CN102142684B - High-voltage direct-hanging type scalable vector graphics (SVG) comprehensive control device and comprehensive control method - Google Patents

Abstract

The invention discloses a high-voltage direct-hanging type scalable vector graphics (SVG) comprehensive control device and an SVG comprehensive control method. The comprehensive control device is connected with an electric network. Each phase of the high-voltage direct-hanging type SVG comprehensive control device comprises an inductor-capacitor (LC) filter branch, a connection reactor and an H-bridge unit serial branch, wherein the H-bridge unit serial branch is connected in series with the connection reactor and then connected in parallel with the LC filter branch; the LC filter branch comprises an inductor and a capacitor; the H-bridge unit serial branch comprises N H-bridge units which are connected in series; N is more than or equal to 2; and each H-bridge unit comprises a bridge circuit which consists of four power elements. The comprehensive control method comprises a step of comprehensive control; and the step of comprehensive control further comprises a detection step, in which a detection method based on a plurality of synchronous rotational coordinates is adopted so as to carry out comprehensive control on a reactive current, a negative-sequence current and a harmonic current. The technical scheme of the invention has the advantages of simple structure, high response speed, good waveform of an output voltage, flexible control, convenience for modular manufacturing, and the like.

Description

A kind of high voltage linear type SVG integrated control device and integrated control method thereof

Technical field

The present invention relates to a kind of electric energy composite control apparatus and method thereof, especially relate to a kind of cascaded high-voltage linear type SVG integrated control device and method thereof based on the H bridge, be widely used in all kinds of electric power systems.

Background technology

In recent years, under the promotion of national energy-saving consumption reduction policy, the electric energy-saving of large industrial enterprise has become the focus of research, and idle and harmonic compensation is the main path that realizes electric energy-saving.On the one hand, power load increasingly complex and variation, particularly for operational effect energy-conservation and the raising electric power system, power supply department encourages the user to change faster, the more efficient production equipment of use.Replacing traditional motor direct drive mode such as various frequency control equipment in the industrial system, because that the use of various current transformers brings is idle, harmonic wave, flickering and the stable state electromagnetic disturbance problem such as uneven have become the focus that the user pays close attention to.On the other hand, along with computer, the precise electronic of microprocessor control and a large amount of uses of electric equipment, these equipment rely on more and more higher to power supply reliability.Industrial expansion is so that increasing power electronic equipment and nonlinear-load thereof obtain application in electrical network, this also so that the harmonic pollution problem more highlight.Harmonic wave can cause outside electric network pollution and the normal operation of harm electric power system, also can bring a large amount of harmonic waves to damage, and wastes energy, and endangers various energy-saving devices.Therefore, particularly important at society to the improvement of the quality of power supply, wherein harmonic wave, idle negative sequence management are the matters of utmost importance in the power quality problem.

Present power consumption equipment mostly is inductive load, except obtaining to power supply the useful active power, also exists a large amount of reactive powers to exchange between power supply and load, causes power factor to reduce, and causes the harmful effect of following aspect:

(1) causes that line current increases, so that the capacity of power supplying and distributing equipment can not take full advantage of, has reduced the power supply capacity of system;

(2) current effective value increases, so that the power loss of equipment and circuit and electric energy loss sharply increase;

(3) loss of voltage of circuit and transformer strengthens, and changes aggravation, so that the quality of voltage of load end descends;

(4) for generator, reactive current increases, and the demagnetizing effect of motor is increased, and terminal voltage reduces, so that the reduction of exerting oneself of generator.

Present reactive power compensator mainly contains LC (filter that inductance L and capacitor C form), TSC (Thyristor Switched Capcitor, the thuristor throw-in and throw-off reactor), TCR (Thyristor Controlled Reactor, thyristor-controlled reactor), MCR (Magnetically Controlled Reactor, magnet controlled reactor), SVG (Static Var Generator, static reacance generator) etc., wherein SVG is that present reactive power is administered the state-of-the-art mode in field, it adopts the full-controlled switch device to form the auxiliary reactive power compensator that consists of with the low capacity energy-storage travelling wave tube of self commutated inverter, it is one of the core apparatus of flexible AC transmitting system and core technology, and the Main Function in electric power system is to carry out reactive power compensation, keep voltage stable of tie point, the steady-state behaviour of improvement system and dynamic property.Compare with existing static passive compensation device SVC have that governing speed is fast, range of operation is wide, absorb idle continuously, the advantage such as harmonic current is little, loss is low, used reactor and condenser capacity and installation volume greatly reduce.In the SVG device, in order to reduce harmonic wave, raising capacity, often adopt the multiple technology of two-level inverter.But the zigzag transformer that needs heaviness, costliness, power consumption, this volume and cost, energy loss that has greatly increased system also increases thereupon.

The existence of harmonic wave can cause following consequence in the electrical network:

(1) harmonic wave can cause the supplementary load loss of electrical network.In general, it is little that harmonic current and fundamental current are compared proportion, but harmonic frequency is high, and the kelvin effect of wire is so that harmonic wave resistance increases a lot, and the loss that is therefore produced by harmonic wave is also large.

(2) harmonic wave can cause the supplementary load loss of electric rotating machine and transformer.Harmonic wave mainly is to cause that supplementary load loss are overheated on the impact of electric rotating machine and transformer, secondly is the generation mechanical oscillation, causes and the harmonic wave overvoltage, and these all can shorten motor or transformer life, also can damage motor or transformer when serious.

(3) harmonic wave is large to the harm of power equipment.Harmonic wave existence meeting causes damage to power equipment, accelerates ageing of insulation; Voltage peak after the harmonic wave stack can reduce its insulation property; Serious harmonic wave overcurrent is so that the loss of equipment increases the heating aggravation.

(4) equipment such as harmonic wave interference communications and relaying protection.Harmonic wave disturbs weakness equipment such as computer, communication, relaying protection, ammeters, the normal work of impact and life.

Present harmonic suppression apparatus has two kinds of LC, APF (Active Power Filter, Active Power Filter-APF), and LC is passive mode, and easy and system produces resonance, can only compensate the fixed frequency harmonic wave.And its principle of APF and SVG are similar, also are to adopt the full-controlled switch device to form self commutated inverter to assist with low capacity energy-storage travelling wave tube formation, can follow the tracks of fast the compensation each harmonic, and consistent system resonance, are the state-of-the-art modes in present harmonic wave control field.Main use is transformer multiplex mode at present, and perhaps the direct parallel connection of a plurality of APF or distributed compensation are to realize the compensation of larger capacity.Owing to be to be operated in low-pressure side, be subjected to the impact of transformer, the promptness that the high-pressure side harmonic source is compensated is affected, and is limited to the compensation effect of high-pressure side harmonic wave.APF possesses the function that reactive power and harmonic wave compensate simultaneously, but because APF carries out harmonic compensation, the switching frequency of required device is high, is subjected to the restriction of device capacity, and the ability of substantially exporting without reactive power more is difficult to satisfy the demand of large capacity reactive compensation.

Negative-sequence current is another object that electrical network is administered.Negative-sequence current causes rotor to produce harmonic current so that electric rotating machine produces counter-rotating magnetic field, the motor heat the increase of output power, and power reduces; Negative phase-sequence also causes electric power system to be done take negative phase-sequence as the protective relaying maloperation that starts easily; Negative phase-sequence causes electric power system capacity and place capacity utilance low, also causes supplementary load loss, causes asymmetrical voltage, reduces the harmful effects such as generator and motor-output.Administer at present TSC, minute facies-controlled TCR and SVG that negative phase-sequence mode commonly used has the phase-splitting switching, because SVG adopts active device, its reaction speed is fast, and regulation effect is good.

At present, the compensation equipment function singleness mainly is partial to a direction, or take reactive power as main, is taken into account fractional harmonic, or take harmonic wave as main, takes into account the part reactive power.A kind of Typical Representative of prior art scheme is the purpose that forms to reach comprehensive compensation with multiple compensator, such as the combination of APF and TSC.Applied on 07 31st, 2010 by HaErBin WeiHan Electrical Appliance Equipment Co., Ltd, on December 08th, 2010 is open, publication number is the Chinese invention patent application " device for comprehensively compensating reactive power harmonics " of CN101908767A, a kind of capacitive character passive compensator of thyristor control and active compensator of IGBT control of comprising proposed, as shown in Figure 1.The left side is TSC in the empty frame, and the right is altogether DC side APF of three-phase.The capacitor type reactive-load compensator of its described thyristor control is in order to satisfy the requirement of large capacity compensation and compensation precision, many group capacitive branch are set as required, by the switching control to capacitive branch, carry out the grouping switching of capacitive reactive power, realize reactive power compensation; The active compensator of described IGBT control by the quick break-make control to various IGBT, sends needed idle and harmonic current based on voltage source inverter (VSC, Voltage Sourced Converters).This combination is to utilize passive compensator to carry out reactive power compensation, and active compensator carries out harmonic wave to be suppressed, and both make up to solve the contradiction of large capacity, cost, compensation precision and reliability.

Summary of the invention

The purpose of this invention is to provide does not a kind ofly need transformer and realizes composite control apparatus and the method thereof that the high-pressure side electric energy is administered, be a kind of possess simultaneously SVG and APF function, based on the hanging cascaded inverter HSVG of the high voltage direct of H bridge cascade (H-Bridge Static Var Generator, H bridge static reacance generator) composite control apparatus and method thereof, this composite control apparatus and method thereof have solved the contradiction between complex structure, expensive and large capacity, high compensation precision and the reliability.

The present invention specifically provides a kind of embodiment of high voltage linear type SVG integrated control device, a kind of high voltage linear type SVG integrated control device, link to each other with electrical network, each of high voltage linear type SVG integrated control device includes the LC filter branch mutually, connect reactance and H bridge units in series branch road, H bridge units in series branch road is with to be connected reactance series connection in parallel with the LC filter branch again, the LC filter branch comprises inductance and electric capacity, H bridge units in series branch road comprises N H bridge unit that is in series, N 〉=2, each H bridge unit comprises the bridge circuit that is comprised of four power components.

