Harmonic suppression method for Si / SiC topological parallel inverter based on multi-harmonic observation and feedforward compensation

Abstract

The invention discloses a Si / SiC topological parallel inverter harmonic suppression method based on multi-harmonic observation and feed-forward compensation, and relates to the technical field of power electronics, and the method comprises the steps: monitoring each harmonic signal outputted by a Si IGBT inverter in a Si / SiC topological parallel inverter in real time, and determining the amplitude and phase of each harmonic signal; the Si / SiC topological parallel inverter is of a structure in which a Si IGBT (Insulated Gate Bipolar Translator) inverter and a SiC MOSFET (Metal-Oxide-Semiconductor Field Effect Transistor) inverter are connected in parallel Generating an adjusted current compensation signal based on a gain scheduling mechanism according to the amplitude and the phase; the adjusted current compensation signal is a current compensation signal which is equal in amplitude and opposite to a harmonic signal of the SiC MOSFET inverter; according to the invention, the harmonic suppression capability and the electric energy quality can be improved, and the method is suitable for a high-power electric power system and an application occasion with strict requirements on the electric energy quality.

Description

Technical Field

[0001] This application relates to the field of power electronics technology, and particularly to a harmonic suppression method for a Si / SiC topology parallel inverter based on multi-harmonic observation and feed-forward compensation. Background Art

[0002] With the transformation of the global energy structure and the rapid development of renewable energy, especially the widespread application of solar energy and wind energy, the operation of power systems faces more and more challenges. In particular, due to the intermittency and volatility of renewable energy, the requirements for power quality in power systems have become more stringent. As one of the common forms of power pollution in power systems, high-frequency harmonics not only affect the operation efficiency and safety of equipment, but may also lead to grid instability, equipment damage and even failures. Therefore, how to accurately suppress the harmonics in the inverter output without sacrificing system efficiency has become a key technical problem in modern power systems.

[0003] Currently, the application of inverters has been widely promoted in fields such as distributed energy systems, microgrids, and energy storage systems. Especially in the case of large-scale access, the harmonic problems of inverters are more prominent. Although the topological structures using wide-bandgap semiconductor materials such as silicon (Si) and silicon carbide (SiC) have become the mainstream solutions, and their parallel use can effectively improve the efficiency of the inverter and reduce switching losses, they still cannot completely solve the problem of high-frequency harmonic suppression. Si IGBT inverters have high efficiency under low-frequency operation, but their ability to suppress high-frequency harmonics is weak under high-frequency and dynamic load changes; while SiC MOSFET inverters show significant advantages in high-frequency operation, but their suppression effects on low-frequency and medium-frequency harmonics are relatively insufficient, and there are still significant challenges in the real-time performance and stability of harmonic compensation in a dynamic environment with load mutations. Therefore, although the parallel structure of Si IGBT and SiC MOSFET inverters has made breakthroughs in improving the overall performance of the system, their harmonic suppression capabilities under different load and frequency conditions still cannot meet the increasingly stringent requirements for power quality in high-power systems, and it is urgent to further optimize their harmonic suppression and dynamic compensation capabilities to meet the grid operation requirements after large-scale access of new energy. Summary of the Invention

[0004] The purpose of this application is to provide a harmonic suppression method for a Si / SiC topology parallel inverter based on multi-harmonic observation and feed-forward compensation, so as to solve the problem that the existing technology has poor harmonic suppression ability of the inverter output and cannot meet the increasingly stringent requirements for power quality in high-power systems.

[0005] To achieve the above purpose, the following solutions are provided in this application.

[0006] The present application provides a harmonic suppression method for a Si / SiC topology parallel inverter based on multi-harmonic observation and feed-forward compensation, including the following steps.

[0007] Monitor in real time the harmonic signals of each order output by the Si IGBT inverter in the Si / SiC topology parallel inverter, and determine the amplitude and phase of each harmonic signal; the Si / SiC topology parallel inverter is a parallel structure of a Si IGBT inverter and a SiC MOSFET inverter.

[0008] Based on the amplitude and the phase, generate an adjusted current compensation signal based on a gain scheduling mechanism; the adjusted current compensation signal is a current compensation signal with the same amplitude and opposite direction as the harmonic signal of the SiC MOSFET inverter.

