Forum China’s Booming Hydropower: Systems Modeling Challenges and Opportunities Chuntian Cheng Professor, Institute of Hydropower and Hydroinformatics, Dalian Univ. of Technology, Dalian 116024, China (corresponding author). E-mail: ctcheng@dlut.edu.cn Lingzhi Yan M.S. Student, Institute of Hydropower and Hydroinformatics, Dalian Univ. of Technology, Dalian 116024, China. E-mail: yanlz@mail.dlut.edu.cn Ali Mirchi, A.M.ASCE Dept. of Civil Engineering and Center for Environmental Resource Man- agement, Univ. of Texas at El Paso, EL Paso, TX 79968. E-mail: amirchi@ utep.edu Kaveh Madani, A.M.ASCE Centre for Environmental Policy, Imperial College London, London SW7 2AZ, U.K. E-mail: k.madani@imperial.ac.uk Forum papers are thought-provoking opinion pieces or essays founded in fact, sometimes containing speculation, on a civil en- gineering topic of general interest and relevance to the readership of the journal. The views expressed in this Forum article do not necessarily reflect the views of ASCE or the Editorial Board of the journal. DOI: 10.1061/(ASCE)WR.1943-5452.0000723 China has been experiencing an unprecedented hydropower boom since 2000. By the end of 2015, the nation’ s cumulative installed hydropower capacity was four times larger than that of the United States (Uria-Martinez et al. 2015), reaching 320 gigawatts (GW), accounting for 26% of the global hydropower capacity (IHA 2016). As a pace-setter for producing electricity from renewable energies (Observ’ER 2013), China has entered a new era of hydropower generation made possible by a series of massive projects with unique features, including the world’ s largest hydropower station (Three Gorges, 22.5 GW), the largest hydro-turbine unit (800 MW), and the largest number of giant cas- caded hydropower systems (10 basins having cascaded systems with capacities more than 10 GW, the largest one holding 32 GW in 2015). To add to this list, the country boasts the largest hydropower aggregation in one regional power grid (China Southern Power Grid, 100 GW in 2015), as well as the largest interprovincial hydropower transmission capacity (73.8 GW in 2015, 100 GW by 2020). Managing such a complex hydropower network is a mam- moth task on the edge of engineering and sciences. This paper outlines the challenges associated with China’s large-scale hydropower system development, providing critical insights in three topical areas of hydrypower generation, transmission, and absorption. The paper also highlights areas where the long and rich history of water resources systems research and state-of-the-art modeling approaches can help address these challenges. Hydropower Generation China’ s geographically disconnected hydropower systems distrib- uted on different rivers are connected through system-wide energy demands and various operational constraints. China’ s operational hydropower challenges can be divided into three main categories: (1) operation of cascaded hydropower system on the supply side of power generation network; (2) operation of multiple cascaded hy- dropower reservoir systems that cross provincial and river basin boundaries; and (3) cooperative operation of transmitted hydro- power and other types of energy at the recipient side of the network for reliable and economically efficient absorption of the delivered hydroelectricity. The first category is a classical, well-known problem while the real challenges that currently hinder China’ s hy- dropower development arise from the latter two categories. Operational Complexity China’ s installed hydropower capacity is growing rapidly, with numerous plants connected to the hydropower network, and many more in the planning phase or under construction. As of 2016, Yunnan Province alone has 190 hydroelectric plants (521 units), with plans to increase the plants to more than 200 before 2020. Significant complexity arises due to the fact that large-scale hydro- power systems within this enormous network need to utilize the various reservoirs’ storage capacities and asynchronous precipita- tion to reduce spillage. The operations need to comply with detailed, stringent regulations such as power reduction depth (reservoir-specific range of unit output adjustment to flatten the net load curve) for peak load shifting, and to balance a multitude of stakeholder objectives (e.g., electricity generation, flood control, urban water delivery, irrigation, navigation, environmental protec- tion, and socioeconomic resilience) that create upstream- downstream conflicts. Furthermore, delivering hydroelectricity to eastern provinces introduces transmission constraints. Engineering expertise, experience, and thorough understanding of operation procedures, security standards, regulations, past system behavior (i.e., historical data), and specifications of hydropower plants can help reduce dimensions of the constraints and decision variables for optimal management of large-scale hydropower systems. Configurational Complexity The Chinese hydroelectricity generation network is characterized by cascaded reservoirs with large units (e.g., 300, 400, or 500 MW). Giant units with a capacity of 700 MW or more are being used extensively in the southwestern hydropower projects. Distinct features of the cascaded reservoirs, besides size of unit capacity, include high head and multiple irregular-shaped vibration zones that are particularly sensitive to head (Cheng et al. 2012). Head- sensitive hydropower plants are typically used as peaking resources to meet high-frequency demands for flattening the net load curve in multiple power grids. However, repeated running through vibration zones can cause severe abrasion and fatigue, or even explosion of turbines. Hydraulic connection and electrical limitations exacerbate these issues in cascaded systems. Therefore, uninterrupted func- tionality of units in the cascaded head-sensitive plants is a stubborn © ASCE 02516002-1 J. Water Resour. Plann. Manage. J. Water Resour. Plann. Manage., 02516002 Downloaded from ascelibrary.org by Imperial College London on 09/25/16. Copyright ASCE. For personal use only; all rights reserved.