Grid-connected inverter power and current coordination control method under harmonic power grid and related device

Abstract

The invention discloses a grid-connected inverter power and current coordination control method under a harmonic power grid and a related device, and relates to the technical field of renewable energy power generation, and the method comprises the steps: obtaining a two-phase power grid AC voltage based on a three-phase power grid AC voltage; calculating a reference current under a direct power control strategy based on the active power reference value, the reactive power reference value and the two-phase power grid AC voltage; harmonic waves in the reference current under the direct power control strategy are filtered out, and a fundamental component and a harmonic component are obtained; based on a preset adjustment coefficient, the fundamental component and the harmonic component, obtaining a reference current with an adjustable harmonic content; performing zero static error control on the reference current with the adjustable harmonic content to obtain a modulation voltage; and performing sine pulse width modulation on the modulation voltage to obtain a grid-connected current. According to the invention, coordinated control of power constancy and current balance of the grid-connected inverter can be realized.

Description

Technical Field

[0001] The present application relates to the technical field of renewable energy power generation, and in particular to a method and related device for coordinated control of power and current of a grid-connected inverter under a harmonic power grid. Background Art

[0002] Against the backdrop of the global push for "dual carbon" goals, renewable energy generation technologies, represented by photovoltaic and wind power, are rapidly developing and their share in the power system continues to increase. As key equipment for integrating renewable energy into the grid, the large-scale deployment of grid-connected inverters (GCIs) places higher demands on grid stability and power quality. However, due to issues such as background harmonic distortion in the public grid, GCIs are susceptible to interference during the grid connection process, resulting in output current distortion and power fluctuations, which in turn affects grid power quality and even threatens the safe and stable operation of the grid.

[0003] Currently, control methods for GCI mainly focus on optimizing a single objective, such as achieving output current balance or maintaining constant active and reactive power, but lack coordinated control strategies between different control objectives. In addition, existing methods usually rely on a phase-locked loop (PLL) to obtain the voltage phase at the grid connection point to achieve grid synchronization, and require positive and negative sequence separation of asymmetric power. These links not only increase the control complexity of the system, but also reduce the dynamic response speed, making it difficult to meet the requirements of renewable energy grid-connected inverters for high-quality output current and power stability. Therefore, there is an urgent need for a new control method that does not require a phase-locked loop and positive and negative sequence separation links to achieve coordinated control of GCI power constancy and current balance, thereby improving the reliability of GCI, enhancing the grid's ability to accept renewable energy, and optimizing the dynamic performance of the power system. Summary of the Invention

[0004] The purpose of this application is to provide a method and related device for coordinated control of power and current of grid-connected inverters under harmonic power grids, which can realize coordinated control of GCI power constancy and current balance, while eliminating the need for a phase-locked loop and positive-negative sequence separation links, thereby improving the reliability of GCI.

[0005] To achieve the above objectives, this application provides the following solutions:

[0006] In a first aspect, the present application provides a method for coordinated control of power and current of a grid-connected inverter in a harmonic power grid, comprising:

[0007] Based on the obtained three-phase grid AC voltage u gabc , get the three-phase grid AC voltage u gabc Two-phase AC grid voltage u in the αβ stationary coordinate system gαβ ;

[0008] Based on the preset active power reference value P * and reactive power reference value Q * And the two-phase grid AC voltage u gαβ , calculate the reference current i under the direct power control strategy hαβ * ;

[0009] Based on the fast delay signal destructive filtering theory, the reference current i under the direct power control strategy is hαβ * The harmonics in the filter are processed to obtain the fundamental component i oαβ * and harmonic components i hαβ ;

[0010] Based on the preset adjustment coefficient λ, the fundamental wave component i oαβ * and the harmonic component i hαβ , get the reference current i with adjustable harmonic content αβ * ;

[0011] Based on the quasi-proportional resonant controller, the reference current i αβ * Perform zero-static-error control to obtain the modulation voltage u αβ * ;

[0012] The modulation voltage u αβ * Perform sinusoidal pulse width modulation to obtain the grid-connected current i gabc The grid-connected current i gabc Meet the requirements of constant power and current balance.

