Distribution Systems
P. Niranjan; N.K. Choudhary; N. Singh; R.K. Singh
Abstract
Conventional overcurrent protection schemes may not be sufficient to provide the complete protection of microgrids, especially in the islanded mode (ISM) of operation. Directional overcurrent relays (DOCRs) in microgrid may malfunction due to significant changes in fault current level and change in topology ...
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Conventional overcurrent protection schemes may not be sufficient to provide the complete protection of microgrids, especially in the islanded mode (ISM) of operation. Directional overcurrent relays (DOCRs) in microgrid may malfunction due to significant changes in fault current level and change in topology from grid-connected mode (GCM) to ISM. The novel contribution of this study is to determine the optimal settings of time-voltage-current-based dual-setting DOCRs with mixed inverse characteristics, valid in both GCM and ISM, without any miscoordination of relay pairs. The relay coordination problem is formulated as a mixed integer non-linear programming (MINLP) problem and optimally solved using an improved environmental adaption method (IEAM). The proposed relay coordination scheme has been tested on a 7-bus microgrid, the low-voltage section of the modified IEEE-14 bus benchmark system. The performance of the proposed protection scheme has been compared with the existing schemes, considering conventional DOCRs, time-voltage-current-based DOCRs, and dual-setting DOCRs.
Distribution Systems
N. Kumar; D.K. Jain
Abstract
The integration of distributed generations (DGs) can disrupt the distribution system's radial configuration, leading to potential coordination issues with the existing protection scheme. Disparate operating modes of microgrids render traditional protection schemes ineffective and insecure. This highlights ...
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The integration of distributed generations (DGs) can disrupt the distribution system's radial configuration, leading to potential coordination issues with the existing protection scheme. Disparate operating modes of microgrids render traditional protection schemes ineffective and insecure. This highlights the need for alternative approaches to ensure the reliability and security of microgrids. To mitigate the relay coordination problem in microgrids, this paper puts forth a solution in the form of an adaptive protection scheme. The proposed method is based on fault current and integrates the use of adaptive numerical directional overcurrent relays (ANDOCRs). The proposed adaptive protection strategy encompasses a microgrid central protection controller (MCPC) equipped with communication capabilities. This feature enables MCPC to communicate with intelligent field electronics devices (IFEDs). The MCPC receives data from the IFEDs and updates the ANDOCRs' settings according to the operation mode. This paper suggests a modified objective function specifically tailored to tackle the nonlinear optimization problem for relay coordination in microgrids to strengthen the coordination between primary and backup relays. The proposed adaptive protection scheme also incorporates a quick online fault detection algorithm to identify the faulty feeder precisely. The proposed method is assessed for its performance using a highly unbalanced IEEE-13 node distribution system in MATLAB/Simulink.