As the further execution mode of a kind of high voltage linear type SVG integrated control device of the present invention, the power component of bridge circuit is IGBT (Insulated Gate Bipolar Transistor, insulated gate bipolar transistor) or IGCT (Integrated Gate-Commutated Thyristor, integrated gate commutated thyristor).Simultaneously, the two ends of bridge circuit are parallel with electric capacity.

The present invention also specifically provides a kind of high voltage linear type SVG integrated control device is carried out the embodiment of the method for Comprehensive Control, and the hanging SVG integrated control method of a kind of high voltage direct comprises the Comprehensive Control step,

The Comprehensive Control step comprises:

(1) detects the three-phase instantaneous value i of the electric current I C that high voltage linear type SVG integrated control device sends _Ca, i _Cb, i _CcDetect the three-phase instantaneous value i of bus current IS _Sa, i _Sb, i _ScDetect the three-phase instantaneous value i of high voltage linear type SVG integrated control device active part current IS VG _Svga, i _Svgb, i _SvgcGather the dc voltage of modules, obtain voltage and the U of each phase N DC side _AD, U _BD, U _CD

(2) the idle control procedure of fundamental positive sequence: carry out the idle control of fundamental positive sequence, be compensated the idle and required Voltage Reference ripple V of dc voltage of positive sequence _A+, V _B+, V _C+

(3) negative-sequence current control procedure: carry out negative-sequence current control, be compensated the required Voltage Reference ripple V of negative sequence power _A-, V _B-, V _C-

(4) harmonic wave control procedure: carry out harmonic wave control, be compensated the required Voltage Reference ripple V of negative sequence power _Ah, V _Bh, V _Ch

(5) according to following formula, with the above-mentioned V that calculates _A+, V _B+, V _C+, V _A-, V _B-, V _C-And V _Ah, V _Bh, V _ChAddition obtains the reference voltage waveform

$u_a^{*}=V_{a+}+V_{a-}+V_{\mathrm{ah}};$

$u_b^{*}=V_{b+}+V_{b-}+V_{\mathrm{bh}};$

$u_c^{*}=V_{c+}+V_{c-}+V_{\mathrm{ch}};$

Carry out the one pole multiple-frequency modulation of 180 °/N, produce 3N road triangular wave, with the instantaneous value of reference voltage

And anti-value Relatively obtain the pulse of 6N road to trigger each H bridge unit, produce the voltage pwm ripple, PWM voltage produces corresponding harmonic wave, idle and negative-sequence current by connecting reactance.

As the further execution mode of the hanging SVG integrated control method of a kind of high voltage direct of the present invention, the idle control procedure of fundamental positive sequence further may further comprise the steps:

(1) to i _Sa, i _Sb, i _ScCarry out obtaining after positive sequence DQ decomposes the i under the DQ coordinate _Sd1+And i _Sq1+, with i _Sd1+And i _Sq1+Carry out obtaining after the low-pass filtering D. C. value i of real component and the idle component of fundamental positive sequence electric current _Sd1+And i _Sq1+

(2) to i _Svga, i _Svgb, i _SvgcCarry out obtaining after positive sequence DQ decomposes the i under the DQ coordinate _SvgdAnd i _Svgq, with i _SvgdAnd i _SvgqCarry out obtaining after the low-pass filtering D. C. value of real component and the idle component of fundamental positive sequence electric current

With

(3) to U _AD, U _BD, U _CDSummation and reference voltage

Compare, wherein

Be each H bridge unit DC side control voltage

3N doubly, namely

To U _AD+ U _BD+ U _CDWith Difference carry out PI regulate after with the required active current i of the voltage control of controlling whole DC side _Cd-ref

(4) to busbar voltage V _AbcAfter carrying out DQ decomposition and filtering, obtain the u under the DQ coordinate _D-feedbackAnd u _Q-feedback

(5) according to i _Cd-ref, i _Sq1+,

u _D-feedback, phase-locked value sin-cos1 be connected reactance La, Lb, the value WL of Lc under the DQ coordinate, obtain voltage u under the DQ coordinate by two PI decoupling zeros control _Sd1+And u _Sq1+, and to u _Sd1+And u _Sq1+Carry out the DQ inverse transformation and be compensated the idle and required Voltage Reference ripple V of dc voltage of positive sequence _A+, V _B+, V _C+

As the further execution mode of the hanging SVG integrated control method of a kind of high voltage direct of the present invention, the negative-sequence current control procedure further may further comprise the steps:

(1) to i _La=i _Sa-i _Ca, i _Lb=i _Sb-i _Cb, i _Lc=i _Sc-i _CcCarry out obtaining after negative phase-sequence DQ decomposes the i under the DQ coordinate _Sd1-And i _Sq1-, with i _Sd1-And i _Sq1-Carry out obtaining after the low-pass filtering D. C. value i of real component and the idle component of fundamental negative sequence current _Sd1-And i _Sq1-

(2) according to i _Sd1-And i _Sq1-Be connected reactance La, Lb, the value WL of Lc under the DQ coordinate, calculate the voltage u under the DQ coordinate _Sd1-And u _Sq1-, and to u _Sd1-And u _Sq1-Carry out the DQ inverse transformation and namely get the required Voltage Reference ripple V of compensation negative sequence power _A-, V _B-, V _C-

As the further execution mode of the hanging SVG integrated control method of a kind of high voltage direct of the present invention, the harmonic wave control procedure further may further comprise the steps:

(1) to i _La=i _Sa-i _Ca, i _Lb=i _Sb-i _Cb, i _Lc=i _Sc-i _CcThe DQ that carries out each harmonic decomposes, and namely determines that according to harmonic number its attribute is positive sequence or negative phase-sequence, and the determined phase-locked sin-cosN of associating harmonic number carries out decomposing for DQ, obtains i _LdNAnd i _LqN

(2) according to i _LdN, i _LqNBe connected reactance La, Lb, the value NWL of Lc under the DQ coordinate, calculate the voltage u under the DQ coordinate _LdNAnd u _LqN, and to u _LdNAnd u _LqNCarry out the DQ inverse transformation and be compensated the required Voltage Reference ripple V of negative sequence power _Ah, V _Bh, V _Ch

As the further execution mode of the hanging SVG integrated control method of a kind of high voltage direct of the present invention, the Comprehensive Control step further comprises detecting step, and detecting step comprises:

(1) gathers the current i that needs analysis _a, i _b, i _c

(2) fundamental positive sequence current detecting process: carry out the fundamental positive sequence current detecting, by calculating three-phase forward-order current i ' _A1+, i ' _B1+, i ' _C1+

(3) negative-sequence current testing process: carry out negative-sequence current and detect, by calculate the three-phase negative/positive current i ' _A1-, i ' _B1-, i ' _C1-

(4) harmonic current testing process: carry out harmonic current and detect, by calculating the DC component i of N subharmonic _DN, i _QN

Integrated control method further comprises the phase-locked value calculation procedure of multifrequency, and the phase-locked value calculation procedure of multifrequency comprises: by line voltage being carried out the phase-locked angular frequency instantaneous value ω t that obtains first-harmonic; Multiply by the times N of harmonic wave by the angular frequency instantaneous value ω t of first-harmonic, obtain the value of N ω t, obtain the value of sin-cosN.

As the further execution mode of the hanging SVG integrated control method of a kind of high voltage direct of the present invention, the idle control procedure of fundamental positive sequence comprises fundamental positive sequence current detecting process, and fundamental positive sequence current detecting process further may further comprise the steps:

i _a, i _b, i _cObtain its first-harmonic part i by the band pass filter processing _A1, i _B1, i _C1, then obtain the meritorious and idle DC component of the forward-order current of DQ coordinate by formula (3) matrixing;

$\left[\begin{array}{c}{i}_{\mathrm{<figure-callout\; id="1"\; label="d"\; filenames="110318160852.png,110318160859.png"\; state="\{\{state\}\}">d</figure-callout>}1+}\\ {\mathrm{<figure-callout\; id="1"\; label="i\; q"\; filenames="110318160852.png,110318160859.png"\; state="\{\{state\}\}">i</figure-callout>}}_q\end{array}\right]=\frac{2}{3}\left[\begin{array}{ccc}\sin \mathrm{n\&omega;t}& \sin (\mathrm{n\&omega;t}-\frac{2\mathrm{\&pi;}}{3})& \sin (\mathrm{n\&omega;t}+\frac{2\mathrm{\&pi;}}{3})\\ \cos \mathrm{n\&omega;t}& \cos (\mathrm{n\&omega;t}-\frac{2\mathrm{\&pi;}}{3})& \cos (\mathrm{n\&omega;t}+\frac{2\mathrm{\&pi;}}{3})\end{array}\right]\left[\begin{array}{c}{i}_{a1}\\ i_{b1}\\ i_{c1}\end{array}\right]---\left(3\right)$

Gain merit and idle component i by the positive sequence that the calculating to formula (3) obtains _D1+, i _Q1+Carry out low-pass filtering, and obtain i ' by multiply by after COEFFICIENT K is revised the amplitude of decay _D1+, i ' _Q1+, as the controlled quentity controlled variable of reactive current;

Again to idle active current and the reactive current amount i that carries out obtaining after the regulating and controlling DQ coordinate " _D1+, i " _Q1+, according to formula (4) to i " _D1+, i " _Q1+Carry out the DQ inverse transformation and obtain the three-phase forward-order current i ' of abc coordinate _A1+, i ' _B1+, i ' _C1+

