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

차동 보호의 한 형태인 파일럿 릴레이는 통신 채널을 활용하여 널리 퍼져 있는 전송 라인의 단자 수량을 비교합니다. 일반적으로 69kV에서 115kV 사이의 짧은 라인에 적용됩니다.
4개의 통신 채널이 사용되며, 두 가지 주요 오류 감지 방법, 즉 전력 흐름을 평가하기 위한 방향 비교와 상대 전류 위상각을 평가하기 위한 위상 비교가 사용됩니다.
차동 릴레이와 마찬가지로 파일럿 릴레이는 복잡한 릴레이 설정이나 시스템 오류 계산 없이 기본 영역 보호를 제공합니다.
이 인버터는 고전압 송전선로의 오류를 신속하게 감지하고 격리하여 무정전 전원 공급을 보장합니다.
숫자 릴레이는 오류 감지를 위해 마이크로프로세서와 소프트웨어를 사용합니다. 장점으로는 콤팩트한 크기, 더 적은 배선, 프로그래밍 가능성, 낮은 변압기 부담, 다기능 기능, 향상된 감도, 신뢰성 및 속도 등이 있습니다. 또한 자동 재설정할 수 있습니다.
하지만 엔지니어는 숫자 계전기가 외부 전력 시스템 과도 상태에 취약하기 때문에 일반적인 고장 모드를 알고 있어야 합니다.

파일럿 및 숫자 릴레이

Pilot and Numeric Relaying

파일럿 릴레이는 전력 시스템에서 사용되는 차동 보호의 한 유형입니다. 직접 릴레이 상호 연결 대신 통신 채널을 통해 장비 단자에서 전기량을 비교합니다. 이 방법은 단자가 멀리 떨어져 있는 송전선에 필수적이며, 일반적으로 정격이 69~115kV인 회선의 경우 최대 80km입니다. 파일럿 릴레이에는 네 가지 유형의 통신 채널이 사용됩니다.

<ul style="list-style-type: disc; display: flex; flex-direction: column; gap: 10px; padding: 0 0 0 40px;">
 <li>파일럿 와이어: DC, 50~60Hz 또는 오디오 주파수에서 작동하는 별도의 전기 회로입니다.</li>
 <li>전력선 캐리어: 이 유형은 전송선 자체를 통신 매체로 활용하며 주파수는 30~300kHz입니다.</li>
 <li>마이크로파: 접시 안테나를 사용하여 시야선 경로를 통해 전송되는 2~12GHz 신호를 사용합니다.</li>
 <li>광섬유 케이블: 비전도성 케이블을 통해 빛을 변조하여 전기 절연 및 간섭 문제를 제거합니다.</li>
</ul>

 두 가지 결함 감지 방법이 있습니다. 방향 비교와 위상 비교입니다. 방향 비교 방법은 회선 단자에서 전력 흐름을 비교하는 반면 위상 비교 방법은 단자에서 전류의 상대 위상 각도를 비교합니다.

숫자 또는 디지털 릴레이는 오류 감지를 위한 소프트웨어가 있는 마이크로프로세서 기반 시스템을 사용합니다. 숫자 릴레이는 패널 배선을 줄이고, 원격 업데이트를 통해 설정 변경을 간소화하며, 변압기의 부담을 최소화합니다. 더 적은 구성 요소를 통해 더 높은 감도, 더 빠른 트리핑 시간 및 향상된 안정성을 제공합니다. 이러한 릴레이는 오류 후 데이터를 분석하고, 시스템 복구를 확인하고, 변화하는 조건에 맞게 설정을 조정할 수 있습니다.

숫자 릴레이는 사이버보안 위험에 민감하므로 북미 전기 신뢰성 협회(NERC) 보안 표준을 준수하는 것이 중요합니다.

분산형 보호에서 각 릴레이는 로컬 전류 및 전압 변압기로부터 정보를 수신하여 로컬 차단기만 트립합니다. 이 접근 방식은 파일럿 릴레이에 의존하지 않고도 신뢰성을 보장합니다. 숫자 릴레이는 중앙 시스템과 통합되어 전반적인 보호 조정 및 시스템 신뢰성을 향상시킬 수 있습니다.

차동 보호의 한 형태인 파일럿 릴레이는 통신 채널을 활용하여 널리 퍼져 있는 전송 라인의 단자 수량을 비교합니다. 술래...

Education

교육

JoVE Core

Electrical Engineering

전기공학

Unit 1

제1단원

System Protection

시스템 보호

KEY TERMS AND CONCEPTS

주요 용어 및 개념

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

Description

Transcript

Tags