Inverter control method and device, controller and photovoltaic energy storage system

Abstract

The invention discloses a control method and a control device of an inverter, a controller and a photovoltaic energy storage system, the inverter is connected with a load through a filter and is used for converting direct current into alternating current, and the alternating current is filtered by the filter and then is supplied to the load, and the control method of the inverter comprises the following steps: obtaining the filtering current of the filter; determining an active damping coefficient based on the filtering current; and controlling the inverter based on the active damping coefficient and the filtering current. Therefore, according to the method, the active damping coefficient is determined in real time according to the filtering current, so that dynamic adjustment of the active damping coefficient is realized based on the filtering current, the voltage waveform determined based on the active damping coefficient and the filtering current is closer to sine waves, corresponding voltage harmonic components are fewer, voltage harmonics are better, and the reliability of the active damping coefficient is improved. And the control effect on the inverter is further improved.

Description

Technical Field

[0001] The present invention relates to the technical field of photovoltaic energy storage systems, and in particular to a control method and control device of an inverter, a controller and a photovoltaic energy storage system. Background Art

[0002] In the system control of low-power photovoltaic energy storage inverters connected to the load using LC filters, resonance is prone to occur, which in turn causes the system to become unstable due to resonance. To solve the resonance problem, two technical solutions, passive damping and active damping, are generally used. Among them, the active damping technical solution has the advantages of simple implementation, flexible control, and strong robustness, and is widely used.

[0003] In the related art, when the active damping technical solution is adopted, a fixed active damping coefficient is preset to achieve stable control of the system. However, when the inverter is connected to a small load, the preset active damping coefficient can meet the stability requirements of the system, but it will cause the voltage waveform output by the controller to be distorted. Summary of the invention

[0004] The present invention aims to solve one of the technical problems in the related art to at least a certain extent. To this end, the first object of the present invention is to propose a control method for an inverter, which determines the active damping coefficient in real time according to the filter current, so as to dynamically adjust the active damping coefficient based on the filter current, so that the voltage waveform determined based on the active damping coefficient and the filter current is closer to a sine wave, and the corresponding voltage harmonic components are less, so that the voltage harmonics are better, and the control effect of the inverter is further improved.

[0005] A second objective of the present invention is to provide a control device for an inverter.

[0006] The third object of the present invention is to provide a controller.

[0007] The fourth objective of the present invention is to provide a photovoltaic energy storage system.

[0008] A fifth objective of the present invention is to provide a photovoltaic energy storage system.

[0009] To achieve the above-mentioned purpose, an embodiment of the first aspect of the present invention proposes a control method for an inverter, wherein the inverter is connected to a load through a filter, and is used to convert direct current into alternating current, and supply power to the load after filtering through the filter. The control method of the inverter includes: obtaining a filter current of the filter; determining an active damping coefficient based on the filter current; and controlling the inverter based on the active damping coefficient and the filter current.

[0010] The inverter according to the embodiment of the present invention is connected to the load through a filter, and is used to convert direct current into alternating current, and supply power to the load after filtering through the filter. The control method of the inverter first obtains the filter current of the filter, and determines the active damping coefficient based on the filter current, and controls the inverter based on the active damping coefficient and the filter current. Therefore, the method determines the active damping coefficient in real time according to the filter current, so as to realize dynamic adjustment of the active damping coefficient based on the filter current, so that the voltage waveform determined based on the active damping coefficient and the filter current is closer to a sine wave, and the corresponding voltage harmonic components are less, so that the voltage harmonics are better, and the control effect of the inverter is further improved.

[0011] In addition, the control method of the inverter according to the above embodiment of the present invention may also have the following additional technical features:

[0012] According to one embodiment of the present invention, determining an active damping coefficient based on a filter current includes: processing the filter current to obtain a reference value for characterizing the fluctuation amplitude of the filter current; determining a reference interval in which the reference value is located, wherein different reference intervals correspond to different active damping coefficients; and determining the active damping coefficient based on the reference interval and the reference value.

[0013] According to one embodiment of the present invention, an active damping coefficient is determined based on a reference interval and a reference value, including: when the reference interval is a first interval, determining the active damping coefficient as a first preset coefficient; when the reference interval is a second interval, determining the active damping coefficient based on the reference value and a preset mapping relationship, wherein the active damping coefficient is negatively correlated with the reference value; when the reference interval is a third interval, determining the active damping coefficient as a second preset coefficient, wherein the second preset coefficient is less than the first preset coefficient, and the reference value corresponding to the third interval is greater than the reference value corresponding to the second interval is greater than the reference value corresponding to the first interval.

[0014] According to an embodiment of the present invention, the reference value includes one of an effective value, a peak value, a per-unit value of the effective value, and a per-unit value of the peak value of the filter current.

[0015] According to one embodiment of the present invention, an inverter is controlled based on an active damping coefficient and a filter current, including: obtaining the product of the active damping coefficient and the filter current to obtain an active damping voltage drop; adjusting an initial control voltage of the inverter based on the active damping voltage drop to obtain a target control voltage; and controlling the inverter based on the target control voltage.

