参与微电网频率调节的光伏发电系统模糊自适应功率控制

Fuzzy adaptive power control for photovoltaic power generation participating in frequency regulation of microgrid

针对光伏在微电网中渗透率不断提高导致系统惯量和频率响应能力不足的问题,提出一种模糊自适应功率控制策略。首先,每相邻两组光伏阵列分别通过前级Buck-Boost型DC/DC变换器并联后再通过DC/AC逆变器接入微电网,其中一组光伏阵列运行在最大功率点追踪模式,并为另一台运行在模糊自适应功率追踪模式的DC/DC变换器提供最大功率参考;其次,考虑到光伏发电运行中负荷变动、辐照度波动等多种因素导致的系统频率波动,设计了模糊自适应控制器,以相邻光伏阵列提供的最大功率参考和当前系统频率为输入,决策输出功率储备因子,并结合最大功率参考生成光伏输出功率指令,实现光伏发电输出功率的自适应调节。最后,光伏阵列运行在模糊自适应功率追踪模式具有上下灵活调节的功率储备,通过自适应增加或减少功率储备实现微电网频率的双向调节。该控制策略减少了最大功率点估计器使用、无需详细的光伏模型且易于实现,基于IEEE 13节点测试系统的仿真结果验证了所提控制策略能够有效抑制微电网频率的波动。

A fuzzy adaptive power control strategy was proposed for the issue of insufficient system inertia and frequency response capability caused by the increasing penetration of photovoltaic(PV)power generation in microgrid.Firstly,each adjacent two groups of PV arrays were connected to the microgrid through two parallel Buck-Boost DC/DC converter,and then connected to the microgrid through a DC/AC inverter.One group of PV array operating in the maximum power point tracking mode provides the maximum power reference for the other DC/DC converter operating in the fuzzy adaptive power tracking mode.Secondly,considering the frequency fluctuations caused by load variations and irradiance fluctuations,a fuzzy adaptive controller was designed,which takes the maximum power reference provided by the adjacent PV arrays and the system frequency as input.Then a power reserve factor was generated,and PV output power reference was generated to realize the adaptive regulation of PV power generation.Finally,the PV arrays operating in fuzzy adaptive power tracking mode are with flexible power reserves,which can realize bi-directional regulation of microgrid frequency by adaptively increasing or decreasing the power reservation.This strategy shows the advantages of no requirements of MPP estimator or detailed PV model,and it is easy to implement.The simulation results of an IEEE 13 bus test system demonstrates that the proposed control strategy can effectively suppress the frequency fluctuation of the microgrid.