Impact assessment of increasing unpredictability in gas balancing caused by massive wind power integration

Abstract

Gas fired power plants make up the main back-up technology to deal with intermittency induced by massive wind power integration. Therefore, the flexibility needs with respect to unpredictable power generation are actually transferred to the gas market. Applying the well known electric power generation concepts of ‘unit commitment’ and ‘dispatching’ to the gas market, hypothetical electricity generation and gas transmission systems have been modeled to verify, first, the physical impact of wind power forecasting errors on the gas system, and, second, its effect on gas imbalance settlement. We find that increasing unpredictability leads to more expensive physical balancing of the gas system. Cost recovery by means of non-market based settlement faces the problem of defining an appropriate unique penalty that covers the balancing costs and incentivizes shippers. Market based settlement relates the variable imbalance tariffs to the actual system imbalance and thus any factor that strongly impacts on the system state like unpredictability. However, this mechanism raises imbalance settlement tariffs for all unbalanced gas network users, even if the major source of unpredictability is the shipper with the wind power related gas demand; whereas these costs should be borne as much as possible by those effectively causing them.