Method for prolonging operation life of multi-module parallel converter
By collecting operating status data of parallel converter modules, calculating the lifespan status factor and adaptively adjusting the droop coefficient, the power distribution is optimized, which solves the problem of uneven operating time between modules, extends the system lifespan, and reduces operation and maintenance costs.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-17
- Publication Date
- 2026-03-13
AI Technical Summary
In existing multi-module parallel converter systems, uneven operating times among modules lead to asynchronous aging, affecting the overall lifespan of the system and maintenance costs. There is a lack of an effective mechanism for managing the lifespan balancing among modules.
By collecting operating status data of parallel converter modules, calculating the lifespan status factor, and adaptively adjusting the droop coefficient to achieve lifespan balance among modules, the power distribution is optimized using software algorithms to reduce the burden on high-aging modules and extend the overall lifespan of the system.
It achieves proactive balancing of lifespan among modules, extends the overall reliability and service life of the system, reduces operation and maintenance costs, and is suitable for application scenarios that require long-term uninterrupted operation.
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Figure CN121663968A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of power electronic power converter technology, specifically a method for improving the service life of a multi-module parallel converter. Background Technology
[0002] With the rapid development of distributed energy sources such as wind power, photovoltaics, and energy storage, as well as data centers, the reliability and long-term operational life of their core power conversion devices, namely high-capacity converters, have become increasingly critical issues. Converter systems employing multiple modules in parallel have become the mainstream solution for medium- and high-power applications due to their advantages such as scalable capacity and ease of redundancy.
[0003] Multi-module parallel systems ensure instantaneous current balance among modules through current sharing control and enhance system availability through redundancy design. In existing technologies, the control of multi-module parallel converters primarily focuses on achieving precise instantaneous power sharing, suppressing parallel circulating current, and enabling seamless hot-swapping and system reconfiguration in case of module failure. When individual modules are taken out of service for maintenance or replacement due to abnormalities, the system can automatically adjust the output of the remaining modules to maintain the total output. Once the new or repaired modules are put back into operation, the system returns to normal current sharing operation.
[0004] However, this control strategy based on instantaneous states has inherent flaws. Modules undergoing maintenance or newly introduced have a much shorter historical operating time than modules that have been running continuously for extended periods in the system, leading to significant differences in cumulative operating time and aging levels among modules. The lifespan of a converter module is strongly correlated with the number of electrical and thermal stress cycles its critical power devices endure; uneven operating time directly translates into asynchronous aging processes. After long-term system operation, some prematurely aging modules may reach the end of their lifespan and fail prematurely. Even if the system still meets redundancy requirements, frequent unexpected downtime for maintenance will significantly increase maintenance costs and reduce the overall actual lifespan of the system.
[0005] For multi-module parallel converters, existing technologies lack a management mechanism for actively balancing the service life of modules. They fail to incorporate factors such as the historical cumulative operating time, losses, and number of thermal cycles of the modules as control variables into the system-level optimization control, thus failing to maximize the overall service life of the parallel system. Summary of the Invention
[0006] To address the problems existing in the prior art, this invention proposes a method for improving the service life of multi-module parallel converters.
[0007] The technical solution of the present invention is as follows: On the one hand, this invention proposes a method for improving the service life of multi-module parallel converters, the specific steps of which include: The operating status data of each parallel converter module in the multi-module parallel converter system is collected during each sampling and control cycle; the operating status data includes at least the cumulative operating time of each parallel converter module. The lifespan status factor of each parallel converter module is calculated based on the operating status data, serving as a comprehensive indicator reflecting the aging degree of each parallel converter module. Based on the lifespan state factor of each parallel converter module, the droop coefficient of the corresponding parallel converter module in the system droop control is adaptively adjusted, increasing the droop coefficient of the parallel converter module with the larger lifespan state factor to reduce the power load. The power distribution control of each parallel converter module is performed using the adjusted droop coefficient, and the droop coefficient of each parallel converter module is periodically adjusted.
[0008] In a preferred embodiment, the multi-module parallel converter system includes multiple parallel converter modules, a control module, a sensing and communication module, and a droop control module.
[0009] In a preferred embodiment, the control module is also equipped with a storage device for calculating the cumulative operating time of each parallel converter module.
[0010] In a preferred embodiment, each parallel converter module includes a droop control module, which includes an active-frequency droop control loop and a reactive-voltage droop control loop.
