CN102842912B - Single carrier control method applicable to cascaded SVG - Google Patents

Abstract

The invention discloses a single carrier control method applicable to a cascaded SVG (Static Var Generator). The method comprises the following steps: acquiring the instantaneous values of power network voltage, grid-connected current, reactive instruction current and the direct current side voltage of each cascaded H bridge unit through a detection link and generating an SVG voltage modulating signal through voltage current double loop control; rounding off the voltage modulating signal, comparing the 'decimal part' acquired by rounding off with a single-channel triangular carrier signal to acquire one path of pulse signal P1, and adding the P1 and the 'integer part' acquired by rounding off to obtain one path of multilevel pulse signal; and distributing on-off action to a semiconductor power device according to the multilevel pulse signal, the current on-off state of a cascaded branch, the sequencing of direct current side voltage and the polarity of the grid-connected current so as to stabilize the direct current side voltage of each cascaded H bridge and control the grid-connected current. The harmonic characteristic of the method is more excellent than that of carrier phase-shift modulation; the on/off of power devices in the cascaded H bridges can be controlled by a single-channel triangular carrier; and the method is easy to implement.

Description

A kind of single carrier control method that is applicable to cascade connection type SVG

Technical field

The present invention relates to cascade connection type static reacance generator (SVG), particularly a kind of single carrier control method that is applicable to cascade connection type SVG.

Background technology

Cascade connection type SVG main circuit structure: take single-phase full bridge inverter circuit as H bridge unit, exchanging directly series connection of end by multiple H bridges unit, draw current transformer from first H bridge unit with last H bridge unit and exchange end, three are linked adopts star-like connection, then joins through linked reactor and electrical network.It has the following advantages: power demand number of devices is few, does not need clamps; Easily realize modularization, be easy to expansion, be suitable for different electric pressures.The nonlinear load of cascade connection type SVG in can centering high voltage distribution network carries out dynamic passive compensation and harmonic wave control, improves distribution network electric energy quality.

At present, the Multilevel modulation method that is applicable to cascade connection type SVG mainly contains phase-shifting carrier wave modulation and the stacked modulation of carrier wave.Phase-shifting carrier wave modulation is compared with modulation signal by the triangular carrier of one group of phase shift, generates multi-channel PWM ripple, for controlling the break-make of Cascade H bridge power device, can guarantee each power device switch motion equilibrium.The stacked modulation of carrier wave adopts one group of triangular carrier that amplitude is identical, frequency is identical, compare at the upper and lower pantostrat poststack of transverse axis and same modulating wave, export different level according to modulating wave from the comparative result of each triangular carrier, determine the break-make of corresponding power device.The stacked modulation of carrier wave is difficult to guarantee each power device switch motion equilibrium, but the stacked modulation of carrier wave homophase has good harmonic elimination performance.Be that phase-shifting carrier wave is modulated or the stacked modulation of carrier wave all needs multichannel triangular carrier signal and modulating wave comparison, realize difficulty large.

Summary of the invention

Technical problem to be solved by this invention is, for prior art deficiency, a kind of single carrier control method that is applicable to cascade connection type SVG is provided, reaches the object of stablizing each Cascade H bridge DC side voltage and controlling grid-connected current, realize the equilibrium of each power device switch motion.

For solving the problems of the technologies described above, the technical solution adopted in the present invention is: a kind of single carrier control method that is applicable to cascade connection type SVG, cascade connection type SVG comprises three cascade branch roads, each cascade branch road comprises the H bridge unit of several series connection, after the Y-connection of described three cascade branch roads through reactor and access three phase network and load between, described H bridge unit is single-phase full-bridge inverter, it is characterized in that, the step of the method is as follows:

1) detect and obtain each Cascade H bridge unit DC voltage signal (u _dai, u _dbi, u _dci), three phase network voltage signal (u _a, u _b, u _c), idle instruction current (i _qa, i _qb, i _qc) and grid-connected current signal (i _ca, i _cb, i _cc), generate SVG voltage modulation signal (u by the control of electric current and voltage dicyclo _ma, u _mb, u _mc);

2) to voltage modulation signal (u _ma, u _mb, u _mc) carry out single-carrier modulated, obtain many level pulses signal P ₂;

3) according to many level pulses signal P ₂, cascade branch road current on off state Q, the sequence of single-phase full-bridge inverter DC voltage and the polarity of grid-connected current, switch motion is dispensed to the semiconductor power device of single-phase full-bridge inverter, reaches the object of stablizing each Cascade H bridge unit DC voltage and controlling grid-connected current.

