CN102386775A - Controllable series compensation device based on parallel connection of double TCR (Thyristor Controlled Reactor) branch circuits and control method thereof - Google Patents

Abstract

The invention provides a controllable series compensation device based on parallel connection of double TCR (Thyristor Controlled Reactor) branch circuits and a control method thereof, which belong to the field of controllable series compensation in the field of flexible alternating current power transmission. The controllable series compensation device uses parallel connection of two TCR (Thyristor Controlled Reactor) branch circuits and makes current passing through each TCR (Thyristor Controlled Reactor) branch circuit be smaller, so that the problem that the current thyristor valve has insufficient through-current capability in ultrahigh voltage controllable series compensation is solved. The TCR (Thyristor Controlled Reactor) branch circuit is formed in a manner that two inverse parallel thyristor valves are connected in series with a reactor, and the two TCR (Thyristor Controlled Reactor) branch circuits are connected in series to form a controllable series compensation device; or the two TCR (Thyristor Controlled Reactor) branch circuits are connected in parallel and then are connected in series with a common reactor to form a controllable series compensation device; and the current equalizing and impedance requirements of branch circuits are realized by control of equal circuit amplitudes of the two TCR (Thyristor Controlled Reactor) branch circuits of the series compensation device and control of fundamental wave impedance. The device can meet the requirements of the impedance control, and has simple control process and uses linear control; and the device is easy to realize in engineering, along with good control stability.

Description

A kind of controlled series compensation device and control method thereof based on the parallel connection of double T CR branch road

Technical field

(Thyristor Controlled Series Capacitor, TCSC) field is specifically related to the invention belongs to controlled series compensation in the flexible ac transmission field.

Background technology

At present, China has begun to build 1000kV UHV transmission network, and the southeast-Nanyang, 1000kV Shanxi of having put into operation-Jingmen extra-high-voltage alternating current experimental project.Ultra-high voltage AC transmission has remarkable advantages at aspects such as transmission capacity, fed distance, power losss.But, because extra high voltage line itself had long distance, characteristics such as capacity greatly, and be subject to requirement such as power system transient stability property, make the ability to transmit electricity of part UHV transmission line be restricted, be difficult to give play to its due advantage.Development experience by supergrid; On UHV transmission line, install string additional and mend device; Can significantly promote the conveying capacity of UHV transmission line, improve the transient stability of place system, thereby solve the more existing problems of extra high voltage line to a certain extent.

Usually, Series Compensation is divided into two kinds, promptly fixed series compensation (Fixed Series Capacitor, FSC) and controlled series compensation.Fixed series compensation equipment is simple, and is safe and reliable, under situation reasonable in design, can satisfy the demand of general electric power system to the capacitive reactances compensation.At present, China has carried out the development work of ultra high voltage fixed series compensation Study on Technology and key equipment, and will put into operation the end of the year in 2011.But; The compensating impedance of fixed series compensation device is fixed, and the compensativity of circuit can not be adjusted neatly, and the fixed series compensation device possibly cause subsynchronous resonance (Sub-Synchronous Resonance; SSR), the safe operation to electric power system causes certain threat.The controlled series compensation device can be avoided the problems referred to above to a certain extent.The controlled series compensation techniques make use realizes the flexible to series compensation impedance and line build-out degree to the triggering of thyristor valve control, make system static state, transient state and dynamic property be improved significantly.The subsynchronous frequency impedance characteristic that controlled series compensation is intrinsic can improve the subsynchronous frequency damping characteristic of system, thereby reduces the risk that subsynchronous resonance takes place to a certain extent.Therefore, install the controlled series compensation device additional at extra high voltage line or 750kV transmission line, comparing fixed series compensation has significant technical advantage.

Present stage, only on the circuit of 500kV and following electric pressure, install the case history of controlled series compensation additional, for ultra high voltage and 750kV transmission line, still do not install the case history of controlled series compensation device additional.The rated current of existing controlled series compensation engineering is generally between 1000A～3000A, and the transmission capacity of UHV transmission line is big, and the rated current of controlled series compensation device should be between 5000A～6300A; The controlled series compensation rated current of 750kV transmission line is also more than 4000A.And the existing thyristor valve that has applied to engineering, its maximum current capacity only can reach about 4500A, can not satisfy UHV transmission line to install the requirement of controlled series compensation to thyristor valve additional; For the 750kV transmission line of alternation current, when rated current is higher, also can not meet the demands.If adopt thyristor valve, then depend on the technological progress of power electronic device with bigger through-current capability.

