CN101938133B - Reverse blocking type IGBT (Insulated Gate Bipolar Translator) based compensating method of PWM (Pulse-Width Modulation) control capacitance type SVC (Static Var Compensator) - Google Patents

Abstract

The traditional reactive power compensation device compensates same reactive power to each phase of three phases, three-phase loads of a plurality of systems are not necessarily symmetrical, and the problems of overcompensation, undercompensation, and the like can occur during the simultaneous compensation of the three phases. The invention provides to a reverse blocking type IGBT (Insulated Gate Bipolar Translator) based compensating method of a PWM (Pulse-Width Modulation) control capacitance type SVC (Static Var Compensator), comprising the following compensating steps of: (1) acquiring voltage and current signals of an electricity grid system through a data acquisition device; (2) computing the size of the reactive power which needs to be compensated to the electricity grid system through a power computation module; (3) converting the reactive power from analog signals into digital signals through an A/D converter, and computing the size of duty ratio of triggering needed pulses through a PLC (Programmable Logic Controller) controller; (4) outputting pulse signals to a drive circuit of a reverse blocking type IGBT switch through a pulse output module, and realizing the continuous regulation of the equivalent capacitance of each continuous capacity regulation device in the three phases of a main circuit by regulating the size of the pulse duty ratio, therefore the purpose of regulating the reactive power is achieved.

Description

PWM control capacitance type SVC compensation method based on inverse-impedance type IGBT

Technical field

The present invention relates to the reactive-load compensation method of electric power system, specifically a kind of PWM control capacitance type SVC compensation method based on inverse-impedance type IGBT.

Background technology

Along with industrial expansion, a large amount of uses of precision instrument, the quality of voltage of electric power system more and more comes into one's own.In electric power system, voltage and frequency are to weigh two the most basic, most important indexs of the quality of power supply.For guaranteeing the normal operation of electric power system, supply power voltage and frequency must be stabilized in certain scope.The control of frequency and the control of active power are closely related, and one of voltage-controlled important method is that the reactive power of electric power system is controlled.Do not having under the prerequisite of reacance generator; Reactive power is mainly provided by generator in the system; Yet the idle meeting of system stability is occupied the inductive load of significant proportion in industry and the life consumes; Therefore will keep that voltage that user side and system side PCC order stablizes just must generation reactive power, i.e. reactive power compensation in the place of consume reactive power.

The main following points of the effect of reactive power compensation:

1, improves the power factor of electricity supplying and using system and load, reduce place capacity, reduce power loss.

2, stablize the voltage of receiving end and electrical network, improve power supply quality.Suitable place is provided with the stability that dynamic reactive compensation device can also improve transmission system in the power transmission line of long distance, improves ability to transmit electricity.

3,, can gaining merit of balance three-phase reach reactive load through suitable reactive power compensation in the unbalanced occasion of threephase load.

Early stage electric power system dynamic reactive compensation device commonly used has only compensator, and compensator comes down to be used for specially producing the synchronous motor of reactive power, but the same slewing that belongs to of compensator operation with generator; Complicated oil, water system are arranged; Loss in service and noise are all bigger, and operation maintenance is complicated, and response speed is slow; Be difficult to satisfy the requirement of quick dynamic compensation, it also is not suitable for too greatly or the reactive power compensation of low capacity too; To the seventies in last century; Because the appearance of power electronic device such as thyristor; Occurred based on thyristor-controlled reactor (TCR) and thyristor switchable capacitor (TSC); But based on the thyristor control technology reactive power compensator (SVC) can only regulate continuously the perception idle, can not regulate capacitive reactive power continuously; Since the eighties; Along with the development of power electronic technology, the absorption that STATCOM can be continuous or send idle has appearred based on the static passive compensation device (STATCOM) from the commutation convertor circuit; But because its control section complicacy and installation cost are higher, so also be not widely used.Following table has been listed the reactive power compensator pluses and minuses of developing based on existing reactive power compensation technology.

Therefore, seek that a kind of response speed is fast, control is simple, can send continuously and idlely can absorb idle compensation method again continuously and be necessary.

Summary of the invention

Technical problem to be solved by this invention is to overcome the defective that above-mentioned prior art exists; A kind of PWM control capacitance type SVC compensation method based on inverse-impedance type IGBT is provided, with reach quick response, control simple, can send continuously and idlely can absorb idle purpose continuously again.

