CN103760447B - A kind of alternating-current fault detection method for D.C. high voltage transmission - Google Patents

Abstract

The invention provides a kind of alternating-current fault detection method for D.C. high voltage transmission, the method comprises the following steps: obtain the three-phase current in the three-phase voltage of change of current bus and each bar outlet of change of current bus respectively; The voltage zero order components value of change of current bus and the current zero sequence component value of rotating vector amplitude and each outlet of change of current bus and rotating vector amplitude is obtained respectively according to the three-phase current on the three-phase voltage of change of current bus and the outlet of change of current bus each bar; Obtain power zero-sequence component value and the power rotating vector amplitude of each outlet of change of current bus; Above-mentioned each value is contrasted with respective setting value respectively, obtains failure detection result.This detection method speed is fast, accuracy good, and meets the requirement of D.C. high voltage transmission to fault detect, for the control system defence commutation failure of D.C. high voltage transmission provides valuable information.

Description

A kind of alternating-current fault detection method for D.C. high voltage transmission

Technical field

The present invention relates to a kind of method of power transmission and distribution technical field, specifically relate to a kind of fault detection method for D.C. high voltage transmission.

Background technology

Since the 1950's, tradition line 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.

But because LCC-HVDC adopts without the triode thyristor of self-switching-off capability as commutation components, therefore LCC-HVDC system needs the AC system of some strength to realize commutation, needs AC network to provide commutation voltage.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, easily 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.

Fault in ac transmission system is one of key factor causing commutation failure, detects fault as early as possible, and control system is reacted rapidly, is the key of defence commutation failure.And in existing protecting electrical power system, the protection domain of isolating switch has strict restriction, its action setting valve will match with the protection seting value of adjacent lines usually, which ensure that selectivity and quick-action.But in D.C. high voltage transmission, change of current bus near zone breaks down all may cause commutation failure, and fault detect is not for this section of circuit, but detect near change of current bus whether have fault.If according to the setting principle of breaker actuation general in electric system, there will be the problems such as fault detect scope is wide not, the detection used time is longer.And D.C. high voltage transmission is as harmonic source, its busbar voltage non complete symmetry, makes the output of voltage have certain fluctuation, if only use voltage as failure criterion, then in order to ensure the reliability judged, has to sacrifice quick-action.Equally, harmonic current and asymmetric electric current on the amplitude of electric current, slope, the impact of curvature waveform generation, only can also have same problem with electric current as failure criterion.

Summary of the invention

For overcoming above-mentioned the deficiencies in the prior art, the invention provides a kind of alternating-current fault detection method for D.C. high voltage transmission, detection failure scope is wide, identify that the fault time used is short, meet the fault detect requirement of D.C. high voltage transmission, for the control system defence commutation failure of D.C. high voltage transmission provides valuable information.

Realizing the solution that above-mentioned purpose adopts is:

For an alternating-current fault detection method for D.C. high voltage transmission, its improvements are: said method comprising the steps of:

Three-phase current in I, the three-phase voltage obtaining change of current bus respectively and each bar outlet of change of current bus;

II, to obtain the voltage zero order components value of change of current bus and the current zero sequence component value of voltage rotating vector amplitude and each outlet of described change of current bus and electric current rotating vector amplitude respectively according to the three-phase current on the three-phase voltage of described change of current bus and the outlet of change of current bus each bar;

III, the power zero-sequence component value obtaining each outlet of change of current bus and power rotating vector amplitude;

IV, the power zero-sequence component value of the current zero sequence component value of the voltage zero order components value of described change of current bus and voltage rotating vector amplitude, each outlet of described change of current bus and electric current rotating vector amplitude, each outlet of described change of current bus and power rotating vector amplitude to be contrasted with respective setting value respectively, obtain failure detection result.

Further, in described step I, described change of current bus is provided with voltage real-time monitoring device, each outlet of described change of current bus is provided with electric current real-time monitoring device, uses described voltage real-time monitoring device and described electric current real-time monitoring device to obtain the three-phase voltage of change of current bus and the three-phase current of each outlet of described change of current bus in real time.

