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

差動保護の一種であるパイロットリレーは、通信チャネルを利用して、広く普及した伝送線路上の端末量を比較します。通常、定格が69〜115kVの短いラインに適用されます。
4つの通信チャネルが使用され、2つの主要な障害検出方法(電力の流れを評価するための方向比較と、相対的な電流位相角を評価するための位相比較)が使用されます。
差動リレーと同様に、パイロットリレーは、複雑なリレー設定やシステム障害の計算を必要とせずに、プライマリゾーン保護を提供します。
高電圧送電線の障害を迅速に検出して切り分け、無停電電源を確保します。
数値リレーは、障害検出にマイクロプロセッサとソフトウェアを使用します。その利点には、コンパクトなサイズ、配線の削減、プログラマビリティ、トランスの負担の低減、多機能機能、感度、信頼性、速度の向上などがあります。また、自動リセットすることもできます。
ただし、数値リレーは外部電源システムの過渡現象に対して脆弱であるため、エンジニアは一般的な故障モードに注意する必要があります。

パイロットおよび数値リレー

Pilot and Numeric Relaying

パイロットリレーは、電力システムで使用される差動保護の一種です。直接リレー接続の代わりに通信チャネルを介して機器の端末の電気量を比較します。この方法は、端末が離れている伝送線路に不可欠です。通常、定格 69 ～ 115 kV の線路では最大 80 km です。パイロットリレーには、次の 4 種類の通信チャネルが使用されます。

<ul style="list-style-type: disc; padding-left: 35px; margin: 0;">
	<li>パイロットワイヤ: DC、50 ～ 60 Hz、またはオーディオ周波数で動作する独立した電気回路です。</li>
	<li>電力線搬送: このタイプは、周波数が 30 ～ 300 kHz の伝送線路自体を通信媒体として利用します。</li>
	<li>マイクロ波: 皿型アンテナを使用して見通し線経由で送信される 2 ～ 12 GHz の信号を使用します。</li>
	<li>光ファイバーケーブル: 非導電性ケーブルを介した光変調を採用し、電気絶縁および干渉の問題を排除します。</li>
</ul>



障害検出方法には、方向比較と位相比較の 2 種類があります。方向比較法では、線路端末での電力フローを比較し、位相比較法では、端末での電流の相対位相角を比較します。

数値リレー、またはデジタルリレーは、障害検出用のソフトウェアを備えたマイクロプロセッサベースのシステムを使用します。数値リレーは、パネル配線を減らし、リモート更新による設定変更を簡素化し、変圧器への負担を最小限に抑えます。コンポーネント数が少ないため、感度が向上し、トリップ時間が短縮され、信頼性が向上します。これらのリレーは、障害後のデータを分析し、システムの回復を確認し、変化する状況に合わせて設定を調整できます。

数値リレーはサイバーセキュリティのリスクに敏感なので、北米電力信頼性協会 (NERC) のセキュリティ標準に準拠することが重要です。

分散型保護では、各リレーはローカルの変流器と電圧変圧器から情報を受信し、ローカルのブレーカーのみをトリップします。このアプローチにより、パイロットリレーに依存せずに信頼性を確保できます。数値リレーを集中型システムと統合して、全体的な保護調整とシステムの信頼性を強化できます。

差動保護の一種であるパイロットリレーは、通信チャネルを利用して、広く普及した伝送線路上の端末量を比較します。それ。。。

Education

JoVE Core

Electrical Engineering

電気工学

Unit 1

ユニット1

System Protection

システム保護

KEY TERMS AND CONCEPTS

主要用語と概念

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 電気工学 は、電気回路の基本概念と回路解析テクニックを網羅したアニメーションビデオシリーズです。オペアンプと回路変換および 1 次・ 2 次回路の概念を網羅しています。実験を撮影した実写動画では、設計例や現代社会での応用が含まれており、複雑な概念も分かりやすく学習いただけます。

electrical engineering

Pilot Relays and Digital Protection

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