Monitoramento de descarga parcial da temperatura do transformador e nível de líquido, guia completo, solução-INNO

Monitoramento da temperatura do óleo do transformador
The Importance of Transformer Oil Temperature Monitoring
Transformer oil temperature is one of the key indicators reflecting the operating status of transformers. Durante a operação de transformadores, internal electromagnetic losses and winding resistance losses are converted into heat, which can cause the oil temperature to rise. Excessive oil temperature may accelerate the aging of transformer oil, reduce its insulation performance, thereby affecting the normal operation of the transformer and even causing faults. Por exemplo, when the oil temperature exceeds the specified limit for a long time, the insulation components in the transformer oil will decompose, produzindo alguns gases que podem causar um aumento na pressão interna e representar um risco à segurança. De acordo com os padrões relevantes, para transformadores imersos em óleo com isolamento Classe A, a temperatura máxima permitida é 105 ℃, e o aumento de temperatura permitido é 65 ℃ quando a temperatura ambiente é 40 ℃.

Método de monitoramento da temperatura do óleo
Medição de temperatura: O método tradicional consiste em medir diretamente a temperatura do óleo do transformador usando um termômetro de mercúrio ou um termômetro de pressão.. Este método é simples e direto, mas requer leitura periódica manual de dados e não pode obter monitoramento contínuo em tempo real.
Medição de temperatura de fibra óptica: A tecnologia de medição de temperatura por fibra óptica é um método relativamente avançado. Utiliza as características sensíveis à temperatura das fibras ópticas para colocá-las em posições adequadas dentro dos transformadores, and obtains oil temperature information by detecting changes in the optical signal in the fibers. This method has the advantages of high accuracy, forte capacidade anti-interferência, and the ability to achieve distributed measurement, which can accurately monitor the distribution of transformer oil temperature in real time.
Fault diagnosis based on oil temperature monitoring
By monitoring the oil temperature of the transformer, preliminary diagnosis of some faults can be made. Por exemplo, if an abnormal increase in oil temperature is found, it may be due to the overload operation of the transformer, which increases internal losses and generates excessive heat; It is also possible that there is a malfunction in the cooling system, such as a clogged radiator or a faulty cooling fan, which prevents heat from dissipating in a timely manner; It may also be due to local overheating faults inside the transformer, such as winding short circuits. When the oil temperature change rate is abnormal, it may also indicate potential faults in the transformer, such as the appearance of new heat sources in the oil or changes in the heat dissipation channels.

Transformer oil level monitoring
The significance of oil level monitoring
The oil level of a transformer is an important indicator for determining the internal insulation status of the transformer. Transformer oil plays an important role in insulation, dissipação de calor, and arc extinguishing in transformers. Excessive or insufficient oil level may lead to a decrease in the quality of the insulation medium, thereby affecting the normal operation of the transformer. Se o nível do óleo estiver muito alto, it may increase the internal pressure of the transformer, which can easily cause oil leakage and even lead to serious consequences such as oil tank rupture; Se o nível do óleo estiver muito baixo, the heat dissipation effect of the transformer will be affected, and some windings may not receive sufficient insulation protection, increasing the risk of faults such as short circuits.

Method of oil level monitoring
Oil level monitoring: Common types include glass tube oil level gauges and pointer type oil level gauges. The glass tube oil level gauge can directly observe the level of oil, but its accuracy is relatively low; The pointer type oil level gauge converts the change in oil level into the rotation of the pointer through a mechanical structure, making it easy to read the oil level value. When reading the oil level gauge, it is necessary to pay attention to sufficient ambient light, stand in front of the oil level gauge, and accurately observe the scale line and oil level indication.
Sensor monitoring: Automatic monitoring of oil level can be achieved through the use of oil level sensors. Sensors convert changes in oil level into electrical signals, which can be transmitted and processed through a signal transmission and processing system to obtain real-time oil level information and set alarm values. When the oil level exceeds the normal range, an alarm can be issued in a timely manner.
Handling of abnormal oil level
When abnormal oil level is detected, it needs to be dealt with in a timely manner. Se o nível do óleo estiver muito alto, it is necessary to check whether there are other faults causing oil volume expansion, such as high oil temperature or whether there is excessive oil replenishment. If necessary, oil can be drained appropriately to lower the oil level; Se o nível do óleo estiver muito baixo, the first thing to check is whether there is oil leakage. If there is a leakage point, it needs to be repaired in a timely manner, and then an appropriate amount of transformer oil should be added to the normal oil level.

