Photovoltaic grid-tie control apparatus, system, method and controller

Abstract

The present disclosure provides a photovoltaic grid-connected control device, system, method and controller, relating to the field of power electronics. The device comprises: a controller, and a voltage converter, an inverter and a low-pass filter in cascade, wherein the input end of the voltage converter is configured to access a photovoltaic device; the output end of the low-pass filter is configured to access a power grid, wherein the filter capacitor of the low-pass filter is configured to be connected in parallel with a non-critical load; and the controller is configured to control the switching drive signal of the inverter to adjust the power of the non-critical load, so that the grid-connected active power output by the low-pass filter tracks the grid-connected active power reference value. The present disclosure can widely adjust the power of the non-critical load to accommodate the power fluctuation of photovoltaic power generation. In addition, unlike the target of voltage stabilization, the control target of the present disclosure is the relative constancy of photovoltaic grid-connected power, which is more suitable for power generation grid-connected application and suppresses the influence of photovoltaic power fluctuation from the source.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to the field of power electronics, and in particular to a photovoltaic grid-connected control device, system, method and controller. BACKGROUND

[0002] With the large-scale promotion of distributed photovoltaic power generation, photovoltaic power generation has defects such as intermittency, randomness and volatility, which causes a severe test on the power and frequency stability of the power grid. In the related art, the power spring is applied to the power system, which can not only realize voltage and frequency regulation, system power factor correction, harmonic suppression and the like to improve power quality, but also can reduce power imbalance, reduce energy storage demand, relieve three-phase imbalance of the power grid and enhance the elasticity of the power system and the like.

[0003] The power spring can be widely distributed in any node in the power grid, as long as there is a non-critical load with a wide voltage range, the power spring can be connected in series with the non-critical load to form an intelligent load to ensure the stability of the voltage of the critical load.

[0004] However, in the related art, the power spring is directly connected in series with the non-critical load, and the compensation capacity or range is limited, and the overvoltage suppression effect is poor in the pure reactive power compensation mode. Moreover, the control target of the existing power spring is the voltage stability of the grid-connected point, and it cannot adapt to the regulation of the grid-connected power of photovoltaic power generation. SUMMARY

[0005] One of the technical problems to be solved by the present disclosure is to provide a photovoltaic grid-connected control device, system, method and controller, which can make the grid-connected active power of the entire topology relatively constant.

[0006] According to an aspect of the present disclosure, a photovoltaic grid-connected control device is provided, comprising: a controller, and a voltage converter, an inverter and a low-pass filter connected in sequence, wherein the input end of the voltage converter is configured to access a photovoltaic device; the output end of the low-pass filter is configured to access a power grid, wherein the filter capacitor of the low-pass filter is configured to be connected in parallel with a non-critical load; and the controller is configured to control the switch driving signal of the inverter to regulate the power of the non-critical load, so that the grid-connected active power output by the low-pass filter tracks a grid-connected active power reference value.

[0007] In some embodiments, the controller is configured to control the switch driving signal of the inverter according to the grid-connected active power reference value P g_ref , a first voltage signal v g and a first current signal i g at the output end of the low-pass filter, a second voltage signal V bus at the DC bus side of the inverter and a voltage reference value V bus_ref , and an inductor value L t in the low-pass filter.

[0008] In some embodiments, the controller is configured to obtain voltage components in an αβ coordinate system according to the grid-connected active power reference value P g_ref , the first voltage signal v g , the first current signal i g , the second voltage signal V bus , the voltage reference value V bus_ref , and an inductor value L t in a low-pass filter; obtain a grid voltage feed-forward component v g according to the first voltage signal v ff(s) and a feed-forward function G f ; and obtain the switching drive signal according to the voltage components in the αβ coordinate system and the grid voltage feed-forward component v f .

[0009] In some embodiments, the controller is configured to obtain first and second current components I g and I g in a dq coordinate system according to the first voltage signal v d and the first current signal i q ; obtain first and second reference voltage values V bus and V bus_ref in the dq coordinate system according to the second voltage signal V g_ref , the voltage reference value V d_ref , and the grid-connected active power reference value P q_ref ; obtain first and second voltage components V d and V q in the dq coordinate system according to the first current component I d_ref , the second current component I q_ref , the first reference voltage value V t , and the second reference voltage value V d , and an inductor value L q in a low-pass filter; and obtain α and β voltage components v d and v q in an αβ coordinate system according to the first voltage component V α and the second voltage component V β .

[0010] In some embodiments, the controller is configured to input the first voltage signal v g to a phase-locked loop to obtain a grid voltage amplitude V g , a phase θ, and a fundamental frequency ω; obtain a β current component i β in the αβ coordinate system based on the β voltage component v g , the first voltage signal v g_β; and a first current component I g , a phase θ, and a β current component i g_β , to obtain a first current component I d and a second current component I q in the dq coordinate system.

[0011] In some embodiments, the controller is configured to: input a first voltage signal v g to a phase-locked loop to obtain a grid-connected voltage amplitude V g , a phase θ, and a fundamental frequency ω; and according to a first current signal i g , a phase θ, to obtain a first current component I d and a second current component I q in the dq coordinate system.

[0012] In some embodiments, the controller is configured to: perform proportional-integral (PI) control on a difference between a voltage reference value V bus_ref and a second voltage signal V bus , and pass the result through a limiter and a holder to obtain a second reference current I q_ref in the dq coordinate system; perform PI control on a difference between the second reference current I q_ref and the second current component I q , and pass the result through a limiter to obtain a second reference voltage value V q_ref ; divide a grid-connected active power reference value P g_ref by a grid-connected voltage amplitude V g , and pass the result through a limiter and a holder to obtain a first reference current I d_ref in the dq coordinate system; perform PI control on a difference between the first reference current I d_ref and the first current component I d , and pass the result through a limiter to obtain a first reference voltage value V d_ref .

[0013] In some embodiments, the controller is configured to: obtain, according to a first current component I d and an inductor value L t in a low-pass filter, a first voltage value V dt corresponding to the inductor in the dq coordinate system; perform difference operation on a second reference voltage value V q_ref and the first voltage value V dt to obtain a second voltage component V q ; obtain, according to a second current component I q and the inductor value L t in the low-pass filter, a second voltage value V qt corresponding to the inductor in the dq coordinate system; and perform difference operation on a first reference voltage value V d_ref and the second voltage value V qta first voltage signal v d .

[0014] In some embodiments, the low-pass filter is an LCL type low-pass filter; the inverter is a single-phase inverter or a three-phase inverter; or the voltage converter is a Boost converter.

