JPS6026470B2 - Ground fault detection device for brushless rotating electric machines - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is a brushless rotating electric machine that enables detection of grounding faults in the field circuit and evaluation of grounding points by measuring ground resistance (insulation resistance) in a non-contact state. The present invention relates to a ground fault detection device for rotating electric machines.

As a result, the need for brushless rotating electric machines is increasing, and along with this, there is an increasing demand for failure detection and protection of the rotor portion thereof.

For example, a grounding failure in a field circuit in a synchronous machine such as a brushless turbine generator has a high risk of eventually leading to a serious accident. Therefore, detecting such grounding faults early and taking appropriate countermeasures is very advantageous both economically and in terms of time, and also leads to an increase in the operating rate of the plant. By the way, conventionally, detection of a grounding failure in the field circuit in a synchronous machine such as a turbine generator is carried out by temporarily stopping the operation of the synchronous machine and measuring the insulation resistance between the field circuit and the shaft. Ta. In addition, although it is relatively easy to measure the insulation resistance of brushless rotating electric machines after they have stopped,
It is relatively difficult to detect the presence or absence of a grounding fault under certain conditions, and even if it is possible to detect the presence or absence of a grounding fault, the current situation is that it is almost impossible to detect the location or extent of the fault. The present invention has been developed in consideration of the above-mentioned circumstances, and is capable of detecting a grounding failure of a field circuit in a brushless rotating electrical machine and measuring its grounding resistance without contact. Among other things, it is an object of the present invention to provide a ground fault detection device for a brushless rotating electric machine that is capable of detecting ground faults and also evaluating grounding points.

Hereinafter, one embodiment of the present invention will be described with reference to the drawings.

FIG. 1 shows an example of a configuration in which a battery fault detection device according to the present invention is applied to a brushless synchronous generator. In FIG. 1, 1 is a synchronous generator equipped with a field winding 11. 2 is an AC exciter equipped with an armature winding 21 installed on the same axis as the rotating shaft of the synchronous generator 1, and a field winding 22 connected to an excitation power source 23, and the AC exciter 2 has an AC output. A rotary rectifier 3 mounted on the rotating shaft of the synchronous generator 1 rectifies the current and supplies it to the field winding 11.

Further, 4 is a rotary transformer, the primary winding 42 of which is connected to a variable power source 41, and the secondary winding 43 connected to the AC side terminal of the rectifier 5.

In addition, the DC side e terminal of this rectifier 3 is grounded to the rotating shaft, and the DC side terminal (3) is connected to the rotor side excitation coil 61 and the resistor 7, which are one component of the non-contact detection device 6, in series. The auxiliary circuit is connected to point B in the figure on the other side of the field main circuit. In this case, the secondary winding 43 of the rotary transformer 4, the rectifier 5, the excitation coil 61, and the resistor 7 are mounted on the same axis as the rotating shaft of the synchronous generator 1, respectively. The non-contact detection device 6 is electromagnetically coupled to the rotor-side excitation coil 61 on the stator side through a predetermined gap to detect the current flowing through the rotor-side excitation coil 61, that is, the ground current id. and a detector 62 that generates a signal proportional thereto. On the other hand, 8 is an insulation resistance measuring device whose details will be described later, which inputs the primary side voltage signal v of the rotary transformer 4, the exciting current signal if of the AC exciter 2, and the output current signal id' of the detector 62, respectively. The output is sent to a display device 9 such as an indicator, an alarm, or a relay. FIG. 2 shows a detailed configuration example of the insulation resistance measuring device 8. As shown in FIG.

81 is the primary side voltage signal V, excitation current signal if,
This is a signal conversion device that generates a signal obtained by correcting the output current signal id' by a certain positive value.

That is, the primary side voltage signal v, is a voltage signal Vd corrected to the ground voltage of the rectifier 6, and the exciting current signal if is a voltage signal Vr corrected to the world voltage of the rotary rectifier 3, and further output. The current signal id' is sent out as a current signal jd which is compared to the ground current. Further, 82 is a ground current surge point detector which detects a sudden increase in the current signal id and closes its normally open contact 82a.

83 is a storage device that stores the voltage signal Vd when the normally open contact 82a is closed as a constant value Vd.

On the other hand, 84 is the voltage signal f and the output signal Vd of the storage device 83.
, is the first arithmetic unit that performs division (Vd, /Vr), and its output is sent to a display device (not shown) as a value a.
’.

