CN106033889A - Method for determining risk degrees of mutual influence of multi-infeed alternating current-direct current system inversion stations - Google Patents

Abstract

The invention discloses a method for determining the risk degrees of mutual influence of multi-infeed alternating current-direct current system inversion stations. The method comprises the following steps that 1, a model corresponding to a multi-infeed alternating current-direct current system is established; 2, disturbance is exerted on a certain inversion station i in the model, so that the voltage Ui of a converter bus i of the inversion station i is reduced by 1%; 3, based on voltage variations delta Uj of other inversion stations j in the multi-infeed alternating current-direct current system, three-phase multi-infeed interaction factors MIIFij of the inversion station i and inversion stations j are calculated; 4, based on the scores of the three-phase multi-infeed interaction factors, the first risk degree Ra and/or the second risk degree Rb of a certain inversion station k are calculated; 5, the first risk degree Ra and/or the second risk degree Rb are compared with reference values (or standard values) so as to determine the risk degrees of one or more inversion stations in the multi-infeed alternating current-direct current system. The method has the guiding effect on finding of potential risks of direct-current station commutation failure and formulation of corresponding prevention measures and can also provide reference indexes for direct-current station address selection.

Description

Determine the method for interactional risk between many feed-ins ac and dc systems Inverter Station

Technical field

The present invention relates to field of power, be specifically related to a kind of determine in many feed-ins ac and dc systems the method for interactional risk between Inverter Station.

Background technology

Along with implementing in full of " transferring electricity from the west to the east, north and south supply mutually, on national network " strategy, China the most progressively builds up the extra-high voltage AC and DC hybrid power system of the rarest trans-regional and long-distance transmissions great power, and its complexity and difficulties run the most also is rare.For the mixing of many feed-ins alternating current-direct current by electricity system, reinforcement and the increase of power system capacity due to electric network composition, electricity net safety stable characteristic there occurs certain change, multi-feed HVDC area is difficult to directly occur the stability disruption accident of angle of attack unstability, but support and in the case of other measures lacking enough dynamic reactive power supplys, disturbance may cause voltage pernicious decline when occurring, cause direct-current commutation failure, ultimately result in system unstability under serious conditions.

At extensive many feed-ins alternating current-direct current by electricity system, owing between DC inversion station, electrical distance is near, straight-flow system intercouples, and its direct current and direct current, direct current and the interaction between exchanging are higher so that the response of straight-flow system deteriorates.The commutation failure fault of one current conversion station, may result in other current conversion station commutation failures；Under fault in ac transmission system, the most simultaneously or sequentially there is commutation failure in each DC converter station, if each straight-flow system can not be recovered smoothly, will result in and has a power failure on a large scale.Thus, by analyzing the coupled relation between DC converter station and the relation that influences each other between ac and dc systems, find out the basic law of many feed-ins commutation failure, weak link in discovery system, and study the technical measures improving weak link, it is highly important for ensureing the safe and stable operation of power system.

Prior art has the interaction strong or weak relation judging between each DC converter station by single-phase many feed-ins interaction factor SMIIF, attempt to be found out the rule of commutation failure by this single-phase many feed-ins interaction factor SMIIF, the interaction strong or weak relation of single-phase voltage between different direct current drop point is only considered yet with single-phase many feed-ins interaction factor SMIIF, the needs in Practical Project can not be met, in addition, according to " power engineering electrical design handbook ", in Power System Shortcuts Current calculation: conductor and the Dynamic stability of electrical equipment, thermally-stabilised and the drop-out current of electrical equipment, general three-phase shortcircuit of pressing checks.Meanwhile, in the simulation analysis of DC transmission system quasi steady state model, it is assumed that three-phase voltage is symmetrical, for power frequency sine wave.So for having in the electrical network of multi-feed HVDC, general only consideration three-phase fault simulation analysis.

Summary of the invention

It is an object of the invention to provide and a kind of determine in many feed-ins ac and dc systems the method for interactional risk between Inverter Station, to ensure the safe and stable operation of power system.

