Figure 1: Simple lay out of a Micro-grid system (Image credit: Mr Sethi, UPES)
What is Micro-grid?
A Micro-grid is a stand-alone small transmission and distribution network which leverages on decentralized distributed power generation systems and exploits locally available resources. In a way, it is a self-sustained power system which serves various electrical loads in a radial distribution network and can operate in a centralized grid-tied or completely isolated mode.
Figure 1 (Source: UPES) depicts a simple sketch a Micro-grid network. As shown, the network rely on distributed renewable energy (DRE) technologies such as solar PV, biomass or wind coupled with energy storage systems and feed power to local loads through a distribution system. The micro-grid operations can be monitored and handled by remote automated system such as a controller. On consumer side the system allow the usage of advanced metering system through which users’ bills can be generated and typical O&M can be scheduled.
Micro-grids thrive in areas that are remote and lack access to centralized electric grid. In such areas, expanding the central grid proves a comparatively expensive proposition and can be done away with the exploitation of local DRE resources through micro-grid network. Initially the cost of energy service through micro-grid in such areas may prove higher but from an opportunity cost perspective such network remains more attractive than the conventional grid or no power.
Micro-grids can employ various DRE technologies and operating parameters vary accordingly. Economically, technologically and operationally there are many issues which need to be accounted before practical implementation of such a network. Those issues are to be evaluated through economics analysis, power control strategies, grid connection issues, stability and protection issues, operation frameworks, consumer acreage, tariff mechanism, billing and revenue collection methods etc.
There are many concurrent benefits of a micro-grid. Firstly, it helps in exploitation of local renewable energy resource through DRE based technologies whose deployment may see harnessing clean power generation instead of polluting fossil fuel based generation. It also helps in mitigating global greenhouse gas emission and improved air quality issues locally. In addition, micro-grid can stand as an auxiliary power supplier during hours when grid power is unavailable. Such network can also improve the reliability as well as quality of power delivered. For remote areas where there is no access to conventional grid, micro-grids can be a real boon for the local community since access to reliable energy can boost (especially rural) communities’ socio-economic development.