CN105305448A - Active filter auto-disturbance rejection control method based on fuzzy PI compound control - Google Patents

Abstract

The invention discloses an active filter auto-disturbance rejection control method based on fuzzy PI compound control, which comprises that a mathematic dynamic model of an active filter is established; based on the mathematic dynamic model, the fuzzy PI compound control is used to control a direct current capacitor voltage, and an active current of a main circuit of the active electric filter is input by an output power grid; according to the active current, an auto-disturbance rejection controller is used to work out a control law; and the control law is input into a PWM controller to generate a signal which controls an inverter to be switched on or switched off, a switching tube in the main circuit is controlled, and an alternating current compensation current is generated and injected into the power grid to realize current compensation and idle elimination. The active filter auto-disturbance rejection control method based on the fuzzy PI compound control disclosed by the invention can ensure real-time tracking of an instruction current by the compensation current and can effectively reduce harmonic waves.

Description

Based on the active filter Auto-disturbance-rejection Control of Fuzzy~+ PI

Technical field

The present invention relates to active power filtering technical field, particularly relate to a kind of active filter Auto-disturbance-rejection Control based on Fuzzy~+ PI.

Background technology

Along with progress and the development of society, the living standard of people improves day by day, and a large amount of power consumption equipments is put in daily productive life, and the thing followed is exactly, and occur a large amount of harmonic waves and the pollution of reactive power in electrical network, this drastically influence the quality of electric energy.There is harmonic voltage or harmonic current in electrical network to increase electric power the supplementary load loss of system equipment, the problem such as cause measuring and apparatus for automatic control is malfunctioning, have impact on the service efficiency of equipment, time serious, fire may be caused because circuit is overheated.

The outside harmonic compensation device of main employing carrys out compensation harmonic at present, and filter is divided into passive filter and active filter two kinds.Passive filter affects very greatly the impedance operator of the control effects of harmonic wave by system, and be very easily subject to the impact of temperature, harmonic wave and nonlinear load change, its filtering performance is unstable.Therefore and be not suitable for the place of harmonic wave situation complexity in addition, passive filter can only the harmonic wave of the specific order of filtering.Existence can only compensate the defects such as particular harmonic, so mainly concentrate on active filter to the improvement of electric energy problem now.Compared to passive filter, Active Power Filter-APF (Activepowerfilter, APF) achieves dynamic compensation, fast response time; Required energy-storage travelling wave tube capacity is little; Impact by electric network impedance is little, can not with electric network impedance generation resonance etc.

Summary of the invention

Technical problem to be solved by this invention is, a kind of active filter Auto-disturbance-rejection Control based on Fuzzy~+ PI is provided, simplification system is to the structure of active filter model and control the data volume needing collection, the real-time tracking of offset current to instruction current can be guaranteed, effectively reduce harmonic wave, be obviously better than traditional control method.

In order to solve the problems of the technologies described above, the invention provides a kind of active filter Auto-disturbance-rejection Control based on Fuzzy~+ PI, comprising:

Set up the mathematics dynamic model of Active Power Filter-APF;

Based on described mathematics dynamic model, adopt the DC capacitor voltage of Fuzzy~+ PI to Active Power Filter-APF to control, export the active current that electrical network is injected with active power filter main circuit;

Automatic disturbance rejection controller is adopted to calculate control law according to described active current;

By generating the signal of control inverter switch in described control law input PWM controller, the switching tube in main circuit being controlled, produces AC offset current, injecting electrical network and realize current compensation and idle elimination.

Further, the described mathematics dynamic model setting up Active Power Filter-APF, specifically comprises:

The mathematics dynamic model setting up Active Power Filter-APF is

$L\frac{{\mathrm{di}}_c}{dt}=u_s-{\mathrm{Ri}}_c-u_c,$ u _c＝u·u _dc

In formula, L represents Inductor, i _crepresenting AC offset current, is amount to be calculated, u _srepresent line voltage, R represents the equivalent resistance of Inductor internal resistance and circuit, u _crepresent inverter output voltage, u _dcrepresent DC capacitor voltage, u represents the modulation voltage of the PWM controller of control inverter, and as control law to be calculated.

