Voltage control method and system of dynamic voltage restorer and electronic equipment

Abstract

The invention relates to a dynamic voltage restorer voltage control method and system and electronic equipment, is applied to a three-phase four-bridge-arm dynamic voltage restorer, and comprises the following steps: acquiring a compensation voltage reference value and a compensation voltage predicted value of the three-phase four-bridge-arm dynamic voltage restorer under a preset number of switch configuration schemes, the compensation voltage reference value comprises a positive sequence voltage reference value, a negative sequence voltage reference value and a zero sequence voltage reference value, and the compensation voltage prediction value comprises a positive sequence voltage prediction value, a negative sequence voltage prediction value and a zero sequence voltage prediction value; calculating according to a preset cost function to obtain a cost value corresponding to each switch configuration scheme; and controlling the switch assembly according to the optimal switch configuration scheme with the minimum cost value, so that the three-phase four-leg dynamic voltage restorer outputs the target compensation voltage. On-off control is realized by combining positive-sequence, negative-sequence and zero-sequence three-sequence compensation voltage, and the output precision of the compensation voltage of the dynamic voltage restorer under the asymmetric working condition is greatly improved.

Description

Technical Field

[0001] The present application relates to the field of integrated circuit technology, and in particular to a voltage control method, system and electronic equipment for a dynamic voltage restorer. Background Art

[0002] The main causes of voltage sag can be divided into three categories: natural factors, power system reasons and accidental events. Natural factors include lightning strikes and lightning, which can cause the protection device to malfunction and cause voltage sag. Common causes in the power system include short circuit faults, line switching and the start and stop of high-power motors, which can cause large current fluctuations in the power grid and cause voltage sags. Severe short circuit faults can also cause voltage sags between two adjacent branches in the power grid. Accidental events include power transmission lines damaged by animals and staff operating errors. As can be seen from the above, voltage sags are inevitable, and how to solve voltage sags is an issue that cannot be ignored.

[0003] In most of the current research on three-phase four-leg inverters, three-dimensional space vector modulation (3D-SVPWM) in the abc coordinate system is used in combination with dual closed-loop control to achieve output control. However, 3D-SVPWM involves the selection of space voltage vectors and the need to calculate the time for each space vector to act, which is relatively cumbersome. When an asymmetric voltage sag occurs, the zero-sequence component that the dynamic voltage restorer (DVR) needs to compensate is difficult to accurately represent in 3D-SVPWM, and the parameter adjustment link of the dual closed-loop control scheme takes a lot of time, and the corresponding compensation voltage cannot be generated in time. Summary of the invention

[0004] Based on this, it is necessary to provide a dynamic voltage restorer voltage control method, system and electronic equipment that can be applied to asymmetric working conditions in order to solve the above technical problems.

[0005] In a first aspect, the present application provides a voltage control method for a dynamic voltage restorer, which is applied to a three-phase four-bridge-arm dynamic voltage restorer, wherein each bridge arm of the three-phase four-bridge-arm dynamic voltage restorer includes a switch assembly consisting of at least two switch tubes, including:

[0006] Obtaining compensation voltage reference values ​​and compensation voltage prediction values ​​of the three-phase four-bridge arm dynamic voltage restorer under a preset number of switch configuration schemes, wherein the compensation voltage reference values ​​include positive-sequence voltage reference values, negative-sequence voltage reference values, and zero-sequence voltage reference values, and the compensation voltage prediction values ​​include positive-sequence voltage prediction values, negative-sequence voltage prediction values, and zero-sequence voltage prediction values;

[0007] According to the preset cost function, the compensation voltage reference value and the compensation voltage prediction value, respectively calculate the cost value corresponding to each switch configuration scheme, and determine the optimal switch configuration scheme from the switch configuration scheme corresponding to the minimum cost value;

[0008] The switch component is controlled according to the optimal switch configuration scheme so that the three-phase four-bridge arm dynamic voltage restorer outputs a target compensation voltage.

[0009] In one embodiment, the step of obtaining the compensation voltage reference value and the compensation voltage prediction value of the three-phase four-bridge arm dynamic voltage restorer under a preset number of switch configuration schemes includes:

[0010] Obtaining positive-sequence components, negative-sequence components, and zero-sequence components of circuit parameters of the three-phase four-bridge-arm dynamic voltage restorer under different switch configuration schemes, wherein the circuit parameters include output voltage, inductor voltage, and output current;

[0011] Processing the positive sequence component, negative sequence component and zero sequence component of the circuit parameter according to the vector angle compensation method, and calculating the compensation voltage reference value;

[0012] The positive sequence component, negative sequence component and zero sequence component of the circuit parameter are processed according to a preset voltage prediction model algorithm to obtain the compensation voltage prediction value.

