JPH06101910B2 - Cooling medium temperature monitoring method for generator - Google Patents

Description

The present invention relates to a cooling medium temperature monitoring system for a generator that monitors the cooling medium temperature at the outlet of a cooling medium passage provided inside a stator coil.

[Conventional technology]

Conventionally, as a device using this type of system, there is a cooling medium temperature monitoring device for a turbine generator as shown in FIGS. 7, 8 and 9. FIG. 7 is an explanatory view showing a ventilation condition inside the turbine generator, FIG. 8 is a sectional view of a stator coil, and FIG. 9 is a monitoring circuit diagram of a cooling medium temperature at an outlet of a cooling medium passage of the stator coil. FIG.

In FIG. 7, reference numeral 1 is a frame of the generator, which has a sealed structure because hydrogen gas is enclosed in the frame. 2 is a stator core, 3 is a stator coil, 4 is a rotor, 5 is a bearing that supports both ends of the rotating shaft 4a of the rotor 4, 6 is a blower protruding from the outer periphery of the end of the rotor 4, and 7 is a hydrogen gas cooler. Is. Further, G ₁ is an arrow indicating the direction of the flow of the low-temperature hydrogen gas, G ₂
Is an arrow showing the direction of the flow of hydrogen gas inside the stator coil 3, G ₃ is an arrow showing the direction of the flow of hydrogen gas at the outlet of the cooling medium passage provided inside the stator coil 3, and G ₄ is the rotor. It is an arrow which shows the direction of the flow of hydrogen gas inside a coil.

Next, to describe the cooling action by this hydrogen gas,
The hydrogen gas is sealed in the frame 1, and is sent to the gas cooler 7 by the blower 6 by the rotation of the rotor 4 to be cooled. The cooled low-temperature hydrogen gas flows in the direction of arrow G ₁ , and flows from the gas inlet of the stator coil 3 to the stator coil 3
Passing through the inside in the axial direction (direction of arrow G ₂ ) to remove the heat generated by resistance loss of the stator coil 3 and connect to the high-temperature hydrogen gas to form an arrow from the outlet of the cooling medium passage of the stator coil 3. It is discharged in the G ₃ direction.

On the other hand, the low-temperature hydrogen gas that has entered the rotor coil of the rotor 4 flows in the axial direction (arrow G ₄ ) from both ends of this rotor coil toward the center, and the heat generated in the rotor coil is generated. It is deprived and discharged as high temperature hydrogen gas from the center of the rotor coil.

These high temperature hydrogen gas is sent to the gas cooler 7 by the blower 6 and exchanges heat with the cooling water to become a low temperature gas,
It again circulates in the directions of the above arrows G ₁ , G ₂ , G ₃ , G ₄ .

The structure near the stator coil 3 is as shown in FIG. In the figure, 12 is a stator core, 13 is a stator slot, and the stator coil 3 is inserted into this slot 13. 14 is a ground coil insulating member of the stator coil 3,
Reference numeral 15 is a stator coil conductor, and 16 is a ventilation pipe embedded in the conductor 15. The ventilation pipe 16 is provided over the entire length of the stator coil 3, and the hydrogen gas passes through the ventilation pipe 16 to cool the stator coil 3. The stator coil 3 has spacers 18 and 19 interposed. Slot wedge 20
Is held by the stator slot 13 so as not to escape.

Further, the cooling medium temperature monitoring circuit is shown in FIG. The hydrogen gas absorbs the heat of the stator coil 3 when passing through the inside of the stator coil 3, and is discharged from the outlet of the cooling medium passage, that is, the outlet of the ventilation pipe 16. Reference numeral 21 is a temperature measuring element provided at the outlet of the cooling medium passages of the plurality of stator coils 3, and measures the temperature of the hydrogen gas discharged from the outlet. The temperature signal from the temperature measuring element 21 is input to the recorder 22 and the alarm device 23.

The alarm device 23 constantly monitors the temperature signals from all the temperature measuring elements 21 and issues an alarm when the temperature detected by any of the temperature measuring elements exceeds a preset alarm value.
This alarm value is set to a constant value depending on only the temperature measurement data regardless of the load of the generator, that is, the generator current. FIG. 10 is a graph showing the relationship between the armature current, the cooling medium temperature at the outlet of the cooling medium passage, and the alarm value. In addition, here, the rise of the cooling medium temperature at the rated armature current is represented as 1 (pu).

