CN116231972A - System and method for detecting temperature of winding of rotor of wound induction hydraulic generator - Google Patents
System and method for detecting temperature of winding of rotor of wound induction hydraulic generator Download PDFInfo
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- H—ELECTRICITY
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Abstract
The invention discloses a system and a method for detecting the temperature of a rotor winding of a wound induction hydraulic generator, wherein the system comprises: the winding type rotor comprises a plurality of rotor teeth, wherein the centers of the rotor teeth are provided with grooves; a spiral coil including a thermistor embedded in the grooves of the rotor teeth; the voltage module is connected with the spiral coil and is used for providing constant direct-current voltage for the spiral coil so as to enable the spiral coil to generate current; the acquisition and analysis module is used for acquiring magnetic field information generated by the spiral coil and analyzing and acquiring temperature data on the winding type rotor according to the magnetic field information. The invention can complete the on-line monitoring of the temperature state of the winding at the central part of the rotor of the wound induction hydraulic generator in the running process, ensure higher precision, provide guarantee for the stable running of the motor in the hydroelectric generation process, provide reference data for the safety of the motor state and prolong the service life of the unit. The invention can be widely applied to the technical field of hydraulic generators.
Description
Technical Field
The invention relates to the technical field of hydraulic generators, in particular to a system and a method for detecting the temperature of a winding of a rotor of a wound induction hydraulic generator.
Background
Renewable energy is used as a green low-carbon energy, and the renewable energy is used for generating electricity, so that the carbon emission can be greatly reduced, the natural resources are saved, and the ecological environment is protected. The hydroelectric power generation is an important renewable energy power generation mode, and has higher specific gravity in various renewable energy power generation systems at present; and the small hydropower station is one of the main means of distributed new energy power generation in China at the present stage. The traditional hydroelectric generator adopts an electric excitation synchronous motor mode, the optimal rotating speed working point of the generator is difficult to adjust, the system operation efficiency and the power generation capacity are greatly influenced by water level conditions, and the power generation load is difficult to adjust and optimize along with actual conditions.
Doubly-fed generators employing wound induction motors have been widely used in the field of wind power generation and have the characteristics of being equally suitable for hydroelectric power generation systems, particularly new energy power generation systems such as small hydropower stations. The hydro-generator adopting the wound induction motor can adjust the rotation speed of the generator according to the requirement, realize variable-speed constant-frequency power generation and give consideration to the output requirement, optimally adjust the load of the generator according to the actual environment condition, and improve the running efficiency of the system. So the traditional electric excitation water turbine keeps the stator structure unchanged, and the electric excitation rotor is replaced by a winding type asynchronous motor rotor. However, since the hydraulic generator has relatively large power and serious wire heating problem, the wire temperature state needs to be evaluated in real time, and the wound rotor is different from the stator, the rotating motion state is always kept in the working process, the difficulty of measuring the temperature of the wire of the rotor winding, especially the wire which is seriously heated and positioned at the center of the axial structure of the rotor is increased, and the traditional stator temperature detection method such as embedding a thermocouple and the like is not applicable any more. If the wireless sensor is used for detecting the temperature of the winding at the central part of the axial structure of the rotor, the signal transmission is most likely to be affected under the condition of high-power strong magnetic field interference of the hydraulic generator; and the sensor belongs to the precision instrument, and the sensor at the rotor position is easy to damage when the motor works due to the small space, and the uncertainty of the temperature read by the sensor is increased and the maintenance cost is increased under the conditions. The finding of a feasible temperature detection method is necessary for guaranteeing the safe and stable operation of the wound rotor hydraulic generator.
Disclosure of Invention
In order to solve at least one of the technical problems existing in the prior art to a certain extent, the invention aims to provide a system and a method for detecting the temperature of a winding of a rotor of a wound-rotor induction hydraulic generator.