[0011] In a preferred embodiment, the parallel converter module is specifically a three-phase two-level converter module connected in parallel, with its AC side connected to a common AC bus and its DC side connected in parallel to a common DC bus.
[0012] In a preferred embodiment, the operating status data also includes the output current, DC side voltage, key component temperature, historical average output current, and number of thermal cycles for each parallel converter module.
[0013] As a preferred embodiment, the method for calculating the lifetime state factor of each parallel converter module based on the operating status data is specifically as follows:
[0014] In the formula, i is the serial number of the parallel converter module; L i T is the lifetime state factor; i T represents the cumulative operating time of parallel converter module i; max I represents the maximum cumulative running time in the current parallel converter module i; rmsavg,i I represents the average effective value of the output current of parallel converter module i over the past time window; rated N is the rated current of parallel converter module i; T,i N represents the number of thermal cycles experienced by parallel converter module i; T,max The maximum number of large thermal cycles experienced by the current parallel converter module i; w T w I w These are the weighting coefficients for the corresponding items.
[0015] As a preferred embodiment, the method for adaptively adjusting the droop coefficient of the corresponding parallel converter module in the system droop control is specifically as follows:
[0016]
[0017] In the formula, k p0,i and k q0,i The baseline droop coefficient; α k is the lifespan balancing adjustment coefficient. pnew,i and k qnew,i This is the adjusted droop coefficient.
[0018] On the other hand, the present invention proposes an electronic 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 a method for improving the operating life of a multi-module parallel converter as described in any embodiment of the present invention.
[0019] On the other hand, the present invention proposes a computer-readable storage medium storing a computer program thereon, which, when executed by a processor, implements a method for improving the operating life of a multi-module parallel converter as described in any embodiment of the present invention.
[0020] The present invention has the following beneficial effects: 1. The method provided by this invention is the first to use the module's historical cumulative running time and aging status as core control variables, realizing a leap from "passive current sharing" to "active lifetime balancing".
[0021] 2. This invention dynamically calculates the adaptive droop coefficient based on the lifespan state factor, which significantly slows down the aging speed of the early-aging modules in the system at the cost of pure software algorithm, thereby extending the time for the system as a whole to reach the first major overhaul or failure, and improving the reliability of the entire life cycle.
[0022] 3. The method of this invention is compatible with existing parallel control architectures and does not require additional hardware costs. It is especially suitable for application scenarios such as photovoltaic inverters, energy storage converters, data center power supply and flexible DC power supply systems that require long-term uninterrupted operation and whose modules may be put into operation or replaced in batches. Attached Figure Description
[0023] Figure 1 This is a schematic diagram of a multi-module parallel converter system; Figure 2 Schematic diagram of active power-frequency droop control loop; Figure 3 This is a schematic diagram of the reactive power-voltage droop control loop; Figure 4 The output current waveforms of different modules during the initial running time are shown. Detailed Implementation
[0024] 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.
[0025] It should be understood that the step numbers used in the text are for ease of description only and are not intended to limit the order in which the steps are performed.
[0026] It should be understood that the terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to limit the invention. As used in this specification and the appended claims, the singular forms “a,” “an,” and “the” are intended to include the plural forms unless the context clearly indicates otherwise.
[0027] The terms “comprising” and “including” indicate the presence of the described feature, whole, step, operation, element and / or component, but do not exclude the presence or addition of one or more other features, wholes, steps, operations, elements, components and / or collections thereof.
[0028] The term “and / or” refers to any combination of one or more of the associated listed items, as well as all possible combinations, and includes these combinations.
[0029] Example 1: A method for improving the service life of a multi-module parallel converter includes the following steps: Step 1: Collect the operating status data of each parallel converter module in the multi-module parallel converter system within each sampling and control cycle; the operating status data shall include at least the cumulative operating time of each parallel converter module. The specific implementation method for this step is as follows: Appendix Figure 1The diagram shows a multi-module parallel converter system. This system comprises three parallel three-phase two-level converter modules, with their AC sides connected to a common AC bus and their DC sides connected in parallel to a common DC bus. The system's central controller is responsible for collecting data from each module and executing the lifetime balancing algorithm of this invention.
[0030] Each module employs droop control as its basic control strategy to achieve autonomous parallel connection without interconnects.
