CN104242331A - Extra-high voltage direct current control system suitable for electromechanical transient simulation - Google Patents

Abstract

The invention provides an extra-high voltage direct current control system suitable for electromechanical transient simulation. The extra-high voltage direct current control system suitable for electromechanical transient simulation comprises a current fire angle output module, a restart control module and a selection module. The current fire angle output module and the restart control module output current fire angles and restart fire angles respectively, and the current fire angles and the restart fire angles obtain fire angle instruction values through the selection module. The extra-high voltage direct current control system suitable for electromechanical transient simulation overcomes the defects of an existing direct current transmission control system, overcomes the defects of the simulation capacity of the existing direct current transmission control system, accurately reflects the control characteristics of extra-high voltage direct current projects, and solves the simulation accuracy problem of the control over an existing electromechanical transient direct current model.

Description

A kind of extra-high voltage direct-current control system being applicable to electromechanical transient simulation

Technical field

The present invention relates to a kind of control system, be specifically related to a kind of extra-high voltage direct-current control system being applicable to electromechanical transient simulation.

Background technology

Extra-high voltage direct-current engineering puts into operation continuously, and the ac and dc systems effect of influencing each other significantly.The transient characterisitics of extra-high voltage direct-current determined primarily of its control system, are therefore the key of direct current modeling during electromechanical transient calculates to the accurate simulation of extra-high voltage direct-current control system.Original electromechanical transient direct current simulation model of domestic use is mainly the DC Model in electromechanical transient simulation software PSD-BPA and PSASP, and their major defect is:

(1) overall control strategy is simple, does not possess some key modules of modern DC transmission engineering;

(2) implementation method of main modular and ultra high voltage Practical Project difference large.

Generally speaking, because characteristic gap is comparatively large, original DC control system is the simulation calculation not being suitable for extra-high voltage direct-current engineering, sets up and accurately can reflect that the control system of extra-high voltage direct-current control characteristic is very necessary.

Summary of the invention

For overcoming the shortcoming of original DC power transmission control system, make up the deficiency of its simulation capacity, the invention provides a kind of extra-high voltage direct-current control system being applicable to electromechanical transient simulation, be applicable to the extra-high voltage direct-current control system of electromechanical transient simulation, reflect the control characteristic of extra-high voltage direct-current engineering comparatively accurately, solve the accuracy of simulation problem that original electromechanical transient DC Model controls.

In order to realize foregoing invention object, the present invention takes following technical scheme:

The invention provides a kind of extra-high voltage direct-current control system being applicable to electromechanical transient simulation, described system comprises current trigger angle output module, restarts control module and select module; Described current trigger angle output module and restart control module output current Trigger Angle and restart Trigger Angle respectively, described current trigger angle and restart Trigger Angle and obtain Trigger Angle command value by selection module.

Described current trigger angle output module comprises main control module, current limiting low-voltage control module and current control module; Described main control module output current command value I _o, I _ocurrent-order amplitude limit value I is obtained by current limiting low-voltage control module _olim, I _olimthrough current control module output current Trigger Angle α _i.

In described main control module, run on firm power control model or constant current control model by the 5th selector certainty annuity; Described 5th selector output current instruction operation value I _op, then through current-order compensatory control, by I _opwith direct current I _ddeviation carry out as compensation rate after integration, with I _opbe added and obtain final current instruction value I _o, have:

$I_o=I_{\mathrm{op}}+\underset{0}{\overset{0.1I_n}{\∫}}(I_{\mathrm{op}}-I_d)\mathrm{dt}---\left(1\right)$

Wherein, I _ndirect current rated value;

Current-order runtime value I _opdetermination be divided into following two kinds of situations:

(1) as the switching value Mode=1 of the 5th selector, system cloud gray model in firm power control model, direct voltage U _dfirst pass through the firstorder filter with lower amplitude limit, the time constant filter of this firstorder filter is T ₀, lower amplitude limit is U _dmin, the direct voltage U after firstorder filter output filtering _dfilt, current-order runtime value I _opfor:

$I_{\mathrm{op}}=\frac{P_{\mathrm{ref}}}{U_{\mathrm{dfilt}}}---\left(2\right)$

Wherein, P _reffor set direct current power reference value;

(2) as the switching value Mode=0 of the 5th selector, system cloud gray model in constant current control model, current-order runtime value I _opfor:

I _op＝I _ref (3)

In formula: I _reffor set current-order reference value.

In described current limiting low-voltage control module, direct voltage U _dfirst through firstorder filter with filtering high dither, the time constant filter T of this firstorder filter is adjustable, if U _dfor ascendant trend, T gets filtering time rising constant T _upif, U _dfor downward trend, T gets filtering time decline constant T _dn; Again according to the direct voltage U that this firstorder filter exports _df, according to interpolation calculation current-order amplitude limit value I _olim, have:

$\left\{\begin{array}{cc}{I}_{\mathrm{olim}}=I_o& U_{\mathrm{df}}\≥U_{\mathrm{dhigh}}\\ I_{\mathrm{olim}}=I_{o\min }+\frac{I_o-I_{o\min }}{U_{\mathrm{dhigh}}-U_{\mathrm{dlow}}}(U_{\mathrm{df}}-U_{\mathrm{dlow}})& U_{\mathrm{dhigh}}>U_{\mathrm{df}}>U_{\mathrm{dlow}}\\ I_{\mathrm{olim}}=I_{o\min }& U_{\mathrm{df}}\≤U_{\mathrm{dlow}}\end{array}\right.---\left(4\right)$

Wherein, I _ofor the current instruction value that current instruction value output module exports, I _ominfor set minimum current command value, U _dhighfor the starting resistor of current limiting low-voltage control module, U _dlowvoltage is exited for current limiting low-voltage control module.

