Harmonic suppression predictive control method and module for three-phase grid-connected inverter system

Abstract

The invention discloses a harmonic suppression predictive control method and module for a three-phase grid-connected inverter system, and belongs to the field of power electronic control. The method comprises the following steps: firstly, establishing a continuous domain state space model of a three-phase grid-connected inverter system under a dq coordinate system, discretizing the state space model at a k moment, and obtaining a prediction model of a k + 1 sampling power grid current; enabling the power grid current prediction model to reach a power grid current reference value at a k + 1 sampling moment, and calculating a reference inverter voltage control reference value; calculating a voltage control reference value of the inverter integrated with harmonic suppression by combining the voltage control reference value of the reference inverter and the discretized quasi-resonance controller; determining an optimal voltage vector and action time of an inverter voltage control reference value capable of synthesizing the integrated harmonic suppression; and generating a control pulse signal and applying the control pulse signal to a switching tube of the three-phase grid-connected inverter to realize harmonic suppression prediction control of the three-phase grid-connected inverter system. The steps are simple, and the harmonic prediction and suppression control effect is good.

Description

Technical Field

[0001] This invention relates to the field of electric drive technology, and in particular to a method and module for predictive control of harmonic suppression in a three-phase grid-connected inverter system. Background Technology

[0002] Photovoltaic energy boasts numerous advantages, including cleanliness, renewability, flexibility, and reliability, making it a crucial component of distributed energy systems. Three-phase grid-connected inverters, as key interface devices between distributed photovoltaic power sources and the grid, directly impact grid connection quality and grid stability. While increasing the proportion of clean energy, this also exacerbates power quality issues in three-phase grid-connected inverter systems. Three-phase grid-connected inverters suffer from harmonic problems caused by component aging and imbalance, resulting in severe distortion of the photovoltaic power generation system's output current. This leads to significant harmonic pollution and disturbances to the grid during large-scale applications of three-phase grid-connected inverter systems. These severe harmonic problems significantly reduce the power generation quality of three-phase grid-connected inverter systems, severely limiting the further increase in the penetration rate of photovoltaic power generation systems.

[0003] In existing technologies, the main method for suppressing harmonic pollution in three-phase grid-connected inverter systems is to absorb harmonic currents generated by harmonic sources nearby using power electronic devices, primarily employing passive and active filters. However, passive filters may resonate with the system impedance and can only filter specific harmonics, heavily relying on component parameters, and their filtering effect is unsatisfactory for loads with harmonic orders varying over time. Active filters are too expensive and cannot provide differentiated, targeted pollution control. Summary of the Invention

[0004] To address the shortcomings of existing technologies, a method and module for predictive control of harmonic suppression in a three-phase grid-connected inverter system are provided. This method and module can reduce background harmonics in the grid through control strategies without changing the hardware circuit, thereby improving grid quality.

[0005] To achieve the above technical objectives, this invention provides a harmonic suppression predictive control method for a three-phase grid-connected inverter system, comprising the following steps:

[0006] The grid current and grid voltage of the three-phase grid-connected inverter system are sampled, and the grid voltage phase is obtained through a phase-locked loop. The state variables in the abc coordinate system are transformed by Park to obtain the state variables in the dq coordinate system. The grid current and grid voltage are used to establish a continuous domain state-space model of the three-phase grid-connected inverter system in the dq coordinate system.

[0007] At time k, the continuous domain state-space model of the three-phase grid-connected inverter system in the dq coordinate system is precisely discretized, and the grid current prediction model i at time k+1 is obtained recursively. g,k+1 ;

[0008] Let grid current prediction model i g,k+1 If the grid current reference value is reached at the next sampling time k+1, the reference inverter voltage control reference value can be calculated.

[0009] Combined with reference inverter voltage control reference value Using a discretized quasi-resonant controller, the inverter voltage control reference value with integrated harmonic suppression h in the dq coordinate system is calculated. Then, an inverse Park transform is performed to obtain the inverter voltage control reference value with integrated harmonic suppression in the stationary αβ coordinate system.

[0010] The optimal voltage vectors v0, v1, v2 and their application times t0, t1, t2 that can synthesize the inverter voltage control reference value for integrated harmonic suppression are determined using the volt-second balance principle. Corresponding control pulse signals are generated and applied to the switching transistors of the three-phase grid-connected inverter to achieve predictive control of harmonic suppression in the three-phase grid-connected inverter system.