[0016] According to an embodiment of the present invention, the initial control voltage of the inverter is adjusted based on the active damping voltage drop to obtain the target control voltage, including: obtaining the difference between the initial control voltage and the active damping voltage drop to obtain the target control voltage.

[0017] According to an embodiment of the present invention, the initial control voltage is obtained by: obtaining a voltage difference between a target output voltage and an actual output voltage of the inverter; and inputting the voltage difference into a voltage controller to obtain the initial control voltage.

[0018] According to one embodiment of the present invention, the voltage controller includes one of a repetitive controller, a proportional resonant controller and a quasi-proportional resonant controller.

[0019] According to an embodiment of the present invention, the filter includes an inductor and a capacitor, and the filter current is an inductor current or a capacitor current.

[0020] To achieve the above-mentioned purpose, the second aspect of the embodiment of the present invention proposes a control device for an inverter, wherein the inverter is connected to a load through a filter, and is used to convert direct current into alternating current, and supply power to the load after filtering through the filter. The control device for the inverter includes: an acquisition module, used to obtain a filter current of the filter; a determination module, used to determine an active damping coefficient based on the filter current; and a control module, used to control the inverter based on the active damping coefficient and the filter current.

[0021] According to the control device of the inverter of the embodiment of the present invention, the inverter is connected to the load through the filter, and is used to convert direct current into alternating current, and supply power to the load after filtering through the filter. The control device of the inverter obtains the filter current of the filter through the acquisition module, determines the active damping coefficient based on the filter current through the determination module, and the control module controls the inverter based on the active damping coefficient and the filter current. Therefore, the device determines the active damping coefficient in real time according to the filter current, so as to realize the dynamic adjustment of the active damping coefficient based on the filter current, so that the voltage waveform of the control voltage determined based on the active damping coefficient and the filter current is closer to the sine wave, and the corresponding voltage harmonic components are less, so that the voltage harmonics are better, so as to ensure the control effect of the inverter.

[0022] To achieve the above objectives, a third aspect of the present invention proposes a controller, including: a memory, a processor, and a program stored in the memory and executable on the processor. When the processor executes the program, the above inverter control method is implemented.

[0023] According to the controller of the embodiment of the present invention, when the processor executes the program, the control method of the inverter mentioned above is implemented. Based on the control method of the inverter mentioned above, the active damping coefficient is determined in real time according to the filter current, so as to realize dynamic adjustment of the active damping coefficient based on the filter current, so that the voltage waveform of the control voltage determined based on the active damping coefficient and the filter current is closer to the sine wave, and the corresponding voltage harmonic components are less, so that the voltage harmonics are better, thereby ensuring the control effect of the inverter.

[0024] To achieve the above-mentioned purpose, a fourth aspect of the present invention provides a photovoltaic energy storage system, including the above-mentioned inverter control device, or the above-mentioned controller.

[0025] According to the photovoltaic energy storage system of the embodiment of the present invention, based on the control device of the above-mentioned inverter or the above-mentioned controller, the voltage waveform of the control voltage determined based on the active damping coefficient and the filter current can be made closer to a sine wave, and the corresponding voltage harmonic components are less, so that the voltage harmonics are better, so as to ensure the control effect of the inverter.

[0026] To achieve the above-mentioned purpose, the fifth embodiment of the present invention proposes a photovoltaic energy storage system, including: a photovoltaic module; an inverter and a filter, the DC side of the inverter is connected to the photovoltaic module, and the AC side of the inverter is connected to the power grid and the load through the filter, which is used to convert the DC power of the photovoltaic module into AC power, and after filtering through the filter, feed it to the power grid and / or power the load; a controller, the controller is respectively connected to the inverter and the filter, and is used to obtain the filter current of the filter when the inverter is off-grid, and determine the active damping coefficient based on the filter current, and control the inverter based on the active damping coefficient and the filter current.

[0027] According to the photovoltaic energy storage system of the embodiment of the present invention, the DC side of the inverter is connected to the photovoltaic module, and the AC side of the inverter is connected to the power grid and the load through the filter, which is used to convert the DC power of the photovoltaic module into AC power, and after filtering through the filter, feed it to the power grid and / or supply power to the load. The controller is connected to the inverter and the filter respectively. The controller is used to obtain the filter current of the filter when the inverter is off-grid, and determine the active damping coefficient based on the filter current, and control the inverter based on the active damping coefficient and the filter current. Therefore, the system determines the active damping coefficient in real time according to the filter current, so as to realize dynamic adjustment of the active damping coefficient based on the filter current, so that the voltage waveform of the control voltage determined based on the active damping coefficient and the filter current is closer to the sine wave, and the corresponding voltage harmonic components are less, so that the voltage harmonics are better, and further ensure that the voltage harmonics of the photovoltaic energy storage system are better.

