CN103779866B - A kind of M, δ integrated optimization control method being applicable to SVG - Google Patents

Abstract

The invention discloses a kind of M, δ integrated optimization control method being applicable to SVG, obtain at maintenance u _dcsVG output current under constant prerequisite and the functional relation list between δ and M, according to extract real-time three phase network phase current draw the electric current that SVG should export and as control objectives current reference value; The output current that M and δ corresponding with control objectives current reference value regulates and controls SVG is chosen in functional relation list; When the output current of SVG reaches the predetermined ratio of control objectives current reference value, pass through with δ and M is finely tuned.The present invention significantly improves the dynamic property of SVG, greatly reduces the step response time of SVG; When greatly reducing to export idle saltus step, the overshoot of offset current, reduces the calm response time of SVG, can reduce the surplus of device and power device, reduce installation cost, significantly improve the combination property of SVG.

Description

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

Technical field

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

Background technology

Along with the high speed development of modern industry, the nonlinear scale spaces loads such as high power electronic equipment, metallurgical arc furnace and rolling mill are widely applied, the renewable energy power generation developed rapidly grid-connected, these all bring more and more serious idle problem and harmonic pollution to electrical network, voltage ripple of power network and waveform are distorted, causes the quality of power supply to decline and threaten the safety of electrical network.So, flexible AC transmitting system (FlexibleACTransmissionSystem, FACTS) the development tool of modern humans society is of great significance, and the SVG of advanced person (SteticVarGenerator) is basic technology and the key equipment of flexible AC transmitting system, main circuit topology many employings chain structure of modern SVG, with IGBT (or IGCT, and the link unit of capacitor composition H bridge commutation inversion IEGT), change of current chain is composed in series with multiple link unit, be connected by triangle (or star) after three change of current chains are connected with three linked reactors respectively, be connected to electrical network again, 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 injected to electrical network, its Main Function is:

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

SVG injects perception or capacitive reactive power by dynamic continuously to electrical network, the real-time power system reactive power that improves distributes, thus Network Voltage Stability control can be realized in given range, improve power factor and delivery of electrical energy efficiency, suppress low frequency oscillations and dynamic over-voltage, improve the quality of power supply.

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

When electrical network generation Voltage Drop fault, SVG can for electrical network Quick be for reactive power support, reduce low pressure release load quantity, improve the fault extreme mute time of electrical network, simultaneously for the time has been won in the recovery of electrical network, avoid electrical network because of instantaneous voltage sag fault off-the-line, improve the low voltage ride-through capability of electrical network and the transient stability of electrical network can be improved.

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

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

The three-phase voltage that SVG exports can be expressed as:

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

In formula, U _smfor system phase voltage amplitude, M is the modulation ratio of SVG, U _dc=Nudc is an all DC capacitor voltage sum of change of current chain, and δ is the phase angle difference between system voltage and SVG output voltage.In order to regulation output is idle, then need to regulate MNudc, namely regulate M and udc simultaneously, at needs, significantly regulation output is idle, or between output is idle from capacitive reactive power to perception during mutual saltus step, then needs significantly to regulate each chain element to meet DC capacitor voltage udc, 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; Have impact on the performance of SVG dynamic compensation ability.In addition, at needs, significantly regulation output is idle, or export idle from capacitive reactive power to perception between mutually saltus step time, due to the I between the control objectives electric current of SVG and its actual output current ^* _cq-I _cq, I ^* _cd-I _cddifference is very large, brings difficulty to the choose reasonable of the Proportional coefficient K p of pi regulator and integral coefficient Ki, is improving dynamic property and is preventing overshoot overshoot to be difficult to take into account between the two.

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

A). Large Copacity impact load often causes the flickering of line voltage, this just requires that SVG has good dynamic property, and because existing control method is when regulating the output of SVG idle, all need the DC capacitor voltage udc simultaneously regulating each link unit in change of current chain, 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; Have impact on the performance of SVG dynamic compensation ability.

B). same because the defect of existing control method and deficiency, when exporting idle generation saltus step, offset current can produce overshoot, the catch time of device is long, reduces its reliability, needs the surplus increasing 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 existed for prior art, a kind of M, δ integrated optimization control method being applicable to SVG is provided, significantly improve the dynamic compensation performance of SVG, substantially inhibit the overshoot exporting the output current that idle saltus step causes.To guarantee the stable of line voltage, substantially increase the combination property of SVG and the reliability of device.