Summary of the invention

The object of the invention is to the problems referred to above; A kind of controlled series compensation device and control method thereof based on the parallel connection of double T CR branch road is provided; String is mended the parallel connection of device through two TCR branch roads; Make and flow through the maximum rated current of the electric current of every TCR branch road less than existing thyristor valve; Thereby solved existing thyristor valve not enough problem of through-current capability in the ultra high voltage controlled series compensation,, realized the current-sharing and the impedance requirement of two TCR branch roads through string being mended the equal control of device two TCR subcircuits amplitudes and the control of impedance of fundamental frequency.

For realizing the foregoing invention purpose, the technical scheme that the present invention takes is:

A kind of controlled series compensation device based on the parallel connection of double T CR branch road, said string are mended device and are comprised capacitor; Its improvements are that said string benefit device comprises the TCR branch road of two parallel connections, and the TCR branch road of two parallel connections is parallelly connected with said capacitor; Every TCR props up antiparallel two thyristor valves of route and reactor is composed in series, and when string was mended the device conducting, the TCR branch current amplitude of said two parallel connections equated that perhaps effective value equates, perhaps mean value equates.

Wherein: the TCR branch road of two parallel connections reactor L that connects ₃Parallelly connected with capacitor again.

A kind of string as claimed in claim 1 is mended the control method of device, and its improvements are that said method comprises the steps:

1) sets up impedance of fundamental frequency Z and trigger angle α ₁Between impedance operator table Table1, according to as follows:

$Z=\frac{1}{\mathrm{\&omega;c}}-\frac{2A}{\mathrm{\&pi;}{k}^2{\mathrm{\&omega;}}^3{c}^2}\left\{(\frac{1}{{\mathrm{<figure-callout\; id="1"\; label="L"\; filenames="HDA0000100075870000013.png"\; state="\{\{state\}\}">L</figure-callout>}}_1}+\frac{1}{L_2})\right[{\mathrm{\&beta;}}_1+\frac{1}{2}\sin 2{\mathrm{\&beta;}}_1-\frac{2F\cos {\mathrm{\&beta;}}_1\cos k{\mathrm{\&beta;}}_1}{k^2-1}(k\tan k{\mathrm{\&beta;}}_1-\tan {\mathrm{\&beta;}}_1)]$

$+(\frac{H_1}{{\mathrm{<figure-callout\; id="1"\; label="L"\; filenames="HDA0000100075870000013.png"\; state="\{\{state\}\}">L</figure-callout>}}_1}+\frac{H_2}{L_2})\sin {\mathrm{\&beta;}}_1\}$

Wherein:

${\mathrm{\&omega;}}_0=\frac{1}{\sqrt{\frac{L_1{L}_2}{{\mathrm{<figure-callout\; id="1"\; label="L"\; filenames="HDA0000100075870000013.png"\; state="\{\{state\}\}">L</figure-callout>}}_1+L_2}c}}$

ω＝2πf

$k=\frac{{\mathrm{\&omega;}}_0}{\mathrm{\&omega;}}=\frac{1}{2\mathrm{\&pi;<figure-callout\; id="1"\; label="f\; L"\; filenames="HDA0000100075870000013.png"\; state="\{\{state\}\}">f</figure-callout>}}\sqrt{\frac{L_{}}{}}\sqrt{\frac{{}_1+L_2}{L_1{L}_{2}c}}$

$A=\frac{k^2}{k^2-1}$

$F=1-\frac{2\cos {\mathrm{\&beta;}}_1-2\cos k{\mathrm{\&beta;}}_1}{2-2\cos k{\mathrm{\&beta;}}_1-k^2{\mathrm{\&omega;}}^2{L}_{1}c}$

${\mathrm{<figure-callout\; id="1"\; label="H"\; filenames="HDA0000100075870000013.png"\; state="\{\{state\}\}">H</figure-callout>}}_1=({\mathrm{<figure-callout\; id="1"\; label="L"\; filenames="HDA0000100075870000013.png"\; state="\{\{state\}\}">L</figure-callout>}}_1/L_2-1)\frac{\cos {\mathrm{\&beta;}}_1-\cos k{\mathrm{\&beta;}}_1}{2-2\cos k{\mathrm{\&beta;}}_1-k^2{\mathrm{\&omega;}}^2{L}_{1}c}$

$H_2=(L_2/L_1-1)\frac{\cos {\mathrm{\&beta;}}_1-\cos k{\mathrm{\&beta;}}_1}{2-2\cos k{\mathrm{\&beta;}}_1-k^2{\mathrm{\&omega;}}^2{L}_{1}c}$

β ₁＝π-α ₁

F: be system frequency;

L ₁, L ₂: be the reactance value of reactor;

C: be condenser capacitance;

