JPS63302327A - Method and apparatus for monitoring shaft torsional vibration of rotary electric machine - Google Patents

Abstract

PURPOSE:To achieve a higher accuracy of monitoring vibration, by using an electromagnetic torque value determined from current flowing through an armature of a rotary electric machine as electromagnetic torque value to compute a shaft torsional vibration of a rotating shaft. CONSTITUTION:For example, a generator 1 connected to a turbine 2 is equipped with the titled apparatus comprising a torque detector 4 and a shaft torsional vibration evaluator 5. Then, a terminal voltage (e), a current (i) and a rotary angular velocity (omega) of a generator 1 are measured, an angle gamma for a specified phase of a winding is detected with a detector 6 and the voltage (e) and the current (i) undergoes a dq conversion with a dq converter 7, namely, being converted into a direct axis component and quadrature axis component from the angle gamma to determine voltage and current values in the respective axes. Then, a magnetic flux computing unit 8 calculates magnetic fluxes phid and phiq of a winding of an armature to determine an electromagnetic torque T with a torque computing device 9. Then, the torque T is stored temporarily in a storage device 10 and the evaluation and monitoring of life by a shaft torsional vibration are performed with a shaft torsional vibration computing device 11 and a shaft torsional fatigue computing device 12.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a method and apparatus for monitoring shaft torsional vibration of a rotating electric machine, and particularly to a shaft torsional vibration monitoring method suitable for monitoring shaft torsional vibration of a turbine generator. The present invention relates to a method and an apparatus thereof.

[Conventional technology]

In the case of a rotating electric machine, it is rare that the rotating electric machine is operated alone; for example, in a turbine generator, a turbine and a generator are often combined and operated under the shaft system.

In rotating electric machines with long bearings, the status of each shaft part during operation is important from a reliability perspective.

For example, it is necessary to sufficiently monitor the temperature and vibration of each part, as well as the supply status of lubricating oil to the bearings.

One of the important monitoring elements is monitoring of shaft torsional vibration.

Many methods and devices for monitoring shaft torsional vibration have been devised and some have been put into practice. The following are well known as representative examples. That is, as described in Japanese Patent Application Laid-Open No. 58-22923, shaft torsion detectors are provided at certain intervals in the axial direction to detect the torsion of the shaft and to detect the external force acting on the shaft system for one rotation. is measured, and the torsional vibration at any point in the rotating shaft system is estimated from these values.

Although it is possible to sufficiently measure and monitor shaft torsional vibration with this type of shaft system, as mentioned above, when this type of shaft system is long, it is necessary to measure many points, and the number of detectors increases. In addition, the mounting position of the detector is limited to a specific part, and especially when installing it on an existing rotating electric machine, parts and equipment for measurement are also installed on the rotating body side. Furthermore, many problems remain, such as the fact that the mounting position is limited and installation may be extremely difficult.

Recently, the following methods have been devised to solve this problem and are being put into practical use. In other words, find the electric torque and mechanical torque of the rotating electric machine, and then solve the equation of motion of the rotating shaft system sequentially based on these values.

It calculates shaft torsional vibration. In other words, this is the second
To explain in more detail using a figure, this figure shows a spring mass model in the case of a turbine generator, where / indicates the generator and 2 indicates the turbine. This generator and turbine are connected via a shaft, and this shaft system has a torsional spring constant K for equal savings.
(K.

, +1) and the torsional damping constant D (D,, yo+1).

Therefore, in general, shaft torsional vibration in a rotating shaft system is expressed by the equation of motion of the following equation, so these equations include -KILL, l+2(δ1+1-61+2)+DI,
t"t (δ, -51+1)t 10Ts...(1) where, δi: Change in rotational axis torsion angle [radlKI torsional spring constant igD+52 damping constant Mk: inertia constant i=1 ~m −1 j = 2 ~ m K = 1 ~ m In the constant, D and electric torque fluctuation numerator l (there is)
is the variation in mechanical torque) to find the axial torsional vibration.

In this way, the electric torque fluctuations (or mechanical torque fluctuations, or both) are used to calculate this equation of motion using numerical analysis methods such as the Runge-Futter-Gill method or the trapezoidal method. In the case of Figure 2, there are five mass points M1 to M5 in the rotating shaft system of the generator/turbine, so the second-order differential equation in Figure 5 must be solved, but in this case, the following You will be solving a system of 10 first-order differential equations one after another.

