A power output grading response control method for full-power variable-speed pumped storage

Abstract

This application relates to a graded response control method for full-power variable-speed pumped storage. The method includes: first, acquiring the real-time DC voltage; if the real-time DC voltage does not deviate from the rated value, the capacitor provides priority support; otherwise, the DC voltage deviation is calculated. Then, if the DC voltage deviation falls within the soft-constraint transition stage range, the capacitor provides primary support, with the rotor gradually providing active power support. Finally, if the DC voltage deviation exceeds the upper limit of the soft-constraint transition stage range or the DC voltage change rate exceeds the limit, the rotor rapidly outputs power to restore the DC voltage. Through graded triggering and hysteresis design with clearly defined thresholds, the response is only activated when the DC voltage exceeds the limit. q The shaft current adjusts the electromagnetic torque, thereby mobilizing the rotor's kinetic energy. Minor daily disturbances do not trigger machine-side actions. This significantly reduces the frequency of electromagnetic torque fine-tuning under high-frequency minor disturbances, lowers the superposition effect of shaft torsional vibration and hydraulic pulsation, and helps reduce damage to mechanical structures such as the rotor and speed governor.

Description

Technical Field

[0001] This application relates to the fields of pumped storage and active power graded response technology, and in particular to a method for output graded response control of full-power variable speed pumped storage. Background Technology

[0002] As the penetration rate of renewable energy sources such as wind power and photovoltaics in the power system continues to increase, the system's equivalent inertia and short-circuit capacity have decreased significantly. Against this backdrop, when the power system faces small disturbances (such as frequency deviations of ±0.05Hz to ±0.2Hz, bus voltage fluctuations of ±1% to ±3%, and random load / output fluctuations of hundreds of milliseconds to several seconds), the system's voltage, frequency, and power flow characteristics exhibit more sensitive and rapid change characteristics.

[0003] To ensure power quality and operational safety in power systems, there is an urgent need for flexible and controllable resources capable of providing power support on a millisecond to hundreds of millisecond timescale. Among these, full-power variable-speed pumped-storage units, as a promising flexible and controllable frequency regulation resource suitable for large-scale application, have gained widespread industry recognition. These units employ a back-to-back full-power converter topology (including the generator-side converter MSC and the grid-side converter GSC) and a DC-link capacitor. Theoretically, they possess a wide speed and power regulation range, excellent power ramping and tracking performance, and can provide active and reactive power support to the power system in both the generation and pumping quadrants.

[0004] Despite the theoretical advantages of full-power variable-speed pumped storage units, existing control strategies still suffer from several key technical shortcomings in practical applications. Traditional control strategies require frequent adjustments to the electromagnetic torque even under small disturbances; high-frequency, small-amplitude torque fluctuations can easily trigger shaft torsional vibration, which, combined with hydraulic excitation, leads to accumulated fatigue damage to critical mechanical components such as bearings and couplings, significantly increasing maintenance costs. Furthermore, while DC-link capacitors have a natural advantage in transient energy buffering, absorbing and releasing energy on a millisecond timescale, in practical engineering applications, they are often used only to maintain DC-side voltage stability, with insufficient active allocation and utilization of their short-term energy storage, failing to fully realize their energy regulation potential.

[0005] Furthermore, existing control strategies fail to clearly define the boundary conditions for DC-link capacitor energy utilization and rotor participation in regulation, which can easily lead to over- or under-response of the unit to system disturbances. Over-response will exacerbate the wear and tear on mechanical components, while under-response will fail to guarantee the frequency and voltage quality of the power system, ultimately causing a double adverse impact on the unit's service life and the stability of system operation.

[0006] Based on the aforementioned shortcomings of existing technologies, without altering the hardware structure of the full-power variable-speed pumped storage unit, there is an urgent need to develop a coordinated control strategy for DC-link capacitor energy and rotor kinetic energy suitable for low-disturbance operating conditions. This strategy aims to achieve the following objectives: fully utilize the transient energy regulation function of the DC-link capacitor, reduce fatigue losses of the unit's mechanical components, ensure stable power quality in the power system, and balance the unit's operating efficiency and service life.

