A one-stop intelligent megawatt enclosure system based on TE-SVM modulation, along with its intelligent controller and control method.

Abstract

This invention discloses a one-stop intelligent megawatt box system based on TE-SVM modulation and its intelligent controller and control method, including an MPPT controller for tracking the maximum power of a DC / DC converter, a positive and negative sequence voltage decomposition module, a phase-locked loop, and a C-type control for the LCL filter. f With R f A current correction module that corrects the three-phase average current output from the component; a positive-sequence theoretical active power reference current conversion module; a positive-sequence theoretical reactive power reference current conversion module; and an output voltage U. α +、U β + Two-phase positive sequence static voltage converter module, output voltage U α -, U β A two-phase negative-sequence static voltage converter module, a TE-SVM waveform generation module based on the TLS-ESPRIT algorithm for estimating smart grid frequencies, and the TE-SVM waveform generation module utilizing voltage U α +、U β + and U α -, U β - Synthesize a reference voltage and generate a waveform based on the estimated smart grid frequency to control the inverter to perform inversion.

Description

Technical Field

[0001] This invention belongs to the field of Internet of Things smart grid power transmission and distribution, and relates to a one-stop smart megawatt box system based on TE-SVM modulation and its smart controller and control method for friendly access to the smart grid. Background Technology

[0002] As the proportion of photovoltaic (PV) renewable energy connected to the traditional power grid approaches its upper limit, the smart grid, as a fundamental unit of the global energy internet, introduces advanced power electronic controllers to achieve grid-friendly smart grid connection of one-stop smart megawatt box systems, aiming to provide efficient power supply from clean energy. However, in practical applications, the research findings have revealed some pressing issues: While photovoltaic power generation is a green and clean energy source, it brings adverse effects to the distribution network, such as overvoltage, three-phase imbalance, frequency deviation, harmonic pollution, and voltage sags. For example, existing synchronous coordinate software phase-locked loop (PLL) control methods have advantages such as simplicity and fast response speed, but when encountering three-phase imbalance or voltages containing high-frequency harmonics, the PLL results have significant errors. While proportional-integral (PI) regulators can be used to reduce system bandwidth to minimize errors, the response speed is significantly slowed, making it difficult to meet system requirements. Furthermore, existing PLL technology lacks the ability to adapt to optimal frequency adjustments that match phase and amplitude when the grid frequency shifts, remaining locked at the frequency and phase when the grid was not shifted, leading to inverter failure. Especially when encountering a large voltage drop, due to the lack of voltage, phase locking cannot be achieved, and both reactive and active power are zero, resulting in insufficient reactive power support for the power grid, reduced voltage stability, and large voltage fluctuations during faults.

[0003] Currently, inverter modulation technologies employing PI regulation and low-pass filtering involve limited control factors and do not effectively regulate all voltage, current, phase, amplitude, and power factors from the photovoltaic array input to the output and grid connection point. However, fluctuations in any of these factors from the photovoltaic array input to the output and grid connection point can significantly reduce the efficiency and inverse variables of the converter and inverter. Current proportional-integral (PI) control struggles to correct unbalanced disturbance current components, cannot independently control positive and negative sequence current components, and has poor low-order harmonic compensation capabilities. Furthermore, widespread grid connection contributes to a weak grid characteristic, exhibiting time-varying linear impedance and background harmonics. Even with existing active or passive damping using LCL filtering to suppress harmonics, the inductive component of the grid impedance still affects current control performance. When the grid inductive reactance is high, for LCL inverters employing a current-open single-loop control strategy, changes in grid inductive reactance can cause a shift in their resonant frequency. Existing modulation controllers cannot track this frequency shift. The LCL filter itself is a third-order system, exhibiting resonant spikes and harmonic issues at its resonant frequency, leading to system instability and becoming a significant factor affecting grid power quality and the normal operation of electrical equipment. Existing modulation controllers using algorithms such as SVM (Space Vector Machine), Fourier Transform, neural networks, and ESPRIT (Rotation Invariant Subspace) transformations suffer from high computational complexity and time consumption for harmonics and interharmonics, high noise in the noise subspace, and an inability to accurately estimate frequency, amplitude, and phase sequentially, failing to meet the real-time and synchronization requirements of smart grids. Currently, there is no controller for a clean and grid-friendly smart grid that meets real-time and synchronization requirements and provides comprehensive control from the input to the grid-connected phase-locked loop (PLL). Summary of the Invention

[0004] To address the aforementioned issues, this invention provides a one-stop intelligent megawatt box system based on TE-SVM modulation, along with its intelligent controller and control method. This addresses problems such as insufficient reactive power support capacity of the power grid, reduced voltage stability, and large fault voltage fluctuations resulting from the increasing proportion of photovoltaic new energy. It also addresses issues related to: PI control's inability to independently control positive and negative sequence currents, eliminate low and high harmonics, and its slow response speed and low capability; the failure of existing photovoltaic power generation system controllers to manage all voltage, current, phase, amplitude, and power factors from the input to the phase-locked loop in PLL phase-locked loop controllers; the inability of existing photovoltaic power generation system controllers to track the resonant frequency offset of LCL inverters using a current-open single-loop control strategy; the presence of resonant spikes at the resonant frequency of LCL filters that introduce harmonics and affect power grid quality; the low inverter efficiency of existing inverters; and the inability of existing photovoltaic power generation system controllers to accurately estimate frequency, amplitude, and phase, resulting in photovoltaic inverters failing to meet the real-time synchronization requirements of the smart grid.

[0005] The technical solution adopted in this invention is an intelligent controller for a one-stop intelligent megawatt box system based on TE-SVM modulation, comprising:

[0006] The MPPT controller is used to track the maximum power of the DC / DC converter and outputs a positive-sequence DC reference voltage U. ref + and DC reference current

[0007] The positive and negative sequence voltage decomposition module is used to convert the three-phase detection voltage V on the inverter grid side into positive and negative sequence voltages. a V b V c Decomposed into positive sequence three-phase voltage V a +、V b +、V c + and negative sequence three-phase voltage V a -、V b -、V c -;

[0008] A phase-locked loop (PLL) is used to adjust the input positive-sequence three-phase voltage V. a +、V b +、V c +, gives the voltage initiation angle θ and frequency f;

[0009] The current correction module is used to adjust the three-phase standard current I′. a 、I′ b 、I′ c Inverter-side inductor L and LCL filter f Three-phase detection current I at the location a I b I c C for LCL filters f With R f The three-phase average current I output at the component aavg I bavg I cavg Make corrections;

[0010] The first 3S / 2R conversion module is used to convert the input three-phase detection current I. a I b I c Perform a 3S / 2R conversion to output the positive-sequence actual active current I′. d+ Positive sequence actual reactive current I′ q+ Negative sequence actual active current I′ d- Negative sequence actual reactive current I′ q- ;

[0011] The positive and negative sequence theory active power reference current transformation module is used to transform the three-phase voltage V at the input grid connection point.ga V gb V gc and standard three-phase voltage V a ′、V b ′、V c The comparison is performed, and the theoretical active reference current is output using PI control based on the comparison results. Positive sequence theory active reference current Negative sequence theory active reference current

[0012] The positive and negative sequence theoretical reactive power reference current conversion module is used to convert the input theoretical active power reference current. And use the formula The theoretical reactive reference current is obtained by reverse calculation. Then the DC reference current and theoretical reactive reference current Compare and output the positive-sequence theoretical reactive reference current. Negative sequence theory reactive reference current

[0013] A two-phase positive sequence static voltage converter module is used to convert the input three-phase standard voltage V... a ′、V b ′、V c ′, Output of the current correction module, Voltage start angle θ, Positive sequence three-phase voltage V a +、V b +、V c +, DC bus capacitor voltage U bus Positive sequence DC reference voltage U ref +, Photovoltaic array output current I pv The average current I output by the entire DC system of the photovoltaic array pvavg Positive and negative sequence theory active reference current Positive and negative sequence actual active current I′ d+ 、I′ d- The transformation yields the two-phase positive-sequence static voltage U. α +、U β +;

[0014] A two-phase negative sequence static voltage converter module is used to convert the input three-phase standard voltage V. a ′、V b ′、V c ′, Output of the current correction module, Voltage start angle θ, Negative sequence three-phase voltage V a -、V b -、V c - Positive sequence reactive DC reference current I qref+, Positive and negative sequence theoretical reactive reference current Positive and negative sequence actual reactive current I′ q+ 、I′ q- The transformation yields the two-phase negative sequence static voltage U. α -、U β -;

[0015] The TE-SVM waveform generation module estimates the frequency of the smart grid based on the TLS-ESPRIT algorithm, utilizing the two-phase positive-sequence static voltage U. α +、U β + and two-phase negative sequence static voltage U α -、U β - Synthesize a three-phase reference voltage, using the grid frequency output by the phase-locked loop or the smart grid frequency solved by the TLS-ESPRIT algorithm as the transmission frequency, and combine it with the synthesized three-phase reference voltage to transmit the waveform and control the inverter to invert.

[0016] Furthermore, the current correction module includes:

[0017] The first comparator of the current correction module is used to compare the C of the LCL filter. f With R f The three-phase average current I at the component aavg I bavg I cavg Inverter-side inductor L with LCL filter f The three-phase current I at the location a I b I c The data is aggregated, and errors are compared.

[0018] A proportional controller is used to proportionally control the output of the first comparator;

[0019] The second comparator in the current correction module is used to compare the output of the proportional controller with the three-phase standard current I. a ′、I b ′、I c Perform error comparison;

[0020] The two-phase positive sequence static voltage conversion module includes:

[0021] The positive-sequence active and reactive current conversion module is used to convert the output of the current correction module to obtain the positive-sequence theoretical active current I. d + and positive sequence theory reactive current I q +;

[0022] The positive sequence voltage conversion module is used to convert the input three-phase standard voltage V′ a V′ b V′ cThe positive-sequence active voltage V is obtained by performing coordinate transformation and filtering. d + and positive sequence reactive voltage V q +;

[0023] The first positive-sequence active power reference current conversion module is used to convert the input DC capacitor voltage U bus Positive sequence DC reference voltage U ref + Perform coordinate transformation and PI control to obtain the first positive sequence active DC reference current I. dref1+ ;

[0024] The second positive-sequence active power reference current conversion module is used to convert the input photovoltaic array output current I. pv The average current I output by the entire DC system of the photovoltaic array pvavg By comparing and controlling the PI controller, the second positive-sequence active DC reference current I is obtained. dref2+ ;

[0025] The positive-sequence third comparator is used for the first positive-sequence active DC reference current I. dref1+ Second positive sequence active DC reference current I dref2+ Positive sequence theory active current I d + Positive sequence theoretical active reference current and the positive sequence actual active current I′ d+ The data is aggregated, and errors are compared.

[0026] The third PI controller is used to perform proportional-integral control on the output current of the positive-sequence third comparator, and outputs a positive-sequence active DC reference voltage U. d +;

[0027] The fourth positive-sequence comparator is used for the positive-sequence reactive DC reference current I. qref +、Positive sequence theoretical reactive current I q + Positive sequence theoretical reactive reference current and positive sequence actual reactive current I′ q+ The data is aggregated, and errors are compared.

[0028] The fourth PI controller is used to perform proportional-integral control on the output current of the positive-sequence fourth comparator, and outputs a positive-sequence reactive DC reference voltage U. q +;

[0029] The positive-sequence low-voltage ride-through control module detects voltage dips at the grid connection point and performs low-voltage ride-through control when a voltage dip occurs. It controls the inputs of the third and fourth PI controllers, thereby controlling the generation of the positive-sequence reactive DC reference voltage U at different times. q +, injecting reactive power into the grid, so that photovoltaic power generation can operate without disconnecting from the grid;

[0030] The first cross-coupler ±ωL is used to couple the positive-sequence theoretical active current I. d + and the reactive current I according to positive sequence theory q + Perform cross-coupling to cancel the positive-sequence theoretical active current I. d + and the reactive current I according to positive sequence theory q The coupling term + causes the d-axis component to be affected by I. d The effect of + causes the q-axis component to be affected by I. q The function of +;

[0031] The fifth positive-sequence comparator is used for the positive-sequence active DC reference voltage U. d + Positive sequence active voltage V d The active power outputs of the + and the first cross-coupler ±ωL are converged and compared for error.

[0032] The sixth positive-sequence comparator is used for the positive-sequence reactive DC reference voltage U. q + Positive sequence reactive voltage V q + and the reactive output of the first cross coupler ±ωL are aggregated and compared for error;

[0033] The first 2R / 2S coordinate transformation module is used to perform 2R / 2S coordinate transformation on the outputs of the positive-sequence fifth and sixth comparators based on the input voltage starting angle θ, to obtain the two-phase positive-sequence static voltage U. α +、U β +.

[0034] Furthermore, the positive-sequence active-reactive current conversion module includes:

[0035] The second 3S / 2R transformation module is used to perform a 3S / 2R coordinate transformation on the output of the current correction module based on the input voltage starting angle θ, and output the positive-sequence theoretical active current I. d + and positive sequence theory reactive current I q +;

[0036] The first low-pass filter, LPF, is used to filter the positive-sequence theoretical active current I. d + and positive sequence theory reactive current I q Perform low-pass filtering to remove high-frequency components and retain low-frequency components;

[0037] The first bandpass filter (BPF) is used to bandpass filter the output of the first low-pass filter (LPF), filtering out noise outside the bandwidth and outputting a clean, positive-sequence theoretical active current I. d + and positive sequence theory reactive current I q +;

[0038] The positive sequence voltage conversion module includes:

[0039] The third 3S / 2R conversion module is used to convert the input three-phase standard voltage V based on the input voltage start angle θ. a ′、V b ′、V c Perform a 3S / 2R coordinate transformation to output the positive-sequence active voltage V. d + and positive sequence reactive voltage V q +;

[0040] The second low-pass filter, LPF, is used to filter the positive-sequence active voltage V. d + and positive sequence reactive voltage V q Perform low-pass filtering to remove high-frequency components and retain low-frequency components;

[0041] The second bandpass filter (BPF) is used to bandpass filter the output voltage of the second low-pass filter (LPF), filtering out noise outside the bandwidth and outputting a clean positive-sequence active voltage V. d + and positive sequence reactive voltage V q +;

[0042] The first positive-sequence active power reference current transformation module includes:

[0043] The first comparator in the positive sequence is used for the DC capacitor voltage U. bus With positive sequence DC reference voltage U ref +Convergence, and error comparison;

[0044] The fourth 3S / 2R conversion module is used to perform 3S / 2R coordinate transformation on the output of the positive sequence first comparator to remove AC harmonic components from the DC voltage.

[0045] The first PI controller is used to perform proportional-integral control on the output voltage of the fourth 3S / 2R converter module, and outputs the first positive-sequence active DC reference current I. dref1+ ;

[0046] The second positive-sequence active power reference current transformation module includes:

[0047] The positive sequence second comparator is used for the photovoltaic array output current I. pv The average current I output by the entire DC system of the photovoltaic array pvavg The data is aggregated, and errors are compared.

[0048] The second PI controller is used to perform proportional-integral control on the output current of the positive-sequence second comparator, and outputs the second positive-sequence active DC reference current I. dref2+ .

[0049] Furthermore, the positive-sequence low-voltage ride-through control module includes:

[0050] The first low-voltage ride-through module is used to determine the input three-phase voltage V.a V b V c Detect whether a voltage drop occurs at the grid connection point, perform droop control, and output the root mean square droop voltage.

