CN1450704A - Method for compensating dynamic three-phase imbalance load and compensator - Google Patents

Abstract

A method for compensating dynamic three-phase unbalanced loadsand and its device characterizing in sampling values of line voltage and load line current of two sample points at the connecting place of the compensation device and the system to compute related sine signal basic wave symmetric component, then to calculate positive and negative sequential compensator threephase equal susceptance, the sum of which is the three-phase susceptance value for compensating load unbalance and providing reactive current for the load, the susceptance reference value to be converted to a control angle signal and an order of the thyristor switched capacitor to be sent to the pulse generation plate and the condenser zero-cross trigger plate for controlling two devices.

Description

The method of compensating dynamic three-phase imbalance load and compensation arrangement

Technical field

A kind of method of compensating dynamic three-phase imbalance load and compensation arrangement belong to electric power system unbalance load compensation technical field.

Background technology

In electrical power trans mission/distribution system, to compensate the imbalance of dynamic load, eliminate harmful negative-sequence current that uncompensated load causes in system; Simultaneously the needed reactive power of loading is compensated fast, improve the system power factor, reduce voltage fluctuation.Its first key is that the dfundamental-harmonic pair that controller must be calculated load current fast and accurately weighs, and second key is to propose to come in view of the above the effective computer implemented method that compensates.

Using the principle of preface component filter and phasor identifier, go to realize with computer software, is the digital method of widely used calculating symmetrical component, sees " the reactive power compensation vector control " of the diligent work of Sun Shu, China Electric Power Publishing House, 1998; " Microcomputer Protection is realized principle and device " of Luo Shiping work, China Electric Power Publishing House, 2001; But its principle itself can cause the time-delay that surpassed for 1/4th primitive periods, and, for avoiding being subjected to the influence of contained harmonic component in the signal, must add the filtering link, introduce additional time-delay again, total time delay is still bigger.The other algorithm, combine new mathematic(al) manipulation form and filtering method, to reach both no influence from harmonic, calculate again target quickly and accurately, see P.Sharma, S.I.Ahson, andJ.Henry.Microprocessor Implementation of fast Walsh-Hadamard Transform for Calculation ofSymmetrical Components.Proceedings of the IEEE, Vol.76, No.10,1385-1388, Oct.1988. and T.Lobos.Fast Estimation of Symmetrical components in Real Time.IEE Proceedings-C, vol.139, No.1, Jan.1992. etc., but time delay is generally all at 3/4ths more than the primitive period.

At document L.Gyugyi, R.A.Otto, T.H.Putman.Principles and Applications of Static, Thristor-Controlled Shunt Compensators.IEEE Trans.on Power Apparatus and System, 1978, PAS-97 (5): propose among the 1935-1945.: compensation arrangement can be divided and make two parts, part three-phase susceptance is a balance, under the positive sequence symmetrical voltage, only produce forward-order current, be used to provide the required reactive current of load or keep voltage, be called the positive sequence compensator; Another part three-phase susceptance imbalance only produces negative-sequence current under the positive sequence symmetrical voltage, be used for offsetting the negative-sequence current that uncompensated load causes, is called the negative sequence compensation device.They can be realized with same compensator as shown in Figure 1, but not propose a kind of digitized practicable compensation method in the literature.

Summary of the invention

Content of the present invention is a kind of method and compensation arrangement of compensating dynamic three-phase imbalance load, it provides a kind of principle simple, realize easily, the precision height, postpone the method that little calculating three-phase sinusoidal signal dfundamental-harmonic pair weighs, simultaneously, its compensation arrangement is by adjusting the equivalent susceptance in the connecting system automatically, can compensate the imbalance of dynamic load, eliminate harmful negative-sequence current that uncompensated load causes in system; Simultaneously the needed reactive power of loading is compensated fast, improve the system power factor, reduce voltage fluctuation.

Compensation method of the present invention is characterised in that:

It contains successively and has the following steps:

(1) reads three line currents of three the line voltage and the load of it and system junction with compensation arrangement, read the set point of user controlled target;

(2) result that sampling is read deposits in the data field and the corresponding position of current sampling point sequence number;

(3) carry out the data processing of uneven control with function d ataprocu (), it contains successively and has the following steps:

1) with the FIR low pass filter to adopt into system line voltage and load line current signal carry out filtering;

2) to any one road signal, by its two adjacent sampled value e ₁, e ₂, calculate its phase place α and effective value E according to following formula in first sampling instant: $\mathrm{tg\&alpha;}={\mathrm{<figure-callout\; id="1"\; label="e"\; filenames="A02103873.200171.png,A02103873.200181.png"\; state="\{\{state\}\}">e</figure-callout>}}_1\sin \mathrm{\&omega;}{T}_s/(e_2-{\mathrm{<figure-callout\; id="1"\; label="e"\; filenames="A02103873.200171.png,A02103873.200181.png"\; state="\{\{state\}\}">e</figure-callout>}}_1\cos \mathrm{\&omega;}{T}_s),$ $\sqrt{{{\mathrm{<figure-callout\; id="1"\; label="e"\; filenames="A02103873.200171.png,A02103873.200181.png"\; state="\{\{state\}\}">e</figure-callout>}}_1}^2+{{\mathrm{<figure-callout\; id="2"\; label="e"\; filenames="A02103873.200171.png,A02103873.200181.png"\; state="\{\{state\}\}">e</figure-callout>}}_2}^2-2e_1{\mathrm{<figure-callout\; id="2"\; label="e"\; filenames="A02103873.200171.png,A02103873.200181.png"\; state="\{\{state\}\}">e</figure-callout>}}_2\cos \mathrm{\&omega;}{T}_s}/\sqrt{2}\sin \mathrm{\&omega;}{T}_s,$ Wherein, T _sBe the time interval of sampling, i.e. in the sampling period, ω is the angular frequency of signal, in electric power system under the normal condition, and ω=100 π;

3) effective value and the phase place of above-mentioned each signal of obtaining are made integral filtering;

4) be reference quantity with ab line voltage,, obtain their phasor form according to the effective value and the phase place of voltage, electric current: $\stackrel{.}{E}=E\&angle;\mathrm{\&alpha;}=\sqrt{2}E(\cos \mathrm{\&alpha;}+j\sin \mathrm{\&alpha;});$

5) by the definition of symmetrical component method, the symmetrical component of calculation system line voltage and load line electric current: $\left[\begin{array}{c}{\stackrel{.}{E}}_1\\ {\stackrel{.}{E}}_2\\ {\stackrel{.}{E}}_0\end{array}\right]=\frac{1}{3}\left[\begin{array}{ccc}1& a& a^2\\ 1& a^2& a\\ 1& 1& 1\end{array}\right]\left[\begin{array}{c}{\stackrel{.}{E}}_{\mathrm{ab}}\\ {\stackrel{.}{E}}_{\mathrm{bc}}\\ {\stackrel{.}{E}}_{\mathrm{ca}}\end{array}\right],$ $\left[\begin{array}{c}{\stackrel{.}{I}}_{a1}\\ {\stackrel{.}{I}}_{a2}\\ {\stackrel{.}{I}}_{a0}\end{array}\right]=\frac{1}{3}\left[\begin{array}{ccc}1& a& a^2\\ 1& a^2& a\\ 1& 1& 1\end{array}\right]\left[\begin{array}{c}{\stackrel{.}{I}}_a\\ {\stackrel{.}{I}}_b\\ {\stackrel{.}{I}}_c\end{array}\right],$ α=e wherein ^{J2/3 π},