2) the impedance order obtains

A: ask the order impedance Z _RefWith the measurement impedance Z _MeasureDifference;

B: the impedance difference obtains order impedance correction through the FEEDBACK CONTROL link, order impedance correction and order impedance Z _RefAddition is as the impedance bid value;

3) assign the impedance order, draw relative trigger angle α through Table1 ₁, as the thyristor trigger angle initial value of following two branch roads of this order impedance;

4) two thyristor trigger angle equate, L is worked as in thyristor conducting simultaneously ₁=L ₂The time, execution in step 7); Work as L ₁≠ L ₂The time, two TCR branch current amplitude i _MaxUnequal, execution in step 5);

5) establish L ₁＜L ₂, i _1max＞i _2max, the trigger angle α of maintenance TCR branch road 1 ₁Constant;

6) obtain the trigger angle α of TCR branch road 2 ₂, make i _1max=i _2max

The measurement of TCR branch current amplitude:

A: adopt detection capacitance voltage zero crossing to produce the sampled signal pulse;

B: the TCR branch current is sampled;

C: get the current amplitude i of the absolute value of sample rate current value as the TCR branch road _1maxAnd i _2max

The control of two TCR branch road current-sharings:

A: set up TCR branch road 2 current amplitude i _2maxWith trigger angle α ₂Relation table Table2, according to as follows:

$i_{2\max }^{*}=\frac{i_{2\max }}{i_m}=\frac{k^2}{k^2-1}\frac{{\cos \mathrm{\&beta;}}_1-\cos k{\mathrm{\&beta;}}_1}{2-2\cos k{\mathrm{\&beta;}}_1-k^2{\mathrm{\&omega;}}^2{L}_{1}c}$

α ₂Satisfy equation:

$\frac{i_m}{{\mathrm{\&omega;}}^2{L}_{2}c(k^2-1)}[\cos (\mathrm{\&pi;}-{\mathrm{\&alpha;}}_2)-F\cos k(\mathrm{\&pi;}-{\mathrm{\&alpha;}}_2)+H_2]=0$

Wherein:

β ₁＝π-α ₁

${\mathrm{\&omega;}}_0=\frac{1}{\sqrt{\frac{L_1{L}_2}{{\mathrm{<figure-callout\; id="1"\; label="L"\; filenames="HDA0000100075870000013.png"\; state="\{\{state\}\}">L</figure-callout>}}_1+L_2}c}}$

$k=\frac{{\mathrm{\&omega;}}_0}{\mathrm{\&omega;}}=\frac{1}{2\mathrm{\&pi;<figure-callout\; id="1"\; label="f\; L"\; filenames="HDA0000100075870000013.png"\; state="\{\{state\}\}">f</figure-callout>}}\sqrt{\frac{L_{}}{}}\sqrt{\frac{{}_1+L_2}{L_1{L}_{2}c}}$

$F=1-\frac{2\cos {\mathrm{\&beta;}}_1-2\cos k{\mathrm{\&beta;}}_1}{2-2\cos k{\mathrm{\&beta;}}_1-k^2{\mathrm{\&omega;}}^2{L}_{1}c}$

$H_2=(L_2/L_1-1)\frac{\cos {\mathrm{\&beta;}}_1-\cos k{\mathrm{\&beta;}}_1}{2-2\cos k{\mathrm{\&beta;}}_1-k^2{\mathrm{\&omega;}}^2{L}_{1}c}$

is perunit value;

i _2maxBe TCR branch road 2 current amplitudes;

i _mBe the line current amplitude;

B: ask two TCR branch current amplitude i _1maxAnd i _2maxDifference Δ i _Max, Δ i _Max=i _1max-i _2max

C: by Δ i _MaxThrough the FEEDBACK CONTROL link, obtain current amplitude correction i _Revise, i _Revise+ i _1maxBid value as TCR branch road 2 current amplitudes;

D:, obtain the trigger angle α of TCR branch road 2 with the input of bid value and line circuit amplitude as Table2 ₂

E:TCR branch road 2 is at trigger angle α ₂Satisfy i down, _1max=i _2max

7) if there is new impedance step order to assign, then obtain trigger angle α through the impedance bid value ₁, obtain trigger angle α through step 6) ₂, realize the current-sharing of two TCR branch roads;

Wherein: said FEEDBACK CONTROL link is linear PI link.

