A method for double droop control of energy storage converter and related equipment

Abstract

The application discloses a kind of energy storage converter double droop control method and related equipment, method includes: three-phase voltage and three-phase inductance current are converted to voltage component and current component in two-phase stationary coordinate system, according to it, positive sequence, negative sequence separation is carried out, and positive sequence proportional control parameter and negative sequence proportional control parameter are calculated;According to the positive sequence voltage component, the positive sequence current component and the positive sequence proportional control parameter obtained by separation are carried out positive sequence droop control, and positive sequence voltage control signal is obtained;According to the negative sequence voltage component, the negative sequence current component and the negative sequence proportional control parameter obtained by separation are carried out negative sequence droop control, and negative sequence voltage control signal is obtained;Negative sequence voltage control signal and positive sequence voltage control signal are combined, and final voltage control signal is obtained.The application can reasonably allocate the capacity allocation of positive sequence support capability and negative sequence suppression capability, can protect energy storage converter hardware, and has voltage correction ability to grid connection point, can be widely applied in energy storage converter control technical field.

Description

Technical Field

[0001] This application relates to the field of energy storage converter control technology, and in particular to a dual droop control method and related equipment for an energy storage converter. Background Technology

[0002] With the large-scale grid connection of new energy equipment, the structure and operating characteristics of the power system have undergone profound changes, placing higher demands on the stability and reliability of power grid operation. In actual power grid operation, the power grid is prone to voltage imbalance due to natural environmental disturbances (such as falling branches and biological damage) and line short circuits. This imbalance not only affects the normal operation of energy storage converters but also leads to a decline in power quality and a reduction in system operating efficiency.

[0003] Existing technologies for addressing grid imbalance issues mainly fall into two categories: one type eliminates negative-sequence current to maintain grid-connected current balance, but this method fails to consider that current regulation can further exacerbate grid-connected voltage imbalance under line fault conditions, resulting in poor applicability during grid line fault scenarios; the other type eliminates negative-sequence voltage to maintain grid-connected voltage balance, but this method leads to grid-connected current imbalance. When the grid voltage imbalance is high, the negative-sequence current is prone to exceed its rated value, thereby causing damage to the energy storage converter hardware. Neither of these methods adequately considers the positive-sequence voltage drop caused by grid line faults, lacks effective support for positive-sequence voltage, and fails to achieve a reasonable allocation of capacity between positive-sequence voltage support and negative-sequence voltage suppression. Consequently, they cannot ensure the effective correction capability of the grid-connected voltage while guaranteeing the hardware safety of the energy storage converter. Summary of the Invention

[0004] The main objective of this application is to propose a dual droop control method and related equipment for an energy storage converter, which can reasonably allocate the capacity distribution of positive sequence support capability and negative sequence suppression capability, protect the hardware of the energy storage converter, and has the ability to correct the voltage at the grid connection point.

[0005] To achieve the above objectives, one aspect of this application proposes a dual droop control method for an energy storage converter, comprising: Collect the three-phase voltage and three-phase inductor current at the grid connection point of the energy storage converter; The three-phase voltage and the three-phase inductor current are converted to a two-phase stationary coordinate system to obtain the voltage and current components in the two-phase stationary coordinate system. Based on the voltage and current components in the two-phase stationary coordinate system, the three-phase voltage and the three-phase inductor current are separated into positive and negative sequences to obtain positive sequence voltage components, negative sequence voltage components, positive sequence current components, and negative sequence current components. Calculate the current amplitude of the energy storage converter, and calculate the positive-sequence proportional control parameter and the negative-sequence proportional control parameter based on the current amplitude; Positive sequence droop control is performed based on the positive sequence voltage component, the positive sequence current component, and the positive sequence proportional control parameter to obtain a positive sequence voltage control signal. Negative sequence droop control is performed based on the negative sequence voltage component, the negative sequence current component, and the negative sequence proportional control parameter to obtain a negative sequence voltage control signal. The negative-sequence voltage control signal and the positive-sequence voltage control signal are combined to obtain the final voltage control signal.

[0006] In some embodiments, separating the three-phase voltage and the three-phase inductor current into positive and negative sequences based on the voltage and current components in the two-phase stationary coordinate system to obtain positive-sequence voltage components, negative-sequence voltage components, positive-sequence current components, and negative-sequence current components includes: Obtain an orthogonal operator, wherein the orthogonal operator refers to performing a phase delay on the signals of the three-phase voltage and the three-phase inductor current; Based on the orthogonal operator and the voltage components in the two-phase stationary coordinate system, calculate the positive sequence voltage component and the negative sequence voltage component; Based on the orthogonal operator and the current components in the two-phase stationary coordinate system, calculate the positive sequence current component and the negative sequence current component. In some embodiments, after separating the three-phase voltage and the three-phase inductor current into positive and negative sequences based on the voltage and current components in the two-phase stationary coordinate system, the method further includes: The positive-sequence voltage component and the negative-sequence voltage component are respectively input into the phase-locked loop; The positive sequence voltage component is phase-locked by the phase-locked loop to obtain the positive sequence phase; The negative sequence voltage component is phase-locked by the phase-locked loop to obtain the negative sequence phase. In some embodiments, the method further includes: Based on the positive sequence phase, Park transformation is performed on the positive sequence current component and the positive sequence voltage component to obtain the measured values ​​of the d-axis positive sequence voltage, q-axis positive sequence voltage, d-axis positive sequence current, and q-axis positive sequence current in the two-phase rotating coordinate system. Based on the negative sequence phase, Park transform is performed on the negative sequence current component and the negative sequence voltage component to obtain the measured values ​​of the d-axis negative sequence voltage, q-axis negative sequence voltage, d-axis negative sequence current, and q-axis negative sequence current in the two-phase rotating coordinate system. In some embodiments, calculating the positive-sequence proportional control parameter and the negative-sequence proportional control parameter based on the current amplitude includes: Calculate the difference between the current amplitude and the preset rated current amplitude, and input the difference into the first PI controller to obtain the control reference value; Calculate the sum of the measured values ​​of the positive-sequence voltage and the negative-sequence voltage on the d-axis, and calculate the positive-sequence distribution ratio based on the ratio of the measured value of the positive-sequence voltage on the d-axis to the sum. Calculate the negative allocation ratio based on the positive allocation ratio; Multiply the positive sequence allocation ratio by the control reference value to obtain the positive sequence proportional control parameter; Multiply the negative order allocation ratio by the control reference value to obtain the negative order proportional control parameter. In some embodiments, the step of performing positive-sequence droop control based on the positive-sequence voltage component, the positive-sequence current component, and the positive-sequence proportional control parameter to obtain a positive-sequence voltage control signal includes: The measured values ​​of the positive sequence voltage on the d-axis are filtered to obtain the filtered measured values ​​of the positive sequence voltage on the d-axis. The measured value of the filtered d-axis positive sequence voltage is multiplied by the positive sequence proportional control parameter to calculate the reference value of the q-axis positive sequence current. The difference between the reference value of the q-axis positive sequence current and the measured value of the q-axis positive sequence current is input to the second PI controller to generate a q-axis positive sequence voltage control signal in a two-phase rotating coordinate system. The difference between the preset d-axis positive sequence current reference value and the measured d-axis positive sequence current value is input to the third PI controller to generate the d-axis positive sequence voltage control signal in the two-phase rotating coordinate system. Based on the positive sequence phase, the q-axis positive sequence voltage control signal and the d-axis positive sequence voltage control signal are converted into positive sequence voltage control signals in the three-phase coordinate system.