[Problems to be solved by the invention]

Since the conventional cooling medium temperature monitoring is configured as described above, until an alarm is generated when any of the temperature signals detected by each temperature measuring element of the plurality of stator coils exceeds the above alarm value. There is a problem that it is difficult to detect an abnormality in the stator coil, and it is not possible to take prompt measures after the abnormality has occurred.

Further, the cooling medium temperature at the outlet of the cooling medium passage of the stator coil changes according to the magnitude of the armature current, but since the alarm value is constant regardless of the armature current, in the region where the armature current is small The warning value becomes more open,
If the temperature of the stator coil does not rise excessively, it is not possible to correctly judge the abnormality of the stator coil, and conversely, in the area where the armature current is large, the temperature of the cooling medium rises, which can easily lead to false alarms. It was

Furthermore, in order to detect the abnormality of the stator coil before the alarm is issued, in the past, the operator judged by comparing the change in the armature current with the time change of all temperature values displayed on the temperature recorder. However, the constant monitoring of the operator is notable for the labor, and the judgment whether the stator coil is abnormal or not is also largely dependent on the experience, and there are cases where an incorrect judgment is made.

The present invention has been made to solve the above problems, and the difference between the temperature signals obtained by the temperature measuring element at the outlet of the cooling medium passage provided inside the stator coil is determined by the same phase of the generator. An object of the present invention is to provide a cooling medium temperature monitoring system for a generator capable of issuing an alarm when the temperature difference obtained by the automatic comparison reaches an alarm value region preset according to the generator output for each band. To do.

[Means for solving problems]

According to the cooling medium monitoring system of the generator of the present invention, the temperature at the outlet of the cooling medium passage in the stator coil is measured for each of a plurality of stator coils belonging to the same phase zone,
A temperature difference is calculated for each temperature of each stator coil in the same phase band, and any of the calculated temperature differences is equal to or higher than a preset alarm value according to the generator output, that is, the armature current of a specific phase. If it does, an alarm is issued.

Moreover, the generator output uses the output signal of the current transformer put in the bus bar of a certain specific phase that is connected to the main transformer from the generator.

Further, in the cooling medium temperature difference monitoring method for the generator according to the present invention, the temperature at the outlet of the cooling medium passage in the stator coil is measured for each of a plurality of stator coils belonging to the same phase zone, and the measured two or more are measured. A temperature difference is calculated for each temperature of each stator coil in the same phase band, and one of the obtained temperature differences for each phase coil exceeds a preset alarm value according to the corresponding armature current of the corresponding phase band. In that case, an alarm was issued.

In addition, the armature current of the generator uses the output signal of each current transformer placed in the busbar of each phase that runs from the generator to the main transformer.

[Action]

According to the present invention, the temperature of the cooling medium is measured by the temperature measuring element at the outlet of each cooling medium passage of the stator coil, and this temperature measuring element is input to the temperature difference monitoring circuit and 2 A temperature difference signal is obtained for the above temperature measurement signals, and one of the thus obtained temperature difference signals for each in-phase band reaches the alarm set temperature region based on the armature current of the corresponding phase or the specific phase. Whether or not the temperature has reached the set temperature range, the alarm device is activated based on the detected output to warn the abnormality of the stator coil.

〔Example〕

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

FIG. 1 is a configuration diagram of a cooling medium temperature monitoring device for a generator used for implementing the method of the present invention. In the figure, the elements denoted by reference numerals 1 to 7 are the same as those in the conventional example, and therefore their explanations are omitted. Reference numeral 21 is a temperature measuring element provided at the outlet of the cooling medium passage provided in each stator coil 3, 22 is a temperature recorder for temperature measurement connected to many temperature measuring elements 21, and 23 is an alarm element similarly connected. Therefore, what is displayed by sound or light is used.
Further, a temperature difference monitoring circuit 24 for processing and calculating two temperature differences to be measured is connected to the temperature measuring element 21, and the operation of the alarm device is controlled based on the output of the temperature difference monitoring circuit 24. There is.

FIG. 2 specifically shows the temperature difference monitoring circuit 24. In such a circuit, the temperature measurement signal of the temperature measurement element 21 is input to each conversion element 25 provided for each temperature measurement element 21 via a cable as a change in the resistance value of the resistance temperature detector or a change in the voltage generated by the thermocouple. To be done. Each conversion element 25 outputs, for example, this input signal as a time-integrated stable analog signal, and inputs it to the microcomputer 29. on the other hand,
The armature current of the generator is detected for each phase by the DC transformer 27 that is inserted into the bus 26 that guides the generated power to the main transformer (not shown), and this detected current is input to the converter 28, and this conversion is performed. vessel
The signal 28 is input to the microcomputer 29 as a signal corresponding to the magnitude of the armature current. Reference numeral 30 is an indicating instrument, which is adapted to constantly show the temperature difference and the magnitude of the armature current as the output of the micro computer 29 to the operator.When the temperature difference exceeds the above alarm value, an alarm is issued. It is adapted to activate the device 23.

