Control method, device and system of energy storage converter and storage medium

Abstract

The invention provides a control method, device and system of an energy storage converter and a storage medium. The method comprises the following steps: acquiring a three-phase power grid voltage instantaneous value and a three-phase power grid current instantaneous value; calculating power grid equivalent impedance according to the three-phase power grid voltage instantaneous value and the three-phase power grid current instantaneous value; calculating the maximum active power transmission value of the energy storage converter according to the equivalent impedance of the power grid; judging whether the maximum active power transmission value is smaller than an active power reference instruction initial value or not; if yes, recalculating the active power reference value of the energy storage converter according to the three-phase power grid voltage instantaneous value, the power grid equivalent impedance and the active power reference instruction initial value, and taking the active power reference value as a new active power reference instruction; and if not, keeping the initial value of the current active power reference instruction unchanged. According to the scheme provided by the invention, the energy storage converter can adaptively adjust the output characteristics of the energy storage converter, so that the stable operation of the energy storage converter is ensured.

Description

Technical Field

[0001] This invention belongs to the field of energy storage converter technology, and in particular relates to a control method, device, system and storage medium for an energy storage converter. Background Technology

[0002] With the large-scale integration of new energy sources, the stability of the power system faces new challenges, among which energy storage converters play an important role. However, when the power grid experiences large disturbances, it will affect the stable operation of energy storage converters. In particular, when the power grid experiences large disturbances (such as voltage disturbances), if the energy storage converter cannot respond quickly or the transient process adjustment time is too long, it will lead to the instability of the energy storage converter and even trigger a fault shutdown. Summary of the Invention

[0003] In view of this, the present invention aims to provide a control method, device, system and storage medium for energy storage converters, so as to solve the problem that the existing control of energy storage converters cannot make fast responses or the transient process adjustment time is too long, which leads to the instability of the energy storage converter operation.

[0004] To achieve the above objectives, the technical solution of the present invention is implemented as follows:

[0005] In a first aspect, embodiments of the present invention provide a control method for an energy storage converter, comprising:

[0006] Obtain the instantaneous values ​​of the three-phase grid voltage and the instantaneous values ​​of the three-phase grid current;

[0007] The equivalent impedance of the power grid is calculated based on the instantaneous values ​​of the three-phase grid voltage and the instantaneous values ​​of the three-phase grid current.

[0008] The maximum active power transmission value of the energy storage converter is calculated based on the equivalent impedance of the power grid.

[0009] Determine whether the maximum active power transmission value is less than the initial value of the active power reference command;

[0010] If so, the active power reference value of the energy storage converter is recalculated based on the instantaneous value of the three-phase grid voltage, the equivalent impedance of the grid, and the initial value of the active power reference command, and the active power reference value is used as the new active power reference command.

[0011] If not, then keep the initial value of the current active power reference command unchanged.

[0012] Furthermore, the step of calculating the maximum active power transmission value of the energy storage converter based on the equivalent impedance of the power grid includes:

[0013] Obtain the instantaneous three-phase voltage values ​​on the AC side of the energy storage converter;

[0014] The phase angle difference between the instantaneous three-phase voltage on the AC side of the energy storage converter and the instantaneous three-phase grid voltage when the maximum active power transmitted by the energy storage converter is calculated based on the equivalent impedance of the grid.

[0015] The maximum active power transmission value of the energy storage converter is calculated based on the phase angle difference.

[0016] Furthermore, when calculating the maximum active power transmitted by the energy storage converter based on the equivalent impedance of the power grid, the phase angle difference between the instantaneous values ​​of the three-phase voltage on the AC side of the energy storage converter and the instantaneous values ​​of the three-phase grid voltage includes:

[0017] Obtain the current operating state of the energy storage converter, including charging or discharging;

[0018] Based on the operating state, the phase angle difference δ between the instantaneous three-phase voltage value on the AC side of the energy storage converter and the instantaneous three-phase grid voltage value is calculated according to the following formula. pm :

[0019]

[0020] Wherein, the grid equivalent impedance of the energy storage converter is Z g Z g =X g +jR g X g R is the grid equivalent inductive reactance of the energy storage converter. g The grid equivalent resistance of the energy storage converter is given.

[0021] Furthermore, the step of calculating the maximum active power transmission value of the energy storage converter based on the phase angle difference includes:

[0022] The maximum active power transmission value P of the energy storage converter is calculated according to the following formula. max :

[0023]

[0024] Among them, V cm V represents the amplitude of the instantaneous three-phase voltage on the AC side of the energy storage converter. gm The amplitude of the instantaneous voltage of the three-phase power grid.

