Synchronous motor system with high inertia and stable support regulation and control capability and control method

Abstract

The invention belongs to the technical field of electric power equipment, and discloses a synchronous motor system with high inertia and stable support regulation and control capability and a control method, and the system comprises a high-inertia synchronous motor, an excitation controller and a transformer. The high-inertia synchronous motor is used as a synchronous generator or a synchronous motor; the excitation controller is connected in series with a single-phase excitation winding of a rotor of the high-inertia synchronous motor and is used for outputting direct-current excitation current to the single-phase excitation winding so as to change the power angle of the synchronous motor, so that the power output by the high-inertia synchronous motor at a constant rotating speed under a power generation or electric working condition meets the requirements of a power grid, and stable support for the power grid is realized; by increasing the physical inertia of the synchronous motor and matching with reasonable regulation and control of rotor excitation, the long-term stable supporting capability of the synchronous motor is enhanced, so that constant frequency / constant voltage of the system can still be maintained when the system is disturbed or breaks down suddenly, the system is strived not to be unstable, not out of step and not to oscillate, and the reliability of the system is improved. And the transient stability supporting effect of the synchronous motor on the new energy power system is enhanced.

Description

Technical Field

[0001] This invention belongs to the field of power equipment technology, and more specifically, relates to a synchronous motor system and control method with high inertia and stable support and regulation capabilities. Background Technology

[0002] With the large-scale integration of high-proportion renewable energy sources and the decline and decommissioning of traditional synchronous generator units, the synchronous inertia of renewable energy power systems has significantly decreased. Due to the prominent volatility and randomness on both the power supply and load sides, especially the fragile grid performance of renewable energy power generation equipment, the system is more prone to sudden power imbalances and disturbances. Instantaneous power imbalances and disturbances can easily trigger system voltage / frequency instability, or cause the system to lose transient stability and enter a dynamic stability phase, resulting in system oscillations. In cases where transient and dynamic stability support capabilities are insufficient, this can lead to the sudden disconnection of local power grids or large-scale system blackouts, posing a severe challenge to the safe and stable operation of renewable energy power systems.

[0003] To enhance the stability of new energy power systems, current methods typically involve adding power compensation equipment: electrochemical energy storage and flywheel energy storage for active power compensation, and synchronous condensers and SVG for reactive power compensation. However, these devices struggle to provide the high inertia and active constant-frequency / constant-voltage stability support required by the system, particularly lacking active constant-frequency stability support capabilities. Existing technologies have addressed improvements to synchronous condensers, which are electrically operated and idle on the grid. By changing the speed of the condenser, its stored energy is released, providing inertia support or active power compensation. However, the motor's own energy storage is limited. When the grid experiences large and prolonged active power fluctuations, controlling the motor to change speed and release its physical energy storage cannot achieve continuous, stable, constant-frequency support for the grid. With the declining proportion of traditional synchronous generators, enhancing the transient and dynamic stability support capabilities of synchronous generators driven by a prime mover at constant speed, especially maintaining system transient stability and better leveraging the stability and fault support capabilities of constant-speed synchronous generator sets to compensate for the loss of stability support capabilities due to the declining proportion of traditional synchronous generators, becomes particularly important and urgent. Meanwhile, it is also crucial for large-capacity synchronous motors to possess the ability to support system frequency / voltage transient stability. Currently and for a considerable period to come, a certain proportion of synchronous motors will remain in new energy power systems, including synchronous generators in thermal power, nuclear power, and hydropower applications, and electrically excited synchronous motors in heavy-duty industrial applications such as large pumping stations and large wind turbines. Although existing synchronous motors can maintain constant speed and frequency operation under normal system conditions, they face the risk of losing synchronization if sudden power imbalances or disturbances occur in the grid, causing voltage or frequency fluctuations. Their ability to support grid stability has not been fully explored and utilized, making it difficult to provide strong support for the stability of new energy power systems. For existing or newly installed synchronous motors, how to further enhance their active support effect for frequency / voltage stability in new energy power systems, especially to more effectively support the transient stability of new energy power systems, ensuring the system does not become unstable, lose synchronization, or oscillate, and better leverage the ballast role of synchronous generator sets and other power equipment driven and controlled by prime movers in actively supporting new energy power systems, is a critical issue that urgently needs to be addressed. Summary of the Invention