[0009] Suppress the harmonic signals output by the SiC MOSFET inverter according to the adjusted current compensation signal.

[0010] According to the specific embodiments provided by the present application, the following technical effects are disclosed: by determining the amplitude and phase of the harmonic signals of each order output by the Si IGBT inverter, and based on the gain scheduling mechanism, an adjusted current compensation signal is generated, and the adjusted current compensation signal is a current compensation signal with the same amplitude and opposite direction as the harmonic signal of the SiC MOSFET inverter. This current compensation signal can accurately and in real time suppress the harmonic signals output by the SiC MOSFET inverter, improving the power quality; in addition, based on the gain scheduling mechanism, it can ensure that high-efficiency harmonic suppression performance can still be maintained under load mutation or overload conditions, and is applicable to high-power power systems and application scenarios with strict requirements for power quality, improving the resonance pollution problem of the inverter output and further improving the power quality. Description of the Drawings

[0011] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings required for use in the embodiments. Obviously, the drawings in the following description are only some embodiments of the present application. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0012] Figure 1 It is a schematic flowchart of a harmonic suppression method for a Si / SiC topology parallel inverter based on multi-harmonic observation and feed-forward compensation provided by an embodiment of the present application.

[0013] Figure 2 It is a block diagram of a harmonic suppression method for a Si / SiC topology parallel inverter based on multi-harmonic observation and feed-forward compensation provided by an embodiment of the present application.

[0014] Figure 3Schematic diagram of another harmonic suppression method for Si / SiC topology parallel inverters based on multi-harmonic observation and feed-forward compensation provided by an embodiment of this application. Detailed implementation manners

[0015] Next, the technical solutions in the embodiments of this application will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of this application. Obviously, the described embodiments are only a part of the embodiments of this application, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in this application without creative efforts shall fall within the protection scope of this application.

[0016] The following further elaborates on this application in conjunction with the accompanying drawings and specific implementation manners.

[0017] An embodiment of this application provides a harmonic suppression method for Si / SiC topology parallel inverters based on multi-harmonic observation and feed-forward compensation. This method is executed by a computer device, and specifically can be executed alone by a computer device such as a terminal or a server, or can be jointly executed by a terminal and a server. In the embodiment of this application, as Figure 1 - Figure 2 shown, where Figure 2 g1 represents the drive signal of inverter 1 (Si IGBT inverter), and g2 represents the drive signal of inverter 2 (SiC MOSFET inverter). This method includes the following steps.

[0018] S1: Real-time monitor the harmonic signals of each order output by the Si IGBT inverter in the Si / SiC topology parallel inverter, and determine the amplitude and phase of each harmonic signal; the Si / SiC topology parallel inverter is a parallel structure of a Si IGBT inverter and a SiC MOSFET inverter.

[0019] S2: Based on the amplitude and the phase, generate an adjusted current compensation signal based on a gain scheduling mechanism; the adjusted current compensation signal is a current compensation signal with the same amplitude and opposite direction to the harmonic signal of the SiC MOSFET inverter.

[0020] S3: Suppress the harmonic signals output by the SiC MOSFET inverter according to the adjusted current compensation signal.

[0021] In an exemplary embodiment, S1 specifically includes: Based on a multi-harmonic observation module, adopt an improved Kalman filtering algorithm to real-time monitor the harmonic signals of each order output by the Si IGBT inverter in the Si / SiC topology parallel inverter, and estimate the amplitude of each harmonic signal.

[0022] The frequency and phase of the grid signal are synchronized using an adaptive Phase-Locked Loop (PLL) algorithm, and the phases of the harmonic signals are estimated based on the frequency and phase of the grid.

