Four-quadrant power compensation calibration method, system and device for energy storage device and medium
By acquiring circuit data from the energy storage converter, calculating the actual active power and reactive power compensation current, and using software phase-locked loop and Park coordinate transformation for phase difference compensation, the problem of active power deviation during the inverter process of the energy storage converter is solved, achieving efficient power control and cost reduction.
Patent Information
- Application Number
- CN202511116980.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-08-11
- Publication Date
- 2025-11-14
AI Technical Summary
The high-order harmonic components generated by the energy storage converter during the inverter process affect the grid-connected voltage quality, causing a deviation between the active power and the given active power, and existing methods increase hardware costs.
By acquiring the DC and AC circuit data of the energy storage converter, the actual active power and reactive power compensation capacitor current are calculated. Phase difference compensation is then performed using a software phase-locked loop and Park coordinate transformation to achieve calibration of active and reactive power.
It improves the accuracy of power control in energy storage converters, reduces hardware costs, and achieves precise compensation of active and reactive power.
Smart Images
Figure CN120955751A_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of power grid technology, and in particular to a four-quadrant power compensation calibration method, system, device and medium for energy storage devices. Background Technology
[0002] Among related technologies, the development and popularization of renewable energy and related industries have further promoted the development of energy storage technology. As a bidirectional current-controllable conversion device connecting energy storage battery systems and the power grid, the energy storage converter can accurately and quickly adjust voltage, frequency, and power between the power grid and the energy storage system, achieving four-quadrant power operation. Accurate power control by the energy storage converter is fundamental to ensuring the safe and efficient operation of the system.
[0003] However, during the inverter process, the AC side voltage of the energy storage converter contains abundant high-order harmonic components due to high-frequency switching operations. Direct grid connection without filtering will affect the grid voltage quality. While LC filters can remove high-order harmonics, their characteristics cause inductor current to deviate from the actual grid-side output current, resulting in a deviation between the output active power and the given active power, and also introducing capacitive reactive power. Currently, the common solution is to add a grid-side current sampling circuit, but this method increases hardware costs.
[0004] In summary, the technical problems existing in the relevant technologies need to be improved. Summary of the Invention
[0005] The main objective of this application is to propose a four-quadrant power compensation calibration method, system, device, and medium for energy storage devices, aiming to improve the accuracy of power control of energy storage converters while reducing the cost of calibrating the power of energy storage converters.
[0006] To achieve the above objectives, one aspect of this application proposes a four-quadrant power compensation calibration method for an energy storage device, the method comprising: Obtain DC-side circuit data, AC-side circuit data, and actual capacitance values of the filter capacitors from the energy storage converter; The actual active power on the DC side is determined based on the DC side circuit data, and the target phase difference is determined based on the actual active power on the DC side and the AC side circuit data. During the Park coordinate transformation of the power grid, the active power is calibrated by applying the target phase difference to the phase-locked angle. The reactive power compensation capacitor current is determined based on the AC side circuit data and the actual capacitance value of the filter capacitor; the reactive power compensation capacitor current is applied to compensate and calibrate the reactive power in the Q-axis positive sequence control loop of the grid-connected inner loop.
[0007] In some embodiments, the DC-side circuit data includes DC voltage and DC current, and the AC-side circuit data includes the effective value of the inverter phase voltage and the effective value of the inductor current. The step of determining the actual active power on the DC side based on the DC-side circuit data, and determining the target phase difference based on the actual active power on the DC side and the AC-side circuit data, includes: The operating condition level of the energy storage converter is determined based on the DC voltage and the DC current, and the mapping conversion efficiency is determined based on the operating condition level. Based on the operating mode of the energy storage converter, the actual active power on the DC side is determined according to the DC voltage, the DC current and the conversion efficiency. The operating mode includes inverter mode or rectifier mode. The target phase difference is determined based on the actual active power, the effective value of the inverter phase voltage, and the effective value of the inductor current.
[0008] In some embodiments, determining the target phase difference based on the actual active power, the effective value of the inverter phase voltage, and the effective value of the inductor current includes: Based on the absence of a phase difference between the inductor current and the grid-side current, a first calculation formula is constructed. The first calculation formula is the product of the effective value of the inverter phase voltage, the effective value of the inductor current, the cosine value of the first phase, and a preset coefficient, which equals the actual active power. The first phase is determined according to the first calculation formula, and the first phase is the phase difference between the inverter voltage and the inductor current. Based on the phase difference between the inductor current and the grid-side current, a second calculation formula is constructed. The second calculation formula is the product of the effective value of the inverter phase voltage, the effective value of the inductor current, the cosine value of the second phase, and a preset coefficient, which equals the actual active power. The target phase difference is determined according to the second calculation formula, wherein the second phase is the sum of the first phase and the target phase difference.
[0009] In some embodiments, determining the actual active power on the DC side based on the operating mode of the energy storage converter, according to the DC voltage, the DC current, and the conversion efficiency, includes: In response to the operating mode being the inverter mode, the actual active power is determined based on a third product of the DC voltage, the DC current, and the conversion efficiency.
[0010] In some embodiments, determining the actual active power on the DC side based on the operating mode of the energy storage converter, according to the DC voltage, the DC current, and the conversion efficiency, includes: In response to the operating mode being the rectification mode, the fourth product of the DC voltage and the DC current is calculated, and the actual active power is determined based on the first ratio of the fourth product to the conversion efficiency.
