JPH04372559A - Fault detector for rotating rectifier of brushless generator - Google Patents

Abstract

PURPOSE:To supervise abnormality easily and at all times by obtaining a caluculated value of loaded excitation current corresponding to a load condition by a simulator circuit, and issuing an alarm when the difference from a real value is larger than a specified value. CONSTITUTION:A power detector 13 calculates effective power Px and reactive power Qx from current and voltage detected with a current transformer 11 and an instrument transformer 12, and puts its outputs into a simulator circuit 20. The first function generator 14 outputs a calculated value of no-load excitation current Ifo which corresponds to the voltage and puts it into the simulation circuit 20. As the simulator circuit 20 simulates the output limit characteristic of an AC generator 2, it outputs a calculated value of loaded excitation current Ifx corresponding to the load condition of the AC generator 2 at that time, by inputting various kinds of data. And it becomes possible to judge whether or not the elements of rotating rectifiers 6 are abnormal by judging whether or not the detected value of the real excitation current IF of the AC generator 2 is equal to the calculated value of the loaded excitation current Ifx.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for detecting a failure in a rotary rectifier, which is a major component of a brushless generator.

0002

2. Description of the Related Art FIG. 6 is a block diagram schematically showing the structure of a brushless generator. In Fig. 6, the alternator consists of a fixed armature 2A and a rotating magnetic pole 2F, and by passing an alternator excitation current IF through the rotating magnetic pole 2F, three-phase AC power is supplied from the armature 2A. Output. The AC exciter for supplying this AC generator excitation current IF consists of a rotating armature 3A and a fixed magnetic pole 3F. 3A outputs three-phase AC power. Therefore, the rotating magnetic pole 2F of the AC generator and the rotating armature 3A of the AC exciter are connected by a common rotating shaft 5, and this rotating shaft 5
is driven by prime mover 4. At this time, a rotating rectifier 6 is fixed to the rotating shaft 5, and the alternating current power output by the rotating armature 3A of the AC exciter is converted into direct current power by the rotating rectifier 6, and the alternating current power is sent to the rotating magnetic pole 2F of the alternator. If the excitation current IF is applied, the rotating rectifier 6 rotates together with the rotating magnetic pole 2F and the rotating armature 3A, so this alternator does not require a slip ring or brushes, and becomes a so-called brushless generator.

Brushless generators are widely used because they do not have parts that wear out, such as brushes, and can eliminate the need for maintenance and inspection of slip rings and the like. Incidentally, conventionally, a fuse has been inserted to protect the rotary rectifier 6, but since this fuse rotates together with the rotary rectifier 6, there is a risk of damage due to centrifugal force, resulting in a structural weakness. On the other hand, with the improvement of applied technology, the risk of damage to the rotary rectifier 6 has decreased, so the protective fuse is often omitted these days.

0004

[Problem to be solved by the invention] In recent brushless generators in which a protective fuse is not inserted in the rotary rectifier 6,
The alternator excitation current IF increases when a rectifier short-circuit occurs, but conventionally, the alternator excitation current when the alternator outputs the rated voltage with no load, and the rated voltage at full load Since only two points of the alternator excitation current were monitored when the alternator was in the state where it was outputting, when the alternator was operating in other conditions, even if a fault such as a short circuit in the rectifying element occurred, this could be detected. There was a problem that made it impossible to do so.

[0005] Therefore, an object of the present invention is to constantly calculate the alternator excitation current corresponding to the operating condition, no matter what load condition the brushless generator is operating under, and to combine this calculated value with the alternator excitation current. If a difference of more than a predetermined value occurs between the current detection value and the current detection value, it is determined that the rotary rectifier is malfunctioning and an alarm is issued.

