JPH0687641B2 - Moisture absorption management method for rotating machines - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention prevents a decrease in insulation resistance due to moisture absorption of a winding wire of a rotating machine such as an electric motor or a generator, and prevents a sudden dielectric breakdown accident due to that. The present invention relates to a method of managing moisture absorption of a rotating machine, which is prevented.

[Conventional technology]

In general, it is said that the insulation breakdown voltage of a rotating machine remarkably drops if the insulating material of the winding of the rotating machine such as an electric motor or a generator absorbs moisture. If such a situation occurs, it will cause a sudden loss of important equipment that requires continuous operation, such as rolling mills and dust collectors in steel mills, or turbine generators in power plants, resulting in a large loss of production. Not only that, but in some cases it could cause disasters and pollution.

Therefore, it is necessary to always strictly control the moisture absorption of the rotating machine winding.

[Problems to be solved by the invention]

However, although the temperature control of the rotating machine is conventionally performed, this temperature control is not intended to manage the moisture absorption of the winding, and for example, the cooling air volume of the rotating machine is also controlled. As for the control of the cooling air volume, the air volume is controlled according to the environmental temperature difference between summer and winter from the viewpoint of energy saving and the like, not from the viewpoint of controlling the moisture absorption.

Also, regarding the control of the heater for the rotating machine, the power source is simply turned on and off to prevent moisture absorption due to temperature decrease during the stop and start of the rotating machine.

In addition, the present applicant previously found in Japanese Patent Application No. 61-202257, the change characteristic of the insulation resistance with respect to the change of the winding temperature during operation of the electric motor, and by making this correspond to the change in humidity, We have proposed an on-line moisture absorption measurement method that automatically determines the degree of moisture absorption of the motor winding under operating conditions, regardless of whether it is AC or DC, and is not affected by humidity, but this method is based on the measurement results. Since there is no means for controlling the moisture absorption within the management standard, in order to positively prevent the increase of the moisture absorption in the operating state and the stopped state of the electric motor,
It is necessary to make a human judgment to adjust the amount of moisture absorption such as turning on / off the rotary machine heater and adjusting the amount of cooling air flow, which not only takes time but also makes a mistake in such judgment or adjustment. There are problems that it may lead to a dielectric breakdown accident and may cause a trip accident due to an excessive rise in winding temperature.

The present invention has been made in view of such a conventional problem, and manages the moisture absorption in the operating state and the stopped state of the rotating machine to positively prevent the rise of the moisture absorption. It is an object of the present invention to provide a moisture absorption management method for a rotating machine, which prevents a sudden accident in a production line due to the dielectric breakdown accident, and a disaster or pollution accompanying it.

[Means and Actions for Solving Problems]

Therefore, the moisture absorption management method for a rotating machine according to the present invention is
As shown in FIG. 1, the insulation resistance measuring means and the winding temperature measuring means are used to detect changes in the insulation resistance and the temperature of the rotating machine winding at operating and stopped states at predetermined time intervals. In addition, the insulation resistance model value corresponding to the temperature change is obtained, and the insulation resistance / temperature characteristic value is calculated based on the model value and the insulation resistance actual measurement value. From the time-series data, select the representative value when the humidity rises and the representative value when the humidity falls in response to changes in the cooling air of the rotating machine, and calculate the evaluation value of the winding moisture absorption based on the integrated value of these two representative values. Then, measure the degree of moisture absorption of the winding.

Then, based on the measurement result, it is possible to maintain the moisture absorption within a predetermined management standard, so as to obtain the difference between the rotating machine winding temperature and the rotating machine cooling air temperature, the rotating machine winding temperature adjusting means, for example, , Cooling air volume, cooling air temperature, etc., for the number of rotations (voltage, frequency) of the cooling air blowing motor, the cooling air damper opening, the current value of the rotating machine cooling air heater, and the cooling air cooler (heat exchanger) 1 The control amount such as the flow rate of the next cooling medium is calculated and automatically controlled.

In this way, the moisture absorption of the rotating machine winding is controlled within the control standard.

〔Example〕

 An embodiment of the present invention will be described below with reference to the drawings.

First, the configuration will be described.

In FIG. 2, 1 is a rotating machine such as an electric motor or a generator, 2
Is a winding of the rotating machine 1, 3 is a DC power supply for the rotating machine, 4 is a fan for cooling the rotating machine, 5 is an electric motor for the cooling machine, 6
Is a rotary machine cooling air heater.

