CN103855716A - Intelligent FLC-PID mixed STATCOM control method - Google Patents

Abstract

The invention relates to an intelligent FLC-PID mixed STATCOM control method. The method comprises the steps that (1) an option switch is automatically switched to a PID controller, wherein when the voltage deviation absolute value |e| is smaller than 1.5, the fuzzy logic control effect becomes poor, vibration is generated, at the moment, the option switch is switched to the PID controller, and a STATCOM stably outputs required reactive power for a system; (2) the option switch is automatically switched to an FLC controller, wherein when the voltage deviation absolute value |e| is larger than 1.5, the system starts the FLC controller with the rapid dynamic response. According to the intelligent FLC-PID mixed STATCOM control method, the defect of slow system dynamic response of a traditional PID method is overcome, self vibration generated by fuzzy logic control near the local minimum value is alleviated, the step response speed is high, the system can be in the steady state rapidly, the overshoot is obviously reduced, the dynamic performance of the STATCOM system is greatly improved, and the better adaptive capacity and the better control effect are achieved.

Description

A kind of FLC-PID hybrid intelligent STATCOM control method

Technical field

The invention belongs to electric power system STATCOM equipment technical field, especially a kind of FLC-PID hybrid intelligent STATCOM control method.

Background technology

On the one hand along with extensive use and the development of automatic production line, Precision Machining, computer system, Robotics etc., the requirement of power distribution system quality of electric power is improved constantly in recent years.On the other hand, along with various novel electric power apparatus, especially power electronic equipment is applied to electrical network, has brought a large amount of harmonic pollution problems, and the quality of power supply of electric power system is worsened.This two reasons has promoted the development of people to power quality control technology.

STATCOM is a kind of parallel connection type dynamic reactive power compensation equipment, can effectively solve the multiple power quality problems such as voltage fluctuation in electric power system, voltage dip, Voltage unbalance, harmonic pollution, guarantees the mutual balance of electric current and voltage in electric power system.Its principle is that wherein Q is total reactive power that three-phase STATCOM absorbs from system, is system phase voltage.In the time of δ >0, Q>0, STATCOM absorbs lagging reactive power from system; In the time of δ <0, Q<0, STATCOM sends lagging reactive power from system.Therefore, by controlling the direction of δ, can in the time that System Reactive Power is not enough, provide reactive power support, in the time that System Reactive Power is superfluous, absorb unnecessary idle; By controlling the size of δ, can regulate the perception of STATCOM absorption or the size of capacitive reactive power in dynamic smoothing ground in addition.

Traditional PI D(proportional-integral derivative controller) control method lacks quick adaptive capacity to STATCOM dynamic characteristic and external interference in reactive power aspect following, and requires accurate Mathematical Modeling simultaneously.As shown in Figure 1, it is the inverse system control structure in a kind of PID, Uref is the reference value of the node voltage of system, Ua, b, c is the instantaneous phase voltage of the three-phase of system, X is short-circuit reactance, Qs is STATCOM to the reactive power of injecting in system, and δ is the phase angle difference of STATCOM AC output voltage and system voltage, and K and Ki are respectively ratio and integral adjustment coefficient.Utilize the instantaneous value calculating voltage effective value of three-phase voltage, that is: $U=\sqrt{(u_a^2+u_b^2+u_c^2)/3}$

The control of δ is adopted to following algorithm, that is:

$\mathrm{\&Delta;\&delta;}={\mathrm{\&delta;}}_1+(\frac{K_i}{S}+K)\mathrm{\&Delta;U}$

Wherein, δ 1 is the approximation of the δ that obtains by method of inverse, and △ δ is the adjustment amount of δ, and S is Laplacian, and the difference of port voltage reference value and actual value is △ U=Uref-Ud.

And fuzzy logic control is comparatively loose to the Mathematical Modeling requirement of controlled device, aspect the variation of system model parameter, showing good robustness, there is certain complementarity with traditional PID control.FLC(fuzzy logic controller) be gamma controller, there is dynamic response fast, to the adaptable feature of shock wave, but near domain " 0 " value, easily produce self-oscillation.As shown in Figure 2, be the system control structure in a kind of FLC, FLC fuzzy logic control method is the controller of a dual input list output in form, input variable is respectively voltage error E and voltage error rate of change C _e, output variable is proportional integral constant K _p.

The linguistic variable of input, output is divided into 7 Linguistic Values, is: (NB, NM, NS, Z, PS, PM, PB), fuzzy reasoning has 7 × 7=49 rule.Membership function all adopts the triangular function form that sensitivity is higher to represent

Summary of the invention

The object of the invention is to overcome the deficiencies in the prior art, a kind of FLC-PID hybrid intelligent STATCOM control method is provided, FLC and PID controller are carried out reasonable combination by the method, make it both to have the fast and adaptable advantage of fuzzy logic control response, have again PID controller compared with high control precision.

The present invention solves its technical problem and takes following technical scheme to realize:

A kind of FLC-PID hybrid intelligent STATCOM control method, method step is as follows:

(1) selector switch automatically switches to PID controller: when voltage deviation absolute value | e|<1.5, fuzzy logic control deleterious, produce vibration, now selector switch is switched to PID controller, make STATCOM stable export required reactive power to system.

(2) selector switch automatically switches to FLC controller: when voltage deviation absolute value | and when e|>1.5, system startup has the fast FLC controller of dynamic response.