Described current control module output current Trigger Angle α _ispecifically comprise the following steps:

Step a: calculate direct current I _dwith current-order amplitude limit value I _olimbetween current deviation and amplify, the current deviation I be amplified _diff, distinguish rectification side and inverter side, select current margins by the 6th selector, make both sides keep the current margins of 0.1pu, I _diffbe expressed as:

Wherein, Gain is multiplication factor;

Step b:I _diffthrough proportional branch, obtain α _iproportional component α _i_ P, specifically has:

Wherein, K _pifor proportional gain, for current trigger angle α _iprevious step calculated value, for comparative example gain K _pIcarry out the modifying factor revised;

I _diffsimultaneously through integration branch road, obtain α _iquadrature components α _i_ I, specifically has:

${\mathrm{\α}}_i\_I=\frac{1}{T_{\mathrm{ii}}}\underset{{\mathrm{\α}}_{i\min }}{\overset{{\mathrm{\α}}_{i\max }}{\∫}}{I}_{\mathrm{diff}}\mathrm{dt}---\left(7\right)$

Wherein, T _iiintegration time constant, α _imaxfor current trigger angle higher limit, α _iminfor current trigger angle lower limit;

α _i_ P and α _ithrough amplitude limit again after _ I is added, obtain current trigger angle α _i, have:

${\mathrm{\&alpha;}}_i=\left\{\begin{array}{cc}{\mathrm{\&alpha;}}_{i\max }& {\mathrm{\&alpha;}}_i\_P+{\mathrm{\&alpha;}}_i\_I>{\mathrm{\&alpha;}}_{i\max }\\ {\mathrm{\&alpha;}}_i\_P+{\mathrm{\&alpha;}}_i\_I& {\mathrm{\&alpha;}}_{i\max }\&le;{\mathrm{\&alpha;}}_i\_P+{\mathrm{\&alpha;}}_i\_I\&le;{\mathrm{\&alpha;}}_{i\max }\\ {\mathrm{\&alpha;}}_{i\min }& {\mathrm{\&alpha;}}_i\_P+{\mathrm{\&alpha;}}_i\_I<{\mathrm{\&alpha;}}_{i\min }\end{array}\right.---\left(8\right).$

Current trigger angle higher limit α _imaxjointly determined by voltage control module, commutation failure PREDICTIVE CONTROL module, gamma kick module, and select to be positioned at rectification side or inverter side by first selector;

In rectification side, described commutation failure PREDICTIVE CONTROL module exports commutation margin angle Δ α, is exported through revised maximum Trigger Angle α ' by gamma kick module _max, this α ' _maxbe current trigger angle higher limit α _imax;

In inverter side, α ' _maxinput to described voltage control module, the voltage triggered angle α that voltage control module exports _vbe current trigger angle higher limit α _imax.

Voltage control module output voltage Trigger Angle α _v, specifically comprise the following steps:

Step a: distinguish rectification side and inverter side, calculates direct voltage U by the 7th selector, the 8th selector and the 9th selector _dwith direct voltage reference value U _drefbetween current deviation U _diff, have:

Wherein, Δ U _drwith Δ U _dibe respectively rectification side and inverter side voltage instruction nargin, R is the resistance of DC line;

Step b: enter proportional plus integral control and amplitude limit subsequently, output voltage Trigger Angle α _v, specifically have:

${\mathrm{\&alpha;}}_v=\left\{\begin{array}{cc}{\mathrm{\&alpha;}}_{\max }^{\&prime;}& K_{\mathrm{pv}}\&times;U_{\mathrm{diff}}+\frac{1}{T_{\mathrm{iv}}}\stackrel{{\mathrm{\&alpha;}}_{\max }^{\&prime;}}{\&Integral;}{U}_{\mathrm{diff}}\mathrm{dt}>{\mathrm{\&alpha;}}_{\max }^{\&prime;}\\ K_{\mathrm{pv}}\&times;U_{\mathrm{diff}}+\frac{1}{T_{\mathrm{iv}}}\stackrel{{\mathrm{\&alpha;}}_{\max }^{\&prime;}}{\&Integral;}{U}_{\mathrm{diff}}\mathrm{dt}& K_{\mathrm{pv}}\&times;U_{\mathrm{diff}}+\frac{1}{T_{\mathrm{iv}}}\stackrel{{\mathrm{\&alpha;}}_{\max }^{\&prime;}}{\&Integral;}{U}_{\mathrm{diff}}\mathrm{dt}\&le;{\mathrm{\&alpha;}}_{\max }^{\&prime;}\end{array}\right.---\left(10\right)$

Wherein, K _pvfor proportional gain, T _ivfor integration time constant, α ' _maxfor the revised maximum Trigger Angle that extinguish angle prediction module exports.

Described gamma kick module exports maximum Trigger Angle α _max, α _maxbe expressed as:

Wherein, γ _reffor extinguish angle reference value, d _xfor commutating reactance, U _di0for ideal no-load direct voltage;

Through the dynamic corrections of volt-ampere characteristic slope, revised maximum Trigger Angle α ' _max:

Wherein, k is modified gain.

Described commutation failure PREDICTIVE CONTROL module exports commutation margin angle Δ α by the 12 selector, has:

$\left\{\begin{array}{cc}\mathrm{\&Delta;\&alpha;}=0& U_{\mathrm{ac}0}-U_{\mathrm{ac}}\&le;1-K_{\mathrm{cf}}\\ \mathrm{\&Delta;\&alpha;}=\arccos (1-G_{\mathrm{cf}}\&times;(U_{\mathrm{ac}0}-U_{\mathrm{ac}}))& U_{\mathrm{ac}0}-U_{\mathrm{ac}}>1-K_{\mathrm{cf}}\end{array}\right.---\left(13\right)$

Wherein, U _ac0for initial steady state ac bus positive sequence voltage, U _acfor actual ac bus positive sequence voltage, K _cffor commutation failure voltage threshold, G _cffor commutation failure voltage gain;

During normal operation, Δ α=0; When fault occurs, if Voltage Drop amplitude exceedes the commutation failure voltage threshold K of setting _cf, calculate commutation margin angle Δ α by (12).

