1,720,991 research outputs found
Damping-enhanced schemes and wide-synchronization control for grid-forming converters
No full textThe paper presents a comparison between grid-forming controls with enhanced damping characteristics and the wide-area control with participation of grid-forming converters, the so called wide-synchronization control. First, an analytical comparison of the considered solutions is provided, deriving the closed-loop transfer functions for all the schemes under specific assumptions. Then, a simulation-based comparison is discussed, referring to the large scale dynamic model of the European power system and considering two possible scenarios of grid-forming integration. The results of both analytical and simulation-based comparisons consistently indicate the better performances of the wide-synchronization control, for a significant reduction of frequency oscillations and instantaneous frequency deviations occurring after a disturbance in the system. The wide-synchronization control proves to be effective already with a limited number of grid-forming sources participating in the control
Frequency dynamics of power systems with temporally distributed disturbances
No full textThe frequency dynamics and stability of power systems is essentially affected by nature and characteristics of the disturbances occurring in the system. Conventionally, frequency transients are examined assuming a single disturbance applied at a given time. However, actual incidents in the power systems can be generally composed of a temporal sequence of events, and thus characterized by multiple power imbalances of different magnitudes and time offsets. The consideration of the effects of the temporal distribution of power imbalances is important for two main reasons: the impact on the frequency dynamics of the system in terms of frequency metrics such as minimum instantaneous frequency and maximum absolute rate of change of frequency, and the correct representation of the dynamic behaviour of the system also for complex events such system separation. The work provides an analytical approach for the theoretical study of the frequency dynamics with temporally distributed power imbalances. The analytical approach is then used to examine the impact of multiple disturbances having different magnitudes and time offsets on the typical frequency metrics used to characterize the transient performances of the system. The concepts derived in the work are finally applied to the case of an actual event occurred in the Continental Europe power system, showing the fundamental role of considering temporally distributed power imbalances for a correct and accurate assessment of the dynamics of the system
Power System Oscillations with Different Prevalence of Grid-Following and Grid-Forming Converters
Full text linkThe oscillatory behaviour of the power system is an aspect that is significantly affected by the increasing integration of converter-based generation sources. Several works address the impact of non-synchronous generation on the operation of the system from different points of view, but only a few studies focus on power-frequency oscillations with a prevalence of generation sources interfaced through power electronics. A lack of research can be found in particular in the comparative analysis of the two main control strategies for power converters, namely grid-following and grid-forming. The article aims to contribute to this direction, starting from a theoretical analysis of the two control structures and then examining the case study of an existing transmission system. The research provides a specific insight into the fundamental aspects related to synchronisation mechanism and inertial capabilities of both grid-following with synthetic inertia and grid-forming controls. The difference in the relationship between synchronisation unit and inertial capability is recognised as the fundamental aspect determining the different impacts on the oscillatory characteristics of the system. The observation derived in the theoretical analysis is then applied to an actual power system with a high predominance of converter-based generation, considering the Colombian interconnected national system as a case study
Synchronizing Interactions Between Different Types of Grid-Forming Converters in Smart Grids
No full textThe work investigates the transient synchronizing interactions between different types of grid-forming controls. Two well-known grid-forming schemes are implemented and considered for analysis: a droop-based control and a swing-based control. The two controls are examined for a temporary loss of synchronism. The analysis is performed considering two different conditions for the grid interconnecting the converters: a resistive-inductive grid and a mainly inductive grid. The first case corresponds to actual conditions in low and medium voltage applications. The second case is realized with the implementation of a virtual reactance in the grid-forming control scheme. The analysis of the results provides a specific insight on the characteristics of the synchronizing interactions between the different types of grid-forming converters, indicating the possibility of steep reactions, mutual oscillations and unsymmetrical interactions
The 10-Bus Model of the Italian Power System: A Tool for Multi-Site Co-Simulations