[0025] Furthermore, the step of recalculating the active power reference value of the energy storage converter based on the instantaneous value of the three-phase grid voltage, the equivalent impedance of the grid, and the initial value of the active power reference command includes:

[0026] The active power reference value P of the energy storage converter should be recalculated using the following formula.ref :

[0027]

[0028] Among them, V cm V represents the amplitude of the instantaneous three-phase voltage on the AC side of the energy storage converter. gm V represents the amplitude of the instantaneous voltage of the three-phase power grid. rated P is the amplitude of the three-phase rated voltage when the energy storage converter is operating normally. ref0 The initial value of the active power reference command for the energy storage converter is Z, and the grid equivalent impedance of the energy storage converter is Z. g Z g =X g +jR g X g R is the grid equivalent inductive reactance of the energy storage converter. g The grid equivalent resistance of the energy storage converter is given.

[0029] Furthermore, after determining that the maximum active power transmission value is less than the initial value of the active power reference command, before recalculating the active power reference value of the energy storage converter based on the instantaneous value of the three-phase grid voltage, the equivalent impedance of the grid, and the initial value of the active power reference command, and before using the active power reference value as the new active power reference command, the method further includes:

[0030] Start timing;

[0031] Determine whether the timing time has reached the preset time, and when the timing time has reached the preset time, recalculate the active power reference value of the energy storage converter based on the instantaneous value of the three-phase grid voltage, the equivalent impedance of the grid, and the initial value of the active power reference command.

[0032] Furthermore, the step of using the active power reference value as the new active power reference command includes:

[0033] The active power reference value is processed according to the following formula before being used as the new active power reference command P. set :

[0034]

[0035] Where n is an integer, and 1≤n≤9, P ref P is the current value of the active power reference value. ref_1 P is the value at the previous sampling time of the active power reference value. ref_n This represents the value of the active power reference value at the previous n sampling times.

[0036] Secondly, embodiments of the present invention also provide a control device for an energy storage converter, comprising:

[0037] The acquisition module is used to acquire the instantaneous values ​​of the three-phase grid voltage and the instantaneous values ​​of the three-phase grid current.

[0038] The impedance calculation module is used to calculate the equivalent impedance of the power grid based on the instantaneous values ​​of the three-phase power grid voltage and the instantaneous values ​​of the three-phase power grid current.

[0039] The power transmission value calculation module is used to calculate the maximum active power transmission value of the energy storage converter based on the equivalent impedance of the power grid.

[0040] The judgment module is used to determine whether the maximum active power transmission value is less than the initial value of the active power reference command;

[0041] The power reference value calculation module is used to recalculate the active power reference value of the energy storage converter based on the instantaneous value of the three-phase grid voltage, the equivalent impedance of the grid, and the initial value of the active power reference command if the condition is met, and to use the active power reference value as the new active power reference command.

[0042] The holding module is used to maintain the initial value of the current active power reference command unchanged if otherwise.

[0043] Thirdly, the present invention also provides an energy storage converter system, comprising:

[0044] The control device for the energy storage converter described in the above embodiments;

[0045] Energy storage converter.

[0046] Fourthly, embodiments of the present invention also provide a storage medium containing computer-executable instructions, which, when executed by a computer processor, are used to perform the control method for the energy storage converter described above.

[0047] Compared with existing technologies, the control method, device, system, and storage medium for an energy storage converter described in this invention have the following advantages:

[0048] The present invention discloses a control method, device, system, and storage medium for an energy storage converter. By acquiring the instantaneous values ​​of the three-phase grid voltage and current, the equivalent impedance of the grid can be calculated. Through modeling and analysis of the energy storage converter, the maximum active power transmission value of the converter can be calculated based on the equivalent impedance. Then, by determining whether the maximum active power transmission value is less than the initial value of the active power reference command, it can be determined whether the energy storage converter is operating in a stable state. If the maximum active power transmission value is less than the initial value of the active power reference command, it can be considered that the actual output or absorbed active power of the energy storage converter is not keeping up with the initial value of the active power reference command. Therefore, the active power reference value of the energy storage converter can be recalculated based on the instantaneous values ​​of the three-phase grid voltage, the equivalent impedance of the grid, and the initial value of the active power reference command, and this recalculated active power reference value can be used as the new active power reference command. Conversely, if the maximum active power transmission value is greater than or equal to the initial value of the active power reference command, the current initial value of the active power reference command can be kept unchanged. In this way, by adaptively adjusting the active power reference command of the energy storage converter, the energy storage converter can always operate in a stable state, and can respond quickly and promptly when disturbances occur in the power grid, shortening the transient adjustment time and suppressing transient fluctuations. Attached Figure Description