Further, in described Step II, obtain A, B, C three-phase voltage instantaneous value of described change of current bus, obtain the described voltage zero order components value of described change of current bus and described voltage rotating vector amplitude according to following formula (1), (2), (3):

u ₀＝u _a+u _b+u _c(1)

$\left[\begin{array}{c}{u}_{\mathrm{\α}}\\ u_{\mathrm{\β}}\end{array}\right]=\left[\begin{array}{ccc}\frac{2}{3}& -\frac{1}{3}& -\frac{1}{3}\\ 0& \frac{\sqrt{3}}{3}& -\frac{\sqrt{3}}{3}\end{array}\right]\left[\begin{array}{c}{u}_a\\ u_b\\ u_c\end{array}\right]---\left(2\right)$

$u_{th}=\sqrt{{u_{\mathrm{\α}}}^2+{u_{\mathrm{\β}}}^2}---\left(3\right)$

In formula, u _a, u _band u _cbe respectively A, B, C three-phase voltage instantaneous value that change of current bus obtains in real time, u _αand u _βbe respectively the component that change of current busbar voltage rotating vector is corresponding on alpha-beta plane α axle and β axle, u ₀and u _thbe respectively voltage zero order components value and the voltage rotating vector amplitude of change of current bus.

Further, in described Step II, A, B, C three-phase current instantaneous value in each outlet of change of current bus described in Real-time Obtaining, obtains described current zero sequence component value in each outlet of described change of current bus and described electric current rotating vector amplitude according to following formula (4), (5), (6):

i _0n＝i _an+i _bn+i _cn(4)

$\left[\begin{array}{c}{i}_{\mathrm{\α}n}\\ i_{\mathrm{\β}n}\end{array}\right]=\left[\begin{array}{ccc}\frac{2}{3}& -\frac{1}{3}& -\frac{1}{3}\\ 0& \frac{\sqrt{3}}{3}& -\frac{\sqrt{3}}{3}\end{array}\right]\left[\begin{array}{c}{i}_{an}\\ i_{bn}\\ i_{cn}\end{array}\right]---\left(5\right)$

$i_{thn}=\sqrt{{i_{\mathrm{\α}n}}^2+{i_{\mathrm{\β}n}}^2}---\left(6\right)$

In formula, i _an, i _bnand i _cna, B, C three-phase current instantaneous value in the outlet that the current transformer being respectively n-th outlet of change of current bus records in real time, i _{α n}and i _{β n}be respectively the component of the electric current rotating vector correspondence on alpha-beta plane α axle and β axle in this outlet, i _0nand i _thnbe respectively described current zero sequence component value and described electric current rotating vector amplitude in this outlet.

Further, in described Step II I, the absolute value absolute value of the described voltage zero order components value of described change of current bus being multiplied by the described current zero sequence component value of each outlet of described change of current bus as shown in the formula (7) obtains the described power zero-sequence component value p in each outlet of described change of current bus _0n:

p _0n＝|u ₀|*|i _0n|(7)

In formula, u ₀for voltage zero order components value, i _0nfor current zero sequence component value.

Further, in described Step II I, as shown in the formula (8) side-play amount of the described voltage rotating vector amplitude of described change of current bus is multiplied by the described electric current rotating vector magnitude shift amount in each outlet of described change of current bus, obtains the described power rotating vector amplitude p in each outlet of change of current bus _thn:

p _thn＝(u _Nth-u _th)*(i _thn-i _Mthn)(8)

In formula, u _thfor voltage rotating vector amplitude; i _thnfor electric current rotating vector amplitude, u _nthfor change of current bus three-phase voltage ratings u _aN, u _bNand u _cNrated voltage rotating vector amplitude, i _mthnfor three-phase current maximal value i _man, i _mbnand i _mcnthe rotating vector amplitude of maximum current.

Further, described step IV comprises the following steps:

S401, in conjunction with D.C. high voltage transmission, according to setting principle, obtain the setting value of the setting value of current zero sequence component, the setting value of the electric current rotating vector amplitude of each outlet of described change of current bus, the setting value of the power zero-sequence component of each outlet of described change of current bus and the power rotating vector amplitude of each outlet of described change of current bus in the setting value of the voltage zero order components of described change of current bus, the setting value of voltage rotating vector amplitude of described change of current bus, the outlet of described change of current bus every bar;

S402, the power zero-sequence component value of the current zero sequence component value of the voltage zero order components value of described change of current bus and voltage rotating vector amplitude, each outlet of described change of current bus and electric current rotating vector amplitude, each outlet of described change of current bus and power rotating vector amplitude to be contrasted with respective setting value respectively, and carry out logic integration, obtain the quick testing result of fault;