For achieving the above object, the invention provides and a kind of determine in many feed-ins ac and dc systems the method for interactional risk between Inverter Station, comprise the following steps:

(1) building the model corresponding to described many feed-ins ac and dc systems, wherein said many feed-ins ac and dc systems includes n the Inverter Station being electrically connected to each other, and n is the positive integer of >=3；

(2) in the model of described many feed-ins ac and dc systems, to a certain Inverter Station i apply disturbance, i=1,2,3,4 ... n so that the voltage U of the change of current bus i of this Inverter Station i_iDecline 1%；

(3) based on the voltage variety △ U of other Inverter Station j in described many feed-ins ac and dc systems_j, calculate mutual factor M IIF of many feed-ins of the three-phase between described Inverter Station i and Inverter Station j_ij, wherein j=1,2,3 ..., n, and j ≠ i；

(4) based on described many feed-ins mutual factor M IIF score value (score), calculating the first risk Ra and/or second risk Rb of a certain Inverter Station k, wherein the first risk Ra is the risk that described Inverter Station is broken down by other Inverter Station disturbance；And the second risk Rb is the risk causing other Inverter Station to break down during described Inverter Station generation disturbance, wherein k=1,2,3 ..., n；With

(5) the first described risk Ra and/or Rb are compared with reference value (or standard value), so that it is determined that the risk of one or more Inverter Station in described many feed-ins ac and dc systems,

Wherein when described Ra is more than or equal to described reference value Ra_standard, then it represents that the risk of this Inverter Station is higher than general Inverter Station；Or.

Wherein when described Rb is more than or equal to described reference value Rb_standard, then it represents that the risk of this Inverter Station is higher than general Inverter Station.

In another preference, mutual factor M IIF of feed-ins many for the three-phase between described Inverter Station i and Inverter Station j_ijCalculate as follows, wherein as a example by i=1 and j=2:

$\mathrm{\Δ}{U}_2=(\frac{\mathrm{\Δ}{E}_2}{X_{N2}}+\frac{{\mathrm{\ΔU}}_1}{X_{12}}+\frac{\mathrm{\Δ}{U}_3}{X_{23}})\·X_{\mathrm{\Σ}}$

$X_{\mathrm{\Σ}}=(\frac{1}{X_{N2}}+\frac{1}{X_{12}}+\frac{1}{X_{23}})$

${\mathrm{MIIF}}_{12}=(\mathrm{\Δ}{U}_2/U_2){|}_{\mathrm{\Δ}{U}_1/U_1=1\%}$

In formula, △ E₂Represent the AC system equivalent electromotive force of change of current bus 2, △ U₁With △ U₃Represent the voltage of change of current bus 1,3, X respectively_N2Represent the equiva lent impedance of the AC system of change of current bus 2 correspondence, X₁₂For the coupled impedance between current conversion station 1,2, X₂₃For the coupled impedance between current conversion station 2,3.

In another preference, described n >=5, >=10, >=20, more preferably n are 5-100 or 10-50.

In another preference, for a certain Inverter Station k, described the first risk Ra I or II as the following formula calculates and judges:

Ra=∑ MIIF_lk, wherein l is the positive integer less than or equal to n, and l ≠ k.

In another preference, l=n, or l=5 or l=10.

In another preference, described ∑ MIIF_lkThe mutual factor score of many feed-ins of the highest front m1 position in score value for MIIF all for described Inverter Station k, wherein m1 is arbitrary positive integer of 3-10.

In another preference, m1 is 3,5,10.

In another preference, described reference value Ra_standardIt is 0.6,1.0 or 1.5.

In another preference, when m1 is 2, Ra_standardIt is 0.3；Or when m1 is 5, Ra_standardIt is 0.5；When m1 is 10, Ra_standardIt is 1.0.

In another preference, for Inverter Station k, described the second risk Rb I or II as the following formula calculates and judges:

Rb=∑ MIIF_kl, wherein l is the positive integer less than or equal to n, and l ≠ k.

In another preference, l=n, or l=5 or l10.

