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Smart Micro-grids for rural electrification
In India, around 40,000 villages (with upto 300 households) and arguably another 250,000 to 300,000 hamlets (with households ranging from 50 to 100) remain either un-electrified or de-electrified. This lack of access has been an inhibitor of equitable economic growth for these marginalized communities. Power in India is mainly through the central grid where shortage of generation and inefficiencies in distribution has crippled supply to these villages. With increase in demand and depletion of fossil fuels, there is a peaking interest for the deployment of decentralized distributed generation in India with an emphasis in the utilization of renewable energy resources. Decentralized micro-grids help in augmenting supply including power requirement for economic sustenance, hence improving power quality and reliability.
Prima Facie, decentralized generation and distribution through micro-grids seems the obvious choice for areas that have adequate renewable energy sources, but a few key challenges listed below need to be addressed to shape an appropriate and sustainable model:
- Supply-demand gap: Unstable and non-contiguous demand coupled with intermittency being an intrinsic nature of renewable energy sources makes it hard for the Energy Supply Companies (ESCOs) to accurately estimate the size of the plant.
- Often these villages are remote and occasionally inaccessible, making it hard to monitor, thereby increasing over-head costs of businesses.
- Supply to the rural areas has always been tainted by theft. Detecting and eliminating thefts is one of the primary pre-requisites to catalyze larger scale of business investments in micro-grids.
- Estimation of demand emerging from an area in foreseeable future is an important consideration since not all loads existing in these rural communities will be willing to connect from the first day of service in the micro-grid. A good view of the community’s behavior and a grid capable of supporting addition of loads at later stage is vital.
- Revenue collection has always been an inhibitor for businesses to venture into the rural markets. A dependable metering service and a strong ground team can help resolve this challenge for the ESCOs and their investors.
- The development and utilization of smart grids with renewable sources for rural electrification could demonstrate the capability of solving the aforementioned issues. The concept of smart grids is to essentially combine information and technology with power to optimize performance in both the supply and demand side, increase productivity, enhance efficiency and stabilize the management of energy resources. Currently the general perception of smart grids is limited to the use of smart meters on the demand side. Smart grid, however, is an umbrella term that encompasses the digitization of grids to optimize current and voltage operations.
The primary components of a smart-grid are as follows:
Distribution Automation: Automation is necessary to measure and control the flow of power on a real-time basis and increase reliability. This smart-grid technology enables the operators/utilities to work power around possible trouble spots in the grid, usually with no noticeable disruption in service to the customers. For instance, if a tree were to fall on the transmission wire, shorting the line, this automation will allow better isolation of the affected section, thus reducing the impact of it to fewer customers. This also helps in the remote detection of any theft arising from any direct hook-ups onto the line or bypass of the installed meters.
Demand scheduling and switching: A key parameter that is absolutely crucial in designing a plant for rural electrification is scheduling of the vacillating demand. Usually grids are designed to cater to a flat demand curve. After the loads are scheduled to obtain a near-flat demand curve and the plant size is optimized, a fuzzy control program is coded to make load switching decisions intelligently deriving inputs from measurement algorithms using the schedule in the form of control rules. This switching happens smoothly and optimally with no visible delays and without manual intervention.
Renewable sources integration: Hybrid systems could be the best solution in certain situations for rural electrification where power is produced from different energy sources such that it meets the demand with the least possible cost while giving the highest priority to the most suitable source. Complex mathematical techniques are used to build forecasting models to manage the intermittency in generation from these sources. The VAR (Voltage-ampere reactive) optimization technology is then used to synchronize the voltage fluctuations caused in different feeders to the grids, thereby creating steady voltage profiles. These voltage fluctuations are particularly evident in renewable energy technologies like solar and wind that depend on dynamic factors like wind speed, cloud cover, moisture, dust, etc.
Advanced energy storage systems: Distributed energy systems are nothing but dispatchable energy source for systems like solar and wind, which do not produce continuous power. This essentially means storing the power generated when the demand is low to meet the demand at a later hour. Storage systems like batteries are also used to firm voltages and accommodate sudden voltage surges, particularly for cranking up large reactive loads. Storage could also be used for peak shaving or shaping a flat demand curve for an optimal plant size.
Energy efficiency: Though application of the above would ensure energy efficiency in the grid, there are other low hanging fruits that could enhance efficiency. Utilizing energy efficient appliances at the consumer-end like low watt LEDs will result in fewer chances of failure, long life and reduced power wastage for these remote customers. Low watt super-efficient appliances will aid in accommodating more loads at a later stage as and when they come alive. Typically rural consumers are skeptical of the technology in the beginning and are interested in getting connected after the grid is energized. Conductor/connector sensors and insulation leakage sensors are other smart devices that can help thwart current leakages.
Smart metering: Revenue collection is one of the key challenges perceived by the business community seeking to address the rural electrification market through micro-grids. Tampering of meters is a common phenomenon in rural India and significant research has gone into identifying some solutions on this front. Smart meters are electronic boxes having the capability of 2- way wireless communication with a database which tracks the energy usage of each customer connected to the micro-grid. The meters can either be pre-paid or post-paid depending on the community’s willingness to pay the appropriate tariff set to offset the business set-up and operational costs. These meters help in streamlining revenue collection, enhancement of service and operational efficiencies and minimization of power loss and theft.
Research, development and application of smart-grids are still in their nascent phase. It requires significant boost in terms of favorable strategies and policies to make them affordable enough for businesses to yield returns at the earliest possible time on the investment, especially for micro-grids. The Government of India through the Ministry of Power has been actively involved in development of smart grid under the various power sector reforms initiatives being undertaken.
One of the most important smart grid related national energy policy decisions in encouraging investments in information technology enabled power systems occurred as a part of Re-structured Accelerated Power Development and Reforms program (R-APDRP) in 2008. The Central Government involvement with the smart grid led to establishment of an inter-departmental task force known as the Smart Grid Task Force comprising of MOP, MNRE, CEA, PFC, DST etc.
The Government has also set-up the Indian Smart Grid Forum to encourage dialogue on smart-grids bringing in utilities, industry and academia as well. With the combined efforts of the Smart Grid Task Force and the Forum, India’s first Smart Grid Vision has been developed. This effort by various groups is promising the advent of affordable and robust smart grid systems percolating even to decentralized micro-grids in the rural setting.
Abishek Bharadwaj is a Senior Energy Analyst at a sustainability consulting firm, cKinetics.