M IS M 5 By capturing the electric torque fluctuations and mechanical torque fluctuations as described above, it is possible to calculate and monitor the shaft torsional vibration of the rotating shaft system. Unlike those using torsion detectors, there is no need to provide any special parts or equipment to the rotating shaft system, and there is no need to worry about where to mount the detector, making it very effective in practice.

[Problem that the invention seeks to solve]

However, as a result of careful experiments, it has become clear that this method also has some drawbacks.

In other words, during normal operation, even if there are fluctuations in electric torque due to disturbances in the power transmission system, or fluctuations in mechanical torque due to turbine drive steam or gas, these values are small, so the rotating shaft system The torsional vibration that acts on the power transmission system is small and does not pose a particular problem, but on the other hand, in the case of a ground fault that occurs in the power transmission system or a system disturbance due to the grid being restarted, etc., the electric torque of the generator will fluctuate. Excites large torsional vibrations in the rotating shaft system of the turbine generator.

However, in those that use electric torque, the detection accuracy of monitoring temporarily decreases when the most severe torsional vibration occurs.

In other words, the electric torque Te can be detected by detecting the terminal voltage and current of the generator using PT-CT, finding the generator output, and dividing this generator output P by the rated rotational angular speed ω0. being done. That is, Te=P/ω0 = (eaia+ebib+ecic)/(110
− It can be determined by (3). Therefore, for example, if a short-circuit accident occurs, the terminal voltage of the generator will instantly change and drop significantly, so the calculated detected torque Te will also be a small value, and it will be The detection accuracy of the shaft torsional vibration becomes extremely poor, and the monitoring becomes meaningless.

The present invention was designed with this in mind, and it is possible to use the
It is an object of the present invention to provide a shaft torsional vibration monitoring device for a rotary electric machine of this type that can sufficiently monitor shaft torsional vibration with high precision.

[Means for solving problems]

That is, when detecting torque, the present invention calculates the armature magnetic flux by taking in the armature current unrelated to transient fluctuations in voltage, and calculates the torque equation 1 based on this value. ．． '、：＞
,,j% Magnetic torque is determined, and the shaft torsional vibration is calculated from this electromagnetic torque value to monitor the shaft torsional vibration.

[Effect]

In this way, the torque value required to calculate the shaft torsional vibration is calculated from the armature magnetic flux, so even if there is a transient change in the terminal voltage of the rotating electrical machine, the electromagnetic torque will be calculated sufficiently, and any This makes it possible to monitor shaft torsional vibration with high accuracy even under various conditions.

〔Example〕

The present invention will be described in detail below based on the illustrated embodiments. FIG. 1 shows a block diagram of a shaft torsional vibration monitoring device when applied to a turbine generator.

The generator 1 is coupled to a turbine 2 which is a prime mover, and its electrical output is connected to the grid via an output line 3.

The shaft torsional vibration monitoring device includes a torque detection device 4 and a shaft torsional vibration evaluation device 5.

The torque detection device 4 includes a detector 6 that receives the terminal voltage e, lightning current and rotational angular velocity ω of the generator to detect the rotation angle γ for a predetermined phase of the winding, and detects the voltage and current from the relationship between the rotation angle γ. A dq converter 7 that converts the magnetic flux into a direct axis component and a horizontal axis component, that is, a d-axis and a q-axis, a magnetic flux calculator 8 that calculates the magnetic flux generated by the armature winding, and a torque The shaft torsional vibration evaluation device 5 also includes a torque storage device 1° that stores the torque value calculated by the torque calculator 9, and a shaft torsional vibration evaluation device 5 that calculates the shaft torsional vibration based on this torque value. The shaft torsional vibration calculation device 11 calculates the fatigue life due to the shaft torsional vibration, and the shaft torsional fatigue life calculation device 12 calculates the fatigue life due to the shaft torsional vibration.

The operation of the shaft torsional vibration monitoring device formed in this way is as follows:
First, the terminal voltage e, current i, and rotational angular velocity ω of the generator 1 are measured and taken into the first rotor position detector 11. Here, the angle γ from the predetermined phase of the armature winding of the d-axis of the rotor is detected from the voltage waveform, and then the angle γ is used in the dq converter 7.

The voltage e and lightning current are subjected to dq transformation, that is, converted into a direct axis component and a horizontal axis component. In other words, the voltage and current values e on each axis
d, eq, id, and iq are found.

