In India, the agricultural industry employs more than 50% of the work force and contributes to a bit less than 20% of the national GDP. The industry accounts for 18% of the total electricity use in Indian power sector. State utilities comprise rural loads consisting mainly of agricultural feeders are critical to maintain with reliability and stability due to abortive infrastructure and inefficient pumping system, which leads to heavy distribution & transmission losses. In addition, the central and state governments allocate billions of funds to subsidize power and reduction of tariff on agriculture feeder put further burden to state utilities in terms of financial challenges and recovery. To gear up challenges in eminent manner various benefits to state utilities from local smart grid solution to be provided such as energy management with arbitrage, real time analysis of data, user interface for monitoring and control, etc., in existing agriculture feeder which can bring down the financial implication and improve the state distribution companies’ redundancy.
The integration of clean energies such as solar and battery storage unit at distribution facilities is one of the important features in the smart grid. The Smart Distributed Energy Resources (SDER) that combine use of decentralized solar & energy storage systems form a “Local Smart Grid” at distribution end. It stimulates the demand response with use of forecasting, data analytics and two-way communication to arbitrage the energy with real time monitoring & smart control at distribution level of 11kV of agriculture feeder substation. This unique and smart system is designed and to be developed with application such as Virtual Irradiance Sensors (VIS), Artificial Intelligence (AI), Graphical User Interface (GUI), Energy Management System (EMS), Sensor Networking etc. The foremost energy utilization from Smart Distributed Energy Resources (SDER) providing 24×7 uninterrupted reliable power supply to the 11kV feeder substation, is one of the most challenging tasks to overcome with the implementation of smart and intelligent systems which will act as local smart grid at distribution point.
The local smart grid provides many benefits, such as Peak load shaving, Real time User Interface, Data Analytics, Stability, Load Profile Management and Controlled Power Infrastructure. The Fig.1 Architecture representation shows, the local smart grid implementation minimizes use of import power from grid and use the decentralized clean power in daytime dedicated to agriculture feeder efficiently improves the infrastructure requirement and minimize the distribution losses at substation end. Local smart grid allows to energies feeder in peak time to export to other available feeder or nearby urban load center to overcome peak shaving and reduce the tariff burden on power available for common man. The single model delivers power from Smart Distributed Energy Resources (SDER) at agriculture feeder for reliability and performance improvement leads to increase the productivity of the agriculture sector.
Energy Management System (EMS)
- The EMS is the primary controller which coordinates and controls all control action in the system. The Decentralized solar energy systems and battery storage system have been developed along with power electronic converters, control algorithms and controllers to operate the System.
- IED/RTU used for the communication and control algorithm to be defined for scheduling and power flow from distributed system.
- IOT/AI based integration can provide real time analytics of the Distribution & Transmission line to communicate for forecasting and scheduling of power flow.
- A two-way communications infrastructure that can network one or more parts of the smart grid via secure, high speed, high bandwidth connections.
It is simply purchasing more electricity during Off-peak periods, storing that electricity and discharging it during Peak periods. In Fig.2. shown, with the help of battery management system, storage units charge at day time with clean power and relase as required by the system operator or State utitltiy peak period to meet the demand of the feeder.
Energy arbitrage with battery units (Compact storage chambers) are highly efficient and require less space compared to other DERs.
Sensor or Wide Area Networks
- The Wide Area Networks (WANs) provide communication links between the NANs and the utility systems to transfer information. As one of the core technologies, an efficient, reliable, and secure communication network plays an important role in realization of all the goals of smart grid NANs.
- Cloud based data storage and GUI to be developed for the integration and real time monitoring of the SDER.
Technical Challenges & Mitigation
Central and state utilities have formed reforms for the improved infrastructure and efficient equipment deployment at substations. Specific technical challenges associated with smart grid tool development to understand all the parameters such as stakeholders, demand profiles and seasonal changes, market features and potential other unforeseen issues that will arise because of unfamiliarity with the local conditions.
Challenges in terms of substation upgradation, advanced metering and reading, efficient troubleshooting and equipment replacement can be overcome with Smart Local Grid.