[0031] Appendix Figure 2 The diagram shows a schematic of the active-frequency droop control loop, whose control law is given by the following equation:
[0032] Among them, f i f is the frequency reference value for the output voltage of parallel converter module i. * k is the system's rated frequency. p,i P is the active power droop factor for parallel converter module i. i For its instantaneous output active power, P ref,i Its active power reference value.
[0033] Appendix Figure 3 The diagram shows a reactive power-voltage droop control loop, and its control law is as follows:
[0034] Among them, V i V is the reference value for the output voltage amplitude of parallel converter module i. * k is the system rated voltage. q,i Q is the reactive power droop factor. i Q is the instantaneous output reactive power. ref,i This is a reference value for reactive power. The core of this invention lies in the active adjustment of the droop coefficient, transforming it from a fixed value into a dynamic variable based on the module's lifetime status.
[0035] In this step, real-time acquisition and updating of operating status data are performed first. During each control cycle, the central controller collects the real-time output current and voltage of each parallel converter module through sensors and the communication system, and calculates the instantaneous output active power P of each parallel converter module. i With reactive power Q i Simultaneously, the controller reads the cumulative operating time T of the parallel converter modules from the memory. i This time is accumulated continuously from the moment the parallel converter module is first put into operation. Even if the parallel converter module is put back into operation after being repaired due to a fault, its accumulated value remains unchanged, thus truly reflecting the historical workload of the module.
[0036] Step 2: Calculate the life status factor of each parallel converter module based on the operating status data, which serves as a comprehensive indicator reflecting the aging degree of each parallel converter module. The specific implementation method for this step is as follows: To quantitatively compare the aging degree of each parallel converter module, a lifetime state factor L is calculated for each parallel converter module. i This factor comprehensively considers operating time, current stress, and the number of thermal cycles. The calculation formula is as follows:
[0037] Among them, T i T is the cumulative operating time of parallel converter module i. max The maximum cumulative running time in the current parallel converter module; I rmsavg,i I represents the average effective value of the output current of parallel converter module i over the past time window, reflecting its recent current stress level; rated N represents the rated current of the parallel converter module. T,i The number of large thermal cycles experienced by parallel converter module i, such as junction temperature changes. T j >N times a certain threshold; T,max The maximum number of large thermal cycles experienced by the current parallel converter module i; w T w I w The weight coefficients for the corresponding terms (satisfying w) T + w I + w =1), which can be determined based on the actual device lifespan model. This formula combines the long-term wear time, short-term current stress, and maximum thermal cycle count of the parallel converter module, making L... i Larger parallel converter modules are considered to be more aged and need to be taken care of in power distribution.
[0038] Step 3: Based on the lifetime state factor of each parallel converter module, adaptively adjust the droop coefficient of the corresponding parallel converter module in the system droop control, increase the droop coefficient of the parallel converter module with the larger lifetime state factor, and reduce the power load. The specific implementation method for this step is as follows: The droop coefficient k is adaptively adjusted based on the lifespan state factors of each parallel converter module. p,i and k q,i Make it consistent with the lifetime state factor L i Positive correlation:
[0039]
[0040] Where, k p0,i and k q0,i k is the baseline droop coefficient. pnew,i and k qnew,i This is the adjusted droop coefficient. α This is the lifespan balancing adjustment coefficient. Through the above modifications, for L... i Larger modules have steeper droop characteristics, automatically reducing the power they bear when operating in parallel, thus diverting power to L. i Smaller module transfer enables closed-loop control for power distribution and lifespan balance.
[0041] Step 4: Use the adjusted droop coefficient to perform power distribution control on each parallel converter module, and periodically adjust the droop coefficient of each parallel converter module.
[0042] The specific implementation method for this step is as follows: Based on the continuous operation of the multi-module parallel converter system, steps one through four are repeated periodically. Over time, modules that originally had longer operating times will be allowed to rest, while modules with shorter operating times will take on more work. This gradually brings the cumulative operating time and aging of all modules closer together and maintains them within a balanced range, ultimately maximizing the overall lifespan of the system.
