Value of stochastic reserve policies in low-carbon power systems

The intermittent nature of wind power and the high ratings of next-generation nuclear units mean that low-carbon power systems will have high short-term reserve requirements, if these requirements are determined using current methods. Meanwhile, the flexible fossil-fuel generators, which have been the traditional providers of reserve services, will run much less frequently. A fundamental review of the reserve requirement is therefore needed if power systems are to absorb high wind penetrations in an efficient manner. A fast Stochastic Unit Commitment algorithm is presented, which accounts for the uncertainties in demand, wind power and thermal generator outages, and schedules both frequency response (primary reserve) and longer-term reserves considering the costs and benefits of their provision. It is shown through multi-year simulations that stochastic scheduling can have substantial benefits at high wind penetrations, in terms of wind curtailment and efficient running of the flexible generators. Under the assumptions made, the cost reduction, compared with system operation under current reserve requirements, is about 4 per cent at a 50 per cent penetration.