CN104569716A - Method for diagnosing bridge arm IGBT open-circuit fault of energy storage converter exteriorly - Google Patents

Abstract

The invention discloses a method for diagnosing the bridge arm IGBT open-circuit fault of an energy storage converter exteriorly. The method comprises the following steps: detecting a three-phase current on the alternating current side of the energy storage converter through a current transformer; calculating the fundamental component, the second harmonic component and the direct current component of the three-phase current through Fourier transform; respectively calculating the second harmonic contents of the three-phase current; when the second harmonic content of any phase in the three-phase current exceeds a preset threshold value, judging that an open-circuit fault occurs in an IGBT of the phase; when the open-circuit fault occurs in the IGBT of any phase in the three-phase current, if the direct current component of the phase is larger than zero, judging that the open-circuit fault occurs in an upper bridge arm IGBT of the phase; if the direct current component of the phase is smaller than zero, judging that the open-circuit fault occurs in a lower bridge arm IGBT of the phase. Based on the second harmonic detection of alternating current and the direct current component detection, the method can accurately and effectively diagnose the bridge arm IGBT open-circuit fault of the energy storage converter, and thus guaranteeing safe and stable operation of an energy storage system.

Description

A kind of method from external diagnosis energy accumulation current converter brachium pontis IGBT open fault

Technical field

The present invention relates to a kind of method from external diagnosis energy accumulation current converter brachium pontis IGBT open fault.

Background technology

There has been many research to voltage source converter fault diagnosis aspect at present, but these researchs all concentrate on DC side translator drives the situation of load, the situation of this and battery energy storage system is different.In addition, traditional voltage source converter method for diagnosing faults all installs detecting element on current transformer, and detection means is more complicated; When current transformer faults itself, can not ensure that the detecting element of its inside can normally work.

Summary of the invention

Battery energy storage unit DC voltage is equal with DC side electrical source voltage, equals each series battery terminal voltage value sum.After open fault occurs energy accumulation current converter IGBT, DC voltage still can keep stable.Therefore, after fault occurs, can't there is the change in very large amplitude in ac-side current, merely adopts the method asking for flip-flop in alternating current there will be the situation of relay fail, effectively cannot carry out detection and Identification to fault.The invention provides a kind of method from external diagnosis current transformer brachium pontis IGBT open fault, after there is IGBT open fault in energy accumulation current converter, external circuit can be relied on to diagnose and to be out of order mutually and fault brachium pontis, timely disconnection AC power supply, prevent DC side battery from damaging by fluctuating power, bring convenience to maintenance simultaneously.

The object of the invention is to be achieved through the following technical solutions: a kind of method from external diagnosis energy accumulation current converter brachium pontis IGBT open fault, comprises the following steps:

(1) energy accumulation current converter AC three-phase current i is detected by current transformer _sa, i _sb, i _sc, current transformer Same Name of Ends is in AC power side, and electric current positive dirction is that AC power points to current transformer;

(2) the fundametal compoment I of three-phase current is calculated by Fourier transform _sa1, I _sb1, I _sc1, second harmonic component I _sa2, I _sb2, I _sc2, DC component I _dca, I _dcb, I _dcc;

(3) the secondary harmonic component THD2 of three-phase current is calculated respectively _a, THD2 _b, THD2 _c:

${\mathrm{THD}2}_a=\frac{I_{\mathrm{sa}2}}{I_{\mathrm{sa}1}}$

${\mathrm{THD}2}_b=\frac{I_{\mathrm{sb}2}}{I_{\mathrm{sb}1}}$

${\mathrm{THD}2}_c=\frac{I_{\mathrm{sc}2}}{I_{\mathrm{sc}1}}---\left(4\right)$ When the secondary harmonic component of a phase any in three-phase current exceedes the threshold value preset, judge that open fault occurs this phase IGBT, namely meet following criterion:

THD2 _x≥THD2 _set

In formula, THD2 _xfor the secondary harmonic component THD2 of three-phase current _a, THD2 _b, THD2 _cin any one, THD2 _setfor the threshold value preset;

After judging that in three-phase, any phase IGBT there occurs open fault, if this phase DC component is greater than zero, i.e. I _dcx>0, in formula, I _dcxfor I _dca, I _dcb, I _dccin correspond to the DC component of fault phase, then judge that in this phase, brachium pontis IGBT there occurs open fault; If this phase DC component is less than zero, i.e. I _dcx<0, then under judging this phase, brachium pontis IGBT there occurs open fault.

Further, the threshold value THD2 preset described in _set>=15%.

The invention has the beneficial effects as follows: by measuring three-phase alternating current at AC side of converter installing current transformer, diagnosing energy accumulation current converter brachium pontis IGBT whether open fault to occur by detecting AC three-phase alternating current, and fault is positioned; Metering circuit is directly installed on outside current transformer, facilitates installation testing, and the protective device of calculating, judgement, action can independent of current transformer work.In addition, what adopt secondary harmonic component criterion and DC component direction criterion not only can judge to break down is separate, can also refer to upper and lower bridge arm is shown, for breakdown maintenance brings convenience; After generation current transformer fault, adopt the device of the inventive method to excise AC power, prevent DC side battery to be subject to secondary damage.

Accompanying drawing explanation

Fig. 1 is the scheme of installation of protective device from the method for external diagnosis current transformer brachium pontis IGBT open fault of the present invention.

