CN112993966A - Active filtering method applied to direct current system - Google Patents

Active filtering method applied to direct current system Download PDF

Info

Publication number
CN112993966A
CN112993966A CN202110359412.4A CN202110359412A CN112993966A CN 112993966 A CN112993966 A CN 112993966A CN 202110359412 A CN202110359412 A CN 202110359412A CN 112993966 A CN112993966 A CN 112993966A
Authority
CN
China
Prior art keywords
current
signal
active
active filter
filter
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
CN202110359412.4A
Other languages
Chinese (zh)
Other versions
CN112993966B (en
Inventor
窦文雷
姚钢
黄琛
周荔丹
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
China Ship Development and Design Centre
Shanghai Jiao Tong University
Original Assignee
China Ship Development and Design Centre
Shanghai Jiao Tong University
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by China Ship Development and Design Centre, Shanghai Jiao Tong University filed Critical China Ship Development and Design Centre
Priority to CN202110359412.4A priority Critical patent/CN112993966B/en
Publication of CN112993966A publication Critical patent/CN112993966A/en
Application granted granted Critical
Publication of CN112993966B publication Critical patent/CN112993966B/en
Active legal-status Critical Current
Anticipated expiration legal-status Critical

Links

Images

Classifications

    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J1/00—Circuit arrangements for DC mains or DC distribution networks
    • H02J1/02—Arrangements for reducing harmonics or ripples
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E40/00—Technologies for an efficient electrical power generation, transmission or distribution
    • Y02E40/40—Arrangements for reducing harmonics

Landscapes

  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Supply And Distribution Of Alternating Current (AREA)

Abstract

一种应用于直流系统的有源滤波方法，通过对直流负载处的电流采样滤波后得到负载电流中的谐波信号，经取反后作为补偿信号并与有源滤波器产生的电流信号相减得到误差信号，以该误差信号作为负反馈，进而动态调节隔离DC/DC变换器输出的电压以及输出的电流范围，从而使得有源滤波器的损耗最小化。本发明通过有源滤波器的补偿作用，大幅度降低直流负载的电流谐波，提高负载侧电压及电流的电能质量，使负载更加稳定可靠运行，有效降低谐波给直流系统中的带来的危害。

Figure 202110359412

An active filtering method applied to the DC system, the harmonic signal in the load current is obtained by sampling and filtering the current at the DC load, and the inversion is used as a compensation signal and subtracted from the current signal generated by the active filter. The error signal is obtained, and the error signal is used as negative feedback to dynamically adjust the output voltage and output current range of the isolated DC/DC converter, thereby minimizing the loss of the active filter. The invention greatly reduces the current harmonics of the DC load through the compensation function of the active filter, improves the power quality of the voltage and current on the load side, makes the load more stable and reliable, and effectively reduces the harmonics brought to the DC system. harm.

