CN111697769B - Method and device for simulating dynamic turn-to-turn short circuit of excitation winding - Google Patents

Abstract

The invention discloses a method and a device for simulating a dynamic turn-to-turn short circuit of an excitation winding, wherein the device comprises the following steps: a short-circuit tap is connected to the generator excitation winding; a slip ring is arranged on a rotating shaft of the generator; the short-circuit tap is connected with the slip ring through the rotating shaft wire slot; the slip ring electrically connects the short-circuit tap with the short-circuit plate through the electric brush; the electric brushes are correspondingly connected with the binding posts on the short circuit board through the wires, so that the corresponding binding posts on the wiring board can be selected to realize different short circuit degrees, and the periodic short circuit mechanism can realize the periodic opening and closing of the circuit, thereby simulating the periodic breakdown of the turn-to-turn of the excitation winding, namely simulating the dynamic turn-to-turn short circuit of the excitation winding. The device for simulating the dynamic turn-to-turn short circuit of the excitation winding, provided by the invention, realizes the discovery and research of the fault characteristics of the fault by an experimental research method, and provides a diagnosis basis for timely troubleshooting of the fault.

Description

Method and device for simulating dynamic turn-to-turn short circuit of excitation winding

Technical Field

The invention relates to the technical field of generators, in particular to a method and a device for simulating a dynamic turn-to-turn short circuit of an excitation winding.

Background

The insulation capacity of the rotor winding is reduced due to insulation aging, damage and the like, and then the breakdown condition of the inter-turn insulation weak points of the winding can be periodically achieved due to unit vibration and the like, for example: the insulation weak point is opposite to and at a breakdown distance, and the turn-to-turn short circuit of the rotor winding is caused after the rotor winding is broken down.

Referring to fig. 1a, fig. 1a is an axial sectional view of a uniform winding of a rotor winding, and when the rotor winding is not uniformly wound, a certain distance h exists between winding turns, as shown in fig. 1 b. When the winding insulation layer has weak points due to aging, abrasion and the like, and a certain distance h still exists between winding turns, the breakdown condition is not reached, and at the moment, the rotor winding can still keep a normal working state, as shown in fig. 1 c. However, when the windings are periodically deformed due to vibration, as shown in fig. 1d, the upper winding is restrained from upward winding deformation due to the restriction of the tightness of the rotor slots and the windings, but the lower winding is reduced in the inter-turn gaps of the original windings due to the winding deformation, the minimum distance is h1, and when h1 is small to a certain extent, the voltage on the windings will break down the insulation weak points and the air between them, thereby generating an inter-turn short circuit of the excitation winding. And because of the periodicity of vibration, the width of an air gap between winding turns also changes periodically, so that the turn-to-turn of the excitation winding is subjected to periodic breakdown, and the periodic turn-to-turn short circuit fault state is the dynamic turn-to-turn short circuit of the excitation winding.

According to field observation experience, the dynamic turn-to-turn short circuit fault of the excitation winding does exist when the generator operates, but the research on the fault characteristics is very limited, so that the fault cannot be monitored on line in real time, and finally the fault cannot be eliminated in time to cause serious consequences, so that a large amount of economic loss is caused, and the safety of workers is damaged.

Therefore, how to provide a method and an apparatus for simulating a dynamic turn-to-turn short circuit of an excitation winding, so as to find and research the fault characteristics of the fault through an experimental research method is a problem that needs to be solved by those skilled in the art.

Disclosure of Invention

In view of this, the invention provides a method and a device for simulating a dynamic turn-to-turn short circuit of an excitation winding, which realizes the discovery and research of fault characteristics of the fault through an experimental research method and provides a diagnosis basis for timely troubleshooting of the fault.

In order to achieve the purpose, the invention adopts the following technical scheme:

an apparatus for simulating a dynamic turn-to-turn short of an excitation winding, comprising: the device comprises a generator, a slip ring, a periodic short-circuit mechanism, a short-circuit plate and a frequency regulator;

a short-circuit tap is connected to the generator excitation winding; a slip ring is arranged on a rotating shaft of the generator;

the short-circuit tap is connected with the slip ring through a rotating shaft wire slot; the slip ring electrically connects a short-circuit tap with the short-circuit plate through an electric brush;

the short-circuit plate is connected with the periodic short-circuit mechanism;

the frequency regulator is connected with the periodic short-circuit mechanism.

