WO2024047843A1

WO2024047843A1 - Inverter apparatus

Info

Publication number: WO2024047843A1
Application number: PCT/JP2022/032951
Authority: WO
Inventors: 活徳竹内; 真琴松下; 雄一坪井; 優介小杉
Original assignee: 東芝インフラシステムズ株式会社; 東芝三菱電機産業システム株式会社
Priority date: 2022-09-01
Filing date: 2022-09-01
Publication date: 2024-03-07
Also published as: JP7362950B1

Abstract

According to one embodiment of the present invention, an inverter apparatus (100) comprises: a power converter (101) for an armature winding; a power converter (102) for a field winding; a velocity control unit (110) which controls three-phase current on dq-axes; a field current control unit (120) which controls field winding current; a simulator (130); and a damper winding failure detection device (200). The damper winding failure detection unit (200) has: a switching unit (210) which switches between a normal operation mode and a failure inspection mode; an inspection current command value generation unit (220) which outputs an AC as a q-axis current command and outputs a DC equivalent value as a d-axis current command in the failure inspection mode; and an inspection time measurement/determination unit (230) which measures a response in a field winding (13) and determines, from a response signal, the presence or absence of anomaly in the damper winding.

Description

inverter device

The present invention relates to an inverter device.

The stator of a synchronous machine is equipped with a general three-phase armature winding (distributed winding, concentrated winding, wave winding, etc.). Further, a field winding is provided on the rotor, and a field current is supplied through a slip ring or a brushless exciter. During steady operation, where there is no temporal variation in the amplitude or rotational speed of the armature voltage, torque (field torque) is obtained by the interaction between the armature winding and the field winding. Since the field magnetic flux can be freely adjusted by changing the field current, it is possible to always operate with a power factor of 1. Taking advantage of this advantage, it is mainly used as large-capacity motors of 1000 kW class or higher. Furthermore, by adjusting the field magnetic flux, reactive power can also be freely controlled, leading to advance and delay control. For this reason, they are used as main generators in various power plants such as hydropower, thermal power, and nuclear power plants.

In addition to the field winding, the rotor of the synchronous machine is provided with a short-circuit winding called a brake winding. The damper winding is composed of a conductor rod (hereinafter referred to as a "damper bar") that penetrates the iron core of the rotor, and a short-circuit ring that electrically connects each damper bar. Since no power source is connected to the damper winding, no current (damper current) flows during steady operation and there is no electrical effect.

On the other hand, in operating conditions involving slippage, such as when starting a synchronous machine, a damper current is induced using the same principle as in the secondary winding of an induction machine. Inductive torque is generated by the damper current, which can supplement the field torque, making it possible to self-start with acceleration using only commercial power. In addition, induced torque is generated by the damper current during transient operation such as when the voltage or load suddenly changes. In this case, the induced torque is generated in a direction that resists fluctuations in voltage and load, so it is possible to suppress an increase in the load angle and improve the ability to withstand step-out. In this way, the brake winding is essential for stable operation of a synchronous machine.

However, compared to other parts such as the iron core and short-circuit ring, the damper bar has a thin and long structure, so its mechanical strength is relatively weak. Synchronous machines are designed with the mechanical strength of the damper bar in mind, but in very rare cases, the damper bar breaks due to unexpected overload or deterioration over time. Since the damper bar is installed on the rotor core, it is usually not possible to visually determine a failure. If the rotor could be taken out from the stator, it would be possible to visually confirm the failure, but the weight of a 1000 kW class synchronous machine is extremely large, and disassembly work itself is not easy. Therefore, it is necessary to detect the breakage failure of the damper bar in a non-disassembled and non-destructive manner by some electrical method.

In induction machines, methods have been known to detect breakage failures in damper bars (in induction machines, this is called the secondary winding, not the damper winding). All of these methods use the principle that when an induction machine with a broken damper bar is operated with slip s, a current having sidebands at intervals of 2sf flows on both sides of the fundamental frequency f.

On the other hand, since a synchronous machine is normally operated at a synchronous speed, that is, with a slip s of 0, sidebands will not occur even if the damper bar is broken, and this technique cannot be applied.

In the case of a synchronous machine driven by commercial power, a slipping condition occurs when self-starting, so in theory the above diagnostic technique can be applied. However, in the case of a synchronous machine, the 2sf component is also generated due to field magnetic flux and saliency, so it is necessary to distinguish it from the sideband caused by a broken damper bar.