In another preference, described ∑ MIIF_klThe mutual factor score of many feed-ins of the highest front m2 position in score value for MIIF all for described Inverter Station k, wherein m2 is arbitrary positive integer of 3-15.

In another preference, m2 is 5,10 or 15.

In another preference, described reference value Rb_standardIt is 0.3,0.5 or 1.0.

In another preference, when m2 is 2, Rb_standardIt is 0.3；Or when m2 is 5, Rb_standardIt is 0.5；When m2 is 10, Rb_standardIt is 1.0.

In another preference, in step (5), further comprising the steps of: for described Inverter Station k, by single MIIF_klAnd/or single MIIF_lkFactor reference value MIIF mutual with many feed-ins_standardCompare,

Wherein as described single MIIF_klAnd/or single MIIF_lkMore than or equal to described reference value MIIF_standard, then it represents that the risk of this Inverter Station is higher than general Inverter Station.

In another preference, described reference value MIIF_standardIt is 0.4.

In another preference, for described Inverter Station k, there is 2-5 MIIF_klAnd/or 2-5 MIIF_lkMore than or equal to described reference value MIIF_standardTime, then it represents that the risk of this Inverter Station is high risk.

In another preference, described fault includes that commutation failure, described risk include the risk of described Inverter Station generation commutation failure.

The mutual level of factor of the many feed-ins of employing (MIIF) that the present invention proposes determine in many feed-ins ac and dc systems the method for interactional risk between Inverter Station, based on actual electric network model, employing time-domain-simulation calculates, preferably consider system dynamic characteristic, the voltage coupling that it is showed substantially has considered electrical distance between Inverter Station, effective short-circuit ratio of each change of current bus, actual DC through-put power etc. affects the factor of commutation failure, pass through quantizating index, the reciprocal action magnitude relationship between each direct current station can be drawn intuitively, the each Inverter Station of judgement system occurs simultaneously/the probability size of commutation failure and combination that may be present in succession, to finding the potential risk of direct current station commutation failure and formulating corresponding preventive measure there is certain directive function, it is alternatively the direct current siting of station and one reference index is provided.

Accompanying drawing explanation

Fig. 1 is three infeed HVDC Systems rough schematic views.

Detailed description of the invention

Below with reference to accompanying drawing, presently preferred embodiments of the present invention is described in detail, in order to become apparent from understanding the purpose of the present invention, feature and advantage.It should be understood that embodiment shown in the drawings is not limitation of the scope of the invention, and simply to illustrate that the connotation of technical solution of the present invention.

Term:

Average risk: commutation failure probability is 20%.

High risk: commutation failure probability is 80%.

Commutation failure: be DC transmission system most common failure.When commutation voltage decline and the inverter side DC voltage decline caused and DC current rising, unbalanced fault thereof, change of current voltage zero-cross point drift all can have influence on the generation of commutation failure, and wherein commutation voltage declines is the main cause causing commutation failure.If once certain current conversion station generation commutation failure, direct current transportation short interruptions will be caused, continuously it also occur that consequences such as DC system lockings during commutation failure, in severe cases it is possible that multiple current conversion station occurs continuous commutation failure simultaneously, even result in mains breakdown.Therefore it is very important for judging and avoiding commutation failure.

Mutual factor M IIF of many feed-ins is project planning stage of being proposed by CIGRE WG B4 working group for weighing in multi-infeed HVDC system the interactive index of voltage between current conversion station, and it is defined as follows:

Hypothesis system i.e. exists numbering and is respectively two DC converter stations of 1 and 2, when change of current bus 1 put into symmetrical three-phase reactor make the voltage drop on this bus be exactly 1% time, the change in voltage of change of current bus 2.That is:

${\mathrm{MIIF}}_{12}=\frac{\mathrm{\Δ}{U}_2\%}{1\%\mathrm{VoltageChangein}{U}_1}$

Multi-infeed HVDC system drop point concentrates on same AC network, and after some current conversion station is applied disturbance, the dynamic response of another current conversion station necessarily contains AC system and other current conversion stations common effect to it around here.The application in many feed-ins ac and dc systems of many feed-ins mutual factor M IIF is described as a example by three infeed HVDC Systems of Fig. 1.