If in certain outlet of S403 change of current bus, when the zero-sequence component of electric current, voltage, power exceedes respective setting value respectively, then make the judgement that single-phase fault occurs;

If when the rotating vector amplitude of above each physical quantity all exceedes setting value in S404 certain outlet, then make the judgement that three-phase fault occurs;

Further, described setting principle comprises following rule:

The described current zero sequence component setting value of A, n-th outlet need be greater than this outlet maximum imbalance current under normal circumstances, and the setting value of the electric current rotating vector amplitude of each outlet of described change of current bus need be greater than the rotating vector amplitude of maximum current;

The zero-sequence component setting value of B, described change of current busbar voltage need be greater than the maximum asymmetrical voltage of described change of current bus, and the setting value of the voltage rotating vector amplitude of described change of current bus need be less than minimum operating voltage rotating vector amplitude.

Compared with prior art, the present invention has following beneficial effect:

(1) the present invention is by measuring the instantaneous value of change of current bus three-phase voltage and change of current bus every bar outlet three-phase current in real time, carry out certain computing, obtain the current zero sequence component value in the voltage zero order components value of change of current bus and rotating vector amplitude thereof, each outlet of change of current bus and rotating vector amplitude thereof, determine power zero-sequence component value and rotating vector amplitude thereof further; According to the requirement of D.C. high voltage transmission to fault detect, the setting value of above-mentioned each physical quantity of rationally adjusting, and by each physical quantity respectively compared with respective setting value, and carry out logic integration, finally obtain the quick testing result of fault; The testing result speed of gained is fast, accuracy good, and meets the requirement of D.C. high voltage transmission to fault detect, can provide valuable information for the control system defence commutation failure of D.C. high voltage transmission.

(2) the present invention with reference to power three kinds of different physical quantities of electric current in change of current busbar voltage, the outlet of described change of current bus each bar and described outlet simultaneously, compared with a kind of physical quantity detection failure of single dependence voltage, quantity of information is larger, more fully reacted the real-time running state near change of current bus, for the quick-action of fault detect, reliability and the two coordinate better and provide larger space.

(3) measurement of voltage involved in the present invention, current zero sequence component and rotating vector and the computation process of power component are all comparatively simple, and computing velocity is fast and result is accurate, and computation delay is very little, can ignore; Increase work efficiency, reduce computer memory.

(4) method of the present invention carries out fault detect with reference to power three kinds of different physical quantities of the electric current in change of current busbar voltage, the outlet of described change of current bus each bar and described outlet, detection failure scope is wide, identify that the fault time used is short, meet the fault detect requirement of D.C. high voltage transmission, for the control system defence commutation failure of D.C. high voltage transmission provides valuable information.

Accompanying drawing explanation

Fig. 1 is the ac fault detection decision logic figure for D.C. high voltage transmission.

Embodiment

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

As shown in Figure 1, Fig. 1 is the decision logic figure of the ac fault detection for D.C. high voltage transmission; Change of current bus is provided with voltage real-time monitoring device, and each outlet of change of current bus is respectively equipped with electric current real-time monitoring device, for obtaining three-phase voltage value and three-phase electricity flow valuve in real time.

A kind of alternating-current fault detection method for D.C. high voltage transmission comprises following:

Step one, the three-phase voltage obtaining change of current bus respectively and three-phase current;

Step 2, to obtain the voltage zero order components value of change of current bus and the current zero sequence component value of rotating vector amplitude and each outlet of change of current bus and rotating vector amplitude respectively according to the three-phase current instantaneous value on the three-phase voltage instantaneous value of change of current bus and every bar outlet of described change of current bus;

Step 3, the power zero-sequence component value obtaining the every bar outlet of change of current bus and power rotating vector amplitude;

Step 4, the power zero-sequence component value of the current zero sequence component value of the voltage zero order components value of described change of current bus and rotating vector amplitude, each outlet of described change of current bus and rotating vector amplitude, each outlet of described change of current bus and power rotating vector amplitude to be contrasted with respective setting value respectively, obtain quick fault testing result.

In step one, obtain the three-phase voltage of change of current bus and the three-phase current of each bar outlet of described change of current bus respectively.

For obtaining the three-phase voltage of change of current bus, change of current bus is provided with voltage real-time monitoring device, such as voltage sensor; For obtaining the instantaneous value of the three-phase current change of current, each outlet of change of current bus is provided with electric current real-time monitoring device, such as current sensor.