Current trigger angle lower limit α _iminjointly determined by voltage control module, rectification side minimum trigger angle control module, voltage resume control module and third selector, and select to be positioned at rectification side or inverter side by second selector;

In rectification side, rectification side minimum trigger angle control module exports minimum trigger angle α _min, itself and voltage triggered angle α _v, the minimum angle constant of rectification side gets maximum, this maximum is current trigger angle lower limit α _imin;

In inverter side, voltage resume control module output voltage accelerates mark, and this voltage accelerates mark and inputs to third selector, when voltage accelerates to indicate and starts, and current trigger angle lower limit α _iminequal voltage triggered angle α _v, otherwise equal the minimum angle constant of inverter side.

Rectification side minimum trigger angle control module exports minimum trigger angle α _minspecifically comprise following situation:

(1) when normally running, actual ac bus positive sequence voltage U _achigher than the ac bus positive sequence voltage first order threshold k preset ₁with second level threshold k ₂, and K ₁<K ₂, determine α by the tenth selector _min=0;

(2) when fault occurs, U _aclower than first order threshold k ₁, then α is determined by the tenth selector _min=C _dl, wherein C _dlfor first order minimum trigger angle;

(3) if U _accontinue to be reduced to and be less than second level threshold k ₂, then α is determined by the 11 selector _min=D _l, wherein D _lfor second level minimum trigger angle;

(4) if U after fault clearance _acreturn to higher than first order threshold k ₁, then by α _minfrom C _dlwith fixed rate D _ecrdrop to zero gradually.

If direct voltage is lower than 0.6pu and exceed low-voltage time delay T ₁, then voltage resume control module starts, and voltage resume control module output voltage accelerates mark URC_ON, makes URC_ON put 1, shows to force inverter side current trigger angle to be the voltage triggered angle α that voltage control module exports _v, to promote the resume speed of direct voltage;

If direct voltage returns to more than 0.7pu, then voltage resume control module exits, and the minimum angle constant of inverter side is selected at the current trigger angle of inverter side.

The minimum angle constant of described rectification side gets 5 °, and the minimum angle constant of described inverter side gets 110 °.

Described restart control module export restart Trigger Angle α _rewith current trigger angle α _itrigger Angle command value α is obtained by selecting module _ord, described selection module is the 4th selector.

Described restart control module export restart Trigger Angle α _respecifically comprise the following steps:

Step a: judge system whether because the short trouble of DC line enters the state of restarting according to criterion, if condition meets, what enter step b restarts control; Criterion is as follows:

I _dr-I _di＞K _res (14)

Wherein, I _drfor rectification side direct current, I _difor inverter side direct current, K _resfor the difference between current threshold value between rectification side and inverter side;

Step b: restart control detailed process as follows:

1) Trigger Angle α will be restarted _resetting in 164 °, restart number counter and add up;

2) if restart number counter number of times more than 3 times, then block signal is sent; If be no more than 3 times, α _rekeep α after 164 ° of state continuance 0.15s _re35ms is kept again setting in 60 °;

3) again judge system mode according to criterion, if still meet criterion, then repeat to restart control.

Compared with prior art, beneficial effect of the present invention is:

1, the extra-high voltage direct-current control system being applicable to electromechanical transient simulation provided by the invention, reflects the control characteristic of extra-high voltage direct-current engineering comparatively accurately, solves the accuracy of simulation problem that original electromechanical transient DC Model controls.

2, the extra-high voltage direct-current control system being applicable to electromechanical transient simulation provided by the invention is the engineering design of extra-high voltage direct-current system, and containing extra-high voltage direct-current alternating current-direct current electrical network planning, run provide simulation means and technical support.

Accompanying drawing explanation

Fig. 1 is the extra-high voltage direct-current control system block diagram being applicable to electromechanical transient simulation in the embodiment of the present invention;

Fig. 2 is main control module logic diagram in the embodiment of the present invention;

Fig. 3 is embodiment of the present invention mesolow current limit control module logic diagram;

Fig. 4 is current control module logic diagram in the embodiment of the present invention;

Fig. 5 is voltage control module logic diagram in the embodiment of the present invention;

Fig. 6 is gamma kick module logic block diagram in the embodiment of the present invention;

Fig. 7 is commutation failure PREDICTIVE CONTROL module logic block diagram in the embodiment of the present invention;

Fig. 8 is rectification side minimum trigger angle control module logic diagram in the embodiment of the present invention;

Fig. 9 is voltage resume control module logic diagram in the embodiment of the present invention;

Figure 10 is Hami-Zhengzhou in the embodiment of the present invention ± 800kV DC transmission system winding diagram;

Figure 11 is that in the embodiment of the present invention, rectification side direct voltage transient emulation curve and actual curve contrast schematic diagram;

Figure 12 is that in the embodiment of the present invention, rectification side direct current transient emulation curve and actual curve contrast schematic diagram;

Figure 13 is that in the embodiment of the present invention, rectification side Trigger Angle transient emulation curve and actual curve contrast schematic diagram;

Figure 14 is inverter side direct voltage transient emulation curve and actual curve contrast schematic diagram in the embodiment of the present invention;

Figure 15 is inverter side direct current transient emulation curve and actual curve contrast schematic diagram in the embodiment of the present invention;

Figure 16 is inverter side Trigger Angle transient state transient emulation curve and actual curve contrast schematic diagram in the embodiment of the present invention;

Figure 17 is direct voltage transient emulation curve and system debug curve comparison schematic diagram in DC line in the embodiment of the present invention;

Figure 18 is direct current transient emulation curve and system debug curve comparison schematic diagram in DC line in the embodiment of the present invention;

Figure 19 is direct current Trigger Angle transient emulation curve and system debug curve comparison schematic diagram in DC line in the embodiment of the present invention.

Embodiment

Below in conjunction with accompanying drawing, the present invention is described in further detail.

As Fig. 1, the invention provides a kind of extra-high voltage direct-current control system being applicable to electromechanical transient simulation, described system comprises current trigger angle output module, restarts control module and select module; Described current trigger angle output module and restart control module output current Trigger Angle and restart Trigger Angle respectively, described current trigger angle and restart Trigger Angle and obtain Trigger Angle command value by selection module.