[0007] In some embodiments, the step of performing negative-sequence droop control based on the negative-sequence voltage component, the negative-sequence current component, and the negative-sequence proportional control parameter to obtain a negative-sequence voltage control signal includes: The measured values ​​of the negative sequence voltage along the d-axis are filtered to obtain the filtered measured values ​​of the negative sequence voltage along the d-axis. The measured value of the filtered d-axis negative sequence voltage is multiplied by the proportional control parameter of the negative sequence to calculate the reference value of the q-axis negative sequence current. The difference between the reference value of the q-axis negative sequence current and the measured value of the q-axis negative sequence current is input to the fourth PI controller to generate the q-axis negative sequence voltage control signal in the two-phase rotating coordinate system. The difference between the preset d-axis negative sequence current reference value and the measured d-axis negative sequence current value is input to the fifth PI controller to generate the d-axis negative sequence voltage control signal in the two-phase rotating coordinate system. Based on the negative sequence phase, the q-axis negative sequence voltage control signal and the d-axis negative sequence voltage control signal are converted into negative sequence voltage control signals in the three-phase coordinate system.

[0008] To achieve the above objectives, another aspect of this application provides a dual droop control device for an energy storage converter, the device comprising: The data acquisition module is used to acquire the three-phase voltage and three-phase inductor current at the grid connection point of the energy storage converter; The coordinate transformation module is used to transform the three-phase voltage and the three-phase inductor current to a two-phase stationary coordinate system to obtain the voltage components and current components in the two-phase stationary coordinate system. The positive and negative sequence separation module is used to separate the three-phase voltage and the three-phase inductor current into positive and negative sequences based on the voltage and current components in the two-phase stationary coordinate system, to obtain positive sequence voltage components, negative sequence voltage components, positive sequence current components, and negative sequence current components. The proportional control parameter calculation module is used to calculate the current amplitude of the energy storage converter, and to calculate the positive-sequence proportional control parameters and the negative-sequence proportional control parameters based on the current amplitude. The positive sequence droop control module is used to perform positive sequence droop control based on the positive sequence voltage component, the positive sequence current component and the positive sequence proportional control parameter to obtain a positive sequence voltage control signal. The negative sequence droop control module is used to perform negative sequence droop control based on the negative sequence voltage component, the negative sequence current component and the negative sequence proportional control parameter to obtain a negative sequence voltage control signal. The signal merging module is used to merge the negative sequence voltage control signal and the positive sequence voltage control signal to obtain the final voltage control signal.

[0009] To achieve the above objectives, another aspect of this application provides an electronic device, which includes a memory and a processor. The memory stores a computer program, and the processor executes the computer program to implement the method described above.

[0010] To achieve the above objectives, another aspect of the embodiments of this application proposes a computer-readable storage medium storing a computer program that, when executed by a processor, implements the methods described above.

[0011] This application also discloses a computer program product or computer program, which includes computer instructions stored in a computer-readable storage medium. A processor of a computer device can read the computer instructions from the computer-readable storage medium and execute the computer instructions, causing the computer device to perform the aforementioned method.

[0012] The embodiments of this application include at least the following beneficial effects: This application provides a dual droop control method for an energy storage converter. This method first collects the three-phase voltage and three-phase inductor current at the grid connection point of the energy storage converter; converts the three-phase voltage and three-phase inductor current to a two-phase stationary coordinate system to obtain voltage and current components in the two-phase stationary coordinate system; separates the three-phase voltage and the three-phase inductor current into positive and negative sequences based on the voltage and current components in the two-phase stationary coordinate system to obtain positive-sequence voltage components, negative-sequence voltage components, positive-sequence current components, and negative-sequence current components; calculates the current amplitude of the energy storage converter, and calculates the positive-sequence proportional control parameters and negative-sequence proportional control parameters based on the current amplitude; performs positive-sequence droop control based on the positive-sequence voltage components, positive-sequence current components, and the positive-sequence proportional control parameters to obtain a positive-sequence voltage control signal; performs negative-sequence droop control based on the negative-sequence voltage components, negative-sequence current components, and negative-sequence proportional control parameters to obtain a negative-sequence voltage control signal; and combines the negative-sequence voltage control signal and the positive-sequence voltage control signal to obtain the final voltage control signal. By calculating the current amplitude of the energy storage converter and dynamically calculating the positive-sequence and negative-sequence proportional control parameters based on this current amplitude, a reasonable allocation of capacity between positive-sequence voltage support and negative-sequence voltage suppression is achieved. Furthermore, positive-sequence droop control is implemented in the positive-sequence part in conjunction with the positive-sequence proportional control parameters, and negative-sequence droop control is implemented in the negative-sequence part in conjunction with the negative-sequence proportional control parameters. By controlling the positive-sequence voltage component and the negative-sequence voltage component separately, it is possible to ensure the voltage correction capability at the grid connection point while ensuring the hardware safety of the energy storage converter when voltage imbalance is caused by grid line faults. Attached Figure Description

[0013] Figure 1 This is a schematic diagram of an implementation environment provided in an embodiment of this application; Figure 2 This is a flowchart of a dual droop control method for an energy storage converter provided in an embodiment of this application; Figure 3 This is a schematic diagram of the faulty power grid and energy storage converter control section provided in the embodiments of this application; Figure 4 This is a schematic diagram of the orthogonal droop control provided in an embodiment of this application; Figure 5 This is a schematic diagram of negative order droop control provided in an embodiment of this application; Figure 6 This is a waveform diagram of grid-connected current and voltage without positive and negative sequence control provided in the embodiments of this application; Figure 7 This is a positive sequence voltage component diagram without positive and negative sequence control provided in the embodiments of this application; Figure 8 This is a grid-connected current and voltage waveform diagram with added positive and negative sequence control provided in an embodiment of this application; Figure 9 This is a positive sequence voltage component diagram with added positive and negative sequence control provided in the embodiments of this application; Figure 10 This is a schematic diagram of the structure of a dual droop control device for an energy storage converter provided in an embodiment of this application; Figure 11 This is a schematic diagram of the hardware structure of the electronic device provided in the embodiments of this application. Detailed Implementation

[0014] 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 of this application and are not intended to limit it. In the following description, when referring to the accompanying drawings, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with those of this application; they are merely examples of apparatuses and methods consistent with some aspects of the embodiments of this application as detailed in the appended claims.

[0015] It is understood that the terms "first," "second," "third," "fourth," etc. (if present) in the specification and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of this application described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0016] It should be understood that in this application, "at least one (item)" means one or more, and "more than" means two or more. "And / or" is used to describe the relationship between related objects, indicating that three relationships can exist. For example, "A and / or B" can represent three cases: only A exists, only B exists, and both A and B exist simultaneously, where A and B can be singular or plural. The character " / " generally indicates that the preceding and following related objects are in an "or" relationship. "At least one (item) of the following" or similar expressions refer to any combination of these items, including any combination of single or plural items. For example, at least one (item) of a, b, or c can represent: a, b, c, "a and b", "a and c", "b and c", or "a and b and c", where a, b, and c can be single or multiple.

[0017] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing embodiments of this application only and is not intended to limit this application.

[0018] Existing technologies for addressing grid imbalance issues mainly fall into two categories: one type eliminates negative-sequence current to maintain grid-connected current balance, but this method fails to consider that current regulation can further exacerbate grid-connected voltage imbalance under line fault conditions, resulting in poor applicability during grid line fault scenarios; the other type eliminates negative-sequence voltage to maintain grid-connected voltage balance, but this method leads to grid-connected current imbalance. When the grid voltage imbalance is high, the negative-sequence current is prone to exceed its rated value, thereby causing damage to the energy storage converter hardware. Neither of these methods adequately considers the positive-sequence voltage drop caused by grid line faults, lacks effective support for positive-sequence voltage, and fails to achieve a reasonable allocation of capacity between positive-sequence voltage support and negative-sequence voltage suppression. Consequently, they cannot ensure the effective correction capability of the grid-connected voltage while guaranteeing the hardware safety of the energy storage converter.