[0015] According to another aspect of the present disclosure, a photovoltaic grid-connected control system is also provided, comprising: the photovoltaic grid-connected control device as described above; and a photovoltaic device.

[0016] According to another aspect of the present disclosure, a control method of the photovoltaic grid-connected control device as described above is also provided, comprising: obtaining a first voltage signal v g and a first current signal i g at an output end of a low-pass filter, and a second voltage signal V bus at a DC bus side of an inverter; generating a switch driving signal of the inverter according to the first voltage signal v g , the first current signal i g , and the second voltage signal V bus ; and feeding back the switch driving signal of the inverter to adjust power of a non-critical load, so that grid-connected active power output by the low-pass filter tracks a grid-connected active power reference value.

[0017] In some embodiments, generating the switch driving signal of the inverter comprises: generating the switch driving signal of the inverter according to the grid-connected active power reference value P g_ref , the first voltage signal v g and the first current signal i g at the output end of the low-pass filter, the second voltage signal V bus and a voltage reference value V bus_ref at the DC bus side of the inverter, and an inductor value L t in the low-pass filter.

[0018] In some embodiments, according to the grid-connected active power reference value P g_ref , the first voltage signal v g , the first current signal i g , the second voltage signal V bus , the voltage reference value V bus_ref , and the inductor value L t in the low-pass filter, a voltage component in an αβ coordinate system is obtained; according to the first voltage signal v g and a feedforward function G ff(s) , a grid voltage feedforward component v f is obtained; and according to the voltage component in the αβ coordinate system and the grid voltage feedforward component v f , the switch driving signal is obtained.

[0019] In some embodiments, the first voltage signal v g and the first current signal i g , a first current component I d and a second current component I q in the dq coordinate system are obtained; the second voltage signal V bus , the voltage reference value V bus_ref and the grid-connected active power reference value P g_ref , a first reference voltage value V d_ref and a second reference voltage value V q_ref in the dq coordinate system are obtained; the first current component I d , the second current component I q , the first reference voltage value V d_ref and the second reference voltage value V q_ref , and the inductor value L t in the low-pass filter, a first voltage component V d and a second voltage component V q in the dq coordinate system are obtained; and the first voltage component V d and the second voltage component V q , an α voltage component v α and a β voltage component v β in the αβ coordinate system are obtained.

[0020] In some embodiments, the first voltage signal v g is input to a phase-locked loop to obtain a grid-connected voltage amplitude V g , a phase θ and a fundamental frequency ω; based on the β voltage component v β , the first voltage signal v g , a β current component i g_β in the αβ coordinate system is obtained; and according to the first current signal i g , the phase θ and the β current component i g_β , the first current component I d and the second current component I q in the dq coordinate system are obtained.

[0021] In some embodiments, the first voltage signal v g is input to a phase-locked loop to obtain a grid-connected voltage amplitude V g , a phase θ and a fundamental frequency ω; and according to the first current signal i g , the phase θ, the first current component I d and the second current component I q in the dq coordinate system are obtained.

[0022] In some embodiments, the voltage reference value V bus_ref is compared with the second voltage signal Vbus The difference is used for proportional-integral PI control, and after passing through a limiter and a hold circuit, the second reference current I in the dq coordinate system is obtained. q_ref ; the second reference current I q_ref With the second current component I q The difference is used for PI control, and after limiting, the second reference voltage value V is obtained. q_ref The grid-connected active power reference value P g_ref Divide by grid voltage amplitude V g After passing through a limiter and a holding circuit, the first reference current I in the dq coordinate system is obtained. d_ref ; Set the first reference current I d_ref With the first current component I d The difference is used for PI control, and after limiting, the first reference voltage value V is obtained. d_ref .

[0023] In some embodiments, based on the first current component I d and the inductor value L in the low-pass filter t The first voltage value V corresponding to the inductor in the dq coordinate system is obtained. dt ; set the second reference voltage value V q_ref With the first voltage value V dt Perform the difference operation to obtain the second voltage component V. q According to the second current component I q and the inductor value L in the low-pass filter t The second voltage value V corresponding to the inductor in the dq coordinate system is obtained. qt ; set the first reference voltage value V d_ref With the second voltage value V qt By performing a summation operation, the first voltage component V is obtained. d .

[0024] According to another aspect of this disclosure, a controller is also proposed, comprising: a memory; and a processor coupled to the memory, the processor being configured to execute the control method as described above based on instructions stored in the memory.

[0025] According to another aspect of this disclosure, a non-transitory computer-readable storage medium is also proposed, on which computer program instructions are stored, which, when executed by a processor, implement the control method described above.

[0026] In the embodiments of the present disclosure, not only can the non-critical load power be widely adjusted to accommodate the power fluctuation of photovoltaic power generation, but also the inherent resonance peak of the filter itself can be suppressed to avoid resonance instability of the system grid connection and reduce the grid-connected harmonic content, so as to ensure the relatively constant grid-connected active power. Unlike the voltage stability as the target, the control target of the present disclosure is the relatively constant photovoltaic grid-connected power, which is more suitable for power generation grid connection application and suppresses the influence of photovoltaic power fluctuation from the source. In addition, by adjusting the impedance ratio of the non-critical load and the grid inductance, the present disclosure can adapt to different impedance characteristics of the power grid scene.

[0027] Other features of the present disclosure and its advantages will become apparent from the following detailed description of exemplary embodiments of the present disclosure with reference to the drawings. BRIEF DESCRIPTION OF DRAWINGS

[0028] The accompanying drawings, which form a part of the specification, illustrate embodiments of the present disclosure and, together with the description, serve to explain the principles of the present disclosure.

