Safety Level Analysis And Prevention Strategy Research Of Power Network Considering Chain Trip

With the rapid development of society and economy,people rely more and more on electric energy in their daily life,which leads to higher requirements for the safety,stability and reliability of power grid operation.In recent years,the frequent blackout accidents at home and abroad not only affect people’s normal life,the normal order of society,national science and technology security,but also cause huge economic losses.The accident research results show that the vast majority of blackout accidents are often caused by chain failures,which usually originate from a simple fault and are accompanied by chain trips in the development process.Therefore,chain failures are closely related to chain trips,and the early stage of chain failures is generally shown as chain trips.Therefore,it is of great significance to strengthen the research on chain trip for the safe operation of power grid.The main research work of this paper is as follows:(1)Chain of tripping process is discussed,combined with the action principle of relay protection to determine whether the grid in the mathematic expression of the trip chain,and the initial fault line after resection,remaining lines in power grid operation parameters and the relay protection setting value as the minimum electric distance between grid security level,the remaining line electric distance average as line operation level,And analyzes the factors that affect the safety level of the power network,and finally carries on the verification analysis in the simulation system.(2)The prevention strategy model based on safety level is determined.The strategy model takes the safe operation of the system as the premise,the active power output of the generator set as the variable,and the goal is to improve the safety level to the optimal level.In order to improve the calculation speed of the model,the selfadaptive penalty function is used to deal with the equality constraints and inequality constraints,and the prevention strategy model with constraints is transformed into an optimization model without constraints.(3)The sparrow search algorithm is used to solve the strategy model.The simulation results show that the prevention strategy model can improve the safety level of the power grid and the line operation level.It can not only make the power grid operate in a better state,but also enhance the ability of the power grid to prevent chain trip.(4)The algorithm was improved.Firstly,the population was initialized by Logistic chaos mapping to improve the diversity of the initial population and avoid the algorithm falling into local optimum in the early stage.Then,the inertia weight factor was used to improve the finders update formula,and finally,Levy flight strategy was introduced to perturb the individuals falling into local optimum early.The improved algorithm,the basic sparrow search algorithm,the particle swarm optimization algorithm and the tabu search algorithm are used to solve the prevention strategy model.The simulation results show that the improved sparrow search algorithm is more suitable for solving the model.