[0051] The first root mean square detection module performs root mean square detection on the output of the first low voltage ride-through module;

[0052] The reference power calculation module calculates the instantaneous values ​​of fundamental active power and fundamental reactive power, and compares these values ​​with standard active and reactive power, as well as the actual power at the smart grid connection point, to obtain the reference power P. * ;

[0053] The third 2R / 2S coordinate transformation module is used to transform the positive sequence active voltage V. d + and positive sequence reactive voltage V q + Perform a 2R / 2S coordinate transformation to obtain the negative-sequence and positive-sequence two-phase static voltage U a U B ;

[0054] The first reference current calculation module is used to calculate the reference current based on the reference power P. * Two-phase static voltage U a U B Calculate the positive sequence reference current

[0055] The first voltage and current calculation module is used to calculate the positive-sequence two-phase static voltage U. a U B and positive sequence reference current Combining formulas and Calculate the grid connection point voltage U N and total current I total ;

[0056] The first voltage drop determination module, when a low-voltage ride-through occurs, determines the voltage drop ΔU based on the result of the first root mean square (RMS) detection module. When a voltage droop RMS exists, it compares the voltage at the grid connection point during the low-voltage ride-through with the grid connection point voltage U. N The voltage drop ΔU is obtained by comparison; when there is no root mean square voltage droop, that is, the voltage at the grid connection point during low voltage ride-through when a voltage drop occurs, it is compared with the grid connection point voltage U. N When they are equal, it indicates that zero-voltage ride-through has occurred. At this time, the three-phase average voltage V output by the inverter is used. iava V iavb V iavc With grid connection point voltage U N The voltage drop ΔU is obtained by comparison;

[0057] The first low-voltage ride-through control module sets the positive-sequence active power to 0 when a low-voltage ride-through occurs, i.e., the positive-sequence theoretical active power reference current. Positive sequence theory active current I d+ Positive sequence actual active current I' d+ The power factor is set to 1, and the positive sequence reactive power reference current I is output with a power factor of 1. qref+ Low-voltage ride-through control is performed based on the voltage drop ΔU; then, the positive-sequence theoretical reactive power reference current is used. Positive sequence theory reactive current I q+ Positive sequence actual reactive current I' q+ I qref+ The maximum difference Δi was obtained by comparison. q+ The maximum difference Δi q+ As the initial suitable current I rective The input to the fourth PI controller generates positive sequence reactive voltage U. q+ For reactive power compensation, suitable for current I rective With total current I total The ratio gradually increases to 20%, and the voltage drop ΔU and voltage U N The ratio reaches 10%; positive sequence theoretical active reference current Positive sequence theory active current I d+ Positive sequence actual active current I' d+ First positive sequence active DC reference current I dref1+ Second positive sequence active DC reference current I dref2+ The maximum difference Δi was obtained by comparison. d+ The maximum difference Δi d+ The third PI controller generates a positive-sequence active voltage U. d+ The maximum difference Δi d+ The maximum difference Δi q+ Synthesized as a suitable current I rectiv Voltage drop ΔU and voltage U N The ratio gradually increases from 10% to 20%, reaching the maximum difference Δi. d+ The maximum difference Δi q+ With continuous injection, the current ratio I rective / I total Gradually increasing from 20% to 45%, the inverter operates continuously for 1 second, and the power factor starts to decrease from 1, ΔU / U N Gradually increase to 50%, suitable for current I rective Reaching I from 0 within 4 seconds total The power factor drops to 0, and the positive sequence reactive current Δi q+ The value is 0, indicating that positive-sequence active power is being injected into the power grid normally.

[0058] Furthermore, the two-phase negative sequence static voltage conversion module includes:

[0059] The voltage initial phase angle determination module is used to determine the voltage initial angle based on the input voltage starting angle θ and the negative sequence three-phase voltage V. a -、V b -、V c -, convert to obtain the initial phase angle of the voltage

[0060] The negative-sequence active and reactive current conversion module is used to convert the output of the current correction module to obtain the negative-sequence theoretical active current I. d - and negative sequence theory reactive current I q -;

[0061] The negative sequence voltage conversion module is used to convert the input three-phase standard voltage V a ′、V b ′、V c The conversion is performed to obtain the negative sequence active voltage V. d - and negative sequence reactive voltage V q -;

[0062] The fifth PI controller is used to control the negative-sequence theoretical active current I. d - Negative sequence actual active current I′ d- and the active reference current of negative sequence theory Perform PI control to output negative-sequence active DC reference voltage U d -;

[0063] The first negative-sequence comparator is used for the negative-sequence theoretical reactive current I. q - Negative sequence reactive DC reference current I qref - Negative sequence actual reactive current I′ q- and negative sequence theory reactive reference current The data is aggregated, and errors are compared.

[0064] The sixth PI controller is used to perform PI control on the output current of the negative-sequence first comparator, and outputs a negative-sequence reactive DC reference voltage U. q -;

[0065] The negative-sequence low-voltage ride-through control module is used to detect whether a voltage drop occurs at the grid connection point and to perform low-voltage ride-through control when a voltage drop occurs. It controls the inputs of the fifth and sixth PI controllers, thereby controlling the generation of the negative-sequence active DC reference voltage U at different times. q - Reactive power is injected into the grid, enabling photovoltaic power generation to operate without disconnecting from the grid;

[0066] The second cross-coupler ±ωL is used to control the negative-sequence theoretical active current I. d -Reactive current I according to negative sequence theoryq - Perform cross-coupling to cancel the negative-sequence theoretical active current I. d -Reactive current I according to negative sequence theory q - The coupling term causes the d-axis component to be affected by I d The effect of - on the q-axis component is influenced by I. q The function of -;

[0067] The negative-sequence second comparator is used for the negative-sequence active DC reference voltage U. d - Negative sequence active voltage V d - The active power output of the second cross-coupler ±ωL is aggregated for error comparison;

[0068] The negative-sequence third comparator is used for the negative-sequence reactive DC reference voltage U. q - Negative sequence reactive voltage V q - and the reactive power output of the second cross coupler ±ωL is aggregated and compared for error;

[0069] The second 2R / 2S coordinate transformation module is used to transform the voltage starting angle θ and the voltage initial phase angle. Performing a 2R / 2S coordinate transformation on the outputs of the negative-sequence second and third comparators yields the two-phase negative-sequence static voltage U. α -、U β -;

[0070] The TE-SVM waveform transmission module includes:

[0071] The TLS-ESPRIT frequency estimation module is used to estimate the frequency of the smart grid based on the TLS-ESPRIT algorithm.

[0072] The SVM waveform generation module is used to generate waveforms based on the two-phase positive sequence static voltage U. α +、U β + and two-phase negative sequence static voltage U α -、U β - Synthetic three-phase reference voltage It transmits waves based on the grid frequency output by the phase-locked loop or the smart grid frequency estimated by the TLS-ESPRIT frequency estimation module;

[0073] The gate controller is used to control each switching module of the inverter to turn on or off based on the vector signal sent by the SVM waveform generation module.

[0074] Furthermore, the voltage initial phase angle determination module includes:

[0075] The fifth 3S / 2R conversion module is used to convert the input negative sequence three-phase voltage V based on the input voltage start angle θ. a -、V b -、V c- Perform a 3S / 2R coordinate transformation to obtain the active voltage V. d and reactive voltage V q ;

[0076] The initial phase angle calculation module is used to calculate the initial phase angle based on the active voltage V. d and reactive voltage V q The initial phase angle of the voltage was calculated.

[0077] The negative-sequence active and reactive current conversion module includes:

[0078] The sixth 3S / 2R conversion module is used to convert the voltage starting angle θ and the voltage initial phase angle. Perform a 3S / 2R coordinate transformation on the output current of the current correction module to output the negative sequence active current I. d - and negative sequence reactive current I q -;

[0079] The third low-pass filter, LPF, is used to filter the negative-sequence active current I. d - and negative sequence reactive current I q - Perform low-pass filtering to remove high-frequency components and retain low-frequency components;

[0080] The third bandpass filter (BPF) is used to bandpass filter the output current of the third low-pass filter (LPF), filtering out noise outside the bandwidth and outputting a clean negative-sequence active current I. d - and negative sequence reactive current I q -;

[0081] The negative sequence voltage conversion module includes:

[0082] The seventh 3S / 2R conversion module is used to convert the voltage starting angle θ and the voltage initial phase angle. For the input three-phase standard voltage V a ′、V b ′、V c Perform a 3S / 2R coordinate transformation to output negative sequence active voltage V. d - and negative sequence reactive voltage V q -;

[0083] The fourth low-pass filter, LPF, is used to filter the negative-sequence active voltage V. d - and negative sequence reactive voltage V q - Perform low-pass filtering to remove high-frequency components and retain low-frequency components;

[0084] The fourth bandpass filter (BPF) is used to bandpass filter the output voltage of the fourth low-pass filter (LPF), filtering out noise outside the bandwidth and outputting a clean negative-sequence active voltage V. d - and negative sequence reactive voltage V q-;

[0085] The negative sequence low voltage ride-through control module includes:

[0086] The second low-voltage ride-through module is used to determine the input negative-sequence three-phase voltage V. a -、V b -、V c - Detect whether a voltage drop occurs at the grid connection point and perform droop control, outputting the root mean square droop voltage;

[0087] The second root mean square detection module is used to perform root mean square detection on the output of the second low voltage ride-through module.

[0088] The third-order negative-sequence maximum current calculation module is used to calculate the positive-sequence reactive DC reference current I. qref +, Maximum current I max and voltage initial phase angle Calculate the third-order negative-sequence maximum current I qmax -;

[0089] The fourth 2R / 2S coordinate transformation module is used for the negative sequence active voltage V. d - and negative sequence reactive voltage V q - Perform a 2R / 2S coordinate transformation to obtain the negative sequence two-phase static voltage U. a U B ;

[0090] The second reference current calculation module is used to calculate the reference current based on the reference power P. * Negative sequence two-phase static voltage U a U B Calculate the negative sequence reference current

[0091] The second voltage and current calculation module is used to calculate the negative sequence two-phase static voltage U. a U B and negative sequence reference current Combining formulas and Calculate the grid connection point voltage U N and total current I total ;

[0092] The second voltage drop determination module, when a low-voltage ride-through occurs, determines the voltage drop ΔU based on the result of the second root mean square (RMS) detection module. When a voltage droop RMS exists, it compares the voltage at the grid connection point during the low-voltage ride-through with the grid connection point voltage U. N The voltage drop ΔU is obtained by comparison; when there is no root mean square voltage droop, that is, the voltage at the grid connection point during low voltage ride-through when a voltage drop occurs, it is compared with the grid connection point voltage U. NWhen they are equal, it indicates that zero-voltage ride-through has occurred. At this time, the three-phase average voltage V output by the inverter is used. iava V iavb V iavc With grid connection point voltage U N The voltage drop ΔU is obtained by comparison;

[0093] The second low-voltage ride-through control module performs low-voltage ride-through control based on the voltage drop ΔU when a low-voltage ride-through occurs, setting the negative-sequence reactive power to 0, i.e., the negative-sequence theoretical reactive power reference current. Negative sequence reactive current I q- Negative sequence actual reactive current I' q- Set to 0; power factor set to 1, low-voltage ride-through control based on voltage drop ΔU; then negative sequence theoretical active reference current. Negative sequence active current I d- Negative sequence actual active current I' d- The maximum difference Δi was obtained by comparison. d- The maximum difference Δi d- As the initial suitable current I rective The input is to the fifth PI controller, which generates a negative-sequence active voltage U. d- Suitable for current I rectiv With total current I total The ratio gradually increases to 20%, and the voltage drop ΔU and voltage U N The ratio begins to rise when it reaches 10%; negative sequence theoretical reactive reference current Negative sequence reactive current I q- Negative sequence actual reactive current I' q- Negative sequence reactive reference current I qref- The maximum difference Δi was obtained by comparison. q- The maximum difference Δi q- The input is to the sixth PI controller, which generates a negative-sequence reactive voltage U. q- The maximum difference Δi q- The maximum difference Δi d- Synthesized as a suitable current I rectiv Voltage drop ΔU and voltage U N The ratio gradually increases from 10% to 20%, reaching the maximum difference Δi. q- The maximum difference Δi d- With continuous injection, the current ratio I rective / I total Gradually increasing from 20% to 45%, the inverter operates continuously for 1 second, and the power factor starts to decrease from 1, ΔU / U N Gradually increase to 50%, suitable for current I rective Reaching I from 0 within 4 seconds totalWhen the power factor drops to 0, the negative sequence active current injects negative sequence active power into the grid normally, while the negative sequence reactive voltage of the negative sequence reactive power is limited.

[0094] Another technical solution adopted in this embodiment of the invention is a control method for the friendly access of a one-stop intelligent megawatt box system based on TE-SVM modulation to the smart grid. This method uses the aforementioned intelligent controller of the one-stop intelligent megawatt box system based on TE-SVM modulation and proceeds according to the following steps:

[0095] Step S1: Receive the actual active and reactive power at the smart grid connection point, and the three-phase voltage V output by the inverter. a V b V c The three-phase voltage V at the grid connection point ga V gb V gc Three-phase average voltage V iava V iavb V iavc Three-phase current I a I b I c Three-phase average current I aavg I bavg I cavg DC bus capacitor voltage U bus Photovoltaic array output current I pv Average current I pvavg It employs an MPPT controller to track the maximum power of the DC / DC converter and outputs a positive-sequence DC reference voltage U. ref + and DC reference current

[0096] Step S2: Calculate the standard active power and reactive power, and the instantaneous values ​​of active power and reactive power at the smart grid connection point;

[0097] Step S3: Determine whether the actual active power and reactive power at the smart grid connection point correspond to the calculated instantaneous values ​​of active power and reactive power at the smart grid connection point, as well as the standard active power and reactive power; and determine whether the frequency output by the phase-locked loop is within the range of 50±0.1Hz.

[0098] Step S4: When the actual active power and reactive power at the smart grid connection point correspond to the calculated instantaneous values ​​of active power and reactive power at the smart grid connection point, as well as the standard active power and reactive power, and the frequency output by the phase-locked loop is within the range of 50±0.1Hz, the frequency output by the phase-locked loop is used as the transmission frequency of the SVM transmission module; otherwise, the frequency search of the smart grid is performed using the TLS-ESPRIT frequency estimation module, and the searched frequency is used as the transmission frequency of the SVM transmission module.

[0099] Step S5: Calculate the three-phase standard voltage V based on the voltage and current signals received in step S1. a ′、V b ′、V c ′, Three-phase standard current I a ′、I b ′、I c ′, standard active power and reactive power, instantaneous active power and instantaneous reactive power at the smart grid connection point, and two-phase positive sequence static voltage U obtained using a two-phase positive sequence static voltage conversion module and a two-phase negative sequence static voltage conversion module. α +、U β + and the two-phase negative sequence static voltage U α -、U β -; Using the SVM waveform generation module based on the two-phase positive sequence static voltage U α +、U β + and the two-phase negative sequence static voltage U α -、U β - A reference voltage is synthesized, and then an SVM waveform is generated based on the waveform frequency and the reference voltage. The equalizing gate controller uses SVPWM modulation to control each switching module of the inverter to turn on or off according to the vector signal generated by the SVM waveform.

[0100] Furthermore, in step S5:

[0101] Calculate the three-phase standard voltage V according to formula (1). a ′、V b ′、V c ′:

[0102]

[0103] Among them, V p It is the peak value of the positive sequence voltage, V n It is the negative sequence voltage peak value. It is the initial phase angle of the positive sequence voltage. ω is the initial phase angle of the negative sequence voltage; ω is the angular frequency of the fundamental voltage.

