A power transformer temperature fault monitoring method and system

Abstract

The application discloses a kind of power transformer temperature fault monitoring method and system, comprising the following steps: using conical optical fiber to measure the temperature of oil inlet pipe and oil outlet pipe in transformer cooling system;Using speed sensor to measure the oil flow velocity on the oil inlet pipe and oil outlet pipe, obtain the flow velocity parameter for assisting the temperature as the basis for decision;Using GBDT diagnosis module, the data measured by the conical optical fiber and speed sensor are used as the input of GBDT diagnosis module, and the winding hot spot temperature of the transformer is used as the output of GBDT diagnosis module.The application realizes the accuracy and real-time monitoring function of transformer fault monitoring by using conical optical fiber to measure the temperature of oil inlet pipe and oil outlet pipe, speed sensor to measure the oil flow velocity inside oil inlet pipe and oil outlet pipe and GBDT diagnosis module.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of transformer fault diagnosis, and in particular to a power transformer temperature fault monitoring method and system. BACKGROUND

[0002] The power transformer is one of the important power equipment in the power system, and the safe and stable operation of the transformer is the condition for determining the reliability and safety of the power system. Among the main fault types of the transformer, the temperature is too high, which is one of the main reasons for the destruction of the insulation of the transformer. Therefore, by detecting the temperature of the transformer in real time, the early warning can be sent in time when the transformer fails, which is of great significance to maintain the stability of the power system.

[0003] At present, the commonly used temperature measurement methods in oil-immersed transformers include infrared temperature measurement method, optical fiber temperature measurement method and thermocouple method. The infrared temperature measurement method can accurately measure the temperature of the transformer and the surface of the oil tank by using an infrared light measuring instrument, but the infrared sensor cannot be installed inside the transformer, and is easily affected by shielding, environmental temperature and external factors, thereby bringing certain measurement error and having limitations; the thermocouple method measures by using a thermocouple sensor, but the thermocouple sensor contains metal shell, metal wire and other components, is easily affected by power frequency interference and will bring hidden danger to the insulation of the transformer;

[0004] The optical fiber temperature measurement method is suitable for measuring the internal temperature of the transformer, and the optical fiber temperature sensing unit does not contain metal components and will not be affected by the electromagnetic field inside the transformer, and will not bring hidden danger to the insulation of the transformer. However, the optical fiber sensor is generally arranged at the top of the oil tank of the transformer, and the diffusion of the transformer temperature is proportional to the oil flow rate. Since the internal volume of the transformer is large and the pressure is small, the oil flow rate in the oil tank is slow. When the transformer causes sudden increase of current due to sudden short circuit and other reasons, the heat emitted by the winding needs a long time to be transmitted to the position where the optical fiber sensor is arranged, and with the increase of the voltage grade of the transformer, the time lag will also increase, so that real-time monitoring of the fault is difficult to realize.

[0005] Therefore, a power transformer temperature fault monitoring method and system are provided to solve the above problems. SUMMARY

[0006] The power transformer temperature fault monitoring method and system provided by the present application can realize the accuracy and real-time monitoring function of the transformer fault monitoring by using the tapered optical fiber for temperature measurement, the speed sensor for speed measurement and the GBDT diagnosis module, and solve the problems in the above background.

[0007] To achieve the above purpose, the present application provides the following technical scheme:

[0008] The power transformer temperature fault monitoring method comprises the following steps: measuring the temperature of the oil inlet pipeline and the oil outlet pipeline in the transformer cooling system by using a tapered optical fiber;

[0009] Measuring the oil flow velocity on the oil inlet pipeline and the oil outlet pipeline by using a velocity sensor to obtain a flow velocity parameter used for assisting the temperature as a decision basis;

[0010] Using a GBDT diagnosis module, taking the data measured by the tapered optical fiber and the velocity sensor as the input of the GBDT diagnosis module, and taking the winding hot spot temperature of the transformer as the output of the GBDT diagnosis module.

[0011] Preferably, the surface of the tapered optical fiber is coated with a layer of graphene, and when the cooling system is subjected to temperature changes, the incident light can produce a phase difference at the tapered optical fiber through the change of the refractive index of the graphene itself.