[0007] Therefore, in related technologies, there is an urgent need for a coordinated control strategy for DC capacitor energy and rotor kinetic energy under small disturbance conditions, which can give full play to the transient energy regulation function of DC-link capacitor, reduce fatigue loss of unit mechanical components, ensure stable power quality of power system, and take into account the operating efficiency and service life of unit. Summary of the Invention

[0008] Therefore, it is necessary to provide a power output graded response control method for full-power variable speed pumped storage to address the aforementioned technical problems.

[0009] In a first aspect, this application provides a method for output-level response control of full-power variable-speed pumped storage. The method includes: Obtain the real-time DC voltage. If the real-time DC voltage does not deviate from the rated value, the capacitor will provide priority support; otherwise, calculate the DC voltage deviation. If the DC voltage deviation falls within the soft-constraint transition phase, the capacitor will provide the main support, while the rotor will gradually provide active power support. If the DC voltage deviation exceeds the upper limit of the soft constraint transition stage or the DC voltage change rate exceeds the limit, the DC voltage will be restored by the rotor output power quickly.

[0010] Optionally, in one embodiment of this application, the capacitor preferential support includes: The dynamic modulation of the grid-side converter's active / reactive output enables the capacitor to provide / absorb energy in a short period of time.

[0011] Optionally, in one embodiment of this application, the step of having the capacitor as the main support and the rotor gradually providing active power support includes: A DC voltage control loop is added outside the q-axis current control loop to generate a q-axis current reference value; Change the q-axis current reference value to access the rotor kinetic energy.

[0012] Optionally, in one embodiment of this application, the q-axis current reference value is expressed as:

[0013] in, This is the reference value for the q-axis current. This represents the q-axis current value in steady state. , These are virtual inertia and damping coefficient, respectively. For real-time DC voltage, the top label is " " represents the differential of the variable, This is the DC voltage reference value. The reference generated by the DC voltage control circuit q Axis current increment.

[0014] Optionally, in one embodiment of this application, when changing the q-axis current reference value to invoke rotor kinetic energy, Represented as:

[0015] in, Indicates the gain coefficient. This is the DC voltage deviation. and This refers to the scope of the soft constraint transition phase.

[0016] Optionally, in one embodiment of this application, the rapid recovery of DC voltage by rotor output includes: Rapid control by a PI controller is represented as:

[0017] in, and These represent the proportional and integral coefficients of the PI controller, respectively.

[0018] Secondly, this application also provides a power output graded response control system for full-power variable-speed pumped storage, characterized in that the system comprises: The disturbance monitoring and signal shaping unit is used to monitor disturbances, acquire signals, and use first-order or second-order filters to obtain smoothing criteria and suppress measurement noise. DC link capacitor priority support unit, used to achieve priority support based on capacitor energy; A dual threshold and hysteresis discrimination unit is used to set upper and lower thresholds and superimpose voltage change rate criteria. The rotor kinetic energy retrieval unit is used to adjust the electromagnetic torque of the machine-side converter and retrieve rotor kinetic energy when the criteria meet the rotor kinetic energy entry conditions. When the disturbance ends or the DC link voltage is lower than the threshold, it gradually returns to the capacitor-priority operating point. The parameter adaptive tuning unit is used to tune the threshold and time constant online based on system inertia, short-circuit capacity and real-time operating conditions.

