Power grid frequency modulation method, device and equipment based on shared direct current bus and medium

Abstract

This application relates to a grid frequency regulation method, apparatus, device, and medium based on a shared DC bus. The method includes: acquiring grid frequency data of each grid connected to a target inverter device; determining, based on the grid frequency data of each grid, whether there is a grid with abnormal frequency in each grid; and, if an abnormal frequency grid is determined to exist, using the target inverter device to adjust the frequency of the abnormal frequency grid. The target inverter device includes one grid-connected inverter and at least two grid-connected inverters, which are connected via a shared DC bus. This method can improve the reliability of grid frequency regulation.

Description

Technical Field

[0001] This application relates to the field of power electronics technology, and in particular to a power grid frequency regulation method, apparatus, equipment and medium based on a shared DC bus. Background Technology

[0002] With the continuous development of renewable energy, high-power power electronic converters, and flexible power transmission and distribution technologies, the problem of grid frequency stability has become increasingly prominent, leading to the emergence of Virtual Synchronous Generator (VSG) technology. By simulating the rotor motion equations and electromagnetic characteristics of a synchronous generator, VSG enables grid-connected inverters to exhibit inertia and damping, thereby stabilizing the grid frequency.

[0003] However, when using the above method to adjust the grid frequency, each inverter operates independently based on local frequency measurements, lacking information exchange and coordination, which reduces the reliability of grid frequency regulation. Summary of the Invention

[0004] Therefore, it is necessary to provide a power grid frequency regulation method, apparatus, equipment, and medium based on a shared DC bus that can improve the reliability of power grid frequency regulation, addressing the aforementioned technical problems.

[0005] Firstly, this application provides a power grid frequency regulation method based on a shared DC bus, including:

[0006] Obtain grid frequency data of each grid to which the target inverter device is connected; wherein, the target inverter device includes one grid-connected inverter and at least two grid-connected inverters, and the grid-connected inverter and the grid-connected inverters are connected through a shared DC bus;

[0007] Based on the grid frequency data of each power grid, determine whether there are any power grids with abnormal frequencies in each power grid;

[0008] When a power grid with an abnormal frequency is identified, a target inverter device is used to adjust the frequency of the power grid with the abnormal frequency.

[0009] In one embodiment, a target inverter device is used to adjust the frequency of a grid with abnormal frequency, including:

[0010] When a grid-connected inverter is connected to a grid with abnormal frequency, the grid-connected inverter is controlled to transmit active power to the grid with abnormal frequency through a shared DC bus.

[0011] When a grid-connected inverter is connected to a grid-connected power grid with abnormal frequency, the grid-connected inverter in the target inverter equipment is used to adjust the frequency of the grid with abnormal frequency based on the abnormal frequency value of the grid.

[0012] In one embodiment, based on the frequency anomaly value of the frequency-abnormal power grid, a grid-connected inverter in the target inverter device is used to adjust the frequency of the frequency-abnormal power grid, including:

[0013] When the frequency anomaly value of the frequency-abnormal power grid is less than the anomaly threshold, the grid-type inverter connected to the frequency-abnormal power grid is used to adjust the frequency of the frequency-abnormal power grid.

[0014] When the frequency anomaly value is greater than or equal to the anomaly threshold, based on the virtual inertia of each grid-type inverter, the grid-type inverter is controlled to adjust the frequency of the abnormal grid through a shared DC bus.

[0015] In one embodiment, based on the virtual inertia of each grid-type inverter, the grid-type inverters are controlled to adjust the frequency of the abnormal grid through a shared DC bus, including:

[0016] With the virtual inertia of each grid-type inverter being consistent, each grid-type inverter is simultaneously controlled to adjust the frequency of the abnormal grid through a shared DC bus.

[0017] When the virtual inertia of each grid-type inverter is inconsistent, the output sequence of each grid-type inverter is determined according to the relationship between the virtual inertia of each grid-type inverter. Based on the output sequence, each grid-type inverter is controlled to adjust the frequency of the grid with abnormal frequency by sharing a DC bus.

[0018] In one embodiment, the method further includes:

[0019] If it is determined that there is no abnormal frequency power grid, obtain the current bus voltage of the shared DC bus;

[0020] Determine the bus adjustment parameters for the shared DC bus based on the voltage deviation between the current bus voltage and the rated bus voltage;

[0021] Based on the bus adjustment parameters, the grid-type inverter is controlled to adjust the voltage of the shared DC bus.

[0022] In one embodiment, the method further includes:

[0023] If it is determined that there is no abnormal frequency grid, stop the frequency control operation on the grid-connected inverter and allocate the computing resources of the grid-connected inverter to the harmonic processing tasks associated with the grid-connected inverter.

[0024] Secondly, this application also provides a power grid frequency regulation device based on a shared DC bus, comprising:

[0025] The data acquisition module is used to acquire the grid frequency data of each grid to which the target inverter device is connected; wherein, the target inverter device includes one grid-connected inverter and at least two grid-connected inverters, and the grid-connected inverter and the grid-connected inverters are connected through a shared DC bus;

[0026] The anomaly detection module is used to determine whether there are any power grids with abnormal frequencies in each power grid based on the power grid frequency data of each power grid.

[0027] The frequency adjustment module is used to adjust the frequency of a grid with an abnormal frequency by using a target inverter device when an abnormal frequency is detected.

