Grid-connected inverter voltage self-adaptive active support control method

Abstract

The invention provides a grid-connected inverter voltage self-adaptive active support control method. In a control period, a power grid inverter is used for collecting filter capacitor voltage and filter inductor current, and then the voltage fluctuation condition is determined to serve as a control basis and serve as a voltage self-adaptive active control signal part; compared with some embodiments in the prior art, a physically interpretable voltage adaptive parameter is obtained as a basis for control signal generation, so that the stability and control effect of the grid-connected inverter on power grid voltage adaptation are improved when a new energy grid-connected inverter generates a power grid voltage fluctuation phenomenon under a specific working condition of a weak power grid; and meanwhile, the real-time performance of control is also improved.

Description

Technical Field

[0001] The present application relates to the field of direct current grid control technology, and in particular to a method for adaptive active support control of grid-connected inverter voltage. Background Art

[0002] In the field of renewable energy power generation, power transmission is mostly completed by feeding into the public power grid through long-distance transmission lines and multiple transformers. The grid-connected inverter, as the energy conversion interface between renewable energy and the power grid, is the core equipment of the renewable energy grid-connected power generation system. Traditional grid-connected inverters lack voltage support control capabilities and have low stability in weak grids under complex working conditions. Therefore, starting from the renewable energy grid-connected inverter equipment itself, a voltage support control solution based on the renewable energy grid-connected inverter can be designed to solve such problems.

[0003] However, the existing grid-connected inverter voltage active support control method in the field of new energy has poor voltage support performance, resulting in poor control effect. Specifically, under complex working conditions, although in some feasible implementations, the voltage of the power grid is used as an input parameter of the grid-connected inverter for control, the adaptive support control capability based on specific working conditions in a weak grid environment is insufficient. Therefore, a grid-connected inverter voltage adaptive active support control method is needed to improve the grid-connected inverter's adaptability to working conditions and voltage stabilization performance. Summary of the invention

[0004] The purpose of this application is to solve at least one of the above-mentioned technical defects, especially the technical defect in the prior art that the current grid-connected inverter has insufficient adaptive support control capability based on specific working conditions in a weak grid environment.

[0005] In a first aspect, the present application provides a method for voltage adaptive active support control of a grid-connected inverter, the method being applied to a target power grid system, the topology structure of the target power grid system comprising:

[0006] A grid-connected inverter and a three-phase grid, wherein the grid-connected inverter is connected to the three-phase grid, the target grid inverter includes a three-phase LC filter, and each phase filter includes a filter inductor and a filter capacitor;

[0007] And, the method comprises:

[0008] When the current control cycle arrives, the filter capacitor voltage of each phase filter in the three-phase LC filter is obtained through the grid-connected inverter, and the grid voltage fluctuation parameter is determined according to the filter capacitor voltage;

[0009] Determining a dynamic control signal according to the grid voltage fluctuation parameter;

[0010] determining steady-state control signals;

[0011] Determining a target voltage modulation wave according to the dynamic control signal and the steady-state control signal;

[0012] A target control signal is generated according to the target voltage modulation wave, so that the grid-connected inverter adjusts the grid voltage of the target grid system according to the control signal.

[0013] As an optional implementation manner, determining a grid voltage fluctuation parameter according to the filter capacitor voltage includes:

[0014] Decomposing the filter capacitor voltage by coordinates, and determining the expression of the radial component of the grid-connected voltage and the expression of the tangential component of the grid-connected voltage by coordinate decomposition equations;

[0015] By combining the coordinate decomposition equation with the grid voltage fluctuation closed-loop equation, the grid voltage fluctuation amount and the first phase of the grid voltage are calculated;

[0016] The grid voltage fluctuation amount and the grid voltage first phase are used to indicate the fluctuation of the grid voltage;

[0017] Wherein, the coordinate decomposition equation includes:

[0018]

[0019] And, the grid-connected voltage fluctuation closed-loop equation includes:

[0020]

[0021] Among them, u Ca 、u Cb and u Cc They are the three-phase filter capacitor voltages, K p_F is the proportional adjustment coefficient for grid voltage fluctuation detection, K i_F is the integral adjustment coefficient of grid voltage fluctuation detection, u d0 is the reference value of the virtual angular momentum of the voltage space vector, s is the Laplace operator, is the grid voltage fluctuation, and δ is the first phase of the grid voltage.

[0022] As an optional implementation manner, determining the dynamic control signal according to the grid voltage fluctuation parameter includes:

[0023] Transforming the filter capacitor voltage from a three-phase stationary coordinate system to a two-phase rotating coordinate system to obtain a first rotating axis filter capacitor voltage and a second rotating axis filter capacitor voltage, and determining a second phase of the grid voltage according to the second rotating axis filter capacitor voltage;

[0024] Wherein, the second phase is used to indicate the real-time phase condition of the grid voltage;

[0025] Determining a virtual admittance value according to the grid voltage fluctuation amount;

[0026] According to the first rotating shaft filter capacitor voltage, the second rotating shaft filter capacitor voltage and the virtual admittance value, the first rotating shaft active support current command signal and the second rotating shaft active support current command signal are obtained by calculating the active support current command calculation equation.

[0027] As an optional implementation manner, determining the steady-state control signal includes:

[0028] Determine a first rotating shaft power grid following current command signal and a second rotating shaft power grid following current command signal;

[0029] And, determining a target voltage modulation wave according to the dynamic control signal and the steady-state control signal comprises:

[0030] Obtaining the filter inductor current of each phase filter in the three-phase LC filter through the grid-connected inverter;

[0031] Transforming the filter inductor current from a three-phase stationary coordinate system to a two-phase rotating coordinate system to obtain a first rotating axis filter inductor current and a second rotating axis filter inductor current;

[0032] According to the first rotating shaft filter capacitor voltage, the second rotating shaft filter capacitor voltage, the first rotating shaft active support current command signal, the second rotating shaft active support current command signal, the first rotating shaft grid following current command signal, the second rotating shaft grid following current command signal, the first rotating shaft filter inductor current and the second rotating shaft filter inductor current, a first rotating shaft voltage modulation wave and a second rotating shaft voltage modulation wave are obtained through an inductor current closed-loop control equation;

[0033] According to the second phase, transforming the first rotating shaft voltage modulated wave and the second rotating shaft voltage modulated wave from a two-phase rotating coordinate system to a three-phase stationary coordinate system to obtain a three-phase voltage modulated wave as a target voltage modulated wave;

[0034] And, generating a target control signal according to the target voltage modulation wave comprises:

[0035] The three-phase voltage modulation wave is processed by sinusoidal pulse width modulation to obtain a switch control signal corresponding to the grid-connected inverter.

[0036] As an optional implementation manner, determining the virtual admittance value according to the grid voltage fluctuation amount includes:

[0037] According to the voltage fluctuation of the power grid, a virtual admittance value is calculated by using an adaptive virtual admittance calculation formula;

[0038] The adaptive virtual admittance calculation formula includes:

[0039]

[0040] Among them, K v is the proportional coefficient of the adaptive virtual admittance adjustment, B v0 is the reference value of virtual admittance, B v is the adaptive virtual admittance value.

[0041] As an optional implementation, the active support current command calculation equation includes:

[0042]

[0043] Among them, u n is the grid-connected voltage rating, i sdref The first rotating axis actively supports the current command signal i sqref is the active support current command signal of the second rotating axis, u Cd is the first rotating axis filter capacitor voltage, u Cq is the voltage of the second rotating axis filter capacitor.