[0028] Additional aspects and advantages of the present invention will be given in part in the following description and in part will be obvious from the following description, or will be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 is a flow chart of a control method of an inverter according to an embodiment of the present invention;

[0030] Figure 2 is a system block diagram of an inverter according to an embodiment of the present invention;

[0031] Figure 3is a control block diagram of an inverter according to an embodiment of the present invention;

[0032] Figure 4 Schematic diagram of the relationship between the active damping coefficient and the per-unit value of the effective value of the inductor current according to an embodiment of the present invention;

[0033] Figure 5 is a flow chart of a method for controlling an inverter according to a specific embodiment of the present invention;

[0034] Figure 6 is a waveform diagram of an initial control voltage when the active damping coefficient is 0 ohm according to a specific embodiment of the present invention;

[0035] Figure 7 is a waveform diagram of an initial control voltage when the active damping coefficient is 10 ohm according to a specific embodiment of the present invention;

[0036] Figure 8 is a waveform diagram of an initial control voltage based on a case where an active damping coefficient is dynamically adjusted according to a specific embodiment of the present invention;

[0037] Fig. 9 is a block diagram of a control device for an inverter according to an embodiment of the present invention;

[0038] Fig.10 is a block diagram of a controller according to an embodiment of the present invention;

[0039] Fig.11 A schematic diagram of a photovoltaic energy storage system according to an embodiment of the present invention Figure 1 ;

[0040] Fig.12 A schematic diagram of a photovoltaic energy storage system according to an embodiment of the present invention Figure 2 ;

[0041] Fig.13 FIG. 4 is a block diagram of a photovoltaic energy storage system according to an embodiment of the present invention. DETAILED DESCRIPTION

[0042] Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present invention, and should not be construed as limiting the present invention.

[0043] The following describes the inverter control method and control device, controller and photovoltaic energy storage system proposed in the embodiments of the present invention with reference to the accompanying drawings.

[0044] Figure 14 is a flow chart of a method for controlling an inverter according to an embodiment of the present invention.

[0045] like Figure 2 As shown, according to one embodiment of the present invention, the inverter 2 is connected to the load 5 via the filter 3 , and is used to convert direct current into alternating current, and supply power to the load 5 after filtering by the filter 3 .

[0046] Specifically, the DC side of the inverter 2 is connected to the DC source Udc, which can be a storage battery, a photovoltaic module, a rectifier circuit, etc. The DC source Udc is used to provide DC power to the inverter 2, and there is no specific limitation here. The AC side of the inverter 2 is connected to the load 5 through the filter 3, and the inverter 2 provides the converted AC power to the load 5 after filtering it through the filter 3. Among them, the filter 3 can adopt an LC filter, an LCC filter, etc., which can be selected according to actual conditions.

[0047] Figure 2 The inverter 2 in the embodiment uses a three-phase inverter circuit composed of six IGBTs (Insulate-Gate Bipolar Transistors) to output three-phase AC power through three ports. The three-phase AC power is represented by phase A, phase B and phase C respectively, and the filter 3 is provided with corresponding filter circuits corresponding to the three-phase AC power. For example, the inductor L1 and the capacitor C1 constitute the filter circuit corresponding to A, the inductor L2 and the capacitor C2 constitute the filter circuit corresponding to B, and the inductor L3 and the capacitor C3 constitute the filter circuit corresponding to C.

[0048] During the control process, the controller 4 determines the initial control voltage Uout based on the active damping coefficient, and outputs corresponding six-way PWM (Pulse Width Modulation) signals according to the initial control voltage Uout to control the on and off of the IGBT in the inverter 2 so that the inverter 2 converts direct current into corresponding alternating current.

[0049] In the related art, Figure 2 In the case of the system block diagram shown, a moderate active damping coefficient will be pre-set to achieve stable control of the system. When the load 5 in the system is a large load, the working current of the controller 5 is small. At this time, the default active damping coefficient of the system, that is, the preset active damping coefficient, can meet the stability requirements of the system and prevent the voltage waveform output by the controller 4 from being distorted; however, when the load 5 is a small load, the working current of the load 5 is large. At this time, the default active damping coefficient of the system meets the stability requirements of the system, but the output voltage waveform will be distorted, such as the shape of a steamed bun wave.

[0050] In order to solve the above technical problems, the present application proposes a control method for an inverter. Figure 1 The technical solution of this application is described in detail.

[0051] like Figure 1 As shown, the control method of the inverter according to the embodiment of the present invention may include:

[0052] S1, obtains the filter current of the filter;

[0053] S2, determining the active damping coefficient R based on the filter current;

[0054] S3, controlling the inverter based on the active damping coefficient R and the filter current.

[0055] Specifically, the filter current is the current flowing through the filter, which can be obtained through a current sensor or a current sampling circuit according to actual conditions. Figure 2 Taking the LC filter shown as an example, the filter current can be the inductor current IL flowing through the inductor L, or the Ic flowing through the capacitor C, and the specific selection can be made according to actual conditions.

[0056] The corresponding active damping coefficient R is determined based on the obtained filter current. For example, the active damping coefficient R can be calculated based on the filter current based on a preset calculation formula, wherein the preset calculation formula is used to characterize the relationship between the filter current and the active damping coefficient R; the active damping coefficient R can also be determined by looking up a table based on a preset filter current-active damping coefficient R relationship table. It can be understood that the preset mapping relationship determined based on different types of filter currents is also different. For example, when the filter current is the inductor current IL, the active damping coefficient R can be determined based on the first preset mapping relationship; when the filter current is the capacitor current Ic, the active damping coefficient R can be determined based on the second preset mapping relationship. The first preset mapping relationship and the second preset mapping relationship can be determined based on experiments, and can be specifically a corresponding relationship formula, a relationship table, etc.

