Nikolaos Lettas

Mr. Nikolaos Lettas


Research Focus & Metrics

Academic Career Length

4Years (2023-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

View All Publications
16 November 2023 in Energies
Verified
Journal Article
Open access
PDF file
EBEvangelos Boutsiadis
Evangelos Boutsiadis
NPNikolaos Pasialis
Nikolaos Pasialis
NLNikolaos Lettas
Nikolaos Lettas
DTDimitris Tsiamitros
Dimitris Tsiamitros
DSDimitris Stimoniaris
Dimitris Stimoniaris
Remotely performing real-time distributed generation control and a demand response is a basic aspect of the grid ancillary services provided by grid operators, both the transmission grid operators (TSOs) and distribution grid operators (DNOs), in order to ensure that voltage, frequency and power loads of the grid remain within safe limits. The stochastic production of electrical power to the grid from the distributed generators (DGs) from renewable energy sources (RES) in conjunction with the newly appeared stochastic demand consumers (i.e., electric vehicles) hardens the efforts of the DNOs to keep the grid’s operation within safe limits and prevent cascading blackouts while staying in compliance with the SAIDI and SAIFI indices during repair and maintenance operations. Also taking into consideration the aging of the existing grid infrastructure, and making it more prone to failure year by year, it is yet of great significance for the DNOs to have access to real-time feedback from the grid’s infrastructure—which is fast, has low-cost upgrade interventions, is easily deployed on the field and has a fast response potential—in order to be able to perform real-time grid management (RTGM). In this article, we present the development and deployment of a control system for DG units, with the potential to be installed easily to TSO’s and DNO’s substations, RES plants and consumers (i.e., charging stations of electric vehicles). This system supports a hybrid control mechanism, either via ripple signaling or through a network, with the latter providing real-time communication capabilities. The system can be easily installed on the electric components of the grid and can act as a gateway between the different vendors communication protocols of the installed electrical equipment. More specifically, a commercially available, low-cost board (Raspberry Pi) and a ripple control receiver are installed at the substation of a PV plant. The board communicates in real-time with a remote server (decision center) via a 5G modem and with the PV plants inverters via the Modbus protocol, which acquires energy production data and controls the output power of each inverter, while one of its digital inputs can be triggered by the ripple control receiver. The ripple control receiver receives on-demand signals with the HEDNO, triggering the digital input on the board. When the input is triggered, the board performs a predefined control command (i.e., lower the inverter’s power output to 50%). The board can also receive control commands directly from the remote server. The remote server receives real-time feedback of the acquired inverter data, the control signals from the ripple control receiver and the state and outcome of each performed control command.

30 September 2023 in Preprints.org
Verified
Preprint
Open access
PDF file
EBEvangelos Boutsiadis
Evangelos Boutsiadis
NPNikolaos Pasialis
Nikolaos Pasialis
NLNikolaos Lettas
Nikolaos Lettas
DTDimitris Tsiamitros
Dimitris Tsiamitros
DSDimitris Stimoniaris
Dimitris Stimoniaris
Remote distributed generation control and demand response is nowadays a basic need, especially for the Distributed Network Operators (DNOs). The integration of Renewable Energy Sources (RES) with stochastic production characteristics into the grid in conjunction with the newly appeared stochastic demand consumers (i.e., electric vehicles) hardens the ef-forts of the DNOs to keep the grid’s operation within safe limits and prevent cascading black-outs while staying in compliance with the SAIDI and SAIFI indices during maintenance and re-pair operations. Taking also under consideration the aging of the existing grid infrastructure, making it year by year more prone to failure, it is yet of great significance for the DNOs to have access to real-time feedback from grid’s infrastructure, fast, with low-cost upgrade interventions, easily deployed on the field and with fast response potential, in order to be able to perform real-time grid management (RTGM). In this article, we describe the architecture, development and deployment of a hybrid real-time control system of distributed generation (DG) units, which has the potential to be applied easily to DNO’s substations, RES plants and consumers (i.e. electric vehicles’ charging stations), that combines a low-cost minimum intervention into the electricity grid and its components and eliminates all communication interoperability problems between the different vendors’ installed electrical equipment.

18 November 2024 in Preprints.org
Verified
Preprint
Open access
PDF file
AKALEXANDRA KARAMOUZA
ALEXANDRA KARAMOUZA
TKTheofano Kollatou
Theofano Kollatou
DSDimitris Stimoniaris
Dimitris Stimoniaris
DTDimitris Tsiamitros
Dimitris Tsiamitros
NLNikolaos Lettas
Nikolaos Lettas
SBStefanos Beis
Stefanos Beis
Initially, the paper involves a thorough analysis and documentation of international literature (research publications, global standards like IEEE, European standards like EN, experimental outcomes, etc.), along with existing studies conducted by the Hellenic Distribution Network Operator (HEDNO) on these topics. Subsequently, there will be a comparative assessment between the international findings and Greek standards and regulations regarding these matters. The final stage includes presenting a substantiated and detailed recommendation for each technical issue. Where feasible, an optimal proposal for fiber optic cable installation is developed for each case, ensuring technical compliance with all constraints.