Further, described based on described mathematics dynamic model, adopt the DC capacitor voltage of Fuzzy~+ PI to Active Power Filter-APF to control, export the active current that electrical network is injected with active power filter main circuit, specifically comprise:

Calculate the voltage deviation of not DC capacitor voltage in the same time and reference voltage, wherein, voltage deviation e (the k)=u in kth moment _ref-u _dc(k), in formula, u _refrepresent reference voltage, u _dck () represents the DC capacitor voltage in kth moment;

Using the input of described voltage deviation as Fuzzy~+ PI device, controlled by the fuzzy controller in Fuzzy~+ PI device when transient state, after entering stable state, the PI controller be switched in Fuzzy~+ PI device controls, thus exports the active current i that electrical network is injected with active power filter main circuit ^* _s.

Further, describedly adopt automatic disturbance rejection controller to calculate control law according to described active current, specifically comprise:

According to described active current i ^* _sbuilding first-order tracking differentiator is:

${\stackrel{\·}{z}}_{11}=-k_{0}fal(z_{11}-i_s^{*},{\mathrm{\α}}_0,{\mathrm{\δ}}_0)$

In formula, z ₁₁for described active current i ^* _stracking signal, k ₀, α ₀, δ ₀for adjustable parameter, nonlinear function fal is: $fal(z_{11}-i_s^{*},{\mathrm{\α}}_0,{\mathrm{\δ}}_0)=\left\{\begin{array}{cc}{\left|z_{11}-i_s^{*}\right|}^{{\mathrm{\α}}_0}\mathrm{sgn}(z_{11}-i_s^{*})& \left|z_{11}-i_s^{*}\right|>{\mathrm{\δ}}_0\\ \frac{z_{11}-i_s^{*}}{{{\mathrm{\δ}}_0}^{1-\mathrm{\α}}}& \left|z_{11}-i_s^{*}\right|\≤{\mathrm{\δ}}_0\end{array}\right.;$

Building extended state observer according to the output of described Nonlinear Tracking Differentiator is:

$\left\{\begin{array}{c}{\stackrel{\·}{z}}_1=z_2-k_{11}fal(\left(z_1-{i_s}^{*}\right),{\mathrm{\α}}_1,{\mathrm{\δ}}_1)+u_{dc}u\\ {\stackrel{\·}{z}}_2=-k_{12}fal(\left(z_1-{i_s}^{*}\right),{\mathrm{\α}}_1,{\mathrm{\δ}}_1)\end{array}\right.$

Wherein, k ₁₁, k ₁₂, α ₁, δ ₁for adjustable parameter, z ₁, z ₂represent controller tracing process, z ₁→ x (t), z ₂→ a.(the expansion state variable that x (t) is system, a=f (x, t)+d (t), f (x, t) they are unknown functions, and d (t) is system unknown disturbances;

The control law that the nonlinear combination of utilization state error obtains automatic disturbance rejection controller is

$u_0=k_{2}fal\left(\right(i_s^{*}-z_1),{\mathrm{\α}}_2,{\mathrm{\δ}}_2)$

$u=u_0-\frac{{\stackrel{\·}{z}}_2}{u_{dc}}$

Wherein k ₂, a ₂, δ ₂for adjustable parameter.

Implement the present invention, have following beneficial effect: single-phase shunt active power filter AC of the present invention adopts Auto Disturbances Rejection Control Technique, DC capacitor voltage adopts Fuzzy~+ PI technology, both make use of the advantage that fuzzy control does not rely on system parameters; Adopt again Active Disturbance Rejection Control theoretical, simplify the design of controller, improve the dynamic performance index of system, as current tracking ability and total harmonic factor, the system that further ensure that carries out the ability of harmonic compensation in real time under load power grid environment.

Accompanying drawing explanation

In order to be illustrated more clearly in the embodiment of the present invention or technical scheme of the prior art, be briefly described to the accompanying drawing used required in embodiment or description of the prior art below, apparently, accompanying drawing in the following describes is only some embodiments of the present invention, for those of ordinary skill in the art, under the prerequisite not paying creative work, other accompanying drawing can also be obtained according to these accompanying drawings.

