Abstract
Multi-microgrids have many new characteristics, such as bi-directional power flow, flexible operation and variable fault current consisting of the different control strategy of inverter interfaced distributed generations (IIDGs), which all present challenges in multi-microgrid protection. In this paper, the current and voltage characteristics of different feeders are analyzed considering faults at different locations of the multi-microgrid. Based on the voltage and current distribution characteristics of the line parameters, a new protection scheme for the internal faults of multi-microgrids is proposed, which takes the change of phase difference and amplitude of measured bus admittances as the criterion. This proposed scheme has high sensitivity and reliability, is based on a simple principle, and can be easily adjusted. Simulation results using PSCAD/EMTDC verify the correctness and effectiveness of the protection scheme.
Highlights
With increased energy demand and pressure to reduce emissions, microgrids have gradually become a hot research topic in power systems [1]
A microgrid is a medium or low-voltage power system, which consists of distributed generations (DGs), energy storage devices, energy conversion devices, loads, and corresponding supervision and protection equipment [2, 3]
This paper proposes a new protection scheme for internal faults of multi-microgrids, which considers the control strategies of the DGs as well as the interconnection and interaction among the adjacent microgrids
Summary
With increased energy demand and pressure to reduce emissions, microgrids have gradually become a hot research topic in power systems [1]. An alternate protection and control scheme for microgrids with converter interfaced micro sources was proposed in [14], where a new inverse time relay characteristic was put forward by using the measured admittance of the protected line. This paper proposes a new protection scheme for internal faults of multi-microgrids, which considers the control strategies of the DGs as well as the interconnection and interaction among the adjacent microgrids. A measured admittance scheme is proposed that analyzes the current and voltage vector graph before and after the fault. This paper mainly discusses the protection scheme for internal faults of the multi-microgrid with radial structure in grid-connected mode, where DGs are under PQ control strategy.
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