This paper introduces the development of 1 000 kV ultra high voltage transmission relay protection and monitoring technology in foreign countries, and puts forward some technical problems to be studied in this field. This paper presents a relay protection and monitoring system platform for substation based on IEC 61850 standard. This platform can adapt to the characteristics of UHV transmission and has strong real-time performance. It is an information platform that integrates relay protection, emergency control and system stability.
Key words: UHV transmission; Relay protection; Monitoring system; Power system
At present, China has formed a regional power grid connecting the northeast, northwest, North, East, central and southern regions. With the construction of large hydroelectric, thermal and nuclear power bases, the demand for long-distance, large-capacity high-voltage or ultra-high-voltage transmission is inevitable. In the grid now operating in our country, high voltage level of DC is ±500 kV, and high voltage level of AC is also 500 kV. In the next few years, 750 kV AC and even 1 000 kV AC and above voltage levels will appear. Therefore, it is necessary to conduct in-depth research on UHV power transmission and transformation technology, especially some key technical issues.

1 Current status and development trend of UHV transmission technology at home and abroad

From the foreign situation, the United States, Canada, Brazil, Venezuela and South Africa and other countries have AC 750 kV voltage level transmission lines in operation; Ekibastuz, Kazakhstan
The Kokchetav transmission line has a voltage class of 1 200 kV. It was put into operation in 1985. It is a single circuit, 900 km long and uses 8 split conductors A1/ST330/43.
The Italian electricity company Enel has built a 1 000 kV experimental single loop line near Pisa. But the Italian grid has so far failed to use this voltage level for transmission. From 1975 to 1979, the BPA Electric Company of the United States operated a high voltage 1 200 kV experimental line in Oregon, in order to study the environmental impact at this voltage level. But in BPA grid, this voltage level has not been used so far. Japan's Tokyo Electric Power Company is now building a voltage class of 1 000 kV, 287 km long AC double loop overhead line. The high working voltage of the transmission line is 1 100 kV, the large continuous current is 8 000 A, the natural capacity of each loop is about 5 000 MW, the double loop transmission capacity is about 13 000 MVA, the corridor width is still limited to 100 m, the height of the tower is about 110 m, the average interval of 549 m, the conductor phase spacing 9 m. Eight split wires and eight steel-core aluminum stranded wires, each with a cross-section of 610 mm2 or 810mm2, are arranged in octagonal shape, with an effective diameter of about 1 m. The electric field of this split wire is uniform and corona noise is small. Two overhead ground cables are used for lightning protection. Each overhead ground cable is equipped with five groups of six optical fibers. Each insulator assembly consists of 2 or 4 strings of 40 insulators each with a length of approximately 9 m.
We have done some basic preliminary research on the technology and equipment of power transmission and transformation above 500 kV. In order to cooperate with the bidding work of 750 kV system relay protection of Northwest Power Grid and provide necessary technical data for the design, operation and scientific research of 750 kV system relay protection, Northwest Power Grid Company entrusted the System Dynamic Mode Laboratory of China Academy of Electric Power Sciences to carry out the dynamic mode test of 750 kV system relay protection device. The lab is a dynamic modeling lab that can simulate a 750 kV system, It has carried out dynamic mode tests on 37 sets of relay protection products from 8 relay protection manufacturers, namely Nanrui Jibao, Sifang Jibao, Guodian Nanzi, Xuji Group, ABB, GE, ALSTOM and TMT&D in line protection, reactor protection, transformer protection and busbar protection, etc. The scale of the test is the second in China. It has received wide attention at home and abroad.

2. Research and development of relay protection and monitoring technology for UHV transmission abroad

(1) AREVA Corporation. Shanghai AREVA Power Automation Co., Ltd. was established in September 2001 as a joint venture between AREVA Group (holding 59%) and Shanghai Power Transmission and Distribution Co., LTD. (holding 41%), and acquired the power transmission and distribution division of Alstom SA. AREVA Power Automation Co., Ltd. and Tsinghua University have jointly established the Relay Protection and Control Research, a research established by AREVA Power Automation Co., Ltd. in China. The main task of this research is to carry out the research and technology development of the relay protection principle of UHV transmission lines, and develop the relay protection devices and other automatic devices suitable for uHV power system.
(2) Siemens AG. SIPROTEC series of microcomputer relay protection products provided by Siemens are suitable for high voltage power system and generator, which can not only control the high voltage primary equipment, but also display the measured value in real time, and realize the control by interval. The product has a complete interval database and a variety of protocol communication interface, users can analyze and manage their own protected data. The striking feature of SIPROTEC series microcomputer relay protection devices is that various functions related to secondary equipment can be integrated into a single device at each interval using artificial intelligence technology. SIPROTEC series microcomputer relay protection device can also be used as a component of SICAM substation automation system, in order to achieve the best configuration.
(3) GE Corporation. Although GE entered the Chinese market relatively early, its entry into the electric protection and supervision system products is relatively late. As a result, the performance of this product in the Chinese power users is less. GE company's high voltage substation relay protection product based on ALPS technology is highly adaptive. It is a multifunctional digital protection device with series compensation, single-phase trip, three-phase trip and reclosing lines can be selected.
(4) TMT&D Company. Different from other companies, TMT&D has no operating performance of primary equipment and relay protection products with voltage level of 1 000 kV and above, and certainly has no research and development, test, construction and operation experience of products with voltage level of 1 000 kV and above. Although its protection kind is complete, configuration mode and man-machine interface have great difference with our country.

3. Substation relay protection and monitoring system platform based on IEC 61850 standard

China Electric Power Research Institute has completed the preliminary experimental research of substation automation based on IEC 61850 standard, and has successfully developed the substation relay protection and monitoring system platform based on IEC 61850 standard. The system platform structure is shown in Figure 1.