Monitoramento da temperatura do enrolamento do transformador
The Influence of Winding Temperature on Transformers
The temperature of transformer windings is one of the key factors affecting the internal insulation of transformers. A temperatura do enrolamento limita diretamente o tamanho da carga do transformador. Quando o transformador está funcionando, a corrente que passa pelo enrolamento gerará calor, fazendo com que a temperatura do enrolamento suba. A temperatura excessiva do enrolamento acelerará o envelhecimento dos materiais de isolamento e reduzirá a vida útil dos transformadores. Por exemplo, quando a temperatura do enrolamento excede o valor permitido por um longo período, o material de isolamento perderá gradualmente seu desempenho de isolamento, o que pode levar a falhas de curto-circuito entre os enrolamentos e afetar seriamente a operação normal do transformador.

Métodos para monitorar a temperatura do enrolamento
Medição de temperatura: Semelhante à medição da temperatura do óleo, um termômetro pode ser usado para medir a temperatura do enrolamento. No entanto, due to the fact that the winding is located inside the transformer, direct measurement is difficult. Portanto, indirect measurement methods are usually used, such as measuring oil temperature and estimating the winding temperature based on empirical formulas or specific temperature relationship curves.

Sistema de medição de temperatura de fibra óptica fluorescente: This is a more advanced and accurate method. Fiber optic cables can directly enter the interior of transformer windings and obtain temperature information at various points of the winding by detecting the state of backscattered light in the fiber optic cables. This method can directly measure the hot spot temperature of the winding in real time, with a temperature measurement accuracy of up to 1 grau, and is very suitable for online measurement of large transformer windings.

Winding temperature monitoring and transformer life evaluation
By long-term monitoring of winding temperature, the lifespan of transformers can be evaluated. According to relevant research, the lifespan of transformers is closely related to winding temperature, and for every 6 degrees increase in temperature, the relative aging rate may double. Por exemplo, for a transformer designed according to GB1094, the relative thermal aging rate is 1 at a hot spot temperature of 98 ℃, which corresponds to “operating at an ambient temperature of 20 ℃ and a hot spot temperature rise of 78K”. By monitoring the winding temperature, the load of the transformer can be reasonably controlled to avoid prolonged operation at high temperatures, thereby extending the service life of the transformer.

Transformer core temperature monitoring
The role of iron core in transformer and its temperature influence
The iron core of a transformer is an important link in the conversion of electricity, magnetism, and electricity, and is one of the most important components of a transformer. Durante a operação de transformadores, heat is generated due to hysteresis and eddy current losses in the iron core, causing the temperature of the iron core to rise. Excessive temperature of the iron core can cause a series of problems, such as a decrease in insulation performance between the iron core laminations, which can easily lead to iron core short circuit faults. If the iron core or clamp is grounded at two or more points, it will form a closed circuit, generate circulating current, further cause local overheating, and even burn out the iron core, damage the winding insulation, and cause damage to the transformer.

Iron core temperature monitoring method
Medição direta: Instalar sensores de temperatura de fibra óptica on the surface of the iron core to directly measure the temperature of the iron core. This method can accurately obtain temperature information of the iron core, but it needs to be installed during transformer manufacturing or maintenance, and the installation position of the sensor needs to be reasonably selected to ensure that it can reflect the true temperature situation of the iron core.

The hazards and prevention of abnormal iron core temperature
An abnormal increase in iron core temperature may cause various malfunctions. In addition to the insulation performance degradation and short-circuit faults mentioned above, it may also lead to a decrease in transformer efficiency and an increase in operating costs. In order to prevent abnormal temperature of the iron core, in addition to temperature monitoring, in the design and manufacturing process of transformers, it is necessary to ensure good stacking technology of the iron core, reduce vibration friction, and prevent conductive impurities from entering the interior of the iron core; Durante a operação, regular maintenance checks should be conducted to promptly identify and address factors that may cause an increase in iron core temperature, such as poor grounding of the iron core.

Transformer insulation resistance monitoring
The relationship between insulation resistance and transformer insulation performance
Insulation resistance is one of the important indicators for measuring the insulation performance of transformers. The insulation system of transformers is mainly used to isolate components of different voltage levels, prevent current leakage and short circuit faults. The magnitude of insulation resistance reflects the ability of insulation materials to obstruct current. If the insulation resistance is too low, it indicates that the insulation material may be affected by moisture, envelhecimento, dano, etc., which will increase the risk of leakage and reduce the safety and reliability of the transformer. Por exemplo, in humid environments or after prolonged operation, the insulation resistance of transformers may decrease, afetando seu funcionamento normal.

