Method for controlling voltage regulating device without direct current bus capacitor and giving consideration to voltage harmonic compensation

Abstract

The invention relates to a control method of a voltage regulating device without a direct-current bus capacitor considering voltage harmonic compensation. The control method comprises the following steps: step 1, building a circuit model of the voltage regulating device without the direct-current bus capacitor; and 2, applying a control algorithm to the voltage regulating device without the DC bus capacitor constructed in the step 1, and carrying out harmonic suppression and voltage regulation. According to the invention, the output voltage can be adjusted in a closed-loop manner, and the background harmonic voltage of the power distribution network is effectively compensated in an open-loop control manner.

Description

Technical Field

[0001] The present invention relates to the technical field of power quality control, and in particular to a control method for a voltage regulator without a DC bus capacitor, and in particular to a control method for a voltage regulator without a DC bus capacitor taking into account voltage harmonic compensation. Background Art

[0002] With the rapid development of new energy and the continuous development of power electronics technology, distributed energy is connected to the grid on a large scale, and the voltage of the distribution network shows the characteristics of rapid fluctuation. At the same time, more and more power electronic equipment are connected to the power grid, the nonlinear loads in the power system continue to increase, and the harmonic problem in the power system is becoming more and more serious, which seriously affects the power quality of the distribution network supplying power to key loads. Therefore, the use of flexible devices for voltage regulation and harmonic compensation has become an important means of power quality management.

[0003] When the grid voltage fluctuates frequently, the flexible voltage regulator can quickly adjust the load-side voltage through closed-loop regulation. However, in many cases, the power supply voltage provided by the distribution network to the load is often non-sinusoidal. Therefore, when supplying power to key loads in the distribution network, harmonic compensation measures are usually required.

[0004] The earliest harmonic compensation measure adopted was to use a passive filter on the output side of the voltage regulator. This device achieves compensation for voltage harmonics at the simplest and lowest cost, but passive filters often have poor load capacity and may resonate with the system. Therefore, some manufacturers currently use active filters for harmonic compensation. It has high controllability and fast response. It can not only compensate for each harmonic, but also suppress voltage flicker and compensate for reactive current. However, its cost is relatively high and has high requirements for power supply stability and ripple disturbance. Nonlinear distortion or oscillation may occur. At the same time, all of the above methods require harmonic compensation methods other than voltage regulation. To address this problem, many manufacturers use PWM pulse width modulation technology, use the existing hardware circuits of flexible voltage regulators, detect the harmonic voltage on the load side, and use proportional resonance control to compensate for the harmonic voltage on the load side. However, this control strategy that relies entirely on closed-loop control to compensate for harmonics is often more complicated.

[0005] At the same time, since the operating mode of the power distribution network will change, the effect of proportional resonant control may be affected, and the proportional resonant controller has high requirements on the accuracy of the resonant frequency, is more complex to design and implement, and has higher program complexity. Therefore, it is necessary to seek a simple and efficient control method.

[0006] After searching, no prior art documents identical or similar to the present invention were found. Summary of the invention

[0007] The purpose of the present invention is to overcome the shortcomings of the prior art and to propose a control method for a voltage regulator without a DC bus capacitor that takes into account voltage harmonic compensation, which can adjust the output voltage in a closed loop and take into account the effective compensation of the background harmonic voltage of the distribution network through open loop control.

[0008] The present invention solves the practical problem by adopting the following technical solutions:

[0009] A control method for a voltage regulating device without a DC bus capacitor taking into account voltage harmonic compensation comprises the following steps:

[0010] Step 1, build a circuit model without a DC bus capacitor voltage regulator;

[0011] Step 2: Apply a control algorithm to the voltage regulator without DC bus capacitor built in step 1 to perform harmonic suppression and voltage regulation.

[0012] Moreover, the voltage regulating device without DC bus capacitor in step 1 includes: a controller, a rectifier bridge circuit, an inverter bridge circuit, a small-capacity industrial frequency half-wave DC capacitor, a filter and a voltage sensor; the first end of the rectifier bridge circuit is connected to the power distribution network, the second end of the rectifier bridge is connected in parallel with the small-capacity industrial frequency half-wave DC capacitor and connected to the first end of the inverter bridge circuit, the second end of the inverter bridge circuit is connected to the first end of the filter, the second end of the filter is connected to the load, and the control signal output by the controller is connected to the gate of the fully controlled device of the rectifier bridge and the inverter bridge; the voltage sensor is arranged at the first end of the rectifier bridge; and voltage sensors are respectively arranged at the first end of the rectifier bridge and at both ends of the load.

