阅读说明：本技术 变换器的谐振抑制方法、模块以及装置 (Resonance suppression method, module and device for converter ) 是由 周党生 陈佳明 于 2021-06-28 设计创作，主要内容包括：本申请公开一种变换器的谐振抑制方法、模块以及装置,所述方法包括：获取变换器交流侧的电容电流分量；将所述电容电流分量通过第一增益环节和第一相位补偿环节进行调节后,得到第一控制作用量；将所述第一控制作用量叠加到变换器的控制器输出中,以形成最终的控制作用量。本申请通过在电容电流前馈控制支路中引入相位补偿器,在不增加系统成本的基础上,避免了现有谐振抑制方法因数字控制系统延时造成的谐振阻尼能力受限的问题,降低了变换器在宽范围电网阻抗下运行的谐振风险,增强了其在不同强度电网下的稳定运行能力。(The application discloses a resonance suppression method, a module and a device of a converter, wherein the method comprises the following steps: acquiring a capacitance current component of an alternating current side of the converter; adjusting the capacitance current component through a first gain link and a first phase compensation link to obtain a first control action quantity; adding the first control action quantity to the controller output of the converter to form a final control action quantity. According to the method, the phase compensator is introduced into the capacitance current feedforward control branch, on the basis of not increasing the system cost, the problem that the resonance damping capacity of the existing resonance suppression method is limited due to time delay of a digital control system is solved, the resonance risk of the converter operating under the wide-range power grid impedance is reduced, and the stable operation capacity of the converter under the power grids with different intensities is enhanced.)

1. A method of suppressing resonance in a converter, the method comprising:

acquiring a capacitance current component of an alternating current side of the converter;

adjusting the capacitance current component through a first gain link and a first phase compensation link to obtain a first control action quantity;

adding the first control action quantity to the controller output of the converter to form a final control action quantity.

2. The method of claim 1, further comprising:

acquiring a capacitance voltage component of an alternating current side of the converter;

adjusting the capacitance voltage component through a second gain link and a second phase compensation link to obtain a second control action quantity;

adding the first control action quantity and the second control action quantity to the controller output of the converter to form a final control action quantity.

3. A method according to claim 1 or 2, characterized in that the first gain element comprises a pure proportional element and/or a functional module with filtering properties.

4. The method according to claim 2, wherein the second gain element comprises a pure proportional element and/or a functional module with a filter characteristic.

5. A method as claimed in claim 1 or 2, characterized in that the transfer function of the input-output characteristics of the first phase compensation element comprises a FIR filter function.

6. The method of claim 2, wherein the transfer function of the input-output characteristics of the second phase compensation element comprises a FIR filter function.

7. A method according to claim 1 or 2, characterized in that the manner of obtaining the capacitive current on the ac side of the converter comprises at least one of:

collecting the capacitance current of the AC side of the converter;

collecting the capacitor voltage at the AC side of the converter and carrying out differential operation on the capacitor voltage to obtain the capacitor current at the AC side of the converter;

and collecting the grid-connected current and the inductive current of the converter and calculating to obtain the capacitive current at the AC side of the converter.

8. The method according to claim 1 or 2, characterized in that the method further comprises:

and using the final control action quantity in closed-loop control of bridge arm current or grid-connected current of the converter.

9. A resonance suppression module of a converter, characterized by comprising a memory, a processor, and a resonance suppression method program of a converter stored on the memory and executable on the processor, the resonance suppression method program of a converter realizing the steps of the resonance suppression method of a converter according to any one of claims 1 to 8 when executed by the processor.

10. The device for inhibiting the resonance of the converter is characterized by comprising a first acquisition module, a first gain link, a first phase compensation link and an output module;

the first acquisition module acquires a capacitance current component on an alternating current side of the converter;

the first gain link is used for carrying out gain adjustment on the capacitance current component;

the first phase compensation link is used for carrying out phase compensation on the gain-adjusted capacitance current component to obtain a first control action quantity;

the output module is configured to superimpose the first control action amount on a controller output of the transducer to form a final control action amount.

11. The apparatus of claim 10, further comprising a second obtaining module, a second gain element, and a second phase compensation element;

the second acquisition module acquires a capacitance voltage component on the AC side of the converter;

the second gain link is used for carrying out gain adjustment on the capacitor voltage component;

the second phase compensation link is used for carrying out phase compensation on the capacitor voltage component after the gain adjustment so as to obtain a second control action quantity;

the output module is further configured to add the first control action amount and the second control action amount to a controller output of the converter to form a final control action amount.