[0012] Preferably, the arrangement of the tapered optical fiber comprises the following steps: two small holes are opened at the connection between the oil tank and the cooling system of the transformer, the two small holes are symmetrical with respect to the connection, and the two small holes are respectively the inlet end and the outlet end of the tapered optical fiber; the tapered optical fiber is fixedly installed on the small holes by flanges, and the flanges and the small holes are sealed by using epoxy resin; the tapered optical fiber is spirally wound on the surface of the oil tank, and the tapered optical fiber is introduced into the oil inlet pipeline and the oil outlet pipeline respectively; the tapered optical fibers are kept apart from each other during winding.

[0013] Preferably, the adjacent intervals of the tapered optical fiber are provided with tapered zones as temperature measuring points, and an optical circulator is arranged between the adjacent two tapered zones for leading out the temperature measuring point signal and adjusting it, the temperature data of the temperature measuring point signal is obtained after the adjustment of the optical circulator, and the temperature data is expressed as an output representation of a temperature vector expression, and the temperature vector expression is:

[0014] {X 11 , X 12 ,... X 1n , X 21 ,... X 2n};

[0015] In the temperature vector expression, X represents a sample, X 1n represents the temperature measured by the n-th measuring point of the tapered optical fiber at the oil inlet pipeline, and X 2n represents the temperature measured by the n-th measuring point of the tapered optical fiber at the oil outlet pipeline.

[0016] Preferably, the arrangement of the speed sensor comprises the following steps: the speed sensor is respectively installed inside the oil inlet pipeline and the oil outlet pipeline; the speed sensor is fixed and pasted on the oil inlet pipeline and the oil outlet pipeline by epoxy resin respectively.

[0017] Preferably, the oil flow rate measured by the speed sensor in the oil inlet pipeline is output and represented by an oil inlet vector expression, the oil inlet vector expression being:

[0018] {X 31 , X 32 , X 33 , X 34};

[0019] The oil flow rate measured by the speed sensor in the oil outlet pipeline is output and represented by an oil outlet vector expression, the oil outlet vector expression being:

[0020] {X 41 , X 42 , X 43 , X 44}.

[0021] Preferably, the sample X is classified and a training regression tree is constructed, the data measured by the tapered optical fiber and the speed sensor are taken as the input of the GBDT diagnosis module, and an input vector expression is established, the input vector expression being:

[0022] {X 11 , X 12 ,..., X 1n , X 21 ,..., X 2n , X 31 , X 32 , X 33 , X 34 , X 41 , X 42 , X 43 , X 44}.

[0023] The power transformer temperature fault monitoring system comprises a temperature measurement unit, which adopts a tapered optical fiber to measure the temperature of an oil inlet pipeline and an oil outlet pipeline in a transformer cooling system;

[0024] A speed monitoring unit adopts a speed sensor to measure the oil flow rate on the oil inlet pipeline and the oil outlet pipeline, so as to obtain a flow rate parameter used for assisting the temperature as a decision basis;

[0025] The GBDT diagnosis unit adopts a GBDT diagnosis module, takes the data measured by the tapered optical fiber and the speed sensor as the input of the GBDT diagnosis module, and takes the winding hot spot temperature of the transformer as the output of the GBDT diagnosis module.

[0026] The present application has the following beneficial effects:

[0027] 1. The power transformer temperature fault monitoring method and system, by using the tapered optical fiber to measure the temperature of the oil inlet pipeline and the oil outlet pipeline in the cooling system, obtains the temperature data in the oil inlet pipeline and the oil outlet pipeline; the speed sensor is used to measure the oil flow velocity in the oil inlet pipeline and the oil outlet pipeline, and the data measured by the tapered optical fiber and the speed sensor is taken as the input of the GBDT diagnosis module, an input vector expression is established, and the winding hot spot temperature of the transformer is taken as the output of the GBDT diagnosis module; the winding hot spot temperature is indirectly calculated by measuring the internal temperature and the oil flow velocity of the oil inlet pipeline and the oil outlet pipeline, and since the oil inlet pipeline and the oil outlet pipeline are narrow, the oil pressure at the internal position is high, and the flow velocity is fast, therefore, the temperature of the winding can be diffused faster, and the problem of poor real-time performance in measuring the top layer oil temperature in the prior art is solved.