[0013] In one embodiment, the obtaining of positive sequence components, negative sequence components and zero sequence components of circuit parameters of the three-phase four-bridge arm dynamic voltage restorer under different switch configuration schemes includes:

[0014] Collecting three-phase stationary coordinate system parameters of the three-phase four-bridge arm dynamic voltage restorer under different switch configuration schemes;

[0015] Performing Clarke transformation on the three-phase stationary coordinate system parameters to obtain two-phase stationary coordinate system parameters;

[0016] Two second-order generalized integrators are used to perform positive-negative sequence decoupling on the two-phase stationary coordinate system parameters to obtain the positive-sequence component, negative-sequence component and zero-sequence component of the circuit parameters.

[0017] In one embodiment, the processing of the positive sequence component, the negative sequence component and the zero sequence component of the circuit parameter according to the vector angle compensation method to calculate the compensation voltage reference value includes:

[0018] Processing the positive-sequence component and the negative-sequence component of the compensation voltage according to the vector angle compensation method, and calculating the positive-sequence voltage reference value and the negative-sequence voltage reference value;

[0019] The zero-sequence component of the compensation voltage is processed according to the vector angle compensation method, and the zero-sequence voltage reference value is calculated.

[0020] In one embodiment, the processing of the positive sequence component, the negative sequence component and the zero sequence component of the circuit parameter according to a preset voltage prediction model algorithm to obtain the compensation voltage prediction value includes:

[0021] Acquire an output voltage prediction model according to the topological structure of the three-phase four-bridge-arm dynamic voltage restorer;

[0022] Processing the voltage prediction model according to the zero-order hold method to obtain a discrete model of the three-phase four-bridge arm dynamic voltage restorer;

[0023] The compensation voltage prediction value is calculated by combining the discrete model of the three-phase four-bridge arm dynamic voltage restorer and the positive sequence component, negative sequence component and zero sequence component of the circuit parameters under the corresponding switch configuration scheme.

[0024] In one embodiment, the cost values ​​corresponding to each switch configuration scheme are calculated based on the preset cost function, the compensation voltage reference value, and the compensation voltage prediction value, respectively, including:

[0025] The cost value is obtained by calculating the sum of squares of differences between the compensation voltage reference value and the compensation voltage prediction value.

[0026] In a second aspect, the present application further provides a dynamic voltage restorer voltage control system, which is applied to a three-phase four-bridge-arm dynamic voltage restorer, wherein each bridge arm of the three-phase four-bridge-arm dynamic voltage restorer includes a switch assembly consisting of at least two switch tubes, including:

[0027] An acquisition module, used to acquire a compensation voltage reference value and a compensation voltage prediction value of the three-phase four-bridge arm dynamic voltage restorer under a preset number of switch configuration schemes, wherein the compensation voltage reference value includes a positive-sequence voltage reference value, a negative-sequence voltage reference value, and a zero-sequence voltage reference value, and the compensation voltage prediction value includes a positive-sequence voltage prediction value, a negative-sequence voltage prediction value, and a zero-sequence voltage prediction value;

[0028] A calculation module, configured to calculate the cost values ​​corresponding to each switch configuration scheme according to a preset cost function, the compensation voltage reference value and the compensation voltage prediction value, and determine the optimal switch configuration scheme from the switch configuration scheme corresponding to the minimum cost value;

[0029] A control module is used to control the switch component according to the optimal switch configuration scheme so that the three-phase four-bridge arm dynamic voltage restorer outputs a target compensation voltage.

[0030] In one embodiment, the calculation module is specifically used for the calculation module, specifically for obtaining the positive-sequence component, negative-sequence component and zero-sequence component of the circuit parameters of the three-phase four-bridge arm dynamic voltage restorer under different switch configuration schemes, wherein the circuit parameters include output voltage, inductor voltage and output current; processing the positive-sequence component, negative-sequence component and zero-sequence component of the circuit parameters according to the vector angle compensation method to calculate the compensation voltage reference value; processing the positive-sequence component, negative-sequence component and zero-sequence component of the circuit parameters according to a preset voltage prediction model algorithm to obtain the compensation voltage prediction value.

[0031] In one of the embodiments, the acquisition module is specifically used to collect the three-phase stationary coordinate system parameters of the three-phase four-bridge arm dynamic voltage restorer under different switch configuration schemes; perform Clarke transformation on the three-phase stationary coordinate system parameters to obtain two-phase stationary coordinate system parameters; use two second-order generalized integrators to perform positive and negative sequence decoupling on the two-phase stationary coordinate system parameters to obtain the positive sequence component, negative sequence component and zero sequence component of the circuit parameters.

[0032] In a third aspect, the present application further provides an electronic device, comprising the dynamic voltage restorer voltage control system described in the second aspect.

[0033] In a fourth aspect, the present application further provides a computer-readable storage medium having a computer program stored thereon, and when the computer program is executed by a processor, the steps of the dynamic voltage restorer voltage control method described in the first aspect are implemented.

[0034] In a fifth aspect, the present application further provides a computer program product, which includes a computer program, and when the computer program is executed by a processor, the steps of the dynamic voltage restorer voltage control method described in the first aspect are implemented.

