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The evolving nature of electricity production, transmission, and consumption necessitates an update to the IEEE's Reliability Test System (RTS), which was last modernized in 1996. The update presented here introduces a generation mix more representative of modern power systems, with the removal of several nuclear and oil-generating units and the addition of natural gas, wind, solar photovoltaics, concentrating solar power, and energy storage. The update includes assigning the test system a geographic location in the southwestern United States to enable the integration of spatio-temporally consistent wind, solar, and load data with forecasts. Additional updates include common RTS transmission modifications in published literature, definitions for reserve product requirements, and market simulation descriptions to enable benchmarking of multi-period power system scheduling problems. The final section presents example results from a production cost modeling simulation on the updated RTS system data.

Integration of large scale renewables into the electrical grid is currently one of the major challenges and priorities for many countries. The Government of India (GOI) has committed to install 175 GW renewable energy (RE) by 2022. Due to favorable policies, RE capacity in India recently exceeded 60 GW, overtaking hydropower as the second largest fleet. To assess the impact of large scale RE on the power system, three studies (one national and two regional) were undertaken jointly by the United States Agency for International Development (USAID) and the Ministry of Power (MOP), GOI. The studies used production cost models to simulate the Indian electricity system for each 15-minute time block of the year 2022 to understand potential future operational challenges and opportunities for more cost-effective integration. This paper is an abridged version of the national study titled, “Greening the Grid: Pathways to Integrate 175 Gigawatts of Renewable Energy into India’s Electric Grid, Vol. I — National Study” (June 2017). The study concluded that the integration of 175 GW of RE, equivalent to 370 TWh annual generation and 22% demand penetration, is achievable at 15-minute operational timescales with minimal RE curtailment. If the thermal fleet exploits their ramping capabilities and lower minimum generation levels, the Indian power system has sufficient flexibility to manage net load changes and RE forecast errors. Along with thermal fleet flexibility, the latent flexibility in hydroelectric generation is critical in maintaining system balance. The study analyzed integration strategies that may generate cost savings and lower RE curtailment. Coordinated scheduling across regional and national levels, which increases the size of the balancing areas, lowers RE curtailment and reduces annual production costs. Reducing the technical minimum of thermal plants has the biggest impact on reducing RE curtailment. The study’s implications to policy makers, planners, and regulators include coordinated transmission planning, better coordination among states for scheduling and dispatch, and incentives for system flexibility.

Author(s): Palchak, D; Cochran, J; Deshmukh, R; Ehlen, A; Soonee, S; Narasimhan, S; Joshi, M; McBennett, B; Milligan, M; Sreedharan, P; Chernyakhovskiy, I; Abhyankar, N | Abstract: The use of renewable energy (RE) sources, primarily wind and solar generation, is poised to grow significantly within the Indian power system. The Government of India has established an installed capacity target of 175 gigawatts (GW) RE by 2022 that includes 60 GW of wind and 100 GW of solar, up from current capacities of 29 GW wind and 9 GW solar. India’s contribution to global efforts on climate mitigation extends this ambition to 40% non-fossil-based generation capacity by 2030. Global experience demonstrates that power systems can integrate wind and solar at this scale; however, evidence-based planning is important to achieve wind and solar integration at least cost. The purpose of this analysis is to evaluate the operation of India’s power grid with 175 GW of RE in order to identify potential cost and operational concerns and actions needed to efficiently integrate this level of wind and solar generation.

Author(s): Palchak, D; Cochran, J; Deshmukh, R; Ehlen, A; Soonee, R; Narasimhan, S; Joshi, M; McBennett, B; Milligan, M; Sreedharan, P; Chernyakhovskiy, I; Abhyankar, N | Abstract: The use of renewable energy (RE) sources, primarily wind and solar generation, is poised to grow significantly within the Indian power system. The Government of India has established a target of 175 gigawatts (GW) of installed RE capacity by 2022, including 60 GW of wind and 100 GW of solar, up from 29 GW wind and 9 GW solar at the beginning of 2017. Using advanced weather and power system modeling made for this project, the study team is able to explore operational impacts of meeting India’s RE targets and identify actions that may be favorable for integration. Our primary tool is a detailed production cost model, which simulates optimal scheduling and dispatch of available generation in a future year (2022) by minimizing total production costs subject to physical, operational, and market constraints. Our team comprises a core group from the Power System Operation Corporation, Ltd. (POSOCO), which is the national grid operator (with representation from the National, Southern, and Western Regional Load Dispatch Centers) under Ministry of Power, National Renewable Energy Laboratory (NREL), and Lawrence Berkeley National Laboratory (Berkeley Lab), and a broader modeling team that includes Central Electricity Authority (CEA), POWERGRID (the central transmission utility, CTU), and State Load Dispatch Centers in Maharashtra, Gujarat, Tamil Nadu, Karnataka, Rajasthan, and Andhra Pradesh. Our model includes high-resolution wind and solar data (forecasts and actuals), unique properties for each generator, CEA/CTU’s anticipated buildout of the power system, and enforced state-to-state transmission flows. Assuming the fulfillment of current efforts to provide better access to the physical flexibility of the power system, we find that power system balancing with 100 GW of solar and 60 GW of wind is achievable at 15-minute operational timescales with minimal RE curtailment. This RE capacity meets 22% of total projected 2022 electricity consumption in India with annual RE curtailment of 1.4%, in line with experiences in other countries with significant RE penetrations (Bird et al. 2016). Changes to operational practice can further reduce the cost of operating the power system and reduce RE curtailment. Coordinating scheduling and dispatch over a broader area is the largest driver to reduce costs, saving INR 6300 crore (USD 980 million) annually when optimized regionally. Lowering minimum operating levels of coal plants (from 70% to 40%) is the biggest driver to reduce RE curtailment—from 3.5% down to 0.76%. In fact, this operating property is more influential than faster thermal generation ramp rates in lowering the projected levels of curtailment. While this study does not answer every question relevant to planning for India’s 2022 RE targets, it is an important step toward analyzing operational challenges and cost saving opportunities using state-of-the-art power system planning tools. Further analysis can build upon this basis to explore optimal renewable resource and intrastate transmission siting, system stability during contingencies, and the influence of total power system investment costs on customer tariffs.