Fig. 2 is the logic diagram carrying out the diagnosis of A phase fault from the method for external diagnosis current transformer brachium pontis IGBT open fault of the present invention.

Fig. 3 is the logic diagram carrying out B phase fault from the diagnostic method of external diagnosis current transformer brachium pontis IGBT open fault of the present invention.

Fig. 4 is the logic diagram carrying out C phase fault from the diagnostic method of external diagnosis current transformer brachium pontis IGBT open fault of the present invention.

Embodiment

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

Kind of the present invention, from the method for external diagnosis energy accumulation current converter brachium pontis IGBT open fault, is not only applicable to energy accumulation current converter.

Microcomputer protective relay device is the protective relaying device extensively adopted at present, and it is made up of analogue collection module, switching value acquisition module, CPU (central processing unit), communication module and human-computer interface module etc. usually.

As shown in Figure 1, in the scheme of installation of energy storage unsteady flow bridge IGBT fault diagnosis protective device, the analogue collection module of protective relaying device is connected to current transformer TA1, TA2, TA3, for gathering AC side of converter three-phase current i _sa, i _sb, i _sc; CPU (central processing unit) calculates gathering the three-phase alternating current come and processes, and obtains the secondary harmonic component THD2 of three-phase current _a, THD2 _b, THD2 _cwith DC component I _dca, I _dcb, I _dcc; The switching value acquisition module of protective device is for gathering the state of three-phase breaker switch, and cut-offfing by control of export circuit controls isolating switch.

As shown in Figure 2, the logic of energy storage unsteady flow bridge A phase IGBT open fault diagnosis is specially: when A phase secondary harmonic component meets criterion 1:THD2 _a>=THD2 _set, relay protective scheme is judged to be that A phase there occurs unsteady flow bridge IGBT open fault, and A phase makes alarm prompt.Meanwhile, if the DC component in A cross streams electric current be maximum and on the occasion of, namely meet criterion 2:I _dcaduring >0, relay protective scheme is judged to be that brachium pontis breaks down, and namely in Fig. 1, open fault occurs VT1.Comprehensive criterion 1 and criterion 2 just can be judged to be brachium pontis IGBT open fault in A phase.

Correspondingly, when A phase secondary harmonic component meets criterion 1:THD2 _a>=THD2 _set, relay protective scheme is judged to be that A phase there occurs converter bridge IGBT open fault, and A phase makes alarm prompt.Meanwhile, if the DC component in A cross streams electric current is maximum and is negative value, namely criterion 3:I is met _dcaduring <0, relay protective scheme is judged to be that lower brachium pontis breaks down, and namely in Fig. 1, open fault occurs VT4.Comprehensive criterion 1 and criterion 3 just can be judged to be brachium pontis IGBT open fault in A phase.

For the converter bridge IGBT open fault that B, C two-phase occurs, identical method is adopted to diagnose.

Although content of the present invention has done detailed introduction by above preferred embodiment, will be appreciated that above-mentioned description should not be considered to limitation of the present invention.After those skilled in the art have read foregoing, for multiple amendment of the present invention and substitute will be all apparent.Therefore, protection scope of the present invention should be limited to the appended claims.

Claims (2)

1., from a method for external diagnosis energy accumulation current converter brachium pontis IGBT open fault, it is characterized in that, comprise the following steps:

(1) energy accumulation current converter AC three-phase current i is detected by current transformer _sa, i _sb, i _sc, current transformer Same Name of Ends is in AC power side, and electric current positive dirction is that AC power points to current transformer;

(2) the fundametal compoment I of three-phase current is calculated by Fourier transform _sa1, I _sb1, I _sc1, second harmonic component I _sa2, I _sb2, I _sc2, DC component I _dca, I _dcb, I _dcc;

(3) the secondary harmonic component THD2 of three-phase current is calculated respectively _a, THD2 _b, THD2 _c:

${\mathrm{THD}2}_a=\frac{I_{\mathrm{sa}2}}{I_{\mathrm{sa}1}}$

${\mathrm{THD}2}_b=\frac{I_{\mathrm{sb}2}}{I_{\mathrm{sb}1}}$

${\mathrm{THD}2}_c=\frac{I_{\mathrm{sc}2}}{I_{\mathrm{sc}1}}$ (4) when the secondary harmonic component of a phase any in three-phase current exceedes the threshold value preset, judge that open fault occurs this phase IGBT, namely meet following criterion:

THD2 _x≥THD2 _set

In formula, THD2 _xfor the secondary harmonic component THD2 of three-phase current _a, THD2 _b, THD2 _cin any one, THD2 _setfor the threshold value preset;

After judging that in three-phase, any phase IGBT there occurs open fault, if this phase DC component is greater than zero, i.e. I _dcx>0, in formula, I _dcxfor I _dca, I _dcb, I _dccin correspond to the DC component of fault phase, then judge that in this phase, brachium pontis IGBT there occurs open fault; If this phase DC component is less than zero, i.e. I _dcx<0, then under judging this phase, brachium pontis IGBT there occurs open fault.

2. a kind of method from external diagnosis energy accumulation current converter brachium pontis IGBT open fault according to claim 1, is characterized in that, described in the threshold value THD2 that presets _set>=15%.