The State utilities, which suffer from heavy revenue crises due to inefficient network capability and non-reliable quality output at agriculture feeder substation, are tangled and tough to maintain it. With a mitigation plan for the improvisation of each component in the system and approach with integrating smart devices into it, the subject of reliability and quality can be resolved to a much better extent. It can reduce the distribution losses by 5-6% with SDER Mitigation plan applicable to any of the existing distributed systems as below:
- Retrofitting existing solar plants with storage
- Substation line optimization
- Real time monitoring
- Systematic & conditional maintenance
- Immediate troubleshooting
Conclusive Case Study and Business Model
Mukyamantri Saur Krishi Vahini Yojana (MSKVY) Scheme for State of Maharashtra
In MSKVY scheme existing projects developed for the Maharashtra state utility with decentralized solar are retrofitting with battery units together communicating with SLDC for load profile management in the substation area with help of AL/IOT. In the Fig. 3, excess solar energy is stored in batteries during off peak hours and the same is discharged during peak hours when the tariff is high. Thus, Energy Management with arbitrage can offer huge savings to large consumers.
This scheme has undertaken plants from the range of 0.2- 10MW at 11kV agriculture feeder that can provide daytime power to agriculture loads only. It has been introduced to use unutilized power for storage charging in off peak period and sell to other loads via state utility in peak time to improve load profile on the substation.
An adequate battery arbitrage algorithm model used under MSKVY project, based on an upper linear approximation, is included in the arbitrage strategies to improve the robustness of the results. A comparison of arbitrage strategies for the Indian electricity market to determine which is the most suitable. An economic evaluation to determine the viability of installing BESS to perform energy arbitrage in the Indian electricity market. Detailed flowchart of algorithm provided in Fig. 4.
Business Model with SDER
- In Maharashtra state, up to 1,000 MW decentralized solar projected with SDER in initial phase towards benefits in levelized tariff and smart solutions.
- Govt. of Maharashtra provides Agriculture subsidy to utilities which in turn passes subsidy to Agriculture consumers for more productivity.
- Distribution solar with SDER will supply agriculture feeder and inject power in urban feeder during peak time.
- With reduced use of grid electricity, there will be large savings to distribution utilities (INR 18,000 to INR 22,000 Crore in 25 years from 1,000 MW projects).
- The reduced subsidy can be returned to Govt. of Maharashtra and utilized for repayment to distributed solar projects in the state.
- Major stakeholders in this project will be – Government of Maharashtra, Distribution utilities, Farmers, State Nodal Agency and Owner as developer.
Expected Commercialization Plan
- Currently, the government of Maharashtra spends INR 12,000 crores annually as a subsidy to farmers.
- Each MW of project results into INR 6-7 Mn/MW savings in first year. The savings will increase in future as per the next graph due to expected increase in ACOS.
- Total benefit in 25 years from 1,000 MW project – INR 18,000 Crore (Without tracker), INR 22,000 crore (With tracker) shown in Fig.6.
- This subsidy is expected to continue unless steps are taken to reduce cost of supply at LT feeder.
- Due to savings in CO2, carbon trading market can also be explored in future which will also
provide monetary benefit and improve project commercials.
- After success of Local Smart-Grid pilot at distribution feeder, it can be scaled to other agriculture feeders on which CESL is implementing solar project. Local smart grid will facilitate distribution solar to reduce state subsidies yearly, improve losses at distribution network.
- Currently, Maharashtra state is heavily dependent upon thermal power to meet high electricity demand. Coal power plants contribute to 60% of overall energy mix in the state.
- With solar projects, facilitated by smart-grid implementation, there will be reduction in CO2, as illustrated below:
- The social cost is associated with factors such as damage to human health, damages to property, adverse impact in the climate and the eco system.
- Social cost of carbon in India is close to USD 10.4 per ton CO2 emission.
- Total avoided social cost of carbon from 1 MW solar project is ~ INR 25 million (Without tracker) and ~ INR 31 million (With tracker).
Eshwar Pisalkar is a Team Lead at Reliance BP mobility Limited for EV/BSS infrastructure development in India. He has 10+ years of industrial and research experience in the field of renewable energy solar, EV, BSS and Energy efficiency. He has a Master’s degree in Power Distribution with Smart Grids and Bachelor’s in Electrical Engineering. He is a certified Energy Manager and Solar Engineer in India.
Dipak Kokate is a BE Electrical and MTech in Power System with MBA in Power Management. He is having 20 years of Energy sector experience working in central and state governing bodies. He’s also a certified Energy Auditor and standing committee member for many renowned forums.