[0057] After determining the corresponding active damping coefficient R, the controller determines a voltage signal according to the active damping coefficient R and the filter current, and determines a PWM signal with the voltage signal to control the inverter.

[0058] This embodiment dynamically adjusts the active damping coefficient R based on the filter current, thereby reducing the distortion of the voltage waveform output by the controller and achieving a better voltage waveform.

[0059] According to an embodiment of the present invention, the filter includes an inductor and a capacitor, and the filter current is the inductor current IL or the capacitor current Ic.

[0060] Specifically, the filter may be an LC filter, an LCC filter, an LCL filter, etc., and obtaining the filter current of the filter may be obtaining the inductor current IL, or obtaining the capacitor current Ic. The specific selection and circuit arrangement may be based on actual conditions.

[0061] This embodiment filters the AC power through a filter composed of inductors and capacitors, outputs it to the load, and dynamically adjusts the active damping coefficient R based on the filtered current. While ensuring the stable operation of the filter and preventing resonance problems, the distortion of the voltage waveform output by the controller is reduced, thereby achieving a better voltage waveform.

[0062] The control method of the inverter of the present application is described in detail below by taking the filter current as the inductor current IL as an example.

[0063] According to one embodiment of the present invention, determining an active damping coefficient based on a filter current includes: processing the filter current to obtain a reference value for characterizing the fluctuation amplitude of the filter current; determining a reference interval in which the reference value is located, wherein different reference intervals correspond to different active damping coefficients; and determining the active damping coefficient based on the reference interval and the reference value.

[0064] According to an embodiment of the present invention, the reference value includes one of an effective value, a peak value, a per-unit value of the effective value, and a per-unit value of the peak value of the filter current.

[0065] Specifically, when the filter current is the inductor current IL, the reference value is used to characterize the fluctuation amplitude of the filter current. For example, the reference value can be the effective value, peak value, per unit value of the effective value, and per unit value of the peak value of the inductor current IL. Among them, the per unit value of the effective value of the inductor current IL is the inductor current I L The ratio of the effective value of the inductor current to the rated current. The per-unit value of the peak value of the inductor current IL is the inductor current I L The ratio of the peak current to the rated current.

[0066] Taking the reference value as the per-unit value Pu of the effective value of the filter current IL as an example, the per-unit value Pu of the effective value of the filter current is calculated by processing the inductor current IL obtained by real-time sampling. Determine the reference interval in which the per-unit value Pu of the effective value of the filter current is located, and obtain the active damping coefficient R based on the reference interval and the per-unit value Pu of the effective value of the filter current. Further, in different reference intervals, the preset relationship between the active damping coefficient R and the per-unit value Pu of the effective value of the filter current is different. Therefore, based on the reference interval in which the per-unit value Pu of the effective value of the filter current is located, the corresponding preset relationship is called, so as to determine the active damping coefficient R according to the preset relationship corresponding to the reference interval and the per-unit value Pu of the effective value of the current filter current, wherein the preset relationship can be embodied in the form of a calculation formula or in the form of a table, which is not limited here.

[0067] It should be noted that the reference interval is divided into intervals based on the type of reference value, and the corresponding preset relationship is set. The corresponding preset relationship is called according to different reference values ​​to determine the corresponding active damping coefficient R.

[0068] According to one embodiment of the present invention, an active damping coefficient is determined based on a reference interval and a reference value, including: when the reference interval is a first interval, determining the active damping coefficient as a first preset coefficient; when the reference interval is a second interval, determining the active damping coefficient based on the reference value and a preset mapping relationship, wherein the active damping coefficient is negatively correlated with the reference value; when the reference interval is a third interval, determining the active damping coefficient as a second preset coefficient, wherein the second preset coefficient is less than the first preset coefficient, and the reference value corresponding to the third interval is greater than the reference value corresponding to the second interval is greater than the reference value corresponding to the first interval.

[0069] Specifically, Figure 3 For example, the first interval is: the per-unit value Pu of the effective value of the filter current is less than 20%; the second interval is: 20%≤the per-unit value Pu of the effective value of the filter current is less than 80%; the third interval is: the per-unit value Pu of the effective value of the filter current is greater than or equal to 80%.

[0070] When the per-unit value Pu of the effective value of the filter current is in the first interval, the active damping coefficient is R1, that is, the first preset coefficient; when the per-unit value Pu of the effective value of the filter current is in the second interval, the active damping coefficient is calculated based on the per-unit value Pu of the effective value of the filter current and the preset mapping relationship; when the per-unit value Pu of the effective value of the filter current is in the third interval, the active damping coefficient is R2, that is, the second preset coefficient.

[0071] That is to say, in the case where the reference value is too large or too small, i.e., the reference values in the first interval and the third interval, a fixed active damping coefficient R is adopted. For the reference values in the middle, i.e., the reference values in the second interval, the active damping coefficient R is determined based on real-time calculation.