[0004] In view of the above-mentioned defects or improvement needs of the prior art, the present invention provides a synchronous motor system and control method with high inertia and stable support control capability, the purpose of which is to improve the transient stability support capability of synchronous generators and synchronous motors driven and controlled by prime movers at constant speed.

[0005] To achieve the above objectives, the present invention provides a synchronous motor system with high inertia and stable support and control capabilities, comprising: a high-inertia synchronous motor, an excitation controller, and a transformer;

[0006] The high-inertia synchronous motor is used as a synchronous generator or a synchronous motor; when used as a synchronous generator, the high-inertia synchronous motor is coaxially connected to the prime mover and is used to generate electricity to the grid; when used as a synchronous motor, the high-inertia synchronous motor is coaxially connected to the load and is used to absorb power from the grid to drive the load.

[0007] The excitation controller is connected in series with the single-phase excitation winding of the rotor of the high-inertia synchronous motor. It is used to output DC excitation current to the single-phase excitation winding to change the induced electromotive force or power angle of the high-inertia synchronous motor, so that the power output by the high-inertia synchronous motor at a constant speed under power generation or motoring conditions meets the grid demand, and provides stable support to the grid during grid faults.

[0008] The transformer is connected to the high-inertia synchronous motor and the power grid to realize voltage transformation and electrical isolation between the high-inertia synchronous motor and the power grid.

[0009] Furthermore, the rotor diameter or axial length of the high-inertia synchronous motor is greater than a preset value to increase its own rotational inertia;

[0010] Alternatively, the high-inertia synchronous motor includes a synchronous motor and a flywheel coaxially connected to the synchronous motor. The flywheel is independent of the rotor of the synchronous motor and is mechanically connected to the rotor coaxially. Alternatively, the flywheel is integrated with the rotor of the synchronous motor. The flywheel is used to increase the rotational inertia of the synchronous motor.

[0011] Furthermore, the high-inertia synchronous motor or the synchronous motor includes a stator, a rotor, a motor shaft, and bearings;

[0012] The stator includes a stator core and a three-phase armature winding that is uniformly slotted in the stator core; the rotor includes a rotor core and a single-phase excitation winding; the rotor core is a salient pole rotor or a non-salient pole rotor, and the single-phase excitation winding is placed in a slot on the surface of the salient pole rotor or on the magnetic pole of the non-salient pole rotor.

[0013] The motor shaft connects the rotor to the prime mover, or the motor shaft connects the rotor to the load; the bearing is used to support the motor shaft.

[0014] Furthermore, when the synchronous motor is installed horizontally, the bearing is a magnetic levitation bearing;

[0015] When the synchronous motor is installed vertically, the bearing is a magnetic levitation bearing and the flywheel is a magnetic levitation flywheel.

[0016] The present invention also provides an excitation control method, which operates on an excitation controller in a synchronous motor system with high inertia and stable support and control capability as described in any of the above claims, the excitation control method comprising:

[0017] When the grid frequency fluctuates, a compensation transfer function is pre-designed. The compensation transfer function is multiplied by the transfer function of the high-inertia synchronous motor itself to obtain a new transfer function. The signal obtained by multiplying the current DC excitation current by the new transfer function is used as the excitation control signal to control the adaptive change of the power angle of the high-inertia synchronous motor, thereby controlling the change of the torque of the high-inertia synchronous motor. This ensures that the active power output by the high-inertia synchronous motor at a constant speed under power generation or motoring conditions meets the grid demand, thus achieving stable support for the grid frequency.