Next, the operation of the cooling medium temperature difference monitoring device having the above-mentioned configuration will be specifically described with a focus on the flow chart shown in FIG.

(A) First, the cooling medium temperatures T _{1 to} T _n at the outlet of each cooling medium passage are detected by the temperature measuring element 21 provided in the stator coil 3 of each phase, for example, each phase of U, V, W. The armature current Iph is detected from the current transformer 27 provided in a specific phase, and each of these detection signals is transmitted through the conversion element 25 and the converter 28 to the random access of the microcomputer 29.
Read into memory (hereinafter referred to as RAM).

(B) A current value I obtained by pu conversion in the microprocessor of the microcomputer 29 from the armature current Iph read in the RAM and the rated armature current Io stored in the read-only memory (hereinafter referred to as ROM) in advance. Is calculated.

(C) Next, the microprocessor of the microcomputer 29 determines whether the current value I is larger or smaller than 0.7, which is a value that greatly affects the temperature measuring element 21.

(D) As a result of this judgment, if I> 0.7, the temperature ΔT _ANN as the alarm value is set as ΔT _H × I ² (see the curve C _{1 in} FIG. 4).

(E) When I ≦ 0.7, the temperature ΔT _ANN as the alarm value is set to ΔT _L (see the boundary line C _{2 in} FIG. 4).

(F) Next, the temperature difference ΔT of the pair of temperature measuring elements in the same phase zone, that is, ΔT _{U for the} U phase, ΔT _{V for the} V phase, and ΔT _W for the W phase are obtained.

(G) The plurality of temperature differences ΔT thus obtained are the alarm values ΔT
Determine if it is greater than _ANN . That is, ΔT Determine ΔT _ANN .

(H) If there is at least one ΔT ≧ ΔT _{ANN based on} this determination, the microcomputer 29 sends a signal to the alarm device 23 to alert the driver that the stator coil is abnormal. become.

By the way, in the above temperature difference monitoring operation, even if each stator coil 3 is normal, the cooling medium temperature at the outlet of each cooling medium passage varies by about 4 to 5 ° C. at the generator rated current. Further, when the generator is operated in parallel with the actual power system, the armature currents of the respective phases may not be the same depending on the operating conditions of the system, and the variation of the cooling medium temperature may be 4 to 5 ° C. It may exceed and become even larger. Therefore,
In order to reduce the influence of such variations and increase the monitoring accuracy, it is desirable to monitor the cooling medium temperature difference for each temperature measuring element of each phase and issue an alarm when this temperature difference exceeds the set alarm value. .

5 and 6 show another embodiment of the present invention,
Further, FIGS. 1 and 4 can be applied to this embodiment as they are.

In the embodiment of the present invention, it is configured to detect whether or not any of the temperature difference signals obtained for each of the same phase bands has reached the set temperature region based on the armature current of the corresponding phase. As shown in FIG. 5, the temperature measuring element 21, the conversion element 25, the current transformer 27, and the converter 28 are provided for each phase of U, V, W.
These signals are input to the microcomputer 29 collectively for each phase of U, V and W. T _{1 to} T _i represent temperature detection signals of the temperature measuring element 21 corresponding to the stator coil 3 belonging to the U-phase band, and T _{i to} T _m are temperature measuring elements corresponding to the stator coil 3 belonging to the V-phase band. 21 indicates the temperature detection signal, and T _{n to} T _r indicate the temperature detection signal of the temperature measuring element 21 corresponding to the stator coil 3 belonging to the W-phase band. Reference numeral 30 is an indicating instrument, which is adapted to constantly show the temperature difference and the magnitude of the armature current as the output of the micro computer 29 to the operator.When the temperature difference exceeds the above alarm value, an alarm is issued. It is adapted to activate the device 23.

Next, the operation of the cooling medium temperature monitoring device having the above configuration will be described.
A detailed description will be given focusing on the flow chart shown in FIG.

