Split-phase control method applied to three-phase three-leg energy storage converter
By employing a phase-by-phase control method combining sliding window discrete Fourier transform and proportional-integral-resonant control, the control architecture of a three-phase three-bridge-arm energy storage converter is simplified, solving the three-phase imbalance problem in rural power grids, reducing hardware and algorithm complexity, and improving computational efficiency.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- PINGGAO GRP CO LTD
- Filing Date
- 2026-01-12
- Publication Date
- 2026-05-01
AI Technical Summary
Existing three-phase four-arm topology energy storage converters are difficult to effectively solve the three-phase imbalance problem in rural power grids, and the control architecture is complex, increasing hardware and algorithm costs.
The active and reactive components of the three-phase voltage and current are extracted by using a sliding window discrete Fourier transform. The active and reactive components are then combined with a proportional-integral and proportional-resonant controller for closed-loop control to generate PWM drive signals to drive the arms of the three-phase three-arm energy storage converter. The coordinate transformation and the fourth arm are omitted.
The control architecture was simplified, hardware costs were reduced, and computing efficiency was improved, achieving stable control of three-phase current and solving the three-phase imbalance problem.
Smart Images
Figure CN121966200A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of software algorithm control strategy technology, and more specifically to a phase-by-phase control method for a three-phase three-arm energy storage converter. Background Technology
[0002] Currently, in the commercial and industrial energy storage converter application market, the basic peak-valley arbitrage model can no longer meet the increasingly diversified customer needs. Commercial and industrial energy storage is also actively seeking new market opportunities. However, due to the power level limitations of commercial and industrial energy storage converters, their application in some large-scale energy storage power stations is unlikely. Instead, they are seeking new breakthroughs in some substation energy storage application scenarios.
[0003] However, in some rural power grid areas, the end load is small, the load connection is chaotic, and the transmission lines are long and severely aged, leading to frequent three-phase imbalance problems. To address this issue, a cloud-based master station monitors the power grid status and regulates the energy storage converter to compensate for or consume grid energy in each phase, thereby raising or lowering the voltage of that phase and mitigating the voltage imbalance. This, combined with the energy storage battery, improves power quality at the end of the grid. The energy storage converter used in this environment is typically a three-phase, four-arm topology. Since the control architecture of energy storage converters is usually implemented in the dq coordinate system, a transformation from abc coordinates to dq coordinates is generally performed, and then the fourth arm controls the zero-sequence current to achieve current path for each phase.
[0004] Therefore, finding a new control architecture to meet the function of phase-separated operation is a problem that urgently needs to be solved by those skilled in the art. Summary of the Invention
[0005] In view of the above problems, the present invention is proposed to provide a phase-by-phase control method for a three-phase three-arm energy storage converter that overcomes or at least partially solves the above problems.
[0006] To achieve the above objectives, the present invention adopts the following technical solution: In a first aspect, embodiments of the present invention provide a phase-splitting control method applied to a three-phase three-arm energy storage converter, comprising: S1. Sample the voltage and current signals of the three-phase power grid to obtain the instantaneous values of voltage and current for each phase; S2. For each phase, the active and reactive components of the phase are extracted from the instantaneous values of voltage and current of each phase using a sliding window discrete Fourier transform. S3. Compare the active and reactive components of each phase with the given reference values to obtain the error signal; S4. Input the error signal of each phase into the corresponding controller for closed-loop control and generate the modulation signal of each phase; S5. Compare the modulation signal of each phase with the carrier signal to generate a PWM drive signal to drive the corresponding bridge arm of the three-phase three-bridge-arm energy storage converter.
[0007] Furthermore, the specific process in S2 of extracting the active and reactive components of each phase from the instantaneous values of voltage and current using the sliding window discrete Fourier transform is as follows: Set the depth of the sliding window to N; For each phase, use the phase angle θ of that phase to calculate sin(θ) and cos(θ) respectively; Multiply sin(θ) and cos(θ) by the instantaneous voltage or current value of the phase, and then multiply by the reciprocal of the sliding window depth to obtain intermediate variables; The intermediate variables are filtered by a sliding window filter, which is implemented by a sliding window array. The array is updated once for each sample, and the cumulative sum within the current window is calculated to obtain the active and reactive components of the phase voltage or current.
[0008] The sliding window depth N is determined by the sampling frequency and the power grid frequency: N = sampling frequency / power grid frequency.
[0009] Furthermore, the reference values given in S3 are: the active and reactive components of the reference current; The specific process of generating errors is as follows: The error term of each phase current is obtained by subtracting the active and reactive components from the active and reactive components of the given reference current.