$\left[\begin{array}{c}{i}_{a1+}^{\&prime;}\\ i_{\mathrm{<figure-callout\; id="1"\; label="b"\; filenames="110318160852.png,110318160859.png"\; state="\{\{state\}\}">b</figure-callout>}1+}^{\&prime;}\\ i_{\mathrm{<figure-callout\; id="1"\; label="c"\; filenames="110318160852.png,110318160859.png"\; state="\{\{state\}\}">c</figure-callout>}1+}^{\&prime;}\end{array}\right]=\left[\begin{array}{cc}\sin \mathrm{\&omega;t}& \cos \mathrm{\&omega;t}\\ \sin (\mathrm{\&omega;t}-\frac{2\mathrm{\&pi;}}{3})& \cos (\mathrm{\&omega;t}-\frac{2\mathrm{\&pi;}}{3})\\ \sin (\mathrm{\&omega;t}+\frac{2\mathrm{\&pi;}}{3})& \cos (\mathrm{\&omega;t}+\frac{2\mathrm{\&pi;}}{3})\end{array}\right]\left[\begin{array}{c}{i}_{\mathrm{<figure-callout\; id="1"\; label="d"\; filenames="110318160852.png,110318160859.png"\; state="\{\{state\}\}">d</figure-callout>}1+}^{\&prime;\&prime;}\\ i_{\mathrm{<figure-callout\; id="1"\; label="q"\; filenames="110318160852.png,110318160859.png"\; state="\{\{state\}\}">q</figure-callout>}1+}^{\&prime;\&prime;}\end{array}\right]---\left(4\right)$

As the further execution mode of the hanging SVG integrated control method of a kind of high voltage direct of the present invention, the negative-sequence current control procedure comprises the negative-sequence current testing process, and the negative-sequence current testing process further may further comprise the steps:

i _a, i _b, i _cObtain its first-harmonic part i by the band pass filter processing _A1, i _B1, i _C1, then obtain the meritorious and idle DC component of the forward-order current of DQ coordinate by formula (5) matrixing;

$\left[\begin{array}{c}{i}_{d1-}\\ i_{q1-}\end{array}\right]=\frac{2}{3}\left[\begin{array}{ccc}\sin \mathrm{n\&omega;t}& \sin (\mathrm{n\&omega;t}+\frac{2\mathrm{\&pi;}}{3})& \sin (\mathrm{n\&omega;t}-\frac{2\mathrm{\&pi;}}{3})\\ \cos \mathrm{n\&omega;t}& \cos (\mathrm{n\&omega;t}+\frac{2\mathrm{\&pi;}}{3})& \cos (\mathrm{n\&omega;t}-\frac{2\mathrm{\&pi;}}{3})\end{array}\right]\left[\begin{array}{c}{i}_{a1}\\ i_{b1}\\ i_{c1}\end{array}\right]---\left(5\right)$

Meritorious and the idle component i of the positive sequence that calculating obtains to formula (5) _D1-, i _Q1-Carry out low-pass filtering, and obtain i ' by multiply by after COEFFICIENT K is revised the amplitude of decay _D1-, i ' _Q1-, as the controlled quentity controlled variable of reactive current, active current and the reactive current amount i to obtaining the DQ coordinate after the negative sequence compensation regulating and controlling again " _D1-, i " _Q1-, according to formula (6) to i " _D1-, i " _Q1-Carry out the DQ inverse transformation obtain the three-phase negative/positive current i of abc coordinate ' _A1-, i ' _B1-, i ' _C1-

$\left[\begin{array}{c}{i}_{a1-}^{\&prime;}\\ i_{b1-}^{\&prime;}\\ i_{c1-}^{\&prime;}\end{array}\right]=\left[\begin{array}{cc}\sin \mathrm{\&omega;t}& \cos \mathrm{\&omega;t}\\ \sin (\mathrm{\&omega;t}+\frac{2\mathrm{\&pi;}}{3})& \cos (\mathrm{\&omega;t}+\frac{2\mathrm{\&pi;}}{3})\\ \sin (\mathrm{\&omega;t}-\frac{2\mathrm{\&pi;}}{3})& \cos (\mathrm{\&omega;t}-\frac{2\mathrm{\&pi;}}{3})\end{array}\right]\left[\begin{array}{c}{i}_{\mathrm{<figure-callout\; id="1"\; label="d"\; filenames="110318160852.png,110318160859.png"\; state="\{\{state\}\}">d</figure-callout>}1+}^{\&prime;\&prime;}\\ i_{\mathrm{<figure-callout\; id="1"\; label="q"\; filenames="110318160852.png,110318160859.png"\; state="\{\{state\}\}">q</figure-callout>}1+}^{\&prime;\&prime;}\end{array}\right]---\left(6\right)$

As the further execution mode of the hanging SVG integrated control method of a kind of high voltage direct of the present invention, the harmonic wave control procedure comprises the harmonic current testing process, and the harmonic current testing process further may further comprise the steps:

i _a, i _b, i _cBand pass filter processing by lower limiting frequency in the setting is fixed subharmonic current i _AN, i _BN, i _CN, utilize formula (7) or formula (8) with i _AN, i _BN, i _CNBe transformed in the DQ coordinate system of N subharmonic; If N=3K+1 then calculates according to formula (7); If N=3K-1 then calculates according to formula (8), obtain the DC component i of N subharmonic _DN, i _Q1N

$\left[\begin{array}{c}{i}_{\mathrm{dN}}\\ i_{\mathrm{qN}}\end{array}\right]=\frac{2}{3}\left[\begin{array}{ccc}\sin \mathrm{n\&omega;t}& \sin (\mathrm{n\&omega;t}-\frac{2\mathrm{\&pi;}}{3})& \sin (\mathrm{n\&omega;t}+\frac{2\mathrm{\&pi;}}{3})\\ \cos \mathrm{n\&omega;t}& \cos (\mathrm{n\&omega;t}-\frac{2\mathrm{\&pi;}}{3})& \cos (\mathrm{n\&omega;t}+\frac{2\mathrm{\&pi;}}{3})\end{array}\right]\left[\begin{array}{c}{i}_{\mathrm{aN}}\\ i_{\mathrm{bN}}\\ i_{\mathrm{cN}}\end{array}\right]---\left(7\right)$

$\left[\begin{array}{c}{i}_{\mathrm{dN}}\\ i_{\mathrm{qN}}\end{array}\right]=\frac{2}{3}\left[\begin{array}{ccc}\sin \mathrm{n\&omega;t}& \sin (\mathrm{n\&omega;t}+\frac{2\mathrm{\&pi;}}{3})& \sin (\mathrm{n\&omega;t}-\frac{2\mathrm{\&pi;}}{3})\\ \cos \mathrm{n\&omega;t}& \cos (\mathrm{n\&omega;t}+\frac{2\mathrm{\&pi;}}{3})& \cos (\mathrm{n\&omega;t}-\frac{2\mathrm{\&pi;}}{3})\end{array}\right]\left[\begin{array}{c}{i}_{\mathrm{aN}}\\ i_{\mathrm{bN}}\\ i_{\mathrm{cN}}\end{array}\right]---\left(8\right)$

Utilize formula (9) or formula (10) that the harmonic content of DQ coordinate is transformed in the abc coordinate system; If N=3K+1 then calculates according to formula (9); If N=3K-1 then calculates according to formula (10), obtain the DC component i of N subharmonic _AN, i _BN, i _CN

$\left[\begin{array}{c}{i}_{\mathrm{aN}}\\ i_{\mathrm{bN}}\\ i_{\mathrm{cN}}\end{array}\right]=\left[\begin{array}{cc}\sin \mathrm{n\&omega;t}& \cos \mathrm{n\&omega;t}\\ \sin (\mathrm{n\&omega;t}+\frac{2\mathrm{\&pi;}}{3})& \cos (\mathrm{n\&omega;t}+\frac{2\mathrm{\&pi;}}{3})\\ \sin (\mathrm{n\&omega;t}-\frac{2\mathrm{\&pi;}}{3})& \cos (\mathrm{n\&omega;t}-\frac{2\mathrm{\&pi;}}{3})\end{array}\right]\left[\begin{array}{c}{i}_{\mathrm{dN}}\\ i_{\mathrm{qN}}\end{array}\right]---\left(9\right)$

$\left[\begin{array}{c}{i}_{\mathrm{aN}}\\ i_{\mathrm{bN}}\\ i_{\mathrm{cN}}\end{array}\right]=\left[\begin{array}{cc}\sin \mathrm{n\&omega;t}& \cos \mathrm{n\&omega;t}\\ \sin (\mathrm{n\&omega;t}-\frac{2\mathrm{\&pi;}}{3})& \cos (\mathrm{n\&omega;t}-\frac{2\mathrm{\&pi;}}{3})\\ \sin (\mathrm{n\&omega;t}+\frac{2\mathrm{\&pi;}}{3})& \cos (\mathrm{n\&omega;t}+\frac{2\mathrm{\&pi;}}{3})\end{array}\right]\left[\begin{array}{c}{i}_{\mathrm{dN}}\\ i_{\mathrm{qN}}\end{array}\right]---\left(10\right)$

By implementing the embodiment of a kind of high voltage linear type SVG integrated control device of the present invention and integrated control method thereof, can reach following technique effect:

(1) owing to the LC with its coupling does not need to carry out switching control, and Comprehensive Control is finished in unique active part, does not therefore need to make up with other equipment, only needs a controller;

(2) only have one group of equipment LC, active part adopts indoor cabinet type, and floor space is little;

(3) fast response time can satisfy the compensation requirement of various impacts, mutational load;

(4) structure of employing H bridge cascade can directly access high-pressure system, does not need transformer pressure-reducing, can directly administer the high-pressure side harmonic wave;

(5) adopt H bridge module structure, be convenient to the scale manufacturing;

(6) single H bridge module switching frequency is low, and whole equivalent switching frequency is high, and the output voltage waveforms quality is good;

(7) separately control of first-harmonic, each harmonic, but both separate compensation was idle, but also separate compensation harmonic wave, and harmonic number can select, highly versatile, flexibly.

