Use of Neutral Overvoltage Relay for Protection of Industrial Systems with DYN Transformer Operation in Intentional Island

This article briefly reviews the importance of distributed photovoltaic generation systems in industry and heir growing trend. It also addresses the problem of islanding in such systems and proposes an alternative for protecting power systems in the event of phase-to-ground faults in the ungrounded feeder during islanding using the neutral overvoltage relay. The 59N function of the relay eliminates the need for grounding transformers and prevents the power system from injecting phase-to-ground faults. This avoids potential catastrophic damage to equipment and personnel in the plant, as well as possible loss of profit. The study suggests that the use of the 59N function is a simple and cost- effective solution for photovoltaic generator ground-fault protection that provides greater safety during islanding operations.