Method and system for flexibly starting high-power equipment

Abstract

The embodiment of the invention provides a method and a system for flexibly starting high-power equipment. The method comprises the following steps: controlling a super capacitor to increase the power discharged to the high-power equipment to a preset capacitance maximum discharge power according to a preset first power rise rate; when a preset first switching condition is met, the super capacitor is controlled to gradually reduce the discharge power to the high-power equipment, and meanwhile, the lithium battery is controlled to gradually increase the discharge power to the high-power equipment, so that the total discharge power to the high-power equipment is maintained to be the rated power of the high-power equipment; and when the working condition of the high-power equipment meets the preset power grid access standard, switching in the power grid to supply power to the high-power equipment, and disconnecting the lithium battery and the super capacitor.

Description

Technical Field

[0001] This invention relates to the field of high-power equipment starting technology, and in particular to a method and system for flexible starting of high-power equipment. Background Technology

[0002] The widespread application of high-power motors in industry, transportation, and other fields has made them one of the core devices for modern energy conversion and power output. For example, in industrial production, high-power motors are often used to drive heavy machinery such as cranes and conveyor belts. However, high-power motors place extremely high demands on the power supply during startup, including high power density and high current output capability. For instance, starting a 260kW motor in many coal mines requires a large starting current; when the motor is started directly, the starting current can reach 5 to 7 times the rated current, impacting the power grid, causing voltage drops, affecting the normal operation of other equipment, and potentially causing overheating of power supply system components, thus affecting the motor's lifespan. Traditional single-power supply systems, such as those relying solely on lithium batteries or lead-acid batteries, struggle to overcome these drawbacks, leading to starting difficulties and even irreversible damage to the motor. For example, traditional star-delta / autotransformers experience current surges of 4-6 times their rated current during startup, while mechanical contacts have short lifespans and generate arcs during switching; pure battery energy storage startup leads to accelerated capacity decay during high-rate discharge, failing to meet instantaneous ultra-high power demands (e.g., a 260kW motor requires ≥300kW / 5s to start); and supercapacitors alone cannot support long-term startup processes due to their low energy density (≤10Wh / kg).

[0003] In the process of developing this invention, the applicant discovered at least the following problems in the prior art:

[0004] Traditional high-power motor starting technology requires a large starting current, places high demands on the power density and current output capability of the power supply, and is prone to impacting the power grid, affecting the lifespan of the motor and starting system. Summary of the Invention

[0005] This invention provides a method and system for flexible starting of high-power equipment, which addresses the problems of traditional high-power motor starting technology requiring large starting currents, high power density and current output capabilities of the power supply, and easy impact on the power grid, thus affecting the lifespan of the motor and starting system.

[0006] To achieve the above objectives, in one aspect, embodiments of the present invention provide a method for flexible start-up of a high-power device, comprising:

[0007] The supercapacitor is controlled to increase the power of its discharge to the high-power device to the preset maximum discharge power of the capacitor at a preset first power increase rate; wherein, the maximum discharge power of the capacitor is the highest power of the high-power device in the initial stage of startup.

[0008] When the preset first switching condition is met, the supercapacitor is controlled to gradually reduce the discharge power to the high-power device, while the lithium battery is controlled to gradually increase the discharge power to the high-power device, so as to maintain the total discharge power to the high-power device at the rated power of the high-power device.

[0009] When the operating conditions of the high-power equipment meet the preset grid connection standards, the grid is connected to supply power to the high-power equipment, and the lithium battery and the supercapacitor are disconnected.

[0010] Furthermore, the control of the supercapacitor to increase the power of discharge to the high-power device to the preset maximum discharge power of the capacitor at a preset first power increase rate includes:

[0011] The discharge current of the supercapacitor is kept stable at a preset discharge current, and the discharge voltage of the supercapacitor is controlled to gradually increase so that the supercapacitor continuously discharges to the high-power device at a preset first power increase rate. When the discharge power of the supercapacitor reaches the preset maximum discharge power of the capacitor, the discharge to the high-power device is maintained at the maximum discharge power of the capacitor. The preset discharge current is 1.5 times the rated current of the high-power device.

[0012] Furthermore, satisfying the preset first switching condition includes: the discharge voltage of the supercapacitor is less than the preset capacitor voltage or the continuous discharge time of the supercapacitor is greater than the preset independent discharge time of the capacitor.

[0013] Furthermore, the high-power equipment meets preset grid connection standards, including:

[0014] The high-power equipment operates at more than 90% of its rated operating conditions, and the phase difference between the current power supply voltage of the high-power equipment and the voltage phase of the power grid is less than 1 degree.

[0015] Furthermore, the high-power device is a motor;

[0016] The control of the supercapacitor to increase the power of discharge to high-power devices to the preset maximum discharge power of the capacitor at a preset first power increase rate includes:

[0017] While maintaining the discharge current of the supercapacitor at a stable 580A, the discharge voltage of the supercapacitor is gradually increased so that the supercapacitor continuously discharges to the motor at a power increase rate of 100kW every 0.1 seconds, and when the discharge power of the supercapacitor reaches 300kW, it continues to discharge to the high-power equipment at the maximum discharge power of the capacitor.

[0018] Furthermore, the high-power device is a motor;

[0019] When a preset first switching condition is met, the supercapacitor is controlled to gradually decrease its discharge power to the high-power device, while the lithium battery is controlled to gradually increase its discharge power to the high-power device, so as to maintain the total discharge power to the high-power device at the rated power of the high-power device, including:

[0020] When the discharge voltage of the supercapacitor is less than 1050V or the continuous discharge time of the supercapacitor is greater than 3 seconds, the supercapacitor is controlled to discharge to the high-power device at a power decrease rate of 150kW per second, while the lithium battery is controlled to continuously discharge to the motor at a power increase rate of 75kW per second until the total discharge power to the high-power device is 260kW. Then, the supercapacitor is adjusted to discharge to the high-power device at a power decrease rate of 75kW per second to maintain the total discharge power to the high-power device at 260kW.

[0021] Furthermore, the high-power device is a motor;

[0022] When the operating conditions of the high-power equipment meet the preset grid connection standards, the process of connecting to the grid to supply power to the high-power equipment and disconnecting the lithium battery and the supercapacitor includes:

[0023] When the motor speed is greater than 90% of the rated speed, and the phase difference between the current supply voltage of the motor and the grid is less than 1 degree, the power grid is switched to supply power to the high-power device at the current zero-crossing point, and the lithium battery and the supercapacitor are disconnected.

[0024] Furthermore, the method of controlling the supercapacitor to increase the power of discharging to the high-power device at a preset first power increase rate to the preset maximum discharge power of the capacitor also includes:

[0025] Check whether the state of charge of the supercapacitor is greater than 80% and whether the state of charge of the lithium battery is greater than 30%.

[0026] If the inspection result shows that the state of charge of the supercapacitor is greater than 80% and the state of charge of the lithium battery is greater than 30%, then the supercapacitor is controlled to increase the power of discharge to the high-power device to the preset maximum discharge power of the capacitor at a preset first power increase rate.

[0027] Further, the high-power device is a motor; the starting peak power of the motor is 300kW, and the rated power is 260kW; the method includes: before starting the motor, when it is found that the state of charge of the supercapacitor is greater than 80% and the state of charge of the lithium battery is greater than 30%, starting the motor, setting the energy storage converter to DC-AC inverter mode, so that the DC power stored by the supercapacitor or lithium battery is converted into AC power to power the motor;

[0028] The energy storage converter is controlled to stabilize the discharge current of the supercapacitor at 580A, and the supercapacitor is controlled to increase the discharge power to 300kW to power the motor at a power increase rate of 100kW / 0.1 seconds.

[0029] When the supercapacitor voltage drops below 1050V or the startup time exceeds 3 seconds, the lithium battery begins to discharge. The lithium battery starts discharging to the motor at a power increase rate of 75kW / s, gradually engaging the supercapacitor. Simultaneously, the supercapacitor discharges to the motor at a power decrease rate of 150kW / s until the total discharge power to the motor stabilizes at 260kW±5%. Then, the power decrease rate of the supercapacitor is adjusted to 75kW / s, and the supercapacitor gradually withdraws to maintain the total discharge power to the motor stable at 260kW±5%.

[0030] When the motor speed exceeds 90% of the rated speed and the phase difference between the supply voltage and the grid voltage is within 1 degree, the power supply of the motor is switched to the grid power supply at the current zero crossing point, and the switching time is recorded when the switching time exceeds 8 milliseconds.

[0031] On the other hand, embodiments of the present invention provide a system for flexible startup of high-power equipment, employing the method for flexible startup of high-power equipment as described above, including: a supercapacitor, a lithium battery, an energy storage converter, a controller, high-power equipment, and a power grid;

[0032] The super battery, lithium battery, controller, high-power equipment, and power grid are respectively connected to the energy storage converter;

[0033] The energy storage converter is used to charge the super battery and the lithium battery using the power grid when the high-power equipment is idle.

