Article
Voltage Profile and Sensitivity Analysis for a Grid Connected
Solar, Wind and Small Hydro Hybrid System
Noah Serem
1,
*, Lawrence K. Letting
2
and Josiah Munda
3
Citation: Serem, N.; Letting, L.K.;
Munda, J. Voltage Profile and
Sensitivity Analysis for a Grid
Connected Solar, Wind and Small
Hydro Hybrid System. Energies 2021,
14, 3555. https://doi.org/10.3390/
en14123555
Academic Editor: Pierluigi Siano
Received: 5 May 2021
Accepted: 26 May 2021
Published: 15 June 2021
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1
African Centre of Excellence in Energy and Sustainable Development, University of Rwanda,
Kigali P.O. Box 4285, Rwanda
2
Department of Electrical and communications Engineering, School of Engineering, Moi University,
Eldoret P.O. Box 3900-30100, Kenya; LettingLK@gmail.com
3
Department of Electrical Engineering, Tshwane University of Technology, Pretoria X680-0001, South Africa;
MundaJL@tut.ac.za
* Correspondence: noah.serem@uoeld.ac.ke
Abstract:
Due to increase in integration of renewable energy into the grid and power quality issues
arising from it, there is need for analysis and power improvement of such networks. This paper
presents voltage profile, Q-V sensitivity analysis and Q-V curves analysis for a grid that is highly
penetrated by renewable energy sources; solar PV, wind power and small hydro systems. Analysis is
done on IEEE 39 bus test system with Wind power injection alone, PV power injection alone, with
PV and wind power injection and with PV, wind and micro hydro power injection to the grid. The
analysis is used to determine the buses where voltage stability improvement is needed. From the
results, it was concluded that injection of the modeled wind power alone helped in stabilizing the
voltage levels as determined from voltage profiles and reactive power margins. Replacing some
of the conventional sources with PV power led to reduction of voltages for weak buses below the
required standards. Injection of power from more than one renewable energy source helped in
slightly improving the voltage levels. Distribution Static compensators (D-STATCOMs) were used to
improve the voltage levels of the buses that were below the required standards.
Keywords: voltage profile; V-Q sensitivity; solar PV; wind power; micro hydro; D-STATCOM
1. Introduction
The demand for electric energy is rapidly increasing and putting pressure on utilities
to expand their generation. This coupled with the need for clean energy has led to energy
demand growth. Because of this, the researchers are envisaging the power generation
technique from the renewable energy sources such as solar, hydro and wind. These energy
sources are preferred for distributed generation because of their abundance, cleanliness
and low cost [1,2]
Solar PV and Wind power systems are getting popular because of their availability
and reducing cost. However, they are intermittent in nature [
3
–
6
] and cannot satisfy power
requirements alone throughout the year. Small hydro systems are also getting interest to
generate electrical power in remote areas. The limitation to small hydro power is its poor
voltage and frequency regulation. Therefore, a reliable technique is required to maintain
constant voltage and frequency irrespective of the load and load types [7].
Grid interconnection of these renewable energy sources come with many advantages
such as [8–10]:
•
Less environmental pollution because of increased use of non- polluting
generation sources
.
• Low cost because of non- consumption of fuel.
• The power capacity of connected grids increase to meet the increase in demand.
• Improved supply security.
•
Cheaper power for consumers due to increase in power supply from cheaper sources.
Energies 2021, 14, 3555. https://doi.org/10.3390/en14123555 https://www.mdpi.com/journal/energies
