Page 37 - Energize January 2021

TECHNICAL

Figure 2: AMI and the smart grid (S Klimowitz)

customer class, and DER type. This gives circuit, the spatial load distribution. As a result, the voltage delivered to a given customer at
planners a greater ability to assess needs any given time could vary significantly.
under varying circuit configurations, the The utility usually has no way of monitoring delivered voltage without installing special
possible operational impacts of behind-the- equipment, and residential consumers have often been relegated to living with whatever
meter alternatives, and how voltage levels they received from the utility. Abnormally high or low voltage can be highly
customer-owned DERs will impact load problematic for certain types of electrical equipment, adversely impacting operation and
growth forecasts. sometimes dramatically shortening operating life.
Accurate load shapes can also help AMI enables the monitoring of voltage at the point of electricity delivery. This allows
utilities understand the impact time-of-use proactive identification of areas where voltage levels are chronically out of tolerance, and
(TOU) rates have on customer bills and the addressing of those problem areas before customers suffer from equipment malfunction
behaviour. Without hourly usage data at or failure. Close voltage monitoring also allows conservation voltage reduction (CVR) to be
the customer level, the utility does not applied without the need for additional voltage monitors in the distribution network.
have a reference for how customers will
be impacted by and respond to the new Outage management and grid reliability
rates. The AMI-generated load shapes can In a professionally managed grid, a utility should not have to wait for a customer call to
be used to inform revenue and planning know that power is out. AMI systems can report loss of voltage to an outage management
forecasts with more precision. system (OMS). A well-designed OMS system can group and analyse customer calls using
feeder models which provide information about likely fault locations. This information, in
Power quality turn, is passed along to staff who are working in the field to resolve fault conditions.
For the residential customer, voltage is the The increased ability to monitor grid conditions makes it possible to anticipate and mitigate
key determinant of power quality. Utilities potential power integrity issues, resulting in fewer outages and power quality events. Smart
are supposed to deliver electricity to meters are equipped with a “last gasp” facility, using some form of energy storage, which
residential consumers within a voltage allows a power failure message to be sent to the AMI centre in the event of a power failure.
band of 230 V ±10% during normal The meter ping function sends a signal to the meter to determine the energised status. It
operating conditions. The voltage at any can be used to do on-demand reads of a single meter, to determine if an outage is a
given point on the distribution system is customer issue, (i.e., a tripped breaker) or system issue, and can also be used to do a mass
not a constant, as it varies according to ping to all the meters, or to meters in a specific given area. This is helpful in identifying
the amount of cumulative load on the smaller outages nested within larger outages so that restoration can be verified, improving

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