Converter control method, controller and power grid power conversion system

Abstract

The embodiment of the present application provides a control method, controller and power conversion system of a converter. The method is applied to a converter, which is used to convert the electric energy of a transmission network; the method includes: obtaining the power data of the converter; using a pre-built converter control model to process the power data and obtain the control data of the converter, the control data is used to control the operating state of the converter, wherein the converter control model is obtained by discretizing a state observer model constructed by the power parameters of the filter and the parameter changes of the converter. The method is used to achieve the effect of improving the control performance of the converter.

Description

Technical Field

[0001] The present application relates to the technical field of electric energy conversion, and in particular to a control method of a converter, a controller and a power grid power conversion system. Background Art

[0002] With the shortage of energy and the impact of fuel-induced environmental degradation, renewable energy as a new energy source has entered a period of rapid development. Distributed generation systems based on renewable energy have become the current research focus, and the energy conversion of the main part of distributed generation systems has become increasingly important. In order to attenuate the switching ripple of the output current, a filter is usually placed between the converter of the voltage source and the transmission network. Among the different filter topologies, the filter is usually used as an interface between the grid-connected converter and the utility because the filter performs better in attenuating high-order harmonics, achieving smaller inductor voltage drops and saving physical size.

[0003] In order to reduce the impact that the filter may have on the stability of the distributed generation system, the control method of the converter in the traditional technology has a control strategy of suppressing the interference of the grid voltage through an observer.

[0004] However, the control strategy for the converter in the traditional technology has the problem of low control performance. Summary of the invention

[0005] Based on this, it is necessary to address the above technical issues. The embodiments of the present application provide a control method, a controller and a power grid power conversion system for a converter to achieve the effect of improving the control performance of the control strategy.

[0006] In a first aspect, an embodiment of the present application provides a method for determining a converter control model, which is applied to a converter, where the converter is used to convert electric energy of a transmission network; the method comprises:

[0007] Obtain power data from the converter;

[0008] The power data is processed by using a pre-built converter control model to obtain converter control data, which is used to control the operating state of the converter. The converter control model is discretized by using a state observer model constructed through the power parameters of the filter and the parameter changes of the converter.

[0009] In a possible implementation, the method further includes:

[0010] Obtaining power parameters of the filter and parameter changes of the converter, and obtaining observer parameters corresponding to a pre-built state observer model based on the power parameters and parameter changes;

[0011] A state observer model for the converter is obtained according to observer parameters and a pre-built state observer model;

[0012] Acquire current data and voltage data of the transmission network, and use the state observer model to process the current data and voltage data to obtain a discrete state observer model;

[0013] Based on the discrete state observer model, the converter control model is constructed.

[0014] In a possible implementation, the state observer model is used to process the current data and the voltage data to obtain a discrete state observer model, including:

[0015] Using the state observer model, the current data and the voltage data are processed to obtain the state observer model matrix;

[0016] Based on the state observer model matrix, a discrete state observer model is obtained.

[0017] In a possible implementation, after obtaining a discrete state observer model based on the state observer model matrix, the following steps are included:

[0018] According to the sampling frequency corresponding to the state observer model and the state estimation parameters of the state observer model, the pole parameters of the discrete state observer model are obtained;

[0019] According to the pole parameters of the discrete state observer model, the stability of the discrete state observer model is obtained.

[0020] In a possible implementation, a converter control model is constructed based on a discrete state observer model, including:

[0021] According to the current data of the filter, a state space current controller is constructed;

[0022] Based on the state-space current controller and discrete state observer model, the converter control model is obtained.

[0023] In a possible implementation manner, after constructing the state-space current controller according to the current data of the filter, the method further includes:

[0024] Get the sampling frequency corresponding to the state observer model;

[0025] According to the sampling frequency, discrete pole parameters of the state space current controller are obtained;

[0026] Based on the discrete pole parameters, the stability of the state-space current controller is obtained.

[0027] In a possible implementation, based on the power parameters and the parameter changes, obtaining observer parameters corresponding to the pre-built state observer model includes:

[0028] Based on the power parameters and parameter changes, a state space model representing the state change of the converter is obtained;

[0029] According to the state space model and the pre-built state observer model, the observer parameters are obtained.

[0030] In a possible implementation, obtaining observer parameters according to the state space model and the pre-built state observer model includes:

[0031] Obtain the error model between the state-space model and the pre-built state observer model;

[0032] According to the error model, the error state matrix corresponding to the error model is obtained;

[0033] Based on the error state matrix, the observer parameters are obtained.

[0034] In a possible implementation manner, after obtaining a state observer model for the converter according to the observer parameters and the pre-built state observer model, the method further includes:

[0035] Obtain a transfer function model corresponding to the state observer model;

[0036] The initial output voltage of the converter is processed using the transfer function model to obtain the stable state of the state observer model.

[0037] In a second aspect, an embodiment of the present application provides a method for determining a converter control model, the method comprising:

[0038] Obtaining power parameters of the filter and parameter changes of the converter, and obtaining observer parameters corresponding to a pre-built state observer model based on the power parameters and parameter changes;

[0039] A state observer model for the converter is obtained according to observer parameters and a pre-built state observer model;

[0040] Acquire current data and voltage data of the transmission network, and use the state observer model to process the current data and voltage data to obtain a discrete state observer model;

[0041] Based on the discrete state observer model, the converter control model is constructed.