In described step 1), the step of electric current and voltage dicyclo control is:

1) the DC voltage summation to all H bridges unit in a cascade branch road, obtains DC side total voltage ∑ u _da, with DC voltage set-point u _d ^*relatively, generated error e, through digital PI link, obtains active current amplitude signal I _pa, then be multiplied by and this synchronous unit of cascade branch voltage sinusoidal signal, obtain active current instantaneous value i _pa; Wherein digital PI dominated formulate is as follows:

$I_{\mathrm{pa}}\left(k\right)=K_{p}e\left(k\right)+K_i\underset{j=0}{\overset{k}{\mathrm{\Σ}}}e\left(j\right)$

Wherein, k is sample sequence, I _pa(k) be the active current amplitude signal of k sampling instant pi regulator output, e (k) is k sampling instant DC voltage error, K _pfor pi regulator proportionality coefficient, K _ifor pi regulator integral coefficient;

2) by active current instantaneous value i _pawith idle instruction current i _qastack, obtains instruction current i _a; Instruction current i _awith the grid-connected current comparison of step 1) cascade branch road, through dead beat control, generate this cascade branch voltage modulation signal u _ma,

$u_{\mathrm{ma}}=\frac{L(i_a-i_{\mathrm{ca}})+u_a}{\mathrm{\Σ}{u}_{\mathrm{da}}\×T}\×N$

Wherein, L is reactor reactance value, and T is control cycle, and N is Cascade H bridge element number.

Described step 2) in, the step of single-carrier modulated is as follows:

1) the voltage modulation signal u to cascade branch road described in claim 2 _maround operation, obtain " integer part " u _ma1" fractional part " u _ma2:

u _ma1=max{n≤u _ma|n∈□}

u _ma2=u _ma-u _ma1

2) " fractional part " u of gained will be rounded _ma2with single channel triangular carrier signal U _carrrelatively, obtain 1 road pulse signal P _1a:

$P_{1a}=\left\{\begin{array}{cc}1& u_{\mathrm{<figure-callout\; id="2"\; label="ma"\; filenames="120912131908.png,120912131923.png"\; state="\{\{state\}\}">ma</figure-callout>}2}>U_{\mathrm{carr}}\\ 0& u_{\mathrm{<figure-callout\; id="2"\; label="ma"\; filenames="120912131908.png,120912131923.png"\; state="\{\{state\}\}">ma</figure-callout>}2}\&le;U_{\mathrm{carr}}\end{array}\right.$

3) by P _1awith " integer part " u that rounds gained _ma1be added, obtain 1 tunnel many level pulses signal P _2a:

P _2a=P _1a+u _ma1。

The process that switch motion is dispensed to the semiconductor power device of single-phase full-bridge inverter is:

1) determine the on off state Q of a cascade branch road: the left brachium pontis on off state that defines i H bridge unit is S _2i-1, right brachium pontis on off state is S _2i; If pipe conducting on brachium pontis, lower pipe cut-off, brachium pontis on off state is 1; If pipe cut-off on brachium pontis, lower pipe conducting, brachium pontis on off state is 0; Define i H bridge unit switch state H _ipoor for the left and right brachium pontis on off state of this H bridge, that is:

H _i=S _2i-1-S _2i

Definition cascade branch switch state Q is each Cascade H bridge unit switch state sum, that is: Q=H ₁+ H ₂+ H _i+ H _n; Wherein N is H bridge unit number;

2) many level pulse signal P _2awith cascade branch switch state Q, determine the changes delta Q of cascade branch switch state:

$\mathrm{\&Delta;Q}=\left\{\begin{array}{cc}1& P_{2a}>Q\\ -1& P_{2a}<Q\\ 0& P_{2a}=Q\end{array}\right.;$

3) switch motion is dispensed to H bridge: if Δ Q=1, cascade branch road grid-connected current >0, by switch motion priority allocation to the low H bridge unit of DC voltage; If Δ Q=1, cascade branch road grid-connected current≤0, by switch motion priority allocation to the high H bridge unit of DC voltage; If Δ Q=-1, cascade branch road grid-connected current >0, by switch motion priority allocation to the high H bridge unit of DC voltage; If Δ Q=-1, cascade branch road grid-connected current≤0, by switch motion priority allocation to the low H bridge unit of DC voltage;

4) switch motion is dispensed to brachium pontis: be the action frequency of the left and right brachium pontis in balance H bridge unit, introduce flag bit L _i; If L _i=1, carry out switch and divide timing preferentially left brachium pontis to be judged; If L _i=0, preferentially right brachium pontis is judged; If switch motion is dispensed to left brachium pontis the most at last, put L _i=0; If switch motion is dispensed to right brachium pontis the most at last, put L _i=1.