[0035] In summary, the present application provides a voltage control method, system and electronic device for a dynamic voltage restorer, which is applied to a three-phase four-bridge arm dynamic voltage restorer, including: obtaining a compensation voltage reference value and a compensation voltage prediction value of the three-phase four-bridge arm dynamic voltage restorer under a preset number of switch configuration schemes, wherein the compensation voltage reference value includes a positive-sequence voltage reference value, a negative-sequence voltage reference value and a zero-sequence voltage reference value, and the compensation voltage prediction value includes a positive-sequence voltage prediction value, a negative-sequence voltage prediction value and a zero-sequence voltage prediction value; calculating the cost value corresponding to each switch configuration scheme according to a preset cost function; controlling the switch component according to the optimal switch configuration scheme with the minimum cost value, so that the three-phase four-bridge arm dynamic voltage restorer outputs the target compensation voltage. The present invention combines the positive-sequence, negative-sequence and zero-sequence three-sequence compensation voltages to realize switch control, which greatly improves the output accuracy of the compensation voltage of the dynamic voltage restorer under asymmetric working conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 A diagram showing an application environment of a voltage control method for a dynamic voltage restorer in one embodiment;

[0037] Figure 2 A schematic flow chart of a voltage control method for a dynamic voltage restorer in one embodiment;

[0038] Figure 3 is a schematic diagram of output voltage components under different switch configuration schemes in one embodiment;

[0039] Figure 4 It is a schematic diagram of the steps of performing positive and negative sequence decoupling of two-phase stationary coordinate system parameters in one embodiment;

[0040] Figure 5 A schematic diagram of a structure for performing positive and negative sequence decoupling of two-phase stationary coordinate system parameters in one embodiment;

[0041] Figure 6 A schematic diagram of a calculation framework for performing positive and negative sequence decoupling of two-phase stationary coordinate system parameters in one embodiment;

[0042] Figure 7 It is a schematic diagram of a calculation framework for performing positive and negative sequence decoupling on two-phase stationary coordinate system parameters in another embodiment;

[0043] Figure 8 It is a schematic diagram of vector distribution after positive and negative sequence decoupling of two-phase stationary coordinate system parameters in one embodiment;

[0044] Fig. 9 A block diagram of a voltage control system of a dynamic voltage restorer in one embodiment;

[0045] Fig.10 FIG. 4 is a diagram showing the internal structure of an electronic device in one embodiment. DETAILED DESCRIPTION

[0046] In order to make the purpose, technical solution and advantages of the present application more clearly understood, the present application is further described in detail below in conjunction with the accompanying drawings and embodiments. 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.

[0047] As described in the above background technology section, in the existing compensation control scheme for the voltage sag problem of the three-phase four-bridge-arm inverter, three-dimensional space vector modulation in the abc coordinate system is often used in combination with dual closed-loop control to achieve output control. When an asymmetric voltage sag occurs, the calculation of the compensation parameters of the DVR is difficult and time-consuming, and the grid or load may be abnormally damaged due to untimely compensation.

[0048] In one embodiment, Figure 1 As shown, a three-phase four-bridge-arm inverter is provided, including multiple dynamic voltage restorers (Dynamic Voltage Restorers, referred to as DVRs), a grid end, a load end, and an LC filter circuit. The three-phase four-bridge-arm inverter includes at least a-phase DVR, b-phase DVR, c-phase DVR, and n-phase DVR, and the n-phase DVR is connected in parallel at both ends of the a-phase DVR, the b-phase DVR, and the c-phase DVR.

[0049] In actual application, the three-phase four-bridge-arm inverter provides an additional N-phase bridge arm that can pass zero-sequence current compared to the three-phase three-bridge-arm inverter, forming an independent loop specifically used to adjust the neutral point potential. The three-phase four-bridge-arm inverter has demonstrated excellent performance in solving the problem of neutral point drift when the load is asymmetric with its unique working principle and advantages.

[0050] When the voltage at the grid end drops asymmetrically, the topological characteristics of the three-phase four-bridge arm can be used to effectively compensate for the drop voltage. In the compensation voltage control method, this embodiment provides a dynamic voltage restorer voltage control method, which can separate the compensation voltage into positive sequence voltage, negative sequence voltage and zero sequence voltage, and then combine the three sequence voltages with model predictive control, simplifying the control logic while improving the accuracy of the compensation voltage under asymmetric conditions.

[0051] In one embodiment, Figure 2 As shown, a dynamic voltage restorer voltage control method is provided, and the method is applied to Figure 1 The three-phase four-leg inverter in FIG. 1 is taken as an example to illustrate the invention, which includes the following steps:

[0052] S201, obtaining compensation voltage reference values ​​and compensation voltage prediction values ​​of a three-phase four-bridge arm dynamic voltage restorer under a preset number of switch configuration schemes, wherein the compensation voltage reference values ​​include positive-sequence voltage reference values, negative-sequence voltage reference values ​​and zero-sequence voltage reference values, and the compensation voltage prediction values ​​include positive-sequence voltage prediction values, negative-sequence voltage prediction values ​​and zero-sequence voltage prediction values.

