Impacts of Distributed Generation on Power System Protection

Abstract

Distributed generation (DG) offers huge benefits to the power system network to cater to the rapidly growing demand for electric power. The integration of DG units into existing power networks is beneficial to both utilities and consumers. However, the installation of DG units in distribution networks might impose some operational, technical, and economic impacts. Increased short-circuit level and changes in load flow direction are examples of the technical issues arising from the high penetration of DG. Such issues will affect the existing protection system, mainly overcurrent relays. Thus, to ensure reliable and selective operation of protection relays, the impacts of DG should be considered. This paper discusses the impacts of DG on the protection systems by identifying various protection problems. The paper is complemented by a simulation case study on the impacts of DG on fault levels, protection coordination, and distance relays. The simulated system was modeled using DIgSILENT PowerFactory® software.

Developing an Adaptive Protection Scheme Towards Promoting the Deployment of Distributed Renewable Sources in Modern Distribution Networks: Operational Simulation Phase

“…Conventional protection schemes were originally designated for radial distribution networks with unidirectional power flow, which were commonly protected using overcurrent relays (OCRs) based on fixed fault current levels. The interconnection of DG units will consequently transform the radial topology into meshed structure with bidirectional power flow, affecting both the magnitude and direction of fault currents in various parts of the system [4]. Moreover, future smart grids will be subject to significant changes and unexpected grid states that may alter the network topology such as the addition or disconnection of a new incoming generation unit, the addition of a new line, the sudden line outage occurrence and the operation of DG units in either grid-connected or islanded mode.…”