Guidelines for transients are in need of revision

Although considerable knowledge has been built-up over the years, the design of various hydroelectric plants, particularly pumped-storage plants, has not always made full use of this knowledge. Mathematical instabilities, which could be resolved by experienced experts, and real physical unavoidable instabilities, make software application by experts not educated and experienced in subject extremely dangerous: bad things can happen if one can't distinguish inaccurate unrealistic results from reasonable good ones. Additionally, in a number of cases there is considerable evidence that already published guidelines, recommendations and standards have not be consistently applied. As a consequence, vital parameters relating to overall safety and sustainable operation which could have been based on the experience and knowledge of designers and equipment suppliers have been neglected. For instance, contrary to certain common working assumptions, the minimum pressure in a draft tube cannot be any constant pressure to fit the complex flow conditions at the exit of the runner. When such realities are combined with pump-turbine "S" instability there is a further increase in the risk of damages and accidents. Rather, a more realistic set of procedures must be applied. What makes such considerations particularly vital is that pumped-storage plants have such excellent potential for further exploitation as they represent a potentially significant environmentally clean load that may help compensate for power variations in the grid and the need to limit wind power output. Energy storage - if well designed and operated - has a great potential for making the overall system and market more efficient and reliable. It is not an exaggeration to say that pumped storage systems could substitute for up to 50% of nuclear and coal generating plants. They are easily manageable and impressively can be 75 - 85% efficient across the energy storage cycle. This work maintains that some crucial technical areas have lost the benefit of valuable experience and knowledge that has accrued in more than 100 years. The poorly coordinated transfer of practical and theoretical experience appears to be the root cause of this loss. The consequences are an unstable market and investment climate, and a greater frequency of accidents, higher inefficiency and the need for more common troubleshooting; yet many of the same problems which have appeared in recent years can be expected to continue to occur with