[0042] In a third aspect, an embodiment of the present application provides a controller, including: a memory, a processor;

[0043] Memory stores computer-executable instructions;

[0044] The processor executes the computer-executable instructions stored in the memory, so that the processor performs the above-mentioned method.

[0045] In a fourth aspect, an embodiment of the present application provides a power grid power conversion system, the system comprising:

[0046] A converter for supplying power to a load;

[0047] Filter, connected to the converter, and also used to connect to the transmission grid;

[0048] The controller as mentioned above is connected to the converter and the filter respectively, and is also used to connect to the transmission network.

[0049] In a fifth aspect, an embodiment of the present application provides a computer-readable storage medium, in which computer-executable instructions are stored. When the computer-executable instructions are executed by a processor, they are used to implement various possible implementations of the method as described above.

[0050] In a sixth aspect, an embodiment of the present application provides a computer program product, including a computer program, which implements various possible implementation methods of the above method when executed by a processor.

[0051] The control method, controller and power grid power conversion system of the converter provided by the embodiment of the present application, the control method of the converter includes: obtaining the power data of the converter; using the pre-built converter control model to process the power data and obtain the control data of the converter; wherein the converter control model is obtained by discretizing the state observer model constructed by the power parameters of the filter and the parameter changes of the converter; according to the control data, the operating state of the converter is controlled. In this way, compared with the traditional technology, the present application can construct a state observer for the change of power parameters by outputting the power parameters of the filter and the parameter changes of the converter, and the converter control model can be obtained after discretizing the state observer, so that the state observer can be used to compensate for the disturbance of the converter, thereby improving the high-performance control of the converter. BRIEF DESCRIPTION OF THE DRAWINGS

[0052] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present application and, together with the description, serve to explain the principles of the present application.

[0053] Figure 1 A schematic diagram of a power grid power conversion system provided for this application;

[0054] Figure 2 The process diagram of the control method of the converter provided in this application is as follows Figure 1 ;

[0055] Figure 3 The process diagram of the control method of the converter provided in this application is as follows Figure 2 ;

[0056] Figure 4 The process diagram of the control method of the converter provided in this application is as follows Figure 3 ;

[0057] Figure 5 A schematic diagram of a discrete state observer model provided in this application;

[0058] Figure 6 A schematic diagram of the effect of parameter changes on the stability of a control model based on a Bode diagram provided in this application;

[0059] Figure 7 The process diagram of the control method of the converter provided in this application is as follows Figure 4 ;

[0060] Figure 8 A flow chart of a method for determining a converter control model provided in the present application;

[0061] Fig. 9 A schematic diagram of a state observer model provided in an embodiment of the present application;

[0062] Fig.10 A schematic diagram of the root locus provided in an embodiment of the present application;

[0063] Fig.11 The process diagram of the control method of the converter provided in this application is as follows Figure 5 ;

[0064] Fig.12 A logic diagram of a control method for a converter provided in the present application;

[0065] Fig.13 A schematic diagram of the structure of the control device of the converter provided in this application;

[0066] Fig.14 A schematic diagram of the structure of the controller provided in this application.

[0067] The above drawings have shown clear embodiments of the present application, which will be described in more detail later. These drawings and text descriptions are not intended to limit the scope of the present application in any way, but to illustrate the concept of the present application to those skilled in the art by referring to specific embodiments. DETAILED DESCRIPTION

[0068] In order to make the purpose, technical solutions and advantages of the present application clearer, exemplary embodiments will be described in detail here, and examples thereof are shown in the accompanying drawings. When the following description refers to the drawings, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements. The implementation methods described in the following exemplary embodiments do not represent all implementation methods consistent with the present application. On the contrary, they are merely examples of devices and implementation methods consistent with some aspects of the present application as detailed in the attached claims. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0069] The terms "first", "second", "third", "fourth", etc. (if any) in the specification and claims of the present application and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged where appropriate, so that the embodiments of the present application described herein, for example, can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions, for example, a series of units, systems, products or devices are not necessarily limited to those units clearly listed, but may include units that are not clearly listed or inherent to these products or devices.

[0070] Figure 1 A schematic diagram of a grid power conversion system provided for this application, such as Figure 1 As shown, the specific application scenario of the present application can be applied to control the converter 101. The converter can be applied to convert the electric energy of the transmission network, and the converter can be a grid-connected converter with an LCL filter.

[0071] The method for determining the converter control model provided in the present application, by constructing a state observer for changes in power parameters, can use the state observer model to discretize the processed current data and voltage data. The discretized state observer can better realize the construction of the converter control model, thereby solving the technical problem of low control performance of the converter control strategy.

[0072] The technical solution of the present application and how the technical solution of the present application solves the above-mentioned technical problems are described in detail below with specific embodiments. The following specific embodiments can be combined with each other, and the same or similar concepts or processes may not be repeated in some embodiments. The embodiments of the present application will be described below in conjunction with the accompanying drawings.

[0073] Figure 2 Schematic diagram of the process of determining the converter control model provided in this application Figure 1 ,like Figure 2As shown, the method can be applied to a converter, and the converter is used to convert the electric energy of a transmission network. The method includes S201 to S203, wherein:

[0074] S201, obtaining power data of the converter.

[0075] The power data of the converter may be current data, voltage data, etc. collected from the converter.

