JPH026296B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a generator bearing monitoring and protection device that monitors the condition of a bearing metal of a generator and starts a protective operation when an abnormality is detected.

Conventionally, there has been a device of this type as shown in FIG. In the figure, 1 is the generator, 2 is the rotating shaft of the generator, 3 is the bearing of the rotating shaft, 4 is the bearing metal of the bearing, 5 is the cooling water pipe for cooling the bearing 3, and 6 is the bearing metal 4. a detector for detecting temperature; 7 a converter for converting the output of the thermometer into an electrical signal; 8 a comparator; 9 a reference voltage source for the comparator 8;
0 is a protection circuit, 7a is the output of converter 7, 9
a is the reference voltage value, 8a is the output of comparator 8, and 7a
When <9a, 8 becomes logic "0", and when 7a9a, 8a becomes logic "1", and 8a becomes logic "1".
In this case, the protection circuit 10 operates.

Since the conventional device is configured as described above, the reference voltage value 9a is fixedly determined, and therefore the maximum allowable temperature of the bearing is fixedly determined, and other conditions related to the bearing are Therefore, if the maximum allowable temperature of the bearing cannot be set to the most appropriate value, and the reference voltage value 9a is set to a high value,
There is a drawback that detection of abnormality in the bearing is delayed, and on the other hand, if the reference voltage value 9a is set to a low value, the protection circuit 10 may malfunction even though there is no abnormality in the bearing.

This invention was made in order to eliminate the drawbacks of the conventional ones as described above, and it detects various physical quantities that affect the temperature of the bearing, such as the temperature and flow rate of the bearing cooling water and the rotation speed of the shaft. , calculate the primary and secondary end values of these physical quantities and bearing temperature over time, determine the maximum permissible bearing temperature from these first derivatives, and determine the bearing temperature from these second derivatives. To provide a highly reliable monitoring protection device by determining the maximum permissible value of the temperature rise rate and activating the protection circuit when both the bearing temperature and the temperature rise rate exceed the respective maximum permissible values. The purpose is

Embodiments of the present invention will be described below with reference to the drawings. FIG. 2 is a block diagram showing an embodiment of the present invention, in which the same reference numerals as in FIG. flow rate detector, 14, 15,
16 and 17 are detectors 11, 6, 12, and 1, respectively.
In this specification, the combination of the detector 6 and the converter 15 is temporarily referred to as a bearing temperature converter, and each of the outputs of 11 and 14, 12 and 16, and 13 and 17 is The combination will be temporarily referred to as each converter. 18, 19, 20, 21, 2
2, 23, 24, 25 are differentiating circuits, 26
is the first arithmetic circuit, 27 is the second arithmetic circuit, 28
is a first comparator, 29 is a second comparator, and 30 is an AND gate.

If the outputs of converters 14, 15, 16, and ₁₇ are respectively X ₁ , X ₂ , X ₃ , and
The outputs of 19, 20, 21, 22, 23, 24, and 25 are X ₁ , X ₂ , X ₃ , X ₄ , X ₁ , X ₂ , X
_¨3 ,
Let _X¨4 . However, X _i (i=1, 2, 3, 4) is the first derivative of variable X with respect to time, and X _i (i=1, 2,
3, 4) represent the second-order differential with respect to time of the variable X _i (i=1, 2, 3, 4).

The first arithmetic circuit 26 performs the calculation Y= _4〓 ⁱ⁼¹ C _li X〓 _i +C ₁₀ (1) and outputs the calculation result Y as the first reference value. However, if Y exceeds X _2nax , X _2nax
is output as the value of Y. Here, X _2nax is a value predetermined as the maximum allowable value of X ₂ ,
C _1i is a coefficient determined in advance depending on the degree to which X〓 _i influences changes in bearing temperature, and C ₁₀ is a numerical value determined in advance as a margin value for the current value of bearing temperature.

The second circuit 27 performs the calculation Z= ₄ 〓 ⁱ⁼¹ C _2i X ¨ _i +C ₂₀ (2) and outputs the calculation result Z as the second reference value. However, if Z exceeds X〓 _2nax, then X〓 _2nax
is output as the Z value. Here, X〓 _2nax is a value predetermined as the maximum allowable value of X〓 ₂ ,
C _2i is a coefficient determined in advance depending on the degree to which X ¨ _i influences X 〓 ₂ (rate of change in bearing temperature),
C ₂₀ is a value predetermined as a margin value for the current value of the rate of change of bearing temperature. The values of Y and Z are △
The calculation is performed every cycle of T and the value is held until the next calculation.