(A) First, the temperature measuring elements 21 provided in the U-phase stator coil of the stator coil 3 detect the cooling medium temperatures T _{1 to} T _i at the outlets of the respective cooling medium passages, and the temperature measuring elements 21 are provided in the U phase. The U-phase armature current I _U is detected from the current transformer 27, and these detection signals are read into the RAM of the microcomputer 29 through the conversion element 25 and the converter 28.

(B) A current value I obtained by pu conversion in the processor of the microcomputer 29 from the U-phase armature current I _U read in the RAM and the rated armature current I _O stored in the ROM in advance.
Calculate (= I _U / I _O ).

(C) Next, the processor of the microcomputer 29 determines whether the current value I is larger or smaller than a value that greatly affects the temperature measuring element 21, for example, 0.7.

(D) As a result of this determination, if I> 0.7, the temperature ΔT _ANN as the alarm value is ΔT _H × I ² (the boundary curve C _{1 in} FIG.
(See) and set.

(E) If I ≦ 0.7, set the temperature ΔT _ANN as the alarm value to ΔT _L (see the boundary curve C _{2 in} FIG. 4).

(F) Next, the temperature difference ΔT _U for two or more temperature measuring elements 21 corresponding to the U phase read in the RAM is obtained.

(G) It is determined whether the temperature difference ΔT _U thus obtained is larger than the alarm value ΔT _ANN . So ΔT _U Determine ΔT _ANN .

(H) According to this judgment, if there is even one ΔT _U ≧ ΔT _ANN , the microcomputer 29 sends a signal to the alarm device 23 to warn the driver that the stator coil is abnormal. It will be.

(I) The above operations (a) to (h) are repeated for the V phase.

(J) The above operations (a) to (h) are repeated for the W phase.

(K) Again, the operation from (a) is sequentially repeated for the U phase, the V phase, and the W phase.

By the way, in the temperature difference monitoring operation, even if each stator coil 3 is normal, the cooling medium temperature at the outlet of each cooling medium passage has a variation of about 4 to 5 ° C. at the generator rated current. Also, when the generator is operated in parallel with the actual power system, the armature currents I _U , I _V , and I _W of the U, V, and W phase electric motors may be the same depending on the operating conditions of the system. However, the variation in the temperature of the cooling medium may exceed 4 to 5 ° C. and further increase. Therefore, in order to reduce the influence of such variations and improve the monitoring accuracy, the cooling medium temperature difference is obtained for each temperature measuring element 21 of each phase of U, V, W, and this temperature difference is calculated for each phase. It is desirable to monitor each phase of U, V, and W in comparison with the set temperature region obtained from the armature current and issue an alarm when the temperature difference exceeds a set alarm value.

By doing so, the armature current of each phase, for example I _U , I _V , I _W
The temperature difference due to the unbalance can be eliminated, and the monitoring accuracy can be improved, and false alarms and instructions can be prevented.

Further, as described above, the cooling temperature of each stator coil 3 changes depending on the generator output, that is, the armature current, and the temperature difference between the temperature measuring elements 21 tends to increase as the armature current increases. . Therefore, depending on the armature current,
As described above, the setting is made as shown in FIG. The alarm value corresponding to the armature current is stored in the ROM of the microcomputer 29 in advance. Here, the allowable value of the temperature difference between the temperature measuring elements 21 is set to 1 (pu), and this value can be adjusted in each generator. Further, since the temperature difference in the alarm area is small when the generator has a low load, a false alarm may occur. Therefore, the minimum value of the temperature difference between the temperature measuring elements 21 is limited in advance.

In each of the above embodiments, ΔT or ΔT _U , ΔT _V , Δ
In comparison between each temperature difference of T _W and ΔT _ANN , an alarm is issued if at least one condition is satisfied, but the number is not limited to one, and an alarm may be issued only when more than one, for example, two or more. Of course good things.

In each of the above embodiments, the turbine generator in which the stator coil 3 is cooled with hydrogen gas has been described, but the present invention can also be applied to a turbine generator in which the stator coil 3 is cooled with water or oil. In addition to directly measuring the temperature of the cooling medium, the temperature of each stator coil may be measured by a temperature measuring element embedded between each stator coil.

Further, it goes without saying that ΔT _ANN may be expressed in an appropriate functional form other than ΔT _H × I ² .