Described current trigger angle output module comprises main control module, current limiting low-voltage control module and current control module; Described main control module output current command value I _o, I _ocurrent-order amplitude limit value I is obtained by current limiting low-voltage control module _olim, I _olimthrough current control module output current Trigger Angle α _i.

As Fig. 2, described main control module realizes the conversion from power definite value to current instruction value, comprises the functions such as the selection of power/current control model, DC voltage filtering, current-order calculating, current-order compensation.Main control module is the integration that bipolar power controls, pole power control section is divided to Practical Project and simplification, only retains the main line of calculating current instruction.Firm power control model or constant current control model is run on by the 5th selector certainty annuity; Described 5th selector output current instruction operation value I _op, then through current-order compensatory control, by I _opwith direct current I _ddeviation carry out as compensation rate after integration, with I _opbe added and obtain final current instruction value I _o, have:

$I_o=I_{\mathrm{op}}+\underset{0}{\overset{0.1I_n}{\&Integral;}}(I_{\mathrm{op}}-I_d)\mathrm{dt}---\left(1\right)$

Wherein, I _ndirect current rated value;

The main purpose arranging current-order compensation is the control ability strengthening electric current, the maximum 0.1I of setting compensation simultaneously _n(500A), to avoid overcompensation.

Current-order runtime value I _opdetermination be divided into following two kinds of situations:

(1) as the switching value Mode=1 of the 5th selector, system cloud gray model in firm power control model, direct voltage U _dfirst pass through the firstorder filter with lower amplitude limit, the time constant filter of this firstorder filter is T ₀, lower amplitude limit is U _dmin, the direct voltage U after firstorder filter output filtering _dfilt, current-order runtime value I _opfor:

$I_{\mathrm{op}}=\frac{P_{\mathrm{ref}}}{U_{\mathrm{dfilt}}}---\left(2\right)$

Wherein, P _reffor set direct current power reference value;

(2) as the switching value Mode=0 of the 5th selector, system cloud gray model in constant current control model, current-order runtime value I _opfor:

I _op＝I _ref (3)

In formula: I _reffor set current-order reference value.

As Fig. 3, the Main Function of current limiting low-voltage control module is when the direct voltage that breaks down reduces, and reduces current instruction value simultaneously, to reduce valve group stress, accelerates the resume speed of direct current.

Direct voltage U _dfirst through firstorder filter with filtering high dither, the time constant filter T of this firstorder filter is adjustable, if U _dfor ascendant trend, T gets filtering time rising constant T _upif, U _dfor downward trend, T gets filtering time decline constant T _dn; Again according to the direct voltage U that this firstorder filter exports _df, according to interpolation calculation current-order amplitude limit value I _olim, have:

$\left\{\begin{array}{cc}{I}_{\mathrm{olim}}=I_o& U_{\mathrm{df}}\&GreaterEqual;U_{\mathrm{dhigh}}\\ I_{\mathrm{olim}}=I_{o\min }+\frac{I_o-I_{o\min }}{U_{\mathrm{dhigh}}-U_{\mathrm{dlow}}}(U_{\mathrm{df}}-U_{\mathrm{dlow}})& U_{\mathrm{dhigh}}>U_{\mathrm{df}}>U_{\mathrm{dlow}}\\ I_{\mathrm{olim}}=I_{o\min }& U_{\mathrm{df}}\&le;U_{\mathrm{dlow}}\end{array}\right.---\left(4\right)$

Wherein, I _ofor the current instruction value that current instruction value output module exports, I _ominfor set minimum current command value, U _dhighfor the starting resistor of current limiting low-voltage control module, U _dlowvoltage is exited for current limiting low-voltage control module.

As Fig. 4, current control module output current Trigger Angle α _ispecifically comprise the following steps:

Step a: calculate direct current I _dwith current-order amplitude limit value I _olimbetween current deviation and amplify, the current deviation I be amplified _diff, distinguish rectification side and inverter side, select current margins by the 6th selector, make both sides keep the current margins of 0.1pu, I _diffbe expressed as:

Wherein, Gain is multiplication factor;

Step b:I _diffthrough proportional branch, obtain α _iproportional component α _i_ P, specifically has:

Wherein, K _pifor proportional gain, for current trigger angle α _iprevious step calculated value, for comparative example gain K _pIcarry out the modifying factor revised; The angle [alpha] adopted in extra-high voltage project _pcofor the calculating angle of valve control system, here for the feature of electromechanical transient, Practical Project is controlled to the equivalence be similar to, adopt approximate angle

I _diffsimultaneously through integration branch road, obtain α _iquadrature components α _i_ I, specifically has:

${\mathrm{\&alpha;}}_i\_I=\frac{1}{T_{\mathrm{ii}}}\underset{{\mathrm{\&alpha;}}_{i\min }}{\overset{{\mathrm{\&alpha;}}_{i\max }}{\&Integral;}}{I}_{\mathrm{diff}}\mathrm{dt}---\left(7\right)$

Wherein, T _iiintegration time constant, α _imaxfor current trigger angle higher limit, α _iminfor current trigger angle lower limit;

α _i_ P and α _iafter _ I is added, through amplitude limit again, (amplitude limit value is still α _imaxwith α _imin), obtain current trigger angle α _i, have:

${\mathrm{\&alpha;}}_i=\left\{\begin{array}{cc}{\mathrm{\&alpha;}}_{i\max }& {\mathrm{\&alpha;}}_i\_P+{\mathrm{\&alpha;}}_i\_I>{\mathrm{\&alpha;}}_{i\max }\\ {\mathrm{\&alpha;}}_i\_P+{\mathrm{\&alpha;}}_i\_I& {\mathrm{\&alpha;}}_{i\max }\&le;{\mathrm{\&alpha;}}_i\_P+{\mathrm{\&alpha;}}_i\_I\&le;{\mathrm{\&alpha;}}_{i\max }\\ {\mathrm{\&alpha;}}_{i\min }& {\mathrm{\&alpha;}}_i\_P+{\mathrm{\&alpha;}}_i\_I<{\mathrm{\&alpha;}}_{i\min }\end{array}\right.---\left(8\right).$

Current trigger angle higher limit α _imaxjointly determined by voltage control module, commutation failure PREDICTIVE CONTROL module, gamma kick module, and select to be positioned at rectification side or inverter side by first selector;

In rectification side, described commutation failure PREDICTIVE CONTROL module exports commutation margin angle Δ α, is exported through revised maximum Trigger Angle α ' by gamma kick module _max, this α ' _maxbe current trigger angle higher limit α _imax;

In inverter side, α ' _maxinput to described voltage control module, the voltage triggered angle α that voltage control module exports _vbe current trigger angle higher limit α _imax.