In order to solve this problem, a method has been proposed that focuses on, for example, the one-sided component of the sideband and monitors the temporal change in the amplitude of the one-sided component of the current waveform during startup. Since the change in amplitude over time is different between when the damper bar is healthy and when it is broken, the aim is to detect breakage of the damper bar by measuring it every time it is started and analyzing its changes over time. Furthermore, instead of using the one-sided component of the current waveform, a method has been proposed in which detection is performed using the fact that the current amplitude at startup is reduced due to a breakage failure. Although these methods focus on different physical quantities, they are based on the same idea of ``monitoring a specific physical quantity when the synchronous machine starts up, and detecting breakage based on the difference from the initial value.''

Japanese Patent Application Laid-Open No. 61-112548 Japanese Patent Application Laid-Open No. 61-112548 Japanese Patent Application Publication No. 2000-92792 Patent No. 6722901

By the way, synchronous machines include not only those driven by commercial power sources but also those driven by inverters. For example, inverter-driven synchronous machines are used in synchronous machines that drive rolling mills in steel mills because they require precise torque control over a wide speed range.

In such a synchronous machine, variable voltage variable frequency (VVVF) power is supplied from the inverter, so slippage does not occur even when starting (accelerating). That is, the conventional method of monitoring physical quantities at the time of startup cannot be applied.

It is not impossible to control the inverter and intentionally create a slipping condition similar to that at startup, but at startup, a starting current that greatly exceeds the rated current will flow, and a correspondingly large torque will be generated. This may cause mechanical equipment connected to the synchronous machine to malfunction, which is not practical.

An object of the present invention is to provide an inverter device that can detect breakage failure of a damper bar.

In order to achieve the above object, an inverter device according to an embodiment of the present invention includes a stator having an armature winding, a rotor core, a field winding, a plurality of damper bars, and a short circuit provided at both ends thereof. an inverter device for driving a synchronous machine comprising: a rotor having a brake winding having a ring; an armature winding power converter for supplying power to the armature winding; It has a field winding power converter for supplying power to the field winding, and an armature current control system, and converts the three-phase current supplied by the armature winding power converter on the dq axis. a field current control unit that controls the current of the field winding supplied by the field winding power converter; and a field current control unit that controls the d-axis current and the q-axis current within the speed control unit. A simulator that calculates commands and field current commands used for control, and a brake winding failure detection device that detects a failure of the brake winding, and the brake winding failure detection device is configured to detect a failure of the inverter. a switching unit that switches a state from a normal operation mode to a failure inspection mode and from the failure inspection mode to the normal operation mode; and a switch unit that switches the state from the normal operation mode to the failure inspection mode and from the failure inspection mode to the normal operation mode, and in the failure inspection mode, commands the d-axis current and the q-axis current in the normal operation mode. Instead, a test current command value generation unit outputs a direct current equivalent value as the d-axis current command and an alternating current value as the q-axis current command, and measures a response signal at the field winding. and an inspection measurement/determination unit that determines whether or not there is a failure in the brake winding from the response signal.

FIG. 1 is a block diagram showing the configuration of an inverter device according to a first embodiment. FIG. 2 is a cross-sectional view showing a configuration example of a synchronous machine targeted by the inverter device according to the first embodiment. FIG. 2 is a perspective view showing an example of a brake winding of a synchronous machine targeted by the inverter device according to the first embodiment. FIG. 2 is a configuration diagram for explaining the configuration and operation of a measurement/judgment section during inspection of the inverter device according to the first embodiment. FIG. 3 is a flowchart showing the procedure of a damper bar breakage failure detection method using the inverter device according to the first embodiment. It is a conceptual explanatory view along the circumferential direction showing a case where the damper bar of the synchronous machine targeted by the inverter device according to the first embodiment is healthy. It is a conceptual explanatory view along the circumferential direction showing a case where a breakage failure occurs in a damper bar of a synchronous machine targeted by the inverter device according to the first embodiment. It is a graph which shows the example of distribution of the gap magnetic flux density for each case when the damper bar of the synchronous machine targeted by the inverter device according to the first embodiment is healthy and when a breakage failure has occurred. 7 is a graph showing an example of the distribution of field voltage with respect to the current phase when the damper bar of the synchronous machine targeted by the inverter device according to the first embodiment is healthy and when a breakage failure has occurred. Examples of the distribution of field voltage when the rotor electrical angle changes when the damper bar of the synchronous machine targeted by the inverter device according to the first embodiment is healthy and when a breakage failure has occurred are shown below. This is a graph showing. The results are obtained through multiple inspections when the rotor electrical angle appears randomly, respectively, when the damper bar of the synchronous machine targeted by the inverter device according to the first embodiment is healthy and when the damper bar has a breakage failure. 3 is a graph showing an example of a change in field voltage. FIG. 7 is a configuration diagram for explaining the configuration and operation of an inspection measurement/judgment section of an inverter device according to a second embodiment.

Hereinafter, an inverter device according to an embodiment of the present invention will be described with reference to the drawings. Here, parts that are the same or similar to each other are given the same reference numerals, and redundant explanation will be omitted.