Description of drawings

In order to be illustrated more clearly in the embodiment of the invention or technical scheme of the prior art, the below will do to introduce simply to the accompanying drawing of required use in embodiment or the description of the Prior Art, apparently, accompanying drawing in the following describes only is some embodiments of the present invention, for those of ordinary skills, under the prerequisite of not paying creative work, can also obtain according to these accompanying drawings other accompanying drawing.

Fig. 1 is a kind of structure composition frame chart based on TSC and APF device for comprehensively compensating reactive power harmonics of prior art;

Fig. 2 is the topology diagram of a kind of embodiment of high voltage linear type SVG integrated control device of the present invention;

Fig. 3 is the topology diagram of a kind of embodiment in high voltage linear type SVG integrated control device H of the present invention bridge unit;

Fig. 4 is the structure composition frame chart of a kind of embodiment of high voltage linear type SVG integrated control device positive sequence detection module of the present invention;

Fig. 5 is the structure composition frame chart of a kind of embodiment of high voltage linear type SVG integrated control device negative phase-sequence detection module of the present invention;

Fig. 6 is the structure composition frame chart of a kind of embodiment of the phase-locked module of high voltage linear type SVG integrated control device of the present invention;

Fig. 7 is system's control principle block diagram of a kind of embodiment of high voltage linear type SVG integrated control device of the present invention;

Fig. 8 is the idle decoupling zero control of the positive sequence schematic diagram of a kind of embodiment of integrated control method of a kind of high voltage linear type SVG integrated control device of the present invention;

Fig. 9 is the idle decoupling zero control of the negative phase-sequence schematic diagram of a kind of embodiment of integrated control method of a kind of high voltage linear type SVG integrated control device of the present invention;

Figure 10 is the harmonic wave decoupling zero control schematic diagram of a kind of embodiment of integrated control method of a kind of high voltage linear type SVG integrated control device of the present invention;

Figure 11 carries out compensation waveform schematic diagram after the Comprehensive Control through the described high voltage linear type SVG integrated control device of a kind of embodiment of the present invention;

Figure 12 carries out appointment subharmonic compensation waveform schematic diagram after the Comprehensive Control through the described high voltage linear type SVG integrated control device of a kind of embodiment of the present invention;

Wherein: 1-high voltage linear type SVG integrated control device, 2-load, 3-LC filter branch, 4-H bridge units in series branch road, 5-H bridge unit, the idle control module of 6-fundamental positive sequence, 7-negative-sequence current control module, 8-harmonic wave control module, 9-fundamental positive sequence current detection module, 10-negative-sequence current detection module, 11-harmonic current detection module, the 12-composite control apparatus, the 13-checkout gear.

Embodiment

Below in conjunction with the accompanying drawing in the embodiment of the invention, the technical scheme in the embodiment of the invention is clearly and completely described, obviously, described embodiment only is a part of embodiment of the present invention, rather than whole embodiment.Based on the embodiment among the present invention, those of ordinary skills belong to the scope of protection of the invention not making the every other embodiment that obtains under the creative work prerequisite.

As the embodiment of a kind of high voltage linear type SVG integrated control device of the present invention, the technical scheme main circuit diagram that high voltage linear type SVG integrated control device (HSVG) is applied in the three phase network system as shown in Figure 2.On structure, main circuit is the star-like connected system of a three-phase full symmetric.Every AC series connection by N H bridge unit 5 is connected with being connected reactance, is formed in parallel with a LC filter branch 3 again.La among the figure, Lb, Lc are the connection reactance of HSVG; Lal and Cal consist of mutually LC filter branch of an A, with by being arranged to certain filter branch; In like manner, Lbl consists of mutually LC filter branch of a B with Cbl; Lcl consists of mutually LC filter branch of a C with Ccl.Wherein the circuit of H bridge unit 5 as shown in Figure 2, it comprises a bridge circuit that is comprised of 4 IGBT or IGCT, the two ends of bridge circuit are parallel with capacitor C dc.

High voltage linear type SVG integrated control device 1 further comprises composite control apparatus 12, composite control apparatus 12 is input as the three-phase instantaneous value of the electric current I C that high voltage linear type SVG integrated control device sends, the three-phase instantaneous value of bus current IS, the three-phase instantaneous value of high voltage linear type SVG integrated control device active part current IS VG and the dc voltage of modules, obtain the reference voltage waveform, composite control apparatus 12 output three-phase voltage reference waveforms, one pole multiple-frequency modulation through 180 °/N, produce 3N road triangular wave, relatively obtain the pulse of 6N road to trigger each H bridge unit with instantaneous value and the anti-value thereof of reference voltage, produce the voltage pwm ripple, PWM voltage produces corresponding harmonic wave by connecting reactance, idle and negative-sequence current.Composite control apparatus 12 further comprises the idle control module 6 of fundamental positive sequence, negative-sequence current control module 7 and harmonic wave control module 8, wherein:

Control module that fundamental positive sequence is idle 6 is carried out the idle control of fundamental positive sequence, the idle and required Voltage Reference ripple of dc voltage of output compensation positive sequence;

Negative-sequence current control module 7 is carried out negative-sequence current control, the required Voltage Reference ripple of output compensation negative sequence power;

Harmonic wave control module 8 is carried out harmonic wave control, the required Voltage Reference ripple of output compensation negative sequence power.

Fundamental positive sequence is idle, and control module 6 comprises fundamental positive sequence current detection module 9, and negative-sequence current control module 7 comprises negative-sequence current detection module 10, and harmonic wave control module 8 comprises harmonic current detection module 11.Fundamental positive sequence current detection module 9, negative-sequence current detection module 10 and harmonic wave current detection module 11 form checkout gear 13, checkout gear 13 is input as three-phase current to be detected, the DC component of output three-phase forward-order current, three-phase negative/positive electric current and N subharmonic.Wherein:

Fundamental positive sequence current detection module 9 carries out the fundamental positive sequence current detecting, is input as three-phase current to be detected, output three-phase forward-order current;

Negative-sequence current detection module 10 carries out negative-sequence current and detects, and is input as three-phase current to be detected, by calculating the three-phase negative/positive electric current;

Harmonic current detection module 11 carries out harmonic current and detects, and is input as three-phase current to be detected, by calculating the DC component of N subharmonic.

Checkout gear 13 further comprises the phase-locked module of multifrequency.SVG comprises H bridge units in series branch road and is connected reactance, selects the SVG of equal capacity in parallel with the LC filter branch, and the LC filter branch is arranged to fixedly subharmonic filtering device.

The described high voltage linear type SVG integrated control device of the specific embodiment of the invention adopts modular construction, be convenient to make, dilatation is convenient, can satisfy different electric pressures as long as change the H bridge unit number of series connection, for example 66kV, 55kV, 35kV, 10kV, 6kV are suitable for the high-pressure side direct compensation.Single H bridge unit module switching frequency is low, can adopt the debugging of one pole frequency multiplication, improves equivalent switching frequency, and the output voltage waveforms quality is good; The module output current is little, the loop of power circuit simplicity of design; The voltage difference that each modular unit bears is little, load sharing; With the LC branch circuit parallel connection, take full advantage of active capacity, save cost, the capacitive compensation capacity doubles.For example active operation interval be-10Mvar～+ 10Mvar, after the LC of-10Mvar is in parallel, can realize-20Mvar～0 compensation.

For the ease of digital control realization, unified positive sequence is idle, the detection of negative-sequence current and appointment subharmonic current, and the embodiment of the hanging SVG integrated control method of high voltage direct of the present invention has also proposed a kind of detection method based on synchronous multiple-rotating coordinate.Its principle is can accomplish in theory the floating of direct current constant signal is followed the tracks of according to traditional pi regulator, stable state accuracy is high, dynamic response is good, engineering is used simple and practical thought, by being DC quantity to rotating coordinate transformation with the nth harmonic current transitions synchronously, then by low pass filter this DC quantity is extracted controlled quentity controlled variable as PI.Needing to use two transformation matrixs shown in formula (1) and (2) in being rotated variation, wherein ω is positive sequence first-harmonic angular velocity of rotation, For n positive sequence harmonic is tied to the coefficient matrix of DQ coordinate system by the abc static coordinate,

Be tied to the coefficient matrix of DQ coordinate system by the abc static coordinate for n negative phase-sequence harmonic wave.In addition definition

Be respectively

Inverse matrix, be the DQ Coordinate Conversion to the transformation matrix of abc rest frame.Following classificating introduction fundamental reactive current, respectively be the testing process of harmonic current and negative-sequence current, because the method not only is suitable in the control method of the follow-up introduction of technical solution of the present invention, also be suitable for other similar application scenarios, suppose that therefore the target current that needs to analyze is i _a, i _b, i _c

$T_{\mathrm{abc}-\mathrm{dqn}}^P=\frac{2}{3}\left[\begin{array}{ccc}\sin \mathrm{n\&omega;t}& \sin (\mathrm{n\&omega;t}-\frac{2\mathrm{\&pi;}}{3})& \sin (\mathrm{n\&omega;t}+\frac{2\mathrm{\&pi;}}{3})\\ \cos \mathrm{n\&omega;t}& \cos (\mathrm{n\&omega;t}-\frac{2\mathrm{\&pi;}}{3})& \cos (\mathrm{n\&omega;t}+\frac{2\mathrm{\&pi;}}{3})\end{array}\right]---\left(1\right)$

$T_{\mathrm{abc}-\mathrm{dqn}}^N=\frac{2}{3}\left[\begin{array}{ccc}\sin \mathrm{n\&omega;t}& \sin (\mathrm{n\&omega;t}+\frac{2\mathrm{\&pi;}}{3})& \sin (\mathrm{n\&omega;t}-\frac{2\mathrm{\&pi;}}{3})\\ \cos \mathrm{n\&omega;t}& \cos (\mathrm{n\&omega;t}+\frac{2\mathrm{\&pi;}}{3})& \cos (\mathrm{n\&omega;t}-\frac{2\mathrm{\&pi;}}{3})\end{array}\right]---\left(2\right)$