[0034] The energy storage converter is also used to control the supercapacitor to increase the power of the discharge to the high-power device to the preset maximum discharge power of the capacitor during the startup of the high-power device; and to maintain the total discharge power to the high-power device at the rated power of the high-power device by discharging the supercapacitor and the lithium battery simultaneously when the preset first switching condition is met; and to connect to the grid to supply power to the high-power device when the operating conditions of the high-power device meet the preset grid connection standard, and disconnect the lithium battery and the supercapacitor.

[0035] Furthermore, the energy storage converter is also used to control the switching frequency of the internal electronic switch after the controller detects the load current at the grid connection point in real time and calculates that the reactive current component that needs to be compensated is greater than the preset reactive current compensation threshold, and uses the energy storage of the supercapacitor or lithium battery to generate a compensation current that is the same in magnitude and opposite in direction as the reactive current component and injects it into the grid.

[0036] The above technical solution has the following beneficial effects: The startup process of high-power equipment is divided into three stages, with different power supply methods used in each stage. In the first stage, a supercapacitor independently powers the high-power equipment, and the discharge power of the supercapacitor is gradually increased to protect it and extend its lifespan. This also ensures a smooth startup of the high-power equipment, avoiding sudden starts from a standstill and guaranteeing startup safety. In the second stage, the lithium battery and supercapacitor jointly output discharge power. The supercapacitor gradually withdraws, and the lithium battery gradually takes over. This maintains a stable discharge power output to the high-power equipment while avoiding impact on the lithium battery, protecting it and extending its lifespan. In the third stage, when the high-power equipment's connection to the grid will not cause unacceptable fluctuations, the output of the lithium battery and supercapacitor is stopped, and the high-power equipment is switched to the grid, using the grid to independently power it, completing the startup process and minimizing the impact on the grid. Attached Figure Description

[0037] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0038] Figure 1 This is a flowchart of a method for flexible startup of a high-power device according to one embodiment of the present invention;

[0039] Figure 2 This is a schematic diagram of the architecture of a system for flexible startup of a high-power device, one of the embodiments of the present invention;

[0040] Figure 3 This is another flowchart of a method for flexible start-up of a high-power device, one of the embodiments of the present invention;

[0041] Figure 4 This is another schematic diagram of the architecture of a system for flexible starting of high-power equipment, which is one embodiment of the present invention;

[0042] Figure 5 This is another schematic diagram of the architecture of a system for flexible starting of high-power equipment, which is one of the embodiments of the present invention. Detailed Implementation

[0043] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0044] On the one hand, such as Figure 1 As shown, an embodiment of the present invention provides a method for flexible start-up of a high-power device, comprising:

[0045] Step S10: Control the supercapacitor to increase the power of the discharge to the high-power device to the preset maximum discharge power of the capacitor at a preset first power increase rate; wherein, the maximum discharge power of the capacitor is the highest power of the high-power device in the initial stage of startup.

[0046] Step S11: When the preset first switching condition is met, control the supercapacitor to gradually reduce the discharge power to the high-power device, and at the same time control the lithium battery to gradually increase the discharge power to the high-power device, so as to maintain the total discharge power to the high-power device as the rated power of the high-power device.

[0047] Step S12: When the operating conditions of the high-power device meet the preset grid connection standards, connect to the grid to supply power to the high-power device, and disconnect the lithium battery and the supercapacitor. When the operating conditions of the high-power device (e.g., its voltage, frequency, and phase are synchronized with the grid) meet the preset grid connection standards, control the grid switch to close, and connect to the grid to supply power to the high-power device. Subsequently, after confirming that the grid power supply is stable, disconnect the lithium battery and the supercapacitor from the load.

[0048] The preset grid connection standard includes: the amplitude, frequency and phase of the voltage of the high-power equipment are synchronized with the grid voltage.

[0049] In one or more embodiments of the present invention, "high-power equipment" specifically refers to motor loads with a rated power ranging from 100 kilowatts (kW) to 1000 kilowatts (kW), such as, but not limited to, mining tunneling machines, large fans, water pumps, compressors, etc. The control method and system of the embodiments of the present invention are particularly suitable for smooth, shock-free, and flexible startup of such equipment. High instantaneous peak power is required in the initial stage of startup of high-power equipment, and this instantaneous peak power will significantly exceed the rated power of the high-power equipment. Supercapacitors have the characteristics of high power density, rapid charging and discharging, and long cycle life. A supercapacitor is a capacitor or a combination of multiple capacitors connected in series, whose rated voltage and rated power are both greater than the rated voltage and rated power of the high-power equipment. By adjusting the number and capacitance of the series capacitors, the supercapacitor's rated voltage and rated power can be made greater than the rated voltage and rated power of the high-power equipment. The startup time of the high-power equipment is used as the time required for the supercapacitor to reach its preset maximum discharge power from startup. Therefore, the startup time of the high-power equipment can be used as the discharge time of the supercapacitor. Dividing the preset maximum discharge power of the supercapacitor by its discharge time allows the calculation of the preset first power rise rate. By determining the first power rise rate based on the startup time of the high-power equipment, the power output curve of the supercapacitor can be made to perfectly match the power demand curve of the high-power equipment during startup. The rated power of the high-power equipment is a known parameter; the highest power during the initial startup phase of the high-power equipment is also a known or measurable parameter. In this embodiment of the invention, in the first stage (step S10), a supercapacitor provides instantaneous peak power output to the high-power device during the initial startup phase, thereby preventing the high-power device from directly drawing power from the lithium battery or the power grid during startup, which could impact the lithium battery and the power grid. When controlling the supercapacitor to discharge to the high-power device, the discharge power of the supercapacitor is gradually increased to the preset maximum discharge power at a preset first power increase rate, which protects the supercapacitor and extends its service life. Specific methods for gradually increasing the discharge power of the supercapacitor may include, but are not limited to, connecting the supercapacitor to an energy storage converter, connecting the energy storage converter to the high-power device, and adjusting the discharge power of the supercapacitor through the energy storage converter. Alternatively, a high-power switch can be set between the supercapacitor and the high-power device, and the discharge power of the supercapacitor to the high-power device can be controlled by modulating the duty cycle of the high-power switch. When adjusting the discharge power of the supercapacitor, the discharge power can be adjusted (gradually increased) by adjusting the discharge voltage and / or discharge current of the supercapacitor.In the second stage (step S11), after the supercapacitor discharges to a certain level, the lithium battery is connected, allowing it to also provide discharge power to the high-power device. At this time, the supercapacitor continues to discharge to the high-power device. After the lithium battery is connected, its discharge power is gradually increased, while the supercapacitor's discharge power gradually decreases. This maintains the discharge power input to the high-power device at a preset total power level, gradually increasing the lithium battery's discharge power and preventing it from being subjected to instantaneous shocks upon connection, thus protecting the lithium battery and extending its lifespan. When the high-power device reaches the preset grid connection standard, the third stage (step S12) begins. Since the supercapacitor's discharge power decreases at a preset first power reduction rate in the second stage, it may have already stopped discharging before entering the third stage, or it may still be discharging. When the high-power device reaches the preset grid connection standard, the lithium battery's discharge and (if the supercapacitor is still discharging) the supercapacitor's discharge will stop, and the high-power device will be connected to the grid. When high-power devices are powered by a power storage converter (PCS), the operating conditions of the high-power devices meet the preset grid connection standards when the amplitude, frequency, and phase of the voltage output from the PCS to the high-power devices are synchronized with the grid voltage. At this point, a seamless switching principle of first closing (connecting) the grid switch and then opening (disconnecting) the energy storage system switch is followed. The grid is connected first to supply power to the high-power devices, and then the lithium battery and supercapacitor are disconnected to ensure system safety. For motors, their speed corresponds to frequency, and their rotor position corresponds to phase. Connecting to the grid only when the operating conditions of the high-power devices meet the preset grid connection standards avoids unacceptable impacts on the grid and ensures the normal operation of the high-power devices. Impact standard at the moment of switching: At the moment the control grid switch is closed, the predicted or measured impact current and voltage fluctuations must be less than the allowable values ​​specified by the grid; Steady-state standard after switching: After the switch is completed, high-power equipment is directly powered by the grid, and its power demand (especially reactive power) and possible harmonics should not affect the stable operation of the grid. Relevant parameters (such as power factor and THD) must meet the grid requirements. The specific values ​​of the preset fluctuation standard need to be determined according to the local grid's stable operation requirements and national power quality standards.

[0050] The embodiments of this invention have the following technical effects: The startup process of high-power equipment is divided into three stages, with different power supply methods used in each stage. In the first stage, a supercapacitor independently powers the high-power equipment, and the discharge power of the supercapacitor is gradually increased to protect it and extend its lifespan. This also ensures a smooth startup of the high-power equipment, avoiding sudden starts from a standstill and guaranteeing startup safety. In the second stage, the lithium battery and supercapacitor jointly output discharge power. The supercapacitor gradually withdraws, and the lithium battery gradually takes over. This maintains a stable discharge power output to the high-power equipment while avoiding impact on the lithium battery, protecting it and extending its lifespan. In the third stage, when the high-power equipment's operation will not cause unacceptable fluctuations in the power grid, the high-power equipment is switched to the grid, the output of the lithium battery and supercapacitor is stopped, and the power grid independently powers the high-power equipment, completing the startup process and minimizing the impact on the power grid.