[First embodiment]
FIG. 1 is a block diagram showing the configuration of an inverter device 100 according to the first embodiment. The inverter device 100 is a drive device intended for the synchronous machine 1.

Hereinafter, in the description of each figure showing the configuration of the inverter device 100, the input/output signal of each element is expressed, for example, as "angular velocity command" ω ^* . Regarding input/output signals, in detail, since the signal name and the signal level value are different things, it is correct to express them separately. However, since the expression is complicated, for example, ω ^* indicates the "angular velocity command signal" and also indicates the "level value of the angular velocity command signal", and both are collectively expressed as "angular velocity command". Note that the name and level value of the feedback signal are also shown together.

Also, among the symbols representing each physical quantity, those with the suffix "*" represent command values, and the others represent feedback values or calculated values.

Inverter device 100 adjusts armature currents Iu, Iv, Iw, and field _current if with respect to angular velocity command ω ^* and magnetic flux command Φ ^* . The inverter device 100 is roughly divided into an armature winding power converter 101, a field winding power converter 102, a speed control section 110, a field current control section 120, a simulator 130, and a brake winding failure detection device. It has 200.

The armature winding power converter 101 is a VVVF (variable voltage variable frequency) power source such as an inverter, and receives power from an AC power source such as a commercial power source (not shown), and converts the armature winding 22 of the synchronous machine 1 to supply power.

The field winding power converter 102 is a DC power supply, receives power from an AC power supply (not shown), and supplies DC power to the field winding 13 of the synchronous machine 1.

The speed control unit 110 includes a subtracter 111, a speed calculator 112, a speed controller 113, and an armature winding current control system 110a. The speed control unit 110 has a cascade control configuration including an armature winding current control system 110a as a minor loop for obtaining the corresponding torque current i _T ^* under the speed control loop for obtaining the angular velocity command ω ^* It becomes. The speed control unit 110 outputs a voltage command to the armature winding power converter 101 through the armature winding current control system 110a, and converts the three-phase current supplied by the armature winding power converter 101 into dq Control on axis.

The armature winding current control system 110a includes a dq-axis current calculator 114, a subtracter 115, a subtracter 116, a 3-phase-dq converter 117, a dq-axis current controller 118, and a dq-3-phase converter 119.

The subtracter 111 of the speed control unit 110 converts the rotation angle Θ of the synchronous machine 1 measured by the rotation angle detector 106 (resolver, encoder, etc.) and calculated by the position calculator 107 into an angular velocity converted by the speed calculator 112. Let ω be a negative feedback signal, and output the angular velocity deviation subtracted from the angular velocity command ω ^* . The speed controller 113 receives the angular velocity deviation and the magnetic flux command Φ ^* as input, and outputs a torque current command i _T ^* .

The dq-axis current calculator 114 receives the torque current command i _T ^* and calculates a d-axis current command i _d ^* and a q-axis current command i _q ^* . At this time, the dq-axis current calculator 114 uses the load angle δ calculated by the simulator 130. In this embodiment, the load angle δ is used to generate the d-axis current command i _d ^* and the q-axis current command i _q ^* , but these may be any physical quantities or calculated values that can be generated. That is, for example, the simulator calculates the current phase angle (the tangent of the d-axis current and the q-axis current), inputs it to the dq-axis current calculator 114, and calculates the d-axis current command i _d ^* and the q-axis current command i A configuration that generates _q ^* may also be used.

The three-phase-dq converter 117 converts the armature phase currents Iu, Iv, and Iw detected by the armature current detector 104 into _{a q-} axis current iq and a d-axis current _id . The three-phase-dq converter 117 uses the rotation angle Θ, which is the output of the position calculator 107, during this conversion. The q-axis current i _q and the d-axis current i _d obtained by the three-phase-dq converter 117 are input as feedback signals to the subtracter 115 and the subtracter 116 .

The subtracter 115 receives the d-axis current command i _d ^* and the d-axis current _{i d} as a feedock signal as input, and outputs a d-axis current deviation obtained by subtracting the d-axis current i _d from the d-axis current command i _d ^* . do. The subtracter 116 receives the q-axis current command i _q ^* and the q-axis current i _q as a feedock signal as input, and outputs a q-axis current deviation obtained by subtracting the q-axis current i _q from the q-axis current command i _q ^* . do.

The dq-axis current controller 118 receives the d-axis current deviation from the subtracter 115 and the q-axis current deviation from the subtracter 116 as input, and calculates the d-axis voltage command V _d ^* and the q-axis voltage command V _q ^*. and output.