[0013] Moreover, the specific steps of step 2 include:

[0014] Step S201: Using the voltage sensor, measure the voltage v of the distribution network. g The output voltage v of the voltage regulator L ;

[0015] Step S202: The controller receives the power distribution network voltage information v g , which is used to indicate the sinusoidal AC voltage v of the distribution network g Rectified into industrial frequency half-wave DC voltage v dc The modulation wave ma dc ;

[0016] The controller is used to receive the distribution network voltage information measured by the voltage transformer, and the distribution network voltage information is used to instruct the generation of control signals for the rectifier bridge and the inverter bridge;

[0017] Step S203: The controller receives the power distribution network voltage information v g, the fundamental voltage component v of the distribution network voltage is separated by a filter g,f and harmonic voltage components v g,h ;

[0018] Step S204: The controller obtains the fundamental voltage component v of the distribution network based on the obtained g,f With the harmonic voltage component v g,h , and obtain the modulation wave ma used for open-loop compensation of the background harmonic voltage of the distribution network g,h ;

[0019] Step S205: The controller is also used to receive the output voltage information v of the voltage regulating device measured by the voltage transformer. L , and generates the output voltage v of the voltage regulator L The reference voltage signal v L,ref , and based on the received voltage information v output by the voltage regulator L With the distribution network voltage information v g , and obtain the modulation wave ma used to indicate the magnitude of the fundamental wave of the output voltage of the voltage regulator L,f ;

[0020] Step S206: The controller obtains a modulation wave ma for indicating the background harmonic voltage of the open-loop compensation distribution network. g,h and the modulation wave ma used to indicate the size of the closed-loop regulated output voltage fundamental wave L,f , and obtain the control signal ma of the power conversion circuit without DC bus capacitor voltage regulation device total ;

[0021] Step S207: The controller obtains the modulation wave ma dc andma total After that, the switching signals of the rectifier bridge and the inverter bridge fully controlled devices are obtained through pulse width modulation, so as to control the opening and closing of the fully controlled devices, realize the closed-loop regulation of the load side voltage and the open-loop compensation of the background harmonic voltage of the distribution network.

[0022] Moreover, the implementation method of step S202 is: according to the controller based on the received distribution network voltage information v g , which is used to indicate the sinusoidal AC voltage v of the distribution network g Rectified into industrial frequency half-wave DC voltage v dc The modulation wave ma dc , as shown in the following formula (1):

[0023]

[0024] Furthermore, the implementation of step S203 includes the following steps:

[0025] The controller receives the distribution network voltage information v g, through the second-order generalized integrator G SOGI (s) Get the fundamental voltage component v of the distribution network voltage g,f As shown in the following formula (2):

[0026]

[0027] Where ω s is the resonant frequency of the second-order generalized integrator, k is the closed-loop coefficient of the second-order generalized integrator;

[0028] Based on the fundamental voltage component v of the distribution network voltage obtained g,f , we can get the harmonic voltage component v of the distribution network voltage g,h , as shown in the following formula (3):

[0029] v g,h =v g -v g,f (3)

[0030] Moreover, the implementation method of step S204 is that the controller obtains the fundamental voltage component v of the distribution network based on the obtained g,f With the harmonic voltage component v g,h By taking the quotient of the two, the modulation wave ma used for open-loop compensation of the background harmonic voltage of the distribution network is obtained. g,h , as shown in the following formula (4):

[0031] ma g,h =v g,h / v g (4)

[0032] Furthermore, the implementation method of step S205 is that the controller is also used to generate an output voltage v of the voltage regulating device. L The reference voltage signal v L,ref , and based on the received voltage information v output by the voltage regulator L With the distribution network voltage information v g After closed-loop control, the modulation wave ma is obtained to indicate the magnitude of the fundamental wave of the output voltage of the voltage regulator. L,f , including the following steps:

[0033] The controller determines the frequency f of the output voltage by ref With amplitude A ref , the output voltage v is obtained by calculation L The reference voltage signal v L,ref , as shown in the following formula (5):

[0034] v L,ref =A ref ×sin(2πf ref t+θ ref ) (5)

[0035] Where t is the time when the controller starts running;

[0036] The controller also outputs voltage information v based on the received voltage regulating device. L With the distribution network voltage information v g , through the proportional-integral controller G PI (s) obtain the modulation wave ma used to indicate the magnitude of the fundamental wave of the output voltage of the voltage regulator L,f , as shown in the following formula (6):

[0037]

[0038] In the formula, k p represents the proportional coefficient of the proportional-integral controller, k i represents the integral coefficient of the proportional-integral controller, and s represents the complex variable in the Laplace transform.