[0011] In some embodiments, the AC side circuit data includes rated phase voltage, rated phase current, and inverter voltage. Determining the reactive power compensation capacitor current based on the AC side circuit data and the actual capacitance value of the filter capacitor includes: Calculate the second ratio of the rated phase voltage to the rated phase current, and determine the normalized parameter of the filter capacitor based on the fifth product of the second ratio and the actual capacitance value of the filter capacitor; The grid frequency is determined by a software phase-locked loop, and the grid angular frequency is determined based on the grid frequency. The per-unit value of the d-axis voltage component is determined based on the inverter voltage and is defined as the per-unit value of the inverter voltage. The reactive power compensation capacitor current is determined based on the normalized parameters of the filter capacitor, the grid angular frequency, and the per-unit value of the inverter voltage.
[0012] In some embodiments, determining the reactive power compensation capacitor current based on the normalized parameters of the filter capacitor, the grid angular frequency, and the inverter voltage per-unit value includes: Calculate the sixth product of the normalized parameter of the filter capacitor and the angular frequency of the power grid, and determine the capacitive reactance of the filter capacitor based on the reciprocal of the sixth product; The reactive power compensation capacitor current is determined based on the third ratio of the inverter voltage per-unit value to the capacitive reactance of the filter capacitor.
[0013] To achieve the above objectives, another aspect of this application proposes a four-quadrant power compensation calibration system for an energy storage device, the system comprising: The data acquisition module is used to acquire DC-side circuit data, AC-side circuit data, and actual capacitance values of the filter capacitors of the energy storage converter. The active power processing module is used to determine the actual active power on the DC side based on the DC side circuit data, and to determine the target phase difference based on the actual active power on the DC side and the AC side circuit data; during the Park coordinate transformation of the power grid, the active power is calibrated by applying the target phase difference to the phase-locked angle. The reactive power processing module is used to determine the reactive power compensation capacitor current based on the AC side circuit data and the actual capacitance value of the filter capacitor; and to apply the reactive power compensation capacitor current to compensate and calibrate reactive power in the Q-axis positive sequence control loop of the grid-connected inner loop.
[0014] To achieve the above objectives, another aspect of this application provides a computer device including a memory and a processor, wherein the memory stores a computer program, and the processor executes the computer program to implement the above-described method.
[0015] 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 above-described method.
[0016] The embodiments of this application include at least the following beneficial effects: This application provides a four-quadrant power compensation calibration method, system, device, and medium for energy storage devices. This scheme collects DC-side circuit data, AC-side circuit data, and the actual capacitance value of the filter capacitor from the energy storage converter. For active power, the actual active power on the DC side is calculated based on the DC-side circuit data and used as the standard for AC-side calculation. The target phase difference is determined in conjunction with the AC-side circuit data, thereby compensating the phase-locked angle of the Park coordinate transformation through the target phase difference, achieving active power calibration. For reactive power, the reactive power compensation capacitor current is calculated based on the AC-side circuit data and the actual capacitance value of the filter capacitor, thereby adding the reactive power compensation capacitor current to the positive sequence Q-axis control loop of the grid-connected inner loop, achieving reactive power calibration. Compared to adding a grid-side current sampling circuit, this application only calculates the active and reactive power compensation strategies based on software and achieves calibration, improving the accuracy of energy storage converter power control. Simultaneously, it eliminates the need for an additional grid-side current sampling circuit, reducing the cost of calibrating the energy storage converter power. Attached Figure Description
[0017] Figure 1 This is a flowchart of a four-quadrant power compensation calibration method for an energy storage device provided in an embodiment of this application; Figure 2 This is a circuit diagram of the energy storage converter connected to the power grid according to an embodiment of this application; Figure 3 This is a schematic diagram of the loop feedback and inner loop control loop in an embodiment of this application; Figure 4 yes Figure 1 The flowchart of step S102 in the document; Figure 5 yes Figure 1 The flowchart of step S103 in the process; Figure 6 yes Figure 1 Another flowchart of step S103 in the process; Figure 7 This is a power comparison line graph of the method in the embodiments of this application; Figure 8This is a schematic diagram of the structure of the four-quadrant power compensation calibration system for the energy storage device provided in the embodiments of this application; Figure 9 This is a schematic diagram of the hardware structure of the computer device provided in the embodiments of this application. Detailed Implementation
[0018] 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.
[0019] It is understood that the terms “first,” “second,” etc., used in this application may be used herein to describe various concepts, but unless otherwise stated, these concepts are not limited by these terms. These terms are only used to distinguish one concept from another. For example, without departing from the scope of the embodiments of this application, first information may also be referred to as second information, and similarly, second information may also be referred to as first information. Depending on the context, the words “if,” “when,” or “in response to a determination” as used herein may be interpreted as “when…” or “when…” or “in response to a determination.”
[0020] As used in this application, the terms "at least one", "multiple", "each", "any", etc., "at least one" includes one, two or more, "multiple" includes two or more, "each" refers to each of the corresponding multiples, and "any" refers to any one of the multiples.
[0021] 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.
[0022] Before providing a detailed description of the embodiments of this application, some of the nouns and terms involved in the embodiments of this application will be explained first. The nouns and terms involved in the embodiments of this application are subject to the following interpretations.