Fig. 1 is the schematic flow sheet of an embodiment of the active filter Auto-disturbance-rejection Control based on Fuzzy~+ PI provided by the invention;

Fig. 2 is Active Power Filter-APF main circuit structure figure;

Fig. 3 is Fuzzy~+ PI system block diagram;

Fig. 4 is Triangleshape grade of membership function;

Fig. 5 is DC Bus Capacitor Voltage of An Active Power Filter reference change conditional curve;

Fig. 6 is automatic disturbance rejection controller structured flowchart;

Fig. 7 is Active Power Filter-APF equivalent circuit diagram;

Fig. 8 compensates front power network current;

Fig. 9 is for compensating rear power network current;

Figure 10 is that DC capacitor voltage follows the tracks of waveform;

Figure 11 is current spectrum figure when not adding control action;

Figure 12 is power network current spectrogram under active disturbance rejection effect.

Embodiment

Below in conjunction with the accompanying drawing in the embodiment of the present invention, be clearly and completely described the technical scheme in the embodiment of the present invention, obviously, described embodiment is only the present invention's part embodiment, instead of whole embodiments.Based on the embodiment in the present invention, those of ordinary skill in the art, not making the every other embodiment obtained under creative work prerequisite, belong to the scope of protection of the invention.

Fig. 1 is the schematic flow sheet of an embodiment of the active filter Auto-disturbance-rejection Control based on Fuzzy~+ PI provided by the invention, as shown in Figure 1, comprising:

S101, set up the mathematics dynamic model of Active Power Filter-APF.

Wherein, setting up mathematics dynamic model according to the Active Power Filter-APF equivalent circuit diagram of Fig. 2 is

$L\frac{{\mathrm{di}}_c}{dt}=u_s-{\mathrm{Ri}}_c-u_c,$ u _c＝u·u _dc

In formula, L represents Inductor, i _crepresenting AC offset current, is amount to be calculated, u _srepresent line voltage, R represents the equivalent resistance of Inductor internal resistance and circuit, u _crepresent inverter output voltage, u _dcrepresent DC capacitor voltage, u represents the modulation voltage of the PWM controller of control inverter, and as control law to be calculated.

S102, based on described mathematics dynamic model, adopt Fuzzy~+ PI (PI-FUZZTCompoundcontrol) DC capacitor voltage to Active Power Filter-APF to control, export the active current that electrical network is injected with active power filter main circuit.

Concrete, as shown in Figure 3, step S102 comprises step:

S1021, calculate the voltage deviation of not DC capacitor voltage in the same time and reference voltage.

Wherein, voltage deviation e (the k)=u in kth moment _ref-u _dc(k), in formula, u _refrepresent reference voltage, u _dck () represents the DC capacitor voltage in kth moment.

S1022, using the input of described voltage deviation as Fuzzy~+ PI device, controlled by fuzzy (Fuzzy) controller in Fuzzy~+ PI device when transient state, after entering stable state, the PI controller be switched in Fuzzy~+ PI device controls, thus exports the active current i that electrical network is injected with active power filter main circuit ^* _s.

Wherein, controlled by fuzzy controller during system transient modelling, system dynamic response performance can be improved; After system enters stable state, be switched to PI controller, the steady-state error of system can be eliminated better, improve the steady-state behaviour of system.The switching of controller is controlled by the order of magnitude of voltage error.Wherein, the parameter of PI controller adopts conventional Tuning to adjust; Fuzzy controller is according to the voltage deviation of each sampling instant, and the fuzzy rule base set up according to the knowledge based on expert, makes rapidly system transient modelling process and effectively judge, realizing stability contorting by suitably strengthening or reducing control dynamics.

Wherein, the input variable of fuzzy controller and the domain of output variable after change of scale are:

X＝{-6-5-4-3-2-10123456}

Its domain is got 7 linguistic variables: NB, NM, NS, ZO, PS, PM, PB.Input variable e (k) and output variable i ^* _sall select overlapping symmetrical Triangleshape grade of membership function, as shown in Figure 4.

Fuzzy control rule is the core of fuzzy control, and therefore, how setting up fuzzy control rule becomes a very crucial problem.Fuzzy control rule is the most natural describing mode to human behavior and decision analysis process, that it establishes fuzzy input variable and fuzzy output becomes contacting between arrow, adopts the hazy condition sentence of IF-THEN form more.

Fig. 5 is the reference curve of DC Bus Capacitor Voltage of An Active Power Filter change procedure, can formulate fuzzy control rule according to this curve.Control experience according to Fig. 5 change procedure and existing DC capacitor voltage, fuzzy control rule can be obtained as shown in Table 1.