[0019] The aforementioned graded response control method for full-power variable-speed pumped storage hydroelectric power generation first acquires the real-time DC voltage. If the real-time DC voltage does not deviate from the rated value, the capacitor provides priority support; otherwise, the DC voltage deviation is calculated. Then, if the DC voltage deviation falls within the soft-constraint transition stage range, the capacitor provides primary support, with the rotor gradually providing active power support. Finally, if the DC voltage deviation exceeds the upper limit of the soft-constraint transition stage range or the DC voltage change rate exceeds the limit, the rotor rapidly outputs power to restore the DC voltage. In other words, through graded triggering and hysteresis design with clearly defined thresholds, the response is only activated when the DC voltage exceeds the limit. q The shaft current adjusts the electromagnetic torque, thereby mobilizing the rotor's kinetic energy. Minor daily disturbances do not trigger machine-side actions. This significantly reduces the frequency of electromagnetic torque fine-tuning under high-frequency, minor disturbances, lowering the superposition effect of shaft torsional vibration and hydraulic pulsation, thus reducing damage to the rotor, governor, and other mechanical structures. Since rotor-side actions are only initiated when necessary, maintenance intervals can be extended, the probability of unplanned downtime decreases, the unit's equivalent availability increases, and the total life-cycle cost decreases accordingly. Furthermore, it can actively utilize capacitors as energy buffers, resulting in more optimized energy distribution. First, within the safe range of DC voltage, disturbance energy is preferentially absorbed by capacitors, resolving small-energy, short-duration events on the DC side and preventing all disturbances from being transmitted to the motor / hydraulic side. Second, a "soft pullback" is used when approaching a threshold, and after exceeding the threshold, the PI controller is activated to access rotor kinetic energy, forming a two-stage buffer. Finally, virtual inertia and damping coefficients are introduced when capacitors absorb disturbances, pre-emptively accessing a small portion of rotor energy for preheating, further preventing sudden changes in rotor-side torque. This method only requires the converter on the machine side. q An improved DC voltage controller is added to the outer layer of the shaft current circuit, while the inner current decoupling and PWM remain unchanged. The grid-side converter maintains active power droop control without requiring any changes to the control method. Furthermore, the main circuitry and sensor layout are not altered, making it a purely software-based incremental approach; parameters can be quickly tuned through offline simulation and small-signal testing. Therefore, the control method proposed in this invention requires minimal system modifications and is easy to implement. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the division of control functions in one embodiment; Figure 2 This is a flowchart illustrating a power output graded response control method for full-power variable-speed pumped storage in one embodiment. Figure 3 This is a schematic diagram of the overall control structure in one embodiment; Figure 4 This is a schematic diagram of a DC voltage control and coordinated power output scheme in one embodiment. Figure 5 This is a schematic diagram of the output graded response control system for full-power variable speed pumped storage in one embodiment. Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0022] In one embodiment, generally speaking, for a single-unit grid-connected converter system, DC voltage and active power are two electrical quantities that must be effectively controlled at both the generator-side and grid-side converters. To achieve the capacitor-priority—threshold discrimination—rotor relay technical approach during small disturbances, active power control must be implemented at the grid-side converter, and DC voltage control at the generator-side converter. On the one hand, implementing active power control at the grid allows the grid-connected converter to support grid-side active power changes, quickly providing active support for grid frequency. On the other hand, controlling DC voltage at the generator-side converter is beneficial for the coordinated energy control of the DC capacitor and rotor. If DC voltage control is implemented at the grid-side converter and active power control at the generator-side converter, it is not only detrimental to the coordinated control of DC capacitor energy and rotor kinetic energy but also leads to insufficient active power support under grid-side disturbances. Therefore, this application chooses to implement active power control at the grid-side converter and DC voltage control at the generator-side converter, with the control division of labor as follows: Figure 1 As shown. The grid-side converter can be controlled using conventional active power synchronization control, such as droop control or virtual synchronous machine control, to achieve active power support under small grid-side disturbances. The generator-side converter control utilizes the capacitor priority-threshold discrimination-rotor relay active power output coordination method of this application to control the DC voltage. Capacitor energy can be directly accessed. Threshold discrimination can be directly completed through detection and judgment templates. When accessing rotor kinetic energy in generator-side control, it is generally achieved by adjusting... q The electromagnetic torque is adjusted by the shaft current, as shown in the following formula:

[0023] in, Indicates electromagnetic torque; Represents the extreme logarithm. Indicates stator flux linkage. , Indicates the stator current at dq Components in coordinate system and This represents the direct-axis / quadrature-axis equivalent inductance. In a conventional vector control structure, a reference value is typically used. Therefore, the electromagnetic torque is proportional to... ,adjust q The electromagnetic torque can be adjusted by changing the shaft current. When using the reference value, the machine-side converter converts the actual value on a millisecond-scale timescale. Once the reference value is reached, the electromagnetic torque changes accordingly.

[0024] According to the rotor rocking equation:

[0025] in, Indicates the rotor's kinetic energy. Represents the equivalent moment of inertia. Indicates the rotor angular velocity. and Represents mechanical power and electromagnetic power. This indicates mechanical torque.

