IEEE Power & Energy Magazine - May/June 2017 - 43

ANM is based on new monitoring, control, and network-planning
functionalities, which were also developed and demonstrated in
laboratories and on live distribution networks.
Main Results
IDE4L Concepts
Electricity distribution networks have, to date, been designed
and operated as passive networks according to a design point
that requires them to handle all probable loading conditions.
Distribution networks are overdimensioned today due to
the quality of supply obligations and missing possibilities
to control DERs. With that design point, the only way to
increase the number of serviced users is to add network
infrastructure assets in proportion to load growth.
The management of a power delivery infrastructure is
enhanced by utilizing active resources in the ANM and
especially by coordinating the operation of DERs from the
whole system viewpoint to achieve synergy benefits, rather
than optimizing their operation from a single party's viewpoint. To realize this vision, it is essential to integrate active
resources as part of an active network instead of just connecting to the network with the "fit and forget" principle.
Control Methods of the Active Distribution Network

An active distribution network utilizes the controllability
of DERs in addition to grid assets. Connection requirements (grid codes) are an efficient method to establish
technical capabilities for the control of DERs. Examples
of applicable connection requirements are production curtailment and the voltage or reactive power control of a DG
unit. A dynamic or power-based grid tariff provides customers with incentives to shift load demand to the network
during off-peak hours.
A distribution grid may also be controlled directly by the
DSO. Direct control is applied when fast and precise control
actions are needed, for example, to maintain the required voltage quality in the grid. The DSO may control its resources
directly. Traditionally, European distribution grids have included very few control elements, such as on-load tap changers
(OLTCs) at primary transformers and reactive power compensation units at primary substations. The remote control of MV
grid switches may also be used for congestion management by
changing the location of normally open switches along MV
feeders. Recently, OLTCs for secondary transformers have
been introduced to mitigate voltage problems in LV grids.
In the future, energy storage-like batteries may also provide
interesting resources for grid management.
The continuity of electricity supply to customers is one of
the main concerns of DSOs today. Distribution automation
reduces outage duration, while additional circuit breakers
may/june 2017

along MV feeders reduce interruption frequency. Automated
fault location isolation and supply restoration (FLISR) solutions may combine both of these enhancements through
FLISR logic in distributed intelligent electronic devices
(IEDs) or a centralized distribution management system
(DMS) and through direct control of circuit breakers and
switches. The next step for reliability enhancement may be
provided by microgrids capable of island operation by supporting supply restoration of a congested backup connection
and automatically isolating fault conditions and resynchronizing after restoration phase.
The DSO's chance to realize production curtailment may
be mandated by grid code such as in Germany, or it may
require a special contract between the DSO and the customer.
Similarly, the voltage control of DG units may be mandated
by grid code, or a special contract might be needed to allow
the DSO to control the voltage or reactive power of a DG
unit. Grid codes and special contracts should be applied only
to nonmarket-based control resources like reactive power
or emergency control actions like production curtailment.
Therefore, demand response should be allocated mainly to
flexibility services.
In addition to more traditional control methods, DSOs
may utilize flexibility services from commercial aggregators. Two types of flexibility services, called scheduled and
conditional reprofiling of flexible DERs, have been proposed
by the Address project, and those have also been used in the
IDE4L project. Scheduled reprofiling is an indirect control
method to prevent forecast congestion a day ahead due to, for
example, maintenance work in the distribution grid. Conditional reprofiling is a real option-type product traded a day
ahead but requires activation before operation in real time.
Therefore, it is more suitable for occasional and more uncertain congestion cases in the grid, such as unexpected high
or low demand and correspondingly low or high production.
Active Network Management

An essential part of implementing ANM is distribution automation and integration of more parties into the electricity
market and power system management. Figure 1 presents the
vision of a complete automation solution for ANM based on
previously described control methods.
Distribution automation (shown inside the DSO box in
Figure 1) includes control center information systems, substation automation, secondary substation automation, and
IEDs, including multiple types of devices like smart meters
in the customer interface. It realizes the real-time monitoring
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Table of Contents for the Digital Edition of IEEE Power & Energy Magazine - May/June 2017