An Evaluation Method of Reactive Power and Voltage Control Ability for Multiple Distributed Generators in an Islanded Micro-grid

Abstract

Micro-gird, as an effective way of connecting the large-scale distributed generators (DGs) to distribution network, has attracted the attention of scholars these years. However, the reactive power and voltage control is a big challenge to the islanded micro-grid, due to the small capacity of the master source or lack of a diesel generator with a large load fluctuation. In the interest of more economical and flexible adapting to various operation modes in an islanded micro-grid with renewable sources, it is necessary to utilize the reactive power potential of existing DGs as much as possible. In this paper, a comprehensive index for evaluating the reactive power and voltage control capability of DGs is proposed using the Analytic Hierarchy Process (AHP). The comprehensive index is determined by five subindices, including Voltage Deviation, Voltage Fluctuation, Voltage Harmonics, Static Reactive Power Support Capability, and Transient Reactive Power Support Capability. The proposed indices are utilized to evaluate the reactive power and voltage control capability of islanded micro-grids with various combinations of DGs such as wind turbine, photovoltaic and energy storage, while the difference between master-slave control and peer-to-peer control is mainly analyzed in this way. Simulations are carried out in the DIgSILENT environment. The effectiveness of the proposed comprehensive index is verified by the comparison of different cases, which can be a reference for the generation planning and voltage control strategies of islanded micro-grids.