Name: power system protection zones
Uploaded: 2024-11-21T14:54:35.000Z
Duration: 1 min 16 s
Channel: JoVE

電力システムでは、セットアップ全体が保護ゾーンに分割されています。ゾーン内で障害が発生した場合、そのゾーンは分離され、システムの残りの部分が保護されます。
これらのゾーンには、発電機、変圧器、バス、送電線と配電線、モーターが含まれます。これらは家の中の異なる部屋と考えてください、それぞれが回路ブレーカーで保護されています。
各部屋またはゾーンは、閉じた破線で定義されます。各部屋内には、1つ以上のコンポーネントが存在する可能性があります。
これらの保護ゾーンのユニークな特性には、オーバーラップとサーキットブレーカーの配置が含まれます。サーキットブレーカーは、これらの部屋の交差点に立っている警備員のようなもので、問題が発生した部屋を隔離します。
そのため、キッチンで障害が発生した場合、キッチンに接続されているすべてのサーキットブレーカーが開き、キッチンが分離され、障害が他の部屋に影響を与えるのを防ぎます。
ゾーンが重なることで、隣接する部屋の間に2つのドアがあることで、保護されていないエリアが残らないようにするため、一方が故障してももう一方を保護できます。
オーバーラップは、各サーキットブレーカーに2つの計器トランスとリレーを使用して実現されます。

保護領域

Zones of Protection

電力システムでは、障害を隔離し、ネットワークの残りの部分を保護するために、セットアップ全体が保護領域に分割されます。これらの領域には、発電機、変圧器、バス、伝送線路、配電線、モーターが含まれます。各領域は、家の中の独立した部屋として視覚化でき、各部屋は独自の回路遮断機によって保護されます。 
保護領域は、1 つ以上のコンポーネントを含む閉じた破線で定義されます。これらの領域の主な特徴は、領域の交差点に回路遮断機を戦略的に配置し、領域内の障害を分離できるようにすることです。たとえば、キッチンに似た領域で障害が発生したとします。その場合、その領域に関連付けられた回路遮断機が開き、障害を分離して、他のエリアへの影響を防ぎます 。 
保護領域間の重複は、システムのどの部分も保護されていない状態にならないようにするために重要です。この重複は、各回路遮断器に計器用変圧器とリレーのセットを 2 つ用意して冗長性を確保することで実現されます。この冗長性により、1 つの保護デバイスが故障しても、もう 1 つのデバイスが必要な保護を提供できるため、電力システム全体の信頼性と安全性が向上します。この設定により、障害を効果的に分離し、電力ネットワーク全体の整合性と効率性を維持できます。 
効果的な保護スキームには、差動リレー、距離リレー、過電流リレーなど、各領域の特定のニーズに合わせて調整されたさまざまな種類の保護リレーの使用が含まれます。通信システムも、保護デバイスの動作を調整し、迅速かつ正確な障害分離を保証する上で重要な役割を果たします。これらの戦略を実装することで、電力システムは高いレベルの信頼性と安全性を実現し、障害による中断や損害を最小限に抑えることができます。

電力システムでは、セットアップ全体が保護ゾーンに分割されています。ゾーン内で障害が発生した場合、そのゾーンは分離され、システムの残りの部分が保護されます。
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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

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 house analogy, stays contained and does not spread to the rest of the system.

Overlap between zones is important because it helps keep every part of the network protected. This overlap is created by using two sets of instrument transformers and relays for each circuit breaker. That redundancy matters if one protection device fails, because the second one can still act and keep the system safe.

Different zones may use different protective relays, including differential relays, distance relays, and overcurrent relays. Communication systems also help these devices work together so faults are cleared quickly and accurately. Together, these protection strategies improve reliability, limit damage, and help maintain the integrity and efficiency of the power network.

Power System Protection Zones

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 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 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...

key terms and concepts

Explore how power system protection zones use circuit breakers, overlapping relays, and communication to isolate faults and protect generators, lines, and motors.

Power System Protection Zones | 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

Power System Protection Zones

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