[0051] Furthermore, the control of the supercapacitor to increase the power of discharge to the high-power device to the preset maximum discharge power of the capacitor at a preset first power increase rate includes:

[0052] The discharge current of the supercapacitor is kept stable at a preset discharge current, and the discharge voltage of the supercapacitor is controlled to gradually increase so that the supercapacitor continuously discharges to the high-power device at a preset first power increase rate. When the discharge power of the supercapacitor reaches the preset maximum discharge power of the capacitor, the discharge to the high-power device is maintained at the maximum discharge power of the capacitor. The preset discharge current is 1.5 times the rated current of the high-power device.

[0053] In some embodiments, the discharge current of the supercapacitor is kept stable, and the discharge power of the supercapacitor is increased at a first power increase rate by adjusting the discharge voltage of the supercapacitor. The discharge current of the supercapacitor can be controlled at a relatively low level, for example, the preset discharge current is 1.5 times the rated current of the high-power device. In conventional techniques, high-power devices (such as high-power motors) are usually connected in parallel with supercapacitors and lithium batteries, or only lithium batteries are directly connected to high-power devices. The discharge stage and the rate of increase of discharge power of the supercapacitor and lithium battery are not controlled. In conventional techniques, the starting current of high-power devices can reach 6 times the rated current of the high-power devices. The embodiments of the present invention improve the discharge power by achieving a stable discharge current and increasing the discharge voltage based on the discharge of the supercapacitor, which significantly reduces the discharge current required during the start-up stage compared to conventional techniques. Furthermore, when the high-power device is a high-power motor, voltage directly affects magnetic flux, and current directly affects rotor current. Both affect starting torque through different paths, but their effects differ. Magnetic flux is the medium for energy conversion in the motor; increasing voltage directly strengthens the magnetic flux, and torque growth is approximately proportional to the square of the voltage. A small voltage increase can lead to a significant torque increase, making voltage increase highly efficient for increasing torque. However, increasing current requires overcoming the impedance (resistance + inductive reactance) of the motor windings, and some electrical energy is converted into heat loss. Torque growth is only linearly related to current, requiring a significant increase in current to improve torque. Therefore, this embodiment of the invention, while maintaining the discharge current of the supercapacitor stable at a preset discharge current, increases the discharge voltage to improve discharge power, providing higher starting efficiency for high-power motor applications.

[0054] Furthermore, satisfying the preset first switching condition includes: the discharge voltage of the supercapacitor is less than a preset capacitor voltage, or the continuous discharge time of the supercapacitor is greater than a preset independent capacitor discharge time. The preset independent capacitor discharge time is a value on the order of seconds.

[0055] In some embodiments of the present invention, the independent discharge time of the supercapacitor in the first stage is on the order of seconds, such as 1, 2, or 3 seconds. In conventional technologies, the supercapacitor and lithium battery are directly connected in parallel to power a high-power device. After startup, the supercapacitor reacts rapidly, supplying power to the high-power device within a microsecond, while the lithium battery reacts more slowly. During discharge, lithium ions need to migrate and diffuse between the positive and negative electrodes, resulting in a relatively slow response speed. However, it also begins to output significant power within tens to hundreds of milliseconds after the high-power device starts. That is, although conventional technologies also have a stage where the supercapacitor discharges first and the lithium battery discharges later, they do not actively control the discharge stages and discharge curves of the supercapacitor and lithium battery. In conventional technologies, the independent discharge time of the supercapacitor is only tens to hundreds of milliseconds. After this, the connection of the lithium battery still causes a significant impact on the lithium battery. In contrast, in the embodiments of the present invention, the independent discharge time of the supercapacitor in the first stage is on the order of seconds. Combined with the control of the discharge current and voltage of the supercapacitor, as well as the control of the lithium battery power, it can be ensured that the lithium battery is not significantly impacted when connected. This invention also protects the supercapacitor by limiting the minimum discharge voltage of the supercapacitor to prevent the discharge voltage from falling below a preset capacitor voltage.

[0056] Furthermore, the operating conditions of the high-power equipment meet the preset grid connection standards, including:

[0057] The high-power equipment operates at more than 90% of its rated operating conditions, and the phase difference between the current power supply voltage of the high-power equipment and the voltage phase of the power grid is less than 1 degree.

[0058] In some embodiments, when the operating condition of a high-power device is greater than 90% of its rated operating condition, and the phase difference between the current supply voltage of the high-power device and the voltage phase of the power grid is less than 1 degree, connecting the high-power device to the power grid can ensure that the impact on the power grid is negligible and maintain the stable operation of the power grid.

[0059] Furthermore, the high-power device is a motor;

[0060] The control of the supercapacitor to increase the power of discharge to high-power devices to the preset maximum discharge power of the capacitor at a preset first power increase rate includes:

[0061] While maintaining the discharge current of the supercapacitor at a stable 580A, the discharge voltage of the supercapacitor is gradually increased so that the supercapacitor continuously discharges to the motor at a power increase rate of 100kW every 0.1 seconds, and when the discharge power of the supercapacitor reaches 300kW, it continues to discharge to the high-power equipment at the maximum discharge power of the capacitor.

[0062] Further, when the preset first switching condition is met, controlling the supercapacitor to gradually decrease its discharge power to the high-power device, while simultaneously controlling the lithium battery to gradually increase its discharge power to the high-power device, so as to maintain the total discharge power to the high-power device at the rated power of the high-power device, includes:

[0063] When the preset first switching condition is met, the discharge power of the supercapacitor is adjusted to the rated power of the high-power device, the lithium battery is controlled to increase the discharge power to the high-power device at a preset second power increase rate, and at the same time the supercapacitor is controlled to decrease the discharge power to the high-power device at a preset first power decrease rate, so as to maintain the total discharge power to the high-power device at the rated power of the high-power device.

[0064] In some embodiments, the second power increase rate and the first power decrease rate are determined by calculation based on the principle of power conservation. During the collaborative power supply phase, the second power increase rate of the lithium battery and the first power decrease rate of the supercapacitor must be matched to ensure that the total output power of both remains constant (e.g., 260kW in the document). The determination method includes: setting an overall target, first determining the constant total power required for this phase, i.e., the preset total power, which is determined based on the power required for the normal operation of high-power equipment; planning the endpoint state, designing the power value that the lithium battery is expected to reach at the end of this phase (this power value is a known parameter of the lithium battery, which can avoid damage to the lithium battery due to over-discharge) and the remaining power value of the supercapacitor (this power value is a known parameter of the supercapacitor, which can avoid over-discharge of the supercapacitor); calculating the change, the change in discharge power of both the lithium battery and the supercapacitor during this phase, i.e., the increase in discharge power of the lithium battery and the decrease in discharge power of the supercapacitor need to be equivalent; dividing by the time calculation rate, dividing this equal change in discharge power by the preset duration of the collaborative power supply phase of the lithium battery and the supercapacitor, to obtain the second power increase rate and the first power decrease rate, respectively. The preset duration of the lithium battery and supercapacitor co-powering phase can be pre-specified based on the actual project requirements. The purpose of determining the second power increase rate and the first power decrease rate is to achieve a smooth, shock-free switch from supercapacitor power to lithium battery power. For example, when the rated power of a high-power device (e.g., a high-power motor) is 260kW, and the maximum power required during startup is 300kW, the discharge power of the supercapacitor is adjusted to 260kW. The lithium battery continues to discharge to the motor at a power increase rate of 75 kW / s, and the supercapacitor discharges to the high-power device at a power decrease rate of 75 kW / s, maintaining a total discharge power of 260kW to the high-power device.

[0065] Furthermore, the high-power device is a motor;

[0066] When a preset first switching condition is met, the supercapacitor is controlled to gradually decrease its discharge power to the high-power device, while the lithium battery is controlled to gradually increase its discharge power to the high-power device, so as to maintain the total discharge power to the high-power device at the rated power of the high-power device, including:

[0067] When the discharge voltage of the supercapacitor is less than 1050V or the continuous discharge time of the supercapacitor is greater than 3 seconds, the supercapacitor is controlled to discharge to the high-power device at a power decrease rate of 150kW per second, while the lithium battery is controlled to continuously discharge to the motor at a power increase rate of 75kW per second, until the total discharge power to the high-power device reaches 260kW. At this point, the supercapacitor is adjusted to discharge to the high-power device at a power decrease rate of 75kW per second to maintain the total discharge power to the high-power device at 260kW. The maximum power during the startup of the high-power device is 300kW.

[0068] Furthermore, the high-power device is a motor;

[0069] When the operating conditions of the high-power equipment meet the preset grid connection standards, the process of connecting to the grid to supply power to the high-power equipment and disconnecting the lithium battery and the supercapacitor includes:

[0070] When the motor speed is greater than 90% of the rated speed, and the phase difference between the current supply voltage of the motor and the grid is less than 1 degree, the power grid is switched to supply power to the high-power device at the current zero-crossing point, and the lithium battery and the supercapacitor are disconnected.