Owing to adopted technique scheme, compared with prior art, beneficial effect of the present invention comprises:

1) the application adopts the method for two TCR branch road parallel connections; Make that the electric current that flows through every TCR branch road is less; Thereby solved existing thyristor valve not enough problem of through-current capability in the ultra high voltage controlled series compensation, a kind of new controlled series compensation implementation that is applicable to extra high voltage line is provided;

2) control strategy that has adopted amplitude to equate makes two TCR branch road conducting current amplitudes equate, has realized current-sharing as much as possible;

3) an impedance Control effect and a conventional controlled series compensation basically identical in the past with a TCR branch road; Having set up amplitude equates under the condition; The relation of impedance of fundamental frequency and trigger angle in the new controlled series compensation scheme, and, enable to satisfy requirement to impedance Control through tabling look-up and the PI link;

4) all controlling units are simple, all adopt Linear Control, in engineering, realize easily, and control stability are good, can be used for ultra high voltage and 750kV transmission line, has good versatility;

Description of drawings

Below in conjunction with accompanying drawing the present invention is further specified.

Fig. 1 is a double T CR branch road parallel connection scheme one;

Fig. 2 is a double T CR branch road parallel connection scheme two;

Fig. 3 is a double T CR branch road TCSC correlated variables sequential chart;

Fig. 4 is the relation curve of branch road 2 current amplitudes and trigger angle;

Fig. 5 is that amplitude equates control strategy control principle block diagram;

Fig. 6 is an impedance Control policy control theory diagram;

Fig. 7 is an instance emulation main circuit diagram;

Fig. 8 is initial command impedance oscillogram when being 1.2p.u.;

Fig. 9 be the order impedance by the 1.2p.u. step oscillogram during to 2.0p.u.;

Reference numeral:

α ₁, α ₂Be thyristor trigger angle initial value;

2 β ₁Be the thyristor angle of flow;

F is a system frequency;

L ₁, L ₂Be the reactor reactance value;

C is an electric capacity;

i _1max, i _2maxAmplitude for branch current;

i ^* _2maxPerunit value for branch current;

i _mFor circuit current amplitude in the main circuit, promptly flow through resistance R _LCurrent value;

Z _RefBe the order resistance value;

Z _MeasureFor measuring resistance value;

R _LBe the circuit equivalent resistance;

X _LBe the circuit equivalent reactance;

E is a voltage source.

Embodiment

Below in conjunction with instance the present invention is carried out detailed explanation.

The objective of the invention is,, propose a kind of controlled series compensation implementation, proposed the control corresponding target simultaneously to UHV transmission line, and for reaching the control strategy that controlled target adopts.

The present invention adopts the TCR branch road of two parallel connections as the technological means of regulating controlled series compensation device impedance of fundamental frequency.Article two, the parallel way of TCR branch road, the present invention proposes two kinds of schemes, and is as depicted in figs. 1 and 2 respectively.

Technical scheme among Fig. 1, two thyristor valves are connected with a reactor after inverse parallel, thereby constitute a TCR branch road, and two TCR branch roads carry out parallel connection more afterwards.Reactor reactance value on two TCR branch roads should equate in theory.All under the situation of conducting, the external equivalent inductive reactance of TCR branch road of two parallel connections can satisfy the adjusting requirement of controlled series compensation device at two branch roads.

Technical scheme among Fig. 2; Article two, the TCR branch road is except the independent reactor that has of string separately, and reactor is used in series connection altogether after parallel connection, at two branch roads all under the situation of conducting; Three reactors through connection in series-parallel after, its external equivalent inductive reactance can satisfy the adjusting requirement of controlled series compensation device.This scheme is than Fig. 1 scheme, and difference is that the required reactance value of valve string reactor on two parallelly connected TCR branch roads is less owing to have and use reactor altogether, thereby reduced the imbalance that the absolute error etc. of reactor manufacturing is brought, and more helps current-sharing.

The present invention has correspondingly proposed the sharing control target of two TCR branch road parallel connections, so that the TCR branch road current-sharing as much as possible of two parallel connections.Through the control corresponding link, make the current amplitude of two TCR branch roads equate respectively, make the current effective value of two TCR branch roads equate, make the current average of two TCR branch roads equate, thereby reach the purpose of current-sharing.

The present invention has also correspondingly proposed control method that the branch current amplitude the equates control strategy as the controlled series compensation implementation.In engineering reality, the reactance value of two TCR branch road institute string reactors can not be equal fully, and therefore, if the simple control strategy that triggers simultaneously that adopts, the electric current that flows through two TCR branch roads will occur uneven.In order to guarantee the equilibrium of two branch currents, the present invention adopts thyristor not trigger simultaneously, and the method that finally makes two branch current amplitudes equate is controlled.Current amplitude reach equate after, the impedance of fundamental frequency of whole controlled series compensation device also can reach required resistance value.

