CN106370968A - IGBT open circuit fault positioning method for three-phase four-wire system three-leg three-level SVG - Google Patents

Abstract

The invention discloses an IGBT open circuit fault positioning method for a three-phase four-wire system three-leg three-level SVG, which belongs to an IGBT open circuit fault diagnosis method. According to the diagnosis method of the invention, a 3D-SVPWM space vector figure is used, through analyzing offset variations of a system reference vector on a horizontal alpha-beta plane and a vertical 0 axis in an open circuit fault state, the fact that the open circuit fault specifically happens to which IGBT on which phase of leg can be diagnosed. The positioning method comprises two steps: firstly, the equivalent offset of the reference vector on the horizontal alpha-beta plane in the case of open circuit fault is used and the interaction vector trajectory offset is combined to lock whether the fault happens to an A-phase leg, a B-phase leg or a C-phase leg, and the step is called phase positioning; and then, through the offset rule of the interaction vector on the vertical 0 axis in the case of open circuit fault, a pulse state is combined to position the open circuit fault happens to whichever IGBT on the fault leg, and the step is called positioning. The method of the invention has the advantages that neutral current is introduced as a basis for fault diagnosis, and the applicability to the three-phase four-wire system is high; and the fault diagnosis method is applicable to fault diagnosis on an STATCOM and an APF with the same topology structure.

Description

The igbt open fault localization method of three-phase four-wire system three bridge arm tri-level svg

Technical field

The present invention relates to a kind of igbt open fault diagnostic method for svg, particularly one kind are directed to three-phase four-wire system The igbt open fault localization method of three bridge arm tri-level svg.

Background technology

Due to the presence of nonlinear load or part inductive load in industry, create substantial amounts of reactive power breach, lead Power factor is caused to reduce, electric energy efficiency of transmission reduces.For this reason, various reactive power generators are used in local reactive power compensation. Reactive-load compensation substantially can be divided into the switching based on capacitor, compensated based on synchronous motor and the svg based on switching device mends Repay.Svg compensates and can synchronize compensation according to the idle size that scene needs, and is not in showing of undercompensation or overcompensation As, and svg compensation real-time is good, follows the tracks of quick, and has both the function of preventing voltage landing, therefore in terms of reactive-load compensation It is advanced.Therefore, svg also becomes the focus of research.

Svg can be divided into chain type h bridge construction, two level, three level etc. according to topology again.Which kind of, no matter topology, all need Want a number of igbt as power switch component.Because igbt is sensitive to high current, overvoltage and temperature, add control The imperfection of strategy and Preservation tactics is it may appear that damage open circuit, the situation of short circuit.Short trouble frequently results in direct shutdown, opens Road fault impact is smaller, but if found not in time, may result in progression of failure, also reduces the effect of system balance simultaneously Really.Therefore the open fault of igbt is detected it is necessary.

Research has much for the fault detect of igbt, can be largely classified into current methods and voltage method.Current methods Such as park vector method, mean value method etc., current methods generally require the response time of 1-2 power frequency period.Voltage method Typically realized by hardware, rapidity is good, but need extra hardware cost.

Igbt open fault method for two level has a lot, and the open fault for three level is studied seldom.Especially It is when needing to carry out zero sequence current compensation, need to introduce center line, i.e. four-wire system system.

Therefore, much the existing igbt open fault diagnostic method for svg is no longer applicable in three-phase four-wire system.

Content of the invention

The invention aims to providing a kind of igbt open fault for three-phase four-wire system three bridge arm tri-level svg fixed Method for position, solves the problems, such as that the existing igbt open fault diagnostic method for svg is no longer suitable in three-phase four-wire system.

The object of the present invention is achieved like this:

Fault Locating Method comprises the following steps:

Step one, three-phase break down state when, impulse-equivalent trend:

Obtain the reference that in svg system, svpwm controls and give vector u_a、u_b、u_c, and u is decomposed into according to coordinate transform_αPoint Amount, u_βComponent and u₀Component；Wherein u₀Represent zero-sequence component；

Defining pulse condition is

Define v_x'_mFor the current potential to dc bus midpoint m for the x phase brachium pontis output point x under malfunction.When fault occurs and right When current potential impacts, fault potential is equivalent to the effect of other normal burst, and its rule is to work as s_x1During fault, actual given arteries and veins Rush s_x=2 failure effect is equivalent to pulse s_x=1 effect, waits same-action pulse s_xIn minimizing trend (2- > 1)；Work as s_x2Fault When, wait same-action pulse to be in minimizing trend (2- > 0,1- > 0)；Work as s_x3During fault, wait same-action pulse be in increase trend (1- > 2, 0->2)；Work as s_x4During fault, same-action pulse is waited to be in minimizing trend (0- > 1)；