Be three line voltages of system,

Be three line currents of load,

With

Represent positive sequence, negative phase-sequence and zero-sequence component respectively;

6) try to achieve phase current by the positive sequence component of load line electric current ${\stackrel{.}{I}}_l={\stackrel{.}{I}}_{a1}{e}^{\mathrm{j\&pi;}/6}/\sqrt{3},$ And real component $I_p=\mathrm{Re}{\stackrel{.}{I}}_l,$ Idle component $I_q=\mathrm{Im}{\stackrel{.}{I}}_l.$

(4) usefulness function negatb () calculates three equal value susceptance of negative sequence compensation device, the three-phase susceptance of negative sequence compensation device part

By following various obtaining: $B_{N,\mathrm{ab}}^{\left(c\right)}E=1/\sqrt{3}\mathrm{Re}{\stackrel{.}{I}}_{a2}-\mathrm{Im}{\stackrel{.}{I}}_{a2},$ $B_{N,\mathrm{bc}}^{\left(c\right)}E=1/\sqrt{3}\mathrm{Re}{\stackrel{.}{I}}_{a2}+\mathrm{Im}{\stackrel{.}{I}}_{a2},$ $B_{N,\mathrm{ca}}^{\left(c\right)}E=-2/\sqrt{3}\mathrm{Re}{\stackrel{.}{I}}_{a2};$

(5) calculate positive sequence compensator three equal value susceptance with function positb (), it is relevant with controlled target: establish: controlled target be voltage then: by pi regulator according to the user to the set point of voltage and the error of voltage actual value, calculate three equal value susceptance of compensation arrangement positive sequence compensator $B_p^{\left(c\right)}=K_{p}e+K_i\mathrm{\&Sigma;e},$ $e=E-E_{\mathrm{ref}},$ E _RefBe the set point of line voltage, E is the actual value of line voltage, K _pBe proportionality coefficient, K _iBe integral coefficient; If: controlled target be power factor then: by the real component I of negative-sequence current _p, idle component I _q, system line voltage E substitution following formula is compensated three equal value susceptance of device positive sequence compensator

$B_p^{\left(c\right)}=(I_p\&CenterDot;\sqrt{1/{{\mathrm{\&lambda;}}_{\mathrm{ref}}}^2-1}-I_q)/E,$ λ wherein _RefThe load of setting for the user total power factor after overcompensation;

(6) the actual every phase susceptance value that should export of compensation arrangement, promptly the susceptance reference value is equivalent susceptance of positive sequence compensator and the equivalent susceptance sum of negative sequence compensation device;

(7) with function tcrtsccomu () each phase susceptance reference value is converted to TCR pilot angle and the instruction of TSC switching, it contains following steps successively:

1) do you differentiate susceptance reference value＞0? if: be that then the instruction of TSC switching puts 1, TCR susceptance reference value=susceptance reference value-TSC susceptance; If: not, then the instruction of TSC switching puts 0, TCR susceptance reference value=susceptance reference value;

2) the k=rounding-off method rounds (TCR susceptance reference value * 100);

3) TCR pilot angle ang=alpha[k], alpha[] be the array of preserving the pilot angle of susceptance reference value correspondence;

4) TCR pilot angle voltage V _AngFor:

V wherein _MaxBe the voltage of 90 ° of pilot angle correspondences, V _MinBe the voltage of 180 ° of pilot angle correspondences;

5) output TCR pilot angle voltage and TSC switching instruction;

(8) finish, return.The method of setting up TCR susceptance reference value～pilot angle correspondence table in the described step (7) contains successively and has the following steps:

(1) the n five equilibrium is carried out in equivalent susceptance output area 0～-1 of compensation arrangement TCR, obtain n+1 point sequence a: B ₀, B ₁..., B _n

(2) with each the some B in the sequence _k, k=0 ..., n, the formula of substitution bottom is found the solution corresponding pilot angle α with Newton iteration method _kValue: $B_R\mathrm{\&alpha;}=-\frac{2(\mathrm{\&pi;}-\mathrm{\&alpha;})+\mathrm{<figure-callout\; id="2"\; label="sin"\; filenames="A02103873.200171.png,A02103873.200181.png"\; state="\{\{state\}\}">sin</figure-callout>}2\mathrm{\&alpha;}}{\mathrm{\&pi;}{X}_R},$ Wherein, B _R(α) for for first-harmonic, the equivalent susceptance value of the reactor of thyristor control, X _RBe the fundamental reactance of reactor, and the admittance value of agreement reactor is for negative, the admittance value of capacitor is for just;

(3) with α ₀, α ₁..., α _nValue when the unit of converting to is " degree " deposits n+1 dimension group alpha[in] in, because alpha[k] corresponding susceptance reference value B _k=-k/n, so susceptance reference value B _kCorresponding pilot angle α _kAt array alpha[] in subscript k=-B _k* n.

When the precision of phase shift trigger board phase shift was 1 °, the n value was 100.

The feature of compensation arrangement of the present invention: it contains: Chuan Jie controller, light sender unit-light collection of letters device-output pulses circuits for triggering and be serially connected with main circuit between each line of system's three-phase successively; TCR pulse generation plate and TSC zero cross fired plate that its middle controller receives DSP control board output signal by the DSP control board, respectively constitute; Main circuit contains thyristor-controlled reactor (TCR) that is composed in series by a pair of antiparallel thyristor and reactor and the thyristor switchable capacitor of being made up of a pair of antiparallel thyristor and capacitors in series (TSC).Described TSC zero cross fired plate is the phase-splitting cross-zero trigger controller that thyristor switchable capacitor is used, it is by the Hall element formula voltage detecting circuit that links to each other with antiparallel thyristor two ends, input links to each other with this voltage detecting circuit output and can be converted into signaling conversion circuit with the synchronous square wave voltage signal of voltage at thyristor two ends to the little current signal of input, the zero passage detection signal generating circuit that links to each other with this signaling conversion circuit output, the OR circuit that input links to each other with the input or the excision signal output part of the output of this zero passage detection signal generating circuit and controller respectively links to each other with this OR circuit output and the delay circuit and the input of the EDM Generator of Adjustable Duty Ratio of the square-wave voltage of its output link to each other with this delay circuit output and the thyristor trigger impulse formation circuit of the Frequency Adjustable that each control end of output and anti-parallel thyristor links to each other.

Use proof: it has realized re-set target.

Description of drawings

Fig. 1: the equivalents of compensation arrangement.

Fig. 2: function Adintserv () flow chart.

Fig. 3: function d ataprocu () flow chart.

Fig. 4: use " two-point method " to ask voltage effective value oscillogram used when giving an example in the symmetrical component process:

4a:A phase voltage effective value oscillogram,

4b: positive sequence voltage effective value oscillogram,

4c: negative sequence voltage effective value oscillogram.