[0019] In view of this, this application provides a dual droop control method and related equipment for an energy storage converter. The method first collects the three-phase voltage and three-phase inductor current at the grid connection point of the energy storage converter; converts the three-phase voltage and three-phase inductor current to a two-phase stationary coordinate system to obtain voltage and current components in the two-phase stationary coordinate system; separates the three-phase voltage and the three-phase inductor current into positive and negative sequences based on the voltage and current components in the two-phase stationary coordinate system to obtain positive-sequence voltage components, negative-sequence voltage components, positive-sequence current components, and negative-sequence current components; calculates the current amplitude of the energy storage converter, and calculates the positive-sequence proportional control parameters and negative-sequence proportional control parameters based on the current amplitude; performs positive-sequence droop control based on the positive-sequence voltage components, positive-sequence current components, and the positive-sequence proportional control parameters to obtain a positive-sequence voltage control signal; performs negative-sequence droop control based on the negative-sequence voltage components, negative-sequence current components, and negative-sequence proportional control parameters to obtain a negative-sequence voltage control signal; and combines the negative-sequence voltage control signal and the positive-sequence voltage control signal to obtain the final voltage control signal. By calculating the current amplitude of the energy storage converter and dynamically calculating the positive-sequence and negative-sequence proportional control parameters based on this current amplitude, a reasonable allocation of capacity between positive-sequence voltage support and negative-sequence voltage suppression is achieved. Furthermore, positive-sequence droop control is implemented in the positive-sequence part in conjunction with the positive-sequence proportional control parameters, and negative-sequence droop control is implemented in the negative-sequence part in conjunction with the negative-sequence proportional control parameters. By controlling the positive-sequence voltage component and the negative-sequence voltage component separately, it is possible to ensure the voltage correction capability at the grid connection point while ensuring the hardware safety of the energy storage converter when voltage imbalance is caused by grid line faults. The dual droop control method for energy storage converters provided in this application relates to the field of energy storage converter control technology. This dual droop control method for energy storage converters can be applied to a terminal, a server, or software running on either a terminal or a server. In some embodiments, the terminal can be a smartphone, tablet, laptop, desktop computer, smart speaker, smartwatch, or vehicle terminal, but is not limited to these. The server can be configured as an independent physical server, a server cluster or distributed system composed of multiple physical servers, or a cloud server providing basic cloud computing services such as cloud services, cloud databases, cloud computing, cloud functions, cloud storage, network services, cloud communication, middleware services, domain name services, security services, CDN, and big data and artificial intelligence platforms. The server can also be a node server in a blockchain network. The software can be an application implementing the dual droop control method for energy storage converters, but is not limited to the above forms.

[0020] This application can be used in a wide variety of general-purpose or special-purpose computer system environments or configurations. Examples include: personal computers, server computers, handheld or portable devices, tablet devices, multiprocessor systems, microprocessor-based systems, set-top boxes, programmable consumer electronics devices, network PCs, minicomputers, mainframe computers, and distributed computing environments including any of the above systems or devices. This application can be described in the general context of computer-executable instructions executed by a computer, such as program modules. Generally, program modules include routines, programs, objects, components, data structures, etc., that perform specific tasks or implement specific abstract data types. This application can also be practiced in distributed computing environments where tasks are performed by remote processing devices connected via a communication network. In distributed computing environments, program modules can reside in local and remote computer storage media, including storage devices.

[0021] like Figure 1 The diagram shown is a schematic representation of an implementation environment provided in an embodiment of this application. (Refer to...) Figure 1 The implementation environment includes at least one terminal 102 and a server 101. The terminal 102 and the server 101 can be connected via a network, either wirelessly or via a wired connection, to complete data transmission and exchange.

[0022] Server 101 can be a standalone physical server, a server cluster or distributed system consisting of multiple physical servers, or a cloud server that provides basic cloud computing services such as cloud services, cloud databases, cloud computing, cloud functions, cloud storage, network services, cloud communication, middleware services, domain name services, security services, CDN (Content Delivery Network), and big data and artificial intelligence platforms.

[0023] Additionally, server 101 can also be a node server in a blockchain network. Blockchain is a novel application model of computer technologies such as distributed data storage, peer-to-peer transmission, consensus mechanisms, and encryption algorithms.

[0024] Terminal 102 can be a smartphone, tablet, laptop, desktop computer, smart speaker, smartwatch, etc. It can also be a vehicle-mounted terminal of the various device types described above, but is not limited to these. Terminal 102 and server 101 can be directly or indirectly connected via wired or wireless communication, and this embodiment does not impose any limitations.

[0025] For example, based on Figure 1The implementation environment shown in this application embodiment provides a dual droop control method for an energy storage converter. The following description uses the application of this dual droop control method for an energy storage converter in server 101 as an example. It can be understood that this method can also be applied to terminal 102.

[0026] Reference Figure 2 , Figure 2 The flowchart illustrates a dual droop control method for an energy storage converter applied to a server, as provided in this application embodiment. The execution subject of this method can be any of the aforementioned computer devices (including servers or terminals). (Refer to...) Figure 2 The method may include the following steps: S100: Collects the three-phase voltage and three-phase inductor current at the grid connection point of the energy storage converter.

[0027] In order to perform positive and negative sequence separation control of voltage in this embodiment, it is first necessary to collect the three-phase voltage and three-phase inductor current at the grid connection point of the energy storage converter in the fault grid.

[0028] S200. Convert the three-phase voltage and the three-phase inductor current to a two-phase stationary coordinate system to obtain the voltage and current components in the two-phase stationary coordinate system.

[0029] For example, the Clarke transformation formula used to transform the current components of a three-phase inductor current from a three-phase stationary coordinate system to a two-phase stationary coordinate system is shown below:

[0030]

[0031]

[0032] in, These represent the current components in each phase of the three-phase stationary coordinate system (i.e., the abc coordinate system). These are the current components in the two-phase stationary coordinate system, i.e., the α-β coordinate system.

[0033] The Clarke transform formula used to transform the voltage components of three-phase voltage from a three-phase stationary coordinate system to a two-phase stationary coordinate system is shown below:

[0034]

[0035]

[0036] in, These are the voltage components of each phase in a three-phase stationary coordinate system. These are the voltage components in the two-phase stationary coordinate system, i.e., the α-β coordinate system.

[0037] S300. Based on the voltage and current components in the two-phase stationary coordinate system, the three-phase voltage and the three-phase inductor current are separated into positive and negative sequences to obtain positive sequence voltage components, negative sequence voltage components, positive sequence current components, and negative sequence current components.

[0038] Based on the voltage and current components in a two-phase stationary coordinate system, this embodiment of the application uses a generalized second-order integrator (DOSGI) to decompose the acquired three-phase voltage and three-phase inductor current at the grid connection point into positive and negative sequence components, respectively, to obtain positive sequence voltage components, negative sequence voltage components, positive sequence current components, and negative sequence current components. The steps include S310-S330: S310. Obtain the orthogonal operator, wherein the orthogonal operator refers to performing a phase delay on the signals of the three-phase voltage and the three-phase inductor current; Specifically, the orthogonal operator refers to an approximate 90° phase delay for the three-phase voltage and three-phase inductor current signals. This can be achieved through the following formula:

[0039] Where k is the damping coefficient. The resonant frequency, Can be set to , It is the independent variable of the function.

[0040] S320. Based on the orthogonal operator and the voltage components in the two-phase stationary coordinate system, calculate the positive-sequence voltage component and the negative-sequence voltage component. The calculation formula is as follows:

[0041]

[0042] Where q is an orthogonal operator; It is the positive sequence voltage component; It is a negative sequence voltage component; The voltage components are in a two-phase stationary coordinate system.

