Specifics of gradual transition to post-emergency parameters for static stability testing of distributed generation facilities

Design and operation of distributed generation facilities needs to provide for sufficient margin of static stability in a variety of operating situations, including normal and post-emergency operation in parallel with the outer grid (the power system). Power system protections are often placed where the on-site power plants connect to the power system; these protections enable the loaded generators to become islanded in case of emergency; rated margin of static stability must be available in such post-emergency operation. To analyze static stability of synchronous generators and motor loads, we propose combining gradual equalization and gradual transition to post-emergency parameters. However, the latter method has different quirks when applied to static stability testing of generators, depending on whether they are running in parallel or islanded. Besides, application of this method requires multiple constraints pertaining to the functioning of on-site power plants, among other things. The authors hereof have developed a single algorithm for static stability testing of generators and loads that applies well to on-site power plants whether they are islanded on running in parallel to the grid. The algorithm adjusts for constraints on excitation systems and is implemented in KATRAN software. A computational experiment is described herein that concerns an electricity delivery system that is powered by distributed generation facilities and carries heterogeneous motor loads. Specific features of such studies are additionally described.