[0023] In an exemplary embodiment, based on the multi-harmonic observation module, an improved Kalman filtering algorithm is used to monitor in real time the harmonic signals of each order output by the Si IGBT inverter in the Si / SiC topology parallel inverter, and estimate the amplitudes of the harmonic signals of each order, specifically including: using Estimate the amplitudes of the harmonic signals of each order; where is the estimated value of the amplitude of the k-th harmonic; is the estimated value of the amplitude of the (k - 1)-th harmonic; is the measurement matrix; is the Kalman gain, ; Prediction error covariance S Describes the reliability of the system state estimation, which reflects the estimation error of the system during prediction; S k is the prediction error covariance matrix at time k, representing the prediction error of the system state; S k-1 is the prediction error covariance matrix at time k - 1, representing the prediction error of the previous moment; F is the state transition matrix, describing the change of the system state from time k - 1 to time k; Q is the process noise covariance matrix, representing the noise in the system dynamic process, usually estimated from the system model and external environment changes. The measurement matrix H Describes how the system state is mapped to the measurement space, representing the linear relationship from the system state to the observed value. For each time k, the measurement matrix H is a constant matrix, that is, it represents the relationship from the state variables x k to the measurement variable z k ; z k is the measurement value at time k, that is, the measurement variable, representing the actual observed signal obtained from the sensor; x k The system state at time k, representing the state variables of the system; v k is the measurement noise, usually assumed to be Gaussian noise with zero mean. The measurement noise covariance R Describes the noise intensity in the measurement process, usually assumed to be a constant, which reflects the measurement error caused by sensor accuracy limitations or other external interferences; T is the transpose matrix.

[0024] In an exemplary embodiment, an adaptive phase-locked loop algorithm is used to synchronize the frequency and phase of the grid signal, and the phases of the harmonic signals are estimated according to the frequency and phase of the grid, including: using to estimate the phases of the harmonic signals; where is the grid phase at time t; is the reference frequency; is the gain parameter; is the phase error signal, representing the phase difference between the grid voltage signal and the reference voltage signal; is the grid input voltage signal, which includes amplitude and phase signals, is the reference voltage signal; arg() is a complex argument extraction function for obtaining the phase angle of a complex number.

[0025] In an exemplary embodiment, S2 specifically includes: based on a feedforward compensation module, generating a current compensation signal that is equal in amplitude and opposite in phase to the harmonic signals of the Si IGBT inverter according to the amplitude and phase.

[0026] Based on a gain scheduling mechanism, dynamically adjust the gain of the current compensation signal according to the change in load power.

[0027] Generate an adjusted current compensation signal according to the adjusted gain.

[0028] In an exemplary embodiment, based on a feedforward compensation module, generating a current compensation signal that is equal in amplitude and opposite in phase to the harmonic signals of the Si IGBT inverter according to the amplitude and phase specifically includes: using to generate a current compensation signal that is equal in amplitude and opposite in phase to the harmonic signals of the Si IGBT inverter; where is the current compensation signal that is equal in amplitude and opposite in phase to the harmonic signals of the Si IGBT inverter; is the n th harmonic current amplitude; is the n th harmonic signal phase; is the reference frequency; N is the total number of harmonic signals.

[0029] In an exemplary embodiment, before dynamically adjusting the gain of the current compensation signal based on a gain scheduling mechanism according to the change in load power, it further includes: during the gain adjustment process, real-time monitoring of the change in load power, and determining that the change in load power is within the change range; the change in load power within the change range can enable the current compensation signal to still work effectively under load fluctuations or mutations.

[0030] In an exemplary embodiment, based on a gain scheduling mechanism, the gain of the current compensation signal is dynamically adjusted according to the change in load power, specifically including: using to adjust the gain of the current compensation signal; where G ( t ) is the adjusted gain at time t; G 0 is the initial gain; α is the adjustment coefficient; Δ P is the change in load power.

[0031] In an exemplary embodiment, according to the adjusted gain, an adjusted current compensation signal is generated, specifically including: using to generate the adjusted current compensation signal; where is the adjusted current compensation signal.

[0032] In an exemplary embodiment, before S1, it further includes: applying a driving signal to the Si IGBT inverter and the SiC MOSFET inverter respectively. As Figure 2 shown, the driving signal g1 is generated through the voltage control loop and the current control loop in the control link of inverter 1, and the driving signal g2 is generated through the control link of inverter 2, where the control link of inverter 2 includes a multi-harmonic observation module, a feed-forward compensation module, a gain scheduling mechanism, and a current control loop.

