Self-adaptive resonance suppression device of medium-voltage passive reactive power compensation device and control method

Abstract

The invention is suitable for the field of power quality of a power distribution network, particularly relates to a control method of a converter device in a compensation device, can be applied to a reactive compensation converter in a power distribution network and other scenes, and provides a self-adaptive resonance suppression method of a reactive and harmonic compensation system in the power distribution network. The compensation device comprises a series capacitor and a converter, the series capacitor is used for compensating reactive power, the converter is used for compensating harmonic current, and the problem of serious resonance of the system caused by overlarge input capacitor can be solved by connecting a frequency-division virtual negative capacitor at a grid-connected point of the compensation device in parallel. And meanwhile, the applied sub-band virtual impedance is adjusted through the closed-loop controller, and the converter is adaptively adjusted to output equivalent impedance, so that the shunt capacitor branch switching logic and the converter can be coordinated, and the system resonance can be effectively suppressed under the multi-scene working conditions that the power grid impedance is unknown and the input capacity of the capacitor is changed.

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 power and harmonic hybrid compensation systems in distribution networks and other scenarios. It is a control strategy for suppressing reactive power compensation systems and grid impedance resonance using frequency-band virtual impedance. Background Art

[0002] With the rapid development of new energy, a large number of distributed power sources have been connected to the grid, which has brought power quality problems such as harmonic pollution to the power system. Compared with traditional passive filters, active power filters have the advantages of being able to achieve dynamic compensation of harmonics and reactive power at the same time and fast response. Therefore, the use of active power filters has become an important trend in harmonic compensation.