Preferably, the periodic shorting mechanism includes: the vibration exciter comprises a base, a support, a clamping device, a vibration exciter, a guillotine and a metal switch;

the bracket is arranged on the base;

the vibration exciter is arranged on the bracket through the clamping device; the bottom of the vibration exciter is provided with a hand hay cutter; the vibration exciter is connected with the frequency regulator;

the metal switches are arranged on the base and are positioned at two ends of the bottom of the guillotine; the metal switch is electrically connected with the shorting plate.

Preferably, the metal switch is connected with the short connection plate through a lead and a binding post in sequence.

Preferably, the clamping device comprises: the clamping rod and the clamping head; the clamping rod is connected with the clamping head in a spherical hinge mode.

Preferably, the number of the binding posts on the short-circuit board corresponds to the number of the short-circuit taps one to one.

Preferably, the brushes are mounted on the generator by means of mounting rods.

Preferably, the method further comprises the following steps: a direct current power supply; the direct current power supply is connected with the short connection plate.

A method for simulating a dynamic inter-turn short circuit of an excitation winding, which is applied to the above-mentioned apparatus for simulating a dynamic inter-turn short circuit of an excitation winding, the method comprising:

connecting a short-circuit tap to the generator excitation winding; a slip ring is arranged on a rotating shaft of the generator; the short-circuit tap is connected with the slip ring through a rotating shaft wire groove;

connecting an electric brush on the slip ring, and electrically connecting a short-circuit tap with the short-circuit plate through the electric brush;

connecting the shorting plate with the periodic shorting mechanism;

connecting the frequency regulator with the periodic short-circuit mechanism;

the excitation frequency of the vibration exciter is preset, and after the power supply is switched on, the device designed above realizes the simulation of dynamic turn-to-turn short circuit of different degrees.

According to the technical scheme, compared with the prior art, the invention discloses a method and a device for simulating the dynamic turn-to-turn short circuit of the excitation winding, wherein the excitation winding of the generator is connected with a short-circuit tap; a slip ring is arranged on a rotating shaft of the generator; the short-circuit tap is connected with the slip ring through the rotating shaft wire slot; the slip ring electrically connects the short-circuit tap with the short-circuit plate through the electric brush; the electric brushes are correspondingly connected with the binding posts on the short circuit board through the wires, so that the corresponding binding posts on the wiring board can be selected to realize different short circuit degrees, and the periodic short circuit mechanism can realize the periodic opening and closing of the circuit, thereby simulating the periodic breakdown of the turn-to-turn of the excitation winding, namely simulating the dynamic turn-to-turn short circuit of the excitation winding. The device for simulating the dynamic turn-to-turn short circuit of the excitation winding, provided by the invention, realizes the discovery and research of the fault characteristics of the fault by an experimental research method, and provides a diagnosis basis for timely troubleshooting of the fault.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the provided drawings without creative efforts.

FIG. 1a is an axial sectional view of a uniform winding of a rotor winding;

FIG. 1b is an axial cross-sectional view of a non-uniform winding of a rotor winding;

FIG. 1c is a sectional view of the winding mode at time t0 and the winding axis;

FIG. 1d is a sectional view of the winding mode at time t1 and the winding axis;

FIG. 2 is a schematic diagram of an excitation winding tap design provided by the present invention;

FIG. 3 is a schematic diagram of rotor slots, field windings and tap distribution thereof according to the present invention;

FIG. 4a is an axial view of a generator shaft raceway provided by the present invention;

FIG. 4b is a side view of a generator shaft raceway provided by the present invention;

FIG. 5 is an assembly view of a slip ring for a rotating shaft of a generator according to the present invention;

FIG. 6a is an axial cross-sectional view of a brush and slip ring assembly provided by the present invention;

FIG. 6b is a side view of a brush and slip ring assembly provided by the present invention;

FIG. 7 is a schematic diagram of a patch panel provided by the present invention;

FIG. 8 is a schematic view of a periodic shorting mechanism provided by the present invention;

FIG. 9 is a schematic view of a clamping device provided by the present invention;

fig. 10 is a device for simulating a dynamic turn-to-turn short circuit of an excitation winding provided by the invention.

