Protection of low-voltage DC microgrids in rural electrification developments

Introduction: Developing Countries in Latin America, Sub-Saharan Africa and Asia are constantly wrestling with the issue of low electrification rates. Isolated communities (such as those in the Amazons or in the Grand Sahara) pose a real challenge for electricity operators. Due to high costs of building transmission lines, it is not possible to extend the national grids to these places. Also, these communities tend to be poverty-stricken and do not possess large purchase power.

Therefore, electric utilities are looking into alternative ways of electirifying these communities. Renewable Energy based distributed generation is by far the most promising approach since it offers sustainable, stand-alone solutions. These systems are mostly DC microgrids based on PV generation and battery storage. In rural areas there are not many electrical devices and the ones that are present used DC such as laptops, mobile phones, LED lights. Considering this fact, there is a new trend to use DC microgrids as the mainstream solution.

However, the protection systems for these DC microgrids need to be extensively investigated. There is a need for a fully automated protection that can be easily deployed and preferably monitored over communicatoin lines.

Method/Case Study: Firstly, current status of DC microgrid protection will be studied. Then, a typical DC microgrid in Rural Electrification system will be developed. Then, necessary protection requirement will be detalied and incorporated in to the automated protection system. It will be a desirable addition to model this system in power system communication standards such as IEC 61850 or Zigbee 2.0

Results/Conclusions: Rural electrification in developing and underdeveloped countries rely on trial-and-error approach. Electric utilities still do not possess much know-how on these developments. This research project will tackle an important aspect of DC microgrids used in isolated communities. Protection is a vital aspect of Power systems since it deals with human life. Furthermore, an automated and standard approach to DC microgrid protection system will make these developments much easier and feasible.