[0006]

[Means for Solving the Problems] In order to achieve the above object, the rotating rectifier failure detection device of the present invention is provided with rotating magnetic poles of an alternator in which the stator is an armature and the rotor is a magnetic pole, and the stator is a magnetic pole. The rotor is connected to a rotating armature of an AC exciter whose armature is connected by a common rotating shaft, and the AC power output from the rotating armature of this AC exciter is rectified by a rotating rectifying means attached to the rotating shaft. , a brushless generator configured to apply exciting current to rotating magnetic poles of the alternator, power detection means for detecting active power and reactive power output by the alternator; voltage detection for detecting alternator terminal voltage; means, alternator excitation current detection means for detecting an excitation current of the alternator, first function generation means for simulating no-load saturation characteristics of the alternator, and a simulating circuit for simulating output limit characteristics of the alternator. When the alternator is not loaded, a calculated value of the no-load excitation current of the alternator is calculated using the detected alternator terminal voltage value and the first function generating means, and when the alternator is loaded, is the detected active power value of this alternator,
The AC generator is generated from the simulated circuit using the detected reactive power value, the calculated no-load excitation current value of the AC generator by the first function generating means, and the direct axis synchronous reactance and horizontal axis synchronous reactance of the former AC generator. Find the calculated value of the excitation current of the machine, compare these calculated values of the excitation current when the alternator is not loaded or when the alternator is loaded, and the detected value of the excitation current of the alternator,
When the difference between the two is greater than or equal to a predetermined value, it is determined that the rotary rectifying means is malfunctioning.

[0007]

[Operation] This invention calculates the calculated no-load excitation current corresponding to the output voltage of the alternator, detects the active power PX and reactive power QX output by the alternator, and combines these with the output voltage of the alternator. The generator direct axis synchronous reactance and the generator horizontal axis synchronous reactance, which are constants, are given to a simulated circuit, and from this simulated circuit, the calculated value of the excitation current during load of the alternator corresponding to the load condition at that time IfX is obtained. If the difference between the load excitation current calculation value IfX and the alternator excitation current detection value IF exceeds a predetermined value, it is determined that the rotary rectifier has failed and an alarm is issued. Note that the above-mentioned simulation circuit has a circuit configuration that simulates the output limit characteristics of an alternator.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a circuit diagram showing a first embodiment of the present invention. In FIG. 1, an AC generator 2 includes an armature 2A and a rotating magnetic pole 2F, an AC exciter 3 includes a rotating armature 3A and a fixed magnetic pole 3F, and a rotating rectifier 6. The brushless generator described above is configured in FIG. 6, and the fixed magnetic pole 3F of the AC exciter 3 is connected from the excitation power source 3S
By supplying the AC exciter excitation current IFE to the rotating magnetic pole 2F of the alternator 2, the alternator excitation current IF flows from the armature 2A of the alternator 2 to the bus bar 8 via the circuit breaker 7. AC power is output to.

A current transformer 11 and an instrument transformer 12 are provided on the output side of the alternator 2 to detect the output current and output voltage of the alternator. The power detector 13 determines the active power P output by the AC generator 2 from this current and voltage.
X and reactive power QX are calculated and output to the simulation circuit 20. Also, since the first function generator 14 generates a function that simulates the no-load saturation characteristic of the alternator, the voltage transformer 12
By inputting the detected voltage, the no-load excitation current calculation value If0 corresponding to the voltage is output to the simulation circuit 20. Further, the first constant setter 15 sets a value A, which is the reciprocal of the generator direct axis synchronous reactance Xd, and the second constant setter 16 sets a value B, which is the reciprocal of the generator horizontal axis synchronous reactance Xq. Then, these setting values are applied to simulation circuit 2.
It is inputting to 0.

Since the simulation circuit 20 simulates the output limit characteristics of the alternator 2, by inputting the above-mentioned various data to this simulation circuit 20, the load state of the alternator 2 at that point in time can be determined. Corresponding load-on excitation current calculation value If
This simulation circuit 20 outputs X. Therefore, by detecting whether or not the AC generator excitation current detection value IF matches the load excitation current calculation value IfX calculated in this way, it is possible to determine whether an abnormality has occurred in the elements of the rotary rectifier 6. It is possible to judge whether

FIG. 2 is a graph showing the output limit characteristics of an alternator, in which the vertical axis represents active power in units, and the horizontal axis represents reactive power in units. The right direction represents leading reactive power with negative polarity, and the left direction of the horizontal axis represents lagging reactive power with positive polarity. In the graph shown in FIG. 2, A=1/Xd (where Xd is the generator direct axis synchronous reactance) and B=1/Xq (however, Xq
is the generator horizontal axis synchronous reactance), so the arc A
B is a part of a circle whose radius is (B-A)/2 and centered at point C. However, the coordinates of point C are [A+(B-A)/2,
0]. In this way, the line segment OA (O is the origin of this graph) will have a size corresponding to the no-load excitation current If0, and the size obtained by subtracting the radius of the circle mentioned above from the line segment CD will be the load excitation current. It is compatible with IfX.