1, fundamental positive sequence current detecting

By gathering the current i that needs analysis _a, i _b, i _c, because i _a, i _b, i _cComprise first-harmonic and harmonic current, obtain its first-harmonic part i after therefore at first processing by a band pass filter (Band Pass Filter) _A1, i _B1, i _C1, then utilize formula (1) matrixing to obtain the meritorious and idle DC component i of the forward-order current of DQ coordinate _D1+, i _Q1+, this moment value n=1, that is:

$\left[\begin{array}{c}{i}_{\mathrm{<figure-callout\; id="1"\; label="d"\; filenames="110318160852.png,110318160859.png"\; state="\{\{state\}\}">d</figure-callout>}1+}\\ i_{\mathrm{<figure-callout\; id="1"\; label="q"\; filenames="110318160852.png,110318160859.png"\; state="\{\{state\}\}">q</figure-callout>}1+}\end{array}\right]=\frac{2}{3}\left[\begin{array}{ccc}\sin \mathrm{n\&omega;t}& \sin (\mathrm{n\&omega;t}-\frac{2\mathrm{\&pi;}}{3})& \sin (\mathrm{n\&omega;t}+\frac{2\mathrm{\&pi;}}{3})\\ \cos \mathrm{n\&omega;t}& \cos (\mathrm{n\&omega;t}-\frac{2\mathrm{\&pi;}}{3})& \cos (\mathrm{n\&omega;t}+\frac{2\mathrm{\&pi;}}{3})\end{array}\right]\left[\begin{array}{c}{i}_{a1}\\ i_{b1}\\ i_{c1}\end{array}\right]---\left(3\right)$

Meritorious and the idle component i of positive sequence that again (3) is obtained _D1+, i _Q1+Carry out low-pass filtering, and obtain i ' by multiply by after COEFFICIENT K is revised the amplitude of decay _D1+, i ' _Q1+, namely can be used as the controlled quentity controlled variable of controlling reactive current, whole process is as shown in Figure 4.On the contrary, again to idle active current and the reactive current amount i that carries out to obtain after the regulating and controlling DQ coordinate " _D1+, i " _Q1+, it is carried out the three-phase forward-order current i ' that the DQ inverse transformation can obtain the abc coordinate _A1+, i ' _B1+, i ' _C1+, this moment value n=1, that is:

$\left[\begin{array}{c}{i}_{a1+}^{\&prime;}\\ i_{b1+}^{\&prime;}\\ i_{c1+}^{\&prime;}\end{array}\right]=T_{\mathrm{abc}-\mathrm{dq}1}^{-\mathrm{<figure-callout\; id="1"\; label="P\; i\; d"\; filenames="110318160852.png,110318160859.png"\; state="\{\{state\}\}">P</figure-callout>}}\left[\begin{array}{c}{i}_d^{}\end{array}\right]\left[\begin{array}{c}{1+}_{\&prime;\&prime;}^{}\\ i_{\mathrm{<figure-callout\; id="1"\; label="q"\; filenames="110318160852.png,110318160859.png"\; state="\{\{state\}\}">q</figure-callout>}1+}^{\&prime;\&prime;}\end{array}\right]=\left[\begin{array}{cc}\sin \mathrm{\&omega;t}& \cos \mathrm{\&omega;t}\\ \sin (\mathrm{\&omega;t}-\frac{2\mathrm{\&pi;}}{3})& \cos (\mathrm{\&omega;t}-\frac{2\mathrm{\&pi;}}{3})\\ \sin (\mathrm{\&omega;t}+\frac{2\mathrm{\&pi;}}{3})& \cos (\mathrm{\&omega;t}+\frac{2\mathrm{\&pi;}}{3})\end{array}\right]\left[\begin{array}{c}{i}_{\mathrm{<figure-callout\; id="1"\; label="d"\; filenames="110318160852.png,110318160859.png"\; state="\{\{state\}\}">d</figure-callout>}1+}^{\&prime;\&prime;}\\ i_{\mathrm{<figure-callout\; id="1"\; label="q"\; filenames="110318160852.png,110318160859.png"\; state="\{\{state\}\}">q</figure-callout>}1+}^{\&prime;\&prime;}\end{array}\right]---\left(4\right)$

2, negative-sequence current detects

With the First Harmonic Reactive Power detection type seemingly, obtain first first-harmonic part i _A1, i _B1, i _C1, then utilize formula (2) matrixing to obtain the meritorious and idle DC component i of the forward-order current of DQ coordinate _D1-, i _Q1-, this moment value n=1, that is:

$\left[\begin{array}{c}{i}_{d1-}\\ i_{q1-}\end{array}\right]=\frac{2}{3}\left[\begin{array}{ccc}\sin \mathrm{n\&omega;t}& \sin (\mathrm{n\&omega;t}+\frac{2\mathrm{\&pi;}}{3})& \sin (\mathrm{n\&omega;t}-\frac{2\mathrm{\&pi;}}{3})\\ \cos \mathrm{n\&omega;t}& \cos (\mathrm{n\&omega;t}+\frac{2\mathrm{\&pi;}}{3})& \cos (\mathrm{n\&omega;t}-\frac{2\mathrm{\&pi;}}{3})\end{array}\right]\left[\begin{array}{c}{i}_{a1}\\ i_{b1}\\ i_{c1}\end{array}\right]---\left(5\right)$

Meritorious and the idle component i of positive sequence that again (5) is obtained _D1-, i _Q1-Carry out low-pass filtering, and obtain i ' by multiply by after COEFFICIENT K is revised the amplitude of decay _D1-, i ' _Q1-, namely can be used as the controlled quentity controlled variable of controlling reactive current, whole process is as shown in Figure 5.On the contrary, active current and the reactive current amount i to obtaining the DQ coordinate after the negative sequence compensation regulating and controlling again " _D1-, i " _Q1-, to its carry out the DQ inverse transformation can obtain the three-phase negative/positive current i of abc coordinate ' _A1-, i ' _B1-, i ' _C1-, this moment value n=1, that is:

$\left[\begin{array}{c}{i}_{a1-}^{\&prime;}\\ i_{b1-}^{\&prime;}\\ i_{c1-}^{\&prime;}\end{array}\right]=T_{\mathrm{abc}-\mathrm{dq}1}^{-\mathrm{<figure-callout\; id="1"\; label="N\; i\; d"\; filenames="110318160852.png,110318160859.png"\; state="\{\{state\}\}">N</figure-callout>}}\left[\begin{array}{c}{i}_d^{}\end{array}\right]\left[\begin{array}{c}{1+}_{\&prime;\&prime;}^{}\\ i_{\mathrm{<figure-callout\; id="1"\; label="q"\; filenames="110318160852.png,110318160859.png"\; state="\{\{state\}\}">q</figure-callout>}1+}^{\&prime;\&prime;}\end{array}\right]=\left[\begin{array}{cc}\sin \mathrm{n\&omega;t}& \cos \mathrm{n\&omega;t}\\ \sin (\mathrm{n\&omega;t}+\frac{2\mathrm{\&pi;}}{3})& \cos (\mathrm{n\&omega;t}+\frac{2\mathrm{\&pi;}}{3})\\ \sin (\mathrm{n\&omega;t}-\frac{2\mathrm{\&pi;}}{3})& \cos (\mathrm{n\&omega;t}-\frac{2\mathrm{\&pi;}}{3})\end{array}\right]\left[\begin{array}{c}{i}_{\mathrm{<figure-callout\; id="1"\; label="d"\; filenames="110318160852.png,110318160859.png"\; state="\{\{state\}\}">d</figure-callout>}1+}^{\&prime;\&prime;}\\ i_{\mathrm{<figure-callout\; id="1"\; label="q"\; filenames="110318160852.png,110318160859.png"\; state="\{\{state\}\}">q</figure-callout>}1+}^{\&prime;\&prime;}\end{array}\right]---\left(6\right)$

3, harmonic current detects

Harmonic wave detects with the principle that forward-order current detects or negative-sequence current detects similar, just for the N subharmonic, since the characteristics determined of harmonic wave self its belong to positive sequence harmonic or negative phase-sequence harmonic wave and Zero-pharse harmonic, 3K-1 (K=1 wherein, 2 ...) inferior be the negative phase-sequence harmonic wave, 3K+1 time is positive sequence harmonic, and 3K is Zero-pharse harmonic.Owing to be three-phase three wire system as shown in Figure 2, therefore do not contain Zero-pharse harmonic.Then according to the attribute of harmonic wave, for example N=3K+1 then selects

Matrix is if N=3K-1 then selects Matrix is changed.Can realize like this extraction to the appointment subharmonic, and highly versatile.Detailed process is:

Same by gathering the current i that needs analysis _a, i _b, i _c, because i _a, i _b, i _cComprise first-harmonic and harmonic current, therefore at first be fixed subharmonic current i behind the band pass filter (Band Pass Filter) by lower limiting frequency in the setting _AN, i _BN, i _CNUtilize formula (1) or (2) that it is transformed in the DQ coordinate system of N subharmonic.If N=3K+1 then utilizes (1) formula, its process is such as (7) formula, n=N wherein, and its schematic diagram is seen Fig. 4; If N=3K-1 then utilizes (2) formula, its process is such as (8) formula, n=N wherein, and its schematic diagram is seen Fig. 5.Obtain the DC component i of N subharmonic _DN, i _Q1N, that is:

$\left[\begin{array}{c}{i}_{\mathrm{dN}}\\ i_{\mathrm{qN}}\end{array}\right]=\frac{2}{3}\left[\begin{array}{ccc}\sin \mathrm{n\&omega;t}& \sin (\mathrm{n\&omega;t}-\frac{2\mathrm{\&pi;}}{3})& \sin (\mathrm{n\&omega;t}+\frac{2\mathrm{\&pi;}}{3})\\ \cos \mathrm{n\&omega;t}& \cos (\mathrm{n\&omega;t}-\frac{2\mathrm{\&pi;}}{3})& \cos (\mathrm{n\&omega;t}+\frac{2\mathrm{\&pi;}}{3})\end{array}\right]\left[\begin{array}{c}{i}_{\mathrm{aN}}\\ i_{\mathrm{bN}}\\ i_{\mathrm{cN}}\end{array}\right]---\left(7\right)$

