Control method and system for suppressing broadband oscillation of energy storage system

Abstract

The invention discloses a control method and system for suppressing broadband oscillation of an energy storage system. According to the method, a self-adaptive control branch based on the phase locking principle is introduced into a current control loop of the energy storage converter, the oscillation frequency in a power grid is identified in real time, and a corresponding additional internal electromotive force signal is generated and superposed into an original control signal, so that the equivalent impedance characteristic of the energy storage converter is dynamically optimized, and the energy storage converter is optimized. And effective damping of broadband oscillation is realized. The method can adaptively track the changing oscillation frequency, does not need to modify the structure of a main circuit, can significantly enhance the system damping, effectively inhibits the broadband oscillation in a power electronic power grid, improves the stability of the power grid through the upgrade of a control algorithm, and has the advantages of low cost, easy integration and high adaptability.

Description

Technical Field

[0001] This invention belongs to the field of energy storage system control technology, and particularly relates to a control method and system for suppressing wideband oscillations in energy storage systems. Background Technology

[0002] With the large-scale grid connection of renewable energy sources such as wind and solar power through power electronic converters, and the widespread application of high-voltage direct current (HVDC) transmission technology, the dynamic characteristics of modern power systems are becoming increasingly "power electronic." While power electronic devices bring control flexibility, their rapid control dynamics and complex interactions with the grid also introduce new stability challenges, namely, broadband oscillations. These oscillations can cover a wide frequency band from subsynchronous to high frequencies, and their mechanisms are more complex than those dominated by traditional synchronous machines, seriously threatening the safe and stable operation of the power grid.

[0003] Existing technologies for suppressing oscillations mainly include optimizing control parameters, adding control branches, or configuring additional damping devices (such as static synchronous compensators). However, these methods have significant limitations: the strategies for optimizing control parameters and adjusting control branches are highly dependent on specific system operating conditions, and the suppression effect may weaken or even fail when the grid structure or operating point changes; while modifying the global controller for wind farms and other power stations containing a large number of power electronic devices is costly. Configuring dedicated damping devices, although not dependent on a specific environment, also increases additional construction and maintenance costs.

[0004] Energy storage systems, especially battery energy storage power stations, are increasingly widely used in power grids due to their rapid active / reactive power regulation capabilities. As the core interface, the energy storage converter's dynamic characteristics directly affect its interaction with the power grid. Optimizing its control strategy to enable it not only to perform normal charging and discharging functions but also to actively dampen system oscillations would be an economical and effective solution. Currently, the control of energy storage converters mainly focuses on the power and current control of the inner and outer loops. Its inherent control characteristics may exhibit negative damping in certain frequency bands, thus exacerbating rather than suppressing oscillations. Therefore, there is an urgent need for a control method that can adapt to the system oscillation frequency and effectively enhance the positive damping characteristics of the energy storage system. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of existing technologies and provide a control method and system for suppressing broadband oscillations in energy storage systems. This method aims to effectively and adaptively suppress broadband oscillations in power systems by introducing an adaptive control branch based on phase-locked loop principles into the current control loop of the energy storage converter without altering its main circuit structure.

[0006] In a first aspect, the present invention provides a control method for suppressing broadband oscillations in an energy storage system, comprising: Obtain the feedback current signal from the AC side of the energy storage converter; Based on the phase-locked loop principle, at least one target oscillation frequency is adaptively identified from the feedback current signal; Based on the target oscillation frequency, an additional internal electromotive force signal is generated through a preset optimized control branch; The additional internal electromotive force signal is superimposed on the original control signal of the energy storage converter to change the equivalent impedance characteristics of the energy storage converter, thereby suppressing broadband oscillations in the power system.

[0007] Secondly, the present invention provides a control system for suppressing broadband oscillations in an energy storage system, comprising: The acquisition module is configured to acquire the feedback current signal from the AC side of the energy storage converter; The identification module is configured to adaptively identify at least one target oscillation frequency from the feedback current signal based on the phase-locked loop principle. The generation module is configured to generate an additional internal electromotive force signal based on the target oscillation frequency through a preset optimized control branch. The superposition module is configured to superimpose the additional internal electromotive force signal onto the original control signal of the energy storage converter in order to change the equivalent impedance characteristics of the energy storage converter, thereby suppressing broadband oscillations in the power system.

