Studies On Power System Mid/Long-Term Hybrid Simulation Model And The Switching Criteria

Time domain simulation analysis is the basic method to study the mid/long-term stability problem of power system.This paper uses time domain simulation method to analyze the mid/long-term stability of the power system.First,the principles and the applicable models of the three time domain simulation methods are introduced in detail,i.e.,the full time domain simulation method(FTS),the quasi-steady state simulation method(QSS)and the hybrid simulation method(FHD?FTS-QSS).The FTS method uses detailed model of each component,and the simulation results are the most accurate,but it is time-consuming.The QSS method uses the quasi-steady state model,the simulation speed is fast,but the accuracy is impaired.The FHD method combines the two simulation methods mentioned above,by employing appropriate model switching criteria,it can exhibit great advantages.Second,based on the conventional frequency-based switching criterion used in the hybrid simulation model,this paper makes an in-depth study and optimizes the frequency criterion with an additional delay.The more optimized criterion is applied to the IEEE 5-machine 14-bus system and the New England 10-machine 39-bus system.The result is compared and analyzed,taking the result obtained by full time domain simulation as the reference.Finally,the simulation results show that,the hybrid simulation using the frequency criterion with an additional delay is more efficient than the FTS simulation and more accurate than the QSS simulation.Taking both the efficiency and the accuracy into account,the summarized criterion is effective.And the optimized delay criterion is more efficient than the traditional delay criterion.The simulation results also show that,if the allowable value in the criterion is too large,the discrete component will result in malfunction.In addition,if the allowable value in the criterion or the simulation step size is unreasonable,the FTS model cannot be switched to the QSS model.By adjusting the parameters including the allowable value,delay time and the simulation step size,the range of appropriate allowable value for the 14-bus system and the 39-bus system are found and the first model switching time are given.