Application of GridEye
for Network Planning
This document provides a use case for the application
of GridEye measurements for the distribution network
planning. GridEye modules primarily measure the
electrical quantities and process the measurements
using the distributed intelligence on every module.
Thus, only useful data for the system operators and/or
end-customers are communicated and stored. In this
way, the high communication costs and big data
issues are avoided. The transmitted data are analyzed
on the server for which they can be used for the
network planning studies. The addition of production
and consumption in the grid needs to receive particular
attention from the distribution system operators.
Suitable decisions should be taken for the network
planning in order to guarantee the secure and reliable
operation of the grid.
Based on the GridEye measurement, a network
planning approach is developed for determining the
maximum additional consumption and production that
can be installed at every node of the grid. The
developed approach allows comparing different
solutions with each other and supports the system
operators to take an appropriate decision for each
specific grid.
Author: Omid Alizadeh-Mousavi
Date: March 8th, 2017
© DEPsys SA
Application of GridEye for Network Planning
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1. INTRODUCTION OF THE USE
CASE AND GRIDEYE INSTALLATION
The grid topology of the use case and the installation
of GridEye modules are shown in Figure 1. The
electricity consumptions in the grid are mainly
residential and agricultural. Moreover, there are PV
installations at three locations shown by G1, G2 and
G3. In this use case, the distribution system operator
is interested in monitoring of the low voltage grid and
then using the measurement data for the network
planning studies. In other words, the system operator
can effectively utilize these measurements to
determine extra production and consumption that can
be added at every node while the secure operation of
the grid is taken into consideration appropriately.
Figure 1. The use case and the installation of GridEye
modules.
The installations of GridEye modules at MV/LV transformer as well as on distribution cabinets are demonstrated in
Figure 2.
a) MV/LV transformer
b) Rogowski coils for the current measurements
at transformer LV side
c) Distribution cabinet
d) PV power plant
Figure 2. Installations of GridEye modules.
Application of GridEye for Network Planning
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2. NETWORK PLANNING USING
GRIDEYE MEASUREMENTS
A year of voltage, current, and power measurements
provided by GridEye are used for the network planning
studies. At first, the current situation of the network is
studied by analyzing the maximum and minimum
nodal voltage levels as well as the maximum loading
levels of cables and transformers in the energy
production and consumption sides. This information is
used for identifying the critical points of the grid from
the voltage and loading levels perspectives. Based on
these statistics, the maximum consumption and
production that can be added at every node is
determined while the secure operation of the grid is
guaranteed. Furthermore, the developed network
planning approach allows the system operators
evaluating the value of several alternative solutions,
including i) upgrade of transformer / cable, ii) taking a
certain level of overloading risk for of transformer /
cable, and iii) deploying GridEye optimal control.
2.1. Analysis of current situation
Based on GridEye measurements and the statistical
analysis, we identify the important information related
to the current operation of the grid, including: the
maximum and minimum voltage levels at every node
and the maximum loading levels of cables and
transformers for the consumption and production
sides. This important information about the current
situation of the grid is presented in Figure 3 which
demonstrates the critical points of the grid. For this use
case, the transformer has reached to its maximum
loading in the consumption side and the voltages of
node 101 and 102 have almost reached to the
maximum allowed voltage level. The rest of the
loading and voltage levels are within acceptable
ranges. Moreover, Figure 3 allows distinguishing the
available margins for the loading of transformer /
cables at consumption and production sides as well as
for the voltages of the nodes.
Figure 3. Important information related to the current situation of the network.
This information is used in the developed network planning approach to support the system operators for determining
the additional consumption / production that can be added at every node such that the technically secure operation
of grid is guaranteed.
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2.2. Network planning approach
2.2.2.
The developed network planning approach is based
on the provided statistics from the GridEye
measurements. In this respect, further consumption
and production that can be added at every node of the
grid are investigated in following subsections.
The addition of production increases the loading of
transformer / cables in the production side and
increases the maximum voltage level of nodes. In the
developed network planning approach, the impact of
the new production on the maximum loading of
transformer / cables and the maximum voltage level of
nodes are taken into consideration. Thus, the system
operator can decide about the additional production
that can be added at every node without deviating the
voltage and current limits.
2.2.1.
Addition of consumption
The addition of consumption increases the loading of
transformer / cables in the consumption side and
decreases the minimum nodal voltages. In the
developed network planning approach, the impact of
the new consumption on the maximum loading of
transformer / cables and the minimum voltage level of
nodes are taken into consideration. Therefore, the
system operator can determine the maximum
additional consumption that can be added at every
node without deviating the voltage and current
limitations. Moreover, the system operators may
permit additional consumption by allowing the
overloading of their assets for a short period of time
and taking a certain amount of overloading risk. The
overloading risk is effectively quantified using the
statistics provided by GridEye measurements.
