孤岛模式下的微电网频率的协调控制研究

Frequency Coordination Control Strategy for Microgrid in Islanded Operation

针对由可再生能源发电系统、常规柴油发电机组和蓄电池储能系统组成的微电网,提出了一种适合微电网在孤岛模式运行时的频率协调控制策略。该策略将系统频率的动态调节过程分为动态支持、下垂控制和无差调频3个层次,对各微电源进行分层协调控制。在该控制策略下,当可再生能源发电功率或负荷大幅波动后,首先蓄电池快速地向系统提供动态支持,分担了柴油发电机的电磁功率,从而抑制了频率初期下降或上升的幅值;扰动初期过后,系统稳态频率先后在微电源的下垂控制和无差调频的作用下完成将一次调频和二次调频的任务。利用DIgSILENT/Power Factory仿真软件研究了微电网在有功扰动下的动态运行特性,仿真结果表明了所提出的控制策略可以在微电源有功出力或者负荷需求变化时,有效地协调控制柴油发电机和蓄电池的有功功率输出,提高了微电网在孤岛模式下的频率性能。

This paper investigates an frequency coordination control strategy for islanded microgrid, including renewable energy, diesel generator and battery energy storage system （BESS）. In the study, the dynamic process of frequency based on the coordination control of microsources is divided into three levels, including the dynamic support, droop control and zero error regulation. The proposed strategy adopts the fast response capability associated with BESS to provide dynamic support, which partly shares diesel generator electrical power, thereby inhibiting the amplitude decrease or increase of earlier frequency fluctuations. The control strategies and control modes are classified into the primary frequency regulation and the secondary frequency regulation. The secondary frequency regulation can be applied for frequency restoration to remove the frequency deviations which could be caused by the decentralized droop controllers in the diesel and storage system. Simulation are performed on DIgSILENT to study the dynamic characteristics of microgrid under the fluctuations by microsources or loads. The simulation results verify the effectiveness of the proposed coordination control strategy of diesel generator and BESS and greatly improve the performance of system frequency regulation.