| Tropical cyclones have frequently landed in the eastern coastal provinces of ourcountry in recent years, which has posed a significant threat to the safe and stableoperation of power grids in coastal areas of our country. Severe tropical cyclonenatural disasters may lead to plenty of power equipment damage in coastal areas in ashort period of time. For this reason, it’s very necessary to analyze quantitativelyimpacts that tropical cyclones have on grid reliability taking characteristics of windfield distribution of a tropical cyclone into consideration. Therefore, overheadtransmission lines are chosen as the research object, and the related issues, such asthe calculation of wind pressure of transmission lines caused by tropical cyclones,the calculation of failure probability of transmission lines caused by tropicalcyclones and the generation of fault set, are discussed in this dissertation from theperspective of the relationship between tropical cyclones and clusters oftransmission line failures, and impacts that tropical cyclones have on transmissionlines of grid are analyzed quantitatively, and the dynamic fault set of grid linesinfluenced by the tropical cyclone is eventually obtained.Firstly, on the basis of previous studies, an approach to solve the wind field of atropical cyclone based on the multi-model ensemble is proposed. The approach isbased on the characteristic that all models include a common parameter of maximumwind speed radius, and parameters of each model together with weight coefficientsby which distributions of wind fields of different models are combined are optimallycalculated with a method of multi-layer iteration and dynamic weighting by usinginformation on a tropical cyclone released by the meteorological center. Then, onthe basis of calculation of tropical cyclone wind field, values of wind pressurewithstood by the unit span are calculated according to the present design standardadopted by our country, and the tropical cyclone Haikui is taken as an example toanalyze the changes of values of wind pressure withstood by the unit span during themotion of tropical cyclone wind field, and periods of time during which wire breakmay occur are identified by comparing values of wind pressure withstood by the unitspan with its design value.Secondly, the curve that describes the relationship between the failure rate ofthe unit span and its value of wind pressure is built. Then, Failure rate of the unitspan and its failure probability in the time window selected are calculated accordingto the real-time information on values of wind pressure withstood by the unit span.The whole transmission line is considered as a serial reliability system which iscomposed of several spans, and the failure probability of the whole transmission line is calculated according to the formula of the serial reliability system. Further, faultstates are selected by setting a threshold value for probability of fault states orlimiting the level of fault states, and fault states which meet the requirements aresorted, and the method with which fault sets are generated is provided.Finally, a test system which simulates the power grid in coastal areas is built,and impacts which tropical cyclones with different intensity have on thetransmission lines of power grid in coastal areas are simulated. Results show that,the tropical cyclone with low intensity has a mild effect on the grid, and it may onlylead to single-line faults in a small number of time windows; in contrast, the tropicalcyclone with high intensity is very likely to result in clusters of transmission linefailures in the grid. In the case of the tropical cyclone with high intensity which maylead to clusters of transmission line failures, fault states are selected with a methodof setting a threshold value for probability of fault states, and then fault statesselected are sorted, and eventually dynamic fault sets are generated.This research is supported by State Grid Corporation of China (SGCC)(NO.SGCC-MPLG-023). |
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