基于改进动态潮流的DFIG风电系统层级频率模型预测控制

Hierarchical frequency control for a power system with DFIG based on frequency prediction with improved dynamic power flow

电力系统原有同步发电机(SG)负责的调频可由双馈感应发电机(DFIG)提供。评估调频效果时,相较详细时域仿真分析,可采用动态潮流(DPF)算法减少运算量。提出包含上层频率预测与下层DFIG控制的层级频率控制。双层控制中皆引入模型预测控制(MPC),通过预估控制效果确定控制目标。上层控制在DPF中引入SG调速器,以提升频率预测精度,基于此确定DFIG有功参考值,在其中计及了DFIG机械暂态的变化率约束。下层控制提出采用基于MPC的直接转子电流控制,追踪调频过程中的DFIG有功参考值,并在频率预测中计及其控制响应。

The frequency regulation previously undertaken by Synchronous Generators(SGs)may be provided by the Doubly-Fed Induction Generator(DFIG).To estimate the control effect,Dynamic Power Flow(DPF)is used to save the calculation effort of the detailed time domain analysis.A hierarchical frequency control with the upper level of the frequency prediction and the lower level of the DFIG control is proposed.Model Predictive Control(MPC)is applied to both levels to determine the control target with pre-evaluation of the control effect.At the upper level,the governor of the SG is included in the DPF to improve the accuracy of the frequency prediction,based on which the active power reference of the DFIG is determined.The mechanical transient of the DFIG with the change rate constraints is included.At the lower level,the MPC-based direct rotor current control of the DFIGs coordinated with frequency control is proposed to track the power reference,whose response is included in the frequency prediction.