Security Risk Assessment And Vulnerability Analysis In Electrical Power System

The security of electrical power system concerns the security of a nation, the stability of a society and people's daily life. With the development of the society, the electrical power system becomes much more huge and complex. Applications of new technology in electrical network also bring more uncertainties into power system's stability. With the fact that large area blackouts happened worldwide frequently in recent years, people have come to realize that traditional security risk assessment methods based on electrical network stability analysis is not adequate to guarantee the security and stability of electrical power system. Thus, with regard to the characteristics of China's power system, establishing new methods of objectivity, practicality and adaptability of security risk assessment, and on this basis, developing vulnerability research of power system are of great importance practically and theoretically.Firstly, recent research and main problems acquainted in the subject focused in this paper are summarized. On this basis, a new method of power system risk assessment and vulnerability analysis is proposed in perspective of application in engineering.By analyzing blackouts, this paper concluded the causes of outages into four main factors as power system structure, power network technology, electrical equipment and management in power system, using Fault Tree Analysis. A Four-class index system of power system risk assessment and vulnerability analysis is established, which is the basis of following work. The structure of the index system is illustrated in this paper.Allocation of index weight is the key problem in the power system risk assessment and vulnerability analysis. Because of the complexity of electrical power system, a lot of qualitative indices are included in the index system. Therefore, Analytic Hierarchy Process is introduced to allocate the weight of index. Several examples are illustrated to compare the influence of different scale to allocation result.Comparison matrix describes the relationship of indices. And the comparison's consistency degree determines the rationality of weight allocation. This paper first established the optimal model of comparison matrix's consistency problem. Genetic Algorithm is introduced to realize this optimization problem. Several cases are calculated, proving that this optimization method is effective.Vulnerability analysis is aimed to find out the vulnerability points of power system. The definition of power system vulnerability is explored in perspective of complex power system. With the result of power system security risk assessment, a new method of power system vulnerability analysis is proposed in this paper. This method uses Fuzzy Analytic Hierarchy Process, and takes the amount of indices into consideration. Using this method, a provincial electrical network of China is analyzed as a pilot.As a conclusion, review and summary are made. And the deficiencies of this paper are pointed out. Then, some work to be done in the future is also proposed.