[0039] Moreover, the specific implementation of step S206 is as shown in the following formula (7):

[0040] ma total =ma g,h +ma L,f (7)

[0041] Advantages and beneficial effects of the present invention:

[0042] 1. The present invention proposes a control method for a voltage regulating device without a DC bus capacitor that takes into account voltage harmonic compensation in a distribution network scenario, which can be applied to flexible voltage regulation in a distribution network scenario. The voltage regulating device without a DC bus capacitor includes a front-stage rectifier bridge, a rear-stage inverter bridge, an intermediate-stage small-capacity industrial frequency half-wave DC capacitor and an output side filter; the front-stage rectifier bridge is used to rectify the input sinusoidal AC voltage into industrial frequency half-wave DC, and the rear-stage inverter bridge is used to perform DC chopping and inversion to generate the required AC output, and the size of the output voltage fundamental wave is adjusted by proportional-integral control in a closed loop, and an open-loop harmonic compensation signal is superimposed on the modulation wave of the rear-stage inverter bridge. While regulating the voltage, it can take into account the problem that the distribution network has background harmonics and affects the power supply quality due to the access of nonlinear loads, which greatly reduces the parameter sensitivity and program complexity of the harmonic compensation algorithm.

[0043] 2. The control method of the DC bus capacitor-free voltage regulator device taking into account voltage harmonic compensation proposed in the present invention adopts a circuit topology with an intermediate stage of industrial frequency half-wave DC, which greatly reduces the capacity of the DC link capacitor and reduces the hardware cost. It has strong practicality in the field of power electronic AC voltage regulation.

[0044] 3. The control method of the DC bus capacitor-free voltage regulator device taking into account voltage harmonic compensation proposed in the present invention adopts a control strategy of closed-loop regulation while taking into account open-loop harmonic compensation. The closed-loop regulation is performed by detecting the load-side voltage through a proportional-integral controller, and the input-side voltage is detected and open-loop compensation is performed for the input-side voltage harmonics. This reduces the complexity of the control strategy and the calculation pressure of the controller, and can ensure the power quality of the load-side voltage when the distribution network voltage contains background harmonics.

[0045] 4. The control method of the DC bus capacitor-free voltage regulator device taking into account voltage harmonic compensation proposed in the present invention enables the four fully-controlled devices of the rectifier bridge and the fully-controlled devices of the first bridge arm of the inverter bridge to operate in a fundamental frequency modulation state, thereby reducing switching noise and switching losses as much as possible and ensuring the efficiency and quality of power transmission. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Figure 1 An electrical connection structure diagram of a voltage regulator without a DC bus capacitor provided by an example of the present invention;

[0047] Figure 2 A schematic diagram of an implementation flow of a control method for a voltage regulating device without a DC bus capacitor taking into account voltage harmonic compensation provided by an embodiment of the present invention;

[0048] Figure 3 A controller block diagram of a control method for a voltage regulating device without a DC bus capacitor taking into account voltage harmonic compensation provided by an embodiment of the present invention;

[0049] Figure 4 An algorithm flow chart for closed-loop voltage regulation and open-loop harmonic compensation provided by an embodiment of the present invention;

[0050] Figure 5 A simulation operation effect diagram of the proportional resonant closed-loop voltage harmonic compensation provided by an embodiment of the present invention;

[0051] Figure 6 A simulation operation effect diagram of proportional resonant closed-loop voltage regulation and open-loop harmonic compensation provided by an embodiment of the present invention;

[0052] Figure 7 A simulation operation effect diagram of the proportional-integral closed-loop voltage regulation and open-loop harmonic compensation provided by an embodiment of the present invention;