With the scheme among Fig. 1 is that example describes, and specifically may further comprise the steps:

1. the topology theory figure that analyzes the present invention's proposition (might as well establish L ₁＜L ₂), draw its Mathematical Modeling, through analysis, set up impedance of fundamental frequency Z and trigger angle α in the controlled series compensation implementation again to Mathematical Modeling ₁The impedance operator table.This table is newly to put forward among the present invention, and is different with single branch road controlled series compensation impedance relationship table in the past.

2. after the impedance order was assigned, through the impedance Control link, tabling look-up drew the relative trigger angle, as the thyristor trigger angle initial value of following two branch roads of this order impedance.

3. this moment, two thyristor trigger angle equated, i.e. conducting simultaneously, and not current-sharing will appear in two branch roads, and current amplitude should be unequal.

4. for the bigger TCR branch road 1 of current amplitude, keep its existing trigger angle α ₁Constant.

5. for the less TCR branch road 2 of current amplitude, the difference of the current amplitude of two branch roads of foundation and impedance order through the control corresponding link, make this branch road thyristor trigger angle α ₂Finally reach a new steady-state value.Under new stable state trigger angle, the amplitude of two branch currents equates, and the impedance of fundamental frequency value also can satisfy the control requirement.

6. if there is new impedance step order to assign, then check in trigger angle α through the impedance operator table ₁, obtain trigger angle α through step (5) ₂, realize control to impedance of fundamental frequency and current amplitude with this.

Embodiment 1:

1.TCR the acquisition of branch current amplitude

Adopt detection capacitance voltage zero crossing to produce the sampled signal pulse, the TCR branch current is sampled.Can find out from Fig. 3 sequential chart, as capacitance voltage u _cDuring zero passage, the electric current of TCR branch road (i among the figure _L1And i _L2) absolute value reaches maximum.Utilize this relation,, produce a sampling pulse signal through detecting the capacitance voltage zero crossing; Electric current to two TCR branch roads is sampled respectively, after the sampled value of acquisition, takes absolute value; As the amplitude of two branch currents, and in following algorithm and control strategy, use.

2. the equal control of two TCR branch current amplitudes

With parallelly connected scheme shown in Figure 1 is that example (might as well be established L ₁＜L ₂), the embodiment that the subcircuits current amplitude is equated describes.

After the order impedance is assigned, utilize impedance operator table Table1 to check in the thyristor trigger angle initial value α of two branch roads ₁=α ₂Because L ₁＜L ₂So,, this moment two branch currents amplitude i _1max＞i _2maxAfterwards, make α ₁Remain unchanged, and to α ₂Value adjust control so that i _1max=i _2max

For a certain given α ₁Angle, topological structure and mathematical derivation by circuit can draw corresponding i _2maxValue, try to achieve by formula (1)

$i_{2\max }^{*}=\frac{i_{2\max }}{i_m}=\frac{k^2}{k^2-1}*\frac{{\cos \mathrm{\&beta;}}_1-\cos k{\mathrm{\&beta;}}_1}{2-2\cos k{\mathrm{\&beta;}}_1-k^2{\mathrm{\&omega;}}^2{L}_{1}c}---\left(1\right)$

Wherein

β ₁＝π-α ₁

${\mathrm{\&omega;}}_0=\frac{1}{\sqrt{\frac{L_1{L}_2}{{\mathrm{<figure-callout\; id="1"\; label="L"\; filenames="HDA0000100075870000013.png"\; state="\{\{state\}\}">L</figure-callout>}}_1+L_2}c}}$

$k=\frac{{\mathrm{\&omega;}}_0}{\mathrm{\&omega;}}=\frac{1}{2\mathrm{\&pi;<figure-callout\; id="1"\; label="f\; L"\; filenames="HDA0000100075870000013.png"\; state="\{\{state\}\}">f</figure-callout>}}\sqrt{\frac{L_{}}{}}\sqrt{\frac{{}_1+L_2}{L_1{L}_{2}c}}$

In the formula (1)

Be perunit value, with line current amplitude i _mBe fiducial value; 2 β ₁The expression thyristor angle of flow, as shown in Figure 3; F is a system frequency.For different line current amplitude i _m, the current amplitude i of branch road 2 _2maxFamous value different.Corresponding α ₂Value can get by following equation approximate solution

$\frac{i_m}{{\mathrm{\&omega;}}^2{L}_{2}c(k^2-1)}[\cos (\mathrm{\&pi;}-{\mathrm{\&alpha;}}_2)-F\cos k(\mathrm{\&pi;}-{\mathrm{\&alpha;}}_2)+H_2]=0---\left(2\right)$