[0043] S330. Based on the orthogonal operator and the current components in the two-phase stationary coordinate system, calculate the positive-sequence current component and the negative-sequence current component. The expression for their calculation is as follows:

[0044]

[0045] in, It is the positive sequence current component; It is the negative sequence current component; The current components are in a two-phase stationary coordinate system.

[0046] In this embodiment, after separating the three-phase voltage and three-phase inductor current into positive and negative sequences based on the voltage and current components in the two-phase stationary coordinate system, the method further includes using a phase-locked loop (PLL) to accurately lock the positive and negative sequence phases. Exemplarily, the steps include: inputting the positive and negative sequence voltage components into the PLL respectively; locking the positive sequence voltage component's phase using the PLL to obtain the positive sequence phase; and locking the negative sequence voltage component's phase using the PLL to obtain the negative sequence phase. Specifically, a synchronous coordinate system is first constructed within the PLL. This synchronous coordinate system is used to realize the voltage projection transformation between the two-phase stationary coordinate system (α-β coordinate system) and the two-phase rotating coordinate system (dq coordinate system). This coordinate system transformation is performed according to the Park transformation formula, which is as follows:

[0047] in, The voltage component along the d-axis. This represents the voltage component along the q-axis.

[0048] Secondly, the voltage (including positive-sequence and negative-sequence voltage components) in the two-phase stationary coordinate system (α-β coordinate system) is a uniformly rotating vector. The synchronous coordinate system (i.e., the dq coordinate system) constructed by the phase-locked loop (PLL) rotates synchronously at a uniform speed. When the voltage vector in the α-β system is completely synchronized with the dq coordinate system, the voltage vector will fall completely on the d-axis of the dq coordinate system. At this time, the q-axis voltage component in the dq coordinate system is 0. The phase corresponding to this state is the phase of the current finally locked voltage component (positive or negative sequence).

[0049] Furthermore, in this embodiment, based on the positive sequence phase, Park transform is performed on the positive sequence current component and the positive sequence voltage component to obtain the measured values ​​of the d-axis positive sequence voltage, q-axis positive sequence voltage, d-axis positive sequence current, and q-axis positive sequence current in a two-phase rotating coordinate system; based on the negative sequence phase, Park transform is performed on the negative sequence current component and the negative sequence voltage component to obtain the measured values ​​of the d-axis negative sequence voltage, q-axis negative sequence voltage, d-axis negative sequence current, and q-axis negative sequence current in a two-phase rotating coordinate system.

[0050] S400. Calculate the current amplitude of the energy storage converter, and calculate the positive-sequence proportional control parameter and the negative-sequence proportional control parameter based on the current amplitude.

[0051] Because of the grid imbalance fault, the grid-connected current contains both positive-sequence and negative-sequence components. Therefore, according to the vector addition principle, the current amplitude of the energy storage converter is calculated based on the positive-sequence and negative-sequence current components. The formula for its calculation is:

[0052] in, and The measured values ​​of the positive sequence current along the d-axis and the positive sequence current along the q-axis are divided into the d-q coordinate system. and The measured values ​​of negative sequence current along the d-axis and the q-axis are divided into the d-q coordinate system.

[0053] Under unbalanced operating conditions, negative sequence current will additionally increase the operating pressure on the energy storage converter itself. In this embodiment, considering the capacity limitation of the energy storage converter when controlling both positive and negative sequences simultaneously, the proportional control parameters in the positive and negative sequence voltage control are adjusted by designing a dynamic allocation of support capacity. This allows the proportional control parameters of the positive and negative sequences to be automatically reduced when the output current is too large, ensuring that the energy storage converter hardware is protected while maximizing its capacity utilization. Although the positive and negative sequences are controlled separately, a reasonable allocation of the energy storage converter capacity occupied by the positive and negative sequence control is achieved by sharing the same adjustment coefficient. For example, the steps of calculating the proportional control parameters of the positive sequence and the negative sequence based on the current amplitude include S410-S450: S410. Calculate the difference between the current amplitude and the preset rated current amplitude, and input the difference into the first PI controller to obtain the control reference value; For example, the difference between the current amplitude and the preset rated current amplitude is input into the first PI controller for calculation to obtain the control reference value K, wherein the preset rated current amplitude can be set to 1; wherein the difference between the current amplitude and the preset rated current amplitude represents the current system capacity margin.

[0054] S420. Calculate the sum of the measured values ​​of the positive-sequence voltage on the d-axis and the measured values ​​of the negative-sequence voltage on the d-axis, and calculate the positive-sequence distribution ratio based on the ratio of the measured values ​​of the positive-sequence voltage on the d-axis to the sum. For example, calculating the ascending allocation ratio The formula is:

[0055] in, This represents the measured value of the positive sequence voltage along the d-axis. This represents the measured value of the negative sequence voltage along the d-axis.

[0056] S430. Calculate the negative allocation ratio based on the positive allocation ratio; For example, calculating the negative order allocation ratio The formula is:

[0057] S440. Multiply the positive sequence allocation ratio by the control reference value to obtain the positive sequence ratio control parameter; For example, the proportional control parameter for the positive sequence is calculated. The formula is:

[0058] Where K is the control reference value.

[0059] S450. Multiply the negative sequence allocation ratio by the control reference value to obtain the negative sequence proportional control parameter.

[0060] For example, the formula for calculating the proportional control parameter for negative order is:

[0061] S500: Perform positive sequence droop control based on the positive sequence voltage component, the positive sequence current component, and the positive sequence proportional control parameter to obtain a positive sequence voltage control signal; This application takes into account that the control strategies in the prior art usually lack support for the positive sequence. Therefore, it adds the same control strategy as the negative sequence component to the positive sequence component, that is, the positive sequence component adopts positive sequence droop control and the negative sequence component adopts negative sequence droop control, so as to achieve separate control of the positive and negative sequence components of voltage and current.

[0062] For example, the step of performing positive-sequence droop control based on the positive-sequence voltage component, the positive-sequence current component, and the positive-sequence proportional control parameter to obtain the positive-sequence voltage control signal includes S510-S550: S510. Filter the measured value of the positive sequence voltage of the d-axis to obtain the filtered measured value of the positive sequence voltage of the d-axis.

[0063] For example, in this embodiment of the application, a first-order filter is used to filter the measured value of the negative sequence voltage on the d-axis.

[0064] S520. Multiply the measured value of the filtered d-axis positive sequence voltage by the positive sequence proportional control parameter to calculate the reference value of the q-axis positive sequence current.

[0065] For example, calculate the q-axis positive sequence current reference value. The formula is:

[0066] in, The measured value of the positive sequence voltage on the d-axis after filtering is shown.

[0067] S530. Input the difference between the reference value of the q-axis positive sequence current and the measured value of the q-axis positive sequence current to the second PI controller to generate a q-axis positive sequence voltage control signal in a two-phase rotating coordinate system.

[0068] S540. Input the difference between the preset d-axis positive sequence current reference value and the measured d-axis positive sequence current value to the third PI controller to generate a d-axis positive sequence voltage control signal in a two-phase rotating coordinate system. For example, the preset d-axis positive sequence current reference value can be set to 0.

[0069] S550. Based on the positive sequence phase, convert the q-axis positive sequence voltage control signal and the d-axis positive sequence voltage control signal into a positive sequence voltage control signal in the three-phase coordinate system.

[0070] For example, firstly, based on the positive sequence phase, the d-axis positive sequence voltage control signal and the q-axis positive sequence voltage control signal are subjected to Park inverse transformation to obtain the positive sequence voltage control signal in the two-phase stationary coordinate system; finally, the positive sequence voltage control signal in the two-phase stationary coordinate system is subjected to Clarke inverse transformation to obtain the positive sequence voltage control signal in the three-phase stationary coordinate system, which is the final voltage control signal of the positive sequence part.