[0053] Figure 8 It is a schematic diagram of a module of an embodiment of a control method for a voltage regulating device without a DC bus capacitor taking into account voltage harmonic compensation provided by an embodiment of the present invention;

[0054] Fig. 9 It is a schematic diagram of a DC bus capacitor-free voltage regulating device provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0055] The following is a further description of the embodiments of the present invention:

[0056] A control method for a voltage regulating device without a DC bus capacitor taking into account voltage harmonic compensation comprises the following steps:

[0057] Step 1, build a circuit model without a DC bus capacitor voltage regulator;

[0058] Build as Figure 1 The circuit model of the voltage regulating device without DC bus capacitor shown;

[0059] The voltage regulating device without DC bus capacitor in step 1 comprises: a controller, a rectifier bridge circuit, an inverter bridge circuit, a small-capacity industrial frequency half-wave DC capacitor, a filter and a voltage sensor; the first end of the rectifier bridge circuit is connected to the power distribution network, the second end of the rectifier bridge is connected in parallel with the small-capacity industrial frequency half-wave DC capacitor and connected to the first end of the inverter bridge circuit, the second end of the inverter bridge circuit is connected to the first end of the filter, the second end of the filter is connected to the load, and the control signal output by the controller is connected to the gate of the fully controlled device of the rectifier bridge and the inverter bridge; the voltage sensor is arranged at the first end of the rectifier bridge; and voltage sensors are respectively arranged at the first end of the rectifier bridge and at both ends of the load.

[0060] Step 2, applying a control algorithm to the voltage regulating device without DC bus capacitor built in step 1 to perform harmonic suppression and voltage regulation;

[0061] Please refer to Figure 2 , a schematic diagram of the implementation flow of a control method for a voltage regulating device without a DC bus capacitor taking into account voltage harmonic compensation.

[0062] The specific steps of step 2 include:

[0063] Step S201: Using the voltage sensor, measure the voltage v of the distribution network. g The output voltage v of the voltage regulator L ;

[0064] Step S202: The controller receives the power distribution network voltage information v g , which is used to indicate the sinusoidal AC voltage v of the distribution network g Rectified into industrial frequency half-wave DC voltage v dc The modulation wave ma dc ;

[0065] The controller is used to receive the distribution network voltage information measured by the voltage transformer, and the distribution network voltage information is used to instruct the generation of control signals for the rectifier bridge and the inverter bridge;

[0066] Step S202 is implemented by: g , which is used to indicate the sinusoidal AC voltage v of the distribution network g Rectified into industrial frequency half-wave DC voltage v dc The modulation wave ma dc , as shown in the following formula (1):

[0067]

[0068] Please refer to Figure 3 , a controller block diagram of a voltage regulating device control method without DC bus capacitor taking into account voltage harmonic compensation, including:

[0069] Step S203: The controller receives the power distribution network voltage information v g , the fundamental voltage component v of the distribution network voltage is separated by a filter g,f and harmonic voltage components v g,h ;

[0070] The implementation of step S203 includes the following steps:

[0071] The controller receives the distribution network voltage information v g , through the second-order generalized integrator G SOGI (s) Get the fundamental voltage component v of the distribution network voltage g,f As shown in the following formula (2):

[0072]

[0073] Where ω s is the resonant frequency of the second-order generalized integrator, k is the closed-loop coefficient of the second-order generalized integrator;

[0074] Based on the fundamental voltage component v of the distribution network voltage obtained g,f , we can get the harmonic voltage component v of the distribution network voltage g,h , as shown in the following formula (3):

[0075] v g,h =v g -v g,f (3)

[0076] Step S204: The controller obtains the fundamental voltage component v of the distribution network based on the obtained g,f With the harmonic voltage component v g,h , and obtain the modulation wave ma used for open-loop compensation of the background harmonic voltage of the distribution network g,h ;

[0077] Step S204 is implemented by: the controller obtains the fundamental voltage component v of the distribution network based on the obtainedg,f With the harmonic voltage component v g,h By taking the quotient of the two, the modulation wave ma used for open-loop compensation of the background harmonic voltage of the distribution network is obtained. g,h , as shown in the following formula (4):

[0078] ma g,h =v g,h / v g (4)