Measurement method for insulation resistance
Power outage measurement: This is the most commonly used measurement method. Before measurement, the transformer must be powered off, and there must be obvious disconnection points for each coil outlet. The surrounding area of the transformer must be clean, without grounding objects or operators. When measuring, use a shaking table that meets the voltage level requirements. For transformers with neutral grounding, the neutral point knife switch should be opened before measurement and restored to its original position after measurement. Both before and after measurement, discharge to ground is required. Por exemplo, a 1000-2500V megohmmeter can be used to measure the insulation resistance of distribution transformers. The measurement results and the oil temperature at the time of measurement should be recorded in the transformer file for comparative analysis.
Tecnologia de monitoramento on-line: Com o desenvolvimento da tecnologia, também surgiram algumas tecnologias de monitoramento on-line para resistência de isolamento. Estas tecnologias podem detectar a tendência decrescente do desempenho do isolamento em tempo hábil, monitorando as mudanças na resistência do isolamento em tempo real durante a operação dos transformadores.. No entanto, a tecnologia de monitoramento online é relativamente complexa e cara, mas para alguns transformadores importantes, o monitoramento on-line pode fornecer avisos de falhas mais oportunos.
Análise e aplicação de resultados de medição de resistência de isolamento
O valor medido da resistência de isolamento precisa ser analisado. De um modo geral, a resistência de isolamento deve ser comparada com os resultados de testes anteriores. Se houver uma mudança significativa em comparação com os resultados anteriores, como uma queda repentina para 50% ou inferior ao valor inicial, inspeção ou manutenção adicional do transformador pode ser necessária. Enquanto isso, a resistência de isolamento de transformadores de diferentes níveis e tipos de tensão também possui uma certa faixa de referência, que pode ser julgado de acordo com padrões relevantes. Por exemplo, a resistência de isolamento dos transformadores de potência imersos em óleo tem uma faixa permitida correspondente. Comparando o valor medido com o valor permitido, a condição de isolamento do transformador pode ser avaliada.

Monitoramento de descarga parcial de transformadores
O conceito e os perigos da descarga parcial
Descarga parcial refere-se ao fenômeno de descarga que ocorre em uma área localizada do sistema de isolamento de um transformador. Quando há lacunas de ar, impurezas, ou isolamento irregular dentro do isolamento de um transformador, discharge may occur in these local areas under the action of an electric field. Partial discharge is not only a precursor to equipment insulation aging, but also an important cause of insulation aging and ultimately insulation breakdown. During partial discharge, phenomena such as electrical pulses, electromagnetic radiation, and ultrasonic waves may cause local overheating and the generation of characteristic oil and gas in transformers, leading to gradual damage to insulation materials and reduced insulation performance. Em última análise, this may cause short-circuit faults in transformers, affecting their normal operation and service life.

Methods for partial discharge monitoring
Ultrasonic testing method: When partial discharge occurs inside the transformer, ultrasonic signals will be generated. By installing ultrasonic sensors outside the transformer, these signals can be detected. This method has the advantages of non invasiveness and insensitivity to environmental interference, but its sensitivity to detecting some weak partial discharge signals may be relatively low.
Pulse current method: Partial discharge generates high-frequency pulse current. By using radio frequency current sensors to detect these pulse currents, partial discharge monitoring can be achieved. This method can directly measure the current signal generated by partial discharge, com alta sensibilidade, but is easily affected by external electromagnetic interference.
Ultra high frequency (UHF) detection method: Partial discharge occurring in transformer oil and oil/insulation paper has a wide frequency spectrum, que pode excitar sinais de ondas eletromagnéticas de frequência ultra-alta de centenas ou até milhares de megahertz. O sinal é obtido através de sensores instalados na abertura da janela da caixa do transformador para obter detecção de descarga parcial. O método de frequência ultra-alta tem forte capacidade anti-interferência, pode localizar fontes de descarga locais, identificar diferentes defeitos de isolamento, tem alta sensibilidade, e pode realizar monitoramento on-line de longo prazo de descargas parciais em transformadores e GIS. Atualmente é um método relativamente maduro para medir descargas parciais.
A importância do monitoramento de descargas parciais
Monitorando descargas parciais de transformadores, potenciais problemas no sistema de isolamento dos transformadores podem ser detectados em tempo hábil. Durante a operação de transformadores, se a descarga parcial for detectada precocemente, medidas correspondentes podem ser tomadas, como ajustar parâmetros operacionais, reparar ou substituir componentes de isolamento, para evitar o desenvolvimento de descargas parciais e falhas graves, como quebra de isolamento. Ao mesmo tempo, analisar os dados de monitoramento de descarga parcial também pode fornecer insights sobre o estado de saúde do isolamento do transformador, e fornecer uma base para a manutenção e gerenciamento de transformadores.