Protection Coordination of Properly Sized and Placed Distributed Generations–Methods, Applications and Future Scope

Abstract

The radial distribution networks are designed for unidirectional power flows and are passive in nature. However, with the penetration of Distributed Generation (DG), the power flow becomes bidirectional and the network becomes active. The integration of DGs into distribution network creates many issues with: system stability, protection coordination, power quality, islanding, proper placement and sizing etc. Among these issues, the two most significant are optimal sizing and placement of DGs and their protection coordination in utility network. The proper coordination of relays with high penetration of DGs placed at optimal location increases the availability and reliability of the network during abnormal operating conditions. This research addresses most of the available methods for efficient sizing and placement of DGs in distribution system (numerical, analytical and heuristic) as well as the developed protection coordination techniques for utility networks in the presence of DGs (Artificial Intelligence (AI), adaptive and non-adaptive, multi-agent, hybrid). This paper indicates the possible research gaps and highlights the applications possibilities and methods’ limitations in the area of DGs.

Optimal Coordination of Overcurrent Relays in Microgrids Considering a Non-Standard Characteristic

“…Protection systems in microgrids must deal with the following two aspects: (a) the dynamic behavior that is usually presented due to intermittent energy resources and (b) the microgrid operation mode which can be connected or disconnected from the main power grid [5,6]. Microgrids are reconfigurable electric power systems with variable levels of current fault and bidirectional power flows [7]. Microgrids have changed the traditional paradigm of radial DNs into non-radial and flexible systems.…”

Adaptive protection coordination scheme in microgrids using directional over-current relays with non-standard characteristics

“…However, there are still some technical issues to be discussed for their suitable incorporation such as the protection coordination problem. MGs are flexible systems that may have multiple operating modes which makes their protection coordination a challenging task [2] , [3] ; MGs also tend to grow in size and complexity and the fact of harboring DG introduces bidirectional power flows and variable short-circuit currents [4] . MG operation modes render inefficient the conventional design of protection coordination which considers fixed short circuit levels and unidirectional power flows; therefore, researchers around the world are in constant search of new models and methodologies regarding the protection coordination problem of MGs [5] .…”

An Approach for Optimal Coordination of Over-Current Relays in Microgrids with Distributed Generation

“…DG changed the traditional configuration of unidirectional power flows in DNs where there is only a single generation bus. With the presence of DG, there are multiple generation buses that produce bidirectional power flows and variable short circuit levels [3]. In general terms, new protection systems must guarantee the stability of the protection scheme not only under intermittent DG units and loads, but also under the possibility of switching between grid-connected and islanded modes [4,5].…”