[0029] The present disclosure can be understood more readily by reference to the following detailed description of exemplary embodiments of the present disclosure and the attached drawings, of which:

[0030] Figure 1 Structure schematic diagram of some embodiments of photovoltaic grid-connected control device of the present disclosure;

[0031] Figure 2A Structure schematic diagram of some other embodiments of photovoltaic grid-connected control device of the present disclosure;

[0032] Figure 2B Structure schematic diagram of some other embodiments of photovoltaic grid-connected control device of the present disclosure;

[0033] Figure 3 Curve schematic diagram in some embodiments of the present disclosure;

[0034] Figure 4 Curve schematic diagram in some other embodiments of the present disclosure;

[0035] Figure 5 Schematic diagram of some embodiments of grid-connected power tracking control model of the present disclosure;

[0036] Figure 6 Schematic diagram of some other embodiments of grid-connected power tracking control model of the present disclosure;

[0037] Figure 7 Flow schematic diagram of some embodiments of control method of photovoltaic grid-connected control device of the present disclosure;

[0038] Figure 8 Flow schematic diagram of some other embodiments of control method of photovoltaic grid-connected control device of the present disclosure;

[0039] Figure 9 Flowchart of another embodiment of the control method of the photovoltaic grid-connected control device of the present disclosure;

[0040] Figure 10 Flowchart of another embodiment of the control method of the photovoltaic grid-connected control device of the present disclosure; and

[0041] Figure 11 Structural diagram of some embodiments of the controller of the present disclosure. DETAILED DESCRIPTION

[0042] Various exemplary embodiments of the present disclosure will now be described in detail below with reference to the accompanying drawings. Note that the relative arrangement, numerical expressions, and numerical values of the components and steps set forth in these embodiments are not limiting to the scope of the present disclosure unless specifically stated otherwise.

[0043] Meanwhile, it should be understood that the sizes of the various portions shown in the drawings are not drawn to actual scale for ease of description.

[0044] The following description of at least one exemplary embodiment is merely illustrative in nature and is in no way limiting to the scope of the disclosure and its applications or uses.

[0045] Techniques, methods, and devices known to those of ordinary skill in the relevant art can not be discussed in detail herein. However, where appropriate, such techniques, methods, and devices can be considered part of the described technology.

[0046] In all examples shown and discussed herein, any specific values should be interpreted as merely illustrative and not as limiting. Thus, other examples of the exemplary embodiments can have different values.

[0047] Note that similar reference numerals and letters refer to like items in the following drawings, and thus, once an item is defined in one drawing, it need not be discussed further in subsequent drawings.

[0048] In order to make the purposes, technical solutions, and advantages of the present disclosure clearer, the present disclosure is further described in detail below with reference to specific embodiments and in conjunction with the accompanying drawings.

[0049] The present disclosure can transfer the power fluctuation of distributed photovoltaic power generation to non-critical loads, reducing the impact on the power grid after grid connection.

[0050] Figure 1 Structural diagram of some embodiments of the photovoltaic grid-connected control device of the present disclosure. The device includes a controller 1, and a voltage converter 2, an inverter 3, and a low-pass filter 4 connected in cascade.

[0051] The input terminal of the voltage converter 2 is configured to be connected to the photovoltaic device 5; the output terminal of the low-pass filter 4 is configured to be connected to the power grid, wherein the filter capacitor of the low-pass filter 4 is configured to be connected in parallel with the non-critical load; the controller 1 is configured to control the switching drive signal of the inverter 3 to adjust the power of the non-critical load, so that the grid-connected active power output of the low-pass filter tracks the grid-connected active power reference value.

[0052] In some embodiments, the loads of end users in a distribution network can be divided into critical loads (CL) that are sensitive to voltage fluctuations and noncritical loads (NCL) with a wide operating voltage range. Noncritical loads are widely found in industrial loads such as electric arc furnaces, boilers, electric chillers, and ice storage air conditioners; thermal comfort loads of buildings such as heating and cooling systems; and energy storage devices such as electricity, gas, heat, and cold storage devices.

[0053] In some embodiments, the photovoltaic device includes multiple photovoltaic arrays.

[0054] In some embodiments, voltage converter 2 is a Boost converter, inverter 3 is a single-phase inverter or a three-phase inverter, and low-pass filter 4 is an LCL type low-pass filter.

[0055] like Figure 2A As shown, the voltage converter 2 includes: a first capacitor C bus Diode D, fifth switch K, and first inductor L i First capacitor C bus The first terminal is connected to the first input terminal of inverter 3, and the first capacitor C bus The second terminal of diode D is connected to the second input terminal of inverter 3. The cathode of diode D is connected to the first capacitor C. bus The first terminal of the fifth switch K is connected to the positive terminal of diode D, and the second terminal of the fifth switch K is connected to the first capacitor C. bus The second terminal is connected and serves as the second input terminal of voltage converter 2. The first inductor L... i The first terminal serves as the first input terminal of voltage converter 2, and the first inductor L i The second terminal is connected to the positive terminal of diode D. The voltage converter 2 also includes a second capacitor C disposed between the first input terminal and the second input terminal. pv The second capacitor C pv It is connected in parallel with photovoltaic array 5.

[0056] Taking single-phase electricity as an example, inverter 3 includes a first switch S1, a second switch S2, a third switch S3, and a fourth switch S4. The first terminal of the first switch S1 is connected to the first terminal of the third switch S3, and the second terminal of the first switch S1 is connected to the first terminal of the second switch S2, serving as the first output terminal of inverter 3. The second terminal of the second switch S2 is connected to the first terminal of the fourth switch S4, and the second terminal of the third switch S3 is connected to the second terminal of the fourth switch S4, serving as the second output terminal of inverter 3. The first terminal of the third switch S3 serves as the first input terminal of inverter 3, and the first terminal of the fourth switch S4 serves as the second input terminal of inverter 3.

[0057] The low-pass filter 4 includes: a first inductor L ff Second inductor L gf and filter capacitor C f First inductor L ff The first terminal is connected to the first output terminal of inverter 3, and the first inductor L ff The second terminal and the second inductor L gf The first end is connected. The second inductor L... gf The second terminal serves as the first output terminal of low-pass filter 4. Filter capacitor C f The first terminal and the first inductor L ff The second terminal is connected to the filter capacitor C. f The second terminal serves as the second output terminal of the low-pass filter 4 and is connected to the second output terminal of the inverter 3. Non-critical load R ncl Parallel connection to filter capacitor C f The two ends of the low-pass filter 4 are connected to the grid at connection points L and N. The power grid at the connection points can be equivalent to a voltage source V. g .

[0058] In some embodiments, non-critical load R ncl First inductor L ff Second inductor L gf and filter capacitor C f This forms a passive damped LCL low-pass filter to filter out high-frequency components in the output voltage of inverter 3. Non-critical load R ncl By using the filter capacitor C f Passive dampers connected in parallel to form an LCL low-pass filter can suppress the frequency response resonance spikes of the LCL low-pass filter to prevent resonance during grid connection with the power system, which could lead to system instability. They can also form a topological critical structure to automatically adjust the power of non-critical loads under control to absorb power fluctuations in photovoltaic power generation and ensure relatively constant active power connected to the grid.