8 is an insulation resistance measuring device for measuring the insulation resistance of the winding 2, 9
Is a temperature measuring device for measuring the temperature of the winding 2, and 10 is a rotating machine 1.
Temperature measuring device for measuring the temperature of the cooling air of the
A humidity measuring device for measuring the humidity of the cooling air, 12 is a rotation detector for detecting the number of rotations of the electric motor 5 for the rotating machine cooling fan, 13
Is a current detector for detecting the current of the rotating machine cooling air heater 6,
Reference numeral 14 denotes a rotating machine load current detector that detects a load current of the rotating machine 1. These measuring devices and detectors constitute a measuring unit.

Reference numeral 16 is a microcomputer. The microcomputer 16 inputs the measurement result and the detection result from the above-mentioned measuring unit, processes the data online, and the winding 2
And the winding temperature control amount corresponding to it are calculated and output.

Reference numeral 17 is a control device for controlling the number of rotations of the electric motor 5 for the rotating machine cooling fan, 18 is a control device for controlling the current value of the rotating machine cooling air heater 6, and these control devices 17, 18 are provided from the microcomputer 16. It is a winding temperature adjusting means for performing control based on a control signal.

Next, the operation of the above embodiment will be described.

At the same time as the system is started up, the microcomputer 16 executes calculation and determination processing according to the steps shown in FIGS. 3 (a) and 3 (b).

In the step, after clearing the data area of the memory, the data is recognized and the insulation resistance initial value Mo of the rotation speed 1 set to an appropriate value, the winding temperature initial value T _MO , the cooling air temperature initial value T
_AO , cooling air humidity initial value RH _O , and rotating machine load current initial value I
Store _O in the data area and initialize.

Next, the process proceeds to step, and the loop counter CNT stores the number of times n of repeating the loop consisting of steps from step to step. This n may be determined according to the degree of change in the load of the rotating machine 1, and is normally set as n = t _R / t, assuming that data input from the measuring unit is repeated at t minute intervals for t _R time.

In the step, the insulation resistance value M from the insulation resistance measuring device 8, the winding temperature value T _M from the temperature measuring device 9 of the winding 2, the cooling air temperature value T _A from the cooling air temperature measuring device 10, the cooling air The humidity value RH from the humidity measuring device 11 and the rotating machine load current value I from the rotating machine load current detector 14
It is read in 16 and these are stored in a predetermined storage area of the memory.

Then, the process proceeds to step, where the stored insulation resistance previous value M _A (first time M _A = M _O ) and the winding temperature previous value T _MA
(The first time is T _MA = T _MO ) and the current value T _MB is called to calculate the insulation resistance model value Mm. This insulation resistance model value Mm is, as shown in FIG. 4, the previous winding temperature T _MA
Is the measurement time interval t = 1 to 10 minutes and this time the winding temperature T
It is an estimated insulation resistance value that a normal winding insulation material that does not absorb moisture abnormally when it changes up to _MB will be shown after the above temperature change, and its calculation is based on the theory of insulation resistance / temperature characteristic of 10 ° C half ( It is performed by the equation (1).

^{_{Mm = M A × 0.5 (ΔT}} / 10) (1) However, ΔT = T _MB -T _MA Next, the process proceeds to step. Here, the measured insulation resistance value M _B for the insulation resistance model value Mm predicted above is
Is calculated by the following equation (2) as insulation resistance / temperature characteristic value S.

S = M _B / Mm (2) Then, shift to the step, the previous time of the cooling air humidity data input in synchronization with the insulation resistances M _A and M _B and the winding temperatures T _MA and T _MB. The value RH _A and the current value RH _B are called from the storage area. Then, it is determined from the comparison of the two values whether or not the humidity has increased after t minutes.

This judgment result is compared with the insulation resistance / temperature characteristic value S calculated in step to select whether the characteristic value S is when the humidity is increasing (S ₁ ) or when the humidity is decreasing or is constant (S ₂ ). If the former, the process proceeds to step a, and if the latter, the process proceeds to step b. Then, the minimum value of the insulation resistance / temperature characteristic value S (that is, the state where the insulation resistance is the worst) is selected.