[0104] Three-phase standard current I a ′、I b ′、Ic Calculate according to formula (2):

[0105]

[0106] Among them, I p It is the peak value of the positive sequence current, I n It is the peak value of the negative sequence current, θ p It is the starting angle of the positive sequence current relative to the positive sequence voltage, θ n It is the starting angle of the negative sequence current relative to the negative sequence voltage;

[0107] In step S5, the positive and negative sequence impedances are calculated when the first low-voltage ride-through module and the second low-voltage ride-through module perform droop control, wherein:

[0108] Positive sequence impedance Z P (S) Calculated according to formula (3):

[0109]

[0110] Among them, K m V is the inverter voltage gain. dc H is the voltage difference across the DC bus capacitor. i (s-j2πf1) is the closed-loop transfer function of the inner-loop PI controller, i.e., the first PI controller, T PLL (s-j2πf1) is the closed-loop transfer function of the phase-locked loop, f1 is the fundamental frequency, and K is the fundamental frequency. d K is the gain of the weighting function. f G is the integral proportional parameter. i (s) is the equivalent transfer function of the current filter composed of the first low-pass filter LPF and the first band-pass filter BPF, L f C is the inductance value of the inverter-side inductor of the LCL filter, and C1 is the DC bus capacitance value; G v (s) is the equivalent transfer function of the voltage filter composed of the second low-pass filter LPF and the second band-pass filter BPF, where s represents the complex frequency domain. I1 is the initial phase angle of the fundamental current, V1 is the peak value of the fundamental current, and V1 is the peak value of the grid voltage.

[0111] Negative sequence impedance Z n (S) Calculated according to formula (4):

[0112]

[0113] Among them, H i (s+j2πf1) is the closed-loop transfer function of the inner-loop PI controller, i.e., the first PI controller, G. i(s) is the equivalent transfer function of the current filter composed of the first low-pass filter LPF and the first band-pass filter BPF, G v (s) is the equivalent transfer function of the voltage filter composed of the fourth low-pass filter LPF and the fourth band-pass filter BPF;

[0114] The standard active power and standard reactive power are calculated according to formulas (7) to (8):

[0115]

[0116] Where P(t) is the standard active power, Q(t) is the standard reactive power, and V... α V β Let I be the corresponding voltage in the αβ stationary reference coordinate system. α I β Let θ1 be the corresponding current in the αβ stationary reference coordinate system, θ2 be the starting angle of the actual grid current relative to the voltage, and θ3 be the starting angle of the phase-locked loop output.

[0117] The instantaneous values ​​of active power and reactive power at the intelligent grid connection point are calculated according to formula (9):

[0118]

[0119] Where P0(t) is the instantaneous value of the fundamental active power, and Q0(t) is the instantaneous value of the fundamental reactive power; V p It is the peak value of the positive sequence voltage, V n It is the negative sequence voltage peak value; I p It is the peak value of the positive sequence current, I n It is the peak value of the negative sequence current, θ p It is the starting angle of the positive sequence current relative to the positive sequence voltage, θ n It is the starting angle of the negative sequence current relative to the negative sequence voltage;

[0120] Step S5 synthesizes the vector reference voltage according to the following formula.

[0121]

[0122] Another technical solution adopted in this embodiment of the invention is a one-stop intelligent megawatt box system based on TE-SVM modulation, comprising:

[0123] Photovoltaic arrays are used to generate solar power and output electrical energy.

[0124] At least two inverters are integrated into a megawatt box, which is used to sequentially combine, step down and invert the DC output of the photovoltaic array, and output three-phase AC power.

[0125] At least two SVM controllers are connected one-to-one with the inverters in all inverter integrated megawatt boxes. Each SVM controller performs inverter control on the inverters connected to it based on TE-SVM modulation.

[0126] The power switching module is used to automatically switch all inverter integrated megawatt boxes connected to it, so that only one inverter integrated megawatt box supplies power to the smart grid at any given time.

[0127] The measurement and control power cabinet is used to perform master-slave competition control on all inverter integrated megawatt boxes based on the frequency, amplitude, and phase of the three-phase AC power output from the inverters in all inverter integrated megawatt boxes, as well as the temperature detection results of each switching module of all inverters. It uses the first-ranked competition standard to select the best among all inverter integrated megawatt boxes in real time, and designates the currently selected best as the master inverter, with the remaining inverter integrated megawatt boxes as slave inverters. It controls the dual power supply switching device connected to the master inverter to work and automatically switch, so that the master inverter can supply power to the smart grid.

[0128] A step-up transformer is used to step up the three-phase AC power output from the dual-power switching device connected to the megawatt box integrated with the main inverter, and then input the stepped-up three-phase AC power into the smart grid.

[0129] in:

[0130] The power switching module consists of at least one dual power switching device. Each dual power switching device is connected to two inverter integrated megawatt boxes. When each dual power switching device is working, it automatically switches between the two inverter integrated megawatt boxes connected to it according to the control signal.

[0131] Furthermore, the one-stop smart megawatt box system based on TE-SVM modulation also includes a group of smart energy meters installed at the common point of the smart grid;

[0132] Each of the aforementioned inverter integrated megawatt enclosures includes:

[0133] Combiner box: The combiner box is used to combine the output of the photovoltaic array. Each connection line between the combiner box and the photovoltaic array is equipped with a first circuit breaker.

[0134] DC / DC converter module, the DC / DC converter module is used to step down the DC power output from the combiner box;

[0135] DC bus capacitor: The DC bus capacitor is used to filter the DC output of the DC / DC converter module before it is used as a DC power supply.

[0136] A three-bridge inverter is used to convert the buck-converted DC power to DC / AC power and output three-phase AC power.

[0137] LCL filters are used to filter the three-phase AC output of a three-bridge inverter.

[0138] The output of the SVM controller is connected to the input of the measurement and control power cabinet via a pairing cloud manager.

[0139] Each inverter integrated megawatt box is equipped with a second circuit breaker on the grid side. The three-phase line of the output terminal of the second circuit breaker is split into two paths. One of the three-phase lines is connected to the third circuit breaker, which is connected to the external measurement and control power supply cabinet. The other three-phase line of the output terminal of the second circuit breaker is connected to the corresponding dual power supply switching device.

[0140] The beneficial effects of this invention are:

[0141] In terms of grid interaction, the vector control coordinate transformation technology of the three-phase system is used, taking into account both low-pass and band-pass filtering characteristics, saving the design of additional filters. At the same time, the all-factor control closed-loop phase-locking can directly lock the mains phase and frequency, perfectly realizing grid tracking and coordination, laying the foundation for the replacement of traditional non-renewable energy power plants with photovoltaic power plants. The positive-sequence and negative-sequence currents are controlled separately through a dual-vector closed-loop system, and the outputs are finally synthesized in a two-phase stationary coordinate system. This allows the system to inject desired active or reactive current into the grid during grid dips (even when the voltage drops to 0), regulating the actual current and enabling the inverter to regulate the active and reactive power of the grid. This ensures continuous operation of photovoltaic power generation without disconnecting from the grid, automatically achieves low-voltage ride-through, and suppresses negative-sequence voltage, enabling automatic reactive power compensation to the grid and adaptive adjustment of unbalanced voltage. The positive-sequence and negative-sequence currents are controlled independently, and multiple coordinate transformations, P-control, PI control, and LPF+BPF filtering are employed to effectively eliminate low-order and high-order harmonics. The phase-locked loop output is controlled in five separate paths. All factors, including voltage, current, phase, amplitude, and power, from the input to the phase-locked loop (PLL) terminal are controlled. The LCL inverter's resonant frequency offset is adjusted using TLS-ESPRIT frequency estimation, improving the real-time and synchronization requirements for frequency and amplitude-phase-friendly smart grid integration, increasing inverter efficiency, and reducing power consumption. This enables the one-stop smart megawatt box system to achieve a real-time and synchronization rate of 93.5% when connected to the smart grid, with a conversion efficiency ≥99.9%. It eliminates resonant frequency offset and resonant spikes under unbalanced faults, reduces unexplained switching losses by 90%, lowers the output current harmonic THD to below 2.23, improves DC bus voltage utilization by 5% compared to the most advanced existing technology, has a large modulation ratio, good dynamic performance, and achieves pulse-level synchronization, enabling highly efficient intelligent interactive operation with the smart grid. This effectively solves the problems of insufficient reactive power support capacity of the power grid, reduced voltage stability, and large fault voltage fluctuations after the increase in the proportion of photovoltaic new energy. It also addresses the problems of PI control being unable to independently control positive and negative sequence currents, compensate for low and high harmonics, and having slow response speed and low capability. Furthermore, it addresses the problems of existing photovoltaic power generation system controllers' PLL phase-locked loops not controlling all voltage, current, phase, amplitude, power, and other factors from the input to the phase-locked loop. It also addresses the problems of existing photovoltaic power generation system controllers being unable to track the resonant frequency deviation of LCL inverters using current open single-loop control strategies, the existence of resonant spikes at the resonant frequency of LCL filters that introduce harmonics and affect the power quality of the power grid, the low inverter efficiency of existing inverters, and the inability of existing photovoltaic power generation system controllers to accurately estimate frequency, amplitude, and phase, resulting in photovoltaic inverters not meeting the real-time synchronization requirements of the smart grid. Attached Figure Description

[0142] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0143] Figure 1 This is a structural block diagram of a one-stop intelligent megawatt box system based on TE-SVM modulation according to an embodiment of the present invention.

[0144] Figure 2 This is a schematic diagram of the specific structure of a one-stop intelligent megawatt box system (single inverter and single controller) based on TE-SVM modulation according to an embodiment of the present invention.

[0145] Figure 3 This is a schematic diagram of the specific structure of the intelligent controller for the one-stop intelligent megawatt box system (single inverter and single controller) based on TE-SVM modulation, which is connected to the smart grid in a friendly manner according to an embodiment of the present invention.

[0146] Figure 4 yes Figure 3 Simplified positive-sequence and negative-sequence circuit diagrams.

[0147] Figure 5 This is a schematic diagram of the connection between the TE-SVM wave generation principle and the equalizing gate controller in an embodiment of the present invention.

[0148] Figure 6 This is a diagram showing the spatial sector of the SVM waveform generation module in an embodiment of the present invention, and the correspondence between the upper switch, the lower switch, and the vector frequency.

[0149] Figure 7 This is an RMS current waveform of the dq axis before PI modulation, after TE-SVM modulation and synchronous rotating reference coordinate transformation.

[0150] Figure 8 This is a network measurement harmonic diagram after the SVM controller and the one-stop smart megawatt box based on TE-SVM modulation are connected to the smart grid in a friendly manner according to an embodiment of the present invention.

[0151] Figure 9 This is an inverter waveform diagram of the intelligent controller and the one-stop intelligent megawatt box based on TE-SVM modulation after being connected to the smart grid in a friendly manner according to an embodiment of the present invention.

[0152] Figure 10This is a power generation operation diagram when the voltage of the PLL (at PCC) drops to 0 after the intelligent controller and the one-stop intelligent megawatt box based on TE-SVM modulation are connected to the smart grid in a friendly manner according to an embodiment of the present invention. Among them, (a) is the current amplitude diagram of the AC grid side of the inverter, (b) is the voltage amplitude diagram of the DC bus side of the inverter, (c) is the reactive current amplitude diagram provided to the PCC, and (d) is the active power amplitude diagram of the inverter.

[0153] Figure 11 This is an LVRT waveform diagram of a photovoltaic grid-connected inverter when the intelligent controller and the one-stop intelligent megawatt box based on TE-SVM modulation are symmetrically connected to the smart grid according to an embodiment of the present invention. Detailed Implementation

[0154] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0155] Example 1

[0156] The one-stop intelligent megawatt box system based on TE-SVM modulation according to embodiments of the present invention, such as Figure 1 As shown, it includes:

[0157] Photovoltaic arrays are used to generate solar power and output electrical energy.

[0158] At least two inverters are integrated into a megawatt box, which is used to sequentially combine, step down and invert the DC output of the photovoltaic array, and output three-phase AC power.

[0159] At least two SVM controllers are connected one-to-one with the inverters in all inverter integrated megawatt boxes. Each SVM controller performs inverter control on the inverters connected to it based on TE-SVM modulation.

[0160] The power switching module is used to automatically switch all connected inverter integrated megawatt boxes, ensuring that only one inverter integrated megawatt box supplies power to the smart grid at any given time. Specifically:

[0161] The power switching module consists of at least one dual power switching device. Each dual power switching device is connected to two inverter integrated megawatt boxes. When each dual power switching device is working, it can automatically switch the two inverter integrated megawatt boxes connected to it according to the control signal.

[0162] The measurement and control power cabinet is used to perform master-slave competitive control on all inverter integrated megawatt boxes based on the frequency, amplitude, and phase (i.e., inverter effect) of the three-phase AC power output from the inverters in all inverter integrated megawatt boxes, as well as the temperature detection results of each switching module of all inverters (indicating whether the switching transistors of the switching modules are intact). It uses a competitive ranking standard to select the best inverter integrated megawatt box in real time, designating the currently selected best inverter as the master inverter, and the remaining inverter integrated megawatt boxes as slave inverters. It controls the dual power switching device connected to the master inverter to operate and automatically switch, enabling the master inverter to supply power to the smart grid. The slave inverters only supplement the master inverter in case of failure, etc. This solves the circulating current problem that occurs when multiple inverters supply power to the smart grid simultaneously, and addresses the instability and imbalance of power, operating voltage, and power of unhealthy photovoltaic cells and unhealthy IGBT / IGCT power switching modules.

[0163] A step-up transformer is used to step up the three-phase AC power output from the dual-power switching device connected to the megawatt box integrated with the main inverter, and then input the stepped-up three-phase AC power into the smart grid.

[0164] Furthermore, each of the TE-SVM modulation-based SVM controllers is connected to the control terminal of each switching module of the inverter connected thereto via a voltage equalization gate controller.

[0165] Furthermore, each of the aforementioned inverter integrated megawatt boxes includes:

[0166] Combiner box: The combiner box is used to combine the output of the photovoltaic array. Each connection line between the combiner box and the photovoltaic array is equipped with a first circuit breaker.

[0167] DC / DC converter module, the DC / DC converter module is used to step down the DC power output from the combiner box;

[0168] DC bus capacitor: The DC bus capacitor is used to filter the DC output of the DC / DC converter module before it is used as a DC power supply.

[0169] A three-bridge inverter is used to convert the buck-converted DC power to DC / AC power and output three-phase AC power.

[0170] LCL filters are used to filter the three-phase AC output of a three-bridge inverter.

[0171] Furthermore, the output of the SVM controller is connected to the input of the measurement and control power cabinet through a pairing cloud manager, so as to transmit various control parameter signals to the measurement and control power cabinet for bidirectional control.

[0172] Furthermore, the step-up transformer has lightning protection, short-circuit protection, and grounding protection functions.

[0173] Furthermore, each of the inverter integrated megawatt boxes is equipped with a second circuit breaker on the grid side. The three-phase line at the output of the second circuit breaker is split into two paths. One of the three-phase lines is connected to a third circuit breaker, which is connected to an external measurement and control power supply cabinet. The other three-phase line at the output of the second circuit breaker is connected to a corresponding dual power supply switching device.

[0174] Furthermore, the three-arm inverter consists of six switches. Composition, in which:

[0175] The switch and switch Form the first bridge arm, switch For the upper switch of the first bridge arm, the switch This is the lower switch for the first bridge arm;

[0176] The switch and switch Form the second bridge arm, switch For the upper switch of the second bridge arm, the switch This is the lower switch for the second bridge arm;

[0177] The switch and switch Form the third bridge arm, switch For the upper switch of the first bridge arm, the switch This is the lower switch for the third bridge arm.

[0178] Furthermore, the switch It is an IGBT / IGCT power switching module with undervoltage, overvoltage, voltage regulation, and temperature detection functions.

[0179] The one-stop intelligent megawatt box system based on TE-SVM modulation according to this embodiment of the invention further includes:

[0180] Smart meter sets are used to measure voltage, current, active power, and reactive power at the common point of the smart grid, i.e., the grid side of the dual-power switching device. A smart meter set includes:

[0181] The active power meter PJP1 is used to measure the actual active power, three-phase voltage (measured by the voltage sensor inside the active power meter PJP1), and three-phase current (measured by the current sensor inside the active power meter PJP1) at the input of the step-up transformer.

[0182] The PJQ1 reactive power meter is used to measure the actual reactive power, three-phase voltage (measured by the voltage sensor inside the PJQ1 reactive power meter), and three-phase current (measured by the current sensor inside the PJQ1 reactive power meter) at the input of the step-up transformer.