Compared with prior art, the beneficial effect that the present invention has is: the present invention is different with the stacked modulation of carrier wave from phase-shifting carrier wave modulation, only need single channel triangular carrier just can realize the break-make control to power device in Cascade H bridge unit, reach the object of stablizing each Cascade H bridge unit DC voltage and controlling grid-connected current; There is the good harmonic elimination performance of the stacked modulation of carrier wave homophase; And can realize the equilibrium of each power device switch motion.

Accompanying drawing explanation

Fig. 1 is five level cascade connection type SVG main circuit structure figure;

Fig. 2 is the single carrier control block diagram that is applicable to cascade connection type SVG;

Fig. 3 is five level cascade connection type SVG single-carrier modulated schematic diagrames; 3 (a) are for rounding process schematic diagram; 3 (b) are comparison procedure schematic diagram; 3 (c) are additive process schematic diagram;

Fig. 4 is the flow chart that switch motion is dispensed to H bridge unit; When 4 (a) are Δ Q=1, switch motion is dispensed to the flow chart of H bridge unit; When 4 (b) are Δ Q=-1, switch motion is dispensed to the flow chart of H bridge unit;

Fig. 5 is the flow chart that switch motion is dispensed to brachium pontis; 5 (a) are Δ H _iswitch motion in=1 o'clock is dispensed to the flow chart of brachium pontis; 5 (b) are Δ H _iswitch motion in=-1 o'clock is dispensed to the flow chart of brachium pontis.

Embodiment

Fig. 1 is five level cascade connection type SVG main circuit structure figure, take single-phase full bridge inverter circuit as H bridge unit, is directly composed in series at interchange end by 2 H bridge unit.Three are linked adopts star-like connection, then joins through linked reactor and electrical network.Wherein, single-phase full bridge inverter circuit comprises two brachium pontis in parallel in left and right and a DC bus capacitor branch road, and each brachium pontis is composed in series by two power devices, and DC bus capacitor branch road is in parallel with brachium pontis.Each Cascade H bridge input two-way, from the pwm signal of control system, is controlled respectively the break-make of two brachium pontis power devices, and is exported a road DC voltage signal.The nonlinear load of cascade connection type SVG in can centering high voltage distribution network carries out dynamic passive compensation and harmonic wave control, improves distribution network electric energy quality.

Fig. 2 is the single carrier control block diagram that is applicable to cascade connection type SVG.Detect and obtain each Cascade H bridge DC side voltage signal (u _dai, u _dbi, u _cdi), mains voltage signal (u _a, u _b, u _c), idle instruction current (i _qa, i _qb, i _qc) and grid-connected current signal (i _ca, i _cb, i _cc).Mutually as example, to each Cascade H bridge DC side voltage summation, obtain DC side total voltage ∑ u take A _da, with DC voltage set-point u _d ^*relatively, generated error e.Through digital PI link, obtain active current amplitude signal I _pa, then be multiplied by the sinusoidal signal with the synchronous unit of A phase voltage, obtain active current instantaneous value i _pa.Numeral PI dominated formulate is as follows:

$I_{\mathrm{pa}}\left(k\right)=K_{p}e\left(k\right)+K_i\underset{j=0}{\overset{k}{\mathrm{\&Sigma;}}}e\left(j\right)---\left(1\right)$

Wherein, k is sample sequence, I _pa(k) be the active current amplitude signal of k sampling instant pi regulator output, e (k) is k sampling instant DC voltage error, K _pfor pi regulator proportionality coefficient, K _ifor pi regulator integral coefficient.

By active current instantaneous value i _pawith idle instruction current i _qastack, obtains instruction current i _a; Instruction current i _awith SVG grid-connected current i _carelatively, through dead beat control (DBC), generate A phase voltage modulation signal u _ma,

$u_{\mathrm{ma}}=\frac{L(i_a-i_{\mathrm{ca}})+u_a}{\mathrm{\&Sigma;}{u}_{\mathrm{da}}\&times;T}\&times;N---\left(2\right)$

Wherein, L is for connecting reactance value, and T is control cycle, and N is Cascade H bridge number.

Voltage modulation signal u _madistribute link control main circuit power device break-make through single-carrier modulated and switch.The control procedure of B, C phase is mutually similar to A.