[0044] As an optional implementation manner, the inductor current closed-loop control equation includes:

[0045]

[0046] Among them, K p_CC is the proportional coefficient of the inductor current control PI regulator, K i_CC is the integral coefficient of the inductor current control PI regulator, u Cd is the first rotating axis filter capacitor voltage, u Cq is the voltage of the second rotating axis filter capacitor, i gdref is the first rotating axis grid following current command signal, i gqref is the second rotating axis grid following current command signal, i Ld is the first rotating axis filter inductor current, i Lq is the second rotating axis filter inductor current, u d is the first rotating axis voltage modulation wave, u q is the second rotating axis voltage modulation wave.

[0047] In a second aspect, the present application provides an inverter voltage adaptive active support control device, the device is applied to a target power grid system, the topology structure of the target power grid system includes:

[0048] A grid-connected inverter and a three-phase grid, wherein the grid-connected inverter is connected to the three-phase grid, the target grid inverter includes a three-phase LC filter, and each phase filter includes a filter inductor and a filter capacitor;

[0049] And, the device comprises:

[0050] A determination module, used for obtaining the filter capacitor voltage of each phase filter in the three-phase LC filter through the grid-connected inverter when the current control cycle arrives, and determining the grid voltage fluctuation parameter according to the filter capacitor voltage;

[0051] A processing module, used for determining a dynamic control signal according to the grid voltage fluctuation parameter;

[0052] The determination module is further used to determine a steady-state control signal;

[0053] The processing module is further used to determine a target voltage modulation wave according to the dynamic control signal and the steady-state control signal;

[0054] The processing module is further used to generate a target control signal according to the target voltage modulation wave, so that the grid-connected inverter adjusts the grid voltage of the target grid system according to the control signal.

[0055] In a third aspect, the present application provides a computer device comprising one or more processors and a memory, wherein the memory stores computer-readable instructions, and when the computer-readable instructions are executed by the one or more processors, the steps of the method described in the first aspect are performed.

[0056] In a fourth aspect, the present application provides a storage medium storing computer-readable instructions, which, when executed by one or more processors, causes the one or more processors to perform the steps of the method described in the first aspect.

[0057] It can be seen from the above technical solutions that the embodiments of the present application have the following advantages:

[0058] Based on any of the above embodiments, the present application determines the corresponding initial droop control coefficient through the performance parameters of each first converter, and determines the power margin of each first converter at the DC control end through the actual operating conditions, and adjusts the initial droop control coefficient according to the power margin to obtain an adaptive droop control coefficient based on the system power regulation requirements and the power regulation capability of the first converter, thereby determining a droop control equation based on the adaptive droop control coefficient to achieve regulation of the first converter. As a result, the control process of the first converter is associated with the dynamic requirements of the system and its own performance, achieving adaptive regulation, reducing the risk of poor control effect and loss of power regulation capability of the DC network due to fixed droop coefficients, and improving the stability, flexibility and effectiveness of converter droop control. BRIEF DESCRIPTION OF THE DRAWINGS

[0059] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0060] Figure 1 A schematic diagram of a power grid structure of a grid-connected inverter voltage adaptive active support control method provided by an embodiment of the present application;

[0061] Figure 2 A schematic flow chart of a method for controlling grid-connected inverter voltage adaptive active support according to an embodiment of the present application;

[0062] Figure 3 A schematic diagram of the control effect of a grid-connected inverter voltage adaptive active support control method provided by an embodiment of the present application;

[0063] Figure 4 A schematic diagram of the control effect of a grid-connected inverter voltage adaptive active support control method provided by an embodiment of the present application;

[0064] Figure 5 A schematic diagram of the control effect of a grid-connected inverter voltage adaptive active support control method provided by an embodiment of the present application;

[0065] Figure 6 A schematic diagram of the control effect of a grid-connected inverter voltage adaptive active support control method provided by an embodiment of the present application;

[0066] Figure 7 This is a diagram of the internal structure of a computer device provided in an embodiment of the present application. DETAILED DESCRIPTION

[0067] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0068] With the continuous increase in the penetration rate of renewable energy power generation, the proportion of synchronous generators in the power grid has gradually decreased. In addition, large-scale renewable energy power generation is usually located in remote areas far away from the load center, and is mostly fed into the public power grid through long-distance transmission lines and multiple transformers. The grid-connected system has complex operating conditions such as low short-circuit ratio and voltage fluctuations, which seriously affects the voltage stability of the system. As the energy conversion interface between renewable energy and the power grid, the grid-connected inverter is the core equipment of the renewable energy grid-connected power generation system. However, the traditional renewable energy grid-connected inverter lacks voltage support capability and is difficult to adapt to the grid voltage fluctuation of the high-penetration renewable energy grid-connected power generation system, and the weak grid stability is low. Domestic and foreign researchers have conducted a lot of research on the voltage support problem of the high-penetration renewable energy grid-connected power generation system. It is generally believed that starting from the renewable energy grid-connected equipment itself, controlling the grid-connected inverter to achieve active support for the grid voltage is an effective way to improve the system voltage stability and achieve stable operation of renewable energy power generation under low short-circuit ratio weak power grids.

[0069] There are some feasible ways to implement the active voltage support problem of new energy grid-connected inverters.

[0070] Specifically, one of the feasible implementation methods proposes a photovoltaic grid-connected control method with grid voltage support capability, which controls the grid-connected inverter to stabilize the grid voltage when the grid voltage drops. However, this scheme does not consider various types of fault conditions such as grid voltage imbalance, and the reactive power control link is prone to interact with the grid impedance under weak grid conditions, affecting the stability of the system.

[0071] Another feasible implementation method proposes a grid-connected inverter fusion control method based on time-sharing switching of voltage source and current source under large fluctuations in grid strength, which improves the weak-grid stability of the grid-connected inverter. However, the switching process of this scheme is likely to cause certain disturbances to the grid.

[0072] Another feasible implementation method proposes a wind farm power rapid control system that provides active support capabilities for the power grid, realizing active support of the system by wind turbines. However, this solution does not consider the voltage support of the system when the voltage of the remote power grid fluctuates greatly, and requires multi-level communication, which reduces the response speed of the system to a certain extent.

[0073] In summary, in the related field, the method of grid-connected inverter voltage adaptive active support control has the following specific shortcomings:

[0074] Although the active voltage support solution for new energy grid-connected inverters can control and improve the voltage stability of the system to a certain extent, it often targets voltage fluctuations under a single fault condition, does not consider multiple types of fault conditions such as grid voltage imbalance, and lacks adaptive support capabilities.

[0075] Although the control of new energy grid-connected inverters that integrate voltage source and current source can improve the stability of the weak power grid of the system, its switching control is likely to cause certain disturbances to the power grid, and the voltage support has a certain time lag, making it difficult to cope with sudden failures of the system.

[0076] The technical concept of the present application is that the present application obtains the filter capacitor voltage and the filter inductor current through the grid-connected inverter, and then determines the grid voltage fluctuation parameters, thereby monitoring the voltage fluctuation on the grid system, and as an input parameter, determines the adaptive current signal of the voltage active support, and further, according to the outer loop control form of the grid-connected inverter, determines the current signal followed by the grid, and combines the two parts of the current signal for processing, determines the target voltage modulation wave, and then generates a control signal to control the grid-connected inverter to adjust the voltage of the grid system, and achieves the effect of stabilizing the voltage. Specifically, because in a control cycle, the filter capacitor voltage and the filter inductor current are collected by the grid inverter, and then the voltage fluctuation is determined as the control basis, as the active control signal part of the voltage adaptation, compared with some implementation methods of the prior art, the physically interpretable voltage adaptation parameters are obtained as the basis for the generation of the control signal, which improves the stability and control effect of the grid-connected inverter on the grid voltage adaptation when the new energy grid-connected inverter generates the grid voltage fluctuation phenomenon under specific working conditions of the weak grid, and also improves the real-time performance of the control.

