静止变频器分阶段启动控制策略研究

Start-up control strategy of static frequency converter in stages

静止变频启动方式作为抽水蓄能机组的主要启动方式,具有启动电流可控、可频繁启动、调速范围宽等优点。转子处于低速状态时,根据机端电压计算出的转速不准确,造成传统控制方法输出的电磁转矩误差较大。针对此问题,文中首先基于同步电机静止变频系统工作原理,提出一种改进型静止变频器(SFC)控制方法。在低速阶段,整流电路采用触发延迟角开环控制,使SFC持续提供充足的加速转矩,转子能够按照一定的加速度上升,逆变电路采用前馈和反馈控制,使直流电流快速上升并维持稳定;在高速阶段,整流电路采用触发延迟角双闭环控制,逆变电路采用负载换相法实现换相。然后,文中提出闭环控制器参数设计方法,提高直流回路稳定性以及静止变频系统动态性能。最后,通过仿真验证了所提控制策略及参数设计方法的有效性。

As the main starting mode of pumped storage unit,the static frequency conversion starting mode has the advantages of controllable starting current,frequent starting and wide speed regulating range.When the rotor is in low speed state,the speed calculated according to the terminal voltage is not accurate.So the output electromagnetic torque error is large with the traditional control method.Firstly,the working principle of the static frequency converter system of synchronous motor is introduced.Then an improved control method of the static frequency converter(SFC)is put forward.In the low-speed phase,the open-loop control of the trigger delay angle is adopted in the rectifier circuit,so that the SFC can continuously provide sufficient acceleration torque,and the rotor can rise according to a certain acceleration.Feedforward and feedback control are adopted in the inverter circuit to make the direct current(DC)current rise rapidly and maintain at a certain level.In the high-speed phase,the double closed-loop control rectifier circuit is used to trigger the delay angle,and the inverter circuit uses the load commutation method to realize the commutation.The parameter design method of the closed-loop controller is also given,which improves the stability of the DC loop and the dynamic performance of the static inverter system.Finally,the correctness and effectiveness of the control strategy are verified by simulation.