[0008] Thirdly, an electronic device is provided, comprising: at least one processor, and a memory communicatively connected to the at least one processor, wherein the memory stores instructions executable by the at least one processor, the instructions being executed by the at least one processor to enable the at least one processor to perform the steps of the control method for suppressing broadband oscillations in an energy storage system according to any embodiment of the present invention.

[0009] Fourthly, the present invention also provides a computer-readable storage medium having a computer program stored thereon, wherein when the program instructions are executed by a processor, the processor performs the steps of the control method for suppressing broadband oscillations in an energy storage system according to any embodiment of the present invention.

[0010] The control method and system for suppressing broadband oscillations in energy storage systems disclosed in this application add an adaptive control branch based on the phase-locked loop principle to the current control loop of the energy storage converter to optimize the dynamic characteristics of the energy storage power station. By optimizing the dynamic characteristics of the energy storage converter, broadband oscillations in the power system can be effectively suppressed. Attached Figure Description

[0011] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the following description of the embodiments will be briefly introduced. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0012] Figure 1 A flowchart illustrating a control method for suppressing broadband oscillations in an energy storage system, as provided in an embodiment of the present invention; Figure 2 This is a control block diagram of an energy storage converter provided in an embodiment of the present invention; Figure 3 This is a schematic diagram of a dynamic model of an energy storage converter provided in an embodiment of the present invention; Figure 4 This is a schematic diagram of the equivalent impedance frequency response curve of an energy storage converter provided in an embodiment of the present invention; Figure 5 This is a schematic diagram of an optimal control strategy provided in an embodiment of the present invention; Figure 6 This is a structural block diagram of a control system for suppressing broadband oscillations in an energy storage system, provided in an embodiment of the present invention. Figure 7 This is a schematic diagram of the structure of an electronic device provided in an embodiment of the present invention. Detailed Implementation

[0013] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0014] Please see Figure 1 The diagram shows a flowchart of a control method for suppressing broadband oscillations in an energy storage system according to this application.

[0015] like Figure 1 As shown, the control method for suppressing broadband oscillations in an energy storage system specifically includes the following steps: Step S101: Obtain the feedback current signal from the AC side of the energy storage converter.

[0016] Step S102: Based on the phase-locked loop principle, at least one target oscillation frequency is adaptively identified from the feedback current signal.

[0017] In this step, the oscillation component in the feedback current signal is tracked by a phase-locked loop, and its instantaneous angular frequency is calculated. The instantaneous angular frequency The calculation formula is: , In the formula, , To identify the angular frequencies of the different oscillation components, These are the corresponding weighting coefficients.

[0018] Step S103: Based on the target oscillation frequency, an additional internal electromotive force signal is generated through a preset optimized control branch.

[0019] In this step, in the stationary coordinate system, based on the feedback current signal... High frequency components of the axis , High frequency components of the axis and virtual resistance parameters ,calculate Axis intermediate variables and Axis intermediate variables The stationary coordinate system is... Coordinate system;

[0020] According to claim 1, the control method for suppressing broadband oscillations in an energy storage system is characterized in that generating an additional internal electromotive force signal based on the target oscillation frequency through a preset optimized control branch includes: In a stationary coordinate system, based on the feedback current signal High frequency components of the axis , High frequency components of the axis and virtual resistance parameters ,calculate Axis intermediate variables and Axis intermediate variables The stationary coordinate system is... Coordinate system; Using coordinate transformation, the Axis intermediate variables and Axis intermediate variables Transforming to a synchronous rotating coordinate system yields an additional internal electromotive force (EMF) signal, which includes the intermediate variable along the d-axis. and q-axis intermediate variable The synchronous rotating coordinate system is the dq coordinate system.

[0021] It should be noted that, Axis intermediate variables The above Axis intermediate variables The dynamic process is represented by the following differential equation: , In the formula, To optimize the time constant of the control branch.