Table one artificial circuit parameter

Parameter	Numerical value
		Power supply	U s＝220V rms/50HZ
DC capacitor voltage	U c＝600V
		PWM switching frequency	f s＝20KHZ
Input inductance	L＝6mH
		Output capacitance	C＝0.003μF

Fuzzy inference system herein adopts Mamdani type, namely adopts the Fuzzy implication relation of following form:

IfeisA,thenuisC

De-fuzzy method have employed the output valve that area gravity model appoach (centroid) obtains fuzzy controller---and electrical network is injected with the active current i of active power filter main circuit ^* _s.

S103, automatic disturbance rejection controller is adopted to calculate control law according to described active current.

Concrete, as shown in Figure 6, automatic disturbance rejection controller mainly comprises Nonlinear Tracking Differentiator (TD), this link process reference input; Extended state observer (ESO), this link is used for the input of process control system; And Active Disturbance Rejection Control rule is effectively combined by selecting suitable nonlinear function by state error.

From operation principle, underarm on APF in parallel can be thought perfect switch, its equivalent electric circuit as shown in Figure 7.Action due to switch can control to exchange surveys the size of voltage, so parallel connection type APF is thinking a controlled voltage source and an impedance parallel connection in circuit, compensates, i to harmonic current and reactive current _cfor the offset current that APF exports.PWM link is regarded as proportional component, i.e. a u _c=uu _dc.

From Circuit Theorem: i _s=i _c+ i _l

Associating $L\frac{{\mathrm{di}}_c}{dt}=u_s-{\mathrm{Ri}}_c-u_c$ Obtain

$(L+L_S)\frac{{\mathrm{di}}_s}{dt}=-(R+R_S)i_s-u\·u_{dc}+u_s+{\mathrm{Ri}}_L+L\frac{{\mathrm{di}}_L}{dt}$

Due to line voltage u _signore the impedance on power circuit, utilize the principle of automatic disturbance rejection controller, by u _sbe considered as the indeterminate of model, order system can be write as:

Automatic disturbance rejection controller does not need to detect load current and voltage, only needs to regard them as unknown disturbance.I _s ^*the reference input of automatic disturbance rejection controller can be regarded as.

Therefore, step S103 comprises step:

S1031, according to described active current i ^* _sbuilding first-order tracking differentiator is:

${\stackrel{\·}{z}}_{11}=-k_{0}fal(z_{11}-i_s^{*},{\mathrm{\α}}_0,{\mathrm{\δ}}_0)$

In formula, z ₁₁for described active current i ^* _stracking signal, k ₀, α ₀, δ ₀for adjustable parameter, nonlinear function fal is: $fal(z_{11}-i_s^{*},{\mathrm{\α}}_0,{\mathrm{\δ}}_0)=\left\{\begin{array}{cc}{\left|z_{11}-i_s^{*}\right|}^{{\mathrm{\α}}_0}\mathrm{sgn}(z_{11}-i_s^{*})& \left|z_{11}-i_s^{*}\right|>{\mathrm{\δ}}_0\\ \frac{z_{11}-i_s^{*}}{{{\mathrm{\δ}}_0}^{1-\mathrm{\α}}}& \left|z_{11}-i_s^{*}\right|\≤{\mathrm{\δ}}_0\end{array}\right.;$

S1032, build extended state observer according to the output of described Nonlinear Tracking Differentiator and be:

$\left\{\begin{array}{c}{\stackrel{\·}{z}}_1=z_2-k_{11}fal(\left(z_1-{i_s}^{*}\right),{\mathrm{\α}}_1,{\mathrm{\δ}}_1)+u_{dc}u\\ {\stackrel{\·}{z}}_2=-k_{12}fal(\left(z_1-{i_s}^{*}\right),{\mathrm{\α}}_1,{\mathrm{\δ}}_1)\end{array}\right.$

Wherein, k ₁₁, k ₁₂, α ₁, δ ₁for adjustable parameter, z ₁, z ₂represent controller tracing process, z ₁→ x (t), z ₂→ a.(the expansion state variable that x (t) is system, a=f (x, t)+d (t), f (x, t) they are unknown functions, and d (t) is system unknown disturbances;

