Name: power system faults in sequence networks
Uploaded: 2024-11-21T14:54:31.000Z
Duration: 1 min 18 s
Channel: JoVE

Considere una sola falla de línea a tierra desde la fase A hasta la tierra en un bus trifásico, incluida una impedancia de falla. Esta impedancia es cero para una falla atornillada, es igual a la impedancia del arco para una falla de arco y representa la impedancia total de la falla durante una descarga eléctrica del aislador de la línea de transmisión.
Las condiciones de falla en el dominio de fase se traducen al dominio de secuencia, derivando las corrientes de secuencia y fase.
Las fallas de línea a línea ocurren entre las fases b y c. Al igual que antes, las condiciones del dominio de fase se convierten en el dominio de secuencia para establecer la relación entre las corrientes de fase y secuencia.
Estas condiciones de falla se satisfacen conectando redes de secuencia positiva y negativa en paralelo en terminales de falla a través de impedancia de falla.
Finalmente, se produce una falla doble de línea a tierra desde la fase b hasta la fase c a través de la impedancia de falla a tierra.
A continuación, se determinan las condiciones de falla en el dominio de fase y se transforman en el dominio de secuencia, que se satisface conectando las redes de secuencia cero, positiva y negativa en paralelo en el terminal de falla.
Este proceso determina la secuencia, las corrientes de falla y los voltajes de línea a tierra.

tipos de fallas

Fault Types

Al analizar una falla simple de línea a tierra desde la fase A hasta tierra en un bus trifásico, es importante considerar la impedancia de falla. Esta impedancia es cero para una falla en serie, igual a la impedancia de arco para una falla de arco y representa la impedancia de falla total para una descarga disruptiva del aislador de una línea de transmisión. Para derivar las corrientes de secuencia y fase, las condiciones de falla se trasladan del dominio de fase al dominio de secuencia.
En el caso de fallas de línea a línea que ocurren entre las fases B y C, las condiciones en el dominio de fase se convierten de manera similar al dominio de secuencia. Esta conversión establece la relación entre las corrientes de fase y secuencia. En estas condiciones de falla, las redes de secuencia positiva y secuencia negativa se conectan en paralelo en los terminales de falla a través de la impedancia de falla, lo que garantiza la representación precisa de la falla.
En el caso de una falla doble de línea a tierra, que ocurre desde la fase B a la fase C a través de la impedancia de falla a tierra, primero se deben determinar las condiciones de falla en el dominio de fase. Luego, estas condiciones se transforman al dominio de secuencia. Este proceso implica conectar las redes de secuencia cero, secuencia positiva y secuencia negativa en paralelo en el terminal de falla. Al hacerlo, se pueden determinar con precisión las corrientes de falla de secuencia y las tensiones de línea a tierra.
Este enfoque del análisis de fallas, que traduce las condiciones entre los dominios de fase y secuencia, permite la evaluación integral de las corrientes y tensiones de falla. Garantiza que se consideren adecuadamente todas las conexiones de red e impedancias de falla relevantes, lo que proporciona una comprensión detallada del impacto de la falla en el sistema.

Tipos de fallas

Considere una sola falla de línea a tierra desde la fase A hasta la tierra en un bus trifásico, incluida una impedancia de falla. Esta impedancia es cero para un ...

Education

Educación

JoVE Core

Electrical Engineering

Ingeniería Eléctrica

Unit 1

Unidad 1

Symmetrical and Unsymmetrical Faults

Fallas Simétricas y Asimétricas

KEY TERMS AND CONCEPTS

TÉRMINOS Y CONCEPTOS CLAVE

power system faults in sequence networks

Power system faults can be analyzed by moving between the phase domain and the sequence domain. This approach helps relate fault currents and voltages for three-phase bus faults and keeps the fault impedance in the model. Fault impedance is zero for a bolted fault, equal to the arc impedance for an arcing fault, and it represents the total fault impedance for a transmission-line insulator flashover.

For a single line-to-ground fault from phase A to ground, the phase-domain conditions are translated into the sequence domain to find the sequence and phase currents. The same conversion is used for a line-to-line fault between phases B and C. In that case, the positive-sequence and negative-sequence networks are connected in parallel at the fault terminals through the fault impedance.

A double line-to-ground fault from phase B to phase C through fault impedance to ground is handled in a similar stepwise way. The fault conditions are first determined in the phase domain and then transformed into the sequence domain. The zero-sequence, positive-sequence, and negative-sequence networks are connected in parallel at the fault terminal, which allows the sequence fault currents and line-to-ground voltages to be determined accurately.

Power System Faults in Sequence Networks

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A series resistor-inductor, or R-L, circuit can model a three-phase short circuit when the switch closes at the start of the time period. In this fault condition, all three phases of an unloaded synchronous machine are short-circuited. With no fault impedance and no initial current, the starting voltage depends on the source voltage phase angle. Kirchhoff's Voltage Law, or KVL, is used to analyze the circuit and find the total asymmetrical fault current. This current has two parts. The AC...

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Three-Phase Fault Current Analysis

Three-phase fault current analysis in an N-bus power system uses the positive-sequence network and the bus impedance matrix. It helps estimate subtransient fault currents when a short circuit occurs at one bus. The method uses superposition, which means the problem is split into two circuits that are studied separately. In the first circuit, all machine voltage sources are short-circuited. Only the prefault voltage source at the faulted bus remains. The positive-sequence bus impedance matrix...

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per-unit sequence models

Transformer Sequence Networks in Per Unit

Transformer sequence networks in per unit show how three-phase transformers respond to positive-, negative-, and zero-sequence currents. For an ideal Y-Y transformer grounded through neutral impedances, the per-unit sequence networks act much like those of a single-phase ideal transformer when the current is balanced. Balanced positive-sequence and negative-sequence currents do not create neutral current, so they do not cause voltage drops across the neutral path. Zero-sequence current behaves...

fault types

Power system faults can be analyzed by moving between the phase domain and the sequence domain. This approach helps relate fault currents and voltages for three-phase bus faults and keeps the fault impedance in the model. Fault impedance is zero for a bolted fault, equal to the arc impedance for an arcing fault, and it represents the total fault impedance for a transmission-line insulator flashover. For a single line-to-ground fault from phase A to ground, the phase-domain conditions are...

key terms and concepts

Learn how single line-to-ground, line-to-line, and double line-to-ground faults are converted from phase to sequence domain to find currents and voltages.

Power System Faults in Sequence Networks | 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

Power System Faults in Sequence Networks

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