The present invention is achieved through the following technical solutions:

Be applicable to M, δ integrated optimization control method of SVG, it is characterized in that, comprise the following steps:

Step 1: obtain at maintenance u _dcsVG output current under constant prerequisite and the functional relation list between δ and M, wherein, u _dcfor link unit DC capacitor voltage each 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 control objectives current reference value;

Step 3: choose the output current that M and δ corresponding with control objectives current reference value regulates and controls SVG in functional relation list;

Step 4: when the output current of SVG reaches the predetermined ratio of control objectives current reference value, by the output active voltage u of SVG under dq coordinate ^* _cdwith the output reactive voltage u of SVG under dq coordinate ^* _cqδ and M is finely tuned

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

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

In formula, u ^* _cdfor output active voltage, the u of SVG under dq coordinate ^* _cqfor the output reactive voltage of SVG under dq coordinate, u _dcfor link unit DC capacitor voltage each 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 setting M value, regulate δ to make u _dcmaintain constant, i.e. u _dc=u _dch, be wherein u _dchfor rated value;

Step 1.1.2, record the output current of now 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, according to formulae discovery:

Step 1.2.1, choose the SVG output current obtained 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, L is the inductance of linked reactor, and ω is first-harmonic angular frequency, for the output current of a SVG chosen in step 1.2.1;

Step 1.2.3, to what obtain in step 1.2.2 carry out abc/dqo coordinate transform and ask for u ^* _cd, u ^* _cq, u ^* _cdfor output active voltage, the u of SVG under dq coordinate ^* _cqfor the output reactive voltage of SVG under dq coordinate;

Step 1.2.4, u by obtaining in step 1.2.3 ^* _cd, u ^* _cqcalculate and choose in step 1.2.1 corresponding M, δ;

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

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

Step 1.2.5, repetition 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 obtained 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 obtained in corresponding step 1.2.4 averages as in functional relation list corresponding δ value.

Step 3 as above comprises the following steps, minimum with control objectives current reference value difference in Selection of Function relation list corresponding M and δ.

Step 3 as above comprises the following steps, and is fitted to respectively by functional relation list curve and curve, in above-mentioned two curves, search corresponding δ and M respectively according to control objectives 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 present invention substantially reduces the overshoot of offset current when exporting idle saltus step, reduces the calm response time of SVG, can reduce the surplus of device and power device, reduce installation cost, significantly improve 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 adopts the SVG of control method of the present invention from exporting the idle output waveform jumped to when exporting 8.5M capacitive reactive power of 8.5M perception;

Fig. 4 be adopt the SVG of control method of the present invention from export 8.5M capacitive reactive power jump to export 8.5M perception idle time output waveform;

Fig. 5 be adopt the SVG of control method of the present invention from 0 idle output jump to export 8.5M perception idle time output waveform;

Fig. 6 adopts the SVG of control method of the present invention from the output waveform exported when 8.5M capacitive reactive power jumps to 0 idle output.

Embodiment

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

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

When regulating and controlling the output reactive power of SVG, complex optimal controlled strategy modulation ratio M and the phase angle difference δ between SVG output voltage and system voltage simultaneously.

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

Precalculate mapping and be stored in master control at maintenance u _dcsVG output current under constant prerequisite (I _ca, I _cb, I _cc) functional relation list δ=f between (containing flowing into the perceptual reactive current of SVG or flowing out the capacitive reactive power electric current of 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 u in advance 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 setting M value, regulate δ to make u _dcmaintain constant, i.e. u _dc=u _dch, be wherein u _dchfor rated value, u _dcfor link unit DC capacitor voltage each in SVG.

Step 1.1.2, record the output current of now SVG (I _ca, I _cb, I _cc), obtain one group (I _ca, I _cb, I _cc) data corresponding with δ and M.

Step 1.1.3, repetition above-mentioned steps, until complete actual measurement, obtain all output currents (I _ca, I _cb, I _cc) with the corresponding relation of δ and M, data acquisition density is depending on the capacity of SVG and required precision.

Step 1.2, according to formulae discovery:

Step 1.2.1, choose the SVG output current obtained in a step 1.1.3 (I _ca, I _cb, I _cc).

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, L is the inductance of linked reactor, and ω is first-harmonic angular frequency, for the output current of a SVG chosen in step 1.2.1.

Step 1.2.3, to what obtain in step 1.2.2 carry out abc/dqo coordinate transform and ask for u ^* _cd, u ^* _cq.U ^* _cdfor output active voltage, the u of SVG under dq coordinate ^* _cqfor the output reactive voltage of SVG under dq coordinate.

Step 1.2.4, pass through u ^* _cd, u ^* _cqcalculate and choose in step 1.2.1 (I _ca, I _cb, I _cc) corresponding M, δ.

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

In formula, u ^* _cdfor output active voltage, the u of SVG under dq coordinate ^* _cqfor the output reactive voltage of SVG under dq coordinate, u _dcfor link unit DC capacitor voltage each in SVG, the link number that N comprises for each change of current chain.

