The Influence Of Large-scale Direct-drive Fan Access On The System's Transient Power Angle Stability

With the rapid development of the power system,the scale of the power system increases year by year,and a large number of new energy sources are connected,making the study of the transient stability of the power system become more complex.The access of large-scale direct draught fan(D-PMSG)makes the power system containing only traditional synchronous generator set changed.Therefore,it is necessary to analyze the transient stability of power system.The direct drive fan,as a kind of fan widely used,has some influence on the safe operation of the system because of its characteristics in normal operation,during fault and after fault removal.Based on the analysis of the characteristics of large-scale direct-driven fans in the transient state of the system,the influence of large-scale direct-driven fans on the transient power Angle stability of the system is studied in this paper.The electromechanical transient equivalent model of direct drive fan is established.Through the simulation software BPA to simulate the active and reactive power output of the direct drive fan under three different operating states,the direct drive fan is equivalent to different electrical models,and then the model of the power system including the direct drive fan is established.Set up with the expansion of the straight drive fan,the mathematical model of single machine infinite system,based on the system normal,after resection of three kinds of fault and the fault under the running condition of node admittance matrix,using WARD equivalent method expunction intermediate nodes,and infinity system only keep synchronous generator node,calculate the equivalent impedance between synchronous generator and infinity system.Based on the simplified dc power flow model,the analytical formula of power Angle difference after wind power is connected is derived in detail,and then the variation trend of power Angle difference with the three influencing factors of fan access proportion,fan access position and fault position is analyzed quantitatively in theory,and the influence rule of the three influencing factors on transient power Angle stability is summarized.Simulation models of extended single-machine infinite bus system and multi-machine system with direct drive fan were established in BPA to verify the correctness of the theoretical analysis method.In the expansion of the straight drive fan single-machine infinite system,according to the area of law is derived in detail such as the straight drive fan system after removal of the Angle limit access to the analytical,and quantitative analysis in theory Angle limit resection with fans access ratio,fans access and fault location change trend of three influence factors,such as summary of the above three kinds of influence factors on the influence law of system transient Angle stability.Based on the simulation model of extended single-machine infinite bus system and multi-machine system with direct drive fan,the simulation verifies the correctness of the theoretical analysis method.