[0028] Thirdly, this application also provides a computer device, including a memory and a processor, wherein the memory stores a computer program, and the processor executes the computer program to perform the following steps:

[0029] Obtain grid frequency data of each grid to which the target inverter device is connected; wherein, the target inverter device includes one grid-connected inverter and at least two grid-connected inverters, and the grid-connected inverter and the grid-connected inverters are connected through a shared DC bus;

[0030] Based on the grid frequency data of each power grid, determine whether there are any power grids with abnormal frequencies in each power grid;

[0031] When a power grid with an abnormal frequency is identified, a target inverter device is used to adjust the frequency of the power grid with the abnormal frequency.

[0032] Fourthly, this application also provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, performs the following steps:

[0033] Obtain grid frequency data of each grid to which the target inverter device is connected; wherein, the target inverter device includes one grid-connected inverter and at least two grid-connected inverters, and the grid-connected inverter and the grid-connected inverters are connected through a shared DC bus;

[0034] Based on the grid frequency data of each power grid, determine whether there are any power grids with abnormal frequencies in each power grid;

[0035] When a power grid with an abnormal frequency is identified, a target inverter device is used to adjust the frequency of the power grid with the abnormal frequency.

[0036] Fifthly, this application also provides a computer program product, including a computer program that, when executed by a processor, performs the following steps:

[0037] Obtain grid frequency data of each grid to which the target inverter device is connected; wherein, the target inverter device includes one grid-connected inverter and at least two grid-connected inverters, and the grid-connected inverter and the grid-connected inverters are connected through a shared DC bus;

[0038] Based on the grid frequency data of each power grid, determine whether there are any power grids with abnormal frequencies in each power grid;

[0039] When a power grid with an abnormal frequency is identified, a target inverter device is used to adjust the frequency of the power grid with the abnormal frequency.

[0040] The aforementioned grid frequency regulation method, apparatus, equipment, and medium based on a shared DC bus introduce a target inverter device comprising one grid-connected inverter and at least two grid-connected inverters, connected via a shared DC bus. By acquiring grid frequency data from each grid connected to the target inverter device, and determining whether any grids exhibit frequency anomalies based on this data, the target inverter device is used to adjust the frequency of the affected grids. Compared to related technologies where each inverter operates independently based solely on local frequency measurements, this method, using inverters connected via a shared DC bus to adjust the frequency of grids with frequency anomalies, enables coordinated control among the inverters, thereby ensuring the reliability of grid frequency regulation. Attached Figure Description

[0041] To more clearly illustrate the technical solutions in the embodiments of this application or related technologies, the drawings used in the description of the embodiments of this application or related technologies will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0042] Figure 1 This is a flowchart illustrating a power grid frequency regulation method based on a shared DC bus in one embodiment;

[0043] Figure 2 This is a schematic diagram of the target inverter device in one embodiment;

[0044] Figure 3 This is a schematic diagram of VSG control in one embodiment;

[0045] Figure 4 This is a schematic diagram of the power grid frequency waveform in one embodiment;

[0046] Figure 5 This is a schematic diagram of the power support of the VSG in one embodiment;

[0047] Figure 6 This is a schematic diagram of the power grid frequency waveform in another embodiment;

[0048] Figure 7 This is a schematic diagram of the voltage adjustment process in one embodiment;

[0049] Figure 8 This is a schematic diagram of the operating mode of the target inverter device in one embodiment;

[0050] Figure 9 This is a schematic diagram of harmonic processing in one embodiment;

[0051] Figure 10 This is a schematic diagram of the harmonic mitigation function in one embodiment;

[0052] Figure 11 This is a flowchart illustrating a power grid frequency regulation method based on a shared DC bus in another embodiment;

[0053] Figure 12 This is a structural block diagram of a power grid frequency regulation device based on a shared DC bus in one embodiment;

[0054] Figure 13 This is an internal structural diagram of a computer device in one embodiment. Detailed Implementation

[0055] 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.

[0056] With the continuous development of renewable energy, high-power power electronic converters, and flexible power transmission and distribution technologies, the problem of grid frequency stability has become increasingly prominent, leading to the emergence of VSG technology. VSG simulates the rotor motion equations and electromagnetic characteristics of synchronous generators, enabling grid-connected inverters to exhibit inertia and damping, thereby stabilizing the grid frequency.

[0057] However, when using the above method to adjust the grid frequency, each inverter operates independently based on local frequency measurements, lacking information exchange and coordination, which reduces the reliability of grid frequency regulation.

[0058] Based on this, in an exemplary embodiment, a power grid frequency regulation method based on a shared DC bus is provided. The method is illustrated using an application to a server as an example. Figure 1 As shown, the specific steps include:

[0059] S101, Obtain the grid frequency data of each power grid to which the target inverter device is connected.

[0060] The so-called grid frequency data refers to the frequency data of the power grid, which may include, but is not limited to, the current grid frequency and historical grid frequencies. The target inverter equipment includes one grid-connected inverter and at least two grid-connected inverters, connected via a shared DC bus. Furthermore, the grid-connected inverter is an inverter based on phase-locked loop (PLL) technology, connected to the strong grid; the grid-connected inverter is an inverter based on VSG, connected to the weak grid. The strong and weak grids can be determined by the short-circuit ratio.