[0076] Exemplarily, the current data of the transformer can be collected by a current sensor, and the voltage data of the transformer can be collected by a voltage sensor. The controller can directly obtain the current data and voltage data through the current sensor and the voltage sensor to complete the acquisition of the power data of the converter.

[0077] S202, using a pre-built converter control model, processing power data to obtain converter control data, the control data is used to control the operating state of the converter, wherein the converter control model is discretized by a state observer model constructed through the power parameters of the filter and the parameter changes of the converter.

[0078] The filter may be an LCL filter, the filter may be a filter of the converter, and the control data may be pulse data.

[0079] Exemplarily, the controller can construct a state observer model in advance based on the power parameters of the filter and the parameter changes of the converter, and can further discretize the state observer model to obtain a discrete state observer model, and obtain the converter control model based on the discrete state observer model.

[0080] Optionally, the controller processes the power data of the converter using the converter control model to obtain control data for controlling the converter, so as to compensate for the state change of the converter through the control data.

[0081] In practical applications, the controller can collect the current data and voltage data of the transmission network, and can discretize the state observer model by processing the current data and voltage data using the state observer model to obtain a discrete state observer model. Furthermore, the discrete state observer model can be used to construct the converter control model, and the construction of the discrete state observer model is conducive to achieving high-performance control of the converter control model.

[0082] For example, the controller may output control data to the converter to implement control of the converter.

[0083] The embodiment of the present application provides a control method for a converter. Through the power parameters of the filter and the parameter changes of the converter, a state observer for the power parameter changes can be constructed, and the converter control model can be obtained after the state observer is discretized. In this way, the state observer can be used to compensate for the disturbance of the converter, thereby achieving high suppression performance for external interference, internal coupling and parameter changes, thereby improving high-performance control of the converter and achieving high suppression performance.

[0084] In an exemplary embodiment, Figure 3 Schematic diagram of the process of determining the converter control model provided in this application Figure 2 ,like Figure 3 As shown, the method further includes S301 to S304, wherein:

[0085] S301, obtaining power parameters of the filter and parameter changes of the converter, and obtaining observer parameters corresponding to a pre-built state observer model based on the power parameters and the parameter changes.

[0086] The filter may be an LCL filter, a circuit device composed of an inductor and a capacitor, or a Figure 1 The filter (filter circuit part) shown in FIG. The power parameters of the filter can be parameters such as the capacitance, inductance, and current of the filter. The parameter change of the converter refers to the change in the output voltage, output current, and inductance of the converter.

[0087] Exemplarily, the controller can collect the power parameters of the filter and the power parameters of the converter, and determine the parameter changes of the converter. Further, the controller can obtain the observer parameters corresponding to the state observer model according to the pre-built state observer model, the power parameters and the parameter changes, and can construct a complete state observer model using the observer parameters.

[0088] For example, the controller may obtain a state space model based on the power parameters and the parameter changes, and the state space model may characterize the state changes of the converter.

[0089] S302: Obtain a state observer model for the converter according to observer parameters and a pre-built state observer model.

[0090] Exemplarily, the controller can parse and obtain observer parameters corresponding to a pre-built state observer model according to power parameters and parameter changes. The controller can obtain a constructed state observer model for compensating for state changes of the converter based on the observer parameters and the pre-built state observer model.

[0091] In practical applications, the grid-following converter with LCL filter can be transformed into the mathematical model in the dq coordinate system by applying Kirchhoff's law as follows:

[0092] (1);

[0093] (2);

[0094] (3);

[0095] Among them, L2 is the second grid-side inductor, C f is the converter output capacitor, L1 is the converter side inductor, is the output current of the grid-side inductor in the dq coordinate system, is the output capacitor voltage of the converter in the dq coordinate system, is the voltage of the common coupling point PCC in the dq coordinate system, is the grid voltage angular frequency, is the output current of the converter side inductor in the dq coordinate system, is the output voltage of the converter in the dq coordinate system.

[0096] Based on the parameter changes of the converter, combined with expressions (1) to (3), the output current dynamic expression (4) of the grid-side inductor in the dq coordinate system is obtained as follows:

[0097] (4);

[0098] in, is the output current of the grid-side inductor in the dq coordinate system The third-order time derivative of, b0 is the coefficient, b0=1 / L1L2C f , is the resonant frequency, where , is the total disturbance of the converter, is the output current of the grid-side inductor in the d coordinate system, is the output current of the grid-side inductor in the q coordinate system, is the voltage of the common coupling point PCC in the d coordinate system, is the voltage angular frequency of the transmission network, is the converter parameter change corresponding to L1, for The corresponding converter parameter changes, for The corresponding converter parameters change.

[0099] Alternatively, the total disturbance can be estimated by a state observer model And perform online compensation to reduce the total disturbance As an additional state of the LCL filter, the additional state is expressed as: Total disturbance To enhance the additional state of the LCL filter, the response state space model derived from expression (4) is as follows: expression (5) and expression (6):

[0100] (5);

[0101] (6);

[0102] in, is the state variable of x, ; A is the state matrix, B is the output matrix, E is the disturbance matrix, and h represents the total disturbance The time inverse of , y is the output state, and C is the output matrix.

[0103] Optionally, the pre-built state observer model can be expressed as follows (7):

[0104] (7)

[0105] in, is the derivative of z, z is the variable of the state observer model, which is the estimated value of the state variable x, L c is the gain vector of the state observer model, that is, the observer parameter corresponding to the state observer model, where .