Fig. 5: function negatb () flow chart.

Fig. 6: function positb () flow chart.

Fig. 7: function tcrtsccomu () flow chart.

Fig. 8: the equivalents of load.

Fig. 9: the three-phase system that asymmetric load and compensation arrangement are formed.

Figure 10: TCR circuit theory and current waveform figure:

The 10a:TCR circuit theory diagrams,

The 10b:TCR current waveform figure.

Figure 11: the schematic block circuit diagram of compensation arrangement.

Figure 12: the schematic block circuit diagram of DSP control board.

Figure 13: system line current waveform figure before and after (only bc has resistive load mutually) compensation arrangement drops under the uncompensated load.

Figure 14: the theory diagram of TSC zero cross fired plate.

Table 1: the effective value of system line voltage before and after compensation arrangement drops under Figure 13 situation.

Embodiment

In conjunction with Fig. 1～Figure 10 this method is illustrated earlier.

Handling uneven control data with function d ataprocu (), i.e. the positive-negative sequence component of negate lotus line current and the real component I of phase current _pWith idle component I _qThe time, the dfundamental-harmonic pair that " two-point method " that has used the present invention to propose calculates three-phase sinusoidal signal weighs.Its concrete computational process is as follows:

To any phase input signal,, calculate frequency, effective value and the phase place of input signal by the value of three sampled points of input signal by trigonometric function operation.Then, calculate the positive and negative zero-sequence component of three-phase signal by the definition of symmetrical component method.The time-delay of algorithm itself only is 3 times sampling interval.If the frequency of input signal is known, such as in electric power system, signal frequency be 50 hertz constant, so, utilize the data of two sampled points just can calculate above-mentioned each amount, further improve response speed.At this moment the time-delay of algorithm itself only is 2 times sampling interval.With per primitive period sampling is example 40 times, and the sampling interval is 0.5ms, and the time-delay of algorithm itself is 1ms.Be referred to as " two-point method " hereinafter.Specifying of algorithm is as follows.

With the voltage signal is example.If the voltage signal of A phase is $e_a=\sqrt{2}{E}_a\sin \mathrm{\&omega;t}---\left(1\right)$

e ₁, e ₂, e ₃For to e _aThree neighbouring sample values of sampling.Have ${\mathrm{<figure-callout\; id="1"\; label="e"\; filenames="A02103873.200171.png,A02103873.200181.png"\; state="\{\{state\}\}">e</figure-callout>}}_1=\sqrt{2}{E}_a\sin \mathrm{\&alpha;}---\left(2\right)$ $e_2=\sqrt{2}{E}_a\sin (\mathrm{\&alpha;}+\mathrm{\&omega;}{T}_s)---\left(3\right)$ $e_3=\sqrt{2}{E}_a\sin (\mathrm{\&alpha;}+2\mathrm{\&omega;}{T}_s)---\left(4\right)$

Wherein α is first sampling instant e _aPhase angle, T _sBe the blanking time of double sampling, i.e. sampling period.We can prove following various establishment

cosωT _s＝(e ₁+e ₃)/2e ₂ (5)

tga＝e ₁sinωT _s/(e ₂-e ₁cosωT _s) (6) $E_a=\sqrt{{{\mathrm{<figure-callout\; id="1"\; label="e"\; filenames="A02103873.200171.png,A02103873.200181.png"\; state="\{\{state\}\}">e</figure-callout>}}_1}^2+{{\mathrm{<figure-callout\; id="2"\; label="e"\; filenames="A02103873.200171.png,A02103873.200181.png"\; state="\{\{state\}\}">e</figure-callout>}}_2}^2-2e_1{\mathrm{<figure-callout\; id="2"\; label="e"\; filenames="A02103873.200171.png,A02103873.200181.png"\; state="\{\{state\}\}">e</figure-callout>}}_2\cos \mathrm{\&omega;}{T}_s}/\sqrt{2}\sin \mathrm{\&omega;}{T}_s---\left(7\right)$

So just, can obtain phase place and the effective value of A phase voltage, calculate A phase voltage phasor in first sampling instant If frequency that can supposing the system is constant, promptly be fixed as 50 hertz, so ω T _sBe a definite value, utilize (6), (7) two formulas, calculate e _aPhase place and effective value only need e ₁, e ₂Two sampled values get final product.In like manner can calculate B, the effective value of C two phase voltages and the phase place of synchronization.With A phase voltage phase place is reference, can obtain B, C two-phase voltage phasor

With Then, according to the definition of symmetrical component method $\left[\begin{array}{c}{\stackrel{.}{E}}_1\\ {\stackrel{.}{E}}_2\\ {\stackrel{.}{E}}_0\end{array}\right]=\frac{1}{3}\left[\begin{array}{ccc}1& a& a^2\\ 1& a^2& a\\ 1& 1& 1\end{array}\right]\left[\begin{array}{c}{\stackrel{.}{E}}_a\\ {\stackrel{.}{E}}_b\\ {\stackrel{.}{E}}_c\end{array}\right]$ Wherein, a=e ^{J2/3 π}(8) just can calculate the positive and negative zero-sequence component of three-phase voltage.

The symmetrical component algorithm of current signal is identical with the top.

If calculate the phasor of voltage and load current simultaneously, then according to the definition to reactive current: electric current phasor can be obtained the idle component of load current perpendicular to the projection on the voltage phasor direction, is used for control compensation device output corresponding compensation electric current.

More than in the explanation, we suppose that input signal does not contain harmonic wave.May have harmonic wave under the actual conditions, need do following processing: at first input signal be carried out low-pass filtering, remove the harmonic components in the signal, only keep the first-harmonic composition; Ask the phasor of signal according to the method described above, operation result still can contain the alternating current component of certain amplitude; Again the effective value and the phase place of phasor are made an integral filtering, just can obtain ideal results.Select the digital filter of suitable type and length according to the harmonic wave situation of system's reality, total time delay can be controlled at 10ms, and promptly in half power frequency period, precision is also fine.Applicating example to algorithm is as follows.

Contain positive sequence and negative phase-sequence first-harmonic, positive sequence 5 subharmonic in the three-phase voltage signal, effective value is respectively 10,1,1. $e_a=10\&CenterDot;\sqrt{2}\sin \mathrm{\&omega;t}+\sqrt{2}\sin (\mathrm{\&omega;t}+\mathrm{\&theta;})+\sqrt{2}\mathrm{<figure-callout\; id="5"\; label="sin"\; filenames="A02103873.200181.png"\; state="\{\{state\}\}">sin</figure-callout>}5\mathrm{\&omega;t}$ $e_b=10\&CenterDot;\sqrt{2}\sin (\mathrm{\&omega;t}+2\mathrm{\&pi;}/3)+\sqrt{2}\sin (\mathrm{\&omega;t}+\mathrm{\&theta;}-2\mathrm{\&pi;}/3)+\sqrt{2}\sin (5\mathrm{\&omega;t}+2\mathrm{\&pi;}/3)$ $e_c=10\&CenterDot;\sqrt{2}\sin (\mathrm{\&omega;t}-2\mathrm{\&pi;}/3)+\sqrt{2}\sin (\mathrm{\&omega;t}+\mathrm{\&theta;}+2\mathrm{\&pi;}/3)+\sqrt{2}\sin (5\mathrm{\&omega;t}-2\mathrm{\&pi;}/3)$

In the moment of t=20ms, the positive sequence component effective value sports 5.Suppose system frequency be 50 hertz constant, adopt " two-point method " to ask the process of symmetrical component as follows.