[0077] See also Figure 1 , Figure 1 A schematic diagram of a grid structure of a grid-connected inverter voltage adaptive active support control method provided by an embodiment of the present application is shown in FIG. Figure 1 As shown, the method provided in the present application can be applied to a target power grid system, and the target power grid system can specifically include a DC side power supply, a three-phase full-bridge inverter circuit, an LC filter, a branch transmission line impedance, a grid impedance and a three-phase power grid. The DC side power supply, the three-phase full-bridge inverter circuit, the LC filter, the branch transmission line impedance, and the grid impedance are connected in series in the aforementioned order and then connected to the three-phase power grid. The LC filter includes a filter inductor, a filter capacitor and a damping resistor.

[0078] In fact, the target grid structure used by the method involved in this application should at least include a grid-connected inverter and a three-phase grid. The grid-connected inverter is connected to the three-phase grid, and the target grid inverter includes a three-phase LC filter, and each phase filter includes a filter inductor and a filter capacitor.

[0079] It should be noted that in the data analysis process of the present application, concepts such as the first rotation axis, active component, and d-axis should be understood equivalently, and corresponding concepts such as the second rotation axis, reactive component, and q-axis should also be understood equivalently.

[0080] See also Figure 2 , Figure 2 A flowchart of a method for controlling grid-connected inverter voltage adaptive active support is provided in accordance with an embodiment of the present application. Figure 2 As shown, the method is applied to a target power grid system, and the topological structure of the target power grid system includes:

[0081] A grid-connected inverter and a three-phase grid, wherein the grid-connected inverter is connected to the three-phase grid, the target grid inverter includes a three-phase LC filter, and each phase filter includes a filter inductor and a filter capacitor;

[0082] And, the method comprises:

[0083] S101. When the current control cycle arrives, the filter capacitor voltage of each phase filter in the three-phase LC filter is obtained through the grid-connected inverter, and the grid voltage fluctuation parameter is determined according to the filter capacitor voltage;

[0084] In a control cycle, the filter capacitor voltage of each phase filter is obtained through the grid-connected inverter, and the grid voltage fluctuation parameter is determined based on the filter capacitor voltage. The parameters involved in data processing are different from those in some feasible implementation methods. The grid voltage fluctuation parameter can be further determined based on the filter capacitor voltage to describe the current grid voltage fluctuation situation. The relevant control signal components are obtained based on the fluctuation situation, so as to achieve adaptive adjustment according to the actual working conditions.

[0085] In addition, the control method involved in the present application may include real-time data acquisition and data processing, thereby executing multiple control cycles according to the control signal obtained by data processing. In the application scenario of the present application, the control method can set a termination condition or a cut-out signal when it needs to stop.

[0086] S102, determining a dynamic control signal according to the grid voltage fluctuation parameter;

[0087] The grid voltage fluctuation parameter can be further calculated to obtain a dynamic control signal related to the dynamic situation of the grid voltage fluctuation. The specific calculation method can refer to the relevant content of other implementation methods.

[0088] S103, determining a steady-state control signal;

[0089] This part of the signal is the control signal component that follows the steady-state grid condition, which can be determined based on the specific condition and the actual control algorithm. For example, it can be given according to the outer loop control requirements of the inverter, such as the control strategy of constant active or reactive control, and its setting value may be different.

[0090] S104, determining a target voltage modulation wave according to the dynamic control signal and the steady-state control signal;

[0091] As mentioned above, the control signal includes a steady-state component and a dynamic component, wherein the steady-state component is the signal instruction value set based on the specific working conditions and the actual control algorithm, and the dynamic component is the aforementioned dynamic control signal related to the dynamic situation of the grid voltage fluctuation.

[0092] S105 . Generate a target control signal according to the target voltage modulation wave, so that the grid-connected inverter adjusts the grid voltage of the target grid system according to the control signal.

[0093] The switching signals of the power devices of the grid-connected inverter are modulated and generated according to SPWM and other methods, and then the opening and closing of the power devices of the three-phase grid-connected inverter are controlled by the driving circuit.

[0094] The present application obtains the filter capacitor voltage and filter inductor current through the grid-connected inverter, and then determines the grid voltage fluctuation parameters, thereby monitoring the voltage fluctuation on the grid system, and as an input parameter, determines the adaptive current signal of the voltage active support, and further, according to the outer loop control form of the grid-connected inverter, determines the current signal followed by the grid, and combines the two parts of the current signal for processing, determines the target voltage modulation wave, and then generates a control signal to control the grid-connected inverter to adjust the voltage of the grid system, and achieves the effect of stabilizing the voltage. Specifically, because in a control cycle, the filter capacitor voltage and filter inductor current are collected by the grid inverter, and the voltage fluctuation is determined as the control basis, as the active control signal part of the voltage adaptation, compared with some implementation methods of the prior art, the physically interpretable voltage adaptation parameters are obtained as the basis for the generation of the control signal, which improves the stability and control effect of the grid-connected inverter on the grid voltage adaptation when the new energy grid-connected inverter generates the grid voltage fluctuation phenomenon under specific working conditions of the weak grid, and also improves the real-time performance of the control.

[0095] As an optional implementation manner, determining a grid voltage fluctuation parameter according to the filter capacitor voltage includes:

[0096] Decomposing the filter capacitor voltage by coordinates, and determining the expression of the radial component of the grid-connected voltage and the expression of the tangential component of the grid-connected voltage by coordinate decomposition equations;

[0097] By combining the coordinate decomposition equation with the grid-connected voltage fluctuation closed-loop equation, the grid voltage fluctuation amount and the first phase of the grid voltage are calculated;

[0098] The grid voltage fluctuation amount and the grid voltage first phase are used to indicate the fluctuation of the grid voltage;

[0099] Wherein, the coordinate decomposition equation includes:

[0100]

[0101] And, the grid-connected voltage fluctuation closed-loop equation includes:

[0102]

[0103] Among them, u Ca 、u Cb and u Cc They are the three-phase filter capacitor voltages, K p_F is the proportional adjustment coefficient for grid voltage fluctuation detection, K i_F is the integral adjustment coefficient of grid voltage fluctuation detection, u d0 is the reference value of the virtual angular momentum of the voltage space vector, s is the Laplace operator, is the grid voltage fluctuation, and δ is the first phase of the grid voltage.

[0104] This embodiment decomposes the three-phase filter capacitor voltage into radial components and tangential components through the coordinate decomposition equation expression, thereby combining with the grid voltage fluctuation closed-loop equation to solve the grid voltage fluctuation amount and the first phase of the grid voltage, so as to determine the voltage fluctuation situation through the grid voltage fluctuation amount and the first phase of the grid voltage and use this as the control basis, as the active control signal part of the voltage adaptation, which improves the stability ability and control effect of the grid-connected inverter for grid voltage adaptation when the grid voltage fluctuation phenomenon occurs in the weak grid under specific working conditions, and also improves the real-time performance of the control.

[0105] As an optional implementation manner, determining the dynamic control signal according to the grid voltage fluctuation parameter includes:

[0106] Transforming the filter capacitor voltage from a three-phase stationary coordinate system to a two-phase rotating coordinate system to obtain a first rotating axis filter capacitor voltage and a second rotating axis filter capacitor voltage, and determining a second phase of the grid voltage according to the second rotating axis filter capacitor voltage;

[0107] Wherein, the second phase is used to indicate the real-time phase condition of the grid voltage;

[0108] Determining a virtual admittance value according to the grid voltage fluctuation amount;

[0109] According to the first rotating shaft filter capacitor voltage, the second rotating shaft filter capacitor voltage and the virtual admittance value, the first rotating shaft active support current command signal and the second rotating shaft active support current command signal are obtained by calculating the active support current command calculation equation.