[0059] Taking three-phase electricity as an example, such as Figure 2BThe voltage transformer 2 is not shown in the figure, and the inverter 3 includes a first switch S1, a second switch S2, a third switch S3, a fourth switch S4, a fifth switch S5, and a sixth switch S6. The first end of the first switch S1 is connected with the first end of the third switch S3 and the first end of the fifth switch S5, the second end of the first switch S1 is connected with the first end of the second switch S2 and serves as the first output end of the inverter 3. The second end of the third switch S3 is connected with the first end of the fourth switch S4 and serves as the second output end of the inverter 3, the second end of the fifth switch S5 is connected with the first end of the sixth switch S6 and serves as the third output end of the inverter 3. The second end of the second switch S2 is connected with the second end of the fourth switch S4 and the second end of the sixth switch S6. The first end of the first switch S1 serves as the first input end of the inverter 3, and the second end of the second switch S2 serves as the second input end of the inverter 3.

[0060] The low-pass filter 4 includes a first inductor L ff , a second inductor L gf , and a filter capacitor C f . Since this embodiment involves three-phase electricity, the first inductor L ff , the second inductor L gf , and the filter capacitor C f each have three elements and are arranged on three lines. The first inductor L ff is connected with the three output ends of the inverter 3 through the three-phase line, one end of the second inductor L gf is connected with the first inductor L ff on the corresponding phase line, and the other end is connected to the power grid side. The filter capacitor C f is arranged between the first inductor L ff and the second inductor L gf , and the filter capacitor C f on each phase line is connected in parallel with the non-critical load R ncl .

[0061] Those skilled in the art should understand that the structures of the voltage transformer, the inverter, and the low-pass filter in the above embodiment are only for example, and the voltage transformer, the inverter, and the low-pass filter can also have various structures.

[0062] The circuit topology of the present disclosure is reasonably configured in design, which can improve the range of non-critical load to accommodate photovoltaic power fluctuation. Details will be introduced below.

[0063] In some embodiments, taking the reference direction of the grid-connected current flowing out of the grid-connected point as the reference direction, according to Kirchhoff's voltage law, the grid-connected point voltage phasor V g , the grid-connected current phasor I gf flowing through the second inductor L g , and the terminal voltage phasor Vncl The phasor relationship between them is V ncl =V g -I g ·jωL gf The effective value V of the voltage of a non-critical load can be obtained using the law of cosines. ncl for: in For I g Lag V g The phase.

[0064] Ignoring other system losses, the output power of photovoltaic array 5 is equal to the output power of voltage converter 2, equal to the output active power of single-phase inverter 3, and equal to the input power of low-pass filter 4. If the power reference value is used, then the per-unit power value for non-critical loads is... Per-unit value of grid-connected active power Per-unit value of grid-connected reactive power and per-unit value of photovoltaic power generation The relationship between them is: Where a=ωL gf / R ncl .

[0065] From the above formula derivation, it can be seen that when the photovoltaic power... When fluctuations occur, the grid-connected reactive power can be adjusted through appropriate control methods. This ensures the active power of grid connection. The constant. And the grid-connected reactive power. per-unit power values ​​for non-critical loads In other words, by adjusting the power of non-critical loads, the grid-connected active power of the entire topology can be kept relatively constant.

[0066] In addition, with Figure 3 and Figure 4 per-unit power values ​​for non-critical loads, for example Per-unit value of grid-connected active power Per-unit value of grid-connected reactive power and per-unit value of photovoltaic power generation The relationship surface diagram shows that when parameter a varies within a certain range, i.e. through the grid-connected inductor L... gf Inductive reactance and non-critical load R nclThe ratio of the inductor value L and the impedance value Z can change the power relationship surface characteristics of the system. When the parameter a is 1, in order to ensure that the active power is constant at 1, the reactive power range is-0.5-1.5, which corresponds to the range of photovoltaic power fluctuation that can be suppressed is 0-8, when the parameter a is 1.2, the range of photovoltaic power fluctuation that can be suppressed is 0-20, and with the increase of a, the ability to suppress photovoltaic power fluctuation is stronger. However, due to the limitation of grid impedance, a cannot be increased indefinitely. The series type power spring is fixed in active and reactive characteristics because the sum of the output voltage of the inverter and the voltage of the non-critical load is equal to the grid voltage, so the active and reactive characteristics cannot be changed by adjusting the a parameter. Compared with the series relationship of the power spring, the present disclosure can improve the range of non-critical load to accommodate photovoltaic power fluctuation by reasonably configuring a in the design. Moreover, by adjusting the impedance ratio of the non-critical load and the grid inductance, the distribution ratio of active power and reactive power can be adjusted, and then different grid scenarios with different impedance characteristics can be adapted.

[0067] In some embodiments of the present disclosure, the controller 1 is configured to control the switching drive signal of the inverter 3 according to the grid active power reference value P g_ref , the first voltage signal v g and the first current signal i g at the output end of the low-pass filter 4, the second voltage signal V bus at the DC bus side of the inverter 3 and the voltage reference value V bus_ref , and the inductor value L t in the low-pass filter 4. By turning on and off the switches of the inverter 3, the current output by the low-pass filter 4 can be adjusted, and then the power of the non-critical load can be adjusted, so that the grid active power output by the low-pass filter 4 tracks the grid active power reference value.

[0068] In some embodiments, for single-phase power, such as Figure 5 , the controller 1 is configured to obtain the α voltage component v α and the β voltage component v β in the αβ coordinate system according to the grid active power reference value P g_ref , the first voltage signal v g , the first current signal i g , the second voltage signal V bus , the voltage reference value V bus_ref , and the inductor value L t in the low-pass filter; obtain the grid voltage feedforward component v f according to the first voltage signal v g and the feedforward function G ff(s) ; and obtain the switching drive signal according to the α voltage component v α and the grid voltage feedforward component v f . The inductor value Lt an inductance value L of the first inductor ff and an inductance value L of the second inductor gf . The feedforward function G ff(s) is The purpose of setting the feedforward function G g (s) is to eliminate the influence of the grid voltage v g (s) on the current i

[0069] In some embodiments, according to the first voltage signal v g and the first current signal i g , a first current component I d and a second current component I q in a dq coordinate system are obtained.

[0070] For example, as shown in FIG. 1, the first voltage signal v g is input to a phase locked loop (PLL) to obtain a grid voltage amplitude V g , a phase θ and a fundamental frequency ω; based on the β voltage component v β , the grid voltage amplitude V g , a β current component i g_β in an αβ coordinate system is obtained; according to the first current signal i g , the phase θ and the β current component i g_β , a first current component I d and a second current component I q in a dq coordinate system are obtained.