Technical Field

The present application relates to the field of control technologies, and in particular, to a method, a module, and an apparatus for suppressing resonance of a converter.

Background

In order to filter high-frequency harmonics, a high-order filter is often assembled at an alternating current input end or an alternating current output end of the grid-connected converter, and an LCL filter which is widely applied is one of the high-order filters. Under the same filtering performance requirement, the high-order filter is adopted, so that the size of the filter can be reduced, the system cost is saved, and the power density of the system can be increased. However, the output characteristics of the high order filter also pose a resonance risk to the converter.

A resonance suppression strategy based on software control is a mainstream method for dealing with resonance of the converter at present. The application and research of the resonance suppression strategy based on capacitance current feed-forward are the most extensive. The resonance damping frequency range of the resonance suppression strategy based on the capacitor current feed-forward is limited due to the existence of the digital control system delay of the converter. In order to widen the resonant damping frequency range as much as possible, the industry proposes a countermeasure strategy of phase compensation, which is summarized into two main strategies:

1) the sampling point of the digital control system is moved forward, so that the time delay is reduced physically;

the coping strategy is simple to implement, but the delay compensation capability is often limited by the computing capability of a chip, the current sampling precision of the converter is easily influenced, and the additional harmonic problem is brought.

2) Links with leading phase compensation capability such as a first-order phase leading compensator, a second-order generalized integrator and a high-pass filter are connected in series in the resonance suppression control branch circuit to equivalently reduce time delay;

in the coping strategy, the phase compensation quantity of the high-pass filter is reduced along with the increase of the frequency, which is just opposite to the compensation requirement of the digital control system delay, so that the compensation of a local frequency band can be realized; although the first-order phase lead compensator and the second-order generalized integrator can meet the delay compensation requirement of a digital control system in terms of phase characteristics, the delay compensation capability is limited due to the contradiction between phase compensation and noise suppression.

In a control system of an actual converter, the capacitance current may not be detected for cost saving. In this case, the capacitance current required by the resonance suppression strategy based on capacitance current feedforward needs to be obtained by means of capacitance voltage differentiation function, and the resonance suppression method in this case is essentially changed into the resonance suppression strategy based on capacitance voltage differentiation feedforward. In the digital control system, the discretization of the differential algorithm also has the contradiction of phase lag and noise suppression. Thus, the effective resonance damping frequency range of the resonance suppression strategy based on the capacitance voltage differential feedforward is more easily limited, and applying a suitable phase compensator is an important research direction for solving the problem.

The existing research results show that in addition to the damping effect on resonance caused by capacitance current feedforward or capacitance voltage differential feedforward, the damping effect on resonance can be generated when the capacitance voltage on the alternating current side of the converter is used as a voltage feedforward term of a current loop in a digital control system. However, the delay of the digital control system, while allowing the capacitor voltage feed forward filtering to produce the damping characteristic, the large delay in turn limits the range of effective resonant damping frequencies.

In addition, based on a mixed resonance suppression strategy combining capacitance current (or capacitance voltage differential) feedforward and capacitance voltage feedforward, although the resonance damping frequency range of the converter can be widened, in actual use, 1) digital control system delay is caused; 2) in the control of the converter, proper filtering needs to be carried out on the capacitor voltage of feedforward in order to improve the requirement of alternating current; the damping capacity of the damping device is still greatly limited due to the existence of two factors.

Disclosure of Invention

In view of this, an object of the present application is to provide a method, a module, and a device for suppressing resonance of a converter, so as to solve the problem that a resonance damping capability of a grid-connected converter is limited due to a delay of a digital control system in a resonance suppression strategy.

The technical scheme adopted by the application for solving the technical problems is as follows:

according to an aspect of the present application, there is provided a resonance suppression method of a converter, the method including:

acquiring a capacitance current component of an alternating current side of the converter;

adjusting the capacitance current component through a first gain link and a first phase compensation link to obtain a first control action quantity;

adding the first control action quantity to the controller output of the converter to form a final control action quantity.

According to another aspect of the present application, there is provided a resonance suppression module of a converter, including a memory, a processor, and a resonance suppression method program of a converter stored on the memory and executable on the processor, the resonance suppression method program of a converter implementing the steps of the resonance suppression method of a converter when executed by the processor.

According to another aspect of the present application, a resonance suppression apparatus for a converter is provided, which includes a first obtaining module, a first gain element, a first phase compensation element, and an output module;

the first acquisition module acquires a capacitance current component on an alternating current side of the converter;

the first gain link is used for carrying out gain adjustment on the capacitance current component;

the first phase compensation link is used for carrying out phase compensation on the gain-adjusted capacitance current component to obtain a first control action quantity;

the output module is configured to superimpose the first control action amount on a controller output of the transducer to form a final control action amount.

