Recently, DC-powered devices such as loads (USB plugs, chargers, LED lighting) and distributed energy resources (solar photovoltaic and battery energy storage) have been increasingly used. Therefore, their connection to the grid requires AC/DC converters, which raises the question of operating part of the grid in DC in order to connect DC loads to DC producers and storage. In Cambodia, the electrification rate is only about 82% of the population in 2021 in rural areas. The objective of this work is to propose a low voltage microgrid comprehensive planning tool for electrification of developing countries. From the data collected on consumption needs, the objective is to find the optimal electrification scheme, i.e., AC or AC/DC distribution, optimal topology and distributed energy resources allocation and operation for both grid-connected and off-grid mode. A set of technical, economic, and environmental key performance indicators allows for comparison of solutions. The interest and efficiency of such a tool are illustrated on a real case study, an island area. Moreover, uncertainties on load consumption are also considered to assess the sensitivity and robustness of the proposed algorithm. The results show that, although the overall cost of the hybrid AC/DC microgrid is slightly higher than that of the AC microgrid, it allows a gradual electrification avoiding large initial investments.

A large part of the population living in rural areas of developing countries does not have access to electricity because the investment is high due to the low population density and some households cannot afford the high electricity bill. Therefore, some of them invest in small photovoltaic generation units called Solar Home System (SHS). The objective of this paper is to provide a microgrid planning methodology including grid design, optimal location and sizing of SHSs and battery energy storage in a context of rapid and low-cost electrification while waiting for a potential connection to the MV distribution grid. To solve these optimization problems, the minimum spanning tree algorithm and a genetic algorithm are selected and tested on a rural village in Cambodia.

This paper studies integrated photovoltaic (PV) into single-phase AC low voltage (LVAC) distribution for electrification in a rural village using battery energy storage (BES). The grid extension with and without the integration of PV-BES is proposed in this paper. Firstly, the minimum conductor used of the LV grid is reached with the shortest path algorithm. Then, the sitting and sizing of distributed generations are performed by using genetic algorithm (GA) and iterative technique. The comparison of grid extension in both strategies is studied thanks to actualized cost method.

This paper aims to find the optimal topology from three different case studies based on energy loss reduction. In the first stage, the shortest path (SP) algorithm is used to find the shortest distance from each load to all poles with the given location. Then, several parameters of electrical appliances used in households have been collected from the survey to generate load profiles of each household by a bottom up algorithm. There are 3 cases for the comparison based on energy loss in this research work. Case 1 is based on a Repeated ABC phase sequence (RPS ABC) which is assumed as the based case. Cases 2 and 3 are designed by phase balancing technique based on peak load and load profile, respectively. In this work, Mixed Integer Linear Programming (MILP) method has been chosen to define phase balancing in the unbalanced three-phase system. Based on the results, case 3 provides a good option for the optimal radial topology with the phase balancing technique based on energy loss.

This paper presents a new AC/DC microgrid topology as an alternative to the traditional AC network in the context of developing countries' electrification. The K-means clustering is employed to pack DC loads into a number of clusters. Next, the minimum spanning tree (MST) is applied to the clusters in order to get the minimum length of DC conductors. Hence, by using the shortest path (SP), the closest electrical poles connected to a cluster at which the AC/DC converter is placed, are found and then, balanced by the mixed-integer linear programming (MILP). Finally, the AC lines connecting all poles and clusters are designed with the MST. The optimal cost of the complete AC/DC microgrid is determined for 20 years of operation.

Planification des architectures de micro-réseaux ruraux AC/DC basse tension en présence de PV et de stockage: Récemment, les appareils fonctionnant en courant continu comme les charges (prises USB, chargeurs, éclairage LED) et les ressources d’énergie distribuées (solaire photovoltaïque et stockage d'énergie par batteries) se sont développés. Pour faire face à ces tendances technologiques, un micro-réseau AC/DC pourrait être une option pour l'électrification rurale dans les pays en développement, en particulier dans les zones éloignées ou rurales. Au Cambodge, le taux d'électrification n'est que d'environ 82% de la population en 2021 en zone rurale. L'objectif de cette thèse est de remettre en question le réseau de distribution AC traditionnel en proposant un nouveau micro-réseau hybride AC/DC dans le contexte de l'électrification des pays en développement. Pour cela, un algorithme permettant de trouver la topologie optimale du réseau basse tension AC/DC a été développé. Deuxièmement, une méthodologie générale pour le dimensionnement et l'emplacement des PVs et des batteries dans le micro-réseau hybride AC/DC est mise en place. Ensuite, les modes « connecté au réseau » et « isolé » du système sont comparés selon plusieurs indicateurs techniques, économiques, et environnementaux. Enfin, la comparaison du micro-réseau AC/DC avec des micro-réseaux entièrement AC a été réalisée sur deux cas d’étude réels (une zone rurale et une zone insulaire) et selon les deux modes possibles (connecté au réseau et isolé). De plus, l'incertitude des charges est également prise en compte afin d'observer la sensibilité et la robustesse de l'algorithme proposé. Les résultats montrent que, bien que le coût global du micro-réseau hybride AC/DC soit sensiblement plus élevé que celui du micro-réseau AC arborescent sans cluster, il permet une électrification progressive évitant ainsi de mobiliser des investissements initiaux importants.