An adaptive resonance suppression device and control method for a medium voltage passive reactive compensation device

Abstract

The invention of the present application is applicable to the field of power quality of distribution networks, and particularly relates to a control method for a converter device in a compensation device. The method can be applied to reactive power compensation converters in scenarios such as distribution networks, and provides an adaptive resonance suppression method for a reactive power and harmonic compensation system in a distribution network. The compensation device includes a series capacitor and a converter, and the series capacitor is used to compensate for reactive power, and the converter is used to compensate for harmonic current. By connecting a frequency-divided virtual negative capacitor in parallel at the grid connection point of the compensation device, the problem of severe system resonance caused by excessive input capacitors can be solved. At the same time, by adjusting the applied frequency-divided virtual impedance and adaptively adjusting the output equivalent impedance of the converter through a closed-loop controller, the parallel capacitor branch switching logic and the converter coordination can be realized, and the system resonance can be effectively suppressed under multi-scenario conditions where the grid impedance is unknown and the capacitor input capacity changes.

Description

Technical Field

[0001] The invention of the present application is applicable to the field of power quality of distribution networks, and can be applied to reactive and harmonic hybrid compensation systems in distribution networks and other scenarios. It is a control strategy for suppressing reactive compensation systems and grid impedance resonance using frequency-band virtual impedance. Background Art

[0002] With the rapid development of new energy sources and the massive influx of distributed power sources into the grid, power quality issues such as harmonic pollution have been introduced into the power system. Active power filters, compared to traditional passive filters, offer advantages such as the ability to simultaneously achieve dynamic compensation for harmonics and reactive power, as well as faster response. Therefore, the use of active power filters has become a key trend in harmonic compensation.

[0003] When reactive loads appear in the grid, active power filters (APFs) can utilize their remaining capacity to actively inject reactive power into the system for reactive compensation. However, large-capacity APFs are generally expensive. When reactive loads are high, small-capacity APFs cannot simultaneously compensate for harmonics and inject reactive power. Therefore, some manufacturers are using hybrid compensation systems to compensate for both reactive power and harmonic currents, reducing the cost per unit of reactive capacity. Traditional hybrid compensation devices often separate active filters and capacitors, with separate controllers, making them inadequate for current weak grid scenarios. To address this issue, some manufacturers are combining active filters and capacitors to form hybrid compensation systems, which offer coordinated compensation and control. When capacitors are used for reactive compensation, the large-capacity reactive compensation capacitors can easily interact with the grid's impedance, causing resonance. This resonance generates large current harmonic components between the reactive compensation capacitor bank, nonlinear loads, and the grid, potentially damaging grid equipment.

[0004] At the same time, since the capacitance of the reactive capacitor is uncertain, and changes in the operation mode of the power grid will cause the grid impedance to change, the probability of resonance and the resonance peak frequency are uncertain. In this case, the traditional method of using active damping to suppress resonance and the method of adding a fixed virtual impedance may fail, resulting in greater safety hazards and instability. Summary of the Invention

[0005] The present invention proposes a control method for connecting harmonic virtual resistance and virtual negative capacitance in series at the reactive capacitor compensation point of the power grid, which can suppress harmonic current and reshape the closed-loop equivalent circuit output impedance of the hybrid active filter to achieve damping of system resonance.

[0006] The purpose of the present invention is achieved through the following technical solutions:

[0007] The output current of the power conversion circuit is measured by the current sensor and the voltage sensor. , switching capacitor current , load current , according to the voltage sensor, the filter voltage is measured , measure the DC bus voltage ;

[0008] The controller is used to receive grid power dispatch information, and the grid power dispatch information is used to indicate the reactive power reference that the reactive power compensation system needs to compensate. The controller distributes reactive power based on the reactive power reference obtained and determines the number of groups of capacitors that need to be switched on. ;

[0009] The controller is based on the obtained switching capacitor current , combined with the measured DC bus voltage , determine the fundamental voltage reference output of the power conversion circuit ;