The dq-3 phase converter 119 converts the d ^{-axis voltage command V d * and the q-axis voltage command V q *} _calculated _by ^the dq-axis current controller 118 into the voltage commands Vu ^* , Vv ^* , Vw of each of the three phases. Convert to ^* . The armature winding power converter 101 generates three-phase armature voltages Vu, Vv, and Vw that are proportional to the voltage commands Vu ^* , Vv ^* , and Vw ^* for each of these three phases, and supplies them to the synchronous machine 1. . As a result, phase currents Iu, Iv, and Iw flow through the armature winding 22 of the synchronous machine 1. These phase currents Iu, Iv, and Iw are each detected by armature current detector 104.

The field current control unit 120 receives the magnetic flux command Φ ^* and the feedback signal of the field current i _f and calculates the field current command i _fd ^* , and the field current controller 121 calculates the field current command i fd *. A field voltage command V _f ^* is calculated from _fd ^* and output to the field winding power converter 102 . The field winding power converter 102 generates a field voltage V _f proportional to the field voltage command V _f ^* , and supplies it to the field winding 13 of the synchronous machine 1 . As a result, a field _current if flows through the field winding 13 of the synchronous machine 1. This field current _if is detected by a field current detector 105.

The simulator 130 calculates and outputs a load angle command δ ^* and a field current command i _{fd *} ^from the magnetic flux command Φ ^* and the field current i _fd which is a feedback signal. For this calculation, for example, in the example of FIG. 1, the d-axis current i _d , the q-axis current i _q , and the torque command are also accepted as inputs. Here, the field current i _fd is the field current converted to the armature side. The simulator 130 is configured by, for example, a dq-axis equivalent circuit or a look-up table. Note that the load angle command δ ^* may be replaced with any physical quantity or calculated value in accordance with the input of the dq-axis current calculator 114. That is, the simulator 130 only needs to be able to generate an auxiliary signal for generating the d-axis current command i _d ^* and the q-axis current command i _q ^* in the dq-axis current calculator 114.

The brake winding failure detection device 200 detects failures in the brake winding 16 (FIG. 3), such as breakage of the damper bar 14 (FIG. 2) provided on the rotor 10 of the synchronous machine 1. The brake winding failure detection device 200 includes a switching section 210, a test current command value generation section 220, and an inspection measurement/determination section 230.

The switching unit 210 switches the state of the inverter device 100 from the normal operation mode to the failure inspection mode and from the failure inspection mode to the normal operation mode.

In the failure inspection mode, the inspection current command value generation unit 220 generates a d-axis current command i _d ^* and a q-axis current command i _q ^* in place of the output of the dq-axis current calculator 114 in the normal operation mode, and performs switching. The subtracter 115 and the subtracter 116 are output via the subtracter 210 .

The test current command value generation section 220 includes an alternating current command section 221 and a zero current command section 222.

The alternating current command unit 221 generates an alternating current as a q-axis current command i _q ^* . Here, the alternating current is a periodic signal having an arbitrary waveform such as a sine wave, a rectangular wave, a triangular wave, or a sawtooth wave.

The zero current command section 222 outputs a zero value as the d-axis current command i _d ^* . Here, an example is shown in which a zero value is used as the command value of the zero current command unit 222, but if the command value does not result in an alternating current, there will be no problem with the detection operation, so it simulates a direct current instead of an alternating current. It is also possible to substitute a current command with a value equivalent to DC, that is, a value equivalent to DC.

Note that the inverter device 100 described above may be provided with a filter, an internal loop, and various arithmetic units that are not shown in FIG. 1 in order to obtain desired characteristics. Furthermore, each input/output signal within the controller may be converted into an equivalent arbitrary signal. For example, instead of the actual physical value, a normalized value proportional to it (such as normalization using the unit method) is used, instead of torque, output (torque multiplied by the number of revolutions) is used, and instead of magnetic flux, voltage is used. (magnetic flux multiplied by the number of rotations), use d-axis magnetic flux and q-axis magnetic flux instead of load angle (load angle is the tangent of d-axis magnetic flux and q-axis magnetic flux), etc. .

FIG. 2 is a cross-sectional view showing a configuration example of the synchronous machine 1 targeted by the inverter device 100 according to the first embodiment.

The synchronous machine 1 has a rotor 10 and a stator 20.

The rotor 10 includes a rotor shaft 11 rotatably supported on both sides in the axial direction by two bearings (not shown), a rotor core 12 provided on the radially outer side of the rotor shaft 11, and a plurality of convexes on the rotor core 12. There are six damper bars 14 each passing through the rotor core 12 in the vicinity of the radial ends of the field windings 13 wound around the respective portions 12a and the convex portions 12a of the rotor core 12.

The stator 20 includes a cylindrical stator core 21 provided on the radially outer side of the rotor 10 via a gap space 30, and a plurality of stator teeth 21a formed on the inner peripheral surface of the stator core 21. It has a turned armature winding 22. Note that the stator 20 is normally housed in a space formed by a frame (not shown) that supports a bearing or a bearing bracket (not shown).