[0110] This embodiment performs abc-dq transformation on the three-phase filter capacitor voltage to obtain the first rotating axis filter capacitor voltage of the active part and the second rotating axis filter capacitor voltage of the reactive part, thereby realizing the decomposition of the filter capacitor voltage, and can further determine the second phase of the grid voltage, that is, the current actual phase of the grid voltage, providing a data basis for the determination or calculation of subsequent indicators. The grid voltage fluctuation amount can determine the virtual admittance value. The first rotating axis filter capacitor voltage of the active part and the second rotating axis filter capacitor voltage of the reactive part are combined with the virtual admittance value. The active support current command calculation equation provided in the subsequent implementation method can be used to calculate the first rotating axis active support current command signal of the active part and the second rotating axis active support current command signal of the reactive part, thereby providing a data basis for the determination of the final command signal, thereby realizing the determination of the dynamic control signal, improving the stability capability and control effect of the grid-connected inverter of the new energy grid-connected inverter in the weak grid under specific working conditions when the grid voltage fluctuation occurs, and at the same time improving the real-time performance of the control.

[0111] As an optional implementation manner, determining the steady-state control signal includes:

[0112] Determine a first rotating shaft power grid following current command signal and a second rotating shaft power grid following current command signal;

[0113] And, determining a target voltage modulation wave according to the dynamic control signal and the steady-state control signal comprises:

[0114] Obtaining the filter inductor current of each phase filter in the three-phase LC filter through the grid-connected inverter;

[0115] Transforming the filter inductor current from a three-phase stationary coordinate system to a two-phase rotating coordinate system to obtain a first rotating axis filter inductor current and a second rotating axis filter inductor current;

[0116] According to the first rotating shaft filter capacitor voltage, the second rotating shaft filter capacitor voltage, the first rotating shaft active support current command signal, the second rotating shaft active support current command signal, the first rotating shaft grid following current command signal, the second rotating shaft grid following current command signal, the first rotating shaft filter inductor current and the second rotating shaft filter inductor current, a first rotating shaft voltage modulation wave and a second rotating shaft voltage modulation wave are obtained through an inductor current closed-loop control equation;

[0117] According to the second phase, transforming the first rotating shaft voltage modulated wave and the second rotating shaft voltage modulated wave from a two-phase rotating coordinate system to a three-phase stationary coordinate system to obtain a three-phase voltage modulated wave as a target voltage modulated wave;

[0118] And, generating a target control signal according to the target voltage modulation wave comprises:

[0119] The three-phase voltage modulation wave is processed by sinusoidal pulse width modulation to obtain a switch control signal corresponding to the grid-connected inverter.

[0120] In the present application, the data processing process involves the decomposition of two rotating axes, namely the active component and the reactive component. Therefore, in the process of determining the steady-state control signal, the components of the two rotating axes can also be processed accordingly. Furthermore, within a control cycle, the grid-connected inverter can also obtain the filter inductor current, and the components on the two rotating axes are also obtained according to the coordinate decomposition of abc-dq. In combination with the parameters obtained above, the first rotating axis voltage modulation wave and the second rotating axis voltage modulation wave are respectively calculated on the two rotating axes, and then the modulation wave is inversely transformed according to the actual phase of the power grid to obtain the three-phase target voltage modulation wave, and the switch control signal is further obtained through modulation processing to control the three-phase thyristors in the grid-connected inverter respectively. In the data processing process of the control signal, the physical interpretability of the control signal is improved, and the grid-connected inverter of the new energy grid-connected inverter in the weak power grid under specific working conditions When the grid voltage fluctuates, the stability ability and control effect of the grid-connected inverter to adapt to the grid voltage are improved, and the real-time performance of the control is also improved.

[0121] As an optional implementation manner, determining the virtual admittance value according to the grid voltage fluctuation amount includes:

[0122] According to the voltage fluctuation of the power grid, a virtual admittance value is calculated by using an adaptive virtual admittance calculation formula;

[0123] The adaptive virtual admittance calculation formula includes:

[0124]

[0125] Among them, Kv is the proportional coefficient of the adaptive virtual admittance adjustment, B v0 is the reference value of virtual admittance, B v is the adaptive virtual admittance value.

[0126] This embodiment uses the preset proportional coefficient, the reference value of the virtual admittance, the determined reference value of the virtual angular momentum of the voltage space vector, and the grid voltage fluctuation to calculate an adaptive virtual admittance value related to the grid voltage fluctuation as the data basis for subsequent control signal generation. This can improve the stability, control effect and real-time performance of the grid-connected inverter for adaptive grid voltage when grid voltage fluctuation occurs in a weak grid under specific working conditions.

[0127] As an optional implementation manner, the active support current command calculation equation includes:

[0128]

[0129] Among them, u n is the grid-connected voltage rating, i sdref The first rotating axis actively supports the current command signal i sqref is the active support current command signal of the second rotating axis, u Cd is the first rotating axis filter capacitor voltage, u Cq is the voltage of the second rotating axis filter capacitor.

[0130] The virtual admittance value can be further processed through the active support current command calculation equation. Combined with the filter capacitor voltage obtained by decomposition, the active support current command signals of the active part and the reactive part are obtained. As the data basis for the subsequent control signal generation, it can improve the stability, control effect and real-time performance of the grid-connected inverter for new energy grid-connected inverters in weak power grids when grid voltage fluctuations occur under specific working conditions.

[0131] As an optional implementation manner, the inductor current closed-loop control equation includes:

[0132]

[0133] Among them, K p_CC is the proportional coefficient of the inductor current control PI regulator, K i_CC is the integral coefficient of the inductor current control PI regulator, u Cd is the first rotating axis filter capacitor voltage, u Cq is the voltage of the second rotating axis filter capacitor, i gdref is the first rotating axis grid following current command signal, i gqref is the second rotating axis grid following current command signal, i Ldis the first rotating axis filter inductor current, i Lq is the second rotating axis filter inductor current, u d is the first rotating axis voltage modulation wave, u q is the second rotating axis voltage modulation wave.

[0134] This implementation combines dynamic control signals and steady-state control signals, and obtains voltage modulation waves on the active and reactive rotating axes by decomposing the two aspects of the signals, thereby generating control signals to control the grid-connected inverter and thereby adjust the voltage of the power grid system, thereby achieving a stable voltage effect. This improves the stability and control effect of the grid-connected inverter in adaptively adjusting the grid voltage when the grid voltage fluctuates under specific working conditions of the weak power grid, and also improves the real-time performance of the control.

[0135] When the aforementioned embodiments are combined and implemented, see Figures 3 to 6 The schematic diagrams of various effects are used to specifically illustrate the method provided by this application.

[0136] in, Figures 3 to 6 All of them are schematic diagrams of control effects of a grid-connected inverter voltage adaptive active support control method provided by an embodiment of the present application.

[0137] Specifically, Figure 3 This is the grid-connected voltage waveform diagram when the inverter adopts traditional grid-following control and the grid voltage drops symmetrically by 50%. Figure 4 The grid-connected voltage waveform diagram is a diagram of the inverter using the AC voltage adaptive active support control of the present application when the grid voltage drops symmetrically by 50%. Figure 5 This is the grid-connected voltage waveform diagram when the single-phase grid voltage drops by 50% when the inverter adopts traditional grid-following control. Figure 6 The grid-connected voltage waveform diagram is a diagram of the inverter using the AC voltage adaptive active support control of the present application when the single-phase grid voltage drops by 50%. Figure 3 , Figure 4 , Figure 5 and Figure 6 The grid-connected voltage curve in the figure includes the line voltage U between phase a and phase b of the filter capacitor ab , the line voltage U between phase b and phase c of the filter capacitor bc , the line voltage U between the filter capacitor phase c and phase a ca .