[0079] Step S205: The controller is also used to receive the output voltage information v of the voltage regulating device measured by the voltage transformer. L , and generates the output voltage v of the voltage regulator L The reference voltage signal v L,ref , and based on the received voltage information v output by the voltage regulator L With the distribution network voltage information v g , and obtain the modulation wave ma used to indicate the magnitude of the fundamental wave of the output voltage of the voltage regulator L,f ;

[0080] Step S205 is implemented by: the controller is further used to generate an output voltage v of the voltage regulator L The reference voltage signal v L,ref , and based on the received voltage information v output by the voltage regulator L With the distribution network voltage information v g After closed-loop control, the modulation wave ma is obtained to indicate the magnitude of the fundamental wave of the output voltage of the voltage regulator. L,f , including the following steps:

[0081] The controller determines the frequency f of the output voltage by ref With amplitude A ref , the output voltage v is obtained by calculation L The reference voltage signal v L,ref , as shown in the following formula (5):

[0082] v L,ref =A ref ×sin(2πf ref t+θ ref ) (5)

[0083] Where t is the time when the controller starts running;

[0084] The controller also outputs voltage information v based on the received voltage regulating device. L With the distribution network voltage information v g , through the proportional-integral controller G PI (s) obtain the modulation wave ma used to indicate the magnitude of the fundamental wave of the output voltage of the voltage regulator L,f , as shown in the following formula (6):

[0085]

[0086] In the formula, k p represents the proportional coefficient of the proportional-integral controller, k i represents the integral coefficient of the proportional-integral controller, and s represents the complex variable in the Laplace transform.

[0087] Step S206: The controller obtains a modulation wave ma for indicating the background harmonic voltage of the open-loop compensation distribution network. g,h And the modulation wave ma used to indicate the size of the closed-loop regulation output voltage fundamental wave L,f , and obtain the control signal ma of the power conversion circuit without DC bus capacitor voltage regulation device total ;

[0088] The specific implementation method is shown in the following formula (7):

[0089] ma total =ma g,h +ma L,f (7)

[0090] Step S207: The controller obtains the modulation wave ma dc andma total After that, the switching signals of the rectifier bridge and the inverter bridge fully controlled devices are obtained through pulse width modulation, so as to control the opening and closing of the fully controlled devices, realize the closed-loop regulation of the load side voltage and the open-loop compensation of the background harmonic voltage of the distribution network.

[0091] Figure 4 The algorithm flow chart of closed-loop voltage regulation and open-loop harmonic compensation provided by the embodiment of the present invention first measures the distribution network v g With the load side voltage v L , based on the distribution network voltage, generates a rectifier modulation signal ma to control the rectifier bridge dc ; Separate the fundamental component v of the distribution network voltage through the filter g,f With the harmonic voltage component v g,h , and calculate the modulation wave signal ma used for open-loop compensation of background harmonics in the distribution network g,h Based on the output voltage v L Generate reference signal v L,ref , and obtain the modulation signal ma of the output voltage fundamental wave through closed-loop control L,f ; The modulation wave ma of the inverter bridge is obtained based on the obtained open-loop harmonic compensation modulation wave and the closed-loop fundamental voltage control modulation wave total , and generates a control signal through a pulse width modulator, and the algorithm ends.

[0092] Figure 5This is the simulation waveform when the proportional resonance control method is used under the condition of distribution network distortion. From top to bottom, they are the distribution network voltage, load side voltage, and power frequency DC voltage. It can be seen that there is background harmonic voltage in the power grid, and the THD is 16.73%. After using the proportional resonance controller, the distribution network voltage THD can be compensated to 3.05%, but when the control strategy is set to Qidong, instability of about half a cycle occurs; Figure 6 The simulation waveforms are shown in Figure 1 when proportional resonance control and the proposed open-loop harmonic compensation strategy are used under the condition of distribution network distortion. It can be seen that when the distribution network voltage THD is 16.73%, the distribution network voltage THD can be compensated to 2.38% by using proportional resonance control and the proposed open-loop harmonic compensation strategy. At the same time, the instability phenomenon when the control strategy is started disappears. Figure 7 The simulation waveform of the proposed proportional integral control and open-loop harmonic compensation strategy method under the condition of distribution network distortion can be seen. When the distribution network voltage THD is 16.73%, the distribution network voltage THD can be compensated to 1.25% after the proposed proportional integral control and open-loop harmonic compensation strategy is adopted. Similarly, there is no instability phenomenon when the control strategy is started, and Figure 7 The control strategy adopted and Figure 6 Compared with the control strategy adopted, the complexity of its algorithm is greatly reduced. In summary, the control method of a voltage regulating device without DC bus capacitor taking into account voltage harmonic compensation proposed in the present invention is feasible. This control method can achieve precise voltage regulation and harmonic compensation. At the same time, the control algorithm is simple, which reduces the controller cost of the system.