[0022] Among them, the intermediate variable of the d-axis q-axis intermediate variable The dynamic process is represented by the following state-space equations: , In the formula, , These are the d-axis high-frequency component and q-axis high-frequency component of the feedback current signal, respectively.

[0023] Step S104: The additional internal electromotive force signal is superimposed on the original control signal of the energy storage converter to change the equivalent impedance characteristics of the energy storage converter, thereby suppressing wideband oscillations in the power system.

[0024] In summary, the method of this application adds an adaptive control branch based on the phase-locked loop principle to the current control loop of the energy storage converter to optimize the dynamic characteristics of the energy storage power station. By optimizing the dynamic characteristics of the energy storage converter, broadband oscillations in the power system can be effectively suppressed.

[0025] In one specific embodiment, the control method for suppressing broadband oscillations in the energy storage system is as follows: To analyze the mid-to-high frequency dynamics of the energy storage converter, a dynamic model should be established. Considering that the mid-to-high frequency dynamics are mainly affected by the current control loop, the dynamics of the external control loop can be ignored. Since the control bandwidth of the PLL is typically tens of hertz, which differs significantly from the current loop, its dynamic process is neglected in this part. Under the above assumptions, the mathematical model used to evaluate the high-frequency dynamics of the system is as follows: Figure 3 As shown. Transfer function and This refers to the filtering stages caused by signal sampling and conditioning in the voltage and current sampling loops. They can be described as follows: (1) in, and It is the cutoff angular frequency of the low-pass filter. The time delay caused by digital control and PWM modulation can be described as follows: (2) In this section, the dynamic model of the energy storage converter is established in a stationary coordinate system. For convenience, PI control in the rotating dq coordinate system is equivalent to proportional resonance (PR) control in the stationary coordinate system. For a symmetrical three-phase system, it can be represented as a complex vector, and the dynamic relationship between different electrical quantities can be described by a complex transfer function. Therefore, it can be simplified to... Figure 3 .

[0026] in, The transfer function of the current regulator in the stationary coordinate system can be expressed as: in, and These are the proportional and integral parameters, respectively.

[0027] AC side equivalent impedance of energy storage converter It can be represented as: (4) Figure 4 This shows the Bode plot of the equivalent impedance and the frequency relationship between the real part of the impedance. For a passive network, the system can operate stably when the real part of each impedance is positive. From Figure 4 As can be seen, the real part of the equivalent impedance is very small in the mid-to-high frequency range and generates negative damping at high frequencies. To enhance the damping effect of the energy storage converter on oscillations, the relevant control strategy should be optimized to improve the impedance characteristics. This optimized control strategy is further discussed.

[0028] Optimal control strategy for energy storage converter: The dynamic characteristics of energy storage converters are primarily influenced by the control algorithm and can be improved by adjusting the control strategy. Since mid-to-high frequency oscillations in power systems are broadband, damping in the relevant frequency bands needs to be increased to suppress them. Considering that the oscillation modes in the mid-to-high frequency band are not fixed, the optimal control strategy should be able to adapt to different frequencies.

[0029] Figure 5 The optimal control strategy proposed in this invention is demonstrated. Feedback current is fed into the internal electromotive force, which improves the mid-to-high frequency dynamic characteristics of the energy storage converter. Transformation matrix. and It can be represented as: (5) variable and The additional internal electromotive force caused by the optimal control branch can be expressed as: (6) Differentiating both sides of the above equation, we get: (7) For the resonant frequency of the energy storage converter, resonance may occur at one point or at two points. Therefore, the general case should be considered: (8) (9) Furthermore, current can be expressed as and ; (10) Substituting equation (7-10) into equation (6), we get: (11) and and It can be written in matrix form: (12) Among them, matrix and Satisfying the formula: (13) (14) The angular frequency is calculated using the current angular frequency in the PLL controller. Based on the above analysis using a phase-locked loop, the optimal control strategy proposed in this invention can track the frequency of the oscillating component in the feedback current and further adaptively adjust the center frequency of the oscillating component in the feedback current, achieving adaptive suppression of broadband oscillations.

