中文摘要：

孤岛运行的微电网由于其容量小，并且大部分微电源通过电力电子装置并网惯性小，因此微电网的频率和电压受微电网中负荷变化影响较大。基于电力系统二次调频原理研究了一种微电网频率控制策略。传统的下垂控制策略属于有差调节，当系统负荷发生变化时，不能保证微电网频率稳定在额定值。提出的基于电力系统二次调频原理的微电源频率控制策略在下垂控制的基础上，引入了比例一积分（PI）控制环节实现了频率的无差调节，类似于电力系统的二次调频过程。为了克服微电网惯性低的缺点，模仿了同步发电机的转子运动方程为该频率控制策略增加了一阶惯性环节，更好地提高了微电网的频率稳定性。基于Matiab／Simulink仿真平台，仿真研究了采用上述控制策略时微电网在孤岛模式下负荷投切、负荷冲击、负荷随机波动、微电网运行模式切换等多种工况时的频率变化，仿真结果证明了该控制策略的正确性和有效性。

英文摘要：

Because of the characteristic of small capacity and low inertia of the inverter based micro-generation, the load changing in islanded micro-grid has large impact on frequency and voltage. A novel frequency control strategy of micro-grid based on the secondary frequency regulation of power system is proposed. Traditional droop control strategy of micro-grid is not a no-error adjustment. It can＇t guarantee the frequency of micro-grid operate at rated state when the load changes. Besides the P-f droop control strategy, the proposed frequency control strategy introduces the proportional-integral （PI） control into control flow. The process is a no-error adjustment, which is similar to the secondary frequency regulation of power system. In order to overcome the disadvantage of low inertia of micro-grid, a first-order inertia link which imitates the motion equation of rotor of synchronous generator is added to the proposed frequency control strategy. So the stability of frequency in micro-grid is greatly improved. The typical operation states of micro-grid such as loads change, loads shock, the random loads fluctuation in islanded mode, and the operation states transform are simulated based on MATLAB/Simulink. Simulation results verify the correctness and validity of the proposed frequency control strategy.