Use voltage real-time monitoring device to obtain the instantaneous voltage of three-phase A, B, C of change of current bus, use electric current real-time monitoring device to obtain the current instantaneous value of three-phase A, B, C in each outlet of change of current bus.

In step 2, obtain voltage zero order components value and the rotating vector amplitude of change of current bus according to three-phase voltage.

Commutation failure PREDICTIVE CONTROL module in three wide DC engineerings can be used, obtain voltage zero order components value and the rotating vector amplitude of change of current bus.

The fault detection method that three wide DC engineerings use is the alternating-current fault detection method utilizing false voltage feature, and the performance period is shorter, requirement of real time.

In the present invention, in three wide DC engineerings, commutation failure PREDICTIVE CONTROL module obtains A, B, C three-phase voltage instantaneous value of change of current bus respectively, use the method for commutation failure PREDICTIVE CONTROL module in three wide DC engineerings, namely according to voltage zero order components value and the rotating vector amplitude of following formula (1), (2), (3) acquisition change of current bus:

u ₀＝u _a+u _b+u _c(1)

$\left[\begin{array}{c}{u}_{\mathrm{\α}}\\ u_{\mathrm{\β}}\end{array}\right]=\left[\begin{array}{ccc}\frac{2}{3}& -\frac{1}{3}& -\frac{1}{3}\\ 0& \frac{\sqrt{3}}{3}& -\frac{\sqrt{3}}{3}\end{array}\right]\left[\begin{array}{c}{u}_a\\ u_b\\ u_c\end{array}\right]---\left(2\right)$

$u_{th}=\sqrt{{u_{\mathrm{\α}}}^2+{u_{\mathrm{\β}}}^2}---\left(3\right)$

In formula, u _a, u _band u _cbe respectively A, B, C three-phase voltage instantaneous value that the voltage transformer (VT) on change of current bus records in real time, u _αand u _βbe respectively the component that change of current busbar voltage rotating vector is corresponding on alpha-beta plane α axle and β axle, u ₀and u _thbe respectively voltage zero order components value and the rotating vector amplitude of change of current bus.

In step 2, with reference to the computing method of change of current busbar voltage zero-sequence component value and rotating vector amplitude in commutation failure PREDICTIVE CONTROL module in three wide DC engineerings, according to the current zero sequence component value in each outlet of three-phase current acquisition change of current bus and rotating vector amplitude.

In the inventive method, in three wide DC engineerings commutation failure PREDICTIVE CONTROL module basis on, increase according to the electric current that each bar outlet of described change of current bus is flow through, and described three-phase voltage and described three-phase current are constructed power component, use three kinds of physical quantitys to detect the logical method of AC fault simultaneously.Specific as follows;

Obtain A, B, C three-phase current instantaneous value in each outlet of change of current bus, with reference to the method for commutation failure PREDICTIVE CONTROL module in three wide DC engineerings, namely obtain current zero sequence component value in each outlet of described change of current bus and rotating vector amplitude according to following formula (4), (5), (6):

i _0n＝i _an+i _bn+i _cn(4)

$\left[\begin{array}{c}{i}_{\mathrm{\α}n}\\ i_{\mathrm{\β}n}\end{array}\right]=\left[\begin{array}{ccc}\frac{2}{3}& -\frac{1}{3}& -\frac{1}{3}\\ 0& \frac{\sqrt{3}}{3}& -\frac{\sqrt{3}}{3}\end{array}\right]\left[\begin{array}{c}{i}_{an}\\ i_{bn}\\ i_{cn}\end{array}\right]---\left(5\right)$

$i_{thn}=\sqrt{{i_{\mathrm{\α}n}}^2+{i_{\mathrm{\β}n}}^2}---\left(6\right)$

In formula, i _an, i _bnand i _cna, B, C three-phase current instantaneous value in this outlet that the electric current real-time monitoring device being respectively n-th outlet of change of current bus obtains, i _{α n}and i _{β n}be respectively the component of the described electric current rotating vector correspondence on alpha-beta plane α axle and β axle in this outlet, i _0nand i _thnbe respectively described current zero sequence component value and described rotating vector amplitude in this outlet.

