Adaptive auto-reclosing based on DER connectivity data with IEC 61850

Most faults in the overhead distribution networks are temporary in nature. The protection system is therefore designed to open the line in an attempt to clear the fault and then automatically reclose to reconnect the circuit once the fault has cleared. Typical open interval dead-band in the medium voltage distribution grids is in the range of 150-300 ms for fast reclosing shots. Distributed energy resources (DER) are incompatible with the present utility reclosing practices since the DER unit may prevent the arc extinction by continuing to feed the fault. This way, a temporary fault can turn into a permanent one. Also, during the circuit breaker open time of the reclosing sequence, the generators in the network usually tend to drift away from synchronism with respect to the grid. A reconnection made without synchronization may cause serious damage to the DER units, potentially leading to overcurrent and/or overvoltage conditions in the grid. This paper proposes an algorithm for adapting the auto-reclosing sequence based on the connectivity status of the DER units in the distribution grid. The solution has been modeled based on IEC 61850 standard for compliance with modern utility practices.