[0028] 2. The power transformer temperature fault monitoring method and system, since the tapered optical fiber is arranged in a winding shape on the surface of the oil tank, the temperature change inside and near the oil inlet pipeline and the oil outlet pipeline can be measured, the monitoring speed and accuracy are improved, and the surface of the tapered optical fiber is coated with graphene, which is beneficial to preventing electromagnetic interference of the transformer and improving the stability of the tapered optical fiber. BRIEF DESCRIPTION OF DRAWINGS

[0029] Figure 1 It is a schematic diagram of the power transformer temperature fault monitoring method;

[0030] Figure 2 It is a schematic diagram of the power transformer temperature fault monitoring system;

[0031] Figure 3 It is a schematic diagram of the tapered optical fiber arrangement scheme;

[0032] Figure 4 It is a cross-sectional view of the tapered optical fiber arrangement in the oil inlet pipeline and the oil outlet pipeline;

[0033] Figure 5 It is a schematic diagram of the speed sensor arrangement scheme.

[0034] MAIN REFERENCE NUMERALS:

[0035] 1, small hole; 2, tapered optical fiber; 3, oil inlet pipe and oil outlet pipe; 4, speed sensor; 11, temperature measurement unit; 12, speed monitoring unit; 13, GBDT diagnosis unit. DETAILED DESCRIPTION

[0036] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are some of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the scope of protection of the present application.

[0037] The present application provides a power transformer temperature fault monitoring method, which combines Figures 1 to 5 to illustrate, comprising the following steps:

[0038] S11, the temperature of the oil inlet pipe and the oil outlet pipe in the transformer cooling system is measured by using a tapered optical fiber;

[0039] S12, the oil flow velocity on the oil inlet pipe and the oil outlet pipe is measured by using a speed sensor to obtain a flow velocity parameter used for assisting temperature as a decision basis;

[0040] S13, the data measured by the tapered optical fiber and the speed sensor are taken as the input of the GBDT diagnosis module, and the winding hot spot temperature of the transformer is taken as the output of the GBDT diagnosis module.

[0041] The arrangement of the tapered optical fiber comprises the following steps: two small holes are opened at the connection between the oil tank and the cooling system of the transformer, the two small holes are symmetrical with respect to the connection, and the two small holes are respectively the inlet end and the outlet end of the tapered optical fiber; the tapered optical fiber is fixedly installed on the small holes through flanges, and the flanges and the small holes are sealed by using epoxy resin; the tapered optical fiber is spirally wound on the surface of the oil tank, and the tapered optical fiber is introduced into the oil inlet pipe and the oil outlet pipe respectively; the tapered optical fibers are kept apart from each other during winding. The adjacent intervals of the tapered optical fibers are provided with tapered zones as temperature measurement points, and a circulator for leading out the temperature measurement point signal and adjusting is arranged between the adjacent two tapered zones. The temperature data of the temperature measurement point signal is obtained after the adjustment of the circulator, and the temperature data is expressed as a temperature vector expression as output, and the temperature vector expression is:

[0042] {X 11 , X 12 ,... X 1n , X 21 ,... X 2n};

[0043] In the temperature vector expression, X represents a sample, X1n represents the temperature measured by the n-th measuring point of the tapered optical fiber at the inlet oil pipeline, X 2n represents the temperature measured by the n-th measuring point of the tapered optical fiber at the outlet oil pipeline

