Name: pilot relays and digital protection
Uploaded: 2024-11-21T14:54:35.000Z
Duration: 1 min 21 s
Channel: JoVE

O relé piloto, uma forma de proteção diferencial, utiliza canais de comunicação para comparar as quantidades de terminais em linhas de transmissão amplamente espalhadas. É normalmente aplicado a linhas mais curtas, classificadas entre 69 e 115 kV.
Quatro canais de comunicação são usados, com dois métodos primários de detecção de falhas: comparação direcional, para avaliar fluxos de potência, e comparação de fase, para avaliar ângulos de fase de corrente relativa.
Como os relés diferenciais, os relés piloto fornecem proteção de zona primária sem exigir configurações complexas de relé ou cálculos de falhas do sistema.
Eles detectam e isolam prontamente falhas em linhas de transmissão de alta tensão para garantir um fornecimento de energia ininterrupto.
Os relés numéricos usam microprocessadores e software para detecção de falhas. Suas vantagens incluem um tamanho compacto, menos fiação, programabilidade, menor carga do transformador, recursos multifuncionais e sensibilidade, confiabilidade e velocidade aprimoradas. Eles também podem ser redefinidos automaticamente.
No entanto, os engenheiros devem estar cientes dos modos de falha comuns, pois os relés numéricos são vulneráveis a transientes externos do sistema de energia.

relés piloto e numérico

Pilot and Numeric Relaying

O relé piloto é um tipo de proteção diferencial usado em sistemas de energia. Ele compara as grandezas elétricas nos terminais do equipamento por meio de um canal de comunicação em vez da interconexão direta do relé. Esse método é essencial para linhas de transmissão em que os terminais estão distantes, normalmente até 80 km para linhas com classificações de 69 a 115 kV. Quatro tipos de canais de comunicação são usados para o relé piloto:


 
 Fios-piloto:
 
 São circuitos elétricos separados que operam em CC, 50 a 60 Hz ou frequências de áudio.


 
 Portadora de linha de energia:
 
 Esse tipo utiliza a própria linha de transmissão como meio de comunicação, com frequências entre 30 e 300 kHz.


 
 Microondas:
 
 Usa sinais de 2 a 12 GHz transmitidos por caminhos de linha de visão com antenas parabólicas.


 
 Cabo de fibra óptica:
 
 Emprega modulação de luz por meio de cabos não condutores, eliminando problemas de isolamento elétrico e interferência.


 Há dois métodos de detecção de falhas: comparação direcional e de fase. O método de comparação direcional compara os fluxos de energia nos terminais da linha, enquanto o método de comparação de fase compara os ângulos de fase relativos das correntes nos terminais.


 O relé numérico ou digital usa sistemas baseados em microprocessador com software para detecção de falhas. Os relés numéricos reduzem a fiação do painel, simplificam as alterações de configurações por meio de atualizações remotas e minimizam a carga sobre os transformadores. Eles oferecem maior sensibilidade, tempos de disparo mais rápidos e maior confiabilidade por meio de menos componentes. Esses relés podem analisar dados pós-falha, verificar a recuperação do sistema e adaptar as configurações às condições variáveis.


 Os relés numéricos são sensíveis aos riscos de segurança cibernética, por isso é fundamental cumprir as normas de segurança da North American Electric Reliability Corporation (NERC).


 Na proteção descentralizada, cada relé recebe informações dos transformadores locais de corrente e tensão, disparando apenas os disjuntores locais. Essa abordagem garante a confiabilidade sem depender de relés piloto. Os relés numéricos podem se integrar aos sistemas centralizados para melhorar a coordenação geral da proteção e a confiabilidade do sistema.

Relés Piloto e Numérico

O relé piloto, uma forma de proteção diferencial, utiliza canais de comunicação para comparar as quantidades de terminais em linhas de transmissão amplamente espalhadas. Ela...

Education

JoVE Core

Electrical Engineering

Engenharia Elétrica

Unit 1

Unidade 1

System Protection

Proteção do Sistema

KEY TERMS AND CONCEPTS

TERMOS-CHAVE E CONCEITOS

pilot relays and digital protection

Pilot relays and numeric relays help protect power systems. Pilot relaying is a form of differential protection, which compares electrical quantities at equipment terminals through a communication channel instead of a direct relay link. It is especially useful for transmission lines with terminals far apart, often up to 80 km on 69 to 115 kV lines.

Pilot relaying can use several communication channels. Pilot wires are separate electrical circuits that operate at DC, 50 to 60 Hz, or audio frequencies. Power-line carrier uses the transmission line itself as the communication path, with frequencies from 30 to 300 kHz. Microwave systems send 2 to 12 GHz signals through line-of-sight paths with dish antennas. Fiber optic cable carries light through non-conducting cables, which avoids electrical insulation and interference problems.