There is open fault phase in step 2, judgement；Specifically comprise the following steps that

u_αComponent, u_βComponent is synthesized together composition u_αβ, represent reference vector projection in the horizontal plane；Draw u_αβRail Mark figure；When the system is normal, svg sends pure reactive power, its u_αβTrajectory diagram assume a circle；When having out in a, b, c three-phase When road fault occurs, u_αβTrack will shift to a, b, c-axis parallel direction；If track offsets to a axle parallel direction, There is open fault in a phase；Track is to other biphase coordinate axess parallel direction skews, then corresponding mutually generation open fault in the same manner；Partially The direction moved can just can be born；

Step 3, determine, in fault phase, specifically which igbt there occurs fault, specifically comprises the following steps that

s_xThere are 2,1,0 three kind of state, therefore (s_a,s_b,s_c) have 27 kinds of states, 27 vectors are drawn by 3/2 conversion Coordinate (u_α*, u_β*, u₀*)；The 3/2 concrete coefficient matrix of conversion is as follows:

The vector obtaining has following rule s_a+s_b+s_c- 3=u₀*, i.e. the algebraical sum of pulse subtracts three and represents reference vector In u₀Projection on axle, the ability to function of corresponding zero-sequence current；

In systems, conductor resistance, l=l are ignored_a=l_b=l_cWhen, in normal state, then have:

v_am=l_a·(di_a/dt)+e_a-l_n·di_n/dt

v_bm=l_b·(di_b/dt)+e_b-l_n·di_n/dt

v_cm=l_c·(di_c/dt)+e_c-l_n·di_n/dt

V is drawn after synthesis_am+v_bm+v_cm=-3l_n·di_n/dt；

Due to v_xmDetermined by pulse under normal circumstances, if i.e. s_x=2, then v_xm=u_dc1；If s_x=1, then v_xm =0；If s_x=0, then v_xm=-udc2；Comprehensively can obtain:

v_xm=s_a*(s_a-1)*u_dc1/2+(s_a-2)*(s_a-1)*(-u_dc2/2)；

Assume u_dc1=u_dc2, then v_xm=1/4 (s_x- 1)

Then 1/4 (s_a+s_b+s_c- 3)=v_am+v_bm+v_cm=-3l_n·di_n/dt；

After fault occurs, in u₀On axle, equipollent vectors also can be to u₀There is unit offset in parallel direction, by this skew To determine concrete igbt abort situation；Define u₀Fault offset vector is:

δ v=3l_n·di_n/dt+1/4(s_a+s_b+s_c-3)；

Step 4, broken down according to which igbt of result of calculation δ v failure judgement phase, specifically comprise the following steps that

Set two threshold values λ₁And λ₂, λ₁Take 0.1* (u_dc1+u_dc2), λ₂Take 0.5* (u_dc1+u_dc2)；

(1) if δ v is negative, occur in two igbt of lower brachium pontis in fault；

If then judging | δ v | > λ₂, then the 4th igbt, i.e. s_x4Open a way；

If λ₁<|δv|<λ₂, then the 3rd igbt, i.e. s_x3Open a way；

(2) if δ v is just, occur in two igbt of upper brachium pontis in fault；

If then judging | δ v | > λ₂, then the 1st igbt, i.e. s_x1Open a way；

If λ₁<|δv|<λ₂, then the 2nd igbt, i.e. s_x2Open a way；

Any one generation open fault positioning of 12 igbt of three-phase brachium pontis completes.

Beneficial effect, due to employing such scheme, this diagnostic method utilizes the three dimensional vector diagram of 3d-svpwm, by dividing Under analysis open fault state, offset variation in horizontal alpha-beta plane and vertical 0 axle for the system reference vector to diagnose open circuit event Concrete which igbt occurring in any phase brachium pontis of barrier；Positioning is divided into two steps: first with reference vector during open fault in level The equivalent offset of alpha-beta plane, and combination vector locus offsets and a phase brachium pontis, b phase brachium pontis or c phase occurs locking fault Brachium pontis, referred to as determines phase；Then, by acting on skew rule on vertical 0 axle for the vector during open fault, and combine pulse condition There is open fault in which igbt concrete carrying out positioning failure brachium pontis, referred to as position.

Traditional igbt open fault diagnostic method, is all with three-wire system as object, is not particularly suited for four-wire system system System.Four-wire system system center line more than three-wire system, and possess zero sequence current compensation ability.The igbt of four-wire system system Open fault diagnostic method does not almost have Research Literature to be related to, and therefore the present invention solves the fault diagnosis of three-phase four-wire system Problem.