[0071] S600. Perform negative sequence droop control based on the negative sequence voltage component, the negative sequence current component, and the negative sequence proportional control parameter to obtain a negative sequence voltage control signal.

[0072] For example, in this embodiment of the application, the step of performing negative sequence droop control based on the negative sequence voltage component, the negative sequence current component, and the negative sequence proportional control parameter to obtain the negative sequence voltage control signal includes S610-S650: S610. Filter the measured value of the negative sequence voltage of the d-axis to obtain the filtered measured value of the negative sequence voltage of the d-axis. For example, in this embodiment of the application, a first-order filter is used to filter the measured value of the negative sequence voltage on the d-axis.

[0073] S620. Multiply the measured value of the filtered d-axis negative sequence voltage by the proportional control parameter of the negative sequence to calculate the reference value of the q-axis negative sequence current. For example, the q-axis negative sequence current reference value is calculated. The formula is:

[0074] in, The measured value of the d-axis negative sequence voltage after filtering is shown.

[0075] S630. Input the difference between the reference value of the q-axis negative sequence current and the measured value of the q-axis negative sequence current to the fourth PI controller to generate a q-axis negative sequence voltage control signal in a two-phase rotating coordinate system.

[0076] S640. Input the difference between the preset d-axis negative sequence current reference value and the measured d-axis negative sequence current value to the fifth PI controller to generate a d-axis negative sequence voltage control signal in a two-phase rotating coordinate system. In this embodiment, the preset d-axis negative sequence current reference value can also be set to 0.

[0077] S650. Based on the negative sequence phase, convert the q-axis negative sequence voltage control signal and the d-axis negative sequence voltage control signal into a negative sequence voltage control signal in the three-phase coordinate system.

[0078] Specifically, based on the negative sequence phase, the d-axis negative sequence voltage control signal and the q-axis negative sequence voltage control signal are first subjected to Park inverse transformation to obtain the negative sequence voltage control signal in the two-phase stationary coordinate system; finally, the negative sequence voltage control signal in the two-phase stationary coordinate system is subjected to Clarke inverse transformation to obtain the negative sequence voltage control signal in the three-phase stationary coordinate system, which is the final voltage control signal of the negative sequence part.

[0079] S700. The negative sequence voltage control signal and the positive sequence voltage control signal are combined to obtain the final voltage control signal.

[0080] Specifically, the final voltage control signal is converted into a PWM signal to drive the IGBT in the energy storage converter.

[0081] To explain in detail the principles of the technical solution of this application, the overall process of this application will be described below with reference to some specific embodiments. It is easy to understand that the following is an explanation of the technical principles of this application and should not be regarded as a limitation of this application.

[0082] In one specific embodiment, the dual droop control process of the energy storage converter in this application includes the following steps: This application includes a circuit section and a control section. The circuit section mainly consists of an energy storage converter topology and a fault grid section. For example... Figure 3 The diagram shown is a schematic of the faulty power grid and the control section of the energy storage converter. (Refer to...) Figure 3 The converter topology consists of a DC constant voltage power supply V. dc The power supply uses six IGBTs arranged in a two-level full-bridge inverter topology, numbered as follows: , , , , , For filtering, an L-type filter is used, and the filter inductance is... The fault grid section first includes an ideal three-phase voltage source. The right side is grounded, and then inductors Lg1 and Lg2 and short-circuit resistor Rg are used to simulate a line with an unbalanced fault. Figure 3 PCC is the grid connection point.

[0083] The control section mainly includes a positive and negative sequence component separation section, a voltage phase control section, a voltage support capability dynamic allocation section, a positive and negative sequence droop control section, and a space vector pulse width modulation section. The flow of its control section is as follows: S1, Separation of Positive and Negative Sequence Components S1.1 In order to achieve positive and negative sequence control of voltage, it is first necessary to control the inductor current in the circuit section. (Three-phase current) and grid connection point voltage (For three-phase voltage) it samples and outputs the measured value as a parameter to the control section, and then receives the PWM control command signal generated by the control section to drive the internal IGBT to work.

[0084] S1.2 To separate the positive and negative sequence components of voltage and current, it is necessary to first obtain the three-phase voltage and three-phase current in the two-phase stationary coordinate system, i.e., the α-β system. This is done by first using Clarke transform to obtain the sampled grid-connected point voltage. and inductor current A coordinate transformation is performed to obtain the grid-connected point voltage and inductor current in a two-phase stationary coordinate system. The Clarke transformation formula used to convert the three-phase current from a three-phase stationary coordinate system to a two-phase stationary coordinate system is shown below:

[0085]

[0086]

[0087] in, These represent the current components in each phase of a three-phase stationary coordinate system (i.e., the abc system). These are the current components in the two-phase stationary coordinate system, i.e., the α-β system.

[0088] The Clarke transform formula used to transform the voltage components of three-phase voltage from a three-phase stationary coordinate system to a two-phase stationary coordinate system is shown below:

[0089]

[0090]

[0091] in, These are the voltage components of each phase in a three-phase stationary coordinate system. These are the voltage components in the two-phase stationary coordinate system, i.e., the α-β coordinate system.

[0092] S1.3 Based on the obtained voltage and current components in the two-phase stationary coordinate system, the positive and negative sequence components are separated by a generalized second-order integrator (DOSGI) to decompose the sampled three-phase voltage and three-phase inductor current at the grid connection point into positive sequence voltage, positive sequence current and negative sequence voltage and negative sequence current components, respectively. Specifically, the formulas for calculating the positive-sequence voltage component and the negative-sequence voltage component are as follows:

[0093]

[0094] in, It is the positive sequence voltage component; It is a negative sequence voltage component; Let be the voltage component in a two-phase stationary coordinate system; q is the orthogonal operator, which delays the signal phase by 90°, achieved through the following formula:

[0095] Where k is the damping coefficient. The resonant frequency, Can be set to , It is the independent variable of the function.

[0096] The formulas for calculating the positive-sequence current component and the negative-sequence current component are as follows:

[0097]

[0098] in, It is the positive sequence current component; It is the negative sequence current component; The current components are in a two-phase stationary coordinate system.

[0099] S2, Voltage Phase Control Section A phase-locked loop (PLL) is used to achieve precise locking of the positive-sequence and negative-sequence phases. Exemplarily, the steps include: inputting the positive-sequence and negative-sequence voltage components into the PLL respectively; using the PLL to perform phase locking based on the positive-sequence voltage component to obtain the positive-sequence phase; and using the PLL to perform phase locking based on the negative-sequence voltage component to obtain the negative-sequence phase. Specifically, a synchronous coordinate system is first constructed within the PLL. This synchronous coordinate system is used to achieve voltage projection transformation between a two-phase stationary coordinate system (α-β coordinate system) and a two-phase rotating coordinate system (dq coordinate system). This coordinate system transformation is performed according to the Park transformation formula, which is as follows:

[0100] in, The voltage component along the d-axis. This represents the voltage component along the q-axis.

[0101] Secondly, the voltage (including positive-sequence and negative-sequence voltage components) in the two-phase stationary coordinate system (α-β coordinate system) is a uniformly rotating vector. The synchronous coordinate system (i.e., the dq coordinate system) constructed by the phase-locked loop (PLL) rotates synchronously at a uniform speed. When the voltage vector in the α-β system is completely synchronized with the dq coordinate system, the voltage vector will fall completely on the d-axis of the dq coordinate system. At this time, the q-axis voltage component in the dq coordinate system is 0. The phase corresponding to this state is the phase of the current finally locked voltage component (positive or negative sequence).