[0043] Based on the above steps, in order to verify the effectiveness of the method described in this invention, examples are used to verify the method of this invention: Appendix Figure 4 The output current waveforms of three modules with different initial operating times are shown after applying the method of this invention. It can be clearly seen that the peak currents (reflecting the active power each module bears) of the three modules are not equal, but rather exhibit a relationship of I3 > I2 > I1. This is fundamentally different from the result of complete overlap of the three current waveforms under traditional current sharing control. This waveform visually demonstrates that the lifetime balancing algorithm is working: module 3, with the shortest operating time, has the largest output current and bears the most load; module 1, with the longest operating time, has the smallest output current and has achieved effective load reduction. With long-term operation, the aging rate of module 1 will slow down, while the aging rate of module 3 will appropriately accelerate, thereby gradually reducing the difference in the cumulative operating time of the three modules and extending the overall lifespan of the system.
[0044] Compared to traditional parallel control schemes that only pursue instantaneous power sharing, the method provided by this invention introduces the module's historical cumulative operating time, current stress, and thermal cycle count as core control variables into the real-time control loop. Through software algorithms, without increasing any hardware costs, the control objective of the parallel system is elevated from instantaneous current sharing to lifetime equalization, actively managing the long-term reliability of the system. This method is particularly suitable for photovoltaic power plants, energy storage systems, and flexible DC power supplies—where modules need to be put into operation in batches and require frequent replacement and maintenance—and other applications with extremely high requirements for system lifespan and availability.
[0045] The above description is merely an embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural or procedural transformations made based on the content of the present invention's specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of the present invention.
Claims
1. A method for improving the service life of a multi-module parallel converter, characterized in that, The specific steps include: The operating status data of each parallel converter module in the multi-module parallel converter system is collected during each sampling and control cycle; the operating status data includes at least the cumulative operating time of each parallel converter module. The lifespan status factor of each parallel converter module is calculated based on the operating status data, serving as a comprehensive indicator reflecting the aging degree of each parallel converter module. Based on the lifespan state factor of each parallel converter module, the droop coefficient of the corresponding parallel converter module in the system droop control is adaptively adjusted, increasing the droop coefficient of the parallel converter module with the larger lifespan state factor to reduce the power load. The power distribution control of each parallel converter module is performed using the adjusted droop coefficient, and the droop coefficient of each parallel converter module is periodically adjusted.
2. The method for improving the service life of a multi-module parallel converter according to claim 1, characterized in that, The multi-module parallel converter system includes multiple parallel converter modules, a control module, a sensing and communication module, and a droop control module.
3. The method for improving the service life of a multi-module parallel converter according to claim 2, characterized in that, The control module is also equipped with a storage device to track the cumulative operating time of each parallel converter module.
4. The method for improving the service life of a multi-module parallel converter according to claim 2, characterized in that, Each parallel converter module contains a droop control module, which includes an active-frequency droop control loop and a reactive-voltage droop control loop.
5. The method for improving the service life of a multi-module parallel converter according to claim 1, characterized in that, The parallel converter module is specifically a three-phase two-level converter module connected in parallel, with its AC side connected to a common AC bus and its DC side connected in parallel to a common DC bus.
6. The method for improving the service life of a multi-module parallel converter according to claim 1, characterized in that, The operating status data also includes the output current, DC side voltage, key component temperature, historical average output current, and number of thermal cycles for each parallel converter module.
7. The method for improving the service life of a multi-module parallel converter according to claim 1, characterized in that, The method for calculating the lifetime state factor of each parallel converter module based on the operating status data is as follows: In the formula, i is the serial number of the parallel converter module; L i T is the lifetime state factor. i T represents the cumulative operating time of parallel converter module i; max I represents the maximum cumulative running time in the current parallel converter module i; rmsavg,i I represents the average effective value of the output current of parallel converter module i over the past time window; rated N is the rated current of parallel converter module i; T,i N represents the number of thermal cycles experienced by parallel converter module i; T,max The maximum number of large thermal cycles experienced by the current parallel converter module i; w T w I w These are the weighting coefficients for the corresponding items.
8. The method for improving the service life of a multi-module parallel converter according to claim 1, characterized in that, The method for adaptively adjusting the droop coefficient of the corresponding parallel converter module in the system droop control is as follows: In the formula, k p0,i and k q0,i The baseline droop coefficient; α k is the lifespan balancing adjustment coefficient. pnew,i and k qnew,i This is the adjusted droop coefficient.
9. An electronic 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 a method for improving the service life of a multi-module parallel converter as described in any one of claims 1 to 8.
10. A computer-readable storage medium having a computer program stored thereon, characterized in that, When executed by the processor, the program implements a method for improving the service life of a multi-module parallel converter as described in any one of claims 1 to 8.