Advantage: 1) introduce current in middle wire as the foundation of fault diagnosis, to three-phase four-wire system strong applicability；2) no Need to increase hardware cost；3) method for diagnosing faults is applied to the fault diagnosis of statcom, apf of homeomorphism structure etc..

Brief description:

Fig. 1 is the Troubleshooting Flowchart of the present invention.

Fig. 2 a is the side view of the reference vector exploded view of the present invention.

Fig. 2 b is the top view of the reference vector exploded view of the present invention.

Fig. 3 is the system topology figure of the present invention.

Fig. 4 be the present invention under u α-u β plane during fault equipollent vectors effect deflection graph.

Fig. 5 be the present invention u α-u β plane under reference vector track judgement figure.

Fig. 6 is the space vector of the present invention in u α-u β-u0 coordinate system coordinate diagram.

Fig. 7 a is specific embodiments of the present invention with regard to s in a phase fault_a1The oscillogram of positioning.

Fig. 7 b is specific embodiments of the present invention with regard to s in a phase fault_a2The oscillogram of positioning.

Fig. 7 c is specific embodiments of the present invention with regard to s in a phase fault_a3The oscillogram of positioning.

Fig. 7 d is specific embodiments of the present invention with regard to s in a phase fault_a4The oscillogram of positioning.

Specific embodiment

For the embodiment of more preferable explanation invention, introduce design parameter system to be described.Concrete system example parameter As shown in table 3 below:

Table 3

Fault Locating Method of the present invention comprises the following steps:

Step one, three-phase break down state when, impulse-equivalent trend:

Obtain the reference that in svg system, svpwm controls and give vector u_a、u_b、u_c, and u is decomposed into according to coordinate transform_αPoint Amount, u_βComponent and u₀Component；Wherein u₀Represent zero-sequence component；Schematic diagram is as shown in Figure 2；

Fig. 3 gives the system construction drawing of the three-phase and four-line three bridge arm tri-level svg of this patent design；

Defining pulse condition is

Define v_x'_mFor the current potential to dc bus midpoint m for the x phase brachium pontis output point x under malfunction, table 1 lists all The possible impact that current potential is caused.

Table 1

Be can be seen that when fault occurs and current potential is impacted by observing upper table, fault potential is equivalent to other The effect of normal burst, its rule is to work as s_x1During fault, actual given pulse s_x=2 failure effect is equivalent to pulse s_x=1 Effect, waits same-action pulse s_xIn minimizing trend (2- > 1)；Work as s_x2During fault, same-action pulse is waited to be in minimizing trend (2- > 0,1- >0)；Work as s_x3During fault, same-action pulse is waited to be in increase trend (1- > 2,0- > 2)；Work as s_x4During fault, same-action pulse is waited to be in subtract Few trend (0- > 1)；For vivider expression impulse-equivalent trend, vivider in lower Fig. 4 illustrate that three-phase breaks down During state, in the equivalent action trend of alpha-beta planar pulse.

There is open fault phase in step 2, judgement；Specifically comprise the following steps that

u_αComponent, u_βComponent is synthesized together composition u_αβ, represent reference vector projection in the horizontal plane, schematic diagram is as schemed Shown in 4.Draw u_αβTrajectory diagram；When the system is normal, svg sends pure reactive power, its u_αβTrajectory diagram assume a circle； When there being open fault to occur in a, b, c three-phase, u_αβTrack will shift to a, b, c-axis parallel direction；If track is to a Axle parallel direction offsets, then a phase occurs open fault；Track to other biphase coordinate axess parallel direction skews, then corresponds in the same manner Mutually there is open fault；The corresponding track of 12 igbt open faults judges schematic diagram as shown in figure 5, in figure can clearly be seen Go out, after fault occurs, a part for Circular test shifts, corresponding with the parallel axle in direction of skew fault phase；Skew Direction can just can bear；

Step 3, determine, in fault phase, specifically which igbt there occurs fault, specifically comprises the following steps that

s_xThere are 2,1,0 three kind of state, therefore (s_a,s_b,s_c) have 27 kinds of states, 27 vectors are drawn by 3/2 conversion Coordinate (u_α*, u_β*, u₀*), as shown in table 2 and Fig. 6.The 3/2 concrete coefficient matrix of conversion is as follows:

Table 2

The rule found out from upper table 2 obtains s_a+s_b+s_c- 3=u₀*；It can be seen that, the algebraical sum of pulse subtracts three and represents reference Vector is in u₀Projection on axle, i.e. the ability to function of zero-sequence current；