[0011] Furthermore, the continuous domain state-space model of the three-phase grid-connected inverter system in the dq coordinate system is as follows:

[0012]

[0013] In the formula: x=[i gd i gq ] T For state variables, u = [v d v q u gd u gq ] T To control the input, the coefficient matrices A and B are as follows: Among them, i gd i gq v d v q u gd u gq These represent the grid current, inverter voltage, and grid voltage of a three-phase grid-connected inverter system in the dq coordinate system, respectively. L and R represent the filter inductance and the parasitic resistance of the filter inductance, respectively. ω g ω is the fundamental angular frequency of the grid voltage.

[0014] Furthermore, the grid current prediction model i at time k+1 is obtained. g,k+1The specific process is as follows:

[0015] Let the sampling period of the three-phase grid-connected inverter system be T. s At time k, the state-space model in the continuous domain is discretized using the exact discretization method, resulting in the following prediction model for the three-phase grid-connected inverter system:

[0016] i g,k+1 =A d i g,k +B d u k

[0017] In the formula, i g,k =[i gd,k i gq,k ] T , represents the grid current collected at time k, i g,k+1 =[i gd,k+1 i gq,k+1 ] T , represents the prediction model of the grid current at time k+1, u k =[v d,k v q,k u gd,k u gq,k ] T , representing the inverter voltage and grid voltage sampled at time k, A d B d These represent the coefficient matrices of the system discretization model calculated using the exact discretization method: B d =A -1 (A d -I2)B, where e is the base of the natural logarithm, and I2 is the second-order identity matrix.

[0018] Furthermore, based on the grid current prediction model i g,k+1 When the grid current reference value is reached at sampling time k+1, the reference inverter voltage control value is calculated as follows:

[0019] Based on the system grid current reference value and its prediction model, let The reference voltage control value of the three-phase grid-connected inverter system can then be calculated.

[0020]

[0021] in This serves as a reference value for inverter voltage control. u is the reference value for the grid current. g,k =[u gd,k u gq,k ]T Let k be the grid voltage at time k. C1 and C2 are coefficient matrices.

[0022] Furthermore, in order to resist the interference caused by harmonic disturbances to the three-phase grid-connected inverter system, a discretized quasi-resonant controller is used to suppress harmonics of specific orders in the three-phase grid-connected inverter system. The discretized quasi-resonant controller is as follows:

[0023]

[0024] in, K r ω represents the proportionality constant. c Indicates the cutoff frequency; T s This represents the sampling period of the three-phase grid-connected inverter system; l takes values ​​of 1, 2, 3, ..., and by adjusting the value of l, harmonics of different orders can be suppressed.

[0025] Furthermore, the reference inverter voltage control value based on the three-phase grid-connected inverter system Using a discretized quasi-resonant controller, the inverter voltage control reference value for a three-phase grid-connected inverter system with integrated harmonic suppression is calculated.

[0026]

[0027] After sorting, we can obtain:

[0028]

[0029] in, These represent the reference values ​​for inverter voltage control at time k and time k-2, respectively. These are the inverter voltage control reference values ​​with integrated harmonic suppression at times k, k-1, and k-2, respectively.

[0030] Furthermore, by performing an inverse Park transform on the inverter voltage control reference value representing integrated harmonic suppression on the dq axis, the inverter voltage control reference value with integrated harmonic suppression in the stationary αβ coordinate system is obtained.

[0031]

[0032] Where θ is the phase of the grid voltage. This represents the inverter voltage control reference value for integrated harmonic suppression in the stationary αβ coordinate system.