According to the resonance suppression method, the module and the device of the converter, the phase compensator is introduced into the capacitance current feedforward control branch, on the basis of not increasing the system cost, the problem that the resonance damping capacity of the existing resonance suppression method is limited due to time delay of a digital control system is solved, the resonance risk of the converter operating under the wide-range power grid impedance is reduced, and the stable operation capacity of the converter under the power grids with different intensities is enhanced.

Drawings

Fig. 1 is a schematic flowchart of a resonance suppression method of a converter according to a first embodiment of the present application;

fig. 2 is a schematic flowchart of a resonance suppression method of a converter according to a second embodiment of the present application;

fig. 3 is a schematic diagram of a resonance suppression implementation process of a converter according to a third embodiment of the present application;

fig. 4 is a schematic structural diagram of a phase compensator according to an embodiment of the present application;

fig. 5 is a schematic diagram of input/output frequency characteristics of a phase compensator according to an embodiment of the present application;

FIG. 6 is a block diagram of converter current control under a synchronous rotating coordinate system according to an embodiment of the present application;

FIG. 7 is a block diagram of transducer current control in a stationary coordinate system according to an embodiment of the present application;

fig. 8 is a schematic diagram of a resonance suppression apparatus of a converter according to a fourth embodiment of the present application;

fig. 9 is a schematic diagram of a resonance suppression module of a converter according to a fourth embodiment of the present application.

The implementation, functional features and advantages of the objectives of the present application will be further explained with reference to the accompanying drawings.

Detailed Description

In order to make the technical problems, technical solutions and advantageous effects to be solved by the present application clearer and clearer, the present application is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present application and are not intended to limit the present application.

Definition of related variables states:

u_cab、u_cbc、u_cca: the converter filter capacitor voltage is also the grid-connected point voltage;

u_cαβ＝u_cα+ju_cβ: vector of filter capacitor voltage in alpha beta coordinate system, where u_cα、u_cβThe alpha and beta axis components thereof, respectively;

u_cdq＝u_cd+ju_cq: vector of filter capacitor voltage in dq coordinate system, where u_cd、u_cqAre respectively d and q axes thereofAn amount;

i_cαβ＝i_cα+ji_cβ: vector of filter capacitance current in alpha beta coordinate system, wherein i_cα、i_cβThe alpha and beta axis components thereof, respectively;

i_cdq＝i_cd+ji_cq: vector of filter capacitor current in dq coordinate system, where i_cd、i_cqThe d and q axis components thereof, respectively;

G_damp: a gain link of capacitance current feedforward control;

u_{dq_damp}＝u_{d_damp}+ju_{q_damp}: the output vector of the capacitor current after the gain element, where u_{d_damp}、u_{q_damp}The d axis action amount and the q axis action amount are respectively;

G_fw: current loop voltage feedforward gain link

u_{cdq_fw}＝u_{cd_fw}+j_{ucq_fw}: output vector of capacitor voltage after gain element, wherein u_{cd_fw}、u_{cq_fw}The d and q axis components thereof, respectively;

u_{dqfw_comp}＝u_{dfw_comp}+ju_{qfw_comp}: vector form of current loop voltage feed forward contribution, where u_{dfw_comp}、u_{qfw_comp}The d and q axis components thereof, respectively;

G_{ph_damp}: a phase compensator of the capacitor current feedforward control branch circuit;

G_{ph_fw}: a phase compensator of the capacitor voltage feedforward control branch circuit;

df/dt: differential operation;

K_ph: a primary phase compensation coefficient of the phase compensator;

K_{ph_aux}: the phase compensator assists the phase compensation coefficient;

G_avg(z): a phase compensator FIR filter function;

u_{dq_ref}＝u_d__ref+ju_{q_ref}: wave-generating voltage command vector of u_{d_ref}、u_{q_ref}Their d and q axis components, respectively.

Example one

As shown in fig. 1, an embodiment of the present application provides a method for suppressing resonance of a converter, where the method includes:

step S11, acquiring a capacitance current component of the AC side of the converter;

step S12, adjusting the capacitance current component through a first gain link and a first phase compensation link to obtain a first control action quantity;

step S13, superimposing the first control action quantity on the controller output of the converter to form a final control action quantity.

In this example, the first gain element comprises a pure proportional element and/or a functional block with a filter characteristic. The transfer function of the input-output characteristic of the first phase compensation element comprises a FIR filter function.