[0138] Specifically, the present application can be applied to Figure 1 The target power grid system shown, its specific structure and parameter selection can be:

[0139] E is the DC power supply, Y is the three-phase full-bridge inverter circuit, L f is the filter inductor, C f is the filter capacitor, Rd is the damping resistor, Z t is the branch transmission line impedance, Z g The three-phase full-bridge inverter circuit Y is connected in series with the DC power supply E and the filter inductor L. f Between, the filter inductor L f The other end is connected to the branch transmission line impedance Z t , filter capacitor C f and damping resistor R d Connect in parallel to the filter inductor L f and branch transmission line impedance Z t Between, the grid impedance Z g Connect to the three-phase power grid to achieve grid connection. Figure 1 R t is the branch transmission line impedance Z t The resistive component, L t is the branch transmission line impedance Z t The perceptual component, R g is the grid impedance Z g The resistive component, L g is the grid impedance Z g The emotional weight of .

[0140] In this embodiment, the DC side voltage V dc =800V, filter inductor L f The inductance value is 0.9mH, and the filter capacitor C f The capacitance value is 11.6 uF, and the damping resistor R d The resistance is 2Ω, and the branch transmission line impedance is Z t The resistive component R t is 0.12Ω, the branch transmission line impedance Z t The perceptual component L t is 3.85mH, the grid impedance Z g The resistive component R g is 0.36Ω, the grid impedance Z g The perceptual component L g It is 11.55mH.

[0141] The current command of the grid-connected inverter in active voltage support control is composed of two parts: active support current command and grid following current command.

[0142] The grid-connected inverter samples the filter capacitor voltage and the filter inductor current once in each control cycle, wherein the steps of one control cycle are as follows:

[0143] Grid voltage fluctuation detection process:

[0144] Sampling the filter capacitor voltage u Ca 、uCb and u Cc , sample the filter inductor current i La 、i Lb and i Lc , according to the sampled filter capacitor voltage u Ca 、u Cb and u Cc , the radial component u of the grid-connected voltage is obtained by coordinate decomposition equation m and the tangential component u of the grid voltage t , the radial component u of the grid voltage m and the tangential component u of the grid voltage t The grid voltage fluctuation amount Δu and the first phase δ of the grid voltage are calculated through the grid voltage fluctuation closed-loop equation.

[0145] Wherein, the coordinate decomposition equation includes:

[0146]

[0147] And, the grid-connected voltage fluctuation closed-loop equation includes:

[0148]

[0149] Among them, u Ca 、u Cb and u Cc They are the three-phase filter capacitor voltages, K p_F is the proportional adjustment coefficient for grid voltage fluctuation detection, K i_F is the integral adjustment coefficient of grid voltage fluctuation detection, u d0 is the reference value of the virtual angular momentum of the voltage space vector, s is the Laplace operator, is the grid voltage fluctuation, and δ is the first phase of the grid voltage.

[0150] In this embodiment, according to specific simulation results, the following reference values ​​can be selected for each parameter: Kp_F=154753.6, Ki_F=17022896, ud0=30385797.8.

[0151] Voltage adaptive support current command value calculation process:

[0152] According to the sampled filter capacitor voltage u Ca 、u Cb and u Cc , the filter capacitor voltage d-axis voltage u is obtained by the transformation equation from the three-phase stationary coordinate system to the two-phase rotating coordinate system Cd and filter capacitor voltage q axis voltage u Cq ; The filter capacitor voltage q axis voltage u CqThe second phase θ of the grid voltage is obtained through phase-locked loop;

[0153] The transformation equation of the filter capacitor voltage from the three-phase stationary coordinate system to the two-phase rotating coordinate system is:

[0154]

[0155] The calculation equation of the second phase θ of the grid voltage is:

[0156]

[0157] Among them, K p_PLL K is the proportional adjustment coefficient of the phase-locked loop PI regulator, i_PLL is the integral adjustment coefficient of the phase-locked loop PI regulator, and s is the Laplace operator. In this embodiment, K p_PLL =0.266, K i_PLL =11.

[0158] According to the voltage fluctuation of the power grid, the virtual admittance value B is obtained by the adaptive virtual admittance calculation formula. v ;

[0159] The adaptive virtual admittance calculation formula includes:

[0160]

[0161] Among them, K v is the proportional coefficient of the adaptive virtual admittance adjustment, B v0 is the reference value of virtual admittance, B v is the adaptive virtual admittance value.

[0162] In this embodiment, the specific parameter value may be: K v =2.76, B v0 =0.

[0163] According to the filter capacitor voltage d-axis voltage u Cd and filter capacitor voltage q axis voltage u Cq , and the virtual admittance value B v , the active support current command value d-axis current command value and the active support q-axis current command value are obtained through the active support current command calculation equation, where the active support current command calculation equation is:

[0164]

[0165] Among them, u n is the grid-connected voltage rating, i sdref The first rotating axis actively supports the current command signal i sqref is the active support current command signal of the second rotating axis, u Cdis the first rotating axis filter capacitor voltage, u Cq is the voltage of the second rotating axis filter capacitor.

[0166] In this embodiment, the simulation can be taken as u n =311.127V.

[0167] Three-phase voltage modulation wave calculation process:

[0168] Set the d-axis current command signal i for the grid to follow gdref and the q-axis current command signal i followed by the power grid gqref , according to the filter inductor current i obtained by sampling the grid-connected inverter La 、i Lb and i Lc , the filter inductor current d-axis current i is obtained by the transformation equation from the three-phase stationary coordinate system to the two-phase rotating coordinate system Ld and filter inductor current q-axis current i Lq .

[0169] The transformation equation of the filter inductor current from the three-phase stationary coordinate system to the two-phase rotating coordinate system is:

[0170]

[0171] Wherein, θ is the second phase of the grid voltage; in this embodiment, i gdref =21.6A, i gqref =0A.

[0172] According to the filter capacitor voltage d-axis voltage u Cd and filter capacitor voltage q axis voltage u Cq , active support d-axis current command value i sdref and the active support q-axis current command value i sqref , and the grid follows the d-axis current command signal i gdref , the power grid follows the q-axis current command signal i gqref 、Filter inductor current d-axis current i Ld and filter inductor current q-axis current i Lq , the d-axis voltage modulation wave u is obtained through the inductor current closed-loop control equation d and q-axis voltage modulation wave u q .

[0173] The closed-loop control equation of the inductor current is:

[0174]

[0175] Among them, K p_CC is the proportional coefficient of the inductor current control PI regulator, K i_CCis the integral coefficient of the inductor current control PI regulator. In this embodiment, K p_CC =1,K i_CC =10.

[0176] According to the second phase θ of the grid voltage and the d-axis voltage modulation wave u d and q-axis voltage modulation wave u q , through the transformation equation from the two-phase rotating coordinate system to the three-phase stationary coordinate system, the three-phase voltage modulation wave u is calculated a ,u b ,u c .

[0177] The transformation equation of the voltage modulation wave from the two-phase rotating coordinate system to the three-phase stationary coordinate system is:

[0178]

[0179] Similarly, θ is the second phase of the grid voltage.

[0180] According to the obtained three-phase voltage modulation wave u a ,u b ,u c , the switching signal of the grid-connected inverter power device is generated through SPWM modulation, and then the opening and closing of the three-phase grid-connected inverter power device is controlled by the drive circuit.

[0181] After that, enter the next control cycle.