[0053] In this embodiment, by obtaining the compensation voltage reference value and compensation voltage prediction value of each phase dynamic voltage restorer of the three-phase four-leg inverter under different switch configuration schemes, the model predictive control (MPC) method can be used to screen the optimal switch configuration scheme.

[0054] Specifically, the compensation voltage reference value and the compensation voltage prediction value in this embodiment are usually the compensation voltage reference value and the compensation voltage prediction value at a preset step distance from the current moment. The compensation voltage reference value and the compensation voltage prediction value are obtained by obtaining the circuit parameters of the dynamic voltage restorer at the current moment and performing corresponding calculations. For example, the output voltage reference value at the current moment is The reference value of compensation voltage is The predicted compensation voltage is .

[0055] In this embodiment, The compensation voltage reference value and compensation voltage prediction value are calculated in the coordinate system. The circuit parameters in coordinates are converted into The circuit parameters of the coordinate system can better represent the zero-sequence component that needs to be compensated by the dynamic voltage restorer (DVR), thereby facilitating the subsequent dual closed-loop parameter adjustment process.

[0056] S202, according to a preset cost function, a compensation voltage reference value and a compensation voltage prediction value, respectively calculate the cost value corresponding to each switch configuration scheme, and determine the switch configuration scheme corresponding to the minimum cost value as the optimal switch configuration scheme.

[0057] In this embodiment, the preset cost function can be used to calculate a cost value according to the compensation voltage reference value and the compensation voltage prediction value corresponding to different switch configuration schemes. By comparing the cost value, the advantages and disadvantages of each switch configuration scheme in the actual compensation process can be judged, thereby assisting in selecting the optimal switch configuration scheme with the best compensation effect.

[0058] It should be noted that in this embodiment, at the current moment, moment, and predict the future time period, such as +1 moment or The optimal switch configuration scheme at each moment can ensure that the system maintains the optimal switch configuration scheme from the current moment to the future time period. And the steps S201-S202 provided in this embodiment can be cyclically executed at each current moment to realize the rolling optimization of MPC.

[0059] In this embodiment, the preset time step of MPC can be adaptively configured according to the needs of the actual application scenario.

[0060] S203, controlling the switch assembly according to the optimal switch configuration scheme so that the three-phase four-bridge arm dynamic voltage restorer outputs a target compensation voltage.

[0061] In this embodiment, the switch assembly is controlled according to the optimal switch configuration scheme, so that the four-phase bridge arm dynamic voltage restorer can output the target compensation voltage at the current moment and the future moment, so as to achieve a rapid response to voltage changes. In this embodiment, the control signal of the switch tube can be obtained directly through MPC control, eliminating the PWM modulation link, and can respond to various working conditions of the power grid more quickly.

[0062] In one embodiment, obtaining a compensation voltage reference value and a compensation voltage prediction value of a three-phase four-bridge arm dynamic voltage restorer under a preset number of switch configuration schemes includes:

[0063] The positive-sequence component, negative-sequence component and zero-sequence component of the circuit parameters of the three-phase four-bridge arm dynamic voltage restorer under different switch configuration schemes are obtained, wherein the circuit parameters include output voltage, inductor voltage and output current.

[0064] The positive sequence component, negative sequence component and zero sequence component of the circuit parameters are processed according to the vector angle compensation method, and the compensation voltage reference value is calculated.

[0065] The positive sequence component, negative sequence component and zero sequence component of the circuit parameters are processed according to a preset voltage prediction model algorithm to obtain a compensation voltage prediction value.

[0066] In this embodiment, after obtaining the specific values ​​of the circuit parameters of the dynamic voltage restorer under different switch configuration schemes in the three-phase coordinate system, the circuit parameters in the three-phase coordinate system can be converted into Positive sequence component, negative sequence component and zero sequence component in the coordinate system. It should be noted that the circuit parameters can be determined according to the needs of the actual application scenario. The circuit parameters include output voltage, inductor voltage, load current and output current

[0067] In this embodiment, after obtaining the positive sequence component, negative sequence component and zero sequence component of the circuit parameter, each component can be processed by the vector angle compensation method to improve the accuracy of the compensation voltage reference value. Specifically, the vector angle compensation method compensates the vector angle of the signal based on the vector representation of the signal, and the vector representation means that the signal can be regarded as a vector with amplitude and angle. In digital signal processing, the signal may be affected by factors such as noise and distortion, resulting in changes in the vector angle of the signal. By measuring and calculating this change and compensating for it, the original state of the signal can be restored or its quality can be improved.

[0068] In this embodiment, the compensation voltage reference value can be directly calculated based on the components of the circuit parameters. When calculating the compensation voltage prediction value, it is necessary to combine the discrete state space model of the three-phase four-leg inverter for calculation.

