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

在电力系统中，整个装置被划分为若干保护区域。如果某一区域内发生故障，则该区域将被隔离，从而保护系统的其余部分。
这些区域包括发电机、变压器、母线、输电和配电线路以及电动机。可以将它们比作房屋中的不同房间，每个房间都由其断路器进行保护。
每个房间或区域由一条封闭的虚线定义。在每个房间内，可能包含一个或多个组件。
这些保护区域的独特特性包括重叠性以及断路器的布置。断路器类似于守卫，位于这些区域的交界处，能够隔离出现故障的任一区域。
因此，如果厨房发生故障，所有与厨房相关的断路器都将断开，从而将其隔离，防止故障影响其他房间。
通过在相邻房间之间设置两道门，重叠区域可确保没有区域处于无保护状态，因为若其中一道门失效，另一道门仍能提供防护。
通过为每个断路器使用两个仪表互感器和继电器来实现重叠。

保护区

Zones of Protection

在电力系统中，整个装置被划分为多个保护区，以隔离故障并保护网络的其余部分。这些区域包括发电机、变压器、母线、输电线、配电线和电动机。每个区域都可以看作是房子里的一个独立房间，每个房间都由自己的断路器保护。

保护区由包含一个或多个组件的闭合虚线定义。这些区域的一个关键特征是在区域交叉点处策略性地放置断路器，以确保可以隔离区域内的任何故障。例如，假设故障发生在类似于厨房的区域。在这种情况下，与该区域相关的断路器将打开，隔离故障并防止其影响其他区域。

保护区之间的重叠对于确保系统的任何部分都受到保护至关重要。这种重叠是通过为每个断路器配备两组仪用互感器和继电器来实现的，从而提供冗余。这种冗余确保即使一个保护装置发生故障，另一个保护装置仍能提供必要的保护，从而提高电力系统的整体可靠性和安全性。这种设置可以有效隔离故障，保持整个电网的完整性和效率。

有效的保护方案涉及使用不同类型的保护继电器，例如差动继电器、距离继电器和过流继电器，以满足每个区域的特定需求。通信系统在协调保护装置的动作方面也发挥着至关重要的作用，确保快速准确地隔离故障。通过实施这些策略，电力系统可以实现高水平的可靠性和安全性，最大限度地减少故障造成的中断和损害。

在电力系统中，整个系统被划分为若干保护区域。当某一区域内发生故障时，该区域将被隔离，从而保护系统的其余部分。

Education

教育

JoVE Core

Electrical Engineering

电气工程

Unit 1

第一单元

System Protection

系统保护

KEY TERMS AND CONCEPTS

关键术语与概念

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 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 Protection Zones

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