Determination of Allowable Capacity of Distributed Generation with Protection Coordination Consideration

The presence of distributed generation (DG) provides considerable benefits from both engineering and economic viewpoints. However, it changes radial configuration of the distribution feeders. Consequently it may cause coordination failure to existing protection system which is originally set based on radial configuration. In addition, high penetration level of DG may increase feeder loss, and cause system voltage profile out of a required range. This paper presents an optimization based method to calculate maximum allowable capacity of a DG considering a set of constraints formulated to maintain protection system coordination. In addition feeder loss and system voltage constraints are also taken into account. With the developed methodology, the maximum DG capacity which does not provide adverse effects to the existing system, i.e. violate protection coordination, increase feeder loss, and cause voltage violation, can be obtained.