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Fault current calculation in distribution systems faces the problem with participation of inverter-based distributed generation (IBDG). This paper analyzes the fault response of IBDG in order to model it under fault condition. An adaptive algorithm based on an iterative technique is then proposed to calculate the fault current in a system with the installation of IBDG. This algorithm is first validated by the conventional fault calculation technique in case of a system without IBDG. Then, a time-variant simulation is performed to validate the proposed algorithm for the system with IBDG. © 2013 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.

Increased distributed generation (DG) in systems always brings about the impacts on maintaining the operation of protection systems. This paper concentrates on the impact on the protection reach reduction and proposes a solution to eliminate this impact by using a suitable DG transformer in parallel with a grounding reactance at the neutral point of the transformer's winding. Based on this, a Tabu search algorithm is proposed to maximize DG when the system operating limits and the protection reach reduction are considered as constraints. In order to illustrate the effectiveness of this algorithm, a case study is performed through an IEEE 34 Node Test Feeder. © 2012 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.

With the rapid increase in using New/Renewable Energy Resources, Inverter-based Distributed Generations (IBDG) are more and more widely installed in electric power systems. However, the limited short-circuit current contributed from these generators should be noted for the operation of the protection systems. This paper analyzes the changes of short-circuit currents in distribution system with the penetration of IBDG and illustrates how the inverter control modes affect the response of the IBDG. Then, an adaptive algorithm is proposed for short-circuit currents calculation. A simulation in Matlab/Simulink environment comprehensively compares the changes of short-circuit current in the system before and after installing IBDG as well as verifies the proposed algorithm.

For exploiting renewable energy resources and obtaining the maximum profit, Distributed Generation (DG) is expected to be as large as possible. However, the DG detrimental impacts on the connecting systems, which are proportional to DG, should be prevented. This paper proposes an algorithm to maximize DG along with an assistance of grounding reactance to keep the sensitivity of corresponding protective relaying at acceptable grades. To illustrate the application of this algorithm, a case study is done through the IEEE 34 Node Test Feeder.

Protection schemes of distribution system are designed conventionally for radial feeder structure with one source supplying. The presence of distributed generation as the second source causes the protection schemes to be confused in operations. This paper evaluates the reach of protective relays after distributed generation has been installed into the system. All types of faults are analyzed with the consideration of system grounding methods and connection transformer which connects distributed generation to power system. Then, an approach is proposed to maintain the protected areas of protective devices.