[0010] The controller is further configured to receive the measured output current , through the harmonic extraction controller, the harmonic current reference required for compensation of the reactive compensation system is obtained ;

[0011] The controller obtains the harmonic current reference , through the vibration suppression controller, the frequency-dividing virtual resistance is applied, and at the same time, a negative virtual capacitance with the same equivalent impedance as the switched capacitor is applied to determine the output harmonic voltage reference of the power conversion circuit ;

[0012] The controller sets the initial value of virtual resistance for each frequency, based on the obtained common grid point voltage , the characteristic subharmonic voltage amplitude is obtained by the harmonic extractor controller , through the virtual impedance adaptive adjustment controller, the virtual impedance value of the frequency band is output;

[0013] The controller is based on the fundamental voltage reference and harmonic voltage reference , through the reference voltage generator, the voltage reference of the power conversion circuit is obtained ; and controlled by a frequency-band proportional resonant controller , get the power output current reference The controller is also used to control the output current of the power conversion circuit , the modulation wave of the power conversion circuit is obtained through the proportional controller ;

[0014] The controller is based on the obtained modulation wave , after coordinate transformation and then passing through a sinusoidal pulse width modulator, the control signal of the power conversion circuit is obtained. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 This is an electrical connection structure of a medium voltage passive reactive power compensation device provided by an embodiment of the present invention;

[0016] Figure 2 yes Figure 1 A schematic diagram of an implementation flow of a control method for adaptive resonance suppression of the device shown;

[0017] Figure 3 yes Figure 1 The harmonic voltage and fundamental voltage of the reactive compensation device and the voltage-current dual-loop controller block diagram are shown;

[0018] Figure 4 yes Figure 1 The adaptive virtual resistance adjustment control block diagram of the reactive compensation device shown;

[0019] Figure 5 yes Figure 1 The flowchart of the impedance adaptive adjustment algorithm of the reactive compensation device shown;

[0020] Figure 6 This is a simulation operation effect diagram of the traditional reactive power compensation system under independent control;

[0021] Figure 7 yes Figure 1 The simulation operation effect diagram of the series resonance suppression method of the reactive compensation system device shown;

[0022] Figure 8 This is a module diagram of an embodiment of a method for controlling resonance suppression of a reactive compensation device provided by an embodiment of the present invention;

[0023] Figure 9 It is a schematic diagram of a reactive power compensation device provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0024] To further clarify the objectives, technical solutions, and advantages of this application, the present application will be described in further detail below with reference to the accompanying drawings. The specific operating methods in the method embodiments can also be applied to the device embodiments or system embodiments. It should be noted that in the description of this application, "at least one" refers to one or more, while "multiple" refers to two or more. Therefore, in the embodiments of this application, "multiple" can also be understood as "at least two." "And / or" describes the relationship between associated objects, indicating that three possible relationships exist. For example, "A and / or B" can represent: A exists alone, A and B exist simultaneously, or B exists alone. Furthermore, the character " / ," unless otherwise specified, generally indicates that the associated objects are in an "or" relationship. Furthermore, it should be understood that in the description of this application, terms such as "first" and "second" are used solely for descriptive purposes and should not be construed to indicate or imply relative importance or order. The present invention will be further described below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present invention and are not intended to limit it.