1, with the FIR low pass filter input voltage signal is carried out digital filtering, obtain fundametal compoment e _Al, e _Bl, e _Cl

2, by the instantaneous value of current sampling instant and last sampling instant, calculate e by (6), (7) formula of top _Al, e _Bl, e _ClEffective value separately and phase angle;

3, with e _AlPhase angle for referencial use, calculate e _Bl, e _ClRelative e _AlPhase place;

4, to e _Al, e _Bl, e _ClEffective value and relative phase make integral filtering, obtain three-phase fundamental voltage phasor

With

5, will

With Substitution (8) formula just can be calculated the positive and negative zero-sequence component of three-phase fundamental voltage.

We do positive sequence load and two parts of negative phase-sequence load to load also branch, correspond respectively to positive sequence compensator and negative sequence compensation device, with three equal value susceptance of function negatb () calculating negative sequence compensation device, its method is as follows, with reference to Fig. 1 and Fig. 9, can get for the negative sequence compensation device: $-{\stackrel{.}{I}}_{a2}=E\&CenterDot;{\mathrm{jB}}_{N,\mathrm{ab}}^{\left(c\right)}-\mathrm{aE}\&CenterDot;{\mathrm{jB}}_{N,\mathrm{ca}}^{\left(c\right)}---\left(9\right)$ $-a{\stackrel{.}{I}}_{a2}=a^{2}E\&CenterDot;j{B}_{N,\mathrm{bc}}^{\left(c\right)}-E\&CenterDot;{\mathrm{jB}}_{N,\mathrm{ab}}^{\left(c\right)}---\left(10\right)$

Be not difficult to solve by formula (9) and (10) $B_{N,\mathrm{ab}}^{\left(c\right)}E=1/\sqrt{3}\mathrm{Re}{\stackrel{.}{I}}_{a2}-\mathrm{Im}{\stackrel{.}{I}}_{a2}---\left(11\right)$ $B_{N,\mathrm{bc}}^{\left(c\right)}E=1/\sqrt{3}\mathrm{Re}{\stackrel{.}{I}}_{a2}+\mathrm{Im}{\stackrel{.}{I}}_{a2}---\left(12\right)$ $B_{N,\mathrm{ca}}^{\left(c\right)}E=-2/\sqrt{3}\mathrm{Re}{\stackrel{.}{I}}_{a2}---\left(13\right)$ Wherein Be respectively the real part and the imaginary part of load current negative sequence component.And have $B_{N,\mathrm{ab}}^{\left(c\right)}+B_{N,\mathrm{bc}}^{\left(c\right)}+B_{N,\mathrm{ca}}^{\left(c\right)}=0---\left(14\right)$

The negative sequence compensation device has been arranged, just can offset because the load unbalanced negative-sequence current that in system, produces.

The positive sequence compensator is in order to provide load required reactive current, to improve the power factor of system, perhaps to keep voltage.When our controlled target was the raising power factor, the principle of calculating the equivalent susceptance of positive sequence compensator was as follows.

If the power-factor angle of load is , power factor λ=cos , the real component of load phase current is I _p, idle component is I _q, according to the definition of power-factor angle as can be known:

Every phase reactive current I that the positive sequence compensator provides ^(c)Expression is because compensation arrangement and load are connected in parallel on the tie point with system, so every total mutually reactive current is I _q+ I ^(c)We wish that after overcompensation the two total power factor is λ _Ref, should have so: $(I_q+I^{\left(c\right)})/I_p=\sqrt{1/{{\mathrm{\&lambda;}}_{\mathrm{ref}}}^2-1}---\left(16\right)$

And then as can be known $I^{\left(c\right)}=I_p\&CenterDot;\sqrt{1/{{\mathrm{\&lambda;}}_{\mathrm{ref}}}^2-1}-I_q---\left(17\right)$

Therefore, the equivalent susceptance that should export of positive sequence compensator is $B_p^{\left(c\right)}=I^{\left(c\right)}/E=(I_p\&CenterDot;\sqrt{1/{{\mathrm{\&lambda;}}_{\mathrm{ref}}}^2-1}-I_q)/E---\left(18\right)$

Wherein E is the line voltage at compensation arrangement and system tie point place.

The equivalent susceptance of positive sequence compensator calculates with function positb () to be realized.

In Fig. 1,8,9, be ab line voltage with reference to phasor, therefore, the phase current on the positive sequence load ab branch road

Real part and imaginary part corresponding real component I respectively _pWith idle component I _qCan obtain by Fig. 8 ${\stackrel{.}{I}}_{P,\mathrm{ab}}={\stackrel{.}{I}}_{a1}\&CenterDot;e^{\mathrm{j\&pi;}/6}\&CenterDot;1/\sqrt{3}$ $=(1/2\mathrm{Re}{\stackrel{.}{I}}_{a1}-\sqrt{3}/6\mathrm{Im}{\stackrel{.}{I}}_{a1})+j(\sqrt{3}/6\mathrm{Re}{\stackrel{.}{I}}_{a1}+1/2\mathrm{Im}{\stackrel{.}{I}}_{a1})---\left(19\right)$ Wherein

Be respectively the real part and the imaginary part of load line electric current positive sequence component.So have $I_p=1/2\mathrm{Re}{\stackrel{.}{I}}_{a1}-\sqrt{3}/6\mathrm{Im}{\stackrel{.}{I}}_{a1}---\left(20\right)$ $I_q=\sqrt{3}/6\mathrm{Re}{\stackrel{.}{I}}_{a1}+1/2\mathrm{Im}{\stackrel{.}{I}}_{a1}---\left(21\right)$ Substitution (18) formula just can obtain the equivalent susceptance of positive sequence compensator.In typical case, λ _RefBe set at 1, substitution (17) formula is so the offset current of positive sequence compensator is $I^{\left(c\right)}=-I_q=-\mathrm{Im}{\stackrel{.}{I}}_{P,\mathrm{ab}}=-(\sqrt{3}/6\mathrm{Re}{\stackrel{.}{I}}_{a1}+1/2\mathrm{Im}{\stackrel{.}{I}}_{a1})---\left(22\right)$ Therefore, the susceptance of positive sequence compensator is among Fig. 1 $B_{P,\mathrm{ab}}^{\left(c\right)}E=-\sqrt{3}/6\mathrm{Re}{\stackrel{.}{I}}_{a1}-1/2\mathrm{Im}{\stackrel{.}{I}}_{a1}---\left(23\right)$ The three-phase susceptance (positive sequence+negative phase-sequence) of compensator is respectively $B_{\mathrm{ab}}^{\left(c\right)}E=-\sqrt{3}/6\mathrm{Re}{\stackrel{.}{I}}_{a1}-1/2\mathrm{Im}{\stackrel{.}{I}}_{a1}+1/\sqrt{3}\mathrm{Re}{\stackrel{.}{I}}_{a2}-\mathrm{Im}{\stackrel{.}{I}}_{a2}---\left(24\right)$ $B_{\mathrm{bc}}^{\left(c\right)}E=-\sqrt{3}/6\mathrm{Re}{\stackrel{.}{I}}_{a1}-1/2\mathrm{Im}{\stackrel{.}{I}}_{a1}+1/\sqrt{3}\mathrm{Re}{\stackrel{.}{I}}_{a2}+\mathrm{Im}{\stackrel{.}{I}}_{a2}---\left(25\right)$ $B_{\mathrm{ca}}^{\left(c\right)}E=-\sqrt{3}/6\mathrm{Re}{\stackrel{.}{I}}_{a1}-1/2\mathrm{Im}{\stackrel{.}{I}}_{a1}-2/\sqrt{3}\mathrm{Re}{\stackrel{.}{I}}_{a2}---\left(26\right)$

