No abstract

No abstract

No abstract

No abstract

The world's energy consumption and power generation demand will continue to rise. Furthermore, the bulk of the energy resources needed to satisfy the rising demand is far from the load centers. The aforementioned requires long-distance transmission systems and one way to accomplish this is to use high voltage direct current (HVDC) transmission systems. The main technical issues for HVDC transmission systems are loss of synchronism, variation of quadrature currents, amplitude, the inability of station 1 (rectifier), and station 2 (inverter) to either inject, or absorb active, or reactive power in the network in any circumstances (before a fault occurs, during having a fault in network and after a fault cleared), and the variations of power transfer capabilities. Additionally, faults impact power quality such as voltage dips and power line outage time. This paper presents a method of overcoming the aforementioned technical issues using voltage-source converter (VSC) based HVDC transmission systems with SCADA VIEWER software and dynamic grid simulator. The benefits include having a higher capacity transmission system and proposed best method for control of active and reactive power transfer capabilities. Simulation results obtained using MATLAB validated the experimental results from SCADA Viewer software. The results indicate that the station's rectifier or inverter can either inject or absorb either active power or reactive power in any circumstance. Also, the reverse power flow under different modes of operation can ride through faults. At a 100.0% power transfer rate, the rectifier injected 775.0 W into the network. At a 0.0% power transfer rate, the rectifier injected 164.0 W into the network. At a −100.0% rated power, the rectifier injected 1264.0 W into the network and direction was also changed.

Access to energy is among the key pillars to socioeconomic and improved life style. The East African Community (EAC) countries, also members of sub-Saharan Africa, are among countries with enough energy resources but still struggling with low electricity access, and the lower proportion of citizens with electricity access challenges such as expensive tariff, frequent blackouts, and unreliable service still persists. Diesel technology is among the easy and fast installation technologies for a location with an urgent need of electricity while solar is a clean technology with free fuel. Considering the diversity of electricity tariffs, cost of diesel fuel, and suitability to solar energy exploitation in EAC, this paper intends to provide a technoeconomic analysis for reliable, affordable, and sustainable energy system in the region. A daily load of 94.44 kWh recorded from averaging electricity bills of a luxury house in Kigali, Rwanda, is used as research object, and HOMER simulations are carried on considering the level of such daily load being supplied by either (a) diesel generator, (b) solar + diesel technology, (c) PV + battery storage, or (d) PV + battery   storage + grid system in each member country of the EAC. The results show that (a) solar energy is a feasible and applicable technology for energy generation for the whole six EAC countries; (b) for South Sudan, if it is a standalone system, the diesel technology is less costly than solar technology; however, solar energy can still be recommended to be adopted as it has no gas emissions; (c) except South Sudan, PV + battery storage technology is found to be more affordable and cleaner than any technology including diesel; and (d) the option of connecting PV + battery storage to the grid is found more economical for locations where grid interaction is possible because their levelized electricity costs (LCOE) are lower than the real electricity tariffs currently in use within each of the six EAC countries. The solar energy system with battery storage (both off-grid and grid connected) proposed in this research can lead to an efficient increase of national energy resource exploitation in the EAC countries, resulting in reliable, affordable, and sustainable energy access to all the citizenry of the EAC.

Renewable energy exploitation is among the development strategies set by the government of Rwanda on the roadmap to 2023/2024 universal electricity access and the United Nations plans by 2030. Numerous previous studies on clean energy technologies in Rwanda have mostly focused on households' usage but there are currently no studies describing the feasibility of clean energy technologies for financial institutions. The skepticism on renewable energy in Africa was previously reported by some personnel. Having realized that most SACCOs (Savings and Credit Co-Operatives) in Rwanda use diesel technology for backup/emergency electricity supply, taking consideration of abundant solar resources in Rwanda, having seen the viability and feasibility studies from other countries of renewable energy for different institutions (financial included); this work uses the HOMER Energy Software and the electricity load profile of a typical SACCO in Rwanda to analyse the affordability and viability of on-site renewable energy generation for SACCO in Rwanda. The results reveal that a solar PV system with storage can be the optimal solution (with levelized cost of electricity (LCOE) of 0.713 $/kWh which is cheaper than 0.73 $/kWh for diesel technology) for SACCOs located in both off-grid areas and grid-connected areas (with 0.041 $/kWh LCOE which is lower than the current electricity tariff in Rwanda). The findings in this work can serve as basic tools/materials for policy drafters in Rwanda on how financial institutions can contribute to climate change mitigation through self-renewable energy exploitation.

No abstract