K1 is closed.

[0040] When it is necessary to switch back to the flywheel energy storage device for braking, the control module outputs a low-level signal to the base of the first transistor Q1. The first transistor Q1 is cut off, the control circuit terminal of the first high-voltage switch group K1 is not energized, the first high-voltage switch K11 of the first high-voltage switch group K1 is closed, and the second high-voltage switch K12 of the first high-voltage switch group K1 is opened.

[0041] According to some embodiments, such as Figure 3As shown, the switching circuit also includes a first diode D1. The positive terminal of the first diode D1 is connected to the collector of the first transistor Q1 and one end of the control circuit terminal of the first high-voltage switch group K1. The negative terminal of the first diode D1 is connected to one end of the first resistor R1 and the other end of the control circuit terminal of the first high-voltage switch group K1.

[0042] The first diode D1 is used to provide freewheeling current to the control circuit terminal of the first high-voltage switch group K1 when it is de-energized, thereby improving the service life of the relay.

[0043] According to some embodiments, such as Figure 2 As shown, the detection circuit includes a detection winding, a step-down transformer, a rectifier and filter circuit, a first optocoupler U1, a second resistor R2, a third resistor R3, a fourth resistor R4, a fifth resistor R5, and a sixth resistor R6. Their specific connection method is as follows:

[0044] The detection winding is used to detect the initial power supply converted by the flywheel energy storage device. The output end of the detection winding is connected to the primary coil of the step-down transformer. The input end of the rectifier and filter circuit is connected to the secondary coil of the step-down transformer. The output end of the rectifier and filter circuit outputs the first power supply and the first ground. One end of the second resistor R2 is connected to the first power supply. The other end of the second resistor R2 is connected to one end of the third resistor R3 and the light-emitting side input end of the first optocoupler U1. The other end of the third resistor R3 is connected to one end of the fourth resistor R4. The other end of the fourth resistor R4 is connected to the first ground. The light-emitting side output end of the first optocoupler U1 is connected to the first ground through the fifth resistor R5. The light-receiving side input end of the first optocoupler U1 is connected to the second power supply. The light-receiving side output end of the first optocoupler U1 is connected to the control module through the sixth resistor R6.

[0045] Furthermore, such as Figure 2 As shown, the detection circuit also includes a second optocoupler U2, a seventh resistor R7, and an eighth resistor R8, with the specific connection method as follows:

[0046] The light-emitting input terminal of the second optocoupler U2 is connected to the other end of the third resistor R3 and one end of the fourth resistor R4. The light-emitting output terminal of the second optocoupler U2 is connected to the first location through the seventh resistor R7. The light-receiving input terminal of the second optocoupler U2 is connected to the second power supply. The light-receiving output terminal of the second optocoupler U2 is connected to the control module through the eighth resistor R8.

[0047] Specifically, when the electrical signal of the first power source exceeds the first preset threshold, it indicates that the electrical signal of the initial power source exceeds the set value and the flywheel energy storage device is fully charged. If braking is required, the control module controls the first high-voltage switch K11 of the first high-voltage switch group K1 to open and the second high-voltage switch K12 of the first high-voltage switch group K1 to close, switching to the electric braking device for braking. When the electrical signal of the first power source is below the second preset threshold, it indicates that the flywheel energy storage device is not fully charged. If braking is required, the control module controls the first high-voltage switch K11 of the first high-voltage switch group K1 to close and the second high-voltage switch K12 of the first high-voltage switch group K1 to open, switching to the flywheel energy storage device for braking.

[0048] The control module detects the first preset threshold through the second optocoupler U2 and the second preset threshold through the first optocoupler U1.

[0049] According to some embodiments, such as Figure 2 As shown, the detection circuit also includes a first capacitor C1 and a second capacitor C2. One end of the first capacitor C1 is connected to the other end of the second resistor R2 and one end of the third resistor R3. One end of the second capacitor C2 is connected to the other end of the third resistor R3 and one end of the fourth resistor R4. The other ends of the first capacitor C1 and the other ends of the second capacitor C2 are connected to the first location.

[0050] Among them, the first capacitor C1 and the second capacitor C2 are used for filtering.

[0051] According to some embodiments, such as Figure 2 As shown, the detection circuit also includes a second transistor Q2, a second relay K2, a ninth resistor R9, a tenth resistor R10, and an eleventh resistor R11, and their specific connection method is as follows.