For instances, for the use case shown in Figure 1,
further consumption cannot be added without causing
overloading at the transformer since the transformer
has already reached its nominal capacity. However, as
mentioned earlier, the system operator can permit
additional consumption in the grid by accepting a
certain level of risk. The risk is presented as the sum
of the products of the overloading level and the
corresponding number of hours. It should be noted
that the maximum additional consumption is the
minimum of the values corresponding to the risk level
and the voltage limits. For instances at node 102, the
consumption of 20 kW can be added by allowing the
transformer’s loading up to 110%. Nevertheless, even
by allowing the transformer’s loading up to 140% the
consumption cannot be added more than 60 kW at this
node due to the voltage limitation.
It is worth noting that the upgrade of the transformer is
an alternative solution which is expensive and allows
increasing the additional consumption in the grid. The
impact of the transformer upgrade on the increase of
consumption can be also analyzed through the
developed network planning approach.
Addition of production
Moreover, the system operators may permit additional
production by allowing the overloading of their assets
for a short period of time and taking a certain amount
of overloading risk. The overloading risk is effectively
quantified using the statistics provided by GridEye
measurements.
The alternative expensive solution is the upgrade of
the assets for increasing their thermal limits and
improving the voltage stability. The impact of the
transformer upgrade on the maximum additional
production can be also analyzed through the
developed network planning approach.
Furthermore, the optimal control of GridEye can be
deployed to increase the maximum additional
production that can be installed. Using the GridEye
optimal control and curtailment of a small amount of
production for a short period of time in the case of
overvoltage and/or overcurrent ensures the secure
operation of the grid with the additional production.
Therefore, the benefit from the installed production is
achieved for most of the time while the secure
operation of grid is ensured and high grid
reinforcement expenditures are avoided.
For the use case shown in Figure 1, the additional
production that can be added to every node of the grid
is limited by the upper voltage limit (i.e. +10%). It
should be noted that the maximum additional
production, in general, is the minimum of the value
corresponding to the risk level and the upper voltage
limit. For instances at node 102, taking high level of
overloading risk does not allow increasing the
additional production above 4 kW due to the upper
voltage limit.
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2.2.3.
Network planning for neighbourhood
Transformer is allowed to
be operated up to 120% of
its nominal capacity
Figure 4. Additional production and consumption at every node of the network.
The described method for determining the
consumption and production that can be added at
every node is deployed for all the nodes of the use
case in Figure 1. Figure 4 shows the additional
production and consumption that can be added at
every node of the network while the voltages remain
within the limits and the transformer is operated up to
120% of its nominal capacity. Note that the given
values in Figure 4 indicates the amount of
consumption / production that can be added for every
node independent of other nodes. For instances, the
addition of 42 kW of production in node 104 raises the
voltage of this node to its upper limit without additional
production at other nodes of the network. Similarly, for
the consumption side, by adding 45 kW of
consumption at node 104 the network reaches to its
limit, without additional consumption at other nodes.
For this network, it is observed that the transformer
loading is the limiting factor for addition of
consumption, whereas the upper voltage limit is the
binding factor for additional production.
Figure 5. Existing voltage distribution at node 102 (left), voltage distribution at node 102 by adding 20 kW of
production (right).
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2.2.4. Advantages of GridEye control for
network planning
The GridEye capability to control the productions /
consumptions can provide important advantages for
the network planning through the management of
voltages and congestions, and consequently
postponing of expensive grid reinforcements.
For instances, the distribution of voltage at node 102
for one year of measurements is shown in Figure 5left. Adding 20 kW of production at this node results in
the new voltage distribution shown in Figure 5-right. It
is observed that the new voltage distribution deviates
the upper voltage limit (i.e. +10%) for a small number
of hours. The GridEye optimal control can be used to
curtail the production at the instances when the
voltage is higher than the allowed limits. In this way,
the 20 kW production can be installed at node 102 and
the owner can benefit from its installation while the
system operator is ensured about the secure
operation of grid without high grid reinforcement
expenditures.
For more information please contact:
DEPsys SA
Route du Verney 20B
1070 Puidoux, Switzerland
Phone : +41 21 546 23 05
Omid Alizadeh-Mousavi
R&D Director
[email protected]
Antony Pinto
Electrical Engineer
[email protected]
Joël Jaton
Chief Technology Officer
[email protected]
www.depsys.ch
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