[0106] In practical applications, the above expressions (5) and (7) can be used to analyze L c , we can further use L c The state observer model is constructed.

[0107] S303, obtaining current data and voltage data for the transmission network, and using a state observer model to process the current data and voltage data to obtain a discrete state observer model.

[0108] The current data of the transmission network may be the output current of the grid-side inductor of the converter, and the voltage data may be the output voltage of the converter.

[0109] Exemplarily, the controller can collect current data and voltage data of the transmission network, and can discretize the state observer model by processing the current data and voltage data using the state observer model to obtain a discrete state observer model. Further, the discrete state observer model can be used to construct a converter control model, and the construction of the discrete state observer model is conducive to realizing high-performance control of the converter control model.

[0110] S304, constructing a converter control model based on a discrete state observer model.

[0111] The converter control model may be a zero-order hold discrete time model.

[0112] Exemplarily, the controller can construct a converter control model based on a discrete state observer model and a state space current controller. For example, the control structure of the converter control model can include a discrete state observer model and a state space current controller. Through the converter control model constructed as above, high-performance control of the converter can be achieved, thereby improving the accuracy of controlling the converter and improving the control performance of the converter.

[0113] In this embodiment, a state observer for power parameter changes can be constructed through the power parameters of the filter and the parameter changes of the converter. In this way, the state observer can be used to compensate for the disturbance of the converter to achieve high suppression performance for external interference, internal coupling and parameter changes. In addition, this embodiment discretizes the constructed state observer model to obtain a discrete state observer model. The discretized state observer can better realize the construction of the converter control model, thereby improving the high-performance control of the converter and achieving high suppression performance.

[0114] In an exemplary embodiment, Figure 4 Schematic diagram of the process of determining the converter control model provided in this application Figure 3 ,like Figure 4 As shown, in this embodiment Figure 2 Based on the embodiment, step S303 is described in detail. In step S303, the state observer model is used to process the current data and the voltage data to obtain a discrete state observer, including:

[0115] S401, using the state observer model, processing the current data and the voltage data to obtain the state observer model matrix.

[0116] The state observer model matrix may be a parameter matrix used to construct a discrete state observer model.

[0117] Exemplarily, the controller can discretize the state observer model matrix by utilizing the state observer model to process the current data and the voltage data, and obtain the state observer model matrix corresponding to the state observer model. Furthermore, the state observer model matrix can be utilized to discretize the state observer model.

[0118] S402, obtaining a discrete state observer model based on the state observer model matrix.

[0119] Exemplarily, the controller may use the state observer model matrix to discretize the state observer model to construct a discrete state observer model.

[0120] In practical applications, the discrete state observer model can be expressed as follows (8):

[0121] (8)

[0122] in, is the observer state estimate at time k+1, is the state observer model matrix, is the current estimated value of the observer at time k, that is, the current observer. is the reference value of the converter output voltage in the dq coordinate system at time k, The input matrix for x.

[0123] Alternatively, the current observer can be obtained by the following expression (9):

[0124] (9)

[0125] in, is the observer state estimate at time k, is the gain matrix parameter of the discrete state observer model, Among them, L d According to the above Get, or .

[0126] In this embodiment, a discrete state observer model can be constructed through the above-mentioned state observer model matrix, which is conducive to the construction of a converter control model to improve the high control performance of the converter control and improve the effectiveness of the converter control.

[0127] Optionally, in step S402, after obtaining the discrete state observer model based on the state observer model matrix, the method further includes:

[0128] S403, obtaining the pole parameters of the discrete state observer model according to the sampling frequency corresponding to the state observer model and the state estimation parameters of the state observer model.

[0129] S404, obtaining the stability of the discrete state observer model according to the pole parameters of the discrete state observer model.

[0130] The sampling frequency refers to the sampling frequency of the state observer, and the state estimation parameter refers to the parameter value corresponding to the state estimation of the observer. The pole parameter can be a pole representation of the discrete state observer model.

[0131] Exemplarily, the controller may obtain a sampling frequency corresponding to the state observer model and a state estimate of the state observer model, and may determine the pole parameters of the discrete state observer model based on the sampling frequency corresponding to the state observer model and the state estimate parameters of the state observer model. Further, the stability of the discrete state observer model may be analyzed based on the pole parameters of the discrete state observer model.

[0132] In practical applications, the pole representation of the discrete state observer model is as shown in expression (10):

[0133] (10)

[0134] in, is the pole of the discrete state observer model, z is the state estimate of the observer model, that is, the state estimation parameter, is the expected bandwidth of the state observer model, is the sampling frequency of the state observer model.

[0135] In this embodiment, the poles of the discrete state observer model can be obtained through sampling frequency and state estimation, which is beneficial to analyzing the stability of the discrete state observer model through poles, and can achieve parameter adjustment of the discrete state observer through stability analysis, thereby improving the stability of the converter control model, which is beneficial to improving high-performance control of the converter.

[0136] In one possible implementation, Figure 5 As shown, a schematic diagram of a discrete state observer model provided in an embodiment of the present application is shown; wherein, is the output current of the grid-side inductor at time k The state variables, for and The difference between them can be obtained by the parameter L of the state observer model of e(k). d , and then the discrete state observer model can be obtained through expressions (8) and (9).