[0071] In some embodiments, a first current component I d and a second current component I q in a dq coordinate system are obtained through a fictitious axis emulator (FAE) and coordinate transformation. In the phase locked loop, the grid voltage v g is an α-axis component v g_α = V g ·sinθ, and a β-axis component v g_β = V g ·sin(θ-π / 2) can be obtained after a phase lag of π / 2. In the FAE, a β-axis main circuit composed of an inverter, a low-pass filter and a non-critical load in the topology is simulated by an s function, wherein a delay function e -T is used to consider the modulation delay effect of the inverter, and K pwm is used to consider the modulation proportion coefficient; after inputting a modulation signal v β and a β-axis grid voltage signal v g_β to the FAE, a β-axis component i g_β of the grid current can be obtained.g_β After transformation from the αβ stationary coordinate system to the dq rotating coordinate system (with a rotational angular velocity of θ), i g_α and i g_β It can be converted into d-axis and q-axis components I d and I q In the above steps, converting the AC signal into a DC stationary component is beneficial for subsequent control operations.

[0072] In some embodiments, according to the second voltage signal V bus Voltage reference value V bus_ref and the grid-connected active power reference value P g_ref The first reference voltage value V in the dq coordinate system is obtained. d_ref Second reference voltage value V q_ref .

[0073] For example, such as Figure 5 As shown, the voltage reference value V bus_ref With the second voltage signal V bus The difference is used for PI (proportional-integral) control, and after passing through a limiter and a hold circuit, the second reference current I in the dq coordinate system is obtained. q_ref ; the second reference current I q_ref With the second current component I q The difference is used for PI control, and after limiting, the second reference voltage value V is obtained. q_ref The grid-connected active power reference value P g_ref Divide by grid voltage amplitude V g After passing through a limiter and a holding circuit, the first reference current I in the dq coordinate system is obtained. d_ref ; Set the first reference current I d_ref With the first current component I d The difference is used for PI control, and after limiting, the first reference voltage value V is obtained. d_ref The hold is, for example, a zero-order hold.

[0074] In some embodiments, based on the first current component I d Second current component I q First reference voltage value V d_ref Second reference voltage value V q_ref and the inductor value L in the low-pass filter t The first voltage component V in the dq coordinate system is obtained. d Second voltage component V q According to the first voltage component V d Second voltage component V q The α voltage component v in the αβ coordinate system is obtained. α and β voltage component v β .

[0075] For example, such as Figure 5 As shown, according to the first current component I d and the inductor value L in the low-pass filter t The first voltage value V corresponding to the inductor in the dq coordinate system is obtained. dt =ωI d (L gf +L ff ); Set the second reference voltage value V q_ref With the first voltage value V dt Perform the difference operation to obtain the second voltage component V. q According to the second current component I q and the inductor value L in the low-pass filter t The second voltage value V corresponding to the inductor in the dq coordinate system is obtained. qt =ωI q (L gf +L ff ); Set the first reference voltage value V d_ref With the second voltage value V qt By performing a summation operation, the first voltage component V is obtained. d .

[0076] For the first voltage component V d Second voltage component V q Perform a coordinate transformation to obtain the α voltage component v in the αβ coordinate system. α and β voltage component v β According to the α voltage component v α and grid voltage feedforward component v f The switch drive signal is obtained.

[0077] In the above embodiments, based on the grid-connected active power reference value P g_ref The first voltage signal v at the output of the low-pass filter g and the first current signal i g The second voltage signal V on the DC bus side of the inverter bus and voltage reference value V bus_ref and the inductor value L in the low-pass filter. t The control signal of the inverter is controlled to adjust the current output of the low-pass filter, thereby regulating the power of non-critical loads and ensuring that the grid-connected active power output of the low-pass filter tracks the grid-connected active power reference value. Unlike voltage stability, the control objective of this disclosure is to achieve relative constancy of the photovoltaic grid-connected power, making it more suitable for grid-connected power generation applications and suppressing the impact of photovoltaic power fluctuations at the source.

[0078] For three-phase electricity, such as Figure 6As shown, similar to single-phase electricity, in the first reference current I d_ref Second reference current I q_ref The preceding section is not shown. Controller 1 is configured to operate based on the grid-connected active power reference value P. g_ref First voltage signal v g First current signal i g Second voltage signal V bus Voltage reference value V bus_ref and the inductor value L in the low-pass filter. t The voltage component v in the αβ coordinate system is obtained. g_α and v g_β According to the first voltage signal v g and feedforward function G ff(s) The grid voltage feedforward component v is obtained. f ; and according to the voltage component v g_α and v g_β and grid voltage feedforward component v f The switch drive signal is obtained. The inductor value L t Equal to the inductance value L of the first inductor ff The inductance value L of the second inductor gf The sum. Since this embodiment is three-phase electricity, therefore, after obtaining the first current component I... d Second current component I q At that time, no β current component i is required. g_β That is, based on the first current signal i g Phase θ, to obtain the first current component I in the dq coordinate system. d Second current component I q .Should Figure 6 H in i and H v These are the sampling coefficients for current and voltage, respectively. For three-phase electricity, the first current signal i... g Including i g_a i g_b and i g_c First voltage signal v g Including v g_a v g_b and v g_c First voltage signal v g After sampling and coordinate transformation, the voltage value v in the αβ coordinate system can be obtained. g_α and v g_β .

[0079] In other embodiments of this disclosure, a photovoltaic grid-connected control system is also protected, the system including photovoltaic equipment and the photovoltaic grid-connected control device described in the above embodiments. For example... Figure 2AAs shown, the DC input end of the voltage transformer is connected in series with the photovoltaic device. Through this architecture, the power of the non-critical load is regulated to accommodate the power fluctuation of the photovoltaic power generation, so as to ensure the relatively constant grid-connected active power. In addition, the circuit topology of the present disclosure does not require an energy storage device, which can weaken the dependence of photovoltaic power generation on energy storage, reduce the increase of energy storage on the overall cost, and is conducive to the promotion of distributed photovoltaic in the distribution network, and has significant practical value. At the same time, the circuit topology of the present disclosure itself does not consume additional active power.

[0080] Figure 7 A flowchart of some embodiments of a control method of the photovoltaic grid-connected control device is shown, and the control method is executed by a controller.

[0081] In step 710, a first voltage signal v g and a first current signal i g at the output end of the low-pass filter are obtained. bus

[0082] In step 720, a switching drive signal of the inverter is generated according to the first voltage signal v g , the first current signal i g , and the second voltage signal V bus .