Therefore, by introducing a phase compensator with input and output characteristic transfer function comprising FIR filter function into the capacitor current feedforward control branch, on the basis of not increasing the system cost, the problem that the resonance damping capacity of the existing resonance suppression method is limited due to the delay of a digital control system is avoided, the resonance risk of the converter operating under the wide-range power grid impedance is reduced, and the stable operation capacity of the converter under the power grids with different intensities is enhanced.

In this example, the manner of obtaining the capacitance current on the ac side of the converter includes at least one of:

collecting the capacitance current of the AC side of the converter;

collecting the capacitor voltage at the AC side of the converter and carrying out differential operation on the capacitor voltage to obtain the capacitor current at the AC side of the converter;

and collecting the grid-connected current and the inductive current of the converter and calculating to obtain the capacitive current at the AC side of the converter.

In this example, a final control action is formed for closed-loop control of the bridge arm current of the converter or closed-loop control of the grid-connected current of the converter.

Example two

As shown in fig. 2, unlike the first embodiment, the method further includes:

step S21, acquiring a capacitance voltage component of the AC side of the converter;

step S22, adjusting the capacitance voltage component through a second gain link and a second phase compensation link to obtain a second control action quantity;

step S23, superimposing the first control action quantity and the second control action quantity on the controller output of the transducer to form a final control action quantity.

The steps of obtaining the first control action amount (S11 and S12) and the steps of obtaining the second control action amount (S21 and S22) may be performed in no order, for example: the first control action amount can be obtained first, and then the second control action amount is obtained; or the second control action amount can be obtained first and then the first control action amount is obtained; or obtain two effects simultaneously.

In this example, the second gain element comprises a pure proportional element and/or a functional block with a filter characteristic. The transfer function of the input-output characteristics of the second phase compensation element comprises a FIR filter function.

Therefore, by introducing a phase compensator with input and output characteristic transfer functions including FIR filter functions into the capacitance current feedforward control branch and the capacitance voltage feedforward control branch, the problem of limited resonance damping capacity caused by delay of a digital control system in the existing resonance suppression method is avoided on the basis of not increasing the system cost, the resonance risk of the converter operating under the wide-range power grid impedance is reduced, and the stable operation capacity of the converter under the power grids with different intensities is enhanced.

EXAMPLE III

Fig. 3 is a schematic diagram of a resonance suppression implementation process of a converter according to a third embodiment of the present application.

The control action amount 1 can be obtained by the following steps: firstly, dq component i of the capacitance current at the AC side of the converter is obtained_cdqThen the component i_cdqBy a gain element G_dampAnd a phase compensation element G_{ph_damp}And obtaining the product. Specifically, the component i_cdqBy a gain element G_dampThen obtaining the initial control action amount u_{dq_damp}，u_{dq_damp}Then through a phase compensation link G_{ph_damp}Then u is obtained_{dq_comp}，u_{dq_comp}I.e. the control action 1. G_dampThe method can be a pure proportion link, a module with a filtering function, or a combination of the two.

Wherein dq component i of the converter AC side capacitance current_cdqCan be obtained by the following method:

mode 1: vector u of converter AC side capacitance voltage under alpha beta coordinate system_cαβObtaining the capacitance current i by differentiating the df/dt_{cαβ_est}Then, the dq component i of the image is obtained through Park conversion_cdq。

Mode 2: collecting three-phase capacitance current i_ca、i_cb、i_ccObtaining a component i corresponding to the dq coordinate system through Clark transformation and Park transformation_cdq。

The control action 2 can be obtained by the following steps: firstly, the voltage u of the capacitor at the AC side of the converter is collected_abcObtaining the component u corresponding to the dq coordinate system through Clark transformation and Park transformation_cdq(ii) a Then the component u_cdqBy a gain element G_fwAnd a phase compensation element G_{ph_fw}And obtaining the product. In particular, the component u_cdqGain element G_fwAfter adjustment, the initial control action u is obtained_{cdq_fw}，u_{cdq_fw}Then through a phase compensation link G_{ph_fw}Then u is obtained_{dqfw_comp}，u_{dqfw_comp}I.e. the control action 2. G_fwThe method can be a pure proportion link, a module with a filtering function, or a combination of the two.

Phase compensation element G_{ph_damp}And G_{ph_fw}As shown in fig. 4, the transfer functions of the input and output characteristics can be collectively expressed as:

in the formula, K_phThe value is recommended to be taken within the range of 0-1 for the primary phase compensation coefficient; k_{ph_aux}The secondary phase compensation coefficient can be used for enhancing the limit compensation capability of the phase compensator, and values are recommended to be taken within the range of 0-1; g_avg(z) is an FIR filter for reducing the noise risk of the compensator, whose input-output characteristic transfer function is:

G_avg(z)＝d+(1-2d)z^-1+dz^-Q，d∈(0,0.5)。

FIG. 5 shows three groups K_ph、K_{ph_aux}And d, the input and output frequency characteristic diagram of the phase compensator under the parameter combination.