Utilize these formula, can be compensated load unbalanced and provide the three-phase susceptance value of the required compensation arrangement of reactive current, i.e. susceptance reference value for load from the load current phasor.Then, DSP is converted to the susceptance reference value pilot angle signal and the instruction of TSC switching of TCR again, sends to TCR pulse generation plate and TSC zero cross fired plate respectively.

When the positive sequence compensator is used for burning voltage, adopt conventional pi regulator to make closed-loop adjustment, try to achieve the equivalent susceptance of positive sequence compensator.

From said process as can be seen, try to achieve voltage phasor and load current phasor respectively by instantaneous voltage, load current instantaneous value that sampling obtains, and then calculate the positive-negative sequence component of load current, be the key link that realizes this compensation principle, the response speed and the precision of controller had material impact.

Following principle according to thyristor-controlled reactor (TCR) illustrates switching instruction how to use function tcrtsccomu () to come each phase susceptance reference value is converted to TCR pilot angle and thyristor switchable capacitor (TSC).

Be the circuit theory 10a and the current waveform 10b of thyristor-controlled reactor (TCR) among Figure 10, Th1 and Th2 are two antiparallel thyristors, respectively conducting in the positive and negative half cycle of mains voltage waveform.In the moment that thyristor is triggered, the phase place of voltage waveform is called pilot angle, represents with α.When α is 90 °, the perceptual idle maximum (being called rated power) that reactor absorbs, the perceptual idle minimum (being called no-load power) that absorbs in the time of 180 °.Because reactor almost is pure inductive load, so electric current lags behind about 90 ° of voltage, is pure reactive current.α can produce the asymmetric electric current that contains DC component, so pilot angle is generally regulated between 0 °～90 ° the time in 90 °～180 ° scopes.

For first-harmonic, the reactor of thyristor control can be regarded a controlled susceptance as, and susceptance value that it is equivalent and the relation of pilot angle α are as follows: $B_R\left(\mathrm{\&alpha;}\right)=-\frac{2(\mathrm{\&pi;}-\mathrm{\&alpha;})+\mathrm{<figure-callout\; id="2"\; label="sin"\; filenames="A02103873.200171.png,A02103873.200181.png"\; state="\{\{state\}\}">sin</figure-callout>}2\mathrm{\&alpha;}}{\mathrm{\&pi;}{X}_R}---\left(27\right)$

X wherein _RBe the fundamental reactance of reactor, and the admittance value of agreement reactor is for negative, the admittance value of capacitor is for just.The susceptance reference value is converted to the method for TCR pilot angle signal and the instruction of TSC switching:

1, whether judges the susceptance reference value greater than zero, if then need to drop into TSC, with TSC switching instruction set, TCR susceptance reference value=susceptance reference value-TSC susceptance; If not, then need not drop into TSC, with TSC switching instruction reset, TCR susceptance reference value=susceptance reference value;

2, look for TCR susceptance reference value～pilot angle correspondence table, obtain TCR susceptance reference value control corresponding angle;

3, the output voltage of calculation control angle correspondence is exported to TCR pulse generation plate with the form of voltage signal with the pilot angle size by dsp board.

Annotate: the equivalent susceptance of (1) compensation arrangement three-phase output is different, so three-phase TCR pilot angle voltage and the instruction of TSC switching separately should be calculated respectively according to the method described above.(2) the susceptance value is with the specified output of TCR, and the equivalent susceptance when promptly pilot angle is 90 ° is a base value.

Set up the method for TCR susceptance reference value～pilot angle correspondence table:

1, the n five equilibrium is carried out in equivalent susceptance output area 0～-1 of compensation arrangement TCR, obtain n+1 point sequence a: B ₀, B ₁..., B _n

2, with each the some B in the sequence _k, k=0 ..., n, the formula of substitution top is found the solution corresponding pilot angle α with Newton iteration method _kValue; Newton iteration method: make f (α)=2 (π-α)+sin2 α+π X _RB _R(α), then f ' (α)=-2+2cos2 α, iterative formula is: α ⁽ⁱ⁺¹⁾=α ⁽ⁱ⁾-f (α ⁽ⁱ⁾)/f ' (α ⁽ⁱ⁾).Step is as follows:

(1) gets initial value α ⁽⁰⁾=π/4, i=0;

(2) by α ⁽ⁱ⁺¹⁾=α ⁽ⁱ⁾-f (α ⁽ⁱ⁾)/f ' (α ⁽ⁱ⁾) calculate α ⁽ⁱ⁺¹⁾

(3) | α ⁽ⁱ⁺¹⁾-α ⁽ⁱ⁾|＜ε?, if, α _k=α ⁽ⁱ⁺¹⁾Finish; If not, i=i+1 returns (2);

Here ε is α _kPermissible error, B _R(α)=B _k

3, with α ₀, α ₁..., α _nValue when the unit of converting to is " degree " deposits n+1 dimension group alpha[in] in.Alpha[k obviously] corresponding susceptance reference value B _kTherefore=-k/n can get following relation:

Susceptance reference value B _kCorresponding pilot angle α _kAt array alpha[] in subscript k=-B _k* n.

In the device running, after the DSP control board obtains susceptance reference value B, make k equal-B * n round off method rounds alpha[k] be exactly the pilot angle of B correspondence.

Susceptance reference value five equilibrium the choosing of n of counting:

Theoretically, n is big more, and the susceptance reference value is just got thin more, and the output of TCR is just accurate more and level and smooth.But in fact, get when meticulous, the number of degrees that the pilot angle of two adjacent susceptance reference value correspondences differs are very little, because phase shift trigger board phase shifting accuracy is limited, can't embody during the actual output of this too little difference, also just less than value.In our device, phase shift trigger board phase shifting accuracy is approximately 1 °, and the n value is 100 more suitable.