As Fig. 5, voltage control module output voltage Trigger Angle α _v, specifically comprise the following steps:

Step a: distinguish rectification side and inverter side, calculates direct voltage U by the 7th selector, the 8th selector and the 9th selector _dwith direct voltage reference value U _drefbetween current deviation U _diff, have:

Wherein, Δ U _drwith Δ U _dibe respectively rectification side and inverter side voltage instruction nargin, R is the resistance of DC line;

Step b: enter proportional plus integral control and amplitude limit subsequently, output voltage Trigger Angle α _v, specifically have:

${\mathrm{\&alpha;}}_v=\left\{\begin{array}{cc}{\mathrm{\&alpha;}}_{\max }^{\&prime;}& K_{\mathrm{pv}}\&times;U_{\mathrm{diff}}+\frac{1}{T_{\mathrm{iv}}}\stackrel{{\mathrm{\&alpha;}}_{\max }^{\&prime;}}{\&Integral;}{U}_{\mathrm{diff}}\mathrm{dt}>{\mathrm{\&alpha;}}_{\max }^{\&prime;}\\ K_{\mathrm{pv}}\&times;U_{\mathrm{diff}}+\frac{1}{T_{\mathrm{iv}}}\stackrel{{\mathrm{\&alpha;}}_{\max }^{\&prime;}}{\&Integral;}{U}_{\mathrm{diff}}\mathrm{dt}& K_{\mathrm{pv}}\&times;U_{\mathrm{diff}}+\frac{1}{T_{\mathrm{iv}}}\stackrel{{\mathrm{\&alpha;}}_{\max }^{\&prime;}}{\&Integral;}{U}_{\mathrm{diff}}\mathrm{dt}\&le;{\mathrm{\&alpha;}}_{\max }^{\&prime;}\end{array}\right.---\left(10\right)$

Wherein, K _pvfor proportional gain, T _ivfor integration time constant, α ' _maxfor the revised maximum Trigger Angle that extinguish angle prediction module exports.

The setting of voltage control module is divided into total head and step-down two kinds of situations.When total head is run, at the Voltage Reference basic value 800kV of rectification side, also must provide larger voltage margin Δ U _dr=80kV; At the Voltage Reference basic value 800-I of inverter side _d× R, I _dthe calculating pressure drop of circuit with the product representation of R, still must provide voltage margin Δ U _i=7.25kV.During brownout operation, for 70% step-down, rectification side Voltage Reference basic value 560kV, voltage margin Δ U _r=56kV; Inverter side Voltage Reference basic value 800-I _d× R, without the need to voltage margin.The object arranging voltage margin is the effect making voltage control link total head situation only play restriction overvoltage of direct current.

As Fig. 6, described gamma kick module exports maximum Trigger Angle α _max, α _maxbe expressed as:

Wherein, γ _reffor extinguish angle reference value, d _xfor commutating reactance, U _di0for ideal no-load direct voltage;

Δ α=0 during normal operation, its computational methods are see commutation failure prediction module.Inverter side converter is according to calculated α _maxduring operation, think and extinguish angle can be kept to equal reference value.Control block diagram as shown in Figure 6.Through the dynamic corrections of volt-ampere characteristic slope, revised maximum Trigger Angle α ' _max:

Wherein, k is modified gain.During direct current dynamic change, the volt-ampere curve of gamma kick is converted into positive slope by the negative slope before revising, and promotes the stability of DC operation.On the basis of (11), a component α relevant to valve detection angulation also will be deducted in Engineering Control _sub, simplify in this model, will not consider.

Commutation failure PREDICTIVE CONTROL module realizes the generation judging commutation failure when inverter side AC fault, reduces its risk.It only starts when inverter side change of current busbar voltage is landed, and calculates commutation margin angle Δ α, acts on gamma kick module and make α _maxcorresponding reduction Δ α, the function realize shortening the commutation failure time, reducing commutation failure risk, control block diagram as shown in Figure 7.Calculate according to change of current bus phase voltage instantaneous value during Practical Project controls, this model has carried out equivalence to working control, adopts U _accalculate.Described commutation failure PREDICTIVE CONTROL module exports commutation margin angle Δ α by the 12 selector, has:

$\left\{\begin{array}{cc}\mathrm{\&Delta;\&alpha;}=0& U_{\mathrm{ac}0}-U_{\mathrm{ac}}\&le;1-K_{\mathrm{cf}}\\ \mathrm{\&Delta;\&alpha;}=\arccos (1-G_{\mathrm{cf}}\&times;(U_{\mathrm{ac}0}-U_{\mathrm{ac}}))& U_{\mathrm{ac}0}-U_{\mathrm{ac}}>1-K_{\mathrm{cf}}\end{array}\right.---\left(13\right)$

Wherein, U _ac0for initial steady state ac bus positive sequence voltage, U _acfor actual ac bus positive sequence voltage, K _cffor commutation failure voltage threshold, G _cffor commutation failure voltage gain;

During normal operation, Δ α=0; When fault occurs, if Voltage Drop amplitude exceedes the commutation failure voltage threshold K of setting _cf, calculate commutation margin angle Δ α by (12); If voltage resume is to normal value after fault clearance, then elapsed time constant is T _dncffirstorder filter, represents that Δ α drops to zero according to given pace.Owing to having carried out equivalence, parameter K _cf, G _cfneed by test method, determine with working control curve comparison.