No full textThe paper presents the 10-bus model of the Italian power system, with a particular focus on the opportunity of using the model for multi-site co-simulations. The model is a simplified version of the Italian power system, where the main structure of the 380 kV transmission system interconnecting southern and northern Italy is reflected, and the total load and generation are distributed proportionally to the represented regions. The model is developed in MATLAB/Simulink, and it is compiled for real-time simulation with the OPAL-RT technologies. Some possible applications of the model for multi-site distributed co-simulations are introduced and discussed, showing also the suitability of the model in terms of variable multi-site configurations
Power system dynamic analysis in future energy scenarios with high penetration of renewable energy sources — case study: Sicilian electrical grid
No full textIn the near future, Sicily will undergo an unprecedented penetration of renewable sources in its electricity generation mix. In response to these developments, several grid enhancement initiatives have been planned, including HVDC infrastructure and interconnections with foreign systems. This paper presents the results of dynamic studies on 2030 energy scenarios developed by the Italian institute Ricerca Sistema Energetico (RSE). These studies consider severe contingencies and evaluate various combinations of regulating resources, both traditional and innovative, including Grid Forming control. The results indicate that relying solely on traditional regulation during contingencies leads to instability, emphasizing the urgent need to involve all available resources in the power system's regulation mechanisms. Among the most interesting findings is the case of the Grid Forming control applied to the Tyrrhenian Link: even in the absence of regulation from the renewable sources present on the island, this approach successfully keeps the frequency drift within the permissible 1.5 Hz range. This demonstrates the significant strategic value of the infrastructure when deployed to provide dynamic support to the power system
THE OPPORTUNITY OF GRID-FORMING CONVERTERS IN THE WIDE-AREA CONTROL OF POWER SYSTEMS
No full textIn conventional wide-area control schemes, the actuators are typically the power system stabilizers of synchronous machines. The control action, in this case, can not directly act upon the power-angle relationship of the machines. In this context, the gridforming control for power converters offers the opportunity of an effective wide-area control: grid-forming converters present in fact a direct formulation of the power-angle control law, and therefore the possibility of directly acting upon it. The paper proposes an extension of the grid-forming control, including a specific additional control action based on a remote frequency signal. The proposed concept is proved with a simple representative system, and then demonstrated with two application cases, the standard IEEE 39-bus system and the European power system. The results indicate that the proposed participation of grid-forming converters in the wide-area control leads to a considerable improvement of the dynamic characteristics of the system
Grid-Forming Operation of the HVDC Tyrrhenian Link-East for Improved Frequency Transients
No full textThe paper examines the possibility of operating the VSC (Voltage Source Converter)-based HVDC (High Voltage Direct Current) Tyrrhenian Link-East with grid-forming capabil-ities. The investigations are focused on the frequency transients, and on the possible contribution which can be provided by the Tyrrhenian Link-East to the system. This infrastructure has a strategic importance, and it is designed to support the energy transition enabling a greater integration of renewable energy sources. The dynamic analysis is performed on a simplified 10-bus simulation model of the continental Italian transmission system linked to an equivalent Sicilian network, and it examines different types of contingencies. The results preliminarily suggest that the Tyrrhenian Link-East can effectively contribute to the frequency control of the system, and that the grid-forming capability represents a valid opportunity for the operation of the VSC-HVDC converters of the link
Grid-Forming Technology as Solution to Improve Voltage Stability: A Case-Study on the Italian Transmission System
No full textThe paper presents the application of the gridforming technology as solution to improve the voltage stability of the system following a critical contingency. A simplified pseudo model of the Italian transmission system is taken as reference case. The model is simulated under the assumptions of a theoretical forward-looking scenario, where a severe contingency would lead to critical conditions for the system. The results indicate the benefit of the grid-forming technology to effectively improve the voltage stability, thus ensuring a secure and stable operation of the system
Assessing the Grid Impact of Renewable Energy Communities in a Small Island
No full textThe paper presents a study carried out on the island of Pantelleria aimed at assessing the impact of the rise of renewable energy communities (RECs) on the distribution grid parameters. A comparison of various scenarios is done considering different operational strategies of BESSes and electric storage water heaters and different penetration of photovoltaic systems, whose maximum power is defined according to the Italian requirements for small islands (Decree “Isole minori”). The analysis of the impact on the grid is a key element for the evolution and development of RECs in small islands. The study highlight the beneficial impacts of RECs on the distribution grid if associated with suitable Demand Response strategies
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