[0044] The graphene coating layer is 0.37 nm thick. Within the temperature variation range of the transformer oil, the conductivity of the graphene will increase with the increase of the temperature, and the relationship conforms to the Kubo formula. The dielectric constant of the graphene is related to the conductivity, and according to the Kubo formula, the dielectric constant of the graphene will decrease when the temperature increases, thereby causing the decrease of the refractive index. Therefore, when the temperature of the cooling system changes, the phase difference of the incident light at the tapered optical fiber will change with the change of the refractive index of the graphene. The distributed tapered optical fiber arrangement method is as follows: two small holes are arranged at the connection between the oil tank of the transformer and the cooling system, the two small holes are 10 cm away from the connection center and are symmetric about the center, the diameters of the two small holes are 0.5 cm, the two small holes are the inlet end and the outlet end of the tapered optical fiber respectively, the tapered optical fiber is fixedly installed on the small holes through flanges, and the flanges and the small holes are sealed by using epoxy resin, including the sealing of the gap at the connection. In order to simultaneously measure the temperature distribution of the surface of the oil tank and the inside of the inlet oil pipeline and the outlet oil pipeline, the tapered optical fiber is spirally wound on the surface of the oil tank, and the tapered optical fiber is introduced into the inside of the inlet oil pipeline and the outlet oil pipeline respectively, and the interval between adjacent tapered optical fibers is 2 cm. A tapered zone is arranged every 20 cm of the tapered optical fiber as a temperature measuring point, and a circulator is arranged between adjacent two tapered zones for leading out the signal of the temperature measuring point and demodulating.

[0045] When the transformer abnormally increases in temperature, the flow rate of the oil flow in the inlet oil pipeline and the outlet oil pipeline will increase, so the flow rate parameter is taken as an auxiliary decision basis for the temperature parameter. The speed sensors are installed at a depth of 10 cm in the inlet oil pipeline and the outlet oil pipeline, and 4 speed sensors are arranged in each of the inlet oil pipeline and the outlet oil pipeline, and the speed sensors are firmly pasted by using epoxy resin glue. The oil flow flow rate measured by the speed sensor in the inlet oil pipeline is output and represented by an inlet oil vector expression, and the inlet oil vector expression is: {X 31 , X 32 , X 33 , X 34}, the oil flow flow rate measured by the speed sensor in the outlet oil pipeline is output and represented by an outlet oil vector expression, and the outlet oil vector expression is: {X 41 , X 42 , X 43 , X 44}.

[0046] The GBDT diagnosis module is a classification module with the GBDT iterative decision tree algorithm as the core, and before diagnosis, the GBDT algorithm needs to be trained first: a training regression tree is constructed for the two classes of 'fault' and 'normal' that the sample X may belong to, the data measured by the tapered optical fiber and the speed sensor are taken as the input of the GBDT diagnosis module, and an input vector expression is established, and the input vector expression is:

[0047] {X 11 , X 12 ,..., X 1n , X 21 ,..., X 2n , X 31 , X 32 , X 33 , X 34 , X 41 , X 42 , X 43 , X 44};

[0048] The winding hotspot temperature of the transformer is indirectly calculated by measuring the temperature and oil flow velocity on the oil inlet pipeline and the oil outlet pipeline in the cooling system, since the oil inlet pipeline and the oil outlet pipeline are narrow, the oil pressure inside the pipeline is high, and the flow velocity is fast, so the temperature of the winding can be diffused faster, and the problem of poor real-time performance in the prior art when measuring the top layer oil temperature is solved. By taking temperature and flow velocity as the input of the GBDT model, the diagnostic accuracy of the model can be further improved.

[0049] The power transformer temperature fault monitoring system provided by the application comprises a temperature measuring unit 11, a speed monitoring unit 12 and a GBDT diagnosis unit 13. Figure 2 The temperature measuring unit 11 measures the temperature of the oil inlet pipeline and the oil outlet pipeline in the transformer cooling system by using a tapered optical fiber.

[0050] The speed monitoring unit 12 measures the oil flow velocity on the oil inlet pipeline and the oil outlet pipeline by using a speed sensor, and obtains the flow velocity parameter used for assisting temperature as a decision basis.

[0051] The GBDT diagnosis unit 13 adopts a GBDT diagnosis module, takes the data measured by the tapered optical fiber and the speed sensor as the input of the GBDT diagnosis module, and takes the winding hotspot temperature of the transformer as the output of the GBDT diagnosis module.