[0102] S3, Dynamic allocation of voltage support capability S3.1 First, based on the positive sequence phase, perform Park transformation on the positive sequence current component and the positive sequence voltage component to obtain the measured values ​​of the d-axis positive sequence voltage, q-axis positive sequence voltage, d-axis positive sequence current, and q-axis positive sequence current in the two-phase rotating coordinate system; based on the negative sequence phase, perform Park transformation on the negative sequence current component and the negative sequence voltage component to obtain the measured values ​​of the d-axis negative sequence voltage, q-axis negative sequence voltage, d-axis negative sequence current, and q-axis negative sequence current in the two-phase rotating coordinate system.

[0103] S3.2 Secondly, due to the imbalance fault in the power grid, both positive-sequence and negative-sequence components exist in the grid-connected current. Therefore, according to the vector addition principle, the current amplitude of the energy storage converter is calculated based on the positive-sequence and negative-sequence current components. The formula for its calculation is:

[0104] in, and The measured values ​​of the positive sequence current along the d-axis and the positive sequence current along the q-axis are divided into the d-q coordinate system. and The measured values ​​of negative sequence current along the d-axis and the q-axis are divided into the d-q coordinate system.

[0105] S3.3 Calculate the positive-sequence and negative-sequence proportional control parameters based on the current amplitude: First, input the difference between the current amplitude and the preset rated current amplitude into the PI controller for calculation. After PI calculation, the control reference value K is output. The difference between the current amplitude and the preset rated current amplitude represents the current system capacity margin. Second, calculate the sum of the measured values ​​of the d-axis positive-sequence voltage and the d-axis negative-sequence voltage, and calculate the positive-sequence allocation ratio based on the ratio of the measured d-axis positive-sequence voltage to the sum. Its formula is:

[0106] in, This represents the measured value of the positive sequence voltage along the d-axis. This represents the measured value of the negative sequence voltage along the d-axis.

[0107] Subtracting the positive allocation ratio from 1 gives the negative allocation ratio. Its formula is:

[0108] Finally, the positive sequence allocation ratio is multiplied by the control reference value to obtain the positive sequence proportional control parameter, the formula of which is:

[0109] Where K is the control reference value.

[0110] Multiplying the negative-order allocation ratio by the aforementioned control reference value yields the negative-order proportional control parameter, the formula of which is:

[0111] By dynamically allocating the support capacity, the proportional control parameters in the positive and negative sequence voltage control are adjusted. This allows the proportional control parameters of the positive and negative sequence components to be automatically reduced when the output current is too high. This ensures that the energy storage converter hardware is protected while maximizing its capacity utilization. Although the positive and negative sequences are controlled separately, a common adjustment coefficient is shared, achieving a reasonable allocation of the energy storage converter capacity occupied by the positive and negative sequence control.

[0112] S4, Positive and Negative Sequence Droop Control Section like Figure 4 As shown, Figure 4 This is a schematic diagram of the orthogonal droop control provided in the embodiments of this application, referring to... Figure 4 The process of the positive sequence droop control section is as follows: a first-order filter (i.e., ...) is used. Figure 41 / S+1 can be represented as a first-order low-pass filter, where (where s is a time constant and s is a Laplace variable) The measured values ​​of the positive sequence voltage on the d-axis Perform filtering; then convert the filtered d-axis positive sequence voltage measurement value... Multiplying the positive sequence proportional control parameter by the given parameters, the q-axis positive sequence current reference value is calculated. ; and compare the q-axis positive sequence current reference value with the measured q-axis positive sequence current value. The difference between the two values ​​is input to a PI controller for calculation, generating a q-axis positive sequence voltage control signal in a two-phase rotating coordinate system; then, the preset d-axis positive sequence current reference value (which is 0) and the measured d-axis positive sequence current value are compared. The difference between them is input to another PI controller for calculation, generating the d-axis positive sequence voltage control signal in a two-phase rotating coordinate system; finally, based on the positive sequence phase... The d-axis and q-axis positive sequence voltage control signals are subjected to an inverse Park transform to obtain the positive sequence voltage control signals in the two-phase stationary coordinate system. Finally, the positive sequence voltage control signals in the two-phase stationary coordinate system are subjected to an inverse Clarke transform to obtain the positive sequence voltage control signals in the three-phase stationary coordinate system. That is, the final voltage control signal of the positive sequence. like Figure 5 As shown, Figure 5 This is a schematic diagram of negative order droop control provided in an embodiment of this application, referring to... Figure 5 The process for the negative sequence droop control section is as follows: A first-order filter is used to filter the measured values ​​of the d-axis negative sequence voltage. The filtered values ​​of the negative sequence voltage on the d-axis are then processed. Multiplying the negative-sequence proportional control parameter by the negative-sequence current, the reference value of the q-axis negative-sequence current is calculated. Compare the reference value of the q-axis negative sequence current with the measured value of the q-axis negative sequence current. The difference between the two values ​​is input to a PI controller to generate a q-axis negative sequence voltage control signal in a two-phase rotating coordinate system; the preset d-axis negative sequence current reference value (which is 0) is compared with the measured d-axis negative sequence current value. The difference between them is input to another PI controller to generate a negative sequence voltage control signal for the d-axis in a two-phase rotating coordinate system; finally, based on the negative sequence phase... The d-axis and q-axis negative sequence voltage control signals are subjected to an inverse Park transform to obtain the negative sequence voltage control signals in the two-phase stationary coordinate system. Finally, the negative sequence voltage control signals in the two-phase stationary coordinate system are subjected to an inverse Clarke transform to obtain the negative sequence voltage control signals in the three-phase stationary coordinate system, which is the final voltage control signal for the negative sequence portion. .

[0113] S5, Space Vector Pulse Width Modulation Section Finally, the final voltage control signals of the positive sequence and negative sequence obtained above are input to the space vector pulse width modulation section, which converts them into PWM signals and outputs them to the inverter topology section of the energy storage AC circuit to drive the IGBT to work.

[0114] To further verify the effectiveness and superiority of the proposed solution, simulation comparison experiments were conducted, and the verification results are as follows: like Figure 6 As shown and Figure 7 As shown, Figure 6 This is a waveform diagram of grid-connected current and voltage without positive and negative sequence control provided in the embodiments of this application; Figure 7 This is a positive sequence voltage component diagram without positive and negative sequence control provided in the embodiments of this application; Figure 6 and Figure 7 These simulations do not include positive-sequence droop and negative-sequence control; the positive-sequence control uses only traditional current loop control. It can be seen that under such severe grid line fault conditions, the positive-sequence voltage drops by nearly 50%, and the grid-connected current risks exceeding its rated value, potentially damaging the hardware.

[0115] Furthermore, such as Figure 8 and Figure 9 As shown, Figure 8 This is a grid-connected current and voltage waveform diagram with added positive and negative sequence control provided in an embodiment of this application; Figure 9 This is a positive sequence voltage component diagram with added positive and negative sequence control provided in the embodiments of this application; Figure 8 and Figure 9 The simulation results, incorporating the control method proposed in this application, demonstrate the system's significant support for positive-sequence voltage. While maintaining the current amplitude within the rated value, the positive-sequence voltage increases from 50% to 81% of the rated value. Furthermore, the grid-connected current does not exceed the rated value by 1%, ensuring the normal operation of the energy storage converter. Ultimately, the simulation control reduces the three-phase voltage imbalance of the unbalanced faulty power grid from 36% to 30%.

[0116] The two sets of simulation results above demonstrate that the control method proposed in this application can enable the energy storage converter to correct the grid connection voltage under line fault conditions, even with the rated current limit. Simultaneously, through dynamic adjustment of the proportional control parameters, the capacity allocation between positive-sequence support and negative-sequence suppression capabilities can be rationally distributed, ensuring that the grid connection current does not exceed the rated value, thus protecting the energy storage converter hardware itself.