In system diagram, ignore conductor resistance, l=l_a=l_b=l_cWhen, in normal state, then have:

v_am=l_a·(di_a/dt)+e_a-l_n·di_n/dt

v_bm=l_b·(di_b/dt)+e_b-l_n·di_n/dt

v_cm=l_c·(di_c/dt)+e_c-l_n·di_n/dt

After synthesis, formula can draw v above_am+v_bm+v_cm=-3l_n·di_n/dt；

Due to v_xmDetermined by pulse under normal circumstances, if i.e. s_x=2, then v_xm=u_dc1；If s_x=1, then v_xm =0；If s_x=0, then v_xm=-udc2；Comprehensively can obtain:

v_xm=s_a*(s_a-1)*u_dc1/2+(s_a-2)*(s_a-1)*(-u_dc2/2)；

Assume u_dc1=u_dc2, then v_xm=1/4 (s_x- 1)

Then 1/4 (s_a+s_b+s_c- 3)=v_am+v_bm+v_cm=-3l_n·di_n/dt；

After fault occurs, in u₀On axle, equipollent vectors also can be to u₀There is unit offset in parallel direction, therefore can lead to Cross this and offset to determine concrete igbt abort situation；Define u₀Fault offset vector is:

δ v=3l_n·di_n/dt+1/4(s_a+s_b+s_c-3)；

Step 4, broken down according to which igbt of result of calculation δ v failure judgement phase, specifically comprise the following steps that

Set two threshold values λ₁And λ₂, λ₁Take 0.1* (u_dc1+u_dc2), λ₂Take 0.5* (u_dc1+u_dc2)；

(1) if δ v is negative, occur in two igbt of lower brachium pontis in fault；

If then judging | δ v | > λ₂, then the 4th igbt, i.e. s_x4Open a way；

If λ₁<|δv|<λ₂, then the 3rd igbt, i.e. s_x3Open a way；

(2) if δ v is just, occur in two igbt of upper brachium pontis in fault；

If then judging | δ v | > λ₂, then the 1st igbt, i.e. s_x1Open a way；

If λ₁<|δv|<λ₂, then the 2nd igbt, i.e. s_x2Open a way；

Any one generation open fault positioning of 12 igbt of three-phase brachium pontis completes.

The english abbreviation being related in the present invention and the symbolic interpretation of variable:

Svg: static state reactive generator；

Igbt: insulated gate bipolar transistor；

3d-svpwm: three-dimensional space vectors pulsewidth modulation；

Statcom: STATCOM；

Apf: Active Power Filter-APF；

u_a,u_b,u_c: the reference that in svg system, svpwm controls gives vector；

u_α,u_β,u₀: the reference that in svg system, svpwm controls gives the result through 3/2 conversion for the vector；

u_α*,u_β*,u₀*: the reference that in svg system, svpwm controls gives coordinate under alpha-beta -0 coordinate system for the vector；l_a, l_b,l_c: svg three-phase output equivalent reactance；

i_a,i_b,i_c: svg three-phase output current；

i_n: svg current in middle wire；

e_a,e_b,e_c: electrical network three-phase voltage；

s_x: pulse condition, x can take a, b, c；

v_xm: under normal circumstances, in svg topology, to m point current potential, x can take a, b, c to x point；

v_x'_m: under malfunction, in svg topology, to m point current potential, x can take a, b, c to x point；

v:u₀Fault offset vector on direction of principal axis；

u_dc1,u_dc2: upper d-c bus voltage value and lower d-c bus voltage value；

λ₁: threshold value sets, and takes 0.1* (u_dc1+u_dc2)；

λ₂: threshold value sets, and takes 0.5* (u_dc1+u_dc2)；

s_x1, s_x2, s_x3, s_x4: from top to bottom 4 igbt of x brachium pontis.

Claims (1)

1. a kind of igbt open fault localization method for three-phase four-wire system three bridge arm tri-level svg, is characterized in that: fault is fixed Method for position comprises the following steps:

Step one, three-phase break down state when, impulse-equivalent trend:

Obtain the reference that in svg system, svpwm controls and give vector u_a、u_b、u_c, and u is decomposed into according to coordinate transform_αComponent, u_β Component and u₀Component；Wherein u₀Represent zero-sequence component；

Defining pulse condition is

$s_x=\left\{\begin{array}{cc}2& s_{x1}=on,s_{x2}=on,s_{x3}=off,s_{x4}=off\\ 1& s_{x1}=off,s_{x2}=on,s_{x3}=on,s_{x4}=off\\ 0& s_{x1}=off,s_{x2}=off,s_{x3}=on,s_{x4}=on\end{array}\right.,(x\&element;a,b,c)$