[0061] It is worth noting that the three inverters in the target inverter system share the same DC-side capacitor, while their AC sides are connected to their respective power grids. This topology achieves dynamic cross-regional energy and inertia mutual support through a shared DC bus, enabling grid-connected inverters connected to strong grids to provide stable power buffers for weak grids. At the same time, VSG-connected inverters on the weak grid side can also use their virtual inertia to provide frequency support for the strong grid through coordinated control, thus constructing a win-win operating paradigm.

[0062] For example, you can refer to Figure 2 The schematic diagram of the target inverter device shown is shown, where C dk This is the DC-side capacitor. The target inverter equipment includes grid-connected inverters VSG-1 and VSG-2, and a grid-connected inverter PLL-1, wherein VSG-1, VSG-2 and PLL-1 are connected via a shared DC bus.

[0063] Optionally, during grid operation, the grid frequency data of each grid to which the target inverter device is connected can be obtained in real time through frequency acquisition devices deployed in each grid.

[0064] S102, Based on the grid frequency data of each grid, determine whether there are any grids with abnormal frequencies in each grid.

[0065] Among them, the so-called frequency abnormal power grid is a power grid in which the frequency is abnormal.

[0066] In one alternative implementation, for each power grid to which the target inverter device is connected, it can be determined whether the power grid is a frequency-abnormal grid based on the difference between the frequency deviation between the current grid frequency and the rated frequency and a deviation threshold. The deviation threshold can be determined by those skilled in the art based on historical experience or by a large number of experiments; there is no limitation on this.

[0067] For example, if the frequency deviation of the power grid is greater than the deviation threshold, the power grid is determined to be a frequency abnormal power grid; if the frequency deviation of the power grid is less than or equal to the deviation threshold, the power grid is determined to be a frequency normal power grid.

[0068] In another alternative implementation, for each power grid connected to the target inverter device, the frequency change rate of the power grid can be determined based on the historical and current power grid frequencies. Then, based on the difference between the frequency change rate and a change rate threshold, it can be determined whether the power grid is a frequency-abnormal grid. The change rate threshold can be determined by those skilled in the art based on historical experience or by a large number of experiments; there is no limitation on this.

[0069] For example, if the frequency change rate of the power grid is greater than the change rate threshold, the power grid is determined to be a frequency abnormal power grid; if the frequency change rate of the power grid is less than or equal to the change rate threshold, the power grid is determined to be a frequency normal power grid.

[0070] S103, if it is determined that there is a frequency abnormality in the power grid, the target inverter equipment is used to adjust the frequency of the frequency abnormality in the power grid.

[0071] In one alternative implementation, if an abnormal frequency grid is identified, and the target inverter connected to the abnormal frequency grid is a grid-connected inverter, frequency adjustment of the abnormal frequency grid can be performed using only the target inverter, based on the cause of the abnormality. The cause of the abnormality may include, but is not limited to, active power deficit and active power surplus.

[0072] For example, when there is an active power deficit in the power grid with an abnormal frequency, the target inverter can continuously increase the active power supplied to the power grid with an abnormal frequency, thereby gradually pulling the frequency back to the rated frequency range. When there is an active power surplus in the power grid with an abnormal frequency, the target inverter can absorb active power from the power grid with an abnormal frequency, thereby gradually pulling the frequency back to the rated frequency range.

[0073] In another alternative implementation, the frequency of the abnormal power grid can be adjusted simultaneously using each inverter in the target inverter equipment, based on the cause of the abnormality.

[0074] For example, in the event of an active power deficit in a frequency-abnormal power grid, the target inverter can directly and continuously generate active power to the frequency-abnormal power grid, and other inverters can also continuously generate active power to the frequency-abnormal power grid through the shared DC bus in the target inverter, thereby gradually pulling the frequency back to the rated frequency range. Here, "other inverters" refers to the grid-connected inverters in the target inverter equipment other than the target inverter itself.

[0075] In the aforementioned grid frequency regulation method based on a shared DC bus, the target inverter equipment includes one grid-connected inverter and at least two grid-connected inverters, which are connected via a shared DC bus. By acquiring the grid frequency data of each grid connected to the target inverter equipment, and based on this data, it is determined whether any grids exhibit frequency anomalies exist. Then, if a frequency anomaly is identified, the target inverter equipment is used to adjust the frequency of that grid. Compared to related technologies where each inverter operates independently based solely on local frequency measurements, using inverters connected via a shared DC bus to adjust the frequency of grids with frequency anomalies enables coordinated control among the inverters, thereby ensuring the reliability of grid frequency regulation.

[0076] Based on the above embodiments, this application provides an optional frequency adjustment method, specifically, when a grid-connected inverter is connected to a grid with abnormal frequency, the grid-connected inverter is controlled to transmit active power to the grid with abnormal frequency through a shared DC bus; when a grid-connected inverter is connected to a grid with abnormal frequency, the grid-connected inverter in the target inverter device is used to adjust the frequency of the grid with abnormal frequency according to the abnormal frequency value of the grid with abnormal frequency.

[0077] Among them, the so-called frequency anomaly value is a value that can characterize the frequency anomaly situation in the power grid.

[0078] It is worth noting that since the grid-connected inverter PLL itself does not have any active frequency regulation control loop, it cannot directly change the grid frequency. Therefore, when a grid-connected inverter is connected to a grid with an abnormal frequency, the grid-connected inverter cannot directly transmit active power to the grid with the abnormal frequency. It is necessary to control the grid-connected inverter in the target inverter equipment to transmit active power to the grid with the abnormal frequency through a shared DC bus, thereby gradually pulling the frequency back to the rated frequency range.