[0183] Furthermore, the output end of the measurement and control power supply cabinet is connected to an external Ethernet communication port.

[0184] Furthermore, the one-stop intelligent megawatt box system based on TE-SVM modulation also includes:

[0185] The intelligent cloud monitoring system for photovoltaic power plants is used to communicate with Ethernet, transmit information and control commands, and overcome the limitations of traditional manual inspections.

[0186] Example 2

[0187] The intelligent controller of the one-stop intelligent megawatt box system based on TE-SVM modulation in this embodiment of the invention, namely the SVM controller in Embodiment 1, is as follows: Figures 2-3 As shown, it includes:

[0188] The MPPT controller is used to track the maximum power of the DC / DC converter and outputs a positive-sequence DC reference voltage U. ref + and DC reference current

[0189] The positive and negative sequence voltage decomposition module is used to convert the three-phase detection voltage V provided by the voltage sensor on the inverter grid side into a single voltage. a V b V c Decomposed into positive sequence three-phase voltage V a +、V b +、V c + and negative sequence three-phase voltage V a -、V b -、V c -;

[0190] A phase-locked loop (PLL) is used to adjust the input positive-sequence three-phase voltage V. a +、V b +、V c +, gives the voltage initiation angle θ and frequency f;

[0191] The current correction module is used to adjust the three-phase standard current I. a ′、I b ′、I c Inverter-side inductor L of the ′ and LCL filter f The three-phase current I provided by the current sensor at the location a I b I c C for LCL filters f With Rf The three-phase average current I output from the current sensor at the component aavg I bavg I cavg The current correction module includes the following components:

[0192] The first comparator of the current correction module is used to compare the C of the LCL filter. f With R f The three-phase average current I provided by the current sensor at the component aavg I bavg I cavg Inverter-side inductor L with LCL filter f The three-phase current I provided by the current sensor at the location a I b I c The data is aggregated, and errors are compared.

[0193] A proportional controller is used to proportionally control the output of the first comparator of the current correction module.

[0194] The second comparator in the current correction module is used to compare the output of the proportional controller with the three-phase standard current I. a ′、I b ′、I c Error comparison is performed, and the error between the measured power and the calculated power of the smart meter group is converted into current adjustment and compensation;

[0195] The intelligent controller for the one-stop intelligent megawatt enclosure system based on TE-SVM modulation also includes:

[0196] The first 3S / 2R conversion module is used to convert the input three-phase detection current I. a I b I c ( Figure 2 The three-phase i(n+1) undergoes a 3S / 2R transformation to output the positive-sequence actual active current I′. d+ Positive sequence actual reactive current I′ q+ Negative sequence actual active current I′ d- Negative sequence actual reactive current I′ q- ;

[0197] The positive and negative sequence theory active power reference current transformation module is used to transform the three-phase voltage V at the input grid connection point. ga V gb V gc and standard three-phase voltage V a ′、V b ′、V c The comparison is performed, and the theoretical active reference current is output using PI control based on the comparison results. Positive sequence theory active reference current Negative sequence theory active reference current

[0198] The positive and negative sequence theoretical reactive power reference current conversion module is used to convert the input theoretical active power reference current. And use the formula The theoretical reactive reference current is obtained by reverse calculation. I dref+ The first positive sequence active reference current I dref1+ Second positive sequence active DC reference current I dref2+ The larger of the two, then the DC reference current. and theoretical reactive reference current Compare and output the positive-sequence theoretical reactive reference current. Negative sequence theory reactive reference current

[0199] A two-phase positive sequence static voltage converter module is used to convert the input three-phase standard voltage V... a ′、V b ′、V c ′, Output of the current correction module, Voltage start angle θ, Positive sequence three-phase voltage V a +、V b +、V c +, DC bus capacitor voltage U bus Positive sequence DC reference voltage U ref +, Photovoltaic array output current I pv The average current I output by the entire DC system of the photovoltaic array pvavg Positive and negative sequence theory active reference current Positive and negative sequence actual active current I′ d+ 、I′ d- The transformation yields the two-phase positive-sequence static voltage U. α +、U β The two-phase positive sequence static voltage conversion module includes:

[0200] The positive-sequence active and reactive current conversion module is used to convert the output of the current correction module to obtain the positive-sequence theoretical active current I. d + and positive sequence theory reactive current I q +, The positive-sequence active and reactive current conversion module includes:

[0201] The second 3S / 2R transformation module is used to perform a 3S / 2R coordinate transformation on the output of the current correction module based on the input voltage starting angle θ, and output the positive-sequence theoretical active current I. d + and positive sequence theory reactive current I q +;

[0202] The first low-pass filter, LPF, is used to filter the positive-sequence theoretical active current I. d + and positive sequence theory reactive current I q Perform low-pass filtering to remove high-frequency components and retain low-frequency components;

[0203] The first bandpass filter (BPF) is used to bandpass filter the output of the first low-pass filter (LPF), filtering out noise outside the bandwidth and outputting a clean, positive-sequence theoretical active current I. d + and positive sequence theory reactive current I q +.

[0204] The two-phase positive sequence static voltage converter module also includes:

[0205] The positive sequence voltage conversion module is used to convert the input three-phase standard voltage V a ′、V b ′、V c The positive-sequence active voltage V is obtained by performing coordinate transformation and filtering. d + and positive sequence reactive voltage V q +, The positive sequence voltage conversion module includes:

[0206] The third 3S / 2R conversion module is used to convert the input three-phase standard voltage V based on the input voltage start angle θ. a ′、V b ′、V c Perform a 3S / 2R coordinate transformation to output the positive-sequence active voltage V. d + and positive sequence reactive voltage V q +;

[0207] The second low-pass filter, LPF, is used to filter the positive-sequence active voltage V. d + and positive sequence reactive voltage V q Perform low-pass filtering to remove high-frequency components and retain low-frequency components;

[0208] The second bandpass filter (BPF) is used to bandpass filter the output voltage of the second low-pass filter (LPF), filtering out noise outside the bandwidth and outputting a clean positive-sequence active voltage V. d + and positive sequence reactive voltage V q +.

[0209] The two-phase positive sequence static voltage converter module also includes:

[0210] The first positive-sequence active power reference current conversion module is used to convert the input DC capacitor voltage U bus Positive sequence DC reference voltage U ref + Perform coordinate transformation and PI control to obtain the first positive sequence active DC reference current I. dref1+The first positive-sequence active power reference current transformation module includes:

[0211] The first comparator in the positive sequence is used for the DC capacitor voltage U. bus With positive sequence DC reference voltage U ref +Convergence, and error comparison;

[0212] The fourth 3S / 2R conversion module is used to perform 3S / 2R coordinate transformation on the output of the positive sequence first comparator to remove AC harmonic components from the DC voltage.

[0213] The first PI controller is used to perform proportional-integral control on the output voltage of the fourth 3S / 2R converter module, and outputs the first positive-sequence active DC reference current I. dref1+ .

[0214] The two-phase positive sequence static voltage converter module also includes:

[0215] The second positive-sequence active power reference current conversion module is used to convert the input photovoltaic array output current I. pv The average current I output by the entire DC system of the photovoltaic array pvavg By comparing and controlling the PI controller, the second positive-sequence active DC reference current I is obtained. dref2+ The second positive-sequence active power reference current transformation module includes:

[0216] The positive sequence second comparator is used for the photovoltaic array output current I. pv The average current I output by the entire DC system of the photovoltaic array pvavg The data is aggregated, and errors are compared.

[0217] The second PI controller is used to perform proportional-integral control on the output current of the positive-sequence second comparator, and outputs the second positive-sequence active DC reference current I. dref2+ .

[0218] The two-phase positive sequence static voltage converter module also includes:

[0219] The positive-sequence third comparator is used for the first positive-sequence active DC reference current I. dref1+ Second positive sequence active DC reference current I dref2+ Positive sequence theory active current I d + Positive sequence theoretical active reference current and the positive sequence actual active current I′ d+ The data is aggregated, and errors are compared.

[0220] The third PI controller is used to perform proportional-integral control on the output current of the positive-sequence third comparator, and outputs a positive-sequence active DC reference voltage U. d +;

[0221] The fourth positive-sequence comparator is used for the positive-sequence reactive DC reference current I. qref +、Positive sequence theoretical reactive current I q + Positive sequence theoretical reactive reference current and positive sequence actual reactive current I′ q+ The data is aggregated, and errors are compared.

[0222] The fourth PI controller is used to perform proportional-integral control on the output current of the positive-sequence fourth comparator, and outputs a positive-sequence reactive DC reference voltage U. q +.

[0223] The two-phase positive sequence static voltage converter module also includes:

[0224] The positive-sequence low-voltage ride-through control module detects voltage dips at the grid connection point and performs low-voltage ride-through control when a voltage dip occurs. It controls the inputs of the third and fourth PI controllers, thereby controlling the generation of the positive-sequence reactive DC reference voltage U at different times. q +, injecting reactive power into the grid to ensure photovoltaic power generation does not disconnect from the grid. The positive sequence low voltage ride-through control module includes:

[0225] The first low-voltage ride-through module is used to determine the input three-phase voltage V. a V b V c Detect whether a voltage drop occurs at the grid connection point, perform droop control, and output the root mean square droop voltage.

[0226] The first root mean square detection module performs root mean square detection on the output of the first low voltage ride-through module;

[0227] The reference power calculation module calculates the instantaneous values ​​of fundamental active power and fundamental reactive power, and compares these values ​​with standard active and reactive power, as well as the actual power at the smart grid connection point, to obtain the reference power P. * ;

[0228] The third 2R / 2S coordinate transformation module is used to transform the positive sequence active voltage V. d + and positive sequence reactive voltage V q + Perform a 2R / 2S coordinate transformation to obtain the negative-sequence and positive-sequence two-phase static voltage U a U B ;

[0229] The first reference current calculation module is used to calculate the reference current based on the reference power P. * Two-phase static voltage U a U B Calculate the positive sequence reference current

[0230] The first voltage and current calculation module is used to calculate the positive-sequence two-phase static voltage U. a U B and positive sequence reference current Combining formulas and Calculate the grid connection point voltage U N and total current I total ;

[0231] The first voltage drop determination module, when a low-voltage ride-through occurs, determines the voltage drop ΔU(ΔU(n+1)) based on the result of the first root mean square detection module. When a drooping root mean square exists, it compares the voltage at the grid connection point during the low-voltage ride-through with the grid connection point voltage U. N The voltage drop ΔU is obtained by comparison; when there is no root mean square voltage droop, that is, the voltage at the grid connection point during low voltage ride-through when a voltage drop occurs, it is compared with the grid connection point voltage U. N When they are equal, it indicates that zero-voltage ride-through has occurred. At this time, the three-phase average voltage V output by the inverter is used. iava V iavb V iavc With grid connection point voltage U N The voltage drop ΔU is obtained by comparison;

[0232] The first low-voltage ride-through control module sets the positive-sequence active power to 0 when a low-voltage ride-through occurs, i.e., the positive-sequence theoretical active power reference current. Positive sequence theory active current I d+ Positive sequence actual active current I' d+ The power factor is set to 1, and the positive sequence reactive power reference current I is output with a power factor of 1. qref+ Low-voltage ride-through control is performed based on the voltage drop ΔU; then, the reactive power reference current is obtained based on the positive sequence current theory. Positive sequence theory reactive current I q+ Positive sequence actual reactive current I' q+ I qref+ The maximum difference Δi was obtained by comparison. q+ The maximum difference Δi q+ As the initial suitable current I rective The input to the fourth PI controller generates positive sequence reactive voltage U. q+ For reactive power compensation, suitable for current I rective With total current I total The ratio gradually increases to 20%, and the voltage drop ΔU and voltage U N The ratio reaches 10%; positive sequence theoretical active reference current Positive sequence theory active current I d+ Positive sequence actual active current I' d+First positive sequence active DC reference current I dref1+ Second positive sequence active DC reference current I dref2+ The maximum difference Δi was obtained by comparison. d+ The maximum difference Δi d+ The third PI controller generates a positive-sequence active voltage U. d+ The maximum difference Δi d+ The maximum difference Δi q+ Synthesized as a suitable current I rectiv Voltage drop ΔU and voltage U N The ratio gradually increases from 10% to 20%, reaching the maximum difference Δi. d+ The maximum difference Δi q+ With continuous injection, the current ratio I rective / I total Gradually increasing from 20% to 45%, the inverter operates continuously for 1 second, and the power factor starts to decrease from 1, ΔU / U N Gradually increase to 50%, suitable for current I rective Reaching I from 0 within 4 seconds total The power factor drops to 0, and the positive sequence reactive current Δi q+ The value is 0, indicating that positive-sequence active power is being injected into the power grid normally.

[0233] Under normal grid voltage conditions, the photovoltaic grid-connected inverter operates in a unity power factor state (0), supplying only active power to the grid, with zero reactive power. However, when the voltage drops (LVRT occurs), the grid connection point voltage is compared with the normal voltage (including the standard voltage). Based on the grid-connected control TE-SVM modulation strategy of this invention, the PI regulator redistributes the active and reactive current commands through the outer loop of the grid voltage, thereby achieving the distribution of inverter output power to the grid. The deeper the grid voltage drop, the more reactive power the inverter provides to the grid. By accurately detecting the grid voltage, it is determined whether the voltage fluctuation is within the normal range. If it is within the normal range, the inverter operates in a unity power factor grid-connected state; otherwise, it needs to provide reactive power to the grid.

[0234] The two-phase positive sequence static voltage converter module also includes:

[0235] The first cross-coupler ±ωL is used to couple the positive-sequence theoretical active current I. d + and the reactive current I according to positive sequence theory q + Perform cross-coupling to cancel the positive-sequence theoretical active current I. d + and the reactive current I according to positive sequence theory q The coupling term + causes the d-axis component to be affected by I. d The effect of + causes the q-axis component to be affected by I. q The + function will transform the positive sequence theoretical active current I d+Enter ωL f The product of these terms is coupled and canceled out; the d-axis coupling term is -ωLi. d Add ωLid and the positive-sequence theoretical active current I on the d-axis. d The coupled phase -ωLid on + is canceled; the positive sequence theoretical reactive current I is reduced. q +Enter-ωL f The product of these terms is coupled and canceled out; the q-axis coupling term is ωLi. q Simply add -ωLi to the q-axis q Reactive current I according to positive sequence theory q + Coupled phase ωLi q To offset;

[0236] The fifth positive-sequence comparator is used for the positive-sequence active DC reference voltage U. d + Positive sequence active voltage V d The active power outputs of the + and the first cross-coupler ±ωL are converged and compared for error.

[0237] The sixth positive-sequence comparator is used for the positive-sequence reactive DC reference voltage U. q + Positive sequence reactive voltage V q + and the reactive output of the first cross coupler ±ωL are aggregated and compared for error;

[0238] The first 2R / 2S coordinate transformation module is used to perform 2R / 2S coordinate transformation on the outputs of the positive-sequence fifth and sixth comparators based on the input voltage starting angle θ, to obtain the two-phase positive-sequence static voltage U. α +、U β +.

[0239] The intelligent controller of the one-stop intelligent megawatt box system based on TE-SVM modulation according to this embodiment of the invention further includes:

[0240] A two-phase negative sequence static voltage converter module is used to convert the input three-phase standard voltage V. a ′、V b ′、V c ′, Output of the current correction module, Voltage start angle θ, Negative sequence three-phase voltage V a -、V b -、V c - Positive sequence reactive DC reference current I qref +, Positive and negative sequence theoretical reactive reference current Positive and negative sequence actual reactive current I′ q+ 、I′ q- The transformation yields the two-phase negative sequence static voltage U. α -、U β - The two-phase negative sequence static voltage conversion module includes:

[0241] The voltage initial phase angle determination module is used to determine the voltage initial angle based on the input voltage starting angle θ and the negative sequence three-phase voltage V. a- V b -、V c -, convert to obtain the initial phase angle of the voltage The voltage initial phase angle determination module includes:

[0242] The fifth 3S / 2R conversion module is used to convert the input negative sequence three-phase voltage V based on the input voltage start angle θ. a -、V b -、V c - Perform a 3S / 2R coordinate transformation to obtain the active voltage V. d and reactive voltage V q ;

[0243] The initial phase angle calculation module is used to calculate the initial phase angle based on the active voltage V. d and reactive voltage V q The initial phase angle of the voltage was calculated.