[0117] In summary, this application provides a dual droop control method and related equipment for an energy storage converter. The method first acquires the three-phase voltage and three-phase inductor current at the grid connection point of the energy storage converter; then converts the three-phase voltage and current to a two-phase stationary coordinate system to obtain voltage and current components in the two-phase stationary coordinate system; based on the voltage and current components in the two-phase stationary coordinate system, the three-phase voltage and the three-phase inductor current are separated into positive and negative sequences to obtain positive-sequence voltage components, negative-sequence voltage components, positive-sequence current components, and negative-sequence current components; the current amplitude of the energy storage converter is calculated, and positive-sequence and negative-sequence proportional control parameters are calculated based on the current amplitude; positive-sequence droop control is performed based on the positive-sequence voltage components, positive-sequence current components, and the positive-sequence proportional control parameters to obtain a positive-sequence voltage control signal; negative-sequence droop control is performed based on the negative-sequence voltage components, negative-sequence current components, and the negative-sequence proportional control parameters to obtain a negative-sequence voltage control signal; finally, the negative-sequence voltage control signal and the positive-sequence voltage control signal are combined to obtain the final voltage control signal. By calculating the current amplitude of the energy storage converter and dynamically calculating the positive-sequence and negative-sequence proportional control parameters based on this current amplitude, a reasonable allocation of capacity between positive-sequence voltage support and negative-sequence voltage suppression is achieved. Furthermore, positive-sequence droop control is implemented in the positive-sequence part in conjunction with the positive-sequence proportional control parameters, and negative-sequence droop control is implemented in the negative-sequence part in conjunction with the negative-sequence proportional control parameters. By controlling the positive-sequence voltage component and the negative-sequence voltage component separately, it is possible to ensure the voltage correction capability at the grid connection point while ensuring the hardware safety of the energy storage converter when voltage imbalance is caused by grid line faults. like Figure 10 As shown in the figure, this application embodiment also provides a structural schematic diagram of a dual droop control device for an energy storage converter. This device can implement the above-mentioned method and may include: Acquisition module 21 is used to acquire the three-phase voltage and three-phase inductor current at the grid connection point of the energy storage converter; The coordinate transformation module 22 is used to transform the three-phase voltage and the three-phase inductor current to a two-phase stationary coordinate system to obtain the voltage component and current component in the two-phase stationary coordinate system. The positive and negative sequence separation module 23 is used to separate the three-phase voltage and the three-phase inductor current into positive and negative sequences according to the voltage and current components in the two-phase stationary coordinate system, so as to obtain positive sequence voltage component, negative sequence voltage component, positive sequence current component and negative sequence current component. The proportional control parameter calculation module 24 is used to calculate the current amplitude of the energy storage converter, and calculate the positive-sequence proportional control parameter and the negative-sequence proportional control parameter based on the current amplitude; The positive sequence droop control module 25 is used to perform positive sequence droop control based on the positive sequence voltage component, the positive sequence current component and the positive sequence proportional control parameter to obtain a positive sequence voltage control signal. The negative sequence droop control module 26 is used to perform negative sequence droop control based on the negative sequence voltage component, the negative sequence current component and the negative sequence proportional control parameter to obtain a negative sequence voltage control signal. The signal merging module 27 is used to merge the negative sequence voltage control signal and the positive sequence voltage control signal to obtain the final voltage control signal.

[0118] It is understood that the content of the above method embodiments is applicable to the present device embodiments. The specific functions implemented by the present device embodiments are the same as those of the above method embodiments, and the beneficial effects achieved are also the same as those achieved by the above method embodiments.

[0119] This application also provides an electronic device, which includes a memory and a processor. The memory stores a computer program, and the processor executes the computer program to implement the above-described dual droop control method for energy storage converters. This electronic device can be any smart terminal, including tablet computers, in-vehicle computers, etc.

[0120] It is understood that the content of the above method embodiments is applicable to this device embodiment. The specific functions implemented by this device embodiment are the same as those of the above method embodiments, and the beneficial effects achieved are also the same as those achieved by the above method embodiments.

[0121] Please see Figure 11 , Figure 11 The hardware structure of an electronic device according to another embodiment is illustrated. The electronic device includes: The processor 901 can be implemented using a general-purpose CPU (Central Processing Unit), microprocessor, application-specific integrated circuit (ASIC), or one or more integrated circuits, and is used to execute relevant programs to implement the technical solutions provided in the embodiments of this application. The memory 902 can be implemented as a read-only memory (ROM), static storage device, dynamic storage device, or random access memory (RAM). The memory 902 can store the operating system and other application programs. When the technical solutions provided in the embodiments of this specification are implemented through software or firmware, the relevant program code is stored in the memory 902 and is called and executed by the processor 901 using the dual droop control method for energy storage converters according to the embodiments of this application. The 903 input / output interface is used to implement information input and output. The communication interface 904 is used to enable communication and interaction between this device and other devices. Communication can be achieved through wired means (such as USB, Ethernet cable, etc.) or wireless means (such as mobile network, WIFI, Bluetooth, etc.). Bus 905 transmits information between various components of the device (e.g., processor 901, memory 902, input / output interface 903, and communication interface 904); The processor 901, memory 902, input / output interface 903, and communication interface 904 are connected to each other within the device via bus 905.

[0122] This application also provides a computer-readable storage medium storing a computer program that, when executed by a processor, implements the above-described energy storage converter dual droop control method.

[0123] It is understood that the content of the above method embodiments is applicable to this storage medium embodiment. The specific functions implemented in this storage medium embodiment are the same as those in the above method embodiments, and the beneficial effects achieved are also the same as those achieved in the above method embodiments.

[0124] Memory, as a non-transitory computer-readable storage medium, can be used to store non-transitory software programs and non-transitory computer-executable programs. Furthermore, memory may include high-speed random access memory, and may also include non-transitory memory, such as at least one disk storage device, flash memory device, or other non-transitory solid-state storage device. In some embodiments, memory may optionally include memory remotely located relative to the processor, and these remote memories can be connected to the processor via a network. Examples of such networks include, but are not limited to, the Internet, intranets, local area networks, mobile communication networks, and combinations thereof.

[0125] The embodiments described in this application are for the purpose of more clearly illustrating the technical solutions of the embodiments of this application, and do not constitute a limitation on the technical solutions provided by the embodiments of this application. As those skilled in the art will know, with the evolution of technology and the emergence of new application scenarios, the technical solutions provided by the embodiments of this application are also applicable to similar technical problems.

[0126] Those skilled in the art will understand that the technical solutions shown in the figures do not constitute a limitation on the embodiments of this application, and may include more or fewer steps than shown, or combine certain steps, or different steps.

[0127] The device embodiments described above are merely illustrative. The units described as separate components may or may not be physically separate; that is, they may be located in one place or distributed across multiple network units. Some or all of the modules can be selected to achieve the purpose of this embodiment according to actual needs.

[0128] Those skilled in the art will understand that all or some of the steps in the methods disclosed above, as well as the functional modules / units in the systems and devices, can be implemented as software, firmware, hardware, or suitable combinations thereof.

[0129] In the several embodiments provided in this application, it should be understood that the disclosed apparatus and methods can be implemented in other ways. For example, the apparatus embodiments described above are merely illustrative; for instance, the division of the units described above is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be through some interfaces; the indirect coupling or communication connection between apparatuses or units may be electrical, mechanical, or other forms.

[0130] The units described above as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0131] Furthermore, the functional units in the various embodiments of this application can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The integrated unit can be implemented in hardware or as a software functional unit.

[0132] If the integrated unit is implemented as a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of this application, in essence, or the part that contributes to the prior art, or all or part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes multiple instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods of the various embodiments of this application. The aforementioned storage medium includes various media capable of storing programs, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks. The preferred embodiments of the present application have been described above with reference to the accompanying drawings, but this does not limit the scope of the claims of the present application. Any modifications, equivalent substitutions, and improvements made by those skilled in the art without departing from the scope and substance of the embodiments of the present application shall be within the scope of the claims of the present application.

