CN103779866A - M and delta comprehensive optimization control method applicable to SVG - Google Patents

Abstract

The invention discloses an M and delta comprehensive optimization control method applicable to an SVG. The M and delta comprehensive optimization control method comprises the steps of obtaining a function relationship form among a current output by the SVG, the delta and the M on the premise of maintaining udc to be constant, obtaining the current which should be output by the SVG according to real-time extraction of a three-phase power grid phase current, and using the current output by the SVG as a control target current reference value; selecting the M and the delta corresponding to the control target current reference value in the function relationship form to adjust and control the current output by the SVG; when the current output by the SVG reaches the reserved proportion of the control target current reference value, conducting fine tuning on the delta and the M according to u*cd and u*cq. According to the M and delta comprehensive optimization control method, the dynamic performance of the SVG is remarkably improved, the step response time of the SVG is greatly shortened, the overshoot of an offset current obtained when an idle jumping is output is greatly reduced, the stabilization response time of the SVG is shortened, the margin of a device and a power device can be reduced, the cost of the device is reduced, and the comprehensive performance of the SVG is remarkably improved.

Description

A kind of M, δ integrated optimization control method that is applicable to SVG

Technical field

The present invention relates to high-tension electricity electronics Semiconductor Converting Technology field, more specifically relate to M, the δ integrated optimization control method of a kind of SVG of being applicable to, it is applicable to that electrical network is implemented to high performance harmonic wave and suppresses and reactive power compensation.

Background technology

Along with the high speed development of modern industry, the non-linear impact loads such as high power electronic equipment, metallurgical arc furnace and rolling mill are widely applied, the renewable energy power generation developing rapidly grid-connected, these have all brought more and more serious idle problem and harmonic pollution to electrical network, voltage ripple of power network and waveform are distorted, the safety that causes the quality of power supply to decline and threaten electrical network.So, flexible AC transmitting system (Flexible AC Transmission System, FACTS) the development tool of modern humans society is of great significance, and advanced SVG (Stetic Var Generator) is basic technology and the key equipment of flexible AC transmitting system, the main circuit topology of modern SVG adopts chain structure more, with IGBT(or IGCT, and the link unit of capacitor composition H bridge commutation inversion IEGT), be composed in series change of current chain with multiple link units, three change of current chains are connected by triangle (or star) respectively with after three linked reactor series connection, be connected to again electrical network, by controlling amplitude and the phase place of change of current chain output voltage, regulate reactive power compensation electric current (comprising inductance current or the capacity current) size of injecting to electrical network, its Main Function is:

A). safeguard Network Voltage Stability, improve the quality of power supply

SVG is by injecting perception or capacitive reactive power to electrical network dynamically continuously, improving in real time power system reactive power distributes, thereby can in given range, realize Network Voltage Stability control, power factor and delivery of electrical energy efficiency are improved, suppress low frequency oscillations and dynamically overvoltage, improve the quality of power supply.

B). improve ability and the Transient Stability Level of the low voltage crossing of electrical network

In the time that electrical network generation voltage falls fault, SVG can be for electrical network Quick be for reactive power support, reduce low pressure and discharge load quantity, improve the fault extreme mute time of electrical network, simultaneously for the time has been won in the recovery of electrical network, avoided electrical network because instantaneous voltage falls fault off-the-line, the low voltage ride-through capability that has improved electrical network also can improve the transient stability of electrical network.