[0071] Furthermore, the method of controlling the supercapacitor to increase the power of discharging to the high-power device at a preset first power increase rate to the preset maximum discharge power of the capacitor also includes:

[0072] Check whether the state of charge of the supercapacitor is greater than 80% and whether the state of charge of the lithium battery is greater than 30%.

[0073] If the inspection result shows that the state of charge of the supercapacitor is greater than 80% and the state of charge of the lithium battery is greater than 30%, then the supercapacitor is controlled to increase the power of discharge to the high-power device to the preset maximum discharge power of the capacitor at a preset first power increase rate.

[0074] Further, the high-power device is a motor; the starting peak power of the motor is 300kW, and the rated power is 260kW; the method includes: before starting the motor, checking whether the state of charge of the supercapacitor is greater than 80% and whether the state of charge of the lithium battery is greater than 30%; when the state of charge of the supercapacitor is greater than 80% and the state of charge of the lithium battery is greater than 30%, starting the motor, setting the energy storage converter to DC-AC inverter mode, so that the DC power stored by the supercapacitor or lithium battery is converted into AC power to power the motor;

[0075] The energy storage converter is controlled to stabilize the discharge current of the supercapacitor at 580A, and the supercapacitor is controlled to increase the discharge power to 300kW to power the motor at a power increase rate of 100kW / 0.1 seconds.

[0076] When the supercapacitor voltage drops below 1050V or the startup time exceeds 3 seconds, the lithium battery begins to discharge. The lithium battery starts discharging to the motor at a power increase rate of 75kW / s, gradually engaging the supercapacitor. Simultaneously, the supercapacitor discharges to the motor at a power decrease rate of 150kW / s until the total discharge power to the motor stabilizes at 260kW±5%. Then, the power decrease rate of the supercapacitor is adjusted to 75kW / s, and the supercapacitor gradually withdraws to maintain the total discharge power to the motor stable at 260kW±5%.

[0077] When the motor speed exceeds 90% of the rated speed and the phase difference between the supply voltage and the grid voltage is within 1 degree, the power supply of the motor is switched to the grid power supply at the current zero crossing point, and the switching time is recorded when the switching time exceeds 8 milliseconds.

[0078] On the other hand, such as Figure 4 As shown, this embodiment of the invention provides a system for flexible starting of high-power equipment, which adopts the method for flexible starting of high-power equipment as described above, including: a supercapacitor 41, a lithium battery 42, an energy storage converter 43, a controller 44, a high-power equipment 45, and a power grid 46;

[0079] The super battery, lithium battery, controller, high-power equipment, and power grid are respectively connected to the energy storage converter;

[0080] The energy storage converter is used to receive instructions from the controller when the high-power equipment is idle, so as to use the power grid to charge the super battery and the lithium battery.

[0081] The energy storage converter is also used to control the supercapacitor to increase the power discharged to the high-power device to a preset maximum discharge power during the startup of the high-power device; and to maintain the total discharge power to the high-power device at the rated power of the high-power device by simultaneously discharging the supercapacitor and the lithium battery when a preset first switching condition is met; and to connect to the grid to supply power to the high-power device when the operating conditions of the high-power device meet a preset grid connection standard, while disconnecting the lithium battery and the supercapacitor; specifically, during the startup of the high-power device, it receives instructions from the controller to control the supercapacitor to increase the power discharged to the high-power device to a preset maximum discharge power at a preset first power increase rate; and to control the supercapacitor to gradually decrease the discharge power while simultaneously controlling the lithium battery to gradually increase the discharge power to maintain the total discharge power to the high-power device at the rated power of the high-power device when the operating conditions of the high-power device meet the preset grid connection standard, while connecting to the grid to supply power to the high-power device, while disconnecting the lithium battery and the supercapacitor.

[0082] Furthermore, the energy storage converter is also used to control the switching frequency of the internal electronic switch after the controller detects the load current at the grid connection point in real time and calculates that the reactive current component that needs to be compensated is greater than the preset reactive current compensation threshold, and uses the energy storage of the supercapacitor or lithium battery to generate a compensation current that is the same in magnitude and opposite in direction as the reactive current component and injects it into the grid.

[0083] In some embodiments, such as Figure 5 As shown, taking a common 260kW tunneling machine in mining as an example, the mains power grid is 660V±10%, 50Hz AC, connected to the PCS (energy storage converter); the supercapacitor (array) consists of 25 48V / 500F capacitors connected in series, with a peak power of 350kW, liquid cooling interface, also connected to the PCS; the lithium battery pack is a 512V / 100Ah lithium iron phosphate DC output, with a continuous power of 150kW, and a voltage range of 450~600V (where 450V is the lowest cutoff voltage of the lithium battery pack at the end of discharge or near-discharge state). The system includes a stop voltage (600V is the highest voltage of the lithium battery pack when fully charged or near fully charged), a BMS system to monitor the lithium battery's operating condition, and a lithium battery cycle life of 8000 cycles based on this system; a PCS (energy storage converter), specifically a four-quadrant PCS, with a DC rated power of 300kW, a voltage of 900~1350V, an efficiency greater than 96%, and optional SVG function; and a three-phase asynchronous motor with a rated power of 260kW, a rated voltage of 1200V, and a rated speed of 1480 rpm. The motor is connected to a motor controller, which is connected to the PCS.

[0084] 1200V DC bus node voltage operating range: 900V (minimum discharge voltage) - 1350V (full charge voltage); Ripple control: ≤±2% (achieved through PCS feedforward compensation); Modular design of supercapacitor array: 25 in series (N=24 working modules + 1 redundant module); Thermal management: parallel layout of liquid cooling pipes, temperature difference ≤5℃ (degrees Celsius); Four-quadrant PCS core functions: Mode 1: DC / AC inverter (start-up stage, THD<3%); Mode 2: AC / DC rectification (energy storage charging, efficiency > 96%); Mode 3: SVG mode (reactive power compensation capacity ±150kVar); Lithium battery pack voltage matching: The designed discharge cutoff voltage is 1050V. This voltage value needs to be designed in conjunction with the minimum effective operating voltage threshold of the supercapacitor array to ensure that both can exit smoothly and synchronously at the end of the mixed discharge.

[0085] Intelligent Management: SOH (State of Health) Estimation Model: in, It is the battery capacity degradation rate (expressed as a decimal, for example, 0.1 represents a 10% degradation). It is the equivalent number of full charge-discharge cycles that the battery has completed, and T is the average operating temperature of the battery (unit: °C); Dynamic DOD (depth of discharge) control: adjusts the SOC (state of charge) working window (e.g., 40%-90%) according to the start-up frequency to optimize battery life.

[0086] The correspondence between the three stages of motor startup and the operating modes of the PCS (Power Conversion System) is as follows:

[0087] Phase 1: High Current Impact Phase (Initial Moment of Startup)

[0088] Motor Status and Requirements: The motor accelerates from a standstill, requiring a huge instantaneous torque, resulting in extremely high current demand and impacting the power supply. Main Power Supply: Supercapacitors (array). Utilizing their ultra-high power density and rapid discharge characteristics, they provide a large instantaneous current. PCS Operating Mode: DC / AC Inverter Mode. PCS Behavior: The PCS inverts the DC power (mainly provided by the supercapacitors) from the 1200V DC bus into AC power to drive the motor. Key Indicators: Power quality is particularly emphasized here, requiring the total harmonic distortion (THD) of the output AC power to be <3% to ensure smooth motor startup while avoiding harmonic pollution. Objective: To successfully cope with the starting impact and achieve "low-impact start-up".

[0089] Phase Two: Continuous Power Support Phase (Late Stage of Startup)

[0090] Motor Status and Requirements: The motor has completed its initial acceleration, and the speed is gradually and steadily increasing, but it still requires continuous and significant power to maintain acceleration until it reaches its rated speed. Main Power Supply: Lithium-ion battery pack. The supercapacitor's charge may have rapidly decreased; the high-energy-density lithium-ion battery takes over, providing continuous and stable energy output. PCS Operating Mode: DC / AC Inverter Mode (Continuous). PCS Behavior: The PCS operating mode remains unchanged, still inverting. However, the main energy source on the DC bus smoothly switches from the supercapacitor to the lithium-ion battery. The system uses control strategies to ensure this switching process is seamless and shock-free. Purpose: To provide stable power support for the motor's continuous acceleration.

