Browsing by Author "Tzovaras, Dimitrios"

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Cloud Induced PV Impact on Voltage Profiles for Real Microgrids
(IEEE, 345 E 47TH ST, NEW YORK, NY 10017 USA, 2018) Kocer, Mustafa Catagatay; Yoldas, Yeliz; Goren, Selcuk; Onen, Ahmet; Alan, Irfan; Al-Agtash, Salem; Azzopardi, Brain; Martensen, Nis; Martinez-Ramos, Jose L.; Tzovaras, Dimitrios; Hadjidemetriou, Lenos; Khiat, Mounir; Camilleri, Tim; Borg, Nicholas; 0000-0002-5320-4213; AGÜ, Mühendislik Fakültesi, Elektrik - Elektronik Mühendisliği Bölümü
Integration of renewable energy sources (RESs) into power systems has been a popular topic for a long time. Due to government policies and incentives, it will be more popular in the future since it is a free and environment-friendly nature. Besides its advantages, photovoltaic (PV) generation causes some serious problems to the grid. Since PV generation directly depends on the solar irradiance, cloud movements can cause sudden changes on the output of PV power and this results in some power issues in the system such as voltage violations, reverse power flow, voltage fluctuations. These types of issues complicate to maintain voltage within compulsory levels at customer sides. Thus, cloud-induced transients in PV power are seen as a potential handicap for the future expansion of renewable energy resources. This study investigates effects of instantaneous changes in PV power on the customer side voltage levels. Daily PV power output and voltage profiles were simulated using a real-world microgrid design that will be implemented in the Malta College of Arts Science and Technology(MCAST) Campus.
A hybrid agent-based secondary control for microgrids with increased fault-tolerance needs
(Institution of Engineering and Technology, 2018) Bintoudi, Angelina D.; Zyglakis, Lampros; Apostolos C. Tsolakis; Ioannidis, Dimosthenis; Al-Agtash S.; Martinez-Ramos, Jose L.; Onen, Ahmet; Azzopardi, Brian; Hadjidemetriou, Lenos; Martensen, Nis; Mounir, Khiat; Borg, Nicholas; Fragale, Nunziatina; Demoulias, Charis; Tzovaras, Dimitrios; 0000-0001-7086-5112; AGÜ, Mühendislik Fakültesi, Elektrik - Elektronik Mühendisliği Bölümü; Onen, Ahmet
This paper proposes a hybrid secondary control architecture for microgrids with AC-coupled droop-controlled units, based on both centralised and distributed control principles. The proposed secondary control is based on a multi-agent system (MAS), complemented by a microgrid centralised controller (MGCC). The system is able to adjust the droop curves dynamically in order to achieve voltage/frequency restoration as well as active/reactive power optimal allocation, based on the actual status of the controllable units, in particular, the state-of-charge of batteries and maximum power point of photovoltaics. The distributed nature of the agents is also fully exploited because the proposed framework retains operability even under fault on secondary MGCC. To evaluate the proposed framework, a scenario-based performance analysis has been tested over a simulated AC islanded microgrid, where communication from the MGCC is suddenly interrupted and the MAS is required to reconfigure in order to maintain the same control objectives. MATLAB/Simulink simulations have been realised using detailed physical form models for a small-scale microgrid, while the implementation of the MGCC and MAS is accomplished through Java Agent Development (JADE) framework.
Novel Hybrid Design for Microgrid Control
(IEEE345 E 47TH ST, NEW YORK, NY 10017 USA, 2017) Bintoudi, Angelina D.; Zyglakis, Lampros; Apostolos, Tsolakis; Ioannidis, Dimosthenis; Al-Agtash, Salem; Martinez-Ramos, Jose L.; Onen, Ahmet; Azzopardi, Brian; Hadjidemetriou, Lenos; Martensen, Nis; Demoulias, Charis; Tzovaras, Dimitrios; AGÜ, Mühendislik Fakültesi, Elektrik - Elektronik Mühendisliği Bölümü; Onen, Ahmet
This paper proposes a new hybrid control system for an AC microgrid. The system uses both centralised and decentralised strategies to optimize the microgrid energy control while addressing the challenges introduced by current technologies and applied systems in real microgrid infrastructures. The well-known 3-level control (tertiary, secondary, primary) is employed with an enhanced hierarchical design using intelligent agent-based components in order to improve efficiency, diversity, modularity, and scalability. The main contribution of this paper is dual. During normal operation, the microgrid central controller (MGCC) is designed to undertake the management of the microgrid, while providing the local agents with the appropriate constraints for optimal power flow. During MGCC fault, a peer-to-peer communication is enabled between neighbouring agents in order to make their optimal decision locally. The initial design of the control structure and the detailed analysis of the different operating scenarios along with their requirements have shown the applicability of the new system in real microgrid environments.