[0025] The present invention proposes a method for controlling adaptive resonance suppression of a medium voltage passive reactive compensation device, comprising the following steps:

[0026] Please refer to Figure 1 , an electrical connection structure of an adaptive resonance suppression device of a medium voltage passive reactive compensation device, comprising:

[0027] Build as Figure 1 A circuit model includes a controller, a power conversion circuit, a filter, a current sensor, a voltage sensor, and a switching capacitor; a first end of the power conversion circuit is connected to the output end of the controller, a first voltage sensor is installed on the DC side of the power conversion circuit, a third end is connected to the first end of the first current sensor, a second end of the first current sensor is connected to the first end of the filter, a second voltage sensor is installed at the filter capacitor, a second end of the filter is connected to the first end of the switching capacitor, a second end of the switching capacitor is connected to the first end of the second current sensor, and a second end of the second current sensor is connected to the AC power grid; a second voltage sensor is installed at the public connection point between the reactive power compensation system and the AC power grid, and a local load is connected between the first end of the third current sensor and the public connection point;

[0028] Please refer to Figure 2 , a schematic diagram of an implementation flow of a control method for adaptive resonance suppression of a medium voltage passive reactive compensation device, comprising:

[0029] Step S201: Measure the output current of the power conversion circuit using the first current sensor. The second current sensor switches the capacitor current The first voltage sensor measures the DC bus voltage The second voltage sensor measures the filter voltage ;

[0030] Step S202: The controller is used to receive grid power dispatch information, which is used to indicate the reactive power reference that the reactive power compensation system needs to compensate. The controller distributes reactive power based on the reactive power reference obtained and determines the number of groups of capacitors that need to be switched on. ;

[0031] Optionally, step S202 is implemented by: , combined with the measured public grid point voltage , determine the number of switched capacitor groups , as shown in the following formula (1):

[0032] (1)

[0033] In the formula represents the fundamental angular frequency of the system, Indicates the capacity of the reactive capacitor.

[0034] Step S203: The controller obtains the switching capacitor current based on the , combined with the measured DC bus voltage , determine the fundamental voltage reference output of the power conversion circuit ;

[0035] Please refer to Figure 3 , block diagram of the harmonic voltage and fundamental voltage controller of the reactive power compensation system provided by the embodiment;

[0036] Optionally, step S203 is implemented by the controller receiving the obtained switching capacitor current and the DC bus voltage of the power converter , using a phase-locked loop to control the switching capacitor current Phase lock obtains the phase angle θ and converts the DC voltage and DC bus voltage Make the difference through the controller The fundamental voltage amplitude , combining the phase angle θ with the amplitude to obtain the fundamental voltage reference , including the following steps:

[0037] (2)

[0038] (3)

[0039] In the formula is the proportional-integral controller proportional coefficient, is the integration parameter;

[0040] Step S204: The controller is further configured to receive the measured output current. , through the harmonic extraction controller, the harmonic current reference required for compensation of the reactive compensation system is obtained ,

[0041] Optionally, step S204 is implemented by the controller receiving the measured , after coordinate transformation, we get , using a harmonic extractor Extracting harmonic currents , as shown in formula (4):

[0042] (4)

[0043] Where, represents the bandwidth at the center frequency of the controller, represents the fundamental angular frequency of the system, Indicates the harmonic order, which can be 5, 7, 9, 11, or 13.

[0044] Step S205: Obtain harmonic current reference according to the controller , through the reactive compensation system resonance suppression controller, the frequency-band virtual impedance is applied, and at the same time, a negative virtual impedance opposite to the equivalent impedance is applied to determine the power conversion circuit output harmonic voltage reference ;

[0045] Optionally, step S205 is implemented by the controller obtaining a harmonic current reference , through the reactive compensation system resonance suppression controller, the frequency-band virtual resistance is applied, and at the same time, a negative virtual capacitance with the same equivalent impedance as the switched capacitor is applied to determine the power conversion circuit output harmonic voltage reference The following steps are involved:

[0046] (5)

[0047] In the formula is the sum of the virtual resistance and the virtual negative capacitance impedance, is the virtual impedance of each harmonic.