[0018] The design process of the compensation transfer function includes:

[0019] Based on the speed and power of the high-inertia synchronous motor, the time-domain signal of the motor torque is obtained; the time-domain signal of the motor torque is then converted into a frequency-domain signal.

[0020] The frequency domain signal is multiplied by a preset compensation transfer function to obtain the output signal; wherein the preset compensation transfer function is composed of one or more preset series-connected lead or lag transfer function units.

[0021] The phase of the output signal is compared with the phase of the power grid frequency to obtain the phase difference deviation, wherein the sign of the phase deviation depends on the current state of the high-inertia synchronous motor; based on the phase deviation, the parameters of the preset compensation transfer function are adjusted so that the phase deviation approaches 0, thereby obtaining the designed compensation transfer function.

[0022] Furthermore, it also includes: when the grid voltage fluctuates, adjusting the DC excitation current to change the induced electromotive force of the high-inertia synchronous motor, so that the reactive power output by the high-inertia synchronous motor at a constant speed under power generation or motoring conditions meets the grid demand, thereby achieving stable support for the grid voltage.

[0023] Furthermore, the grid voltage fluctuation includes grid voltage drops or grid voltage increases;

[0024] When the grid voltage drops, the DC excitation current is increased according to the motor excitation characteristic curve to enhance the induced electromotive force. This allows the high-inertia synchronous motor to send inductive reactive power to the grid while reducing its power angle, thus providing stable support for the grid voltage.

[0025] When the grid voltage rises, the DC excitation current is reduced according to the motor excitation characteristic curve to reduce the induced electromotive force. Then, under the premise of increasing the power angle of the high-inertia synchronous motor, inductive reactive power is absorbed from the grid to achieve stable support for the grid voltage.

[0026] The present invention also provides an excitation control system, including a computer-readable storage medium and a processor;

[0027] The computer-readable storage medium is used to store executable instructions;

[0028] The processor is used to read executable instructions stored in the computer-readable storage medium and execute the excitation control method described above.

[0029] The present invention also provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the excitation control method as described in any of the preceding claims.

[0030] The present invention also provides a computer program product, including a computer program that, when run on a computer, causes the computer to execute the excitation control method described in any of the preceding claims.

[0031] In summary, the above-described technical solutions conceived in this invention can achieve the following beneficial effects:

[0032] (1) This invention provides a novel synchronous motor topology with high inertia and stable support and control capability. Based on the high inertia synchronous motor, and in conjunction with the excitation controller with active stable support and control capability, the motor power angle is adaptively changed by changing the magnitude of the DC excitation current, so that the output power of the high inertia synchronous motor in the power generation or motoring mode meets the grid demand. When the high inertia synchronous motor is in the power generation mode, under the constant speed drive of the prime mover and the effect of its own high inertia, the synchronous motor maintains a constant speed. When the high inertia synchronous motor is in the motoring mode, the synchronous motor takes advantage of its high inertia to maintain a constant speed. Through mechanical-electromagnetic coordination, the synchronous generator set achieves the hard support capability of the grid.

[0033] (2) The present invention increases the rotational inertia of the synchronous motor by adding a flywheel to the original synchronous motor or increasing the rotor diameter or axial length of the synchronous motor to make the synchronous motor a high-inertia synchronous motor.

[0034] (3) This invention can be used to build new generator sets and electric drive equipment, and can also be used to modify existing generator sets and equipment. It only requires the addition of a flywheel or / and modification of its excitation control system. The modification cost is low and the implementation is easy.

[0035] (4) When the grid is subjected to sudden power (active / reactive) imbalance, the grid is subjected to sudden disturbances, resulting in fluctuations in grid voltage and frequency. Based on the high inertia synchronous motor and combined with the excitation control method of the present invention, the synchronous motor can be rapidly and powerfully regulated. Especially when the grid frequency fluctuates, the designed compensation transfer function can apply additional damping torque on the basis of the original electromagnetic torque, so that the high inertia synchronous motor can output active power at a constant speed under power generation or motoring conditions to meet the grid demand. This enhances the transient and dynamic stability support capability of the synchronous generator driven and controlled by the prime mover at constant speed, as well as the synchronous motor's ability to support the transient stability of system frequency / voltage.