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

Step 1.3, general (I _ca, I _cb, I _cc) M in corresponding step 1.1.3 and same the M obtained in corresponding step 1.2.4 averages as in functional relation list (I _ca, I _cb, I _cc) corresponding M value;

Will (I _ca, I _cb, I _cc) δ in corresponding step 1.1.3 and same the δ obtained in corresponding step 1.2.4 averages as in functional relation list (I _ca, I _cb, I _cc) corresponding δ value.

Step 2: extract real-time three phase network phase current (I _sa, I _sb, I _sc), it processed and implements abc/dqo coordinate transform, LPF digital low-pass filtering, dq0/abc inverse transformation, drawing the electric current that SVG should export (I _ca, I _cb, I _cc), and it can be used as control objectives current reference value;

Step 3: according to control objectives current reference value, chooses M and δ in functional relation list, is used for the output current of SVG.

The mode chosen has two kinds:

First kind of way: minimum with control objectives current reference value difference in Selection of Function relation list (I _ca, I _cb, I _cc) corresponding to M and δ.

The second way: functional relation list is fitted to respectively with the curve of δ with the curve of M in above-mentioned two curves, corresponding δ and M is searched respectively according to control objectives current reference value.

Step 4: when the output current (effective value) of SVG reaches the predetermined ratio of control objectives current reference value, control mode proceeds to finely tunes δ and M according to following formula

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

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

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

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

In formula, K _pfor proportionality coefficient, the K of PI controller _ifor integral coefficient, ω is first-harmonic angular frequency, and L is the inductance value of linked reactor, and S is integral operator, u ^* _cdfor output active voltage, the u of SVG under dq coordinate ^* _cqfor reactive voltage, I ^* _cqfor the idle instruction current of output of SVG under dq coordinate, I _cqfor the output reactive current of SVG under dq coordinate, I ^* _cdfor under dq coordinate, the output of SVG is gained merit instruction current, I _cdfor the output active current of SVG under dq coordinate, u _sdfor the real component of line voltage under dq coordinate, u _dcfor link unit DC capacitor voltage each in SVG, the link unit number that N comprises for each change of current chain.

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

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

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

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

Fig. 6 adopts the SVG of control method of the present invention from the output waveform exported when 8.5M capacitive reactive power jumps to 0 idle output, and waveform shows, and 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 amendment or supplement or adopt similar mode to substitute to described specific embodiment, but can't depart from spirit of the present invention or surmount the scope that appended claims defines.

Claims (3)

1. be applicable to M, δ integrated optimization control method of SVG, it is characterized in that, comprise the following steps:

Step 1: obtain at maintenance u _dcsVG output current under constant prerequisite and the functional relation list between δ and M, wherein, u _dcfor link unit DC capacitor voltage each 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 control objectives current reference value;

Step 3: choose the output current that M and δ corresponding with control objectives current reference value regulates and controls SVG in functional relation list;

Step 4: when the output current of SVG reaches the predetermined ratio of control objectives current reference value, pass through u ^* _cdand u ^* _cqδ and M is finely tuned

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

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

In formula, u ^* _cdfor output active voltage, the u of SVG under dq coordinate ^* _cqfor the output reactive voltage of SVG under dq coordinate, the link unit number that N comprises for each change of current chain;

The acquisition of described functional relation list comprises the following steps:

Step 1.1, to SVG implement field measurement:

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

Step 1.1.2, record the output current of now 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, according to formulae discovery:

Step 1.2.1, choose the SVG output current obtained 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, L is the inductance of linked reactor, and ω is first-harmonic angular frequency, for the output current of a SVG chosen in step 1.2.1;

Step 1.2.3, to what obtain in step 1.2.2 carry out abc/dqo coordinate transform and ask for u ^* _cd, u ^* _cq,

Step 1.2.4, u by obtaining in step 1.2.3 ^* _cd, u ^* _cqcalculate and choose in step 1.2.1 corresponding M, δ;

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

Step 1.2.5, repetition 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 obtained 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 obtained in corresponding step 1.2.4 averages as in functional relation list corresponding δ value.

2. a kind of M, δ integrated optimization control method being applicable to SVG according to claim 1, it is characterized in that, described step 3 comprises the following steps, minimum with control objectives current reference value difference in Selection of Function relation list corresponding M and δ.

3. a kind of M, δ integrated optimization control method being applicable to SVG according to claim 1, it is characterized in that, described step 3 comprises the following steps, and is fitted to respectively by functional relation list curve and curve, in above-mentioned two curves, search corresponding δ and M respectively according to control objectives current reference value.