The technical scheme adopted by the invention is as follows:
a system for temperature detection of a wound rotor winding of a wound induction hydro-generator, comprising:
the winding type rotor comprises a plurality of rotor teeth, wherein the centers of the rotor teeth are provided with grooves;
a spiral coil including a thermistor embedded in the grooves of the rotor teeth; the spiral coil comprises a thermistor, namely the resistance value of the spiral coil changes along with the change of temperature, namely the resistance value of the spiral coil is different at different temperatures; specifically, the spiral coil can be made of a thermistor, and the spiral coil can also comprise a thermistor part;
the voltage module is connected with the spiral coil and is used for providing constant direct-current voltage for the spiral coil so as to enable the spiral coil to generate current;
the acquisition and analysis module is used for acquiring magnetic field information generated by the spiral coil and analyzing and acquiring temperature data on the winding type rotor according to the magnetic field information.
Further, the voltage module includes:
the AC/DC converter is connected with a rotor collecting ring of the wound-rotor hydraulic generator and is used for converting three-phase alternating voltage into direct voltage;
and one end of the direct-current voltage-stabilizing boost power supply is connected with the AC/DC converter, and the other end of the direct-current voltage-stabilizing boost power supply is connected with the spiral coil and is used for stabilizing the voltage value of the converted direct-current voltage so as to ensure that the voltage on the spiral coil is unchanged.
Further, the grooves of the rotor teeth are round grooves, and the groove depth is consistent with the rotor winding groove depth; the number of rotor teeth that need to be slotted is determined based on the total number of helical coils.
Further, the number of turns N of the spiral coil q Equal to the number of turns N of the rotor winding r After all spiral coils are embedded, the head and tail parts of the lead-out heads are connected according to the rule of generating magnetic fields by current.
Further, the pole pair number p formed by connecting the spiral coils L Not equal to the number of rotor grooves Q 2 Integer multiple of the pole pair number p L Is half the number of the total spiral coils.
Further, the pole pair number p L And rotor groove number Q 2 The relationship of (2) is as follows:
p L /Q 2 score =score
According to the principle of electromagnetic field of motor, when the number of magnetic pole pairs p L Not equal to the number of rotor grooves Q 2 When the integer multiple of the number is achieved, the k (1-s) subharmonic content in the air gap magnetic field generated by the three-phase induction motor is very small.
The invention adopts another technical scheme that:
a method for detecting the temperature of a winding of a rotor of a wound-type induction hydraulic generator comprises the following steps:
embedding a helical coil in a slot of a rotor tooth of a wound rotor; wherein the spiral coil comprises a thermistor;
providing a constant direct current voltage to the spiral coil so as to generate current on the spiral coil;
magnetic field information generated by the spiral coil is collected, and temperature data on the winding type rotor are obtained according to magnetic field information analysis.
Further, the collecting magnetic field information generated by the spiral coil, analyzing and obtaining temperature data on the wound rotor according to the magnetic field information, includes:
since the resistance of the thermistor changes with temperature, the current in the coil changes according to the resistance without changing the voltage applied to the spiral coil, thereby changing the magnetic field strength generated in the coil and affecting the frequency f 1 The magnitude of the lower back emf;
according to frequency f 1 And acquiring temperature data on the wound rotor according to the relation between the lower counter potential amplitude and the rotor temperature.
Further, the frequency f 1 The expression of (2) is as follows:
wherein k is the number p of pole pairs formed by spiral coils L P to the pole pair of the motor m The ratio s is slip ratio when the wire-wound hydraulic generator operates, and f is generator electromotive force frequency.