Finally, after obtaining the control action amounts 1, 2, the control action amount 1 can be superimposed on the controller output of the converter to form the final control action amount. The control action amount 1 and the control action amount 2 may be added to the controller output of the inverter to form the final control action amount.

As shown in fig. 6, the resonant suppression implementation can refer to the converter current control block diagram in the synchronous rotation (dq) coordinate system.

As shown in fig. 7, the converter current control block diagram in the stationary (α β) coordinate system is different: will component i_cαβBy a gain element G_da2pAnd a phase compensation element G_{ph_damp}Making an adjustment to the component u_cαβBy a gain element G_fwAnd a phase compensation element G_{ph_fw}And (6) carrying out adjustment.

Example four

As shown in fig. 8, a fourth embodiment of the present application provides a resonance suppression apparatus for a converter, including a first obtaining module 11, a first gain element 12, a first phase compensation element 13, and an output module 14;

the first obtaining module 11 obtains a capacitance current component at an ac side of the converter;

the first gain element 12 is configured to perform gain adjustment on the capacitance current component;

the first phase compensation link 13 is configured to perform phase compensation on the gain-adjusted capacitance current component to obtain a first control action amount;

the output module 14 is configured to add the first control action quantity to the controller output of the converter to form a final control action quantity.

In this example, the first gain element comprises a pure proportional element and/or a functional block with a filter characteristic. The transfer function of the input-output characteristic of the first phase compensation element comprises a FIR filter function.

Therefore, by introducing a phase compensator with input and output characteristic transfer function comprising FIR filter function into the capacitor current feedforward control branch, on the basis of not increasing the system cost, the problem that the resonance damping capacity of the existing resonance suppression method is limited due to the delay of a digital control system is avoided, the resonance risk of the converter operating under the wide-range power grid impedance is reduced, and the stable operation capacity of the converter under the power grids with different intensities is enhanced.

In this example, the manner of obtaining the capacitance current on the ac side of the converter includes at least one of:

collecting the capacitance current of the AC side of the converter;

collecting the capacitor voltage at the AC side of the converter and carrying out differential operation on the capacitor voltage to obtain the capacitor current at the AC side of the converter;

and collecting the grid-connected current and the inductive current of the converter and calculating to obtain the capacitive current at the AC side of the converter.

In this example, a final control action is formed for closed-loop control of the bridge arm current of the converter or closed-loop control of the grid-connected current of the converter.

In another example, the resonance suppression apparatus of the converter further includes a second obtaining module 21, a second gain element 22, and a second phase compensation element 23;

the second obtaining module 21 obtains a capacitance voltage component at the ac side of the converter;

the second gain element 22 is configured to perform gain adjustment on the capacitor voltage component;

the second phase compensation link 23 is configured to perform phase compensation on the gain-adjusted capacitor voltage component to obtain a second control action amount;

the output module 14 is further configured to add the first control action quantity and the second control action quantity to the controller output of the converter to form a final control action quantity.

In this example, the second gain element comprises a pure proportional element and/or a functional block with a filter characteristic. The transfer function of the input-output characteristics of the second phase compensation element comprises a FIR filter function.

Therefore, by introducing a phase compensator with input and output characteristic transfer functions including FIR filter functions into the capacitance current feedforward control branch and the capacitance voltage feedforward control branch, the problem of limited resonance damping capacity caused by delay of a digital control system in the existing resonance suppression method is avoided on the basis of not increasing the system cost, the resonance risk of the converter operating under the wide-range power grid impedance is reduced, and the stable operation capacity of the converter under the power grids with different intensities is enhanced.

EXAMPLE five

As shown in fig. 9, a fifth embodiment of the present application provides a resonance suppression module for a converter, which includes a memory 21, a processor 22, and a resonance suppression method program of the converter, which is stored in the memory 21 and is executable on the processor 22, and when the resonance suppression method program of the converter is executed by the processor, the steps of the resonance suppression method of the converter described in embodiment 1 or embodiment 2 are implemented.

The preferred embodiments of the present application have been described above with reference to the accompanying drawings, and are not intended to limit the scope of the claims of the application accordingly. Any modifications, equivalents and improvements which may occur to those skilled in the art without departing from the scope and spirit of the present application are intended to be within the scope of the claims of the present application.