In step 3, obtain the following method of power zero-sequence component value of change of current bus every bar outlet:

The absolute value as shown in the formula (7), the absolute value of the described voltage zero order components of described change of current bus being multiplied by the described current zero sequence component of each outlet of described change of current bus obtains the described power zero-sequence component value p in each outlet of described change of current bus _0n:

p _0n＝|u ₀|*|i _0n|(7)

In formula, u ₀for the voltage zero order components value of described change of current bus; i _0nfor the current zero sequence component value of this outlet on described change of current bus.

In step 3, obtain the following method of power rotating vector amplitude of change of current bus every bar outlet:

As shown in the formula (8) side-play amount of the described voltage rotating vector amplitude of described change of current bus is multiplied by the described electric current rotating vector magnitude shift amount in each outlet of described change of current bus, obtains the described power rotating vector amplitude p in each outlet of change of current bus _thn:

p _thn＝(u _Nth-u _th)*(i _thn-i _Mthn)(8)

In formula, u _thfor rotating vector amplitude; i _thnfor rotating vector amplitude; u _nthfor change of current bus three-phase voltage ratings u _aN, u _bNand u _cNrated voltage rotating vector amplitude, by the u in formula (2) _a, u _band u _creplace with the change of current bus A, B, C three-phase voltage ratings u respectively _aN, u _bNand u _cN, can be calculated by formula (2), (3); i _mthnfor three-phase current maximal value i _man, i _mbnand i _mcnthe rotating vector amplitude of maximum current, by the i in formula (5) _an, i _bnand i _cna, B, C three-phase current maximal value i in n-th outlet replacing with change of current bus respectively _man, i _mbnand i _mcn, can be calculated by formula (5), (6).

In step 4, the power zero-sequence component value of the current zero sequence component value of the voltage zero order components value of described change of current bus and rotating vector amplitude, each outlet of described change of current bus and rotating vector amplitude, each outlet of described change of current bus and power rotating vector amplitude are contrasted with respective setting value respectively, obtains quick fault testing result.

Specifically comprise the following steps:

(1) feature, in conjunction with D.C. high voltage transmission is adjusted, according to setting principle, obtain the setting value of the power rotating vector amplitude in the setting value of the fault power zero-sequence component in the setting value of the electric current rotating vector amplitude in the setting value of the current zero sequence component in the setting value of the voltage zero order components of change of current bus, the setting value of voltage rotating vector amplitude of change of current bus, the outlet of change of current bus every bar, the outlet of change of current bus every bar, the outlet of change of current bus every bar and the every bar outlet of change of current bus.

Owing to breaking down in distance change of current bus certain distance, all likely cause DC transmission system generation commutation failure, and the occurrence of this segment distance is relevant with many factors, is difficult to determine.Therefore, must ensure that CFPREP (in three wide DC engineerings commutation failure PREDICTIVE CONTROL module) has enough sensitivity, to find the fault likely causing commutation failure.

For this reason, only need ensure that CFPREP can not judge by accident under normal circumstances, then the setting principle that in CFPREP, in the setting principle of each physical quantity setting value and relay protection, time delay over-current is protected is similar.

Above-mentioned setting principle is specific as follows:

A, electric current for n-th outlet, its zero-sequence component setting value i _{0n_set}only need escape this outlet maximum imbalance current under normal circumstances, α β component setting value i _{thn_set}only need escape the rotating vector amplitude of maximum current, i.e. i _{thn_set}be about 30% of maximum current rotating vector amplitude.

B, for change of current busbar voltage, its zero-sequence component setting value u _{0_set}only need escape the maximum asymmetrical voltage of change of current bus, α β component setting value u _{th_set}only need escape minimum operating voltage rotating vector amplitude, i.e. u _{th_set}be about 95% of rated voltage rotating vector amplitude.

If the two correspondence is multiplied by C, obtain CFPREP power zero-sequence component setting value p respectively _{0n_set}, α β component setting value p _{thn_set}, then power component setting value is all less, and sensitivity is very high, can detect fault rapidly.

D, for improve reliability, guarantee judge correctness, can suitably improve CFPREP power component setting value on this basis.

Not malfunction when " escaping " situation below of expression.That is:

Setting principle A represents, current zero sequence component setting value needs to be greater than this outlet maximum imbalance current under normal circumstances, and the setting value of electric current rotating vector amplitude needs the rotating vector amplitude being greater than maximum current.