[0033] Furthermore, the optimal voltage vectors v0, v1, v2 and their application times t0, t1, t2 for synthesizing the inverter voltage control reference value with integrated harmonic suppression are determined using the volt-second balance principle, and corresponding control pulse signals are generated. These control pulse signals are then applied to the switching transistors of the three-phase grid-connected inverter to achieve predictive control of harmonic suppression in the three-phase grid-connected inverter system. The process is as follows:

[0034] Predictive control reference value based on integrated resonance suppression of three-phase grid-connected inverter Let three intermediate variables A, B, and C be represented as follows:

[0035]

[0036] When A>0, B>0, and C<0, the corresponding optimal voltage vector is v0=v αβ,0 v1 = v αβ,1 and v2 = v αβ,2 When A>0, B<0, and C<0, the corresponding optimal voltage vector is v0 = v αβ,0 v1 = v αβ,2 and v2 = v αβ,3 When A>0, B<0, and C>0, the corresponding optimal voltage vector is v0 = v αβ,0 v1 = v αβ,3 and v2 = v αβ,4 When A < 0, B < 0, C > 0, the corresponding optimal voltage vector is v0 = v αβ,0 v1 = v αβ,4 and v2 = v αβ,5 When A < 0, B > 0, and C > 0, the corresponding optimal voltage vector is v0 = v αβ,0 v1 = v αβ,5 and v2 = v αβ,6 When A<0, B>0, and C<0, the corresponding optimal voltage vector is v0 = v αβ,0 v1 = v αβ,6 and v2 = v αβ,1 ;

[0037] Let the durations of the optimal voltage vectors v0, v1, and v2 be t0, t1, and t2, respectively; in one sampling period T s Based on the volt-second balance principle, we can obtain:

[0038]

[0039] The duration of action of each vector can be obtained from the above equation:

[0040]

[0041] Among them, V dcThis is the DC bus voltage; The inverter voltage control reference value with integrated harmonic suppression in the αβ coordinate system;

[0042] The switching states corresponding to the optimal voltage vectors v0, v1, and v2 are applied sequentially according to the seven-segment symmetrical model at action times t0, t1, and t2, generating the following control pulse signals:

[0043]

[0044] Ultimately, predictive control can be achieved by directly applying control pulse signals to the switching transistors of the three-phase grid-connected inverter system.

[0045] A computer device includes a processor and a memory, the processor being electrically connected to the memory, the memory being used to store instructions and data, and the processor being used to execute the harmonic suppression predictive control method and module for a three-phase grid-connected inverter system according to any one of claims 1-8.

[0046] A harmonic suppression predictive control module for a three-phase grid-connected inverter system includes a prediction model construction module, a reference inverter voltage control reference value calculation module, a harmonic suppression module, and a pulse generation module connected in sequence.

[0047] The prediction model building module establishes a continuous domain state-space model of the three-phase grid-connected inverter system in the dq coordinate system by sampling the grid current and grid voltage of the three-phase grid-connected inverter system and performs precise discretization to obtain the grid current prediction model of the three-phase grid-connected inverter system at time k+1.

[0048] The reference inverter voltage control reference value calculation module calculates the reference inverter voltage control reference value based on the idea of ​​making the grid current prediction model reach the grid current reference value at sampling time k+1.

[0049] The harmonic suppression module, combining the reference inverter voltage control reference value and the discretized quasi-resonant controller, calculates the inverter voltage control reference value with integrated harmonic suppression in the dq coordinate system, and performs Park inverse transformation to obtain the inverter voltage control reference value with integrated harmonic suppression in the stationary αβ coordinate system.

[0050] The pulse generation module uses the volt-second balance principle to determine the optimal voltage vectors v0, v1, v2 and the action times t0, t1, t2 that can synthesize the inverter voltage control reference value with integrated harmonic suppression, and generates the corresponding three-phase grid-connected inverter system control pulse signals.

[0051] Compared with existing technologies, the beneficial effects of this invention are as follows: This invention provides a predictive control strategy for three-phase grid-connected inverter systems to reduce grid background harmonics and improve grid quality. Compared with existing solutions, the method provided by this invention does not require changes to external hardware circuits, has low operation and usage costs, and is easier to promote in engineering. This invention uses a quasi-resonant controller embedded with a predictive control strategy to suppress grid background harmonics, which has stronger anti-disturbance capabilities and is suitable for various operating scenarios compared with existing technologies. Attached Figure Description

[0052] Figure 1 This is a flowchart of the harmonic suppression prediction control method for a three-phase grid-connected inverter system in an embodiment of the present invention;

[0053] Figure 2 The above are the steady-state waveform of the grid-connected current and the harmonic spectrum diagram of the three-phase grid-connected inverter system without adding a harmonic suppression term in the embodiments of the present invention.