As shown in Figure 1:

$U_2=(\frac{E_2}{X_{N2}}+\frac{U_1}{X_{12}}+\frac{U_3}{X_{23}}-\frac{\sqrt{6}}{\mathrm{\π}}{I}_{d2})\·(\frac{1}{X_{N2}}+\frac{1}{X_{12}}+\frac{1}{X_{23}})$

Wherein, U₁～U₃It is respectively the voltage of change of current bus 1～3；E₁～E₃It is respectively the AC system equivalent electromotive force corresponding with change of current bus 1～3；X_N1～X_N3It is respectively the AC system equiva lent impedance corresponding with change of current bus 1～3；X₁₂For the coupled impedance between current conversion station 1,2, X₁₃For the coupled impedance between current conversion station 1,3, X₂₃For the coupled impedance between current conversion station 2,3；I_d1～I_d3It is respectively the DC current that 3 DC power transmission lines are corresponding.

In the case of electric network composition and the method for operation determine, between current conversion station, coupled impedance and AC system Dai Weinan equiva lent impedance are certain, i.e.

$(\frac{1}{X_{N2}}+\frac{1}{X_{12}}+\frac{1}{X_{23}})$ It is a constant, is designated as X_Σ。

The most rewritable as follows:

$U_2=(\frac{E_2}{X_{N2}}+\frac{U_1}{X_{12}}+\frac{U_3}{X_{23}}-\frac{\sqrt{6}}{\mathrm{\π}}{I}_{d2})\·X_{\mathrm{\Σ}}$

Judge in engineering that commutation failure is usually employing experience voltage criterion, i.e. be considered as commutation failure when commutation voltage drops to certain threshold value.Assuming that commutation voltage just drops into commutation failure threshold value, corresponding Voltage Drop amplitude is △ U2, utilizes superposition theorem to have:

$\mathrm{\Δ}{U}_2=(\frac{\mathrm{\Δ}{E}_2}{X_{N2}}+\frac{\mathrm{\Δ}{U}_1}{X_{12}}+\frac{\mathrm{\Δ}{U}_3}{X_{23}})\·X_{\mathrm{\Σ}}$

General DC current just can significantly rise after commutation failure occurs, and have ignored the change of DC current the most here.From this formula, the commutation failure of Inverter Station is in addition to being affected by the AC system equivalent electric potential source being directly attached thereto, also affected by Inverter Station voltage coupled thereto, and the coefficient of coup between them is depended on the coupled impedance between each current conversion station and X from formula_∑。

MIIF is as the interactive index of voltage weighed between two Inverter Station, it is based on actual electric network model, the factors such as electrical distance between Inverter Station, effective short-circuit ratio of each change of current bus, actual DC through-put power are considered, employing time-domain-simulation calculates, and the voltage coupling coefficient that obtained result is relatively individually obstructed by exchange Dai Weinan equivalence and between Inverter Station, coupled impedance determines is the most reasonable.

The invention used MIIF index to weigh the risk that in many feed-ins ac and dc systems, Inverter Station breaks down, this fault includes commutation failure etc., and this risk includes the risk of Inverter Station generation commutation failure.

Use many feed-ins mutual factor M IIF is described in detail below to weigh the method for the risk that Inverter Station breaks down in many feed-ins ac and dc systems.