[0091] Phase 3: Steady-state operation and grid switching phase (after startup)

[0092] Motor Status and Demands: The motor has reached its rated operating speed and entered a steady-state operation phase, at which point the power demand is relatively stable. Main Power Supply: Grid (Main Power). The grid directly supplies power to the motor, which is the most economical and efficient method. PCS Operating Mode: This phase includes two sub-states: The first sub-state is the instantaneous switching: The PCS, acting as a controller, achieves a seamless switch from "energy storage power supply" to "grid power supply." This involves precise synchronization control (ensuring the voltage, frequency, and phase of the PCS output are completely consistent with the grid), followed by closing the grid-side switch. The second sub-state is after the switch is complete: For the motor circuit: The PCS stops inverterizing and disconnects from power supply. The motor is directly driven by the grid. For the energy storage circuit: The PCS switches to AC / DC rectification mode. PCS Behavior: The PCS draws power from the grid, rectifies the AC power into DC power, and charges the supercapacitor and lithium battery after energy release, restoring the energy storage system's capacity for the next startup.

[0093] Optional Mode: The PCS can also operate in SVG mode. PCS Behavior: Even when power supply to the motor is stopped, the PCS can still be connected to the grid as a static var generator, providing reactive power compensation (capacity + 150kVar), improving the power factor of the grid, and achieving "grid-friendly access".

[0094] When the power grid requires reactive power support (such as when the grid voltage is unstable or the load has reactive power demand), the energy storage converter operates in reactive power compensation mode (SVG mode). In this mode, it does not exchange or has only a small amount of active power, primarily providing or absorbing reactive power. The controller monitors the load current / grid current at the grid connection point (PCC point) in real time and calculates the reactive current component that needs compensation. The energy storage converter also controls the switching frequency of its internal electronic switches after the controller detects the load current at the grid connection point and calculates that the current reactive current component requiring compensation exceeds a preset reactive current compensation threshold. This allows it to utilize the energy stored in the supercapacitor or lithium battery to generate a compensation current of the same magnitude but opposite direction to the reactive current component, which is then injected into the power grid.

[0095] The technical solutions of the present invention will be described in detail below with reference to specific application examples. For technical details not described in the implementation process, please refer to the relevant descriptions above.

[0096] Supercapacitors, with their high power density and rapid charge / discharge characteristics, can effectively mitigate the high current surge during startup; while lithium batteries, with their high energy density and stable output voltage, provide continuous energy support for motor operation. The introduction of this hybrid power system not only helps solve the problems associated with traditional single-power-source startup but also offers new possibilities for improving the overall performance of the motor, which is of great significance for energy optimization and technological advancement.

[0097] The technical problems to be solved by the embodiments of the present invention include achieving millisecond-level shockless switching from supercapacitors to lithium batteries to mains power, dynamically optimizing the switching timing through multi-parameter collaborative decision-making, and achieving low-impact startup and grid-friendly access.

[0098] Example 1: The following description uses the startup of a 260kW tunneling machine as an example.

[0099] 1. Equipment selection:

[0100] Supercapacitors: 25 Maxwell 48V / 500F modules in series (total capacity 3.84kWh, peak power 1.2MW). Used to provide instantaneous high power during the initial stage of motor startup; the supercapacitor bank adopts a modular array, with each module rated at 48V and having a capacity greater than or equal to 500F (farads).

[0101] Lithium-ion battery: Lithium iron phosphate 512V / 100Ah (51.2kWh, continuous power 150kW). Used to provide power after the supercapacitor voltage drops to the threshold.

[0102] PCS (Power Conversion System): A 300kW four-quadrant converter. It connects the mains power, supercapacitors, lithium batteries, and motors to enable bidirectional energy flow. The four-quadrant converter operates in three quadrants: Quadrant 1 (Forward Electrode): The energy storage system absorbs active power from the grid to charge the lithium battery, while simultaneously generating reactive power to support the grid voltage. Quadrant 2 (Forward Regenerative Braking): The energy storage system releases active power to the grid, while simultaneously generating or absorbing reactive power. This is typically used when the grid requires active power support; the energy storage system (supercapacitor or lithium battery pack) discharges and, depending on the grid voltage, generates reactive power to raise the voltage or absorbs reactive power to stabilize the voltage. Quadrant 3 (Reverse Electrode): The energy storage system absorbs both active and reactive power from the grid. This can be used when the grid requires reactive power compensation; the energy storage system absorbs reactive power and stores electrical energy.

[0103] Fourth Quadrant (Reverse Feedback Braking): The energy storage system releases active power to the grid while simultaneously generating or absorbing reactive power. This is typically used when the grid requires both active and reactive power support, allowing the energy storage system to discharge and flexibly provide reactive power compensation. Through four-quadrant operation, the energy storage system can flexibly adjust active and reactive power, quickly respond to the grid's frequency regulation and peak shaving needs, provide inertia support for new power systems, and effectively solve the stability problems after large-scale renewable energy power plants are connected to the grid.

[0104] The controller is used to perform hierarchical power supply and seamless operation.

[0105] 2. Startup process:

[0106] Phase 1 (0-3s): The supercapacitor outputs 300kW, limiting the start-up current to 580A (1.5 times the rated current).

[0107] Phase 2 (3-10s): The lithium battery continues to output 150kW, and the capacitor gradually withdraws.

[0108] Phase 3 (after 10 seconds): The static switch switches to mains power, with a switching time of 8ms.

[0109] 3. Effect Verification:

[0110] index Traditional star-delta start Embodiments of the present invention Maximum starting current 1560A 580A Grid voltage drop 12% ≤3% Equipment lifespan 5 years (contactor) 10+ years

[0111] Control logic pseudocode:

[0112] 1. Initialization checks (prerequisite for startup)

[0113] Before starting the motor, check if the state of charge (SOC) of the supercapacitor is greater than 80% and the SOC of the lithium battery is greater than 30%. Start-up is allowed only if both conditions are met (otherwise, an assertion error will be triggered).

[0114] Pseudocode: assert super_cap.SOC > 0.8 and battery.SOC > 0.3

[0115] 2. Phase 1: Supercapacitor-led startup

[0116] 2.1 The PCS is set to DC-AC inverter mode to convert the stored DC power into AC power to power the motor;

[0117] Pseudocode: pcs.set_mode(DC_AC_INVERTER) #

[0118] 2.2 Supercapacitor Discharge: (Commands are issued by a controller such as a PLC / EMS, and a dedicated controller such as a DSP controls the process through precise hardware peripheral manipulation.) The power ramp-up rate is 100kW / 0.1 seconds (rapid voltage ramp-up) to increase the supercapacitor discharge power to 300kW. Stage 1 Exit Condition: Stage 1 exits when the supercapacitor voltage drops below 1050V or the start-up time exceeds 3 seconds. During this period, the current is maintained stable at 580A. Function: Utilizing the rapid charging and discharging advantage of the supercapacitor, the high power required for startup is quickly provided, ensuring the initial starting power of the motor.

[0119] Pseudo code: super_cap.discharge(power=300kW, ramp_rate=100kW / 0.1s) #

[0120] while not (super_cap.voltage < 1050 or time.elapsed > 3s):

[0121] regulate_current(target=580A)

[0122] Among them, the minimum exit voltage of the supercapacitor in Phase 1 (such as 1050V in the example above) must follow the calculation rules based on the principle of energy conservation.

[0123] First, calculate the energy required to start up high-power equipment based on load demand:

[0124] E_req = P × t (1)

[0125] Where P is the average power required by the high-power equipment during startup, in watts, and t is the duration of the startup process, in seconds.

[0126] Subsequently, based on the rated capacitance (C) and initial voltage (V_start) of the supercapacitor, the theoretical minimum voltage value is precisely calculated using physical formula (2):

[0127] (2)

[0128] 3. Phase 2: Hybrid Power Supply (Supercapacitor + Battery)

[0129] The lithium battery begins to discharge, with its power increasing at a rate of 150kW / 2 seconds, gradually engaging the battery; the supercapacitor's power decreases at a rate of 300kW / 2 seconds, gradually disengaging the supercapacitor; maintaining a stable total power of approximately 260kW (allowing ±5% fluctuation); Stage 2 exit condition: when the motor speed exceeds 90% of its rated speed and is synchronized with the grid, Stage 2 exits; function: the supercapacitor gradually reduces its output, while the battery gradually increases its output, with both working together to supply power, smoothly transitioning to a stable speed and synchronizing with the grid frequency / phase;

[0130] Pseudo code: battery.discharge(ramp_up=150kW / 2s)

[0131] super_cap.discharge(ramp_down=300kW / 2s)

[0132] while not (motor.speed > 0.9 and grid.is_synchronized):

[0133] balance_power(total=260kW, tolerance=±5%)

[0134] The lithium battery side is equipped with a DC / DC converter. By controlling the output of the lithium battery-side DC / DC converter to zero power, "soft isolation" is achieved between the lithium battery and the supercapacitor, allowing the supercapacitor to output power independently in stage 1, while the lithium battery does not output power. When the lithium battery needs to be involved, the DC / DC converter is controlled to smoothly increase its power as needed.

[0135] 4. Phase 3: Grid connection switching to access the power grid

[0136] The PCS is synchronized with the power grid, with phase deviation controlled within 1 degree; the static switch closes at the current zero-crossing point (reducing switching impact); transient data during the switching process is recorded, and if the duration exceeds 8ms, it is logged; the logged data is used to monitor the current transient after the switch closes. Abnormal events lasting longer than 8ms are logged and alarms are triggered for diagnosing potential problems and predictive maintenance (such as synchronization failure, device aging). Transients shorter than 8ms are considered normal physical phenomena and are ignored to avoid log redundancy. This threshold strikes a balance between reliability and efficiency.

