Integrating Wind Power: A Potential Role for Controllable Demand

With high penetrations of wind generation, it is likely that some potential power production from this source will be spilled unless the inherent variability of this source is mitigated in some way. Installing dedicated on-site storage or backup generators, for example, is one effective but expensive way to do this. Without some form of mitigation, some wind generation will be spilled even if its operating cost (i.e. the offer into the wholesale market) is zero. The two main reasons are 1) transmission congestion when demand is high limits the ability of the network to transfer available wind power to customers, and 2) limiting the size of wind contingencies (i.e. cutouts to protect turbines from damage at high wind speeds). Under these conditions, another way to reduce the amount of wind spilled is to use controllable demand to shift demand from peak to off-peak periods using thermal storage and electric vehicles, for example. Controllable demand can also be used to provide other ancillary services, like ramping services to offset fluctuations in wind generation. These demand technologies are likely to be more cost effective than dedicated equipment because a large part of their capital cost is already covered by their primary uses for space conditioning and transportation. Using the Cornell SuperOPF, operations on a test network are simulated for a typical day to compare the effects of 1) controllable load, 2) on-site storage, and 3) upgrading transmission capacity. The different scenarios are evaluated in terms of 1) the percentage of potential wind generation spilled, 2) the total operating cost of production, and 3) the amount of installed capacity needed to maintain operating reliability. The results show that controllable load improves (reduces) all three criteria by alleviating congestion and mitigating wind variability. In contrast, the beneficial effects are smaller for both on-site storage, because it does not shift load to off-peak periods, and for upgrading transmission, because it does not mitigate wind variability.