Further, the method further comprises pre-acquiring the frequency f 1 The step of the relation between the magnitude of the lower back emf and the rotor temperature:
a1, embedding a thermocouple in the central position of the wound rotor to enable the rotor to be in a static state, introducing current into a rotor winding, starting heating of the winding under the action of the current, and setting an initial detection temperature value according to insulation capability by the thermocouple because the thermocouple is in the static state and can measure a wire temperature value at the central position of the wound rotor;
a2, immediately disconnecting the current and the thermocouple detection end when the measured temperature of the central winding of the rotor reaches an initial detection temperature value, enabling the rotor to reach a rated rotation speed in a prime motor dragging mode, and testing a counter electromotive force waveform of the stator at the moment;
a3, after the test in the step A2 is finished, returning the rotor to a static state again, accessing a thermocouple detection end, enabling the thermocouple detection temperature value to be stable at a preset maintaining time of an initial detection temperature value in a preset mode, disconnecting again, and testing a stator counter electromotive force waveform at the moment in the preset mode;
a4, recovering the static state again after the step A3 is finished, accessing a thermocouple detection end, introducing preset current to continuously heat the rotor winding, immediately disconnecting the current and the thermocouple detection end when the temperature is detected to reach the temperature of the set interval by setting a temperature rise interval, repeating the step A2 process, repeating the step A3 process after the test is finished, and testing the counter electromotive force waveform of the stator in the steady-state temperature state;
a5, setting a cutoff temperature according to the insulation grade, testing the waveform of the counter electromotive force of the stator in a steady state of the cutoff temperature of the rotor center winding, and ending the experiment.
The beneficial effects of the invention are as follows: according to the invention, a sensor and a thermocouple are not needed when the generator runs, the real-time on-line monitoring of the temperature state of the winding at the central part of the rotor of the wound-rotor induction hydraulic generator in the running process can be completed, higher precision is ensured, the sensor is not needed, so that the fault rate, maintenance difficulty and cost of a detection system are reduced, reference data are provided for the state safety of the generator in the hydroelectric generation process, the stable running of the generator is ensured by matching with a power generation control system, and the service life of a unit is prolonged.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following description is made with reference to the accompanying drawings of the embodiments of the present invention or the related technical solutions in the prior art, and it should be understood that the drawings in the following description are only for convenience and clarity of describing some embodiments in the technical solutions of the present invention, and other drawings may be obtained according to these drawings without the need of inventive labor for those skilled in the art.
FIG. 1 is a schematic view of a rotor core of a typical wound induction hydro-generator;
FIG. 2 is a schematic diagram of a rotor tooth slotting position along a rotation axis direction in an embodiment of the present invention;
FIG. 3 is a schematic illustration of the slotting position of rotor tooth portions in one tooth of a radial plane of the motor in an embodiment of the invention;
FIG. 4 is a schematic illustration of the manner in which the connection between the spiral coils of the thermistor placed in each tooth slot forms a magnetic pole in an embodiment of the present invention;
fig. 5 is a schematic diagram of the overall structure of the rotor center winding temperature detection system on the rotating side of the motor according to the embodiment of the invention.
Detailed Description
Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings, wherein like or similar reference numerals refer to like or similar elements or elements having like or similar functions throughout. The embodiments described below by referring to the drawings are illustrative only and are not to be construed as limiting the invention. The step numbers in the following embodiments are set for convenience of illustration only, and the order between the steps is not limited in any way, and the execution order of the steps in the embodiments may be adaptively adjusted according to the understanding of those skilled in the art.
In the description of the present invention, it should be understood that references to orientation descriptions such as upper, lower, front, rear, left, right, etc. are based on the orientation or positional relationship shown in the drawings, are merely for convenience of description of the present invention and to simplify the description, and do not indicate or imply that the apparatus or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and thus should not be construed as limiting the present invention.
In the description of the present invention, a number means one or more, a number means two or more, and greater than, less than, exceeding, etc. are understood to not include the present number, and above, below, within, etc. are understood to include the present number. The description of the first and second is for the purpose of distinguishing between technical features only and should not be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated or implicitly indicating the precedence of the technical features indicated.
In the description of the present invention, unless explicitly defined otherwise, terms such as arrangement, installation, connection, etc. should be construed broadly and the specific meaning of the terms in the present invention can be reasonably determined by a person skilled in the art in combination with the specific contents of the technical scheme.
Based on the defects of the prior art, the invention aims to provide a method and a system capable of detecting the temperature of a winding at the center of a rotor of a wound induction hydraulic generator in real time, which can finish on-line monitoring of the temperature state of the winding at the center of the rotor of the wound induction hydraulic generator in the running process, ensure certain precision, provide guarantee for the stable running of a motor in the hydroelectric generation process, provide reference data for the safety of the state of the motor and prolong the service life of a unit.
