Page 66 - Energize January 2022

TECHNICAL

Smart distribution network controls and

management lead to energy savings

by Mike Rycroft, Energize features editor

The smart grid is seen as a means to meet the changing needs of electricity networks, and a
number of high-level scenarios have been developed in an attempt to define what SG is and
where it is going. Most of the impact of changing conditions, however, is on the distribution

network or so-called grid-edge sector, and it is here where new techniques and technologies are
being developed and applied to meet the challenge of changing conditions.

ontrol of distribution network The distribution network has been the focus of a number of smart grid innovations,
(DG) parameters using static aimed at reducing energy and improving operation.
Cswitching centralised devices
is common and has been in use for Smart metering
many years. Distribution networks are The first step towards smart distribution network adoption is use of smart metering. These
evolving to incorporate changing load not only improve metering, but result in an improved overall view of distribution networks.
and consumption patterns and increasing Many utilities have realised the usefulness of smart meters over and above smart billing. 1
integration of distributed small scale Smart metering provides a wealth of information on the state of the distribution network,
energy generation (SSEG), such as rooftop which can be used to support the introduction of smart grid management technologies.
solar. Digital transformation at the grid
edges, so-called grid-edge control (GEC) is Control of DG voltage levels
emerging to harmonise the coexistence of One of the primary concerns is control of the voltage level at consumer connection points.
the grid control system. The voltage delivered to consumers is required to remain within set upper and lower limits
This evolution imposes many to ensure that appliances and other machinery connected to the grid operate correctly. In
challenges to the operation of the the South African network these limits are 230 V ± 10% for single phase connections. This is
network, which calls for new control and basically achieved by managing the output voltage of the distribution transformer, and can
operation approaches. The introduction be further refined by the use of voltage control devices along the route.
of SSEGs has had a profound effect on the In a radial distribution system, the voltage at the consumer supply point will
dynamic and static parameters of the DG, decrease with increased distance from the transformer, and one of the aims is to ensure
making real time monitoring and rapid that the voltage at the end of the distribution grid remains above the lower limit, under
adjustment of parameters necessary, all load conditions.
and older non-smart devices are proving With a constant load and a smooth distribution of load, this can be achieved by setting
incapable of handling this situation. Smart the transformer voltage to a value that ensures that the voltage at the end of the route is
controls have been developed that make within limits. However, loads are not constant, and generally the route does not have an
the best use of the situation, but these even load distribution. In addition, the load distribution can vary throughout the day, making
require comprehensive information on the the control of the end-of-line voltage difficult. The effect of load variation with a fixed
state of the system. 3 voltage setting is shown in Figure 1.
Distribution networks are evolving
from the traditional, passive system into
smart, active systems with the rapid
digital transformation at the grid edges,
i.e., the secondary side of LV distribution
transformers. The digital transformation
arises from the adoption of advanced
sensors, smart meters (SM) as well as
development of Internet-of-Things (IoT)
that allows devices to be connected with
two-way communication. Figure 1: Voltage levels under different loads

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