[0244] The two-phase negative sequence static voltage converter module also includes:

[0245] The negative-sequence active and reactive current conversion module is used to convert the output of the current correction module to obtain the negative-sequence theoretical active current I. d - and negative sequence theory reactive current I q - The negative-sequence active and reactive current conversion module includes:

[0246] The sixth 3S / 2R conversion module is used to convert the voltage starting angle θ and the voltage initial phase angle. Perform a 3S / 2R coordinate transformation on the output current of the current correction module to output the negative sequence active current I. d - and negative sequence reactive current I q -;

[0247] The third low-pass filter, LPF, is used to filter the negative-sequence active current I. d - and negative sequence reactive current I q - Perform low-pass filtering to remove high-frequency components and retain low-frequency components;

[0248] The third bandpass filter (BPF) is used to bandpass filter the output current of the third low-pass filter (LPF), filtering out noise outside the bandwidth and outputting a clean negative-sequence active current I. d - and negative sequence reactive current I q -

[0249] The two-phase negative sequence static voltage converter module also includes:

[0250] The negative sequence voltage conversion module is used to convert the input three-phase standard voltage V a ′、V b ′、V c The conversion is performed to obtain the negative sequence active voltage V. d - and negative sequence reactive voltage V q - The negative sequence voltage conversion module includes:

[0251] The seventh 3S / 2R conversion module is used to convert the voltage starting angle θ and the voltage initial phase angle. For the input three-phase standard voltage V a ′、V b ′、V c Perform a 3S / 2R coordinate transformation to output negative sequence active voltage V. d - and negative sequence reactive voltage V q -;

[0252] The fourth low-pass filter, LPF, is used to filter the negative-sequence active voltage V. d - and negative sequence reactive voltage V q - Perform low-pass filtering to remove high-frequency components and retain low-frequency components;

[0253] The fourth bandpass filter (BPF) is used to bandpass filter the output voltage of the fourth low-pass filter (LPF), filtering out noise outside the bandwidth and outputting a clean negative-sequence active voltage V. d - and positive sequence reactive voltage V q -

[0254] The two-phase negative sequence static voltage converter module also includes:

[0255] The fifth PI controller is used to control the negative-sequence theoretical active current I. d - Negative sequence actual active current I′ d- and the active reference current of negative sequence theory Perform PI control to output negative-sequence active DC reference voltage U d -;

[0256] The first negative-sequence comparator is used for the negative-sequence theoretical reactive current I. q - Negative sequence reactive DC reference current I qref - Negative sequence actual reactive current I′ q- and negative sequence theory reactive reference current The data is aggregated, and errors are compared.

[0257] The sixth PI controller is used to perform PI control on the output current of the negative-sequence first comparator, and outputs a negative-sequence reactive DC reference voltage U. q -;

[0258] The negative-sequence low-voltage ride-through control module is used to detect whether a voltage drop occurs at the grid connection point and to perform low-voltage ride-through control when a voltage drop occurs. It controls the inputs of the fifth and sixth PI controllers, thereby controlling the generation of the negative-sequence active DC reference voltage U at different times. q - Reactive power is injected into the grid, enabling photovoltaic power generation to operate without disconnecting from the grid. The negative sequence low voltage ride-through control module includes:

[0259] The second low-voltage ride-through module is used to determine the input negative-sequence three-phase voltage V. a -、V b -、V c - Detect whether a voltage drop occurs at the grid connection point and perform droop control, outputting the root mean square droop voltage;

[0260] The second root mean square detection module is used to perform root mean square detection on the output of the second low voltage ride-through module.

[0261] The third-order negative-sequence maximum current calculation module is used to calculate the positive-sequence reactive DC reference current I. qref +, Maximum current I max and voltage initial phase angle Calculate the third-order negative-sequence maximum current I qmax -;

[0262] The fourth 2R / 2S coordinate transformation module is used for the negative sequence active voltage V. d - and negative sequence reactive voltage V q - Perform a 2R / 2S coordinate transformation to obtain the negative sequence two-phase static voltage U. a U B ;

[0263] The second reference current calculation module is used to calculate the reference current based on the reference power P. * Negative sequence two-phase static voltage U a U B Calculate the negative sequence reference current

[0264] The second voltage and current calculation module is used to calculate the negative sequence two-phase static voltage U. a U B and negative sequence reference current Combining formulas and Calculate the grid connection point voltage U N and total current I total ;

[0265] The second voltage drop determination module, when a low-voltage ride-through occurs, determines the voltage drop ΔU based on the result of the second root mean square (RMS) detection module. When a voltage droop RMS exists, it compares the voltage at the grid connection point during the low-voltage ride-through with the grid connection point voltage U.N The voltage drop ΔU is obtained by comparison; when there is no root mean square voltage droop, that is, the voltage at the grid connection point during low voltage ride-through when a voltage drop occurs, it is compared with the grid connection point voltage U. N When they are equal, it indicates that zero-voltage ride-through has occurred. At this time, the three-phase average voltage V output by the inverter is used. iava V iavb V iavc With grid connection point voltage U N The voltage drop ΔU is obtained by comparison;

[0266] The second low-voltage ride-through control module performs low-voltage ride-through control based on the voltage drop ΔU when a low-voltage ride-through occurs, setting the negative-sequence reactive power to 0, i.e., the negative-sequence theoretical reactive power reference current. Negative sequence theory reactive current I q- Negative sequence actual reactive current I' q- Set to 0; power factor set to 1, low-voltage ride-through control based on voltage drop ΔU; then negative sequence theoretical active reference current. Negative sequence theory active current I d- Negative sequence actual active current I' d- Comparison (the comparator) Figure 3 (Not shown in the text) The maximum difference Δi is obtained. d- The maximum difference Δi d- As the initial suitable current I rective The input is to the fifth PI controller, which generates a negative-sequence active voltage U. d- Suitable for current I rectiv With total current I total The ratio gradually increases to 20%, and the voltage drop ΔU and voltage U N The ratio begins to rise when it reaches 10%; negative sequence theoretical reactive reference current Negative sequence theory reactive current I q- Negative sequence actual reactive current I' q- Negative sequence reactive reference current I qref- The maximum difference Δi was obtained by comparison. q- The maximum difference Δi q- The input is to the sixth PI controller, which generates a negative-sequence reactive voltage U. q- The maximum difference Δi q- The maximum difference Δi d- Synthesized as a suitable current I rectiv Voltage drop ΔU and voltage U N The ratio gradually increases from 10% to 20%, reaching the maximum difference Δi. q- The maximum difference Δi d- With continuous injection, the current ratio I rective / I totalGradually increasing from 20% to 45%, the inverter operates continuously for 1 second, and the power factor starts to decrease from 1, ΔU / U N Gradually increase to 50%, suitable for current I rective Reaching I from 0 within 4 seconds total When the power factor drops to 0, the negative sequence active current injects negative sequence active power into the grid normally, while the negative sequence reactive voltage of the negative sequence reactive power is limited.

[0267] The two-phase negative sequence static voltage converter module also includes:

[0268] The second cross-coupler ±ωL is used to control the negative-sequence theoretical active current I. d -Reactive current I according to negative sequence theory q - Perform cross-coupling to cancel the negative-sequence theoretical active current I. d -Reactive current I according to negative sequence theory q - The coupling term causes the d-axis component to be affected by I d The effect of - on the q-axis component is influenced by I. q The function of - is to transform the negative sequence theory active current I d -Input-ωL f The product of these terms is coupled and canceled out; the d-axis coupling term is ωLi. d Add -ωLid and the negative sequence theoretical active current I on the d-axis. d - The coupling phase ωLid on the - is canceled; the negative sequence theoretical reactive current I is reduced. q - Input ωL f The product of these terms is coupled and canceled out; the q-axis coupling term is -ωLi. q Add ωLi on the q-axis q And negative sequence theory reactive current I q -coupling phase-ωLi q To offset;

[0269] The negative-sequence second comparator is used for the negative-sequence active DC reference voltage U. d - Negative sequence active voltage V d - The active power output of the second cross-coupler ±ωL is aggregated for error comparison;

[0270] The negative-sequence third comparator is used for the negative-sequence reactive DC reference voltage U. q - Negative sequence reactive voltage V q - and the reactive power output of the second cross coupler ±ωL is aggregated and compared for error;

[0271] The second 2R / 2S coordinate transformation module is used to transform the voltage starting angle θ and the voltage initial phase angle. Performing a 2R / 2S coordinate transformation on the outputs of the negative-sequence second and third comparators yields the two-phase negative-sequence static voltage U.α -、U β -

[0272] To evaluate and analyze the topology simplification of the intelligent controller in this embodiment of the invention, it is divided into positive-sequence circuits and negative-sequence circuits, such as... Figure 4 As shown, both the positive-sequence circuit and the negative-sequence circuit consist of INV, a power grid, an active power meter, and a reactive power meter.

[0273] The intelligent controller of the one-stop intelligent megawatt box system based on TE-SVM modulation enables low voltage ride-through with superior current tracking performance during grid disturbances or fault drops. It also sends positive-sequence reactive power and negative-sequence active power to the grid and supports the grid connection point voltage, which is beneficial to the safety and stability of the system.

[0274] The intelligent controller of the one-stop intelligent megawatt box system based on TE-SVM modulation according to this embodiment of the invention further includes:

[0275] The TE-SVM waveform generation module performs frequency estimation for smart grids based on the TLS-ESPRIT algorithm, utilizing two-phase positive-sequence static voltage U. α +、U β + and two-phase negative sequence static voltage U α -、U β - Synthesize a three-phase reference voltage, using the grid frequency output by the phase-locked loop or the smart grid frequency solved by the TLS-ESPRIT algorithm as the transmission frequency, and combine it with the synthesized three-phase reference voltage to transmit the waveform, controlling the inverter bridge to invert. The TE-SVM waveform transmission module includes:

[0276] The TLS-ESPRIT frequency estimation module is used to estimate the frequency of the smart grid based on the TLS-ESPRIT (rotationally invariant subspace frequency search) algorithm.

[0277] The SVM waveform generation module is used to generate waveforms based on the two-phase positive sequence static voltage U. α +、U β + and two-phase negative sequence static voltage U α -、U β - Synthetic three-phase reference voltage It transmits waves based on the grid frequency output by the phase-locked loop or the smart grid frequency estimated by the TLS-ESPRIT frequency estimation module;

[0278] The gate controller is used to control each switching module of the inverter to turn on or off based on the vector signal sent by the SVM waveform generation module.

[0279] After the SVM waveform generation module outputs to the outer loop control, inner loop control, and gate control, it modulates the control terminal of the power switch transistor of the inverter switching module according to the SVPWM modulation. Figure 2As shown, the phase-locked loop output voltage start angle θ, input voltage and current inner loop controller, photovoltaic array and smart module switch temperature sensor detection and control, and DC-DC conversion voltage U dc After passing through the A / D converter, the input to the power outer loop controller is the DC bus capacitor voltage U. bus The voltage is input to the gate controller after passing through the AD converter, and the gate controller outputs a three-phase voltage u. c u b u a and frequency, three-phase voltage u c u b u a With frequency input SVPWM, each phase SVPWM controls the operation of two switching modules on one bridge arm of the inverter.

[0280] Specifically, such as Figure 5 As shown, the vector output terminal of the SVM waveform generation module is connected to the gate controller. The gate controller can be a voltage equalization gate controller. The six output vectors are connected to the drive terminals of the six gates of the voltage equalization gate controller, and the drive lines are sequentially connected to the gates of the corresponding power switches of the inverter. An output current I is output between the drain of the upper bridge arm power switch, the source of the lower bridge arm power switch, and between the source and drain of the upper and lower bridge arm power switches in each bridge arm. A I B I C Output current I A I B I C The corresponding A / D converter is connected to the corresponding isolation circuit, which is then connected to the equalizing gate controller; a corresponding equalizing voltage U is connected between the source of the upper bridge arm power switch and the drain of the lower bridge arm power switch in each of the three bridge arms. AE U BE U CE Equalization voltage U AE U BE U CE Each transistor is connected to its corresponding isolation circuit via an A / D converter. This isolation circuit is then connected to the voltage equalization gate controller to achieve average voltage equalization of the three-phase power switching transistors.

[0281] Example 3

[0282] A control method for a one-stop intelligent megawatt box based on TE-SVM modulation for friendly access to the smart grid, using the intelligent controller of the one-stop intelligent megawatt box system based on TE-SVM modulation described in Example 2, is carried out according to the following steps:

[0283] Step S1: Receive the actual active and reactive power at the smart grid connection point, and the three-phase detection voltage V. a V b Vc The three-phase voltage V at the grid connection point ga V gb V gc Three-phase average voltage V iava V iavb V iavc Three-phase current I a I b I c Three-phase average current I aavg I bavg I cavg DC bus capacitor voltage U bus Photovoltaic array output current I pv Average current I pvavg It employs an MPPT controller to track the maximum power of the DC / DC converter and outputs a positive-sequence DC reference voltage U. ref + and DC reference current

[0284] Step S2: Calculate the standard active power and reactive power, and the instantaneous values ​​of active power and reactive power at the smart grid connection point;

[0285] Step S3: Determine whether the actual active power and reactive power at the smart grid connection point correspond to the calculated instantaneous values ​​of active power and reactive power at the smart grid connection point, as well as the standard active power and reactive power; and determine whether the frequency output by the phase-locked loop is within the range of 50±0.1Hz.

[0286] Step S4: If the actual active power and reactive power at the smart grid connection point correspond to the calculated instantaneous values ​​of active power and reactive power at the smart grid connection point, and the frequency output by the phase-locked loop is within the range of 50±0.1Hz, then the frequency output by the phase-locked loop is used as the transmission frequency of the SVM transmission module; otherwise, the frequency search of the smart grid is performed using the TLS-ESPRIT frequency estimation module, and the searched frequency is used as the transmission frequency of the SVM transmission module.

[0287] Step S5: Calculate the three-phase standard voltage V based on the voltage and current signals received in step S1. a ′、V b ′、V c ′, Three-phase standard current I a ′、I b ′、I c ′, standard active power and reactive power, instantaneous active power and instantaneous reactive power at the smart grid connection point, and two-phase positive sequence static voltage U obtained using a two-phase positive sequence static voltage conversion module and a two-phase negative sequence static voltage conversion module. α +、U β + and the two-phase negative sequence static voltage Uα -、U β -; Using the SVM waveform generation module based on the two-phase positive sequence static voltage U α +、U β + and the two-phase negative sequence static voltage U α -、U β - A reference voltage is synthesized, and then an SVM waveform is generated based on the waveform generation frequency and the reference voltage. The equalizing gate controller uses SVPWM modulation to control each switching module of the inverter to turn on or off according to the vector signal generated by the SVM waveform. The specific operation is as follows:

[0288] like Figure 5 As shown, the inverter's six IGBT / IGCT switching modules are distributed across six sectors in the SVM. These six sectors are defined by voltage vectors V1, V2, V3, V4, V5, V6, V0, and V7 as boundary values, with V0 and V7 being the origin. The starting boundary time for each sector is T1, and the ending boundary time for adjacent 60-degree intervals is T2. T1, T2, and T0 are the synthesized reference voltages. The driving time of the decomposed vector. T0 and T7 are virtual times used to replace the B and C phases, and the time when the A phase repeats its waveform. In reality, the repeated segments of the B and C phases and the A phase only run along the time period to achieve synchronization, eliminating the repeated waveform of the power transistors. Only one power transistor generates power at a time, reducing ineffective power consumption. Along the 6 sectors, the voltage vectors V1, V2, V3, V4, V5, V6, V0, V... 7· A vector that rotates 360 degrees counterclockwise corresponds to six power switching modules driven by six vector switching frequency signals S1, S2, S3, S4, S5, and S6.

