| In recent years,typhoon disasters have caused many blackouts worldwide,making serious losses to the national economy and human life.These blackouts have exposed the difficulty of traditional reliability-constrained transmission grid planning methods to deal with extreme disasters such as typhoons.Under this concern,building a highly resilient transmission grid with strong anti-disaster ability has also become a new trend in today’s transmission grid planning and construction.At present,research on the resilience of transmission grids has received great attention from domestic and foreign electrical scholars,but the related research on the assessment and improvement of transmission grid resilience for planning is not deep enough.In response to this problem,based on the existing research results in the field of resilience assessment of power systems,this thesis has carried out research work in three aspects: the impact mechanism of the evolution of typhoon disasters on the transmission grid,resilience assessment methods,and resilience enhancement methods for planning needs.The main content and research results include:(1)A transmission grid resilience assessment method that takes into account the temporal and spatial effects of a specific typhoon disaster is proposed.First,the Batts typhoon wind field model is used to simulate the temporal and spatial evolution of a specific typhoon disaster and obtain the wind speed changes of the corresponding lines and towers of each transmission branch.The transmission branch vulnerability model is then used to reflect the failure probability of the transmission branch and the typhoon wind speed,which calculates the failure probability of the transmission branch considering the temporal and spatial effects of typhoon disasters.Based on the impactincrement based state enumeration method,a transmission grid resilience assessment method is proposed.The transmission failure state set is constructed,using the corrected failure probability of each failure states and the corresponding impactincrement,which quickly calculates the resilience of the transmission grid under the influence of a specific typhoon disaster.(2)On account of the uncertainty of typhoon disasters,a rapid assessment method for the resilience of transmission grid is proposed.First,based on the probability distribution of key typhoon parameters of typhoon wind field model within the transmission grid area,an uncertainty model of typhoon disasters is established to simulate the typhoon scenarios that may occur during the planning period.Combined with the resilience assessment under the influence of a specific typhoon method,a planning-oriented transmission grid resilience index and an evaluation method are proposed.An independent failure state reduction method is developed based on branch breaking distribution coefficients to reduce the dimensionality of large numbers of failure states that may occur under each typhoon scenario,which efficiently calculates the planning-oriented transmission grid resilience index with the sensitivity approach.(3)A planning-oriented method weak links location method and a resilience precision promotion method are proposed.First,based on the transmission grid resilience index by considering the uncertainty of typhoon disasters,a transmission branch resilience index is proposed.This index reflects the impact of any transmission branch failure on the overall resilience of the transmission grid and can be used to locate weak points in the transmission grid.A precise enhancement method for the weak links is proposed,including measures such as strengthening transmission branches and adding redundant branches.By improving the design standards or redundancy of weak links,the overall resilience level can be enhanced in a precision way.Finally,a modified resilience index method based on local parameter changes is proposed,which can quickly evaluate the enhancing effect of the resilience enhancement plan. |
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