Power system automation realizes automatic control, automatic scheduling and automatic management of electric energy production, transmission and management. The power system [1] is a complex and large-scale system with a wide geographical distribution, composed of power plants, substations, transmission and distribution networks, and users.

The field of power system automation includes automatic detection, regulation and control of production process, automatic safety protection of systems and components, automatic transmission of network information, automatic scheduling of system production, and automatic economic management of enterprises. The main goal of power system automation is to ensure the power quality (frequency and voltage) of power supply, ensure the safe and reliable operation of the system, and improve economic benefits and management efficiency.

Transmission system

The automatic transmission system of power system information is referred to as telecontrol system. Its function is [2] to realize real-time information transmission between the dispatch center and the power plant substation. The automatic transmission system consists of a telecontrol device and a telecontrol channel. Telecontrol channels have various forms such as microwave, carrier, high frequency, audio frequency and optical guide communication. According to the function, the telecontrol device is divided into three categories: telemetry, remote signaling and remote control. The process of transmitting the analog quantity of the plant station to the receiving end located in the dispatch center and displaying it through transformation is called telemetry. The process of transmitting the switching quantity of the plant to the receiving end and displaying it is called remote signaling. The process of transmitting the control and regulation signals of the dispatching end to the receiving end located at the plant station to realize the control of the regulation object is called remote control or remote adjustment. According to the composition of the telecontrol device, it can be divided into wiring logic telecontrol device and storage program logic device. The former consists of a hardware logic circuit that implements its function in a fixed wiring mode, and the latter is a computerized telecontrol device.

Accident device

The function of the anti-accident automatic device is to prevent accidents in the power system from endangering the operation of the system and electrical equipment. There are two basic types of anti-accident automatic devices installed in power systems.

Relay protection device: its function is to prevent damage to electrical equipment due to system failure, and is commonly used to protect electrical equipment such as lines, busbars, generators, transformers, motors, etc. According to the principle of protection, relay protection devices are divided into overcurrent protection, direction protection, differential protection, distance protection and high-frequency protection.

System safety protection device: It is used to ensure the safe operation of the power system and prevent catastrophic accidents such as system oscillation, out-of-step detraining, network-wide frequency collapse and voltage collapse. The system safety protection device is divided into 4 forms according to the function:

The first is the automatic input of standby equipment, such as the automatic input of standby power supply, the automatic reclosing of transmission lines, etc.;

Second, it belongs to the power shortage of the control receiving end, such as low-frequency automatic load reduction device, low-voltage automatic load reduction device, low-frequency self-starting device of the unit, etc.;

Third, it belongs to the control of excess power at the transmission end, such as fast automatic cutting device, fast closing valve device, electric braking device, etc.;

Fourth, it belongs to the control system oscillation out of step, such as the system oscillation automatic decoupling device, automatic parallel device, etc.