[0137] Pseudocode: pcs.sync_to_grid(phase_tolerance=1deg)

[0138] static_switch.close_at_zero_cross()

[0139] log_switch_transient(duration_threshold=8ms)

[0140] The embodiments of the present invention have the following technical effects:

[0141] I. Improve startup performance

[0142] 1. Meets high current requirements

[0143] High-power motors require extremely high currents during startup to overcome static friction and inertial loads, posing a significant challenge to power supply systems. Traditional single-power sources struggle to meet the demands of transient high currents, while supercapacitors, due to their high power density, have become a key component in solving this problem. Research shows that supercapacitors can release a large amount of charge in a short time, with a power density far exceeding that of traditional batteries. Furthermore, the low internal resistance of supercapacitors allows them to respond quickly to load changes, further optimizing the startup process of high-power motors. By combining supercapacitors with lithium batteries, the power supply system can provide a stable high-current output during startup, effectively reducing startup difficulty and improving system reliability.

[0144] 2. Shorten startup time

[0145] Supercapacitors' rapid charging and discharging capabilities can significantly shorten the start-up time of high-power motors. Studies have shown that supercapacitors charge and discharge several times faster than traditional batteries, giving them a clear advantage in handling transient loads. In practical applications, supercapacitors can release energy within milliseconds, rapidly driving the motor to its rated speed. Simultaneously, the lithium battery provides a continuous and stable energy output, ensuring the motor's normal operation after startup. This collaborative mechanism not only improves motor starting efficiency but also reduces energy loss and heat accumulation caused by prolonged startup. Experimental results show that high-power motors starting with a combination of supercapacitors and lithium batteries have a startup time approximately 30% shorter than those starting with a single traditional power source, fully demonstrating the superiority of this combination in improving starting performance.

[0146] II. Extending Motor Life

[0147] 1. Reduce motor shock

[0148] High-power motors generate a massive current surge during startup, which severely damages the motor windings and insulation, increasing the motor's failure rate. A combined starting method using supercapacitors and lithium batteries effectively mitigates this problem. Because supercapacitors can rapidly absorb and release energy, they handle the primary current output during startup, significantly reducing the impact on the lithium battery. Furthermore, the high power density of supercapacitors allows them to provide a stable current output within a short time, preventing motor vibration and overheating caused by current fluctuations. Research data shows that using this combined starting method reduces the motor's starting inrush current by approximately 40% and decreases the required lithium battery cycle life by 80%, significantly extending the motor's lifespan.

[0149] 2. Optimize the operating environment

[0150] The continuous and stable energy output of lithium batteries creates a more stable operating environment for motors, thereby further extending their lifespan. With their high energy density and stable output voltage characteristics, lithium batteries can provide long-term energy support for motors, ensuring stable performance during operation. Meanwhile, supercapacitors further optimize motor operating conditions by absorbing and releasing transient power fluctuations. For example, during sudden load changes or braking, supercapacitors can rapidly absorb or release energy, reducing the burden on lithium batteries. This collaborative mechanism not only improves motor operating efficiency but also significantly reduces the risk of motor fatigue and damage caused by energy fluctuations, providing a strong guarantee for long-term stable motor operation.

[0151] III. Improve system efficiency

[0152] 1. Energy complementarity

[0153] The complementarity of supercapacitors and lithium batteries in energy output is a crucial factor in improving the efficiency of the entire power system. Supercapacitors, with their high power density and rapid charge / discharge capabilities, excel at handling transient load demands, while lithium batteries, with their high energy density and stable output characteristics, are suitable for providing continuous energy support. This complementarity allows the power system to flexibly allocate energy under different operating conditions, thereby achieving higher energy utilization efficiency. For example, during motor startup and braking, supercapacitors are responsible for providing and absorbing peak power, while lithium batteries maintain basic energy output; this division of labor significantly reduces the overall energy consumption of the system. Furthermore, research shows that by rationally designing energy management strategies, the synergistic effect of both can be further optimized, thereby improving the overall performance of the system.

[0154] 2. Reduce energy consumption

[0155] The combined starting method of supercapacitors and lithium batteries not only improves energy utilization efficiency but also significantly reduces energy consumption during motor startup and operation. Studies show that traditional single-power sources often result in significant energy loss as heat when starting high-power motors due to the need for continuous high current output. However, by combining supercapacitors and lithium batteries, the supercapacitor handles the high power demand during startup, thus reducing energy loss in the lithium battery. Furthermore, during motor operation, the supercapacitor absorbs and releases braking energy, further improving the system's energy recovery rate. Experimental results show that this combined starting method can reduce energy consumption during motor startup and operation by approximately 20%, while simultaneously improving overall system efficiency. This energy-saving effect significantly enhances the economic and environmental benefits of the power system, laying a solid foundation for its widespread application in industrial fields.

[0156] Example 2:

[0157] 1. Equipment selection:

[0158] Supercapacitors: Maxwell 48V / 500F modules × 20 in series (total capacity 2.16kWh, peak power 350kW). Used to provide instantaneous high power during the initial stage of motor startup; the supercapacitor bank adopts a modular array, with each module rated at 48V (volts) and having a capacity greater than or equal to 500F (farads).

[0159] Lithium-ion battery: Lithium iron phosphate 512V / 100Ah (51.2kWh, continuous power 150kW). Used to provide power after the supercapacitor voltage drops to the threshold.

[0160] PCS (Power Conversion System): 300kW four-quadrant converter. Used to connect mains power, supercapacitors, lithium batteries, and motors to achieve bidirectional energy flow;

[0161] The controller is used to perform tiered power supply and seamless switching control.

[0162] 2. Startup process:

[0163] Phase 1 (0-3s): The supercapacitor outputs 300kW, limiting the start-up current to 580A (1.5 times the rated current).

[0164] Phase 2 (3-10s): The lithium battery continues to output 150kW, and the capacitor gradually withdraws.

[0165] Phase 3 (after 10 seconds): The static switch switches to mains power, with a switching time of 8ms.

[0166] The motor is started by releasing instantaneous high power through a supercapacitor; the capacitor voltage is monitored in real time, and the system switches to lithium battery power when the voltage is below the threshold; when the motor speed reaches the synchronization condition, the system switches to mains power.

[0167] The supercapacitors handle the peak power during the initial 0-3 seconds of startup, which is greater than or equal to 5C (coulombs), or 300 kilowatts. A modular array design is used to construct a supercapacitor array (or supercapacitor bank) (48V / 500F modules * N, supporting hot-swapping).

[0168] The lithium battery continues to supply power after the capacitor voltage reaches the threshold, providing 1C discharge and 150kW, which only requires the average power of the lithium battery, and the lithium battery life is increased by more than 3 times.

[0169] The energy storage converter (bidirectional converter) enables discharge mode, charging mode and reactive power compensation mode;

[0170] Discharge mode: DC / AC inversion is achieved during the startup phase;

[0171] Charging mode: AC / DC rectification, using mains power / photovoltaic power to charge energy storage;

[0172] Reactive power compensation mode (optional): The SVG function improves the grid power factor. Specifically, when the supercapacitor is not used to start motors, it can be used to supply power to the grid, balancing grid demand. An SVG is essentially a high-power voltage-source converter (VSC), its core being an H-bridge power unit chain composed of IGBTs (Insulated Gate Bipolar Transistors). Operating principle: By real-time detection of the load current, the controller quickly calculates the reactive current component that needs compensation. Active injection: The SVG actively generates a current equal in magnitude and opposite in direction to the reactive current requiring compensation through the rapid switching of power electronic devices, and immediately injects it into the grid.

[0173] 3. Effect Verification:

[0174] index Traditional star-delta start Embodiments of the present invention Maximum starting current 1560A 580A Grid voltage drop 12% ≤3% Equipment lifespan 5 years (contactor) 10+ years

[0175] This invention reduces the starting current from 6 times the rated value of the motor to 1.5 times; reduces the required number of lithium battery cycles by 80%, extending the life of the lithium battery; reduces grid voltage drop by less than 5%, eliminating the need for capacity expansion and improving compatibility with various grids; and reduces the total cost over 10 years by 30% compared to a pure lithium battery solution, improving economic efficiency.

[0176] Example 3, as Figure 2 As shown,

[0177] After the motor starts, it enters Phase 1 (0-3s): The PCS (Power Conversion System) controls the supercapacitor to increase its output power to 300kW at a power increase rate of 100kW / 0.1 seconds to discharge to the motor, limiting the starting current to 580A (1.5 times the motor's rated current). When the supercapacitor voltage drops below 1050V or the starting time exceeds 3 seconds, it exits Phase 1 and enters Phase 2.