Wherein

$F=1-\frac{2\cos {\mathrm{\&beta;}}_1-2\cos k{\mathrm{\&beta;}}_1}{2-2\cos k{\mathrm{\&beta;}}_1-k^2{\mathrm{\&omega;}}^2{L}_{1}c}$

$H_2=(L_2/L_1-1)\frac{\cos {\mathrm{\&beta;}}_1-\cos k{\mathrm{\&beta;}}_1}{2-2\cos k{\mathrm{\&beta;}}_1-k^2{\mathrm{\&omega;}}^2{L}_{1}c}$

β ₁＝π-α ₁

So far, can draw corresponding i _2maxAnd α ₂Corresponding relation, as shown in Figure 4.Among Fig. 4, abscissa is 100 times of perunit values of branch road 2 current amplitudes, and ordinate is corresponding trigger angle α ₂Adopt form to handle in the practical application, set up current amplitude i _2maxThyristor trigger angle α with branch road 2 ₂Mapping table Table2, the corresponding different relationships curve of different line current obtains the thyristor trigger angle α of branch road 2 through lookup table mode ₂

Except setting up the thyristor trigger angle α of branch road 2 ₂With current amplitude i _2maxThe corresponding relation off-balancesheet, install feedback element again additional, the PI link in as shown in Figure 5 can be regulated so that current amplitude reaches indifference.The theory diagram of The whole control strategy is as shown in Figure 5.

3. the control of impedance of fundamental frequency

From 2., can know, if α ₁Change α ₂Also can change accordingly through the amplitude adjustment, utilize this relation also to control, can make the first-harmonic equiva lent impedance of two branch road controlled series compensations reach the order resistance value.Through circuit topological structure and mathematical derivation, can draw that impedance of fundamental frequency Z depends on α to a great extent under the control strategy that amplitude equates to Fig. 1 ₁So impedance of fundamental frequency Z is approximate with formula (3)

$Z=\frac{1}{\mathrm{\&omega;c}}-\frac{2A}{\mathrm{\&pi;}{k}^2{\mathrm{\&omega;}}^3{c}^2}\left\{(\frac{1}{{\mathrm{<figure-callout\; id="1"\; label="L"\; filenames="HDA0000100075870000013.png"\; state="\{\{state\}\}">L</figure-callout>}}_1}+\frac{1}{L_2})\right[{\mathrm{\&beta;}}_1+\frac{1}{2}\sin 2{\mathrm{\&beta;}}_1-\frac{2F\cos {\mathrm{\&beta;}}_1\cos k{\mathrm{\&beta;}}_1}{k^2-1}(k\tan k{\mathrm{\&beta;}}_1-\tan {\mathrm{\&beta;}}_1)]$

$+(\frac{H_1}{{\mathrm{<figure-callout\; id="1"\; label="L"\; filenames="HDA0000100075870000013.png"\; state="\{\{state\}\}">L</figure-callout>}}_1}+\frac{H_2}{L_2})\sin {\mathrm{\&beta;}}_1\}---\left(3\right)$

Wherein

$A=\frac{k^2}{k^2-1}$

$F=1-\frac{2\cos {\mathrm{\&beta;}}_1-2\cos k{\mathrm{\&beta;}}_1}{2-2\cos k{\mathrm{\&beta;}}_1-k^2{\mathrm{\&omega;}}^2{L}_{1}c}$

${\mathrm{<figure-callout\; id="1"\; label="H"\; filenames="HDA0000100075870000013.png"\; state="\{\{state\}\}">H</figure-callout>}}_1=({\mathrm{<figure-callout\; id="1"\; label="L"\; filenames="HDA0000100075870000013.png"\; state="\{\{state\}\}">L</figure-callout>}}_1/L_2-1)\frac{\cos {\mathrm{\&beta;}}_1-\cos k{\mathrm{\&beta;}}_1}{2-2\cos k{\mathrm{\&beta;}}_1-k^2{\mathrm{\&omega;}}^2{L}_{1}c}$

$H_2=(L_2/L_1-1)\frac{\cos {\mathrm{\&beta;}}_1-\cos k{\mathrm{\&beta;}}_1}{2-2\cos k{\mathrm{\&beta;}}_1-k^2{\mathrm{\&omega;}}^2{L}_{1}c}$

β ₁＝π-α ₁

Formula (1) is too complicated, still adopts form to handle, and sets up the thyristor trigger angle α of impedance of fundamental frequency Z and branch road 1 ₁Relation table Table1, can obtain to order corresponding α under the impedance through tabling look-up ₁Value.

Except setting up impedance of fundamental frequency Z and α ₁The corresponding relation off-balancesheet, install feedback element again additional, like the PI link among Fig. 6, can regulate so that impedance of fundamental frequency Z reaches indifference quickly.The control principle block diagram is as shown in Figure 6.

