HVDC grids are a promising alternative for the expansion of the existing AC grid. They are interesting for the integration of large-scale renewable energy sources, connecting high power offshore windfarms, interconnecting new market areas, including asynchronous AC grids and off-grid communities, and they can even provide ancillary services to the AC system. It is expected to create a more reliable and flexible transmission grid using HVDC grids. However, their development will require, among other technologies, DC-DC conversion systems. Although the DC-DC conversion techniques are well understood in low and medium voltage, a specific review on the approaches for high voltage is needed. This paper presents an overview of the DC-DC power converters dedicated to HVDC proposing a classification based on their structure. Two large families are established: those which provide galvanic isolation, and those which do not. Several sub-families are also proposed. An overview of the main HVDC applications that can be targeted with each family is also presented, highlighting the main converter requirements for each application case.

A new 3-D power module dedicated to SiC mosfet is presented. It is based on printed circuit board embedded die technology and is compared with a standard power module. After considering the characteristics that contribute to optimal switching performances from the packaging point of view, both modules are characterized in terms of switching behavior and electromagnetic interference emissions. The results show better performances of the 3-D embedded die module with stray inductances below 2 nH and two times less common mode noise.

The rural electrification of Sub-Saharan Africa and South-East Asia is crucial to end the energy poverty in which around 1 billion people are trapped. Swarm electrification, i.e., the progressive building of decentralized and decarbonized electric infrastructure in a bottom-up manner, tackles rural electrification challenges by quickly providing modern and reliable electricity services to unelectrified communities while fostering local socio-economic development. This paper follows the technological approach of this electrification model and presents the development of a DC microgrid with decentralized production and storage suitable for rural electrification. This DC microgrid aims at interconnecting nanogrids, small collective autonomous power units composed of a solar panel and a lead–acid battery for 4 to 6 households, to increase the electrical services brought to the community and enhance the economic sustainability of this rural electrification model. The design of the proposed microgrid as well as its control algorithm are thoroughly addressed and tested from software simulations and experimental testing to field deployment in Madagascar. Extensive software, experimental and field-tests results are illustrated, and the microgrid design feedback is given. This paper overall validates the proper operation of the proposed microgrid, confirming the technical feasibility of the swarm electrification approach.

To facilitate the transformation from conventional power systems towards smart grids, the concept of microgrids has been widely applied in practice, serving as the medium to accommodate renewable generators. One crucial problem is the stability associated with microgrids. This paper proposes a converter-based power system stabilizer (CBPSS), acting as a supplementary control loop, to enhance the stability of the islanded microgrids. The goal of the proposed CBPSS is to stabilize the critical microgrid mode with the generation of a damping torque, and it is achieved with the identification of the forward loop from the CBPSS to the microgrid. Then, the parameters of the proposed CBPSS can be designed accordingly to compensate the phase lag of the identified forward loop. Besides, an eigenvalue-mobility-based method is presented to identify the optimal installation location of the CBPSS in microgrids. As a consequence, the maximum stabilizing effect can be realized with the least control effort. Finally, modal analysis and time-domain simulations as well as hardware experimental results confirm the effectiveness of the proposed method.

The cascaded control approach is widely used to control the Modular Multilevel Converter (MMC). Such approach allows to manage all MMC state variables in a decoupling manner based on modes separation. This separation introduces conditions related to control objectives response time resulting in a slow dynamic. This will limit the use of the potential of MMC energy that is considered as a freedom for AC and DC grids ancillary services. On another side, robustness properties for a given control are also of a great interest when considering unmodelled uncertainties and disturbances. Starting from these requirements, a linear feedback dead-beat control is proposed in this paper to accelerate the inner loops and consequently the outer ones (control objectives). The proposed control, based on exact discrete-time model of the MMC in which the sampling period is considered a priory in the control design, is synthetized by taking into account the control outputs saturation. The stability proof of the control and the robustness analysis as well as experimental results under fault grid operations highlighted on small scale MMC will be presented in this paper. The comparison with a continuous-time Sliding Mode Control shows the advantage of the proposed control regarding the response time and undesired oscillation reduction

Highlighted by the United Nations sustainable Development Goals to ensure universal access to clean, reliable, and modern energy services by 2030, the world is increasingly becoming concerned by energy poverty and its consequences on human development and the environment. Yet, even if numerous initiatives and a significant amount of money are directly addressed to tackle the energy-access challenges, a billion people are still denied access to basic and modern electricity services, especially in rural areas of sub-Saharan Africa and Southeast Asia. In the past two decades, the African continent has seen an encouraging improvement as the number of people gaining access to electricity rose from 9 million per year between 2000 and 2013 to 20 million per year between 2014 and 2019, outpacing population growth for the first time. However, most of those recent improvements are restricted mainly to urban and peri-urban areas of a small number of countries located in eastern or western Africa. Also, the population without access to electricity in Africa is expected to increase in the coming years following the health crisis and economic downturn caused by COVID-19. This definitely proves the fragility and poor resilience of the electrification solutions favored today. While grid extension and conventional microgrids suffer from low inclusivity and replicability, solar home systems are only a stopgap measure and fail to boost socioeconomic development. A third way must be proposed to combine quick and affordable access to basic electricity services and community uplift through socioeconomic development, answering the two greatest challenges that developing countries are struggling to cope with today. With this objective in mind, Nanoé, a French–Malagasy social company, is developing the lateral electrification model , based on the collaborative and progressing building of electric infrastructures, which is presented in this article, first from a general point of view and then through a focus on Nanoé’s experience in Madagascar.