One, what is electrical once, twice?
A lot of small partners can not distinguish the electrical primary and secondary equipment, today by Jiangxi Electric to explain their main differences in detail.
Mainly reflected in the difference between electrical primary equipment and secondary equipment:
Primary equipment refers to high-voltage electrical equipment directly used in the production process of producing, transporting and distributing electrical energy. It includes generator, transformer, circuit breaker, isolation switch, automatic switch, contactor, knife switch, bus, transmission line, power cable, reactor, motor and so on.
Electrical equipment connected to each other by primary equipment to form power generation, transmission, distribution or other production processes is called primary equipment.
Secondary equipment refers to the low-voltage electrical equipment required to monitor, control, adjust and protect the work of primary equipment and provide operating conditions or production command signals for operation and maintenance personnel. Such as fuses, control switches, relays, control cables, etc.
The electrical equipment that is interconnected by the secondary equipment and constitutes the monitoring, control, regulation and protection of the primary equipment is called the secondary equipment.
Second, electrical classification
Electrical primary equipment can be divided into six categories according to its role in production:
(1) Equipment for the production and conversion of electrical energy. For example, the generator converts mechanical energy into electrical energy, the motor converts electrical energy into mechanical energy, and the transformer increases or decreases the voltage to meet the needs of transmission and distribution.
(2) Switch on or off the circuit. Such as circuit breakers, isolating switches, fuses, contactors, etc. They are used to close or disconnect the circuit in normal or emergency conditions of the power system.
(3) Limit fault current and guard against overvoltage electrical appliances. Such as limiting the short circuit current reactor and guard against overvoltage arrester.
(4) Grounding device. It is a metal conductor buried in the ground directly in contact with the earth and a metal wire connected with electrical equipment. Whether it is the working grounding of the neutral point of the power system or the protective grounding to protect personal safety, it is connected with the grounding device embedded in the ground.
(5) current carrying conductor. For example, bare conductors and cables. Connect related electrical equipment according to design requirements.
(6) AC electrical conversion equipment between one and two times. Such as voltage and current transformer, through which the voltage and current of the primary side are converted to the secondary system.
Third, electrical secondary circuit classification
1. Control (operation) loop:
2, regulation loop: refers to the regulation type automatic device. For example, the VQC system carries out on-load voltage regulation device for the main transformer and the excitation regulation device of the generator. It is composed of a measuring mechanism, a transmission mechanism, a regulator and an executive mechanism.
Its function is to adjust the working state of the primary equipment online in real time according to the changes of the operating parameters of the primary equipment to meet the operating requirements.
3, relay protection and automatic device circuit: it is composed of measurement circuit, comparison part, logic part and execution part.
Its role is based on the operating state of a device and the system, determine the occurrence of failure or abnormal, automatically issue a trip command to selectively remove the fault, and send a corresponding signal, when the fault or abnormal disappear, quickly put into the relevant circuit breaker (reclosing and standby power automatic input device), restore the normal operation of the system. (Note: The above mainly refers to the protection and automatic devices composed of conventional electromagnetic relays)
4. Measurement loop:
Its role is to indicate or record the operating parameters of the primary equipment and system, so that the operator can master the operation of the primary system, and it is also the main basis for analyzing the power quality, calculating economic indicators, understanding the system power flow and the operating conditions of the main equipment. (Note: Integrated automation has made the boundary point between the loop and the tertiary loop increasingly blurred)
5, signal loop:
Its function is to reflect the working state of the primary and secondary equipment.
6, operation power system:
Its role is mainly to provide working power and operating power for control, protection, signal and other equipment, for the main transformer cooling, water and coal and other power equipment, to ensure that all equipment in power plants and substations work normally.
The electrical secondary circuit connecting the protection device has the following circuits:
(1) From the secondary terminal of the current transformer and voltage transformer to the secondary circuit of the relays protection device (for sleeve transformers such as multi-oil circuit breakers or transformers, starting from the terminal box).
(2) From the relay protection DC shunt fuse to the secondary circuit of the relevant protection device.
(3) The DC circuit from the protection device to the control panel and the central signal panel.
(4) The exit terminal block of the relay protection device is connected to the jumping and closing circuit of the terminal block of the circuit breaker operating box.
Electrical secondary equipment is the research and management of secondary equipment. And the electrical secondary we want to understand is the division at this level.
It is an important aspect of electrical secondary, responsible for the safety protection of primary equipment, is the guarantee of the safe operation of primary equipment, commonly known as "backer", the related equipment has the transformer group protection, line protection, factory protection (station protection), fault recording device, protection and fault information sub-station (main station).
2, electrical measurement, measurement: responsible for monitoring the operation data of the primary equipment, to facilitate the monitoring of relevant personnel, such as transmitters, ammeter, voltmeter, power meter, etc., the metering meter is used for energy saving analysis and electricity settlement. This major involves the regular calibration and maintenance of relevant instruments to ensure the authenticity and reliability of data.
3, automation: generally used for equipment management connected with the power grid dispatching system and information exchange, common PMU (phasor measuring device), RTU (remote device), AVC (automatic voltage control), power market, electricity billing, etc. (sub-station or main station).
4. Communication: Responsible for providing channels for data transmission of automation equipment and maintenance and management of channel-related equipment. Changes and adjustments involving communication methods; The main equipment includes optical terminal, digital distribution frame, audio distribution frame, administrative dispatching switch, optical fiber distribution frame and other equipment.
The reason why it is independent is that it is different from the relay protection and automation specialty and is associated with the relay protection and automation. Such as excitation system, frequency conversion system, soft start device, quick cutting device essentially belong to automatic control system.
A device that provides power to a secondary device is called a power device. Such as 110V, 220V DC system, battery, UPS system, etc., can be called power supply equipment.
Four, electrical secondary control
Secondary control is to convert the voltage of a high voltage end to the voltage of a low voltage end to control the control line of a high-voltage component, which is called secondary control. That's not the right answer.
Simple understanding is that a load directly open and close the circuit is called a primary line, in a line to install an AC contactor and other electrical appliances, by controlling the AC contactor suction and disconnect, to control the primary circuit line is called a secondary control line.