[0137] In practical applications, such as Figure 6 As shown, the embodiment of the present application provides a schematic diagram of the effect of parameter changes on the stability of the control model based on the Bode diagram, which can be obtained by Figure 6 Analyze the stability of discrete state observer models.

[0138] In an exemplary embodiment, Figure 7 Schematic diagram of the process of determining the converter control model provided in this application Figure 4 ,like Figure 7 As shown, in this embodiment Figure 3 Based on the embodiment, step S304 is described in detail. In step S304, a converter control model is constructed based on a discrete state observer model, including:

[0139] S701, constructing a state space current controller according to the current data of the filter.

[0140] S702, obtaining a converter control model based on a state-space current controller and a discrete state observer model.

[0141] The current data of the LCL filter may be the output current of the grid-side inductor.

[0142] Exemplarily, the controller can construct a state-space current controller for implementing current control based on the current data of the LCL filter. Further, the controller can complete the construction of the converter control model based on the state-space current controller and the discrete state observer model. In other words, the control structure of the converter control model can mainly include two parts: the state-space current controller and the discrete state observer model.

[0143] In practical applications, the state-space current controller can be expressed as follows (11):

[0144] (11);

[0145] in, is the output voltage of the converter in the dq coordinate system at time k, are the state feedback gain, is the state feedback gain at time k The state variables, is the state feedback gain at time k The state variables, is the reference value of the output current of the grid-side inductor in the dq coordinate system at time k, is the total disturbance at time K state variables.

[0146] Optionally, the converter control model can be expressed as follows:

[0147] (12);

[0148] (13);

[0149] Among them, x(k+1) is the state variable of x at time k+1, x(k) is the state variable of x at time k, is the input matrix of x, is the state observer model matrix, is the reference value of the converter output voltage in the dq coordinate system at time k, is the perturbation matrix of x, is the disturbance at time k, is the output current of the grid-side inductor in the dq coordinate system at time k, is the output matrix of x.

[0150] In this embodiment, a converter control model can be obtained through the above-mentioned discrete state observer model and state-space current controller. The converter control model can be a zero-order hold discrete time model, which can achieve equivalent control of the converter and is conducive to achieving high-performance control of the converter.

[0151] Optionally, in step S702, after constructing the state space current controller according to the current data of the LCL filter, the method further includes:

[0152] S703, obtaining a sampling frequency corresponding to the state observer model.

[0153] S704, obtaining discrete pole parameters of the state-space current controller according to the sampling frequency.

[0154] S705, obtaining the stability of the state-space current controller based on the discrete pole parameters.

[0155] The discrete pole parameters may be pole representations of a state-space current controller.

[0156] Exemplarily, the controller can obtain the sampling frequency corresponding to the state observer model, and based on the sampling frequency can determine the discrete pole representation of the state-space current controller, and further can analyze the stability of the state-space current controller according to the discrete pole parameters of the state-space current controller.

[0157] In practical applications, the discrete poles of the state-space current controller are expressed as Expression (14) and Expression (15):

[0158] (14);

[0159] (15);

[0160] in, are the discrete poles of the first state-space current controller, are the discrete poles of the second and third state-space current controllers, is the expected bandwidth of the state observer model, T s is the sampling frequency of the state observer model, is the grid voltage angular frequency, is the damping ratio, , is the natural frequency of the resonant pole.

[0161] In this embodiment, the discrete poles of the state-space current controller can be obtained through the sampling frequency, which is beneficial to analyzing the stability of the state-space current controller through poles. Through the design of the current controller with direct pole arrangement, high suppression performance against external interference, internal coupling and parameter changes can be achieved. The parameters of the state-space current controller can be adjusted through stability analysis, thereby improving the stability of the converter control model and facilitating improving high-performance control of the converter.

[0162] In an exemplary embodiment, Figure 8 Schematic diagram of the process of determining the converter control model provided in this application Figure 4 ,like Figure 8 As shown, in this embodiment Figure 3 Based on the embodiment, the step S301 is described in detail. In the step S301, based on the power parameters and the parameter changes, the observer parameters corresponding to the pre-built state observer model are obtained, which may include:

[0163] S801, based on the power parameters and the parameter changes, obtain a state space model that represents the state change of the converter;

[0164] S802, obtaining observer parameters according to the state space model and the pre-built state observer model.

[0165] The state space model may be a model that characterizes parameter changes of the converter.

[0166] Exemplarily, the controller can establish a state space model that characterizes the parameter changes of the converter according to the power parameters and the parameter changes. For example, the state expression of the LCL filter can be transformed into a mathematical model in the dq coordinate system by applying Kirchhoff's law, and the state space model can be further established through the mathematical model.

[0167] In practical applications, the state space model can be obtained through the above expressions (1) to (6). Furthermore, based on the state observer model represented by expression (5) and the above expression (7), the observer parameters of the state observer model can be obtained to realize the construction of the state observer model.

[0168] In this embodiment, a state space model is obtained through power parameters and parameter changes, and observer parameters can be obtained based on the state space model and a pre-built state observer model, which is conducive to building a state observer model, thereby improving the control performance of the converter.

[0169] Optionally, in step S802, obtaining observer parameters according to the state space model and the pre-built state observer model may specifically include:

[0170] Get the error model between the state-space model and the pre-built state observer model.

[0171] According to the error model, the error state matrix corresponding to the error model is obtained.

