Simulation and modeling of blended constant-frequency and variable-frequency air-conditioner
The conventional constant frequency airconditioner (CFAC) and the inverter based variable-frequency air-conditioner (VFAC) are increasingly used now. The study of air-conditioner based load and its impact on power system is greatly demanded. In this paper, the characteristics of CFAC and VFAC are investigated, respectively. Then, a modeling method of blended air-conditioner (BAC) load is proposed, and parameters of CFAC and VFAC are studied in detail. Later, the proposed model is tested in real power system. It is found that the characteristics of blended air-conditioner model is strongly related to the composition proportion of CFAC and VFAC, and they apparently affect power grids especially on voltage/reactive power issues.
Efficient operation of IBM Vermont’s 200mm semiconductor wafer fabrication facility is essential to achieve the objective of transforming the site into a world class foundry manufacturer. To that end, we develop a fluctuation smoothing for the variation of cycle time (FSVCT) production control policy capable of allowing for a diversity of cycle time commitments. The policy directs which lot should next receive processing when a tool becomes available. In the absence of a validated cycle time model for the fabricator, we obtain estimates of achievable cycle time performance in the presence of business constraints on the cycle times of certain lots via a consequence of Little’s law. The mean and variation of cycle time implications for IBM Vermont’s facility are highlighted.