[0013] Optionally, based on a preset active power reference value P * and reactive power reference value Q * And the two-phase grid AC voltage u gαβ , calculate the reference current i under the direct power control strategy hαβ * , specifically:

[0014]

[0015] in, is the reference current i under the direct power control strategy hαβ * a first current component of; is the reference current i under the direct power control strategy hαβ *The second current component of P * is the active power reference value; Q * is the reactive power reference value; u gα is the two-phase AC grid voltage u gαβ The first voltage component of u gβ is the two-phase AC grid voltage u gαβ The second voltage component of

[0016] Optionally, based on the fast delay signal destructive filtering theory, the reference current i under the direct power control strategy is hαβ * The harmonics in the filter are processed to obtain the fundamental component i oαβ * and harmonic components i hαβ , specifically including:

[0017] Based on the fast delay signal cancellation filtering theory, the reference current i under the direct power control strategy is filtered out. hαβ * The 5th harmonic and 7th harmonic, as well as the 3rd harmonic and 9th harmonic, get the fundamental component i oαβ * ;

[0018] The reference current i under the direct power control strategy hαβ * and the fundamental component i oαβ * Perform difference calculation to obtain harmonic component i hαβ .

[0019] Optionally, the filter expressions for the 5th harmonic and the 7th harmonic are:

[0020]

[0021] in, is the fundamental signal after filtering out the 5th and 7th harmonics; T is the fundamental period; u(t) is the AC voltage at the current time t; is the lag of the current moment t AC voltage; is the lag of the current moment t AC voltage;

[0022] The filter expressions for the 3rd and 9th harmonics are:

[0023]

[0024] Among them, FDSC(0,12) is the fundamental signal after filtering out the 3rd harmonic and 9th harmonic.

[0025] Optionally, based on a quasi-proportional resonant controller, the reference current i αβ * Perform zero-static-error control to obtain the modulation voltage u αβ * , specifically:

[0026]

[0027] Among them, u αβ * is the modulation voltage; i αβ * is the reference current of adjustable harmonic content; G QPR (s) is the transfer function of the quasi-proportional resonant controller; k p is the proportional gain; k r is the resonant gain; ω c is the cutoff angular frequency; s is the Laplace operator; ω is the fundamental angular frequency; h is the harmonic number; i αβ is the actual output current.

[0028] Optionally, the method for coordinated control of power and current of a grid-connected inverter in a harmonic power grid further includes:

[0029] Based on the fast Fourier transform, the reference current i under the direct power control strategy is hαβ * Decompose and get the fundamental component i oαβ * and harmonic components i hαβ superimposed form.

[0030] In a second aspect, the present application provides a power and current coordinated control device for a grid-connected inverter in a harmonic power grid, comprising:

[0031] Direct power control module for:

[0032] Based on the obtained three-phase grid AC voltage u gabc , get the three-phase grid AC voltage u gabc Two-phase AC grid voltage u in the αβ stationary coordinate system gαβ ;

[0033] Based on the preset active power reference value P * and reactive power reference value Q * And the two-phase grid AC voltage u gαβ , calculate the reference current i under the direct power control strategy hαβ * ;

[0034] The harmonic extraction module is used to extract the reference current i under the direct power control strategy based on the fast delay signal cancellation filtering theory. hαβ * The harmonics in the filter are processed to obtain the fundamental component i oαβ * and harmonic components i hαβ ;

[0035] The power-current coordinated control module is used to adjust the power-current coordinated control module based on the preset adjustment coefficient λ and the fundamental component i oαβ * and the harmonic component i hαβ , get the reference current i with adjustable harmonic content αβ * ;

[0036] The current outer loop control module is used to adjust the reference current i of the adjustable harmonic content based on the quasi-proportional resonant controller. αβ * Perform zero-static-error control to obtain the modulation voltage u αβ * ;

[0037] Sine pulse width modulation module, used to modulate the voltage u αβ * Perform sinusoidal pulse width modulation to obtain the grid-connected current i gabc The grid-connected current i gabc Meet the requirements of constant power and current balance.

[0038] In a third aspect, the present application provides a computer device comprising: a memory, a processor, and a computer program stored in the memory and capable of running on the processor, wherein the processor executes the computer program to implement any of the above-mentioned methods for coordinated control of power and current of a grid-connected inverter under a harmonic power grid.

[0039] In a fourth aspect, the present application provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements any of the above-mentioned methods for coordinated control of power and current of a grid-connected inverter under a harmonic power grid.

[0040] In a fifth aspect, the present application provides a computer program product, including a computer program, which, when executed by a processor, implements any of the above-mentioned methods for coordinated control of power and current of a grid-connected inverter under a harmonic power grid.