[0049] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, although the drawings described below are some specific embodiments of the present invention, those skilled in the art can extend and extend the basic concepts of the device structure, driving method, and manufacturing method disclosed and indicated by various embodiments of the present invention to other structures and drawings. Undoubtedly, these should all be within the scope of the claims of the present invention. In the drawings:

[0050] Figure 1 This is a schematic flowchart of a control method for an energy storage converter according to Embodiment 1 of the present invention;

[0051] Figure 2 This is a schematic flowchart of a control method for an energy storage converter according to Embodiment 2 of the present invention;

[0052] Figure 3 This is a schematic flowchart of a control method for an energy storage converter according to Embodiment 3 of the present invention;

[0053] Figure 4 This is a schematic diagram of the control device for an energy storage converter according to Embodiment 4 of the present invention;

[0054] Figure 5This is a schematic diagram of the structure of an energy storage converter system according to Embodiment 5 of the present invention. Detailed Implementation

[0055] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of this invention. Obviously, the described embodiments are only some embodiments of this invention, not all embodiments. Based on the basic concepts disclosed and indicated in the embodiments of this invention, all other embodiments obtained by those skilled in the art are within the scope of protection of this invention.

[0056] Example 1

[0057] Figure 1 This is a schematic flowchart of a control method for an energy storage converter according to Embodiment 1 of the present invention. Figure 1 As shown, the control method specifically includes the following steps:

[0058] S11. Obtain the instantaneous values ​​of the three-phase grid voltage and the instantaneous values ​​of the three-phase grid current.

[0059] It is understandable that the three-phase grid current here is the current that the energy storage converter interacts with the grid during grid-connected operation. When the direction of the three-phase grid current is the same as the direction of the three-phase grid voltage, the energy storage converter can be considered to be in a discharging state. When the direction of the three-phase grid current is opposite to the direction of the three-phase grid voltage, the energy storage converter can be considered to be in a charging state.

[0060] S12. Calculate the equivalent impedance of the power grid based on the instantaneous values ​​of the three-phase power grid voltage and the instantaneous values ​​of the three-phase power grid current.

[0061] Specifically, the collected instantaneous three-phase grid voltage values ​​are first filtered to remove noise signals and high-frequency harmonic components, thereby obtaining the fundamental component of the instantaneous three-phase grid voltage values. Then, further processing of the fundamental component of the instantaneous three-phase grid voltage values ​​yields the amplitude and phase angle of the instantaneous three-phase grid voltage values.

[0062] Similarly, the collected instantaneous values ​​of the three-phase power grid current are first filtered to remove noise signals and high-frequency harmonic components, thereby obtaining the fundamental component of the instantaneous values ​​of the three-phase power grid current. Then, further processing of the fundamental component of the instantaneous values ​​of the three-phase power grid current yields the amplitude and phase angle of the instantaneous values ​​of the three-phase power grid current.

[0063] Therefore, given the instantaneous amplitude and phase angle of the three-phase grid voltage and the instantaneous amplitude and phase angle of the three-phase grid current, the formula can be used... The magnitude of the equivalent impedance of the power grid is obtained, where V gm I represents the amplitude of the instantaneous voltage of the three-phase power grid.gm Z represents the amplitude of the instantaneous current in the three-phase power grid. g This is the equivalent impedance of the power grid. Furthermore, according to the formula R... g =|Z g |·cosθ and formula X g =|Z g |·sinθ is used to calculate the equivalent inductive reactance X of the power grid in the equivalent impedance of the power grid. g Equivalent resistance R of the power grid g , where θ is the phase angle difference between the instantaneous values ​​of the three-phase grid voltage and the instantaneous values ​​of the three-phase grid current.

[0064] S13. Calculate the maximum active power transmission value of the energy storage converter based on the equivalent impedance of the power grid.

[0065] Specifically, the magnitude of the grid equivalent impedance limits the maximum active power transmitted between the energy storage converter and the grid, especially the magnitude of the equivalent resistance within the grid equivalent impedance. Therefore, once the grid equivalent impedance is determined, a mathematical model of the energy storage converter can be used for modeling and analysis to calculate the maximum active power transmission value of the energy storage converter.

[0066] S14. Determine whether the maximum active power transmission value is less than the initial value of the active power reference command. If yes, proceed to step S15; otherwise, proceed to step S16.

[0067] The initial value of the active power reference command can be any value between 0 and the rated power of the energy storage converter.

[0068] S15. Recalculate the active power reference value of the energy storage converter based on the instantaneous value of the three-phase grid voltage, the grid equivalent impedance, and the initial value of the active power reference command, and use the active power reference value as the new active power reference command.