[0054] Figure 3 The steady-state waveform of the grid-connected current and the schematic diagram of the harmonic spectrum are shown when a harmonic suppression term is added to the phase-connected grid inverter system in the embodiment of the present invention. Detailed Implementation

[0055] The embodiments of the present invention will be further described below with reference to the accompanying drawings:

[0056] like Figure 1 As shown, the three-phase grid-connected inverter system to which this invention applies includes: a DC bus voltage source is converted into an AC voltage square wave signal by a three-phase voltage source inverter, and then connected to the power grid via an output L filter. The three-phase grid current and three-phase grid voltage are sampled sequentially.

[0057] In the diagram, V dc This represents the DC bus voltage; L and R represent the filter inductance and parasitic resistance, respectively. g,abc Represents grid current; u g,abc Indicates grid voltage; i g * i is the reference current for the power grid. g,k and v g,k Let represent the grid current, grid voltage, filter capacitor voltage, and filter inductor current in the α-β stationary coordinate system at time k, respectively; the sampled grid voltage is fed into a phase-locked loop to obtain the grid voltage phase θ; denoted by k, represents the inverter voltage control reference value of a three-phase grid-connected inverter system with integrated harmonic suppression in the stationary αβ coordinate system at time k; S represents the switching state of the upper bridge arm switch transistor of the inverter.

[0058] This invention discloses a harmonic suppression predictive control method for a three-phase grid-connected inverter system, the steps of which are as follows:

[0059] Step 1: Construct the state-space model of the three-phase grid-connected inverter system in the continuous domain under the dq coordinate system:

[0060]

[0061] In the formula: x=[i gd i gq ] T For state variables, u = [v d v q u gd u gq ] T To control the input, the coefficient matrices A and B are as follows: Among them, i gd i gq v d v q u gd u gq These represent the grid current, inverter voltage, and grid voltage in the dq coordinate system, respectively; L and R are the filter inductors and their parasitic resistance; ω is... g ω is the fundamental angular frequency of the grid voltage.

[0062] Step 2: Let the sampling period of the three-phase grid-connected inverter system be T. s At time k, the state-space model in the continuous domain is discretized using the exact discretization method, resulting in the following prediction model for the three-phase grid-connected inverter system:

[0063] i g,k+1 =A d i g,k +B d u k

[0064] In the formula, i g,k =[i gd,k i gq,k ] T Represents the grid current collected at time k, i g,k+1 =[i gd,k+1 i gq,k+1 ] T For the prediction model of the grid current at time k+1, u k =[v d,k v q,k u gd,k u gq,k ] T A represents the inverter voltage and grid voltage collected at time k. d B d The coefficient matrix of the system discretized model calculated using the exact discretization method is as follows: B d =A-1 (A d -I2)B, where e is the base of the natural logarithm, and I2 is the second-order identity matrix.

[0065] Step 3: Based on the system grid current reference value and its prediction model, let... The reference inverter voltage control value for a three-phase grid-connected inverter system can then be calculated.

[0066]

[0067] in This serves as a reference value for inverter voltage control. u is the reference value for the grid current. g,k =[u gd,k u gq,k ] T Let k be the grid voltage at time k. C1 and C2 are coefficient matrices.

[0068] Step 4: To resist harmonic disturbances from interfering with the three-phase grid-connected inverter system, a model similar to the input signal needs to be added to the control loop of the three-phase grid-connected inverter system. The input quantity of the grid to the three-phase grid-connected inverter system is a sinusoidal current; therefore, a discretized quasi-resonant controller is used to suppress harmonics of specific orders in the three-phase grid-connected inverter system. The discretized quasi-resonant controller is as follows:

[0069]

[0070] in, K r ω is the proportionality constant. c The cutoff frequency is set to l, which can be 1, 2, 3, ... By adjusting the value of l, harmonics of different orders can be suppressed.

[0071] Reference value for inverter voltage control based on a three-phase grid-connected inverter system Using a discretized quasi-resonant controller, the inverter voltage control reference value for a three-phase grid-connected inverter system with integrated harmonic suppression is calculated.