[0010] Furthermore, the controller in S4 includes: a proportional-integral controller and a proportional-resonant controller; The proportional-integral controller and the proportional-resonant controller work in parallel. The proportional-integral controller is used to control the DC and low-frequency components, while the proportional-resonant controller is used to provide high gain at the fundamental frequency.
[0011] Furthermore, generating the modulation signal for each phase in S4 also includes: limiting the modulation signal to keep it within the range of [-1, 1].
[0012] Furthermore, the specific process of generating the PWM drive signal in S5 is as follows: The carrier signal is a unipolar carrier; The modulating signal is compared with the carrier signal. When the modulating signal is greater than the carrier signal, the PWM output is high; when the modulating signal is less than the carrier signal, the PWM output is low.
[0013] A computer-readable storage medium having a computer program stored thereon that, when executed by a processor, implements the above-described method.
[0014] A computer device includes a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the program to implement the above-described method.
[0015] The beneficial effects of the above-described technical solutions provided in the embodiments of the present invention include at least the following: 1. The phase-separation control algorithm proposed in this invention has the characteristics of simple structure and easy implementation, omitting the complex calculation of coordinate transformation and saving the model decoupling process.
[0016] 2. This algorithm saves costs by omitting the material cost of the fourth bridge arm and simplifying the complexity of hardware design.
[0017] 3. The algorithm has a high degree of control model reusability, which improves the computational efficiency. The three-phase controllers are designed in a consistent manner, which is a reuse of a single controller. Attached Figure Description
[0018] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.
[0019] Figure 1 This is a flowchart of the overall solution provided in the embodiments of the present invention; Figure 2 This is a flowchart of the DQ component provided in an embodiment of the present invention. Detailed Implementation
[0020] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.
[0021] This invention discloses a phase-by-phase control method for a three-phase, three-arm energy storage converter, such as... Figure 1 As shown, it includes: S1. Sample the voltage and current signals of the three-phase power grid to obtain the instantaneous values of voltage and current for each phase; S2. For each phase, the active and reactive components of the phase are extracted from the instantaneous values of voltage and current of each phase using a sliding window discrete Fourier transform. S3. Compare the active and reactive components of each phase with the given reference values to obtain the error signal; S4. Input the error signal of each phase into the corresponding controller for closed-loop control and generate the modulation signal of each phase; S5. Compare the modulation signal of each phase with the carrier signal to generate a PWM drive signal to drive the corresponding bridge arm of the three-phase three-bridge-arm energy storage converter.
[0022] The specific implementation of this invention is as follows: First, the DQ-axis components of the controlled object in each phase are extracted using the Discrete Fourier Transform with a sliding window; this is the foundation of phase-by-phase control. The specific implementation process is as follows: Orthogonalize the sampled real-time data and perform sliding window filtering on the sampled real-time data.
[0023] If phase A voltage DQ is separated: A-phase voltage D-axis component (active component) acquisition: Temp = sin(theta_A) * Inv_M; temp is an intermediate variable in the calculation, theta_A is the phase angle of phase A voltage, and Inv_M is the reciprocal of the sliding window filter window depth; ②Ua_D=Ua_D+temp-Ua_DS[k];Ua_DS[k]=temp;Ua_D is the extracted A-phase voltage D-axis component, Ua_DS[k] is the sliding window filter array, and k is the scaling of the elements in the window.
[0024] Similarly, the Q-axis component (reactive component) can be obtained: Temp = cos(theta_A) * Inv_M; temp is an intermediate variable in the calculation, theta_A is the phase angle of phase A voltage, and Inv_M is the reciprocal of the sliding window filter window depth; Ua_Q = Ua_Q + temp - Ua_QS[k]; Ua_QS[k] = temp; Ua_Q is the extracted A-phase voltage D-axis component, Ua_QS[k] is the sliding window filter array, and k is the scaling of the elements within the window.
