Name: differential relay protection in power systems
Uploaded: 2024-11-21T14:54:35.000Z
Duration: 1 min 20 s
Channel: JoVE

Los relés diferenciales protegen generadores, buses y transformadores.
En un generador sin fallas, transformadores de corriente idénticos mantienen el relé inactivo, ya que no fluye corriente a través de la bobina de funcionamiento del relé.
Una falla interna, como un cortocircuito de fase a tierra o de fase a fase, interrumpe este equilibrio, causando corriente diferencial y potencialmente activando el relé.
Los relés diferenciales electromecánicos, al igual que los relés de barra de equilibrio, funcionan cuando la fuerza de un lado supera la del otro. Dado que no hay dos transformadores de corriente idénticos, pueden ocurrir corrientes diferenciales significativas durante fallas externas, incluso con corrientes iguales.
Para la protección del bus, cada fase utiliza un relé diferencial. Si se activa uno, se abren todos los interruptores trifásicos conectados al bus.
Si no existe una falla interna entre los transformadores de corriente, la corriente del relé diferencial permanece cero. Sin embargo, una falla de bus genera una corriente diferencial distinta de cero, activando el relé.
Los transformadores de más de 10 MVA utilizan relés diferenciales para protección.
Existen adaptaciones especializadas para transformadores de devanado múltiple y transformadores reguladores de voltaje.

relés diferenciales

Differential Relays

Los relés diferenciales se utilizan para proteger generadores, buses y transformadores comparando magnitudes eléctricas en diferentes puntos. Cuando ocurre una falla, la diferencia de corriente entre los dos puntos hace que el relé funcione, abriendo el disyuntor. En condiciones normales, la corriente que entra (i_1) y sale (i_2) de un generador es igual. Sin embargo, cuando ocurre una falla, estas corrientes se vuelven desiguales y la corriente diferencial fluye en la bobina de operación del relé, lo que hace que el relé se dispare. Un relé diferencial electromecánico, conocido como relé de viga de equilibrio, funciona en función de la comparación de fuerzas electromagnéticas generadas por la corriente diferencial. El relé se dispara cuando la fuerza en la bobina de operación excede la fuerza de restricción. La condición para el funcionamiento del relé viene dada por:
<img alt="Equation1" src="/files/ftp_upload/16167/16167_PT_Equation1.svg" style="height: 30px;">
La protección del bus se logra mediante el uso de relés diferenciales para detectar fallas dentro de la zona del bus. El relé funciona cuando la suma de las corrientes que entran y salen del bus no es cero, lo que indica una falla.
La protección diferencial de los transformadores es más compleja debido a la presencia de diferentes devanados y relaciones de espiras. Cuando el transformador opera en condiciones normales sin falla interna, las corrientes primaria y secundaria, ajustadas por sus respectivas relaciones de transformador de corriente (TC), deberían estar equilibradas. Pero en el caso de una falla interna, la corriente diferencial fluye a través de la bobina de operación del relé, provocando su disparo.
En el caso de los transformadores trifásicos, los TC deben estar conectados correctamente para tener en cuenta los cambios de fase provocados por los devanados del transformador. Esto garantiza que las corrientes secundarias estén en fase, lo que evita el funcionamiento incorrecto del relé. En el caso de los transformadores Y-Δ, los TC del lado Y deben estar conectados en Δ y los TC del lado Δ deben estar conectados en Y.
Los métodos de protección diferencial se han adaptado para diversas configuraciones de transformadores, incluidos transformadores de múltiples devanados, transformadores de regulación de ángulo de fase y transformadores con conexiones especiales.

Relés diferenciales

Los relés diferenciales protegen generadores, buses y transformadores.
En un generador sin fallos, transformadores de corriente idénticos mantienen el relé inactivo ...

Education

Educación

JoVE Core

Electrical Engineering

Ingeniería Eléctrica

Unit 1

Unidad 1

System Protection

Protección del sistema

KEY TERMS AND CONCEPTS

TÉRMINOS Y CONCEPTOS CLAVE

differential relay protection in power systems

Differential relays protect generators, buses, and transformers by comparing currents at different points in a power system. When the currents do not match, the relay detects the difference and opens the circuit breaker. Under normal conditions, the current entering a generator, i1, equals the current leaving it, i2. If a fault occurs, these currents become unequal, and the difference current flows through the relay operating coil to trip the relay.

An electromechanical differential relay is called a balance beam relay. It works by comparing the electromagnetic forces created by the differential current. The relay trips when the force on the operating coil becomes greater than the restraining force. This same basic idea is used to protect bus zones. For bus protection, the relay operates when the total current entering and leaving the bus is not zero, which signals a fault inside the bus area.

Differential protection is more complex for transformers because they have different windings and turn ratios. Under normal operation, with no internal fault, the primary and secondary currents should balance after they are adjusted for their current transformer, or CT, ratios. If an internal fault occurs, differential current flows through the relay operating coil and causes a trip.

Three-phase transformers also require the CTs to be connected correctly to match phase shifts caused by the windings. This keeps the secondary currents in phase and helps prevent unwanted relay operation. For Y-Δ transformers, the CTs on the Y side should be connected in Δ, and the CTs on the Δ side should be connected in Y. These protection methods have also been adapted for multi-winding transformers, phase-angle regulating transformers, and transformers with special connections.

Differential Relay Protection in Power Systems

differential-relay-protection-in-power-systems

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differential relays

Differential relays protect generators, buses, and transformers by comparing currents at different points in a power system. When the currents do not match, the relay detects the difference and opens the circuit breaker. Under normal conditions, the current entering a generator, i1, equals the current leaving it, i2. If a fault occurs, these currents become unequal, and the difference current flows through the relay operating coil to trip the relay. An electromechanical differential relay is...

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key terms and concepts

Learn how differential relays protect generators, buses, and transformers by sensing current imbalance and tripping during faults, with CT connection details.

Differential Relay Protection in Power Systems | JoVE K12

JoVE Core Electrical Engineering offers easy-to-understand animated videos that cover fundamental concepts of electric circuits along with circuit analysis techniques. It incorporates first-order and second-order circuits using operational amplifiers and circuit transformation concepts. The inclusion of practical design examples and real-world applications through scientist-in-action videos adds significant educational value, making complex concepts accessible.

electrical engineering

Differential Relay Protection in Power Systems

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