That is, in step a, the insulation resistance when the humidity rises /
Contents of the memory that stores the temperature characteristic value S ₁ and its minimum value
Compare with MIN. In this case, first the insulation resistance / temperature characteristic value S ₁ of the _{first time} is put in the variable MIN. As a result, MI
If N <S ₁ , it is judged as the minimum value and the process jumps to the step. On the other hand, if MIN <S _{1 is} not satisfied, the process proceeds to step a, where the content MIN of the memory is replaced with S _1, and then the process proceeds to step.

On the other hand, when the humidity drops or is constant, the insulation resistance / temperature characteristic value S ₂ is processed in the same manner as described above through steps b and b to select the minimum value.

Next, in the step, the counter CNT is decremented, and then the process proceeds to the next step. Here, the counter CN
It is determined whether the value of T has become zero. If it is not zero, the process proceeds to the step, and after it is determined that the predetermined set time t minutes has elapsed, the process returns to the step.

This step-step loop is performed n times, that is,
The process is repeated until t _R time has elapsed, and then the process proceeds to step.

In the step, the contents stored in the memory for storing the minimum value, that is, the minimum value (representative value) S _1M and S _{2M of the} above insulation resistance / temperature characteristic values are called, and the product of both values is calculated. Then, the result is calculated as a moisture absorption evaluation value CPI (= S _1M × S _2M ).

In step, it is determined whether or not the moisture absorption evaluation value CPI is less than a predetermined reference value, eg, 1.2. As a result, if the reference value is less than 1.2, it is determined that there is no moisture absorption characteristic, and the process returns to step.

On the other hand, if it is equal to or more than the reference value, it is determined that the moisture absorption characteristic is present, and the process proceeds to step.

In the step, a comparison is made with the control upper limit value of the winding temperature T _M , and if it exceeds the control upper limit value, an alarm is issued in step and an abnormality alarm is issued, and the rotating machine 1 is stopped in the step and then the process returns to the step. To do.

In the step, the difference between the rotating machine winding temperature T _M and the cooling air temperature T _A is calculated, and the difference is compared with a reference value.If the difference exceeds the reference value, abnormal moisture absorption (water infiltration or A warning of (e.g., water vapor infiltration) is issued, the rotating machine 1 is stopped in step, and then the process returns to step.

When it is determined in the step that the difference between the winding temperature T _M and the cooling air temperature T _A is smaller than the reference value, the process proceeds to the next step, and the load current I of the rotating machine 1 is determined to be large or small. to step if it exceeds the reference value I _L, in the case of less than the reference value I _L a determination to proceed in steps. In step, the load current I is compared with a reference value I _U, to step in the case of more than the reference value I _U, when the reference value I _U smaller than, the flow proceeds to step.

The step is during load operation and the rotating machine current I is a reference value.
It is a temperature control amount calculation block of the winding temperature adjusting means in the case of I _U or more, and the air amount control correction amount ΔQ of the rotating machine cooling fan 4 is expressed by the following formula (3) under the condition that the rotating machine cooling air heater 6 is stopped. Calculate by

Here, B is a constant.

Then, in step, a stop command signal for the rotating machine cooling air heater 6 is output to the control device 18, and an air flow correction value ΔQ of the rotating machine cooling fan 4 is output to the control device 17.

The step is a temperature control amount calculation block of the winding temperature adjusting means when the rotating machine load current I is smaller than the reference value I _U during load operation, and the air volume of the rotating machine cooling fan 4 according to the formula (3). Along with the control correction amount ΔQ, the current control correction amount ΔI _H of the rotary machine cooling air heater 6 is calculated by the following equation (4).

Here, A is a constant.

Then, in steps, the control correction amounts ΔI _H and ΔQ are output to the controller 18 of the rotary machine cooling air heater 6 and the controller 17 of the rotary machine cooling fan electric motor 5, respectively.

The step is a temperature control amount calculation block of the winding temperature adjusting means when the rotating machine 1 is stopped, and includes the rotating machine cooling fan 4
Under the condition that the electric motor 5 is stopped, the control correction amount ΔI _H of the rotary machine cooling air heater 6 is calculated by the equation (4). In a subsequent step, the stop command signal for the rotating machine cooling fan 4 and the control correction amount ΔI _H are output to the controller 17 for the rotating machine cooling fan electric motor 5 and the controller 18 for the rotating machine cooling air heater 6, respectively. .

After any of the above steps 1 to 3 is completed, the process returns to the step.

By repeating the above determination and processing, the moisture absorption of the winding is managed both when the rotating machine 1 is operating and when it is stopped.

