Impact of Tropical Cyclone Idai on the Southern African Electric Power Grid

Zimba, Sydney Kadikula; Houane, Mario Jotamo; Chikova, A.

doi:10.1109/powerafrica49420.2020.9219944

Cited by 8 publications

(2 citation statements)

References 10 publications

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“…The 5 × 480 MVA generators are shown in Figure 5 as G1 to G5. Cahora Bassa is connected to the double 220 kV busbar substation in Songo, six km away [45]. Busbars are assigned to the primary AC and DC loads.…”

Section: Songo-apollo Hvdc-lcc Networkmentioning

confidence: 99%

Network Coordination between High-Voltage DC and High-Voltage AC Transmission Systems Using Flexible AC Transmission System Controllers

Ndlela

Davidson

2022

Energies

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The strategic intent of the African Union is to develop a “Smart Integrated African Electric Power Super Grid” driven by modern tools and advances in high-voltage direct current (HVDC) engineering and flexible alternating current technology systems (FACTS), which is central in supporting Africa’s sustained economic growth and development. The southern African region, including South Africa, is beset by the critical challenges of perennial load-shedding, which impedes economic growth and aggravates unemployment. This has led to the insecurity of electricity supplies and degraded the quality of life. The parallel operation of high-voltage direct current (HVDC) and flexible AC technology systems (FACTS) controllers is gaining traction as system conditions become more complex, such as weak power networks which requires increased stability requirements, resulting in load-shedding and power outages. These adversely affect business productivity and adversely affect GDP and economic growth. Thus, the application of innovative technologies such as HVDC links can stabilize weak power systems. It is established that HVDC delivery systems reduce losses in long transmission lines transporting bulk power compared with high-voltage alternating current (HVAC) transmission lines for power wheeling. This paper evaluates the parallel operation of the Cahora Bassa 1414 km bipolar HVDC link and a weak parallel 400/330 kV alternating current (AC) link. It demonstrates the use of FACTS controllers to enhance the technical performance of an existing network, such as voltage control, and technical loss reduction. It combines an HVDC line commutated converter (LCC) and HVAC transmission lines, in hybrid notation to increase the voltage stability of the system by controlling the reactive power with a Static Var Compensator (SVC). These modern tools can increase the transmission power controllability and stability of the power network. In this study, HVDC–LCC was used with a setpoint of 1000 MW in conjunction with the 850 MVAr SVC. The results show that the technical losses were reduced by 0.24% from 84.32 MW to 60.32 MW as Apollo 275 kV SVC was utilized for voltage control. The network analysis was performed using DIgSILENT PowerFactory software that is manufactured by DIgSILENT GmbH at Gomaringen, Germany

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Section: Songo-apollo Hvdc-lcc Networkmentioning

confidence: 99%

Network Coordination between High-Voltage DC and High-Voltage AC Transmission Systems Using Flexible AC Transmission System Controllers

Ndlela

Davidson

2022

Energies

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“…The event resulted in a cholera outbreak with over 6500 confirmed cases, which was subsequently contained by a vaccination programme of over 800,000 people [15]. The event also impacted the power grid in Southern Africa due to damaged infrastructure in Mozambique as the country exports electricity to the neighbouring countries [16]. Land degradation was indicated by a notable decrease in the Normalized Difference Vegetation Index (NDVI) following the event [17].…”

Section: Introductionmentioning

confidence: 99%

Sensitivity of Tropical Cyclone Idai Simulations to Cumulus Parametrization Schemes

et al. 2021

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Weather simulations are sensitive to subgrid processes that are parameterized in numerical weather prediction (NWP) models. In this study, we investigated the response of tropical cyclone Idai simulations to different cumulus parameterization schemes using the Weather Research and Forecasting (WRF) model with a 6 km grid length. Seventy-two-hour (00 UTC 13 March to 00 UTC 16 March) simulations were conducted with the New Tiedtke (Tiedtke), New Simplified Arakawa–Schubert (NewSAS), Multi-Scale Kain–Fritsch (MSKF), Grell–Freitas, and the Betts–Miller–Janjic (BMJ) schemes. A simulation for the same event was also conducted with the convection scheme switched off. The twenty-four-hour accumulated rainfall during all three simulated days was generally similar across all six experiments. Larger differences in simulations were found for rainfall events away from the tropical cyclone. When the resolved and convective rainfall are partitioned, it is found that the scale-aware schemes (i.e., Grell–Freitas and MSKF) allow the model to resolve most of the rainfall, while they are less active. Regarding the maximum wind speed, and minimum sea level pressure (MSLP), the scale aware schemes simulate a higher intensity that is similar to the Joint Typhoon Warning Center (JTWC) dataset, however, the timing is more aligned with the Global Forecast System (GFS), which is the model providing initial conditions and time-dependent lateral boundary conditions. Simulations with the convection scheme off were found to be similar to those with the scale-aware schemes. It was found that Tiedtke simulates the location to be farther southwest compared to other schemes, while BMJ simulates the path to be more to the north after landfall. All of the schemes as well as GFS failed to simulate the movement of Idai into Zimbabwe, showing the potential impact of shortcomings on the forcing model. Our study shows that the use of scale aware schemes allows the model to resolve most of the dynamics, resulting in higher weather system intensity in the grey zone. The wrong timing of the peak shows a need to use better performing global models to provide lateral boundary conditions for downscalers.

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