[0069] In one embodiment, the positive sequence component, negative sequence component and zero sequence component of the circuit parameters are processed according to a preset voltage prediction model algorithm to obtain a compensation voltage prediction value, including: obtaining an output voltage prediction model according to the topological structure of the three-phase four-bridge arm dynamic voltage restorer. The voltage prediction model is processed according to the zero-order hold method to obtain a discrete model of the three-phase four-bridge arm dynamic voltage restorer. The compensation voltage prediction value is calculated by combining the discrete model of the three-phase four-bridge arm dynamic voltage restorer and the positive sequence component, negative sequence component and zero sequence component of the circuit parameters under the corresponding switch configuration scheme.

[0070] In this embodiment, the preset voltage prediction model algorithm includes:

[0071]

[0072] in, express The parameter prediction value at time is the discrete state space model of the three-phase four-leg inverter, In actual application, when obtaining the output voltage, inductor voltage and output current After the coordinate components of the coordinate system are obtained, the output voltage prediction model is obtained according to the topological structure of the three-phase four-bridge arm dynamic voltage restorer, and the relationship can be obtained:

[0073]

[0074] in, are the positive and negative sequence components of the output current, is the zero-sequence component of the output current, are the positive and negative sequence components of the output voltage, is the zero-sequence component of the output voltage, are the positive and negative sequence components of the inductor voltage, is the zero-sequence component of the inductor voltage, are the positive and negative sequence components of the load current, is the zero-sequence component of the load current. Simplifying the above formula, we can get ,in, is the predicted value for the next moment, The discrete state space model can be derived by applying the zero-order hold to the above formula: ,in, , , , , A and B are both matrices in the above relationship.

[0075] In actual application, the sampling frequency is much higher than the time constant of the inverter filter. Assuming that the load current In one control cycle, the inductor voltage is a constant. Depend on The switching vector selected at the moment determines, therefore, ,in, for The positive and negative sequence components of the inductor voltage under the optimal switch configuration scheme at the moment, for Zero-sequence component of inductor voltage under the optimal switch configuration scheme at the moment.

[0076] In one embodiment, if Figure 4 As shown, the positive sequence component, negative sequence component and zero sequence component of the circuit parameters of the three-phase four-bridge arm dynamic voltage restorer under different switch configuration schemes are obtained, including:

[0077] S401, collecting three-phase stationary coordinate system parameters of a three-phase four-bridge-arm dynamic voltage restorer under different switch configuration schemes.

[0078] S402, performing Clarke transformation on the three-phase stationary coordinate system parameters to obtain the two-phase stationary coordinate system parameters.

[0079] S403, using two second-order generalized integrators to perform positive-negative sequence decoupling on the two-phase stationary coordinate system parameters to obtain positive-sequence components, negative-sequence components and zero-sequence components of the circuit parameters.

[0080] In this embodiment, it is assumed that Sa, Sb, Sc, and Sn represent the switch states of branches a, b, c, and n, respectively. "1" indicates that the upper switch is in the on state and the lower switch is in the off state. "0" indicates that the upper switch is in the off state and the lower switch is in the on state. There are 16 possible switch configurations for a three-phase four-bridge-leg inverter. These 16 switch configurations are numbered in sequence. The output voltage of each phase branch of the three-phase four-bridge-leg inverter is obtained. Then, through Clark transformation, the DVR can be derived. The output voltage of the coordinate system.

[0081] like Figure 3 As shown, , and Indicates that branch n is The node voltage in the coordinate system, , and Indicates that branch n is The node voltage of the coordinate system, is the positive sequence node voltage component, is the negative sequence node voltage component, is the zero-sequence node voltage component.

[0082] Specifically, the specific implementation method of using two second-order generalized integrators to perform positive and negative sequence decoupling of the two-phase stationary coordinate system parameters is as follows: Figure 5 shown.

[0083] In a specific embodiment, Figure 6 , Figure 7 and Figure 8 As shown, the specific formula for positive and negative sequence decoupling of the two-phase stationary coordinate system parameters is:

[0084]

[0085]

[0086] The specific process of positive and negative sequence decoupling can be summarized as follows: using two second-order generalized integrators (SOGI) to process the parameters of Quantity and Quantity , and get the intermediate component , , and , and then use the above calculation formula to calculate the corresponding positive sequence component and , negative sequence component and .

[0087] In one embodiment, the positive sequence component, the negative sequence component and the zero sequence component of the circuit parameter are processed according to the vector angle compensation method to calculate the compensation voltage reference value, including:

[0088] The positive sequence component and the negative sequence component of the compensation voltage are processed according to the vector angle compensation method, and the positive sequence voltage reference value and the negative sequence voltage reference value are calculated;

[0089] The zero-sequence component of the compensation voltage is processed according to the vector angle compensation method, and the zero-sequence voltage reference value is calculated.

[0090] In actual application, according to the vector angle compensation method, the reference value of the compensation voltage generated by the DVR detection unit at time k is The specific process of compensation is as follows: After decoupling control, the positive sequence voltage vector expression is obtained as follows:

[0091]

[0092] At this time, the positive sequence voltage reference value of DVR compensation at time k+2 is:

[0093]

[0094] Similarly, the negative sequence voltage reference value of DVR compensation at time k+2 is:

[0095]

[0096] Combining the positive sequence voltage reference value and negative sequence voltage reference value of DVR compensation at time k+2, we can get:

[0097]

[0098] The reference value of zero-sequence voltage is:

[0099]

[0100] In one embodiment, according to a preset cost function, a compensation voltage reference value, and a compensation voltage prediction value, cost values ​​corresponding to each switch configuration scheme are calculated respectively, including:

[0101] The sum of squares of the differences between the compensation voltage reference value and the compensation voltage prediction value is calculated to obtain a cost value.