The TCR pilot angle is changed into the method for relevant voltage signal:

Generally speaking, the voltage signal of TCR pulse generation plate input and pilot angle are corresponding one by one.The trigger board of the Xinda of for example selecting for use at present, Shenyang requires 90 °～180 ° pilot angle, represents with the voltage of 7.5～0V, and the two is linear relationship basically.Therefore, the pilot angle corresponding voltage value, calculate by the formula of bottom:

Wherein ang is the TCR pilot angle, V _MaxBe the voltage of 90 ° of pilot angle correspondences, V _MinBe the voltage of 180 ° of pilot angle correspondences.

Below the embodiment of method proposed by the invention will be described according to an instantiation:

The circuit of calculated examples is seen Fig. 9.Suppose that load is an arc furnace, under certain state, the three-phase admittance is respectively: $Y_{\mathrm{ab}}=-\mathrm{<figure-callout\; id="1"\; label="j"\; filenames="A02103873.200171.png,A02103873.200181.png"\; state="\{\{state\}\}">j</figure-callout>}\frac{1}{2},Y_{\mathrm{bc}}=\frac{1}{2}-\mathrm{<figure-callout\; id="1"\; label="j"\; filenames="A02103873.200171.png,A02103873.200181.png"\; state="\{\{state\}\}">j</figure-callout>}\frac{1}{2},Y_{\mathrm{ca}}=\frac{\sqrt{3}}{2}-\mathrm{<figure-callout\; id="1"\; label="j"\; filenames="A02103873.200171.png,A02103873.200181.png"\; state="\{\{state\}\}">j</figure-callout>}\frac{1}{2}.$

System line voltage is: ${\stackrel{.}{E}}_{\mathrm{ab}}=1,{\stackrel{.}{E}}_{\mathrm{bc}}=-\frac{1}{2}-\mathrm{<figure-callout\; id="3"\; label="j"\; filenames="A02103873.200171.png"\; state="\{\{state\}\}">j</figure-callout>}\frac{\sqrt{3}}{2},{\stackrel{.}{E}}_{\mathrm{ca}}=-\frac{1}{2}+\mathrm{<figure-callout\; id="3"\; label="j"\; filenames="A02103873.200171.png"\; state="\{\{state\}\}">j</figure-callout>}\frac{\sqrt{3}}{2}.$

Compensator parameter:

The specified admittance B of TCR _R=-1/X _R=-1,

The specified admittance B of TSC _C=0.8.

1, the DSP control board acquisition system line voltage of compensation arrangement and the line current of load, the method (" two-point method ") that adopts front described calculating three-phase electricity signal dfundamental-harmonic pair to weigh, the positive-negative sequence component of negate charged current, step is as follows:

(1) signal that at first sampling obtains to AD is done low-pass filtering, keeps the fundametal compoment in voltage, the electric current;

(2) calculate the effective value and the phase place of each voltage, current signal respectively, and the result is made integral filtering.With ab line voltage phasor for referencial use, obtain the phasor of three line currents: ${\stackrel{.}{E}}_{\mathrm{ab}}=1,{\stackrel{.}{I}}_a=-\mathrm{<figure-callout\; id="3"\; label="j"\; filenames="A02103873.200171.png"\; state="\{\{state\}\}">j</figure-callout>}\frac{3}{2},{\stackrel{.}{I}}_b=-\frac{\sqrt{3}+1}{4}-j\frac{\sqrt{3}-3}{4},{\stackrel{.}{I}}_c=\frac{\sqrt{3}+1}{4}+\mathrm{<figure-callout\; id="3"\; label="j"\; filenames="A02103873.200171.png"\; state="\{\{state\}\}">j</figure-callout>}\frac{\sqrt{3}+3}{4};$

(3) according to the definition of symmetrical component method, i.e. (8) formula calculates the positive-negative sequence component of load current: ${\stackrel{.}{I}}_{a1}=\frac{1}{4}-j(1+\frac{\sqrt{3}}{12})$ ${\stackrel{.}{I}}_{a2}=-\frac{1}{4}-j(\frac{1}{2}-\frac{\sqrt{3}}{12})$

2, calculate the three-phase susceptance of compensation arrangement negative sequence compensation device part by (11), (12), (13) formula: $B_{N,\mathrm{ab}}^{\left(c\right)}=\frac{1}{2}-\frac{\sqrt{3}}{6},B_{N,\mathrm{bc}}^{\left(c\right)}=-\frac{1}{2},B_{N,\mathrm{ca}}^{\left(c\right)}=\frac{\sqrt{3}}{6}.$

3, ask the equivalent susceptance of positive sequence compensator:

Compensation arrangement can regulation voltage by the size of regulating the output reactive current.When controlled target is made as voltage, by pi regulator according to the user to the set point of voltage and the error of virtual voltage, calculate the three-phase susceptance of compensation arrangement positive sequence compensator.In this example, suppose that the user is 1 to the set point of voltage, then because system line voltage also is 1 at this moment, the positive sequence susceptance of compensator equals 0.

If controlled target is a power factor, and λ _RefBe set at 1, then the equivalent susceptance of positive sequence compensator is calculated by (23) formula: $B_{P,\mathrm{ab}}^{\left(c\right)}=(-\sqrt{3}/6\mathrm{Re}{\stackrel{.}{I}}_{a1}-1/2\mathrm{Im}{\stackrel{.}{I}}_{a1})/E=\frac{1}{2}$

4, the actual three-phase susceptance value that should export of compensation arrangement that obtains by control algolithm, promptly the susceptance reference value is positive sequence and negative phase-sequence susceptance sum: when controlled target is power factor: $B_{\mathrm{ab}}^{\left(c\right)}=1-\frac{\sqrt{3}}{6},B_{\mathrm{bc}}^{\left(c\right)}=0,B_{\mathrm{ca}}^{\left(c\right)}=\frac{1}{2}+\frac{\sqrt{3}}{6}.$ When controlled target is voltage: $B_{\mathrm{ab}}^{\left(c\right)}=\frac{1}{2}-\frac{\sqrt{3}}{6},B_{\mathrm{bc}}^{\left(c\right)}=-\frac{1}{2},B_{\mathrm{ca}}^{\left(c\right)}=\frac{\sqrt{3}}{6};$

5, the pilot angle voltage that the susceptance reference value of each phase is changed into TCR instructs with the TSC switching: when controlled target is power factor: ab mutually: susceptance reference value=0.71＞0, need to drop into TSC, the instruction of TSC switching puts 1;

TCR susceptance reference value=susceptance reference value-TSC susceptance=0.71-0.8=-0.09;

The k=rounding-off method rounds (TCR susceptance reference value * 100)=9;

TCR pilot angle ang=alpha[k]=alpha[9]=146.38 °;

TCR pilot angle voltage

(V _max＝7.5V，V _min＝0V)。The bc phase: susceptance reference value=0, do not need to drop into TSC, the instruction of TSC switching puts 0;

Obviously, TCR pilot angle ang=180 °;

TCR pilot angle voltage=0V.The ca phase: susceptance reference value=0.79＞0, need to drop into TSC, the instruction of TSC switching puts 1;

TCR susceptance reference value=susceptance reference value-TSC susceptance=0.79-0.8=-0.01;

Ang=163.48 ° of TCR pilot angle;

TCR pilot angle voltage=1.38V.When controlled target was voltage, the output computational methods of each phase of dsp board were identical with the top, repeat no more.