In this case, this ciq conversion is performed using the following generally known formula.

...(4) ...(4) Next, using the voltage and current values on each axis, the magnetic flux calculator 8
The magnetic flux of the armature winding is φ6. φg is calculated. This calculation is performed as follows. In other words, ra: Armature resistance Among the above, armature resistance ra, voltage and current value e on each axis
Since d, eq, id, iq, and rotational angular velocity ω are all known values, the armature winding magnetic flux φd is obtained by sequentially numerically calculating the above equation using the Runge-Futter method, for example, using the predetermined magnetic flux as an initial value.

φq can be found.

When the armature winding magnetic fluxes φd and φq are determined, the electromagnetic torque T is determined by the torque calculator 9.

In other words, according to the two-reaction theory of a synchronous machine, the electric machine winding magnetic flux is the direct magnetic flux φd, the horizontal axis magnetic flux φq, and the armature current is the direct axis component i.
d, and the horizontal axis component iq, the electromagnetic torque T can be obtained as T=iq・φd−id・φq (6).

In other words, armature current and electric machine pre-winding 4! The torque value is determined from the relationship between the internal induced voltage and the magnetic flux.

Next, this electromagnetic torque T is temporarily stored in the torque storage device 10, and as in the conventional case, the shaft torsional vibration calculation device 11. A shaft torsional fatigue life calculation 12 performs life evaluation based on shaft torsional vibration.

Note that the reason why the electromagnetic torque is temporarily stored in the torque storage device 10 is because of the calculation speed. Therefore, instead of storing this electromagnetic torque, other elements may be stored.

That is, FIG. 4 shows another embodiment related to the storage device. In this figure, the storage device 13 is provided in the torque detection device, and the voltage/current x d+ iqt in each axis is
The converted value of edt e q is stored, and even this method will have exactly the same effect as the above-mentioned one. Furthermore, it goes without saying that the detected voltage e and current i may be stored. Furthermore, if the speed of the arithmetic unit becomes faster, it may be possible to omit the storage device.

Further, in the above description, a case has been described in which two arithmetic units are provided for each element's arithmetic operation, but it would also be possible to use a dual arithmetic unit. Fifth
The figure shows one example, in which the magnetic flux calculator is also used as the shaft torsional vibration calculator. That is, the aforementioned magnetic flux calculation and shaft torsional vibration calculation are first-order differential equations of the same form, and it may be possible to use the calculation unit for both.

In the above explanation, the calculation of shaft torsional vibration from electromagnetic torque has been explained, but mechanical torque may also be calculated at the same time, and in this case, of course, this calculation unit may also be used. It would be nice.

Next, referring to FIG. 3, a comparison will be made between the conventional shaft torsional vibration monitoring device and the shaft torsional vibration monitoring device of the present invention in terms of their effects.

This figure shows the electrical torque in relation to time from normal load operation to ground fault.

The test rotating electrical machine was a simulated rotating electrical machine with a capacity equivalent to 30,000 KVA, a shaft system total length of 10 m, and a rotation speed of 360 rpm.

In the solid line curve in the figure,
The period up to o is the state of normal load operation. Naturally, the electric torque during this normal load operation is a constant value, but it can be seen that the electric torque is oscillating due to the ground fault accident at the time of to. The recent trend is to detect and monitor this shaft torsional vibration using electric torque or mechanical torque, and the curve Y formed by the dotted line in the figure is an attempt to detect and monitor shaft torsional vibration using the conventional electric torque mentioned above. As is clear from this curve, during normal load operation, shaft torsional vibration is detected with high accuracy without any particular problem.
From the time of the ground fault accident, as mentioned above, the terminal voltage of the rotating electrical machine becomes zero, so the detected value also becomes zero, indicating that no detection or monitoring is performed even though the electric torque is in fact in an oscillating state.

In contrast, the shaft torsional vibration monitoring device of the present invention has
As shown by curve Z, vibration conditions almost equal to the vibrations of electric torque are detected not only under normal load conditions but also during ground faults.

We can see how superior the monitoring device of the present invention is.

〔Effect of the invention〕

As described above, according to the shaft torsional vibration monitoring device of the present invention, the armature current value and the armature winding magnetic flux value are incorporated into torque detection, and the magnetic torque is calculated from both. However, since the shaft torsional vibration is calculated using this electromagnetic torque, it can be used not only during normal load operation, but also during normal load operation.
Even if a short-circuit accident occurs in the electrical system, the
It is possible to obtain a shaft torsional vibration monitoring device for this type of rotating electrical machine that is capable of monitoring shaft torsional vibration.