$\left[\begin{array}{c}{i}_{\mathrm{dN}}\\ i_{\mathrm{qN}}\end{array}\right]=\frac{2}{3}\left[\begin{array}{ccc}\sin \mathrm{n\&omega;t}& \sin (\mathrm{n\&omega;t}+\frac{2\mathrm{\&pi;}}{3})& \sin (\mathrm{n\&omega;t}-\frac{2\mathrm{\&pi;}}{3})\\ \cos \mathrm{n\&omega;t}& \cos (\mathrm{n\&omega;t}+\frac{2\mathrm{\&pi;}}{3})& \cos (\mathrm{n\&omega;t}-\frac{2\mathrm{\&pi;}}{3})\end{array}\right]\left[\begin{array}{c}{i}_{\mathrm{aN}}\\ i_{\mathrm{bN}}\\ i_{\mathrm{cN}}\end{array}\right]---\left(8\right)$

Equally, also can be transformed in the abc coordinate in the harmonic content of DQ coordinate and to go, in the same manner as above according to harmonic number N attribute and size, select suitable matrix, its conversion formula is seen (9) and (10).

$\left[\begin{array}{c}{i}_{\mathrm{aN}}\\ i_{\mathrm{bN}}\\ i_{\mathrm{cN}}\end{array}\right]=T_{\mathrm{abc}-\mathrm{dqN}}^{-N}\left[\begin{array}{c}{i}_{\mathrm{dN}}\\ i_{\mathrm{qN}}\end{array}\right]=\left[\begin{array}{cc}\sin \mathrm{n\&omega;t}& \cos \mathrm{n\&omega;t}\\ \sin (\mathrm{n\&omega;t}+\frac{2\mathrm{\&pi;}}{3})& \cos (\mathrm{n\&omega;t}+\frac{2\mathrm{\&pi;}}{3})\\ \sin (\mathrm{n\&omega;t}-\frac{2\mathrm{\&pi;}}{3})& \cos (\mathrm{n\&omega;t}-\frac{2\mathrm{\&pi;}}{3})\end{array}\right]\left[\begin{array}{c}{i}_{\mathrm{dN}}\\ i_{\mathrm{qN}}\end{array}\right]---\left(9\right)$

$\left[\begin{array}{c}{i}_{\mathrm{aN}}\\ i_{\mathrm{bN}}\\ i_{\mathrm{cN}}\end{array}\right]=T_{\mathrm{abc}-\mathrm{dqN}}^{-P}\left[\begin{array}{c}{i}_{\mathrm{dN}}\\ i_{\mathrm{qN}}\end{array}\right]=\left[\begin{array}{cc}\sin \mathrm{n\&omega;t}& \cos \mathrm{n\&omega;t}\\ \sin (\mathrm{n\&omega;t}-\frac{2\mathrm{\&pi;}}{3})& \cos (\mathrm{n\&omega;t}-\frac{2\mathrm{\&pi;}}{3})\\ \sin (\mathrm{n\&omega;t}+\frac{2\mathrm{\&pi;}}{3})& \cos (\mathrm{n\&omega;t}+\frac{2\mathrm{\&pi;}}{3})\end{array}\right]\left[\begin{array}{c}{i}_{\mathrm{dN}}\\ i_{\mathrm{qN}}\end{array}\right]---\left(10\right)$

4, the phase-locked value of multifrequency is calculated

In above-mentioned calculating, need to use the phase-locked value of each harmonic, because it is large separately every subharmonic current to be carried out phase-locked then amount of calculation, a kind of preferred embodiments of the present invention adopts first-harmonic phase-locked, then the method that adopts frequency multiplication to calculate obtains the phase-locked value of each harmonic, and its process as shown in Figure 6.Obtain the angular frequency instantaneous value ω t of first-harmonic by line voltage being carried out software phlase locking, by its times N that multiply by harmonic wave, obtain the value of N ω t, for example N=(1,3,5,7 ... N), then obtain sin-cosN value among Fig. 6.The phase-locked value of the frequency multiplication that wherein will use in the formula is by the first-harmonic supply voltage is carried out software phlase locking, obtain its instantaneous ω t value, by it being multiply by the number of times of harmonic wave, obtain the value of N ω t, for example N=(3,5,7 ... N), then obtain the value of sinN ω t and cosN ω t, i.e. the value of sin-cosN among Fig. 6.

The below is introduced integrated control method according to the detection method of above-mentioned reactive current, negative-sequence current and harmonic current.According to Fig. 2, the three-phase instantaneous value i of the electric current I C that detection HSVG sends _Ca, i _Cb, i _CcDetect the three-phase instantaneous value i of bus current IS _Sa, i _Sb, i _ScDetect the three-phase instantaneous value i of HSVG active part current IS VG _Svga, i _Svgb, i _SvgcGather the dc voltage of modules, i.e. C among Fig. 2 _Cd-a1～C _Cd-aN, C _Cd-b1～C _Cd-bN, C _Cd-c1～C _Cd-cNOn voltage, obtain voltage and the U of each phase N DC side _AD, U _BD, U _CD

Because relatively idle, the pace of change of harmonic wave is fast, in order to improve its response speed, open loop control is adopted in harmonic wave control, namely sends with its amplitude as reference take the harmonic wave of obtaining load to equate that the harmonic wave of single spin-echo compensates.Yet the electric current of load generally is difficult to detect, so technical solution of the present invention adopts nodal method to obtain load current IL, and namely the three-phase instantaneous value of IL is i _La=i _Sa-i _Ca, i _Lb=i _Sb-i _Cb, i _Lc=i _Sc-i _Cc

Whole control is divided into based on the idle controlling unit of the fundamental positive sequence of FEEDBACK CONTROL, based on negative-sequence current controlling unit and a plurality of harmonic wave controlling unit of feedfoward control, as shown in Figure 7.Wherein, comprised fundamental positive sequence Detecting Reactive Current link in the idle controlling unit of fundamental positive sequence; Comprised the negative-sequence current detection in the negative-sequence current controlling unit; Comprised the harmonic current detection in the harmonic wave controlling unit.

1, the idle control of fundamental positive sequence:

(1) to i _Sa, i _Sb, i _ScCarry out obtaining after positive sequence DQ decomposes the i under the DQ coordinate _Sd1+And i _Sq1+, it is carried out obtaining after the low-pass filtering D. C. value i of real component and the idle component of fundamental positive sequence electric current _Sd1+And i _Sq1+

(2) to i _Svga, i _Svgb, i _SvgcCarry out obtaining after positive sequence DQ decomposes the i under the DQ coordinate _SvgdAnd i _Svgq, it is carried out obtaining after the low-pass filtering D. C. value of real component and the idle component of fundamental positive sequence electric current

With

(3) to U _AD, U _BD, U _CDSummation and reference voltage

Compare, wherein

Be each H bridge unit DC side control voltage

3N doubly, namely

To U _AD+ U _BD+ U _CDWith Difference carry out PI regulate after with the required active current i of the voltage control of controlling whole DC side _Cd-refTo gaining merit except carrying out overall control of DC side, also divide a PI control to the dc voltage of each H bridge;

(4) to busbar voltage V _AbcAfter carrying out DQ decomposition and filtering, obtain the u under the DQ coordinate _D-feedbackAnd u _Q-feedback

(5) according to i _Cd-ref,

i _Sq1+,

u _D-feedback, phase-locked value sin-cos1 be connected reactance La, Lb, the value WL of Lc under the DQ coordinate, can be according to shown in Figure 8, obtain voltage u under the DQ coordinate by two PI decoupling zeros controls _Sd1+And u _Sq1+, and it is carried out the DQ inverse transformation be compensated the idle and required Voltage Reference ripple V of dc voltage of positive sequence _A+, V _B+, V _C+

2, negative-sequence current control:

(1) to i _La=i _Sa-i _Ca, i _Lb=i _Sb-i _Cb, i _Lc=i _Sc-i _CcCarry out obtaining after negative phase-sequence DQ decomposes the i under the DQ coordinate _Sd1-And i _Sq1-, it is carried out obtaining after the low-pass filtering D. C. value i of real component and the idle component of fundamental negative sequence current _Sd1-And i _Sq1-

(2) according to i _Sd1-And i _Sq1-Be connected reactance La, Lb, the value WL of Lc under the DQ coordinate, calculate the voltage u under the DQ coordinate _Sd1-And u _Sq1-, and it is carried out the DQ inverse transformation namely get compensation negative sequence power required Voltage Reference ripple V _A-, V _B-, V _C-Wherein REF represents to calculate according to system and GB permissible value the DQ coordinate reference value of gained among Fig. 9.

3, harmonic wave control:

(1) to i _La=i _Sa-i _Ca, i _Lb=i _Sb-i _Cb, i _Lc=i _Sc-i _CcThe DQ that carries out each harmonic decomposes, and namely determines that according to harmonic number its attribute is positive sequence or negative phase-sequence, and the determined phase-locked sin-cosN of associating harmonic number carries out decomposing for DQ, obtains i _LdNAnd i _LqN

(2) according to i _LdNAnd i _LqNBe connected reactance La, Lb, the value NWL of Lc under the DQ coordinate, calculate the voltage u under the DQ coordinate _LdNAnd u _LqN, and it is carried out the DQ inverse transformation be compensated the required Voltage Reference ripple V of negative sequence power _Ah, V _Bh, V _ChWherein REF represents to calculate according to system and GB permissible value the DQ coordinate reference value of gained among Figure 10.