[0030] Please see Figure 6 The diagram shows a structural block diagram of a control system for suppressing broadband oscillations in an energy storage system according to this application.

[0031] like Figure 6 As shown, the control system 200 for suppressing broadband oscillations in the energy storage system includes an acquisition module 210, an identification module 220, a generation module 230, and a superposition module 240.

[0032] The acquisition module 210 is configured to acquire the feedback current signal on the AC side of the energy storage converter; the identification module 220 is configured to adaptively identify at least one target oscillation frequency from the feedback current signal based on the phase-locked loop principle; the generation module 230 is configured to generate an additional internal electromotive force signal according to the target oscillation frequency through a preset optimized control branch; and the superposition module 240 is configured to superimpose the additional internal electromotive force signal onto the original control signal of the energy storage converter to change the equivalent impedance characteristics of the energy storage converter, thereby suppressing broadband oscillations in the power system.

[0033] It should be understood that Figure 6 The modules and references described in the document Figure 1 The steps described in the text correspond to those in the method described above. Therefore, the operations, features, and corresponding technical effects described above also apply to the method described in the text. Figure 6 The various modules in the document will not be described in detail here.

[0034] In other embodiments, the present invention also provides a computer-readable storage medium having a computer program stored thereon, wherein when the program instructions are executed by a processor, the processor performs the control method for suppressing broadband oscillations in the energy storage system in any of the above method embodiments. In one embodiment, the computer-readable storage medium of the present invention stores computer-executable instructions, which are configured as follows: Obtain the feedback current signal from the AC side of the energy storage converter; Based on the phase-locked loop principle, at least one target oscillation frequency is adaptively identified from the feedback current signal; Based on the target oscillation frequency, an additional internal electromotive force signal is generated through a preset optimized control branch; The additional internal electromotive force signal is superimposed on the original control signal of the energy storage converter to change the equivalent impedance characteristics of the energy storage converter, thereby suppressing broadband oscillations in the power system.

[0035] Computer-readable storage media may include a stored program area and a stored data area, wherein the stored program area may store an operating system and an application program required for at least one function; the stored data area may store data created based on the use of the control system for suppressing broadband oscillations in the energy storage system, etc. Furthermore, the computer-readable storage medium may include high-speed random access memory, and may also include memory, such as at least one disk storage device, flash memory device, or other non-volatile solid-state storage device. In some embodiments, the computer-readable storage medium may optionally include memory remotely disposed relative to a processor, which can be connected via a network to the control system for suppressing broadband oscillations in the energy storage system. Examples of such networks include, but are not limited to, the Internet, corporate intranets, local area networks, mobile communication networks, and combinations thereof.

[0036] Figure 7 This is a schematic diagram of the structure of the electronic device provided in the embodiment of the present invention, such as... Figure 7 As shown, the device includes a processor 310 and a memory 320. The electronic device may also include an input device 330 and an output device 340. The processor 310, memory 320, input device 330, and output device 340 can be connected via a bus or other means. Figure 7Taking a bus connection as an example, the memory 320 is the computer-readable storage medium described above. The processor 310 executes various server functions and data processing by running non-volatile software programs, instructions, and modules stored in the memory 320, thereby implementing the control method for suppressing broadband oscillations in the energy storage system described in the above embodiment. The input device 330 can receive input digital or character information and generate key signal inputs related to user settings and function control of the control system for suppressing broadband oscillations in the energy storage system. The output device 340 may include a display screen or other display device.

[0037] The aforementioned electronic device can execute the method provided in the embodiments of the present invention, and has the corresponding functional modules and beneficial effects for executing the method. Technical details not described in detail in this embodiment can be found in the method provided in the embodiments of the present invention.

[0038] In one implementation, the above-described electronic device is applied in a control system for suppressing broadband oscillations in an energy storage system, and is used as a client. It includes: at least one processor; and a memory communicatively connected to the at least one processor; wherein the memory stores instructions executable by the at least one processor, which, when executed by the at least one processor, enable the at least one processor to: Obtain the feedback current signal from the AC side of the energy storage converter; Based on the phase-locked loop principle, at least one target oscillation frequency is adaptively identified from the feedback current signal; Based on the target oscillation frequency, an additional internal electromotive force signal is generated through a preset optimized control branch; The additional internal electromotive force signal is superimposed on the original control signal of the energy storage converter to change the equivalent impedance characteristics of the energy storage converter, thereby suppressing broadband oscillations in the power system.