[0036] (5) This invention can be applied to synchronous generator sets in thermal power, nuclear power, hydropower, and other new energy power systems that are controlled by constant-speed prime movers. It effectively ensures constant-speed and constant-frequency power generation of the units, enhances the active and hard support capability for voltage / frequency stability of the new energy power grid, resists sudden changes in voltage and frequency and fault impacts caused by sudden power imbalances or sudden disturbances in the power grid, strongly supports the transient stability of the power grid, and avoids system oscillations in the power grid. It can also be applied to the drive systems of large-capacity electrically excited synchronous motors such as large pumping stations and large wind turbines in new energy power systems, providing transient stability auxiliary support capability for the power grid, suppressing sudden fluctuations in power grid voltage and frequency, so as to help maintain the transient stability of power grid voltage and frequency and support the constant voltage and constant frequency operation of the power grid.

[0037] In general, this invention enhances the long-term stability support capability of synchronous motors by increasing the physical inertia of the synchronous motor and coordinating with reasonable control of rotor excitation. This aims to maintain constant frequency / voltage of the system even when there are sudden disturbances or faults, striving to prevent the system from becoming unstable, losing synchronization, or oscillating, thereby enhancing the transient stability support role of synchronous motors for new energy power systems. Attached Figure Description

[0038] Figure 1 This is one of the topological diagrams of a synchronous motor system with high inertia and stable support and control capabilities provided in an embodiment of the present invention;

[0039] Figure 2 This is a second schematic diagram of a synchronous motor system topology with high inertia and stable support and control capabilities, provided as an embodiment of the present invention. Detailed Implementation

[0040] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of this invention described below can be combined with each other as long as they do not conflict with each other.

[0041] Example 1

[0042] like Figure 1 and Figure 2 As shown, this embodiment of the invention provides a synchronous motor system with high inertia and stable support and control capabilities, mainly including: a high inertia synchronous motor, an excitation controller, and a transformer.

[0043] High-inertia synchronous motors are used as synchronous generators or synchronous motors. The rotor diameter or axial length of a high-inertia synchronous motor is greater than a preset value to increase the rotational inertia of the synchronous motor. Alternatively, a high-inertia synchronous motor includes a synchronous motor and a flywheel coaxially connected to the synchronous motor. The flywheel is independent of the rotor of the synchronous motor and is coaxially connected to the rotor mechanically. Alternatively, the flywheel is integrated with the rotor of the synchronous motor and is used to increase the rotational inertia of the synchronous motor.

[0044] When a high-inertia synchronous motor is kept in grid-connected operation, it is coaxially connected to the prime mover to generate electricity for the grid when acting as a synchronous generator; when acting as a synchronous motor, it is coaxially connected to the load to absorb power from the grid to drive the load.

[0045] In this embodiment of the invention, the high-inertia synchronous motor includes horizontal or vertical mounting methods, and its structure includes components such as stator, rotor, motor shaft, and bearings.

[0046] The stator includes a stator core and three-phase armature windings. The stator core is a laminated core with slots evenly spaced in it to hold the three-phase armature windings.

[0047] The rotor includes a rotor core and a single-phase excitation winding. The rotor core is either a salient pole rotor or a non-salient pole rotor, so that the rotor topology exhibits salient pole or non-salient pole characteristics. The rotor core is a solid structure or a laminated structure. The single-phase excitation winding is placed in a slot on the surface of the salient pole rotor or on the magnetic pole of the non-salient pole rotor.

[0048] The motor shaft, as a key component connecting the rotor and external machinery, is used to transmit mechanical torque. In this embodiment of the invention, the external machinery is a prime mover or a load.