Embodiment 2:

According to the above, adopt ball bearing made using shown in Figure 7, methods of the present invention are carried out simulation analysis, to verify feasibility of the present invention.Be example still with the said scheme of Fig. 1.Among Fig. 7, the voltage source amplitude is 500kV, circuit equivalent resistance R _L=11.0 Ω, circuit equivalent reactance X _L=111.15 Ω, the basic capacitance C=190.5 μ F of controlled series compensation, the inductance of two valve string reactors is measured maximum manufacturing process error ± 5%, L ₁=0.01729H, L ₂=0.01911H.

According to the main circuit parameter and the formula (3) of artificial circuit, can set up the impedance operator table that is applicable to double T CR branch road parallel connection TCSC, shown in subordinate list 1.Only choose some points in the table 1 and describe, should carry out intensive getting a little according to the minimum interval in the engineering during practical application, so that the impedance operator table satisfies the requirement of control precision.Resistance value is represented emotional resistance for just; Resistance value is represented capacitive reactances for negative.Trigger angle is represented with angle.

Table 1 impedance operator table

When the initial impedance order was 12 times of perunit values, simulation waveform figure was as shown in Figure 8.0.4 a second place drops into the current amplitude controlling unit, can find out two branch currents through after adjusting, it is equal that amplitude is tending towards, and resistance value reaches 12 times perunit value.

Located at 1 second afterwards, assign the order of impedance step, the impedance bid value steps to 2.0 times of perunit values from 12 times of perunit values, and simulation waveform figure is as shown in Figure 9.Can find out that after impedance Control link and current amplitude controlling unit, the current amplitude of two branch roads is tending towards equal, resistance value reaches 2.0 times perunit value.

Thereby the feasibility of checking the present invention program and control strategy thereof.

Invention has been described according to specific exemplary embodiment here.It will be conspicuous under not departing from the scope of the present invention, carrying out suitable replacement to one skilled in the art or revise.Exemplary embodiment only is illustrative, rather than to the restriction of scope of the present invention, scope of the present invention is by appended claim definition.

Claims (4)

1. controlled series compensation device based on double T CR branch road parallel connection, said string is mended device and is comprised capacitor; It is characterized in that said string benefit device comprises the TCR branch road of two parallel connections, the TCR branch road of two parallel connections is parallelly connected with said capacitor; Every TCR props up antiparallel two thyristor valves of route and reactor is composed in series, and when string was mended the device conducting, the TCR branch current amplitude of said two parallel connections equated that perhaps effective value equates, perhaps mean value equates.

2. a kind of controlled series compensation device as claimed in claim 1, the TCR branch road that it is characterized in that two parallel connections reactor L that connects based on double T CR branch road parallel connection ₃Parallelly connected with capacitor again.

3. the control method that string as claimed in claim 1 is mended device is characterized in that said method comprises the steps:

1) sets up impedance of fundamental frequency Z and trigger angle α ₁Between impedance operator table Table1, according to as follows:

$Z=\frac{1}{\mathrm{\&omega;c}}-\frac{2A}{\mathrm{\&pi;}{k}^2{\mathrm{\&omega;}}^3{c}^2}\left\{(\frac{1}{L_1}+\frac{1}{L_2})\right[{\mathrm{\&beta;}}_1+\frac{1}{2}\sin 2{\mathrm{\&beta;}}_1-\frac{2F\cos {\mathrm{\&beta;}}_1\cos k{\mathrm{\&beta;}}_1}{k^2-1}(k\tan k{\mathrm{\&beta;}}_1-\tan {\mathrm{\&beta;}}_1)]$

$+(\frac{H_1}{L_1}+\frac{H_2}{L_2})\sin {\mathrm{\&beta;}}_1\}$

Wherein:

${\mathrm{\&omega;}}_0=\frac{1}{\sqrt{\frac{L_1{L}_2}{L_1+L_2}c}}$

ω＝2πf

$k=\frac{{\mathrm{\&omega;}}_0}{\mathrm{\&omega;}}=\frac{1}{2\mathrm{\&pi;f}}\sqrt{\frac{L_1+L_2}{L_1{L}_{2}c}}$

$A=\frac{k^2}{k^2-1}$

$F=1-\frac{2\cos {\mathrm{\&beta;}}_1-2\cos k{\mathrm{\&beta;}}_1}{2-2\cos k{\mathrm{\&beta;}}_1-k^2{\mathrm{\&omega;}}^2{L}_{1}c}$