The device comprises a generator 1, a generator 2, a slip ring 3, a periodic short-circuit mechanism 4, a short-circuit plate 5, a frequency regulator 6, a rotating shaft 7, a rotating shaft wire casing 8, an electric brush 9, a direct-current power supply 31, a base 32, a support 33, a clamping device 34, a vibration exciter 35, a guillotine 36, a metal switch 331, a clamping rod 332 and a clamping head.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Referring to fig. 10, an embodiment of the present invention discloses an apparatus for simulating a dynamic inter-turn short circuit of an excitation winding, including: the device comprises a generator 1, a slip ring 2, a periodic short-circuit mechanism 3, a short-circuit plate 4 and a frequency regulator 5;

a short-circuit tap is connected to an excitation winding of the generator 1; a rotating shaft 6 of the generator 1 is provided with a slip ring 2;

the short-circuit tap is connected with the slip ring 2 through the rotating shaft wire slot 7; the slip ring 2 electrically connects the short-circuit tap with the short-circuit plate 4 through the electric brush 8; the electric brushes 8 are correspondingly connected with the binding posts on the short circuit plates 4 through wires, so that the corresponding binding posts on the wiring board can be selected to realize different short circuit degrees.

The short connection plate 4 is connected with the periodic short connection mechanism 3;

the frequency regulator 5 is connected with the periodic short-circuit mechanism 3 and is used for regulating the excitation frequency of the periodic short-circuit mechanism 3 so as to adjust the dynamic turn-to-turn short-circuit period of the excitation winding.

The periodic short-circuit mechanism 3 can realize periodic opening and closing of a circuit, so that periodic breakdown between turns of the excitation winding is simulated, namely dynamic turn-to-turn short circuit of the excitation winding is simulated.

Referring to fig. 8 and 9, in order to further optimize the above technical solution, the periodic shorting mechanism 3 includes: the device comprises a base 31, a bracket 32, a clamping device 33, an exciter 34, a guillotine 35 and a metal switch 36;

the bracket 32 is mounted on the base 31;

the exciter 34 is mounted on the bracket 32 through a clamping device 33; the bottom of the vibration exciter 34 is provided with a hand hay cutter 35; the vibration exciter 34 is connected with the frequency regulator 5;

the metal switches 36 are arranged on the base 31 and are positioned at two ends of the bottom of the guillotine 35; the metal switch 36 is electrically connected to the shorting plate 4.

The vibration exciter 34 is fixed with a hand hay cutter 35 on the probe, the vibration exciting frequency is set through the frequency regulator 5, so that the electric hand hay cutter 36 moves up and down periodically, after the hand hay cutter 35 moves down to be in contact with the metal switch 35, the metal switch 36 is connected with the short circuit plate 4 through a wire and a wiring column, and when the hand hay cutter 35 moves up, the connection is broken, so that the metal switch 36 is opened and closed periodically.

In order to further optimize the above technical solution, the metal switch 36 is connected to the shorting plate 4 through a wire and a terminal in sequence.

In order to further optimize the above solution, the clamping device 33 comprises: a gripping bar 331 and a gripping head 332; the clamping rod 331 and the clamping head 332 are connected by means of a ball joint.

Referring to fig. 7, in order to further optimize the above technical solution, the number of the terminals on the shorting plate 4 corresponds to the number of the shorting taps one to one.

In order to further optimize the above solution, the brushes 8 are mounted on the generator 1 by means of mounting rods 81.

In order to further optimize the above technical solution, the method further comprises: a DC power supply 9; the dc power supply 9 is connected to the shorting plate 4.

In addition, the embodiment of the invention also discloses a method for simulating the dynamic turn-to-turn short circuit of the excitation winding, which is suitable for the device for simulating the dynamic turn-to-turn short circuit of the excitation winding, and the method comprises the following steps:

connecting an excitation winding of the generator 1 with an upper short-circuit tap; a slip ring 2 is arranged on a rotating shaft 6 of the generator 1; wherein, the short-circuit tap is connected with the slip ring 2 through the rotating shaft wire slot 7;

an electric brush 8 is connected to the slip ring 2, and the short-circuit tap is electrically connected with the short-circuit plate 4 through the electric brush 8;

connecting the short circuit plate 4 with the periodic short circuit mechanism 3;

connecting the frequency regulator 5 with the periodic short-circuit mechanism 3;

the excitation frequency of the vibration exciter is preset, and after the power supply is switched on, the device designed above realizes the simulation of dynamic turn-to-turn short circuit of different degrees.