[0289] The switching frequencies, switching states, and space vector definitions of the corresponding vector switches S1, S2, S3, S4, S5, and S6 in SVM are as follows, as shown in Table 1:

[0290] S1: Frequency: Switch state: 100; Vector: 0°; Equation value: (2 / 3, 0); Vector voltage V1; Reference voltage:

[0291] S2: Frequency: Switch state: 110; Vector: 60°; Equation value: (1 / 3, Vector voltage V2; Reference voltage:

[0292] S3: Frequency: Switch state: 010; Vector: 120°; Equation value: (-1 / 3, Vector voltage V3; Reference voltage:

[0293] S4: Frequency Switch state: 011; Vector: 180°; Equation value: (-2 / 3, 0); Vector voltage V4; Reference voltage:

[0294] S5: Frequency: Switch state: 001; Vector: 240°; Equation value: (-1 / 3, Vector voltage V5; Reference voltage:

[0295] S6: Frequency Switch state: 101; Vector: 300°; Equation value: (1 / 3, Vector voltage V6; Reference voltage:

[0296] S7: Frequency: Switch status: 111; Vector: 0°;

[0297] S0: Frequency Switch status: 000; Vector: 0°.

[0298] Table 2 defines vector switches, space vectors, switch states, and line voltages.

[0299]

[0300]

[0301] The corresponding vector switches S1, S2, S3, S4, S5, and S6 in SVM are related to the transmission frequency. Relationship such as Figure 6 As shown, the frequency waveforms driving the upper and lower switches of the six sectors of the space vector SVM are defined as follows:

[0302] Sector 1:

[0303] The wave transmission time of upper switch S1 is S1 = T1 + T2 + T0 / 2, the wave transmission time of upper switch S3 is S3 = T2 + T0 / 2, the wave transmission time of upper switch S5 is S5 = T0 / 2, the wave transmission time of lower switch S4 is S4 = T0 / 2, the wave transmission time of lower switch S6 is S6 = T1 + T0 / 2, and the wave transmission time of lower switch S2 is S2 = T1 + T2 + T0 / 2.

[0304] 2 sectors:

[0305] The wave transmission time of upper switch S1 is S1 = T1 + T0 / 2, the wave transmission time of upper switch S3 is S3 = T1 + T2 + T0 / 2, the wave transmission time of upper switch S5 is S5 = T0 / 2, the wave transmission time of lower switch S4 is S4 = T2 + T0 / 2, the wave transmission time of lower switch S6 is S6 = T0 / 2, and the wave transmission time of lower switch S2 is S2 = T1 + T2 + T0 / 2.

[0306] 3 sectors:

[0307] The wave transmission time of upper switch S1 is S1 = T0 / 2, the wave transmission time of upper switch S3 is S3 = T1 + T2 + T0 / 2, the wave transmission time of upper switch S5 is S5 = T2 + T0 / 2, the wave transmission time of lower switch S4 is S4 = T1 + T2 + T0 / 2, the wave transmission time of lower switch S6 is S6 = T0 / 2, and the wave transmission time of lower switch S2 is S2 = T1 + T0 / 2.

[0308] 4 sectors:

[0309] The wave transmission time of upper switch S1 is S1 = T0 / 2, the wave transmission time of upper switch S3 is S3 = T1 + T0 / 2, the wave transmission time of upper switch S5 is S5 = T1 + T2 + T0 / 2, the wave transmission time of lower switch S4 is S4 = T1 + T2 + T0 / 2, the wave transmission time of lower switch S6 is S6 = T2 + T0 / 2, and the wave transmission time of lower switch S2 is S2 = T0 / 2.

[0310] 5 sectors:

[0311] The wave transmission time of upper switch S1 is S1 = T2 + T0 / 2, the wave transmission time of upper switch S3 is S3 = T0 / 2, the wave transmission time of upper switch S5 is S5 = T1 + T2 + T0 / 2, the wave transmission time of lower switch S4 is S4 = T1 + T0 / 2, the wave transmission time of lower switch S6 is S6 = T1 + T2 + T0 / 2, and the wave transmission time of lower switch S2 is S2 = T0 / 2.

[0312] 6 sectors:

[0313] The wave transmission time of upper switch S1 is S1 = T1 + T2 + T0 / 2, the wave transmission time of upper switch S3 is S3 = T0 / 2, the wave transmission time of upper switch S5 is S5 = T1 + T0 / 2, the wave transmission time of lower switch S4 is S4 = T0 / 2, the wave transmission time of lower switch S6 is S6 = T1 + T2 + T0 / 2, and the wave transmission time of lower switch S2 is S2 = T2 + T0 / 2.

[0314] The Space Vector Dynamics (SVM) operates based on vector states and the frequencies S1, S3, S5, S4, S6, and S2 that drive the upper and lower switches in six sectors. These frequencies, defined by the gate frequency S1, S3, S5, S4, S6, and S2, are used to drive the control electrodes (gate G) of the upper switches S1, S3, and S5 in the inverter via a voltage equalization gate controller. The transmission is initiated sequentially according to the vector switch definition: S1→S3→S5. The current IA from the upper switch S1 is input to the corresponding A / D converter and isolation circuit through the emitter and collector, respectively, and then returned to the voltage equalization gate controller to achieve voltage equalization control and inversion. The lower switch S4 is closed and inactive. 3. The current IB of switch S1 is input to the corresponding A / D converter and isolation circuit through the emitter and collector respectively, and returns to the voltage equalization gate controller to achieve voltage equalization control inversion. Switch S6 is closed and not in operation. The current IC of switch S5 is input to the corresponding A / D converter and isolation circuit through the emitter and collector respectively, and returns to the voltage equalization gate controller to achieve voltage equalization control inversion. Switch S2 is closed and not in operation. Conversely, when switches S4 → S6 → S2 operate according to the wave transmission time and sequence of sector 1, switches S1 → S3 → S5 are closed and not in operation. Sectors 2, 3, 4, 5, and 6 operate sequentially according to the above process, from sector 1 to sector 6.

[0315] The RMS current I of the intelligent controller of the one-stop megawatt box system based on TE-SVM modulation for connection to the smart grid. dRMS I qRMS The waveform is shown Figure 7 This demonstrates that the frequency, phase, and amplitude accuracy of the dual-vector current control all meet the synchronization and real-time requirements, providing the necessary conditions for the dual intelligent controller. The intelligent controller, based on TE-SVM modulation and integrated into the smart grid in a one-stop intelligent megawatt box, exhibits excellent performance in controlling the dq-axis current under both balanced and unbalanced loads, with a synchronously rotating (dq) coordinate system.

[0316] Network testing for harmonics Figure 8 The three-phase inverter waveform is shown below. Figure 9 , Figures 8-9 This study demonstrates that the intelligent controller using a one-stop intelligent megawatt box based on TE-SVM modulation for friendly access to the smart grid meets the real-time synchronization requirements of the smart grid in terms of the synchronization and real-time performance of the inverter's output three-phase current, three-phase voltage, line voltage, and line current. It also exhibits high-quality harmonic component processing capabilities, with the measured harmonic THD reaching 2.23%. Therefore, the intelligent controller using a one-stop intelligent megawatt box based on TE-SVM modulation for friendly access to the smart grid can independently handle unbalanced positive and negative sequence components and has excellent processing capabilities for low and high order harmonics.

[0317] The intelligent controller based on TE-SVM modulation enables the one-stop intelligent megawatt box system to achieve a real-time and synchronization rate of 93.5% when connected to the smart grid, with a conversion efficiency of ≥99.9%. It eliminates resonant frequency shift and resonant spikes under unbalanced faults, reduces unexplained switching losses by 90%, and achieves an output current harmonic THD below 2.23. The DC bus voltage utilization rate is 5% higher than the current world advanced level of 90%. It has a large modulation ratio, good dynamic performance (see Table 2), and achieves pulse-level synchronization. It enables highly efficient intelligent interactive operation with the smart grid.

[0318] Table 2 Comparison Information (August 17, 2020)

[0319]

[0320] like Figure 10 As shown, when the common point voltage of the PLL phase-locked loop drops to 0 and the unbalanced fault duration is 140ms, the operating effect of the intelligent controller using this embodiment of the invention is as follows: Figure 10 As shown, this invention can reduce AC side overvoltage and DC bus overvoltage of the network inverter, and minimize the fluctuation of voltage peak and active power. When encountering a low voltage drop in the grid, until it drops to 0 voltage, this invention injects 1100A of reactive current into the grid, achieving 100% reactive current injection from the inverter into the grid.

[0321] Figure 11 The LVRT waveform of the photovoltaic grid-connected inverter is shown when the grid voltage is symmetrical. The grid voltage drop depth is 15%, and the fault duration is 350ms. According to the grid connection rules, the positive sequence reactive current command output by the photovoltaic system during the fault duration should be expressed in per-unit value, with an upper limit of 1pu. The reactive current compensation coefficient is determined according to the penetration rate of the photovoltaic system into the grid, and is usually taken as 2. The reactive current command is equal to the reactive current compensation coefficient multiplied by the grid voltage drop depth ratio. It can be concluded that the reactive current command output by the grid-connected inverter during the fault duration is 0.3pu. According to the embodiment of the present invention, the power factor is 1 as the maximum factor. Due to the limitation of the rated capacity of the system, the active current command is limited to 0.7pu. During the fault, the DC bus voltage rises, and the LVRT response speed of the photovoltaic grid-connected inverter is relatively fast, which meets the requirements of the embodiment of the present invention: uninterrupted operation for 1 second, reactive power compensation completed within 4 seconds, and active power injected into the grid.

[0322] Several application scenarios for intelligent controllers with one-stop intelligent megawatt boxes based on TE-SVM modulation that are friendly to smart grid integration:

[0323] The current control system, i.e., SAG (SAG stands for droop control), does not inject reactive power;

[0324] In the current control system, when the active power of SAG is 0, reactive power is injected.

[0325] Full current feedback, which simultaneously performs positive sequence voltage feedforward and negative sequence voltage feedforward, is called VCCF;

[0326] Dual vector control, where negative sequence current is not controlled and negative sequence voltage is not fed forward, only positive sequence control is performed, is called DVCC1;

[0327] Dual vector control, where the negative sequence current is controlled to 0 and the negative sequence voltage is fed forward, is called DVCC2;

[0328] Dual vector control with current limiting function (active power limiting) is called DVCCL.

[0329] In step S5, the three-phase standard voltage V a ′、V b ′、V c Calculate according to formula (1):

[0330]

[0331] Among them, V p It is the peak value of the positive sequence voltage, V n It is the negative sequence voltage peak value. It is the initial phase angle of the positive sequence voltage. ω is the initial phase angle of the negative sequence voltage; ω is the angular frequency of the fundamental voltage.

[0332] Three-phase standard current I a ′、I b ′、I c Calculate according to formula (2):

[0333]

[0334] Among them, I p It is the peak value of the positive sequence current, I n It is the peak value of the negative sequence current, θ p It is the starting angle of the positive sequence current relative to the positive sequence voltage, θ n It is the starting angle of the negative sequence current relative to the negative sequence voltage;

[0335] In step S5, the positive and negative sequence impedances are calculated when the first low-voltage ride-through module and the second low-voltage ride-through module perform droop control, wherein:

[0336] Positive sequence impedance Z P (S) Calculated according to formula (3):

[0337]

[0338] Among them, K mV is the inverter voltage gain. dc H is the voltage difference across the DC bus capacitor. i (s-j2πf1) is the closed-loop transfer function of the inner-loop PI controller, i.e., the first PI controller, T PLL (s-j2πf1) is the closed-loop transfer function of the phase-locked loop, f1 is the fundamental frequency, and K is the fundamental frequency. d K is the gain of the weighting function. f G is the integral proportional parameter. i (s) is the equivalent transfer function of the current filter composed of the first low-pass filter LPF and the first band-pass filter BPF, L f C is the inductance value of the inverter-side inductor of the LCL filter, and C1 is the DC bus capacitance value; G v (s) is the equivalent transfer function of the voltage filter composed of the second low-pass filter LPF and the second band-pass filter BPF, where s represents the complex frequency domain. I1 is the initial phase angle of the fundamental current, V1 is the peak value of the fundamental current, and V1 is the peak value of the grid voltage.

[0339] Negative sequence impedance Z n (S) Calculated according to formula (4):

[0340]

[0341] Among them, H i (s+j2πf1) is the closed-loop transfer function of the inner-loop PI controller, i.e., the first PI controller, G. i (s) is the equivalent transfer function of the current filter composed of the first low-pass filter LPF and the first band-pass filter BPF, G v (s) is the equivalent transfer function of the voltage filter composed of the fourth low-pass filter LPF and the fourth band-pass filter BPF;

[0342] According to the constant amplitude Clark transform formula, the expressions for voltage and current in a two-phase rotating coordinate system can be obtained as follows:

[0343]

[0344] Among them, V d V is the d-axis voltage in a two-phase rotating coordinate system. q Let I be the q-axis voltage in a two-phase rotating coordinate system. d Let I be the d-axis current in a two-phase rotating coordinate system. q Let q be the q-axis current in a two-phase rotating coordinate system;

[0345] Standard active power and standard reactive power are calculated according to formulas (7) to (8):

[0346]

[0347] Where P(t) is the standard active power, Q(t) is the standard reactive power, and V... α V β Let I be the voltage in the stationary reference (αβ) coordinate system. α I β Let θ1 and θ2 represent the initial phase angles of the voltage in the stationary reference (αβ) coordinate system.

[0348] In a three-phase symmetrical system, dq is a DC component in the fundamental steady state, and the d-axis coincides with the grid voltage vector. Therefore, active and reactive power can be controlled independently. If the second harmonic is filtered out, the expressions for the instantaneous values ​​of the fundamental active power and reactive power are as follows:

[0349]

[0350] P0(t) is the instantaneous value of fundamental active power, Q0(t) is the instantaneous value of fundamental reactive power, and the instantaneous values ​​of active power and reactive power at the smart grid connection point are calculated according to formula (9).

[0351] dq transformation voltage initial phase angle Calculate according to formula (10):

[0352]

[0353] The third-order negative sequence maximum current I qmax- Calculate according to formula (11):

[0354]

[0355] Among them, I max It is the maximum current, k is a positive integer coefficient, and α = ωt;

[0356] The negative sequence reactive power reference current I qref - Calculate according to the following formula:

[0357]

[0358] SVM synthesizes the vector reference voltage according to formula (13).

[0359]

[0360] Example 4

[0361] The search algorithm process for TLS-ESPRIT frequency estimation is as follows:

[0362] The expression for the sampled real signal of the power grid is:

[0363]

[0364] where \(x(n)\) is the real power grid sampling signal at the \(n\)th sampling point, \(p\) is the number of harmonic components of the real power grid sampling signal, and \(\alpha\) k is the amplitude of the \(k\)th harmonic and interharmonic components of the real power grid sampling signal, and \(\omega\) k is the angular frequency of the \(k\)th harmonic and interharmonic components of the real power grid sampling signal, is the phase of the \(k\)th harmonic and interharmonic components of the real power grid sampling signal, \(n\) is the sampling point, and \(W(n)\) is the noise component of the real power grid sampling signal at the \(n\)th sampling point.