Current trigger angle lower limit α _iminjointly determined by voltage control module, rectification side minimum trigger angle control module, voltage resume control module and third selector, and select to be positioned at rectification side or inverter side by second selector;

In rectification side, rectification side minimum trigger angle control module exports minimum trigger angle α _min, itself and voltage triggered angle α _v, the minimum angle constant of rectification side gets maximum, this maximum is current trigger angle lower limit α _imin;

In inverter side, voltage resume control module output voltage accelerates mark, and this voltage accelerates mark and inputs to third selector, when voltage accelerates to indicate and starts, and current trigger angle lower limit α _iminequal voltage triggered angle α _v, otherwise equal the minimum angle constant of inverter side.

Rectification side minimum trigger angle control module realizes the Trigger Angle minimum value at rectification side AC fault limit converter.It only starts when rectification side change of current busbar voltage is landed, and is forced by the Trigger Angle of rectification side Current Control link to export angle [alpha] setting in it _min, control block diagram as shown in Figure 8.Calculate according to change of current bus phase voltage instantaneous value during Practical Project controls, working control has been carried out equivalence by this model, adopts U _accalculate.Rectification side minimum trigger angle control module exports minimum trigger angle α _minspecifically comprise following situation:

(1) when normally running, actual ac bus positive sequence voltage U _achigher than the ac bus positive sequence voltage first order threshold k preset ₁with second level threshold k ₂, and K ₁<K ₂, determine α by the tenth selector _min=0;

(2) when fault occurs, U _aclower than first order threshold k ₁, then α is determined by the tenth selector _min=C _dl, wherein C _dlfor first order minimum trigger angle;

(3) if U _accontinue to be reduced to and be less than second level threshold k ₂, then α is determined by the 11 selector _min=D _l, wherein D _lfor second level minimum trigger angle;

(4) if U after fault clearance _acreturn to higher than first order threshold k ₁, then by α _minfrom C _dlwith fixed rate D _ecrdrop to zero gradually.Owing to having carried out equivalence, therefore K ₁and K ₂need by test method, determine with working control curve comparison.

The voltage that voltage resume control module realizes in transient process adds quick-recovery, and control block diagram as shown in Figure 9.If direct voltage is lower than 0.6pu and exceed low-voltage time delay T ₁, then voltage resume control module starts, and voltage resume control module output voltage accelerates mark URC_ON, makes URC_ON put 1, shows to force inverter side current trigger angle to be the voltage triggered angle α that voltage control module exports _v, to promote the resume speed of direct voltage;

If direct voltage returns to more than 0.7pu, then voltage resume control module exits, and the minimum angle constant of inverter side is selected at the current trigger angle of inverter side.Consider the feature of electromechanical transient simulation fault setting, this model have ignored the function of the longest effective time that voltage resume controls in working control.

The minimum angle constant of described rectification side gets 5 °, and the minimum angle constant of described inverter side gets 110 °.

Described restart control module export restart Trigger Angle α _rewith current trigger angle α _itrigger Angle command value α is obtained by selecting module _ord, described selection module is the 4th selector.

Described restart control module export restart Trigger Angle α _respecifically comprise the following steps:

Step a: judge system whether because the short trouble of DC line enters the state of restarting according to criterion, if condition meets, what enter step b restarts control; Criterion is as follows:

I _dr-I _di＞K _res (14)

Wherein, I _drfor rectification side direct current, I _difor inverter side direct current, K _resfor the difference between current threshold value between rectification side and inverter side;

Step b: restart control detailed process as follows:

1) Trigger Angle α will be restarted _resetting in 164 °, restart number counter and add up;

2) if restart number counter number of times more than 3 times, then block signal is sent; If be no more than 3 times, α _rekeep α after 164 ° of state continuance 0.15s _re35ms is kept again setting in 60 °;

3) again judge system mode according to criterion, if still meet criterion, then repeat to restart control.

The present invention has carried out equivalence to the control logic of Practical Project, namely judges system mode according to both sides direct current difference, and only detects this side direct current in Engineering Control, according to the rate of change size failure judgement of electric current, and therefore parameter K _resneed determine according to actual curve.

Extra-high voltage direct-current control system provided by the invention is used for Electrical-Machanical Transient Simulation of Power System and calculates, and main feature is the control characteristic that can reflect Practical Project, and accuracy of simulation is high.This feature needs to carry out contrasting to prove with Practical Project controlling curve, in fairly large electrical network, is limited to simulation velocity, cannot verifies this feature of the present invention, therefore below by way of a simple embodiment, key property of the present invention is described.

For Hami-Zhengzhou ± 800kV DC transmission system, system main electrical scheme as shown in Figure 10.The two 12 pulse conversion device wiring of direct current system one pole, adopt Ground return operational mode, and AC system adopts the circuit of ideal voltage source series system equivalent impedance to represent.Breathe out Zheng's direct current system steady-state load flow as table 1:

Table 1

Direct current transmission power	Direct voltage	Direct current	α angle (rectification side)	γ angle (inverter side)
					4000MW	800kV	5kA	15°	17°

Respectively Practical Project controller and control system model provided by the invention being accessed this system to emulate, compare three type systematic disturbances---under rectification side change of current bus three-phase shortcircuit, inverter side change of current bus three-phase shortcircuit, DC side line short, two kinds of simulation results are as follows.

1, the instantaneous three-phase shortcircuit of rectification side

Simulation curve contrast as shown in figure 11.Controlling model simulation curve provided by the invention and working control curves good.After rectification side fault occurs, direct current is decreased to zero, and direct voltage reduces, and current limiting low-voltage controls current instruction value to be limited to minimum value, and rectification side Current Control is motor current, exports Trigger Angle and will be decreased to minimum value 5 °; Subsequently, rectification side minimum trigger angle controls to start, by rectification side Trigger Angle setting in 30 ° of (C _dl=D _l=30 °), and be retained to fault always and terminate, alternating voltage recover normal after, control Trigger Angle is linearly declined with given pace, until delay time arrives, control is returned rectification side Current Control.Between age at failure, because direct current is little, inverter side will enter Current Control state by gamma kick and remain to direct current recovers normal level.