Claims

1. A dual droop control method for an energy storage converter, characterized in that, include: Collect the three-phase voltage and three-phase inductor current at the grid connection point of the energy storage converter; The three-phase voltage and the three-phase inductor current are converted to a two-phase stationary coordinate system to obtain the voltage and current components in the two-phase stationary coordinate system. Based on the voltage and current components in the two-phase stationary coordinate system, the three-phase voltage and the three-phase inductor current are separated into positive and negative sequences to obtain positive sequence voltage components, negative sequence voltage components, positive sequence current components, and negative sequence current components. Calculate the current amplitude of the energy storage converter, and calculate the positive-sequence proportional control parameter and the negative-sequence proportional control parameter based on the current amplitude; Positive sequence droop control is performed based on the positive sequence voltage component, the positive sequence current component, and the positive sequence proportional control parameter to obtain a positive sequence voltage control signal. Negative sequence droop control is performed based on the negative sequence voltage component, the negative sequence current component, and the negative sequence proportional control parameter to obtain a negative sequence voltage control signal. The negative-sequence voltage control signal and the positive-sequence voltage control signal are combined to obtain the final voltage control signal.

2. The dual droop control method for energy storage converter according to claim 1, characterized in that, The step of separating the three-phase voltage and the three-phase inductor current into positive and negative sequences based on the voltage and current components in the two-phase stationary coordinate system to obtain positive-sequence voltage components, negative-sequence voltage components, positive-sequence current components, and negative-sequence current components includes: Obtain an orthogonal operator, wherein the orthogonal operator refers to performing a phase delay on the signals of the three-phase voltage and the three-phase inductor current; Based on the orthogonal operator and the voltage components in the two-phase stationary coordinate system, calculate the positive sequence voltage component and the negative sequence voltage component; Based on the orthogonal operator and the current components in the two-phase stationary coordinate system, calculate the positive sequence current component and the negative sequence current component.

3. The dual droop control method for energy storage converters according to claim 1, characterized in that, After separating the three-phase voltage and the three-phase inductor current into positive and negative sequences based on the voltage and current components in the two-phase stationary coordinate system, the method further includes: The positive-sequence voltage component and the negative-sequence voltage component are respectively input into the phase-locked loop; The positive sequence voltage component is phase-locked by the phase-locked loop to obtain the positive sequence phase; The negative sequence voltage component is phase-locked by the phase-locked loop to obtain the negative sequence phase.

4. The dual droop control method for energy storage converter according to claim 3, characterized in that, The method further includes: Based on the positive sequence phase, Park transformation is performed on the positive sequence current component and the positive sequence voltage component to obtain the measured values ​​of the d-axis positive sequence voltage, q-axis positive sequence voltage, d-axis positive sequence current, and q-axis positive sequence current in the two-phase rotating coordinate system. Based on the negative sequence phase, Park transform is performed on the negative sequence current component and the negative sequence voltage component to obtain the measured values ​​of the d-axis negative sequence voltage, q-axis negative sequence voltage, d-axis negative sequence current, and q-axis negative sequence current in the two-phase rotating coordinate system.

5. The dual droop control method for energy storage converter according to claim 4, characterized in that, The calculation of the positive-sequence proportional control parameter and the negative-sequence proportional control parameter based on the current amplitude includes: Calculate the difference between the current amplitude and the preset rated current amplitude, and input the difference into the first PI controller to obtain the control reference value; Calculate the sum of the measured values ​​of the positive-sequence voltage and the negative-sequence voltage on the d-axis, and calculate the positive-sequence distribution ratio based on the ratio of the measured value of the positive-sequence voltage on the d-axis to the sum. Calculate the negative allocation ratio based on the positive allocation ratio; Multiply the positive sequence allocation ratio by the control reference value to obtain the positive sequence proportional control parameter; Multiply the negative order allocation ratio by the control reference value to obtain the negative order ratio control parameter.

6. The dual droop control method for energy storage converter according to claim 4, characterized in that, The step of performing positive-sequence droop control based on the positive-sequence voltage component, the positive-sequence current component, and the positive-sequence proportional control parameter to obtain a positive-sequence voltage control signal includes: The measured values ​​of the positive sequence voltage on the d-axis are filtered to obtain the filtered measured values ​​of the positive sequence voltage on the d-axis. The measured value of the filtered d-axis positive sequence voltage is multiplied by the positive sequence proportional control parameter to calculate the reference value of the q-axis positive sequence current. The difference between the reference value of the q-axis positive sequence current and the measured value of the q-axis positive sequence current is input to the second PI controller to generate a q-axis positive sequence voltage control signal in a two-phase rotating coordinate system. The difference between the preset d-axis positive sequence current reference value and the measured d-axis positive sequence current value is input to the third PI controller to generate the d-axis positive sequence voltage control signal in the two-phase rotating coordinate system. Based on the positive sequence phase, the q-axis positive sequence voltage control signal and the d-axis positive sequence voltage control signal are converted into positive sequence voltage control signals in the three-phase coordinate system.

7. The dual droop control method for energy storage converter according to claim 4, characterized in that, The step of performing negative-sequence droop control based on the negative-sequence voltage component, the negative-sequence current component, and the negative-sequence proportional control parameter to obtain a negative-sequence voltage control signal includes: The measured values ​​of the negative sequence voltage along the d-axis are filtered to obtain the filtered measured values ​​of the negative sequence voltage along the d-axis. The measured value of the filtered d-axis negative sequence voltage is multiplied by the proportional control parameter of the negative sequence to calculate the reference value of the q-axis negative sequence current. The difference between the reference value of the q-axis negative sequence current and the measured value of the q-axis negative sequence current is input to the fourth PI controller to generate the q-axis negative sequence voltage control signal in the two-phase rotating coordinate system. The difference between the preset d-axis negative sequence current reference value and the measured d-axis negative sequence current value is input to the fifth PI controller to generate the d-axis negative sequence voltage control signal in the two-phase rotating coordinate system. Based on the negative sequence phase, the q-axis negative sequence voltage control signal and the d-axis negative sequence voltage control signal are converted into negative sequence voltage control signals in the three-phase coordinate system.

8. A dual droop control device for an energy storage converter, characterized in that, The device includes: The data acquisition module is used to acquire the three-phase voltage and three-phase inductor current at the grid connection point of the energy storage converter; The coordinate transformation module is used to transform the three-phase voltage and the three-phase inductor current to a two-phase stationary coordinate system to obtain the voltage components and current components in the two-phase stationary coordinate system. The positive and negative sequence separation module is used to separate the three-phase voltage and the three-phase inductor current into positive and negative sequences based on the voltage and current components in the two-phase stationary coordinate system, to obtain positive sequence voltage components, negative sequence voltage components, positive sequence current components, and negative sequence current components. The proportional control parameter calculation module is used to calculate the current amplitude of the energy storage converter, and to calculate the positive-sequence proportional control parameters and the negative-sequence proportional control parameters based on the current amplitude. The positive sequence droop control module is used to perform positive sequence droop control based on the positive sequence voltage component, the positive sequence current component and the positive sequence proportional control parameter to obtain a positive sequence voltage control signal. The negative sequence droop control module is used to perform negative sequence droop control based on the negative sequence voltage component, the negative sequence current component and the negative sequence proportional control parameter to obtain a negative sequence voltage control signal. The signal merging module is used to merge the negative sequence voltage control signal and the positive sequence voltage control signal to obtain the final voltage control signal.

9. An electronic device, characterized in that, Including the processor and memory; The memory is used to store programs; The processor executes the program to implement the dual droop control method for energy storage converters as described in any one of claims 1 to 7.

10. A computer program product, comprising a computer program, characterized in that, When the computer program is executed by the processor, it implements the dual droop control method for energy storage converters as described in any one of claims 1 to 7.

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