Page 24 - CARILEC CE Industry Journal_Oct_2019

Timed Connections Consider we have two industrial customers [figure 5], one
with local distributed generation for local consumption,
Timed connections [2] help reduce the level of upstream and another that has energy storage. Both are connected
reinforcement required to facilitate new connections. By to the utility network. The utility has remote control
doing so it allows the network operator to offer faster and facilities at the point of connection. These are RTUs
cheaper connections to the network for distributed which have the capacity to run some localized active
generator customers. network management software.

Consider a connection to a renewable energy source as The customer on the left has control of the distributed
shown in figure 4. Industrial customers will be permitted generation but has agreed to curtail its generation when
to export/import at set times and not at others, or may requested to allow the network to be kept within its firm
have a fixed limit imposed on their output at certain times. capacity. The customer on the right has energy storage
available.

There is an active network management system running
which uses the RTUs to actively manage the distributed
generation and the storage without interfering with the
operation of the actual utility network. In this application the
RTU manages the interface to the switchgear, and ensures
only one control is executed at a time, from either the
utilities SCADA control system, or from the ANM controller.
Although described as a centralized scheme, this
application is closer to a regional scheme as it is
managing a collection of DER in real-time with accurate
Figure 4 - Timed Connections acquisition of distributed measurements. The prime
function of this solution is to maximize the utilization of
This schedule will be enforced primarily through local the network by increasing the generation hosting
control mechanisms on the customer side, and by the DNO capability. This ANM control system typically manages
through the monitoring of power flows at the point of multiple generator outputs of up to 70-80 MVA, with
connection. The local DNO RTU will monitor the multiple constraints, using a meshed wireless network
connection and in the event that constraints are breached providing the communications between the switchgear
sends a failsafe signal to the customer control system to and the ANM. In comparison to timed connections, this
reduce the import/export to the agreed level. If the customer application has a more complex set of rules such LIFO
control system does not comply, the logic will send an and pro-rata selection of generation.
alarm to the Network Management System (NMS), and a
configurable option within the logic will allow the relevant Constraint Management Using ANM
circuit breaker to be opened to disconnect
load/generation/storage (as applicable) if required. The dotted line in figure 5 illustrates the trace of the
network load if there is no ANM running. As can be seen,
Centralized ANM at times it would exceed the firm capacity of the network.
The solid blue line shows that the generation has been
The timed logic approach can be extended by using active curtailed to avoid exceeding the network capacity. By
network management techniques to manage the output applying this to a few sites, it is possible to release
of multiple and dispersed generation. This is real-time capacity on the network to allow a diverse range of
control with feedback loops handled by an Active distributed energy resources.
Network Management ANM system.

Figure 5 - Centralized ANM
22 CE INDUSTRY Journal Figure 6 - Managing capacity