[0072] Combined with Figure 4 As shown, according to an embodiment of the present invention, the inverter is controlled based on the active damping coefficient R and the filtered current, including: obtaining the product of the active damping coefficient R and the filtered current to obtain the active damping voltage drop Ur; adjusting the initial control voltage U0 of the inverter based on the active damping voltage drop Ur to obtain the target control voltage Uout; and controlling the inverter based on the target control voltage Uout.

[0073] Specifically, continuing to take the filtered current as the inductor current IL as an example, the product of the active damping coefficient R and the filtered current IL is calculated to obtain the active damping voltage drop Ur. The initial voltage U0 is adjusted according to the active damping voltage drop Ur. For example, the corresponding adjustment coefficient is determined according to the active damping voltage drop Ur, and the product of the adjustment coefficient and the initial voltage U0 is used as the target control voltage Uout. Finally, the PWM waveform is determined according to the target control voltage Uout to control the inverter.

[0074] According to an embodiment of the present invention, adjusting the initial control voltage U0 of the inverter based on the active damping voltage drop Ur to obtain the target control voltage Uout includes: obtaining the difference between the initial control voltage U0 and the active damping voltage drop Ur to obtain the target control voltage Uout. That is to say, the target control voltage Uout is calculated by subtracting the active damping voltage drop Ur from the initial control voltage U0.

[0075] According to an embodiment of the present invention, the initial control voltage U0 is obtained in the following manner: obtaining the voltage difference Uerr between the target output voltage Ucmd and the actual output voltage Ucap of the inverter; and inputting the voltage difference Uerr into a voltage controller to obtain the initial control voltage U0.

[0076] Specifically, the target output voltage Ucmd is a given voltage, and the actual output voltage Ucap can be obtained by sampling the actual output voltage of the inverter based on a sampling unit. The voltage difference Uerr is calculated by subtracting the actual output voltage Ucap from the target output voltage Ucmd, and the voltage difference Uerr is input into the voltage controller to calculate the initial control voltage U0.

[0077] It should be noted that the voltage controller can adopt a repetitive controller, a proportional-resonant controller, a quasi-proportional-resonant controller, etc., which is not limited herein.

[0078] As a specific embodiment of the present application, the first preset interval is [0, 20%), the second preset interval is [20%, 80%), and the third interval is [80%, 100%). The control method of the inverter in the embodiment of the present invention is as follows: Figure 5 As shown, the following steps may be included:

[0079] S101, obtaining the inductor current IL of the inverter.

[0080] S102, processing the inductor current IL to obtain a per-unit value Pu of its effective value.

[0081] S103, determine if the per-unit value Pu is less than 20%. If so, execute step S104; if not, execute step S105.

[0082] S104, determining that the active damping coefficient R is a first preset coefficient R1. Execute step S108.

[0083] S105, judging whether the per-unit value Pu is less than 80%. If so, executing step S106; if not, executing step S107.

[0084] S106, determining the active damping coefficient R based on the per-unit value Pu and the preset mapping relationship. Execute step S108.

[0085] S107, determining the active damping coefficient R to be a second preset coefficient R2.

[0086] S108, calculating the active damping pressure drop Ur=R*IL.

[0087] S109, calculating the target control voltage Uout=U0-Ur.

[0088] S110, controlling the inverter based on the target control voltage Uout.

[0089] Combination Figure 4 As shown, in the process of controlling the inverter, the target output voltage Ucmd minus the actual output voltage Ucap is calculated to obtain the voltage difference Uerr, and the voltage difference Uerr is input into the voltage controller to calculate the initial control voltage U0. Thus, the target control voltage Uout is calculated based on the calculated initial control voltage U0 minus the active damping voltage drop Ur, and the inverter is controlled by the target control voltage Uout.

[0090] Furthermore, the simulation output results based on different active damping coefficients R are as follows: Figure 6-8 shown.

[0091] Specifically, when the active damping coefficient R = 0 Ohm, the voltage waveform output by the controller, i.e., the target control voltage Uout, is as follows: Figure 6As shown in the figure, the controller's output voltage will resonate. At rated power, if the active damping coefficient R = 10Ohm is used, the controller output voltage waveform is as follows: Figure 7 As shown in FIG. 1 , although the voltage waveform output by the controller is very stable and has no resonance, the output voltage waveform of the controller will be distorted at the peak, that is, the peak clipping phenomenon will occur, causing the waveform to be deformed. Based on the control method of the present application, when the active damping coefficient is dynamically adjusted by filtering current, the voltage waveform output by the controller is as follows: Figure 8 As shown, based on Figure 8 It can be seen that the voltage waveform is stable, the peak distortion of the waveform is reduced, and the THD (Total Harmonic Distortion) is significantly reduced.

[0092] In summary, the inverter according to the embodiment of the present invention is connected to the load through a filter, which is used to convert direct current into alternating current, and supply power to the load after filtering through the filter. The control method of the inverter first obtains the filter current of the filter, and determines the active damping coefficient based on the filter current, and controls the inverter based on the active damping coefficient and the filter current. Therefore, the method determines the active damping coefficient in real time according to the filter current, so as to realize dynamic adjustment of the active damping coefficient based on the filter current, so that the voltage waveform of the control voltage determined based on the active damping coefficient and the filter current is closer to a sine wave, and the corresponding voltage harmonic components are less, so that the voltage harmonics are better, so as to ensure the control effect of the inverter.