Figure 202110359412

Description

Active filtering method applied to direct current system
Technical Field
The invention relates to a technology in the field of direct current filters, in particular to an active filtering method applied to a direct current system.
Background
In the prior art, active filters are increasingly gaining attention and being used to improve the quality of electric power. However, most active filters are designed for three-phase ac systems and cannot be applied directly to dc systems. Some control methods for an active filter in an ac system, although they can also be applied to an active filter in a dc system, do not make good use of the characteristics of the dc system, and thus are redundant and complicated. However, in the existing research on the dc active filter, most of the researches are on the current tracking control and the harmonic detection algorithm thereof, and the control of the dc side voltage of the active filter and the influence of the harmonic frequency change on the filtering effect are rarely considered, and a specific architecture of the whole dc active filter system is not given. Aiming at the characteristic that direct current is mainly used in a direct current system, the direct current active filter can be simplified in control, and the loss of the active filter can be reduced as much as possible.
Disclosure of Invention
Aiming at the problems of larger load harmonic current, fixed and unadjustable input voltage, unstable direct-current side voltage and larger loss in the existing direct-current system, the invention provides an active filtering method applied to the direct-current system, which greatly reduces the current harmonic of a direct-current load through the compensation effect of an active filter, improves the electric energy quality of the load side voltage and current and ensures that the load can operate more stably and reliably; the stable filtering effect can be still kept when the harmonic frequency changes through the PI controller and the self-adaptive quasi-PR controller; the isolated DC/DC converter directly takes electricity from the DC bus to provide stable DC voltage for the input end of the active filter, so that an additional DC power supply is not needed; the system can also estimate harmonic power according to the magnitude of load voltage and current, so as to intelligently regulate and control the output voltage of the DC/DC converter, namely the input voltage of the active filter, so that the output current of the DC/DC converter is kept in a certain range, devices are protected, meanwhile, the loss of the active filter can be reduced, the normal and stable operation of the load is ensured, and the harm of harmonic to a direct current system is effectively reduced.
The invention is realized by the following technical scheme:
the invention relates to an active filtering method applied to a direct current system, which is characterized in that a harmonic signal in load current is obtained after current at a direct current load is sampled and filtered, the harmonic signal is used as a compensation signal after being inverted and is subtracted from a current signal generated by an active filter to obtain an error signal, and the error signal is used as negative feedback to dynamically adjust and isolate the voltage output by a DC/DC converter and the range of the output current, so that the loss of the active filter is minimized.
The negative feedback generates a control signal through a parallel PI controller and a self-adaptive quasi-PR controller which are arranged between the direct current bus and the active filter, and the control signal is compared with a triangular carrier by a carrier pulse width modulation (CBPWM) unit to obtain a control signal for controlling the on and off of a switching tube in the active filter.
The active filter is arranged on a direct current bus through an isolation DC/DC converter and is connected with a load, and the active filter specifically comprises: the output end of the direct current active filter is connected with the direct current load in parallel through a blocking capacitor, the input end of the direct current active filter is connected with the output end of the isolation DC/DC converter, and the input end of the isolation DC/DC converter is connected with the direct current bus.
The active filter adopts a diode Neutral Point Clamped (NPC) three-level topology, and comprises: the active filter comprises eight switching tubes, two blocking capacitors and a second-order LC filter which is composed of an output filter capacitor and an output filter inductor and used for filtering harmonic waves in output current of the active filter.
The isolation DC/DC converter adopts a two-level dual-active full-bridge topology, and comprises: eight switching tubes, a high-frequency transformer, an input filter capacitor, two output filter capacitors and a resonant inductor.
The isolated DC/DC converter voltage loop is controlled with single phase shift PWM and the output voltage can be varied by varying the value of the reference voltage.
Technical effects
The invention integrally solves the harmonic problem of the direct current load in the existing direct current microgrid system. Compared with the prior art, the invention can quickly and effectively compensate the harmonic current of the direct current load and reduce the harmonic distortion rate of the load current to about 0.01 percent. The PI controller and the self-adaptive quasi-PR controller are adopted in the control of the active filter, so that good tracking and compensation effects can be still kept when the frequency or the load of the generator suddenly changes; the direct current side of the active filter adopts the mode that the isolation DC/DC converter directly supplies power, so that the voltage of the direct current side can be still ensured to be stable when the load power fluctuates.
