According to an analysis by the World Bank, about 400 million Indians lack either continuous or even any access to electricity because of fossil fuel shortages and/or geographical isolation particularly in rural areas or forest-covered regions1. The absence of electricity has led to challenges in earning a living, educating children, and connecting with the outside world.
Decentralized Electricity Generation
Connecting the whole country to the main electricity grid might take several years and may not be an economically viable solution. A more practical alternative is local energy generation and distribution. One option for this is to power individual houses with stand-alone solar photovoltaic (PV) systems. In such systems, each house is independently powered by a small PV system consisting of a solar panel, a charge controller, a battery, and an inverter.
When FluxGen Technologies, a renewable energy technology company, visited villages situated in inner reserve forest areas of the North Karnataka state in India, we found that because of the dense forest growth, conventional electricity grid was not feasible. We also saw that the stand-alone solar PV systems installed for each house a few years back were nonfunctional. After talking with the local villagers, we found that their illiteracy and lack of knowledge about these systems and their maintenance have resulted in a system breakdown.
Upon realizing this, we developed an efficient and cost-effective solution for decentralized electricity generation using solar PV panels. Our main goals for our system, called the Smart Renewable Energy Micro-Grid2, were to achieve higher mean time between failure of the implemented system, remote monitoring of the system’s health and performance, generation of system diagnostics, and assurance of proper safety using sophisticated engineering methods. Financially, the micro-grid offers the inherent advantage of pooling (like carpooling) over stand-alone solar electrification. Working with a single universal inverter for all houses is more economical than using stand-alone PV systems. Furthermore, a single high-power inverter offers greater efficiency than individual low-power inverters.
System Setup
Figure 1 shows the schematic model of the Smart Renewable Energy Micro-Grid. The flexible, scalable system can provide electricity for just a few houses or a whole town. The PV panels are wired together in a series of parallel combinations depending on the solar hybrid inverter specifications. The solar inverter features maximum power point tracking (MPPT), which ensures efficient power extraction from panels and stores the power in lead acid batteries. The inverter converts the DC power in batteries to AC power, and the programmed hardware that forms the control center distributes the power to houses. Smart meters are installed at the users’ end. These communicate energy consumption information to the control system using industrial standards communication protocols. The solar hybrid inverter enables synchronization with windmills or diesel generators designed to handle future increases in energy demand.
India is already using several micro-grids powered by PV panels. What makes our renewable energy micro-grid different is its ability to interface with the sbRIO-9641, which we programmed using a graphical system design platform that features LabVIEW software. Understanding the criticality of the entire control system, we used the sbRIO-9641 to enable parallel data processing, periodic system health monitoring, data logging, failure mode effect analysis, and data transfer to remote servers via wireless communication. This enables remote system control through the Internet. With its integrated 1 million gates, reconfigurable I/O (RIO) FPGA, a real-time OS (VxWorks RTOS) featuring Ethernet connectivity, and numerous analog and digital I/O ports, the sbRIO-9641 provides the most versatile stand-alone platform for the implementation and operation of customized protocols and algorithms/programs as required by specific projects.
The sbRIO-9641 monitors the solar PV array and MPPT performance including periodic updating of power generation data in graphs and spreadsheets3. To monitor the solar inverter performance, we interfaced the inverter’s input and output with the sbRIO-9641. By implementing certain mathematical computations, we record and graph inverter conversion efficiency and the variation of total load power consumed in a day.
Batteries are used to store electricity, but when they are mishandled, their operation may become unpredictable. To continuously inspect battery functionality, the sbRIO-9641 generates graphical data on battery power levels and charging/discharging states and maintains a battery service log record. If the sbRIO-9641 detects a false operation, it immediately disconnects the batteries. This extends battery life.
To distribute the stored energy as required by all users, the micro-grid uses a predictive power supply capping algorithm. The algorithm predicts the possible power capping for individual houses depending on the amount of energy harvested per day in batteries. Manual control is also provided for this. If a specific user consumes too much power, the sbRIO-9641 automatically disconnects that particular user’s line. It also notifies the user about the power cut through a message sent over a mobile network. By reducing the user’s energy demand, the micro-grid can restore power to the user. The smart energy meters send the individual power consumption data to the sbRIO-9641. All users are automatically informed about their weekly usage rates so they can adjust their power consumption and conserve it accordingly. Applicable billing details can be communicated to the user monthly through SMS.
All of the computational data, data analysis, graphical data, and logged data metrics in spreadsheets are updated on the Internet via mobile network communication (mobile network penetration is much greater than electric grid penetration in India). Interfacing Single-Board RIO’s Ethernet power with a GSM modem enhances of the system’s ability to access real-time data in any part of the world, 24/7, using the Internet.
In a nutshell, using Single-Board RIO and LabVIEW has enabled us to add numerous features to a micro-grid, which makes it smarter. The system’s data logs can further help provide good data points for researchers in the fields of renewable energy and energy-sharing micro-grids. The logs also may be useful in solving some of the social science problems faced by those in the remote villages of India.
This micro-grid is currently running in a village called Mendil located in the forest-covered area of Northern Karnataka state, India. A decentralized renewable energy solar PV plant powers sources of light and electricity to conduct household business for wealth generation and to educate children. It also powers irrigation systems for agriculture and entertainment systems (television, disc players, and radios) for leisure time and keeping up with news outside the village. The feeling of satisfaction and happiness among the people in Mendil has inspired us to implement similar smart micro-grids in the future.
Our thanks to NI for developing such powerful embedded devices and programming software that we can use to deliver all-in-one solutions to meet the energy needs of several remote areas in India. We are also grateful to the Planet NI program for funding our technology and providing training to our engineers in the past, which helped made this work possible. Without NI’s technology, the effort and design time required to develop the Smart Renewable Energy Microgrid system would have been greater.
We believe that, in the long run, our work will lead to wider access to reliable, cost-effective, and eco-friendly electricity by the people who cannot connect to the mainstream electric grid in India
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Reference
1. The World Bank, Energy Facts – What is the energy challenge in developing countries?
http://siteresources.worldbank.org/INTENERGY/Publications/20269216/energybrochure.pdf
2. Mutha, Abhishek. “Smart Renewable Energy Microgrid.” Electronics for You.
http://electronicsforu.com/electronicsforu/circuitarchives/view_article.asp?sno=1517&title%20=%20Smart+Renewable+Energy+Microgrid&id=12414&article_type=5&b_type=new
3. Hari, D.K. “Building an Embedded Renewable Energy Performance Monitor for Rural India.” National Instruments.
http://sine.ni.com/cs/app/doc/p/id/cs-15022
Author(s):
Ganesh Shankar – FluxGen Engineering Technologies Pvt. Ltd.
KaustubhKarnataki – FluxGen Engineering Technologies Pvt. Ltd.
Tejas Kumar N – FluxGen Engineering Technologies Pvt. Ltd.
Shodhan S – FluxGen Engineering Technologies Pvt. Ltd.
