A power limiting control strategy based on adaptive utility function for fast demand response of buildings in smart grids

Power imbalance in electrical grid operation has become a most critical issue that results in a series of problems to grids and end-users. The end-users at demand side can actually take full advantage of their power reduction potentials to alleviate the power imbalance of an electrical grid. Buildings, as the major energy end-users, could play an important role on power demand response in smart grids. This article presents a fast power demand limiting control strategy in response to the sudden pricing changes or urgent requests of grids within a very short time, i.e., minutes. The basic idea is to shut down some of active chillers during demand response events for immediate power demand reduction. The article focuses on the solutions to address the operation problems caused by the conventional control logics, particularly the disordered flow distribution in chilled water system. A water flow supervisor based on an adaptive utility function is developed for updating the chilled water flow set-point of every individual zone online. The objective is to maintain even indoor air temperature change among all zones during a demand response period. A case study is conducted in a simulation platform to test and validate the novel control strategy. Test results show that the proposed control strategy can achieve fast power reduction after receiving a demand response request. Simultaneously, the proposed control strategy can effectively solve the problem of disordered water distribution and achieve the similar changing profiles of the thermal comfort among different zones under the reduced cooling supply.