[0083] In some embodiments, the switching drive signal of the inverter is generated according to a grid-connected active power reference value P g_ref , the first voltage signal v g and the first current signal i g at the output end of the low-pass filter, the second voltage signal V bus at the DC bus side of the inverter, a voltage reference value V bus_ref , and an inductor value L t in the low-pass filter. The grid-connected active power reference value P g_ref , the voltage reference value V bus_ref , and the inductor value L t in the low-pass filter are known quantities.

[0084] For example, according to the grid-connected active power reference value P g_ref , the first voltage signal v g , the first current signal i g , the second voltage signal V bus , the voltage reference value V bus_ref , and the inductor value L t in the low-pass filter, the voltage component in the αβ coordinate system is obtained; according to the first voltage signal v g and the feedforward function G ff(s) , the grid voltage feedforward component v f ​; and based on the voltage component and the grid voltage feedforward component v f This yields the switch drive signal. For single-phase electricity, based on the α voltage component v... α and grid voltage feedforward component v f The switch drive signal is obtained; for three-phase electricity, based on the α voltage component v α β voltage component v β and grid voltage feedforward component v f The switch drive signal is obtained.

[0085] In step 730, a switching drive signal is sent to the inverter to adjust the power of non-critical loads so that the grid-connected active power output of the low-pass filter tracks the grid-connected active power reference value.

[0086] In the above embodiments, when the photovoltaic power generation fluctuates or changes within a certain range, by using reasonable control methods to adjust the power of non-critical loads, the grid-connected active power of the entire topology can be kept relatively constant. Unlike the voltage stability target, this is more suitable for power generation and grid connection applications, suppressing the impact of photovoltaic power fluctuations from the source.

[0087] In some embodiments of this disclosure, based on the first voltage signal v g and the first current signal i g The first current component I in the dq coordinate system is obtained. d Second current component I q For single-phase electricity, such as Figure 8 As shown.

[0088] In step 810, the first voltage signal v g The input is fed into the phase-locked loop to obtain the grid-connected voltage amplitude V. g Phase θ and fundamental frequency ω.

[0089] In step 820, based on the β voltage component v β Grid-connected voltage amplitude V g The β current component i in the αβ coordinate system is obtained. g_β .

[0090] In step 830, according to the first current signal i g Phase θ and β current component i g_β The first current component I in the dq coordinate system is obtained. d Second current component I q .

[0091] In some embodiments, in a phase-locked loop, the grid-connected voltage v is set... g For the α-axis component v g_α =V g The β-axis component v can be obtained by hysteresis sinθ and phase lag of π / 2.g_β = V g sin(θ-π / 2). In the FAE, the main circuit of the β axis composed of the inverter, the low-pass filter and the non-critical load is simulated by the s function, wherein the delay function e -T is used to consider the modulation delay effect of the inverter, and K pwm is used to consider the modulation proportion coefficient; the modulation signal v β and the grid voltage signal v g_β of the β axis are input into the FAE, and the β axis component i g_β of the grid-connected current can be obtained. g_α After the transformation from the αβ static coordinate system to the dq rotating coordinate system (the rotating angular velocity is θ), i g_β and i d can be converted into the d-axis and q-axis components I q and I g .

[0092] In the above steps, the alternating current signal is converted into the direct current static component, which is beneficial to the subsequent control operation.

[0093] If the three-phase current is used, according to the first current signal i d and the phase θ, the first current component I q and the second current component I bus in the dq coordinate system can be obtained. Step 820 does not need to be performed.

[0094] In some other embodiments of the present disclosure, according to the second voltage signal V bus_ref , the voltage reference value V g_ref and the grid-connected active power reference value P d_ref , the first reference voltage value V q_ref and the second reference voltage value V bus_ref in the dq coordinate system can be obtained. As shown in step 810. Figure 9

[0095] In step 910, the difference between the voltage reference value V bus and the second voltage signal V q_ref is subjected to PI control, and after the limiter and the keeper, the second reference current I q_ref in the dq coordinate system can be obtained.

[0096] In step 920, the difference between the second reference current I q and the second current component I q_ref is subjected to PI control, and after the limiter, the second reference voltage value V g_ref can be obtained.

[0097] In step 930, the grid-connected active power reference value P g is divided by the grid voltage amplitude VAfter passing through a limiter and a holding circuit, the first reference current I in the dq coordinate system is obtained. d_ref .

[0098] In step 940, the first reference current I is... d_ref With the first current component I d The difference is used for PI control, and after limiting, the first reference voltage value V is obtained. d_ref .

[0099] In some embodiments of this disclosure, based on the first current component I d Second current component I q First reference voltage value V d_ref Second reference voltage value V q_ref and the inductor value L in the low-pass filter t The first voltage component V in the dq coordinate system is obtained. d Second voltage component V q .like Figure 10 As shown.

[0100] In step 1010, according to the first current component I d and the inductor value L in the low-pass filter t The first voltage value V corresponding to the inductor in the dq coordinate system is obtained. dt .

[0101] For example, V dt =ωI d (L gf +L ff ).

[0102] In step 1020, the second reference voltage value V is... q_ref With the first voltage value V dt Perform the difference operation to obtain the second voltage component V. q .

[0103] In step 1030, according to the second current component I q and the inductor value L in the low-pass filter t The second voltage value V corresponding to the inductor in the dq coordinate system is obtained. qt .

[0104] For example, V qt =ωI q (L gf +L ff ).

[0105] In step 1040, the first reference voltage value V is... d_ref With the second voltage value V qt By performing a summation operation, the first voltage component V is obtained.d .

[0106] According to the first voltage component V d and the second voltage component V q , an alpha voltage component v α and a beta voltage component v β in an alpha-beta coordinate system are obtained. For single-phase power, according to the alpha voltage component v α and a grid voltage feedforward component v f , a switch driving signal is obtained. For three-phase power, according to the alpha voltage component v α , the beta voltage component v β and the grid voltage feedforward component v f , a switch driving signal is obtained.

[0107] If the non-critical load is not provided, due to the inherent resonance peak of the LCL filter, the amplitude gain is infinite at the resonance frequency, and the system will show instability. After the non-critical load is connected in parallel to the capacitor of the LCL filter and then controlled by the control system, the overall system can show good control performance.

