CN103543357B - A kind of pre-judging method of converter valve commutation failure - Google Patents

Abstract

The invention provides a kind of pre-judging method of converter valve commutation failure, comprise the following steps: calculate inverter side AC current-voltage amplitude perunit value and DC current perunit value; Calculate the Trigger Angle upper limit of inverter side converter valve; Whether anticipation there is commutation failure.The invention provides a kind of pre-judging method of converter valve commutation failure, accurately can judge the commutation failure caused by common causes such as inverter side fault in ac transmission system or straight-flow system overloads, for prevention commutation failure provides information.Swift with judgement, after fault occurs, about 1ms can obtain phase conversion failure judgment information, contributes to taking measures rapidly to prevent commutation failure.Accuracy of judgement, according to the Trigger Angle upper limit computing method that theory deduction obtains, the method accurately can judge the generation of commutation failure.

Description

A kind of pre-judging method of converter valve commutation failure

Technical field

The present invention relates to a kind of pre-judging method, be specifically related to a kind of pre-judging method of converter valve commutation failure.

Background technology

Power Electronic Technique have passed through the thyristor valve period of 70 ~ eighties of 20th century, makes direct current transportation obtain great development, and presents more advantages in bulk power grid is interconnected, and traditional pure AC network has developed into alternating current-direct current mixing electrical network; Adopt thyristor as commutation element normal grid commutation D.C. high voltage transmission (Line-Commutated-ConverterHighVoltageDirectCurrent, LCC-HVDC) with its Large Copacity long distance power transmission, active power fast the feature such as controlled worldwide obtain and develop fast.

The commutation failure (CommutationFailure, CF) of current conversion station and DC line fault are the comparatively common failure modes of straight-flow system.When grid collapses or severe three-phase asymmetric time, can cause ac bus voltage drop, line voltage zero-cross point may shift to an earlier date, and the commutation overlap angle of LCC-HVDC valve arm will increase, close the angle of rupture will reduce, likely cause commutation failure.The generation of commutation failure seriously limits straight-flow system through-put power, makes through-put power drop to suddenly very little value or even zero from normal value, for whole AC-DC-AC system brings huge disturbance.

Mainly there is ground connection or phase fault in inverter side, ac bus voltage reduces, DC current rises suddenly to cause the reason of commutation failure, in addition, and transistors breakdown and triggering system is abnormal also may cause commutation failure.

Abroad; the Control protection platform of the HVDC Transmission Technology device of same company is substantially all the mode adopting a kind of general character platform; require for dissimilar DC engineering and use corresponding Control protection module, and the Achtechture of its Control protection platform remains unchanged substantially.ABB, SIEMENS etc. can the complete company manufactured and designed direct-current power transmission control protection system as minority in the world, the Control protection system of domestic current employing also mainly adopts the scheme of above Liang Ge company, and the domestic weakness relatively to the control & protection strategy research during HVDC system failure; And the commutation failure pre-judging method that ABB proposes can only judge the generation of AC fault, can not judge that can this fault cause commutation failure.For first prevention commutation failure needs to carry out anticipation to commutation failure, therefore the pre-judging method of commutation failure becomes the primary research object of prevention commutation failure.

Summary of the invention

In order to overcome above-mentioned the deficiencies in the prior art, the invention provides a kind of pre-judging method of converter valve commutation failure, accurately can judge the commutation failure caused by common causes such as inverter side fault in ac transmission system or straight-flow system overloads, for prevention commutation failure provides information.

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

The invention provides a kind of pre-judging method of converter valve commutation failure, said method comprising the steps of:

Step 1: calculate inverter side AC current-voltage amplitude perunit value and DC current perunit value;

Step 2: the Trigger Angle upper limit calculating inverter side converter valve;

Step 3: whether anticipation commutation failure occurs.

In described step 1, described step 1 comprises the following steps:

Step 1-1: measure inverter side alternating current streamline voltage magnitude U _lwith the DC current instantaneous value I under condition of work _d;

Step 1-2: inverter side AC current-voltage amplitude perunit value and DC current perunit value are used respectively with represent, be expressed as:

$U_L^{*}=U_L/U_{\mathrm{LN}}---\left(1\right)$

$I_d^{*}=I_d/I_{\mathrm{dN}}---\left(2\right)$

Wherein, U _lNfor rated line voltage amplitude, I _dNfor rated DC current flow valuve.