In order to achieve the above object, the main idea of the method of the present invention is: because the rotor tooth part of the doubly-fed hydraulic generator is generally larger, the space is enough, a thermistor can be made into a spiral coil to be embedded in the center part of the rotor tooth, then the thermistor coil is connected into a coil group with a certain number of relations with the number of magnetic poles of a motor, voltage is led out from the collector ring of the rotor, the converted voltage is led into the thermistor coil through a rectifying and power supply voltage stabilizing device, and a magnetic field is generated after the coil is electrified. According to the heat conduction relation, the resistance of the thermistor coil can change along with the change of the temperature of the central winding of the motor rotor, and the introduced voltage is kept unchanged, so that the current of the thermistor coil can change, the change of a magnetic field generated by the coil is caused, and the corresponding average temperature data of the winding at the center of the rotor can be obtained by testing and analyzing the counter electromotive force of the stator winding at the corresponding position.
Specifically, the present embodiment is realized by:
in the manufacturing and processing process of the rotor core, a circular groove with proper size is uniformly formed in each tooth along the circumferential range at the center of the tooth part of the winding rotor at the axial middle position, the groove depth is equal to the groove depth of the rotor winding, and the groove diameter is not excessively large so as not to influence the mechanical strength of the tooth part, so that the winding is placed in the winding.
Step 2, manufacturing spiral coils by using thermistors, embedding the spiral coils in grooves in the center of rotor teeth, wherein the number of turns of the coils can be equal to that of turns of rotor windings, connecting the head and the tail of each coil after all the coils are embedded according to rules to form fixed magnetic pole numbers, leading out the voltage on a winding rotor in a specific mode, connecting the voltage with a thermistor coil group with the determined magnetic pole numbers in an end-to-end mode, enabling the thermistor coils to obtain the voltage and generate current, and generating a magnetic field in the spiral tube by the current.
And 3, as the stator part is fixed in the whole operation process, the test wire can be embedded and the related detection is easy to carry out. The method of the invention adopts a part of coils of a certain phase winding to be embedded into a test wire at the stator winding corresponding to the placement position of the spiral coil of the thermistor, and the part of coils are connected with an external monitoring device to measure the back electromotive force waveform of the part of windings selected at the position.
Step 4, carrying out Fourier analysis on the tested counter electromotive force to find out the magnetic pole pair number p formed by the counter electromotive force and the thermistor spiral coil L Corresponding frequency part, p in the motor operation process L The rotation speed of the corresponding part of the magnetic field is the actual rotation speed n of the rotor.
According to the electromagnetic relation of the motor, the number p of the magnetic pole pairs L Corresponding frequency f 1 The method comprises the following steps:
f 1 ＝np L /60
wherein n is the rotation speed of the motor rotor and is different from the synchronous rotation speed of the magnetomotive force of the stator and the rotor, so the frequency f 1 Unlike the generation frequency (i.e., the frequency of the connected grid).
Because the resistance of the thermistor can change along with the change of temperature, under the condition that the voltage led into the spiral coil of the thermistor from the winding rotor is unchanged, the current in the coil can change, so that the strength of a magnetic field generated in the coil is changed, and the counter potential of a winding part corresponding to the strength of the magnetic field is influenced to change under the corresponding frequency. Namely, the counter potential of the frequency part corresponding to the number of the poles of the spiral coil of the thermistor can change along with the change of temperature after the counter potential Fourier analysis tested by the measuring device.
Step 5, adopting an analytical calculation and a sensor or thermocouple temperature rise experiment test method before the wound rotor type hydraulic generator is formally put into use to obtain the frequency f 1 The relationship between the back-emf amplitude and rotor temperature is tabulated. The actual running process of the generator can be realized without a sensor or a thermocouple by only observing the collected frequency in real timeIs f 1 The counter potential waveform amplitude of (2) judges the highest temperature value of the winding at the center of the rotor in a table look-up mode.