With the above-mentioned V that calculates _A+, V _B+, V _C+, V _A-, V _B-, V _C-And V _Ah, V _Bh, V _ChAddition obtains the reference voltage waveform $u_a^{*},u_b^{*},u_c^{*};$

$u_a^{*}=V_{a+}+V_{a-}+V_{\mathrm{ah}};$

$u_b^{*}=V_{b+}+V_{b-}+V_{\mathrm{bh}};$

$u_c^{*}=V_{c+}+V_{c-}+V_{\mathrm{ch}};$

Carry out the one pole multiple-frequency modulation of 180 °/N, produce 3N road triangular wave, with the instantaneous value of reference voltage

And anti-value

Relatively obtain the pulse of 6N road to trigger each H bridge unit, produce the voltage pwm ripple, PWM voltage produces corresponding harmonic wave, idle and negative-sequence current by connecting reactance.

It compensates waveform as shown in FIG. 11 and 12 emulation, and its load is 6 Pulses Rectifiers.Figure 11 is respectively compensating reactive power, the total compensation image of harmonics and negative sequence electric current, and wherein IL is the three-phase current of rectification load, and IC is the three-phase current that HSVG sends, and IS is the three-phase current of the rear bus of compensation.This method can compensate exactly as can be seen from Figure, the basic sineization of the bus current IS after the compensation.Figure 12 is for specifying the compensation effect of subharmonic, is respectively 5 times, 7 times, 11 times, 13 times compensation harmonic A phase currents and load A phase current among the figure, and wherein amplitude is larger is the load harmonic wave, and the less harmonic wave for compensation of amplitude.As can be seen from Figure, the described method of the specific embodiment of the invention can effectively be followed the tracks of each harmonic and compensated.

Technical scheme of the present invention belongs on high-tension side idle, the harmonics and negative sequence electric current of active compensation, and this has solved a difficult problem of directly in the high-pressure side high pressure harmonic wave being administered.In the high-pressure side direct compensation, with respect to the harmonic wave of present use by step-down in the low-pressure side compensation, compensation effect is good, speed is fast, more saves cost and floor space.

Consider that load mostly is inductive load, and SVG can be operated in capacitive and two kinds of operating modes of perception, it is in parallel with it that therefore selection waits the LC of capacity, and by LC filtering subharmonic.With respect to using pure SVG to carry out reactive power compensation, capacity has been saved half, takes full advantage of the active compensation capacity like this, and price reduces greatly.Based on the first-harmonic of multiple-rotating coordinate, the detection method of harmonics and negative sequence electric current, realized the separate detection of first-harmonic, harmonics and negative sequence electric current.Fundamental positive sequence is idle, the method for independently controlling of negative-sequence current and harmonic wave, mutually between without coupling, can realize reactive power, can select subharmonic and negative-sequence current to carry out alternative to compensate, flexibly, highly versatile.Harmonic wave is extracted in Fourier's gradation of using relatively at present or first-harmonic is controlled, Fourier analysis or fast Fourier analysis need the cycle of delaying time half at least, and invention technical scheme computation delay only has a digital employing cycle, and is simple, and amount of calculation reduces; With respect to the harmonic wave extracting method based on instantaneous reactive, can only the whole harmonic wave of disposable extraction based on the harmonic wave of instantaneous reactive, and technical solution of the present invention can gradation extract each harmonic, optionally extract, the compensation of realization frequency division, highly versatile, flexibly.

The above only is preferred implementation of the present invention; should be pointed out that for those skilled in the art, under the prerequisite that does not break away from the principle of the invention; can also make some improvements and modifications, these improvements and modifications also should be considered as protection scope of the present invention.

Claims (3)

1. high voltage linear type SVG integrated control device, link to each other with electrical network, it is characterized in that: each of high voltage linear type SVG integrated control device includes the LC filter branch mutually, connect reactance and H bridge units in series branch road, H bridge units in series branch road is with to be connected reactance series connection in parallel with the LC filter branch again, and the LC filter branch comprises inductance and electric capacity, and H bridge units in series branch road comprises the individual H bridge unit that is in series of N, N 〉=2, each H bridge unit comprises the bridge circuit that is comprised of four power components.

2. a kind of high voltage linear type SVG integrated control device according to claim 1, it is characterized in that: the power component of described bridge circuit is IGBT or IGCT, and the two ends of bridge circuit are parallel with electric capacity.

3. method that claim 1 or 2 described a kind of high voltage linear type SVG integrated control devices are controlled, it is characterized in that: described control method comprises the Comprehensive Control step, the Comprehensive Control step comprises:

(1) detects the three-phase instantaneous value i of the electric current I C that high voltage linear type SVG integrated control device sends _Ca, i _Cb, i _CcDetect the three-phase instantaneous value i of bus current IS _Sa, i _Sb, i _ScDetect the three-phase instantaneous value i of high voltage linear type SVG integrated control device active part current IS VG _Svga, i _Svgb, i _SvgcGather the dc voltage of each H bridge unit, obtain voltage and the U of each phase N DC side _AD, U _BD, U _CD

(2) the idle control procedure of fundamental positive sequence: to i _Sa, i _Sb, i _ScCarry out obtaining after positive sequence DQ decomposes the i under the DQ coordinate _Sd1+And i _Sq1+, with i _Sd1+And i _Sq1+Carry out obtaining after the low-pass filtering D. C. value i of real component and the idle component of fundamental positive sequence electric current _Sd1+And i _Sq1+To i _Svga, i _Svgb, i _SvgcCarry out obtaining after positive sequence DQ decomposes the i under the DQ coordinate _SvgdAnd i _Svgq, with i _SvgdAnd i _SvgqCarry out obtaining after the low-pass filtering D. C. value of real component and the idle component of fundamental positive sequence electric current

With

To U _AD, U _BD, U _CDSummation and reference voltage Compare, wherein

Be each H bridge unit DC side control voltage

3N doubly, namely

To U _AD+ U _BD+ U _CDWith Difference carry out PI regulate after to control the required active current i of whole DC voltage control _Cd-refTo busbar voltage V _AbcAfter carrying out DQ decomposition and filtering, obtain the u under the DQ coordinate _D-feedbackAnd u _Q-feedbackAccording to i _Cd-ref,

i _Sq1+,

u _D-feedback, phase-locked value sin-cos1 be connected reactance La, Lb, the value WL of Lc under the DQ coordinate, obtain voltage u under the DQ coordinate by two PI decoupling zeros control _Sd1+And u _Sq1+, and to u _Sd1+And u _Sq1+Carry out the DQ inverse transformation and be compensated the idle and required Voltage Reference ripple V of dc voltage of positive sequence _A+, V _B+, V _C+

(3) negative-sequence current control procedure: to i _La=i _Sa-i _Ca, i _Lb=i _Sb-i _Cb, i _Lc=i _Sc-i _CcCarry out obtaining after negative phase-sequence DQ decomposes the i under the DQ coordinate _Sd1-And i _Sq1-, with i _Sd1-And i _Sq1-Carry out obtaining after the low-pass filtering D. C. value i of real component and the idle component of fundamental negative sequence current _Sd1-And i _Sq1-According to i _Sd1-And i _Sq1-Be connected reactance La, Lb, the value WL of Lc under the DQ coordinate, calculate the voltage u under the DQ coordinate _Sd1-And u _Sq1-, and to u _Sd1-And u _Sq1-Carry out the DQ inverse transformation and namely get the required Voltage Reference ripple V of compensation negative sequence power _A-, V _B-, V _C-

(4) harmonic wave control procedure: to i _La=i _Sa-i _Ca, i _Lb=i _Sb-i _Cb, i _Lc=i _Sc-i _CcThe DQ that carries out each harmonic decomposes, and namely according to determining that together with the ripple number of times its attribute is positive sequence or negative phase-sequence, the determined phase-locked value sin-cosN of associating harmonic number carries out DQ and decomposes, and obtains i _LdNAnd i _LqNAccording to i _LdNAnd i _LqNBe connected reactance La, Lb, the value NWL of Lc under the DQ coordinate, calculate the voltage u under the DQ coordinate _LdNAnd u _LqN, and to u _LdNAnd u _LqNCarry out the DQ inverse transformation and be compensated the required Voltage Reference ripple V of negative sequence power _Ah, V _Bh, V _Ch

(5) according to following formula, with the above-mentioned V that calculates _A+, V _B+, V _C+, V _A-, V _B-, V _C-And V _Ah, V _Bh, V _ChAddition obtains the reference voltage waveform

$u_a^{*},u_b^{*},u_c^{*};$

$u_a^{*}=V_{a+}+V_{a-}+V_{\mathrm{ah}};$

$u_b^{*}=V_{b+}+V_{b-}+V_{\mathrm{bh}};$

$u_c^{*}=V_{c+}+V_{c-}+V_{\mathrm{ch}};$

Carry out the one pole multiple-frequency modulation of 180 °/N, produce 3N road triangular wave, with the instantaneous value of reference voltage And anti-value

Relatively obtain the pulse of 6N road to trigger each H bridge unit, produce the voltage pwm ripple, PWM voltage produces corresponding harmonic wave, idle and negative-sequence current by connecting reactance.