[0049] Bearings are used to support the motor shaft, effectively reducing shaft friction and ensuring smooth and stable rotation of the rotor system. In this embodiment of the invention, to achieve high inertia in the synchronous motor, the rotor diameter or axial length can be appropriately increased, or a flywheel can be further configured. The flywheel is independent of the synchronous motor rotor body and is coaxially connected to the rotor mechanical transmission, or it can be integrated with the synchronous motor rotor body and mechanically transmitted at the same speed and coaxial with the rotor, ultimately forming a high-inertia synchronous motor.

[0050] If the motor is horizontally mounted, magnetic levitation bearings can be used to further reduce frictional losses in the motor system. If the motor is vertically mounted, a magnetic levitation flywheel and magnetic levitation bearings can both be used to further reduce the pressure and frictional losses on the bearings from the flywheel system.

[0051] The excitation controller is connected in series with the single-phase excitation winding of the rotor of the high-inertia synchronous motor to provide DC excitation current to the single-phase excitation winding of the rotor. This allows the high-inertia synchronous motor to change its induced electromotive force or power angle by changing the magnitude of the DC excitation current while maintaining its own constant speed. In this way, the output power of the high-inertia synchronous motor under power generation or motoring conditions can meet the grid demand, and the synchronous generator set can provide transient stability support to the grid during grid faults.

[0052] When there is no disturbance or fault in the power grid, the amplitude and frequency of the rated voltage at the stator winding terminals remain unchanged. The excitation controller provides DC excitation current to the rotor single-phase excitation winding. At this time, the excitation controller adjusts the DC excitation current appropriately according to the load conditions. Under the condition of ensuring the static stability of the high-inertia synchronous motor (constant speed), the motor power angle changes adaptively, thereby enabling the output power of the high-inertia synchronous motor in power generation or motoring conditions to meet the power grid demand.

[0053] When a sudden power imbalance (active / reactive) in the power grid causes a sudden disturbance, resulting in fluctuations in grid voltage and frequency, and consequently changes in the motor's power angle, the excitation controller rapidly adjusts the DC excitation current of the motor rotor based on the changes in grid voltage, motor power angle, and grid frequency. This achieves rapid and powerful regulation of the synchronous motor, providing strong support for the transient stability of grid voltage and frequency. The aim is to achieve transient stability of the motor and the new energy power system, maintain constant grid voltage and frequency, and prevent the motor from losing synchronization or becoming unstable relative to the grid, as well as power system oscillations. The core principle of excitation control is to strive for transient stability of grid voltage and frequency, avoiding instability, loss of synchronization, and oscillations.

[0054] As a specific implementation method, when the grid voltage fluctuates, the DC excitation current is adjusted to change the power angle of the high-inertia synchronous motor, enabling it to supply or absorb inductive reactive power to the grid and support grid voltage stability. Specifically, when the grid voltage drops (or rises), the DC excitation current is increased (or decreased) according to the motor's excitation characteristic curve to increase (or decrease) the induced electromotive force. At this time, in order to keep the motor's active power constant, the motor's power angle will be reduced (or increased), while simultaneously supplying (or absorbing) inductive reactive power to the grid and supporting grid voltage stability.

[0055] When the grid frequency fluctuates (drops or rises), a pre-designed compensation transfer function is used. This compensation transfer function is multiplied by the synchronous motor's own transfer function to obtain a new transfer function. The current DC excitation current is then multiplied by this new transfer function to change its magnitude. Based on the resulting DC excitation current, the motor's power angle is adaptively adjusted, thereby controlling the change in motor torque. This ensures that the high-inertia synchronous motor, while statically stable (with a constant speed), can supply or absorb power to the grid, maintaining a balance between electromagnetic and mechanical power and supporting grid frequency stability. The synchronous motor's own transfer function is known.

[0056] The design process of the compensation transfer function includes:

[0057] (1) Detect the current motor speed, grid frequency, motor power and other signals.

[0058] (2) Process and analyze the signal, determine the subsynchronous or supersynchronous state of the motor based on the current motor speed and grid frequency; and obtain the time domain signal of the motor torque based on the motor speed and motor power; convert the time domain signal of the motor torque into the frequency domain to obtain the frequency domain signal of the motor torque.