[0023] 1) The energy storage converter is the core device in an energy storage system, enabling bidirectional conversion of electrical energy between DC and AC, and controlling and managing the energy storage process. Its operating states include charging and discharging. In charging mode, it converts AC power generated from renewable energy into DC power to charge the energy storage battery. In discharging mode, it converts the DC power from the energy storage battery into AC power that meets grid standards or load requirements, releasing the electrical energy. Simultaneously, during the conversion process, it adjusts parameters such as charging and discharging power, voltage, and frequency according to grid demand, load changes, or energy storage strategies to achieve smooth power output or absorption, avoiding impact on the grid.
[0024] 2) A software phase-locked loop is a digital control system that achieves signal phase synchronization through software algorithms. Its core function is to keep the frequency and phase of the output signal consistent with the input reference signal, that is, to achieve phase locking.
[0025] In related technologies, the development and popularization of renewable energy and related industries have further promoted the development of energy storage technology, and the proportion of intermittent energy sources such as photovoltaic and wind power in the power system is constantly increasing. As a bidirectional current-controllable conversion device connecting energy storage battery systems and the power grid, the energy storage converter can accurately and quickly adjust voltage, frequency, and power between the grid and the energy storage system, achieving four-quadrant power operation. It can be used in scenarios such as power smoothing and peak shaving for photovoltaic and wind power generation. Accurate power control of the energy storage converter is the foundation for ensuring the safe and efficient operation of the system. Inaccurate power measurement will lead to a decrease in actual operating efficiency, preventing the system from operating at its optimal point and increasing energy loss. It may also affect the battery management system's decisions, leading to overcharging or over-discharging, affecting battery life, and even causing serious consequences such as thermal runaway.
[0026] On the other hand, during the inverter process, the AC side voltage of the energy storage converter contains abundant high-order harmonic components due to high-frequency switching operations. If it is directly connected to the grid without filtering, it will affect the grid voltage quality and disrupt the stability of the grid-connected system. While using an LC filter can remove high-order harmonics, the characteristics of the filter will cause the inductor current to be inconsistent with the actual grid-side output current, resulting in a deviation between the output active power and the given active power. It will also introduce capacitive reactive power, ultimately leading to power control deviations. Currently, the general solution is to add a grid-side current sampling circuit, but this method increases hardware costs.
[0027] In view of this, this application provides a four-quadrant power compensation calibration method, system, device, and medium for energy storage devices. This scheme collects DC-side circuit data, AC-side circuit data, and the actual capacitance value of the filter capacitor from the energy storage converter. For active power, the actual active power on the DC side is calculated based on the DC-side circuit data and used as the standard for AC-side calculation. The target phase difference is determined by combining the AC-side circuit data, and the phase-locked angle of the Park coordinate transformation is compensated using this target phase difference, thus achieving active power calibration. For reactive power, the reactive power compensation capacitor current is calculated based on the AC-side circuit data and the actual capacitance value of the filter capacitor. This reactive power compensation capacitor current is then added to the positive sequence Q-axis control loop within the grid-connected inner loop, achieving reactive power calibration. Compared to adding a grid-side current sampling circuit, this application only calculates the active and reactive power compensation strategies based on software and performs calibration, improving the accuracy of energy storage converter power control. Simultaneously, it eliminates the need for an additional grid-side current sampling circuit, reducing the cost of calibrating the energy storage converter power.
[0028] The four-quadrant power compensation calibration method for energy storage devices provided in this application relates to the field of power grid technology. This method can be applied to terminals, servers, or software running on either terminal or 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 four-quadrant power compensation calibration method for energy storage devices, but is not limited to the above forms.
[0029] 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, 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.
[0030] Figure 1 This is an optional flowchart of the four-quadrant power compensation calibration method for energy storage devices provided in the embodiments of this application. Figure 1 The method may include, but is not limited to, steps S101 to S103.
[0031] Step S101: Obtain the DC side circuit data, AC side circuit data, and actual capacitance value of the filter capacitor of the energy storage converter; For details, please refer to Figure 2 , Figure 2 This is a schematic diagram of an energy storage converter connected to the power grid. The energy storage battery is connected in parallel with the bus capacitor, and then connected to the power grid in parallel with a bidirectional DC / AC converter and a filter device. Figure 2 In the diagram, Bus+ and Bus- are the DC bus capacitances, r is the line equivalent impedance, L is the filter inductance, and C is the filter capacitor. For inductor current, For grid-side current, This is the grid voltage.
[0032] based on Figure 2 The circuit shown collects DC-side circuit data and AC-side circuit data, and determines the actual capacitance value of the filter capacitor for subsequent analysis and calculation. The DC-side circuit data includes at least DC voltage and DC current, while the AC-side circuit data includes at least inverter inductor current and inverter voltage.
[0033] Step S102: Determine the actual active power on the DC side based on the DC side circuit data, and determine the target phase difference based on the actual active power on the DC side and the AC side circuit data. When a filter is added to the circuit for active power, its characteristics cause a phase difference between the inductor current and the actual grid-side current, resulting in a deviation in active power.
