Grid integration of renewables: challenges and solutions

Exponential growth in the energy demand on account of rising population and economic growth, increasing apprehensions of energy security coupled with climate change and global warming concerns are some of the major drivers for pushing the renewable energy (RE) to the top of the energy portfolio. Among various renewable energy resources, wind and solar PV systems are experiencing rapid growth since 2010. By the end of 2016, the world total capacity of wind power generation was 487 GW and that of solar PV was 303 GW, aggregating to a penetration level of 4.0% and 1.5% respectively. Global renewable energy penetration till December 2016, excluding conventional hydro share (of 16.6%) was only around 8.0%. However, many countries have set target of 30% RE based electricity generation by 2030. India has an ambitious target of achieving 175 GW of RE power by 2022, with 100 GW from solar, 60 GW from wind, 10 GW from biomass and 5 GW from small hydro. Power generation from renewables often takes place through distributed generation (DG). These units, mostly located in remote locations, are not centrally planned or dispatched, and are usually connected to distribution grids at LV or MV levels. In few cases, large capacity RE generation are also connected to transmission networks. As a result, the power generation structure is moving from the large, centralized plants to a mixed generation pool consisting of traditional large plants and many smaller DG units. Most of the RE generators have electrical characteristics that are different from the synchronous machines. Since a large group of DG technologies use power electronics converters for grid connectivity, they introduce many technical issues related to the operation, control and protection of the power system, impacting generators, transmission system and consumer devices. This paper presents some of the technical issues and challenges that need to be addressed for the effective grid integration of RE based power generators so that eventually our reliance on polluting and expensive fossil based hydrocarbon driven power generation can be reduced substantially.