[0365] Based on TLS - ESPRIT to solve the power grid frequency, formula (14) is transformed into a sampling complex signal through Euler transformation:

[0366]

[0367] where \(\alpha'\) k is the amplitude of the \(k\)th harmonic and interharmonic components of the sampling complex signal, and \(\omega'\) k is the angular frequency of the \(k\)th harmonic and interharmonic components of the sampling complex signal, is the phase of the \(k\)th harmonic and interharmonic components of the sampling complex signal;

[0368] When \(1\leq k\leq p\),

[0369] When \(p\lt k\leq 2p\), \(\alpha\) k-p is the amplitude of the \((k - p)\)th harmonic and interharmonic components of the real power grid sampling signal, and \(\omega\) k-p is the frequency of the \((k - p)\)th harmonic and interharmonic components of the real power grid sampling signal, is the initial phase angle of the \((k - p)\)th harmonic and interharmonic components of the real power grid sampling signal;[[ID=Y]]

[0370] Define a signal vector \(X(n)\) with dimension \(L\times1\), where \(L\gt\gt 2p\). Combining with formula (15), we have:

[0371] \(X(n)=[x(n),x(n + 1),\cdots,x(n + L - 1)]\) T ; (16)

[0372] Using formula (14), formula (15) can be described as:

[0373] \(X(n)=S(n)+W(n)=A\varphi\) n \(\alpha+W(n)\); (17)

[0374] Where S(n) is the vector of the nth sampling point, α is the interharmonic amplitude, A is the phase, and φ is the rotation factor matrix, S(n) = Aφ n α = [x(n), x(n+1), ..., x(n+L-1)] T ,Α=[α(ω1),α(ω2),L,α(ω 2p )], W(n)=[W(n),W(n+1),L,W(n+L-1)] T ;

[0375] After removing the first row S(n) and the last row, the intersecting vectors S1 and S2 are obtained using the vertical decomposition method:

[0376]

[0377] Let S2 = S1φ, the frequency information of the signal is completely contained in the rotation factor matrix φ.

[0378] Based on the constraint of minimizing the overall mean square error, the frequency parameters of the interharmonics are estimated, and the process is as follows:

[0379] (1) Construct the HANKEL matrix using the sampled data:

[0380]

[0381] Where M is the number of array elements, N is the number of snapshots, and M>L>>2p.

[0382] (2) Perform singular value decomposition on matrix X:

[0383]

[0384] Where L is the left singular vector matrix, U H L is a right singular vector matrix. s L is the left singular vector matrix corresponding to the maximum singular value. n Let be the left singular vector matrix corresponding to the minimum singular value, and let ∑ be the diagonal matrix of singular values ​​arranged in descending order. Let ∑s be the right singular value vector matrix corresponding to the 2P maximum singular values. The signal subspace of Zhang Cheng; Let ∑n be the right singular value vector matrix corresponding to L-2P minimum singular values. The spanning noise subspace;

[0385] (3) Remove In the first and last rows, we obtain two intersecting vectors U1 and U2 using the vertical decomposition method. Let U1 = ΨU2, and then perform singular value decomposition on the matrix [U1, U2] using the least squares approach:

[0386]

[0387] (4) The matrix is ​​decomposed into four 2P×2P square matrices:

[0388]

[0389] Then we have:

[0390]

[0391] (5) To Ψ TLS Perform eigenvalue decomposition to obtain eigenvalues ​​λ. k The SVM transmission frequency parameters estimated from this are for:

[0392]

[0393] The above description is merely a preferred embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention are included within the scope of protection of the present invention.

Claims

1. A smart controller for one-stop smart megawatt box system based on TE-SVM modulation, characterized by, Comprising: MPPT controller for tracking the maximum power of the DC / DC converter, outputting a positive sequence DC reference voltage U ref + and a DC reference current ; A positive and negative sequence voltage decomposition module is configured to decompose three-phase detection voltages V a , V b , V c at the grid side of the inverter into positive sequence three-phase voltages V a +, V b +, V c + and negative sequence three-phase voltages V a -, V b -, V c -; A phase-locked loop for deriving a positive-sequence three-phase voltage V a + from an input three-phase voltage V b + from an input three-phase voltage V c + gives the voltage initial angle θ and frequency f; Current correction module, used to adjust the current according to the three-phase standard current. , , Inverter-side inductor L and LCL filter f Three-phase detection current I at the location a I b I c C for LCL filters f With R f The three-phase average current I output at the component aavg I bavg I cavg Make corrections; a first 3S / 2R transformation module, configured to perform 3S / 2R transformation on input three-phase detection current I a 、 b 、 c to output positive sequence actual active current , positive sequence actual reactive current , negative sequence actual active current , negative sequence actual reactive current ; The positive and negative sequence theory active reference current conversion module is used for comparing the input three-phase voltage V ga 、 gb 、 gc at the grid connection point with the standard three-phase voltage 、 、 and outputting the PI control result of the comparison as the theory active reference current 、 the positive sequence theory active reference current 、 the negative sequence theory active reference current ; The positive and negative sequence theory reactive reference current conversion module is used for converting the input theory active reference current And using the formula The theory reactive reference current is obtained by inverse calculation Then the DC reference current And the theory reactive reference current Are compared, and the positive sequence theory reactive reference current , The negative sequence theory reactive reference current ; wherein, Indicates the maximum current; Two-phase positive sequence static voltage conversion module, the two-phase positive sequence static voltage conversion module is used for converting three-phase standard voltage inputted by the current correction module , , , the output of the current correction module, voltage initial angle θ, positive sequence three-phase voltage V a +, V b +, V c +, DC bus capacitor voltage U bus , positive sequence DC reference voltage U ref +, photovoltaic array output current I pv , average current I pvavg outputted by the whole DC system of the photovoltaic array, positive sequence theoretical active reference current , positive sequence actual active current , two-phase positive sequence static voltage U α +, U β + obtained by conversion; The two-phase negative sequence static voltage conversion module is used for converting three-phase standard voltage into two-phase negative sequence static voltage according to the input three-phase standard voltage 、 、 , the output of the current correction module, the voltage initial angle θ, the negative sequence three-phase voltage V a -、V b -、V c -; the negative sequence reactive direct current reference current I qref- , the negative sequence theoretical reactive reference current , the negative sequence actual reactive current , the two-phase negative sequence static voltage U α -、U β - obtained by conversion; TE-SVM wave generation module, based on TLS-ESPRIT algorithm to estimate the frequency of smart grid, using two-phase positive sequence static voltage U α +, U β + and two-phase negative sequence static voltage U α -, U β - synthesis three-phase reference voltage, the grid frequency output by the phase-locked loop or the smart grid frequency solved by the TLS-ESPRIT algorithm as the wave generation frequency, and combine the synthesized three-phase reference voltage to generate waves, control the inverter.

2. The intelligent controller of the one-stop intelligent megawatt box system based on TE-SVM modulation according to claim 1, wherein, The current correction module comprises: The current correction module first comparator is used for comparing the three-phase average current I f with R f The three-phase average current I aavg , I bavg , I cavg The three-phase current I f at the inverter side inductance L a , I b , I c Converge and compare errors; a proportional controller for proportional control of the output of the first comparator of the current correction module; A current correction module second comparator is used to compare the output of the proportional controller with the three-phase standard current 、 、 for error comparison; The two-phase positive sequence static voltage conversion module comprises: The positive sequence active and reactive current conversion module is used for converting the output result of the current correction module to obtain positive sequence theoretical active current I d + and positive sequence theoretical reactive current I q +; a positive sequence voltage conversion module for converting input three-phase standard voltage , , , performing coordinate conversion and filtering to obtain positive sequence active voltage V d + and positive sequence reactive voltage V q +; The first positive sequence active reference current conversion module is used for carrying out coordinate transformation and PI control on the input DC bus capacitor voltage U bus , the positive sequence DC reference voltage U ref + to obtain the first positive sequence active DC reference current ; The second positive sequence active reference current conversion module is used for comparing and PI controlling the input photovoltaic array output current I pv , the average current I of the entire direct current system output of the photovoltaic array pvavg to obtain the second positive sequence active direct current reference current ; a positive sequence third comparator for the first positive sequence active dc reference current , a second positive sequence active dc reference current , a positive sequence theoretical active current I d +, a positive sequence theoretical active reference current and a positive sequence actual active current are aggregated and compared for errors; a third PI controller for proportional integral control of the output current of the positive sequence third comparator, outputting a positive sequence active DC reference voltage U d +; positive sequence fourth comparator for positive sequence real reference current I qref +, positive sequence theoretical reactive current I q +, positive sequence theoretical reactive reference current and positive sequence actual reactive current converge, error comparison is made; A fourth PI controller is used to proportionally and integrally control the output current of the positive sequence fourth comparator, and output a positive sequence reactive DC reference voltage U q +; The positive sequence low-voltage ride-through control module is used for detecting whether voltage drop occurs at the grid-connected point and performing low-voltage ride-through control when voltage drop occurs at the grid-connected point, controlling the input of the third PI controller and the fourth PI controller, and further controlling the generation of the positive sequence reactive direct-current reference voltage U q +, and injecting reactive power into the power grid, so that the photovoltaic power generation is not off-grid operation. a first cross-coupler ±ωL for cross-coupling the positive-sequence theoretical active current I d + with the positive-sequence theoretical reactive current I q + to cancel the coupling terms of the positive-sequence theoretical active current I d + with the positive-sequence theoretical reactive current I q + so that the d-axis component is influenced by I d + and the q-axis component is influenced by I q + a positive-sequence fifth comparator for comparing a positive-sequence active direct current reference voltage U d + a positive-sequence active voltage V d + and an active output of the first cross-coupler ±ωL converging to perform error comparison; a positive-sequence sixth comparator for a positive-sequence reactive direct-current reference voltage U q + a positive-sequence reactive voltage V q + and a reactive output convergence of the first cross-coupler ±ωL, to perform error comparison; a first 2R / 2S coordinate transformation module, configured to perform 2R / 2S coordinate transformation on outputs of the positive-sequence fifth comparator and the positive-sequence sixth comparator according to an input voltage initial angle θ to obtain two-phase positive-sequence static voltages U α +,U β + 3. The intelligent controller of the one-stop intelligent megawatt box system based on TE-SVM modulation according to claim 2, wherein, The positive sequence active and reactive current conversion module comprises: a second 3S / 2R conversion module, configured to perform 3S / 2R coordinate conversion on the output result of the current correction module according to an input voltage initial angle θ, and output a positive sequence theoretical active current I d + and a positive sequence theoretical reactive current I q +; a first low pass filter LPF for low pass filtering the positive sequence theoretical active current I d + and the positive sequence theoretical reactive current I q + to filter out the high frequency parts and to retain the low frequency parts; a first band pass filter BPF for band pass filtering the output of the first low pass filter LPF, filtering out noise outside the bandwidth, outputting clean positive sequence theoretical active current I d + and positive sequence theoretical reactive current I q +; The positive sequence voltage conversion module comprises: a third 3S / 2R conversion module, configured to perform 3S / 2R coordinate conversion on the input three-phase standard voltage according to an input voltage initial angle θ, and output positive-sequence active voltage V , , d + and positive-sequence reactive voltage V q +;​ a second low-pass filter LPF for low-pass filtering the positive-sequence active voltage V d + and the positive-sequence reactive voltage V q + to filter out the high-frequency part and retain the low-frequency part; a second band-pass filter BPF for band-pass filtering the output voltage of the second low-pass filter LPF, filtering out noise outside the bandwidth, and outputting a clean positive sequence active voltage V d + and a positive sequence reactive voltage V q +; The first positive sequence active reference current conversion module comprises: a positive sequence first comparator for a DC bus capacitor voltage U bus with a positive sequence DC reference voltage U ref + convergence, error comparison; A fourth 3S / 2R conversion module is configured to perform 3S / 2R coordinate conversion on the output of the first positive sequence comparator to remove the AC harmonic component in the DC voltage; a first PI controller for proportional integral control on the output voltage of the fourth 3S / 2R conversion module, outputting a first positive-sequence active direct-current reference current ; The second positive sequence active reference current conversion module comprises: positive sequence second comparator for the photovoltaic array output current I pv the average current I of the entire direct current system output of the photovoltaic array pvavg converge, and perform error comparison; a second PI controller for proportional integral control of the output current of the positive sequence second comparator, outputting a second positive sequence active DC reference current .

4. The intelligent controller of one-stop intelligent megawatt box system based on TE-SVM modulation according to claim 2, wherein, The positive sequence low voltage ride through control module comprises: The first low-voltage ride-through module is configured to detect whether a voltage drop occurs at a grid-connected point according to input three-phase detection voltages V a , V b , V c , and perform droop control to output a droop voltage root mean square. A first root mean square detection module is configured to perform root mean square detection on the output of the first low voltage ride through module; The reference power calculation module is used for calculating the fundamental active power instantaneous value and the fundamental reactive power instantaneous value, and comparing the fundamental active power instantaneous value and the reactive power instantaneous value with the standard active power and the standard reactive power and the actual power at the grid connection point to obtain the reference power ; a third 2R / 2S coordinate conversion module, configured to perform 2R / 2S coordinate conversion on positive-sequence active voltage V d + and positive-sequence reactive voltage V q + to obtain positive-sequence two-phase static voltage U a , U B ; a first reference current calculation module configured to calculate a first reference current , a two-phase static voltage U a , U B a positive sequence reference current , ; a first voltage and current calculation module for calculating grid point voltage U a , B and positive sequence reference current , in combination with formulas and , grid point voltage U N and total current I total ; The first voltage drop determination module, when a low-voltage ride-through occurs, is used to determine the voltage drop based on the result of the first root mean square detection module. When a drooping voltage root mean square exists, the voltage at the grid connection point during low-voltage ride-through due to a voltage drop is compared to the grid connection point voltage U. N Comparison yields voltage drop When there is no root mean square droop voltage, i.e., the voltage at the grid connection point during a low-voltage ride-through caused by a voltage drop, is compared with the grid connection point voltage U. N When the values ​​are equal, it indicates that zero-voltage ride-through has occurred. In this case, the three-phase average voltage output by the inverter is used. , , With grid connection point voltage U N Comparison yields voltage drop ; The first low-voltage ride-through control module sets the positive sequence active power to 0, i.e. the positive sequence theoretical active reference current , the positive sequence theoretical active current , the positive sequence actual active current , the power factor to 1, and outputs the positive sequence reactive DC reference current under the power factor of 1 , and performs low-voltage ride-through control according to the voltage drop ; then the positive sequence theoretical reactive reference current , the positive sequence theoretical reactive current , the positive sequence actual reactive current , the positive sequence reactive DC reference current are compared to obtain the maximum difference , and the maximum difference is taken as the initial suitable current I rective The fourth PI controller is inputted to generate the positive sequence reactive DC reference voltage , and reactive power compensation is performed, and the ratio of the suitable current I rective to the total current I total is gradually increased to 20%, the ratio of the voltage drop to the voltage U N reaches 10%; the positive sequence theoretical active reference current , the positive sequence theoretical active current , the positive sequence actual active current , the first positive sequence active DC reference current , the second positive sequence active DC reference current are compared to obtain the maximum difference , and the maximum difference is inputted to the third PI controller to generate the positive sequence active DC reference voltage , and the maximum difference and the maximum difference are synthesized as the suitable current I rective , the ratio of the voltage drop to the voltage U N is gradually increased from 10% to 20%, under the continuous injection of the maximum difference and the maximum difference , the current ratio I rective / I total is gradually increased from 20% to 45%, the inverter keeps uninterrupted operation for 1s, the power factor starts to decrease from 1, / is gradually increased to 50%, the suitable current I rective reaches I total in 4s, the power factor decreases to 0, the maximum difference is 0, and the positive sequence active power is normally injected into the power grid.