[Brief explanation of drawings]

Fig. 1 is a block diagram showing an embodiment of the shaft torsional vibration monitoring device of the present invention, Fig. 2 is a diagram showing a spring mass model in a turbine generator, and Figs. 3 and 4 are diagrams showing an embodiment of the shaft torsional vibration monitoring device of the present invention. FIG. 5 is a block diagram showing another embodiment of the shaft torsional vibration vjJ monitoring device of FIG. 1... Generator (rotating electric machine), 2... Turbine, 4...
...Torque detection device, 5...Shaft torsional vibration evaluation device,
8... Magnetic flux calculator, 9... Torque calculator, 11...
- Shaft torsional vibration calculation device, 12...shaft torsion fatigue life calculation device.

Claims (1)

[Claims] 1. Detecting the torque acting on the rotating shaft of a rotating electric machine, calculating the shaft torsional vibration of the rotating shaft based on the detected torque value, and monitoring the shaft torsional vibration of the rotating shaft. In the method for monitoring shaft torsional vibration of a rotating electrical machine, the shaft torsional vibration of the rotating shaft is calculated using an electromagnetic torque value obtained from a current flowing through an armature of the rotating electrical machine as the torque value. A method for monitoring shaft torsional vibration of rotating electric machines. 2. A rotating system that monitors the torsional vibration of the rotating shaft by detecting the torque acting on the rotating shaft of the rotating electric machine and calculating the torsional vibration of the rotating shaft based on the detected torque value. In the shaft torsional vibration monitoring method of an electric machine, when detecting torque with the torque detection device, the terminal voltage, current, and rotational angular velocity value of the rotor of the rotating electric machine are taken in, the internal induced voltage of the rotating electric machine is determined from these three, and the internal induced voltage of the rotating electric machine is determined from these three factors. A method for monitoring shaft torsional vibration of a rotating electric machine, characterized in that a torque value is determined from an induced voltage. 3. A rotating device that monitors the torsional vibration of the rotating shaft by detecting the torque acting on the rotating shaft of the rotating electric machine and calculating the torsional vibration of the rotating shaft based on the detected torque value. A method for monitoring shaft torsional vibration of an electric machine, characterized in that when detecting a torque value acting on the rotating shaft, an electromagnetic torque determined from the armature winding magnetic flux of the rotating electric machine is applied to this torque value. A method for monitoring shaft torsional vibration of rotating electric machines. 4. A torque detection device that detects the torque acting on the rotating shaft of a rotating electric machine, a shaft torsional vibration calculation device that calculates the shaft torsional vibration of the rotating shaft based on the torque value detected by the torque detection device, and the shaft torsion This rotating machine is equipped with a shaft torsional vibration fatigue life calculation device that evaluates the torsional fatigue of the rotating shaft based on the shaft torsional vibration calculation results of the vibration calculation device, and is designed to monitor the shaft torsional vibration of the rotating shaft system of a rotating electric machine. Shaft torsion vibration monitoring device for an electric machine, characterized in that the torque detection device is provided with a torque calculator that takes in a value of an armature winding result and calculates an electromagnetic torque from this value. Vibration monitoring equipment. 5. A torque detection device that detects the torque acting on the rotating shaft of a rotating electric machine, a shaft torsional vibration calculation device that calculates the shaft torsional vibration of the rotating shaft based on the torque value detected by the torque detection device, and the shaft torsion This rotating machine is equipped with a shaft torsional vibration fatigue life calculation device that evaluates the torsional fatigue of the rotating shaft based on the shaft torsional vibration calculation results of the vibration calculation device, and is designed to monitor the shaft torsional vibration of the rotating shaft system of a rotating electric machine. In the shaft torsional vibration monitoring device for an electric machine, the torque detection device includes a voltage detection means for detecting a terminal voltage of the rotating electric machine, a current detection means for detecting a current flowing through an armature of the rotating electric machine, and a rotational angular velocity of the rotor. A rotation angular velocity detection device for detecting rotational angular velocity, and a torque calculator for computing electromagnetic torque from the detection value of the rotation angular velocity detection device, the voltage value of the voltage detection means, and the detection value of the current detection means. Electrical machinery shaft torsional vibration monitoring device.