4, the hanging SVG integrated control method of a kind of high voltage direct according to claim 3, it is characterized in that: described Comprehensive Control step comprises detecting step, and detecting step comprises:

(1) gathers the current i that needs analysis _a, i _b, i _c

(2) fundamental positive sequence current detecting process: i _a, i _b, i _cObtain its first-harmonic part i by the band pass filter processing _A1, i _B1, i _C1, then obtain the meritorious and idle DC component i of the forward-order current of DQ coordinate by formula (3) matrixing _D1+, i _Q1+, this moment value n=1;

$\left[\begin{array}{c}{i}_{\mathrm{dl}+}\\ i_{\mathrm{ql}+}\end{array}\right]=\frac{2}{3}\left[\begin{array}{ccc}\sin \mathrm{n\&omega;t}& \sin (\mathrm{n\&omega;t}-\frac{2\mathrm{\&pi;}}{3})& \sin (\mathrm{n\&omega;t}+\frac{2\mathrm{\&pi;}}{3})\\ \cos \mathrm{n\&omega;t}& \cos (\mathrm{n\&omega;t}-\frac{2\mathrm{\&pi;}}{3})& \cos (\mathrm{n\&omega;t}+\frac{2\mathrm{\&pi;}}{3})\end{array}\right]\left[\begin{array}{c}{i}_{\mathrm{al}}\\ i_{\mathrm{bl}}\\ i_{\mathrm{cl}}\end{array}\right]---\left(3\right)$

Gain merit and idle component i by the positive sequence that the calculating to formula (3) obtains _D1+, i _Q1+Carry out low-pass filtering, and obtain i ' by multiply by after COEFFICIENT K is revised the amplitude of decay _D1+, i ' _Q1+, as the controlled quentity controlled variable of reactive current;

Again to idle active current and the reactive current amount i that carries out obtaining after the regulating and controlling DQ coordinate " _D1+, i " _Q1+, according to formula (4) to i " _D1+, i " _Q1+Carry out the DQ inverse transformation and obtain the three-phase forward-order current i ' of abc coordinate _A1+, i ' _B1+, i ' _C1+, this moment value n=1;

$\left[\begin{array}{c}{i}_{\mathrm{al}+}^{\&prime;}\\ i_{\mathrm{bl}+}^{\&prime;}\\ i_{\mathrm{cl}+}^{\&prime;}\end{array}\right]=\left[\begin{array}{cc}\sin \mathrm{\&omega;t}& \cos \mathrm{\&omega;t}\\ \sin (\mathrm{\&omega;t}-\frac{2\mathrm{\&pi;}}{3})& \cos (\mathrm{\&omega;t}-\frac{2\mathrm{\&pi;}}{3})\\ \sin (\mathrm{\&omega;t}+\frac{2\mathrm{\&pi;}}{3})& \cos (\mathrm{\&omega;t}+\frac{2\mathrm{\&pi;}}{3})\end{array}\right]\left[\begin{array}{c}{i}_{\mathrm{dl}+}^{\&prime;\&prime;}\\ i_{\mathrm{ql}+}^{\&prime;\&prime;}\end{array}\right]---\left(4\right)$

(3) negative-sequence current testing process: i _a, i _b, i _cObtain its first-harmonic part i by the band pass filter processing _A1, i _B1, i _C1, then obtain the meritorious and idle DC component i of the forward-order current of DQ coordinate by formula (5) matrixing _D1-, i _Q1-, this moment value n=1;

$\left[\begin{array}{c}{i}_{\mathrm{dl}-}\\ i_{\mathrm{ql}-}\end{array}\right]=\frac{2}{3}\left[\begin{array}{ccc}\sin \mathrm{n\&omega;t}& \sin (\mathrm{n\&omega;t}+\frac{2\mathrm{\&pi;}}{3})& \sin (\mathrm{n\&omega;t}-\frac{2\mathrm{\&pi;}}{3})\\ \cos \mathrm{n\&omega;t}& \cos (\mathrm{n\&omega;t}+\frac{2\mathrm{\&pi;}}{3})& \cos (\mathrm{n\&omega;t}-\frac{2\mathrm{\&pi;}}{3})\end{array}\right]\left[\begin{array}{c}{i}_{\mathrm{al}}\\ i_{\mathrm{bl}}\\ i_{\mathrm{cl}}\end{array}\right]---\left(5\right)$

Meritorious and the idle component i of the positive sequence that calculating obtains to formula (5) _D1-, i _Q1-Carry out low-pass filtering, and obtain i ' by multiply by after COEFFICIENT K is revised the amplitude of decay _D1-, i ' _Q1-, as the controlled quentity controlled variable of reactive current, active current and the reactive current amount i to obtaining the DQ coordinate after the negative sequence compensation regulating and controlling again " _D1-, i " _Q1-, according to formula (6) to i " _D1-, i " _Q1-Carry out the DQ inverse transformation obtain the three-phase negative/positive current i of abc coordinate ' _A1-, i ' _B1-, i ' _C1-, this moment value n=1;

$\left[\begin{array}{c}{i}_{\mathrm{al}-}^{\&prime;}\\ i_{\mathrm{bl}-}^{\&prime;}\\ i_{\mathrm{cl}-}^{\&prime;}\end{array}\right]=\left[\begin{array}{cc}\sin \mathrm{\&omega;t}& \cos \mathrm{\&omega;t}\\ \sin (\mathrm{\&omega;t}+\frac{2\mathrm{\&pi;}}{3})& \cos (\mathrm{\&omega;t}+\frac{2\mathrm{\&pi;}}{3})\\ \sin (\mathrm{\&omega;t}-\frac{2\mathrm{\&pi;}}{3})& \cos (\mathrm{\&omega;t}-\frac{2\mathrm{\&pi;}}{3})\end{array}\right]\left[\begin{array}{c}{i}_{\mathrm{dl}+}^{\&prime;\&prime;}\\ i_{\mathrm{ql}+}^{\&prime;\&prime;}\end{array}\right]---\left(6\right)$

(4) harmonic current testing process: i _a, i _b, i _cBand pass filter processing by lower limiting frequency in the setting is fixed subharmonic current i _AN, i _BN, i _CN, utilize formula (7) or formula (8) with i _AN, i _BN, i _CNBe transformed in the DQ coordinate system of N subharmonic; If N=3K+1 then calculates according to formula (7), wherein n=N; If N=3K-1 then calculates according to formula (8), obtain the DC component i of N subharmonic _DN, i _Q1N, n=N wherein;

$\left[\begin{array}{c}{i}_{\mathrm{dN}}\\ i_{\mathrm{qN}}\end{array}\right]=\frac{2}{3}\left[\begin{array}{ccc}\sin \mathrm{n\&omega;t}& \sin (\mathrm{n\&omega;t}-\frac{2\mathrm{\&pi;}}{3})& \sin (\mathrm{n\&omega;t}+\frac{2\mathrm{\&pi;}}{3})\\ \cos \mathrm{n\&omega;t}& \cos (\mathrm{n\&omega;t}-\frac{2\mathrm{\&pi;}}{3})& \cos (\mathrm{n\&omega;t}+\frac{2\mathrm{\&pi;}}{3})\end{array}\right]\left[\begin{array}{c}{i}_{\mathrm{aN}}\\ i_{\mathrm{bN}}\\ i_{\mathrm{cN}}\end{array}\right]---\left(7\right)$

$\left[\begin{array}{c}{i}_{\mathrm{dN}}\\ i_{\mathrm{qN}}\end{array}\right]=\frac{2}{3}\left[\begin{array}{ccc}\sin \mathrm{n\&omega;t}& \sin (\mathrm{n\&omega;t}+\frac{2\mathrm{\&pi;}}{3})& \sin (\mathrm{n\&omega;t}-\frac{2\mathrm{\&pi;}}{3})\\ \cos \mathrm{n\&omega;t}& \cos (\mathrm{n\&omega;t}+\frac{2\mathrm{\&pi;}}{3})& \cos (\mathrm{n\&omega;t}-\frac{2\mathrm{\&pi;}}{3})\end{array}\right]\left[\begin{array}{c}{i}_{\mathrm{aN}}\\ i_{\mathrm{bN}}\\ i_{\mathrm{cN}}\end{array}\right]---\left(8\right)$

Utilize formula (9) or formula (10) that the harmonic content of DQ coordinate is transformed in the abc coordinate system; If N=3K+1 then calculates according to formula (9), wherein n=N; If N=3K-1 then calculates according to formula (10), obtain DC component iaN, ibN, the icN of N subharmonic, wherein n=N;

$\left[\begin{array}{c}{i}_{\mathrm{aN}}\\ i_{\mathrm{bN}}\\ i_{\mathrm{cN}}\end{array}\right]=\left[\begin{array}{cc}\sin \mathrm{\&omega;t}& \cos \mathrm{\&omega;t}\\ \sin (\mathrm{\&omega;t}+\frac{2\mathrm{\&pi;}}{3})& \cos (\mathrm{\&omega;t}+\frac{2\mathrm{\&pi;}}{3})\\ \sin (\mathrm{\&omega;t}-\frac{2\mathrm{\&pi;}}{3})& \cos (\mathrm{\&omega;t}-\frac{2\mathrm{\&pi;}}{3})\end{array}\right]\left[\begin{array}{c}{i}_{\mathrm{dN}}\\ i_{\mathrm{qN}}\end{array}\right]---\left(9\right)$

$\left[\begin{array}{c}{i}_{\mathrm{aN}}\\ i_{\mathrm{bN}}\\ i_{\mathrm{cN}}\end{array}\right]=\left[\begin{array}{cc}\sin \mathrm{\&omega;t}& \cos \mathrm{\&omega;t}\\ \sin (\mathrm{\&omega;t}-\frac{2\mathrm{\&pi;}}{3})& \cos (\mathrm{\&omega;t}-\frac{2\mathrm{\&pi;}}{3})\\ \sin (\mathrm{\&omega;t}+\frac{2\mathrm{\&pi;}}{3})& \cos (\mathrm{\&omega;t}+\frac{2\mathrm{\&pi;}}{3})\end{array}\right]\left[\begin{array}{c}{i}_{\mathrm{dN}}\\ i_{\mathrm{qN}}\end{array}\right]---\left(10\right)$

Described detecting step comprises the phase-locked value calculation procedure of multifrequency, and the phase-locked value calculation procedure of multifrequency comprises: by line voltage being carried out the phase-locked angular frequency instantaneous value ω t that obtains first-harmonic; Multiply by the times N of harmonic wave by the angular frequency instantaneous value ω t of first-harmonic, obtain the value of N ω t, obtain the value of sin-cosN.

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