Application of PRA methodology in Chongqing transmission system

Power system reliability is always one of the most important requirements in system operation and planning. For a long time, deterministic methods are widely used in system analysis, such as N-1 rule in transmission system static analysis, but the probability characteristics of the components failure have been ignored, and the risk of actual system can't been obtained exactly. Recently, large-range blackouts occurred frequently all over the world, especially in transmission system because of its numerous components and complex operation modes, which made the experts to worry about the effectiveness of the old methods, then a new way of assessing system risk is needed urgently. Probabilistic Reliability Assessment (PRA) Methodology firstly proposed by EPRI is a new method to perform risk-based reliability assessment. Unlike traditional deterministic methods, PRA Methodology calculates a measure of the probability of undesirable events and a measure of the severity or impact of the events, then combines them into a single reliability index - Probabilistic Reliability Index (PRI) and develops PRI program based on PRA Methodology. So far PRA Methodology has been widely accepted in North America and already been used by many utilities since 2001, but it hasn't been introduced into the domestic power system. In this paper, PRA Methodology is adopted to analysis Chongqing's transmission system of 2009, mainly including of system comprehensive analysis, connection section analysis, specific status analysis, danger point analysis, etc. The research conclusion can be applied to practical operation of the network to help electrical operator to finish their work, such as weak links location, influence range assessment and the optimal scheme choosing, then the system risk can be acquired quantitatively to provide technical support for leader decision and power system planning. This work has demonstrated that the PRA Methodology can address these new uncertainties and significantly improves the ability of conducting effective transmission operational planning.