[0033] This application is based on the parallel structure of the Si IGBT inverter and the SiC MOSFET inverter, combines multi-harmonic observation technology and feed-forward compensation method, accurately and real-time suppresses multiple harmonics in the inverter output, and improves the power quality.

[0034] As Figure 2 shown, the harmonic suppression method shown in this application can be applied to the stable control of a multi-modal collaborative grid-forming power system. The multi-harmonic observation module uses an improved Kalman filter algorithm and an adaptive phase-locked loop algorithm to real-time obtain the amplitude and phase of each harmonic, and provides a feedback signal for the feed-forward compensation module. The feed-forward compensation module generates a compensation signal equal in amplitude and opposite in direction to the harmonic according to the harmonic amplitude and phase, significantly improving the harmonic suppression effect. The gain scheduling mechanism dynamically adjusts the compensation signal gain according to the load change, ensuring that the system can still maintain high-efficiency harmonic suppression performance under load mutation or overload conditions.

[0035] This application is applicable to high-power power systems and application scenarios with strict requirements for power quality, can significantly improve the harmonic pollution of the inverter output, and improve the power quality.

[0036] In an exemplary embodiment, the harmonic suppression method of the Si / SiC topology parallel inverter based on multi-harmonic observation and feed-forward compensation provided by this application is as Figure 3as shown

[0037] Step 1: First, the multi - harmonic observation module monitors the harmonic signals in the power supply system in real - time. This module uses an improved Kalman filtering algorithm to dynamically estimate the amplitude and phase of each harmonic signal in the power supply system. The Kalman filter optimizes the prediction error of the harmonic signal and updates the amplitude and phase estimates of each harmonic signal in real - time, ensuring that the system can accurately track the changes in harmonics.

[0038] Step 2: Next, the adaptive phase - locked loop algorithm synchronizes the frequency and phase of the power grid. The phase - locked loop algorithm calculates the phase difference between the power grid signal and the reference signal and adjusts the frequency to keep the power grid signal synchronized with the reference signal. This process ensures the accuracy of the multi - harmonic observation module, enabling precise phase information to be obtained for subsequent harmonic signal estimation.

[0039] Step 3: After obtaining the accurate harmonic amplitudes and phases, the feed - forward compensation module generates current compensation signals that are equal in amplitude and opposite in phase to the harmonics based on this information. The compensation signals are generated by calculating the reverse of the amplitude and phase of each harmonic signal. These reverse current signals are used to suppress the harmonics in the inverter output, ensuring that the output power quality of the system meets the standard requirements.

[0040] Step 4: To cope with load changes and overload conditions, the gain - scheduling mechanism adjusts the gain of the compensation signal in real - time according to the load power change. When the system load changes suddenly, the gain - scheduling mechanism can ensure the efficient operation of the compensation signal under different load conditions by adjusting the gain of the compensation signal. This adjustment process ensures that the system can still maintain high - efficiency harmonic suppression performance in a changing load environment.

[0041] Step 5: Finally, the reverse compensation current signal optimized by the gain - scheduling is output to the system to adjust the output current of the inverter in real - time, thereby effectively suppressing the harmonic pollution in the system. The entire system continuously adjusts according to real - time load changes and harmonic characteristics to ensure the stability of the inverter output current and the improvement of power quality. This process can maintain the efficiency and stability of the system in a complex and dynamic load environment.

[0042] This application is based on the parallel structure of a Si IGBT inverter and a SiC MOSFET inverter, making use of the complementary advantages of the two devices in different frequency bands to achieve precise observation and real - time compensation of multiple harmonics in the inverter output, significantly improving the overall performance and stability of the inverter system.

[0043] First, this application introduces a multi-harmonic observation module based on an improved Kalman filter algorithm, which can monitor in real time and accurately estimate the harmonic amplitudes and phases in the power system. Through this module, the system can dynamically identify each harmonic in the inverter output and provide real-time feedback to the subsequent compensation module. The Kalman filter algorithm has self-adaptability and can optimize the estimated value in the presence of noise or interference in the harmonic signal, thus ensuring the accuracy and stability of harmonic observation. In addition, by combining the adaptive phase-locked loop algorithm, this application can synchronize the frequency and phase of the power grid, further improving the accuracy of the multi-harmonic observation module and ensuring the accurate tracking of harmonic signals under complex dynamic operating conditions.