As shown in Figure 2, if symmetry system having symmetry, without high order harmonic component, three-phase system voltage can be expressed as existing control algolithm block diagram:

$\left\{\begin{array}{c}{u}_{\mathrm{sa}}=U_{\mathrm{sm}}\cos \mathrm{\ωt}\\ u_{\mathrm{sb}}=U_{\mathrm{sm}}\cos (\mathrm{\ωt}-\frac{2\mathrm{\π}}{3})\\ u_{\mathrm{sc}}=U_{\mathrm{sm}}\cos (\mathrm{\πt}+\frac{2\mathrm{\π}}{3})\end{array}\right.$

The three-phase voltage of SVG output can be expressed as:

$\left\{\begin{array}{c}{u}_{\mathrm{ca}}={\mathrm{MU}}_{\mathrm{dc}}\cos (\mathrm{\ωt}+\mathrm{\δ})\\ u_{\mathrm{cb}}={\mathrm{MU}}_{\mathrm{dc}}\cos (\mathrm{\ωt}-\frac{2\mathrm{\π}}{3}+\mathrm{\δ})\\ u_{\mathrm{dc}}={\mathrm{MU}}_{\mathrm{dc}}\cos (\mathrm{\ωt}+\frac{2\mathrm{\π}}{3}+\mathrm{\δ})\end{array}\right.$

In formula, Usm is system phase voltage amplitude, the modulation ratio that M is SVG, u _dc=Nudc is all DC capacitor voltage sums of change of current chain, and δ is the phase angle difference between system voltage and SVG output voltage.For regulation output idle, need to regulate MNudc, regulate M and udc simultaneously, at needs, significantly regulation output is idle, or mutually when saltus step, needs significantly to regulate each chain element to meet DC capacitor voltage udc between output is idle from capacitive reactive power to perception, because capacitance voltage can not suddenly change, cause the bad dynamic performance of SVG, the step response time of device is long, dynamic compensation degradation; Affect the performance of SVG dynamic compensation ability.In addition, at needs, significantly regulation output is idle, or between output is idle from capacitive reactive power to perception mutually when saltus step, due to the I between control target current and its actual output current of SVG ^* _cq-I _cq, I ^* _cd-I _cddifference is very large, brings difficulty to the Proportional coefficient K p of pi regulator and the choose reasonable of integral coefficient Ki, is improving dynamic property and is preventing that overshoot overshoot is difficult to take into account between the two.

Therefore, mostly there is above-mentioned defect and the not enough performance that has affected to a great extent SVG quick performance because of its control method in existing SVG, and main defect shows as the following aspects:

A). large capacity impact load tends to cause the flickering of line voltage, this just requires SVG to have good dynamic property, and because existing control method is in the time regulating the output of SVG idle, all need to regulate the DC capacitor voltage udc of each link unit in change of current chain simultaneously, because capacitance voltage can not suddenly change, cause the bad dynamic performance of SVG, the step response time of device is long, dynamic compensation degradation; Affect the performance of SVG dynamic compensation ability.

B). same defect and deficiency because of existing control method, in the time of the idle generation saltus step of output, offset current can produce overshoot, the catch time of device is long, reduces its reliability, need to increase the surplus of power device and device, increase installation cost, electrical network is impacted simultaneously.

Summary of the invention

The object of the invention is to the deficiency existing for prior art, M, the δ integrated optimization control method of a kind of SVG of being applicable to are provided, obviously improved the dynamic compensation performance of SVG, substantially suppressed to export the overshoot of the output current that idle saltus step causes.To guarantee the stable of line voltage, the combination property of SVG and the reliability of device are greatly improved.

The present invention is achieved through the following technical solutions:

The M, the δ integrated optimization control method that are applicable to SVG, is characterized in that, comprises the following steps:

Step 1: obtain and maintaining u _dcsVG output current under constant prerequisite and the functional relation list between δ and M, wherein, u _dcfor each link unit DC capacitor voltage in SVG; M is the modulation ratio of SVG, and δ is the phase angle difference between system voltage and SVG output voltage;

Step 2: according to extract real-time three phase network phase current draw the electric current that SVG should export

and as controlling target current reference value;

Step 3: the output current of choosing the M corresponding with controlling target current reference value and δ regulation and control SVG in functional relation list;

Step 4: in the time that the output current of SVG reaches the predetermined ratio of controlling target current reference value, the output active voltage by SVG under dq coordinate output reactive voltage with SVG under dq coordinate