2, the instantaneous three-phase shortcircuit of inverter side

Simulation curve as shown in figure 12.Controlling model simulation curve provided by the invention and working control curves good.After inverter side breaks down, direct current increases, and direct voltage reduces, and current limiting low-voltage controls current instruction value to be limited to minimum value, and rectification side Current Control will increase Trigger Angle to control electric current; Inverter side commutation failure prediction link starts, and it exports angle and acts on gamma kick inverter side Trigger Angle is reduced instantaneously, and continues to fault always and terminate, and after alternating voltage recovers, controls Trigger Angle and returns to normal value with given pace.

3, DC side circuit instantaneous short-circuit

Simulation curve as shown in figure 13.Controlling model simulation curve provided by the invention and working control curves good.After DC line short circuit, rectification side direct current increases, and inverter side direct current reduces, and direct voltage drops to zero, after both sides current differential being detected, restart control to start immediately, Trigger Angle phase shift to 164 ° will be restarted, go the free time through 0.15s, Trigger Angle is placed in 60 °, now fault is removed, and direct current, voltage all recover normal level, and direct current is restarted successfully.

Can be seen by this example, DC control system model provided by the invention, fundamentally solve original model emulation accuracy not enough, the defect of Practical Project characteristic cannot be reflected, thus provide simulation means and technical support for the simulation calculation of AC-DC interconnecting power network.

Finally should be noted that: above embodiment is only in order to illustrate that technical scheme of the present invention is not intended to limit; those of ordinary skill in the field still can modify to the specific embodiment of the present invention with reference to above-described embodiment or equivalent replacement; these do not depart from any amendment of spirit and scope of the invention or equivalent replacement, are all applying within the claims of the present invention awaited the reply.

Claims (15)

1. be applicable to an extra-high voltage direct-current control system for electromechanical transient simulation, it is characterized in that: described system comprises current trigger angle output module, restarts control module and select module; Described current trigger angle output module and restart control module output current Trigger Angle and restart Trigger Angle respectively, described current trigger angle and restart Trigger Angle and obtain Trigger Angle command value by selection module.

2. the extra-high voltage direct-current control system being applicable to electromechanical transient simulation according to claim 1, is characterized in that: described current trigger angle output module comprises main control module, current limiting low-voltage control module and current control module; Described main control module output current command value I _o, I _ocurrent-order amplitude limit value I is obtained by current limiting low-voltage control module _olim, I _olimthrough current control module output current Trigger Angle α _i.

3. the extra-high voltage direct-current control system being applicable to electromechanical transient simulation according to claim 2, is characterized in that: in described main control module, runs on firm power control model or constant current control model by the 5th selector certainty annuity; Described 5th selector output current instruction operation value I _op, then through current-order compensatory control, by I _opwith direct current I _ddeviation carry out as compensation rate after integration, with I _opbe added and obtain final current instruction value I _o, have:

Wherein, I _ndirect current rated value;

Current-order runtime value I _opdetermination be divided into following two kinds of situations:

(1) as the switching value Mode=1 of the 5th selector, system cloud gray model in firm power control model, direct voltage U _dfirst pass through the firstorder filter with lower amplitude limit, the time constant filter of this firstorder filter is T ₀, lower amplitude limit is U _dmin, the direct voltage U after firstorder filter output filtering _dfilt, current-order runtime value I _opfor:

Wherein, P _reffor set direct current power reference value;

(2) as the switching value Mode=0 of the 5th selector, system cloud gray model in constant current control model, current-order runtime value I _opfor:

I _op＝I _ref (3)

In formula: I _reffor set current-order reference value.

4. the extra-high voltage direct-current control system being applicable to electromechanical transient simulation according to claim 2, is characterized in that: in described current limiting low-voltage control module, direct voltage U _dfirst through firstorder filter with filtering high dither, the time constant filter T of this firstorder filter is adjustable, if U _dfor ascendant trend, T gets filtering time rising constant T _upif, U _dfor downward trend, T gets filtering time decline constant T _dn; Again according to the direct voltage U that this firstorder filter exports _df, according to interpolation calculation current-order amplitude limit value I _olim, have:

Wherein, I _ofor the current instruction value that current instruction value output module exports, I _ominfor set minimum current command value,

U _dhighfor the starting resistor of current limiting low-voltage control module, U _dlowvoltage is exited for current limiting low-voltage control module.

5. the extra-high voltage direct-current control system being applicable to electromechanical transient simulation according to claim 2, is characterized in that: described current control module output current Trigger Angle α _ispecifically comprise the following steps:

Step a: calculate direct current I _dwith current-order amplitude limit value I _olimbetween current deviation and amplify, the current deviation I be amplified _diff, distinguish rectification side and inverter side, select current margins by the 6th selector, make both sides keep the current margins of 0.1pu, I _diffbe expressed as:

Wherein, Gain is multiplication factor;

Step b:I _diffthrough proportional branch, obtain α _iproportional component α _i_ P, specifically has:

Wherein, K _pifor proportional gain, for current trigger angle α _iprevious step calculated value, sin15 °/ for comparative example gain K _pIcarry out the modifying factor revised;

I _diffsimultaneously through integration branch road, obtain α _iquadrature components α _i_ I, specifically has:

Wherein, T _iiintegration time constant, α _imaxfor current trigger angle higher limit, α _iminfor current trigger angle lower limit;

α _i_ P and α _ithrough amplitude limit again after _ I is added, obtain current trigger angle α _i, have:

6. the extra-high voltage direct-current control system being applicable to electromechanical transient simulation according to claim 5, is characterized in that: current trigger angle higher limit α _imaxjointly determined by voltage control module, commutation failure PREDICTIVE CONTROL module, gamma kick module, and select to be positioned at rectification side or inverter side by first selector;

In rectification side, described commutation failure PREDICTIVE CONTROL module exports commutation margin angle Δ α, is exported through revised maximum Trigger Angle α ' by gamma kick module _max, this α ' _maxbe current trigger angle higher limit α _imax;

In inverter side, α ' _maxinput to described voltage control module, the voltage triggered angle α that voltage control module exports _vbe current trigger angle higher limit α _imax.