[0069] Understandably, when an energy storage converter is connected to the grid, the stability of the grid directly affects its stable operation. When a large disturbance occurs in the grid, such as a short-circuit fault or large-scale load switching, it may cause a sudden and significant drop or rise in grid voltage. If this is not controlled in a timely and effective manner, it will lead to voltage collapse and cause a large-scale power outage.

[0070] S16. Keep the current active power reference command initial value unchanged.

[0071] Specifically, the magnitude of the grid's equivalent impedance affects the strength of the entire power grid system. If the grid's equivalent impedance is very small, the grid system can be considered a strong grid system; if the grid's equivalent impedance is very large, the grid system can be considered a weak grid system. Therefore, when the energy storage converter is operating in grid-connected mode, the active power transmission between it and the grid is also limited by the magnitude of the grid's equivalent impedance. Once the maximum active power transmission value between the energy storage converter and the grid is less than the initial value of the active power reference command, it will lead to instability of the entire system, or even serious faults. Thus, when the grid experiences disturbances, in order to ensure the stable operation of the system, the active power reference command can be adaptively adjusted based on the detected instantaneous values ​​of the three-phase grid voltage, the grid's equivalent impedance, and the initial value of the active power reference command. This ensures that the entire system always operates stably, and during the transient process of grid disturbances, the energy storage converter can quickly respond by adjusting the active power reference command, reducing the transient adjustment time and suppressing transient active power fluctuations.

[0072] Therefore, this embodiment of the invention obtains the instantaneous values ​​of the three-phase grid voltage and current, and then calculates the grid equivalent impedance based on these values. Thus, by modeling and analyzing the energy storage converter, the maximum active power transfer value of the energy storage converter can be further calculated based on the grid equivalent impedance. Then, by determining whether the maximum active power transfer value is less than the initial value of the active power reference command, it can be determined whether the energy storage converter is currently operating in a stable state. If the maximum active power transfer value is less than the initial value of the active power reference command, it can be considered that the actual output or absorbed active power of the energy storage converter is not keeping up with the initial value of the active power reference command. Therefore, the active power reference value of the energy storage converter can be recalculated based on the instantaneous values ​​of the three-phase grid voltage, the grid equivalent impedance, and the initial value of the active power reference command, and this new active power reference command can be used. Conversely, if the maximum active power transfer value is greater than or equal to the initial value of the active power reference command, the current initial value of the active power reference command can be kept unchanged. In this way, by adaptively adjusting the active power reference command of the energy storage converter, the energy storage converter can always operate in a stable state, and can respond quickly and promptly when there are disturbances in the power grid, shortening the transient adjustment time and suppressing transient fluctuations.

[0073] It should be noted that those skilled in the art will understand that the active power reference command mentioned in this invention is only the active power reference command issued by the host computer during the actual operation of the energy storage converter, which is completely different from the compensated active power reference mentioned in the primary frequency regulation or inertia support of the energy storage converter.

[0074] Example 2

[0075] Figure 2This is a schematic flowchart of a control method for an energy storage converter according to Embodiment 2 of the present invention. Figure 2 As shown, based on the above embodiment one, the specific optimization of this embodiment is as follows: Step S13, which calculates the maximum active power transmission value of the energy storage converter based on the grid equivalent impedance, specifically includes the following steps:

[0076] S131. Obtain the instantaneous three-phase voltage values ​​on the AC side of the energy storage converter.

[0077] S132. When calculating the maximum active power transmitted by the energy storage converter based on the equivalent impedance of the power grid, the phase angle difference between the instantaneous value of the three-phase voltage on the AC side of the energy storage converter and the instantaneous value of the three-phase power grid voltage.

[0078] Specifically, the phase angle difference between the instantaneous three-phase voltage on the AC side of the energy storage converter and the instantaneous three-phase grid voltage will result in different active power transmitted between the energy storage converter and the grid. Thus, the phase angle difference between the instantaneous three-phase voltage on the AC side of the energy storage converter and the instantaneous three-phase grid voltage when the energy storage converter generates or absorbs the maximum active power can be calculated using the grid equivalent impedance. It should be noted that the phase angle difference at this time is not the maximum phase angle difference.

[0079] Preferably, when calculating the maximum active power transmitted by the energy storage converter based on the grid equivalent impedance, the phase angle difference between the instantaneous values ​​of the three-phase voltage on the AC side of the energy storage converter and the instantaneous values ​​of the three-phase grid voltage specifically includes the following steps:

[0080] Obtain the current operating status of the energy storage converter, including charging or discharging.

[0081] The operating state can be a status flag bit in the control algorithm. Different status flag bits indicate that the energy storage converter is currently operating in different states. For example, a status flag bit of 0 indicates that the energy storage converter is operating in the charging state, and a status flag bit of 1 indicates that the energy storage converter is operating in the discharging state.