Although FIG. 2 shows an example in which the rotor has a six-pole structure, the number of poles, the number of slots, the number of windings, and the number of damper bars are arbitrary. Further, although FIG. 2 shows a salient pole type synchronous machine, a cylindrical synchronous machine similarly provided with a damper bar can also be used as the synchronous machine targeted by the inverter device 100.

FIG. 3 is a perspective view showing an example of the brake winding 16 of the synchronous machine 1 targeted by the inverter device 100 according to the first embodiment.

The damper winding 16 includes a plurality of damper bars 14 passing through the rotor core 12 in the axial direction at each pole, and is provided at both ends of the damper bars 14 in the axial direction to mechanically and electrically connect the damper bars 14. It has two short circuit rings 15 connecting the two.

Each of the six damper bars 14 provided on each of the six poles of the rotor 10 passes through the convex portion 12a of the rotor core 12, and then the entirety is mechanically coupled to the shorting ring 15 provided at both ends. connected and electrically shorted.

Here, the number, length, and cross-sectional shape of the damper bars 14 are arbitrary, and there are no restrictions as long as they satisfy the electrical properties as the damper winding 16. For example, instead of forming the short circuit ring 15 with a ring-shaped conductor, a structure may be adopted in which a conductor plate is provided at the end of the shaft. Further, in many cases, the damper bar 14 and the short-circuit ring 15 are assembled by welding, fitting, etc. copper materials, but they may be integrally molded such as aluminum die-casting.

FIG. 4 is a configuration diagram for explaining the configuration and operation of the inspection measurement/judgment section 230 of the inverter device 100 according to the first embodiment.

The armature winding 22, the power converter 101 on its power supply side, and the armature winding current control system 110a have already been described with reference to FIG. 1, so their description will be omitted here.

The field winding 13 of the rotor 10 is drawn out of the stator 20 via a slip ring (not shown) or the like, and is connected to the field winding power converter 102.

A field current detector 105 for detecting a feedback signal of the field current shown in FIG. 1 is provided in the circuit connecting the field winding 13 and the field winding power converter 102.

An inspection measurement/judgment section 230 is provided on the output side of the field current detector 105.

The inspection measurement/determination section 230 includes a field voltage detector 231, and a computing unit 233, a determination device 234, and an alarm indicator 235 that constitute the failure determination section shown in FIG.

The field voltage detector 231 is provided for the purpose of stepping down the voltage to a level that can be input to the arithmetic unit 233, and uses, for example, a transformer (PT), a resistive voltage divider, or the like.

The arithmetic unit 233 has a part that performs a Fourier transform function, and outputs an amplitude equivalent of a component synchronized with the fundamental frequency of the alternating current in the failure inspection mode. Note that instead of the Fourier transform, an effective value (rms value), an average rectified effective value (mean value), or other calculations that can obtain an amount equivalent to the amplitude of the AC voltage may be used. Furthermore, the computing unit 233 stores a certain number of values of the input signal (for example, the values of the past 10 points from the latest value) or a certain period of time (for example, the values of the past week from the latest value). , perform numerical processing (for example, calculation of integral and differential) and statistical processing (for example, calculation of arithmetic mean, geometric mean, variance, etc.) on the value.

The determiner 234 accepts the output of the arithmetic unit 233 as an input signal. The determiner 234 compares the numerically/statistically processed value with a threshold set in advance for the synchronous machine 1, and if the numerically/statistically processed value exceeds the threshold, the damper bar 14 It is determined that a breakage has occurred. At this time, a signal indicating the abnormality is output to the failure indicator. The threshold value is determined by calculation or testing, and the setting can be changed.

The alarm display 235 is composed of, for example, a liquid crystal display, and upon receiving the abnormality signal from the determiner 234, displays a display indicating a failure.

Note that the arithmetic unit 233 and the determiner 234 may be configured with a digital circuit such as an FPGA (Field Programmable Gate Array) or a PC (Personal Computer). Alternatively, it may be configured with an analog circuit using an operational amplifier or the like.

In addition, if the environment in which the synchronous machine 1 is installed is not in a good condition from the viewpoint of electromagnetic noise, in order to avoid false detection, it is necessary to A filter or shield may be provided as necessary. Further, when the synchronous machine 1 is operated at high voltage, an insulation circuit or a protection circuit may be provided as necessary.

FIG. 5 is a flowchart showing the steps of a damper bar breakage failure detection method using the inverter device according to the first embodiment.

First, the synchronous machine 1 is brought to a stopped state (step S10). That is, the rotor 10 is not rotated, and the field winding 13 and the armature winding 22 are not energized.