[0034] To compensate for the calibration active power, this embodiment calculates the active power on both the DC and AC sides separately, and determines the compensation strategy by comparing the deviations. Specifically, the actual active power on the DC side is first calculated based on the DC voltage and DC current. Then, based on the AC side circuit data, the difference between the AC side's effective value of the inverter phase voltage and the inductor current is compared with the actual active power calculated on the DC side, ultimately determining the target phase difference. The effective value of the inverter phase voltage is... Figure 2 The root mean square value of the AC phase voltage output by the inverter shown in the figure over one cycle represents the DC voltage equivalent to that phase voltage in terms of energy transfer.
[0035] Step S103: Determine the reactive power compensation capacitor current based on the AC side circuit data and the actual capacitance value of the filter capacitor; For reactive power, since the filter itself also acts as an energy storage element (including inductors and capacitors), it will change the original reactive power balance of the system, thus resulting in a reactive power deviation.
[0036] To compensate for reactive power during calibration, this embodiment calculates the reactive power compensation capacitor current based on the rated phase voltage, rated phase current, and actual capacitance of the filter capacitor using AC side circuit data. The rated phase voltage is the standard effective value of the phase voltage designed for the inverter under normal operating conditions; the rated phase current is the standard effective value of the phase current designed for the inverter under normal operating conditions; and the actual capacitance of the filter capacitor refers to the actual capacitance value exhibited by the filter capacitor under actual operating conditions, not its nominal capacitance.
[0037] In step S104, during the Park coordinate transformation process of the power grid, the active power is calibrated by applying target phase difference compensation to the phase-locked angle; in the positive sequence control loop of the Q-axis of the grid-connected inner loop, the reactive power is calibrated by applying reactive power compensation capacitor current compensation.
[0038] Based on the calculation of the target phase difference and reactive power compensation capacitor current in the above steps, refer to Figure 3 , Figure 3This diagram illustrates the loop feedback and inner control loop obtained through grid-connected coordinate transformation. It can be understood that the collected three-phase inverter inductor current is transformed from a three-phase stationary coordinate system to a two-phase stationary coordinate system via Clark transformation, and then to a two-phase rotating coordinate system via Park transformation, thus converting the control of the three-phase non-DC quantity into the control of the DC quantity. On the other hand, the inner control loop includes four control loops with positive and negative sequences on the D and Q axes. Based on this, it also needs to undergo coordinate inverse transformations corresponding to the Park and Clark transformations to transform from two-phase back to three-phase, obtaining three sinusoidal modulation waves, thereby generating three-phase PWM control signals and forming the power control process. During the above transformation process, applying a target phase difference to the phase-locked angle in the Park coordinate transformation for phase compensation completes the calibration of the active power. Figure 3 China and Israel Indicates the phase-locked angle, with This indicates the target phase difference; while in the Q-axis positive sequence control loop of the inner loop control circuit, reactive power compensation capacitor current is added. This allows for the calibration of reactive power. Thus, compensation calibration is performed on both active and reactive power.
[0039] In this embodiment, active power and reactive power are compensated and calibrated separately. The specific order of steps S101 to S104 is not limited. The actual execution order can follow the order of data acquisition, data processing, and calibration compensation, as described above.
[0040] Furthermore, the DC voltage, DC current, inverter voltage, RMS inverter phase voltage, inductor current, rated phase voltage, rated phase current, and actual capacitance of the filter capacitor used in the calculations in this embodiment are all reference values. Figure 2 The circuit and the above description of the parameters can be obtained directly from the circuit, preset by the device, or determined directly through simple transformation. In this embodiment, the source of the parameters will not be described again.
[0041] Steps S101 to S104 as shown in the embodiments of this application improve the accuracy of power control of the energy storage converter by calculating the compensation strategy of active power and reactive power based solely on software and performing calibration. At the same time, it eliminates the need to add an additional grid-side current sampling circuit, thereby reducing the cost of calibrating the power of the energy storage converter.
[0042] Please see Figure 4 In some embodiments, step S102 may include, but is not limited to, steps S201 to S203: Step S201: Determine the operating level of the energy storage converter based on the DC voltage and DC current, and determine the mapping conversion efficiency according to the operating level; Step S202: Based on the operating mode of the energy storage converter, determine the actual active power on the DC side according to the DC voltage, DC current and conversion efficiency. The operating mode includes inverter mode or rectifier mode. Step S203: Determine the target phase difference based on the actual active power, the effective value of the inverter phase voltage, and the effective value of the inductor current.
[0043] For energy storage converters, their conversion efficiency is related to multiple factors. In this embodiment, the operating level of the energy storage converter can be inferred from the DC voltage and DC current. A mapping table between DC voltage, DC current, and conversion efficiency is set up. Through this mapping table, the appropriate conversion efficiency for calculating the actual active power can be inferred based on the DC voltage and DC current. In other embodiments, since other factors may affect the operating level of the energy storage converter, thereby affecting the conversion efficiency, such as inverter voltage, inductor current, temperature, and reference power determined based on DC voltage and DC current, the mapping table can also be set up in conjunction with the above parameters. The operating level is determined based on at least one of the parameters, including DC voltage, DC current, temperature, inverter voltage, inductor current, and reference power, and then the mapped conversion efficiency is determined. The mapped conversion efficiency is determined through more multi-dimensional data.