[0026] When a small disturbance occurs in the system, and the turbine-side converter needs to increase the electromagnetic torque to obtain rotor energy, the mechanical torque input to the turbine may be affected due to the governor's slow dynamic response or the existence of a dead zone. The ratio can be considered to change, i.e., remain constant. At this point, the electromagnetic torque is greater than the mechanical torque, and the rotor rotates... Decrease, rotor kinetic energy Extracted and converted into electrical power Conversely, reduce The electric power is then sent to the rotor and stored as kinetic energy.

[0027] In one embodiment, such as Figure 2 As shown, a power output graded response control method for full-power variable-speed pumped storage is provided, comprising the following steps: S101: Obtain the real-time DC voltage. If the real-time DC voltage does not deviate from the rated value, the capacitor will provide priority support; otherwise, calculate the DC voltage deviation.

[0028] In this embodiment, the energy of the capacitor on the DC-link is directly related to the DC voltage. To utilize the energy in the capacitor without damaging the system, the fluctuation range of the DC voltage needs to be limited. The detected DC bus voltage... As a judgment signal, the control process is divided into three stages: capacitor support stage, soft constraint transition stage, and rotor support stage. Taking the converter providing active power support to the grid as an example, a normalized DC voltage deviation is defined. :

[0029] in, Positive representation Below the reference value This means that the capacitor's energy is utilized to support capacitor disturbances. (Settings) and This refers to the scope of the soft-constraint transition phase. Take 3%-5% of the rated DC voltage. The higher the value, the less rotor involvement; the lower the value, the smaller the allowable capacitance fluctuation. Take 90% of the rated DC voltage to form a soft constraint transition zone to prevent sudden changes in rotor torque.

[0030] The goal of the capacitor-supported stage is to prioritize capacitor support over rotor kinetic energy during disturbances. Under small disturbances, the active power change is still primarily supported by the DC capacitor. The capacitor-supported stage satisfies the following:

[0031] At this time, under active power droop control, the grid-side converter utilizes energy from the DC capacitor to provide active power support to the grid, resulting in a decrease in DC voltage but not exceeding the threshold. The generator-side converter, due to... q The shaft current remains almost constant, the electromagnetic torque remains constant, and the rotor kinetic energy is not utilized.

[0032] In one embodiment of this application, the capacitor preferential support includes: The dynamic modulation of the grid-side converter's active / reactive output enables the capacitor to provide / absorb energy in a short period of time.

[0033] In one embodiment of this application, the active / reactive power output of the dynamically modulated grid-side converter (GSC) enables the capacitor to provide / absorb energy in a short time, quickly offsetting the power shortfall caused by small disturbances. The principle of prioritizing support based on capacitor energy is expressed as follows:

[0034] in, The energy stored in the capacitor. Indicates the capacitance. This represents the voltage across the capacitor.

[0035] S102: If the DC voltage deviation falls within the range of the soft constraint transition stage, the capacitor will provide the main support, and the rotor will gradually provide active power support.

[0036] In this embodiment of the application, when the disturbance is large or lasts for a long time, the DC voltage It may exceed the threshold, potentially requiring the rotor to provide active power support. The purpose of this stage is to... Approaching the boundary of the soft-constraint transition stage, rotor energy gradually and incrementally intervenes to provide power support, playing a mild traction role and avoiding sudden changes in rotor torque. During this stage, the capacitor remains dominant while minimizing vibration and sudden changes. This stage requires gradual rotor intervention and an increase in the q-axis current to utilize rotor kinetic energy. The soft-constraint transition stage satisfies the following:

[0037] In one embodiment of this application, the step of having the capacitor as the primary support and the rotor gradually providing active power support includes: A DC voltage control loop is added outside the q-axis current control loop to generate a q-axis current reference value; Change the q-axis current reference value to access the rotor kinetic energy.