[0082] Based on the operating status, the phase angle difference δ between the instantaneous three-phase voltage on the AC side of the energy storage converter and the instantaneous three-phase grid voltage is calculated using the following formula. pm :

[0083]

[0084] Among them, the grid equivalent impedance of the energy storage converter is Z. g Z g =X g +R g X g R is the grid equivalent inductive reactance of the energy storage converter. g The grid equivalent resistance of the energy storage converter.

[0085] Specifically, when the energy storage converter is operating in discharge and charging states, and the active power transmitted between it and the grid reaches its maximum value, the phase angle difference δ between the instantaneous three-phase voltage on the AC side of the energy storage converter and the instantaneous three-phase grid voltage is... pm They will be different.

[0086] S133. Calculate the maximum active power transmission value of the energy storage converter based on the phase angle difference.

[0087] Specifically, when determining the maximum active power transmitted by the energy storage converter, after considering the phase angle difference between the instantaneous values ​​of the three-phase voltage on the AC side of the energy storage converter and the instantaneous values ​​of the three-phase grid voltage, the maximum active power transmission value of the energy storage converter can be further calculated based on this phase angle difference.

[0088] Optionally, the maximum active power transfer value P of the energy storage converter can be calculated according to the following formula. max :

[0089]

[0090] Among them, V cm V represents the amplitude of the instantaneous three-phase voltage on the AC side of the energy storage converter. gm This represents the amplitude of the instantaneous voltage of the three-phase power grid.

[0091] Specifically, after obtaining the maximum active power transmission value of the energy storage converter based on the above calculations, it can be compared with the initial value of the active power reference command in real time. If it is determined that the maximum active power transmission value is less than the initial value of the active power reference command, the active power reference value P of the energy storage converter can be recalculated according to the following formula. ref :

[0092]

[0093] Among them, V cm V represents the amplitude of the instantaneous three-phase voltage on the AC side of the energy storage converter. gm V represents the amplitude of the instantaneous voltage of the three-phase power grid. rated P is the amplitude of the three-phase rated voltage when the energy storage converter is operating normally. ref0 The initial value of the active power reference command for the energy storage converter is given by Z. The grid equivalent impedance of the energy storage converter is given by Z. g Z g =X g +R g X g R is the grid equivalent inductive reactance of the energy storage converter. g The grid equivalent resistance of the energy storage converter.

[0094] Specifically, when the lines, equipment, and loads in the power grid system remain unchanged, the equivalent impedance of the power grid can be considered constant. Therefore, the instantaneous values ​​of the three-phase voltage on the AC side of the energy storage converter and the instantaneous values ​​of the three-phase grid voltage will affect the specific magnitude of the active power reference value in real time. When there is a disturbance in the grid voltage or fluctuations in the instantaneous value of the three-phase voltage output on the AC side of the energy storage converter, the first active power reference value P can be recalculated according to the above formula. ref1 , and the second active power reference value P ref2 , First active power reference value P ref1 Second active power reference value P ref2 The values ​​may be the same or different. When the energy storage converter operates stably under active power reference commands generated from different active power reference values, a phase angle difference exists, as indicated by the power angle curve. During transient adjustments, if the phase angle deviation between the instantaneous values ​​of the three-phase voltage on the AC side of the energy storage converter and the instantaneous values ​​of the three-phase grid voltage fluctuates, or even increases to exceed a certain limit, it can easily lead to instability of the energy storage converter. Therefore, it is advisable to first determine whether the energy storage converter is in a charging or discharging state. When it is determined that the energy storage converter is in a discharging state, the first active power reference value P can be selected. ref1 Second active power reference value P ref2 The minimum value in the range is used as the active power reference value P. ref When determining that the energy storage converter is in a discharge state, the first active power reference value P can be selected. ref1 Second active power reference value P ref2 The maximum value in the range is used as the active power reference value P. ref This allows the energy storage converter to adaptively adjust the active power reference value according to its own and the influence of the external power grid, thereby ensuring that the energy storage converter always operates stably.

[0095] Example 3

[0096] Figure 3 This is a schematic flowchart of a control method for an energy storage converter according to Embodiment 3 of the present invention. Figure 3As shown, based on the above embodiment, this embodiment is specifically optimized as follows: After determining that the maximum active power transmission value is less than the initial value of the active power reference command, before recalculating the active power reference value of the energy storage converter based on the instantaneous value of the three-phase grid voltage, the equivalent impedance of the grid, and the initial value of the active power reference command, and before using the active power reference value as the new active power reference command, the method further includes: starting timing. It determines whether the timing time has reached a preset time, and when it is determined that the timing time has reached the preset time, recalculates the active power reference value of the energy storage converter based on the instantaneous value of the three-phase grid voltage, the equivalent impedance of the grid, and the initial value of the active power reference command. Therefore, this control method specifically includes the following steps:

[0097] S31. Obtain the instantaneous values ​​of the three-phase grid voltage and the instantaneous values ​​of the three-phase grid current.