[0025] Single-phase sampled data is processed separately, unlike the traditional three-phase unified processing of coordinate transformation, which eliminates the need for decoupling. The algorithm design requires setting the window width to buffer the controlled object's data for one power grid cycle. The window width is determined by the frequency of the sampling period signal and the sampling frequency. For example, if the sampling frequency is 15kHz, the sampled signal period is 20ms, and the frequency is 50Hz, then the window width N = 15000 / 50 = 300. The controlled object includes the three-phase (A, B, C) power grid current, obtained through sampling and AD conversion. The sliding window process involves the cyclical change of the element index k in the sliding window filter array. An accumulation is performed after each sample, and the value is reset to zero after reaching a window width of 300, then the cycle continues. The sliding window filtering implementation involves adding a new value based on the k index each time the window slides, subtracting the old value to achieve a rolling update of the accumulated sum. Rolling through one 20ms power frequency cycle allows for the extraction and calculation of the DQ axis components of the single-phase controlled quantity. The specific implementation process is as follows: Figure 2 As shown: Then, the extracted DQ component is subtracted from the given reference current DQ component to generate error terms for the three-phase currents (A, B, and C), which are then fed into the three-phase PI and PR controllers for closed-loop control. The PI and PR controllers operate in parallel, primarily to ensure the controlled current reaches the target value and stabilizes. The desired interface is determined when the outputs of the PI and PR controllers approach zero, indicating steady-state control. Unlike traditional control models, phase-by-phase control requires a controller for each phase, increasing computation time; however, the controller design remains consistent, so algorithm complexity is not increased. Finally, the control output is superimposed with the voltage component to generate a modulated reference voltage. First, the reference voltage is limited to between ±1 to prevent overmodulation. Then, it is compared with a unipolar carrier to generate a PWM drive signal to control the bridge arm. When the modulated voltage is greater than the carrier counter value, a high-level PWM is output; when the modulated voltage is less than the carrier counter value, a low-level PWM is output. This continuous pulse output controls the switching transistors on the bridge arm for operation.
[0026] This embodiment provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the above-described method.
[0027] This embodiment provides a computer device, including a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the program, it implements the above-described method.
[0028] Readable storage media include: mobile storage devices, read-only memory (ROM), random access memory (RAM), magnetic disks or optical disks, and other media that can store program code.
[0029] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on its differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. For the apparatus disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the description is relatively simple; relevant parts can be referred to the method section.
[0030] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.
Claims
1. A phase-by-phase control method for a three-phase, three-arm energy storage converter, characterized in that, include: S1. Sample the voltage and current signals of the three-phase power grid to obtain the instantaneous values of voltage and current for each phase; S2. For each phase, the active and reactive components of the phase are extracted from the instantaneous values of voltage and current of each phase using a sliding window discrete Fourier transform. S3. Compare the active and reactive components of each phase with the given reference values to obtain the error signal; S4. Input the error signal of each phase into the corresponding controller for closed-loop control to generate the modulation signal of each phase; S5. Compare the modulation signal of each phase with the carrier signal to generate a PWM drive signal to drive the corresponding bridge arm of the three-phase three-bridge-arm energy storage converter.
2. The method as described in claim 1, characterized in that, The specific process of extracting the active and reactive components of each phase from the instantaneous values of voltage and current in S2 using the sliding window discrete Fourier transform is as follows: Set the depth of the sliding window to N; For each phase, use the phase angle θ of that phase to calculate sin(θ) and cos(θ) respectively; Multiply the sin(θ) and cos(θ) by the instantaneous voltage or current value of the phase, and then multiply by the reciprocal of the sliding window depth to obtain intermediate variables; The intermediate variables are filtered by a sliding window filter, which is implemented by a sliding window array. The array is updated once for each sample, and the cumulative sum within the current window is calculated to obtain the active and reactive components of the phase voltage or current.
3. The method as described in claim 2, characterized in that, The sliding window depth N is determined by the sampling frequency and the power grid frequency: N = sampling frequency / power grid frequency.
4. The method as described in claim 1, characterized in that, The reference values given in S3 are: the active and reactive components of the reference current. The specific process of generating the error is as follows: The error term of each phase current is obtained by subtracting the active and reactive components from the active and reactive components of the given reference current, and serving as the error signal.
5. The method as described in claim 1, characterized in that, The controller in S4 includes: a proportional-integral controller and a proportional-resonant controller; The proportional-integral controller and the proportional-resonant controller operate in parallel. The proportional-integral controller is used to control the DC and low-frequency components, while the proportional-resonant controller is used to provide high gain at the fundamental frequency.
6. The method as described in claim 1, characterized in that, The generation of each phase modulation signal in S4 further includes: limiting the amplitude of the modulation signal to control it within the range of [-1, 1].
7. The method as described in claim 1, characterized in that, The specific process of generating the PWM drive signal in S5 is as follows: The carrier signal is a unipolar carrier; The modulation signal is compared with the carrier signal. When the modulation signal is greater than the carrier signal, a high level PWM is output; when the modulation signal is less than the carrier signal, a low level PWM is output.
8. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the program is executed by the processor, it implements the method as described in any one of claims 1 to 7.
9. A computer device, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that, When the processor executes the program, it implements the method as described in any one of claims 1 to 7.