[0048] Step S206: The controller sets the initial value of the virtual resistance of each frequency based on the obtained common grid point voltage , the characteristic subharmonic voltage amplitude is obtained by the harmonic extractor controller , executing the frequency-band virtual resistance and virtual negative capacitance adaptive adjustment controller through the reactive compensation device to adaptively adjust the frequency-band virtual impedance value output by the reactive compensation device;

[0049] Please refer to Figure 5 , which is a flow chart of the reactive compensation system impedance adaptive adjustment algorithm provided by an embodiment of the present invention;

[0050] Optionally, step S206 is implemented by the controller obtaining the common grid connection point voltage , the characteristic subharmonic amplitude component is obtained by the harmonic extractor , as shown below:

[0051] (6)

[0052] Where, is the characteristic order of harmonic voltage, It is the amplitude of the characteristic hth harmonic component of the grid connection point voltage.

[0053] Given the initial value of the virtual resistance of the resonance suppression controller , through the characteristic subharmonic amplitude The change in the value of the virtual resistance is used to determine whether the resonance is suppressed. If the resonance is suppressed, no adjustment is required. If the resonance is not suppressed, the value of the virtual resistance needs to be determined by the characteristic subharmonic amplitude. The virtual impedance adaptive adjustment controller is shown as follows:

[0054] (7)

[0055] Where, represents the proportional coefficient of the virtual impedance closed-loop regulator, represents the integral coefficient of the virtual impedance closed-loop regulator, It is the change in the amplitude of each harmonic voltage at the grid connection point.

[0056] Step S207: Determine the output voltage reference of the converter based on the fundamental wave, harmonics, and voltage reference obtained by the controller in steps S203 and S205, and determine the modulation wave voltage of the converter through the voltage loop proportional resonant controller and the current loop proportional controller.

[0057] Optionally, the implementation of step S207 is that the controller is based on the fundamental voltage reference and harmonic voltage reference , through the reference voltage generator, the voltage parameter of the reactive power compensation system power converter is obtained ;

[0058] (8)

[0059] The controller is used to control , through the divided-band proportional resonant controller , get the current reference output of the power conversion circuit :

[0060] (9)

[0061] Where, represents the proportional coefficient of the proportional resonant controller, Represents the resonance coefficient of the controller. represents the bandwidth at the center frequency of the controller, represents the fundamental angular frequency of the system, Indicates the harmonic order, which can be 5, 7, 9, 11, or 13;

[0062] The controller is also used to control the output current of the power conversion circuit , through the ratio and voltage feedforward controller, the modulation wave of the power conversion circuit is obtained ;

[0063] (10)

[0064] Where, Indicates the proportional coefficient of the current loop proportional controller.

[0065] Step S208: After obtaining the modulated wave voltage of the reactive power compensation system controller After that, the duty cycle signal of the switch tube is obtained by comparing it with the triangle wave according to the sinusoidal pulse width modulation, thereby controlling the on and off of the converter switch tube, realizing the rapid response of the hybrid active filter to the system harmonic current, and compensating the reactive capacitor to generate system damping.

[0066] Figure 5 Figure 2 shows the actual simulation waveforms of the reactive power compensation system under grid distortion conditions when the proposed resonance suppression method is not used. From top to bottom, they are the grid voltage, the public grid connection point voltage, and the grid-side current. It can be seen that the grid voltage is distorted, with a THD of 7.83%. When the resonance suppression strategy is not used, the system has seven serious resonances, the grid connection point voltage THD is 65.14%, and the grid-side current is severely distorted, with a THD of 110.62%. Figure 6The waveforms of the grid-connected point voltage and grid-side current when the reactive power compensation system is stable after adopting the virtual impedance controller are shown. It can be seen that the THD of the grid-connected point voltage is reduced to 4.04%, close to the grid voltage, and the THD of the grid-side current is reduced to 3.52%, and the resonance is completely suppressed. In summary, the adaptive resonance suppression device and control method of the medium-voltage passive reactive power compensation device proposed in the present invention are feasible. This control scheme can achieve the function of accurately compensating harmonics and reactive power, and at the same time has the function of resonance suppression, which increases the stability of the system, prevents the occurrence of resonance, and realizes the coordination of the parallel capacitor branch switching logic and the converter.