[0098] S32. Calculate the equivalent impedance of the power grid based on the instantaneous values ​​of the three-phase power grid voltage and the instantaneous values ​​of the three-phase power grid current.

[0099] S33. Calculate the maximum active power transmission value of the energy storage converter based on the equivalent impedance of the power grid.

[0100] S34. Determine whether the maximum active power transmission value is less than the initial value of the active power reference command. If yes, proceed to step S35; otherwise, proceed to step S38.

[0101] S35, Start timing.

[0102] S36. Determine whether the preset time has been reached. If yes, proceed to step S37; otherwise, return to step S35.

[0103] The specific value of the preset time can be set according to the actual situation, and the embodiments of the present invention do not impose specific limitations on it.

[0104] S37. Recalculate the active power reference value of the energy storage converter based on the instantaneous value of the three-phase grid voltage, the grid equivalent impedance, and the initial value of the active power reference command, and use the active power reference value as the new active power reference command.

[0105] S38. Keep the current active power reference command initial value unchanged.

[0106] Specifically, by setting a preset time, the system initiates a timer when the maximum active power transmission value is determined to be less than the initial value of the active power reference command. It then checks if the preset time has been reached. Only when the preset time has elapsed does the system recalculate the active power reference value of the energy storage converter based on the instantaneous three-phase grid voltage, the grid equivalent impedance, and the initial value of the active power reference command. This new active power reference value serves as the new active power reference command, allowing the energy storage converter to track and operate according to it. In this way, by setting a preset time, the system effectively avoids erroneous triggering of adjustments to the active power reference command due to the maximum active power transmission value.

[0107] Preferably, the active power reference value is processed according to the following formula before being used as the new active power reference command P. set :

[0108]

[0109] Where n is an integer, and 1≤n≤9, P ref P is the current value of the active power reference value. ref_1 P is the value at the previous sampling time of the active power reference value. ref_n This represents the value of the active power reference value at the previous n sampling times.

[0110] Specifically, when the instantaneous value of the three-phase grid voltage contains high-frequency harmonics or large high-frequency fluctuations, it can easily lead to high-frequency fluctuations in the recalculated active power reference value of the energy storage converter. This will cause the actual active power output of the energy storage converter to fluctuate accordingly when tracking the new active power reference command, thus affecting the stability of the grid and even causing the entire control system to become unstable. Therefore, by performing multi-value averaging filtering on the active power reference value according to the above formula before using it as the new active power reference command, the high-frequency fluctuations of the active power reference value can be suppressed, and the stability of the energy storage converter operation can be improved.

[0111] Based on the same inventive concept, embodiments of the present invention also provide a control device for an energy storage converter, which is used to execute the control method for the energy storage converter provided in any of the above embodiments.

[0112] Specifically, the control device can be integrated inside the energy storage converter product or installed outside the energy storage converter product. Voltage signals (such as the instantaneous value of three-phase grid voltage) can be acquired through voltage sensors, and current signals (such as the instantaneous value of three-phase grid current) can be acquired through current sensors. These signals are then transmitted to the control device, enabling the control device to perform further control based on the acquired voltage and current signals.

[0113] It should be noted that the control device not only executes the control method provided in the embodiments of the present invention, but also executes other control algorithms based on the actual control logic, such as reactive power control method, voltage loop control method, current loop control method and modulation algorithm, so as to ensure the normal operation of the entire energy storage converter.

[0114] Example 4

[0115] Figure 4 This is a schematic diagram of the control device for an energy storage converter according to Embodiment 4 of the present invention. Figure 4 A block diagram of an exemplary apparatus suitable for implementing embodiments of the present invention is shown. Figure 4 The device shown is merely an example and should not impose any limitations on the functionality and scope of use of the embodiments of the present invention. Figure 4 As shown, it includes:

[0116] The acquisition module 401 is used to acquire the instantaneous values ​​of the three-phase power grid voltage and the instantaneous values ​​of the three-phase power grid current;

[0117] Impedance calculation module 402 is used to calculate the equivalent impedance of the power grid based on the instantaneous values ​​of the three-phase power grid voltage and the instantaneous values ​​of the three-phase power grid current;

[0118] The power transmission value calculation module 403 is used to calculate the maximum active power transmission value of the energy storage converter based on the equivalent impedance of the power grid.

