Just five years after the contracts were signed, the Shisanling pumped storage plant went into operation, relieving pressure on the Beijing grid. Suzanne Moxon reports.
Until recently China’s pumped storage industry was described as being in its infancy but, after commissioning of the Shisanling pumped storage plant, this sector of Chinese hydro power is demonstrating a new-found maturity.
The area around Beijing, 40km from Shisanling, has been experiencing consistent economic growth. Living standards are rising and so is the demand for power. As the difference between peak and base load grew, citizens experienced more frequent blackouts due to a lack of peaking capacity in the local grid. It became quite clear that existing capacity in Beijing could not meet demand.
Hydroelectric power was seen as the most effective solution to Beijing’s power shortages — it is pollution-free, renewable and can be utilised within several minutes. The dry climate of northern China is not conducive to large conventional hydro plants, so proposals for a pumped storage facility won the day.
The country already has experience of pumped storage facilities through existing plants. China’s oldest station is Gangnan (built in 1968), while 2000MW Guangzhou (completed in 1996) is one of the world’s largest pumped storage plants.
With many factors in its favour, such as its proximity to the load centre, a minimal impact on the environment (through an absence of waste products) and its reliability, the idea behind Shisanling pumped storage plant began to materialise. Furthermore, foundations for the project were already in existence. Under the initiative of the late Premier Zhou Enlai, the Shisanling reservoir was completed in 1958; this would now be utilised as the lower reservoir for the pumped storage plant. The upper reservoir was built on the Shangslgou gully behind Mang Mountain, while the waterway system and powerhouse, accommodating four 200MW Francis reversible pump/turbine units, were placed 200m underground in the rocky terrain behind the mountain.
The difference in altitude between the two reservoirs is approximately 500m. The upper reservoir is connected to the powerhouse through two intake tunnels and two penstocks, while a pair of tailrace tunnels connect the four pump/turbine units to the lower reservoir. In this design, if maintenance is being carried out on one intake, surge tank or tailrace, the pair of units served by the other penstock will still be operational.
Designed by the Beijing Hydroelectric Investigation and Design Institute, Shisanling station was built by the Beijing government and the State Energy Investment Corporation (SEIC). Financing for the project was secured by the government and SEIC, with a loan of US$750M from Japan’s OECF. Ownership is in the hands of the North China Electric Power Group, whose subsidiary, Beijing Hydroelectric Development Corporation oversees the development, construction and operation of hydro power in the Beijing area.
In July 1992, within the grand environment of Beijing’s Great Hall of the People, a consortium of Voith Hydro and Elin Energieversorgung signed contracts for the project’s pump/turbine and generator/motor. Voith Hydro (the consortium leader) supplied turbines; Voith Heidenheim the turbine-governors; while Elin supplied the generators, excitation and protection systems, generator bus ducts, switchgear, start-up frequency converters and control systems.
Voith and Elin stress that the project uses state-of-the-art technology. Voith had to carefully analyse stress levels, deflections and fatigue when designing the turbine/pumps. The design of the Shisanling units was optimised mechanically and hydraulically to achieve maximum performance and was accomplished through tight running clearances (in relation to the runner wearing ring and wicket gate end clearance).
The first turbine-generator was brought on line in 1995 and the remaining units were commissioned at five-month intervals. Just over five years after contracts were signed, final commissioning was in November 1997.
After Shisanling’s first four months of operation, the North China Power Group (NCPG) is well satisfied with its progress. The plant’s ability to provide peaking capacity on a daily basis, as well as the availability of 800MW of emergency power which can be on-line within 150 seconds, has found NCPG’s favour.
‘Since the first unit was put into operation, Shisanling has played a very important role in the north China power grid,’ Liu Xuezhong, vice president of NCPG, says. ‘The high level of successful starting-up and the unit availability index have given us a good reputation, as well as considerable profit for our power plant.’ With the success of Shisanling under its belt, the future bodes well for China’s pumped storage sector. The Beijing Hydroelectric Development Corporation says it has acquired considerable knowledge during construction of this plant, and it now boasts of a number of skilled and experienced employees familiar with large capacity pumped storage. Furthermore, the corporation has committed itself to the development of China’s hydro power industry.