[0079] In another alternative implementation, when a grid-connected inverter is connected to a grid with an abnormal frequency, the abnormal frequency value can be determined first based on the grid frequency data. For example, a preset adjustment weight can be used to adjust the frequency deviation between the current grid frequency and the rated frequency to obtain the abnormal frequency value.

[0080] Furthermore, based on the frequency anomaly value, it can be determined whether multiple grid-connected inverters are needed to simultaneously adjust the frequency of the grid with the frequency anomaly. If so, multiple grid-connected inverters are used based on a shared DC bus to simultaneously adjust the frequency of the grid with the frequency anomaly; if not, only the grid-connected inverter connected to the grid with the frequency anomaly is used to adjust the frequency of the grid with the frequency anomaly.

[0081] Understandably, reference Figure 3 The diagram shows a VSG control system. First, determine the power deviation between the actual output power and the set power at the input terminal. Then, based on the rated angular frequency ω0, the power deviation is converted into a torque deviation, thus converting the power signal into a torque signal. Afterwards, the middle branch J represents the moment of inertia (virtual correlation), and the lower branch D represents the damping coefficient, which suppresses power oscillations. The upper branch k... f This is the droop coefficient, corresponding to the droop characteristic of primary frequency modulation, enabling a steady-state relationship where "the frequency decreases by the same amount as the power change." Angular velocity deviation can be output through three-way coordination. The actual angular velocity ω is obtained by superimposing the angular velocity deviation with the rated angular frequency ω0 (it is worth noting that, in the simplified model, the rated angular frequency can be equivalent to the rated angular velocity).

[0082] Furthermore, the actual angular velocity ω is integrated (1 / s) to obtain the phase angle θ of the virtual electromotive force; then, it is processed through the power feedback closed-loop module E0U / X. f Based on the phase difference θ, virtual electromotive force, grid voltage, and reactance, calculate the actual output electromagnetic power P. e Where E0 is the virtual electromotive force amplitude; U is the grid voltage amplitude; X f This is the filter reactance.

[0083] For example, to verify the effectiveness of the frequency-supporting function of the VSG, at time 3s, a frequency drop of 0.1Hz was caused in the grid corresponding to each port of the target inverter, and the virtual inertia of the two VSG-controlled inverters was set to 3. (Reference) Figure 4 The diagram shows the grid frequency waveform. At the start of grid operation, after a brief frequency fluctuation, the two grid-connected inverters returned to a stable state. After a 3-second frequency drop, the VSG, after a brief transient process, released more active power to support the grid frequency, thus restoring it to a steady state. The power support diagram of the VSG is shown in the reference diagram. Figure 5 That is, more active power was released at 3s.

[0084] In this embodiment of the application, by determining the corresponding grid frequency regulation method according to the type of inverter connected to the grid with abnormal frequency, the flexibility and reliability of grid frequency regulation can be guaranteed.

[0085] Based on the above embodiments, this application provides another optional method for frequency adjustment. Specifically, when the frequency anomaly value of the frequency-abnormal power grid is less than the anomaly threshold, the grid-connected inverters of the frequency-abnormal power grid are used to adjust the frequency of the frequency-abnormal power grid; when the frequency anomaly value is greater than or equal to the anomaly threshold, each grid-connected inverter is controlled to adjust the frequency of the frequency-abnormal power grid through a shared DC bus based on the virtual inertia of each grid-connected inverter.

[0086] The so-called abnormal threshold is used to measure the magnitude of frequency anomalies and can be determined based on the frequency range that a single grid-connected inverter can adjust. Virtual inertia is a core control coefficient in VSG virtual synchronous generator control, used to simulate the mechanical rotational inertia of the rotor of a traditional synchronous generator set. It has no physical entity and exists only in the control algorithm, specifically used to provide virtual rotational inertia to the power grid and suppress instantaneous changes in grid frequency.

[0087] Optionally, if the frequency anomaly value of the abnormal power grid is less than the anomaly threshold, it proves that the power deviation is small. In this case, a single grid-connected inverter can complete the frequency adjustment. Therefore, only the grid-connected inverter connected to the abnormal power grid can be used to adjust the frequency of the abnormal power grid, thereby gradually pulling the frequency back to the rated frequency range.

[0088] When the frequency anomaly value is greater than or equal to the anomaly threshold, it indicates that the power deviation is large. At this time, a single grid-type inverter cannot complete the frequency adjustment. Therefore, the output sequence of each grid-type inverter to the frequency anomaly grid can be determined by the virtual inertia of each grid-type inverter in the target inverter equipment. Then, based on the output sequence, each grid-type inverter is controlled to adjust the frequency of the frequency anomaly grid through a shared DC bus.

[0089] In this embodiment of the application, by determining the corresponding power grid frequency regulation method according to the degree of abnormality of the power grid, the flexibility and reliability of power grid frequency regulation can be guaranteed.

[0090] Based on the above embodiments, this application provides another optional frequency adjustment method. Specifically, when the virtual inertia of each grid-type inverter is consistent, each grid-type inverter is simultaneously controlled to adjust the frequency of the abnormal grid through a shared DC bus. When the virtual inertia of each grid-type inverter is inconsistent, the output sequence of each grid-type inverter is determined according to the relationship between the virtual inertia of each grid-type inverter, and according to the output sequence, each grid-type inverter is controlled to adjust the frequency of the abnormal grid through a shared DC bus.