[0182] In order to demonstrate the beneficial effects of the present application, data simulation of a virtual platform was performed on the present application.

[0183] Figure 3 This is the grid-connected voltage waveform diagram when the inverter adopts traditional grid-following control and the grid voltage drops symmetrically by 50%. Figure 4 The grid-connected voltage waveform diagram is a diagram of the inverter using the AC voltage adaptive active support control of the present application when the grid voltage drops symmetrically by 50%. Figure 5 This is the grid-connected voltage waveform diagram when the single-phase grid voltage drops by 50% when the inverter adopts traditional grid-following control. Figure 6 The grid-connected voltage waveform diagram is a diagram of the inverter using the AC voltage adaptive active support control of the present application when the single-phase grid voltage drops by 50%. Figure 3 , Figure 4 , Figure 5 and Figure 6 The grid-connected voltage curve in the figure includes the line voltage U between phase a and phase b of the filter capacitor ab , the line voltage U between phase b and phase c of the filter capacitor bc , the line voltage U between the filter capacitor phase c and phase a ca .

[0184] like Figure 3 As shown, at 5 seconds, the grid voltage drops symmetrically by 50%. When the inverter adopts traditional grid-following control, the grid-connected line voltage U ab , U bc , U ca A large drop occurs, and the inverter cannot provide active voltage support. Figure 4 As shown, the grid voltage drops symmetrically by 50% at 5 seconds. When the inverter adopts the AC voltage adaptive active support control of the present application, the grid line voltage U ab , U bc , U ca The smaller the drop, the more active the inverter is. Figure 5 As shown in the figure, at 5 seconds, the grid phase a voltage drops by 50%. When the inverter adopts traditional grid-following control, the grid line voltage U ab , U bc , U ca A large imbalance has occurred, seriously affecting the quality of grid-connected power. Figure 6 As shown, at 5 seconds, the grid phase a voltage drops by 50%. When the inverter adopts the voltage adaptive active support control provided by the present application, the grid line voltage U ab , U bc , U ca The degree of imbalance Figure 5 Significantly reduced, effectively improving the voltage quality of the system

[0185] The embodiment of the present application further provides a grid-connected inverter voltage adaptive active support control device to implement the above method, the device is applied to a target power grid system, and the topology structure of the target power grid system includes:

[0186] A grid-connected inverter and a three-phase grid, wherein the grid-connected inverter is connected to the three-phase grid, the target grid inverter includes a three-phase LC filter, and each phase filter includes a filter inductor and a filter capacitor;

[0187] And, the device comprises:

[0188] A determination module, used for obtaining the filter capacitor voltage of each phase filter in the three-phase LC filter through the grid-connected inverter when the current control cycle arrives, and determining the grid voltage fluctuation parameter according to the filter capacitor voltage;

[0189] A processing module, used for determining a dynamic control signal according to the grid voltage fluctuation parameter;

[0190] The determination module is further used to determine a steady-state control signal;

[0191] The processing module is further used to determine a target voltage modulation wave according to the dynamic control signal and the steady-state control signal;

[0192] The processing module is further used to generate a target control signal according to the target voltage modulation wave, so that the grid-connected inverter adjusts the grid voltage of the target grid system according to the control signal.

[0193] The present application obtains the filter capacitor voltage and filter inductor current through the grid-connected inverter, and then determines the grid voltage fluctuation parameters, thereby monitoring the voltage fluctuation on the grid system, and as an input parameter, determines the adaptive current signal of the voltage active support, and further, according to the outer loop control form of the grid-connected inverter, determines the current signal followed by the grid, and combines the two parts of the current signal for processing, determines the target voltage modulation wave, and then generates a control signal to control the grid-connected inverter to adjust the voltage of the grid system, and achieves the effect of stabilizing the voltage. Specifically, because in a control cycle, the filter capacitor voltage and filter inductor current are collected by the grid inverter, and the voltage fluctuation is determined as the control basis, as the active control signal part of the voltage adaptation, compared with some implementation methods of the prior art, the physically interpretable voltage adaptation parameters are obtained as the basis for the generation of the control signal, which improves the stability and control effect of the grid-connected inverter on the grid voltage adaptation when the new energy grid-connected inverter generates the grid voltage fluctuation phenomenon under specific working conditions of the weak grid, and also improves the real-time performance of the control.

[0194] As an optional implementation manner, the specific manner in which the determining module determines the grid voltage fluctuation parameter according to the filter capacitor voltage includes:

[0195] Decomposing the filter capacitor voltage by coordinates, and determining the expression of the radial component of the grid-connected voltage and the expression of the tangential component of the grid-connected voltage by coordinate decomposition equations;

[0196] By combining the coordinate decomposition equation with the grid-connected voltage fluctuation closed-loop equation, the grid voltage fluctuation amount and the first phase of the grid voltage are calculated;

[0197] The grid voltage fluctuation amount and the grid voltage first phase are used to indicate the fluctuation of the grid voltage;

[0198] Wherein, the coordinate decomposition equation includes:

[0199]

[0200] And, the grid-connected voltage fluctuation closed-loop equation includes:

[0201]

[0202] Among them, u Ca 、u Cb and u Cc They are the three-phase filter capacitor voltages, K p_F is the proportional adjustment coefficient for grid voltage fluctuation detection, K i_F is the integral adjustment coefficient of grid voltage fluctuation detection, u d0 is the reference value of the virtual angular momentum of the voltage space vector, s is the Laplace operator, is the grid voltage fluctuation, and δ is the first phase of the grid voltage.

[0203] This embodiment decomposes the three-phase filter capacitor voltage into radial components and tangential components through the coordinate decomposition equation expression, thereby combining with the grid voltage fluctuation closed-loop equation to solve the grid voltage fluctuation amount and the first phase of the grid voltage, so as to determine the voltage fluctuation situation through the grid voltage fluctuation amount and the first phase of the grid voltage and use this as the control basis, as the active control signal part of the voltage adaptation, which improves the stability ability and control effect of the grid-connected inverter for grid voltage adaptation when the grid voltage fluctuation phenomenon occurs in the weak grid under specific working conditions, and also improves the real-time performance of the control.

[0204] As an optional implementation manner, the processing module determines a specific manner of the dynamic control signal according to the grid voltage fluctuation parameter, including:

[0205] Transforming the filter capacitor voltage from a three-phase stationary coordinate system to a two-phase rotating coordinate system to obtain a first rotating axis filter capacitor voltage and a second rotating axis filter capacitor voltage, and determining a second phase of the grid voltage according to the second rotating axis filter capacitor voltage;

[0206] Wherein, the second phase is used to indicate the real-time phase condition of the grid voltage;

[0207] Determining a virtual admittance value according to the grid voltage fluctuation amount;

[0208] According to the first rotating shaft filter capacitor voltage, the second rotating shaft filter capacitor voltage and the virtual admittance value, the first rotating shaft active support current command signal and the second rotating shaft active support current command signal are obtained by calculating the active support current command calculation equation.

[0209] This embodiment performs abc-dq transformation on the three-phase filter capacitor voltage to obtain the first rotating axis filter capacitor voltage of the active part and the second rotating axis filter capacitor voltage of the reactive part, thereby realizing the decomposition of the filter capacitor voltage, and can further determine the second phase of the grid voltage, that is, the current actual phase of the grid voltage, providing a data basis for the determination or calculation of subsequent indicators. The grid voltage fluctuation amount can determine the virtual admittance value. The first rotating axis filter capacitor voltage of the active part and the second rotating axis filter capacitor voltage of the reactive part are combined with the virtual admittance value. The active support current command calculation equation provided in the subsequent implementation method can be used to calculate the first rotating axis active support current command signal of the active part and the second rotating axis active support current command signal of the reactive part, thereby providing a data basis for the determination of the final command signal, thereby realizing the determination of the dynamic control signal, improving the stability capability and control effect of the grid-connected inverter of the new energy grid-connected inverter in the weak grid under specific working conditions when the grid voltage fluctuation occurs, and at the same time improving the real-time performance of the control.