Define v_x'_mFor the current potential to dc bus midpoint m for the x phase brachium pontis output point x under malfunction；When fault occurs and to current potential When impacting, fault potential is equivalent to the effect of other normal burst, and its rule is to work as s_x1During fault, actual given pulse s_x =2 failure effect is equivalent to pulse s_x=1 effect, waits same-action pulse s_xIn minimizing trend (2- > 1)；Work as s_x2During fault, etc. Same-action pulse is in minimizing trend (2- > 0,1- > 0)；Work as s_x3During fault, same-action pulse is waited to be in increase trend (1- > 2,0- > 2)； Work as s_x4During fault, same-action pulse is waited to be in minimizing trend (0- > 1)；

There is open fault phase in step 2, judgement；Specifically comprise the following steps that

u_αComponent, u_βComponent is synthesized together composition u_αβ, represent reference vector projection in the horizontal plane.Draw u_αβTrack Figure；When the system is normal, svg sends pure reactive power, its u_αβTrajectory diagram assume a circle；When having open circuit in a, b, c three-phase When fault occurs, u_αβTrack will shift to a, b, c-axis parallel direction；If track offsets to a axle parallel direction, a Mutually there is open fault；Track is to other biphase coordinate axess parallel direction skews, then corresponding mutually generation open fault in the same manner；Skew Direction can just can bear；

Step 3, determine, in fault phase, specifically which igbt there occurs fault, specifically comprises the following steps that

s_xThere are 2,1,0 three kind of state, therefore (s_a,s_b,s_c) have 27 kinds of states, the coordinate of 27 vectors is drawn by 3/2 conversion (u_α*, u_β*, u₀*)；The 3/2 concrete coefficient matrix of conversion is as follows:

$t=\sqrt{\frac{2}{3}}\left[\begin{array}{ccc}1& -1/2& -1/2\\ 0& \sqrt{3}/2& -\sqrt{3}/2\\ 1/\sqrt{2}& 1/\sqrt{2}& 1/\sqrt{2}\end{array}\right]$

The vector obtaining has following rule s_a+s_b+s_c- 3=u₀*, i.e. the algebraical sum of pulse subtracts three and represents reference vector in u₀ Projection on axle, the ability to function of corresponding zero-sequence current；

In systems, conductor resistance, l=l are ignored_a=l_b=l_cWhen, in normal state, then have:

v_am=l_a·(di_a/dt)+e_a-l_n·di_n/dt

v_bm=l_b·(di_b/dt)+e_b-l_n·di_n/dt

v_cm=l_c·(di_c/dt)+e_c-l_n·di_n/dt

V is drawn after synthesis_am+v_bm+v_cm=-3l_n·di_n/dt；

Due to v_xmDetermined by pulse under normal circumstances, if i.e. s_x=2, then v_xm=u_dc1；If s_x=1, then v_xm=0； If s_x=0, then v_xm=-u_dc2；Comprehensively can obtain:

v_xm=s_a*(s_a-1)*u_dc1/2+(s_a-2)*(s_a-1)*(-u_dc2/2)；

Assume u_dc1=u_dc2, then v_xm=1/4 (s_x- 1)

Then 1/4 (s_a+s_b+s_c- 3)=v_am+v_bm+v_cm=-3l_n·di_n/dt；

After fault occurs, in u₀On axle, equipollent vectors also can be to u₀There is unit offset in parallel direction, come really by this skew Fixed concrete igbt abort situation；Define u₀Fault offset vector is:

δ v=3l_n·di_n/dt+1/4(s_a+s_b+s_c-3)；

Step 4, broken down according to which igbt of result of calculation δ v failure judgement phase, specifically comprise the following steps that

Set two threshold values λ₁And λ₂, λ₁Take 0.1* (u_dc1+u_dc2), λ₂Take 0.5* (u_dc1+u_dc2)；

(1) if δ v is negative, occur in two igbt of lower brachium pontis in fault；

If then judging | δ v | > λ₂, then the 4th igbt, i.e. s_x4Open a way；

If λ₁<|δv|<λ₂, then the 3rd igbt, i.e. s_x3Open a way；

(2) if δ v is just, occur in two igbt of upper brachium pontis in fault；

If then judging | δ v | > λ₂, then the 1st igbt, i.e. s_x1Open a way；

If λ₁<|δv|<λ₂, then the 2nd igbt, i.e. s_x2Open a way；

Any one generation open fault positioning of 12 igbt of three-phase brachium pontis completes.