The technical solution of the present invention is further described with reference to the following specific embodiments.

1. Excitation winding and short circuit joint design

The excitation winding is designed to be 480 turns of the excitation winding of a pair of pole generators, each pole has 240 turns, and the short-circuit tapping scheme is designed as follows: short-circuit taps are provided at 0%, 1%, 2%, 4% and 100% of one pole, corresponding to 5, 10 and 20 turns of turn-to-turn short circuit, respectively, as shown in fig. 2.

The rotor slot design and winding distribution are shown in fig. 3, the rotor is designed with 24 rotor slots, wherein the number of rotor real slots is 16 (slotting and winding), the number of virtual slots is 8 (reserving space and not slotting), according to the winding and the tap design scheme thereof, each slot has 60 turns, and then L0-L4 are all located in slot 1, and L4 is located in slot 8'. It should be noted here that theoretically, two arbitrary turns in a slot may be shorted, but the number of shorted turns is at most the total number of turns in one slot, so the maximum value of the short-circuit ratio is N/N, where N is the number of excitation turns in one slot, and N is the total number of excitation turns per pole, and in a specific experiment, the short-circuit ratio is adjusted according to specific situations.

The leading wires of each tap of the excitation winding are connected with the slip ring 2 through the rotating shaft wire grooves 7, wherein the rotating shaft wire grooves 7 are shown in figure 4, the slip ring 2 and the rotating shaft 6 are assembled as shown in figure 5, and the leading wires are connected with copper rings in the slip ring grooves through the rotating shaft wire grooves 7.

As shown in fig. 6b, the slip ring 2 is fitted with the copper brush 8, and the winding taps are connected to the terminal block 4 through the wiring holes of the copper brush 8. The wiring board 4 is designed as shown in fig. 7, the wiring board 4 is correspondingly connected with the copper brush 8 through a wire, corresponding terminals on the wiring board 4 can be selected during experiments to realize selection of different short circuit degrees, and a specific short circuit scheme is shown in table 1.

Table 1: different short circuit schemes and tap selection thereof

Tap selection	Degree of short circuit
		L0-L1	1％
L1-L2	1％
		L2-L3	2％
L0-L2	2％
		L1-L3	3％
L0-L3	4％

2. Periodic short-circuit mechanism

The core of the periodic short circuit mechanism is that the switch is periodically opened and closed, the periodic opening and closing of the short circuit is realized by adopting a method that a knife switch-like switch is matched with an exciter 34, as shown in fig. 8, the exciter 34 is fixed on a bracket 32 through a double-thread clamping device 33, wherein the clamping device 33 can be adjusted according to the type and the size of the exciter 34, a clamping head 332 in direct contact with the exciter 34 adopts a spherical hinge connecting mechanism, the clamping head can be flexibly disassembled and replaced, the matching between the clamping head and a clamping rod does not limit the degree of freedom of the clamping head in rotating around the axis of the clamping rod, the specific assembly details are shown in a partial enlarged view in fig. 9, and the overall assembly scheme of the clamping device 33 is shown in fig. 9. A chopper 35 is fixed on a probe of the vibration exciter 34, the vibration exciting probe can drive the chopper 35 to do vertical linear motion with a specified period after the vibration exciting frequency is set, when the chopper 35 moves downwards along with the vibration exciting probe and contacts with a metal switch 36 on the base 31, metal switches 36 at two ends are conducted, then circuits at two ends of the wiring terminal are conducted through a conducting wire between the metal switch 36 and the wiring terminal, when the chopper 35 moves upwards along with the vibration exciting probe, the chopper is separated from the metal switch 36 on the base, the metal switches 36 at two sides are disconnected, and the periodic opening and closing of the circuits at two ends of the wiring terminal under the specified frequency can be realized by the chopper 35 between one upper part and one lower part of the periodicity of the probe of the vibration exciter 34.

3. Excitation winding dynamic turn-to-turn short circuit simulation

By utilizing a designed excitation winding tap and a periodic short-circuit mechanism and matching with a correct wiring mode, as shown in fig. 10, L0 and L1 are respectively connected to two end terminals of a periodic short-circuit structure, and the frequency of a vibration exciter is set through a frequency regulator, so that the short-circuit between L0 and L1 can realize the switching state conversion of a specified period, at the moment, the generator is in a dynamic inter-turn short-circuit working state of the excitation winding under the specified period, and similarly, other short-circuit schemes in table 1 can be realized based on the device shown in fig. 10.