[0091] Optionally, when the virtual inertia of each grid-type inverter is consistent, the transient dynamic response of each grid-type inverter to frequency disturbances is completely synchronized, i.e., there is no sequential response or power difference. In this case, each grid-type inverter can be simultaneously controlled to adjust the frequency of the abnormal grid through a shared DC bus. That is, the target inverter connected to the abnormal grid can be simultaneously controlled to adjust the frequency of the abnormal grid, and other inverters can be controlled to adjust the frequency of the abnormal grid through a shared DC bus.

[0092] Because grid-connected inverters with smaller virtual inertia can process active power more quickly, while grid-connected inverters with larger virtual inertia can continuously output stable active power. For example, refer to... Figure 6 The diagram shows the grid frequency waveform. At time 3s, a 0.1Hz frequency drop is caused in the grid corresponding to each port of the target inverter. With the virtual inertia of VSG1 and VSG2 set to 5.5 and 0.5 respectively, VSG1 responds more slowly but has a smaller overshoot, a smaller transient rate of change, and better steady-state characteristics. Conversely, VSG2 responds more quickly but has a larger overshoot and more drastic system state changes. This difference is because the system determines that VSG2 has greater capacity redundancy and that the system connected to the converter has higher strength and stability. Therefore, a more aggressive parameter design is adopted, allowing VSG2 to respond to system changes more quickly. VSG1, with its larger inertia coefficient, results in a smoother change process, thus avoiding system stability issues.

[0093] Therefore, when the virtual inertia of each grid-type inverter is inconsistent, the output sequence of the inverters can be determined first based on the relationship between their virtual inertia. Then, according to the output sequence, each grid-type inverter is controlled to adjust the frequency of the grid with frequency anomalies via a shared DC bus. That is, the output sequence is to first control the grid-type inverter with the smaller virtual inertia to adjust the frequency of the grid with frequency anomalies; then control the grid-type inverter with the larger virtual inertia to adjust the frequency of the grid with frequency anomalies.

[0094] It is worth noting that in practical applications, the basic inertia parameter J0 can be determined under the normal operation of the power grid system. Then, based on the actual capacity of the two VSGs, one VSG grid-type inverter can be selected with a larger deviation of the J value from the basic inertia parameter J0, while the other VSG grid-type inverter has a smaller deviation of the J value from the basic inertia parameter J0.

[0095] Furthermore, during operation, VSG units with more abundant capacity or connected to areas with weaker grid structures and scarcer inertia can be prioritized to dynamically undertake a larger share of inertia support tasks, while another VSG can appropriately reduce its inertia output to retain necessary power regulation margin. This parameter-level dynamic mutual assistance mechanism based on real-time status achieves optimal dynamic configuration and precise support of limited inertia resources in the spatiotemporal dimensions within the system, maximizing the overall support efficiency and operational flexibility of the hybrid power grid in the face of complex and ever-changing operating conditions.

[0096] In this embodiment, by determining the corresponding grid frequency regulation method based on the consistency of the virtual inertia of each grid-type inverter, the flexibility and reliability of grid frequency regulation can be guaranteed.

[0097] Based on the above embodiments, this application provides a voltage adjustment method, such as... Figure 7 As shown, the specific steps include:

[0098] S701, if it is determined that there is no abnormal frequency power grid, obtain the current bus voltage of the shared DC bus.

[0099] The current bus voltage refers to the voltage across the shared DC bus. It can be understood that the target inverter equipment, in addition to regulating the grid's power output, can also perform bus voltage stabilization and harmonic mitigation operations. For example, refer to... Figure 8 As shown, the core control flexibility of the target inverter equipment is prominently reflected in its VSG-controlled inverter, which has advanced multi-mode operation and dynamic seamless switching capabilities. Its highly integrated control architecture includes three key operating modes: frequency support mode for grid stability, harmonic control mode for power quality optimization, and bus voltage stabilization mode for system energy balance.

[0100] Optionally, if it is determined that there is no abnormal frequency in the power grid, the target inverter equipment can perform bus voltage stabilization. In this case, the current bus voltage of the shared DC bus can be obtained by voltage acquisition units (such as Hall voltage sensors / precision voltage divider resistors) deployed at the positive and negative terminals of the shared DC bus main bus.

[0101] S702 determines the bus adjustment parameters for the shared DC bus based on the voltage deviation between the current bus voltage and the rated bus voltage.

[0102] The rated bus voltage refers to the voltage value of the shared DC bus during normal operation. The bus adjustment parameters are the relevant parameters for achieving bus voltage stabilization, which may include, but are not limited to, corrected virtual inertia, corrected droop coefficient, and corrected active power reference.

[0103] Optionally, the voltage difference between the current bus voltage and the rated bus voltage of the shared DC bus can be used as the voltage deviation. This voltage deviation can then be fed into the shared DC bus voltage PI regulator to output the active power correction required to balance DC energy. Furthermore, the active power correction can be coupled into the VSG frequency regulation parameters to form bus adjustment parameters with voltage regulation constraints.

[0104] S703 controls the grid-type inverter to adjust the voltage of the shared DC bus based on the bus adjustment parameters.