[0093] Corresponding to the above embodiment, the present invention further proposes a control device for an inverter.

[0094] According to an embodiment of the present invention, the inverter is connected to the load via a filter, and is used to convert direct current into alternating current, and then supplies power to the load after filtering by the filter.

[0095] Specifically, refer to Figure 2 As shown, the DC side of the inverter 2 is connected to the DC source Udc, which can be a storage battery, a photovoltaic module, a rectifier circuit, etc. The DC source Udc is used to provide DC power to the inverter 2, and there is no specific limitation here. The AC side of the inverter 2 is connected to the load 5 through the filter 3, and the inverter 2 provides the converted AC power to the load 5 after filtering it through the filter 3. Among them, the filter 3 can be an LC filter, an LCC filter, etc., which can be selected according to actual conditions.

[0096] During the control process, the controller 4 determines the initial control voltage Uout based on the active damping coefficient, and outputs corresponding six-way PWM (Pulse Width Modulation) signals according to the initial control voltage Uout to control the on and off of the IGBT in the inverter 2 so that the inverter 2 converts direct current into corresponding alternating current.

[0097] like Fig. 9 As shown, the control device of the inverter according to the embodiment of the present invention may include: an acquisition module 10 , a determination module 20 and a control module 30 .

[0098] The acquisition module 10 is used to acquire the filter current of the filter. The determination module 20 is used to determine the active damping coefficient based on the filter current. The control module 30 is used to control the inverter based on the active damping coefficient and the filter current.

[0099] According to one embodiment of the present invention, the determination module 20 determines the active damping coefficient based on the filter current, and is specifically used to: process the filter current to obtain a reference value for characterizing the fluctuation amplitude of the filter current; determine a reference interval in which the reference value is located, wherein different reference intervals correspond to different active damping coefficients; and determine the active damping coefficient based on the reference interval and the reference value.

[0100] According to one embodiment of the present invention, the determination module 20 determines the active damping coefficient based on the reference interval and the reference value, and is specifically used to: when the reference interval is the first interval, determine the active damping coefficient as the first preset coefficient; when the reference interval is the second interval, determine the active damping coefficient based on the reference value and the preset mapping relationship, wherein the active damping coefficient is negatively correlated with the reference value; when the reference interval is the third interval, determine the active damping coefficient as the second preset coefficient, wherein the second preset coefficient is less than the first preset coefficient, and the reference value corresponding to the third interval is greater than the reference value corresponding to the second interval is greater than the reference value corresponding to the first interval.

[0101] According to an embodiment of the present invention, the reference value includes one of an effective value, a peak value, a per-unit value of the effective value, and a per-unit value of the peak value of the filter current.

[0102] According to one embodiment of the present invention, the control module 30 controls the inverter based on the active damping coefficient and the filter current, and is specifically used to: obtain the product of the active damping coefficient and the filter current to obtain the active damping voltage drop; adjust the initial control voltage of the inverter based on the active damping voltage drop to obtain the target control voltage; and control the inverter based on the target control voltage.

[0103] According to one embodiment of the present invention, the control module 30 adjusts the initial control voltage of the inverter based on the active damping voltage drop to obtain a target control voltage, and is specifically used to: obtain the difference between the initial control voltage and the active damping voltage drop to obtain the target control voltage.

[0104] According to an embodiment of the present invention, the control module 30 is further used to: obtain a voltage difference between a target output voltage and an actual output voltage of the inverter; and input the voltage difference into a voltage controller to obtain an initial control voltage.

[0105] According to one embodiment of the present invention, the voltage controller includes one of a repetitive controller, a proportional resonant controller and a quasi-proportional resonant controller.

[0106] According to an embodiment of the present invention, the filter includes an inductor and a capacitor, and the filter current is an inductor current or a capacitor current.

[0107] It should be noted that for details not disclosed in the inverter control device of the embodiment of the present invention, please refer to the details disclosed in the inverter control method of the above embodiment of the present invention, and the details will not be repeated here.

[0108] According to the control device of the inverter of the embodiment of the present invention, the inverter is connected to the load through the filter, and is used to convert direct current into alternating current, and supply power to the load after filtering through the filter. The control device of the inverter obtains the filter current of the filter through the acquisition module, determines the active damping coefficient based on the filter current through the determination module, and the control module controls the inverter based on the active damping coefficient and the filter current. Therefore, the device determines the active damping coefficient in real time according to the filter current, so as to realize the dynamic adjustment of the active damping coefficient based on the filter current, so that the voltage waveform of the control voltage determined based on the active damping coefficient and the filter current is closer to the sine wave, and the corresponding voltage harmonic components are less, so that the voltage harmonics are better, so as to ensure the control effect of the inverter.

[0109] Corresponding to the above embodiment, the present invention also proposes a controller.

[0110] like Fig.10 As shown, the controller 100 of the embodiment of the present invention includes: a memory 110, a processor 120, and a program stored in the memory 110 and executable on the processor 120. When the processor 120 executes the program, the above-mentioned inverter control method is implemented.