The foregoing is further explained with reference to the drawings and the detailed description.
A typical wound induction hydro-generator rotor core employs open slots, similar to the rotor core structure shown in fig. 1 in this example.
First, in the manufacturing process of a rotor core of a wound induction hydraulic generator, the wound rotor is axially positioned at a middle position, as shown in fig. 2; the center of the tooth part of the radial plane of the motor is provided with a circular groove with proper size on each tooth according to the grooving mode of one tooth shown in fig. 3 along the circumferential range, and the groove depth is basically equivalent to the groove depth of the rotor winding. The number of teeth of the rotor to be grooved is selected uniformly according to the number of turns of the thermistor spiral line, and the diameter of the grooves is not required to be too large so as not to influence the mechanical strength of the tooth part, as shown in fig. 3, and the grooves are enough to be placed into coils. The coil position is near the most central position of the rotor winding of the wound-type hydro-generator.
And secondly, manufacturing a spiral coil by using a thermistor, and embedding the spiral coil in a groove at the center of the rotor tooth formed in the step.
In the present embodiment, the number of turns N of the coil q Equal to the number of turns N of the rotor winding r After all coils are embedded, the head and tail parts of the lead-out heads are connected according to the rule of generating magnetic fields by current. In this example, the number p of pole pairs formed by connecting spiral coils of a thermistor L Not equal to the number of rotor grooves Q 2 Integer multiple of the pole pair number p L Is half of the total number of thermistor spiral coils, and the thermistor spiral coils are connected to form magnetic poles in a manner shown in fig. 4. In fig. 4, i is the direction of direct current, and since the voltage provided by the direct current voltage-stabilizing boost power supply is unchanged, the resistance of the thermistor will change with temperature, and the magnitude of the current i will change with the change of the temperature of the winding at the center of the axial structure of the rotor, and when the number of turns of the spiral coil of the thermistor is unchanged, the change of the air gap magnetic field is only related to the current i. N, S each represent a magnetic pole direction.
And a third step of: three-phase alternating voltage is led out from a collecting ring of a rotor of a wound hydraulic generator and then is connected with an AC/DC converter, the three-phase alternating voltage is converted into direct voltage and then is connected with a direct-current voltage stabilizing and boosting power supply, the devices can be assembled on a rotating shaft of the generator together with the collecting ring, alternating current on the rotor is converted into stable direct voltage, then the direct-current voltage stabilizing and boosting power supply is connected with the head end and the tail end of a thermistor coil group in a mode of embedding a wire through a groove in the rotating shaft, the thermistor coil obtains constant voltage and generates current, the current generates a magnetic field in a spiral tube, and the overall rotor system structure schematic diagram is shown in figure 5.
Fourth step: in order to make the detected counter potential signal easier to extract, the part of the stator A phase winding, which is close to the thermistor spiral coil, is embedded with a test winding or directly led out of the head end and the tail end of the part A phase winding, and no load is connected, and the no-load counter electromotive force waveform is tested by using devices such as an oscilloscope.
Fifth step: fourier analyzing the tested counter electromotive force to find the magnetic pole pair number p formed by the thermistor spiral coil L Counter potential amplitude value under corresponding frequency, and magnetic pole pair number p according to motor electromagnetic relation L Corresponding frequency f 1 The method comprises the following steps:
f 1 ＝np L /60
wherein n is the actual rotation speed of the rotor of the wound induction hydraulic generator and is different from the synchronous rotation speed n of the magnetomotive force of the stator and the rotor s ：
n s ＝60f/p m
Wherein p is m For the number of pairs of magnetic poles of the motor, f is the electromotive force frequency of the generator, and is generally 50Hz, n and n of standard frequency accessed to a power grid s The relation between the two is:
n＝n s (1-s)
in the above formula, s is slip when the wound-type induction hydraulic generator operates.
The frequency f selected in this example 1 The relationship with the generator electromotive force frequency f is as follows:
i.e.