[0105] Optionally, based on bus adjustment parameters, the grid-type inverter can be controlled to adjust the AC-side active power throughput, thereby changing the DC-side energy balance and ultimately pulling the bus voltage back to its rated value. For example, based on the corrected virtual inertia, inertia-based frequency regulation power can be calculated to suppress voltage / frequency transient fluctuations; steady-state frequency regulation active power can be calculated based on the corrected droop coefficient and the corrected active power reference to achieve energy balance.

[0106] In this embodiment, by controlling the grid-type inverter according to the bus adjustment parameters, the voltage of the shared DC bus is adjusted to achieve voltage stabilization of the shared DC bus, thereby ensuring the reliability of the power grid operation.

[0107] Based on the above embodiments, this application provides a harmonic adjustment method, specifically, in the case that there is no abnormal frequency grid, the frequency control operation of the grid-type inverter is stopped, and the computing resources of the grid-type inverter are allocated to the harmonic processing tasks associated with the grid-type inverter.

[0108] The so-called harmonic processing task refers to the computational tasks related to harmonic processing associated with grid-connected inverters. For example, refer to... Figure 9 The diagram shows a harmonic processing procedure. It also shows the acquisition of the three-phase load current i. L (In the abc stationary coordinate system), through the abc / dq transformation, it is transformed to the dq rotating coordinate system to obtain i. Ld and i Lq Among them, i Ld The d-axis component (corresponding to active current, including fundamental and harmonic frequencies); i Lq This represents the q-axis component (corresponding to reactive current, including fundamental and harmonic frequencies). Then, i can be... Ld and i Lq The signals are fed into a filter (low-pass filter, LPF). The fundamental frequency is a DC component in the dq coordinate system, while the harmonics are high-frequency AC components. The low-pass filter removes the harmonics and retains the fundamental frequency component, resulting in I. Ld and I Lq Among them, I Ld I represents the fundamental active current (d-axis). LqThis represents the fundamental reactive current (q-axis).

[0109] Furthermore, subtracting the fundamental frequency dq component from the total current dq component yields the harmonic component i. hd (d-axis harmonic current) and i hq (q-axis harmonic current). Then, based on the system frequency / voltage regulation requirements, an additional reference value is superimposed on the dq-axis via a mode switching module to obtain the dq-axis compensation current reference value. Through dq / abc transformation, the dq-axis compensation current reference value is converted back to the three-phase stationary coordinate system to obtain the three-phase compensation current reference value i. ref .

[0110] For example, refer to Figure 10 The diagram illustrating harmonic mitigation shows that when the grid frequency of VSG1 is fixed at 50Hz, harmonic current is injected into the corresponding grid 1. In this case, VSG1 does not need to perform additional power compensation, harmonics are significantly reduced, and the system's power quality is noticeably improved.

[0111] To ensure the efficiency of harmonic processing tasks in the power grid, if it is determined that there is no power grid with abnormal frequency, the computing resources originally used for power grid frequency regulation can be allocated to harmonic processing tasks.

[0112] Optionally, the virtual inertia J control loop in the grid-connected inverter can be locked to stop the transient surge protection power calculation based on the frequency change rate, and the active frequency-droop control loop can be locked to stop the steady-state correction power regulation based on the frequency deviation. It is worth noting that the core function of the grid-connected inverter remains unchanged at this time; it still provides voltage amplitude and phase references for the associated weak grid, only the frequency regulation operation is not performed.

[0113] Furthermore, the computing resources released after frequency modulation is stopped can be fully allocated to the harmonic processing tasks associated with the grid-type inverter.

[0114] In this embodiment of the application, by allocating the computing resources of the grid-connected inverter to the harmonic processing tasks associated with the grid-connected inverter, the efficiency of harmonic processing in the power grid can be improved, thereby ensuring the reliability of power grid operation.

[0115] Figure 11 This is a flowchart illustrating a power grid frequency regulation method based on a shared DC bus in another embodiment. Based on the above embodiments, this embodiment provides an optional example of a power grid frequency regulation method based on a shared DC bus. (Combined with...) Figure 11 The specific implementation process is as follows:

[0116] S1101, Obtain the grid frequency data of each power grid to which the target inverter device is connected.

[0117] The target inverter equipment includes one grid-connected inverter and at least two grid-connected inverters, which are connected via a shared DC bus.

[0118] S1102, Based on the grid frequency data of each grid, determine whether there are any grids with abnormal frequencies in each grid. If yes, proceed to S1103; otherwise, proceed to S1104.

[0119] S1103, when a grid-connected inverter is connected to a grid with abnormal frequency, the grid-connected inverter is controlled to transmit active power to the grid with abnormal frequency through a shared DC bus; or, when a grid-connected inverter is connected to a grid with abnormal frequency, the grid-connected inverter in the target inverter device is used to adjust the frequency of the grid with abnormal frequency based on the abnormal frequency value of the grid with abnormal frequency.

[0120] Optionally, if the frequency anomaly value of the frequency-abnormal power grid is less than the anomaly threshold, a grid-connected inverter connected to the frequency-abnormal power grid can be used to adjust the frequency of the frequency-abnormal power grid.

[0121] If the abnormal frequency value is greater than or equal to the abnormal threshold, and the virtual inertia of each grid-type inverter is consistent, then each grid-type inverter is controlled to adjust the frequency of the abnormal grid through the shared DC bus. If the virtual inertia of each grid-type inverter is inconsistent, then the output sequence of each grid-type inverter is determined according to the relationship between the virtual inertia of each grid-type inverter, and according to the output sequence, each grid-type inverter is controlled to adjust the frequency of the abnormal grid through the shared DC bus.