[0093] The present invention is not limited to the embodiments described above. The above description of the specific embodiments is intended to describe and illustrate the technical solution of the present invention. The above specific embodiments are merely illustrative and not restrictive. Without departing from the scope of the present invention and the scope of protection of the claims, a person of ordinary skill in the art can also make many forms of specific changes under the guidance of the present invention, which all fall within the scope of protection of the present invention.

[0094] It should be understood that the order of execution of the steps in the above embodiment does not necessarily mean the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiment of the present invention.

[0095] Example module such as Figure 8 As shown, a control method for a voltage regulating device without a DC bus capacitor taking into account voltage harmonic compensation includes:

[0096] A first obtaining module 801 is used to obtain the distribution network voltage and the load side voltage according to the voltage sensor;

[0097] A first determination module 802 is used to determine a modulation signal for rectifying the sinusoidal AC voltage of the distribution network into a power frequency half-wave DC voltage according to the voltage information of the distribution network;

[0098] A second determination module is used to determine the fundamental component and harmonic component of the distribution network voltage through a filter according to the obtained distribution network voltage;

[0099] A third determination module is used to determine the modulation wave signal of the background harmonic voltage of the open-loop compensation distribution network according to the fundamental wave component and the harmonic component of the obtained distribution network voltage;

[0100] A fourth determination module is used to determine a modulation wave signal for adjusting the load voltage through closed-loop control according to the obtained distribution network voltage and load side voltage;

[0101] A fifth determining module, used to determine a modulation wave signal for controlling the operation of the inverter bridge according to the third determining module and the fourth determining module;

[0102] The second obtaining module is used to obtain a switch signal for controlling the operation of the rectifier bridge and the inverter bridge through pulse width modulation according to the first determining module and the fifth determining module.

[0103] Fig. 9 It is a schematic diagram of a control method of a voltage regulating device without a DC bus capacitor taking into account voltage harmonic compensation provided by an embodiment of the present invention.

[0104] The control method of the voltage regulator device without DC bus capacitor taking into account voltage harmonic compensation may include, but is not limited to, a converter circuit 901, a controller 902, and a memory 903. Those skilled in the art can understand that Fig. 9 It is only an example of the voltage regulating device 9 in the control method of the voltage regulating device without DC bus capacitor taking into account voltage harmonic compensation, and does not constitute a limitation on the voltage regulating device without DC bus capacitor, and may include more or less components than shown in the figure, or a combination of certain components, or different components.

[0105] The controller 902 may be a central processing unit (CPU), or other general-purpose processors, digital signal processors (DSP), application-specific integrated circuits (ASIC), field-programmable gate arrays (FPGA) or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. A general-purpose processor may be a microprocessor or the processor may be any conventional processor, etc.

[0106] The 903 may be an internal storage unit of the capacitor voltage regulator device 9 without a DC bus, or an external storage circuit of the capacitor voltage regulator device 9 without a DC bus. For example, a plug-in hard disk, a smart memory card (Smart Media Card, SMC), a secure digital (Secure Digital, SD) card, a flash card (FlashCard), etc. equipped on the voltage regulator device 9. Further, the memory 903 may also include both the internal storage unit of the voltage regulator device 9 and an external storage device. The memory 903 is used to store the computer program and other programs and data required by the capacitor voltage regulator device without a DC bus. The memory 903 can be used to temporarily store data that has been output or is to be output.

[0107] The technicians in the relevant field can clearly understand that for the convenience and simplicity of description, only the division of the above-mentioned functional units and modules is used as an example for illustration. In practical applications, the above-mentioned function allocation can be completed by different functional units and modules as needed, that is, the internal structure of the device can be divided into different functional units or modules to complete all or part of the functions described above. The functional units and modules in the embodiment can be integrated in a processing unit, or each unit can exist physically separately, or two or more units can be integrated in one unit. The above-mentioned integrated unit can be implemented in the form of hardware or in the form of software functional units. In addition, the specific names of the functional units and modules are only for the convenience of distinguishing each other, and are not used to limit the scope of protection of this application. The specific working process of the units and modules in the above-mentioned system can refer to the corresponding process in the aforementioned method embodiment, which will not be repeated here.

