Volt/var management? An essential “SMART” function

The smart grid (SG) is an all-encompassing term reflecting the broad objective of applying the latest technology to the overall power system. As it was designed to do, the SG philosophy and government backing has prompted an avalanche of ideas to be generated in every aspect of power system operation. The subject feature discussed in this paper is the VVMS (volt/var management system). The objectives of a coordinated VVMS include reducing system-wide losses, minimizing distribution system and customer voltage variation, reducing maintenance costs, reducing operating costs, reducing/deferring capital spending and increasing the power delivery capacity of existing equipment. In the case of the CVC (conservation voltage control) application, an added objective is maintaining customer voltage levels to minimize power consumption on the system. This SG interest should also prompt comprehensive review of the present system´s equipment, integrating the SG into the present systems and evaluating innovative application of present equipment. These reviews will assist in forming the basis for the algorithms used in controlling the SG. They will also form the basis for local backup operation for many contingency cases which will occur, even in an SG system. This paper will also discuss the need to retain much of the local intelligence (locally) for those broader operational contingencies which will inevitably occur. Not only must the SG meet objectives as an overall system but it must continue to meet those objectives for isolated areas for all contingency conditions. A distribution system example will include some presently available hardware capabilities that are not universally being used to the fullest advantage towards the SG goals. The industry must be careful not to lose the local intelligence and operational capabilities that have been developed over many years of experience.