Advances in Phytochemistry, Textile and Renewable Energy Research for
Industrial Growth – Nzila et al. (Eds)
© 2022 Copyright the Author(s), ISBN: 978-1-032-11871-0
Open Access: www.taylorfrancis.com, CC BY-NC-ND 4.0 license
Mitigation of power outages in Rwanda
Boniface Ntambara & Paul M. Wambua
Department of Manufacturing, Industrial and Textile Engineering, School of Engineering, Moi University, Eldoret,
Kenya
S. Simiyu Sitati
Department of Electrical and Communication Engineering, School of Engineering, Moi University, Eldoret, Kenya
Jean B. Byiringiro
Siemens Mechatronics Certification Center, Dedan Kimathi University of Technology, Nyeri, Kenya
ABSTRACT: Power outages in Rwanda severely affected most of the Western and Northern grids of Rwanda in
2018, 2019, and 2020. This paper studied the causes and mechanism of power outages and developed the methods
and techniques to mitigate the power outages. Two operational elucidations such as a balanced steady state
control system and an optimal overcurrent relay settings model for operational HV substation relay coordination
have been proposed and developed. The sustainable synchronism between Rwanda Power system regions was
becoming difficult over time due to load disturbances/changes. The under and over frequency, and under and over
voltage load shedding techniques have been taken to reduce and mitigate the system outages. However, in order
to minimize power outages in emergency regions, these systems have been extended in different regions such
as Western and Northern grids which need to be maintained. The PID controllers for enhancing and mitigating
the power outages have been developed in single and two area power systems. The load disturbance injection
of 50MW has been created. Matlab/Simulink 2017a have been used to simulate the frequency load control,
overcurrent relay, and power system models. The relay coordination and settings for a 110/15kV substation with
a 17156.48A and 13987.10A of maximum and minimum fault currents, plug setting (PS), and actual operating
time of the different relay have been ascertained and modeled. The simulation results have been compared with
and without PID controller installation in the power system and it has been shown that the frequency response
characteristics for single and two area networks in western and northern grids have been minimized to 0.0 Hz,
0.0 Hz, and 2.5 sec for overshoots, steady state errors, and settling times after cascade outages respectively. The
overcurrent substation relays have been coordinated with the expected times of 0.0924–0.0622sec, 0.0949–0.0720
sec, and 0.0764–0.0661sec for extremely, very, and standard inverse relay characteristics, respectively.
Keywords: Overcurrent relay; Frequency Load Control; Power Outages; Matlab/Simulink 2017a; PID
controllers; power system stability.
1 INTRODUCTION
The power outages in Rwanda clearly demonstrated the
relevance of the severe problems of loss of supply and
MW loss. The situation is further complicated by the
necessity for the power system to survive under competition and uncertain conditions. Based on a detailed
power outage analysis, the dangerous overload of the
transmission grid is held as a key element initiating the
development of many cascading processes (Zalostiba
2020). The outages which occurred in Rwanda from
2018 to June 2020, have mostly proven severe and very
significant. It has been reported that during the power
outages, about 5 million people have been affected in
5 districts from the Northern region and 5 districts
from the Western region, and 70 MW of loads were
lost, which is about 27% of the total load. Some other
major outages began when lightning and overloading caused the tripping of a major transmission line
between Western and Northern grids. Research work in
these two regions are aimed at predicting voltage collapse and voltage overload with a view to controlling
and reducing its occurrence on power system networks
(Weiss 2019).Most of power outages are triggered by
distribution circuit failure (Wang L. 2016). Conventionally overcurrent relay settings are provided based
on the full load current of power system components.
Load frequency control was based on many power
control advanced concepts and the dynamic behavior of many industrial plants is heavily influenced
DOI 10.1201/9781003221968-7
51
Industrial Growth – Nzila et al. (Eds)
© 2022 Copyright the Author(s), ISBN: 978-1-032-11871-0
Open Access: www.taylorfrancis.com, CC BY-NC-ND 4.0 license
Mitigation of power outages in Rwanda
Boniface Ntambara & Paul M. Wambua
Department of Manufacturing, Industrial and Textile Engineering, School of Engineering, Moi University, Eldoret,
Kenya
S. Simiyu Sitati
Department of Electrical and Communication Engineering, School of Engineering, Moi University, Eldoret, Kenya
Jean B. Byiringiro
Siemens Mechatronics Certification Center, Dedan Kimathi University of Technology, Nyeri, Kenya
ABSTRACT: Power outages in Rwanda severely affected most of the Western and Northern grids of Rwanda in
2018, 2019, and 2020. This paper studied the causes and mechanism of power outages and developed the methods
and techniques to mitigate the power outages. Two operational elucidations such as a balanced steady state
control system and an optimal overcurrent relay settings model for operational HV substation relay coordination
have been proposed and developed. The sustainable synchronism between Rwanda Power system regions was
becoming difficult over time due to load disturbances/changes. The under and over frequency, and under and over
voltage load shedding techniques have been taken to reduce and mitigate the system outages. However, in order
to minimize power outages in emergency regions, these systems have been extended in different regions such
as Western and Northern grids which need to be maintained. The PID controllers for enhancing and mitigating
the power outages have been developed in single and two area power systems. The load disturbance injection
of 50MW has been created. Matlab/Simulink 2017a have been used to simulate the frequency load control,
overcurrent relay, and power system models. The relay coordination and settings for a 110/15kV substation with
a 17156.48A and 13987.10A of maximum and minimum fault currents, plug setting (PS), and actual operating
time of the different relay have been ascertained and modeled. The simulation results have been compared with
and without PID controller installation in the power system and it has been shown that the frequency response
characteristics for single and two area networks in western and northern grids have been minimized to 0.0 Hz,
0.0 Hz, and 2.5 sec for overshoots, steady state errors, and settling times after cascade outages respectively. The
overcurrent substation relays have been coordinated with the expected times of 0.0924–0.0622sec, 0.0949–0.0720
sec, and 0.0764–0.0661sec for extremely, very, and standard inverse relay characteristics, respectively.
Keywords: Overcurrent relay; Frequency Load Control; Power Outages; Matlab/Simulink 2017a; PID
controllers; power system stability.
1 INTRODUCTION
The power outages in Rwanda clearly demonstrated the
relevance of the severe problems of loss of supply and
MW loss. The situation is further complicated by the
necessity for the power system to survive under competition and uncertain conditions. Based on a detailed
power outage analysis, the dangerous overload of the
transmission grid is held as a key element initiating the
development of many cascading processes (Zalostiba
2020). The outages which occurred in Rwanda from
2018 to June 2020, have mostly proven severe and very
significant. It has been reported that during the power
outages, about 5 million people have been affected in
5 districts from the Northern region and 5 districts
from the Western region, and 70 MW of loads were
lost, which is about 27% of the total load. Some other
major outages began when lightning and overloading caused the tripping of a major transmission line
between Western and Northern grids. Research work in
these two regions are aimed at predicting voltage collapse and voltage overload with a view to controlling
and reducing its occurrence on power system networks
(Weiss 2019).Most of power outages are triggered by
distribution circuit failure (Wang L. 2016). Conventionally overcurrent relay settings are provided based
on the full load current of power system components.
Load frequency control was based on many power
control advanced concepts and the dynamic behavior of many industrial plants is heavily influenced
DOI 10.1201/9781003221968-7
51