[0052] The second relay K2 is a double-pole double-throw relay. One end of the ninth resistor R9 is connected to the other end of the third resistor R3 and one end of the fourth resistor R4. The other end of the ninth resistor R9 is connected to one end of the tenth resistor R10 and the base of the second transistor Q2. The emitter of the second transistor Q2 and the other end of the tenth resistor R10 are connected to the first ground point. The collector of the second transistor Q2 is connected to one end of the coil of the second relay K2. The other end of the coil of the second relay K2 is connected to the other end of the second resistor R2, one end of the third resistor R3, and one end of the first contactor K21 configured for the second relay K2 through the eleventh resistor R11. The other end of the first contactor K21 configured for the second relay K2 is connected to the light-emitting input terminal of the first optocoupler U1. One end of the second contactor K22 configured for the second relay K2 is connected to the other end of the third resistor R3 and one end of the fourth resistor R4. The other end of the second contactor K21 configured for the second relay K2 is connected to the light-emitting input terminal of the second optocoupler U2.

[0053] The first contactor K21 configured with the second relay K2 is normally closed, and the second contactor K22 configured with the second relay K2 is normally open.

[0054] The working principle of the above embodiment is as follows: when the first power supply is close to the second preset threshold, the electrical signal is low. The base of the second transistor Q2 receives a low-level signal through the tenth resistor R10. The second transistor Q2 is cut off, the coil terminal of the second relay K2 is not energized, the first contactor K21 configured with the second relay K2 is closed, the second contactor K22 is opened, and the control module detects the electrical signal of the first power supply through the first optocoupler U1.

[0055] When the first power supply approaches the first preset threshold, the electrical signal is high. The base of the second transistor Q2 receives a high-level signal through the ninth resistor R9. The second transistor Q2 is turned on, the coil of the second relay K2 is energized, the first contactor K21 configured with the second relay K2 is opened, and the second contactor K22 is closed. The control module detects the electrical signal of the first power supply through the second optocoupler U2.

[0056] According to some embodiments, such as Figure 2 As shown, the detection circuit also includes a second diode D2. The positive terminal of the second diode D2 is connected to the collector of the second transistor Q2 and one end of the coil terminal of the second relay K2. The negative terminal of the second diode D2 is connected to the other end of the coil terminal of the second relay K2 and the eleventh resistor R11.

[0057] The second diode D2 is used to allow the coil terminal of the second relay K2 to continue flowing through the second diode D2 when the second relay K2 is de-energized, thereby improving the service life of the relay.

[0058] According to some embodiments, such as Figure 2 As shown, the rectifier and filter circuit includes a rectifier bridge DB, a twelfth resistor R12, a third capacitor C3, and a fourth capacitor C4. Its specific connection method is as follows:

[0059] The input terminal of the rectifier bridge DB is connected to the secondary coil of the step-down transformer. The positive output terminal of the rectifier bridge DB outputs the first power supply through the twelfth resistor R12. The negative output terminal of the rectifier bridge DB outputs the first ground. One end of the third capacitor C3 and one end of the fourth capacitor C4 are connected to the first power supply. The other end of the third capacitor C3 and the other end of the fourth capacitor C4 are connected to the first ground.

[0060] The capacitance of the third capacitor C3 is greater than that of the fourth capacitor C4.

[0061] Among them, the rectifier bridge DB is used to convert AC power to DC power, the third capacitor C3 is used to filter low frequency, and the fourth capacitor C4 is used to filter high frequency.

[0062] In the description of the above embodiments, specific features, structures, materials, or characteristics may be combined in any suitable manner in one or more embodiments or examples.

[0063] Although this disclosure has been described with reference to several typical embodiments, it should be understood that the terminology used is descriptive and exemplary, and not restrictive. Because this disclosure can be embodied in many forms without departing from the spirit or substance of this application, it should be understood that the above embodiments are not limited to any of the foregoing details, but should be interpreted broadly within the spirit and scope defined by the appended claims. Therefore, all variations and modifications falling within the scope of the claims or their equivalents should be covered by the appended claims.

Claims

1. An energy recovery system for a power plant, characterized by The energy recovery system includes: A hydro-turbine generator set, wherein the hydro-turbine generator set is used for generating electricity; The switching circuit includes a first high-voltage switch group, which includes a first high-voltage switch and a second high-voltage switch. One end of the first high-voltage switch and one end of the second high-voltage switch of the first high-voltage switch group are connected to the bus output terminal of the hydro-generator unit. The first high-voltage switch of the first high-voltage switch group is normally closed, and the second high-voltage switch of the first high-voltage switch group is normally open. The flywheel energy storage device and the electric braking device are provided, wherein the other end of the first high-voltage switch of the first high-voltage switch group is connected to the input end of the flywheel energy storage device, and the other end of the second high-voltage switch of the first high-voltage switch group is connected to the input end of the electric braking device. The control module is connected to the switching circuit and the detection circuit respectively, and the detection circuit is used to detect the initial power supply converted by the flywheel energy storage device. When the electrical signal of the initial power supply exceeds the set value, the control module controls the first high-voltage switch of the first high-voltage switch group to open and the second high-voltage switch of the first high-voltage switch group to close.