Furthermore, 85 is the voltage signal Vd and the output signal V of the storage device 83.
A subtraction device serves as a second arithmetic device that performs subtraction (ΔVd=Vd−V) with d. Furthermore, 86 is a division device that divides the output signal ΔVd of the subtraction device 85 and the current signal id (ΔVd/jd), and 88 is the division device 8.
a subtraction device that performs subtraction (ΔVd/id-R8) between the output signal AVd/id of 6 and the output signal RB of the auxiliary circuit resistance value setter 87, which is set to a value corresponding to the total resistance value of the auxiliary circuit; On the road, the output is sent to a measuring device (not shown) as a value R^E.
I am trying to send it as .

Next, the operation of the ground fault detection device having such a configuration will be explained.

First, a normal case with no grounding fault will be described. now,
Assuming that the synchronous generator 1 is in operation, the field current winding 22 of the AC exciter 2 receives an exciting current i supplied from the power supply 23.
f, and its output is rectified by the rotary rectifier 3 from the armature winding 21 and supplied to the field winding 11. On the other hand, the primary winding 42 of the rotary transformer 4 is excited by the power supply voltage v of the variable power supply 41, and the output obtained from the secondary winding 43 is sent to the rectifier 5. has been added. In such a state, when the voltage v of the variable power supply 41 is increased, the ground fin pressure Vd of the rectifier 5 is also increased accordingly. However, at this time, almost no ground current id flows through the auxiliary circuit, so the detector 62 of the non-contact detection device 6 does not detect the current id, and its output signal id' is almost zero. This world power signal id' is applied to the signal conversion device 81 in the insulation resistance measuring device 8, together with the voltage signal v of the variable power supply 41 and the excitation current signal if. Each signal added here if, v,,id'
are corrected based on a certain positive value. That is,
The current signal ir is the output voltage Vf of the rotary rectifier 3, the voltage signal v is the ground voltage Vd of the rectifier 5, and the current signal id'
are respectively connected to the ground current id. Here, the current signal jd flowing through the auxiliary circuit is almost zero, and even if the voltage signal Vd increases, the increase remains very small due to leakage current. Therefore, the contact current surge point detector 82 does not detect the current surge,
Since the normally open contact 82a is not closed, the voltage signal Vd is not input to the storage device 83, and the stored value Vd is still zero. Further, the subtraction device 85 performs subtraction between the voltage signal Vd and the output signal Vd of the storage device 83.
As mentioned above, since Vd,=0, the output is Vd itself. Further, in the division device 86, the output signal ΔVd=Vd of the subtraction device 85 is divided by the current signal id, but since id=0 as described above, its output becomes infinite. The output of this dividing device 86 is converted to the setting value R of the auxiliary circuit resistance value setting device 87 in the next subtracting device 88.
Subtraction is performed with B, but since the output of the divider 86 is much larger, its output R^E is output as infinite. On the other hand, in the division device 84, division of the voltage signal Vf and the output signal V of the storage device 83 is performed.
Since d.=0, the output signal a' becomes zero. In this way, since the output R^E corresponding to the ground resistance value is infinitely large, it is determined that there is no ground fault. Next, we will discuss the case where a grounding fault occurs. Now, assuming that there is a ground fault at point A in FIG. 1, the field circuit and auxiliary circuit shown in FIG. 1 can be equivalently represented as shown in FIG. 3. That is, the DC voltage applied to the field winding 11 of the field power circuit can be considered to be the voltage obtained from the DC power supply Vf through the diode 33 inserted in series with it, and the output voltage of the auxiliary circuit is similarly It can be considered as equivalent to the voltage obtained from the DC power supply Vd through the diode 35 and resistor RB inserted in series with it. Note that the internal resistance of the power supply Vf is zero in the forward direction and infinitely large in the reverse direction. In addition, the field winding 11
The grounding fault point A is located a percent from the far side of the entire length of the field winding, and the grounding resistance at the fault point is R^8 ohm. First, the relationship between power supplies Vf and Vd and related equipment will be explained. That is, since Vf is a rectified output voltage of the AC exciter 2, it can be expressed as the following equation. Vf nikl・Vbait nikl・(k?・■・n)=K.
・(kJ・kr・lf・n)=K ear・lf.・---
[11 However, vex: AC exciter output voltage, ■: magnetic flux,
n: rotation speed, i? : Excitation current, k,, k◇, kr, KE
:constant.

On the other hand, since the voltage Vd of the auxiliary circuit is obtained by converting the output of the secondary winding 43 of the rotary transformer 4 into DC, it can be expressed as follows.

Vd=k2・v2=K.・(n2/n,)v, ……■
However, v, and v2: rotating transformer primary and secondary side voltages,
ri/n. : winding ratio, k2: constant.