δ and M are finely tuned

$M=\frac{\sqrt{{{u^{*}}_{\mathrm{cd}}}^2+{{u^{*}}_{\mathrm{cq}}}^2}}{{\mathrm{Nu}}_{\mathrm{dc}}}$

$\mathrm{\δ}={\mathrm{tg}}^{-1}\frac{{u^{*}}_{\mathrm{cd}}}{{u^{*}}_{\mathrm{cq}}}$

In formula,

for the output active voltage of SVG under dq coordinate,

for the output reactive voltage of SVG under dq coordinate, u _dcfor each link unit DC capacitor voltage in SVG, the link unit number that N comprises for each change of current chain.

The acquisition of functional relation list as above comprises the following steps:

Step 1.1, to SVG implement field measurement:

Step 1.1.1, a M value of setting, regulate δ to make u _dcremain constant, i.e. u _dc=u _dch, be wherein u _dchfor rated value;

Step 1.1.2, record the now output current of SVG

obtain one group with

corresponding δ and M;

Step 1.1.3, repetition above-mentioned steps 1.1.1-1.1.2, until complete actual measurement, obtain all output currents

with the corresponding relation of δ and M,

Step 1.2, calculate according to formula:

Step 1.2.1, choose the SVG output current obtaining in a step 1.1.3

Step 1.2.2, according to following formula:

ask for the output voltage of SVG

in formula for line voltage,

for the output voltage of SVG, the inductance that L is linked reactor, ω is first-harmonic angular frequency,

for the output current of a SVG choosing in step 1.2.1;

Step 1.2.3, to what obtain in step 1.2.2

carrying out abc/dqo coordinate transform asks for

for the output active voltage of SVG under dq coordinate,

for the output reactive voltage of SVG under dq coordinate;

Step 1.2.4, by what obtain in step 1.2.3

in calculating and step 1.2.1, choose

corresponding M, δ;

Based on following formula: $M=\frac{\sqrt{{{u^{*}}_{\mathrm{cd}}}^2+{{u^{*}}_{\mathrm{cq}}}^2}}{{\mathrm{Nu}}_{\mathrm{dc}}},$ $\mathrm{\δ}={\mathrm{tg}}^{-1}\frac{{u^{*}}_{\mathrm{cd}}}{{u^{*}}_{\mathrm{cq}}}$

In formula,

for the output active voltage of SVG under dq coordinate, for the output reactive voltage of SVG under dq coordinate, u _dcfor each link unit DC capacitor voltage in SVG, the link unit number that N comprises for each change of current chain;

Step 1.2.5, repeating step 1.2.1-1.2.4, until obtain in step 1.1.3 all

corresponding M, δ;

Step 1.3, general

m in corresponding step 1.1.3 and same

the M obtaining in corresponding step 1.2.4 averages as in functional relation list

corresponding M value;

Will δ in corresponding step 1.1.3 and same

the δ obtaining in corresponding step 1.2.4 averages as in functional relation list

corresponding δ value.

Step 3 as above comprises the following steps, and Selection of Function is related in list and controls target current reference value difference minimum

corresponding M and δ.

Step 3 as above comprises the following steps, and functional relation list is fitted to respectively

curve and

curve, in above-mentioned two curves, search respectively corresponding δ and M according to controlling target current reference value.

The present invention compared with prior art, has following beneficial effect:

1. compared with traditional control method, the present invention significantly improves the dynamic property of SVG, greatly reduces the step response time of SVG.

2. compared with traditional control method, the overshoot of offset current when the present invention has reduced to export idle saltus step greatly, reduces calm response time of SVG, can reduce the surplus of device and power device, has reduced installation cost, has significantly improved the combination property of SVG.