[0072]

[0073] After sorting, we can obtain:

[0074]

[0075] in, These represent the reference values ​​for inverter voltage control at time k and time k-2, respectively. These are the inverter voltage control reference values ​​with integrated harmonic suppression at times k, k-1, and k-2, respectively.

[0076] By performing an inverse Park transform on the inverter voltage control reference value representing integrated harmonic suppression on the dq axis, the inverter voltage control reference value with integrated harmonic suppression in the stationary αβ coordinate system is obtained.

[0077]

[0078] Where θ is the phase of the grid voltage. This represents the inverter voltage control reference value for integrated harmonic suppression in the stationary αβ coordinate system.

[0079] Step 5: Predict control reference values ​​based on the integrated resonance suppression three-phase grid-connected inverter Let three intermediate variables A, B, and C be represented as follows:

[0080]

[0081] When A>0, B>0, and C<0, the corresponding optimal voltage vector is v0=v αβ,0 v1 = v αβ,1 and v2 = v αβ,2 When A>0, B<0, and C<0, the corresponding optimal voltage vector is v0 = v αβ,0 v1 = v αβ,2 and v2 = v αβ,3 When A>0, B<0, and C>0, the corresponding optimal voltage vector is v0 = v αβ,0 v1 = v αβ,3 and v2 = v αβ,4 When A < 0, B < 0, C > 0, the corresponding optimal voltage vector is v0 = v αβ,0 v1 = v αβ,4 and v2 = v αβ,5 When A < 0, B > 0, and C > 0, the corresponding optimal voltage vector is v0 = v αβ,0 v1 = v αβ,5 and v2 = v αβ,6 When A<0, B>0, and C<0, the corresponding optimal voltage vector is v0 = v αβ,0 v1 = v αβ,6 and v2 = v αβ,1 .

[0082] Assume that an inverter voltage control reference value with integrated harmonic suppression can be synthesized. The optimal voltage vectors v0, v1, and v2 have action times of t0, t1, and t2, respectively, within one sampling period T. s Based on the volt-second balance principle, we can obtain:

[0083]

[0084] The duration of action of each vector can be obtained from the above equation:

[0085]

[0086] Among them, V dc This is the DC bus voltage. This is the reference value for inverter voltage control with integrated harmonic suppression in the αβ coordinate system.

[0087] The switching states corresponding to the optimal voltage vectors v0, v1, and v2 of the inverter voltage control reference value that can synthesize integrated harmonic suppression are applied symmetrically in 7 segments according to the action times t0, t1, and t2, generating the following control pulse signals:

[0088]

[0089] Finally, the control pulse signal is applied directly to the switching transistors of the three-phase grid-connected inverter.

[0090] To verify the harmonic suppression prediction control method and module for a three-phase grid-connected inverter system provided by this invention, the method was applied to a three-phase grid-connected inverter system. Specific parameters are given in Table 1.

[0091] Table 1

[0092]

[0093] Figure 2 The diagram shows the steady-state waveform of the grid current and the harmonic spectrum when the harmonic suppression prediction control method for the three-phase grid-connected inverter system of the present invention is not used to add a harmonic suppression term. Figure 3 The diagram shows the steady-state waveform of the grid current and the schematic diagram of the harmonic spectrum when a harmonic suppression term is added to the three-phase grid-connected inverter system harmonic suppression predictive control method of the present invention. Figure 2 and Figure 3 The comparison shows that the method provided by this invention can effectively reduce grid current harmonics during system steady-state operation, ensuring the power generation quality of the three-phase grid-connected inverter system. A comparison of the harmonic spectrum diagrams reveals that the method provided by this invention can achieve lower grid current harmonic distortion.