$H_1=(L_1/L_2-1)\frac{\cos {\mathrm{\&beta;}}_1-\cos k{\mathrm{\&beta;}}_1}{2-2\cos k{\mathrm{\&beta;}}_1-k^2{\mathrm{\&omega;}}^2{L}_{1}c}$

$H_2=(L_2/L_1-1)\frac{\cos {\mathrm{\&beta;}}_1-\cos k{\mathrm{\&beta;}}_1}{2-2\cos k{\mathrm{\&beta;}}_1-k^2{\mathrm{\&omega;}}^2{L}_{1}c}$

β ₁＝π-α ₁

F: be system frequency;

L ₁, L ₂: be the reactance value of reactor;

C: be condenser capacitance;

2) the impedance order obtains

A: ask the order impedance Z _RefWith the measurement impedance Z _MeasureDifference;

B: the impedance difference obtains order impedance correction through the FEEDBACK CONTROL link, order impedance correction and order impedance Z _RefAddition is as the impedance bid value;

3) assign the impedance order, draw relative trigger angle α through Table1 ₁, as the thyristor trigger angle initial value of following two branch roads of this order impedance;

4) two thyristor trigger angle equate, L is worked as in thyristor conducting simultaneously ₁=L ₂The time, execution in step 7); Work as L ₁≠ L ₂The time, two TCR branch current amplitude i _MaxUnequal, execution in step 5);

5) establish L ₁＜L ₂, i _1max＞i _2max, the trigger angle α of maintenance TCR branch road 1 ₁Constant;

6) obtain the trigger angle α of TCR branch road 2 ₂, make i _1max=i _2max

The measurement of TCR branch current amplitude:

A: adopt detection capacitance voltage zero crossing to produce the sampled signal pulse;

B: the TCR branch current is sampled;

C: get the current amplitude i of the absolute value of sample rate current value as the TCR branch road _1maxAnd i _2max

The control of two TCR branch road current-sharings:

A: set up TCR branch road 2 current amplitude i _2maxWith trigger angle α ₂Relation table Table2, according to as follows:

$i_{2\max }^{*}=\frac{i_{2\max }}{i_m}=\frac{k^2}{k^2-1}\frac{{\cos \mathrm{\&beta;}}_1-\cos k{\mathrm{\&beta;}}_1}{2-2\cos k{\mathrm{\&beta;}}_1-k^2{\mathrm{\&omega;}}^2{L}_{1}c}$

α ₂Satisfy equation:

$\frac{i_m}{{\mathrm{\&omega;}}^2{L}_{2}c(k^2-1)}[\cos (\mathrm{\&pi;}-{\mathrm{\&alpha;}}_2)-F\cos k(\mathrm{\&pi;}-{\mathrm{\&alpha;}}_2)+H_2]=0$

Wherein:

β ₁＝π-α ₁

${\mathrm{\&omega;}}_0=\frac{1}{\sqrt{\frac{L_1{L}_2}{L_1+L_2}c}}$

$k=\frac{{\mathrm{\&omega;}}_0}{\mathrm{\&omega;}}=\frac{1}{2\mathrm{\&pi;f}}\sqrt{\frac{L_1+L_2}{L_1{L}_{2}c}}$

$F=1-\frac{2\cos {\mathrm{\&beta;}}_1-2\cos k{\mathrm{\&beta;}}_1}{2-2\cos k{\mathrm{\&beta;}}_1-k^2{\mathrm{\&omega;}}^2{L}_{1}c}$

$H_2=(L_2/L_1-1)\frac{\cos {\mathrm{\&beta;}}_1-\cos k{\mathrm{\&beta;}}_1}{2-2\cos k{\mathrm{\&beta;}}_1-k^2{\mathrm{\&omega;}}^2{L}_{1}c}$

is perunit value;

i _2maxBe TCR branch road 2 current amplitudes;

i _mBe the line current amplitude;

B: ask two TCR branch current amplitude i _1maxAnd i _2maxDifference Δ i _Max, Δ i _Max=i _1max-i _2max

C: by Δ i _MaxThrough the FEEDBACK CONTROL link, obtain current amplitude correction i _Revise, i _Revise+ i _1maxBid value as TCR branch road 2 current amplitudes;

D:, obtain the trigger angle α of TCR branch road 2 with the input of bid value and line circuit amplitude as Table2 ₂

E:TCR branch road 2 is at trigger angle α ₂Satisfy i down, _1max=i _2max

7) if there is new impedance step order to assign, then obtain trigger angle α through the impedance bid value ₁, obtain trigger angle α through step 6) ₂, realize the current-sharing of two TCR branch roads;

4. string as claimed in claim 3 is mended apparatus control method, it is characterized in that said FEEDBACK CONTROL link is linear PI link.

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