Articles about relay protection, both in Chinese and English

Relay protection is a system composed of relay protection technology and relay protection device.

There are four basic technical requirements for relay protection:

Reliability, selectivity, snapness, sensitivity.

1. The circuit breaker cannot detect the short-circuit current, and the current transformer detects the short-circuit current.

2. The action of the circuit breaker is controlled by relay protection.

3. After the bus failure, multiple sets of protection can detect the fault, but the set of protection with the shortest action time limit is set to act first (the bus fault should be the bus differential protection first).

Hello! If the bus fails, the bus protection is activated, disconnecting all lines and transformers connected to the bus. The circuit breaker only plays the role of cutting off the power supply, and the start of the circuit breaker is started by the protection device.

The circuit breaker itself does not have a current detection function and does not start an automatic trip function, and is only used as a line cut-off. The action of the circuit breaker is activated under the control of the relay protection device.

The State Grid Corporation team will answer for you, I hope it can be helpful to you!

A few ways to do this are as follows:

1) Classification according to the protected object: transmission line protection, generator protection, transformer protection, motor protection, bus protection, etc.;

2) Classified according to the protection principle: current protection, voltage protection, distance protection, differential protection, direction protection, zero sequence protection, etc.;

3) Classification according to the type of fault reflected by protection: phase-to-phase short-circuit protection, grounding fault protection, turn-to-turn short-circuit protection, disconnection protection, out-of-step protection, loss of magnetism protection and over-excitation protection, etc.;

4) According to the technical classification of relay protection devices: electromechanical protection (such as electromagnetic protection and inductive protection), rectifier protection, transistor protection, integrated circuit protection and microcomputer protection, etc.;

5) Classification according to the role of protection: primary protection, reserve protection, auxiliary protection, etc.;

You're not sure about this question, huh? What the hell are you asking?

1。Distance relays, single and multi-phase, are used when the system configuration is changed, or when generating modes that provide too much fault current to change allows reliable settings to use only current as the determining factor.

2. The installation of shunt capacitors and reactors has completely different reasons, and even if they are parallel to the line itself, it usually does not have a significant impact on the transmission line relay.

3. However, since series reactors are often required to achieve safe short-circuit current levels, they rarely take service and do not take service either. Therefore, the reactor can be considered present, and the corresponding line relay.

4。Series capacitors introduce a discontinuous reactive element that fails over from the relay and goes beyond that of the capacitor.

Study the abnormal working conditions of power system failures and endangering safe operation, and take anti-accident automation measures to countermeasures. Because in the process of its development, relays with contacts were mainly used to protect the power system and its components (generators, transformers, transmission lines, etc.) from damage, so it is called relay protection. The basic tasks are:

When the power system fails or abnormal working conditions, the faulty equipment is automatically removed from the system in the shortest time and the smallest area that can be realized, or a signal is sent out by the personnel on duty to eliminate the root cause of the abnormal working conditions, so as to reduce or avoid the damage to the equipment and the impact on the power supply in adjacent areas.

The earliest protective relay devices were fuses. Later, electromagnetic relay protection devices acting on circuit breakers, electronic static relays, and digital relay protection using computers appeared. With the rapid development of electronic technology, computer technology, and communication technology, artificial intelligence technologies such as artificial neural networks, genetic algorithms, evolutionary scale, and fuzzy logic have been successively applied in the field of relay protection.

The protective relay device must have the following 4 basic properties: Sensitivity. The ability to reflect a fault, usually expressed as a sensitivity factor.

Reliability. At the time of this action, no rejection action occurs. Rapidity.

Faults or anomalies can be eliminated in the shortest possible time. Selectivity. Faults are removed in the smallest possible interval to ensure maximum continued power supply to the fault-free section.

When choosing a relay protection scheme, in addition to the above four basic performances, you should also pay attention to its economy. That is, not only the investment and operation and maintenance costs of the protection device must be considered, but also the losses caused by the rejection or misoperation of the device due to the imperfection of the device to the national economic and social life.

With the increasing capacity of the power system and the wider and wider range, only the relay protection devices of each element of the system are far from preventing the occurrence of serious accidents of long-term large-scale power outages in the whole power system. Therefore, it is necessary to start from the overall situation of the power system and study what kind of working conditions the system will present after the faulty components are removed by the action of the corresponding relay protection device, what characteristics will appear when the system loses stability, and how to restore its normal operation as soon as possible. The task of system protection is to minimize the scope of influence and minimize the load outage time when the normal operation of the large power system is destroyed.

In addition, the failure of any part of the machine, furnace and electricity will affect the safe production of electric energy, especially the mutual influence and coordination of large units and large power systems is becoming a major issue for the safe production of electric energy. Therefore, the configuration scheme of the relay protection and safety automatic device of the system should consider the transformer-bearing capacity of the machine, furnace and other equipment, and the design and manufacture of the machine and furnace equipment should also fully consider the actual needs of the safe and economical operation of the power system. For the safety of giant generator sets, not only should there be perfect relay protection, but also should be researched and promoted fault technology.

Foreign well-known brands include ABB, GE, SWEL, SEL, Siemens, Areva, Schneider, etc., and domestic well-known brands include NARUI, Nanzi, Sifang, Xu Ji, etc.

You can check it inside, you can check it out!

For the power grid to operate normally, it must have relay protection. Protective equipment is the secondary equipment of the power system.

Current transformers and voltage transformers collect information from primary equipment such as busbars and outgoing wires, and transmit them to the control room through cables. On the one hand, real-time detection is realized, and on the other hand, this information is provided to the protection equipment, and if there is any abnormality, the protection equipment judges the fault and automatically trips. The protection facility is the rows of cabinets in the main control room of the substation.

Now microcomputer protection is widely used, and the function is very perfect.

Relay protection is a system that collects information, analyzes and judges, and outputs instructions. The output command is tripping, automatic reclosing or something, and the fault is removed in a few tenths of a second or even less.