Flexible Medium Sized Pumped Storage Plants

摘要

The need for flexible storage solutions in the power grid has been becoming more and more important during the last years. The main reason is the penetration of in-feed from volatile energy sources, with wind energy and photo voltaic leading the way. For medium and large scale energy storage, pumped storage plants (PSP) are the most important component in the grid. The requirements for such plants have been changing during the years: The flexibility of plant operation has been arousing more and more interest, including a wide operation range, a fast transient behavior and the possibility to regulate pump input power. To fulfill these requirements, variable speed solutions utilizing converter technology are increasing their market share, since they offer the maximum flexibility. Such units have been successfully implemented in Europe and Japan, mostly in the power range of several hundreds of megawatts, using so called double fed motor-generators. But nowadays developing new sites for large pumped storage units has becoming very difficult, so smaller sites with often unfavorable hydraulic conditions are coming more and more into focus. One option for such sites is the utilization of full scale converters between motor-generator and step-up transformer. This solution has been becoming more economic within the last years because of falling prices for power electronics. It allows decoupling of hydraulic generation and grid connection within certain limits and so is superior to classical units in terms of dynamic response, fault behavior as well as operation range. This paper gives an introduction into this technology. Simulation results of unit behavior from hydraulic generation to the grid, thus a full “water-to-wire” system, are investigated.