CN103543357A - Method for prejudging phase change failure of converter valve - Google Patents

Abstract

The invention provides a method for prejudging phase change failure of a converter valve. The method includes the steps of calculating an inverter side alternating current voltage amplitude per unit value and a direct current per unit value, calculating a fire angle upper limit of the converter valve on the inverter side and prejudging whether phase change is failed. According to the method for prejudging the phase change failure of the converter valve, phase change failure caused by inverter side alternating current system failure or direct current system overloading and other common reasons can be accurately judged, and information is provided for preventing the phase change failure. Judgment can be carried out quickly, phase change failure judgment information can be obtained in 1ms after the failure occurs, and measures can be quickly taken to prevent the phase change failure. Judgment is accurate, the calculation method of the fire angle upper limit is obtained through theoretical deduction, and the phase change failure can be accurately judged through the method.

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 has been passed through the thyristor valve period of 70～eighties of 20th century, makes direct current transportation obtain great development, and is representing more advantages aspect large Power System Interconnection, and traditional pure AC network has developed into alternating current-direct current mixing electrical network; Adopt thyristor as the conventional electrical network commutation D.C. high voltage transmission (Line-Commutated-Converter High Voltage Direct Current, LCC-HVDC) of commutation element with its large capacity long distance power transmission, active power fast the feature such as controlled worldwide obtained development fast.

The commutation failure of current conversion station (Commutation Failure, CF) and DC line fault are the comparatively common failure modes of straight-flow system.When electrical network breaks down or when severe three-phase is asymmetric, 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, and closing the angle of rupture will reduce, and likely cause commutation failure.The generation of commutation failure has seriously limited 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.

The reason that causes commutation failure is mainly that inversion side ground connection or phase fault, ac bus lower voltage, DC current occur rises suddenly etc., and in addition, transistors breakdown and triggering system extremely also may cause commutation failure.

Abroad; the control protecting platform of the HVDC Transmission Technology device of same company is substantially all the mode that adopts a kind of general character platform; for dissimilar DC engineering, require and use the corresponding protection module of controlling, and its Achtechture of controlling protecting platform remains unchanged substantially.ABB, SIEMENS etc. are as minority can completely manufacture and design direct-current power transmission control protection system in the world company, the control protection system of domestic current employing also mainly adopts the scheme of above Liang Ge company, and a little less than the relative thin of domestic control & protection strategy research during to the HVDC system failure; And can the commutation failure pre-judging method that ABB proposes can only be judged the generation of AC fault, can not judge this fault and cause commutation failure.For first prevention commutation failure needs commutation failure to carry out anticipation, so 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, can accurately judge the commutation failure being caused by common causes such as inversion 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 pre-judging method that the invention provides a kind of converter valve commutation failure, said method comprising the steps of:

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

Step 2: the Trigger Angle upper limit of calculating inversion 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 inversion side alternating current line voltage magnitude U _lwith the DC current instantaneous value I under condition of work _d;

Step 1-2: inversion 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 required commutation area of converter valve commutation under nominal working conditions;

Step 2-2: calculate the required commutation area of commutation under work at present condition;

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

In described step 2-1, by general number order, u _bafor the change of current voltage of converter valve 1 to converter valve 3 commutations, its expression formula under nominal working conditions is:

u _ba(t)＝U _LNsin(ωt) （3）

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

If the specified Trigger Angle of inversion side is α _n, the specified pass angle of rupture of inversion side is γ _n; Commutation zero hour, 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 required commutation cartographic represenation of area of 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 required commutation area of the converter valve commutation under nominal working conditions.

In described step 2-2, under work at present condition, the required commutation cartographic represenation of area of commutation is:

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

Wherein, A _ffor the required commutation area of commutation under work at present condition; I _dfor the DC current under work at present condition; 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, under work at present condition, commutation voltage can fluctuate, and the Trigger Angle of inversion side converter valve reaches Trigger Angle upper limit α _limittime, the pass angle of rupture is γ ₀, after commutation voltage fluctuates, commutation voltage amplitude is by U _lNbecome U _l, the required commutation area of 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 ' _ffor after commutation voltage fluctuates, the required commutation area of commutation under work at present condition;

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, by the Trigger Angle of the relatively control protection system output of converter valve and the Trigger Angle upper limit of inversion side converter valve, can anticipation whether there is commutation failure; The Trigger Angle of controlling protection system output represents with α, and deterministic process is specially:

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

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 take measures rapidly to prevent commutation failure.

2. accuracy of judgement, the Trigger Angle upper limit computing method of deriving and obtaining according to theory, the method can accurately be judged the generation of commutation failure.

