Matlab 2017a/Simulink. Figure 1 demonstrates the
flowchart of power cascade outages detection and the
load–supply power imbalance control from the start
of monitoring of the power system to the provided
frequency control mechanism.
The governor regulated the turbine speed, loadsupply power and the grid frequency by starting the
turbine from a still condition and varied the load on
the turbo-generator in imbalance conditions. The 0.8%
load variation caused 1% frequency change. The rated
Figure 1. Flowchart of detection for cascade outages minimization in power balance steady system.
Figure 2. Rwanda Northern grid at Ntaruka hydropower plant without PID controller.
Figure 3. Rwanda Northern electricity grid at Ntaruka hydropower plant with PID controller.
load active power of 200 MW, nominal frequency of
50 Hz, and a sudden load disturbance of 50 MW have
occurred in both area power systems, as shown in Figures 2 and 5 for no PID installed and Figures 3 and
6 for PID installed. The single area power systems
without and with PID controllers have been computed
and modeled as shown in Figures 2 and 3. The two
area power system has been considered in unbalanced
frequency load control and the generators have been
interconnected in series with the loads fed, and the
load disturbances have been applied in area 1 and the
two power generations have been synchronized as indicated in the Figures 5 and 6. Figures 4 and 7 show the
setting values and parameters of PID controllers in a
single area, area 1 and area 2 in two area power generations, respectively. The performance characteristics
of power and frequency in two area power generations
with and without PID controllers have been observed,
recorded and plotted in Figures 10, 13–16.
2.2 Optimal overcurrent relay settings for effective
substation relay coordination
The values and parameters of grid and feeder
impedance equivalences, phase to phase fault currents, current settings of 110 kV incomer and 15 kV
outgoing feeders, and operating times for relay characteristics of the studied Rwanda power system have
53
flowchart of power cascade outages detection and the
load–supply power imbalance control from the start
of monitoring of the power system to the provided
frequency control mechanism.
The governor regulated the turbine speed, loadsupply power and the grid frequency by starting the
turbine from a still condition and varied the load on
the turbo-generator in imbalance conditions. The 0.8%
load variation caused 1% frequency change. The rated
Figure 1. Flowchart of detection for cascade outages minimization in power balance steady system.
Figure 2. Rwanda Northern grid at Ntaruka hydropower plant without PID controller.
Figure 3. Rwanda Northern electricity grid at Ntaruka hydropower plant with PID controller.
load active power of 200 MW, nominal frequency of
50 Hz, and a sudden load disturbance of 50 MW have
occurred in both area power systems, as shown in Figures 2 and 5 for no PID installed and Figures 3 and
6 for PID installed. The single area power systems
without and with PID controllers have been computed
and modeled as shown in Figures 2 and 3. The two
area power system has been considered in unbalanced
frequency load control and the generators have been
interconnected in series with the loads fed, and the
load disturbances have been applied in area 1 and the
two power generations have been synchronized as indicated in the Figures 5 and 6. Figures 4 and 7 show the
setting values and parameters of PID controllers in a
single area, area 1 and area 2 in two area power generations, respectively. The performance characteristics
of power and frequency in two area power generations
with and without PID controllers have been observed,
recorded and plotted in Figures 10, 13–16.
2.2 Optimal overcurrent relay settings for effective
substation relay coordination
The values and parameters of grid and feeder
impedance equivalences, phase to phase fault currents, current settings of 110 kV incomer and 15 kV
outgoing feeders, and operating times for relay characteristics of the studied Rwanda power system have
53