[0038] In one embodiment of this application, by q To generate a DC voltage control loop outside the shaft current control loop. q The shaft current reference value allows the DC voltage energy and rotor energy to be correlated in the system, and the overall control structure is as follows: Figure 3 As shown. This application designs a new DC voltage control loop that allows the DC voltage to fluctuate within a certain range. In other words, if it exceeds the range, it is controlled to track a reference value. q The shaft current is increased or decreased to utilize the rotor's kinetic energy, and DC voltage variations are permitted as long as they do not exceed the specified range. q The shaft current remains constant. Existing control structures primarily use a PID controller to directly track the DC voltage reference value, but this method of achieving rapid tracking does not utilize the energy of the DC capacitor. In this embodiment, unlike the traditional method where the DC voltage is controlled to track the reference value at the initial fluctuation, a capacitor-priority—threshold discrimination—rotor relay active power coordination method is implemented. A schematic diagram is shown below. Figure 4 As shown.

[0039] use q The external DC voltage control circuit generates a reference q-axis current. In steady state, q The shaft current is a constant value When a disturbance occurs and a rotor kinetic energy response is required, change In order to achieve the purpose of adjusting the electromagnetic torque, therefore, It can be described as:

[0040] in, When in steady state q The value of the shaft current, This is the reference generated by the DC voltage control circuit. q Shaft current increment. To suppress the rate of change of DC voltage under small disturbances, improve the outer loop phase / gain margin, thereby avoiding sudden rotor surges and suppressing torque shocks, the DC link voltage is... U dc The change is equivalent to an angular velocity deviation, introducing virtual inertia and damping terms. Based on the virtual inertia and damping coefficient, the depth of rotor energy utilization during the capacitor-supported stage can be controlled. Furthermore, if rotor energy is not used, the virtual inertia and damping coefficient are set to 0.

[0041] Specifically, in one embodiment of this application, the q-axis current reference value is expressed as:

[0042] in, This is the reference value for the q-axis current. This represents the q-axis current value in steady state. , These are the virtual inertia and the damping coefficient, respectively, which are usually set to a minimum value to smooth out changes in rotor torque while preventing the capacitor energy from being unusable. For real-time DC voltage, the top label is " " represents the differential of the variable, This is the DC voltage reference value. The reference generated by the DC voltage control circuit q Axis current increment.

[0043] In one embodiment of this application, when the q-axis current reference value is changed to invoke rotor kinetic energy, Represented as:

[0044] in, This represents the gain coefficient; the larger the value, the stronger the pull near the band boundary. It can be quickly pulled back to the capacitor-supported stage, but requires more rotor kinetic energy; conversely, it is supported by the capacitor itself, but is more likely to exceed the threshold. To balance the transition of the rotor support stage and the abrupt reduction in rotor torque, a setting can be made. Make Approximately 15%.

[0045] S103: If the DC voltage deviation exceeds the upper limit of the soft constraint transition stage or the DC voltage change rate exceeds the limit, the DC voltage will be restored by the rotor output power quickly.

[0046] When the DC voltage exceeds the threshold To prevent the system from triggering DC link overvoltage protection due to excessive DC voltage drops, and even damaging capacitors, the rotor kinetic energy is required to provide strong active power support and boost the DC voltage to its rated value. Furthermore, to prevent rapid DC voltage changes caused by insufficient capacitor energy to effectively support large disturbances, a voltage change rate criterion is added at this stage. Therefore, the rotor support stage can be triggered as long as one of the following conditions is met:

[0047]

[0048] in, This represents the upper limit of the rate of change of DC voltage, usually taken as... During this stage, the rotor needs to quickly output power. The machine-side converter releases kinetic energy from the rotor by changing the electromagnetic torque to restore the DC voltage. .

[0049] In one embodiment of this application, the rapid recovery of DC voltage by rotor output includes: Rapid control by a PI controller is represented as:

[0050] in, and These represent the proportional and integral coefficients of the PI controller, respectively, which are directly related to active power support and DC voltage recovery. The larger the value, the faster the active power support and DC voltage recovery, and vice versa. They are adaptively tuned by a small signal.

