Mr. Luu Viet Tien, Deputy General Director of the National Power Transmission Corporation (EVNNPT)
Mr. Luu Viet Tien, Deputy General Director of the National Power Transmission Corporation (EVNNPT) shared about new features in Thuy Nguyen 220kV substation and the digitalization plan of substations managed by EVNNPT.
- "Digital substation" sounds very interesting and in line with the digitalization trend. So what differences can be seen in comparison with other substations, sir?
- Thuy Nguyen 220kV substation is equipped with Siemens computerized protection and control system with many different features. They are the process bus LAN using fiber optic cables according to the IEC 61850-9-2 substation communication network architecture to connect Siemens protection and control devices (such as transformer differential protection (F87T) 7UT86, line differential protection (F87L) 7SL86, distance protection (F21) 7SA86, bay control unit (BCU) 7SJ85, etc.) to 6MU65 devices (including Merging Units (MU) and I/O (Breaker IEDs)).
The 6MU65 devices include MU converting analog signals from voltage transformers and current transformers together with time synchronization signals into digital signals to provide protection and control devices, I/O sets (Breaker IEDs) for exchanging status signals, receiving commands to switch circuit breakers and disconnectors according to the IEC 61850-9-2 protocol.
By equipping Process Bus using fiber-optic cables and MU, I/O (Breaker IEDs), the investment in Thuy Nguyen 220 kV substation reduces about 80% of copper cable volume, reducing costs of transportation, construction and installation of copper cables, reducing the area of cable ditch thanks to using copper cables only to connect from voltage transformers, current transformers, circuit breakers, disconnectors to 6MU65 devices including MU and I/O (Breaker IEDs). The connection from 6MU65 to protection and control devices by fiber-optic cables on the process bus LAN is in line with the IEC 61850-9-2 communication protocol, which reduces the space to install protection and control devices by not using common I/O and reduces the risks of short circuit failures of copper cables.
However, to achieve such advantages as an ideal digital substation, manufacturers need to commercialize voltage transformers, current transformers integrated with MU and circuit breakers, disconnectors integrated with I/O (Breaker IEDs). In other words, all of the current, voltage, and state signals of the equipment need to be digitized and fiber-optic connected from measuring equipment, switchgear to protection and control equipment. Then it will completely reduce the number of copper cables, save costs and alleviate risks of incidents related to copper cables. The above digital substation solution does not differ much from the solution of installing protection and control cabinets outdoors or indoors Bay Housing considering the efficiency of copper cable reduction.
- It seems that this is a new technology in Vietnam...
Digital substation is not only new technology to Vietnam but also to advanced countries in the world. EVNNPT has held many seminars with major companies in the world such as Siemens, ABB, GE, etc. on the digital substation, however, the number of 220kV substations with the same scale as Thuy Nguyen 220kV substation (with 12 220kV feeders, 20 110kV feeders and two 220kV – 250MVA transformers) using digital substation technology are very few.
During the investment process and operation of Thuy Nguyen 220kV substation, EVNNPT will review and analyze the advantages/disadvantages, benefits/costs, investment efficiency of the digital substation to serve as the basis for deciding on the selection of substation protection and control technology in the future.