Accompanying drawing explanation

Fig. 1 is control method block diagram of the present invention;

Fig. 2 is existing control method block diagram;

Fig. 3 is the output waveform while adopting the SVG of control method of the present invention to jump to output 8.5M capacitive reactive power from output 8.5M perception is idle;

To be the SVG that adopts control method of the present invention jump to the output waveform of output 8.5M perception when idle from output 8.5M capacitive reactive power to Fig. 4;

To be the SVG that adopts control method of the present invention jump to the output waveform of output 8.5M perception when idle from 0 idle output to Fig. 5;

Fig. 6 is the output waveform while adopting the SVG of control method of the present invention to jump to 0 idle output from output 8.5M capacitive reactive power.

Embodiment

Below in conjunction with accompanying drawing and embodiment, the invention will be further described.

Be applicable to M, a δ integrated optimization control method of SVG,

In the time of the output reactive power of regulation and control SVG, the phase angle difference δ between complex optimum control modulation ratio M and SVG output voltage and system voltage simultaneously.

In the time regulating the output reactive power of SVG, all the time simultaneously the DC capacitor voltage u of each power cell _dcmaintain the main goal of regulation and control of constant conduct.

Calculate in advance mapping and be stored in master control and maintaining u _dcsVG output current under constant prerequisite

functional relation list δ=f between (containing flowing into the perceptual reactive current of SVG or the capacitive reactive power electric current of outflow SVG) and δ and M ₁(I _ca, I _cb, I _cc), M=f ₂(I _ca, I _cb, I _cc).

Control algolithm comprises following steps:

Step 1: be stored in advance u in master control _dcmaintain SVG output current I under constant prerequisite _ca, I _cb, I _ccand the functional relation list δ=f1 (I between δ and M _ca, I _cb, I _cc), M=f2 (I _ca, I _cb, I _cc).The manufacture method of functional relation list adopts comprehensive (the getting its mean value) of following two kinds of modes:

Step 1.1, to device implement field measurement:

Step 1.1.1, a M value of setting, regulate δ to make u _dcremain constant, i.e. u _dc=u _dch, be wherein u _dchfor rated value, u _dcfor each link unit DC capacitor voltage in SVG.

Step 1.1.2, record the now output current of SVG

obtain one group

the data corresponding with δ and M.

Step 1.1.3, repetition above-mentioned steps, until complete actual measurement, obtain all output currents

with the corresponding relation of δ and M, data acquisition density is depending on capacity and the required precision of SVG.

Step 1.2, calculate according to formula:

Step 1.2.1, choose the SVG output current obtaining in a step 1.1.3

Step 1.2.2, according to following formula:

ask for the output voltage of SVG

in formula

for line voltage,

for the output voltage of SVG, the inductance that L is linked reactor, ω is first-harmonic angular frequency,

for the output current of a SVG choosing in step 1.2.1.

Step 1.2.3, to what obtain in step 1.2.2

carrying out abc/dqo coordinate transform asks for

for the output active voltage of SVG under dq coordinate,

for the output reactive voltage of SVG under dq coordinate.

Step 1.2.4, pass through

in calculating and step 1.2.1, choose

corresponding M, δ.

Based on following formula: $M=\frac{\sqrt{{{u^{*}}_{\mathrm{cd}}}^2+{{u^{*}}_{\mathrm{cq}}}^2}}{{\mathrm{Nu}}_{\mathrm{dc}}},$ $\mathrm{\δ}={\mathrm{tg}}^{-1}\frac{{u^{*}}_{\mathrm{cd}}}{{u^{*}}_{\mathrm{cq}}}$

In formula,

for the output active voltage of SVG under dq coordinate,

for the output reactive voltage of SVG under dq coordinate, u _dcfor each link unit DC capacitor voltage in SVG, the link number that N comprises for each change of current chain.

Step 1.2.5, repeating step 1.2.1-1.2.4, until obtain in step 1.1.3 all

corresponding M, δ;

Step 1.3, general m in corresponding step 1.1.3 and same

the M obtaining in corresponding step 1.2.4 averages as in functional relation list

corresponding M value;

Will

δ in corresponding step 1.1.3 and same the δ obtaining in corresponding step 1.2.4 averages as in functional relation list

corresponding δ value.