[0044] Based on DC voltage, DC current, and conversion efficiency, the actual active power can be calculated. During the calculation, the current operating mode of the energy storage converter also needs to be considered, with different calculation methods applicable to different operating modes. Operating modes include rectification mode and inverter mode. Rectification mode converts AC power to DC power, i.e., it charges the energy storage battery. Inverter mode converts DC power to AC power, i.e., it converts the electrical energy stored in the energy storage battery into AC power for transmission to the grid or supply to the load.
[0045] Based on the actual active power calculated on the DC side, and given a fixed and accurate value for the actual active power, the active power can then be further calculated based on the effective value of the inverter phase voltage and the inductor current on the AC side. The target phase difference can then be determined based on the deviation.
[0046] By combining conversion efficiency and operating mode, the actual active power is calculated, improving the accuracy of the calculated actual active power, and supporting comparison with the calculation on the AC side to achieve calibration of active power.
[0047] In some embodiments, step S202 may include, but is not limited to: In response to the inverter mode, the actual active power is determined by the third product of DC voltage, DC current and conversion efficiency.
[0048] When the energy storage converter operates in inverter mode, the relationship between the actual active power, DC voltage, DC current and conversion efficiency can be referred to the following formula (1): (1) in, This represents the actual active power. DC voltage It is direct current. The conversion efficiency is calculated by multiplying the DC voltage, DC current, and conversion efficiency. This product is defined as the third product, which represents the actual active power in inverter mode.
[0049] By calculating the actual active power in inverter mode, it supports the calibration and compensation of active power of the energy storage converter in inverter mode.
[0050] In some embodiments, step S202 may include, but is not limited to: In response to the operating mode being rectification mode, the fourth product of DC voltage and DC current is calculated, and the actual active power is determined based on the ratio of the fourth product to the first conversion efficiency.
[0051] When the energy storage converter operates in rectification mode, the relationship between the actual active power, DC voltage, DC current and conversion efficiency can be referred to the following formula (2): (2) in, This represents the actual active power. DC voltage It is direct current. To determine the conversion efficiency, calculate the product of DC voltage and DC current, define this product as the fourth product, then calculate the ratio of the fourth product to the conversion efficiency, define this ratio as the first ratio, and this first ratio is the actual active power in rectification mode.
[0052] By calculating the actual active power in rectification mode, it supports the calibration and compensation of active power of the energy storage converter in rectification mode.
[0053] In some embodiments, step S203 may include, but is not limited to: Based on the fact that there is no phase difference between the inductor current and the grid-side current, a first calculation formula is constructed. The first calculation formula is that the product of the effective value of the inverter phase voltage, the effective value of the inductor current, the cosine value of the first phase, and the first preset coefficient equals the actual active power. The first phase is determined according to the first calculation formula, and the first phase is the phase difference between the inverter voltage and the inductor current. Based on the phase difference between the inductor current and the grid-side current, a second calculation formula is constructed. The second calculation formula is the product of the effective value of the inverter phase voltage, the effective value of the inductor current, the cosine value of the second phase, and the second preset coefficient, which equals the actual active power. The target phase difference is determined according to the second calculation formula, where the second phase is the sum of the first phase and the target phase difference.
[0054] The calculation of the active power deviation on the AC side is carried out in two steps. First, it is assumed that there is no phase difference between the inductor current and the grid-side current. At this time, the relationship between the effective value of the inverter phase voltage, the effective value of the inductor current, the first phase, the preset coefficient and the actual active power satisfies the first calculation formula, namely the following formula (3): (3) in, The actual active power is preset with a coefficient of 3. This is the effective value of the inverter phase voltage. This is the effective value of the inductor current. The first phase is determined by equation (3). This first phase represents the phase difference between the inverter voltage and the inductor current.
[0055] Then, the phase difference between the inductor current and the grid-side current can be taken into account to redetermine the relationship between the effective value of the inverter phase voltage, the effective value of the inductor current, the second phase (the sum of the first phase and the target phase difference), the preset coefficient and the actual active power, satisfying the second calculation formula, namely the following formula (4): (4) in, For the second phase, The target phase difference is the objective phase difference; other parameters are not elaborated upon. The objective phase difference can be calculated and determined using equation (4).
[0056] By setting two scenarios where there is a phase difference between the inductor current and the grid-side current, the phase difference between the inverter voltage and the inductor current is first calculated, and then the target phase difference is calculated in combination with this phase difference (the first phase). This allows for the determination of how to accurately compensate and calibrate active power entirely from the software level, thereby improving the accuracy of power control of the energy storage converter while reducing calibration costs.
[0057] Please see Figure 5 In some embodiments, step S103 may include, but is not limited to, steps S301 to S304: Step S301: Calculate the second ratio of the rated phase voltage to the rated phase current, and determine the normalized parameter of the filter capacitor based on the fifth product of the second ratio and the actual capacitance value of the filter capacitor. Step S302: Determine the grid frequency through a software phase-locked loop, and determine the grid angular frequency based on the grid frequency; Step S303: Determine the per-unit value of the d-axis voltage component based on the inverter voltage, and define it as the per-unit value of the inverter voltage; Step S304: Determine the reactive power compensation capacitor current based on the normalized parameters of the filter capacitor, the grid angular frequency, and the per-unit value of the inverter voltage.