[0122] S1104: Obtain the current bus voltage of the shared DC bus, and determine the bus adjustment parameters of the shared DC bus based on the voltage deviation between the current bus voltage and the rated bus voltage.

[0123] S1105 controls the grid-type inverter to adjust the voltage of the shared DC bus based on the bus adjustment parameters.

[0124] S1106, stop the frequency control operation on the grid inverter and allocate the computing resources of the grid inverter to the harmonic processing task associated with the grid inverter.

[0125] The specific processes of S1101-S1106 described above can be found in the description of the above method embodiments. Their implementation principles and technical effects are similar, and will not be repeated here.

[0126] 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.

[0127] Based on the same inventive concept, this application also provides a shared DC bus-based grid frequency regulation device for implementing the aforementioned grid frequency regulation method based on a shared DC bus. The solution provided by this device is similar to the implementation described in the above method. Therefore, the specific limitations of one or more shared DC bus-based grid frequency regulation device embodiments provided below can be found in the limitations of the shared DC bus-based grid frequency regulation method described above, and will not be repeated here.

[0128] In one exemplary embodiment, such as Figure 12 As shown, a power grid frequency regulation device 1 based on a shared DC bus is provided, comprising: a data acquisition module 10, an anomaly detection module 20, and a frequency adjustment module 30, wherein:

[0129] The data acquisition module 10 is used to acquire the grid frequency data of each grid to which the target inverter device is connected; wherein, the target inverter device includes one grid-connected inverter and at least two grid-connected inverters, and the grid-connected inverter and the grid-connected inverters are connected through a shared DC bus.

[0130] The anomaly detection module 20 is used to determine whether there are any abnormal frequency grids in each power grid based on the power grid frequency data of each power grid.

[0131] The frequency adjustment module 30 is used to adjust the frequency of the abnormal power grid by using a target inverter device when it is determined that there is an abnormal power grid.

[0132] In one exemplary embodiment, the frequency adjustment module 30 is specifically used for:

[0133] When a grid-connected inverter is connected to a grid with abnormal frequency, the grid-connected inverter is controlled to transmit active power to the grid with abnormal frequency through a shared DC bus. When a grid-connected inverter is connected to a grid with abnormal frequency, the grid-connected inverter in the target inverter equipment is used to adjust the frequency of the grid with abnormal frequency based on the abnormal frequency value of the grid.

[0134] In one exemplary embodiment, the frequency adjustment module 30 is further configured to:

[0135] When the frequency anomaly value of the frequency-abnormal power grid is less than the anomaly threshold, the grid-connected inverters of the frequency-abnormal power grid are used to adjust the frequency of the frequency-abnormal power grid; when the frequency anomaly value is greater than or equal to the anomaly threshold, the virtual inertia of each grid-connected inverter is used to control each grid-connected inverter to adjust the frequency of the frequency-abnormal power grid through a shared DC bus.

[0136] In one exemplary embodiment, the frequency adjustment module 30 is further configured to:

[0137] When the virtual inertia of each grid-type inverter is consistent, the inverters are controlled to adjust the frequency of the grid with abnormal frequency by sharing a DC bus. When the virtual inertia of each grid-type inverter is inconsistent, the output sequence of each inverter is determined according to the relationship between their virtual inertia, and the inverters are controlled to adjust the frequency of the grid with abnormal frequency by sharing a DC bus according to the output sequence.

[0138] In an exemplary embodiment, the grid frequency regulation device 1 based on a shared DC bus further includes a bus voltage stabilization module, wherein the bus voltage stabilization module is specifically used for:

[0139] If it is determined that there is no abnormal frequency grid, the current bus voltage of the shared DC bus is obtained; the bus adjustment parameters of the shared DC bus are determined based on the voltage deviation between the current bus voltage and the rated bus voltage; and the grid-type inverter is controlled to adjust the voltage of the shared DC bus based on the bus adjustment parameters.

[0140] In an exemplary embodiment, the grid frequency regulation device 1 based on a shared DC bus further includes a harmonic processing module, wherein the harmonic processing module is specifically used for:

[0141] If it is determined that there is no abnormal frequency grid, stop the frequency control operation on the grid-connected inverter and allocate the computing resources of the grid-connected inverter to the harmonic processing tasks associated with the grid-connected inverter.

[0142] Each module in the aforementioned power grid frequency regulation device based on a shared DC bus can be implemented entirely or partially through software, hardware, or a combination thereof. These modules can be embedded in or independent of the processor in a computer device, or stored in the memory of a computer device as software, so that the processor can call and execute the corresponding operations of each module.

[0143] In one exemplary embodiment, a computer device is provided, which may be a server, and its internal structure diagram may be as follows: Figure 13 As shown, this computer device includes a processor, memory, input / output (I / O) interfaces, and a communication interface. The processor, memory, and I / O interfaces are connected via a system bus, and the communication interface is also connected to the system bus via the I / O interfaces. The processor provides computational and control capabilities. The memory includes non-volatile storage media and internal memory. The non-volatile storage media stores the operating system, computer programs, and a database. The internal memory provides the environment for the operating system and computer programs stored in the non-volatile storage media. The database stores power grid frequency data. The I / O interfaces are used for exchanging information between the processor and external devices. The communication interface is used for communicating with external terminals via a network. When executed by the processor, the computer program implements a power grid frequency regulation method based on a shared DC bus.