[0210] As an optional implementation manner, the specific manner in which the determination module determines the steady-state control signal includes:

[0211] Determine a first rotating shaft power grid following current command signal and a second rotating shaft power grid following current command signal;

[0212] And, determining a target voltage modulation wave according to the dynamic control signal and the steady-state control signal comprises:

[0213] Obtaining the filter inductor current of each phase filter in the three-phase LC filter through the grid-connected inverter;

[0214] Transforming the filter inductor current from a three-phase stationary coordinate system to a two-phase rotating coordinate system to obtain a first rotating axis filter inductor current and a second rotating axis filter inductor current;

[0215] According to the first rotating shaft filter capacitor voltage, the second rotating shaft filter capacitor voltage, the first rotating shaft active support current command signal, the second rotating shaft active support current command signal, the first rotating shaft grid following current command signal, the second rotating shaft grid following current command signal, the first rotating shaft filter inductor current and the second rotating shaft filter inductor current, a first rotating shaft voltage modulation wave and a second rotating shaft voltage modulation wave are obtained through an inductor current closed-loop control equation;

[0216] According to the second phase, transforming the first rotating shaft voltage modulated wave and the second rotating shaft voltage modulated wave from a two-phase rotating coordinate system to a three-phase stationary coordinate system to obtain a three-phase voltage modulated wave as a target voltage modulated wave;

[0217] And, generating a target control signal according to the target voltage modulation wave comprises:

[0218] The three-phase voltage modulation wave is processed by sinusoidal pulse width modulation to obtain a switch control signal corresponding to the grid-connected inverter.

[0219] In the present application, the data processing process involves the decomposition of two rotating axes, namely the active component and the reactive component. Therefore, in the process of determining the steady-state control signal, the components of the two rotating axes can also be processed accordingly. Furthermore, within a control cycle, the grid-connected inverter can also obtain the filter inductor current, and the components on the two rotating axes are also obtained according to the coordinate decomposition of abc-dq. In combination with the parameters obtained above, the first rotating axis voltage modulation wave and the second rotating axis voltage modulation wave are respectively calculated on the two rotating axes, and then the modulation wave is inversely transformed according to the actual phase of the power grid to obtain the three-phase target voltage modulation wave, and the switch control signal is further obtained through modulation processing to control the three-phase thyristors in the grid-connected inverter respectively. In the data processing process of the control signal, the physical interpretability of the control signal is improved, and the grid-connected inverter of the new energy grid-connected inverter in the weak power grid under specific working conditions When the grid voltage fluctuates, the stability ability and control effect of the grid-connected inverter to adapt to the grid voltage are improved, and the real-time performance of the control is also improved.

[0220] As an optional implementation manner, the specific manner in which the processing module determines the virtual admittance value according to the grid voltage fluctuation includes:

[0221] According to the voltage fluctuation of the power grid, a virtual admittance value is calculated by using an adaptive virtual admittance calculation formula;

[0222] The adaptive virtual admittance calculation formula includes:

[0223]

[0224] Among them, K v is the proportional coefficient of the adaptive virtual admittance adjustment, B v0 is the reference value of virtual admittance, B v is the adaptive virtual admittance value.

[0225] This embodiment uses the preset proportional coefficient, the reference value of the virtual admittance, the determined reference value of the virtual angular momentum of the voltage space vector, and the grid voltage fluctuation to calculate an adaptive virtual admittance value related to the grid voltage fluctuation as the data basis for subsequent control signal generation. This can improve the stability, control effect and real-time performance of the grid-connected inverter for adaptive grid voltage when grid voltage fluctuation occurs in a weak grid under specific working conditions.

[0226] As an optional implementation, the active support current command calculation equation includes:

[0227]

[0228] Among them, u n is the grid-connected voltage rating, i sdref The first rotating axis actively supports the current command signal i sqref is the active support current command signal of the second rotating axis, u Cd is the first rotating axis filter capacitor voltage, u Cq is the voltage of the second rotating axis filter capacitor.

[0229] The virtual admittance value can be further processed through the active support current command calculation equation. Combined with the filter capacitor voltage obtained by decomposition, the active support current command signals of the active part and the reactive part are obtained. As the data basis for the subsequent control signal generation, it can improve the stability, control effect and real-time performance of the grid-connected inverter for new energy grid-connected inverters in weak power grids when grid voltage fluctuations occur under specific working conditions.

[0230] As an optional implementation manner, the inductor current closed-loop control equation includes:

[0231]

[0232] Among them, K p_CC is the proportional coefficient of the inductor current control PI regulator, K i_CC is the integral coefficient of the inductor current control PI regulator, u Cd is the first rotating axis filter capacitor voltage, u Cq is the voltage of the second rotating axis filter capacitor, i gdref is the first rotating axis grid following current command signal, i gqref is the second rotating axis grid following current command signal, i Ld is the first rotating axis filter inductor current, i Lq is the second rotating axis filter inductor current, u d is the first rotating axis voltage modulation wave, u q is the second rotating axis voltage modulation wave.

[0233] This implementation combines dynamic control signals and steady-state control signals, and obtains voltage modulation waves on the active and reactive rotating axes by decomposing the two aspects of the signals, thereby generating control signals to control the grid-connected inverter and thereby adjust the voltage of the power grid system, thereby achieving a stable voltage effect. This improves the stability and control effect of the grid-connected inverter in adaptively adjusting the grid voltage when the grid voltage fluctuates under specific working conditions of the weak power grid, and also improves the real-time performance of the control.

[0234] It should be noted that it should be understood that the division of the various modules of the above device is only a division of logical functions. In actual implementation, they can be fully or partially integrated into one physical entity, or they can be physically separated. And these modules can all be implemented in the form of software called by processing elements; they can also be all implemented in the form of hardware; some modules can also be implemented in the form of software called by processing elements, and some modules can be implemented in the form of hardware. For example, the determination module can be a separately established processing element, or it can be integrated in a chip of the above device. In addition, it can also be stored in the memory of the above device in the form of program code, and called and executed by a processing element of the above device. The implementation of other modules is similar. In addition, these modules can be fully or partially integrated together, or they can be implemented independently. The processing element here can be an integrated circuit with signal processing capabilities. In the implementation process, each step of the above method or each module above can be completed by an integrated logic circuit of hardware in the processor element or instructions in the form of software.

[0235] Indicatively, Figure 7 As shown, Figure 7 This is a schematic diagram of the internal structure of a computer device provided in an embodiment of the present application. The computer device 300 may be provided as a server. Figure 7 The computer device 300 includes a processing component 302, which further includes one or more processors, and a memory resource represented by a memory 301 for storing instructions executable by the processing component 302, such as an application. The application stored in the memory 301 may include one or more modules, each corresponding to a set of instructions. In addition, the processing component 302 is configured to execute the instructions to perform the text recognition method of any of the above embodiments.

[0236] The computer device 300 may further include a power supply component 303 configured to perform power management of the computer device 300, a wired or wireless network interface 304 configured to connect the computer device 300 to a network, and an input / output (I / O) interface 305. The computer device 300 may operate based on an operating system stored in the memory 301, such as Windows Server TM, Mac OS X TM, Unix TM, Linux TM, Free BSD TM, or the like.

