Risk Assessment And Prevention Control Based On Fault Chains

Recent years,the development of power system in our country made great progress.With the development of ultra-high voltage direct current transmission and the global energy international,China has finished interconnection of power grids expect Taiwan,we have stepped into ultra-high voltage and large power grid era.On the one hand,the connection of the multistage grid made the remote transmission of trans-regional electricity came true,and made great economic benefits.On the other hand,the security of the whole power grid has confronted a big threat,which has proposed a new challenge to the steady operation of power grid.Since the last century 80's,there have many blackouts occurred domestic and overseas,it has caused economic losses,panic as well.So we must take measures to research the development mechanism of cascading failure and the prevention and control.Firstly,a integration information platform is established,which provide date to the generation of subsequent fault chain and risk assessment.The Cyber-Physical Systems(CPS)is integrated into this platform to make the date more comprehensive,which provides a visual interface to the dispatcher and makes the information retrieval more favorable to get.Secondly,The fault chain model are established based on the mechanism of cascading failure in this thesis.The initial segment of element is determined by the Monte Carlo simulation method,and the intermediate link of the accident is determined according to the importance degree of probability and the importance of structure,and then the fault chain sets is generated.With this method,the combinatorial explosion problem in cascading failure analysis is solved.Thirdly,the concept of risk is introduced in this thesis.Using the Markov method to calculate the probability of the occurrence of the fault chain,and according to economic and safety to assess the consequences of the fault chain.In this thesis,the power generation enterprise economic loss,transmission enterprise economic loss,business users economic losses,overloading or overload consequences,the voltage offset and frequency offset consequences are classified for grading into respective range,and consider multi risk state,and finally,the fault chain risk level can obtain for taking the probability and risk level,consequences of risk rating,as well.Finally,on the basic of obtaining fault chain sets and risk index,the game theory is introduced to preventive control the cascading failures.This method takes the fault party as the "virtual person",the power grid dispatch as a "natural person",so the prevention of cascading failure performance as the zero-sum game between the "virtual person" and"natural" person".In this thesis,the specific defense strategy of dynamic game is given,and the solution of the game is given as well,and preventive control strategy is obtained by solving the dynamic game theory.