[0041] According to the specific embodiments provided in this application, this application discloses the following technical effects:

[0042] The present application provides a method and related device for coordinated control of power and current of a grid-connected inverter under a harmonic power grid, which directly sets the active power reference value P * and reactive power reference value Q * This effectively achieves power regulation and current balancing for the inverter, enabling the grid-connected inverter to maintain stable output power in harmonically polluted grids. By combining the adjustment coefficient λ, a reference current iαβ* with adjustable harmonic content is obtained, allowing the inverter to dynamically adjust the output current waveform based on actual grid conditions. This achieves precise control of the current waveform and effectively eliminates harmonic interference. Furthermore, the elimination of the phase-locked loop and positive-negative sequence separation control steps reduces latency and improves the stability of the grid-connected inverter. Furthermore, the use of a quasi-proportional resonant controller for zero-static-error control helps reduce steady-state errors, ensuring the inverter's power tracking performance during long-term operation and further improving the inverter's response speed and stability. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0044] Figure 1 This is an application environment diagram of a method for coordinated control of power and current of a grid-connected inverter under a harmonic power grid in Example 1 of the present application;

[0045] Figure 2 A flow chart of a method for coordinated control of power and current of a grid-connected inverter in a harmonic power grid provided in Example 1 of the present application;

[0046] Figure 3 A schematic diagram of the functional modules of a power and current coordinated control device for a grid-connected inverter in a harmonic power grid provided in Example 2 of the present application;

[0047] Figure 4 Schematic diagram of the power-current coordinated control module provided in Example 2 of the present application;

[0048] Figure 5a Schematic diagram of the GCI reference current before adding the harmonic extraction module provided in Example 2 of the present application;

[0049] Figure 5b This is the spectrum diagram corresponding to the GCI reference current before adding the harmonic extraction module provided in Example 2 of the present application;

[0050] Figure 6aA schematic diagram of the GCI reference current after adding the harmonic extraction module provided in Example 2 of the present application;

[0051] Figure 6b This is the spectrum diagram corresponding to the GCI reference current before adding the harmonic extraction module provided in Example 2 of the present application;

[0052] Figure 7 A schematic diagram of simulation results of the coordinated control of current balance and constant power provided in Example 2 of the present application;

[0053] Figure 8 A schematic diagram of the structure of a computer device provided in one embodiment of the present application. DETAILED DESCRIPTION

[0054] The following will be combined with the drawings in the embodiments of this application to clearly and completely describe the technical solutions in the embodiments of this application. Obviously, the embodiments described are only part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0055] In order to make the above-mentioned purposes, features and advantages of the present application more obvious and easy to understand, the present application is further described in detail below with reference to the accompanying drawings and specific implementation methods.

[0056] Example 1

[0057] The method for coordinated control of power and current of a grid-connected inverter under a harmonic power grid provided in the embodiment of the present application can be applied to Figure 1 In the application environment shown. Among them, the terminal 102 communicates with the server 104 through the network. The data storage system can store data that the server 104 needs to process. The data storage system can be set up separately, integrated on the server 104, or placed on the cloud or other servers. The terminal 102 can send the three-phase grid AC voltage to the server 104. The server 104 obtains the two-phase grid AC voltage based on the three-phase grid AC voltage; calculates the reference current under the direct power control strategy based on the active power reference value and the reactive power reference value and the two-phase grid AC voltage; filters the harmonics in the reference current under the direct power control strategy to obtain the fundamental component and the harmonic component; obtains the reference current with adjustable harmonic content based on the preset adjustment coefficient, the fundamental component and the harmonic component; performs zero-static error control on the reference current with adjustable harmonic content to obtain the modulation voltage; and performs sinusoidal pulse width modulation on the modulation voltage to obtain the grid-connected current. The server 104 can feed back the obtained grid-connected current to the terminal 102.

[0058] In an exemplary embodiment, Figure 2As shown, a method for coordinated control of power and current of a grid-connected inverter under a harmonic power grid is provided. The method is executed by a computer device, specifically a computer device such as a terminal or a server, or a terminal and a server. In the embodiment of the present application, the method is applied to Figure 1 The server 104 in the example is used as an example to illustrate the process, including the following steps 201 to 206.

[0059] Step 201: Based on the acquired three-phase grid AC voltage u gabc , get the three-phase grid AC voltage u gabc Two-phase AC grid voltage u in the αβ stationary coordinate system gαβ .

[0060] Step 202: Based on the preset active power reference value P * and reactive power reference value Q * And the two-phase AC grid voltage u gαβ , calculate the reference current i under the direct power control strategy hαβ * .

[0061] Step 203: Based on the Fast Delayed Signal Cancellation (FDSC) filtering theory, the reference current i under the direct power control strategy is hαβ * The harmonics in the filter are processed to obtain the fundamental component i oαβ * and harmonic components i hαβ .

[0062] Step 204: Based on the preset adjustment coefficient λ and the fundamental component i oαβ * and harmonic components i hαβ , get the reference current i with adjustable harmonic content αβ * .