Use mutual factor M IIF of many feed-ins to judge that the method that between each Inverter Station of ac and dc systems, reciprocal action is strong and weak comprises the following steps:

(1) building the model corresponding to described many feed-ins ac and dc systems, wherein said many feed-ins ac and dc systems includes n the Inverter Station being electrically connected to each other, and n is the positive integer of >=3；

(2) in the model of described many feed-ins ac and dc systems, to a certain Inverter Station i apply disturbance, i=1,2,3,4 ... n so that the voltage U of the change of current bus i of this Inverter Station i_iDecline 1%；

(3) based on the voltage variety △ U of other Inverter Station j in described many feed-ins ac and dc systems_j, calculate mutual factor M IIF of many feed-ins of the three-phase between described Inverter Station i and Inverter Station j_ij, wherein j=1,2,3 ..., n, and j ≠ i；

(4) based on described many feed-ins mutual factor M IIF score value (score), calculating the first risk Ra and/or second risk Rb of a certain Inverter Station k, wherein the first risk Ra is the risk that described Inverter Station is broken down by other Inverter Station disturbance；And the second risk Rb is the risk causing other Inverter Station to break down during described Inverter Station generation disturbance, wherein k=1,2,3 ..., n；With

(5) the first described risk Ra and/or Rb are compared with reference value (or standard value), so that it is determined that the risk of one or more Inverter Station in described many feed-ins ac and dc systems,

Wherein when described Ra is more than or equal to described reference value Ra_standard, then it represents that the risk of this Inverter Station is higher than general Inverter Station；Or.

Wherein when described Rb is more than or equal to described reference value Rb_standard, then it represents that the risk of this Inverter Station is higher than general Inverter Station.

Wherein, for a certain Inverter Station k, the first risk Ra calculates as the following formula and judges:

Ra=∑ MIIF_lk, wherein l is the positive integer less than or equal to n, and l ≠ k.

It is preferred that l=n, or l=5 or l=10.

As l=n, Ra=∑ MIIF_lk=MIIF_1k+MIIF_2k+MIIF_3k+…+MIIF_nk。

As l=l or l=5 or l=10, identical with above-mentioned computational methods.

It is preferred that ∑ MIIF_lkThe mutual factor score of many feed-ins of the highest front m1 position in score value for MIIF all for Inverter Station k, wherein m1 is arbitrary positive integer of 3-10.

Wherein, it is 2, Ra as m1_standardIt is 0.4；Or when m1 is 5, Ra_standardIt is 0.5；When m1 is 10, Ra_standardIt is 1.0.

For Inverter Station k, the second risk Rb calculates as the following formula and judges:

Rb=∑ MIIF_kl, wherein l is the positive integer less than or equal to n, and l ≠ k.

In another preference, l=n, or l is 5 or 10.

As l=n, Ra=∑ MIIF_kl=MIIF_k1+MIIF_k2+MIIF_k3+…+MIIF_kn。

As l=1 or l=5 or l=10, identical with above-mentioned computational methods.

It is preferred that ∑ MIIF_klThe mutual factor score of many feed-ins of the highest front m2 position in score value for MIIF all for described Inverter Station k, wherein m2 is arbitrary positive integer of 3-15.

It is preferred that m2 is 5,10 or 15.

When m2 is 2, Rb_standardIt is 0.3；Or when m2 is 5, Rb_standardIt is 0.5；When m2 is 10, Rb_standardIt is 1.0.

In the present embodiment, in step (5), further comprising the steps of: for described Inverter Station k, by single MIIF_klAnd/or single MIIF_lkFactor reference value MIIF mutual with many feed-ins_standardCompare,

Wherein as described single MIIF_klAnd/or single MIIF_lkMore than or equal to described reference value MIIF_standard, then it represents that the risk of this Inverter Station is higher than general Inverter Station.

It is preferred that for Inverter Station k, have 2-5 MIIF_klAnd/or 2-5 MIIF_lkMore than or equal to described reference value MIIF_standardTime, then it represents that the risk of this Inverter Station is high risk.

It is preferred that described reference value MIIF_standardIt is 0.4.

Other current conversion station voltage participations to it when it will be seen that a current conversion station (or other exchange junctions) busbar voltage decline by MIIF；When certain current conversion station (or other exchange junctions) voltage suffers large disturbances, other disturbed degree of current conversion station voltage can be estimated by MIIF, can show that multiple Inverter Station simultaneously or sequentially experiences possible combination and the risk size of commutation failure, MIIF is the biggest, and the risk that commutation failure simultaneously occurs is the highest.

