双馈风电场抑制系统次同步振荡分析及控制策略

Analysis and Control Strategies for Depressing System Sub-synchronous Oscillation of DFIG-based Wind Farms

为挖掘大容量风电场参与系统次同步振荡的抑制能力,提出双馈风电场抑制系统次同步振荡的机理研究及其附加阻尼控制策略对比分析。首先,建立汽轮发电机轴系多质量块的数学模型,引入风场输出功率与汽轮发电机转速之间的传递函数,推导了双馈风电场有功功率和无功功率调节对系统阻尼系数的表达式,并分析提供正阻尼的范围。其次,基于汽轮发电机转速信号以及系统正阻尼条件,对比例积分微分相位补偿控制环节及其参数进行优化,分别研究基于双馈风电场有功功率或无功功率环的附加阻尼优化控制策略。最后,以含双馈风电场的IEEE第一标准测试系统为例,对基于有功功率和无功功率附加阻尼优化控制策略的次同步振荡效果进行比较。理论分析和时域仿真结果表明,推导的基于风电场有功功率和无功功率的阻尼系数表达式可有效分析双馈风电场对系统次同步振荡的作用机理,且基于风电场的有功功率或无功功率附加阻尼优化控制策略都能在全次同步频段内提供有效正阻尼。

In order to discover the control capability of large-capacity wind farms depressing power system sub-synchronous oscillations（SSO）, the mechanism of doubly-fed induction generator（DFIG） based wind farms for damping SSO and ancillary damping control strategies were investigated. Firstly, the multiple mass-lumped models of turbo-generator shaft was built, then the transfer functions between turbo-generator speed and wind farms output power were introduced, the expression of the DFIG-based wind farms active/reactive power for the damping ratio and damping effects on the power system was derived, and the condition of the positive damping was obtained respectively. Secondly, the phase compensation parameters of the proportion integration differentiation（PID） controller were optimized to achieve the goal of providing effective damping in the whole sub-synchronous frequency band, the additional damping control strategies based on the active/reactive power loop of DFIG was investigated. Finally, taken the IEEE first benchmark model integrated with DFIG wind farms as example, depressing SSO performances were compared by using the optimization strategies of the active/reactive power additional damping control. Theoretical analysis and simulation results show that this derived damping factor expression of the active/reactive power can effectively analyze their impact on the system sub-synchronous oscillations of DFIG based wind farms, and the proposed wind farms active/reactive power additional damping optimal control strategies are valid over the whole sub-synchronous frequency band.