[0108] In the above embodiments, the description of each embodiment has its own emphasis. For parts that are not described or recorded in detail in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.

[0109] Those skilled in the art will appreciate that the units and algorithm steps of each example described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professional and technical personnel can use different methods to implement the described functions for each specific application, but such implementation should not be considered to be beyond the scope of the present invention.

[0110] In the embodiments provided by the present invention, it should be understood that the disclosed devices / terminal equipment and methods can be implemented in other ways. For example, the device / terminal equipment embodiments described above are only schematic. For example, the division of the modules or units is only a logical function division. There may be other division methods 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 through some interfaces, indirect coupling or communication connection of devices or units, which can be electrical, mechanical or other forms.

[0111] 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 of the units may be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0112] 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. The above-mentioned integrated unit may be implemented in the form of hardware or in the form of software functional units.

[0113] If the integrated module / unit 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 present invention implements all or part of the processes in the above-mentioned embodiment method, and can also be completed by instructing the relevant hardware through a computer program. The computer program can be stored in a computer-readable storage medium, and the computer program can implement the steps of the above-mentioned various method embodiments when executed by the processor. Among them, the computer program includes computer program code, and the computer program code can be in source code form, object code form, executable file or some intermediate form. The computer-readable medium may include: any entity or device capable of carrying the computer program code, recording medium, U disk, mobile hard disk, disk, optical disk, computer memory, read-only memory (ROM, Read-Only Memory), random access memory (RAM, Random Access Memory), electric carrier signal, telecommunication signal and software distribution medium. It should be noted that the content contained in the computer-readable medium can be appropriately increased or decreased according to the requirements of legislation and patent practice in the jurisdiction. For example, in some jurisdictions, according to legislation and patent practice, computer-readable media do not include electric carrier signals and telecommunication signals.

[0114] The embodiments described above are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. Such modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention, and should all be included in the protection scope of the present invention.

Claims

1. A control method for a voltage regulator without a DC bus capacitor taking into account voltage harmonic compensation, characterized in that: The following steps are involved: Step 1, build a circuit model without a DC bus capacitor voltage regulator; Step 2: Apply a control algorithm to the voltage regulator without DC bus capacitor built in step 1 to perform harmonic suppression and voltage regulation.

2. The control method of a voltage regulator without DC bus capacitor taking into account voltage harmonic compensation according to claim 1 is characterized in that: The voltage regulating device without DC bus capacitor in step 1 comprises: a controller, a rectifier bridge circuit, an inverter bridge circuit, a small-capacity industrial frequency half-wave DC capacitor, a filter and a voltage sensor; the first end of the rectifier bridge circuit is connected to the power distribution network, the second end of the rectifier bridge is connected in parallel with the small-capacity industrial frequency half-wave DC capacitor and connected to the first end of the inverter bridge circuit, the second end of the inverter bridge circuit is connected to the first end of the filter, the second end of the filter is connected to the load, and the control signal output by the controller is connected to the gate of the fully controlled device of the rectifier bridge and the inverter bridge; the voltage sensor is arranged at the first end of the rectifier bridge; and voltage sensors are respectively arranged at the first end of the rectifier bridge and at both ends of the load.