[0003] When reactive load appears in the power grid, the active power filter can use its remaining capacity to actively inject reactive power into the system to achieve reactive compensation. However, large-capacity active power filters are generally expensive. When the reactive load in the power grid is large, small-capacity active power filters cannot simultaneously perform harmonic compensation and inject reactive power. Therefore, some manufacturers currently use hybrid compensation systems to compensate for system reactive power and harmonic current, which can reduce the cost of unit reactive capacity. Traditional hybrid compensation devices often separate active filters and capacitors, and the controller is configured separately, which cannot adapt to the current weak power grid scenario. To address this problem, some manufacturers currently combine active filters with capacitors to form a hybrid compensation system, and perform coordinated compensation and control. When the system uses capacitors for reactive compensation, the large-capacity reactive compensation capacitors are easily interacted with the impedance of the power grid, thereby generating resonance. After resonance, a large current harmonic component will be generated between the reactive compensation capacitor group, the nonlinear load and the power grid, which may cause damage to the power 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 impedance of the power grid to change, the probability of resonance and the peak frequency of resonance are uncertain. In this case, the traditional method of 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 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 objective of the present invention is achieved through the following technical solutions: According to the current sensor, the output current of the power conversion circuit is measured , switching capacitor current , load current , according to the voltage sensor, the filter voltage is measured , measure the DC bus voltage ; The controller is used to receive power grid dispatch information, and the power grid 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. ; The controller is based on the obtained switched capacitor current , combined with the measured DC bus voltage , determine the fundamental voltage reference of the power conversion circuit output ; The controller is also used to receive the measured output current , load current , through the harmonic extraction controller, the harmonic current reference required for compensation of the reactive power compensation system is obtained ; The controller obtains the harmonic current reference , through the reactive compensation system resonance suppression controller, the frequency-dividing virtual resistance is applied, and at the same time, a negative virtual capacitor with the same equivalent impedance as the switched capacitor is applied to determine the output harmonic voltage reference of the power conversion circuit ; The controller sets the initial value of virtual resistance at each frequency based on the obtained common grid connection point voltage , the characteristic subharmonic voltage amplitude is obtained by the harmonic extractor controller , the reactive power compensation device executes a frequency-band virtual resistance and a virtual negative capacitance adaptive adjustment controller to adaptively adjust the frequency-band virtual impedance value output by the reactive power compensation device; The controller obtains the fundamental voltage reference and harmonic voltage reference , through the reference voltage generator, the voltage reference of the power converter of the reactive power compensation system is obtained ; and controlled by the frequency-dividing proportional resonant controller , and obtain a power output current reference. The controller is also used to control the output current of the power conversion circuit , through the proportional controller, the modulation wave of the power conversion circuit is obtained ; The controller is based on the obtained modulation wave , through the sinusoidal pulse width modulator, a control signal of the power conversion circuit of the reactive power compensation system is obtained. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Figure 1 The electrical connection structure of the medium voltage passive reactive power compensation device provided by the embodiment of the present invention; Figure 2 yes Figure 1 A schematic diagram of an implementation flow of a control method for adaptive resonance suppression of the device shown; Figure 3 yes Figure 1 The harmonic voltage and fundamental voltage of the reactive power compensation device and the voltage-current dual-loop controller block diagram are shown; Figure 4 yes Figure 1 The adaptive virtual resistance adjustment control block diagram of the reactive power compensation device shown; Figure 5 yes Figure 1 The impedance adaptive adjustment algorithm flow chart of the reactive compensation device shown; Figure 6 This is a simulation operation effect diagram of the traditional reactive power compensation system under independent control; Figure 7 yes Figure 1 The simulation operation effect diagram of the series resonance suppression method of the reactive power compensation system device shown; Figure 8 It is a module schematic diagram of an embodiment of a resonance suppression control method for a reactive compensation device provided by an embodiment of the present invention; Fig. 9 It is a schematic diagram of a reactive power compensation device provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0008] In order to make the purpose, technical scheme and advantages of the present application clearer, the present application will be further described in detail below in conjunction with the accompanying drawings. The specific operation method in the method embodiment can also be applied to the device embodiment or the system embodiment. It should be noted that in the description of the present application, "at least one" refers to one or more, wherein multiple refers to two or more. In view of this, "multiple" can also be understood as "at least two" in the embodiment of the present application. "And / or" describes the association relationship of the associated objects, indicating that there can be three relationships. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / ", unless otherwise specified, generally indicates that the front and back associated objects are in an "or" relationship. In addition, it should be understood that in the description of the present application, the words "first", "second" and the like are only used to distinguish the purpose of description, and cannot be understood as indicating or implying relative importance, nor can they be understood as indicating or implying order. The present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0009] A control method for adaptive resonance suppression of a medium voltage passive reactive compensation device proposed by the present invention comprises the following steps: Please refer to Figure 1 , an electrical connection structure of an adaptive resonance suppression device of a medium voltage passive reactive compensation device, comprising: Build as Figure 1 The circuit model includes a controller, a power converter, an LC filter, a current sensor, a voltage sensor and a switching capacitor; one end of the converter is connected to the controller, and the other end is connected to the LC filter through a current sensor. The filter is connected in series with the switching capacitor, and the nonlinear local load is connected in parallel with the switching capacitor to a public grid-connected point. At the same time, a voltage sensor is installed at the grid-connected point, and a current sensor is connected at the local load; 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: Step S201: Measure the output current of the power conversion circuit using the current sensor , switching capacitor current , load current , according to the voltage sensor, the filter voltage is measured , measure the DC bus voltage ; Step S202: The controller is used to receive power grid dispatch information, and the power grid 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. ; Optionally, step S202 is implemented by: , combined with the measured common grid-connected 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.

[0010] Step S203: The controller obtains the switching capacitor current based on the , combined with the measured DC bus voltage , determine the fundamental voltage reference of the power conversion circuit output ; Please refer to Figure 3 , a block diagram of a harmonic voltage and fundamental voltage controller for a reactive power compensation system provided in an embodiment; 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 switch the 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: (2) (3) In the formula is the proportional-integral controller proportional coefficient, is the integration parameter.

[0011] Step S204: The controller is further configured to receive the measured output current , load current , through the harmonic extraction controller, the harmonic current reference required to be compensated by the hybrid compensation system is obtained ; Optionally, step S204 is implemented as follows: The controller receives the measured and , after coordinate transformation, we get , using a harmonic extractor Extracting harmonic current , as shown in formula (4): (4) In the formula, 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 5th, 7th, 9th, 11th, or 13th.