[0111] According to the controller of the embodiment of the present invention, when the processor executes the program, the control method of the inverter mentioned above is implemented. Based on the control method of the inverter mentioned above, the active damping coefficient is determined in real time according to the filter current, so as to realize dynamic adjustment of the active damping coefficient based on the filter current, so that the voltage waveform of the control voltage determined based on the active damping coefficient and the filter current is closer to the sine wave, and the corresponding voltage harmonic components are less, so that the voltage harmonics are better, thereby ensuring the control effect of the inverter.

[0112] Corresponding to the above embodiment, the present invention also proposes a photovoltaic energy storage system.

[0113] like Fig.11 As shown, the photovoltaic energy storage system 200 of the embodiment of the present invention includes the inverter control device 210 mentioned above, or, as Fig.12 As shown, the photovoltaic energy storage system 200 of the embodiment of the present invention includes the above-mentioned controller 100.

[0114] According to the photovoltaic energy storage system of the embodiment of the present invention, based on the control device of the above-mentioned inverter or the above-mentioned controller, the voltage waveform of the control voltage determined based on the active damping coefficient and the filter current can be made closer to a sine wave, and the corresponding voltage harmonic components are less, so that the voltage harmonics are better, so as to ensure the control effect of the inverter.

[0115] Corresponding to the above embodiment, the present invention also proposes a photovoltaic energy storage system.

[0116] like Fig.13 As shown, the photovoltaic energy storage system of the embodiment of the present invention may include: a photovoltaic component 1, an inverter 2, a filter 3 and a controller 4.

[0117] The DC side of the inverter 2 is connected to the photovoltaic module 1, and the AC side of the inverter 2 is connected to the power grid 6 and the load 5 through the filter 3. The inverter 2 is used to convert the DC power of the photovoltaic module 1 into AC power, and after filtering through the filter 3, feed it to the power grid 6 and / or supply power to the load 5. The controller 4 is connected to the inverter 2 and the filter 3 respectively. The controller 4 is used to obtain the filter current of the filter 4 when the inverter 2 is off-grid, determine the active damping coefficient based on the filter current, and control the inverter 2 based on the active damping coefficient and the filter current.

[0118] Among them, the photovoltaic energy storage system is also called the solar photovoltaic energy storage power generation system, which is a power generation system composed of photovoltaic equipment and energy storage equipment. Photovoltaic components 1, also known as solar panels, are the core part of the photovoltaic energy storage system, and their function is to convert solar energy into electrical energy. Inverter 2 is a converter that converts DC power into constant frequency and voltage or frequency and voltage regulated AC power. The power grid 6 is a whole composed of substations and transmission and distribution lines of various voltages in the power system. It includes three units: substation, transmission, and distribution. Its task is to transmit and distribute electric energy and change voltage. Load 5 is a device for converting electric energy into other forms of energy, which may include resistors, motors, etc. Among them, the AC side of inverter 2 is connected to load 5 and power grid 6 through filter 3, and inverter 2 provides the converted AC power to load 5 and power grid 6 after filtering through filter 3. Among them, filter 3 can adopt LC filter, LCC filter, etc., which can be selected according to actual conditions.

[0119] When the inverter 2 is off-grid, the filter 3 is disconnected from the grid 6, and the system connection can refer to Figure 2 As shown, the photovoltaic module 1 is Figure 2 The DC source Udc in the. For details, please refer to Figure 2 The content will not be repeated here.

[0120] According to the photovoltaic energy storage system of the embodiment of the present invention, the DC side of the inverter is connected to the photovoltaic module, and the AC side of the inverter is connected to the power grid and the load through the filter, which is used to convert the DC power of the photovoltaic module into AC power, and after filtering through the filter, feed it to the power grid and / or supply power to the load. The controller is connected to the inverter and the filter respectively. The controller is used to obtain the filter current of the filter when the inverter is off-grid, and determine the active damping coefficient based on the filter current, and control the inverter based on the active damping coefficient and the filter current. Therefore, the system determines the active damping coefficient in real time according to the filter current, so as to realize dynamic adjustment of the active damping coefficient based on the filter current, so that the voltage waveform of the control voltage determined based on the active damping coefficient and the filter current is closer to the sine wave, and the corresponding voltage harmonic components are less, so that the voltage harmonics are better, and further ensure that the voltage harmonics of the photovoltaic energy storage system are better.

[0121] It should be noted that the logic and / or steps represented in the flowchart or otherwise described herein, for example, can be considered as a sequenced list of executable instructions for implementing logical functions, and can be specifically implemented in any computer-readable medium for use by an instruction execution system, device or apparatus (such as a computer-based system, a system including a processor, or other system that can fetch instructions from an instruction execution system, device or apparatus and execute instructions), or in combination with these instruction execution systems, devices or apparatuses. For the purposes of this specification, "computer-readable medium" can be any device that can contain, store, communicate, propagate or transmit a program for use by an instruction execution system, device or apparatus, or in combination with these instruction execution systems, devices or apparatuses. More specific examples of computer-readable media (a non-exhaustive list) include the following: an electrical connection portion with one or more wirings (electronic device), a portable computer disk box (magnetic device), a random access memory (RAM), a read-only memory (ROM), an erasable and programmable read-only memory (EPROM or flash memory), an optical fiber device, and a portable compact disk read-only memory (CDROM). In addition, the computer-readable medium may even be paper or other suitable medium on which the program is printed, since the program may be obtained electronically, for example, by optically scanning the paper or other medium and then editing, interpreting or processing in other suitable ways if necessary, and then stored in a computer memory.

