Maintaining the reach of protective devices in distribution system with penetration of distributed generation

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.