Drawings
FIG. 1 is a schematic diagram of an embodiment of an active filter;
FIG. 2 is a flow chart of an embodiment active filtering method.
FIG. 3 is a flowchart of a voltage loop control method of an isolated DC/DC converter according to an embodiment.
Detailed Description
As shown in fig. 1, the present embodiment relates to a dc active filtering system with a harmonic frequency adaptive tracking function, which includes: direct current bus, direct current load, direct current active filter, isolated DC/DC converter, wherein: the input end and the output end of the isolated DC/DC converter are respectively connected with the DC bus and the DC side of the active filter, and the output end of the DC active filter passes through the inductor LfAnd a capacitor CfForm a second-order LC filter and a DC blocking capacitor CiThen the current is connected in parallel with the DC load to be compensated, thereby improving the current flowing through the load and further improving the voltage on the load.
The DC/DC converter adopts two-level full-bridge DAB topology and phase-shift PWM voltage closed-loop control to ensure the stability of output voltage and improve the voltage utilization rate, and the voltage and current stress of a switching device is small, so the cost is low, high efficiency can be achieved, and the problem of voltage stability of the direct current side of an active filter does not need to be considered.
The active filter adopts a diode neutral point clamped three-level topology, has a better compensation effect compared with two levels, has lower voltage stress of the switching tube, saves cost and reduces loss.
The embodiment relates to a direct current active filtering method of the system, which is characterized in that harmonic power is obtained through sampling voltage and current at a direct current load and estimating, and then the voltage output by an isolation DC/DC converter and the range of the output current are dynamically adjusted, so that the loss of an active filter is minimized.
The embodiment reduces the output voltage of the isolation DC/DC converter as much as possible on the premise of ensuring that the output current does not exceed the allowable maximum value, even if the input voltage of the active filter is as low as possible, thereby reducing the loss of the active filter.
As shown in fig. 2, the minimization of the loss of the active filter specifically includes:
the method comprises the following steps: sampling the current at the load to obtain a current signal I containing direct current and harmonic currentd+idAfter passing through a low-pass filter, a direct current I without harmonic waves is obtaineddAnd then using the collected current signal Id+idSubtracting the DC signal IdThe harmonic signal i in the load current can be obtainedd。
Step two: harmonic signal idObtaining the compensation signal needed to be generated by the active filter by taking the inverse, and then combining the compensation signal with the current signal i generated by the active filtercBy subtraction, i.e. obtaining the error signal e by negative feedbackiAnd then respectively inputting the signals into a PI controller and an adaptive quasi-PR controller.
Step three: and a carrier pulse width modulation (CBPWM) unit superposes signals output by the PI controller and the self-adaptive quasi-PR controller and compares the superposed signals with upper and lower paths of in-phase triangular carriers to obtain a control signal for controlling the on and off of a switching tube in the active filter.
As shown in fig. 3, the single phase shift PWM control of the isolated DC/DC converter specifically includes:
step i: sampling the output voltage of the converter to obtain UoutAnd using a set reference voltage UrefMinus the sampling voltage UoutBy using negative feedback to obtain the error signal euThe above signals are combinedAnd inputting the signals into a PI controller to generate a control signal of phase shift.
Step ii: the signal output by the controller is processed by a linearization unit and then compared with a triangular wave, namely a Pulse Width Modulation (PWM) strategy is adopted to obtain a control signal for controlling the on and off of a switching tube in the isolation DC/DC converter.
Through simulation, under the environment of MATLAB/Simulink, the direct current active filter system is built, the harmonic distortion rate of the load current before filtering is about 0.08%, the harmonic distortion rate of the load current after filtering is about 0.01%, the harmonic distortion rate can still be kept about 0.01% when the frequency of the generator fluctuates, and the voltage of the direct current side of the active filter is kept at 400V in the period.
In summary, the present invention utilizes a diode midpoint clamping type three-level topology and an isolation DC/DC converter to directly take power at a DC bus as an input voltage of an active filter, and adopts a PI + adaptive quasi-PR control strategy on a current tracking control strategy of the active filter, so that the system can still maintain a good compensation effect under the condition of harmonic frequency variation.
The foregoing embodiments may be modified in many different ways by those skilled in the art without departing from the spirit and scope of the invention, which is defined by the appended claims and all changes that come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.