For this reason; The present invention adopts following technical scheme: a kind of PWM control capacitance type SVC compensation method based on inverse-impedance type IGBT; It is characterized in that: each in the network system main circuit three-phase comprises a continuous apparatus for adjusting capacity and a definite value inductance parallelly connected with it mutually; Described continuous apparatus for adjusting capacity comprises two bidirectional switchs, and each bidirectional switch forms by two inverse-impedance type IGBT switch reverse parallel connections, the parallel connection behind the certain value electric capacity of respectively connecting of two bidirectional switchs; And then connect with a current-limiting inductance, the frequency of inverse-impedance type IGBT switch (being called for short RB-IGBT) is more than 10kHz.

Owing to the present invention is based on AC transmission system; Therefore switching circuit need adopt the switch combination circuit of two-way admittance, the inner collector and emitter of conventional IGBT two ends all inverse parallel a fly-wheel diode, whether IGBT cut-offs not influence of entire circuit; Because no matter IGBT triggering and conducting whether; Electric current can circulate through fly-wheel diode, and inverse-impedance type IGBT switch inside does not have parallelly connected fly-wheel diode, so avoided the generation of this kind situation.

Compensation process of the present invention is following: voltage, the current signal of 1) gathering network system through data acquisition unit; 2) big or small through the reactive power of the required compensation of power computation module calculating network system; 3) described reactive power becomes digital signal through A/D converter by analog signal conversion, in this digital signal input PLC controller, calculates triggering required pulse duty ratio size through the PLC controller; 4) through the drive circuit of pulse output module output pulse signal to inverse-impedance type IGBT switch; 5) computing formula of the equivalent capacity of said continuous apparatus for adjusting capacity size does

C in the formula ₁, C ₂The size of representing two above-mentioned definite value electric capacity; K representes the size of above-mentioned pulse duty factor; Draw from following formula, the size through the regulating impulse duty ratio can realize regulating continuously in the main circuit three-phase each equivalent capacity of apparatus for adjusting capacity continuously mutually, thereby reaches the purpose of regulating reactive power.

Described equivalent capacity C is at C ₁, C ₂In smaller value and C ₁+ C ₂Between change continuously.

The beneficial effect that the present invention has: 1) system side voltage, the current signal of the present invention through collecting; Confirm the reactive capability of the required compensation of system; Relation according to equivalent capacity and trigger impulse duty ratio; Through calculating trigger impulse duty ratio this moment, the compensation principle of the relative STATCOM device of control method is simple a lot, has good application prospect.

2) the present invention adopts inverse-impedance type IGBT to replace conventional IGBT, reduces the quantity of the power electronic device of device, reduces the wastage, increased reliability.

3) the present invention can realize that capacitive reactive power arrives perception idle continuous, smooth adjustment.

Below in conjunction with Figure of description and embodiment the present invention is described further.

Description of drawings

Fig. 1 is the single phase circuit figure of network system main circuit of the present invention.

Fig. 2 is a control impuls sketch map of the present invention.

(transverse axis is K to the curve that Fig. 3 changes with pulse duty factor K value for equivalent capacity C of the present invention, and the longitudinal axis is C, C ₁=100uF, C ₂During=500uF).

Relation curve (the C of Fig. 4 idle Q and pulse duty factor K for the present invention exports ₁=100uF, C ₂During=500uF).

Fig. 5 is the connection sketch map of compensation method device therefor of the present invention.

Fig. 6 is the single phase circuit figure of application implementation example of the present invention.

Embodiment

The single phase circuit of network system main circuit as shown in Figure 1, it is made up of a continuous apparatus for adjusting capacity and a definite value inductance L parallelly connected with it, in the incoming transport transmission of electricity electrical network.Described continuous apparatus for adjusting capacity comprises two bidirectional switchs, and each bidirectional switch forms by two inverse-impedance type IGBT switches (RB-IGBT) reverse parallel connection, two bidirectional switchs certain value capacitor C of respectively connecting ₁, C ₂Back parallel connection, and then with current-limiting inductance L ₀Connect with internal resistance R.

K ₁, K ₂Be the two-way start pulse signal of complementation, establishing its cycle is Δ t, and the switching frequency that the present invention selects for use is very fast, reaches more than the 10kHz, so the Δ t time is very short, this moment is owing to current-limiting inductance L in the circuit ₀Existence make when the RB-IGBT conducting the instantaneous capacitor C that flows through ₁, C ₂Electric current I ₁, I ₂With flow through current-limiting inductance L ₀On electric current I equate.

