@misc{SchifferKrishnaRaisch, author = {Schiffer, Johannes and Krishna, Ajay and Raisch, J{\"o}rg}, title = {A Consensus-Based Control Law for Accurate Frequency Restoration and Power Sharing in Microgrids in the Presence of Clock Drifts}, series = {2018 European Control Conference, (EEC) 12-15 Jun 2018, Limassol, Cyprus}, journal = {2018 European Control Conference, (EEC) 12-15 Jun 2018, Limassol, Cyprus}, publisher = {IEEE}, address = {Piscataway, NJ}, isbn = {978-3-9524-2698-2}, doi = {10.23919/ECC.2018.8550191}, language = {en} } @misc{SchifferKrishnaHansetal., author = {Schiffer, Johannes and Krishna, Ajay and Hans, Christian A. and Raisch, J{\"o}rg and Kral, Thomas}, title = {Steady State Evaluation of Distributed Secondary Frequency Control Strategies for Microgrids in the Presence of Clock Drifts}, series = {25th Mediterranean Conference on Control and Automation}, journal = {25th Mediterranean Conference on Control and Automation}, issn = {2473-3504}, doi = {10.1109/MED.2017.7984168}, pages = {508 -- 515}, abstract = {Secondary frequency control, i.e., the task of restoring the network frequency to its nominal value following a disturbance, is an important control objective in microgrids. In the present paper, we compare distributed secondary control strategies with regard to their behaviour under the explicit consideration of clock drifts. In particular we show that, if not considered in the tuning procedure, the presence of clock drifts may impair an accurate frequency restoration and power sharing. As a consequence, we derive tuning criteria such that zero steady state frequency deviation and power sharing is achieved even in the presence of clock drifts. Furthermore, the effects of clock drifts of the individual inverters on the different control strategies are discussed analytically and in a numerical case study.}, language = {en} } @misc{KrishnaSchifferMonshizadehetal., author = {Krishna, Ajay and Schiffer, Johannes and Monshizadeh, Nima and Raisch, J{\"o}rg}, title = {A consensus-based voltage control for reactive power sharing and PCC voltage regulation in microgrids with parallel-connected inverters}, series = {European Control Conference 2019, Naples, Italy}, journal = {European Control Conference 2019, Naples, Italy}, address = {Neapel}, isbn = {978-3-907144-00-8}, doi = {10.23919/ECC.2019.8795924}, pages = {6}, abstract = {We consider small-scale power systems consisting of several inverter-interfaced units connected in parallel to a common bus, the point of common coupling (PCC), and sharing a joint load. This is a frequently encountered configuration in microgrid applications. In such a setting, two important control objectives are reactive power sharing and voltage regulation at the PCC. In this paper, we first show that the nonlinear equilibrium equations corresponding to the aforementioned objectives admit a unique positive solution. Then, we propose a consensus-based distributed voltage controller which renders this desired unique solution locally asymptotically stable. Finally, control performance is illustrated via a simulation example.}, language = {en} }