Claims

1. A three-phase grid-connected inverter system harmonic suppression predictive control method, characterized in that: Here are the steps: The state variables of the three-phase grid-connected inverter system, namely, grid current and grid voltage, are sampled, and the grid voltage phase is obtained through a phase-locked loop. The state variables in the abc coordinate system are transformed by Park to obtain the state variables in the dq coordinate system, and the continuous domain state space model of the three-phase grid-connected inverter system in the dq coordinate system is established using the grid current and grid voltage; At time k, the continuous domain state space model of the three-phase grid-connected inverter system in the dq coordinate system is accurately discretized, and the grid current prediction model i at time k+1 is obtained by recursion. g,k+1 ; Let the grid current prediction model i g,k+1 At the next k+1 sampling time, the grid current reference value can be reached, and the reference inverter voltage control reference value is calculated. Combined with the reference inverter voltage control reference value The inverter voltage control reference value of the integrated harmonic suppression h in the dq coordinate system is calculated with the discretized quasi-resonant controller And perform Park inverse transformation to obtain the inverter voltage control reference value with integrated harmonic suppression in the stationary αβ coordinate system The volt-second balance principle is used to determine the optimal voltage vectors v0, v1, v2 and action times t0, t1, t2 of the inverter voltage control reference value that can synthesize integrated harmonic suppression, generate corresponding control pulse signals, and apply the control pulse signals to the switching tubes of the three-phase grid-connected inverter to realize harmonic suppression predictive control of the three-phase grid-connected inverter system.

2. The harmonic suppression prediction control method for a three-phase grid-connected inverter system according to claim 1, characterized in that: The continuous domain state space model of the three-phase grid-connected inverter system in the dq coordinate system is as follows: Where: x = [i gd i gq ] T is the state variable, u=[v d v q u gd u gq ] T is the control input, and the coefficient matrices A and B are: Among them, i gd 、i gq 、v d 、v q 、u gd 、u gq are the grid current, inverter voltage and grid voltage of the three-phase grid-connected inverter system in the dq coordinate system, L and R represent the filter inductance and the parasitic resistance of the filter inductance, respectively. g is the fundamental angular frequency of the grid voltage.

3. The harmonic suppression prediction control method for a three-phase grid-connected inverter system according to claim 2, characterized in that: Get the grid current prediction model i at time k+1 g,k+1 The specific process is as follows: Assume that the sampling period of the three-phase grid-connected inverter system is T s At time k, the state space model in the continuous domain is discretized using the precise discretization method, and the prediction model of the three-phase grid-connected inverter system is obtained as follows: i g,k+1 =A d i g,k +B d u k In the formula, i g,k =[i gd,k i gq,k ] T , represents the grid current collected at time k, i g,k+1 =[i gd,k+1 i gq,k+1 ] T , represents the prediction model of the grid current at time k+1, u k =[v d,k v q,k u gd,k u gq,k ] T , represents the inverter voltage and grid voltage collected at time k, A d , B d They represent the discretization model coefficient matrices of the system calculated using the exact discretization method: d =e ATs , Β d =A -1 (A d -I2)B, where e is the base of the natural logarithm and I2 is the second-order identity matrix.

4. The harmonic suppression prediction control method for a three-phase grid-connected inverter system according to claim 3, characterized in that: Based on the grid current prediction model i g,k+1 At the k+1 sampling time, the grid current reference value is reached and the reference inverter voltage control reference value is calculated. The process is as follows: According to the system grid current reference value and its prediction model, let The reference value of the three-phase grid-connected inverter system can be calculated. in is the reference value for the base inverter voltage control, is the grid current reference value, u g,k =[u gd,k u gq,k ] T is the grid voltage at time k, C1 and C2 are coefficient matrices.

5. The harmonic suppression prediction control method for a three-phase grid-connected inverter system according to claim 4, characterized in that: In order to resist the interference of harmonic disturbance to the three-phase grid-connected inverter system, a discrete quasi-resonant controller is used to suppress the harmonics of a specific order of the three-phase grid-connected inverter system. The discrete quasi-resonant controller is as follows: in, K r Represents the proportionality coefficient; ω c represents the cut-off frequency; T s It represents the sampling period of the three-phase grid-connected inverter system; l is 1, 2, 3, etc., and harmonics of different orders can be suppressed by adjusting the value of l.

6. A three-phase grid-connected inverter system harmonic suppression prediction control method according to claim 5, characterized in that: Benchmark inverter voltage control reference value based on three-phase grid-connected inverter system The inverter voltage control reference value of the three-phase grid-connected inverter system with integrated harmonic suppression is calculated by using a discrete quasi-resonant controller After finishing, we can get: in, They represent the reference values ​​of the reference inverter voltage control at time k and time k-2 respectively, are the inverter voltage control reference values ​​for integrated harmonic suppression at moments k, k-1 and k-2 respectively.