[0012] Step S205: Obtaining harmonic current reference according to the controller , through the reactive compensation system resonance suppression controller, the frequency-divided virtual impedance is applied, and at the same time, a negative virtual impedance opposite to the equivalent impedance is applied to determine the output harmonic voltage reference of the power conversion circuit ; Optionally, step S205 is implemented by the controller obtaining a harmonic current reference , through the reactive compensation system resonance suppression controller, the frequency-divided virtual resistance is applied, and at the same time, a virtual negative capacitance with the same equivalent impedance as the switched capacitor is applied to determine the output harmonic voltage reference of the power conversion circuit ; The following steps are included: (5) In the formula is the sum of the virtual resistance and the virtual negative capacitance impedance, is the virtual impedance of each harmonic.

[0013] Step S206: The controller sets the initial value of the virtual resistance at each frequency based on the obtained common grid connection point voltage , the characteristic subharmonic voltage amplitude is obtained by the harmonic extractor controller , the reactive power compensation device executes a frequency-band virtual resistance and a virtual negative capacitance adaptive adjustment controller to adaptively adjust the frequency-band virtual impedance value output by the reactive power compensation device; Please refer to Figure 5 , which is a flow chart of an impedance adaptive adjustment algorithm for a reactive compensation system provided by an embodiment of the present invention; 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: (6) In the formula, is the characteristic order of harmonic voltage, It is the amplitude of the characteristic h-order harmonic component of the grid-connected point voltage.

[0014] Given the initial value of virtual resistance R of the resonance suppression controller v0,h , 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: (7) In the formula, 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.

[0015] Step S207: Determine the output voltage reference of the converter according to 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.

[0016] Optionally, step S207 is implemented by the controller based on the obtained fundamental voltage reference and harmonic voltage reference , through the reference voltage generator, the voltage reference of the power converter of the reactive power compensation system is obtained. ; (8) The controller is used to control , through the split-band proportional resonant controller , get the current reference output of the power conversion circuit : i L 1 ref = G V ( s ) ⋅ ( v C 1 ( αβ ) ref − v C 1 ( αβ ) ) = [ k pv + ∑ h 2 k rv,h ω cut s s 2 + 2 ω cut s + （ h ω 0 ) 2 ] ⋅ ( v C 1 ( αβ ) ref − v C 1 ( αβ ) ) (9) In the formula, 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 , through the ratio and voltage feedforward controller, the modulation wave of the power conversion circuit is obtained ; (10) In the formula, Represents the proportional coefficient of the current loop proportional controller.

[0017] Step S208: After obtaining the modulation wave voltage of the reactive power compensation system controller After that, the sine pulse width modulation is compared with the triangle wave to obtain the duty cycle signal of the switch tube, so as to control the opening and closing of the converter switch tube, realize the rapid response of the hybrid active filter to the system harmonic current, and compensate the reactive capacitor to generate system damping at the same time.

[0018] Figure 5 The figure is the actual simulation waveform of the reactive power compensation system under the condition of grid distortion when the proposed resonance suppression method is not adopted. 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, and the THD is 7.83%. When the resonance suppression strategy is not adopted, the system has 7 serious resonances, the grid connection point voltage THD is 65.14%, and the grid-side current is seriously distorted, with a THD of 110.62%. Figure 6 The waveforms of the grid-connected point voltage and grid-side current when the system is stable after the reactive power compensation system adopts a virtual impedance controller are shown. It can be seen that the grid-connected point voltage THD is reduced to 4.04%, close to the grid voltage, the grid-side current THD is reduced to 3.52%, and the resonance is completely suppressed. In summary, the adaptive resonance suppression device and control method of a medium-voltage passive reactive compensation device proposed in the present invention are feasible. The control scheme can realize the function of accurate compensation of harmonics and reactive power, and 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.

[0019] 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.

[0020] 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.