7. the extra-high voltage direct-current control system being applicable to electromechanical transient simulation according to claim 6, is characterized in that: voltage control module output voltage Trigger Angle α _v, specifically comprise the following steps:

Step a: distinguish rectification side and inverter side, calculates direct voltage U by the 7th selector, the 8th selector and the 9th selector _dwith direct voltage reference value U _drefbetween current deviation U _diff, have:

Wherein, Δ U _drwith Δ U _dibe respectively rectification side and inverter side voltage instruction nargin, R is the resistance of DC line;

Step b: enter proportional plus integral control and amplitude limit subsequently, output voltage Trigger Angle α _v, specifically have:

Wherein, K _pvfor proportional gain, T _ivfor integration time constant, α ' _maxfor the revised maximum Trigger Angle that extinguish angle prediction module exports.

8. the extra-high voltage direct-current control system being applicable to electromechanical transient simulation according to claim 6, is characterized in that: described gamma kick module exports maximum Trigger Angle α _max, α _maxbe expressed as:

Wherein, γ _reffor extinguish angle reference value, d _xfor commutating reactance, U _di0for ideal no-load direct voltage;

Through the dynamic corrections of volt-ampere characteristic slope, revised maximum Trigger Angle α ' _max:

Wherein, k is modified gain.

9. the extra-high voltage direct-current control system being applicable to electromechanical transient simulation according to claim 6, is characterized in that: described commutation failure PREDICTIVE CONTROL module exports commutation margin angle Δ α by the 12 selector, has:

Wherein, U _ac0for initial steady state ac bus positive sequence voltage, U _acfor actual ac bus positive sequence voltage, K _cffor commutation failure voltage threshold, G _cffor commutation failure voltage gain;

During normal operation, Δ α=0; When fault occurs, if Voltage Drop amplitude exceedes the commutation failure voltage threshold K of setting _cf, calculate commutation margin angle Δ α by (12).

10. the extra-high voltage direct-current control system being applicable to electromechanical transient simulation according to claim 5, is characterized in that: current trigger angle lower limit α _iminjointly determined by voltage control module, rectification side minimum trigger angle control module, voltage resume control module and third selector, and select to be positioned at rectification side or inverter side by second selector;

In rectification side, rectification side minimum trigger angle control module exports minimum trigger angle α _min, itself and voltage triggered angle α _v, the minimum angle constant of rectification side gets maximum, this maximum is current trigger angle lower limit α _imin;

In inverter side, voltage resume control module output voltage accelerates mark, and this voltage accelerates mark and inputs to third selector, when voltage accelerates to indicate and starts, and current trigger angle lower limit α _iminequal voltage triggered angle α _v, otherwise equal the minimum angle constant of inverter side.

The 11. extra-high voltage direct-current control system being applicable to electromechanical transient simulation according to claim 10, is characterized in that: rectification side minimum trigger angle control module exports minimum trigger angle α _minspecifically comprise following situation:

(1) when normally running, actual ac bus positive sequence voltage U _achigher than the ac bus positive sequence voltage first order threshold k preset ₁with second level threshold k ₂, and K ₁<K ₂, determine α by the tenth selector _min=0;

(2) when fault occurs, U _aclower than first order threshold k ₁, then α is determined by the tenth selector _min=C _dl, wherein C _dlfor first order minimum trigger angle;

(3) if U _accontinue to be reduced to and be less than second level threshold k ₂, then α is determined by the 11 selector _min=D _l, wherein D _lfor second level minimum trigger angle;

(4) if U after fault clearance _acreturn to higher than first order threshold k ₁, then by α _minfrom C _dlwith fixed rate D _ecrdrop to zero gradually.

The 12. extra-high voltage direct-current control system being applicable to electromechanical transient simulation according to claim 10, is characterized in that: if direct voltage exceedes low-voltage time delay T lower than 0.6pu ₁, then voltage resume control module starts, and voltage resume control module output voltage accelerates mark URC_ON, makes URC_ON put 1, shows to force inverter side current trigger angle to be the voltage triggered angle α that voltage control module exports _v, to promote the resume speed of direct voltage;

If direct voltage returns to more than 0.7pu, then voltage resume control module exits, and the minimum angle constant of inverter side is selected at the current trigger angle of inverter side.

The 13. extra-high voltage direct-current control system being applicable to electromechanical transient simulation according to claim 10, it is characterized in that: the minimum angle constant of described rectification side gets 5 °, the minimum angle constant of described inverter side gets 110 °.

The 14. extra-high voltage direct-current control system being applicable to electromechanical transient simulation according to claim 1, is characterized in that: described in restart control module export restart Trigger Angle α _rewith current trigger angle α _itrigger Angle command value α is obtained by selecting module _ord, described selection module is the 4th selector.

The 15. extra-high voltage direct-current control system being applicable to electromechanical transient simulation according to claim 14, is characterized in that: described in restart control module export restart Trigger Angle α _respecifically comprise the following steps:

Step a: judge system whether because the short trouble of DC line enters the state of restarting according to criterion, if condition meets, what enter step b restarts control; Criterion is as follows:

I _dr-I _di＞K _res (14)

Wherein, I _drfor rectification side direct current, I _difor inverter side direct current, K _resfor the difference between current threshold value between rectification side and inverter side;

Step b: restart control detailed process as follows:

1) Trigger Angle α will be restarted _resetting in 164 °, restart number counter and add up;

2) if restart number counter number of times more than 3 times, then block signal is sent; If be no more than 3 times, α _rekeep α after 164 ° of state continuance 0.15s _re35ms is kept again setting in 60 °;

3) again judge system mode according to criterion, if still meet criterion, then repeat to restart control.