Fig. 3 five level cascade connection type SVG single-carrier modulated schematic diagrames.Voltage modulation signal u _mathrough rounding, compare, superpose three processes, generate many level pulses signal P ₂.Take A, mutually as example, single-carrier modulated process is as follows:

A) round.To voltage modulation signal u _maround operation, obtain " integer part " u _ma1" fractional part " u _ma2, as shown in Fig. 3 (a).Wherein, u _ma1for being not more than u _mamaximum integer.

u _ma1=max{n≤u _ma|n∈□}(3)

u _ma2=u _ma-u _ma1(4)

B) relatively." fractional part " u of gained will be rounded _ma2with single channel triangular carrier signal U _carrrelatively, obtain pulse signal P _1a, as shown in Fig. 3 (b).Work as u _ma2>U _carrtime, P _1abe 1; Work as u _ma2≤ U _carrtime, P _1abe 0.

$P_{1a}=\left\{\begin{array}{cc}1& u_{\mathrm{<figure-callout\; id="2"\; label="ma"\; filenames="120912131908.png,120912131923.png"\; state="\{\{state\}\}">ma</figure-callout>}2}>U_{\mathrm{carr}}\\ 0& u_{\mathrm{<figure-callout\; id="2"\; label="ma"\; filenames="120912131908.png,120912131923.png"\; state="\{\{state\}\}">ma</figure-callout>}2}\&le;U_{\mathrm{carr}}\end{array}\right.---\left(5\right)$

C) stack.By P _1awith " integer part " u that rounds gained _ma1be added, obtain 1 tunnel many level pulses signal P _2a, as shown in Fig. 3 (c).

P _2a=P _1a+u _ma1(6)

Fig. 4 is the flow chart that switch motion is dispensed to H bridge.

Carrying out before switch distribution, need to determine cascade branch road of SVG (take A mutually as example)

Current on off state Q and state increment Δ Q.

The left brachium pontis on off state that defines i H bridge is S _2i-1, right brachium pontis on off state is S _2i.If pipe conducting on brachium pontis, lower pipe cut-off, brachium pontis on off state is 1; If pipe cut-off on brachium pontis, lower pipe conducting, brachium pontis on off state is 0.

Define i H bridge switch state H _ipoor for the left and right brachium pontis on off state of this H bridge.That is:

H _i=S _2i-1-S _2i (7)

Definition A phase on off state Q is each Cascade H bridge switch state sum, that is:

Q=H ₁+H ₂…+H _i…+H _n (8)

For realizing A phase on off state Q to many level pulses signal P _2atracking, constantly relatively inverter switching states and many level pulses signal.If P _2a>Q, needs to increase Q, state increment Δ Q=1; If P _2a<Q, needs to reduce Q, state increment Δ Q=-1; If P _2a=Q, all brachium pontis are all failure to actuate, and Q remains unchanged, state increment Δ Q=0.

$\mathrm{\&Delta;Q}=\left\{\begin{array}{cc}1& P_{2a}>Q\\ -1& P_{2a}<Q\\ 0& P_{2a}=Q\end{array}\right.---\left(9\right)$

Work as P _2awhen ≠ Q, meet often more than one of the brachium pontis of operation condition, for SVG DC voltage energy imbalance, the present invention adopts a kind of switch allocation strategy with reference to DC voltage sequence.

For 2N+1 electrical level inverter, there is N independently DC side.Link obtains the instantaneous value of DC voltage after testing, deposits array u in _d[N].Adopt bubbling method to array u _d[N] carries out descending sequence, and the subscript after sequence is recorded in to array T[N].Take 9 electrical level inverters as example, have 4 independently DC side, suppose that first Cascade H bridge DC side voltage is 740V, second Cascade H bridge DC side voltage is 735V, the 3rd Cascade H bridge DC side voltage is 760V, and the 4th Cascade H bridge DC side voltage is 720V.U before sequence _d[N] is { 740,735,760,720}, u after sequence _d[N] be 760,740,735,720}, array T[N] be { 3,1,2,4}.

