SNIPPETS ON POWER SYSTEM RESILIENCE AND MICROGRIDS - ANY POTENTIAL FOR SUB-SAHARAN AFRICA?

 

The dominant Electric power generation technology in Sub-Saharan Africa, Malawi inclusive, is hydropower. Hydropower accounts for more than two thirds of the total power generated in the region (with the exception of South Africa). Hydropower generation mainly depends on runoff resources, which are themselves dependent on precipitation. The global and local risks of climate change pose a great risk to hydropower generation sector. Like most of sub-Saharan Africa, Central Africa has not been spared from severe impacts of climate change, which include but not limited to dry spells, seasonal droughts, intense rainfall, riverine floods, and flash floods. These natural disasters and extreme weather-related incidents and their subsequent disruptive events on the power system are underscoring the need for enhancing the power system resilience.

Resilience is defined as the ability to reduce the magnitude and/or duration of disruptive events, which includes the capability to anticipate, absorb, adapt to, and/or rapidly recover from a potentially disruptive event. Resilience refers to low probability/high impact events e.g., earthquake and flood with a rare probability in power systems. Reliability refers to high probability/low impact events such as seasonal precipitation and accidental outages with a high probability of occurrence in power systems.

In Sub-Saharan Africa, most often uncontrolled farming practices along the hydropower station catchment area, aggravated by wanton plunder of vegetation tend to cause siltation and sedimentation at the hydro-station reservoirs. These phenomena can highly affect power station generation capacities during rainy seasons which in turn may affect the energy demand and supply ratio of the power systems. Other extreme events may include high wind speeds which may impact both Transmission and Distribution overhead power lines thereby plunging consumers into very long-duration power cuts. Other rare but probable incidents may include heavy precipitation incidents that may result in extreme flooding of the runoff resources and in the process even flooding the respective power generation stations themselves.

Considering the high-impact and the low-probable disruptions caused by extreme events, the main task for power system operation is to maintain the continuity of power services to critical loads (e.g., hospitals, police stations, and data centers) by introducing a resilient network of Microgrids. Microgrids are introduced into electric power systems for managing the widespread penetration of Distributed Energy Resources in power distribution networks. Microgrids take advantage of locally available resources, and thus could reduce their dependence on the main grid to serve on-site customers, in particular when critical circumstances are encountered.