Described step 2 comprises the following steps:

Step 2-1: calculate the commutation area needed for converter valve commutation under nominal working conditions;

Step 2-2: the commutation area under calculating current operating conditions needed for commutation;

Step 2-3: the Trigger Angle upper limit calculating inverter side converter valve.

In described step 2-1, by Universal Number order, u _bafor converter valve 1 is to the change of current voltage of converter valve 3 commutation, its expression formula is under nominal operating conditions:

u _ba(t)＝U _LNsin(ωt)（3）

Wherein, u _bat () is t, under nominal operating conditions, converter valve 1 is to the change of current voltage of converter valve 3 commutation; U _lNfor specified commutation voltage amplitude; ω is change of current voltage u _baangular frequency;

If the specified Trigger Angle of inverter side is α _n, the specified pass angle of rupture of inverter side is γ _n; Commutation start time, change of current voltage u _baphase place be α _n, commutation finish time, change of current voltage u _baphase place be π-γ _n;

So the commutation cartographic represenation of area needed for converter valve commutation under nominal working conditions is:

$A_N=\frac{1}{\mathrm{\ω}}{\∫}_{{\mathrm{\α}}_N}^{\mathrm{\π}-{\mathrm{\γ}}_N}{U}_{\mathrm{LN}}\sin \left(\mathrm{\ωt}\right)\mathrm{d\ωt}=\frac{1}{{\mathrm{\ω}}_N}{U}_{\mathrm{LN}}[\cos {\mathrm{\α}}_N+\cos {\mathrm{\γ}}_N]---\left(4\right)$

Wherein, A _nfor the commutation area needed for the converter valve commutation under nominal working conditions.

In described step 2-2, the commutation cartographic represenation of area under current operating conditions needed for commutation is:

$\frac{A_f}{A_N}=\frac{I_d}{I_{\mathrm{dN}}}---\left(5\right)$

Wherein, A _ffor the commutation area under current operating conditions needed for commutation; I _dfor the DC current under current operating conditions; I _dNfor the DC current under nominal working conditions;

In conjunction with (4) and (5), can obtain:

$A_f=\frac{I_d}{I_{\mathrm{dN}}}\·\frac{1}{\mathrm{\ω}}{U}_{\mathrm{LN}}(\cos {\mathrm{\α}}_N+\cos {\mathrm{\γ}}_N)---\left(6\right)$

In described step 2-3, due under current operating conditions, commutation voltage can fluctuate, and the Trigger Angle of inverter side converter valve reaches Trigger Angle upper limit α _limittime, the pass angle of rupture is γ ₀, then, after commutation voltage fluctuates, commutation voltage amplitude is by U _lNbecome U _l, the commutation area needed for commutation is:

$A_f^{\text{'}}=\frac{1}{\mathrm{\ω}}{\∫}_{{\mathrm{\α}}_{\mathrm{limit}}}^{\mathrm{\π}-{\mathrm{\γ}}_0}{U}_L\sin \left(\mathrm{\ωt}\right)\mathrm{d\ωt}=\frac{1}{\mathrm{\ω}}{U}_L(\cos {\mathrm{\α}}_{\mathrm{limit}}+\cos {\mathrm{\γ}}_0)---\left(7\right)$

Wherein, A ' _fafter commutation voltage fluctuates, the commutation area under current operating conditions needed for commutation;

In conjunction with (6) and (7), can obtain:

${\mathrm{\α}}_{\mathrm{limit}}=\arccos [\frac{U_{\mathrm{LN}}}{U_L}\·\frac{I_d}{I_{\mathrm{dN}}}(\cos {\mathrm{\α}}_N+\cos {\mathrm{\γ}}_N)-\cos {\mathrm{\γ}}_0]---\left(8\right)$

In described step 3, whether the Trigger Angle exported by the Control protection system comparing converter valve and the Trigger Angle upper limit of inverter side converter valve, anticipation can there is commutation failure; The Trigger Angle that Control protection system exports represents with α, and deterministic process is specially:

A) if α < is α _limit, then can judge that commutation failure does not occur converter valve;

B) if α > is α _limit, cause the pass angle of rupture γ of converter valve to be less than the minimum turn-off angle γ of converter valve ₀, and then cause converter valve generation commutation failure.

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

1. swift with judgement, after fault occurs, about 1ms can obtain phase conversion failure judgment information, contributes to taking measures rapidly to prevent commutation failure.

2. accuracy of judgement, according to the Trigger Angle upper limit computing method that theory deduction obtains, the method accurately can judge the generation of commutation failure.

3. accurately can judge the commutation failure caused by common causes such as inverter side fault in ac transmission system or straight-flow system overloads, for prevention commutation failure provides information.