[0172] Based on the error state matrix, the observer parameters are obtained.

[0173] The error equation may be a model established by the error between the state space model and a pre-built state observer model.

[0174] Exemplarily, the controller may use the state space model to subtract the pre-built state observer model to obtain the error between the state space model and the pre-built state observer model, and may establish a corresponding error model based on the error. The controller may determine the error state matrix corresponding to the error model based on the error model, and may parse the error state matrix to obtain the observer parameters corresponding to the state observer model, and then may use the observer parameters to construct the state observer model.

[0175] In practical applications, the error model can be expressed as follows (16):

[0176] (16);

[0177] in, is the derivative of the difference e, is the state matrix of the difference e, where e is the error (difference) between the state-space model and the pre-built state observer model.

[0178] Where, e=xz;

[0179] Alternatively, according to expression (15), The roots of the characteristic polynomial are all in the left half plane, and the state observer model is stable. Therefore, the gain parameter of the state observer model is as follows (17):

[0180] (17);

[0181] in, is the intermediate variable, is the first extended state observer gain parameter, is the second extended state observer gain parameter, is the third extended state observer gain parameter, is the fourth extended state observer gain parameter, is the initial bandwidth of the state observer model.

[0182] In this embodiment, the error state matrix corresponding to the error model is obtained through the error model between the state space model and the pre-constructed state observer model, and the observer parameters can be obtained based on the error state matrix, which is conducive to accurately and effectively obtaining the observer parameters used to construct the state observer model, and is conducive to improving the control performance of the converter.

[0183] Optionally, in step S802, after obtaining a state observer model for the converter according to the observer parameters and the pre-built state observer model, the method further includes:

[0184] S803, obtaining a transfer function model corresponding to the state observer model;

[0185] S804, using the transfer function model, processing the initial output voltage of the converter to obtain a stable state of the state observer model.

[0186] Among them, the transfer function model can characterize the transfer function.

[0187] For example, the controller may convert the above expression (7) into a transfer function form, and the transfer function model may be the following expression (18):

[0188] (18)

[0189] in, is the transfer function of the state observer model (transfer function model), is the transfer function drop, is the initial output voltage of the converter in the dq coordinate system, s is the pull operator, is the transfer function from disturbance to input, is the transfer function from disturbance to output.

[0190] Within the bandwidth of the state observer model, the transfer function of the state observer model is expressed as follows (19):

[0191] (19);

[0192] At high frequencies beyond the observer frequency, the transfer function of the modified state observer model is expressed as follows (20):

[0193] (20);

[0194] in, is the initial bandwidth of the state observer model, and ω is the bandwidth of the state observer model.

[0195] Optionally, expression (19) shows that the transfer function of the state observer model has no total interference within the observer's bandwidth, expression (20) shows that at the high frequency of the state observer model, the modified extended state observer transfer function will return to the original grid-connected converter, and the transition from the low-frequency grid-connected converter to the high-frequency grid-connected converter is obtained by expression (18).

[0196] In practical applications, such as Fig. 9 As shown, a schematic diagram of a state observer model provided in an embodiment of the present application can be obtained by Fig. 9 The state observer model shown realizes the state observation of the converter. Fig. 9 The parameters in can be explained as above.

[0197] Alternatively, one can Fig.10 The root locus diagram provided in the embodiment of the present application is shown to implement frequency domain analysis of the state observer model and understand parameter adjustment of the state observer model to compensate for interference.

[0198] In this embodiment, the initial output voltage of the converter can be processed through the above transfer function model, and the stable state of the state observer model can be analyzed, thereby improving the stability of the state observer model, which is beneficial to high-performance control of the converter.

[0199] In an exemplary embodiment, Fig.11 Schematic diagram of the process of the converter control method provided in this application Figure 5 , the method comprising:

[0200] S1101, establish a mathematical model of the LCL filter and a mathematical model of the state observer.

[0201] S1102, construct a state observer model.

[0202] S1103, discretize the state observer model.

[0203] S1104, analyze the stability of the designed state observer model.

[0204] Understandably, Fig.10 Each step in the above-mentioned embodiments can be implemented by the combination of the above-mentioned embodiments or multiple embodiments, and the corresponding implementation method can be obtained from the above-mentioned embodiments, which will not be repeated here.

[0205] Optionally, Fig.12 A logic diagram of the control method of the converter provided in this application, such as Fig.12 As shown, the method can be applied to a converter having an LCL filter, the converter being used to convert the electric energy of a transmission network, wherein: Fig.12 The current state control in can be realized by the state space current controller of expression (11), Fig.12 The extended state observer in can be realized by the discrete state observer model of expression (8), Fig.12 The various parameters in can refer to the above parameter explanations and will not be repeated here.

[0206] In this embodiment, high suppression performance against external interference, internal coupling and parameter changes can be achieved through the construction of a state observer model and the design of a current controller with direct pole arrangement in the discrete time domain; and through the frequency domain analysis of the state observer model, the principle of interference compensation by the state observer model can be deeply understood; a discrete state observer model for the LCL filter is proposed, and the parameter adjustment and stability of the discrete state observer model are discussed, thereby improving the stability of the state observer model in high-order systems.

[0207] Fig.13 The schematic diagram of the structure of the converter control device provided in this application is as follows: Fig.13 As shown, the converter control model determination device 130 provided in this embodiment is applied to a converter having an LCL filter, and the converter is used to convert the electric energy of a transmission network; the device includes:

[0208] The power data acquisition module 1301 is used to acquire power data of the converter.

