基于自抗扰控制的直驱风电场次同步振荡抑制策略

Subsynchronous oscillation mitigation strategy based on ADRC forD-PMSGs based wind farm

近年来,我国西部地区频繁出现直驱风电场与弱交流电网之间相互作用引发的次同步振荡(SSO)问题。为解决该问题,首先从SSO发生机理出发,提出了基于自抗扰控制(ADRC)理论的直驱风电场SSO抑制策略。该策略针对直驱风机网侧换流器设计了ADRC控制器替换电流内环PI控制器抑制策略。然后,从数学形式上推导得ADRC控制器抑制机理是ADRC控制器通过实时估计与补偿直驱风电场接入弱交流电网产生的影响,阻断直驱风电场与弱交流电网之间的相互作用,从而达到抑制SSO的目的。最后,基于PSCAD/EMTDC仿真软件,建立基于PI控制器和ADRC控制器的直驱风电场接入弱交流电网的电磁暂态仿真模型,对比分析PI控制器与ADRC控制器对SSO的抑制效果。仿真结果表明,ADRC控制器不仅对SSO具有较好的抑制效果,且具有较强的鲁棒性与适应性。这也从侧面证明了直驱风电场接入弱交流电网引发的次同步振荡主导因素是直驱风机网侧换流器电流内环PI控制器。

Recently,the problem that SSO(SubSynchronous Oscillation)caused by the interaction between D-PMSGs(Direct-drive Permanent Magnetic Synchronous Generators)based wind farm and weak AC power grid frequently occurs in western China.To solve this problem,the SSO mitigation strategy based on ADRC(Active Disturbance Rejection Control)is firstly proposed,in which the mechanism of SSO is utilized.In this strategy,the ADRC controller is designed to replace the PI(Proportional-Integral)controller of current inner loop of grid-side converter for D-PMSGs.Secondly,the mitigation mechanism of the ADRC controller is theoretically derived.This ADRC controller can estimate and compensate the real-time impact of D-PMSGs based wind farm integrated in weak AC power grid,and hence can avoid the interaction between D-PMSGs based wind farm and weak AC power grid.As a result,the SSO is expected to be effectively mitigated.Finally,an electromagnetic transient simulation model with both PI and ADRC controllers is built on PSCAD/EMTDC,and the mitigation effect of the two controllers on SSO are analyzed and compared.Simu⁃lative results show that the ADRC controller not only effectively mitigates SSO,but also exhibits satisfactory robustness and adaptability.It also proves that the main factor of SSO in D-PMSGs based wind farm lies in the PI controller of current inner loop of grid-side converter for D-PMSGs.