[0122] It should be understood that the various parts of the present invention can be implemented by hardware, software, firmware or a combination thereof. In the above-mentioned embodiments, a plurality of steps or methods can be implemented by software or firmware stored in a memory and executed by a suitable instruction execution system. For example, if implemented by hardware, as in another embodiment, it can be implemented by any one of the following technologies known in the art or their combination: a discrete logic circuit having a logic gate circuit for implementing a logic function for a data signal, a dedicated integrated circuit having a suitable combination of logic gate circuits, a programmable gate array (PGA), a field programmable gate array (FPGA), etc.

[0123] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0124] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In the description of the present invention, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0125] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0126] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations of the present invention. A person skilled in the art may change, modify, replace and vary the above embodiments within the scope of the present invention.

Claims

1. A control method for an inverter, It is characterized in that The inverter is connected to the load via a filter, and is used to convert direct current into alternating current, and supplies power to the load after filtering by the filter. The method includes: Obtaining a filter current of the filter; determining an active damping coefficient based on the filtered current; The inverter is controlled based on the active damping coefficient and the filter current.

2. The method according to claim 1, It is characterized in that The determining of the active damping coefficient based on the filter current comprises: Processing the filter current to obtain a reference value for characterizing the fluctuation amplitude of the filter current; Determining a reference interval in which the reference value is located, wherein different reference intervals correspond to different active damping coefficients; The active damping coefficient is determined based on the reference interval and the reference value.

3. The method according to claim 2, It is characterized in that The determining the active damping coefficient based on the reference interval and the reference value comprises: When the reference interval is the first interval, determining the active damping coefficient to be a first preset coefficient; When the reference interval is the second interval, determining the active damping coefficient based on the reference value and a preset mapping relationship, wherein the active damping coefficient is negatively correlated with the reference value; When the reference interval is the third interval, the active damping coefficient is determined to be a second preset coefficient, wherein the second preset coefficient is smaller than the first preset coefficient, and the reference value corresponding to the third interval is greater than the reference value corresponding to the second interval and greater than the reference value corresponding to the first interval.

4. The method according to claim 2, It is characterized in that The reference value includes one of an effective value, a peak value, a per-unit value of the effective value, and a per-unit value of the peak value of the filter current.

5. The method according to claim 1, It is characterized in that The controlling the inverter based on the active damping coefficient and the filter current includes: Obtaining the product of the active damping coefficient and the filter current to obtain an active damping voltage drop; Adjusting the initial control voltage of the inverter based on the active damping voltage drop to obtain a target control voltage; The inverter is controlled based on the target control voltage.

6. The method according to claim 5, It is characterized in that The adjusting the initial control voltage of the inverter based on the active damping voltage drop to obtain a target control voltage includes: The difference between the initial control voltage and the active damping voltage drop is obtained to obtain the target control voltage.

7. The method according to claim 5, It is characterized in that The initial control voltage is obtained by: Obtaining a voltage difference between a target output voltage and an actual output voltage of the inverter; The voltage difference is input into a voltage controller to obtain the initial control voltage.

8. The method according to claim 7, It is characterized in that The voltage controller includes one of a repetitive controller, a proportional resonant controller and a quasi-proportional resonant controller.

9. The method according to any one of claims 1 to 8, It is characterized in that The filter includes an inductor and a capacitor, and the filter current is an inductor current or a capacitor current.

10. A control device for an inverter, It is characterized in that The inverter is connected to the load through a filter, and is used to convert direct current into alternating current, and supplies power to the load after filtering by the filter. The device includes: An acquisition module, used for acquiring a filter current of the filter; A determination module, configured to determine an active damping coefficient based on the filter current; A control module is used to control the inverter based on the active damping coefficient and the filter current.

11. A controller, It is characterized in that include: A memory, a processor, and a program stored in the memory and executable on the processor, wherein when the processor executes the program, the control method for the inverter according to any one of claims 1 to 9 is implemented.

12. A photovoltaic energy storage system, It is characterized in that The invention comprises the control device of the inverter according to claim 10, or the controller according to claim 11.

13. A photovoltaic energy storage system, It is characterized in that include: Photovoltaic panels; An inverter and a filter, wherein the DC side of the inverter is connected to the photovoltaic module, and the AC side of the inverter is connected to the power grid and the load through the filter, and is used to convert the DC power of the photovoltaic module into AC power, and after filtering through the filter, feed it to the power grid and / or supply power to the load; A controller is connected to the inverter and the filter respectively, and is used to obtain a filter current of the filter when the inverter is off-grid, determine an active damping coefficient based on the filter current, and control the inverter based on the active damping coefficient and the filter current.

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