As is clear from these {1', '2} expressions, Vr, V
It can be seen that d is approximately proportional to if and v, respectively.

Further, the potential Va at the failure point A is lower than the potential at the illustrated point B by Vf·(a/100). Therefore, the ground current id flowing through the auxiliary circuit is as follows. l
d=(Vd-Va)/(R80R^8)={Vd-Vf
．． (a/100)}/RB+R^8).・・・． ...'3
However, as can be seen from FIG. 3, when Vd<Va, the ground current id does not flow and is zero due to the diode 35.

Also, since the excitation voltage Vf is normally considered to be constant, the ground current id when changing the auxiliary circuit voltage Sd is
The result is as shown in FIG. In the figure, the auxiliary circuit voltage Vd at the moment when the ground current id starts flowing can be expressed as follows using the glue equation. That is, Vd=Vr・(a
/100)=Va=Vf・a'...[4'and V
In the range of d>Vf・(a/100), as the auxiliary circuit voltage Vd increases, the ground current id also increases proportionally,
The ratio of their respective increase rates ΔVd and Δid can be expressed as follows.

△Vd/△id=RB+R＾E......■In this way, the ground current id when changing the auxiliary circuit voltage Vd
Using the characteristics of
'=Vd/Vr. Furthermore, the resistance value of the grounding point can be determined as R^8=△Vd/△id-RB from the formula [5}.

These will be explained in detail. Now, when the synchronous generator 1 is in a synchronous operation state, if a grounding fault occurs in the Kaiji winding 11, the grounding current id, which previously did not flow into the auxiliary circuit, will
begins to flow at the point at which the failure occurs. Then, the ground current id flowing through the auxiliary circuit is detected by the non-contact detection device 6, and its output signal id' is the output signal v of the variable power supply 41.
, and the excitation current signal ir to the signal converter 81 in the insulation resistance measuring device 8. The signals id, v, , if applied here are corrected according to their positive values, that is, the signal id' is the ground current id, the signal v is the auxiliary circuit voltage Vd, and the signal if is the rotary rectifier 3. output voltage V
They are corrected and output respectively to f. Here, since the ground current id starts to flow as described above, the ground current surge detector 8
2 detects this and instantaneously closes its normally open contact 82a. As a result, the auxiliary circuit voltage Vd at that time is applied to the storage device 83 through the normally open contact 82a, and is thereafter stored as a constant value Vd. Furthermore, when the variable power supply voltage v, increases further, each signal if
, v, , id' are applied to the signal converter 81 in the same manner as described above, where they are each corrected and output. First, the output signal Vf of the rotary rectifier outputted from here is divided by the output signal Vd of the storage device 83 in the dividing device 84, and as a result, the value of a': Vd, /Vf is obtained. The value a' is output to a display device (not shown) and displayed.
Therefore, the position of the ground fault point A can be determined from this value a'. On the other hand, the auxiliary circuit voltage signal Vd sent out from the input signal converter 81 is applied to the subtraction device 85. The subtraction device 85 also has an output signal Vd from the storage device 83.
, is added, and subtraction is performed between these two signals Vd and Vd, resulting in ΔVd=Vd-Vd. An output signal with a value of is applied to a divider 86. Furthermore, the ground current signal id is applied to this divider 86, and division is performed between both signals ΔVd and id, and the result is output as the value ΔVd/id. Further, the output signal of the division device 86 is applied to a subtraction device 88, and subtraction is performed between it and the output signal RB of the auxiliary circuit resistance value determiner 87, and as a result, the output signal is changed to ΔV.
The value of d/id-RB=R^8 is sent to a measuring device (not shown), and the ground resistance value R^8 is measured. Therefore,
The grounding resistance at the grounding fault point A can be known from this value R, and the degree of the fault can be determined based on its magnitude. Note that the present invention is not limited to the embodiments described above.

In the above embodiment, the auxiliary circuit is connected to the positive side of the field circuit, but it can be implemented in the same way, for example, if the auxiliary circuit is connected to the negative side and the rectifier of the auxiliary circuit is connected in reverse sacrifice. It is something. In this way, the present invention rectifies the output of the AC exciter 2 to transform the field winding 1 into
In a rotating electric machine such as a brushless synchronous generator 1 which is supplied to the motor 1, a rotary displacement device 4 whose primary side is excited by a variable power source 41, and a rectifier device which converts the secondary side output of this rotary transformer 4 into direct current. 5, a non-contact detection device 6 comprising a rotor-side excitation coil 61, and a detector 62 that is electromagnetically coupled to the rotor-side excitation coil 61 and detects the current flowing through the coil, and the rectifier 5. an auxiliary circuit formed by grounding one DC-side terminal of the controller and connecting the other DC-side terminal to one end of the field winding 11 of the brushless rotating electrical machine via the rotor-side excitation coil 61; The primary side voltage signal v of the rotary transformer 4, the excitation current signal if of the AC exciter 2, and the output current signal id' of the detector 62 of the non-contact detection device 61 are inputted to the rotary transformer 4. Each of the above signals v,,lf,i when changing the primary side voltage of
The apparatus is equipped with an insulation resistance measuring device 8 which performs a predetermined calculation based on d' and measures the grounding failure location and grounding resistance of the field circuit.