Fault detection in pilot relaying uses directional comparison or phase comparison. Directional comparison checks the direction of power flow at the line terminals. Phase comparison checks the relative phase angles of currents at the terminals. Both methods help decide whether a fault is inside the protected section of the line.

Numeric relaying, also called digital relaying, uses microprocessor-based systems and software to detect faults. These relays reduce panel wiring, make setting changes easier through remote updates, and place less burden on transformers. They also offer higher sensitivity, faster tripping times, and better reliability because they use fewer components.

Numeric relays can also study data after a fault, check how the system recovers, and adjust settings when conditions change. They do face cybersecurity risks, so North American Electric Reliability Corporation, or NERC, security standards are important. In decentralized protection, each relay uses local current and voltage transformer data and trips only its local breakers. Numeric relays can also work with centralized systems to improve protection coordination and overall system reliability.

Pilot Relays and Digital Protection

instrument transformers

Voltage and Current Sensing in Power Grids

Instrument transformers help power substations measure voltage and current safely. They create isolated replicas of electrical signals for measurement and protection. These devices support protective relays and other monitoring equipment that keep power systems stable and reliable. The two main types are voltage transformers, or VTs, and current transformers, or CTs. A voltage transformer reduces the primary voltage to a lower level that relays and measuring devices can use. A current...

overcurrent relays

Relay Settings for Circuit Fault Protection

Overcurrent relays protect circuits by sensing excess current through the secondary side of a current transformer. They are an important part of circuit protection and help keep power systems stable when a fault occurs. Two main relay types are used here: instantaneous and time-delay overcurrent relays. An instantaneous relay trips right away when current rises above the pickup current, which is the preset level that starts the relay. It then energizes the circuit breaker trip coil at once,...

radial system protection

Breaker Coordination in Radial Systems

Breaker coordination in radial systems uses time-delay overcurrent relays to limit load interruption. When a fault happens, the nearest breaker should open first. Upstream breakers stay closed because they are set with longer delays. This lets the fault be isolated while the rest of the system keeps running. If a fault is downstream of the third breaker, only the third breaker should trip. That removes power from the load beyond the fault. The second breaker keeps a longer delay setting, so...

reclosers and fuses

Fault Coordination with Reclosers and Fuses

Fault coordination with reclosers and fuses helps protect radial distribution circuits. A recloser is an automatic switch that interrupts AC power and then closes again on a preset schedule. This brief outage can clear temporary faults on overhead lines, such as those caused by tree limbs or wildlife, and it can improve overall reliability. Reclosers and their ground-level hazards also matter. Contact with a recloser or with a broken energized conductor on the ground can be dangerous. That is...

directional relays

Directional Relays in Power System Protection

Directional relays help protect power systems by telling forward faults from reverse faults. They are used when fault current flows mainly in one direction on a line. This makes the relay useful for safe and efficient fault clearing. On a protected line, a fault downstream, or to the right of the current transformer, usually makes the fault current lag the bus voltage by about 90 degrees. This is called the forward direction. A fault upstream, or to the left, may make the fault current lead...

zones of protection

Power System Protection Zones

Power system protection zones divide the network into sections so faults can be isolated quickly. These zones can include generators, transformers, buses, transmission lines, distribution lines, and motors. Each zone is shown with closed dashed lines and contains one or more components. Circuit breakers are placed at the borders where protection zones meet. If a fault happens in one zone, the related breakers open and disconnect only that section. A fault in one area, such as a kitchen in the...

line protection with impedance relays

Impedance Relays for Fault Detection

Impedance relays help protect power lines by watching the voltage-to-current ratio on a line. They measure the apparent impedance, which is the electrical opposition the relay sees at that point in the system. This makes them useful when time-delay overcurrent relays are hard to coordinate in complex radial systems and when directional overcurrent relays are difficult to use in multi-source transmission loops. These relays respond strongly during a fault. As current rises and voltage falls,...

differential relays

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...

pilot and numeric relaying

Pilot relays and numeric relays help protect power systems. Pilot relaying is a form of differential protection, which compares electrical quantities at equipment terminals through a communication channel instead of a direct relay link. It is especially useful for transmission lines with terminals far apart, often up to 80 km on 69 to 115 kV lines. Pilot relaying can use several communication channels. Pilot wires are separate electrical circuits that operate at DC, 50 to 60 Hz, or audio...

key terms and concepts

Learn how pilot relays compare terminal data, how directional and phase methods detect faults, and how numeric relays improve power system protection.

Pilot Relays and Digital Protection | 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

Pilot Relays and Digital Protection

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