[0021] Example module such as Figure 8 As shown, a control method for adaptive resonance suppression of a medium voltage passive reactive compensation device comprises: A first obtaining module 801 is used to obtain a common grid voltage, a converter output current and a load current according to the sensor; The first determination module 802 is used to determine the switching capacity of the reactive power compensation capacitor and the power data of the converter compensation according to the power dispatch information of the power grid; A second determination module 803 is used to determine the output fundamental voltage reference of the power conversion circuit according to the switching capacitor current obtained by the controller and the measured DC bus voltage; The second obtaining module 804 is used to obtain the 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; The third determination module 805 is used to obtain the harmonic current reference according to the controller, apply the frequency-divided virtual impedance through the reactive compensation system resonance suppression controller, and simultaneously apply a virtual negative capacitance opposite to the equivalent impedance of the switched capacitors, to determine the output harmonic voltage reference of the power conversion circuit; A fourth determination module 806 is used 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; A fifth determination module 807, used to determine the output voltage reference of the converter according to the fundamental wave, harmonic wave and voltage reference obtained by the third and fifth modules of the controller step, and determine the modulation wave voltage of the converter through the voltage loop proportional resonant controller and the current loop proportional controller; The third obtaining module 808 is used 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.

[0022] Fig. 9 It 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.

[0023] The schematic diagram of the adaptive resonance suppression device of the reactive power compensation device is as follows: Fig. 9 As shown, it includes: a power conversion circuit 901, a controller 902, a memory 903, and a computer program 904 stored in the memory 903 and executable 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.

[0024] Exemplarily, the computer program 904 may be divided into one or more modules / units, which are stored in the memory 903 and executed by the controller 902 to complete the embodiment of the present invention. The one or more modules / units may be a series of computer program instruction segments capable of completing 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 may 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, and the functions of each module are as follows: A first obtaining module, used for obtaining a public grid-connected voltage, a converter output current and a load current according to the sensor; The first determination module is used to determine the switching capacity of the reactive power compensation capacitor and the power data of the converter compensation according to the power dispatching information of the power grid; A second determination module is used to determine the output fundamental voltage reference of the power conversion circuit according to the switching capacitor current obtained by the controller and the DC bus voltage measured; A second obtaining module is used for receiving the measured output current and load current according to the controller, and obtaining the harmonic current reference required to be compensated by the reactive power compensation system through the harmonic extraction controller; A third determination module is used to obtain a harmonic current reference according to the controller, apply the frequency-divided virtual impedance through the reactive compensation system resonance suppression controller, and simultaneously apply a virtual negative capacitance that is the same as the equivalent impedance of the switched capacitors, to determine the output harmonic voltage reference of the power conversion circuit; A fourth determination module, configured to determine the value of the frequency-dividing virtual resistance through the virtual impedance adaptive regulator according to the common grid-connected point voltage received by the controller; A fifth determination module, used to determine the output voltage reference of the converter according to the fundamental wave, harmonic wave and voltage reference obtained by the third module and the fifth module of the controller step, and determine the modulation wave voltage of the converter through the voltage loop proportional resonant controller and the current loop proportional controller; 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.

[0025] 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. Those skilled in the art will appreciate that Figure 8It is only an example of the reactive power and harmonic compensation system device 8 and does not constitute a limitation of 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.

[0026] 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 any conventional processor, etc.

[0027] The memory 803 may be an internal storage unit of the adaptive resonance suppression device 9 of the medium voltage passive reactive compensation device, such as an external memory circuit of the reactive compensation system device 9. For example, a plug-in hard disk, a smart media card (SMC), a secure digital (SD) card, a flash card, etc., equipped on the hybrid compensation system device 9. Further, the memory 803 may also include both an internal storage unit of the reactive 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 and harmonic compensation system device. The memory 903 may be used to temporarily store data that has been output or is to be output.

[0028] 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.

[0029] 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.

[0030] 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.

[0031] 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.

[0032] 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.

[0033] 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.

[0034] 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. When the computer program is executed by the processor, the steps of the above-mentioned various method embodiments can be implemented. 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.