2. The energy recovery system of claim 1, wherein, The switching circuit further includes a first transistor and a first resistor. The collector of the first transistor is connected to one end of the control circuit of the first high-voltage switch group, the base of the first transistor is connected to the control module, the emitter of the first transistor is connected to a second location, the other end of the control circuit of the first high-voltage switch group is connected to one end of the first resistor, and the other end of the first resistor is connected to a second power supply.

3. The energy recovery system of claim 2, wherein, The switching circuit further includes a first diode, the anode of which is connected to the collector of the first transistor and one end of the control circuit of the first high-voltage switch group, and the cathode of which is connected to one end of the first resistor and the other end of the control circuit of the first high-voltage switch group.

4. The energy recovery system of claim 1, wherein, The detection circuit includes a detection winding, a step-down transformer, a rectifier and filter circuit, a first optocoupler, a second resistor, a third resistor, a fourth resistor, a fifth resistor, and a sixth resistor. The detection winding is used to detect the initial power supply converted by the flywheel energy storage device. The output end of the detection winding is connected to the primary coil of the step-down transformer. The input end of the rectifier and filter circuit is connected to the secondary coil of the step-down transformer. The output end of the rectifier and filter circuit outputs a first power supply and a first ground point. One end of the second resistor is connected to the first power supply. The other end of the second resistor is connected to one end of the third resistor and the light-emitting input end of the first optocoupler. The other end of the third resistor is connected to one end of the fourth resistor. The other end of the fourth resistor is connected to the first ground point. The light-emitting output end of the first optocoupler is connected to the first ground point through the fifth resistor. The light-receiving input end of the first optocoupler is connected to the second power supply. The light-receiving output end of the first optocoupler is connected to the control module through the sixth resistor.

5. The energy recovery system of claim 4, wherein, The detection circuit further includes a second optocoupler, a seventh resistor, and an eighth resistor. The light-emitting input terminal of the second optocoupler is connected to the other end of the third resistor and one end of the fourth resistor. The light-emitting output terminal of the second optocoupler is connected to a first location through the seventh resistor. The light-receiving input terminal of the second optocoupler is connected to a second power supply. The light-receiving output terminal of the second optocoupler is connected to a control module through the eighth resistor.

6. The energy recovery system of claim 5, wherein, The detection circuit further includes a first capacitor and a second capacitor. One end of the first capacitor is connected to the other end of the second resistor and one end of the third resistor. One end of the second capacitor is connected to the other end of the third resistor and one end of the fourth resistor. The other ends of the first capacitor and the other ends of the second capacitor are connected to a first location.

7. The energy recovery system of claim 5, wherein, The detection circuit further includes a second transistor, a second relay, a ninth resistor, a tenth resistor, and an eleventh resistor. The second relay is a double-pole double-throw relay. One end of the ninth resistor is connected to the other end of the third resistor and one end of the fourth resistor. The other end of the ninth resistor is connected to one end of the tenth resistor and the base of the second transistor. The emitter of the second transistor and the other end of the tenth resistor are connected to a first ground point. The collector of the second transistor is connected to one end of the coil of the second relay. The other end of the coil of the second relay is connected to the other end of the second resistor, one end of the third resistor, and one end of the first contactor of the second relay through the eleventh resistor. The other end of the first contactor of the second relay is connected to the light-emitting input terminal of the first optocoupler. One end of the second contactor of the second relay is connected to the other end of the third resistor and one end of the fourth resistor. The other end of the second contactor of the second relay is connected to the light-emitting input terminal of the second optocoupler. The first contactor of the second relay is normally closed, and the second contactor of the second relay is normally open.

8. The energy recovery system of claim 7, wherein, The detection circuit further includes a second diode, the positive terminal of which is connected to the collector of the second transistor and one end of the coil of the second relay, and the negative terminal of which is connected to the other end of the coil of the second relay and the eleventh resistor.

9. The energy recovery system of claim 4, wherein, The rectifier and filter circuit includes a rectifier bridge, a twelfth resistor, a third capacitor, and a fourth capacitor. The input terminal of the rectifier bridge is connected to the secondary coil of the step-down transformer. The positive output terminal of the rectifier bridge outputs a first power supply through the twelfth resistor. The negative output terminal of the rectifier bridge outputs a first ground point. One end of the third capacitor and one end of the fourth capacitor are connected to the first power supply. The other ends of the third capacitor and the other ends of the fourth capacitor are connected to the first ground point. The capacitance of the third capacitor is greater than that of the fourth capacitor.

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