[0051] In the aforementioned graded response control method for full-power variable-speed pumped storage, firstly, the real-time DC voltage is acquired. If the real-time DC voltage does not deviate from the rated value, the capacitor provides priority support; otherwise, the DC voltage deviation is calculated. Then, if the DC voltage deviation falls within the soft-constraint transition stage range, the capacitor provides primary support, with the rotor gradually providing active power support. Finally, if the DC voltage deviation exceeds the upper limit of the soft-constraint transition stage range or the DC voltage change rate exceeds the limit, the rotor rapidly outputs power to restore the DC voltage. In other words, through graded triggering and hysteresis design with clearly defined thresholds, the response is only activated when the DC voltage exceeds the limit. q The shaft current adjusts the electromagnetic torque, thereby mobilizing the rotor's kinetic energy. Minor daily disturbances do not trigger machine-side actions. This significantly reduces the frequency of electromagnetic torque fine-tuning under high-frequency, minor disturbances, lowering the superposition effect of shaft torsional vibration and hydraulic pulsation, thus reducing damage to the rotor, governor, and other mechanical structures. Since rotor-side actions are only initiated when necessary, maintenance intervals can be extended, the probability of unplanned downtime decreases, the unit's equivalent availability increases, and the total life-cycle cost decreases accordingly. Furthermore, it can actively utilize capacitors as energy buffers, resulting in more optimized energy distribution. First, within the safe range of DC voltage, disturbance energy is preferentially absorbed by capacitors, resolving small-energy, short-duration events on the DC side and preventing all disturbances from being transmitted to the motor / hydraulic side. Second, a "soft pullback" is used when approaching a threshold, and after exceeding the threshold, the PI controller is activated to access rotor kinetic energy, forming a two-stage buffer. Finally, virtual inertia and damping coefficients are introduced when capacitors absorb disturbances, pre-emptively accessing a small portion of rotor energy for preheating, further preventing sudden changes in rotor-side torque. This method only requires the converter on the machine side. qAn improved DC voltage controller is added to the outer layer of the shaft current circuit, while the inner current decoupling and PWM remain unchanged. The grid-side converter maintains active power droop control without requiring any changes to the control method. Furthermore, the main circuitry and sensor layout are not altered, making it a purely software-based incremental approach; parameters can be quickly tuned through offline simulation and small-signal testing. Therefore, the control method proposed in this invention requires minimal system modifications and is easy to implement.

[0052] It should be understood that although the steps in the flowcharts of the embodiments described above are shown sequentially according to the arrows, these steps are not necessarily executed in the order indicated by the arrows. Unless explicitly stated herein, there is no strict order restriction on the execution of these steps, and they can be executed in other orders. Moreover, at least some steps in the flowcharts of the embodiments described above may include multiple steps or multiple stages. These steps or stages are not necessarily completed at the same time, but can be executed at different times. The execution order of these steps or stages is not necessarily sequential, but can be performed alternately or in turn with other steps or at least some of the steps or stages of other steps.

[0053] Based on the same inventive concept, this application also provides an output-graded response control system for full-power variable-speed pumped hydro storage, which implements the aforementioned output-graded response control method for full-power variable-speed pumped hydro storage. The solution provided by this system is similar to the implementation described in the above method. Therefore, the specific limitations of one or more embodiments of the output-graded response control system for full-power variable-speed pumped hydro storage provided below can be found in the above-described limitations of the output-graded response control method for full-power variable-speed pumped hydro storage, and will not be repeated here.

[0054] In one embodiment, such as Figure 5 As shown, a power output graded response control system for full-power variable-speed pumped storage is provided, comprising: The disturbance monitoring and signal shaping unit is used to monitor disturbances, acquire signals, and use first-order or second-order filters to obtain smoothing criteria and suppress measurement noise.

[0055] DC link capacitor priority support unit, used to achieve priority support based on capacitor energy.

[0056] The dual threshold and hysteresis discrimination unit is used to set upper and lower thresholds and superimpose voltage change rate criteria.

[0057] The rotor kinetic energy retrieval unit is used to adjust the electromagnetic torque of the machine-side converter and retrieve rotor kinetic energy when the criteria for entering rotor kinetic energy are met. When the disturbance ends or the DC link voltage is lower than the threshold, it gradually returns to the capacitor-priority operating point.

[0058] The parameter adaptive tuning unit is used to tune the threshold and time constant online based on system inertia, short-circuit capacity and real-time operating conditions.

[0059] It should be noted that the user information (including but not limited to user device information, user personal information, etc.) and data (including but not limited to data used for analysis, data stored, data displayed, etc.) involved in this application are all information and data authorized by the user or fully authorized by all parties.