[0067] 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 solutions 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, those skilled in the art may make various specific modifications based on the teachings of the present invention, all of which fall within the scope of protection of the present invention.

[0068] It should be understood that the size of the serial numbers of the steps in the above embodiments does not 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 embodiments of the present invention.

[0069] Example modules such as Figure 8 As shown, a control method for adaptive resonance suppression of a medium voltage passive reactive compensation device includes:

[0070] A first obtaining module 801 is configured to obtain a public grid voltage, a converter output current, and a load current according to the sensor;

[0071] A first determining module 802 is configured to determine the switching capacity of the reactive compensation capacitor and the power data of the converter compensation according to the power dispatch information of the power grid;

[0072] A second determining module 803 is configured to determine a power conversion circuit output fundamental voltage reference based on the switching capacitor current obtained by the controller and the measured DC bus voltage;

[0073] The second obtaining module 804 is configured to obtain a harmonic current reference required to be compensated by the reactive power compensation system through the harmonic extraction controller according to the output current and the load current measured by the controller;

[0074] A third determination module 805 is configured to determine a harmonic voltage reference output by a power conversion circuit by applying the frequency-divided virtual impedance and a virtual negative capacitance having an opposite impedance to the equivalent impedance of the switched capacitors through the reactive compensation system resonance suppression controller according to the harmonic current reference obtained by the controller;

[0075] A fourth determining module 806 is configured to determine the value of the sub-frequency band virtual impedance through the virtual impedance adaptive regulator according to the common grid connection point voltage received by the controller;

[0076] A fifth determination module 807 is configured to determine the output voltage reference of the converter based on the fundamental wave, harmonics, and voltage reference obtained by the third and fifth modules of the controller step, and determine the modulation wave voltage of the converter through a voltage loop proportional resonant controller and a current loop proportional controller;

[0077] The third obtaining module 808 is configured to obtain a switching signal of the power converter through sinusoidal pulse width modulation according to the modulation wave voltage determined by the seventh determining module 807 .

[0078] Figure 9 3 is a schematic diagram of a control method for adaptive resonance suppression of a medium-voltage passive reactive compensation device provided by an embodiment of the present invention.

[0079] The schematic diagram of the adaptive resonance suppression device of the reactive compensation device is as follows Figure 9 As shown, the system includes: a power conversion circuit 901, a controller 902, a memory 903, and a computer program 904 stored in the memory 903 and capable of running on the controller 902. When the controller 902 executes the computer program 904, the steps in the above-mentioned resonance suppression method embodiment are implemented, for example Figure 2 Alternatively, when the controller 802 executes the computer program 804, the power of each module / unit in the above embodiment is realized, for example Figure 8 The functions of modules 801 to 808 are shown.

[0080] Exemplarily, the computer program 904 can be divided into one or more modules / units, which are stored in the memory 903 and executed by the controller 902 to implement the embodiments of the present invention. The one or more modules / units can be a series of computer program instruction segments capable of performing specific functions, which are used to describe the execution process of the computer program 904 in the reactive power and harmonic compensation system device 9. For example, the computer program 904 can be divided into a first acquisition module, a first determination module, a second determination module, a second acquisition module, a third determination module, a fourth determination module, a fifth determination module, and a third acquisition module. The functions of each module are as follows:

[0081] A first obtaining module is used to obtain a public grid voltage, a converter output current and a load current according to the sensor;

[0082] The first determination module is used to determine the switching capacity of the reactive compensation capacitor and the power data of the converter compensation according to the power dispatch information of the power grid;

[0083] A second determination module is used to determine the output fundamental voltage reference of the power conversion circuit based on the switching capacitor current obtained by the controller and the measured DC bus voltage;

[0084] A second obtaining module is configured to receive the measured output current and load current according to the controller, and obtain a harmonic current reference required to be compensated by the reactive power compensation system through the harmonic extraction controller;