[0044] Secondly, the feedforward compensation module of this application can generate current compensation signals that are equal in amplitude and opposite in direction to the harmonics based on the obtained harmonic amplitude and phase information. These compensation signals are output through the inverter, thus effectively canceling the impact of harmonics on the power system. Feedforward compensation ensures that the amplitude of harmonics is reduced to a minimum by precisely adjusting the amplitude and phase of the compensation signals, achieving dual suppression of high-frequency and low-frequency harmonics. Different from traditional passive filtering techniques, the feedforward compensation method of this application can respond to system changes in real time without additional filtering components, thus improving the dynamic response speed and efficiency of the system.

[0045] To ensure that the system can still maintain high-efficiency harmonic suppression performance under load mutations or overload conditions, this application also introduces a gain scheduling mechanism. The gain scheduling mechanism dynamically adjusts the gain of the compensation signal to adapt to changes in load power. The adjustment of the gain is based on the real-time monitored change in load power to ensure that the compensation signal can still work effectively under load fluctuations or mutations. Through this mechanism, this application can ensure that stable harmonic suppression effects can still be maintained under frequent changes in grid conditions or loads.

[0046] The Si / SiC topology parallel inverter harmonic suppression method based on multi-harmonic observation and feedforward compensation provided by this application has the following advantages: on the one hand, through the parallel structure of Si IGBT and SiC MOSFET, the advantages of both in different frequency bands are fully utilized to improve the overall power conversion efficiency of the system; on the other hand, through the combination of the Kalman filter and the adaptive phase-locked loop algorithm, high-precision and high real-time harmonic observation are ensured; furthermore, the feedforward compensation module can achieve precise harmonic suppression, avoiding the problems of poor frequency adaptability and compensation lag faced by traditional filters; finally, the introduction of the gain scheduling mechanism ensures the efficient operation of the system under load fluctuations or mutations. These innovations enable this application to operate stably and effectively improve the power quality under variable and complex working conditions, and have broad application prospects, especially suitable for harmonic suppression tasks in high-power inverter systems and new energy power generation systems.

[0047] The technical features of the above embodiments can be combined arbitrarily. For the sake of brevity of description, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered that the scope recorded in this specification.

[0048] Specific examples are used in this article to elaborate on the principles and implementation manners of the present application. The description of the above embodiments is only used to help understand the method and its core idea of the present application; at the same time, for those of ordinary skill in the art, according to the idea of the present application, there will be changes in the specific implementation manners and application scopes. In summary, the content of this specification should not be construed as a limitation on the present application.

Claims

1. A harmonic suppression method for Si / SiC topology parallel inverters based on multi-harmonic observation and feed-forward compensation, characterized in that Including: Real-time monitor the harmonic signals of each order output by the Si IGBT inverter in the Si / SiC topology parallel inverter, and determine the amplitude and phase of each harmonic signal; The Si / SiC topology parallel inverter is a parallel structure of a Si IGBT inverter and a SiC MOSFET inverter; Based on the amplitude and the phase, generate an adjusted current compensation signal based on the gain scheduling mechanism; the adjusted current compensation signal is a current compensation signal with the same amplitude and opposite direction to the harmonic signal of the SiC MOSFET inverter; Suppress the harmonic signals output by the SiC MOSFET inverter according to the adjusted current compensation signal.

2. The harmonic suppression method for Si / SiC topology parallel inverters based on multi-harmonic observation and feed-forward compensation according to claim 1, wherein, Real-time monitor the harmonic signals of each order output by the Si IGBT inverter in the Si / SiC topology parallel inverter, and determine the amplitude and phase of each harmonic signal, specifically including: Based on the multi-harmonic observation module, adopt an improved Kalman filtering algorithm to real-time monitor the harmonic signals of each order output by the Si IGBT inverter in the Si / SiC topology parallel inverter, and estimate the amplitude of each harmonic signal; Adopt an adaptive phase-locked loop algorithm to synchronize the frequency and phase of the grid signal, and estimate the phase of each harmonic signal according to the frequency and phase of the grid.

