2020/02/16 by Andreas Kasis, Kasis, Andreas, Ioannis Lestas +1
Engineering · #Microgrid Control and Optimization #Smart Grid Energy Management #Frequency Control in Power Systems
paper · pdf · doi:10.48550/arxiv.2002.06649
Thermostatically controlled loads (TCLs) can provide ancillary services to\nthe power network by aiding existing frequency control mechanisms. TCLs are,\nhowever, characterized by an intrinsic limit cycle behavior which raises the\nrisk that these could synchronize when coupled with the frequency dynamics of\nthe power grid, i.e. simultaneously switch, inducing persistent and possibly\ncatastrophic power oscillations. To address this problem, schemes with a\nrandomized response time in their control policy have been proposed in the\nliterature. However, such schemes introduce delays in the response of TCLs to\nfrequency feedback that may limit their ability to provide fast support at\nurgencies. In this paper, we present a deterministic control mechanism for TCLs\nsuch that those switch when prescribed frequency thresholds are exceeded in\norder to provide ancillary services to the power network. For the considered\nscheme, we provide analytic conditions which ensure that synchronization is\navoided. In particular, we show that as the number of loads tends to infinity,\nthere exist arbitrarily long time intervals where the frequency deviations are\narbitrarily small. Our analytical results are verified with simulations on the\nNortheast Power Coordinating Council (NPCC) 140-bus system, which demonstrate\nthat the proposed scheme offers improved frequency response compared to\nconventional implementations.\n