Accompanying drawing explanation

Fig. 1 is the pre-judging method process flow diagram of converter valve commutation failure;

Fig. 2 is two-phase commutation equivalent circuit schematic diagram;

Fig. 3 is commutation voltage u _bawaveform and converter valve 1 are to converter valve 3 commutation process schematic diagram;

Fig. 4 is when t=2.0s breaks down, Trigger Angle instruction and Trigger Angle upper limit α _limitoscillogram.

Embodiment

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

As Fig. 1, the invention provides a kind of pre-judging method of converter valve commutation failure, said method comprising the steps of:

Step 1: calculate inverter side AC current-voltage amplitude perunit value and DC current perunit value;

Step 2: the Trigger Angle upper limit calculating inverter side converter valve;

Step 3: whether anticipation commutation failure occurs.

In described step 1, described step 1 comprises the following steps:

Step 1-1: measure inverter side alternating current streamline voltage magnitude U _lwith the DC current instantaneous value I under condition of work _d;

Step 1-2: inverter side AC current-voltage amplitude perunit value and DC current perunit value are used respectively with represent, be expressed as:

$U_L^{*}=U_L/U_{\mathrm{LN}}---\left(1\right)$

$I_d^{*}=I_d/I_{\mathrm{dN}}---\left(2\right)$

Wherein, U _lNfor rated line voltage amplitude, I _dNfor rated DC current flow valuve.

As Fig. 2, it is two-phase commutation equivalent circuit diagram.If t ₁for commutation start time, t ₂for commutation finish time, so at t ∈ [t ₁, t ₂] time, the current relationship before and after by the voltage relationship on change of current inductance and commutation in converter valve, has wherein: L _rfor change of current inductance, I _dfor DC current, u ' _bat top-stitching voltage that () is AB two-phase, A is commutation area.

Definition commutation voltage be commutation voltage time and area (hereinafter referred to as commutation area, being designated as A) to the integration of time, the commutation area A described needed for commutation process is a fixed value, and commutation area A and DC current proportional.The size of commutation area A determines the speed of commutation process, also determines the size of angle of overlap μ.

In described step 2, when Trigger Angle increases, closing the angle of rupture can reduce thereupon; Minimum turn-off angle γ is equaled when Trigger Angle increases to the pass angle of rupture ₀time, if continue to increase Trigger Angle, then will cause closing the angle of rupture and be less than minimum turn-off angle γ ₀, and then cause commutation failure.Therefore, the pass angle of rupture is made to equal minimum turn-off angle γ ₀trigger Angle be the maximum Trigger Angle that can not cause commutation failure, (be designated as α referred to herein as the Trigger Angle upper limit _limit).Specifically comprise the following steps:

Step 2-1: calculate the commutation area needed for converter valve commutation under nominal working conditions;

Step 2-2: the commutation area under calculating current operating conditions needed for commutation;

Step 2-3: the Trigger Angle upper limit calculating inverter side converter valve.

In described step 2-1, with inverter side commutation voltage u _bawaveform and converter valve 1 to the commutation process of converter valve 3 commutation, nominal working conditions are described under commutation area A _ncomputing method.Suppose commutation voltage u _bawaveform is standard sine waveform, and angular frequency does not change, inverter side commutation voltage u _bawaveform as shown in Figure 3, by Universal Number order, u _bafor converter valve 1 is to the change of current voltage of converter valve 3 commutation, its expression formula is under nominal operating conditions:

u _ba(t)＝U _LNsin(ωt)（3）

Wherein, u _bat () is t, under nominal operating conditions, converter valve 1 is to the change of current voltage of converter valve 3 commutation; U _lNfor specified commutation voltage amplitude; ω is change of current voltage u _baangular frequency;

If the specified Trigger Angle of inverter side is α _n, the specified pass angle of rupture of inverter side is γ _n; Commutation start time, change of current voltage u _baphase place be α _n, commutation finish time, change of current voltage u _baphase place be π-γ _n;

So the commutation cartographic represenation of area needed for converter valve commutation under nominal working conditions is:

$A_N=\frac{1}{\mathrm{\&omega;}}{\&Integral;}_{{\mathrm{\&alpha;}}_N}^{\mathrm{\&pi;}-{\mathrm{\&gamma;}}_N}{U}_{\mathrm{LN}}\sin \left(\mathrm{\&omega;t}\right)\mathrm{d\&omega;t}=\frac{1}{{\mathrm{\&omega;}}_N}{U}_{\mathrm{LN}}[\cos {\mathrm{\&alpha;}}_N+\cos {\mathrm{\&gamma;}}_N]---\left(4\right)$

Wherein, A _nfor the commutation area needed for the converter valve commutation under nominal working conditions.