[0059] (3) Multiply the frequency domain signal of the motor torque with the preset compensation transfer function to obtain the output signal; wherein the preset compensation transfer function is composed of one or more preset series lead or lag transfer function units, wherein the lead or lag transfer function units are known.

[0060] (4) The phase of the output signal is compared with the phase of the detected grid frequency to obtain the phase difference deviation. The sign of this phase deviation depends on the current state of the motor, which in turn affects the sign of the additional damping torque applied during compensation. Based on this phase deviation, the parameters of the preset compensation transfer function are adjusted so that the phase deviation approaches 0, thus obtaining the designed compensation transfer function. This compensation transfer function enables the application of additional damping torque on top of the original electromagnetic torque.

[0061] When a high-inertia synchronous motor is in generating mode, if the current motor torque is positive, it outputs power to the grid; if the motor torque is negative, it absorbs power from the grid. When a high-inertia synchronous motor is in motoring mode, if the current motor torque is positive, it absorbs power from the grid; if the motor torque is negative, it outputs power to the grid.

[0062] The transformer is connected to the high-inertia synchronous motor and the power grid to achieve voltage transformation and electrical isolation between the high-inertia synchronous motor and the power grid.

[0063] Example 2

[0064] This invention provides an excitation control system, including a memory and a processor. The memory stores a computer program, and the processor executes the computer program to implement the steps of the excitation control method in Embodiment 1 above.

[0065] The relevant technical solutions are the same as above, and will not be repeated here.

[0066] Example 3

[0067] This invention provides a computer-readable storage medium storing a computer program thereon, which, when executed by a processor, implements the steps of the excitation control method in Embodiment 1 above.

[0068] Specifically, the memory may include high-speed random access memory, as well as non-volatile memory, such as hard disks, RAM, plug-in hard disks, smart media cards (SMC), secure digital cards (SD), flash cards, at least one disk storage device, flash memory device, or other volatile solid-state storage devices.

[0069] The relevant technical solutions are the same as above, and will not be repeated here.

[0070] Example 4

[0071] This invention provides a computer program product, including a computer program that, when run on a computer, causes the computer to execute the steps of the excitation control method in Embodiment 1 above.

[0072] The relevant technical solutions are the same as above, and will not be repeated here.

[0073] Those skilled in the art will readily understand that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements 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 synchronous motor system with high inertia and stable support and control capabilities, characterized in that, include: High inertia synchronous motors, excitation controllers, and transformers; The high-inertia synchronous motor is used as a synchronous generator or synchronous motor. When used as a synchronous generator, the high-inertia synchronous motor is coaxially connected to the prime mover and is used to generate electricity for the grid; when used as a synchronous motor, the high-inertia synchronous motor is coaxially connected to the load and is used to absorb power from the grid to drive the load. The excitation controller is connected in series with the single-phase excitation winding of the rotor of the high-inertia synchronous motor. It is used to output DC excitation current to the single-phase excitation winding to change the induced electromotive force or power angle of the high-inertia synchronous motor, so that the power output by the high-inertia synchronous motor at a constant speed under power generation or motoring conditions meets the grid demand, and provides stable support to the grid during grid faults. The transformer is connected to the high-inertia synchronous motor and the power grid to realize voltage transformation and electrical isolation between the high-inertia synchronous motor and the power grid.

2. The synchronous motor system with high inertia and stable support and control capability according to claim 1, characterized in that, The rotor diameter or axial length of the high-inertia synchronous motor is greater than a preset value in order to increase its rotational inertia. Alternatively, the high-inertia synchronous motor includes a synchronous motor and a flywheel coaxially connected to the synchronous motor. The flywheel is independent of the rotor of the synchronous motor and is mechanically connected to the rotor coaxially. Alternatively, the flywheel is integrated with the rotor of the synchronous motor. The flywheel is used to increase the rotational inertia of the synchronous motor.