Wherein k is the pole pair number p formed by the thermistor spiral coil L P to the pole pair of the motor m Ratio of the two components. In this example, p is selected L And rotor groove number Q 2 The following relationship is provided:
p L /Q 2 score =score
According to the principle of the electromagnetic field of the motor, when p L Not equal to the number of rotor grooves Q 2 In the air-gap magnetic field generated by the three-phase induction motor, the k (1-s) subharmonic content is very small, so that the k (1-s) subharmonic electromotive force generated by the motor is close to zero, thus the f obtained by adopting the method of the invention 1 The electromotive force at the frequency is more easily separated and identified. Since the resistance of the thermistor changes with temperature, the current in the coil will change under the condition that the voltage applied to the spiral coil of the thermistor is unchanged, thereby changing the intensity of the magnetic field generated in the coil and affecting f 1 The magnitude of the back emf at frequency.
Step six, adopting an analytical calculation and sensor or thermocouple temperature rise experiment test method before the wound rotor type hydro-generator is formally put into use to obtain the frequency f 1 The relationship between the magnitude of the lower back emf and the rotor temperature is tabulated. The manner in which this example takes is as follows:
after the winding type hydraulic generator completes the assembly of the thermistor spiral coil, the DC voltage source of the DC converter and the counter potential test wire in the first three steps of the implementation mode, one test experiment is added in the experiment before the input.
1) Embedding a thermocouple in the central position of the wound rotor, enabling the rotor to be in a static state, introducing maximum current which is calculated through analysis in the design process into a rotor winding, and starting heating the winding under the action of current, wherein the thermocouple can measure the temperature value of a wire at the central position of the wound rotor in the static state, the initial detection temperature value is set according to the insulation capacity, and the initial detection temperature value is set to 100 ℃ when F-level insulation is used;
2) When the measured temperature of the central winding of the rotor reaches 100 ℃, immediately disconnecting the current and the thermocouple detection end, enabling the rotor to reach the rated rotation speed in a prime motor dragging mode, and testing the counter electromotive force waveform of the stator at the moment;
3) After the test of the previous step is finished, the rotor is returned to a static state again, a thermocouple detection end is connected, the thermocouple detection temperature value is stabilized at 100 ℃ for 30 minutes by introducing proper current and the like, then the rotor is disconnected again, and the back electromotive force waveform of the stator at the moment is tested in the same way as in the step 2;
4) And 3, recovering the static state again after the step 3 is finished, accessing a thermocouple detection end, introducing proper current (the maximum current can be smaller than the maximum current in running for protecting the winding) to continuously heat the rotor winding, setting a detection temperature rise interval, namely immediately disconnecting the current and the thermocouple detection end when the temperature reaches 105 ℃ in the example, repeating the step 2 process, repeating the step 3 process after the test is finished, and testing the counter electromotive force waveform of the stator in the steady state at 105 ℃. The above test procedure was repeated again every five degrees of increase in temperature rise later.
5) The cut-off temperature is set according to the insulation grade, and for protecting the motor, the F-grade insulation can be set to 145 ℃, namely after the stator back electromotive force waveform in steady-state operation at 145 ℃ of the rotor center winding temperature is tested, the experiment is finished.
In all the experimental processes, the voltage of the direct-current voltage source which is introduced into the thermistor spiral coil is required to be kept unchanged.
According to the heat transfer rule, the temperature rise of the rotor winding inevitably causes the temperature rise of the spiral coil of the thermistor nearby, and then the resistance change of the coil is caused. The current in the coil will change under the condition of unchanged voltage, so that the magnetic field generated by the coil changes, and the counter potential measured at the stator is equal to f 1 The harmonic electromotive force amplitude at frequency changes. Fourier analysis is carried out on the stator back electromotive force waveforms measured by all experiments to find out the central temperature transients of different rotor windingsAnd the amplitude of the k (1-s) subharmonic frequency of the corresponding back electromotive force under the steady state is recorded, data fitting or extension is carried out by using a computer numerical method, a data table and temperature judging mode is formed, and a computer analysis program is compiled. In order to improve the detection precision, the correlation coefficient in the data table can be further corrected by adopting a mode of theoretical analysis and thermodynamic finite element simulation analysis on actual working conditions.