[0209] The pulse data acquisition module 1302 is used to process the power data using a pre-built converter control model to obtain converter control data; wherein the converter control model is obtained by discretizing a state observer model constructed by the power parameters of the LCL filter and the parameter changes of the converter.

[0210] The control module 1303 is used to control the operating state of the converter according to the control data.

[0211] In an exemplary embodiment, the apparatus further comprises:

[0212] A parameter acquisition module is used to acquire power parameters of the LCL filter and parameter changes of the converter, and based on the power parameters and parameter changes, acquire observer parameters corresponding to the pre-built state observer model;

[0213] An observer acquisition module, used for obtaining a state observer model for the converter according to observer parameters and a pre-built state observer model;

[0214] The discrete observer acquisition module is also used to acquire current data and voltage data for the transmission network, and use the state observer model to process the current data and voltage data to obtain a discrete state observer model;

[0215] The control model building module is used to build a converter control model based on a discrete state observer model.

[0216] In an exemplary embodiment, the discrete observer acquisition module is used to process the current data and the voltage data using the state observer model to obtain the state observer model matrix; and obtain the discrete state observer model based on the state observer model matrix.

[0217] In an exemplary embodiment, the discrete observer acquisition module is also used to obtain the pole parameters of the discrete state observer model according to the sampling frequency corresponding to the state observer model and the state estimation parameters of the state observer model; and obtain the stability of the discrete state observer model according to the pole parameters of the discrete state observer model.

[0218] In an exemplary embodiment, the control model building module is used to build a state-space current controller according to the current data of the LCL filter; and obtain a converter control model based on the state-space current controller and the discrete state observer model.

[0219] In an exemplary embodiment, the control model building module is also used to obtain the sampling frequency corresponding to the state observer model; obtain the discrete pole parameters of the state space current controller according to the sampling frequency; and obtain the stability of the state space current controller based on the discrete pole parameters.

[0220] In an exemplary embodiment, the parameter acquisition module is used to obtain a state space model characterizing the state change of the converter based on the power parameters and the parameter change; and obtain observer parameters according to the state space model and a pre-built state observer model.

[0221] In an exemplary embodiment, the parameter acquisition module is used to acquire an error model between a state space model and a pre-built state observer model; obtain an error state matrix corresponding to the error model according to the error model; and obtain observer parameters based on the error state matrix.

[0222] In an exemplary embodiment, the observer acquisition module is further used to acquire a transfer function model corresponding to the state observer model; and use the transfer function model to process the initial output voltage of the converter to obtain a stable state of the state observer model.

[0223] In an exemplary embodiment, this embodiment further provides a control device for a converter, the device comprising:

[0224] The control model acquisition module is used to obtain the converter control model according to the above converter control model determination method.

[0225] The control data acquisition module is used to obtain the control data of the converter according to the converter control model and the power data of the converter.

[0226] The converter control model determination device and converter control device provided in this embodiment can execute the method provided in the above method embodiment. The implementation principle and technical effect are similar, and will not be described in detail in this embodiment.

[0227] Fig.14 This is a schematic diagram of the structure of the controller provided in this application. Fig.14 As shown, the electronic device 140 provided in this embodiment includes: at least one processor 1401 and a memory 1402. Optionally, the device 140 also includes a communication component 1403. The processor 1401, the memory 1402 and the communication component 1403 are connected via a bus 1404.

[0228] In a specific implementation process, at least one processor 1401 executes the computer-executable instructions stored in the memory 1402, so that at least one processor 1401 executes the above method.

[0229] The specific implementation process of the processor 1401 can be found in the above method embodiment, and its implementation principle and technical effect are similar, so this embodiment will not be repeated here.

[0230] In the above embodiments, it should be understood that the processor can be a central processing unit (CPU), or other general-purpose processors, digital signal processors (DSP), application-specific integrated circuits (ASIC), etc. A general-purpose processor can be a microprocessor or any conventional processor. The steps of the method disclosed in the invention can be directly implemented as a hardware processor, or can be implemented by a combination of hardware and software modules in the processor.

[0231] The memory may include a high-speed memory (Random Access Memory, RAM), and may also include a non-volatile memory (NVM), such as at least one disk storage.

[0232] The bus can be an Industry Standard Architecture (ISA) bus, a Peripheral Component Interconnect (PCI) bus, or an Extended Industry Standard Architecture (EISA) bus, etc. The bus can be divided into an address bus, a data bus, a control bus, etc. For ease of representation, the bus in the drawings of this application is not limited to only one bus or one type of bus.

[0233] The present application also provides a power grid power conversion system, the system comprising:

[0234] A converter for supplying power to a load;

[0235] LCL filter, connected to the converter, and also used to connect to the transmission grid;

[0236] The controller as mentioned above is respectively connected to the converter and the LCL filter, and is also used to connect to the transmission network.

[0237] The present application also provides a computer program product, including a computer program, which implements the above method when executed by a processor.

[0238] The present application also provides a computer-readable storage medium, in which computer-executable instructions are stored. When a processor executes the computer-executable instructions, the above method is implemented.