Only the humidity absorption measuring method described in Japanese Patent Application No. 61-202257 described above is applied to one of the tandem rolling mills having six stands, and the temperature controlling means for the windings as in the present invention is not controlled. And the embodiment to which the present invention is applied, the RMS (Root
Mean Square) value (%), Insulation resistance measurement value of winding 2 M
(MΩ), humidity of cooling air RH (%), temperature of cooling air T _A (° C) are shown in FIGS. 5 and 6, respectively.

As can be seen from both figures, the cooling air humidity RH is about 80 in both examples.
%, The variation of the insulation resistance is smaller with respect to the change of the operating condition (change of load current or stop), and the minimum value of the insulation resistance is the same as that of the embodiment of the present invention. The value is 0.28 MΩ in the example, which is considerably higher than the value of 0.17 MΩ in the conventional example, and the effect of application of the present invention appears.

In the above embodiment, as the winding temperature adjusting means of the rotating machine 1, the rotating machine cooling fan 4 and the rotating machine cooling air heater 6 are used.
Other than that, for example, a cooling air cooler may be added, a compressed air supply device may be used instead of the rotating machine cooling fan 4, and a heat exchanger may be used as the rotating machine cooling air heater 6. Needless to say, any winding temperature can be freely adjusted within a required range.

〔The invention's effect〕

As described above, according to the moisture absorption management method for a rotating machine of the present invention, the insulation resistance measuring means and the winding temperature measuring means are used to measure the insulation resistance and the temperature of the rotating machine winding in the operating state and the stopped state. A change is detected at a predetermined time interval, an insulation resistance model value corresponding to the temperature change is obtained for each detection, and an insulation resistance / temperature characteristic value is calculated based on the model value and the insulation resistance actual measurement value. From the obtained predetermined number of insulation resistance / temperature characteristic value time series data, the representative value when the humidity rises and the representative value when the humidity falls are selected according to the humidity change of the cooling air of the rotating machine. An evaluation value of winding moisture absorption is calculated based on the integrated value, the winding temperature control amount of the rotating machine is calculated according to the evaluation value, and the winding temperature adjustment means is controlled according to the control amount. , Management of moisture absorption of the rotating machine winding, This is possible regardless of whether the vehicle is in operation or stopped, and thus it is possible to prevent the production line from being suddenly stopped due to an unexpected dielectric breakdown accident, and to prevent accidents such as disasters and pollution.

[Brief description of drawings]

FIG. 1 is a flow chart showing the basic configuration of a moisture absorption management method for a rotating machine according to the present invention, and FIG. 2 is a schematic configuration diagram of an embodiment of an apparatus for realizing the moisture absorption management method for a rotating machine according to the present invention. 3 (a) and 3 (b) are flowcharts showing the procedure of processing executed in the microcomputer, FIG. 4 is a diagram showing the principle of measuring the moisture absorption of the winding used in the present invention, and FIG. FIG. 6 is a graph showing the time transition of various measured values by the method, and FIG. 6 is a graph showing the time transition of various measured values by the method of the present invention. 1 ... Rotating machine, 2 ... winding, 4 ... Rotating machine cooling fan, 5 ... Rotating machine cooling fan electric motor, 6 ... Rotating machine cooling air heater, 8 ... Insulation resistance measuring device, 9 ... … Winding temperature measuring device, 10 …… Cooling air temperature measuring device, 11 …… Cooling air humidity measuring device, 12 …… Fan motor rotation detector, 13 ……
Heater current detector, 14 ... Rotating machine load current detector, 16 ...
… Microcomputer, 17 …… Motor controller, 18…
... Heater control device.

Claims (1)

[Claims] 1. An insulation resistance measuring means and a winding temperature measuring means are used to detect a change in insulation resistance and temperature of a rotating machine winding in a running state and a stopped state at predetermined time intervals, and the temperature is detected at each detection. Insulation resistance / temperature characteristic value is calculated based on the model value and the measured insulation resistance value, and the obtained insulation resistance / temperature characteristic value time-series data is obtained. The representative value when the humidity rises and the representative value when the humidity falls are selected in accordance with the change in the cooling air of the rotating machine, and the evaluation value of the winding moisture absorption is calculated based on the integrated value of these two representative values. A method for managing moisture absorption of a rotating machine, which calculates a winding temperature control amount of a rotating machine according to an evaluation value, and controls a winding temperature adjusting means according to the control amount.