Step 2: extract real-time three phase network phase current

it is processed and implement abc/dqo coordinate transform, LPF digital low-pass filtering, dq0/abc inverse transformation, draw the electric current that SVG should export

and set it as and control target current reference value;

Step 3: according to controlling target current reference value, choose M and δ in functional relation list, be used for the output current of SVG.

The mode of choosing has two kinds:

First kind of way: Selection of Function is related in list and controls target current reference value difference minimum

corresponding M and δ.

The second way: functional relation list is fitted to respectively

curve with δ

curve with M

in above-mentioned two curves, search respectively corresponding δ and M according to controlling target current reference value.

Step 4: in the time that the output current (effective value) of SVG reaches the predetermined ratio of controlling target current reference value, control mode proceeds to according to following formula δ and M are finely tuned

$M=\frac{\sqrt{{{u^{*}}_{\mathrm{cd}}}^2+{{u^{*}}_{\mathrm{cq}}}^2}}{{\mathrm{Nu}}_{\mathrm{dc}}}$

$\mathrm{\δ}={\mathrm{tg}}^{-1}\frac{{u^{*}}_{\mathrm{cd}}}{{u^{*}}_{\mathrm{cq}}}$

${u^{*}}_{\mathrm{cq}}=-(K_p+\frac{K_i}{S})({I^{*}}_{\mathrm{cq}}-I_{\mathrm{cq}})-\mathrm{\ω}\×L\×I_{\mathrm{cd}}$

${u^{*}}_{\mathrm{cd}}=-(K_p+\frac{K_i}{S})({I^{*}}_{\mathrm{cd}}-I_{\mathrm{cd}})+\mathrm{\ω}\×L\×I_{\mathrm{cq}}+u_{\mathrm{sd}}$

In formula, K _pfor proportionality coefficient, the K of PI controller _ifor integral coefficient, ω is first-harmonic angular frequency, the inductance value that L is linked reactor, and S is integral operator,

for the output active voltage of SVG under dq coordinate, for reactive voltage,

for the idle instruction current of output of SVG under dq coordinate, I _cqfor the output reactive current of SVG under dq coordinate,

for the meritorious instruction current of output of SVG under dq coordinate, I _cdfor the output active current of SVG under dq coordinate, u _sdfor the real component of line voltage under dq coordinate, u _dcfor each link unit DC capacitor voltage in SVG, the link unit number that N comprises for each change of current chain.

Fig. 3～Figure 6 shows that the output waveform of the SVG that adopts control method of the present invention, the electric pressure of SVG is 10KV, Y type connects, rated capacity 10Mvar.

Fig. 3 is the output waveform while adopting the SVG of control method of the present invention to jump to output 8.5M M capacitive reactive power from output 8.5M perception is idle, and waveform shows, the step response time of SVG is less than 5ms, and the calm response time of SVG is less than 10ms;

To be the SVG that adopts control method of the present invention jump to the output waveform of output 8.5M perception when idle from output 8.5M capacitive reactive power to Fig. 4, and waveform shows, the step response time of SVG is less than 5ms, and the calm response time of SVG is less than 10ms;

To be the SVG that adopts control method of the present invention jump to the output waveform of output 8.5M perception when idle from 0 idle output to Fig. 5, and waveform shows, the step response time of SVG is less than 5ms, and the calm response time of SVG is less than 10ms;

Fig. 6 is the output waveform while adopting the SVG of control method of the present invention to jump to 0 idle output from output 8.5M capacitive reactive power, and waveform shows, the step response time of SVG is less than 5ms, and the calm response time of SVG is less than 10ms.

Specific embodiment described herein is only to the explanation for example of the present invention's spirit.Those skilled in the art can make various modifications or supplement or adopt similar mode to substitute described specific embodiment, but can't depart from spirit of the present invention or surmount the defined scope of appended claims.