[0144] Those skilled in the art will understand that Figure 13 The structure shown is merely a block diagram of a portion of the structure related to the present application and does not constitute a limitation on the computer device to which the present application is applied. Specific computer devices may include more or fewer components than those shown in the figure, or combine certain components, or have different component arrangements.

[0145] In one embodiment, a computer device is also provided, including a memory and a processor, wherein the memory stores a computer program, and the processor executes the computer program to implement the steps in the above method embodiments.

[0146] In one embodiment, a computer-readable storage medium is provided having a computer program stored thereon that, when executed by a processor, implements the steps in the above method embodiments.

[0147] In one embodiment, a computer program product is provided, including a computer program that, when executed by a processor, implements the steps in the above method embodiments.

[0148] It should be noted that the data involved in this application (including but not limited to power grid frequency data) are all information and data authorized by the user or fully authorized by all parties, and the collection, use and processing of the relevant data must comply with relevant regulations.

[0149] Those skilled in the art will understand that all or part of the processes in the methods of 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 of the above methods. Any references to memory, databases, or other media used in the embodiments provided in this application can include at least one of non-volatile memory 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, artificial intelligence (AI) processors, etc., and are not limited to these.

[0150] 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 application.

[0151] 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 patent 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 power grid frequency regulation method based on a shared DC bus, characterized in that, The method includes: Obtain the grid frequency data of each power grid to which the target inverter device is connected; wherein, the target inverter device includes one grid-connected inverter and at least two grid-connected inverters, and the grid-connected inverter and the grid-connected inverters are connected through a shared DC bus; Based on the grid frequency data of each power grid, determine whether there are any power grids with abnormal frequencies in each power grid; If the existence of the frequency-abnormal power grid is confirmed, the target inverter device is used to adjust the frequency of the frequency-abnormal power grid.

2. The method according to claim 1, characterized in that, The step of using the target inverter equipment to adjust the frequency of the abnormal power grid includes: When the grid-connected inverter is connected to the frequency-abnormal power grid, the grid-connected inverter is controlled to transmit active power to the frequency-abnormal power grid through the shared DC bus; When a grid-connected inverter is connected to the abnormal frequency grid, the grid-connected inverter in the target inverter device is used to adjust the frequency of the abnormal frequency grid according to the abnormal frequency value of the abnormal frequency grid.

3. The method according to claim 2, characterized in that, The step of adjusting the frequency of the abnormal power grid based on the abnormal frequency value of the abnormal grid, using a grid-connected inverter in the target inverter equipment, includes: When the frequency anomaly value of the frequency anomaly grid is less than the anomaly threshold, the frequency of the frequency anomaly grid is adjusted by using the grid-connected inverter connected to the frequency anomaly grid. When the frequency anomaly value is greater than or equal to the anomaly threshold, each grid-type inverter is controlled to adjust the frequency of the abnormal grid through the shared DC bus, based on the virtual inertia of each grid-type inverter.

4. The method according to claim 3, characterized in that, The step of controlling each grid-type inverter to adjust the frequency of the abnormal frequency grid through the shared DC bus based on the virtual inertia of each grid-type inverter includes: With the virtual inertia of each grid-type inverter being consistent, each grid-type inverter is simultaneously controlled to adjust the frequency of the abnormal frequency grid through the shared DC bus. When the virtual inertia of each grid-type inverter is inconsistent, the output sequence of each grid-type inverter is determined according to the relationship between the magnitudes of the virtual inertia of each grid-type inverter, and according to the output sequence, each grid-type inverter is controlled to adjust the frequency of the abnormal frequency grid through the shared DC bus.

5. The method according to any one of claims 1-4, characterized in that, The method further includes: If it is determined that there is no abnormal frequency power grid, the current bus voltage of the shared DC bus is obtained; The bus adjustment parameters of the shared DC bus are determined based on the voltage deviation between the current bus voltage and the rated bus voltage. Based on the bus adjustment parameters, the grid-type inverter is controlled to adjust the voltage of the shared DC bus.

6. The method according to any one of claims 1-4, characterized in that, The method further includes: If it is determined that there is no abnormal frequency grid, the frequency control operation on the grid-connected inverter is stopped, and the computing resources of the grid-connected inverter are allocated to the harmonic processing tasks associated with the grid-connected inverter.

7. A power grid frequency regulation device based on a shared DC bus, characterized in that, The device includes: The data acquisition module is used to acquire the grid frequency data of each grid to which the target inverter device is connected; wherein, the target inverter device includes one grid-connected inverter and at least two grid-connected inverters, and the grid-connected inverter and the grid-connected inverters are connected through a shared DC bus. The anomaly detection module is used to determine whether there are any power grids with abnormal frequencies in each power grid based on the power grid frequency data of each power grid. The frequency adjustment module is used to adjust the frequency of the abnormal power grid by using the target inverter device when the existence of the abnormal power grid is determined.

8. A computer device comprising a memory and a processor, wherein the memory stores a computer program, characterized in that, When the processor executes the computer program, it implements the steps of the method according to any one of claims 1 to 6.

9. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by a processor, it implements the steps of the method according to any one of claims 1 to 6.

10. A computer program product, comprising a computer program, characterized in that, When the computer program is executed by a processor, it implements the steps of the method according to any one of claims 1 to 6.

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