[0039] Through the above description of the embodiments, those skilled in the art can clearly understand that each embodiment can be implemented by means of software plus necessary general-purpose hardware platforms, and of course, it can also be implemented by hardware. Based on this understanding, the above technical solutions, in essence or the part that contributes to the prior art, can be embodied in the form of a software product. This computer software product can be stored in a computer-readable storage medium, such as ROM / RAM, magnetic disk, optical disk, etc., including several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute the methods of various embodiments or some parts of embodiments.

[0040] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A control method for suppressing broadband oscillations in an energy storage system, characterized in that, include: Obtain the feedback current signal from the AC side of the energy storage converter; Based on the phase-locked loop principle, at least one target oscillation frequency is adaptively identified from the feedback current signal; Based on the target oscillation frequency, an additional internal electromotive force signal is generated through a preset optimized control branch; The additional internal electromotive force signal is superimposed on the original control signal of the energy storage converter to change the equivalent impedance characteristics of the energy storage converter, thereby suppressing broadband oscillations in the power system.

2. The control method for suppressing broadband oscillations in an energy storage system according to claim 1, characterized in that, The adaptive identification of at least one target oscillation frequency from the feedback current signal based on the phase-locked loop principle includes: The oscillating component in the feedback current signal is tracked by a phase-locked loop, and its instantaneous angular frequency is calculated. The instantaneous angular frequency The calculation formula is: ， In the formula, , To identify the angular frequencies of the different oscillation components, These are the corresponding weighting coefficients.

3. The control method for suppressing broadband oscillations in an energy storage system according to claim 1, characterized in that, The step of generating an additional internal electromotive force signal based on the target oscillation frequency through a preset optimized control branch includes: In a stationary coordinate system, based on the feedback current signal High frequency components of the axis , High frequency components of the axis and virtual resistance parameters ,calculate Axis intermediate variables and Axis intermediate variables The stationary coordinate system is... Coordinate system; Using coordinate transformation, the Axis intermediate variables and Axis intermediate variables Transforming to a synchronous rotating coordinate system yields an additional internal electromotive force (EMF) signal, which includes the intermediate variable along the d-axis. and q-axis intermediate variable The synchronous rotating coordinate system is the dq coordinate system.

4. The control method for suppressing broadband oscillations in an energy storage system according to claim 3, characterized in that, in, The Axis intermediate variables The above Axis intermediate variables The dynamic process is represented by the following differential equation: ， In the formula, To optimize the time constant of the control branch.

5. The control method for suppressing broadband oscillations in an energy storage system according to claim 3, characterized in that, in, The intermediate variable of the d-axis The q-axis intermediate variable The dynamic process is represented by the following state-space equations: ， In the formula, , These are the d-axis high-frequency component and the q-axis high-frequency component of the feedback current signal, respectively.

6. A control system for suppressing broadband oscillations in an energy storage system, characterized in that, include: The acquisition module is configured to acquire the feedback current signal from the AC side of the energy storage converter; The identification module is configured to adaptively identify at least one target oscillation frequency from the feedback current signal based on the phase-locked loop principle. The generation module is configured to generate an additional internal electromotive force signal based on the target oscillation frequency through a preset optimized control branch. The superposition module is configured to superimpose the additional internal electromotive force signal onto the original control signal of the energy storage converter in order to change the equivalent impedance characteristics of the energy storage converter, thereby suppressing broadband oscillations in the power system.

7. An electronic device, characterized in that, include: At least one processor, and a memory communicatively connected to the at least one processor, wherein the memory stores instructions executable by the at least one processor to enable the at least one processor to perform the method according to any one of claims 1 to 5.

8. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the program is executed by the processor, it implements the method described in any one of claims 1 to 5.

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