3. can accurately judge the commutation failure being caused by common causes such as inversion 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 inversion side AC current-voltage amplitude perunit value and DC current perunit value;

Step 2: the Trigger Angle upper limit of calculating inversion 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 inversion side alternating current line voltage magnitude U _lwith the DC current instantaneous value I under condition of work _d;

Step 1-2: inversion 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 zero hour, t ₂for commutation finish time, so at t ∈ [t ₁, t ₂] time, the current relationship before and after being started 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 ' _ba(t) be line voltage between AB two-phase, A is commutation area.

Definition commutation voltage to the integration of time, be commutation voltage time and area (hereinafter to be referred as commutation area, being designated as A), illustrated that completing the required commutation area A of commutation process is a fixed value, and commutation area A and DC current proportional.The size of commutation area A has determined the speed of commutation process, has also determined the size of angle of overlap μ.

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

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

Step 2-2: calculate the required commutation area of commutation under work at present condition;

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

In described step 2-1, with inversion side commutation voltage u _bawaveform and converter valve 1 to the commutation process of converter valve 3 commutations, commutation area A under nominal working conditions is described _ncomputing method.Suppose commutation voltage u _bawaveform is standard sine waveform, and angular frequency do not change, inversion side commutation voltage u _bawaveform as shown in Figure 3, is pressed general number order, u _bafor the change of current voltage of converter valve 1 to converter valve 3 commutations, its expression formula under nominal working conditions is:

u _ba(t)＝U _LNsin(ωt) （3）

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

If the specified Trigger Angle of inversion side is α _n, the specified pass angle of rupture of inversion side is γ _n; Commutation zero hour, 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 required commutation cartographic represenation of area of 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 required commutation area of the converter valve commutation under nominal working conditions.

In described step 2-2, under work at present condition, the required commutation cartographic represenation of area of commutation is:

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

Wherein, A _ffor the required commutation area of commutation under work at present condition; I _dfor the DC current under work at present condition; 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, under work at present condition, commutation voltage can fluctuate, and the Trigger Angle of inversion side converter valve reaches Trigger Angle upper limit α _limittime, the pass angle of rupture is γ ₀, after commutation voltage fluctuates, commutation voltage amplitude is by U _lNbecome U _l, the required commutation area of 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 ' _ffor after commutation voltage fluctuates, the required commutation area of commutation under work at present condition;

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, by the Trigger Angle of the relatively control protection system output of converter valve and the Trigger Angle upper limit of inversion side converter valve, can anticipation whether there is commutation failure; The Trigger Angle of controlling protection system output represents with α, and deterministic process is specially:

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

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 instruction 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 the present invention is had been described in detail with reference to above-described embodiment, those of ordinary skill in the field are to be understood that: still can modify or be equal to replacement the specific embodiment of the present invention, and do not depart from any modification of spirit and scope of the invention or be equal to replacement, it all should be encompassed in the middle of claim scope of the present invention.

Claims (7)

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

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

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

Step 3: whether anticipation commutation failure occurs.

2. the pre-judging method of converter valve commutation failure according to claim 1, is characterized in that: in described step 1, described step 1 comprises the following steps:

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

Step 1-2: inversion 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.

3. the pre-judging method of converter valve commutation failure according to claim 1, is characterized in that: described step 2 comprises the following steps:

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

Step 2-2: calculate the required commutation area of commutation under work at present condition;

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

4. the pre-judging method of converter valve commutation failure according to claim 3, is characterized in that: in described step 2-1, press general number order, u _bafor the change of current voltage of converter valve 1 to converter valve 3 commutations, its expression formula under nominal working conditions is:

u _ba(t)＝U _LNsin(ωt) （3）

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

If the specified Trigger Angle of inversion side is α _n, the specified pass angle of rupture of inversion side is γ _n; Commutation zero hour, 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 required commutation cartographic represenation of area of 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 required commutation area of the converter valve commutation under nominal working conditions.

5. the pre-judging method of converter valve commutation failure according to claim 3, is characterized in that: in described step 2-2, under work at present condition, the required commutation cartographic represenation of area of commutation is:

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

Wherein, A _ffor the required commutation area of commutation under work at present condition; I _dfor the DC current under work at present condition; I _dNfor the DC current under nominal working conditions;

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

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

6. the pre-judging method of converter valve commutation failure according to claim 3, is characterized in that: in described step 2-3, under work at present condition, commutation voltage can fluctuate, and the Trigger Angle of inversion side converter valve reaches Trigger Angle upper limit α _limittime, the pass angle of rupture is γ ₀, after commutation voltage fluctuates, commutation voltage amplitude is by U _lNbecome U _l, the required commutation area of 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 ' _ffor after commutation voltage fluctuates, the required commutation area of commutation under work at present condition;

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

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

7. the pre-judging method of converter valve commutation failure according to claim 1, it is characterized in that: in described step 3, by the Trigger Angle of the relatively control protection system output of converter valve and the Trigger Angle upper limit of inversion side converter valve, can anticipation whether there is commutation failure; The Trigger Angle of controlling protection system output represents with α, and deterministic process is specially:

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

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.

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