Setting principle B represents, the zero-sequence component setting value of change of current busbar voltage need be greater than the maximum asymmetrical voltage of change of current bus, and the setting value of the voltage rotating vector amplitude of described change of current bus need be less than minimum operating voltage rotating vector amplitude.

(2), the power zero-sequence component value of the current zero sequence component value of the voltage zero order components value of change of current bus and rotating vector amplitude, each outlet of change of current bus and rotating vector amplitude, each outlet of change of current bus and power rotating vector amplitude are contrasted with respective setting value respectively, and carry out logic integration, obtain the quick testing result of fault;

If in certain outlet of change of current bus, when the zero-sequence component of electric current, voltage, power (voltage zero order components is shared by each bar outlet, lower with) exceedes respective setting value respectively, then make the judgement that single-phase fault occurs;

If when the rotating vector amplitude of above each physical quantity all exceedes setting value in certain outlet, then make the judgement that three-phase fault occurs.

Finally should be noted that: above embodiment is only for illustration of the technical scheme of the application but not the restriction to its protection domain; although with reference to above-described embodiment to present application has been detailed description; those of ordinary skill in the field are to be understood that: those skilled in the art still can carry out all changes, amendment or equivalent replacement to the embodiment of application after reading the application; but these change, revise or be equal to replacement, all applying within the claims awaited the reply.

Claims (7)

1. for an alternating-current fault detection method for D.C. high voltage transmission, it is characterized in that: said method comprising the steps of:

Three-phase current in I, the three-phase voltage obtaining change of current bus respectively and each bar outlet of change of current bus;

II, to obtain the voltage zero order components value of change of current bus and the current zero sequence component value of voltage rotating vector amplitude and each outlet of described change of current bus and electric current rotating vector amplitude respectively according to the three-phase current on the three-phase voltage of described change of current bus and the outlet of change of current bus each bar;

III, the power zero-sequence component value obtaining each outlet of change of current bus and power rotating vector amplitude;

In described Step II I, the absolute value absolute value of the described voltage zero order components value of described change of current bus being multiplied by the described current zero sequence component value of each outlet of described change of current bus as shown in the formula (7) obtains the described power zero-sequence component value p in each outlet of described change of current bus _0n:

p _0n＝|u ₀|*|i _0n|(7)

In formula, u ₀for voltage zero order components value, i _0nfor current zero sequence component value;

IV, the power zero-sequence component value of the current zero sequence component value of the voltage zero order components value of described change of current bus and voltage rotating vector amplitude, each outlet of described change of current bus and electric current rotating vector amplitude, each outlet of described change of current bus and power rotating vector amplitude to be contrasted with respective setting value respectively, obtain failure detection result.

2. a kind of alternating-current fault detection method for D.C. high voltage transmission as claimed in claim 1, it is characterized in that: in described step I, described change of current bus is provided with voltage real-time monitoring device, each outlet of described change of current bus is provided with electric current real-time monitoring device, uses described voltage real-time monitoring device and described electric current real-time monitoring device to obtain the three-phase voltage of change of current bus and the three-phase current of each outlet of described change of current bus in real time.

3. a kind of alternating-current fault detection method for D.C. high voltage transmission as claimed in claim 1, it is characterized in that: in described Step II, obtain A, B, C three-phase voltage instantaneous value of described change of current bus, obtain the described voltage zero order components value of described change of current bus and described voltage rotating vector amplitude according to following formula (1), (2), (3):

u ₀＝u _a+u _b+u _c(1)

$\left[\begin{array}{c}{u}_{\mathrm{\α}}\\ u_{\mathrm{\β}}\end{array}\right]=\left[\begin{array}{ccc}\frac{2}{3}& -\frac{1}{3}& -\frac{1}{3}\\ 0& \frac{\sqrt{3}}{3}& -\frac{\sqrt{3}}{3}\end{array}\right]\left[\begin{array}{c}{u}_a\\ u_b\\ u_c\end{array}\right]---\left(2\right)$

$u_{th}=\sqrt{{u_{\mathrm{\α}}}^2+{u_{\mathrm{\β}}}^2}---\left(3\right)$

In formula, u _a, u _band u _cbe respectively A, B, C three-phase voltage instantaneous value that change of current bus obtains in real time, u _αand u _βbe respectively the component that change of current busbar voltage rotating vector is corresponding on alpha-beta plane α axle and β axle, u ₀and u _thbe respectively voltage zero order components value and the voltage rotating vector amplitude of change of current bus.