More than each the step all be under the organization of unity of the function Adintserv () of Fig. 2 flow chart, to finish.

Below ask for an interview Figure 11～Figure 14, will describe with regard to compensation arrangement and actual compensation effect thereof.The i in Figure 11 wherein _sBe the line current of load, u _sBe system line voltage, u _tBe synchronizing signal, also take from system line voltage, u _zBe TSC main circuit thyristor terminal voltage signal.△ represents that connection is a three-phase three-wire system.The LEM module is to utilize hall principle to measure the device of the signal of telecommunication, and used herein is voltage LEM module, can be converted to current signal to voltage signal.

The main circuit of compensation arrangement is made up of two parts: thyristor-controlled reactor (TCR) and thyristor switchable capacitor (TSC).TCR is composed in series by a pair of antiparallel thyristor and reactor, and the time of control thyristor conducting can be regulated the equivalent reactance in the connecting system.TSC is made up of a pair of antiparallel thyristor and capacitors in series, and the turn-on and turn-off of control thyristor can drop into or excise capacitor fast.

The compensation arrangement controller mainly is made of three parts: DSP control board, TCR pulse generation plate and TSC zero cross fired plate.Wherein the controlled target set according to the user of DSP control board and system running state are determined TCR pilot angle signal that compensation arrangement should be exported and the switching instruction of TSC; TCR pulse generation buttress sends the high-frequency impulse of process phase shift according to the input of pilot angle signal and synchronizing voltage, the conducting angle of thyristor in the control TCR main circuit, the equivalent reactance of change connecting system; TSC zero cross fired plate then produces high-frequency impulse according to the switching instruction of control board output, triggers the thyristor in the TSC main circuit, reaches the purpose of switched capacitor.

The DSP control board selects for use Beijing to close the C32SS type application plate that the crowd reaches company.Its feature is that employing floating type digital signal processor TMS320C32 makes central processing unit (CPU), holds but topmost processor active task.High-speed, the high-precision advantage of DSP is to realize the assurance of algorithm of the present invention.Except CPU, also have 8 tunnel 12 A/D converters on the DSP control board, the input of 8 way switch amounts, the output of 8 way switch amounts, 256kSRAM, keyboard and display interface, RS232 and RS485 serial communication interface etc.Also have the house dog and the electric source monitoring circuit of being equipped with on the plate, strengthened the fault tolerance of controller.Wherein the operating frequency of dsp chip TMS320C32 is 40MHz, and the individual instructions time of implementation is 25ns.Figure 12 is the hardware principle block diagram of control board.

TCR pulse generation plate adopts the single-phase trigger board of the 3 Shenyang CF2B-2A of Xinda company type, done following change: 1, power supply is held concurrently the transformer of synchronous usefulness by input 220V or 380V output ± 20V, change input 66V output ± 20V into, be connected on that 3000V is than the step-down side of the instrument transformer of 100V in the device, this instrument transformer is used for the line voltage of measuring system.2, only use the function of adjusted open loop, removed open/close and regulated diverter switch, circuit is connected into the adjusted open loop state.

TSC zero cross fired plate has been applied for patent of invention, proprietary term: the phase-splitting cross-zero circuits for triggering of thyristor switchable capacitor (TSC) usefulness for design voluntarily.Number of patent application: 01136260.X, its schematic block circuit diagram is seen Figure 14.

TCR pulse generation plate and TSC zero cross fired plate output electric pulse are given the light sender unit, become light signal; Light signal is delivered to light collection of letters device by optical fiber again.Light collection of letters device is converted to the signal of telecommunication to light signal, gives the output pulses trigger board.The output pulses trigger board changes the low power electric pulse of input into the large power, electrically pulse again, triggers thyristor.Light collection of letters device and sender unit are selected the product of Agilent company for use, and model is respectively: HFBR2521 and HFBR1521.Optical fiber adopts the Ying Saier Eus-100 of company type.The output pulses trigger board selects for use Beijing gold from day a kind of universal thyristor trigger board of positive Based Intelligent Control Co., Ltd.

Figure 13 is the oscillogram of system line electric current before and after (only bc has resistive load mutually) compensation arrangement drops under the uncompensated load.Table 1 is the effective value of system line voltage before and after compensation arrangement drops into.

This method has been used for 2 kilovolts, 240 kilovars compensation arrangements of a cover.Test shows that it can compensate the imbalance of load and required reactive current fast and accurately, has to respond fast, advantage of high precision.

Claims (5)

1, a kind of method of compensating dynamic three-phase imbalance load contains useful compensation arrangement and reads it and the line voltage of system junction, the line current of load; Obtain the positive and negative preface component of load current with calculating method that three-phase electricity signal dfundamental-harmonic pair weighs; According to the set point of controlled target, the imbalance of compensation dynamic load is eliminated harmful negative-sequence current that uncompensated load causes, simultaneously the step that the needed reactive power of loading is compensated in system again.It is characterized in that it contains successively and has the following steps:

(1) reads three line currents of three the line voltage and the load of it and system junction with compensation arrangement, read the set point of user controlled target;

(2) result that sampling is read deposits in the data field and the corresponding position of current sampling point sequence number;

(3) carry out the data processing of uneven control with function d ataprocu (), it contains successively and has the following steps:

1) with the FIR low pass filter to adopt into system line voltage and load line current signal carry out filtering;

2) to any one road signal, by its two adjacent sampled value e ₁, e ₂, calculate its phase place α and effective value E according to following formula in first sampling instant: $\mathrm{tg\&alpha;}=e_1\sin {\mathrm{\&omega;T}}_s/(e_2-e_1\cos {\mathrm{\&omega;T}}_s),$ $E=\sqrt{{e_1}^2+{e_2}^2-2e_1{e}_2\cos {\mathrm{\&omega;T}}_s}/\sqrt{2}\sin {\mathrm{\&omega;T}}_s,$

Wherein, T _sBe the time interval of sampling, i.e. in the sampling period, ω is the angular frequency of signal, in electric power system under the normal condition, and ω=100 π;

3) effective value and the phase place of above-mentioned each signal of obtaining are made integral filtering;

4) be reference quantity with ab line voltage,, obtain their phasor form according to the effective value and the phase place of voltage, electric current: $\stackrel{.}{E}=E\&angle;\mathrm{\&alpha;}=\sqrt{2}E(\cos \mathrm{\&alpha;}+j\sin \mathrm{\&alpha;});$

5) by the definition of symmetrical component method, the symmetrical component of calculation system line voltage and load line electric current: $\left[\begin{array}{c}{\stackrel{.}{E}}_1\\ {\stackrel{.}{E}}_2\\ {\stackrel{.}{E}}_0\end{array}\right]=\frac{1}{3}\left[\begin{array}{ccc}1& a& a^2\\ 1& a^2& a\\ 1& 1& 1\end{array}\right]\left[\begin{array}{c}{\stackrel{.}{E}}_{\mathrm{ab}}\\ {\stackrel{.}{E}}_{\mathrm{bc}}\\ {\stackrel{.}{E}}_{\mathrm{ca}}\end{array}\right],$ $\left[\begin{array}{c}{\stackrel{.}{I}}_{a1}\\ {\stackrel{.}{I}}_{a2}\\ {\stackrel{.}{I}}_{a0}\end{array}\right]=\frac{1}{3}\left[\begin{array}{ccc}1& a& a^2\\ 1& a^2& a\\ 1& 1& 1\end{array}\right]\left[\begin{array}{c}{\stackrel{.}{I}}_a\\ {\stackrel{.}{I}}_b\\ {\stackrel{.}{I}}_c\end{array}\right],$