[0119] The judgment module 404 is used to determine whether the maximum active power transmission value is less than the initial value of the active power reference command;

[0120] The power reference value calculation module 405 is used to recalculate the active power reference value of the energy storage converter based on the instantaneous value of the three-phase grid voltage, the equivalent impedance of the grid, and the initial value of the active power reference command if the condition is met, and to use the active power reference value as the new active power reference command.

[0121] The holding module 406 is used to maintain the initial value of the current active power reference command unchanged if not otherwise.

[0122] The control device for an energy storage converter provided in this embodiment of the invention can execute the control method for the energy storage converter provided in any embodiment of the invention, and has the corresponding functional modules and beneficial effects of the method.

[0123] Example 5

[0124] Figure 5 This is a schematic diagram of the structure of an energy storage converter system according to Embodiment 5 of the present invention. Figure 5As shown, this embodiment of the invention also provides an energy storage converter system, which includes a control device and an energy storage converter as described in the above embodiments.

[0125] Specifically, the energy storage converter can be either a grid-connected or a network-based energy storage converter. The converter's structure can be cascaded or non-cascaded; no specific limitations are imposed here, and it can be adapted to the actual situation. It should be noted that the specific power rating of the energy storage converter is also not specifically limited.

[0126] Example 6

[0127] Embodiment 4 of the present invention also provides a storage medium containing computer-executable instructions, which, when executed by a computer processor, are used to perform the steps of the control method for the energy storage converter as described above.

[0128] The computer storage medium of this invention can be any combination of one or more computer-readable media. A computer-readable medium can be a computer-readable signal medium or a computer-readable storage medium. A computer-readable storage medium can be, for example,—but not limited to—an electrical, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any combination thereof. More specific examples (a non-exhaustive list) of computer-readable storage media include: an electrical connection having one or more wires, a portable computer disk, a hard disk, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), optical fiber, portable compact disk read-only memory (CD-ROM), optical storage device, magnetic storage device, or any suitable combination thereof. In this document, a computer-readable storage medium can be any tangible medium that contains or stores a program that can be used by or in conjunction with an instruction execution system, apparatus, or device.

[0129] Computer-readable signal media may include data signals propagated in baseband or as part of a carrier wave, carrying computer-readable program code. Such propagated data signals may take various forms, including but not limited to electromagnetic signals, optical signals, or any suitable combination thereof. Computer-readable signal media may also be any computer-readable medium other than computer-readable storage media, capable of sending, propagating, or transmitting programs for use by or in connection with an instruction execution system, apparatus, or device.

[0130] Program code contained on a computer-readable medium may be transmitted using any suitable medium, including—but not limited to—wireless, wire, optical fiber, RF, etc., or any suitable combination thereof.

[0131] Computer program code for performing the operations of this invention can be written in one or more programming languages ​​or a combination thereof, including object-oriented programming languages ​​such as Java, Smalltalk, and C++, as well as conventional procedural programming languages ​​such as "C" or similar programming languages. The program code can be executed entirely on the user's computer, partially on the user's computer, as a standalone software package, partially on the user's computer and partially on a remote computer, or entirely on a remote computer or server. In cases involving remote computers, the remote computer can be connected to the user's computer via any type of network—including a local area network (LAN) or a wide area network (WAN)—or can be connected to an external computer (e.g., via the Internet using an Internet service provider).

[0132] Note that the above description is merely a preferred embodiment of the present invention and the technical principles employed. Those skilled in the art will understand that the present invention is not limited to the specific embodiments described herein, and various obvious changes, readjustments, and substitutions can be made without departing from the scope of protection of the present invention. Therefore, although the present invention has been described in detail through the above embodiments, the present invention is not limited to the above embodiments, and may include many other equivalent embodiments without departing from the concept of the present invention, the scope of which is determined by the scope of the appended claims.

Claims

1. A control method for an energy storage converter, characterized in that, include: Obtain the instantaneous values ​​of the three-phase grid voltage and the instantaneous values ​​of the three-phase grid current; The equivalent impedance of the power grid is calculated based on the instantaneous values ​​of the three-phase grid voltage and the instantaneous values ​​of the three-phase grid current. The maximum active power transmission value of the energy storage converter is calculated based on the equivalent impedance of the power grid. Determine whether the maximum active power transmission value is less than the initial value of the active power reference command; If so, the active power reference value of the energy storage converter is recalculated based on the instantaneous value of the three-phase grid voltage, the equivalent impedance of the grid, and the initial value of the active power reference command, and the active power reference value is used as the new active power reference command. If not, then keep the initial value of the current active power reference command unchanged.