4. a kind of alternating-current fault detection method for D.C. high voltage transmission as claimed in claim 1, it is characterized in that: in described Step II, A, B, C three-phase current instantaneous value in each outlet of change of current bus described in Real-time Obtaining, obtains described current zero sequence component value in each outlet of described change of current bus and described electric current rotating vector amplitude according to following formula (4), (5), (6):

i _0n＝i _an+i _bn+i _cn(4)

$\left[\begin{array}{c}{i}_{\mathrm{\α}n}\\ i_{\mathrm{\β}n}\end{array}\right]=\left[\begin{array}{ccc}\frac{2}{3}& -\frac{1}{3}& -\frac{1}{3}\\ 0& \frac{\sqrt{3}}{3}& -\frac{\sqrt{3}}{3}\end{array}\right]\left[\begin{array}{c}{i}_{an}\\ i_{bn}\\ i_{cn}\end{array}\right]---\left(5\right)$

$i_{thn}=\sqrt{{i_{\mathrm{\α}n}}^2+{i_{\mathrm{\β}n}}^2}---\left(6\right)$

In formula, i _an, i _bnand i _cna, B, C three-phase current instantaneous value in the outlet that the current transformer being respectively n-th outlet of change of current bus records in real time, i _{α n}and i _{β n}be respectively the component of the electric current rotating vector correspondence on alpha-beta plane α axle and β axle in this outlet, i _0nand i _thnbe respectively described current zero sequence component value and described electric current rotating vector amplitude in this outlet.

5. a kind of alternating-current fault detection method for D.C. high voltage transmission as claimed in claim 1, it is characterized in that: in described Step II I, as shown in the formula (8) side-play amount of the described voltage rotating vector amplitude of described change of current bus is multiplied by the described electric current rotating vector magnitude shift amount in each outlet of described change of current bus, obtains the described power rotating vector amplitude p in each outlet of change of current bus _thn:

p _thn＝(u _Nth-u _th)*(i _thn-i _Mthn)(8)

In formula, u _thfor voltage rotating vector amplitude; i _thnfor electric current rotating vector amplitude, u _nthfor change of current bus three-phase voltage ratings u _aN, u _bNand u _cNrated voltage rotating vector amplitude, i _mthnfor three-phase current maximal value i _man, i _mbnand i _mcnthe rotating vector amplitude of maximum current.

6. a kind of alternating-current fault detection method for D.C. high voltage transmission as claimed in claim 1, is characterized in that: described step IV comprises the following steps:

S401, setting principle in conjunction with D.C. high voltage transmission, obtain the setting value of the setting value of current zero sequence component, the setting value of the electric current rotating vector amplitude of each outlet of described change of current bus, the setting value of the power zero-sequence component of each outlet of described change of current bus and the power rotating vector amplitude of each outlet of described change of current bus in the setting value of the voltage zero order components of described change of current bus, the setting value of voltage rotating vector amplitude of described change of current bus, the outlet of described change of current bus every bar;

S402, the power zero-sequence component value of the current zero sequence component value of the voltage zero order components value of described change of current bus and voltage rotating vector amplitude, each outlet of described change of current bus and electric current rotating vector amplitude, each outlet of described change of current bus and power rotating vector amplitude to be contrasted with respective setting value respectively, and carry out logic integration, obtain the quick testing result of fault;

If in certain outlet of S403 change of current bus, when the zero-sequence component value of electric current, voltage, power exceedes respective setting value respectively, then make the judgement that single-phase fault occurs;

If when the rotating vector amplitude of electric current, voltage, power all exceedes setting value in S404 certain outlet, then make the judgement that three-phase fault occurs.

7. a kind of alternating-current fault detection method for D.C. high voltage transmission as claimed in claim 6, is characterized in that: described setting principle comprises following rule:

The described current zero sequence component setting value of A, n-th outlet need be greater than this outlet maximum imbalance current under normal circumstances, and the setting value of the electric current rotating vector amplitude of each outlet of described change of current bus need be greater than the rotating vector amplitude of maximum current;

The zero-sequence component setting value of B, described change of current busbar voltage need be greater than the maximum asymmetrical voltage of described change of current bus, and the setting value of the voltage rotating vector amplitude of described change of current bus need be less than minimum operating voltage rotating vector amplitude.