[0058] To compensate for the reactive power during calibration, the normalized parameters of the filter capacitor are first calculated according to the relationship between the rated phase voltage, the rated phase current, and the actual capacitance of the filter capacitor, based on the following formula (5): (5) in, These are the normalized parameters for the filter capacitor. This is the actual capacitance value of the filter capacitor. This is the rated value of the phase voltage. The phase current is the rated value. First, calculate the ratio of the rated phase voltage to the rated phase current, and define this ratio as the second ratio. Then, calculate the product of the second ratio and the actual capacitance value of the filter capacitor, and define this product as the fifth product. This fifth product is also the normalized parameter of the filter capacitor. This process allows the physical value of the capacitor to be scaled proportionally according to the rated voltage and current of the energy storage converter, so that the reactive power compensation capacitor current obtained in the final calculation can be directly adapted to the control system.
[0059] On the other hand, a software phase-locked loop (PLL) is also set in the system of this embodiment. Compared with the hardware PLL, the software PLL completes phase detection, error adjustment and signal generation through the computing power of the digital processor, and has higher flexibility and customizability. This also matches the requirement of this application embodiment to reduce the power cost of calibrating energy storage converters. Through the software PLL, the grid frequency and phase-locked angle can be calculated and obtained in real time. Therefore, the phase-locked angle used in the Park coordinate transformation can be directly obtained through the software PLL. The relationship between the grid frequency and the grid angular frequency satisfies the following equation (6): (6) in, The angular frequency of the power grid. Let be the grid frequency. The grid angular frequency can be calculated using equation (6).
[0060] Furthermore, regarding the d-axis voltage component of the inverter voltage, please refer to... Figure 3The Clark and Park transformations shown apply to the inductor current. The same coordinate transformation is performed on the inverter voltage, converting it from a three-phase stationary coordinate system to a two-phase rotating coordinate system (including the d-axis and q-axis). The d-axis component is forced to coincide with the direction of the grid voltage fundamental positive sequence vector, thus anchoring the grid's reference direction. The per-unit value of the d-axis voltage component is then calculated. The per-unit value is the ratio between its actual value and the reference value, i.e., the ratio between the actual value and the rated phase voltage. This ratio is defined as the inverter voltage per-unit value.
[0061] Based on the normalized parameters of the filter capacitor, the grid angular frequency, and the per-unit value of the inverter voltage obtained from the above steps, further calculations can be performed in subsequent steps to determine the reactive power compensation capacitor current, thereby achieving reactive power compensation calibration.
[0062] Please see Figure 6 In some embodiments, step S304 may include, but is not limited to, steps S305 and S306: Step S305: Calculate the sixth product of the normalized parameters of the filter capacitor and the grid angular frequency, and determine the capacitive reactance of the filter capacitor based on the reciprocal of the sixth product; Step S306: Determine the reactive power compensation capacitor current based on the third ratio of the inverter voltage per unit value to the capacitive reactance of the filter capacitor.
[0063] Specifically, the capacitive reactance of the filter capacitor is first calculated and determined. The relationship between the normalized parameters of the filter capacitor and the grid angular frequency satisfies the following equation (7): (7) in, For the capacitive reactance of the filter capacitor, The angular frequency of the power grid. Here are the normalized parameters for the filter capacitor. Calculate the product of the normalized parameters for the filter capacitor and the grid angular frequency. Define this product as the sixth product, and the reciprocal of this sixth product is the capacitive reactance of the filter capacitor.
[0064] Based on the obtained filter capacitor reactance, and according to the relationship between the inverter voltage per unit value, the filter capacitor reactance, and the reactive power compensation capacitor current, we have the following equation (8): (8) in, For reactive power compensation capacitor current, This is the per-unit value of the inverter voltage. Calculate the ratio of the per-unit value of the inverter voltage to the capacitive reactance of the filter capacitor. Define this ratio as the third ratio, which is also the reactive power compensation capacitor current.
[0065] By using AC side circuit data to calculate the reactive power compensation capacitor current, the method of accurately compensating and calibrating reactive power can be determined entirely at the software level, thereby improving the accuracy of power control of the energy storage converter while reducing calibration costs.
[0066] refer to Figure 7 , Figure 7 A line graph illustrating the power comparison effect of applying the method of the above embodiments is shown. Figure 7 In the above embodiments, curve P is the original active power curve, with a maximum power deviation of 6.98%. The active power after calibration by the above embodiment method is curve P_Adjust, and the power accuracy is controlled within ±2%. Curve Q is the original reactive power curve, with a maximum power deviation of 7.01%. The reactive power after calibration by the above embodiment method is curve Q_Adjust, and the power accuracy is controlled within ±2%. In addition, curve PQ_can is the theoretical curve when active and reactive power are applied simultaneously. The uncalibrated original curve is curve PQ, which also has a deviation exceeding ±2%. After calibration, it becomes curve PQ_Adjust, which can also control the power accuracy within ±2%.
[0067] The following is a detailed description and explanation of the solutions in the embodiments of the present invention, using specific application examples: This application provides a four-quadrant power compensation calibration method for an energy storage device, applicable to environments where energy storage converters are connected to the power grid. The method involves collecting DC voltage and DC current on the DC side of the energy storage converter; collecting inverter voltage and inductor current on the AC side; and determining the effective value of the inverter phase voltage, the effective value of the inductor current, and the per-unit value (defined as the per-unit value of the inverter voltage's d-axis voltage component) based on these data. The phase-locked loop angle and grid frequency are determined using a software phase-locked loop. Additionally, the actual capacitance value of the filter capacitor, as well as the preset rated values of the phase voltage and phase current of the energy storage converter, are determined.