FIG. 3 is a diagram showing temporal changes in the output of each converter during operation of the generator, and T indicates an appropriate time point after the start of operation. Figure 4 shows the temporal changes in X ₂ and Y and X〓 ₂
In this figure, T is the same as T in Fig. 3, and C ₁₀ in equation (1) is expressed by X ₂ and X〓 ₂ of T time.
This shows that C ₂₀ in equation (2) is determined, and the reference values Y and Z to be used from T+ΔT to T+2ΔT are determined.

FIG. 5 is a diagram showing the difference in operation between the conventional monitoring and protection device and the device of the present invention. Between T ₁ and T ₁ +△T, the generator bearing temperature suddenly rises due to some abnormality T ₁ +△T Then, X ₂ Y, X〓 ₂ Z, the outputs of the comparators 28 and 29 become logic "1", and the output of the AND gate 30 becomes logic "1", and the protection circuit 10
works, but in the conventional device (7a=X ₂ )
9a and the protection circuit 10 operates at T ₁ +△
This is later than T, and the bearing may be damaged during that time.If 9a is set low to avoid this, there is a risk that the protection circuit 10 will malfunction due to the temperature rise of the bearing under normal conditions.

In addition, in the above embodiment, the rotation speed of the generator, the flow rate of the cooling water, and the water temperature are used as the physical quantities that affect the temperature of the generator bearing, but other physical quantities may be used. Furthermore, instead of the bearing temperature, the vibration amplitude, pressure, etc. of the bearing can be used as the monitoring target.

As described above, according to the present invention, it is possible to accurately detect an abnormality in a device and perform a desired protective operation before the abnormality progresses and causes greater damage.

[Brief explanation of drawings]

Fig. 1 is a block diagram showing a conventional device, Fig. 2 is a block diagram showing an embodiment of the present invention, and Fig. 3 shows the temperature of a bearing and changes over time in physical quantities that affect this temperature. FIG. 4 corresponds to FIG. 3 and shows temporal changes in X ₂ , Y, X〓 ₂ , and Z, and FIG. 5 shows abnormality detection by the apparatus shown in FIG. 1... Generator, 2... Rotating shaft, 3... Bearing, 5
... Cooling water pipe, 6, 15 ... Bearing temperature converter, 1
1, 14... Rotation speed converter, 12, 16... Cooling water temperature converter, 13, 17... Cooling water amount converter,
10...Protection circuit, 18, 19, 20, 21...
First-order differential circuit, 22, 23, 24, 25, respectively
. . . Second order differential circuit, 26 . . . first arithmetic circuit, and 27 . . . second arithmetic circuit. Note that the same reference numerals in each figure indicate the same or corresponding parts.

Claims (1)

[Claims] 1. A bearing temperature converter that converts the temperature of the generator bearing into an electrical signal, and physical quantities that affect the temperature of the generator bearing, such as the temperature and flow rate of cooling water for the bearing and the rotation speed of the generator. into electrical signals, each first-order differentiation circuit that differentiates the output of the above-mentioned bearing temperature converter and the output of each of the above-mentioned converters with respect to time, and the output of each of these first-order differentiation circuits is inputted. The output of each second-order differentiation circuit that further differentiates the input with respect to time, the output of the above-mentioned bearing temperature converter, and the output of each of the above-mentioned first-order differentiation circuits are inputted, and calculations are performed at predetermined intervals to calculate the output of the above-mentioned bearing temperature converter. The first reference value is the sum of the value obtained by adding a predetermined margin value to the value obtained by multiplying the output of each of the above-mentioned first-order differential circuits by a predetermined coefficient, and the first reference value or the first reference value is the bearing temperature. a first arithmetic circuit that outputs the permissible value when the predetermined permissible value of The output is input and calculations are performed at predetermined intervals, and a value obtained by adding a predetermined margin value to the output of the above-mentioned first-order differentiator circuit and a value obtained by multiplying the output of each of the above-mentioned second-order differentiator circuits by a predetermined coefficient are calculated. a second arithmetic circuit that takes the sum as a second reference value and outputs the permissible value when the second reference value or the second reference value exceeds a predetermined value as a permissible value for the rate of change in the bearing temperature; , the output of the bearing temperature converter exceeds the output of the first arithmetic circuit, and the output of the first-order differential circuit inputting the output of the bearing temperature converter exceeds the output of the second arithmetic circuit. and means for activating a protective operation when the generator bearing is in use.