[0035] 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. An adaptive resonance suppression device for a medium voltage passive reactive compensation device, characterized in that: include: The reactive power compensation device comprises: 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 voltage sensor is installed on the DC side of the power conversion circuit, the third end of the power conversion circuit is connected to the first end of the current sensor, the second end of the current sensor is connected to the first end of the filter, a voltage sensor is installed at the capacitor of the filter, 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 current sensor, the second end of the current sensor is connected to the AC power grid, the connection point between the reactive power compensation system and the AC power grid is a public grid connection point, a voltage sensor is installed at the public grid connection point, a local load is connected to the first end of the current sensor, and the second end of the current sensor is connected to the public grid connection point.

2. A control method for adaptive resonance suppression of a medium voltage passive reactive compensation device, according to the adaptive resonance suppression device of claim 1, characterized in that: The current sensor and the voltage sensor measure the output current of the power conversion circuit. , switching capacitor current , Load current , measure the filter voltage , measure the DC bus voltage ; The controller is used to receive power grid dispatch information, and the power grid dispatch information is used to indicate the reactive power reference that the reactive power compensation device 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. ; The controller is based on the obtained switched capacitor current , combined with the measured DC bus voltage Determine the fundamental voltage reference of the power conversion circuit output ; The controller is also used to receive the measured output current , Load current , through the harmonic extraction controller, the harmonic current reference that the reactive power compensation device needs to compensate is obtained ; The controller obtains the harmonic current reference , through the compensation device resonance suppression controller, apply the frequency-divided virtual resistance, and at the same time apply the virtual negative capacitance with the equivalent impedance of the switched capacitors 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 connection point voltage , the characteristic subharmonic voltage amplitude is obtained through the harmonic extractor controller , the reactive power compensation device executes a frequency-band virtual resistance and a virtual negative capacitance adaptive adjustment controller to adaptively adjust the frequency-band virtual impedance value output by the reactive power compensation device; The controller is based on the fundamental voltage reference and harmonic voltage reference , through the reference voltage generator, the voltage reference of the power converter is obtained ; And controlled by a frequency-divided 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 , through a sinusoidal pulse width modulator, a control signal of the power conversion circuit is obtained.

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

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

5. The control method for adaptive resonance suppression of a medium voltage passive reactive compensation device according to claim 2, characterized in that: The controller is also used to receive the measured output current , load current , through the harmonic extraction controller, the harmonic current reference required for compensation of the reactive power compensation system is obtained ; comprising the following steps: the controller receives the measured and , after coordinate transformation, we get , using a harmonic extractor Extracting harmonic current , as shown in formula (4): (4) In the formula, 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 5th, 7th, 9th, 11th, or 13th.

6. The control method for adaptive resonance suppression of a medium voltage passive reactive compensation device according to claim 2, characterized in that: The controller obtains the harmonic current reference , through the reactive compensation system resonance suppression controller, the frequency-divided 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 ; including the following steps: (5) In the formula is the sum of the virtual resistance and the virtual negative capacitance, It is the virtual resistance of each frequency sub-harmonic.

7. The control method for adaptive resonance suppression of a medium voltage passive reactive compensation device according to claim 2, 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) In the formula, 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 virtual impedance R of the resonance suppression controller v0,h , 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) In the formula, 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.

8. The control method for adaptive resonance suppression of a medium voltage passive reactive compensation device according to claim 2, 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 converter of the reactive power compensation system is obtained. ; (8) The controller is used to control , through the frequency-divided proportional resonant controller , get the current reference output of the power conversion circuit : (9) In the formula, 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 5th, 7th, 9th, 11th, or 13th; 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 ; (10) In the formula, Represents the proportional coefficient of the current loop proportional controller.

9. The control method for adaptive resonance suppression of a medium voltage passive reactive compensation device according to claim 2, characterized in that: The following steps are involved: After obtaining the modulation wave voltage of the controller After the inverse coordinate transformation, 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 reactive power compensation system.

Images