In the time of Δ Q=1, state of need selection is not 1 H bridge execution switch motion, increases its on off state.If grid-connected current i _c>0, carries out this switch motion by improving the input power of this H bridge, is the each H bridge DC side of balance voltage, preferentially this switch motion is dispensed to the H bridge that DC voltage is low.With reference to DC voltage from low to high successively to H bridge state H _t[N], H _t[N-1]... H _t[1]judge, until the state of finding out is not 1 H bridge, make its on off state increment Delta H _i=1.If grid-connected current i _c≤ 0, carry out this switch motion by reducing the input power of this H bridge, be the each H bridge DC side of balance voltage, preferentially this switch motion is dispensed to the H bridge that DC voltage is high.With reference to DC voltage from high to low successively to H _t[1], H _t[2]... H _t[N]judge, until the state of finding out is not 1 H bridge, make its on off state increment Delta H _i=1.As shown in Fig. 4 (a).

In the time of Δ Q=-1, state of need selection is not-1 H bridge execution switch motion, reduces its on off state.If grid-connected current i _c>0, successively to H _t[1], H _t[2]... H _t[N]judge, until the state of finding out is not-1 H bridge, make its on off state increment Delta H _i=-1.If grid-connected current i _c≤ 0, successively to H _t[N], H _t[N-1]... H _t[1]judge, the state of finding out is not-1 H bridge, makes its on off state increment Delta H _i=-1.As shown in Fig. 4 (b).

Fig. 5 is the flow chart that switch motion is dispensed to brachium pontis.

For the action frequency of the left and right brachium pontis in balance H bridge, introduce flag bit L _i.If L _i=1, switch divides timing preferentially left brachium pontis to be judged; If L _i=0, preferentially right brachium pontis is judged.If switch motion is dispensed to left brachium pontis the most at last, put L _i=0, in the time that switch motion is dispensed to this H bridge again, preferentially right brachium pontis is judged.If switch motion is dispensed to right brachium pontis the most at last, put L _i=1, in the time that switch motion is dispensed to this H bridge again, preferentially left brachium pontis is judged.

As Δ H _i=1 o'clock, switch assigning process was as shown in Fig. 5 (a).If L _i=1 and left brachium pontis state S _2i-1=0, left brachium pontis is carried out switch motion, and state turnover is 1, and by L _iset to 0; If L _i=1 and left brachium pontis state S _2i-1=1, right brachium pontis is carried out switch motion, and state turnover is 0, L _iremain unchanged; If L _i=0 and right brachium pontis state S _2i=1, right brachium pontis is carried out switch motion, and state turnover is 0, and by L _iput 1; If L _i=0 and right brachium pontis state S _2i=0, left brachium pontis is carried out switch motion, and state turnover is 1, L _iremain unchanged.

As Δ H _i=-1 o'clock, switch assigning process was as shown in Fig. 5 (b).If L _i=1 and left brachium pontis state S _2i-1=1, left brachium pontis is carried out switch motion, and state turnover is 0, and by L _iset to 0; If L _i=1 and left brachium pontis state S _2i-1=0, right brachium pontis is carried out switch motion, and state turnover is 1, and L _iremain unchanged; If L _i=0 and right brachium pontis state S _2i=0, right brachium pontis is carried out switch motion, and state turnover is 1, and by L _iput 1; If L _i=0 and right brachium pontis state S _2i=1, left brachium pontis is carried out switch motion, and state turnover is 0, and by L _iset to 0.

Claims (2)

1. one kind is applicable to the single carrier control method of cascade connection type SVG, cascade connection type SVG comprises three cascade branch roads, each cascade branch road comprises the H bridge unit of several series connection, after the Y-connection of described three cascade branch roads through reactor and access three phase network and load between, described H bridge unit is single-phase full-bridge inverter, it is characterized in that, the step of the method is as follows:

(1) detect obtain each Cascade H bridge unit DC voltage signal ( u _dai , u _dbi , u _dci ), three phase network voltage signal ( u _a , u _b , u _c ), idle instruction current ( i _qa , i _qb , i _qc ) and grid-connected current signal ( i _ca , i _cb , i _cc ), by the control of electric current and voltage dicyclo generate SVG voltage modulation signal ( u _ma , u _mb , u _mc );

(2) to voltage modulation signal ( u _ma , u _mb , u _mc ) carry out single-carrier modulated, obtain many level pulses signal p ₂ ;

(3) according to many level pulses signal p ₂ , cascade branch road current on off state q, the sequence of single-phase full-bridge inverter DC voltage and the polarity of grid-connected current, switch motion is dispensed to the semiconductor power device of single-phase full-bridge inverter, reach the object of stablizing each Cascade H bridge unit DC voltage and controlling grid-connected current;

In described step (1), the step of electric current and voltage dicyclo control is:

