Research On Control Method Of The Dual Side Converter In Stand-alone Power Generation System Based On Brushless Doubly-fed Machine

Shaft generator technology can reduce diesel fuel consumption,improve energy efficiency and reduce electricity costs by using the redundant power for ship power generation.This way of power generation belongs to the variable speed constant frequency(VSCF)power generation.Brushless doubly-fed machine(BDFM)has great advantages in the field of VSCF power generation.Generator system which consists of BDFM has high reliability and maintainability by using power converter of small capacity and omitting the brushes and slip rings.Based on this,this paper focus on BDFM stand-alone power generation and study how to ensure power generating quality through reasonable control strategy in the situation of ship rotational speed variation and load change.This paper establishes the system structure composed of prime mover,BDFM and DualPWM converter and separately studies the control method of control-winding side converter(CSC)and power-winding side converter(PSC).As for the control method of CSC,this paper analyzes the operation principle of BDFM firstly.In order to decouple the parameter variables of control windings and power windings,double rotor speed d-q model of BDFM is established.And then double synchronous speed model is derived,in which the parameter variables is transformed into DC variables.Based on double synchronous speed model,this paper proposed a stator field oriented vector control strategy,through which accurate control of generation voltage and good dynamic response performance of variable operating conditions is realized.As for the control method of PSC,this paper introduces the direct power control(DPC)strategy to achieve quick dynamic response.The important content of DPC is analysed,including hysteresis control and virtual flux technology.And in order to inherit the advantages of DPC and avoid the weakness of it,a new direct power control strategy with fixed frequency based on PI regulators is proposed.In Matlab/Simulink environment the new strategy is contrasted with several common control method,which is proved to have low input current harmonic distortion rate,good dynamic response and small steady wave motion of bus voltage.Finally,hardware circuit is designed and an experimental platform is built in view of PSC.This paper designs software based on the direct power control strategy with fixed frequency based on PI regulators.And then relevant experiments are carried out,which confirm the practicability and the advantage of this strategy.