A=ej wherein ^{2/3 π},

Be three line voltages of system,

Be three line currents of load,

With Represent positive sequence, negative phase-sequence and zero-sequence component respectively;

6) try to achieve phase current by the positive sequence component of load line electric current

${\stackrel{.}{I}}_l={\stackrel{.}{I}}_{a1}{e}^{\mathrm{j\&pi;}/6}/\sqrt{3},$ And real component $I_p=\mathrm{Re}{\stackrel{.}{I}}_l,$ Idle component $I_q=\mathrm{Im}{\stackrel{.}{I}}_l.$

(4) usefulness function negatb () calculates three equal value susceptance of negative sequence compensation device, the three-phase susceptance of negative sequence compensation device part

By following various obtaining: $B_{N,\mathrm{ab}}^{\left(c\right)}E=1/\sqrt{3}\mathrm{Re}{\stackrel{.}{I}}_{a2}-\mathrm{Im}{\stackrel{.}{I}}_{a2},$ $B_{N,\mathrm{bc}}^{\left(c\right)}E=1/\sqrt{3}\mathrm{Re}{\stackrel{.}{I}}_{a2}+\mathrm{Im}{\stackrel{.}{I}}_{a2},$ $B_{N,\mathrm{ca}}^{\left(c\right)}E=-2/\sqrt{3}\mathrm{Re}{\stackrel{.}{I}}_{a2};$

(5) calculate positive sequence compensator three equal value susceptance with function positb (), it is relevant with controlled target:

If: controlled target is a voltage

Then: by pi regulator according to the user to the set point of voltage and the error of voltage actual value, calculate three equal value susceptance of compensation arrangement positive sequence compensator $B_p^{\left(c\right)}=K_{p}e+K_i\mathrm{\&Sigma;e},$ $e=E-E_{\mathrm{ref}},$

E _RefBe the set point of line voltage, E is the actual value of line voltage, K _pBe proportionality coefficient, K _iBe integral coefficient;

If: controlled target is a power factor

Then: by the real component I of negative-sequence current _p, idle component I _q, system line voltage E substitution following formula is compensated three equal value susceptance of device positive sequence compensator $B_p^{\left(c\right)}=(I_p\&CenterDot;\sqrt{1/{{\mathrm{\&lambda;}}_{\mathrm{ref}}}^2-1}-I_q)/E,$

λ wherein _RefThe load of setting for the user total power factor after overcompensation;

(6) the actual every phase susceptance value that should export of compensation arrangement, promptly the susceptance reference value is equivalent susceptance of positive sequence compensator and the equivalent susceptance sum of negative sequence compensation device;

(7) with function tcrtsccomu () each phase susceptance reference value is converted to TCR pilot angle and the instruction of TSC switching, it contains following steps successively:

1) do you differentiate susceptance reference value＞0?

If: be that then the instruction of TSC switching puts 1, TCR susceptance reference value=susceptance reference value-TSC susceptance;

If: not, then the instruction of TSC switching puts 0, TCR susceptance reference value=susceptance reference value;

2) the k=rounding-off method rounds (TCR susceptance reference value * 100);

3) TCR pilot angle ang=alpha[k], alpha[] be the array of preserving the pilot angle of susceptance reference value correspondence;

4) TCR pilot angle voltage V _AngFor:

V wherein _MaxBe the voltage of 90 ° of pilot angle correspondences, V _MinBe the voltage of 180 ° of pilot angle correspondences;

5) output TCR pilot angle voltage and TSC switching instruction;

(8) finish, return.

According to the method for the compensating dynamic three-phase imbalance load of claim 1, it is characterized in that 2, the method for setting up TCR susceptance reference value～pilot angle correspondence table in the described step (7) contains successively and has the following steps:

(1) the n five equilibrium is carried out in equivalent susceptance output area 0～-1 of compensation arrangement TCR, obtain n+1 point sequence a: B ₀, B ₁..., B _n

(2) with each the some R in the sequence _k, k=0 ..., n, the formula of substitution bottom is found the solution corresponding pilot angle α with Newton iteration method _kValue: $B_R\left(\mathrm{\&alpha;}\right)=-\frac{2(\mathrm{\&pi;}-\mathrm{\&alpha;})+\sin 2\mathrm{\&alpha;}}{\mathrm{\&pi;}{X}_R},$

Wherein, B _R(α) for for first-harmonic, the equivalent susceptance value of the reactor of thyristor control, X _RBe the fundamental reactance of reactor, and the admittance value of agreement reactor is for negative, the admittance value of capacitor is for just;

(3) with α ₀, α ₁..., α _nValue when the unit of converting to is " degree " deposits n+1 dimension group alpha[in] in, because alpha[k] corresponding susceptance reference value B _k=-k/n, so susceptance reference value B _kCorresponding pilot angle α _kAt array alpha[] in subscript k=-B _k* n.

3, according to the method for the compensating dynamic three-phase imbalance load of claim 1 or 2, it is characterized in that: when the precision of phase shift trigger board phase shift was 1 °, the n value was 100.

4, the compensation arrangement that proposes according to the method for compensating dynamic three-phase imbalance load is characterized in that it contains: Chuan Jie controller, light sender unit-light collection of letters device-output pulses circuits for triggering and be serially connected with main circuit between each line of system's three-phase successively; TCR pulse generation plate and TSC zero cross fired plate that its middle controller receives DSP control board output by the DSP control board, respectively constitute; Main circuit contains thyristor-controlled reactor (TCR) that is composed in series by a pair of antiparallel thyristor and reactor and the thyristor switchable capacitor of being made up of a pair of antiparallel thyristor and capacitors in series (TSC).

5, compensation arrangement according to the compensating dynamic three-phase imbalance load of claim 4, it is characterized in that: described TSC zero cross fired plate is the phase-splitting cross-zero trigger controller that thyristor switchable capacitor is used, it is by the Hall element formula voltage detecting circuit that links to each other with antiparallel thyristor two ends, input links to each other with this voltage detecting circuit output and can be converted into signaling conversion circuit with the synchronous square wave voltage signal of voltage at thyristor two ends to the little current signal of input, the zero passage detection signal generating circuit that links to each other with this signaling conversion circuit output, the OR circuit that input links to each other with the input or the excision signal output part of the output of this zero passage detection signal generating circuit and controller respectively links to each other with this OR circuit output and the delay circuit and the input of the EDM Generator of Adjustable Duty Ratio of the square-wave voltage of its output link to each other with this delay circuit output and the thyristor trigger impulse formation circuit of the Frequency Adjustable that each control end of output and anti-parallel thyristor links to each other.

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