The electric current that flows through on the electric capacity can have computes:

is because Δ t is very short, so following formula also can be expressed as

Then ${\mathrm{\&Delta;\; <figure-callout\; id="1"\; label="U\; C"\; filenames="HDA0000026662680000021.png,HDA0000026662680000022.png"\; state="\{\{state\}\}">U</figure-callout>}}_C={\mathrm{\&Delta;\; t}}_1\frac{I_1}{C_1}---\left(2\right)$

${\mathrm{\&Delta;U}}_{C2}={\mathrm{\&Delta;t}}_2\frac{I_2}{C_2}---\left(3\right)$

In Δ t time pulse period, Δ U _C1Be Δ t action time ₁, Δ U _C2Be Δ t action time ₂, then in the action time of whole equivalent capacity Δ t, the voltage variety on the equivalent capacity does

$\mathrm{\&Delta;}{U}_C=\mathrm{\&Delta;}{\mathrm{<figure-callout\; id="1"\; label="U\; C"\; filenames="HDA0000026662680000021.png,HDA0000026662680000022.png"\; state="\{\{state\}\}">U</figure-callout>}}_C\frac{\mathrm{\&Delta;}{\mathrm{<figure-callout\; id="1"\; label="t"\; filenames="HDA0000026662680000021.png,HDA0000026662680000022.png"\; state="\{\{state\}\}">t</figure-callout>}}_1}{\mathrm{\&Delta;t}}+\mathrm{\&Delta;}{U}_{C2}\frac{{\mathrm{\&Delta;t}}_2}{\mathrm{\&Delta;t}}---\left(4\right)$

Formula (2) and formula (3) substitution following formula are got

${\mathrm{\&Delta;U}}_C={\mathrm{<figure-callout\; id="1"\; label="I"\; filenames="HDA0000026662680000021.png,HDA0000026662680000022.png"\; state="\{\{state\}\}">I</figure-callout>}}_1\frac{{{\mathrm{\&Delta;<figure-callout\; id="1"\; label="t"\; filenames="HDA0000026662680000021.png,HDA0000026662680000022.png"\; state="\{\{state\}\}">t</figure-callout>}}_1}^2}{\mathrm{\&Delta;t}*{\mathrm{<figure-callout\; id="1"\; label="C"\; filenames="HDA0000026662680000021.png,HDA0000026662680000022.png"\; state="\{\{state\}\}">C</figure-callout>}}_1}{+I}_2\frac{{{\mathrm{\&Delta;t}}_2}^2}{\mathrm{\&Delta;t}*C_2}---\left(5\right)$

Can know by formula (1) ${\mathrm{\&Delta;\; U}}_C=I\frac{\mathrm{\&Delta;\; t}}{C}---\left(6\right)$

Can know according to preceding surface analysis, because the Δ t time is very short, so transient current I, I ₁, I ₂Equate, formula (6) substitution formula (5) is got

$\frac{1}{C}=\frac{1}{C_1}{\left(\frac{{\mathrm{\&Delta;<figure-callout\; id="1"\; label="t"\; filenames="HDA0000026662680000021.png,HDA0000026662680000022.png"\; state="\{\{state\}\}">t</figure-callout>}}_1}{\mathrm{\&Delta;t}}\right)}^2+\frac{1}{C_2}{\left(\frac{{\mathrm{\&Delta;t}}_2}{\mathrm{\&Delta;t}}\right)}^2---\left(7\right)$

Remember that pulse duty factor substitution following formula is put in order

$C=\frac{C_1{C}_2}{({\mathrm{<figure-callout\; id="1"\; label="C"\; filenames="HDA0000026662680000021.png,HDA0000026662680000022.png"\; state="\{\{state\}\}">C</figure-callout>}}_1+C_2)K^2-2C_{1}K+C_1}---\left(8\right)$

Can find out by following formula, because capacitor C ₁, C ₂Value is fixed value, and through changing the duty ratio K of RB-IGBT trigger impulse, the size that can regulate equivalent capacity C continuously asks extreme value analysis to know, when The time, it is C that equivalent capacity C gets maximum ₁+ C ₂, when K got near limiting value 0 or 1, equivalent capacity was respectively C ₁Or C ₂, promptly only drop into capacitor C ₁And C ₂In one.

In sum, can realize regulating continuously the purpose of equivalent capacity through the size of regulating impulse duty ratio, the excursion of equivalent capacity C is at C ₁, C ₂In smaller value and C ₁+ C ₂Between change continuously.For example get C ₁=100uF, C ₂=500uF, as shown in Figure 3 with the curve that pulse duty factor changes according to formula (8) with the Matlab equivalent capacity C that draws.

