Optimal sizing and control of balancing power in the future European system considering transmission system constraints

1 PROBLEM DESCRIPTION

It is a well -established fact that the futu re European power system will require an increasing amount of balancing power capability, in form of what today is called secondary and tertiary control reserves, in order to accommodate the increasing amount of fluctuating power producers, i.e. primarily wind power and photo-voltaic. In a sustainable scenario this balancing power must be provided by renewable power sources in order to fulfi ll the energy policies of EU and other European countri es, e.g. Norway and Switzerland . There are in principle five possible means to reduce the need for balancing power or to provide the needed balancing power in a sustainable way :

1. Improved forecasts of power production from fluctuating power sources.

2. Increased controllability of the fluctuating power sources

3 . Designated storage devices close to the fl uctu ating power producers, e.g. Battery Energy Storage Systems (BESS)

4 . Hydro power from a storage reservoir, possibly pumped storage

5. Demand Side Participation (DSP), i.e. load management

The first action is obvious and would lead to that the accuracy in the power production forecasts are improved, which will reduce the need for balancing power. The second one of these means would imply that the power plants are not operating at optimal efficiency and would consequently lead to energy losses of these power plants, which cou ld be substantial. Local energy storage would lead to a higher energy output from the power plants but requires an additional investment. The advantage of items two and th ree above is that the balancing power is provided locally and the transmission system is not utilized to supply the needed balancing power. For the first three means above one does not provide more balancing power but rather decreases the need for additional balancing

power and storage.



2 PROJECT OBJECTIVES

Hydro power, possibly with pumping capabilities, is a well proven effective source of sustainable balancing power. In Europe hydro power is of limited capacity and is located in a few geographical areas, i.e. basically in Scandinavia and in the Alps, implying that a certa in power transmission capacity be required. This is particularly obvious for the Scandinavian hydro power, which requires HVDC cables in order to be integrated in the balancing power scheme of the continental system, but this is also the case for the hydro power in the Alps. Demand Side Participation (DSP) is an instrument that hitherto has not been utilized as balancing power to any larger extent. The potential available is deemed to be significant and various concepts how it should be implemented have been proposed . Also for DSP power transmission capacity is needed for its utilization.

It is thus clear that the need for more balancing power will also introduce additional requirements on the transmission system. These requirements are concerning demands on transmission capabilities but also concerning the management and control of the transmission grid. Both these aspects must be addressed in order to obtain a viable and effective solution for handling balancing

power in the European system. The overall objectives are to address the problems related to balancing power in a future European system with a substantial part of the power generation in form of fluctuating renewable power sources. More specifically the following aspects will be addressed:

l.Estimation of the need of balancing power in different scenarios

2.Assessment of the different methods listed above to provide balancing power including the limitations imposed by the transmission system with regard to technical and economic criteria. Environmental issues will also be considered.

3.Development of planning methods and operational strategies for the future European system incorporating the needs of balancing power.