Below as a example by the Inverter Station of Jiangsu Power Grid many feed-ins ac and dc systems, illustrate to use mutual factor M IIF of many feed-ins to weigh the method for the risk that Inverter Station breaks down in many feed-ins ac and dc systems.

(1) the many feed-ins ac and dc systems model corresponding to Jiangsu Power Grid many feed-ins ac and dc systems is built, including 10 Inverter Station；

(2) a certain Inverter Station i is applied disturbance, i=1,2,3,4 ... 10 so that the voltage U of the change of current bus i of this Inverter Station i_iDecline 1%；

(3) voltage variety △ U based on other Inverter Station j_j, calculate three-phase mutual factor M IIF of many feed-ins between Inverter Station i and Inverter Station j_ij, wherein j=1,2,3 ..., n, and j ≠ i；

(4) based on many feed-ins mutual factor M IIF score value (score), calculating the first risk Ra and/or second risk Rb of a certain Inverter Station k, wherein the first risk Ra is the risk that Inverter Station is broken down by other Inverter Station disturbance；And the second risk Rb is the risk causing other Inverter Station to break down during Inverter Station generation disturbance, wherein k=1,2,3 ... 10；With

(5) the first risk Ra and/or Rb are compared with reference value (or standard value), so that it is determined that the risk of Inverter Station i, wherein when Ra is more than or equal to reference value Ra_standard, then it represents that the risk of this Inverter Station is higher than general Inverter Station；Or wherein when Rb is more than or equal to reference value Rb_standard, then it represents that the risk of this Inverter Station is higher than general Inverter Station.In this embodiment, reference value Ra_standard=2.5, Rb_standard=2.5.

Table 1 is the MIIF value between each Inverter Station in many feed-ins ac and dc systems model of Jiangsu Power Grid many feed-ins ac and dc systems, and wherein, first row represents the Inverter Station applying disturbance, and the first row represents each Inverter Station being disturbed.

Table 1

As can be seen from Table 1, south bridge, Hua Xin, the first risk Ra of the western Inverter Station in Shanghai are higher than general Inverter Station higher than general Inverter Station, Taizhou 1000, Hua Xin, Hu Xi, the second risk Rb of Fengxian.

In step (5), further comprising the steps of: for Inverter Station k, by single MIIF_klAnd/or single MIIF_lkFactor reference value MIIF mutual with many feed-ins_standardCompare, wherein as described single MIIF_klAnd/or single MIIF_lkMore than or equal to described reference value MIIF_standard, then it represents that the risk of this Inverter Station is higher than general Inverter Station.Additionally, for Inverter Station k, have 2-5 MIIF_klAnd/or 2-5 MIIF_lkMore than or equal to described reference value MIIF_standardTime, then it represents that the risk of this Inverter Station is high risk.In the present embodiment, mutual factor reference value MIIF_standardIt is 0.4.

As can be seen from Table 1:

Taizhou 500, the risk in Nanjing are higher than general Inverter Station, there is average risk；

There is high risk in Taizhou 1000, south bridge, Hua Xin, Hu Xi, Fengxian.

Below presently preferred embodiments of the present invention has been described in detail, it is understood that after the above-mentioned teachings having read the present invention, the present invention can be made various changes or modifications by those skilled in the art.These equivalent form of values fall within the application appended claims limited range equally.

Claims (10)

1. determine in many feed-ins ac and dc systems a method for interactional risk, its feature between Inverter Station It is, comprises the following steps:

(1) model corresponding to described many feed-ins ac and dc systems, wherein said many feed-ins ac and dc systems bag are built Include n the Inverter Station being electrically connected to each other, and n is the positive integer of >=3；

(2) in the model of described many feed-ins ac and dc systems, a certain Inverter Station i is applied disturbance, I=1,2,3,4 ... n so that the voltage U of the change of current bus i of this Inverter Station i_iDecline 1%；

(3) based on the voltage variety △ U of other Inverter Station j in described many feed-ins ac and dc systems_j, calculate described inverse Become three-phase mutual factor M IIF of many feed-ins between station i and Inverter Station j_ij, wherein j=1,2,3 ..., n, and And j ≠ i；