[0063] Step 205: Based on the quasi-proportional resonant controller, the reference current i αβ * Perform zero-static-error control to obtain the modulation voltage u αβ * .

[0064] Step 206: Modulate the voltage u αβ * Perform sinusoidal pulse width modulation to obtain the grid-connected current i gabc ; Grid current i gabc Meet the requirements of constant power and current balance.

[0065] Implementation of the above steps 201 to 206, the present application directly sets the active power reference value P * and reactive power reference value Q * This effectively achieves power regulation and current balancing for the inverter, enabling the grid-connected inverter to maintain stable output power in harmonically polluted grids. By combining the adjustment coefficient λ, a reference current iαβ* with adjustable harmonic content is obtained, allowing the inverter to dynamically adjust the output current waveform based on actual grid conditions. This achieves precise control of the current waveform and effectively eliminates harmonic interference. Furthermore, the elimination of the phase-locked loop and positive-negative sequence separation control steps reduces latency and improves the stability of the grid-connected inverter. Furthermore, the use of a quasi-proportional resonant controller for zero-static-error control helps reduce steady-state errors, ensuring the inverter's power tracking performance during long-term operation and further improving the inverter's response speed and stability.

[0066] In addition, the power and current coordinated control method of the grid-connected inverter under the harmonic power grid of the present application further includes: based on the fast Fourier transform, the reference current i under the direct power control strategy is hαβ * Decompose and get the fundamental component i oαβ * and harmonic components i hαβ superimposed form.

[0067] Furthermore, in step 202, based on the preset active power reference value P * and reactive power reference value Q * And the two-phase AC grid voltage u gαβ , calculate the reference current i under the direct power control strategy hαβ * , specifically:

[0068]

[0069] in, is the reference current i under the direct power control strategy hαβ * a first current component of; is the reference current i under the direct power control strategy hαβ * The second current component of P * is the active power reference value; Q * is the reactive power reference value; u gα is the two-phase AC grid voltage u gαβ The first voltage component of u gβ is the two-phase AC grid voltage u gαβ The second voltage component of

[0070] Furthermore, in step 203, based on the fast delay signal destructive filtering theory, the reference current i under the direct power control strategy is hαβ * The harmonics in the filter are processed to obtain the fundamental component i oαβ * and harmonic components i hαβ , specifically including:

[0071] Step 2031: Based on the fast delay signal cancellation filtering theory, filter out the reference current i under the direct power control strategy. hαβ * The 5th harmonic and 7th harmonic, as well as the 3rd harmonic and 9th harmonic, get the fundamental component i oαβ * ; Specifically, the filter expressions for the 5th harmonic and the 7th harmonic are:

[0072]

[0073] in, is the fundamental signal after filtering out the 5th and 7th harmonics; T is the fundamental period; u(t) is the AC voltage at the current time t; is the lag of the current moment t AC voltage; is the lag of the current moment t AC voltage.

[0074] The filter expressions for the 3rd and 9th harmonics are:

[0075]

[0076] Among them, FDSC(0,12) is the fundamental signal after filtering out the 3rd harmonic and 9th harmonic.

[0077] Step 2032: the reference current i under the direct power control strategy is hαβ * and fundamental component i oαβ * Perform difference calculation to obtain harmonic component i hαβ .

[0078] Furthermore, in step 205, based on the quasi-proportional resonant controller, the reference current i of the adjustable harmonic content is αβ * Perform zero-static-error control to obtain the modulation voltage u αβ * , specifically:

[0079]

[0080] Among them, uαβ * is the modulation voltage; i αβ * is the reference current of adjustable harmonic content; G QPR (s) is the transfer function of the quasi-proportional resonant controller; k p is the proportional gain; k r is the resonant gain; ω c is the cutoff angular frequency; s is the Laplace operator; ω is the fundamental angular frequency; h is the harmonic number; i αβ is the actual output current.

[0081] Example 2

[0082] Based on the same inventive concept, embodiments of the present application also provide a coordinated control device for implementing the aforementioned method for coordinated control of power and current of a grid-connected inverter in a harmonic power grid. The solution provided by this device is similar to the solution described in the aforementioned method. Therefore, the specific limitations in one or more embodiments of the coordinated control device provided below can be found in the above-mentioned limitations on the coordinated control method and will not be further elaborated here.

[0083] In an exemplary embodiment, Figure 3 As shown, a power and current coordinated control device for a grid-connected inverter under a harmonic power grid is provided, comprising:

[0084] Direct power control module for:

[0085] Based on the obtained three-phase grid AC voltage u gabc , get the three-phase grid AC voltage u gabc Two-phase AC grid voltage u in the αβ stationary coordinate system gαβ .