[0085] A third determination module is configured to obtain a harmonic current reference from the controller, apply the frequency-divided virtual impedance through the reactive compensation system resonance suppression controller, and simultaneously apply a virtual negative capacitance having the same value as the equivalent impedance of the switched capacitors, to determine a harmonic voltage reference output by the power conversion circuit;

[0086] a fourth determining module, configured to determine the value of the frequency-band virtual resistance through the virtual impedance adaptive regulator according to the common grid connection point voltage received by the controller;

[0087] a fifth determination module, configured to determine an output voltage reference of the converter based on the fundamental wave, harmonics, and voltage reference obtained by the third and fifth modules of the controller step, and determine a modulation wave voltage of the converter through a voltage loop proportional resonant controller and a current loop proportional controller;

[0088] The third obtaining module is used to obtain the switching signal of the power converter through sinusoidal pulse width modulation according to the modulation wave voltage determined by the seventh determining module 807.

[0089] The control method for adaptive resonance suppression of the medium voltage passive reactive compensation device may include, but is not limited to, a power conversion circuit 901, a controller 902, and a memory 903. It will be understood by those skilled in the art that Figure 8 It is only an example of the reactive power and harmonic compensation system device 8 and does not constitute a limitation on the reactive power and harmonic compensation system device. It may include more or fewer components than shown in the figure, or a combination of certain components, or different components. For example, the life assessment terminal device of the power transformer may also include input and output devices, network access equipment, buses, etc.

[0090] 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. The general-purpose processor may be a microprocessor or any conventional processor.

[0091] The memory 803 can be an internal storage unit of the adaptive resonance suppression device 9 of the medium-voltage passive reactive power compensation device, such as an external memory circuit of the reactive power compensation system device 9. Examples include a plug-in hard drive, a Smart Media Card (SMC), a Secure Digital (SD) card, a flash memory card, etc., equipped on the hybrid compensation system device 9. Furthermore, the memory 803 can include both the internal storage unit of the reactive power compensation system device 9 and an external storage device. The memory 893 is used to store the computer program and other programs and data required by the reactive power and harmonic compensation system device. The memory 903 can also be used to temporarily store data that has been output or is about to be output.

[0092] Those skilled in the art can clearly understand that, for the convenience and brevity of description, only the division of the above-mentioned functional units and modules is used as an example for illustration. In actual applications, the above-mentioned functions can be distributed and 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 into one processing unit, or each unit can exist physically alone, or two or more units can be integrated into 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, and will not be repeated here.

[0093] In the above embodiments, the description of each embodiment has its own focus. For parts that are not described or recorded in detail in a certain embodiment, reference can be made to the relevant description of other embodiments.

[0094] 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. Professionals and technicians can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of the present invention.

[0095] 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 merely illustrative. For example, the division of the modules or units is merely a logical function division. In actual implementation, there may be other division methods, 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.

[0096] The units described as separate components may or may not be physically separate, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed across multiple network units. Some of these units may be selected according to actual needs to achieve the purpose of this embodiment.

[0097] In addition, the functional units in the various embodiments of the present invention may be integrated into a single processing unit, each unit may exist physically separately, or two or more units may be integrated into a single unit. The aforementioned integrated units may be implemented in the form of hardware or software functional units.

[0098] If the integrated module / unit is implemented as a software functional unit and sold or used as a standalone product, it can be stored in a computer-readable storage medium. Based on this understanding, the present invention can implement all or part of the process steps in the above-mentioned method embodiments by using a computer program to instruct the relevant hardware. The computer program can be stored in a computer-readable storage medium. When executed by a processor, the computer program can implement the steps of each of the above-mentioned method embodiments. The computer program includes computer program code, which can be in source code form, object code form, executable file, or some intermediate form. The computer-readable medium can include: any entity or device capable of carrying the computer program code, recording medium, USB flash drive, mobile hard drive, magnetic disk, optical disk, computer memory, read-only memory (ROM), random access memory (RAM), electric carrier signal, telecommunication signal, and software distribution medium. It should be noted that the content of the computer-readable medium can be appropriately increased or decreased based on the requirements of legislation and patent practice in a jurisdiction. For example, in some jurisdictions, based on legislation and patent practice, computer-readable media does not include electric carrier signals and telecommunication signals.