3. The harmonic suppression method of the Si / SiC topology parallel inverter based on multi-harmonic observation and feed-forward compensation according to claim 2, wherein, Based on the multi-harmonic observation module, adopt an improved Kalman filtering algorithm to real-time monitor the harmonic signals of each order output by the Si IGBT inverter in the Si / SiC topology parallel inverter, and estimate the amplitude of each harmonic signal, specifically including: Utilize Estimate the amplitudes of each harmonic signal; among them, is the estimated value of the amplitude of the k-th harmonic; is the estimated value of the amplitude of the (k - 1)-th harmonic; is the Kalman gain; is the measurement variable; is the measurement matrix.

4. The harmonic suppression method for the Si / SiC topology parallel inverter based on multi-harmonic observation and feedforward compensation according to claim 2, wherein, Adopt an adaptive phase-locked loop algorithm to synchronize the frequency and phase of the grid signal, and estimate the phase of each harmonic signal according to the frequency and phase of the grid, including: Utilize Estimate the phases of the harmonic signals; where is the grid phase at time t; is the reference frequency; is the gain parameter; is the phase error signal at time t, representing the phase difference between the grid voltage signal and the reference voltage signal; is the grid input voltage signal, which includes an amplitude and a phase signal, is the reference voltage signal; arg() is the complex argument extraction function.

5. The harmonic suppression method for the Si / SiC topology parallel inverter based on multi-harmonic observation and feedforward compensation according to claim 1, characterized in that, Based on the amplitude and the phase, generate an adjusted current compensation signal based on the gain scheduling mechanism, specifically including: Based on the feed-forward compensation module, generate a current compensation signal with the same amplitude and opposite direction to the harmonic signals of each order of the Si IGBT inverter according to the amplitude and phase; Based on the gain scheduling mechanism, dynamically adjust the gain of the current compensation signal according to the change in load power; Generate an adjusted current compensation signal according to the adjusted gain.

6. The harmonic suppression method of the Si / SiC topology parallel inverter based on multi-harmonic observation and feed-forward compensation according to claim 5, characterized in that, Based on the feed-forward compensation module, generate a current compensation signal with the same amplitude and opposite direction to the harmonic signals of each order of the Si IGBT inverter according to the amplitude and phase, specifically including: Utilize to generate a current compensation signal that is equal in amplitude and opposite in direction to each harmonic signal of the Si IGBT inverter; where is the current compensation signal that is equal in amplitude and opposite in direction to each harmonic signal of the Si IGBT inverter at time t; is the current amplitude of the n th harmonic; is the phase of the n th harmonic signal; is the reference frequency; N is the total number of harmonic signals.

7. The harmonic suppression method for the Si / SiC topology parallel inverter based on multi-harmonic observation and feedforward compensation according to claim 5, characterized in that, Before dynamically adjusting the gain of the current compensation signal based on the gain scheduling mechanism according to the change in load power, it also includes: During the gain adjustment process, real-time monitor the change in load power, and determine that the change in load power is within the change range; the change in load power within the change range can enable the current compensation signal to still work effectively under load fluctuations or mutations.

8. The harmonic suppression method for a Si / SiC topology parallel inverter based on multi-harmonic observation and feed-forward compensation according to claim 6, characterized in that, Based on the gain scheduling mechanism, dynamically adjust the gain of the current compensation signal according to the change in load power, specifically including: Utilize Adjust the gain of the current compensation signal; wherein, G ( t ) is the adjusted gain at time t; G 0 is the initial gain; α is the adjustment coefficient; Δ P is the change amount of the load power.

9. The harmonic suppression method for the Si / SiC topology parallel inverter based on multi-harmonic observation and feed-forward compensation according to claim 8, wherein, Generate an adjusted current compensation signal according to the adjusted gain, specifically including: Utilize to generate an adjusted current compensation signal; wherein, is the adjusted current compensation signal.

10. The harmonic suppression method for the Si / SiC topology parallel inverter based on multi-harmonic observation and feedforward compensation according to claim 1, wherein, Before real-time monitoring the harmonic signals of each order output by the Si IGBT inverter in the Si / SiC topology parallel inverter and determining the amplitude and phase of each harmonic signal, it also includes: Apply a driving signal to the Si IGBT inverter and the SiC MOSFET inverter respectively.

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