Next, the field winding power converter 102 on the power source side of the field winding 13 is brought to a stopped state (step S20). The gate of the semiconductor element of the field winding power converter 102 may be turned off (gate blocked). Alternatively, if a disconnector is provided between the field winding 13 and the field winding power converter 102, the disconnector may be opened.

Next, the switching unit 210 switches to failure inspection mode (step S30).

Next, the following operations are performed in the failure inspection mode (step S40).

First, the alternating current command section 221 of the test current command value generation section 220 causes an alternating current to flow through the armature winding 22 in the q-axis direction (direction between magnetic poles) of the rotor 10 (step S41). On the other hand, zero current flows through the armature winding 22 in the d-axis direction of the rotor 10 by the zero current command unit 222 . That is, no current flows in the d-axis direction of the rotor 10.

Next, the field voltage detector 231 measures the induced voltage induced in the field winding 13 (step S42).

Next, the calculator 233 derives the amplitude value of the synchronous component with the alternating current for the induced voltage induced in the field winding 13 (step S43).

Next, the determiner 234 determines whether there is a breakage failure of the damper bar 14 (step S44). That is, the amplitude value derived by the determiner in step S43 is compared with a threshold value, and if the amplitude value exceeds the threshold value, it is determined that a breakage failure of the damper bar 14 has occurred, and an abnormality signal is output.

FIG. 6 is a conceptual explanatory diagram along the circumferential direction showing a case where the damper bar 14 of the synchronous machine 1 targeted by the inverter device 100 according to the first embodiment is healthy. FIG. 6 is a diagram schematically showing the damper bar 14 and the short-circuit ring 15 of two adjacent magnetic poles centered on the q-axis developed along the circumferential direction.

As shown in Fig. 6, when the damper bar 14 is healthy, the q-axis alternating magnetic flux generated by the armature current (magnetic flux density distribution that is maximum at Ca (on the q-axis) in Fig. 6) is distributed in the damper winding. 16, a damper current is induced in the damper winding 16 composed of the damper bar 14 and the short-circuit ring 15 so as to cancel it. Since the loop through which this current flows is symmetrical with respect to the q-axis as shown in Figure 6, the direction of the magnetomotive force created by the damper current is also the direction of the q-axis (Ca in Figure 6 (on the q-axis)), which is the maximum. magnetic force distribution). This means that axis Ca overlaps axis Cd, and the magnetomotive force created by the damper current only has the effect of canceling the q-axis alternating magnetic flux generated by the armature current, and does not act on the d-axis. , no d-axis magnetic flux is generated.

FIG. 7 is a conceptual explanatory diagram along the circumferential direction showing a case where a breakage failure occurs in a damper bar of a synchronous machine targeted by the inverter device according to the first embodiment.

If a part of the damper bar is broken as shown in Figure 7, no current will flow through that bar. Therefore, the damper current induced in the damper winding 16 flows to the adjacent damper bar etc. so as to bypass the broken point. In this case, the center of the loop through which the damper current flows will be shifted from the q-axis. That is, in FIG. 7, the magnetomotive force produced by the damper current is maximum at the axis Cd located at a position offset from the q-axis.

As a result, the damper current not only has the effect of canceling the q-axis magnetic flux, but also has the effect of generating magnetic flux on the d-axis. In other words, even though only the q-axis armature current is flowing, a d-axis magnetic flux is generated. This is called interference between d and q axes. Since the d-axis alternating magnetic flux generated by the interference between the d and q axes interlinks with the field winding, a field voltage that should not occur if the brake winding 16 is healthy will occur in this case. Become.

FIG. 8 is a graph showing an example of the gap magnetic flux density distribution when the damper bar 14 of the synchronous machine 1 targeted by the inverter device according to the first embodiment is healthy and when a breakage failure has occurred. It is. The horizontal axis is the mechanical angle (degrees) at the rotor 10, and the vertical axis is the gap magnetic flux density (T).

In FIG. 8, the curve shown by a broken line shows a case where the damper bar 14 is in a healthy state, and the curve shown by a solid line shows a case where a part of the damper bar 14 is broken. As shown in FIG. 8, when the damper bar 14 is healthy, the magnetic flux density is point symmetrical at the center of the figure (horizontal axis 90 degrees, vertical axis 0T). On the other hand, when a portion of the damper bar 14 is broken, the gap magnetic flux density is not point symmetrical. This indicates that not only the magnetic flux distribution on one axis (q-axis) but also the magnetic flux component on the other axis (d-axis) is occurring.

FIG. 9 shows an example of the distribution of field voltage with respect to the current phase when the damper bar of the synchronous machine targeted by the inverter device according to the first embodiment is healthy and when a breakage failure has occurred. It is a graph. The horizontal axis shows the electrical angle (degrees) at the rotor 10, and the vertical axis shows the field voltage (V).