Claims (7)

1.一种应用于直流系统的有源滤波方法，其特征在于，通过对直流负载处的电流采样滤波后得到负载电流中的谐波信号，经取反后作为补偿信号并与有源滤波器产生的电流信号相减得到误差信号，以该误差信号作为负反馈，进而动态调节隔离DC/DC变换器输出的电压以及输出的电流范围，从而使得有源滤波器的损耗最小化；1. an active filtering method applied to a DC system, it is characterized in that, the harmonic signal in the load current is obtained by sampling and filtering the current at the DC load place, and after the inversion is used as a compensation signal and is combined with the active filter. The generated current signal is subtracted to obtain an error signal, and the error signal is used as negative feedback to dynamically adjust the output voltage and output current range of the isolated DC/DC converter, thereby minimizing the loss of the active filter; 所述的负反馈，通过设置于直流母线和有源滤波器之间的并联的PI控制器和自适应准PR控制器生成控制信号，进一步由载波脉宽调制CBPWM单元将控制信号与三角载波相比较，得到用于控制有源滤波器中的开关管导通与关断的控制信号。The negative feedback generates a control signal through a parallel PI controller and an adaptive quasi-PR controller arranged between the DC bus and the active filter, and the control signal is further phased with the triangular carrier by the carrier pulse width modulation CBPWM unit. By comparison, a control signal for controlling the turn-on and turn-off of the switch in the active filter is obtained. 2.根据权利要求1所述的应用于直流系统的有源滤波方法，其特征是，所述的有源滤波器，通过隔离DC/DC变换器设置于直流母线上并与负载相连，具体为：直流有源滤波器输出端与直流负载经隔直电容并联，直流有源滤波器输入端与隔离DC/DC变换器的输出端相连，隔离DC/DC变换器的输入端与直流母线相连。2. The active filtering method applied to a DC system according to claim 1, wherein the active filter is arranged on the DC bus and connected to the load by isolating the DC/DC converter, and is specifically : The output end of the DC active filter is connected in parallel with the DC load through the DC blocking capacitor, the input end of the DC active filter is connected with the output end of the isolated DC/DC converter, and the input end of the isolated DC/DC converter is connected with the DC bus. 3.根据权利要求1所述的应用于直流系统的有源滤波方法，其特征是，所述的有源滤波器，采用二极管中点箝位型三电平拓扑，包括：八个开关管、两个隔直电容以及由输出滤波电容和输出滤波电感构成的用于滤除有源滤波器输出电流中的谐波的二阶LC滤波器。3. The active filtering method applied to a DC system according to claim 1, wherein the active filter adopts a diode midpoint clamping type three-level topology, comprising: eight switch tubes, Two DC blocking capacitors and a second-order LC filter composed of an output filter capacitor and an output filter inductor for filtering out harmonics in the output current of the active filter. 4.根据权利要求1所述的应用于直流系统的有源滤波方法，其特征是，所述的隔离DC/DC变换器采用两电平双有源全桥拓扑，包括：八个开关管、高频变压器、输入滤波电容、两个输出滤波电容和谐振电感。4. The active filtering method applied to a DC system according to claim 1, wherein the isolated DC/DC converter adopts a two-level dual active full-bridge topology, comprising: eight switch tubes, High frequency transformer, input filter capacitor, two output filter capacitors and resonant inductor. 5.根据权利要求1所述的应用于直流系统的有源滤波方法，其特征是，所述的隔离DC/DC变换器电压环采用单移相PWM控制，并且通过改变参考电压的值来改变输出电压。