[0237] Those skilled in the art will understand that Figure 7 The structure shown in the figure is only a block diagram of a part of the structure related to the solution of the present application, and does not constitute a limitation on the computer device to which the solution of the present application is applied. The specific computer device may include more or fewer components than those shown in the figure, or combine certain components, or have a different arrangement of components.

[0238] An embodiment of the present application provides a storage medium, in which computer-readable instructions are stored. When the computer-readable instructions are executed by one or more processors, the one or more processors execute a method provided in any embodiment.

[0239] Finally, it should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "comprise a ..." do not exclude the presence of other identical elements in the process, method, article or device including the elements.

[0240] The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The various embodiments can be combined as needed, and the same or similar parts can refer to each other.

[0241] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present application. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to the embodiments shown herein, but will conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A grid-connected inverter voltage adaptive active support control method, characterized in that: The method is applied to a target power grid system, wherein the topological structure of the target power grid system includes: A grid-connected inverter and a three-phase grid, wherein the grid-connected inverter is connected to the three-phase grid, the target grid inverter includes a three-phase LC filter, and each phase filter includes a filter inductor and a filter capacitor; And, the method comprises: When the current control cycle arrives, the filter capacitor voltage of each phase filter in the three-phase LC filter is obtained through the grid-connected inverter, and the grid voltage fluctuation parameter is determined according to the filter capacitor voltage; Determining a dynamic control signal according to the grid voltage fluctuation parameter; determining steady-state control signals; Determining a target voltage modulation wave according to the dynamic control signal and the steady-state control signal; A target control signal is generated according to the target voltage modulation wave, so that the grid-connected inverter adjusts the grid voltage of the target grid system according to the control signal.

2. The method according to claim 1, characterized in that The determining of the grid voltage fluctuation parameter according to the filter capacitor voltage comprises: Decomposing the filter capacitor voltage by coordinates, and determining the expression of the radial component of the grid-connected voltage and the expression of the tangential component of the grid-connected voltage by coordinate decomposition equations; By combining the coordinate decomposition equation with the grid voltage fluctuation closed-loop equation, the grid voltage fluctuation amount and the first phase of the grid voltage are calculated; The grid voltage fluctuation amount and the grid voltage first phase are used to indicate the fluctuation of the grid voltage; Wherein, the coordinate decomposition equation includes: And, the grid-connected voltage fluctuation closed-loop equation includes: Among them, u Ca 、u Cb and u Cc They are the three-phase filter capacitor voltages, K p_F is the proportional adjustment coefficient for grid voltage fluctuation detection, K i_F is the integral adjustment coefficient of grid voltage fluctuation detection, u d0 is the reference value of the virtual angular momentum of the voltage space vector, s is the Laplace operator, is the grid voltage fluctuation, and δ is the first phase of the grid voltage.

3. The method according to claim 2, characterized in that The step of determining a dynamic control signal according to the grid voltage fluctuation parameter comprises: Transforming the filter capacitor voltage from a three-phase stationary coordinate system to a two-phase rotating coordinate system to obtain a first rotating axis filter capacitor voltage and a second rotating axis filter capacitor voltage, and determining a second phase of the grid voltage according to the second rotating axis filter capacitor voltage; Wherein, the second phase is used to indicate the real-time phase condition of the grid voltage; Determining a virtual admittance value according to the grid voltage fluctuation amount; According to the first rotating shaft filter capacitor voltage, the second rotating shaft filter capacitor voltage and the virtual admittance value, the first rotating shaft active support current command signal and the second rotating shaft active support current command signal are obtained by calculating the active support current command calculation equation.

4. The method according to claim 3, characterized in that The determining of the steady-state control signal comprises: Determine a first rotating shaft power grid following current command signal and a second rotating shaft power grid following current command signal; And, determining a target voltage modulation wave according to the dynamic control signal and the steady-state control signal comprises: Obtaining the filter inductor current of each phase filter in the three-phase LC filter through the grid-connected inverter; Transforming the filter inductor current from a three-phase stationary coordinate system to a two-phase rotating coordinate system to obtain a first rotating axis filter inductor current and a second rotating axis filter inductor current; According to the first rotating shaft filter capacitor voltage, the second rotating shaft filter capacitor voltage, the first rotating shaft active support current command signal, the second rotating shaft active support current command signal, the first rotating shaft grid following current command signal, the second rotating shaft grid following current command signal, the first rotating shaft filter inductor current and the second rotating shaft filter inductor current, a first rotating shaft voltage modulation wave and a second rotating shaft voltage modulation wave are obtained through an inductor current closed-loop control equation; According to the second phase, transforming the first rotating shaft voltage modulated wave and the second rotating shaft voltage modulated wave from a two-phase rotating coordinate system to a three-phase stationary coordinate system to obtain a three-phase voltage modulated wave as a target voltage modulated wave; And, generating a target control signal according to the target voltage modulation wave comprises: The three-phase voltage modulation wave is processed by sinusoidal pulse width modulation to obtain a switch control signal corresponding to the grid-connected inverter.

5. The method according to claim 3, characterized in that: The determining of the virtual admittance value according to the grid voltage fluctuation comprises: According to the voltage fluctuation of the power grid, a virtual admittance value is calculated by using an adaptive virtual admittance calculation formula; The adaptive virtual admittance calculation formula includes: Among them, K v is the proportional coefficient of the adaptive virtual admittance adjustment, B v0 is the reference value of virtual admittance, B v is the adaptive virtual admittance value.

6. The method according to claim 5, characterized in that The active support current command calculation equation includes: Among them, u n is the grid-connected voltage rating, i sdref The first rotating axis actively supports the current command signal i sqref is the active support current command signal of the second rotating axis, u Cd is the first rotating axis filter capacitor voltage, u Cq is the voltage of the second rotating axis filter capacitor.

7. The method according to claim 6, characterized in that The inductor current closed-loop control equation includes: Among them, K p_CC is the proportional coefficient of the inductor current control PI regulator, K i_CC is the integral coefficient of the inductor current control PI regulator, u Cd is the first rotating axis filter capacitor voltage, u Cq is the voltage of the second rotating axis filter capacitor, i gdref is the first rotating axis grid following current command signal, i gqref is the second rotating axis grid following current command signal, i Ld is the first rotating axis filter inductor current, i Lq is the second rotating axis filter inductor current, u d is the first rotating axis voltage modulation wave, u q is the second rotating axis voltage modulation wave.

8. A grid-connected inverter voltage adaptive active support control device, characterized in that: The device is applied to a target power grid system, and the topological structure of the target power grid system includes: A grid-connected inverter and a three-phase grid, wherein the grid-connected inverter is connected to the three-phase grid, the target grid inverter includes a three-phase LC filter, and each phase filter includes a filter inductor and a filter capacitor; And, the device comprises: A determination module, used for obtaining the filter capacitor voltage of each phase filter in the three-phase LC filter through the grid-connected inverter when the current control cycle arrives, and determining the grid voltage fluctuation parameter according to the filter capacitor voltage; A processing module, used for determining a dynamic control signal according to the grid voltage fluctuation parameter; The determination module is further used to determine a steady-state control signal; The processing module is further used to determine a target voltage modulation wave according to the dynamic control signal and the steady-state control signal; The processing module is further used to generate a target control signal according to the target voltage modulation wave, so that the grid-connected inverter adjusts the grid voltage of the target grid system according to the control signal.

9. A computer device, characterized in that: The method comprises one or more processors and a memory, wherein the memory stores computer-readable instructions, and when the computer-readable instructions are executed by the one or more processors, the steps of the method according to any one of claims 1 to 7 are performed.

10. A storage medium, characterized in that: The storage medium stores computer-readable instructions, and when the computer-readable instructions are executed by one or more processors, the one or more processors execute the steps of the method according to any one of claims 1 to 7.

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