In described step 2-2, the commutation cartographic represenation of area under current operating conditions needed for commutation is:

$\frac{A_f}{A_N}=\frac{I_d}{I_{\mathrm{dN}}}---\left(5\right)$

Wherein, A _ffor the commutation area under current operating conditions needed for commutation; I _dfor the DC current under current operating conditions; I _dNfor the DC current under nominal working conditions;

In conjunction with (4) and (5), can obtain:

$A_f=\frac{I_d}{I_{\mathrm{dN}}}\&CenterDot;\frac{1}{\mathrm{\&omega;}}{U}_{\mathrm{LN}}(\cos {\mathrm{\&alpha;}}_N+\cos {\mathrm{\&gamma;}}_N)---\left(6\right)$

In described step 2-3, due under current operating conditions, commutation voltage can fluctuate, and the Trigger Angle of inverter side converter valve reaches Trigger Angle upper limit α _limittime, the pass angle of rupture is γ ₀, then, after commutation voltage fluctuates, commutation voltage amplitude is by U _lNbecome U _l, the commutation area needed for commutation is:

$A_f^{\text{'}}=\frac{1}{\mathrm{\&omega;}}{\&Integral;}_{{\mathrm{\&alpha;}}_{\mathrm{limit}}}^{\mathrm{\&pi;}-{\mathrm{\&gamma;}}_0}{U}_L\sin \left(\mathrm{\&omega;t}\right)\mathrm{d\&omega;t}=\frac{1}{\mathrm{\&omega;}}{U}_L(\cos {\mathrm{\&alpha;}}_{\mathrm{limit}}+\cos {\mathrm{\&gamma;}}_0)---\left(7\right)$

Wherein, A ' _fafter commutation voltage fluctuates, the commutation area under current operating conditions needed for commutation;

In conjunction with (6) and (7), can obtain:

${\mathrm{\&alpha;}}_{\mathrm{limit}}=\arccos [\frac{U_{\mathrm{LN}}}{U_L}\&CenterDot;\frac{I_d}{I_{\mathrm{dN}}}(\cos {\mathrm{\&alpha;}}_N+\cos {\mathrm{\&gamma;}}_N)-\cos {\mathrm{\&gamma;}}_0]---\left(8\right)$

In described step 3, whether the Trigger Angle exported by the Control protection system comparing converter valve and the Trigger Angle upper limit of inverter side converter valve, anticipation can there is commutation failure; The Trigger Angle that Control protection system exports represents with α, and deterministic process is specially:

A) if α < is α _limit, then can judge that commutation failure does not occur converter valve;

B) if α > is α _limit, cause the pass angle of rupture γ of converter valve to be less than the minimum turn-off angle γ of converter valve ₀, and then cause converter valve generation commutation failure.

When Fig. 4 is 2.0s generation AC fault, the Trigger Angle upper limit and Control protection system Trigger Angle instructional waveform.After fault occurs, about 1ms can judge the generation of commutation failure, obtains anticipation result.

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, although with reference to above-described embodiment to invention has been detailed description, those of ordinary skill in the field are to be understood that: still can modify to the specific embodiment of the present invention or equivalent replacement, and not departing from any amendment of spirit and scope of the invention or equivalent replacement, it all should be encompassed in the middle of right of the present invention.

Claims (4)

1. a pre-judging method for converter valve commutation failure, is characterized in that: said method comprising the steps of:

Step 1: calculate inverter side AC current-voltage amplitude perunit value and DC current perunit value;

Step 2: the Trigger Angle upper limit calculating inverter side converter valve;

Step 3: whether anticipation commutation failure occurs;

In described step 1, described step 1 comprises the following steps:

Step 1 ?1: measure inverter side alternating current streamline voltage magnitude U _lwith the DC current instantaneous value I under condition of work _d;

Step 1 ?2: inverter side AC current-voltage amplitude perunit value and DC current perunit value are used respectively with represent, be expressed as:

$U_L^{*}=U_L/U_{LN}---\left(1\right)$

$I_d^{*}=I_d/I_{dN}---\left(2\right)$

Wherein, U _lNfor rated line voltage amplitude, I _dNfor rated DC current flow valuve;

Described step 2 comprises the following steps:

Step 2 ?1: calculate the commutation area needed for converter valve commutation under nominal working conditions;