Claims (4)

1. the M, the δ integrated optimization control method that are applicable to SVG, is characterized in that, comprises the following steps:

Step 1: obtain and maintaining u _dcsVG output current under constant prerequisite and the functional relation list between δ and M, wherein, u _dcfor each link unit DC capacitor voltage in SVG, the modulation ratio that M is SVG, δ is the phase angle difference between system voltage and SVG output voltage;

Step 2: according to extract real-time three phase network phase current

draw the electric current that SVG should export

and as controlling target current reference value;

Step 3: the output current of choosing the M corresponding with controlling target current reference value and δ regulation and control SVG in functional relation list;

Step 4: in the time that the output current of SVG reaches the predetermined ratio of controlling target current reference value, pass through

with

δ and M are finely tuned

$M=\frac{\sqrt{{{u^{*}}_{\mathrm{cd}}}^2+{{u^{*}}_{\mathrm{cq}}}^2}}{{\mathrm{Nu}}_{\mathrm{dc}}}$

$\mathrm{\δ}={\mathrm{tg}}^{-1}\frac{{u^{*}}_{\mathrm{cd}}}{{u^{*}}_{\mathrm{cq}}}$

In formula,

for the output active voltage of SVG under dq coordinate,

for the output reactive voltage of SVG under dq coordinate, the link unit number that N comprises for each change of current chain.

2. a kind of M, δ integrated optimization control method that is applicable to SVG according to claim 1, is characterized in that, the acquisition of described functional relation list comprises the following steps:

Step 1.1, to SVG implement field measurement:

Step 1.1.1, a M value of setting, regulate δ to make u _dcremain constant, i.e. u _dc=u _dch, be wherein u _dchfor rated value;

Step 1.1.2, record the now output current of SVG

obtain one group with

corresponding δ and M;

Step 1.1.3, repetition above-mentioned steps 1.1.1-1.1.2, until complete actual measurement, obtain all output currents

with the corresponding relation of δ and M,

Step 1.2, calculate according to formula:

Step 1.2.1, choose the SVG output current obtaining in a step 1.1.3

Step 1.2.2, according to following formula:

ask for the output voltage of SVG

in formula

for line voltage, the inductance that L is linked reactor, ω is first-harmonic angular frequency,

for the output current of a SVG choosing in step 1.2.1;

Step 1.2.3, to what obtain in step 1.2.2

carrying out abc/dqo coordinate transform asks for

Step 1.2.4, by what obtain in step 1.2.3 in calculating and step 1.2.1, choose

corresponding M, δ;

Based on following formula: $M=\frac{\sqrt{{{u^{*}}_{\mathrm{cd}}}^2+{{u^{*}}_{\mathrm{cq}}}^2}}{{\mathrm{Nu}}_{\mathrm{dc}}},$ $\mathrm{\δ}={\mathrm{tg}}^{-1}\frac{{u^{*}}_{\mathrm{cd}}}{{u^{*}}_{\mathrm{cq}}}$

Step 1.2.5, repeating step 1.2.1-1.2.4, until obtain in step 1.1.3 all corresponding M, δ;

Step 1.3, general

m in corresponding step 1.1.3 and same

the M obtaining in corresponding step 1.2.4 averages as in functional relation list

corresponding M value;

Will δ in corresponding step 1.1.3 and same

the δ obtaining in corresponding step 1.2.4 averages as in functional relation list

corresponding δ value.

3. a kind of M, δ integrated optimization control method that is applicable to SVG according to claim 1, is characterized in that, described step 3 comprises the following steps, and Selection of Function is related in list and controls target current reference value difference minimum

corresponding M and δ.

4. a kind of M, δ integrated optimization control method that is applicable to SVG according to claim 1, is characterized in that, described step 3 comprises the following steps, and functional relation list is fitted to respectively curve and

curve, in above-mentioned two curves, search respectively corresponding δ and M according to controlling target current reference value.

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