[0060] Those skilled in the art will understand that all or part of the processes in the above embodiments can be implemented by a computer program instructing related hardware. The computer program can be stored in a non-volatile computer-readable storage medium, and when executed, it can include the processes of the embodiments described above. Any references to memory, databases, or other media used in the embodiments provided in this application can include at least one of non-volatile and volatile memory. Non-volatile memory can include read-only memory (ROM), magnetic tape, floppy disk, flash memory, optical memory, high-density embedded non-volatile memory, resistive random access memory (ReRAM), magnetic random access memory (MRAM), ferroelectric random access memory (FRAM), phase change memory (PCM), graphene memory, etc. Volatile memory can include random access memory (RAM) or external cache memory, etc. By way of illustration and not limitation, RAM can take many forms, such as Static Random Access Memory (SRAM) or Dynamic Random Access Memory (DRAM). The databases involved in the embodiments provided in this application may include at least one type of relational database and non-relational database. Non-relational databases may include, but are not limited to, blockchain-based distributed databases. The processors involved in the embodiments provided in this application may be general-purpose processors, central processing units, graphics processing units, digital signal processors, programmable logic devices, quantum computing-based data processing logic devices, etc., and are not limited to these.

[0061] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0062] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of this application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this application should be determined by the appended claims.

Claims

1. A method for graded output response control of full-power variable-speed pumped storage, characterized in that, The method includes: Obtain the real-time DC voltage. If the real-time DC voltage does not deviate from the rated value, the capacitor will provide priority support; otherwise, calculate the DC voltage deviation. If the DC voltage deviation falls within the soft-constraint transition phase, the capacitor will provide the main support, while the rotor will gradually provide active power support. If the DC voltage deviation exceeds the upper limit of the soft constraint transition stage or the DC voltage change rate exceeds the limit, the DC voltage will be restored by the rotor output power quickly.

2. The output graded response control method for full-power variable-speed pumped storage as described in claim 1, characterized in that, The capacitor priority support includes: The dynamic modulation of the grid-side converter's active / reactive output enables the capacitor to provide / absorb energy in a short period of time.

3. The output graded response control method for full-power variable-speed pumped storage as described in claim 1, characterized in that, The system, primarily supported by capacitors and with the rotor gradually providing active power support, includes: A DC voltage control loop is added outside the q-axis current control loop to generate a q-axis current reference value; Change the q-axis current reference value to access the rotor kinetic energy.

4. The output graded response control method for full-power variable-speed pumped storage as described in claim 3, characterized in that, The q-axis current reference value is expressed as follows: in, This is the reference value for the q-axis current. This represents the q-axis current value in steady state. , These are virtual inertia and damping coefficient, respectively. For real-time DC voltage, top label " " represents the differential of the variable, This is the DC voltage reference value. The reference generated by the DC voltage control circuit q Axis current increment.

5. The output graded response control method for full-power variable-speed pumped storage as described in claim 4, characterized in that, When changing the q-axis current reference value to access rotor kinetic energy Represented as: in, Indicates the gain coefficient. This is the DC voltage deviation. and This refers to the scope of the soft constraint transition phase.

6. The output graded response control method for full-power variable-speed pumped storage as described in claim 4, characterized in that, The process of restoring DC voltage by rapid rotor output includes: Rapid control by a PI controller is represented as: in, and These represent the proportional and integral coefficients of the PI controller, respectively.

7. A power output graded response control system for full-power variable-speed pumped storage, characterized in that, The system includes: The disturbance monitoring and signal shaping unit is used to monitor disturbances, acquire signals, and use first-order or second-order filters to obtain smoothing criteria and suppress measurement noise. DC link capacitor priority support unit, used to achieve priority support based on capacitor energy; A dual threshold and hysteresis discrimination unit is used to set upper and lower thresholds and superimpose voltage change rate criteria. The rotor kinetic energy retrieval unit is used to adjust the electromagnetic torque of the machine-side converter and retrieve rotor kinetic energy when the criteria meet the rotor kinetic energy entry conditions. When the disturbance ends or the DC link voltage is lower than the threshold, it gradually returns to the capacitor-priority operating point. The parameter adaptive tuning unit is used to tune the threshold and time constant online based on system inertia, short-circuit capacity and real-time operating conditions.

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