Step 2 ?2: calculate the commutation area needed for commutation under current operating conditions;

Step 2 ?3: the Trigger Angle upper limit calculating inverter side converter valve;

Described step 2 ?in 1, by Universal Number order, u _bafor converter valve 1 is to the change of current voltage of converter valve 3 commutation, its expression formula is under nominal operating conditions:

u _ba(t)＝U _LNsin(ωt)(3)

Wherein, u _bat () is t, under nominal operating conditions, converter valve 1 is to the change of current voltage of converter valve 3 commutation; U _lNfor specified commutation voltage amplitude; ω is change of current voltage u _baangular frequency;

If the specified Trigger Angle of inverter side is α _n, the specified pass angle of rupture of inverter side is γ _n; Commutation start time, change of current voltage u _baphase place be α _n, commutation finish time, change of current voltage u _baphase place be π-γ _n;

So the commutation cartographic represenation of area needed for converter valve commutation under nominal working conditions is:

$A_N=\frac{1}{\mathrm{\&omega;}}{\&Integral;}_{{\mathrm{\&alpha;}}_N}^{\mathrm{\&pi;}-{\mathrm{\&gamma;}}_N}{U}_{LN}sin\left(\mathrm{\&omega;}t\right)d\mathrm{\&omega;}t=\frac{1}{\mathrm{\&omega;}}{U}_{LN}\&lsqb;{\mathrm{cos\&alpha;}}_N+{\mathrm{cos\&gamma;}}_N\&rsqb;---\left(4\right)$

Wherein, A _nfor the commutation area needed for the converter valve commutation under nominal working conditions.

2. the pre-judging method of converter valve commutation failure according to claim 1, is characterized in that: described step 2 ?in 2, the commutation cartographic represenation of area under current operating conditions needed for commutation is:

$A_f=\frac{I_d}{I_{dN}}{A}_N---\left(5\right)$

Wherein, A _ffor the commutation area under current operating conditions needed for commutation; I _dfor the DC current under current operating conditions; I _dNfor the DC current under nominal working conditions;

In conjunction with (4) and (5), can obtain:

$A_f=\frac{I_d}{I_{dN}}\&CenterDot;\frac{1}{\mathrm{\&omega;}}{U}_{LN}({\mathrm{cos\&alpha;}}_N+{\mathrm{cos\&gamma;}}_N)---\left(6\right).$

3. the pre-judging method of converter valve commutation failure according to claim 2, is characterized in that: described step 2 ?in 3, due under current operating conditions, commutation voltage can fluctuate, and the Trigger Angle of inverter side converter valve reaches Trigger Angle upper limit α _limittime, the pass angle of rupture is γ ₀, then, after commutation voltage fluctuates, commutation voltage amplitude is by U _lNbecome U _l, the commutation area needed for commutation is:

$A_f^{\&prime;}=\frac{1}{\mathrm{\&omega;}}{\&Integral;}_{{\mathrm{\&alpha;}}_{\lim it}}^{\mathrm{\&pi;}-{\mathrm{\&gamma;}}_0}{U}_{L}sin\left(\mathrm{\&omega;}t\right)d\mathrm{\&omega;}t=\frac{1}{\mathrm{\&omega;}}{U}_L({\mathrm{cos\&alpha;}}_{\lim it}+{\mathrm{cos\&gamma;}}_0)---\left(7\right)$

Wherein, A ' _fafter commutation voltage fluctuates, the commutation area under current operating conditions needed for commutation;

In conjunction with (6) and (7), can obtain:

${\mathrm{\&alpha;}}_{\lim it}=arccos\&lsqb;\frac{U_{LN}}{U_L}\&CenterDot;\frac{I_d}{I_{dN}}({\mathrm{cos\&alpha;}}_N+{\mathrm{cos\&gamma;}}_N)-{\mathrm{cos\&gamma;}}_0\&rsqb;---\left(8\right).$

4. the pre-judging method of converter valve commutation failure according to claim 1, it is characterized in that: in described step 3, whether the Trigger Angle exported by the Control protection system comparing converter valve and the Trigger Angle upper limit of inverter side converter valve, anticipation can there is commutation failure; The Trigger Angle that Control protection system exports represents with α, and deterministic process is specially:

A) if α < is α _limit, then can judge that commutation failure does not occur converter valve;

B) if α > is α _limit, cause the pass angle of rupture γ of converter valve to be less than the minimum turn-off angle γ of converter valve ₀, and then cause converter valve generation commutation failure.