In summary, the device for simulating the dynamic turn-to-turn short circuit of the excitation winding provided by the invention can find and research the fault characteristics of the fault through an experimental research method, provide a diagnosis basis for timely troubleshooting the fault, greatly promote the research on the aspect of the dynamic turn-to-turn short circuit of the excitation winding, have the advantages of accurate and controllable period, sensitive response, simple and convenient structure and the like, and can greatly restore the situation that the generator has the dynamic turn-to-turn short circuit of the excitation winding in the real working condition.

The embodiments in the present description are described in a progressive manner, each embodiment focuses on differences from other embodiments, and the same and similar parts among the embodiments are referred to each other. The device disclosed by the embodiment corresponds to the method disclosed by the embodiment, so that the description is simple, and the relevant points can be referred to the method part for description.

The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims (7)

1. An apparatus for simulating a dynamic turn-to-turn short circuit of an excitation winding, comprising: the device comprises a generator (1), a slip ring (2), a periodic short-circuit mechanism (3), a short-circuit plate (4) and a frequency regulator (5);

a short-circuit tap is connected to an excitation winding of the generator (1); a rotating shaft (6) of the generator (1) is provided with a slip ring (2);

the short-circuit tap is connected with the slip ring (2) through a rotating shaft wire slot (7); the slip ring (2) electrically connects a short-circuit tap with the short-circuit plate (4) through an electric brush (8);

the short-circuit plate (4) is connected with the periodic short-circuit mechanism (3);

the frequency regulator (5) is connected with the periodic short-circuit mechanism (3);

the periodic shorting mechanism (3) comprises: the vibration exciter comprises a base (31), a bracket (32), a clamping device (33), a vibration exciter (34), a guillotine (35) and a metal switch (36);

the bracket (32) is mounted on the base (31);

the exciter (34) is mounted on the bracket (32) through the clamping device (33); a guillotine (35) is arranged at the bottom of the vibration exciter (34); the vibration exciter (34) is connected with the frequency regulator (5);

the metal switches (36) are arranged on the base (31) and are positioned at two ends of the bottom of the guillotine (35); the metal switch (36) is electrically connected with the shorting plate (4).

2. A device for simulating a dynamic turn-to-turn short circuit of an excitation winding according to claim 1, characterized in that the metal switch (36) is connected to the shorting plate (4) in turn by means of a wire and a terminal.

3. A device for simulating a dynamic turn-to-turn short circuit of an excitation winding according to claim 1, wherein the clamping means (33) comprises: a gripping lever (331) and a gripping head (332); the clamping rod (331) and the clamping head (332) are connected through a spherical hinge.

4. A device for simulating a dynamic turn-to-turn short circuit of an excitation winding according to claim 1, wherein the number of the terminals on the shorting plate (4) corresponds to the number of the shorting taps one by one.

5. A device for simulating a dynamic turn-to-turn short circuit of a field winding according to claim 1, characterized in that the brush (8) is mounted on the generator (1) by means of a mounting rod (81).

6. The apparatus of claim 1, further comprising: a DC power supply (9); the direct current power supply (9) is connected with the short connection plate (4).

7. A method for simulating a dynamic turn-to-turn short circuit of an excitation winding, which is suitable for the device for simulating the dynamic turn-to-turn short circuit of the excitation winding according to any one of claims 1 to 6, and the method comprises the following steps:

connecting an upper short-circuit tap on an excitation winding of the generator (1); a slip ring (2) is arranged on a rotating shaft (6) of the generator (1); the short-circuit tap is connected with the slip ring (2) through a rotating shaft wire slot (7);

an electric brush (8) is connected to the slip ring (2), and a short-circuit tap is electrically connected with the short-circuit plate (4) through the electric brush (8);

connecting the shorting plate (4) with the periodic shorting mechanism (3);

connecting the frequency regulator (5) with the periodic short-circuit mechanism (3);

the excitation frequency of the vibration exciter is preset, and after the power supply is switched on, the device designed above realizes the simulation of dynamic turn-to-turn short circuit of different degrees.

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