IEEE Power & Energy Magazine - March/April 2017 - 54

Legend
Substation
MV Line
MV/LV Transformer
LV Line

500

1,000 1,500 2,000 m

figure 5. A real distribution network.

3,000
2,500
2,000

2,500

1,500

2,000

1,000

1,500

500

1,000

500

0
20
0
40
0
60
0
80
0
1,
00
1, 0
20
1, 0
40
1, 0
60
1, 0
80
2, 0
00
0

Number of Customers

3,000

2, 0
00
4, 0
00
0
6,
00
8, 0
0
10 00
,0
0
12 0
,0
14 00
,0
0
16 0
,0
18 00
,0
00

kWh per Month
(a)
3,000
2,500

Number of Customers

3,000

2,000

2,500

1,500

2,000

1,000

1,500

500

1,000

500
0

8 10 12 14 16 18 20

20
40
60
80 100
kW Peak of PV System
(b)

figure 6. Histograms of (a) energy consumption and (b)
defined PV system capacity.
54

ieee power & energy magazine

introduces the PV penetration level (in kilowatts) and
the tool defines the location and optimal capacity of
PV systems based on an economic assessment. The report released by the Ministry of Energy and Environment details this economic evaluation. The input data
of this OpenDSS-based distribution network analyzer
correspond to the electrical models created using Tool 2
as well as the active and reactive power demanded by
the circuit (information that is also provided by the local DNO). The latter is used in a load allocation algorithm implemented as part of this third tool and in
which the demand of the circuit is matched with that
of the loads plus losses. This tool can be run as many
times as needed to assess each of the impact studies
and PV penetrations of interest. Currently the tool can
run snapshot, daily, yearly and harmonic power flows,
as well as short circuit studies. The corresponding results are stored as layers in QGIS so that they can be
used by the visualization tool.
✔✔ Tool 4-Visualization of impacts: The fourth tool
enables DNOs to visualize the results of the impact
studies within QGIS, making the identification of
lines and buses with problems easy and efficient. So
far, a few different ways to visualize results have been
implemented: color-based ranking of bus voltages and
line loading, heat maps for identifying areas with voltage and/or line loading problems, the animation of
results through a defined period, and element-specific
pop-up windows with further results (e.g., active and
reactive power, loading). This tool can be used immediately after Tool 3 to visualize the corresponding
new results.
To increase the acceptability of the tools by Costa Rican
DNOs, a user-friendly graphical interface was designed for
each of them. In addition, the open-source nature of the tools
makes possible the implementation of further improvements
and/or changes to meet specific requirements of the DNOs.
The tools are currently being used in different types of distribution networks, from rural to urban, so their effectiveness in solving most of the particularities of Costa Rican
networks is constantly being enhanced.
To illustrate the use of the tools, the large urban network
presented in Figure 5 will be used. It supplies over 5,000
customers (MV and LV) and is located within the concession area of CNFL. The first tool, which uses as input only
the GIS data related to the distribution network, solved all
connectivity issues and reported all transformers with inappropriate capacities (0 kVA), which were manually changed
based on CNFL practices. The corrected data was then combined with the meteorological (i.e., solar irradiance) and socioeconomic data to produce the combined GIS data, which
then serve as input to the electrical models.
The second tool translated the 34.5-kV distribution circuit available in the GIS to an OpenDSS model. This model
contains 1,638 MV buses, 827 MV line sections, 204 MV/LV
march/april 2017

Table of Contents for the Digital Edition of IEEE Power & Energy Magazine - March/April 2017