[0068] For active power, the operating level of the energy storage converter is determined based on DC voltage and DC current, and the mapped conversion efficiency is determined according to the operating level. Then, the operating mode of the energy storage converter is determined. When the operating mode is inverter mode, the third product of DC voltage, DC current and conversion efficiency is calculated to determine the actual active power; when the operating mode is rectification mode, the fourth product of DC voltage and DC current is calculated, and the ratio of the fourth product to the first conversion efficiency is calculated to determine the actual effective power. First, assuming no phase difference between the inductor current and the grid-side current, a first calculation formula is constructed. This formula is the product of the RMS inverter voltage, the RMS inductor current, the cosine of the first phase, and a preset coefficient, equaling the actual active power. The first phase, representing the phase difference between the inverter voltage and the inductor current, is derived from this formula. Next, assuming a phase difference exists between the inductor current and the grid-side current, a second calculation formula is constructed. This second formula is the product of the RMS inverter voltage, the RMS inductor current, the cosine of the second phase, and a preset coefficient, equaling the actual active power. The second phase is the sum of the first phase and the target phase difference. The target phase difference can then be derived from this second formula. Using this target phase difference, during the Park coordinate transformation of the power grid, the target phase difference is applied to the phase-locked loop angle to compensate and calibrate the active power.
[0069] For reactive power, the second ratio of the rated phase voltage to the rated phase current is calculated, and the fifth product of this second ratio and the actual capacitance of the filter capacitor is calculated to determine the normalized parameter of the filter capacitor. The grid angular frequency is calculated based on the grid frequency. Then, the sixth product of the normalized parameter of the filter capacitor and the grid angular frequency is calculated, and the reciprocal of this sixth product is used to determine the capacitive reactance of the filter capacitor. Next, the third ratio of the per-unit inverter voltage to the capacitive reactance of the filter capacitor is calculated to determine the reactive power compensation capacitor current. Using this reactive power compensation capacitor current, it is applied in the positive sequence Q-axis control loop of the grid-connected inner loop to compensate and calibrate the reactive power.
[0070] This application embodiment improves the accuracy of power control of energy storage converters by calculating active and reactive power compensation strategies solely based on software and performing calibration, while eliminating the need for additional grid-side current sampling circuits and reducing the cost of calibrating the power of energy storage converters.
[0071] Please see Figure 8 This application also provides a four-quadrant power compensation calibration system for an energy storage device, which can implement the above-mentioned method. The system includes: The data acquisition module is used to acquire DC-side circuit data, AC-side circuit data, and actual capacitance values of the filter capacitors of the energy storage converter. The active power processing module is used to determine the actual active power on the DC side based on the DC side circuit data, and to determine the target phase difference based on the actual active power on the DC side and the AC side circuit data; during the Park coordinate transformation process of the power grid, the active power is calibrated by applying the target phase difference compensation to the phase-locked angle. The reactive power processing module is used to determine the reactive power compensation capacitor current based on the AC side circuit data and the actual capacitance value of the filter capacitor; in the grid-connected inner loop Q-axis positive sequence control loop, the reactive power compensation capacitor current is applied to compensate and calibrate the reactive power.
[0072] It is understood that the content of the above method embodiments is applicable to this system embodiment. The specific functions implemented in this system 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.
[0073] This application also provides a computer 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 method. This computer device can be any smart terminal, including tablet computers, in-vehicle computers, etc.
[0074] 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.
[0075] Please see Figure 9 , Figure 9 The hardware structure of a computer device according to another embodiment is illustrated. The computer 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 methods described in the embodiments of this application. The input / output interface 903 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, network 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 interconnected within the device via bus 905.
[0076] This application also provides a computer-readable storage medium storing a computer program that, when executed by a processor, implements the above-described method.
[0077] 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.
[0078] 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.
[0079] The four-quadrant power compensation calibration method, system, device, and medium for energy storage devices provided in this application collect DC-side circuit data, AC-side circuit data, and the actual capacitance value of the filter capacitor from the energy storage converter. For active power, the actual active power on the DC side is calculated based on the DC-side circuit data and used as the standard for AC-side calculation. The target phase difference is determined by combining the AC-side circuit data, and the phase-locked angle of the Park coordinate transformation is compensated using this target phase difference, thus achieving active power calibration. For reactive power, the reactive power compensation capacitor current is calculated based on the AC-side circuit data and the actual capacitance value of the filter capacitor. This reactive power compensation capacitor current is then added to the positive sequence Q-axis control loop of the grid-connected inner loop, achieving reactive power calibration. Compared to adding a grid-side current sampling circuit, this application only calculates the active and reactive power compensation strategies based on software and performs calibration, improving the accuracy of energy storage converter power control. Simultaneously, it eliminates the need for an additional grid-side current sampling circuit, reducing the cost of calibrating the energy storage converter power.
[0080] 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.
[0081] 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.
[0082] 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.
[0083] 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.
[0084] 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.
[0085] 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.
[0086] 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.
[0087] 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.
[0088] 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.
[0089] 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.