(4) based on described many feed-ins mutual factor M IIF score value (score), the first wind of a certain Inverter Station k is calculated Danger degree Ra and/or the second risk Rb, wherein the first risk Ra is that described Inverter Station is by other Inverter Station disturbances The risk disturbed and break down；And the second risk Rb is to cause other inverse during described Inverter Station generation disturbance The risk broken down in change station, wherein k=1,2,3 ..., n；With

(5) the first described risk Ra and/or Rb are compared with reference value (or standard value), thus really The risk of one or more Inverter Station in fixed described many feed-ins ac and dc systems,

Wherein when described Ra is more than or equal to described reference value Ra_standard, then it represents that the risk of this Inverter Station is high In general Inverter Station；Or

Wherein when described Rb is more than or equal to described reference value Rb_standard, then it represents that the risk of this Inverter Station is high In general Inverter Station.

2. the method for claim 1, it is characterised in that between described Inverter Station i and Inverter Station j Three-phase mutual factor M IIF of many feed-ins_ijCalculate as follows, wherein as a example by i=1 and j=2:

${\mathrm{\ΔU}}_2=(\frac{{\mathrm{\ΔE}}_2}{X_{N2}}+\frac{{\mathrm{\ΔU}}_1}{X_{12}}+\frac{{\mathrm{\ΔU}}_3}{X_{23}})\·X_{\mathrm{\Σ}}$

$X_{\mathrm{\Σ}}=(\frac{1}{X_{N2}}+\frac{1}{X_{12}}+\frac{1}{X_{23}})$

${\mathrm{MIIF}}_{12}=({\mathrm{\ΔU}}_2/U_2){|}_{{\mathrm{\ΔU}}_1/U_1=1\%}$

In formula, △ E₂Represent the AC system equivalent electromotive force of change of current bus 2, △ U₁With △ U₃Represent respectively and change The voltage of stream bus 1,3, X_N2Represent the equiva lent impedance of the AC system of change of current bus 2 correspondence, X₁₂For the change of current Stand the coupled impedance between 1,2, X₂₃For the coupled impedance between current conversion station 2,3.

3. the method for claim 1, it is characterised in that for a certain Inverter Station k, described First risk Ra calculates as the following formula and judges:

Ra=∑ MIIF_lk, wherein l is the positive integer less than or equal to n, and l ≠ k.

4. the method for claim 1, it is characterised in that described Ra is for described Inverter Station k For all MIIF score value in the mutual factor score of many feed-ins of the highest front m1 position, wherein m1 is 3-10 Arbitrary positive integer.

5. the method for claim 1, it is characterised in that for Inverter Station k, described Two risks Rb calculate as the following formula and judge:

Rb=∑ MIIF_kl, wherein l is the positive integer less than or equal to n, and l ≠ k.

6. method as claimed in claim 5, it is characterised in that described Rb is for described Inverter Station k For all MIIF score value in the mutual factor score of many feed-ins of the highest front m2 position, wherein m2 is 3-10 Arbitrary positive integer.

7. the method for claim 1, it is characterised in that in step (5), further comprising the steps of: For described Inverter Station k, by single MIIF_klAnd/or single MIIF_lkFactor reference value mutual with many feed-ins MIIF_standardCompare,

Wherein as described single MIIF_klAnd/or single MIIF_lkMore than or equal to described reference value MIIF_standard, Then represent that the risk of this Inverter Station is higher than general Inverter Station.

8. method as claimed in claim 7, it is characterised in that described reference value MIIF_standardIt is 0.4.

9. method as claimed in claim 7, it is characterised in that for described Inverter Station k, have 2-5 MIIF_kl And/or 2-5 MIIF_lkMore than or equal to described reference value MIIF_standardTime, then it represents that the risk of this Inverter Station Degree is high risk.

10. method as claimed in claim 7, it is characterised in that described fault includes commutation failure, described Risk include the risk of described Inverter Station generation commutation failure.