Because the present invention is at equivalent capacity C two ends and met a fixed inductance L, when the value of equivalent capacity C makes the electric current that flows through electric capacity when flowing through the electric current of fixed inductance L, it is idle that whole device sends perception; When the value of equivalent capacity C makes the electric current that flows through electric capacity when flowing through the electric current of fixed inductance L, whole device sends capacitive reactive power.So just can reach and to send continuous capacitive reactive power and can send the idle purpose of continuous perception again.For example, when getting system voltage U=220V, fixed inductance L=0.038H, capacitor C ₁=100uF, C ₂=500uF, the relation curve of then idle output and pulse duty factor is as shown in Figure 4.

As shown in Figure 5, the step that the present invention compensates is following: voltage, the current signal of 1) gathering network system through data acquisition unit; 2) big or small through the reactive power of the required compensation of power computation module calculating network system; 3) described reactive power becomes digital signal through A/D converter by analog signal conversion, in this digital signal input PLC controller, calculates triggering required pulse duty ratio size through the PLC controller; 4) through the drive circuit of pulse output module output pulse signal to inverse-impedance type IGBT switch.Described PLC controller is connected with touch-screen through data wire, is used for video data.

As shown in Figure 6, the voltage U=220V of initialization system side, fixed inductance L=50mH, internal resistance and current-limiting inductance are all very little, and its impedance is ignored, capacitor C ₁=100uF, capacitor C ₂=500uF, system load apparent power S=P+jQ=5 * 10 ³+ j3.75 * 10 ³, then this moment load place system power factor

(perception), the perceptual reactive power consumption of load is Q=3.75 * 10 ³Var confirms capacitive reactive power Q=3.75 * 10 that this moment, system need compensate by the compensation way of compensation power factor to 1 ³Var is by Q=ω C*U ²Can get the equivalent capacity of whole device this moment The equivalent capacity C parallel connection of fixed inductance L and apparatus for adjusting capacity output continuously among Fig. 6 is by the parallel impedance formula

C with previous calculations ₀Value and known fixed inductance L value substitution following formula draw the equivalent capacity C=449.60uF of this moment, in conjunction with C ₁=100uF, C ₂=500uF, substitution formula (8) can calculate the duty ratio K=0.38 or-0.05 of required pulse, because pulse duty factor can not be negative, so get K=0.38.Confirm to give corresponding pulse output module (FPGA device) order again after the duty ratio of trigger impulse, send needed pulse duty factor, and then reach the idle purpose of compensated line.

Annotate: can know by Fig. 3, when calculating the equivalent capacity C=550uF of the continuous apparatus for adjusting capacity output of gained, can know that through calculating this moment, duty ratio K value had two reasonably to separate, at this moment only need appoint therein and get value conduct and export duty of ratio and get final product.

Claims (3)

1. PWM control capacitance type SVC compensation method based on inverse-impedance type IGBT; It is characterized in that: each in the network system main circuit three-phase comprises a continuous apparatus for adjusting capacity and a definite value inductance parallelly connected with it mutually; Described continuous apparatus for adjusting capacity comprises two bidirectional switchs; Each bidirectional switch forms by two inverse-impedance type IGBT switch reverse parallel connections; The parallel connection behind the certain value electric capacity of respectively connecting of two bidirectional switchs, and then connect with a current-limiting inductance, the frequency of inverse-impedance type IGBT switch is more than 10kHz;

Compensation process is following: voltage, the current signal of 1) gathering network system through data acquisition unit; 2) big or small through the reactive power of the required compensation of power computation module calculating network system; 3) described reactive power becomes digital signal through A/D converter by analog signal conversion, in this digital signal input PLC controller, calculates triggering required pulse duty ratio size through the PLC controller; 4) through the drive circuit of pulse output module output pulse signal to inverse-impedance type IGBT switch; 5) computing formula of the equivalent capacity of said continuous apparatus for adjusting capacity size does

C in the formula ₁, C ₂The size of representing two above-mentioned definite value electric capacity; K representes the size of above-mentioned pulse duty factor; Draw from following formula, the size through the regulating impulse duty ratio can realize regulating continuously in the main circuit three-phase each equivalent capacity of apparatus for adjusting capacity continuously mutually, thereby reaches the purpose of regulating reactive power.

2. the PWM control capacitance type SVC compensation method based on inverse-impedance type IGBT according to claim 1 is characterized in that described equivalent capacity C is at C ₁, C ₂In smaller value and C ₁+ C ₂Between change continuously.

3. the PWM control capacitance type SVC compensation method based on inverse-impedance type IGBT according to claim 1 and 2 is characterized in that described PLC controller is connected with a touch-screen through data wire.

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