[0086] Based on the preset active power reference value P * and reactive power reference value Q * And the two-phase AC grid voltage u gαβ , calculate the reference current i under the direct power control strategy hαβ * The specific method is: According to the instantaneous power theory, the reference current i under the direct power control strategy is obtained hαβ * expression:

[0087]

[0088] in, is the reference current i under the direct power control strategy hαβ * a first current component of; is the reference current i under the direct power control strategy hαβ * The second current component of P * is the active power reference value; Q * is the reactive power reference value; u gα is the two-phase AC grid voltage u gαβ The first voltage component of u gβ is the two-phase AC grid voltage u gαβ The second voltage component of

[0089] Harmonic interaction mechanism analysis module, used for: based on the three-phase grid AC voltage u gabc Expanded in the αβ stationary coordinate system, the reference current i under the direct power control strategy is hαβ * Perform harmonic component analysis and convert the reference current i under the direct power control strategy into hαβ * Expanded into fundamental component i oαβ * and harmonic components i hαβ The specific method is: the actual AC voltage of the power grid mainly has -5 harmonics and +7 harmonics, etc., then the three-phase AC voltage u gabc In the αβ stationary coordinate system, it can be expressed as:

[0090] u gαβ =u gαβ+ +u gαβ5- +u gαβ7+ =U g+ e jωt +U g5- e -j5ωt +U g7+ e j7ωt ;

[0091] Among them, u gαβ+ is the fundamental component of the two-phase AC grid voltage; u gαβ5- is the -5th harmonic component of the two-phase AC grid voltage; u gαβ7+ is the +7th harmonic component of the two-phase AC grid voltage; U g+ 、U g5- 、U g7+ They are the fundamental amplitude, -5th harmonic amplitude and +7th harmonic amplitude of the AC voltage of the power grid respectively; is the fundamental angular frequency.

[0092] The background harmonics such as -5 and +7 in the AC voltage of the power grid cause the GCI reference current to contain the corresponding -5 harmonics, +7 harmonics, etc., while the reference current i under the direct power control strategy hαβ *The denominator of the expression can be expanded into a cross term containing the fundamental wave and harmonics, generating the 2nd harmonic, 4th harmonic and 6th harmonic, which then interact with the -5th harmonic and +7th harmonic in the numerator through division operations to generate new harmonic frequencies. For example, the fundamental wave interacts with the 4th harmonic in the denominator to generate the 3rd harmonic and the 5th harmonic, and the 5th harmonic interacts with the 4th harmonic in the denominator to generate the fundamental wave and the 9th harmonic, etc.

[0093] The reference current i under direct power control strategy hαβ * The expression is used as the GCI output current reference instruction for tracking control, so that the GCI output power tracks the given values ​​P* and Q*, and there is no 2-fold frequency fluctuation. However, the reference current i under the direct power control strategy is hαβ * The expression contains the third harmonic, fifth harmonic, seventh harmonic and ninth harmonic, which lead to serious output current distortion. Therefore, the reference current i obtained by the direct power control strategy is hαβ * It can be expressed as:

[0094]

[0095] in, is the reference current i under the direct power control strategy hαβ * a first current component of; is the reference current i under the direct power control strategy hαβ * a second current component of is the fundamental component of the first current component; i hα is the harmonic component of the first current component; is the fundamental component of the second current component; i hβ is the harmonic component of the second current component.

[0096] The harmonic extraction module is used to extract the reference current i under the direct power control strategy based on the fast delayed signal cancellation (FDSC) filtering theory. hαβ * The 5th harmonic and 7th harmonic, as well as the 3rd harmonic and 9th harmonic are filtered out to obtain the fundamental component i oαβ * , and the reference current i under the direct power control strategy hαβ * and fundamental component i oαβ * Perform difference processing to obtain harmonic component i hαβ The specific method is: the reference current i under the direct power control strategy is hαβ *The 5th harmonic and 7th harmonic are unified into the form of 12k±5 (k=0, 1, 2, ...). According to the FDSC filtering theory, the delay coefficient n=12 is set and the filtering parameters are calculated. Thus, the fifth and seventh harmonics are filtered out. expression:

[0097]

[0098] in, is the fundamental signal after filtering out the 5th and 7th harmonics; T is the fundamental period; u(t) is the AC voltage at the current time t; is the lag of the current moment t AC voltage; is the lag of the current moment t AC voltage.

[0099] Similarly, the expression of FDSC(0,12) for filtering out the 3rd and 9th harmonics can be obtained:

[0100]

[0101] Among them, FDSC(0,12) is the fundamental signal after filtering out the 3rd harmonic and 9th harmonic.

