The development of power grids and the application of new technologies for power grids, while promoting the development of relay protection technologies, have also increased the complexity of relay protection technologies, presenting greater challenges to traditional relay protection application methods and management methods.

On November 9, the 78th China Electronics Fair (CEF) was held at the Shanghai New International Expo Center. This is the annual event of the Chinese electronics industry. At this exhibition, many relay protection technologies and products were unveiled, showing the R&D achievements of the relay industry in recent years.

Statistics from relevant agencies show that China's relay industry has huge market potential. In 2008, the national industrial relays had a market capacity of 1.09 billion yuan. In 2009, the market capacity of industrial relays reached 1.16 billion yuan, and relays exported more than 38 million US dollars. In 2010, China's relay sales were about 1.6 billion US dollars. With the gradual implementation of the ten industry promotion policies, experts predict that during the “Twelfth Five-Year Plan” period, the required amount of the relays and the application fields will continue to grow and develop. The traditional electromechanical relays will grow at a rate of about 8%. The speed of development will remain at about 15%, and special relays will develop at a rapid rate of more than 20%.

Ultra high voltage relay technology is a challenge

The application of relays is quite extensive. In the power system, when the power system itself fails and endangers the safe operation of the power system, the relay protection device can issue a warning signal in time, or issue a trip command directly to the controlled circuit breaker to terminate the development of the fault. Reduce the damage to the power system components themselves and also meet certain specific requirements of the power system. Therefore, relay protection is called the first line of defense for the safe operation of the power grid.

However, the security and rapidity of power protection control are difficult to take into consideration. It has always been a worldwide problem that threatens the security of power grids. The two large-scale blackouts occurred in the United States were caused by relays; in China, before the 1990s, more than half of blackouts were caused by relay protection defects.

According to the academician of the Chinese Academy of Engineering and Professor Yang Qixun of North China Electric Power University, the development of power grids and the application of new technologies for power grids have promoted the development of relay protection technologies, and have also increased the complexity of relay protection technologies, and applied traditional relay protection methods. The management approach presents even greater challenges. The rapid increase of short-circuit current level requires a higher speed of relay protection; the application of DC transmission and series compensation technology requires technical breakthroughs in relay protection; compact lines, multi-circuit lines on the same pole, and high-voltage short-circuit lines in cities The emergence of a large number of them makes the configuration, setting and cooperation of relay protection more complicated. The development of power grid equipment and operation control technologies, such as digital substation research, application of unattended substations, and construction and operation of UHV power grids, will impose higher requirements on the technical performance of relay protection. It is necessary to study and propose new relays. Protection solution. The actual operation of the power grid and lessons learned from domestic and foreign power grid accidents indicate that failure of a single component of a single relay protection device or device may lead to power grid accidents, and the reliability of relay protection equipment still needs to be further improved.

UHV power grids have distinct features that distinguish them from ultra-high voltage power grids. At present, there are many technical difficulties in relay protection, such as the influence of capacitive currents on the protection characteristics of ultra-high voltage lines, the influence of submergence currents on reclosing, and UHV. Relay protection equipment such as electromagnetic compatibility. It is understood that at present China's relevant agencies have carried out a series of independent research and development work, and have achieved initial results.

Microcomputer protection is the development direction

The technological development of relay protection is inextricably linked with the development of technologies such as electronics, information, and communications. In the future, with the gradual improvement of electronic CT (Current Transformer) and PT (Voltage Transformer), and the further improvement of the IEC61850 standardization protocol, it can be foreseen that digital technology will be applied more widely. In China, there are 110 kV and 220 kV voltage-grade electronic CTs and electronic PTs that have been put into trial operation. The research and development of relay protection devices for electronic CT and PT will promote the development of relay protection technology and promote relaying. Changes in the protection of new principles, new technologies, and new applications have become new topics for protection researchers.

Yang Qixun believes that microcomputer protection is based on software protection, compared with the traditional transistor, integrated circuit protection, with a strong self-test function, high integration of protection features, stable operating characteristics, high reliability, low maintenance and other significant advantages. It represents the development direction of relay protection technology.

China's microcomputer relay protection research started in the late 1970s. In 1984, the first microcomputer line protection device in China was identified and applied in the system. After more than 20 years of development, domestic microcomputer protection technology has been continuously improved, and many achievements and patents have been achieved in terms of computer protection hardware, software, and algorithms. Four generations of microcomputer protection devices have been introduced, and all performance and operating indicators have exceeded imports. Products are in a leading position in the world. Domestic microcomputer protection has replaced transistors, integrated circuits and other protections, and has occupied a dominant position.

High barriers to industry

Electric power equipment is divided into primary equipment and secondary equipment. Primary equipment refers to the equipment that directly assumes the functions of generating electricity, transmitting electricity, substations, power distribution, and electricity, such as generators and transformers. The technical content is relatively low, and there are more domestic manufacturers. Intense competition. Secondary equipment refers to various equipment required for the normal operation of a primary equipment and the realization of power management objectives, such as generator set protection and dispatching automation systems. Compared with the same equipment, secondary equipment production has higher industry barriers. The industry's products bring together modern electronic technology, communication technology, computer and network technology, with high technical content and high added value, and are typically high. Technology industry. Although the relay industry in our country has achieved remarkable results after years of development, there are still only a handful of companies capable of producing secondary equipment in China.

Nanrui Jibao Electric Co., Ltd. is a key enterprise in China's relay industry. Through its technological innovation, it has broken the long-term monopoly of large foreign companies on the relay protection market in China in a short period of 10 years and has begun to occupy the market in advanced technology.

In the academic community, Nan Rui Int'l first proposed the principle of power frequency variation protection. Using this principle, it is possible to quickly identify the grid section where the accident occurred, and to protect the entire power grid from damage, and it is recognized that it has an international advanced level.

Nanrui Insurer will also focus on the control and protection of ultra-high voltage DC transmission that has long been monopolized by foreign electric companies. For the Gezhouba-Shanghai 500,000-volt DC transmission line reconstruction project, it provided the first domestic production and control DC protection system in China. Subsequently, in the first 750,000-volt power transmission demonstration project in China, Nanrui Jibao became the only one. Manufacturers that provide all protected products.

XJ Group is another key enterprise in China's relay industry. Its main industry is the development of power system relay protection automation. It has successively achieved many firsts in the field of power system relay protection research in China: Successfully developed China's first electrified railway system. Feeder protection device; Successfully developed China's first 500,000-volt EHV line protection device; Successfully developed China's first 600,000-kilowatt large unit protection device; Successfully developed China's first nuclear power plant (Qinshan Nuclear Power Station) relay protection device; China's first submarine cable DC transmission control protection system (Zhoushan Project) was successfully developed; China's first DC networked control and protection system (Lingbao back-to-back project) was successfully developed. For many technologies such as high-voltage direct current transmission control and protection systems, large-scale industrial automation information control system software, ultra-high voltage, ultra high voltage substation automation systems, etc., XJ Group has mastered complete independent intellectual property rights and has reached the international advanced or advanced level. In the field of relay protection for main equipment of power systems, XJ Group has become a leader in the development and operation of protection products for domestic computer generators.