In FIG. 9, the curve shown by a broken line shows a case where the damper bar 14 is in a healthy state, and the curve shown by a solid line shows a case where a part of the damper bar 14 is broken. As shown in FIG. 9, the distribution of field voltage when a part of the damper bar 14 is broken is clearly out of phase from the distribution of field voltage when the damper bar 14 is in a healthy state. I can see that In other words, the field current at a rotor electrical angle of 90 degrees (i.e., q-axis) is zero when the damper bar 14 is healthy, but when a part of the damper bar 14 is broken, it becomes significant. The value ΔV is shown.

Therefore, in short, the determination unit 234 determines whether or not ΔV is higher than a predetermined threshold, thereby determining whether or not the damper bar 14 has a breakage failure.

FIG. 10 shows the field when the rotor electrical angle changes when the damper bar 14 of the synchronous machine 1 targeted by the inverter device 100 according to the first embodiment is healthy and when a breakage failure has occurred. It is a graph showing an example of distribution of magnetic voltage.
The results shown in FIGS. 8 and 9 shown above are changes in field voltage when the rotor 10 is fixed at a certain position (angle). In reality, it is not easy to make the position of the rotor 10 exactly the same, so it is assumed that the mode shifts to the failure inspection mode at an arbitrary position. In this case, since there are magnetic irregularities caused by the slots of the stator core 21, the detected value fluctuates due to the difference in relative position between the stator 20 and the rotor 10. FIG. 10 shows this. Even if an alternating current with the same amplitude and frequency is applied, the amplitude of the field voltage will be different. Therefore, if the rotor 10 can be in any position, a voltage difference will be seen between the healthy state and the faulty state, but it is possible to determine a fault by just trying the fault inspection mode once (measuring the field voltage once). is difficult.

FIG. 11 shows that the rotor position (converted to electrical angle) is random when the damper bar of the synchronous machine targeted by the inverter device according to the first embodiment is healthy and when a breakage failure has occurred. 3 is a graph showing an example of a change in field voltage obtained through multiple tests in the case where the above occurs.
The points plotted in FIG. 11 are pseudo-calculated field voltage detection values assuming that the measurement results in FIG. 10 appear randomly and that multiple inspections have been performed. It is assumed that the failure occurred at the 800th time, and a clear difference in the trends can be seen. The solid line in FIG. 11 is a moving average (arithmetic average) of 10 points calculated for the plotted points. After the 800th time that a failure occurred, a clear difference can be seen between the sound state of the damper bar before that point and the broken state of the damper bar after that point. In this way, even if there is a fluctuation in the field voltage detection value, rather than judging the detection signal as it is, it can be determined by going through some kind of numerical/statistical processing, such as based on the trend of the field voltage detection value shown in Figure 11. , failures can be detected.

As described above, the damper winding failure detection device 200 of the inverter device 100 according to the present embodiment detects a breakage failure of the damper bar 14 without disassembling the synchronous machine 1 using the principle of interference between d and q axes. be able to.

In the inverter device 100 according to the present embodiment, in order to detect a breakage failure of the damper bar 14, an alternating current is simply passed through the q-axis of the armature winding 22, so almost no torque is generated and the rotor is stationary. It is possible to maintain the condition.

[Second embodiment]
FIG. 12 is a configuration diagram for explaining the configuration and operation of the inspection measurement/judgment section 230a of the inverter device 100a according to the second embodiment.

This embodiment is a modification of the first embodiment, and the inverter device 100a differs from the first embodiment in the inspection measurement/determination section 230a.

The inspection measurement/judgment unit 230a according to this embodiment includes a field current detector 105, a calculator 233a, a determiner 234a, an alarm indicator 235, and a contactor 236.

The field current detector 105 is composed of devices that measure current as voltage, such as a shunt resistor, current transformer (CT), and Hall CT.

In addition, in FIG. 12, the field current detector 105 is a detector for detecting a feedback signal of the field current in the field current control section 120, but the field current detector 105 is a detector for detecting a feedback signal of the field current in the field current control section 120. A separate container may also be provided.

In addition, if the environment in which the synchronous machine 1 is installed is not in a good condition in terms of electromagnetic noise, a filter or shield may be installed as necessary to avoid false detection, or a filter or shield may be installed as necessary. Similar to the first embodiment, an insulation circuit or a protection circuit may be provided as necessary when the second embodiment is operated at a high voltage.

The contactor 236 is provided between the field winding 13 and the field winding power converter 102. The contactor 236 is automatically turned on when the switching unit 210 switches to the failure inspection mode, and the field winding 13 is placed in a short-circuited state. Note that instead of providing the contactor 236, the short circuit may be achieved by turning on (conducting) the gate of the semiconductor element of the power converter 102.