[0102] Will and two FDSC cascades of FDSC (0,12) to filter the reference current i under the direct power control strategy hαβ * The 3rd harmonic, 5th harmonic, 7th harmonic and 9th harmonic etc.

[0103] The reference current is extracted by taking the difference between the reference current before and after filtering. The 3rd harmonic, 5th harmonic, 7th harmonic and 9th harmonic components i hαβ :

[0104]

[0105] Power-current coordinated control module, used for adjusting the current based on the preset adjustment coefficient λ, fundamental component i oαβ * and harmonic components i hαβ , get the reference current i with adjustable harmonic content αβ * , to achieve the constant output power of the grid-connected inverter and the three-phase balance of the output current. The specific method is: Figure 4 In the schematic diagram of the power constant and current balance coordinated control module, is the fundamental component of the reference current under the direct power control strategy, i hα 、ihβ is the extracted harmonic component, is the reference current command of the adjustable harmonic content output by the adjusted GCI. The adjustment coefficient λ (value range is [0, 1]) is used to adjust the harmonic content. When λ = 0, That is balanced current control. At this time, the output current is balanced in three phases, but the output power fluctuation is the largest. In the process of λ gradually changing from 0 to 1, the harmonic component i hα 、i hβ Gradually increases, the instantaneous power fluctuation gradually becomes smaller; when λ=1, This is instantaneous power control. While the output power remains constant, the adjusted GCI output current reference command has the highest harmonic content, resulting in severe output current distortion. In practical applications, by setting the value of λ, coordinated control of GCI output current balance and power stability can be achieved.

[0106] The current outer loop control module is used to adjust the reference current i with adjustable harmonic content based on the Quasi Proportional Resonance (QPR) controller. αβ * Perform zero-static-error control to obtain the modulation voltage u αβ * , complete the overall design of the GCI power constant and current balance coordinated control system. The specific method is:

[0107]

[0108] Among them, u αβ * is the modulation voltage; i αβ * is the reference current of adjustable harmonic content; G QPR (s) is the transfer function of the quasi-proportional resonant controller, which can achieve zero-static-error control of the AC signal; k p is the proportional gain; k r is the resonant gain; ω c is the cutoff angular frequency; s is the Laplace operator; ω is the fundamental angular frequency; h is the harmonic number; i αβ is the actual output current.

[0109] Figures 5 and 6 show the filtering effect of the harmonic extraction module of this embodiment, where Figure 5a and Figure 5b This is the GCI reference current and the corresponding spectrum before adding the harmonic extraction module. Figure 6a and Figure 6b The GCI reference current and the corresponding spectrum after adding the harmonic extraction module. The waveform is significantly distorted, with the contents of the 3rd harmonic, 5th harmonic, 7th harmonic, and 9th harmonic being 8.02%, 6.01%, 0.96%, and 0.64%, respectively. After adding the harmonic extraction module, the contents of the four harmonics are almost zero, and the distortion rate is reduced from 10.07% to 0.33%. The simulation results show that the method of this embodiment can effectively extract the harmonic components in the GCI reference current.

[0110] Figure 7 The simulation results of the coordinated control of current balance and power constancy of this embodiment are shown. The simulation data show that when the adjustment coefficient λ = 0, the output current is balanced and the harmonic content is low, but the output active power and output reactive power fluctuate greatly, with the peak values ​​of the fluctuation being 0.9kW and 0.9kvar respectively; during the period of 0.15s-0.25s, the adjustment coefficient λ increases linearly from 0 to 1. At this time, the harmonic component in the output current gradually increases, but the fluctuation of the output active power and output reactive power gradually decreases; after 0.25s, the adjustment coefficient λ is set to 1. At this time, the output current is severely distorted, but the output active power and output reactive power are constant. It can be seen that the reasonable setting of the value of λ can realize the flexible regulation of GCI output power and current quality in different scenarios. At the same time, this process does not require a phase-locked loop and the positive and negative sequence separation link of asymmetric power, and the system delay is small.

[0111] Sinusoidal pulse width modulation module (SPWM), used to modulate the voltage u αβ * Perform sinusoidal pulse width modulation to obtain the grid-connected current i gabc ; Grid current i gabc Meet the requirements of constant power and current balance.

