Session 2 (System Aspects) Rapporteur: Hiroshi Okamoto (JP) 2 nd International Symposium on International Standards for Ultra High Voltage, New Delhi, India

1 Key issues in Session 2 System aspects of UHV technologies Standard voltage (highest voltage of equipment), Power system stabilities especially in the UHVAC/(U)HVDC hybrid systems, Insulation coordination, and Technical requirements and standardization aspects for equipment installed in the UHV network

2 Session 2 “ System Aspects ” 2-1 “1200 kV system parameters and status of development of substation equipment & transmission lines in India” 2-2 “Selection of the rated voltage for the UHV AC system in China” 2-3 “Analysis of overvoltages related to the UHV AC system”, China 2-4 “Stability research on the planned UHV power grid in China” 2-5 “Standardization aspects of UHV in AC networks”, IEC/TC17

3 Summary System aspects Standard voltage: 2-1(India) and 2-2(China) Overvoltage control: 2-1(India) and 2-3(China) Secondary arc extinction : 2-3 (China) Stability of UHVAC/(U)HVDC system: 2- 4(China) Technical requirements for equipment in UHVAC network Switchgear : 2-5 (IEC/TC17), 2-1 (India), 2-3 (China) Surge Arrestor : 2-1 (India), 2-3 (China)

4 System Aspects (1) In India, highest voltage and test voltage for equipment are determined for their first project expected in 2013/2014. Standard voltage: 1200kV SIWV: 1800kV LIWV: 2250kV, 2400kV In China, the first project will start its commercial operation in Standard voltage: 1100kV SIWV: 1800kV LIWV: 2250kV, 2400kV

5 System Aspects (1) Question 1 Are IEC/TC8 and IEC/TC28 proceeding with their work on necessary revisions in IS and IS to meet the urgent market needs in China and India? Are proposed revisions and work schedules in TC8 and TC28 consistent with the project considered in both markets?

6 System Aspects (2) In India and China, large scale UHVAC / (U)HVDC hybrid systems will be constructed. In this context, the dynamic security of the hybrid system will be one major concern of power system planners and operators mainly because of - the very large transmission capacity of UHV transmission and - interaction between UHVAC and (U)HVDC systems.

7 System Aspects (2) Question 2 Given the growing applications of UHVAC / (U)HVDC transmission technologies, there may exist some needs for standardization on the system design and operation guidelines of UHV transmission systems considering some stability control measures. What role should TC8 and TC115 play in the design and operating guidelines of UHVAC/(U)HVDC hybrid system?

8 Technical Requirements for equipment in UHVAC networks (1) IEC/TC17 will start standardization of switchgear for UHVAC networks, based on the report from CIGRE WG A3.22. Some technical requirements for UHV equipment will not be simply an extrapolation of those already defined in IEC standards up to 800kV, mainly because there exist some peculiarities in UHV AC network.

9 Technical Requirements for equipment in UHVAC networks (1) Question 3 Are there any other modifications or new items by SC17A or SC17C needed for China and India? Comments from both countries are welcome. What kind of peculiarities in UHVAC networks should be considered in the standardization process in TC17?

10 Technical Requirements for equipment in UHVAC networks (2) High performance metal oxide surge arrestor (MOSA) plays a pivotal role in insulation coordination of UHVAC network, as well as other countermeasures such as circuit breakers equipped with pre-insertion resistor, and shunt reactors directly connected to UHV lines.

11 Technical Requirements for equipment in UHVAC networks (2) Question 4 How were specifications of MOSA (Metal Oxide Surge Arrestor) determined in China? Residual voltage of MOSA with respect to highest voltage of equipment is determined to be lower in India than that in China, probably because the lower protection level is preferable from the viewpoint of overvoltage control. Are there any technical challenges in application of the lower protection level of MOSA?