[0178] Phase 2 (3-10s): The EMS (Energy Management System) uses its built-in algorithm, combined with collected speed sampling values, to automatically generate appropriate dynamic thresholds. This allows for better coordination between the lithium battery and the motor, improving stability by smoothing the rise in lithium battery power and the decrease in supercapacitor power, preventing large fluctuations in total power (within an allowable range of ±5%). It also improves rapid response by quickly adjusting the power distribution between the lithium battery and supercapacitor when the motor load or speed changes slightly, enabling the system to quickly return to its optimal operating state. Furthermore, it enhances efficiency and safety by ensuring the lithium battery operates within a high-efficiency, safe discharge range (avoiding over-discharge and overheating), while the supercapacitor leverages its ability to handle instantaneous high power. The overall system consumes less energy and experiences less stress on components, ultimately accelerating the motor smoothly to over 90% of its rated speed within a predetermined time (3-10 seconds), creating conditions for grid connection. During this period, based on the calculation results of EMS and the real-time monitoring of the lithium battery status through BMS (Battery Management System), the PCS indirectly controls the lithium battery to output the corresponding power within 3-10 seconds to start discharging, according to the preset dynamic threshold and the real-time status of the lithium battery. The power increases at a rate of 150kW / 2 seconds, and the lithium battery gradually intervenes. The power of the supercapacitor is controlled to decrease at a rate of 300kW / 2 seconds, and the supercapacitor gradually withdraws. The total power is maintained at around 260kW (allowing ±5% fluctuation). When the motor speed exceeds 90% of the rated speed and is synchronized with the grid, the process exits stage 2 and enters stage 3. The conditions for synchronization with the grid are that the phase difference between the motor supply voltage and the grid voltage is less than or equal to 1 degree, the relative voltage deviation is less than or equal to 2%, and the frequency difference is less than or equal to 0.05Hz (Hertz). The relative voltage deviation is defined as the percentage obtained by dividing the absolute value of the difference between the motor voltage and the grid voltage by the grid voltage and then multiplying by 100%. The EMS (Electric Power Management System) monitors the overall system status (such as motor speed and grid parameters) and makes decisions based on built-in algorithms (such as calculating dynamic thresholds), directing the PCS (Power Control System), lithium battery, and supercapacitor to work together. The BMS (Battery Management System) monitors and manages the battery's internal state in real time, including voltage, current, temperature, remaining charge (SOC), and state of health (SOH), ensuring the battery operates within a safe and efficient range and reporting this critical information to the EMS. The dynamic threshold, a target power reference value or power allocation ratio, is determined based on the following logic: The EMS continuously collects the motor's real-time speed. It compares the real-time speed with the expected acceleration curve (or target speed curve or expected curve). If the real-time speed is lower than the expected curve, it indicates insufficient motor acceleration and a need for more power. The EMS dynamically increases the threshold, instructing the lithium battery to increase power output while allowing the supercapacitor to deactivate more slowly. If the real-time speed is higher than the expected curve, it indicates excessive acceleration.The EMS lowers the threshold, causing the lithium battery to reduce its power output and the supercapacitor to exit more quickly. If the real-time speed matches the expected curve, the current threshold is maintained. The dynamic threshold is automatically generated by the EMS through closed-loop feedback control, aiming to ensure that the actual starting speed of the motor closely follows the ideal optimal starting model. The dynamic threshold is used as a control signal for the PCS, and the specific adjustment process is as follows: For the lithium battery, the EMS sends the difference between the target total power (rated power of high-power equipment) and the power carried by the supercapacitor as the dynamic threshold (e.g., if the target total power is 260kW and the current supercapacitor carries 180kW, then the target power threshold (dynamic threshold) for the lithium battery is 80kW). The PCS controls the lithium battery's output power to approach this dynamic threshold at a rate of 150kW / 2 seconds. For the supercapacitor: The EMS calculates the power target (dynamic threshold) that the supercapacitor needs to reduce based on the total power demand and the lithium battery's intervention. The PCS controls the supercapacitor's power to decrease at a rate of 300kW / 2 seconds. Total power stability: These two processes rise and fall, and the rates are coordinated. The ultimate goal is to maintain the total power supplied to the motor at 260kW (±5% fluctuation) during the power handover process.

[0179] Phase 3 (after 10 seconds): The static switch switches to the mains power grid (mains power) in 8ms.

[0180] Example 4: Figure 3 As shown,

[0181] Phase 1 (Capacitor Burst): The supercapacitor discharges, with a peak output power of 350kW. During startup, the PCS controls the supercapacitor to discharge at 300kW for 3 seconds; current closed-loop control stabilizes the output current at 580A (1.5 times the motor's rated current); speed detection determines whether the startup is normal based on the speed and the depth of capacitor discharge. If the startup is normal, Phase 2 begins when the supercapacitor voltage is less than or equal to 1050V or the discharge time is greater than 3 seconds.

[0182] Phase 2 (Hybrid Power Supply): Lithium battery ramp-up: The PCS controls the lithium battery current to gradually increase so that the discharge power to the motor increases according to the power transition slope. At the same time, the supercapacitor gradually reduces the current so that the discharge power of the supercapacitor decreases according to the power transition slope until it stops discharging. Dynamic power allocation: While the lithium battery gradually increases the discharge power, the supercapacitor gradually reduces the discharge power to maintain the total discharge power at 260kW±5. Speed ​​verification: The actual motor speed is detected by sensors or transmitted to the PCS for comparison with the set speed to determine whether the motor speed is within the set value range. The PCS system sets the response strategy, and the PLC adjusts the motor parameters to correct the motor to the set (normal) speed. The PLC controls the phase-locked loop to detect and switch the frequency. The switching conditions are that the speed is greater than or equal to 90% of the rated speed and the phase difference is less than 1 degree. When the motor speed is greater than or equal to 90% of the rated speed and the motor is synchronized with the power grid, Phase 3 is entered.

[0183] Phase 3 (Grid-connected Operation): Synchronous detection, detecting zero-crossing points; zero-current switching, disconnecting the lithium battery and supercapacitor at the zero-crossing point, switching the motor's power supply to the grid. With grid load, the grid supplies power to the motor after startup; via the PCS, the grid is controlled to charge the supercapacitor and lithium battery.

[0184] At any stage, when the current supplied to the motor triggers the overcurrent protection, the motor parameters are adjusted via PLC to correct the motor current to within the set normal range.

[0185] In Phase 2, when the temperature of the lithium battery exceeds 45 degrees Celsius, the charging and discharging power of the lithium battery is reduced for safety reasons.

[0186] Table 1 below lists the key technical parameters for the three stages:

[0187] stage Conditions for proceeding to the next stage Current operating parameters Phase 1 Startup signal + supercapacitor SOC > 80% The supercapacitor discharge current (580A) is ≤ 1.5 times the motor's rated current. Phase 2 Supercapacitor voltage ≤ 1050V and operating time > 3 seconds Power transition slope ≤50kW / s Phase 3 The motor speed is ≥90% of the rated speed and the voltage phase difference is <1 degree. Switching inrush current <10% of motor rated current

[0188] It should be understood that the specific order or hierarchy of steps in the disclosed process is an example of an exemplary method. Based on design preferences, it should be understood that the specific order or hierarchy of steps in the process may be rearranged without departing from the scope of this disclosure. The appended method claims provide elements of various steps in an exemplary order and are not intended to limit the scope to the specific order or hierarchy described.

[0189] In the above detailed description, various features are combined together in a single embodiment to simplify this disclosure. This approach to disclosure should not be construed as reflecting an intention that embodiments of the claimed subject matter require more features than are explicitly stated in each claim. Rather, as reflected in the appended claims, the invention is presented with fewer features than all of the features of the single disclosed embodiment. Therefore, the appended claims are hereby explicitly incorporated into the detailed description, wherein each claim stands alone as a preferred embodiment of the invention.

[0190] The disclosed embodiments have been described above to enable any person skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein can be applied to other embodiments without departing from the spirit and scope of this disclosure. Therefore, this disclosure is not limited to the embodiments given herein, but is consistent with the broadest scope of the principles and novel features disclosed in this application.

[0191] The foregoing description includes examples of one or more embodiments. It is certainly impossible to describe all possible combinations of components or methods in order to describe the above embodiments, but those skilled in the art will recognize that further combinations and arrangements of the various embodiments are possible. Therefore, the embodiments described herein are intended to cover all such changes, modifications, and variations falling within the scope of the appended claims. Furthermore, the term "comprising" as used in the specification or claims is used in a manner similar to the term "including." Additionally, the use of any term "or" in the specification of the claims is intended to mean "non-exclusive or."

[0192] Those skilled in the art will also understand that the various illustrative logical blocks, units, and steps listed in the embodiments of the present invention can be implemented by electronic hardware, computer software, or a combination of both. To clearly demonstrate the interchangeability of hardware and software, the functions of the various illustrative components, units, and steps described above have been generally described. Whether such functionality is implemented through hardware or software depends on the specific application and the overall system design requirements. Those skilled in the art can implement the described functions using various methods for each specific application, but such implementation should not be construed as exceeding the scope of protection of the embodiments of the present invention.