[0102] In a specific embodiment, the preset cost function may be:

[0103]

[0104] in, for The positive sequence component of the compensation voltage reference value at time, for The negative sequence component of the compensation voltage reference value at time, for The zero-sequence component of the compensation voltage reference value at time for The positive sequence component of the predicted value of the compensation voltage at time instant, for The negative sequence component of the predicted value of the compensation voltage at time instant, for The zero-sequence component of the predicted value of the compensation voltage at time instant.

[0105] In summary, this embodiment provides a voltage control method for a dynamic voltage restorer, which can effectively simplify the switch control of a three-phase four-bridge-arm DVR. The above-mentioned MPC method can quickly and flexibly generate a switch configuration scheme to cope with voltage changes, and the setting of the cost function ensures that the system always adopts the optimal switch configuration scheme at any time. Under the voltage control method proposed in this embodiment, the three-phase four-bridge-arm inverter performs better when dealing with unbalanced working conditions.

[0106] It should be understood that, although the various steps in the flowcharts involved in the above-mentioned embodiments are displayed in sequence according to the indication of the arrows, these steps are not necessarily executed in sequence according to the order indicated by the arrows. Unless there is a clear explanation in this article, the execution of these steps does not have a strict order restriction, and these steps can be executed in other orders. Moreover, at least a part of the steps in the flowcharts involved in the above-mentioned embodiments can include multiple steps or multiple stages, and these steps or stages are not necessarily executed at the same time, but can be executed at different times, and the execution order of these steps or stages is not necessarily to be carried out in sequence, but can be executed in turn or alternately with other steps or at least a part of the steps or stages in other steps.

[0107] Based on the same inventive concept, the embodiment of the present application also provides a dynamic voltage restorer voltage control system for implementing the dynamic voltage restorer voltage control method involved above. The implementation scheme for solving the problem provided by the device is similar to the implementation scheme recorded in the above method, so the specific limitations in one or more dynamic voltage restorer voltage control system embodiments provided below can refer to the limitations of the dynamic voltage restorer voltage control method above, and will not be repeated here.

[0108] In one embodiment, Fig. 9 As shown, a dynamic voltage restorer voltage control system 900 is provided. Compared with the three-phase four-bridge-arm dynamic voltage restorer in the aforementioned embodiment, each bridge arm of the three-phase four-bridge-arm dynamic voltage restorer includes a switch assembly composed of at least two switch tubes. The dynamic voltage restorer voltage control system 900 includes: an acquisition module 910, a calculation module 920 and a control module 930, wherein:

[0109] An acquisition module 910 is used to acquire compensation voltage reference values ​​and compensation voltage prediction values ​​of a three-phase four-bridge arm dynamic voltage restorer under a preset number of switch configuration schemes, wherein the compensation voltage reference values ​​include a positive-sequence voltage reference value, a negative-sequence voltage reference value, and a zero-sequence voltage reference value, and the compensation voltage prediction values ​​include a positive-sequence voltage prediction value, a negative-sequence voltage prediction value, and a zero-sequence voltage prediction value;

[0110] A calculation module 920 is used to calculate the cost value corresponding to each switch configuration scheme according to a preset cost function, a compensation voltage reference value and a compensation voltage prediction value, and determine the optimal switch configuration scheme from the switch configuration scheme corresponding to the minimum cost value;

[0111] The control module 930 is used to control the switch assembly according to the optimal switch configuration scheme so that the three-phase four-bridge arm dynamic voltage restorer outputs the target compensation voltage.

[0112] In one embodiment, the calculation module 920 is specifically used for the calculation module, specifically for obtaining the positive-sequence component, negative-sequence component and zero-sequence component of the circuit parameters of the three-phase four-bridge arm dynamic voltage restorer under different switch configuration schemes, wherein the circuit parameters include output voltage, inductor voltage and output current; processing the positive-sequence component, negative-sequence component and zero-sequence component of the circuit parameters according to the vector angle compensation method, and calculating the compensation voltage reference value; processing the positive-sequence component, negative-sequence component and zero-sequence component of the circuit parameters according to the preset voltage prediction model algorithm, and obtaining the compensation voltage prediction value.

[0113] In one of the embodiments, the acquisition module 910 is specifically used to collect the three-phase stationary coordinate system parameters of the three-phase four-bridge arm dynamic voltage restorer under different switch configuration schemes; perform Clarke transformation on the three-phase stationary coordinate system parameters to obtain the two-phase stationary coordinate system parameters; use two second-order generalized integrators to perform positive and negative sequence decoupling on the two-phase stationary coordinate system parameters to obtain the positive sequence component, negative sequence component and zero sequence component of the circuit parameters.