〔The invention's effect〕

As described above, according to the present invention, a plurality of temperature measuring elements are provided corresponding to each stator coil belonging to each same phase zone of the generator, and the output of the specific phase of the generator is below a certain value. Is a constant level value, and a predetermined value or more is a preset value corresponding to the output of the specific phase, and an alarm value is preset, and the temperature signal difference between the temperature signals measured by the temperature measuring element is calculated for each phase. Since it is configured to include a temperature difference monitoring circuit that obtains an alarm value for each zone classification and issues an alarm in accordance with the comparison between the alarm value and the temperature signal difference for each phase zone category, the temperature measuring element is used for the generator. It is provided corresponding to each stator coil belonging to each same phase band, and the temperature difference monitoring circuit generates an alarm value according to the comparison between the alarm value and the temperature signal difference for each phase band section. , There is variation in the current value generated for each phase, which causes temperature distribution in the stator. Also, the accuracy of the alarm output can be improved, and the alarm value is set to a constant level value when the generator output is below a certain value. The temperature signal difference does not exceed the alarm level, which is a constant level, and the alarm does not malfunction. Therefore, it is possible to prevent occurrence of thermal or insulation failure due to insufficient cooling of the generator, particularly the stator coil, and improve the reliability of the generator. In addition, the automatic monitoring by the above-mentioned alarm has an effect of reducing the labor burden on the operator.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a cooling medium temperature monitoring device for a generator used for implementing the method of the present invention, FIG. 2 is a circuit diagram showing an embodiment of a cooling medium temperature difference monitoring circuit, and FIG. FIG. 4 is a flow chart showing the flow of the circuit operation in FIG. 4, FIG. 4 is a diagram showing the relationship between the armature current and the set alarm value, and FIG. 5 is a circuit diagram showing another embodiment of the cooling medium temperature difference monitoring circuit. FIG. 6 is a flow chart showing the flow of the circuit operation of FIG.
FIG. 8 is an explanatory view showing a structure of a conventional turbine generator and a cooling gas ventilation system which are the basis of the present invention, FIG. 8 is a sectional view of the vicinity of a stator coil, and FIG. 9 is a conventional cooling medium temperature monitoring circuit. Similarly, FIG. 10 is a diagram showing a relationship between a set alarm value and a conventional armature current. In the figure, 3 is a stator coil, 4 is a rotor, 7 is a gas cooler, 2 is a stator core, 16 is a ventilation pipe, 21 is a temperature measuring element,
23 is an alarm device, 24 is a temperature difference monitoring circuit, 27 is a current transformer,
30 is an indicating instrument. In the drawings, the same reference numerals indicate the same or corresponding parts.

Claims (4)

[Claims] 1. A temperature measuring element for cooling the stator coil by flowing a cooling medium through a cooling medium passage provided inside a stator coil, and for measuring the temperature of the cooling medium at the outlet of the cooling medium passage. In a cooling medium temperature monitoring method for a generator that monitors the temperature of the cooling medium based on a temperature signal from the sensor, a plurality of measurements are provided for each of the stator coils belonging to the same phase zone of the generator. A temperature element, a current detector for detecting the output current of the generator, and an output current of the specific phase of the generator detected by the current detector is a constant value or less is a constant level value, a constant value or more is An alarm value set as a set value according to the output current of the specific phase is preset, and the temperature signal difference between the temperature signals measured by the temperature measuring element is obtained for each phase zone classification, and the alarm value and Each phase division Coolant temperature monitoring system of the generator, characterized in that a temperature difference monitoring circuit for generating an alarm in response to a comparison between the temperature signal difference. 2. The cooling medium temperature monitoring of the generator according to claim 1, wherein the output current of the specific phase of the generator is obtained from a DC transformer inserted in the bus of the specific phase. method. 3. A temperature measuring element for cooling the stator coil by flowing a cooling medium through a cooling medium passage provided inside the stator coil and measuring the temperature of the cooling medium at the outlet of the cooling medium passage. In a cooling medium temperature monitoring method for a generator that monitors the temperature of the cooling medium based on a temperature signal from the sensor, a plurality of measurements are provided for each of the stator coils belonging to the same phase zone of the generator. Temperature element,
A current detector that detects the output current of the generator, and the output current of each phase of the generator detected by the current detector is a constant value or less for each phase constant level value, a constant value or more for each The alarm value as the set value for each phase according to the output current of the phase is preset, and the temperature signal difference between the temperature signals measured by the temperature measuring element is obtained for each phase zone classification, Cooling medium temperature of a generator, comprising a temperature difference monitoring circuit for issuing an alarm in accordance with a comparison between an alarm value for each phase and a temperature signal difference for each phase zone classification corresponding to the phase Monitoring method. 4. The cooling medium temperature monitoring of the generator according to claim 3, wherein the output current of each phase of the generator is obtained from a DC transformer inserted in each phase bus. method.