Implementation Electromechanical And Electromagnetic Hybrid Simulation For Power System Using PSCAD/EMTDC

In recent years,with the rapid development of modern electronics technology, manynew power electronic devices such as HVDC and FACTS devices have been widelyapplied in power system. With the usage of these devices which can provide rapidresponse in a system disturbance, power system operation and control has becomemore complex than ever. It is necessary to study effective simulation methodologiesfor power systems including such equipments for improving the system stability andsecurity.In transient stability program (TSP), HVDC and FACTS devices are represented byquasi steady state models;hence the rapid transient responses of HVDC and FACTSdevices cannot be simulated in detail. On the other hand, electromagnetic transientprogram (EMTP) can provide detailed simulation of the devices throughtime-consuming computation. For large power systems, the computation burden andstorage requirement in EMTP would become serious problems. Conventionally, alarge power system has to be reduced to an equivalent system model beforeperforming electromagnetic transient simulation.To overcome the disadvantage of both TSP and EMTP, new methods called hybridsimulation algorithms have been developed. The whole power system is divided intotwo subsystems according to different research interests: the detailed subsystemincluding HVDC or FACTS devices and external subsystem. These two subsystemsare simulated separately with different model representations. As TSP utilizesrelatively larger integration time-step (usually 0.02 second) than that of EMTP, whichtypically requires time-step of 50 microseconds, the hybrid algorithm has higherefficiency in computations and requires less computer storage than EMTP. The hybridapproach can also simulate the fast response in three-phase waveform for HVDC orFACTS devices. But these methods need constructing the model of HVDC or FACTSand their controllers in the simulation program and writing a lot of codes by users.Lack of flexibility and generality, the conventional hybrid simulation algorithms haveto write different programs for different devices and their controllers.According to the disadvantage of conventional hybrid simulation algorithms, a newhybrid simulation algorithm using commercial software PSCAD/EMTDC is proposedin this paper. The new hybrid algorithm embeds an in-house transient stabilityprogram to EMTDC main program by the user interface of EMTDC. HVDC andFACTS devices are constructed using the components of PSCAD under graphicenvironment, and simulated by EMTDC in detail. The outside AC power system issimulated with traditional transient simulation program. The 3-generator 9-bus IEEEpower system including SVC is tested to demonstrate the effectiveness of the newhybrid simulation algorithm. By comparing the simulation results with those of EMTP,it is clearly show that the new hybrid simulation algorithm can effectively simulatethe rapidly transient response of SVC both in voltages and currents. The new hybridalgorithm proposed in this paper provides a useful tool for studying dynamicperformance of other FACTS devices and HVDC system.