Research On Cascading Failure Sequence Identification And Control Strategy Of AC/DC Hybrid Power Grid

With the planning and construction of UHV power grids and AC/DC hybrid systems,the topological structure of the power system is becoming increasingly large,and the operating conditions of the power grid are more complex.Partial faults of the power system are more likely to spread to the entire power grid through chain reactions,effectively guarantee The safe and stable operation of AC/DC hybrid power grid has important theoretical significance and practical application value.In order to avoid the occurrence of cascading failures in AC/DC hybrid power grids,this paper analyzes the development characteristics of cascading failures of AC/DC hybrid power grids,studies the prediction methods of cascading failure sequences and the control strategies to prevent cascading failures of AC/DC hybrid power grids.The main research contents are as follows:Based on the fault characteristics of the AC/DC hybrid power grid,this paper analyzes the system states such as DC commutation failure,AC bus overvoltage and line power flow overload.Considering the influence of the system grid structure and the coupling between AC and DC systems,the local topology,The four aspects of AC/DC influence,power flow operation and AC/DC connection relationship have established link prediction indicators that can characterize system failures,multi-infeed interaction factor indicators,weighted power flow entropy indicators,and multi-infeed short-circuit ratio indicators.In order to study the cascading failure sequence prediction of the AC/DC hybrid power grid,this paper uses the non-cooperative game theory idea to comprehensively assign weights to meet the cascading failure sequence analysis and prediction needs based on the constructed AC/DC hybrid power grid cascading failure characteristic index.The immune quantum particle swarm algorithm solves the non-cooperative game problem,and carries on the systematic risk assessment to the cascading failure sequence through the system load-loss degree and the severity of power flow crossing.Finally,the improved IEEE-39-bus AC/DC hybrid power grid and the actual system data of a certain province are used for simulation analysis.The simulation results verify the accuracy and superiority of the cascading failure sequence prediction.Aiming at the research on the control strategy of preventing the cascading failure of the AC/DC hybrid power grid,this paper establishes the objective function to minimize the generator adjustment,the sound DC line adjustment and the load adjustment as the objective function,and the power of the generator,load and line and the minimum safe voltage for constraint conditions,chaos-lightning search algorithm is used to solve the optimal control strategy.And on the power system comprehensive analysis software PSASP,the improved IEEE-39-bus AC/DC hybrid power grid and the actual system of a certain province were modeled and simulated,and the adjustment measures of the system control strategy were obtained,and the accuracy of the system voltage and power control strategy was verified.