[0090] 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 four-quadrant power compensation calibration method for an energy storage device, characterized in that, The method includes the following steps: Obtain DC-side circuit data, AC-side circuit data, and actual capacitance values of the filter capacitors from the energy storage converter; The actual active power on the DC side is determined based on the DC side circuit data, and the target phase difference is determined based on the actual active power on the DC side and the AC side circuit data. During the Park coordinate transformation of the power grid, the active power is calibrated by applying the target phase difference to the phase-locked angle. The reactive power compensation capacitor current is determined based on the AC side circuit data and the actual capacitance value of the filter capacitor; the reactive power compensation capacitor current is applied to compensate and calibrate the reactive power in the Q-axis positive sequence control loop of the grid-connected inner loop.
2. The method according to claim 1, characterized in that, The DC-side circuit data includes DC voltage and DC current, and the AC-side circuit data includes the effective value of the inverter phase voltage and the effective value of the inductor current. The step of determining the actual active power on the DC side based on the DC-side circuit data, and determining the target phase difference based on the actual active power on the DC side and the AC-side circuit data, includes: The operating condition level of the energy storage converter is determined based on the DC voltage and the DC current, and the mapping conversion efficiency is determined based on the operating condition level. Based on the operating mode of the energy storage converter, the actual active power on the DC side is determined according to the DC voltage, the DC current and the conversion efficiency. The operating mode includes inverter mode or rectifier mode. The target phase difference is determined based on the actual active power, the effective value of the inverter phase voltage, and the effective value of the inductor current.
3. The method according to claim 2, characterized in that, Determining the target phase difference based on the actual active power, the effective value of the inverter phase voltage, and the effective value of the inductor current includes: Based on the absence of a phase difference between the inductor current and the grid-side current, a first calculation formula is constructed. The first calculation formula is the product of the effective value of the inverter phase voltage, the effective value of the inductor current, the cosine value of the first phase, and a preset coefficient, which equals the actual active power. The first phase is determined according to the first calculation formula, and the first phase is the phase difference between the inverter voltage and the inductor current. Based on the phase difference between the inductor current and the grid-side current, a second calculation formula is constructed. The second calculation formula is the product of the effective value of the inverter phase voltage, the effective value of the inductor current, the cosine value of the second phase, and a preset coefficient, which equals the actual active power. The target phase difference is determined according to the second calculation formula, wherein the second phase is the sum of the first phase and the target phase difference.
4. The method according to claim 2, characterized in that, The determination of the actual active power on the DC side based on the operating mode of the energy storage converter, according to the DC voltage, the DC current, and the conversion efficiency, includes: In response to the operating mode being the inverter mode, the actual active power is determined based on a third product of the DC voltage, the DC current, and the conversion efficiency.
5. The method according to claim 2, characterized in that, The determination of the actual active power on the DC side based on the operating mode of the energy storage converter, according to the DC voltage, the DC current, and the conversion efficiency, includes: In response to the operating mode being the rectification mode, the fourth product of the DC voltage and the DC current is calculated, and the actual active power is determined based on the first ratio of the fourth product to the conversion efficiency.
6. The method according to claim 1, characterized in that, The AC side circuit data includes the rated phase voltage, rated phase current, and inverter voltage. Determining the reactive power compensation capacitor current based on the AC side circuit data and the actual capacitance value of the filter capacitor includes: Calculate the second ratio of the rated phase voltage to the rated phase current, and determine the normalized parameter of the filter capacitor based on the fifth product of the second ratio and the actual capacitance value of the filter capacitor; The grid frequency is determined by a software phase-locked loop, and the grid angular frequency is determined based on the grid frequency. The per-unit value of the d-axis voltage component is determined based on the inverter voltage and is defined as the per-unit value of the inverter voltage. The reactive power compensation capacitor current is determined based on the normalized parameters of the filter capacitor, the grid angular frequency, and the per-unit value of the inverter voltage.
7. The method according to claim 6, characterized in that, The step of determining the reactive power compensation capacitor current based on the normalized parameters of the filter capacitor, the grid angular frequency, and the inverter voltage per-unit value includes: Calculate the sixth product of the normalized parameter of the filter capacitor and the angular frequency of the power grid, and determine the capacitive reactance of the filter capacitor based on the reciprocal of the sixth product; The reactive power compensation capacitor current is determined based on the third ratio of the inverter voltage per-unit value to the capacitive reactance of the filter capacitor.
8. A four-quadrant power compensation calibration system for an energy storage device, characterized in that, The system includes: The data acquisition module is used to acquire DC-side circuit data, AC-side circuit data, and actual capacitance values of the filter capacitors of the energy storage converter. The active power processing module is used to determine the actual active power on the DC side based on the DC side circuit data, and to determine the target phase difference based on the actual active power on the DC side and the AC side circuit data; during the Park coordinate transformation of the power grid, the active power is calibrated by applying the target phase difference to the phase-locked angle. The reactive power processing module is used to determine the reactive power compensation capacitor current based on the AC side circuit data and the actual capacitance value of the filter capacitor; and to apply the reactive power compensation capacitor current to compensate and calibrate reactive power in the Q-axis positive sequence control loop of the grid-connected inner loop.
9. A computer device, characterized in that, The computer device includes a memory and a processor, the memory storing a computer program, and the processor executing the computer program to implement the method according to any one of claims 1 to 7.
10. A computer-readable storage medium storing a computer program, characterized in that, When the computer program is executed by a processor, it implements the method of any one of claims 1 to 7.