[0193] The various illustrative logic blocks or units described in the embodiments of this invention can be implemented or operate the described functions using a general-purpose processor, digital signal processor, application-specific integrated circuit (ASIC), field-programmable gate array or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof. The general-purpose processor can be a microprocessor; alternatively, it can be any conventional processor, controller, microcontroller, or state machine. The processor can also be implemented using a combination of computing devices, such as a digital signal processor and a microprocessor, multiple microprocessors, one or more microprocessors combined with a digital signal processor core, or any other similar configuration.

[0194] The steps of the methods or algorithms described in the embodiments of this invention can be directly embedded in hardware, a software module executed by a processor, or a combination of both. The software module can be stored in RAM, flash memory, ROM, EPROM, EEPROM, registers, hard disk, removable disk, CD-ROM, or any other form of storage medium in the art. Exemplarily, the storage medium can be connected to the processor so that the processor can read information from and write information to the storage medium. Optionally, the storage medium can also be integrated into the processor. The processor and storage medium can be housed in an ASIC, which can be housed in a user terminal. Optionally, the processor and storage medium can also be housed in different components of the user terminal.

[0195] In one or more exemplary designs, the functions described in the embodiments of the present invention can be implemented in hardware, software, firmware, or any combination of these three. If implemented in software, these functions can be stored on a computer-readable medium or transmitted on a computer-readable medium in the form of one or more instructions or code. Computer-readable media include computer storage media and communication media that facilitate the transfer of computer programs from one place to another. Storage media can be any available media that can be accessed by a general-purpose or special-purpose computer. For example, such computer-readable media can include, but is not limited to, RAM, ROM, EEPROM, CD-ROM or other optical disk storage, magnetic disk storage or other magnetic storage devices, or any other medium that can be used to carry or store program code in the form of instructions or data structures and other forms that can be read by a general-purpose or special-purpose computer, or a general-purpose or special-purpose processor. Furthermore, any connection can be suitably defined as a computer-readable medium, for example, if the software is transmitted from a website, server, or other remote resource via a coaxial cable, fiber optic cable, twisted pair, digital subscriber line (DSL), or wirelessly, such as infrared, wireless, and microwave, it is also included in the defined computer-readable medium. The disks and discs mentioned include compressed disks, laser discs, optical discs, DVDs, floppy disks, and Blu-ray discs. Disks typically copy data magnetically, while discs typically copy data optically using lasers. Combinations of the above can also be contained in computer-readable media.

[0196] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for flexible start-up of high-power equipment, characterized in that, include: The supercapacitor is controlled to increase the power of its discharge to the high-power device to the preset maximum discharge power of the capacitor at a preset first power increase rate; wherein, the maximum discharge power of the capacitor is the highest power of the high-power device in the initial stage of startup. When the preset first switching condition is met, the supercapacitor is controlled to gradually reduce the discharge power to the high-power device, while the lithium battery is controlled to gradually increase the discharge power to the high-power device, so as to maintain the total discharge power to the high-power device at the rated power of the high-power device. When the operating conditions of the high-power equipment meet the preset grid connection standards, the grid is connected to supply power to the high-power equipment, and the lithium battery and the supercapacitor are disconnected.

2. The method for flexible start-up of high-power equipment as described in claim 1, characterized in that, The control of the supercapacitor to increase the power of discharge to high-power devices to the preset maximum discharge power of the capacitor at a preset first power increase rate includes: The discharge current of the supercapacitor is kept stable at a preset discharge current, and the discharge voltage of the supercapacitor is controlled to gradually increase so that the supercapacitor continuously discharges to the high-power device at a preset first power increase rate. When the discharge power of the supercapacitor reaches the preset maximum discharge power of the capacitor, the discharge to the high-power device is maintained at the maximum discharge power of the capacitor. The preset discharge current is 1.5 times the rated current of the high-power device.

3. The method for flexible start-up of high-power equipment as described in claim 1, characterized in that, The condition of satisfying the preset first switching condition includes: the discharge voltage of the supercapacitor is less than the preset capacitor voltage or the continuous discharge time of the supercapacitor is greater than the preset independent discharge time of the capacitor.

4. The method for flexible start-up of high-power equipment as described in claim 1, characterized in that, The high-power equipment meets the preset grid connection standards, including: The high-power equipment operates at more than 90% of its rated operating conditions, and the phase difference between the current power supply voltage of the high-power equipment and the voltage phase of the power grid is less than 1 degree.

5. The method for flexible start-up of high-power equipment as described in claim 1, characterized in that, The high-power device is a motor; The control of the supercapacitor to increase the power of discharge to high-power devices to the preset maximum discharge power of the capacitor at a preset first power increase rate includes: While maintaining the discharge current of the supercapacitor at a stable 580A, the discharge voltage of the supercapacitor is gradually increased so that the supercapacitor continuously discharges to the motor at a power increase rate of 100kW every 0.1 seconds, and when the discharge power of the supercapacitor reaches 300kW, it continues to discharge to the high-power equipment at the maximum discharge power of the capacitor.

6. The method for flexible start-up of high-power equipment as described in claim 1, characterized in that, The high-power device is a motor; When a preset first switching condition is met, the supercapacitor is controlled to gradually decrease its discharge power to the high-power device, while the lithium battery is controlled to gradually increase its discharge power to the high-power device, so as to maintain the total discharge power to the high-power device at the rated power of the high-power device, including: When the discharge voltage of the supercapacitor is less than 1050V or the continuous discharge time of the supercapacitor is greater than 3 seconds, the supercapacitor is controlled to discharge to the high-power device at a power decrease rate of 150kW per second, while the lithium battery is controlled to continuously discharge to the motor at a power increase rate of 75kW per second until the total discharge power to the high-power device is 260kW. Then, the supercapacitor is adjusted to discharge to the high-power device at a power decrease rate of 75kW per second to maintain the total discharge power to the high-power device at 260kW.

7. The method for flexible start-up of high-power equipment as described in claim 1, characterized in that, The high-power device is a motor; When the operating conditions of the high-power equipment meet the preset grid connection standards, the process of connecting to the grid to supply power to the high-power equipment and disconnecting the lithium battery and the supercapacitor includes: When the motor speed is greater than 90% of the rated speed, and the phase difference between the current supply voltage of the motor and the grid is less than 1 degree, the power grid is switched to supply power to the high-power device at the current zero-crossing point, and the lithium battery and the supercapacitor are disconnected.

8. The method for flexible start-up of high-power equipment as described in claim 1, characterized in that, The method of controlling the supercapacitor to increase the power of discharge to high-power devices to the preset maximum discharge power of the capacitor at a preset first power increase rate also includes: Check whether the state of charge of the supercapacitor is greater than 80% and whether the state of charge of the lithium battery is greater than 30%. If the inspection result shows that the state of charge of the supercapacitor is greater than 80% and the state of charge of the lithium battery is greater than 30%, then the supercapacitor is controlled to increase the power of discharge to the high-power device to the preset maximum discharge power of the capacitor at a preset first power increase rate.

9. The method for flexible start-up of high-power equipment as described in claim 1, characterized in that, The high-power device is a motor; the method includes: When the state of charge of the supercapacitor is found to be greater than 80% and the state of charge of the lithium battery is greater than 30%, the motor is started and the energy storage converter is set to DC-AC inverter mode. The energy storage converter is controlled to stabilize the discharge current of the supercapacitor at 580A, and the supercapacitor is controlled to increase the discharge power to 300kW to power the motor at a power increase rate of 100kW / 0.1 seconds. When the supercapacitor voltage drops below 1050V or the startup time exceeds 3 seconds, the lithium battery begins to discharge to the motor at a rising discharge power rate of 75kW / s, while the supercapacitor discharges to the motor at a decreasing discharge power rate of 150kW / s. This continues until the total discharge power to the motor stabilizes at 260kW±5%. At this point, the decreasing discharge power rate of the supercapacitor is adjusted to 75kW / s, and the supercapacitor gradually disengages to maintain the total discharge power to the motor at a stable 260kW±5%. When the motor speed exceeds 90% of the rated speed and the phase difference between the supply voltage and the grid voltage is within 1 degree, the power supply of the motor is switched to the grid power supply at the current zero crossing point, and the switching time is recorded when the switching time exceeds 8 milliseconds.

10. A system for flexible starting of high-power equipment, characterized in that, The method for flexible start-up of high-power equipment as described in claims 1 to 8 includes: a supercapacitor, a lithium battery, an energy storage converter, a controller, high-power equipment, and a power grid; The super battery, lithium battery, controller, high-power equipment, and power grid are respectively connected to the energy storage converter; The energy storage converter is used to charge the super battery and the lithium battery using the power grid when the high-power equipment is idle. The energy storage converter is also used to control the supercapacitor to increase the power of the discharge to the high-power device to the preset maximum discharge power of the capacitor during the startup of the high-power device; and to maintain the total discharge power to the high-power device at the rated power of the high-power device when the preset first switching condition is met; and to switch to the grid to supply power to the high-power device when the operating conditions of the high-power device meet the preset grid connection standard, and to disconnect the lithium battery and the supercapacitor.

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