Chinas Power System and Relay Protection Technique in Preventing Blackout for the World
Two large blackouts occurred in North India on 30 and 31, July 2012, and these two outages have increased the worldwide large Country blackouts (each with a power loss of over 8,000MW) from 23 to 25 incidents.The worlds largest blackouts usually occur through two stages:Stage one is related to voltage collapse/transient instability and the reason why most of the instability has occurred in the huge and complex configuration is because of the cascading trips by impedance relays due to load transfer initiated by a single disturbance and the heavy load superimposed to the long distance/high impedance circuits.Stage two is that the transient instability may spread out to blackout due to cascading trips by impedance relays of transmission lines and out-of-step relays of the Generators operating during the system instability.Two different strategies exist on how to handle system transient instability:The first strategy is from the North American NERC Planning Standards (1997), where the standards state thatGeneration and transmission protection systems should avoid tripping for stable swings on the interconnected systems. This means that the operations of the relay protection and subsequent tripping of the generation and transmission systems are permitted during transient instability.The consequential results are blackouts.The second strategy is from the rule of Power System Security and Stability Criteria issued in China in 1981.The China criteria firstly stipulates for the generation and AC/DC network infrastructure that the segregation of large interconnection by HVDC links ; radioactive connection between high and low voltage network ;and single generation point to load centerand <avoid overload cascading trips of transmission lines> by relay protection/automation technology to prevent transient instability.Secondly, even when instability occurs, avoid relay protection cascading tripsof all the transmission lines and most of the generators to prevent blackout, as re-synchronization of the whole system can be restored within a short time.Therefore, China (except Taiwan) has prevented large blackouts.This China power system infrastructure and relay protection design is based on close examinations of blackouts that have occurred all over the world.The study concluded that The cause of cascading blackouts was the un-controlled power system infrastructure and relay protection. Thus for 35 years of implementing the Stability Criteria —— building proper AC/DC system infrastructure and better qualified relay protection to keep system integrity,system transient instability may occasionally occur, but it could not cascade to widespread blackout.
Blackout Collapse Stability System infrastructure Trips by protection
Dingzhong Meng
China Electric Power Misistry and CIGRE & IEEE
国际会议
南京
英文
252-260
2015-09-21（万方平台首次上网日期，不代表论文的发表时间）