Nonlinear Sliding Mode and Distributed Control of Battery Energy Storage and Photovoltaic Systems in AC Microgrids With Communication Delays

• Published in: IEEE transactions on industrial informatics Vol. 15; no. 9; pp. 5149 - 5160
• Main Authors: Zhang, Runfan, Hredzak, Branislav
• Format: Journal Article
• Language: English
• Published: Piscataway IEEE 01.09.2019; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Balancing; Batteries; Battery energy storage system (BESS); Communication; Computer simulation; Converters; Cooperative control; Delay effects; Delays; Distributed generation; distributed multiagent control; Dynamic stability; Electric potential; Electric power grids; Energy storage; Feedback linearization; fixed-time control; Frequency control; Lead acid batteries; Microgrids; Multiagent systems; Observers; photovoltaic (PV) system; Product design; Reactive power; Restoration; Robust control; Sliding mode control; State of charge; state of charge (SoC) balancing; time delay; Time delay systems; Voltage; Voltage control
• ISSN: 1551-3203; 1941-0050
• DOI: 10.1109/TII.2019.2896032

This paper proposes a distributed fixed-time multiagent control strategy for the frequency restoration, voltage regulation, state of charge balancing, and proportional reactive power sharing between photovoltaic battery systems distributed in a microgrid with communication time delays. First, the feedback linearization method is applied to find the direct relationships between explicit states and control inputs. Then, based on the model, the distributed fixed-time cooperative control system restores the frequency, regulates the average voltage to the nominal value, and achieves accurate power sharing. For the state of charge balancing, a fixed-time observer is proposed to estimate the average state of charge of a battery using only information from neighbors. Based on the estimated value, a local fixed-time sliding mode control is applied to achieve the balanced state of charge. Due to robustness of the fixed-time control strategy, the balanced state of charge can be maintained despite intermittent photovoltaic generation and variable loads. The Artstein's transformation is applied to ensure the stability of the time delayed system. The dynamic performance is verified with an RTDS Technologies real-time digital simulator, using switching converter models, nonlinear lead-acid battery models, photovoltaic generation, and communication delays in a European benchmark microgrid.