7. A three-phase grid-connected inverter system harmonic suppression prediction control method according to claim 6, characterized in that: By performing Park inverse transformation on the inverter voltage control reference value with integrated harmonic suppression represented by the dq axis, the inverter voltage control reference value with integrated harmonic suppression in the stationary αβ coordinate system is obtained. Where θ is the grid voltage phase, It represents the inverter voltage control reference value with integrated harmonic suppression in the stationary αβ coordinate system.

8. The harmonic suppression prediction control method for a three-phase grid-connected inverter system according to claim 7, characterized in that: The optimal voltage vector v0, v1, v2 and action time t0, t1, t2 of the inverter voltage control reference value capable of synthesizing integrated harmonic suppression are determined by using the volt-second balance principle, and a corresponding control pulse signal is generated. The control pulse signal is applied to the switch tube of the three-phase grid-connected inverter to realize the harmonic suppression predictive control of the three-phase grid-connected inverter system. The process is as follows: Predictive control reference values ​​for three-phase grid-connected inverters based on integrated resonance suppression Set three intermediate variables A, B, and C to be expressed as: When A>0, B>0, C<0, the corresponding optimal voltage vector is v0=v αβ,0 、v1=v αβ,1 and v2 = v αβ,2 ; When A>0, B<0, C<0, the corresponding optimal voltage vector is v0=v αβ,0 、v1=v αβ,2 and v2 = v αβ,3 ; When A>0, B<0, C>0, the corresponding optimal voltage vector is v0=v αβ,0 、v1=v αβ,3 and v2 = v αβ,4 ; When A<0, B<0, C>0, the corresponding optimal voltage vector is v0=v αβ,0 、v1=v αβ,4 and v2 = v αβ,5 ; When A<0, B>0, C>0, the corresponding optimal voltage vector is v0=v αβ,0 、v1=v αβ,5 and v2 = v αβ,6 ; When A<0, B>0, C<0, the corresponding optimal voltage vector is v0=v αβ,0 、v1=v αβ,6 and v2 = v αβ,1 ; Assume that the action time of the optimal voltage vectors v0, v1, and v2 are t0, t1, and t2 respectively; in a sampling period T s Based on the volt-second balance principle, we can get: From the above formula, the action time of each vector can be solved as: Among them, V dc is the DC bus voltage; is the inverter voltage control reference value with integrated harmonic suppression in the αβ coordinate system; The switch states corresponding to the optimal voltage vectors v0, v1, and v2 are respectively acted on in accordance with the 7-segment symmetric model according to the action times t0, t1, and t2, and the control pulse signals are generated as follows: Finally, predictive control can be achieved by directly applying the control pulse signal to the switch tube of the three-phase grid-connected inverter system.

9. A computer device, characterized in that: It includes a processor and a memory, the processor is electrically connected to the memory, the memory is used to store instructions and data, and the processor is used to execute the harmonic suppression prediction control method for a three-phase grid-connected inverter system as described in any one of claims 1-8.

10. A three-phase grid-connected inverter system harmonic suppression prediction control module, characterized in that: The method comprises a prediction model building module connected in sequence, a reference inverter voltage control reference value calculation module, a harmonic suppression module and a pulse generation module prediction model building module. By sampling the grid current and grid voltage of the three-phase grid-connected inverter system, a continuous domain state space model of the three-phase grid-connected inverter system in the dq coordinate system is established and accurately discretized, and a grid current prediction model of the three-phase grid-connected inverter system at time k+1 is obtained; The reference inverter voltage control reference value calculation module calculates the reference inverter voltage control reference value based on the idea of ​​making the grid current prediction model reach the grid current reference value at the k+1 sampling time; The harmonic suppression module combines the reference inverter voltage control reference value with the discretized quasi-resonant controller to calculate the inverter voltage control reference value with integrated harmonic suppression in the dq coordinate system, and performs Park inverse transformation to obtain the inverter voltage control reference value with integrated harmonic suppression in the stationary αβ coordinate system; The pulse generation module uses the volt-second balance principle to determine the optimal voltage vectors v0, v1, v2 and action times t0, t1, t2 that can synthesize the inverter voltage control reference value with integrated harmonic suppression, and generates the corresponding three-phase grid-connected inverter system control pulse signal.

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