[0114] Each module in the above-mentioned dynamic voltage restorer voltage control system can be implemented in whole or in part by software, hardware and a combination thereof. Each of the above-mentioned modules can be embedded in or independent of a processor in an electronic device in the form of hardware, or can be stored in a memory in an electronic device in the form of software, so that the processor can call and execute the operations corresponding to each of the above modules.

[0115] In one embodiment, an electronic device is provided. The electronic device may be a terminal, and its internal structure diagram may be as follows: Fig.10As shown. The electronic device includes a processor, a memory, an input / output interface, a communication interface, a display unit and an input device. The processor, the memory and the input / output interface are connected through a system bus, and the communication interface, the display unit and the input device are connected to the system bus through the input / output interface. The processor of the electronic device is used to provide computing and control capabilities. The memory of the electronic device includes a non-volatile storage medium and an internal memory. The non-volatile storage medium stores an operating system and a computer program. The internal memory provides an environment for the operation of the operating system and the computer program in the non-volatile storage medium. The input / output interface of the electronic device is used to exchange information between the processor and the external device. The communication interface of the electronic device is used to communicate with an external terminal in a wired or wireless manner, and the wireless manner can be implemented through WIFI, a mobile cellular network, NFC (near field communication) or other technologies. When the computer program is executed by the processor, a dynamic voltage restorer voltage control method is implemented. The display unit of the electronic device is used to form a visually visible picture, which can be a display screen, a projection device or a virtual reality imaging device. The display screen can be a liquid crystal display screen or an electronic ink display screen, and the input device of the electronic device can be a touch layer covering the display screen, or a button, trackball or touchpad set on the electronic device casing, or an external keyboard, touchpad or mouse.

[0116] Those skilled in the art will understand that Fig.10 The structure shown in the figure is merely a block diagram of a partial structure related to the scheme of the present application, and does not constitute a limitation on the electronic device to which the scheme of the present application is applied. The specific electronic device may include more or fewer components than shown in the figure, or combine certain components, or have a different arrangement of components.

[0117] Those skilled in the art can understand that all or part of the processes in the above-mentioned embodiment methods can be completed by instructing the relevant hardware through a computer program, and the computer program can be stored in a non-volatile computer-readable storage medium. When the computer program is executed, it can include the processes of the embodiments of the above-mentioned methods. Among them, any reference to the memory, database or other medium used in the embodiments provided in this application can include at least one of non-volatile and volatile memory. Non-volatile memory can include read-only memory (ROM), magnetic tape, floppy disk, flash memory, optical memory, high-density embedded non-volatile memory, resistive random access memory (ReRAM), magnetoresistive random access memory (MRAM), ferroelectric random access memory (FRAM), phase change memory (PCM), graphene memory, etc. Volatile memory can include random access memory (RAM) or external cache memory, etc. As an illustration and not limitation, RAM can be in various forms, such as static random access memory (SRAM) or dynamic random access memory (DRAM). The database involved in each embodiment provided in this application may include at least one of a relational database and a non-relational database. Non-relational databases may include distributed databases based on blockchains, etc., but are not limited to this. The processor involved in each embodiment provided in this application may be a general-purpose processor, a central processing unit, a graphics processor, a digital signal processor, a programmable logic device, a data processing logic device based on quantum computing, etc., but are not limited to this.

[0118] The technical features of the above embodiments may be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0119] The above-described embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the present application. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the present application shall be subject to the attached claims.

Claims

1. A voltage control method for a dynamic voltage restorer, characterized in that: Applied to a three-phase four-bridge-arm dynamic voltage restorer, each bridge arm of the three-phase four-bridge-arm dynamic voltage restorer includes a switch assembly consisting of at least two switch tubes, including: Obtaining compensation voltage reference values ​​and compensation voltage prediction values ​​of the three-phase four-bridge arm dynamic voltage restorer under a preset number of switch configuration schemes, wherein the compensation voltage reference values ​​include positive-sequence voltage reference values, negative-sequence voltage reference values, and zero-sequence voltage reference values, and the compensation voltage prediction values ​​include positive-sequence voltage prediction values, negative-sequence voltage prediction values, and zero-sequence voltage prediction values; According to the preset cost function, the compensation voltage reference value and the compensation voltage prediction value, respectively calculate the cost value corresponding to each switch configuration scheme, and determine the optimal switch configuration scheme from the switch configuration scheme corresponding to the minimum cost value; The switch component is controlled according to the optimal switch configuration scheme so that the three-phase four-bridge arm dynamic voltage restorer outputs a target compensation voltage.