[0108] In a normal case, the grid-connected power of photovoltaic power generation changes with the change of light intensity. When the light intensity decreases sharply, the grid-connected power of photovoltaic power generation decreases, and the grid-connected current of photovoltaic power also decreases. However, by using the circuit topology and control method of the present disclosure, when the light intensity decreases sharply, the power and voltage of the non-critical load decrease, but the grid-connected power of photovoltaic power generation changes little.

[0109] In some embodiments of the present disclosure, the circuit topology and control method of the present disclosure are applied to a certain building, for example, a roof is provided with a photovoltaic power generation system and a water heater, and the water heater is used as a non-critical load. When the light is sufficient and the photovoltaic power generation is excessive, the power of the water heater increases accordingly, and when the light is insufficient and the photovoltaic power generation is insufficient, the power of the water heater decreases accordingly. Ultimately, the grid-connected active power can be relatively constant, overcoming the uncertainty and random fluctuations of photovoltaic power generation power.

[0110] Figure 11 A structural schematic diagram of some embodiments of the controller of the present disclosure is shown in FIG. 11. The controller 1100 includes a memory 1110 and a processor 1120. The memory 1110 can be a disk, a flash memory or any other non-volatile storage medium. The memory is used to store the instructions in the above-mentioned corresponding embodiments. The processor 1120 is coupled to the memory 1110 and can be implemented as one or more integrated circuits, such as a microprocessor or a microcontroller. The processor 1120 is used to execute the instructions stored in the memory.

[0111] In some embodiments, the processor 1120 is coupled to the memory 1110 by a bus 1130. The controller 1100 can also be connected to an external storage system 1150 by a storage interface 1140 to call external data, and can be connected to a network or another computer system (not shown) by a network interface 1160. Details are not described here.

[0112] In this embodiment, the data instruction is stored in the memory, and the above-mentioned instruction is processed by the processor, and the power of the non-critical load is adjusted to make the grid-connected active power of the whole topology relatively constant. The disclosure can weaken the dependence of photovoltaic power generation on energy storage, reduce the increase of energy storage on the overall cost, and is beneficial to the promotion of distributed photovoltaic in the power distribution network, and has significant practical value.

[0113] In other embodiments, a computer readable storage medium has computer program instructions stored thereon, which, when executed by a processor, implement the steps of the method in the above-mentioned corresponding embodiments. Those skilled in the art should understand that the embodiments of the disclosure can be provided as a method, device, or computer program product. Therefore, the disclosure can take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware aspects. Moreover, the disclosure can take the form of a computer program product implemented on one or more computer usable non-transitory storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer usable program code.

[0114] The disclosure is described with reference to flowcharts and / or block diagrams of methods, devices (systems) and computer program products according to embodiments of the disclosure. It should be understood that each flow and / or block in the flowcharts and / or block diagrams and the combination of flows and / or blocks in the flowcharts and / or block diagrams can be implemented by computer program instructions. These computer program instructions can be provided to a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing apparatus to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing apparatus produce a device that implements the functions specified in the flow Figure 1 The device that implements the functions specified in one or more flows and / or blocks. Figure 1 The device that implements the functions specified in one or more flows and / or blocks.

[0115] These computer program instructions can also be stored in a computer readable memory that can guide the computer or other programmable data processing apparatus to work in a specific way, so that the instructions stored in the computer readable memory produce a product including instruction devices, which implement the functions specified in the flow Figure 1 The device that implements the functions specified in one or more flows and / or blocks. Figure 1 The device that implements the functions specified in one or more flows and / or blocks.

[0116] These computer program instructions can also be loaded into a computer or other programmable data processing devices, so that a series of operational steps are performed on the computer or other programmable devices to generate computer-implemented processes, so that the instructions executed on the computer or other programmable devices provide a process for implementing the functions specified in the flowchart Figure 1 one flow or multiple flows and / or blocks Figure 1 one block or multiple blocks.

[0117] So far, the present disclosure has been described in detail. In order to avoid obscuring the concept of the present disclosure, some details known in the art are not described. Those skilled in the art can fully understand how to implement the technical solutions disclosed herein according to the above description.

[0118] Although some specific embodiments of the present disclosure have been described in detail through examples, those skilled in the art should understand that the above examples are only for illustration, not for limiting the scope of the present disclosure. Those skilled in the art should understand that the above embodiments can be modified without departing from the scope and spirit of the present disclosure. The scope of the present disclosure is defined by the appended claims.

Claims

1. A photovoltaic grid-connected control device, comprising: The controller, and the voltage converter, inverter and low-pass filter cascaded in sequence. The input terminal of the voltage converter is configured to connect to a photovoltaic device; The output of the low-pass filter is configured to be connected to the power grid, wherein the filter capacitor of the low-pass filter is configured to be connected in parallel with a non-critical load. as well as The controller is configured to operate based on the grid-connected active power reference value P. g_ref The first voltage signal v at the output terminal of the low-pass filter g and the first current signal i g The second voltage signal V on the DC bus side of the inverter bus and voltage reference value V bus_ref and the inductor value L in the low-pass filter. t The voltage components in the αβ coordinate system are obtained, based on the first voltage signal v g and feedforward function G ff(s) The grid voltage feedforward component v is obtained. f Based on the voltage components in the αβ coordinate system and the grid voltage feedforward component v f The inverter's switching drive signal is controlled to adjust the power of the non-critical load, so that the grid-connected active power output by the low-pass filter tracks the grid-connected active power reference value P. g_ref .

2. The photovoltaic grid-connected control device according to claim 1, wherein, The controller is configured to: According to the first voltage signal v g and the first current signal i g The first current component I in the dq coordinate system is obtained. d Second current component I q ; According to the second voltage signal V bus The voltage reference value V bus_ref and the grid-connected active power reference value P g_ref The first reference voltage value V in the dq coordinate system is obtained. d_ref Second reference voltage value V q_ref ; According to the first current component I d The second current component I q The first reference voltage value V d_ref and the second reference voltage value V q_ref and the inductor value L in the low-pass filter t The first voltage component V in the dq coordinate system is obtained. d Second voltage component V q ;as well as According to the first voltage component V d and the second voltage component V q The α voltage component v in the αβ coordinate system is obtained. α and β voltage component v β .

3. The photovoltaic grid-connected control device according to claim 2, wherein, The controller is configured to: The first voltage signal v g The input is fed into the phase-locked loop to obtain the grid-connected voltage amplitude V. g Phase θ and fundamental frequency ω; Based on the β voltage component v β The first voltage signal v g The β current component i in the αβ coordinate system is obtained. g_β ; as well as According to the first current signal i g The phase θ and the β current component i g_β The first current component I in the dq coordinate system is obtained. d and the second current component I q .