Therefore, the exciting current I during load shown in FIG.
fX (that is, the length obtained by subtracting the radius of the circle from the line segment CD) is as shown in Equation 1 below.

[0013]

[Math 1]

FIG. 3 is a block circuit diagram showing a second embodiment of the present invention, which is a circuit for calculating the above-mentioned equation 1. In other words, A is the reciprocal of the generator direct axis synchronous reactance Xd
and B, which is the reciprocal of the generator horizontal axis synchronous reactance Xq
(first subtractor 21), and the result of the calculation is calculated as 2.
By dividing by (first divider 22), the radius of the circle already described in FIG. 2 is calculated. The first adder 23 is the first divider 2
2, the above-mentioned value A, and the reactive power detection value QX
The first multiplier 24 then calculates the square of this value. On the other hand, since the second multiplier 25 calculates the square of the active power detection value PX, the calculation result of the second multiplier 25 and the calculation result of the first multiplier 24 are added (second adder 26).
Then, the square root of this is determined by a square root calculator 27. The second subtracter 28 calculates the difference between the calculation result of the square root calculator 27 and the calculation result of the first divider 22 described above, and divides the calculation result by the value A (second divider 29). This division result is multiplied by the no-load excitation current calculation value If0 as the third
By performing this in the multiplier 30, it is possible to obtain the load excitation current calculation value IfX.

FIG. 4 is a circuit diagram showing a circuit for obtaining an alarm output by comparing the load excitation current calculated value obtained by the second embodiment circuit shown in FIG. 3 with the AC generator excitation current detection value. It is composed of a third divider 41, a comparator 42, and an alarm setting device 43. That is, the calculated value of excitation current under load If
The third divider 41 calculates the ratio between X and the alternator excitation current detection value IF, and when the calculation result reaches the value set by the alarm setting device 43, the comparator 42 outputs an alarm signal. . However, in the case of a brushless generator, it is difficult to detect the alternator excitation current IF. Therefore, instead of detecting this alternating current generator excitation current IF, an alternating current exciter excitation current detection value IFE, which has a substantially linear relationship with this, is used.

FIG. 5 is a circuit diagram showing a third embodiment of the present invention. As already described in FIG. 4, when outputting the alarm signal, if the AC exciter excitation current detection value IFE is used instead of the AC generator excitation current IF which is difficult to detect,
Even if the relationship between the two is approximately linear, errors occur. Therefore, the AC exciter excitation current detection value IFE is converted to the second function generator 50.
By inputting to I can do it.

[0017]

[Effect of the invention] Conventionally, in brushless generators, only the excitation current when the alternator was in the no-load rated voltage state and the excitation current when the alternator was in the full-load rated voltage state were monitored, so the rectification of the rotating rectifier Even if an abnormality such as a short circuit occurred in the element, this abnormality could not be detected. In the present invention, the no-load excitation current of an alternator and the active power and reactive power output by the alternator are detected, and these detected values and constants of the alternator are provided to a simulation circuit. Since this simulation circuit simulates the output limit characteristics of an alternator, this simulation circuit inputs the above-mentioned values, calculates the load excitation current, and outputs it. Therefore, no matter what operating state the brushless generator is in, the excitation current of the alternator in that operating state is accurately calculated. (substituted by machine excitation current), it is possible to constantly and easily monitor whether or not an abnormality has occurred in the rotary rectifier.

[Brief explanation of drawings]

[Fig. 1] A circuit diagram showing a first embodiment of the present invention.

