Modeling techniques for studying DG interconnections to distribution systems

Growing requirements for high reliability of power supply have focused interest on distributed generation (DG) and power electronic devices when ride-through support is needed. When combined with the existing distribution grid, high reliability is possible. Even when power electronic equipment is not required, DG must be used to achieve reliable system. However, the addition of DG complicates protection schemes and associated control equipment. If not properly handled, lower reliability and even a reduction in power quality can result. Criteria for DG integration into existing distribution grids has been defined by Standards that provide requirements relevant to the performance, operation, testing, safety considerations, and maintenance of DG interconnections. However, Standards do not provide methods for determining practicality, on whether the distribution system has appropriate current and voltage ratings, and other relevant characteristics to allow interconnection. It does not prescribe methodologies for determining system limitations or DG unit protection and operating requirements. The user is responsible for identifying suitable methods. To optimize DG interconnection, computer studies must be performed.