Integrating reliability into distribution planning

The development of short range and long range plans for expansion of the distribution system has become an ever-increasing challenge for today´s engineers. At the corporate level, there are two goals common to utilities that appear to be conflicting - cut costs and improve reliability. Compounding this is the fact that the same departments and personnel do not always perform planning and reliability initiatives and, as a result, the consequences and impact of each are not fully quantified or properly taken into account. Distribution planning generally centers on load and voltage issues. Reliability initiatives are in place to address corporate reliability targets, specific concerns for areas of poor service, or may be driven by state utility commissions. Utilities find it to be advantageous to develop a single system plan that incorporates all of these. This paper addresses how to combine the development of reliability improvement initiatives into the overall system plans. Related issues such as changes in equipment ratings and reduced capacity margin are also addressed and their impacts on overall system reliability are discussed.