China's Approach to the Smart Grid
- Written by Jinyu Wen and Haibo He
Connecting widely separated generation and loads by means of ultra-high-voltage transmission and adapting a relatively rigid generation structure to accommodate intermittent wind and solar necessarily take precedence in Chinese planning. But incorporation of digital communications into transmission also visualized under the rubric of what China is calling a "strong" smart grid.
Electricity planning in China is governed by two distinct characteristics of its power system, both connected with the dominance of coal. First, coal reserves are mainly in the Northwest region, while demand is concentrated in rapidly industrializing Eastern and Central China; compounding the problem is the fact that exploitable hydropower, the country's second most important source of electricity, is in the Southwest. Second, because active power regulation is relatively inflexible in coal-fired generation units, intermittent sources of power such as wind cannot easily be accommodated by means of frequency adjustment and peak shaving. Accordingly, it is hardly surprising that grid planning for the next five years emphasizes the exchange of bulk power across regions, with smart grid technologies—including integration of renewable energy—a distant second.
The 12th National Economic and Social Development Five-Year Planning Outline, officially promulgated on March 16th, 2011, states that "to meet the requirements for the bulk power transmission and the renewable power generation, it is of importance to accelerate the construction of a modern power system, enlarge further the power transmission scale from the west of China to the east of China, improve regional main grid structure and develop large-capacity, high-efficiency, long-distance power transmission technologies such as ultra-high-voltage power transmission; promote…smart grid development based on advanced technologies such as…information, control and energy storage; strengthen the construction and renovation of urban and rural power grids; and enhance the optimal allocation capacity of the grids as well as the reliability of power supply." All of these are the essential characteristics and key development blueprint for the national grid.
In the last decade, China's demand for electricity has been increasing at a rate of about 10 percent per year. Between 2004 and 2008, the national load doubled, adding an increment of power one-and-half times the size of Japan's. To connect that load with main power sources, regional grid systems have been connected by ultra-high-voltage (AC 1000 kV or DC ±800 kV) and extra-high-voltage transmission lines. HVDC corridors link the Central China and East China grids, the Northwest China and Central China grids, and the Central China and China Southern power grids. A 1000 kV AC line links the North China and Central China grids.
Implementation of ultra-high-voltage AC transmission is, by the way, not unique to China—Russia and Japan installed such lines first, and Brazil is considering the technology. But China has taken UHVAC to a new level, developing and building, for example, a new line of standard-setting step-up transformers.
The rapid growth of China's wind sector, which is now the largest of any nation's, has compounded the general problem of regionally separated generation and load—and, together with related problems, has helped bring smart grid thinking to the fore. China’s wind capacity already exceeds 41 GW and—with dependence on fossil fuels, air pollution and climate change in mind—the China National Energy Administration has proposed a target of 90 GW of wind power by 2015 and 150 GW by 2020. As with coal, however, wind resources are mainly concentrated in the Northwest and Inner Mongolia regions, where the power grid is relatively undeveloped and wind power can’t be readily absorbed locally because of limited demand. So, the bulk wind power also has to be transmitted to remote load centers by the transmission network at high voltage levels.
Although the smart grid, as such, would only come under discussion later, as early as 1999, the notion of a digital power system already was put forth in the context of a study on how to make the power system more robust and economically efficient. In October 2007, the State Grid Corporation of China (SGCC) officially launched an investigation into the feasibility of a self-healing smart grid. In May 2009, the SGCC proposed the concept of what it calls a Strong Smart Grid, officially launching the study and construction of the system, to be completed by 2020.
Despite the intensive discussions of the smart grid concept and wide-ranging research by enterprises, institutions and individual experts, actual reform and reconstruction of the power system depends primarily on the perspectives of the grid corporations. The China Southern Power Grid Corporation (CSG), for example, has proceeded more conservatively in the construction of the smart grid compared to the SGCC, but CSG has begun some pilot projects, such as an intelligent distribution network, distributed generation and microgrids, energy storage, electric vehicle charging stations in Guangzhou and Shenzhen, and so on. So far, however, it has not specified a development path or milestones. Accordingly, the SGCC's work represents China's most advanced progress in this field.
The process for constructing the strong grid is divided into three stages, with a total estimated investment of 4 trillion RMB (about US $620 billion at the official exchange rate). The planning stage and pilot work took place in 2009 and 2010. Also during that time, technical and management standards were devised and key technology research and equipment development undertaken. 2011 to 2015 mark the construction stage, when rollout of UHV links will be accelerated and urban and rural distribution networks built out. The period from 2016 to 2020 could be defined as the improvement and upgrade stage.
The comprehensive demonstration project for Shanghai World Expo, which was completed and opened to the public in April 2010, has been a representative pilot project. Another, in Zhangbei, Hebei Province, combines—on a large-scale—renewables, energy storage and transmission. Upon completion, it will house, among other things, the world’s largest single photovoltaic power plant.
In sum, the Strong Smart Grid will integrate the entire power sector—including generation, transmission, transformation, distribution, consumption and dispatch—at all voltage levels. It is a comprehensive concept. Strength—in terms of robustness, resilience and reliability—is its foundation, and smartness—that is to say intelligence, adaptiveness and optimization—is its key characteristic.