[0239] The above-mentioned readable storage medium can be implemented by any type of volatile or non-volatile storage device or a combination thereof, such as static random access memory (SRAM), electrically erasable programmable read-only memory (EEPROM), erasable programmable read-only memory (EPROM), programmable read-only memory (PROM), read-only memory (ROM), magnetic memory, flash memory, magnetic disk or optical disk. The readable storage medium can be any available medium that can be accessed by a general or special-purpose computer.

[0240] An exemplary readable storage medium is coupled to a processor so that the processor can read information from the readable storage medium and write information to the readable storage medium. Of course, the readable storage medium can also be a component of the processor. The processor and the readable storage medium can be located in an application specific integrated circuit (Application Specific Integrated Circuits, referred to as: ASIC). Of course, the processor and the readable storage medium can also exist in the device as discrete components.

[0241] The division of units is only a logical function division, and there may be other divisions in actual implementation, such as multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be an indirect coupling or communication connection through some interface, device or unit, which can be electrical, mechanical or other forms.

[0242] The units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed on multiple network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0243] In addition, each functional unit in each embodiment of the present invention may be integrated into one processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit.

[0244] If the function is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, or the part that contributes to the prior art, or the part of the technical solution, can be embodied in the form of a software product. The computer software product is stored in a storage medium, including several instructions for a computer device (which can be a personal computer, server, or network device, etc.) to perform all or part of the steps of the methods of each embodiment of the present invention. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (ROM, Read-Only Memory), random access memory (RAM, Random Access Memory), disk or optical disk, etc. Various media that can store program codes.

[0245] Those skilled in the art can understand that all or part of the steps of implementing the above-mentioned method embodiments can be completed by hardware related to program instructions. The aforementioned program can be stored in a computer-readable storage medium. When the program is executed, the steps of the above-mentioned method embodiments are executed; and the aforementioned storage medium includes: ROM, RAM, disk or optical disk and other media that can store program codes.

[0246] Finally, it should be noted that those skilled in the art will readily conceive of other embodiments of the present invention after considering the specification and practicing the invention disclosed herein. The present invention is intended to cover any variations, uses or adaptations of the present invention, which follow the general principles of the present invention and include common knowledge or customary technical means in the art not disclosed by the present invention, are not limited to the precise structure described above and shown in the drawings, and may be modified and changed in various ways without departing from the scope thereof. The scope of the present invention is limited only by the appended claims.

Claims

1. A method for controlling a converter, characterized in that: Applied to a converter, the converter is used to convert electric energy of a transmission network; the method comprises: Acquiring power data of the converter; Processing the power data using a pre-built converter control model to obtain control data of the converter, wherein the control data is used to control the operating state of the converter; The method further comprises: Acquire power parameters of the filter and parameter changes of the converter, and obtain a state space model characterizing the state change of the converter based on the power parameters and the parameter changes; Obtaining an error model between the state space model and a pre-built state observer model; According to the error model, an error state matrix corresponding to the error model is obtained; Based on the error state matrix, obtaining observer parameters corresponding to the pre-constructed state observer; Obtaining a state observer model for the converter according to the observer parameters and the pre-built state observer model; Acquiring current data and voltage data of the transmission network, and using the state observer model to process the current data and voltage data to obtain a discrete state observer model; Based on the discrete state observer model, the converter control model is constructed.

2. The method according to claim 1, characterized in that The method of using the state observer model to process the current data and the voltage data to obtain a discrete state observer model includes: Using the state observer model, processing the current data and the voltage data to obtain a state observer model matrix; Based on the state observer model matrix, a discrete state observer model is obtained.

3. The method according to claim 2, characterized in that After obtaining the discrete state observer model based on the state observer model matrix, the method further comprises: Obtaining the pole parameters of the discrete state observer model according to the sampling frequency corresponding to the state observer model and the state estimation parameters of the state observer model; The degree of stability of the discrete state observer model is obtained according to the pole parameters of the discrete state observer model.

4. The method according to claim 1, characterized in that: The step of constructing the converter control model based on the discrete state observer model includes: constructing a state-space current controller according to the current data of the filter; Based on the state-space current controller and the discrete state observer model, the converter control model is obtained.

5. The method according to claim 4, characterized in that After constructing the state-space current controller according to the current data of the filter, the method further includes: Obtaining a sampling frequency corresponding to the state observer model; According to the sampling frequency, obtaining discrete pole parameters of the state-space current controller; Based on the discrete pole parameters, the stability of the state-space current controller is obtained.

6. The method according to any one of claims 1 to 5, characterized in that: After obtaining the state observer model for the converter according to the observer parameters and the pre-built state observer model, the method further includes: Obtaining a transfer function model corresponding to the state observer model; The initial output voltage of the converter is processed by using the transfer function model to obtain a stable state of the state observer model.

7. A controller, characterized in that: include: Memory, processor; The memory stores computer-executable instructions; The processor executes the computer-executable instructions stored in the memory, so that the processor performs the method according to any one of claims 1 to 6.

8. A power grid power conversion system, characterized in that: The system comprises: A converter for supplying power to a load; A filter, connected to the converter and also used to connect to a transmission network; The controller as claimed in claim 7 is connected to the converter and the filter respectively, and is also used to connect to a transmission network.

9. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores computer-executable instructions, which are used to implement the method according to any one of claims 1 to 6 when executed by a processor.

10. A computer program product, characterized in that The invention comprises a computer program, which implements the method according to any one of claims 1 to 6 when being executed by a processor.

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