5. The intelligent controller of the one-stop intelligent megawatt box system based on TE-SVM modulation according to claim 4, wherein, The two-phase negative sequence static voltage conversion module comprises: a voltage initial phase angle determining module, configured to determine a voltage initial phase angle φ according to the input voltage initial angle θ and the negative sequence three-phase voltage V a -, b -, c -, convert the voltage initial phase angle φ. The negative sequence active and reactive current conversion module is used for converting the output result of the current correction module to obtain the negative sequence theoretical active current I d - and the negative sequence theoretical reactive current I q - a negative sequence voltage conversion module for converting input three-phase standard voltage 、 、 to obtain negative sequence active voltage V d - and negative sequence reactive voltage V q -; a fifth PI controller for PI controlling the negative sequence theoretical active current I d - the negative sequence actual active current and the negative sequence theoretical active reference current to output a negative sequence active DC reference voltage U d - a negative sequence first comparator for comparing the negative sequence theoretical reactive current I q a negative sequence reactive DC reference current I qref a negative sequence actual reactive current a negative sequence theoretical reactive reference current aggregates, and performs error comparison; a sixth PI controller for PI controlling the output current of the negative sequence first comparator, outputting a negative sequence reactive DC reference voltage U q -; The negative sequence low voltage ride through control module is used for detecting whether voltage drop occurs at the grid connection point and performing low voltage ride through control when voltage drop occurs at the grid connection point, controlling the input of the fifth PI controller and the sixth PI controller, and further controlling the negative sequence reactive direct current reference voltage U generated at different moments q , injecting reactive power to the power grid, so that the photovoltaic power generation is not off-grid operation; a second cross-coupler ±ωL for cross-coupling the negative-sequence theoretical active current I d - with the negative-sequence theoretical reactive current I q - to cancel the negative-sequence theoretical active current I d - with the negative-sequence theoretical reactive current I q - so that the d-axis component is influenced by I d - and the q-axis component is influenced by I q - a negative sequence second comparator for a negative sequence active direct current reference voltage U d - a negative sequence active voltage V d - converging the active output of the second cross-coupler ±ωL to perform error comparison; a negative sequence third comparator for a negative sequence reactive direct current reference voltage U q - and a negative sequence reactive voltage V q - and a reactive output convergence of the second cross-coupler ±ωL, to perform error comparison; A second 2R / 2S coordinate transformation module is configured to perform 2R / 2S coordinate transformation on the outputs of the negative sequence second comparator and the negative sequence third comparator according to the voltage initial angle θ and the voltage initial phase angle φ to obtain two-phase negative sequence static voltage U α -、U β -; The TE-SVM wave generation module comprises: A TLS-ESPRIT frequency estimation module is configured to estimate the frequency of the smart grid based on the TLS-ESPRIT algorithm; SVM firing module for firing according to two-phase positive sequence static voltage U α +, U β + and two-phase negative sequence static voltage U α -, U β -, synthesizing a three-phase reference voltage and according to the grid frequency output by the phase-locked loop or the frequency of the smart grid estimated by the TLS-ESPRIT frequency estimation module. A voltage equalization gate controller is configured to control each switching module of the inverter to open or close according to the vector signal sent by the SVM wave generation module.

6. The intelligent controller of the one-stop intelligent megawatt box system based on TE-SVM modulation according to claim 5, wherein, The voltage initial phase angle determination module comprises: a fifth 3S / 2R conversion module, configured to perform 3S / 2R coordinate conversion on the input negative sequence three-phase voltage V a - according to an input voltage initial angle θ to obtain an active voltage V b - and a reactive voltage V c - d q ;​ a phase angle calculation module for calculating a voltage phase angle φ from the active voltage V d and the reactive voltage V q . The negative sequence active and reactive current conversion module comprises: a sixth 3S / 2R conversion module, configured to perform 3S / 2R coordinate conversion on the output current of the current correction module according to the voltage initial angle θ and the voltage initial phase angle φ, and output a negative sequence theoretical active current I d - and a negative sequence theoretical reactive current I q - a third low pass filter LPF for low pass filtering the negative sequence theoretical active current I d - the negative sequence theoretical reactive current I q - low pass filtering, filtering out the high frequency part and retaining the low frequency part; a third band-pass filter BPF for band-pass filtering the output current of the third low-pass filter LPF, filtering out noise outside the bandwidth, outputting a clean negative sequence theoretical active current I d - the negative sequence theoretical reactive current I q - The negative sequence voltage conversion module comprises: a seventh 3S / 2R conversion module for performing 3S / 2R coordinate conversion on the input three-phase standard voltage according to the voltage initial angle θ and the voltage initial phase angle φ, and outputting a negative sequence active voltage V , , - and a negative sequence reactive voltage V d -. q - a fourth low pass filter LPF for low pass filtering the negative sequence active voltage V d - and the negative sequence reactive voltage V q - to filter out the high frequency parts and to retain the low frequency parts; a fourth band-pass filter BPF for band-pass filtering the output voltage of the fourth low-pass filter LPF, filtering out noise outside the bandwidth, outputting a clean negative sequence active voltage V d - and a negative sequence reactive voltage V q -; The negative sequence low voltage ride through control module comprises: A second low voltage ride through module is configured to detect whether a voltage drop occurs at the grid-connected point according to an input negative sequence three-phase voltage V a - and output a droop voltage root mean square value. b - and output a droop voltage root mean square value. c - detects whether a voltage drop occurs at the grid-connected point and performs droop control to output a droop voltage root mean square value. A second root mean square detection module is configured to perform root mean square detection on the output of the second low voltage ride through module; a third order negative sequence maximum current calculation module for calculating a third order negative sequence maximum current I qref + a maximum current I max and a voltage initial phase angle φ, a third order negative sequence maximum current I qmax -; a fourth 2R / 2S coordinate conversion module for performing 2R / 2S coordinate conversion on the negative sequence active voltage V d - and the negative sequence reactive voltage V q to obtain the negative sequence two-phase stationary voltage U a1 , U B1 ; a second reference current calculation module configured to calculate a second reference current based on the reference power , a negative sequence two-phase stationary voltage U a1 , U B1 calculate a negative sequence reference current , ; a second voltage and current calculation module, configured to calculate the grid-connection point voltage U a1 , B1 and the negative-sequence reference current , in combination with the formulae and , according to the negative-sequence two-phase static voltage U N and the total current I total ; The second voltage drop determination module, when a low-voltage ride-through occurs, is used to determine the voltage drop based on the result of the second root mean square detection module. When a drooping voltage root mean square exists, the voltage at the grid connection point during low-voltage ride-through due to a voltage drop is compared to the grid connection point voltage U. N Comparison yields voltage drop When there is no root mean square droop voltage, i.e., the voltage at the grid connection point during a low-voltage ride-through caused by a voltage drop, is compared with the grid connection point voltage U. N When the values ​​are equal, it indicates that zero-voltage ride-through has occurred. In this case, the three-phase average voltage output by the inverter is used. , , With grid connection point voltage U N Comparison yields voltage drop ; The second low voltage ride through control module, when low voltage ride through occurs, according to the voltage drop The low voltage ride through control is carried out, the negative sequence reactive power is set to 0, that is, the negative sequence theoretical reactive reference current , the negative sequence theoretical reactive current , the negative sequence actual reactive current Is set to 0; the power factor is set to 1, according to the voltage drop The low voltage ride through control is carried out; then the negative sequence theoretical active reference current , the negative sequence theoretical active current , the negative sequence actual active current The maximum difference , the maximum difference As the initial suitable current I rective The fifth PI controller is input, and the fifth PI controller generates the negative sequence active DC reference voltage , the ratio of the suitable current I rective To the total current I total Rises gradually to 20%, the voltage drop And the voltage U N The ratio reaches 10% and starts to rise; the negative sequence theoretical reactive reference current , the negative sequence theoretical reactive current , the negative sequence actual reactive current , the negative sequence reactive DC reference current The maximum difference , the maximum difference The sixth PI controller is input, and the sixth PI controller generates the negative sequence reactive DC reference voltage , the maximum difference And the maximum difference Synthesis as suitable current I rective , the voltage drop And the voltage U N The ratio gradually rises from 10% to 20%, under the continuous injection of the maximum difference And the maximum difference , the current ratio I rective / I total Gradually rises from 20% to 45%, the inverter keeps uninterrupted operation for 1s, the power factor starts to decline from 1, / Gradually rises to 50%, the suitable current I rective Reaches I total From 0 in 4s, the power factor drops to 0, the negative sequence active current normally injects negative sequence active power to the power grid, and the negative sequence reactive voltage of the negative sequence reactive power is limited.

7. A control method of one-stop intelligent megawatt box system based on TE-SVM modulation, characterized in that, The intelligent controller of the one-stop intelligent megawatt box system based on TE-SVM modulation according to claim 6 is used in the following steps: Step S1, receive the actual active power and actual reactive power at the grid connection point, the three-phase voltage V a b c the three-phase voltage V ga gb gc the three-phase average voltage the three-phase current I a b c the three-phase average current I aavg bavg cavg the DC bus capacitor voltage U bus the photovoltaic array output current I pv the average current I pvavg and use the MPPT controller to track the maximum power of the DC / DC converter, output the positive sequence DC reference voltage U ref + and the DC reference current ;​​​​​​​​​​ Step S2, calculate the standard active power and the standard reactive power, and the active power instantaneous value and the reactive power instantaneous value at the grid point; Step S3, determine whether the actual active power and the actual reactive power at the grid point, the calculated active power instantaneous value and the calculated reactive power instantaneous value at the grid point, and the standard active power and the standard reactive power correspond to each other, and whether the frequency output by the phase-locked loop is within the range of 50±0.1 Hz; Step S4, when the actual active power and the actual reactive power at the grid point, the calculated active power instantaneous value and the calculated reactive power instantaneous value at the grid point, and the standard active power and the standard reactive power correspond to each other, and the frequency output by the phase-locked loop is within the range of 50±0.1 Hz, the frequency output by the phase-locked loop is taken as the wave generation frequency of the SVM wave generation module; otherwise, the frequency of the smart grid is searched by using the TLS-ESPRIT frequency estimation module, and the searched frequency is taken as the wave generation frequency of the SVM wave generation module; Step S5, according to the voltage, current signal received in step S1, calculate three-phase standard voltage 、 、 , three-phase standard current 、 、 , standard active power and standard reactive power, active power instantaneous value and reactive power instantaneous value at the point of interconnection, using two-phase positive sequence static voltage transformation module and two-phase negative sequence static voltage transformation module to get two-phase positive sequence static voltage U α +, U β + and two-phase negative sequence static voltage U α -, U β -; using SVM wave generation module to synthesize reference voltage according to two-phase positive sequence static voltage U α +, U β + and two-phase negative sequence static voltage U α -, U β -, then based on the wave generation frequency and reference voltage to carry out SVM wave generation, voltage equalization gate controller generates vector signal according to the SVM wave generation, using SVPWM modulation to control each switching module of the inverter to open or close.

8. The control method of a one-stop intelligent megawatt box system based on TE-SVM modulation according to claim 7, wherein, In the step S5, The three-phase standard voltage is calculated according to formula (1) , , : ；（1） where V p is the positive sequence voltage peak value, V n is the negative sequence voltage peak value, φ1 is the positive sequence voltage initial phase angle, φ2 is the negative sequence voltage initial phase angle; ω is the fundamental voltage angular frequency; Three-phase standard current , , According to formula (2): ；（2） where I p is the positive sequence current peak value, I n is the negative sequence current peak value, θ p is the positive sequence current phase relative to the positive sequence voltage starting angle, θ n is the negative sequence current phase relative to the negative sequence voltage starting angle; The positive and negative sequence impedance is calculated when the first low voltage ride through module and the second low voltage ride through module perform droop control in the step S5, wherein: Positive sequence impedance Z P (S) is calculated according to equation (3): ；（3） wherein K m is the inverter voltage gain, V dc is the DC bus capacitor voltage difference, is the closed-loop transfer function of the current inner loop PI controller, i.e., the first PI controller, is the closed-loop transfer function of the phase-locked loop, f1 is the fundamental frequency, is the gain of the weighting function, is the integral proportionality parameter, is the equivalent transfer function of the current filter composed of the first low-pass filter LPF and the first band-pass filter BPF, is the inductance value of the inverter-side inductance of the LCL filter, is the DC bus capacitance value; is the equivalent transfer function of the voltage filter composed of the second low-pass filter LPF and the second band-pass filter BPF, s represents the complex frequency domain, is the fundamental current initial phase angle, is the fundamental current peak value, is the grid voltage peak value; The standard active power and the standard reactive power are calculated according to the formula (7)~(8): ；（7） ；（8） wherein is the standard active power, is the standard reactive power, , is the corresponding voltage in the stationary reference frame, , is the corresponding current in the stationary reference frame, is the initial angle of the grid actual current with respect to the voltage, is the initial angle of the phase locked loop output; The active power instantaneous value and the reactive power instantaneous value at the grid-connected point are calculated according to the formula (9): ；（9） wherein, is the fundamental active power instantaneous value, is the fundamental reactive power instantaneous value; V p is the positive sequence voltage peak value, V n is the negative sequence voltage peak value; I p is the positive sequence current peak value, I n is the negative sequence current peak value, θ p is the starting angle of the positive sequence current with respect to the positive sequence voltage, θ n is the starting angle of the negative sequence current with respect to the negative sequence voltage; The step S5 synthesizes the vector reference voltage according to the following formula : （13）。 9. One stop smart megawatt box system based on TE-SVM modulation characterized in that, It comprises: A photovoltaic array for generating solar power and outputting electric energy; At least two inverter integrated megawatt boxes for sequentially collecting, step-down converting and inverting the direct current output by the photovoltaic array and outputting three-phase alternating current; At least two SVM controllers corresponding to the inverters of all the inverter integrated megawatt boxes, each SVM controller performing inverting control on the inverter connected thereto based on TE-SVM modulation; the SVM controller is the intelligent controller according to any one of claims 1-6; A power switching module for automatically switching all the inverter integrated megawatt boxes connected thereto so that only one inverter integrated megawatt box supplies power to the smart grid at the same time; A measurement and control power cabinet for performing master-slave competition control on all the inverter integrated megawatt boxes according to the frequency, amplitude and phase of the three-phase alternating current output by the inverters of all the inverter integrated megawatt boxes and the temperature detection results of each switching module of all the inverters, and selecting the best one among all the inverter integrated megawatt boxes in real time by adopting the first competition ranking standard, taking the currently selected best one as the master inverter and the remaining inverter integrated megawatt boxes as slave inverters, controlling the double power switching device corresponding to the master inverter to work and automatically switch so that the master inverter supplies power to the smart grid; A step-up transformer for step-up converting the three-phase alternating current output by the double power switching device corresponding to the master inverter integrated megawatt box and inputting the step-up converted three-phase alternating current into the smart grid; Wherein: The power switching module is composed of at least one double power switching device, each double power switching device corresponding to two inverter integrated megawatt boxes, and each double power switching device automatically switching the two inverter integrated megawatt boxes connected thereto according to the control signal when working.

10. The TE-SVM modulation based one-stop smart megawatt box system according to claim 9, wherein, It further comprises a group of intelligent electric energy meters arranged at the common point of the smart grid; Each inverter integrated megawatt box comprises: A collecting box for collecting the output of the photovoltaic array, the collecting box being provided with a first circuit breaker on each connection line of the photovoltaic array; A DC / DC conversion module for step-down converting the direct current output by the collecting box; A direct current bus capacitor for filtering the direct current output by the DC / DC conversion module and using the filtered direct current as a direct current power supply; A three-bridge-arm inverter for DC / AC converting the step-down converted direct current and outputting three-phase alternating current; An LCL filter for filtering the three-phase alternating current output by the three-bridge-arm inverter; The output end of the SVM controller is connected with the input end of the measurement and control power cabinet through a matching cloud manager. The grid side of each of the inverter integrated megawatt boxes is provided with a second circuit breaker, and the three-phase lines of the output end of the second circuit breaker are divided into two paths, one of which is connected to a third circuit breaker, and the third circuit breaker is connected to a measurement and control power supply cabinet, and the other path of the three-phase lines of the output end of the second circuit breaker is connected to a corresponding double power supply switching device.

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