2. The method according to claim 1, characterized in that The obtaining of the compensation voltage reference value and the compensation voltage prediction value of the three-phase four-bridge arm dynamic voltage restorer under a preset number of switch configuration schemes includes: Obtaining positive-sequence components, negative-sequence components, and zero-sequence components of circuit parameters of the three-phase four-bridge-arm dynamic voltage restorer under different switch configuration schemes, wherein the circuit parameters include output voltage, inductor voltage, and output current; Processing the positive sequence component, negative sequence component and zero sequence component of the circuit parameter according to the vector angle compensation method, and calculating the compensation voltage reference value; The positive sequence component, negative sequence component and zero sequence component of the circuit parameter are processed according to a preset voltage prediction model algorithm to obtain the compensation voltage prediction value.

3. The method according to claim 2, characterized in that The obtaining of positive sequence components, negative sequence components and zero sequence components of circuit parameters of the three-phase four-bridge arm dynamic voltage restorer under different switch configuration schemes includes: Collecting three-phase stationary coordinate system parameters of the three-phase four-bridge arm dynamic voltage restorer under different switch configuration schemes; Performing Clarke transformation on the three-phase stationary coordinate system parameters to obtain two-phase stationary coordinate system parameters; Two second-order generalized integrators are used to perform positive-negative sequence decoupling on the two-phase stationary coordinate system parameters to obtain the positive-sequence component, negative-sequence component and zero-sequence component of the circuit parameters.

4. The method according to claim 2, characterized in that: The step of processing the positive sequence component, the negative sequence component and the zero sequence component of the circuit parameter according to the vector angle compensation method to calculate the compensation voltage reference value comprises: Processing the positive-sequence component and the negative-sequence component of the compensation voltage according to the vector angle compensation method, and calculating the positive-sequence voltage reference value and the negative-sequence voltage reference value; The zero-sequence component of the compensation voltage is processed according to the vector angle compensation method, and the zero-sequence voltage reference value is calculated.

5. The method according to claim 2, characterized in that: The step of processing the positive sequence component, the negative sequence component and the zero sequence component of the circuit parameter according to a preset voltage prediction model algorithm to obtain the compensation voltage prediction value includes: Acquire an output voltage prediction model according to the topological structure of the three-phase four-bridge-arm dynamic voltage restorer; Processing the voltage prediction model according to the zero-order hold method to obtain a discrete model of the three-phase four-bridge arm dynamic voltage restorer; The compensation voltage prediction value is calculated by combining the discrete model of the three-phase four-bridge arm dynamic voltage restorer and the positive sequence component, negative sequence component and zero sequence component of the circuit parameters under the corresponding switch configuration scheme.

6. The method according to claim 1, characterized in that The cost values ​​corresponding to each switch configuration scheme are calculated respectively according to the preset cost function, the compensation voltage reference value and the compensation voltage prediction value, including: The cost value is obtained by calculating the sum of squares of differences between the compensation voltage reference value and the compensation voltage prediction value.

7. A dynamic voltage restorer voltage control system, characterized in that: Applied to a three-phase four-bridge-arm dynamic voltage restorer, each bridge arm of the three-phase four-bridge-arm dynamic voltage restorer includes a switch assembly consisting of at least two switch tubes, including: An acquisition module, used to acquire a compensation voltage reference value and a compensation voltage prediction value of the three-phase four-bridge arm dynamic voltage restorer under a preset number of switch configuration schemes, wherein the compensation voltage reference value includes a positive-sequence voltage reference value, a negative-sequence voltage reference value, and a zero-sequence voltage reference value, and the compensation voltage prediction value includes a positive-sequence voltage prediction value, a negative-sequence voltage prediction value, and a zero-sequence voltage prediction value; A calculation module, configured to calculate the cost values ​​corresponding to each switch configuration scheme according to a preset cost function, the compensation voltage reference value and the compensation voltage prediction value, and determine the optimal switch configuration scheme from the switch configuration scheme corresponding to the minimum cost value; A control module is used to control the switch component according to the optimal switch configuration scheme so that the three-phase four-bridge arm dynamic voltage restorer outputs a target compensation voltage.

8. The system according to claim 7, characterized in that The calculation module is specifically used to obtain the positive-sequence component, negative-sequence component and zero-sequence component of the circuit parameters of the three-phase four-bridge arm dynamic voltage restorer under different switch configuration schemes, wherein the circuit parameters include output voltage, inductor voltage and output current; process the positive-sequence component, negative-sequence component and zero-sequence component of the circuit parameters according to the vector angle compensation method, and calculate the compensation voltage reference value; process the positive-sequence component, negative-sequence component and zero-sequence component of the circuit parameters according to a preset voltage prediction model algorithm to obtain the compensation voltage prediction value.

9. The system according to claim 8, characterized in that The acquisition module is specifically used to collect the three-phase stationary coordinate system parameters of the three-phase four-bridge arm dynamic voltage restorer under different switch configuration schemes; perform Clarke transformation on the three-phase stationary coordinate system parameters to obtain two-phase stationary coordinate system parameters; use two second-order generalized integrators to perform positive and negative sequence decoupling on the two-phase stationary coordinate system parameters to obtain the positive sequence component, negative sequence component and zero sequence component of the circuit parameters.

10. An electronic device, characterized in that: A dynamic voltage restorer voltage control system comprising the method described in any one of claims 7 to 9.

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