Phasing Information
Phasing information within the DMS data model is extremely important to solution accuracy, the more the accurate the phasing information the more accurate the power flow solution will be. If accurate phasing information cannot be provided there will be limitations with certain DMS functionality. For example while using Fault Location Analysis if per phase fault currents are being received at the breaker the algorithm may not trace down the correct single phase lateral if the phasing has been defaulted. Let's say a fault occurs on a "A" phase lateral in the field but in the NMS the lateral has been defaulted to phase "B" this candidate location will not be flagged. To default phasing information there are several options that could be used.
1. Create a balanced 3 phase model in which all devices are simply defaulted to 3 phase and the load split across each phase evenly. This scenario would provide reasonable results down the feeder backbone but the lateral taps off the feeder would generally show incorrect current flow since in the field it would be a single phase device but NMS would have it modeled as a 3 phase device and the current would be spread across three phases rather than all on a single phase.
2. Create a program that analyzes the feeder and tries to estimate the phasing. This program would need to look at the total load served on the feeder and then distribute it evenly such that a single phase is not overloaded. If phasing was known for a portion of the feeder the load in the known area should first be summed and then the unknown loading distributed accordingly to maintain balance.