[0099] 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 they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present invention, and should all be included in the scope of protection of the present invention.

Claims

1. A control method for adaptive resonance suppression of a medium voltage passive reactive power compensation device, characterized by: The medium-voltage passive reactive power compensation device includes: a controller, a power conversion circuit, a filter, a current sensor, a voltage sensor, and a switching capacitor; the first end of the power conversion circuit is connected to the output end of the controller, a first voltage sensor is installed on the DC side of the power conversion circuit, the third end is connected to the first end of the first current sensor, the second end of the first current sensor is connected to the first end of the filter, a second voltage sensor is installed at the filter capacitor, the second end of the filter is connected to the first end of the switching capacitor, the second end of the switching capacitor is connected to the first end of the second current sensor, and the second end of the second current sensor is connected to the AC power grid; a second voltage sensor is installed at the common connection point between the medium-voltage passive reactive power compensation device and the AC power grid, and a local load is connected between the first end of the third current sensor and the common connection point; The current sensor and the voltage sensor measure the output current of the power conversion circuit , switching capacitor current , measure the filter voltage , measure the DC bus voltage ; The controller is used to receive grid power dispatch information, and the grid power dispatch information is used to indicate the reactive power reference that needs to be compensated by the medium voltage passive reactive compensation device. The controller distributes reactive power based on the reactive power reference obtained and determines the number of groups of capacitors that need to be switched on. ; The controller is based on the obtained switching capacitor current , combined with the measured DC bus voltage Determine the fundamental voltage reference output of the power conversion circuit ; The controller is also used to receive the measured switching capacitor current , through the harmonic extractor, the harmonic current reference required for compensation of the medium voltage passive reactive compensation device is obtained ; The controller obtains the harmonic current reference , through the resonance suppression controller, the frequency-dividing virtual resistance is applied, and at the same time, the virtual negative capacitance with the same equivalent impedance as the number of switched capacitors is applied to determine the output harmonic voltage reference of the power conversion circuit ; The controller sets the initial value of the virtual resistance of the frequency division, based on the obtained common grid point voltage , the characteristic subharmonic voltage amplitude is obtained through the harmonic extractor , through the virtual impedance adaptive adjustment controller, the virtual impedance value of the frequency band is output; The controller is based on the fundamental voltage reference and harmonic voltage reference , through the reference voltage generator, the voltage reference of the power conversion circuit is obtained ; and controlled by a frequency-band proportional resonant controller , get the power output current reference The controller is also used to control the output current of the power conversion circuit , the modulation wave of the power conversion circuit is obtained through the proportional controller ; The controller is based on the obtained modulation wave , after coordinate transformation and then passing through a sinusoidal pulse width modulator, the control signal of the power conversion circuit is obtained.

2. The method for controlling adaptive resonance suppression of a medium voltage passive reactive compensation device according to claim 1, characterized in that: The controller is based on obtaining reactive power capacity , combined with the measured public grid point voltage , determine the number of capacitor groups to be switched ; including the following steps: The reactive power capacity obtained by the controller , combined with the measured public grid point voltage , determine the number of switched capacitor groups , as shown in the following formula (1): (1) In the formula represents the fundamental angular frequency of the system, Indicates the capacity of the reactive capacitor.

