Optimization Principles / Constraints
The optimization calculation should take into consideration the following factors:
The optimized system should satisfy the current levels of service as embodied in any contracts.
The optimized system should take into consideration current safety requirements where these influence the choice of materials.
Many organizations also have policies that define their design philosophies. The optimized system should take into considerations any constraints embodied in these policies. However, it is necessary also to assess the adequacy of these standards in comparison to the industry standards to ensure that the former standards do not err on the low side.
The locations of the existing customers must not be varied.
Security should be designed into the optimized system to reflect the need to protect customer supply in the event of equipment compromise and the need to meet operational demands consistent with levels now considered prudent and economically justifiable, for example, expected outage duration and number of customers affected for a failure of the asset.
Security of supply considerations may have great impact on the system layout and asset configuration in an optimized system.
A suggested criterion for the security of supply in a distribution network is to have not more than, say, 100 customers affected for a maximum of one day in any one incident that cuts supply.
The optimized system should provide for current demand plus allowance for growth. In no case should the optimized capacity exceed the current system capacity.
Evidence for future growth needs to be provided and a reasonable growth period determined. Typically 3 to 10 years is considered a growth horizon for which planners have some confidence and can make reasonable predictions.
Where the existing system is under capacity, it should be accepted as the optimized system.