3. The control method of a voltage regulator without DC bus capacitor taking into account voltage harmonic compensation according to claim 1, characterized in that: The specific steps of step 2 include: Step S201: Using the voltage sensor, measure the voltage v of the distribution network. g The output voltage v of the voltage regulator L ; Step S202: The controller receives the power distribution network voltage information v g , which is used to indicate the sinusoidal AC voltage v of the distribution network g Rectified into industrial frequency half-wave DC voltage v dc The modulation wave ma dc ; The controller is used to receive the distribution network voltage information measured by the voltage transformer, and the distribution network voltage information is used to instruct the generation of control signals for the rectifier bridge and the inverter bridge; Step S203: The controller receives the power distribution network voltage information v g , the fundamental voltage component v of the distribution network voltage is separated by a filter g,f and harmonic voltage components v g,h ; Step S204: The controller obtains the fundamental voltage component v of the distribution network based on the obtained g,f With the harmonic voltage component v g,h , and obtain the modulation wave mg used for open-loop compensation of the background harmonic voltage of the distribution network g,h ; Step S205: The controller is also used to receive the output voltage information v of the voltage regulating device measured by the voltage transformer. L , and generates the output voltage v of the voltage regulator L The reference voltage signal v L,ref , and based on the received voltage information v output by the voltage regulator L With the distribution network voltage information v g , and obtain the modulation wave ma used to indicate the magnitude of the fundamental wave of the output voltage of the voltage regulator L,f ; Step S206: The controller obtains a modulation wave ma for indicating the background harmonic voltage of the open-loop compensation distribution network. g,h And the modulation wave ma used to indicate the size of the closed-loop regulation output voltage fundamental wave L,f , and obtain the control signal ma of the power conversion circuit without DC bus capacitor voltage regulation device total ; Step S207: The controller obtains the modulation wave ma dc andma total After that, the switching signals of the rectifier bridge and the inverter bridge fully controlled devices are obtained through pulse width modulation, so as to control the opening and closing of the fully controlled devices, realize the closed-loop regulation of the load side voltage and the open-loop compensation of the background harmonic voltage of the distribution network.

4. The control method of a voltage regulator without DC bus capacitor taking into account voltage harmonic compensation according to claim 3 is characterized in that: The implementation method of step S202 is: according to the controller based on the received distribution network voltage information v g , which is used to indicate the sinusoidal AC voltage v of the distribution network g Rectified into industrial frequency half-wave DC voltage v dc The modulation wave ma dc , as shown in the following formula (1):

5. The control method of a voltage regulator without DC bus capacitor taking into account voltage harmonic compensation according to claim 3 is characterized in that: The implementation of step S203 includes the following steps: The controller receives the distribution network voltage information v g , through the second-order generalized integrator G SOGI (s) Get the fundamental voltage component v of the distribution network voltage g,f As shown in the following formula (2): Where ω s is the resonant frequency of the second-order generalized integrator, k is the closed-loop coefficient of the second-order generalized integrator; Based on the fundamental voltage component v of the distribution network voltage obtained g,f , we can get the harmonic voltage component v of the distribution network voltage g,h , as shown in the following formula (3): v g,h =v g -v g,f (3)。 6. The control method of a voltage regulator without DC bus capacitor taking into account voltage harmonic compensation according to claim 3 is characterized in that: The implementation method of step S204 is that the controller obtains the fundamental voltage component v of the distribution network based on the obtained g,f With the harmonic voltage component v g,h By taking the quotient of the two, the modulation wave ma used for open-loop compensation of the background harmonic voltage of the distribution network is obtained. g,h , as shown in the following formula (4): me g,h =in g,h / in g (4)。 7. The control method of a voltage regulator without DC bus capacitor taking into account voltage harmonic compensation according to claim 3 is characterized in that: The implementation method of step S205 is that the controller is also used to generate an output voltage v of the voltage regulating device L The reference voltage signal v L,ref , and based on the received voltage information v output by the voltage regulator L With the distribution network voltage information v g After closed-loop control, the modulation wave ma is obtained to indicate the magnitude of the fundamental wave of the output voltage of the voltage regulator. L,f , including the following steps: The controller determines the frequency f of the output voltage by ref With amplitude A ref , the output voltage v is obtained by calculation L The reference voltage signal v L,ref , as shown in the following formula (5): v L,ref =A ref ×sin(2πf ref t+θ ref ) (5) Where t is the time when the controller starts running; The controller also outputs voltage information v based on the received voltage regulating device. L With the distribution network voltage information v g , through the proportional-integral controller G PI (s) obtain the modulation wave ma used to indicate the magnitude of the fundamental wave of the output voltage of the voltage regulator L,f , as shown in the following formula (6): In the formula, k p represents the proportional coefficient of the proportional-integral controller, k i represents the integral coefficient of the proportional-integral controller, and s represents the complex variable in the Laplace transform.

8. The control method of a voltage regulator without DC bus capacitor taking into account voltage harmonic compensation according to claim 3 is characterized in that: The specific implementation of step S206 is shown in the following formula (7): at total =at g,h + on L,f (7).

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