Therefore, if a grounding failure occurs in the field circuit while the rotating electric machine is in operation, it can be detected, and the grounding point can be easily determined from the measurement of the grounding resistance. .

In particular, even if there is no abnormality in the ground resistance while the motor is stopped, it is very effective when rotating to reduce the ground resistance due to centrifugal force or the like. Additionally, ground failures can be monitored almost continuously during operation.
Serious accidents caused by grounding failures can be prevented. Moreover, the rotor side does not require a complicated structure and can have an extremely simple configuration, and the stator side can also be configured with a subtraction device, a division device, etc., making it possible to have a simple configuration. can. As explained above, according to the present invention, in a brushless rotating electric machine, it is possible to detect a grounding fault in the power supply circuit in a non-contact manner, and also measure the grounding resistance, so that it is possible to detect the presence or absence of a grounding fault and the grounding location. It is possible to provide a ground fault detection device for a brushless rotating electrical machine that can easily perform evaluation even in an operating state.

[Brief explanation of drawings]

FIG. 1 is a configuration diagram showing an embodiment of the ground fault detection device according to the present invention applied to a brushless synchronous generator, and FIG.
FIG. 3 is a block diagram showing an example of the structure of the insulation resistance measuring instrument in FIG. 1, FIG. 3 is a diagram showing an equivalent circuit of FIG. 1 in the case of a ground fault, and FIG. 4 is a diagram for explaining the operation. 1... Synchronous generator, 11, 12... Field winding, 2... AC exciter, 21... Armature winding, 23, 41... ...Power supply, 3...
Rotating rectifier, 4... Rotating transformer, 42, 43
...Primary and secondary windings, 5 ... Rectifier, 6 ... Non-contact detection device, 61 ... Rotor side excitation coil, 62 ... ...Detector, 7...Resistance, 8...Insulation resistance measuring device, 9...Display device, 81...Signal conversion device, 82...・・・
... Ground current rapid increase point detector, 82a... 82 normally open ground, 83... Storage device, 84, 86...
...Division device, 85, 88...Subtraction device,
87...Auxiliary circuit resistance value setter. Figure 1 Figure 2 Figure 3 Figure 4

Claims (1)

[Scope of Claims] 1. In a brushless rotating electrical machine that rectifies the output of an AC exciter and supplies it to a field winding, a rotating transformer whose primary side is excited by a variable power source, and a secondary side of this rotating transformer. a non-contact detection device comprising a rectifier that converts an output into direct current, a rotor-side excitation coil, and a detector that is electromagnetically coupled to the rotor-side excitation coil and detects the current flowing through the coil; an auxiliary circuit formed by grounding one DC side terminal of the rectifier and connecting the other DC side terminal to one end of the field winding of the brushless rotating electric machine via the rotor side excitation coil; Primary voltage signal v of transformer
_1, each of the signals v_1 when the primary side voltage of the rotary transformer is changed by inputting the excitation current signal i_f of the AC exciter and the output current signal i_d' of the detector of the non-contact detection device, respectively; , i_f, i_d', and performs a predetermined calculation based on the grounding fault location and grounding resistance of the field circuit. Device. 2 The insulation resistance measuring instrument detects each signal v_1, i_f and i
__d' is the auxiliary circuit voltage signal V_d and the field circuit voltage signal V
When the ground current signal i_d increases rapidly, a signal conversion device that converts the ground current signal i_d into the ground current signal i_d performs the calculation V_d_1/V_f between the auxiliary circuit voltage signal V_d_1 and the field voltage signal V_f at that time. A first arithmetic device that calculates a grounding fault location, an auxiliary circuit voltage signal V_d_1 at that point in time when the grounding current signal i_d suddenly increases, an auxiliary circuit voltage signal V_d at the current moment, and a grounding current i
and a second arithmetic unit that calculates the grounding resistance due to a grounding fault by performing the calculation (V_d-V_d_1)/i_d between the brushless rotation and the brushless rotation according to claim 1. Ground fault detection device for electrical equipment.