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U.S. Department of Energy
Office of Scientific and Technical Information

Cost/risk trade-offs of alternate protection schemes for small power sources connected to an electric distribution system. [PROTECT]

Technical Report ·
OSTI ID:6079510
The provisions of the Public Utility Regulatory Policies Act of 1978 have stimulated the interconnection of dispersed storage and generation (DSG) devices on utility distribution systems. One of the requirements for parallel operation of DSGs is that adequate protection be provided at the point of interconnection to ensure that DSGs do not damage the utility's distribution system and customers' loads when a utility system abnormality (open or short circuit) occurs. This report describes a methodology formulated to aid in deciding on the appropriate quality and quantity of protection equipment required for a small electric power producing device, known in the industry as dispersed storage and generation. In this methodology, a discrete state-space model of the response of both the utility's and DSG's protection equipment to shunt faults (short circuits) and series faults (open circuits) on an electric distribution feeder is developed. The parameters of the model are linked to the component reliabilities of the protection schemes and to the specific characteristics of the distribution system. The mathematics of semi-Markov theory are used in the methodology to calculate the expected annual damage costs for various protection schemes. The total costs are calculated for alternative protection schemes by considering equipment damage, repair time, lost revenue, outage costs, and time spent in different operating states during the hazardous condition(s). This methodology is useful to electric utilities, small power producers, and regulatory bodies who must make decisions regarding the adequacy and the cost-effectiveness of protection requirements for DSG installations. The model is implemented on the computer in the form of a FORTRAN program, PROTECT. A sample evaluation among various protection schemes is presented. Four schemes are designed for a 500-kVA synchronous generator connected to a hypothetical feeder.
Research Organization:
Systems Control, Inc., Palo Alto, CA (USA). Energy Systems Div.
DOE Contract Number:
AC05-84OR21400
OSTI ID:
6079510
Report Number(s):
ORNL/Sub-81-16957/1; ON: DE86008952
Country of Publication:
United States
Language:
English