The Complex Power Grid Critical Line Identification And Ice Melting Decision Making Model In Extreme Freezing Disaster

In recent years,China’s social and economic development is in a rapid stage,and the transmission of electricity from west to East has risen to a national strategic project,resulting in the rapid growth of power grid scale from the western energy export provinces to the eastern economically developed provinces.At the same time,the impact of global warming has led to extreme freezing disasters on transmission lines in the southern region more frequently than before.At present,the critical line identification model of complex power grid under extreme freezing disaster only considers one fault,but does not consider the problem of secondary cascading failures,and cascading failures are analyzed only from line power change or network topology structure unilaterally.Although some ice-melting decision models consider line importance constraints,the evaluation index is too simple,and only consider some important power output and high level.Voltage and UHV transmission lines.Aiming at the problems in these aspects,this paper proposes a critical line identification and ice melting decision model for complex power grid under extreme freezing disaster,and achieves the following research results:1)A critical line analysis model of complex power grid under extreme freezing disaster is proposed.The model first uses Monte Carlo method to analyze the primary fault vulnerability of transmission lines caused by extreme freezing disasters,and then disconnects the lines with high primary fault vulnerability in turn.Based on self-organizing criticality theory and power flow mediator method,the secondary fault vulnerability is analyzed and fused from two aspects of line power and topology structure.Based on the simulation of the IEEE-39 bus power system,the critical lines of the power grid are identified and the importance of the lines is classified through the joint ranking of the vulnerability of primary and secondary faults.2)A multi-constraint decision-making model for ice melting considering the importance of lines is proposed.The objective function of the model is to minimize the expectation of load removal,and the main constraints are the importance of line and the importance of ice melting determined by ice thickness prediction.Particle swarm optimization(PSO)algorithm is used to output the optimal decision of ice melting.The simulation results show that,under the premise that the icing thickness of the line in each period of the whole icing cycle does not exceed the limit value,the proposed scheme has higher reliability of the power system and reduces the risk of excessive icing thickness of important lines.3)Based on matlab/GUI,a critical line identification and ice-thawing decision system is built,which can quickly and accurately identify the critical lines of complex power grid under extreme freezing disasters,and optimize the ice-thawing decision-making according to meteorological forecast and line importance data output,which proves the real-time and effectiveness of the system,and provides a convenient visual operation interface for power grid operators.