In the failure inspection mode, an induced voltage is generated in the field winding 13 when the brake winding 16 is in failure, as in the first embodiment. In this embodiment, since the field winding 13 is short-circuited, a field current is induced by the induced voltage.

This field current is measured by the field current detector 105, and its output is input to the calculator 233a. While the inspection measurement/judgment section 230 in the first embodiment detects failures based on voltage values, the inspection measurement/judgment section 230a of the present embodiment makes judgments based on current values.

According to the embodiments described above, it is possible to provide an inverter device that makes it possible to detect a breakage failure of a damper bar.

[Other embodiments]
Although the embodiments of the present invention have been described above, the embodiments are presented as examples and are not intended to limit the scope of the invention. Moreover, the features of each embodiment may be combined. Furthermore, the embodiments can be implemented in various other forms, and various omissions, substitutions, and changes can be made without departing from the gist of the invention. The embodiments and their modifications are included within the scope and gist of the invention as well as within the scope of the invention described in the claims and its equivalents.

DESCRIPTION OF SYMBOLS 1... Synchronous machine, 10... Rotor, 11... Rotor shaft, 12... Rotor core, 12a... Convex part, 13... Field winding, 14, 14a... Damper bar, 15... Short circuit ring, 16... Brake winding , 20... Stator, 21... Stator core, 21a... Stator teeth, 22... Armature winding, 30... Gap space, 100, 100a... Inverter device, 101... Power converter for armature winding, 102... Field winding power converter, 103... Breaker, 104... Armature current detector, 105... Field current detector, 106... Rotation angle detector, 107... Position calculator, 110... Speed controller, 110a ...Armature winding current control system, 111...Subtractor, 112...Speed calculator, 113...Speed controller, 114...DQ-axis current calculator, 115, 116...Subtractor, 117...3-phase-dQ converter, 118... dq axis current controller, 119... dq-3 phase converter, 120... field current controller, 121... field current controller, 130... simulator, 200... damper winding failure detection device, 210... switching unit , 220... Inspection current command value generation unit, 221... Alternating current command unit, 222... Zero current command unit, 230, 230a... Measurement/judgment unit during inspection, 231... Field voltage detector, 233, 233a... Arithmetic unit, 234, 234a... Judgment device, 235... Alarm indicator, 236... Contactor

Claims

A synchronous machine comprising a stator having an armature winding, and a rotor having a rotor core, a field winding, and a damper winding having a plurality of damper bars and short circuit rings provided at both ends thereof. An inverter device for driving,
an armature winding power converter for supplying power to the armature winding;
a field winding power converter for supplying power to the field winding;
a speed control unit having an armature current control system and controlling the three-phase current supplied by the armature winding power converter on the dq axis;
a field current control unit that controls the current of the field winding supplied by the field winding power converter;
a simulator that calculates a command and a field current command used when controlling the d-axis current and the q-axis current in the speed control unit;
a brake winding failure detection device that detects a failure of the brake winding;
Equipped with
The brake winding failure detection device includes:
a switching unit that switches the state of the inverter device from a normal operation mode to a failure inspection mode and from the failure inspection mode to the normal operation mode;
In the failure inspection mode, instead of the d-axis current and q-axis current commands in the normal operation mode, a direct current equivalent value is output as the d-axis current command, and an alternating current is output as the q-axis current command. a test current command value generation unit to output;
an inspection measurement/judgment unit that measures a response signal in the field winding and determines whether or not there is a failure in the brake winding from the response signal;
An inverter device comprising:
The inspection measurement/judgment section includes:
a voltage detector that detects the voltage of the field winding;
an arithmetic unit that calculates an amplitude equivalent of the output of the voltage detector;
a comparator that compares the output of the arithmetic unit with a predetermined threshold value to determine whether it is large or small;
The inverter device according to claim 1, comprising:.
The inspection measurement/judgment section includes:
an arithmetic unit that calculates an amplitude equivalent of the field current detected by the field current control unit;
a comparator that compares the output of the arithmetic unit with a predetermined threshold value to determine whether it is large or small;
The inverter device according to claim 1, comprising:.
The inverter device according to claim 2 or 3, wherein the arithmetic unit calculates the amplitude of a component synchronized with a fundamental frequency of the alternating current by Fourier transform of the response signal.
The inverter device according to claim 2 or 3, wherein the arithmetic unit calculates a total effective value of the response signal.
3. The computer according to claim 2, wherein the arithmetic unit holds a certain number of calculated values equivalent to the amplitude, counting from the latest value, and applies numerical and statistical processing to the set of the held values. The inverter device according to claim 3.
The inverter device according to any one of claims 1 to 6, wherein the alternating current is a sine wave.