3. The synchronous motor system with high inertia and stable support and control capability according to claim 2, characterized in that, The high inertia synchronous motor or the synchronous motor includes a stator, a rotor, a motor shaft, and bearings; The stator includes a stator core and a three-phase armature winding that is uniformly slotted in the stator core; the rotor includes a rotor core and a single-phase excitation winding; the rotor core is a salient pole rotor or a non-salient pole rotor, and the single-phase excitation winding is placed in a slot on the surface of the salient pole rotor or on the magnetic pole of the non-salient pole rotor. The motor shaft connects the rotor to the prime mover, or the motor shaft connects the rotor to the load; the bearing is used to support the motor shaft.

4. The synchronous motor system with high inertia and stable support and control capability according to claim 3, characterized in that, When the synchronous motor is installed horizontally, the bearing is a magnetic levitation bearing; When the synchronous motor is installed vertically, the bearing is a magnetic levitation bearing and the flywheel is a magnetic levitation flywheel.

5. An excitation control method, characterized in that, The excitation control method, which operates in the synchronous motor system with high inertia and stable support control capability as described in any one of claims 1-4, comprises: When the grid frequency fluctuates, a compensation transfer function is pre-designed. The compensation transfer function is multiplied by the transfer function of the high-inertia synchronous motor itself to obtain a new transfer function. The signal obtained by multiplying the current DC excitation current by the new transfer function is used as the excitation control signal to control the adaptive change of the power angle of the high-inertia synchronous motor, thereby controlling the change of the torque of the high-inertia synchronous motor. This ensures that the active power output by the high-inertia synchronous motor at a constant speed under power generation or motoring conditions meets the grid demand, thus achieving stable support for the grid frequency. The design process of the compensation transfer function includes: Based on the speed and power of the high-inertia synchronous motor, the time-domain signal of the motor torque is obtained; the time-domain signal of the motor torque is then converted into a frequency-domain signal. The frequency domain signal is multiplied by a preset compensation transfer function to obtain the output signal; wherein the preset compensation transfer function is composed of one or more preset series-connected lead or lag transfer function units. The phase of the output signal is compared with the phase of the power grid frequency to obtain the phase difference deviation, wherein the sign of the phase deviation depends on the current state of the high-inertia synchronous motor; based on the phase deviation, the parameters of the preset compensation transfer function are adjusted so that the phase deviation approaches 0, thereby obtaining the designed compensation transfer function.

6. The excitation control method according to claim 5, characterized in that, Also includes: When the grid voltage fluctuates, the DC excitation current is adjusted to change the induced electromotive force of the high-inertia synchronous motor, so that the reactive power output by the high-inertia synchronous motor at a constant speed under power generation or motoring conditions meets the grid demand, thereby achieving stable support for the grid voltage.

7. The excitation control method according to claim 6, characterized in that, The grid voltage fluctuations include grid voltage drops or grid voltage increases; When the grid voltage drops, the DC excitation current is increased according to the motor excitation characteristic curve to enhance the induced electromotive force. This allows the high-inertia synchronous motor to send inductive reactive power to the grid while reducing its power angle, thus providing stable support for the grid voltage. When the grid voltage rises, the DC excitation current is reduced according to the motor excitation characteristic curve to reduce the induced electromotive force. Then, under the premise of increasing the power angle of the high-inertia synchronous motor, inductive reactive power is absorbed from the grid to achieve stable support for the grid voltage.

8. An excitation control system, characterized in that, Includes computer-readable storage media and processors; The computer-readable storage medium is used to store executable instructions; The processor is used to read executable instructions stored in the computer-readable storage medium and execute the excitation control method according to any one of claims 5-7.

9. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the program is executed by the processor, it implements the excitation control method as described in any one of claims 5-7.

10. A computer program product, characterized in that, Includes a computer program that, when run on a computer, causes the computer to perform the excitation control method according to any one of claims 5-7.

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