Research on line voltage quality control of microgrid in islanded mode

A secondary voltage control strategy is proposed for the improvement of line voltage quality in islanded microgrid. Secondary voltage control is commonly utilized in voltage regulation of line voltage in islanded mode because of the application of droop control scheme in power converters, which leads to deviation of frequency and voltage following the variation of system loads. However, the line voltage may be fluctuant drastically if large system loads variation exist, likely there are heavy loads switching on or off, and this even causes system stability problem. A secondary voltage control scheme based on inverters' power feedforward is proposed here to improve the system dynamic performance. With power feedforward the secondary voltage regulator can immediately response to load variation to enhance the line voltage quality, which is realized through the shift of droop curves of power converters by power distribution algorithm. The system simulation model has been established on the basis of the proposed control strategy and simulation results verify the validity and effectiveness of the control scheme.