And FLC fuzzy logic control method is the controller of a dual input list output in form, input variable is respectively voltage error E and voltage error rate of change C _e, output variable is proportional integral constant K _p.

And, the linguistic variable of input, output is divided into 7 Linguistic Values, be: NB, NM, NS, Z, PS, PM, PB, fuzzy reasoning has 7 × 7=49 rule, and fuzzy rule base is as shown in the table:

Fuzzy rule minor function is determined:

$\mathrm{\&mu;}\left(x\right)=\left\{\begin{array}{c}\frac{1}{b-a}(x-a),a\&le;x<b\\ \frac{1}{b-c}(x-c),b\&le;x\&le;c\\ 0\\ \end{array}\right.$

And in the time that the absolute value of voltage error E becomes large, adjuster should mainly be brought into play proportional action, reduces integral action effect simultaneously; In the time that the absolute value of E diminishes, adjuster should mainly be brought into play integral action, reduces proportional action effect.

Advantage of the present invention and good effect are:

1, the present invention adopts the improvement mixing control method based on FLC and PID, makes up the underspeed of traditional PI D method aspect system dynamic response, has improved again near the self-oscillation that fuzzy logic control produces little value simultaneously.

2, the present invention adopts FLC-PID to mix the reactive power output of control STATCOM, step response speed is accelerated, and system can reach stable state quickly, and overshoot obviously reduces, improve significantly the dynamic property of STATCOM system, embodied good adaptive capacity and control effect.

Accompanying drawing explanation

Fig. 1 is the inverse system control structure figure in a kind of PID;

Fig. 2 is the system control structure figure in a kind of FLC;

Fig. 3 is FLC-PID hybrid intelligent STATCOM control method schematic diagram of the present invention.

Embodiment

Below in conjunction with accompanying drawing, the embodiment of the present invention is further described:

It is emphasized that; embodiment of the present invention is illustrative; rather than determinate; therefore the present invention is not limited to the embodiment described in embodiment; every other execution modes that drawn by those skilled in the art's technical scheme according to the present invention, belong to the scope of protection of the invention equally.

A kind of FLC-PID hybrid intelligent STATCOM control method, as shown in Figure 3, method step is as follows:

(1) when hour (| e|<1.5) of voltage deviation absolute value, voltage deviation approaches domain 0th district, fuzzy logic control deleterious, produce vibration, now selector switch automatically switches to PID controller, because PID controller steady-state behaviour is better and highly sensitive, make STATCOM stable export required reactive power to system.

(2), when voltage deviation absolute value large (| e|>1.5), system starts and has the fast FLC controller of dynamic response

(3) FLC fuzzy logic control method is the controller of a dual input list output in form, and input variable is respectively voltage error E and voltage error rate of change C _e, output variable is proportional integral constant K _p.

(4) linguistic variable of input, output is divided into 7 Linguistic Values, is: (NB, NM, NS, Z, PS, PM, PB), fuzzy reasoning has 7 × 7=49 rule, and fuzzy rule base is as shown in the table:

Fuzzy rule minor function is determined:

$\mathrm{\&mu;}\left(x\right)=\left\{\begin{array}{c}\frac{1}{b-a}(x-a),a\&le;x<b\\ \frac{1}{b-c}(x-c),b\&le;x\&le;c\\ 0\\ \end{array}\right.$

(5), in the time that the absolute value of voltage error E becomes large, adjuster should mainly be brought into play proportional action, reduces integral action effect simultaneously; In the time that the absolute value of E diminishes, adjuster should mainly be brought into play integral action, reduces proportional action effect.

Claims (4)

1. a FLC-PID hybrid intelligent STATCOM control method, is characterized in that: method step is as follows:

(1) selector switch automatically switches to PID controller: when voltage deviation absolute value | e|<1.5, fuzzy logic control deleterious, produce vibration, now selector switch is switched to PID controller, make STATCOM stable export required reactive power to system.

(2) selector switch automatically switches to FLC controller: when voltage deviation absolute value | and when e|>1.5, system startup has the fast FLC controller of dynamic response.

2. FLC-PID hybrid intelligent STATCOM control method according to claim 1, is characterized in that: FLC fuzzy logic control method is the controller of a dual input list output in form, and input variable is respectively voltage error E and voltage error rate of change C _e, output variable is proportional integral constant K _p.

3. FLC-PID hybrid intelligent STATCOM control method according to claim 2, it is characterized in that: the linguistic variable of input, output is divided into 7 Linguistic Values, be: NB, NM, NS, Z, PS, PM, PB, fuzzy reasoning has 7 × 7=49 rule, and fuzzy rule base is as shown in the table:

fuzzy rule minor function is determined:

$\mathrm{\&mu;}\left(x\right)=\left\{\begin{array}{c}\frac{1}{b-a}(x-a),a\&le;x<b\\ \frac{1}{b-c}(x-c),b\&le;x\&le;c\\ 0\\ \end{array}\right.$

4. according to the FLC-PID hybrid intelligent STATCOM control method described in claim 2 or 3, it is characterized in that: in the time that the absolute value of voltage error E becomes large, adjuster should mainly be brought into play proportional action, reduces integral action effect simultaneously; In the time that the absolute value of E diminishes, adjuster should mainly be brought into play integral action, reduces proportional action effect.

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