[0112] In an exemplary embodiment, a computer device is provided. The computer device may be a server or a terminal. The internal structure diagram thereof may be as follows: Figure 8As shown. The computer device includes a processor, a memory, an input / output interface (Input / Output, abbreviated as I / O) and a communication interface. The processor, memory and input / output interface are connected through a system bus, and the communication interface is connected to the system bus through the input / output interface. The processor of the computer device is used to provide computing and control capabilities. The memory of the computer device includes a non-volatile storage medium and an internal memory. The non-volatile storage medium stores an operating system, a computer program and a database. The internal memory provides an environment for the operation of the operating system and computer program in the non-volatile storage medium. The database of the computer device is used to store processing data. The input / output interface of the computer device is used to exchange information between the processor and an external device. The communication interface of the computer device is used to communicate with an external terminal through a network connection. When the computer program is executed by the processor, a method for coordinated control of power and current of a grid-connected inverter under a harmonic power grid is implemented.

[0113] Those skilled in the art will understand that Figure 8 The structure shown in the figure is only a block diagram of a part of the structure related to the solution of the present application, and does not constitute a limitation on the computer device to which the solution of the present application is applied. The specific computer device may include more or fewer components than shown in the figure, or combine certain components, or have a different component arrangement.

[0114] In an exemplary embodiment, a computer device is provided, including a memory and a processor. The memory stores a computer program, and the processor implements the steps in the above method embodiments when executing the computer program.

[0115] In an exemplary embodiment, a computer-readable storage medium is provided, storing a computer program. When the computer program is executed by a processor, the steps in the above-mentioned method embodiments are implemented.

[0116] In an exemplary embodiment, a computer program product is provided, including a computer program. When the computer program is executed by a processor, the steps in the above method embodiments are implemented.

[0117] Those skilled in the art will understand that all or part of the processes in the above-mentioned embodiment methods can be implemented by instructing the relevant hardware through a computer program, and the computer program can be stored in a non-volatile computer-readable storage medium. When the computer program is executed, it can include the processes of the embodiments of the above-mentioned methods. Among them, any reference to memory, database or other media used in the embodiments provided in this application may include at least one of non-volatile and volatile memory. Non-volatile memory may include read-only memory (ROM), magnetic tape, floppy disk, flash memory, optical memory, high-density embedded non-volatile memory, resistive random access memory (ReRAM), magnetic random access memory (MRAM), ferroelectric random access memory (FRAM), phase change memory (PCM), graphene memory, etc. Volatile memory may include random access memory (RAM) or external cache memory, etc. By way of illustration and not limitation, RAM may be in various forms, such as static random access memory (SRAM) or dynamic random access memory (DRAM).

[0118] The databases involved in the various embodiments provided herein may include at least one of a relational database and a non-relational database. Non-relational databases may include, but are not limited to, distributed databases based on blockchains. The processors involved in the various embodiments provided herein may include, but are not limited to, general-purpose processors, central processing units, graphics processing units, digital signal processors, programmable logic units, data processing logic units based on quantum computing, and the like.

[0119] The technical features of the above embodiments can be combined arbitrarily. In order to make the description concise, 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, they should be considered to be within the scope of this specification.

[0120] This document uses specific examples to illustrate the principles and implementation methods of this application. The description of the above examples is only intended to help understand the method and core concept of this application. At the same time, for those skilled in the art, based on the concept of this application, there may be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as limiting this application.

Claims

1. A method for coordinated control of power and current of a grid-connected inverter under a harmonic power grid, characterized in that: The method for coordinated control of power and current of a grid-connected inverter under a harmonic power grid includes: Based on the obtained three-phase grid AC voltage u gabc , get the three-phase grid AC voltage u gabc Two-phase AC grid voltage u in the αβ stationary coordinate system gαβ ; Based on the preset active power reference value P * and reactive power reference value Q * And the two-phase grid AC voltage u gαβ , calculate the reference current i under the direct power control strategy hαβ * ; Based on the fast delay signal destructive filtering theory, the reference current i under the direct power control strategy is hαβ * The harmonics in the filter are processed to obtain the fundamental component i oαβ * and harmonic components i hαβ ; Based on the preset adjustment coefficient λ, the fundamental wave component i oαβ * and the harmonic component i hαβ , get the reference current i with adjustable harmonic content αβ * ; Based on the quasi-proportional resonant controller, the reference current i αβ * Perform zero-static-error control to obtain the modulation voltage u αβ * ; The modulation voltage u αβ * Perform sinusoidal pulse width modulation to obtain the grid-connected current i gabc The grid-connected current i gabc Meet the requirements of constant power and current balance.