The control law that the nonlinear combination of S1033, utilization state error obtains automatic disturbance rejection controller is

$u_0=k_{2}fal\left(\right(i_s^{*}-z_1),{\mathrm{\α}}_2,{\mathrm{\δ}}_2)$

$u=u_0-\frac{{\stackrel{\·}{z}}_2}{u_{dc}}$

Wherein k ₂, a ₂, δ ₂for adjustable parameter.Coefficient in ADRC all need be debugged in simulation

S104, by generating the signal of control inverter switch in described control law input PWM controller, the switching tube in main circuit being controlled, produces AC offset current, injecting electrical network and realize current compensation and idle elimination.

In order to verify the feasibility of above-mentioned theory, under Matlab, carry out emulation experiment.In emulation, the parameter of all PI controllers is K _p=0.2, K _i=0.01.

As can be seen from Figure 8, due to the cause of nonlinear load impact, there is serious distortion phenomenon in the waveform of power network current.

As can be seen from Figure 9, after increasing filter, the distortion phenomenon of the waveform of power network current obtains obvious improvement.

As can be seen from Figure 10 the actual value of DC capacitor voltage can well follow the tracks of the magnitude of voltage of setting, has the advantages such as overshoot is little, stable state accuracy is high, robustness is good

By Figure 11 and Figure 12, known nonlinear load causes power network current to contain a large amount of harmonic wave, now THD=45.82%; Figure 12 is the total harmonic distortion setting up power network current after the Active Power Filter-APF electric current Active Disturbance Rejection Control based on Fuzzy~+ PI, now THD=2.65%.The suppression of Active Power Filter-APF electric current Auto-disturbance-rejection Control to mains by harmonics as can be seen here based on Fuzzy~+ PI is effective..

The technical solution used in the present invention is: Fuzzy~+ PI technology is applied to DC Bus Capacitor Voltage of An Active Power Filter and controls above, Auto Disturbances Rejection Control Technique be applied on Active Power Filter-APF ac-side current compensatory control.By making it reach the magnitude of voltage of setting to the accurate control of DC voltage, the feedback being realized energy again by active filter injects the offset current contrary with harmonic current equal phase in circuit, and make offset current real-time tracking command signal, reach the object of harmonic carcellation.

By adopting technique scheme, single-phase shunt active power filter AC of the present invention adopts Auto Disturbances Rejection Control Technique, DC capacitor voltage adopts Fuzzy~+ PI technology, and beneficial effect of the present invention exists: both make use of the advantage that fuzzy control does not rely on system parameters; Adopt again Active Disturbance Rejection Control theoretical, simplify the design of controller, improve the dynamic performance index of system, as current tracking ability and total harmonic factor, the system that further ensure that carries out the ability of harmonic compensation in real time under load power grid environment.Obviously be better than traditional control method.

It should be noted that, in this article, term " comprises ", " comprising " or its any other variant are intended to contain comprising of nonexcludability, thus make to comprise the process of a series of key element, method, article or device and not only comprise those key elements, but also comprise other key elements clearly do not listed, or also comprise by the intrinsic key element of this process, method, article or device.When not more restrictions, the key element limited by statement " comprising ... ", and be not precluded within process, method, article or the device comprising this key element and also there is other identical element.

To the above-mentioned explanation of the disclosed embodiments, professional and technical personnel in the field are realized or uses the present invention.To be apparent for those skilled in the art to the multiple amendment of these embodiments, General Principle as defined herein can without departing from the spirit or scope of the present invention, realize in other embodiments.Therefore, the present invention can not be restricted to these embodiments shown in this article, but will meet the widest scope consistent with principle disclosed herein and features of novelty.

Claims (4)

1., based on an active filter Auto-disturbance-rejection Control for Fuzzy~+ PI, it is characterized in that, comprising:

Set up the mathematics dynamic model of Active Power Filter-APF;

Based on described mathematics dynamic model, adopt the DC capacitor voltage of Fuzzy~+ PI to Active Power Filter-APF to control, export the active current that electrical network is injected with active power filter main circuit;

Automatic disturbance rejection controller is adopted to calculate control law according to described active current;

By generating the signal of control inverter switch in described control law input PWM controller, the switching tube in main circuit being controlled, produces AC offset current, injecting electrical network and realize current compensation and idle elimination.