2. The method according to claim 1, characterized in that, The calculation of the maximum active power transmission value of the energy storage converter based on the equivalent impedance of the power grid includes: Obtain the instantaneous three-phase voltage values ​​on the AC side of the energy storage converter; The phase angle difference between the instantaneous three-phase voltage on the AC side of the energy storage converter and the instantaneous three-phase grid voltage when the maximum active power transmitted by the energy storage converter is calculated based on the equivalent impedance of the grid. The maximum active power transmission value of the energy storage converter is calculated based on the phase angle difference.

3. The method according to claim 2, characterized in that, When calculating the maximum active power transmitted by the energy storage converter based on the equivalent impedance of the power grid, the phase angle difference between the instantaneous three-phase voltage on the AC side of the energy storage converter and the instantaneous three-phase grid voltage includes: Obtain the current operating state of the energy storage converter, including charging or discharging; Based on the operating state, the phase angle difference δ between the instantaneous three-phase voltage on the AC side of the energy storage converter and the instantaneous three-phase grid voltage is calculated according to the following formula. pm : Wherein, the grid equivalent impedance of the energy storage converter is Z g Z g =X g +jR g X g R is the grid equivalent inductive reactance of the energy storage converter. g The grid equivalent resistance of the energy storage converter is given.

4. The method according to claim 3, characterized in that, The calculation of the maximum active power transmission value of the energy storage converter based on the phase angle difference includes: The maximum active power transmission value P of the energy storage converter is calculated according to the following formula. max : Among them, V cm V represents the amplitude of the instantaneous three-phase voltage on the AC side of the energy storage converter. gm The amplitude of the instantaneous voltage of the three-phase power grid.

5. The method according to claim 1, characterized in that, The step of recalculating the active power reference value of the energy storage converter based on the instantaneous value of the three-phase grid voltage, the equivalent impedance of the grid, and the initial value of the active power reference command includes: Recalculate the active power reference value P of the energy storage converter according to the following formula. ref : Among them, V cm V represents the amplitude of the instantaneous three-phase voltage on the AC side of the energy storage converter. gm V represents the amplitude of the instantaneous voltage of the three-phase power grid. rated P is the amplitude of the three-phase rated voltage when the energy storage converter is operating normally. ref0 The initial value of the active power reference command for the energy storage converter is Z, and the grid equivalent impedance of the energy storage converter is Z. g Z g =X g +jR g X g R is the grid equivalent inductive reactance of the energy storage converter. g The grid equivalent resistance of the energy storage converter is given.

6. The method according to claim 1, characterized in that, After determining that the maximum active power transmission value is less than the initial value of the active power reference command, before recalculating the active power reference value of the energy storage converter based on the instantaneous value of the three-phase grid voltage, the equivalent impedance of the grid, and the initial value of the active power reference command, and before using the active power reference value as the new active power reference command, the method further includes: Start timing; Determine whether the timing time has reached the preset time, and when the timing time has reached the preset time, recalculate the active power reference value of the energy storage converter based on the instantaneous value of the three-phase grid voltage, the equivalent impedance of the grid, and the initial value of the active power reference command.

7. The method according to claim 1, characterized in that, The instruction to use the active power reference value as the new active power reference includes: The active power reference value is processed according to the following formula before being used as the new active power reference command P. set : Where n is an integer, and 1≤n≤9, P ref P is the current value of the active power reference value. ref_1 P is the value at the previous sampling time of the active power reference value. ref_n This represents the value of the active power reference value at the previous n sampling times.

8. A control device for an energy storage converter, characterized in that, include: The acquisition module is used to acquire the instantaneous values ​​of the three-phase grid voltage and the instantaneous values ​​of the three-phase grid current. The impedance calculation module is used to calculate the equivalent impedance of the power grid based on the instantaneous values ​​of the three-phase power grid voltage and the instantaneous values ​​of the three-phase power grid current. The power transmission value calculation module is used to calculate the maximum active power transmission value of the energy storage converter based on the equivalent impedance of the power grid. The judgment module is used to determine whether the maximum active power transmission value is less than the initial value of the active power reference command; The power reference value calculation module is used to recalculate the active power reference value of the energy storage converter based on the instantaneous value of the three-phase grid voltage, the equivalent impedance of the grid, and the initial value of the active power reference command if the condition is met, and to use the active power reference value as the new active power reference command. The holding module is used to maintain the initial value of the current active power reference command unchanged if otherwise.

9. An energy storage converter system, characterized in that, include: Control device for the energy storage converter as described in claim 8; Energy storage converter.

10. A storage medium containing computer-executable instructions, characterized in that, The computer-executable instructions, when executed by a computer processor, are used to perform a control method for the energy storage converter as described in any one of claims 1-7.

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