Seventh step: through all the processes, the final realization does not need a sensor and a thermocouple, and only needs to detect the counter potential waveform of the stator and Fourier analyze the f 1 The harmonic electromotive force amplitude under the frequency is used for finding out the corresponding central temperature value of the rotor winding in a data table checking mode by a computer, carrying out real-time on-line monitoring on the temperature state of the hydro-generator during operation, providing guarantee for the stable operation of the motor in the hydroelectric power generation process, providing reference data for the safety of the motor state and prolonging the service life of the unit.
In summary, compared with the prior art, the embodiment has at least the following advantages:
(1) According to the invention, the temperature-free sensor and the thermocouple of the winding temperature state of the central part of the internal rotor of the wound-rotor-type induction hydraulic generator can be monitored online in real time in the running process of the wound-rotor-type induction hydraulic generator, a certain precision is ensured, the fault rate and the maintenance cost of a detection system are reduced, reference data are provided for the state safety of the motor in the hydroelectric generation process, and the service life of the generator set is prolonged by auxiliary running control.
(2) Three-phase alternating voltage is led out from a collecting ring of a rotor of the wound hydraulic generator and then is connected with an AC/DC converter, the three-phase alternating voltage is converted into direct voltage and then is connected with a direct-current voltage-stabilizing boosting power supply, and the devices can be assembled on a rotating shaft of the generator together with the collecting ring, so that the structure is simple and the implementation is easy.
In the foregoing description of the present specification, reference has been made to the terms "one embodiment/example", "another embodiment/example", "certain embodiments/examples", and the like, means that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, schematic representations of the above terms do not necessarily refer to the same embodiments or examples. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.
While embodiments of the present invention have been shown and described, it will be understood by those of ordinary skill in the art that: many changes, modifications, substitutions and variations may be made to the embodiments without departing from the spirit and principles of the invention, the scope of which is defined by the claims and their equivalents.
While the preferred embodiment of the present invention has been described in detail, the present invention is not limited to the above embodiments, and various equivalent modifications and substitutions can be made by those skilled in the art without departing from the spirit of the present invention, and these equivalent modifications and substitutions are intended to be included in the scope of the present invention as defined in the appended claims.
Claims (10)
1. A system for temperature detection of a winding of a rotor of a wound induction hydro-generator, comprising:
the winding type rotor comprises a plurality of rotor teeth, wherein the centers of the rotor teeth are provided with grooves;
a spiral coil including a thermistor embedded in the grooves of the rotor teeth;
the voltage module is connected with the spiral coil and is used for providing constant direct-current voltage for the spiral coil so as to enable the spiral coil to generate current;
the acquisition and analysis module is used for acquiring magnetic field information generated by the spiral coil and analyzing and acquiring temperature data on the winding type rotor according to the magnetic field information.
2. The system for temperature sensing of a rotor winding of a wound induction hydro-generator as defined by claim 1 wherein the voltage module comprises:
the AC/DC converter is connected with a rotor collecting ring of the wound-rotor hydraulic generator and is used for converting three-phase alternating voltage into direct voltage;
and one end of the direct-current voltage-stabilizing boost power supply is connected with the AC/DC converter, and the other end of the direct-current voltage-stabilizing boost power supply is connected with the spiral coil and is used for stabilizing the voltage value of the converted direct-current voltage so as to ensure that the voltage on the spiral coil is unchanged.
3. The system for detecting the temperature of a rotor winding of a wound rotor induction hydraulic generator according to claim 1, wherein the grooves of the rotor teeth are circular grooves, and the groove depth is consistent with the groove depth of the rotor winding; the number of rotor teeth that need to be slotted is determined based on the total number of helical coils.
4. The system for detecting temperature of a rotor winding of a wound induction hydro-generator as defined by claim 1 wherein the helical coil has a number of turns N q Equal to the number of turns N of the rotor winding r After all spiral coils are embedded, the head and tail parts of the lead-out heads are connected according to the rule of generating magnetic fields by current.