2. The method for coordinated control of power and current of a grid-connected inverter under a harmonic power grid according to claim 1, characterized in that: Based on the preset active power reference value P * and reactive power reference value Q * And the two-phase grid AC voltage u gαβ , calculate the reference current i under the direct power control strategy hαβ * , specifically: in, is the reference current i under the direct power control strategy hαβ * a first current component of; is the reference current i under the direct power control strategy hαβ * The second current component of P * is the active power reference value; Q * is the reactive power reference value; u gα is the two-phase AC grid voltage u gαβ The first voltage component of u gβ is the two-phase AC grid voltage u gαβ The second voltage component of 3. The method for coordinated control of power and current of a grid-connected inverter under a harmonic power grid according to claim 1, characterized in that: Based on the fast delay signal destructive filtering theory, the reference current i under the direct power control strategy is hαβ * The harmonics in the filter are processed to obtain the fundamental component i oαβ * and harmonic components i hαβ , specifically including: Based on the fast delay signal cancellation filtering theory, the reference current i under the direct power control strategy is filtered out. hαβ * The 5th harmonic and 7th harmonic, as well as the 3rd harmonic and 9th harmonic, get the fundamental component i oαβ * ; The reference current i under the direct power control strategy hαβ * and the fundamental component i oαβ * Perform difference calculation to obtain harmonic component i hαβ .

4. The method for coordinated control of power and current of a grid-connected inverter under a harmonic power grid according to claim 3, characterized in that: The filter expressions for the 5th harmonic and the 7th harmonic are: in, is the fundamental signal after filtering out the 5th and 7th harmonics; T is the fundamental period; u(t) is the AC voltage at the current time t; is the lag of the current moment t AC voltage; is the lag of the current moment t AC voltage; The filter expressions for the 3rd and 9th harmonics are: Among them, FDSC(0,12) is the fundamental signal after filtering out the 3rd harmonic and 9th harmonic.

5. The method for coordinated control of power and current of grid-connected inverters in harmonic power grids according to claim 1, characterized in that: Based on the quasi-proportional resonant controller, the reference current i αβ * Perform zero-static-error control to obtain the modulation voltage u αβ * , specifically: Among them, u αβ * is the modulation voltage; i αβ * is the reference current of adjustable harmonic content; G QPR (s) is the transfer function of the quasi-proportional resonant controller; k p is the proportional gain; k r is the resonant gain; ω c is the cutoff angular frequency; s is the Laplace operator; ω is the fundamental angular frequency; h is the harmonic number; i αβ is the actual output current.

6. The method for coordinated control of power and current of a grid-connected inverter under a harmonic power grid according to claim 1, characterized in that: The method for coordinated control of power and current of a grid-connected inverter under a harmonic power grid further includes: Based on the fast Fourier transform, the reference current i under the direct power control strategy is hαβ * Decompose and get the fundamental component i oαβ * and harmonic components i hαβ superimposed form.

7. A power and current coordinated control device for a grid-connected inverter under a harmonic power grid, characterized in that: The power and current coordinated control device for the grid-connected inverter under the harmonic power grid includes: Direct power control module for: Based on the obtained three-phase grid AC voltage u gabc , get the three-phase grid AC voltage u gabc Two-phase AC grid voltage u in the αβ stationary coordinate system gαβ ; Based on the preset active power reference value P * and reactive power reference value Q * And the two-phase grid AC voltage u gαβ , calculate the reference current i under the direct power control strategy hαβ * ; The harmonic extraction module is used to extract the reference current i under the direct power control strategy based on the fast delay signal cancellation filtering theory. hαβ * The harmonics in the filter are processed to obtain the fundamental component i oαβ * and harmonic components i hαβ ; The power-current coordinated control module is used to adjust the power-current coordinated control module based on the preset adjustment coefficient λ and the fundamental component i oαβ * and the harmonic component i hαβ , get the reference current i with adjustable harmonic content αβ * ; The current outer loop control module is used to adjust the reference current i of the adjustable harmonic content based on the quasi-proportional resonant controller. αβ * Perform zero-static-error control to obtain the modulation voltage u αβ * ; Sine pulse width modulation module, used to modulate the voltage u αβ * Perform sinusoidal pulse width modulation to obtain the grid-connected current i gabc The grid-connected current i gabc Meet the requirements of constant power and current balance.

8. A computer device comprising: A memory, a processor, and a computer program stored in the memory and capable of running on the processor, characterized in that the processor executes the computer program to implement the power and current coordinated control method of the grid-connected inverter under the harmonic power grid according to any one of claims 1 to 6.

9. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the method for coordinated control of power and current of a grid-connected inverter in a harmonic power grid according to any one of claims 1 to 6 is implemented.

10. A computer program product comprising a computer program, characterized in that When the computer program is executed by a processor, the method for coordinated control of power and current of a grid-connected inverter in a harmonic power grid according to any one of claims 1 to 6 is implemented.

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