Development direction and characteristics of relay industry

　　With the gradual implementation of ten industrial revitalization policies, the demand and application fields of relays in China will continue to grow. The traditional electromechanical relay will grow at a speed of about 8%, the development speed of solid state relay will remain at about 15%, and the special relay will develop rapidly at a speed of more than 20%.According to statistics, China's relay industry contains huge market potential, and China's relay industry has the following development direction and characteristics.
　　
　　Has the high industry barrier characteristic

　　Power equipment is divided into primary equipment and secondary equipment. Primary equipment refers to the equipment that directly undertakes the functions of generation, transmission, transformation, distribution and consumption, such as generators and transformers, etc., with low technical content, many domestic manufacturers and fierce competition.Secondary equipment refers to all kinds of equipment needed for the normal operation of primary equipment and the realization of the management goal of electricity, such as generator set protection and dispatching automation system.Compared with the same equipment, the production of secondary equipment has higher industry barriers. The products of this industry are a collection of modern electronic technology, communication technology, computer and network technology, with high technical content and high added value, which is a typical high-tech industry.Although China's relay industry has achieved remarkable results after years of development, there are still few domestic enterprises capable of producing secondary equipment.

　　Microcomputer protection is the development direction

　　The development of relay protection technology is closely related to the development of electronics, information and communication technology.In the future, with the gradual application of electronic CT(current transformer) and PT(voltage transformer) and the further improvement of THE IEC61850 standardization protocol, it is foreseeable that digital technology will be more widely used.Domestic 110 kv, 220 kv voltage class of electronic type CT, electronic PT put into trial operation, research and development applicable to electronic CT and PT relay protection equipment, will promote the development of relay protection technology, drive the new relay protection principle and application of new technology and new change, become a new subject in front of the researchers of relay protection.

　　Microcomputer protection is realized by software. Compared with the traditional transistor and integrated circuit protection, it has obvious advantages such as strong self-test function, high integration of protection function, stable action characteristic, high reliability and small maintenance amount, which represents the development direction of relay protection technology.

　　The research of microcomputer relay protection in China started at the end of 1970s.In 1984, the first microcomputer line protection device passed the appraisal and was applied in the system.After more than 20 years of development, the domestic computer protection technology has been constantly improved, in the computer protection hardware, software, algorithm and other aspects have obtained a lot of achievements and patents, has launched four generations of computer protection devices, the performance and operational indicators have been fully beyond the imported products, in the leading position in the world.Domestic microcomputer protection has replaced the transistor, integrated circuit and other protection, occupies a dominant position.

　　Uhv relay technology is a challenge

　　According to Yang Qisun, academician of Chinese Academy of Engineering and professor of North China Electric Power University, the development of power grid and the application of new power grid technology not only promote the development of relay protection technology, but also increase the complexity of relay protection technology, posing a greater challenge to the traditional application and management of relay protection.The rapid increase of short circuit current level requires the relay protection to have higher rapidity.The application of DC transmission and series compensation technology requires a breakthrough in relay protection technology.The configuration, setting and coordination of relay protection are more complicated due to the appearance of compact lines, multi-loop lines with the same pole and short lines with high voltage in cities.The development of power network equipment and operation control technology, such as the study of digital substation, the application of unguarded substation, the construction and operation of UHV power grid, will put forward higher requirements for the performance of relay protection technology, and new relay protection solutions need to be studied and proposed.The actual operation of power network and the lessons of power network accidents at home and abroad show that the fault of a single relay protection device or a single component of the device may lead to power network accidents, so it is still necessary to further improve the reliability of the relay protection equipment.

　　However, uHV power grid has significant characteristics different from UHV power grid. At present, there are many technical difficulties in relay protection, such as the influence of capacitive current on protection characteristics of UHV ultra-long lines, the influence of potential power supply flow on recirculation, and the electromagnetic compatibility of UHV relay protection equipment.It is understood that China's relevant institutions have carried out a series of independent research and development work, has achieved phased results.