New ways of providing ancillary services in a power system
Czech Technical University in Prague, Faculty of Electrical
Czech Technical University in Prague, Faculty of Electrical Engineering, Department of Economics, Management and Humanities
This paper focuses on new possibilities for balancing generation and load in an electrical power system.
The ever increasing proportion of intermittent power sources (wind and solar) in the power system changes the basic paradigm of power engineering economics whereby instead of adjusting generation output to the demand at the time, the focus is shifting towards adjusting consumption based on the output of intermittent generation. That is the goal of the so-called smart grids, where the consumer will be adapting to intermittent generation by responding to price signals.
In spite of or rather because of this, there will still be (at the moment, more and more) the need for power sources and appliances that will, at the dispatcher’s request, quickly increase or decrease generation or instead of generators become consumers, i.e. their technical parameters enable them to maintain balance between generation and consumption and network frequency within set limits.
On the generation side, these are primarily gas turbines and closed cycle gas turbines, storage hydro stations, heat plants with turbines equipped with heat accumulators or accumulating heat into a heat distribution network and networks of CHPs (combined heat and power) also with heat accumulators supplying heat into buildings in a wide area, but centrally controlled.
On the demand side, these are ripple control (HDO in the Czech Republic) which control appliances that convert electricity into useful heat, which is easier to accumulate for water heating purposes, electrical boilers connected into heat networks and in the future also P2G systems using cheap electricity to decompose water into oxygen and hydrogen. Being affiliated with current heat plants, they will utilise carbon from fossil or biofuel combustion for the methanization of hydrogen and its injection into the natural gas network for the purposes of seasonal energy accumulation.
Nonetheless, for accumulation of AC current over the course of a day to a week it is still the best to make use of the benefits of pumped storage hydro power stations which remain to be a proven form of electricity accumulation in the grid. The vast majority of them are designed and constructed in mountainous areas so that they can take advantage of the differences in elevation of the landscape. This appears to be at odds with nature protection interests. The paper concentrates on a location of an active lignite quarry in the northwest of the Czech Republic, where the interests of nature protection would not be affected.
From an economical perspective, in the case of a pumped storage hydro station, capital expenditure is key and therefore the paper also includes an assessment of the economic efficiency of the project, through the valuation of the effects resulting from the provision of ancillary services to the transmission system.