4. The photovoltaic grid-connected control device according to claim 2, wherein, The controller is configured to: The first voltage signal v g The input is fed into the phase-locked loop to obtain the grid-connected voltage amplitude V. g Phase θ and fundamental frequency ω; as well as According to the first current signal i g And the phase θ, to obtain the first current component I in the dq coordinate system. d and the second current component I q .

5. The photovoltaic grid-connected control device according to claim 2, wherein, The controller is configured to: The voltage reference value V bus_ref With the second voltage signal V bus The difference is used for proportional-integral PI control, and after passing through a limiter and a hold circuit, the second reference current I in the dq coordinate system is obtained. q_ref ; The second reference current I q_ref With the second current component I q The difference is used for PI control, and after limiting, the second reference voltage value V is obtained. q_ref ; The grid-connected active power reference value P g_ref Divide by grid voltage amplitude V g After passing through a limiter and a holding circuit, the first reference current I in the dq coordinate system is obtained. d_ref ; as well as The first reference current I d_ref With the first current component I d The difference is used for PI control, and after limiting, the first reference voltage value V is obtained. d_ref .

6. The photovoltaic grid-connected control device according to claim 2, wherein, The controller is configured to: According to the first current component I d and the inductor value L in the low-pass filter t The first voltage value V corresponding to the inductor in the dq coordinate system is obtained. dt ; The second reference voltage value V q_ref With the first voltage value V dt Perform the difference operation to obtain the second voltage component V. q ; According to the second current component I q and the inductor value L in the low-pass filter t The second voltage value V corresponding to the inductor in the dq coordinate system is obtained. qt ;as well as The first reference voltage value V d_ref With the second voltage value V qt The first voltage component V is obtained by performing an addition operation. d .

7. The photovoltaic grid-connected control device according to any one of claims 1 to 6, wherein, The low-pass filter is an LCL type low-pass filter, the inverter is a single-phase inverter or a three-phase inverter, or the voltage converter is a Boost converter.

8. A photovoltaic grid-connected control system, comprising: The photovoltaic grid-connected control device according to any one of claims 1 to 7; as well as Photovoltaic equipment.

9. A control method for a photovoltaic grid-connected control device as described in claim 1, comprising: Obtain the first voltage signal v at the output of the low-pass filter. g and the first current signal i g And the second voltage signal V on the DC bus side of the inverter. bus ; According to the grid-connected active power reference value P g_ref The first voltage signal v g First current signal i g Second voltage signal V bus and voltage reference value V bus_ref and the inductor value L in the low-pass filter. t The voltage components in the αβ coordinate system are obtained, based on the first voltage signal v g and feedforward function G ff(s) The grid voltage feedforward component v is obtained. f Based on the voltage components in the αβ coordinate system and the grid voltage feedforward component v f Generate the switching drive signal for the inverter; as well as A switching drive signal is sent to the inverter to regulate the power of non-critical loads, so that the grid-connected active power output of the low-pass filter tracks the grid-connected active power reference value P. g_ref .

10. The control method according to claim 9, wherein, The voltage components in the αβ coordinate system are obtained as follows: According to the first voltage signal v g and the first current signal i g The first current component I in the dq coordinate system is obtained. d Second current component I q ; According to the second voltage signal V bus The voltage reference value V bus_ref and the grid-connected active power reference value P g_ref The first reference voltage value V in the dq coordinate system is obtained. d_ref Second reference voltage value V q_ref ; According to the first current component I d The second current component I q The first reference voltage value V d_ref and the second reference voltage value V q_ref and the inductor value L in the low-pass filter t The first voltage component V in the dq coordinate system is obtained. d Second voltage component V q ;as well as According to the first voltage component V d and the second voltage component V q The α voltage component v in the αβ coordinate system is obtained. α and β voltage component v β .

11. The control method according to claim 10, wherein, The first current component I in the dq coordinate system is obtained. d Second current component I q include: The first voltage signal v g The input is fed into the phase-locked loop to obtain the grid-connected voltage amplitude V. g Phase θ and fundamental frequency ω; Based on the β voltage component v β The first voltage signal v g The β current component i in the αβ coordinate system is obtained. g_β ;as well as According to the first current signal i g The phase θ and the β current component i g_β The first current component I in the dq coordinate system is obtained. d and the second current component I q .

12. The control method according to claim 10, wherein, The first current component I in the dq coordinate system is obtained. d Second current component I q include: The first voltage signal v g The input is fed into the phase-locked loop to obtain the grid-connected voltage amplitude V. g Phase θ and fundamental frequency ω; and According to the first current signal i g The phase θ is used to obtain the first current component I in the dq coordinate system. d and the second current component I q .

13. The control method according to claim 10, wherein, The first reference voltage value V in the dq coordinate system is obtained. d_ref Second reference voltage value V q_ref include: The voltage reference value V bus_ref With the second voltage signal V bus The difference is used for proportional-integral PI control, and after passing through a limiter and a hold circuit, the second reference current I in the dq coordinate system is obtained. q_ref ; The second reference current I q_ref With the second current component I q The difference is used for PI control, and after limiting, the second reference voltage value V is obtained. q_ref ; The grid-connected active power reference value P g_ref Divide by grid voltage amplitude V g After passing through a limiter and a holding circuit, the first reference current I in the dq coordinate system is obtained. d_ref ;as well as The first reference current I d_ref With the first current component I d The difference is used for PI control, and after limiting, the first reference voltage value V is obtained. d_ref .

14. The control method according to claim 10, wherein, The first voltage component V in the dq coordinate system is obtained. d Second voltage component V q include: According to the first current component I d and the inductor value L in the low-pass filter t The first voltage value V corresponding to the inductor in the dq coordinate system is obtained. dt ; The second reference voltage value V q_ref With the first voltage value V dt Perform the difference operation to obtain the second voltage component V. q ; According to the second current component I q and the inductor value L in the low-pass filter t The second voltage value V corresponding to the inductor in the dq coordinate system is obtained. qt ;as well as The first reference voltage value V d_ref With the second voltage value V qt The first voltage component V is obtained by performing an addition operation. d .

15. A controller, comprising: Memory; as well as A processor coupled to the memory, the processor being configured to execute the control method as described in any one of claims 9 to 14 based on instructions stored in the memory.

16. A non-transitory computer-readable storage medium having stored thereon computer program instructions that, when executed by a processor, implement the control method as described in any one of claims 9 to 14.

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