3. The method for controlling adaptive resonance suppression of a medium voltage passive reactive compensation device according to claim 1, characterized in that: The controller is based on the obtained switching capacitor current , combined with the measured DC bus voltage , determine the fundamental voltage reference output of the power conversion circuit ; comprising the following steps: the controller receives the switching capacitor current obtained and the DC bus voltage of the power converter , using a phase-locked loop to control the switching capacitor current Phase lock to get phase angle and the DC voltage and DC bus voltage Make the difference through the controller Get the fundamental voltage amplitude , combining the phase angle θ with the amplitude to obtain the fundamental voltage reference : (2) （3） In the formula is the proportional-integral controller proportional coefficient, is the integration parameter.

4. The method for controlling adaptive resonance suppression of a medium voltage passive reactive compensation device according to claim 1, characterized in that: The controller is further configured to receive the measured output current , through the harmonic extraction controller, the harmonic current reference that the power conversion circuit needs to compensate is obtained ; comprising the steps of: the controller receives the measured , after coordinate transformation, we get , using a harmonic extractor Extracting harmonic currents , as shown in formula (4): （4） Where, represents the bandwidth at the center frequency of the controller, represents the fundamental angular frequency of the system, Indicates the harmonic order, take 5, 7, 9, 11, 13.

5. The method for controlling adaptive resonance suppression of a medium voltage passive reactive compensation device according to claim 1, characterized in that: The following steps are involved: The controller obtains the harmonic current reference , through the resonance suppression controller, the frequency-dividing virtual resistance is applied, and at the same time, a negative virtual capacitance with the same equivalent impedance as the switched capacitor is applied to determine the power conversion circuit output harmonic voltage reference ; (5) In the formula is the sum of virtual resistance and virtual negative capacitance, is the virtual resistance of each frequency sub-harmonic.

6. The method for controlling adaptive resonance suppression of a medium voltage passive reactive compensation device according to claim 1, characterized in that: The controller obtains the public grid connection point voltage , the characteristic subharmonic amplitude component is obtained by the harmonic extractor , as shown below: (6) Where, is the characteristic order of harmonic voltage, is the amplitude of the characteristic hth harmonic component of the grid connection point voltage; Given the initial value of the virtual impedance of the resonance suppression controller , through the characteristic subharmonic amplitude The change in is used to determine whether the resonance is suppressed. If the resonance is suppressed, no adjustment is required. If the resonance is not suppressed, the value of the virtual impedance needs to be determined by the characteristic subharmonic amplitude. The virtual impedance adaptive adjustment controller is shown as follows: (7) Where, represents the proportional coefficient of the virtual impedance closed-loop regulator, represents the integral coefficient of the virtual impedance closed-loop regulator, It is the change in the amplitude of each harmonic voltage at the grid connection point.

7. The method for controlling adaptive resonance suppression of a medium voltage passive reactive compensation device according to claim 1, characterized in that: The following steps are involved: The controller is based on the fundamental voltage reference and harmonic voltage reference , through the reference voltage generator, the voltage reference of the power conversion circuit is obtained ; (8) The controller is used to control , through the frequency-band proportional resonant controller , get the current reference output of the power conversion circuit : (9) Where, represents the proportional coefficient of the proportional resonant controller, represents the resonance coefficient of the controller, represents the bandwidth at the center frequency of the controller, represents the fundamental angular frequency of the system, Indicates the harmonic order, which can be 5, 7, 9, 11, or 13; The controller is also used to control the output current of the power conversion circuit , obtained by coordinate transformation , and then the modulation wave of the power conversion circuit is obtained by the ratio and voltage feedforward controller ; (10) Where, Indicates the proportional coefficient of the current loop proportional controller.

8. The method for controlling adaptive resonance suppression of a medium voltage passive reactive compensation device according to claim 1, characterized in that: The following steps are involved: After obtaining the modulation wave voltage of the controller After that, we get Through the sinusoidal pulse width modulation generator, the duty cycle signal of the switch tube is obtained, thereby controlling the opening and closing of the converter switch tube to achieve reactive power compensation and resonance suppression of the medium voltage passive reactive power compensation device.

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