Improved Operational Efficiency of the Distribution Grid

Utilities today do a limited amount of effort to reduce the system losses occurred on the distribution grid, primarily because of the lack of information necessary to make an impact on the loss level. Although utilities perform calculations to determine what their respective loss levels are (typically 7 to 8%) and these levels are used in rate-making calculations, the calculations are based on conditions where all equipment is in service as planned. The use of capacitor banks is one such example of the equipment a utility uses to correct power factor on its distribution feeders to improve operating efficiency. While the capacitor banks located in substations may have a connection to the SCADA system in place thus giving the system operators knowledge of their status and ability to control as required, the line capacitors out on the distribution circuits are typically installed without any remote status or control capability. Although utilities maintain these devices on a routine basis, it is not uncommon to have a fairly large percentage of these devices off line when their use would be valuable to improve the efficiency of the grid or on-line when they are not required. With the capabilities of GRIDmaster that utilizes customer load information from installed AMI systems, the system operator has access to near real-time system information that can identify whether a circuit has an inoperable or off-line capacitor bank allowing the operator to take action to address the shortfall of Vars on the system. Because the availability of the capacitor bank was assumed in the rate structure, its unavailability when needed results in added operational costs to the utility as the utility then has to cover the additional generation requirement not paid for through the rate structure.

The efficiency of the distribution grid is also impacted by the loading of the distribution feeders and how that load is distributed among circuits and among the phases of a circuit that carries the load. Because of the limited information currently available to a utility on the loading of certain line segments on a feeder, the utility performs estimations on how to load up the individual phases of a circuit or how to configure the circuits within an area. With the use of GRIDmaster and the customer load data available from the installed AMI systems, the utility now has an analysis tool and a system model which can help determine the most efficient way to load a particular circuit (the connection of load onto phases of the circuit) or determine the optimal configuration of a group of circuits in an area. This improved analysis will result in a more efficient delivery of power to customers thus reducing line losses.

Whether or not a utility takes action to improve its line losses beyond the current level is a decision each utility needs to make. An additional value of utilizing GRIDmaster for analysis of the existing grid is to provide the utility with a more accurate actual loss level for use in it’s rate making process. An assumption that a utility has a 7% loss level where the calculation reveals that the utility actually has a 7.5% loss level can have a significant impact in the rate making process as the utility works to establish it’s true cost of operation.