This study proposes a hierarchical control structure for a smooth transition of multi-bus microgrids from islanded mode to grid-connected mode. The proposed control structure uses an average consensus protocol for the secondary control layer and Andronov-Hopf virtual oscillator control as a primary controller. The proposed method enhances the power-sharing accuracy among DGs in normal operation. A synchronization strategy is embedded into the secondary control layer in synchronization mode to force the MG-side voltage at the connection point to synchronize with the grid-side voltage. The influence of the secondary controller and communication time-delay on system stability and performance is analyzed with small-signal analysis. The proposed method is validated via control-hardware-in-the-loop (CHiL) using a real-time Opal-RT platform.

This paper introduces a consensus-based distributed control strategy for islanded microgrids, which employs grid-forming and grid-feeding inverters for power sharing and voltage regulation and involves measurements from high-reporting-rate phasor measurement units. The performance of the proposed control scheme is analyzed through a cyber-physical (CP) model and by laboratory implementation. The CP model emphasizes the flexible design of the communication (cyber layer) and the interaction between the cyber and physical layers. The laboratory experiment affirms the functionality of the control scheme and the accuracy of the CP model. The results demonstrate that the proposed control scheme can successfully manage islanded microgrids. The high-reporting-rate meters enhance the control during transient operations following major disturbances, and the CP model accurately depicts the dynamics of the cyber-physical system

This paper presents formulation and analysis of a distributed consensus-based controller for power electronics based microgrids (MG) with grid forming (GFM) and grid feeding (GFD) inverters. The control is supported by measurements from high reporting rate meters that improve the dynamics of consensus control and enables participation of buses with no dispatchable units. The study is performed on a developed cyber-physical (CP) model in DQ domain that allows for the analysis of arbitrary MGs. The control is established on fundamental principles of consensus and provides power sharing and voltage regulation, maintains power reserve in MG, and assumes distinct roles for different types of inverters. The analysis of the control scheme includes aspects of coupling between cyber and physical layers and stability under multi-layer communication structure. The study addresses disadvantages of classical hierarchical control and enhances analysis of distributed controllers through the proposed CP model.

Grid-connected photovoltaic (PV) systems are commonly designed for maximum energy production. However, as their presence grows, revised grid regulations increasingly require these systems to partially adhere to the primary frequency regulation (PFR) by reducing their power production when the grid frequency exceeds the nominal value. Nevertheless, full participation in PFR of PV systems, without battery storage, would require operating with a dedicated active power reserve to be utilized in the event of underfrequency conditions. This paper presents a model-based (MB) flexible power point tracking (FPPT) algorithm for PV systems. Results of a microgrid simulation show that the proposed algorithm enables a PV system with a nominal power of 100 kW to maintain a 20 kW active power reserve under various irradiation and temperature conditions, with a relative error lower than 3%. Furthermore, a simulation of the PV system assisting in primary frequency regulation is presented. Thanks to the proposed strategy, when employing the algorithm, the frequency deviation is reduced both in the event of underfrequency and overfrequency conditions. By enabling operation with a constant active power reserve, as well as a quick adjustment of the produced active power, in the event of frequency imbalance, the proposed MB algorithm is an interesting candidate for achieving complete PFR capabilities of PV systems.

On-line sharing of cyber-security information is necessary to effectively counter cyber-attacks. An online cyber-security analytics system for detecting and mitigating cyber-attacks and sharing information between Critical Infrastructure operators and regional and national authorities and also internationally is presented. The system contains one part which acts as a Security Operations Centre at Critical Infrastructure-level, with the capability to automatically mitigate attacks, and a part on meta- Critical Infrastructure level which, on a pan-European scale, gathers and analyses cyber-security information provided by the Critical Infrastructure operators and provides the results of the wide-area cyber-security analytics to authorities and back to the Critical Infrastructure operators. A use case of the system detecting and mitigating an attack is presented.