2., as claimed in claim 1 based on the active filter Auto-disturbance-rejection Control of Fuzzy~+ PI, it is characterized in that, the described mathematics dynamic model setting up Active Power Filter-APF, specifically comprises:

The mathematics dynamic model setting up Active Power Filter-APF is

$L\frac{{\mathrm{di}}_c}{dt}=u_s-{\mathrm{Ri}}_c-u_c,$ u _c＝u·u _dc

In formula, L represents Inductor, i _crepresenting AC offset current, is amount to be calculated, u _srepresent line voltage, R represents the equivalent resistance of Inductor internal resistance and circuit, u _crepresent inverter output voltage, u _dcrepresent DC capacitor voltage, u represents the modulation voltage of the PWM controller of control inverter, and as control law to be calculated.

3. the active filter Auto-disturbance-rejection Control based on Fuzzy~+ PI according to claim 2, it is characterized in that, described based on described mathematics dynamic model, the DC capacitor voltage of Fuzzy~+ PI to Active Power Filter-APF is adopted to control, export the active current that electrical network is injected with active power filter main circuit, specifically comprise:

Calculate the voltage deviation of not DC capacitor voltage in the same time and reference voltage, wherein, voltage deviation e (the k)=u in kth moment _ref-u _dc(k), in formula, u _refrepresent reference voltage, u _dck () represents the DC capacitor voltage in kth moment;

Using the input of described voltage deviation as Fuzzy~+ PI device, controlled by the fuzzy controller in Fuzzy~+ PI device when transient state, after entering stable state, the PI controller be switched in Fuzzy~+ PI device controls, thus exports the active current i that electrical network is injected with active power filter main circuit ^* _s.

4. the active filter Auto-disturbance-rejection Control based on Fuzzy~+ PI according to claim 3, is characterized in that, describedly adopts automatic disturbance rejection controller to calculate control law according to described active current, specifically comprises:

According to described active current i ^* _sbuilding first-order tracking differentiator is:

${\stackrel{\·}{z}}_{11}=-k_{0}fal(z_{11}-i_s^{*},{\mathrm{\α}}_0,{\mathrm{\δ}}_0)$

In formula, z ₁₁for described active current i ^* _stracking signal, k ₀, α ₀, δ ₀for adjustable parameter, nonlinear function fal is: $fal(z_{11}-i_s^{*},{\mathrm{\α}}_0,{\mathrm{\δ}}_0)=\left\{\begin{array}{cc}|z_{11}-i_s^{*}{|}^{{\mathrm{\α}}_0}\mathrm{sgn}(z_{11}-i_s^{*})& |z_{11}-i_s^{*}|>{\mathrm{\δ}}_0\\ \frac{z_{11}-i_s^{*}}{{{\mathrm{\δ}}_0}^{1-\mathrm{\α}}}& |z_{11}-i_s^{*}|\≤{\mathrm{\δ}}_0\end{array}\right.;$

Building extended state observer according to the output of described Nonlinear Tracking Differentiator is:

$\left\{\begin{array}{c}{\stackrel{\·}{z}}_1=z_2-k_{11}fal(\left(z_1-{i_s}^{*}\right),{\mathrm{\α}}_1,{\mathrm{\δ}}_1)+u_{dc}u\\ {\stackrel{\·}{z}}_2=-k_{12}fal(\left(z_1-{i_s}^{*}\right),{\mathrm{\α}}_1,{\mathrm{\δ}}_1)\end{array}\right.$

Wherein, k ₁₁, k ₁₂, α ₁, δ ₁for adjustable parameter, z ₁, z ₂represent controller tracing process, z ₁→ x (t), z ₂the expansion state variable that → a, x (t) they are system, and a=f (x, t)+d (t), f (x, t) they are unknown functions, and d (t) is system unknown disturbances;

The control law that the nonlinear combination of utilization state error obtains automatic disturbance rejection controller is

$u_0=k_{2}fal\left(\right(i_s^{*}-z_1),{\mathrm{\α}}_2,{\mathrm{\δ}}_2)$

$u=u_0-\frac{{\stackrel{\·}{z}}_2}{u_{dc}}$

Wherein k ₂, a ₂, δ ₂for adjustable parameter.