5. The active filtering method applied to a DC system according to claim 1, wherein the isolated DC/DC converter voltage loop adopts single-phase-shift PWM control, and is changed by changing the value of the reference voltage The output voltage. 6.根据权利要求1所述的应用于直流系统的有源滤波方法，其特征是，所述的有源滤波器的损耗最小化，具体包括：6. The active filtering method applied to a DC system according to claim 1, wherein the loss of the active filter is minimized, specifically comprising: 步骤一：对负载处的电流进行采样，得到包含直流电流和谐波电流的电流信号Id+id，经过低通滤波器后得到不含谐波的直流电流Id，再用上述采集到的电流信号Id+id减去直流信号Id便可得到负载电流中的谐波信号id；Step 1: Sampling the current at the load to obtain the current signal I d +id including the DC current and the harmonic current. After passing through the low-pass filter, the DC current I d without harmonics is obtained . The harmonic signal id in the load current can be obtained by subtracting the DC signal I d from the current signal I d + id of the load current; 步骤二：将谐波信号id取反得到需要有源滤波器产生的补偿信号，再将上述补偿信号与有源滤波器已经产生的电流信号ic相减，即通过负反馈获得误差信号ei后，分别输入PI控制器及自适应准PR控制器；Step 2: Invert the harmonic signal id to obtain the compensation signal that needs to be generated by the active filter, and then subtract the above compensation signal from the current signal ic that has been generated by the active filter, that is, obtain the error signal e through negative feedback After i , input the PI controller and the adaptive quasi-PR controller respectively; 步骤三：载波脉宽调制单元将PI控制器及自适应准PR控制器输出的信号叠加后与上下两路同相三角载波相比较，得到控制有源滤波器中的开关管导通与关断的控制信号。Step 3: The carrier pulse width modulation unit superimposes the signals output by the PI controller and the adaptive quasi-PR controller and compares them with the upper and lower in-phase triangular carriers, and obtains the switching on and off of the switches in the active filter. control signal. 7.根据权利要求5所述的应用于直流系统的有源滤波方法，其特征是，所述的隔离DC/DC变换器的单移相PWM控制，具体包括：7. The active filtering method applied to a DC system according to claim 5, wherein the single-phase-shift PWM control of the isolated DC/DC converter specifically includes: 步骤i：对变换器的输出电压进行采样得到Uout，并用设定的参考电压Uref减去采样电压Uout，即采用负反馈得到误差信号eu，将上述信号输入PI控制器，生成移相比的控制信号；Step i: sampling the output voltage of the converter to obtain U out , and subtracting the sampling voltage U out from the set reference voltage U ref , that is, using negative feedback to obtain the error signal e u , and inputting the above signal into the PI controller to generate a shift signal. compared to the control signal; 步骤ii：将控制器输出的信号经过线性化单元处理，再通过与三角波进行比较，即采用脉宽调制策略，得到控制隔离DC/DC变换器中的开关管导通与关断的控制信号。Step ii: The signal output by the controller is processed by the linearization unit, and then compared with the triangular wave, that is, the pulse width modulation strategy is used to obtain the control signal for controlling the switching on and off of the isolated DC/DC converter.
CN202110359412.4A 2021-04-02 2021-04-02 Active filtering method applied to direct current system Active CN112993966B (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CN202110359412.4A CN112993966B (en) 2021-04-02 2021-04-02 Active filtering method applied to direct current system