[0052] The above embodiments are only used to illustrate the technical solutions of the present application, and are not intended to limit the present application; although the present application has been described in detail with reference to the above embodiments, those skilled in the art should understand that the technical solutions recorded in the above embodiments can still be modified, or some or all of the technical features can be replaced by equivalents; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application, and they should be covered in the scope of the claims and the description of the present application.

Claims

1. A method for monitoring temperature faults of power transformers, characterized in that: The following steps are involved: Use tapered optical fiber to measure the temperature of the oil inlet and outlet pipes in the transformer cooling system; Using a velocity sensor to measure the oil flow velocity on the oil inlet pipe and the oil outlet pipe to obtain a flow velocity parameter to assist the temperature in making a decision; A GBDT diagnostic module is used, the data measured by the tapered optical fiber and the speed sensor are used as inputs of the GBDT diagnostic module, and the hot spot temperature of the transformer winding is used as output of the GBDT diagnostic module.

2. A method for monitoring temperature faults of a power transformer according to claim 1, characterized in that: The surface of the tapered optical fiber is coated with a layer of graphene. When the cooling system is subjected to temperature changes, the refractive index of the graphene itself changes, so that the incident light can generate a phase difference at the tapered optical fiber.

3. A method for monitoring temperature faults of a power transformer according to claim 1, characterized in that: The arrangement of the tapered optical fiber includes the following steps: opening two small holes at the connection between the oil tank and the cooling system of the transformer, the two small holes being symmetrical with each other about the connection, and the two small holes being the inlet end and the outlet end of the tapered optical fiber, respectively; the tapered optical fiber is fixedly mounted on the small holes through flanges, and the flanges and the small holes are sealed with epoxy resin; the tapered optical fiber is spirally wound on the surface of the oil tank, and the tapered optical fiber is respectively introduced into the interior of the oil inlet pipe and the oil outlet pipe; the tapered optical fibers are kept spaced apart when being wound.

4. A method for monitoring temperature faults of a power transformer according to claim 3, characterized in that: Conical areas serving as temperature measurement points are provided at adjacent intervals of the tapered optical fiber. A circulator for extracting and mediating the temperature measurement point signal is provided between two adjacent tapered areas. The circulator obtains temperature data of the temperature measurement point signal after mediation. The temperature data is represented as an output using a temperature vector expression. The temperature vector expression is: ； In the temperature vector expression, Representative samples, represents the temperature measured at the nth measuring point of the tapered optical fiber at the oil inlet pipeline, Represents the temperature measured at the nth measuring point of the tapered optical fiber at the oil outlet pipeline.

5. The method for monitoring temperature fault of a power transformer according to claim 1, characterized in that: The arrangement of the speed sensor includes the following steps: the speed sensor is respectively installed inside the oil inlet pipeline and the oil outlet pipeline; the speed sensor is fixedly adhered to the oil inlet pipeline and the oil outlet pipeline by epoxy resin.

6. A method for monitoring temperature faults of a power transformer according to claim 5, characterized in that: The oil flow velocity measured by the speed sensor in the oil inlet pipe is outputted and represented by an oil inlet vector expression. The oil inlet vector expression is: ； The oil flow velocity measured by the velocity sensor in the oil outlet pipeline is outputted by an oil outlet vector expression, which is: 。 7. A method for monitoring temperature faults of a power transformer according to claim 4, characterized in that: The sample X is classified and a training regression tree is constructed. The data measured by the tapered optical fiber and the speed sensor are used as the input of the GBDT diagnostic module, and an input vector expression is established. The input vector expression is: 。 8. A power transformer temperature fault monitoring system, characterized in that: include: The temperature measurement unit uses a tapered optical fiber to measure the temperature of the oil inlet and outlet pipes in the transformer cooling system; a speed monitoring unit, which uses a speed sensor to measure the oil flow velocity on the oil inlet and outlet pipes to obtain a flow velocity parameter used to assist the temperature in making a decision; The GBDT diagnostic unit adopts a GBDT diagnostic module, uses the data measured by the tapered optical fiber and the speed sensor as the input of the GBDT diagnostic module, and uses the hot spot temperature of the transformer winding as the output of the GBDT diagnostic module.

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