[Figure 2] Graph showing the output limit characteristics of an alternator

FIG. 3 is a block circuit diagram showing a second embodiment of the present invention.

[Fig. 4] A circuit diagram showing a circuit for obtaining an alarm output by comparing the load excitation current calculated value obtained by the second embodiment circuit shown in Fig. 3 and the AC generator excitation current detection value.

[Fig. 5] Circuit diagram showing a third embodiment of the present invention

[Figure 6] Configuration diagram showing the outline of the configuration of a brushless generator

[Explanation of symbols]

2　　　AC generator 2F　AC generator rotating magnetic pole 3 AC exciter 3A AC exciter rotating armature 4. Prime mover 5 Rotation axis 6 Rotating rectifier 13 Power detector 14 First function generator 20 Simulated circuit 21 First subtractor 22 First divider 23 First adder 24 First multiplier 25 Second multiplier 26 Second adder 27 Square root calculator 28 Second subtractor 29 Second divider 30 Third multiplier 41 3rd divider 42 Comparator 50 Second function generator

Claims (3)

[Claims] Claim 1: A rotating magnetic pole of an alternating current generator in which the stator is an armature and a rotor is a magnetic pole, and a rotating armature of an AC exciter in which the stator is a magnetic pole and the rotor is an armature are coupled together by a common rotating shaft. In this brushless generator, the AC power output from the rotating armature of the AC exciter is rectified by a rotary rectifying means attached to the rotating shaft, and the AC power is applied as excitation current to the rotating magnetic poles of the AC generator. Power detection means for detecting active power and reactive power output by a generator, voltage detection means for detecting alternator terminal voltage, alternator excitation current detection means for detecting excitation current of the alternator, alternator a first function generating means for simulating the no-load saturation characteristic of the alternator, and a simulating circuit for simulating the output limit characteristic of the alternator. A first function generation means calculates a no-load excitation current calculation value of this alternator, and when the alternator is loaded, the active power detection value, reactive power detection value of this alternator, and the first function generation means The excitation current calculation value of this alternator is obtained from the above simulation circuit using the no-load excitation current calculation value of this alternator, and the direct axis synchronous reactance and horizontal axis synchronous reactance of the previous alternator, and these AC The calculated excitation current value when the generator is unloaded or when the generator is loaded is compared with the detected value of the alternator excitation current, and when the difference between the two is greater than or equal to a predetermined value, it is determined that the rotary rectifying means has failed. Rotating rectifier failure detection device for brushless generators. 2. The brushless generator rotary rectifier failure detection device according to claim 1, wherein the simulating circuit has a reciprocal A of a generator direct axis synchronous reactance, which is an alternating current generator constant;
A first subtracter that calculates the difference between B, which is the reciprocal of the generator horizontal axis synchronous reactance, which is also an AC generator constant, and a first divider that divides the calculation result of this first subtracter by 2.
a first adder that adds the calculation result of the first divider, the value A, and the reactive power detection value; a first multiplier that squares the calculation result of the first adder; and a first multiplier that squares the calculation result of the first adder; A second multiplier that squares the detected value, a second adder that adds the calculation results of the first multiplier and the second multiplier, and calculates the square root of the calculation result of the second adder. a second subtractor that calculates the difference between the calculation result of the square root calculation unit and the calculation result of the first divider; and a second subtractor that calculates the difference between the calculation result of the square root calculation unit and the calculation result of the first divider, and divides the calculation result of the second subtractor by the value A. It is composed of a second divider and a third multiplier that multiplies the calculation result of the second divider by the no-load excitation current calculation value outputted by the first function generating means, and the calculation result of the third multiplier is A rotary rectifier failure detection device for a brushless generator, characterized in that the result is compared with the detected value of the alternating current generator excitation current, and when the difference between the two is greater than a predetermined value, it is determined that the rotary rectifier has failed. 3. The rotary rectifier failure detection device for a brushless generator according to claim 1 or 2, wherein a second function is generated for converting the AC generator excitation current detection value into the AC exciter excitation current detection value. A rotary rectifier failure detection device for a brushless generator, comprising: means.