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CN202110359412.4A CN112993966B (en) 2021-04-02 2021-04-02 Active filtering method applied to direct current system

Publications (2)

Publication Number Publication Date
CN112993966A true CN112993966A (en) 2021-06-18
CN112993966B CN112993966B (en) 2023-03-24

Family

ID=76339064

Family Applications (1)

Application Number Title Priority Date Filing Date
CN202110359412.4A Active CN112993966B (en) 2021-04-02 2021-04-02 Active filtering method applied to direct current system

Country Status (1)

Country Link
CN (1) CN112993966B (en)

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN1658485A (en) * 2005-03-10 2005-08-24 上海交通大学 Inverse Control Current Tracking Control Method Based on Average Current Compensation
US20110057517A1 (en) * 2009-09-09 2011-03-10 Jinhui Zhang Hybrid Conditioner for a Power System
CN104269841A (en) * 2014-09-19 2015-01-07 中国舰船研究设计中心 Rectification harmonic suppression device for direct current power grid
CN104993470A (en) * 2015-06-29 2015-10-21 南京航空航天大学 Control mode for active filter in DC link
CN110912132A (en) * 2019-11-27 2020-03-24 天津瑞能电气有限公司 Harmonic compensation control method for single-phase cascade active power filter

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN1658485A (en) * 2005-03-10 2005-08-24 上海交通大学 Inverse Control Current Tracking Control Method Based on Average Current Compensation
US20110057517A1 (en) * 2009-09-09 2011-03-10 Jinhui Zhang Hybrid Conditioner for a Power System
CN104269841A (en) * 2014-09-19 2015-01-07 中国舰船研究设计中心 Rectification harmonic suppression device for direct current power grid
CN104993470A (en) * 2015-06-29 2015-10-21 南京航空航天大学 Control mode for active filter in DC link
CN110912132A (en) * 2019-11-27 2020-03-24 天津瑞能电气有限公司 Harmonic compensation control method for single-phase cascade active power filter

Non-Patent Citations (4)

* Cited by examiner, † Cited by third party
Title
WEI HUANG 等: "A Novel Recursive Integral PI Repetitive Control for Three-phase Three-wire Shunt Active Power Filter", 《2011 6TH IEEE CONFERENCE ON INDUSTRIAL ELECTRONICS AND APPLICATIONS》 *
刘文亚 等: "基于级联多电平的有源滤波器直流侧电压平衡控制", 《电力系统保护与控制》 *
孟鑫 等: "改进PR控制器在四桥臂有源滤波装置中的设计与实现", 《电测与仪表》 *
纪飞峰 等: "基于直流侧电压周期离散控制的单相并联有源滤波器", 《中国电机工程学报》 *

Also Published As

Publication number Publication date
CN112993966B (en) 2023-03-24

Similar Documents

Publication Publication Date Title
CN109302094A (en) Non-isolated modular three-level parallel inverter, control method and system
CN109066684B (en) A three-phase active power filter based on LCL filter and its control method
CN108574403A (en) Non-isolated photovoltaic inverter common-mode resonant loop current and leakage current suppression method
CN110572057B (en) Current source converter specific harmonic suppression method under extremely low switching frequency
CN102916572A (en) Control method and system for inhibiting secondary ripple current and improving dynamic characteristic
CN101540510A (en) Method for eliminating secondary pulsation interference on middle DC side in two-stage grid-connected system
CN107800135B (en) A Different Harmonic Refinement Compensation Method for SAPF
KR20200075136A (en) Charging apparatus capable of reducing low frequency leakage current
Rahmani et al. Two PWM techniques for single-phase shunt active power filters employing a direct current control strategy
CN110266009A (en) An AC microgrid high-order harmonic active stabilization device and method
CN110212535B (en) A high-order harmonic active stabilization device and method for an AC-DC hybrid microgrid
CN113746309A (en) DC active filter resonance suppression method based on inverter side current feedback
CN112350590A (en) Uncontrolled rectifier harmonic compensation circuit and control method
CN105680711B (en) A kind of T-shaped three-level inverter neutral-point voltage balance method using SHEPWM
CN114884046B (en) An adaptive suppression method for multiple low-order harmonic currents based on impedance editing
US11695322B2 (en) AC-side symmetrically-split single-phase inverter for decoupling
CN111064380A (en) A grid-connected inverter system
CN113067372A (en) Active damping method and circuit for improving LCL filtering grid-connected control performance
Miret et al. A simple sliding mode control of an active power filter
CN102025146A (en) Double-switch direct current active power filter and control method thereof
Guo et al. Third-order current harmonic suppression and neutral-point voltage balance control strategy for single-phase three-level NPC inverter
CN112993966A (en) Active filtering method applied to direct current system
CN113078837B (en) Clamping type three-level converter based on auxiliary bridge arm structure and control method
Engel et al. Digital repetitive control of a three-phase flat-top-modulated grid tie solar inverter
Mobarrez et al. A control method for THD minimization in high power density vienna-type rectifier

Legal Events

Date Code Title Description
PB01 Publication
PB01 Publication
SE01 Entry into force of request for substantive examination
SE01 Entry into force of request for substantive examination
GR01 Patent grant
GR01 Patent grant