A) the DC voltage summation to all H bridges unit in a cascade branch road, obtains DC side total voltage ∑ u _da , with DC voltage set-point u _d ^* relatively, generated error e, through digital PI link, obtain active current amplitude signal i _pa , then be multiplied by and this synchronous unit of cascade branch voltage sinusoidal signal, obtain active current instantaneous value i _pa ; Wherein digital PI dominated formulate is as follows:

Wherein, kfor sample sequence, i _pa (k)be kthe active current amplitude signal of individual sampling instant pi regulator output, e (k)be kindividual sampling instant DC voltage error, k _p for pi regulator proportionality coefficient, k _i for pi regulator integral coefficient;

B) by active current instantaneous value i _pa with idle instruction current i _qa stack, obtains instruction current i _a ; Instruction current i _a with the grid-connected current comparison of step a) cascade branch road, through dead beat control, generate this cascade branch voltage modulation signal u _ma ,

Wherein, lfor reactor reactance value, tfor control cycle, nfor Cascade H bridge element number;

The step of described single-carrier modulated is as follows:

1) voltage modulation signal to described cascade branch road u _ma round operation, obtain " integer part " u _ma1 " fractional part " u _ma2 :

2) will round " fractional part " of gained u _ma2 with single channel triangular carrier signal u _carr relatively, obtain 1 road pulse signal p _1a :

3) will p _1a with " integer part " that round gained u _ma1 be added, obtain 1 tunnel many level pulses signal p _2a :

。

2. the single carrier control method that is applicable to cascade connection type SVG according to claim 1, is characterized in that, the process that switch motion is dispensed to the semiconductor power device of single-phase full-bridge inverter is:

1) determine the on off state of a cascade branch road q: definition the ithe left brachium pontis on off state of individual H bridge unit is s _2i-1 , right brachium pontis on off state is s _2i ; If pipe conducting on brachium pontis, lower pipe cut-off, brachium pontis on off state is 1; If pipe cut-off on brachium pontis, lower pipe conducting, brachium pontis on off state is 0; Definition the iindividual H bridge unit switch state h _i poor for the left and right brachium pontis on off state of this H bridge, that is:

Definition cascade branch switch state qfor each Cascade H bridge unit switch state sum, that is:

; Wherein N is H bridge unit number;

2) many level pulse signals p _2a with cascade branch switch state q, determine the variation of cascade branch switch state △ Q:

；

3) switch motion is dispensed to H bridge: if △ Q=1, cascade branch road grid-connected current >0, by switch motion priority allocation to the low H bridge unit of DC voltage; If △ Q=1, cascade branch road grid-connected current≤0, by switch motion priority allocation to the high H bridge unit of DC voltage; If △ Q=-1, cascade branch road grid-connected current >0, by switch motion priority allocation to the high H bridge unit of DC voltage; If △ Q=-1, cascade branch road grid-connected current≤0, by switch motion priority allocation to the low H bridge unit of DC voltage;

4) switch motion is dispensed to brachium pontis: be the action frequency of the left and right brachium pontis in balance H bridge unit, introduce flag bit l _i ; If l _i =1, carry out switch and divide timing preferentially left brachium pontis to be judged; If l _i =0, preferentially right brachium pontis is judged; If switch motion is dispensed to left brachium pontis the most at last, put l _i =0; If switch motion is dispensed to right brachium pontis the most at last, put l _i =1;

If l _i =1 and left brachium pontis state s _2i-1 =0, left brachium pontis is carried out switch motion, and state turnover is 1, and will l _i set to 0; If l _i =1 and left brachium pontis state s _2i-1 =1, right brachium pontis is carried out switch motion, and state turnover is 0, l _i remain unchanged; If l _i =0 and right brachium pontis state s _2i =1, right brachium pontis is carried out switch motion, and state turnover is 0, and will l _i put 1; If l _i =0 and right brachium pontis state s _2i =0, left brachium pontis is carried out switch motion, and state turnover is 1, l _i remain unchanged;

If l _i =1 and left brachium pontis state s _2i-1 =1, left brachium pontis is carried out switch motion, and state turnover is 0, and will l _i set to 0; If l _i =1 and left brachium pontis state s _2i-1 =0, right brachium pontis is carried out switch motion, and state turnover is 1, l _i remain unchanged; If l _i =0 and right brachium pontis state s _2i =0, right brachium pontis is carried out switch motion, and state turnover is 1, and will l _i put 1; If l _i =0 and right brachium pontis state s _2i =1, left brachium pontis is carried out switch motion, and state turnover is 0, and will l _i set to 0.

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