5. The system for detecting the temperature of a rotor winding of a wound induction hydro-generator as defined by claim 1 wherein the spiral coils are connected to form a pole pair p L Not equal to the number of rotor grooves Q 2 Integer multiple of the pole pair number p L Is half the number of the total spiral coils.
6. The system for detecting temperature of a rotor winding of a wound rotor induction hydro-generator as defined by claim 5 wherein the pole pair number p L And rotor groove number Q 2 The relationship of (2) is as follows:
p L /Q 2 score =score
According to the principle of electromagnetic field of motor, when the number of magnetic pole pairs p L Not equal to the number of rotor grooves Q 2 When the integer multiple of the number is achieved, the k (1-s) subharmonic content in the air gap magnetic field generated by the three-phase induction motor is very small.
7. The method for detecting the temperature of the rotor winding of the wound-type induction hydraulic generator is characterized by comprising the following steps of:
embedding a helical coil in a slot of a rotor tooth of a wound rotor; wherein the spiral coil comprises a thermistor;
providing a constant direct current voltage to the spiral coil so as to generate current on the spiral coil;
magnetic field information generated by the spiral coil is collected, and temperature data on the winding type rotor are obtained according to magnetic field information analysis.
8. The method for detecting the temperature of a rotor winding of a wound-rotor induction hydraulic generator according to claim 7, wherein the step of collecting magnetic field information generated by the spiral coil and analyzing the temperature data on the wound-rotor according to the magnetic field information comprises the steps of:
since the resistance of the thermistor changes with temperature, the current in the coil changes according to the resistance without changing the voltage applied to the spiral coil, thereby changing the magnetic field strength generated in the coil and affecting the frequency f 1 The magnitude of the lower back emf;
according to frequency f 1 And acquiring temperature data on the wound rotor according to the relation between the lower counter potential amplitude and the rotor temperature.
9. A method for detecting the temperature of a rotor winding of a wound induction hydro-generator as defined by claim 8 wherein the frequency f 1 The expression of (2) is as follows:
wherein k is the number p of pole pairs formed by spiral coils L P to the pole pair of the motor m The ratio s is slip ratio when the wire-wound hydraulic generator operates, and f is generator electromotive force frequency.
10. The method of claim 8, further comprising pre-acquiring a frequency f 1 The step of the relation between the magnitude of the lower back emf and the rotor temperature:
a1, embedding a thermocouple in the central position of the wound rotor to enable the rotor to be in a static state, introducing current into a rotor winding, starting heating of the winding under the action of the current, and setting an initial detection temperature value according to insulation capability by the thermocouple because the thermocouple is in the static state and can measure a wire temperature value at the central position of the wound rotor;
a2, immediately disconnecting the current and the thermocouple detection end when the measured temperature of the central winding of the rotor reaches an initial detection temperature value, enabling the rotor to reach a rated rotation speed in a prime motor dragging mode, and testing a counter electromotive force waveform of the stator at the moment;
a3, after the test in the step A2 is finished, returning the rotor to a static state again, accessing a thermocouple detection end, enabling the thermocouple detection temperature value to be stable at a preset maintaining time of an initial detection temperature value in a preset mode, disconnecting again, and testing a stator counter electromotive force waveform at the moment in the preset mode;
a4, recovering the static state again after the step A3 is finished, accessing a thermocouple detection end, introducing preset current to continuously heat the rotor winding, immediately disconnecting the current and the thermocouple detection end when the temperature is detected to reach the temperature of the set interval by setting a temperature rise interval, repeating the step A2 process, repeating the step A3 process after the test is finished, and testing the counter electromotive force waveform of the stator in the steady-state temperature state;
a5, setting a cutoff temperature according to the insulation grade, testing the waveform of the counter electromotive force of the stator in a steady state of the cutoff temperature of the rotor center winding, and ending the experiment.
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| CN116231972B (en) | 2023-12-19 |
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