Using storage devices for compensating uncertainties caused by non-dispatchable generators

This paper presents a study on combining a grid-connected stochastic generator with an energy storage device. The storage device is used to balance the power fluctuations of the non-dispatchable generator in order to feed power into the network according to an hourly pre-determined constant profile. The negative effects of inaccurate forecasts are thus reduced by turning the stochastic generation into a deterministic network infeed. Important parameters for achieving this goal are the energy capacity of the energy storage and the error magnitude of the forecast used to define the infeed profile. A general method for simulations based on a measurement series is presented, together with a method for the simulation of forecasts with different forecast errors. The methodology is then applied in a case study to investigate the feasibility of using an storage device for hourly balancing. The emphasis is on the relation between infeed accuracy, forecast error and energy capacity of the storage