95 research outputs found
A novel wide-area control for general application to inverter-based resources in power systems
No full textThe article illustrates the wide-synchronization control, a novel wide-area control for general application to inverter-based resources. The principle is first introduced from a theoretical point of view, including a mathematical proof of the concept, a technological assessment of grid-following and grid-forming converters as actuators, and the examination of the effects of the latencies. The wide-synchronization control is then demonstrated with the application to two case-studies, the standard two-area benchmark system and the large-scale European power system. Analysis and results indicate that the proposed control can remarkably improve the dynamic characteristics of the system, securing a stable operation with a high degree of flexibility and even under critical conditions
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
STUDI DI TRANSITORI ELETTROMECCANICI ED ELETTROMAGNETICI PER LINEE MISTE DI TRASMISSIONE AEREOCAVO
No full textPower System Oscillations with Different Prevalence of Grid-Following and Grid-Forming Converters
No full textThe 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
Primary Frequency Control in the Power System of Continental Europe including the Dynamics of the HVDC Link France-Great Britain
No full textThe paper presents a study of primary frequency control within the power system of Continental Europe (CE) including the dynamics of the high voltage direct current (HVDC) link between France and Great Britain (GB). The large-scale dynamic model of the CE system originally provided by ENTSO-E is extended with a more detailed representation of the whole HVDC interconnection. The dynamics of the GB synchronous area is
also considered in the analysis, implementing a system equivalent suitable for primary frequency control studies. The opportunity of frequency containment reserve exchange between the two areas through the link is also investigated, considering supplementary frequency controls within the HVDC control system, namely synthetic inertia and fast frequency response. The overall system is then simulated in two different scenarios: a base case of all synchronous generation, and a reduced inertia scenario with the introduction of a given amount of non-synchronous generation
share. The reference incident for the CE system of 3 GW loss is considered for the analysis. The specific effects on the frequency dynamics of the system in the different operating conditions are illustrated and discussed
Wide-Area Damping Control for Clustered Microgrids
No full textThe increasing integration of renewable energy sources and distributed generation has led to new challenges in maintaining power system stability. This work presents a novel approach to wide-area damping control (WADC) for clustered microgrids, addressing inter-area oscillations and enhancing system stability. The proposed methodology leverages wide-area measurements and clustering algorithms to coordinate microgrid participation in damping control. A specific WADC concept is first formulated, detailing the mathematical background and the emergence of damping couplings. A bio-inspired flocking algorithm is introduced to determine how the microgrids are clustered, coordinated, and controlled. For that, three particular principles of the flocking algorithm are discussed. The developed control strategy is applied to the IEEE 68-bus benchmark system, where microgrids serve as actuators of the WADC to stabilize the oscillations in the system. Simulation results demonstrate significant improvements in damping performance, achieving stable system dynamics with minimal impact on microgrid resources. The findings highlight the feasibility of integrating microgrids into wide-area control schemes, offering a scalable solution for modern power grids with high renewable penetration
Transient behaviour of a “mixed” overhead-cable EHV line under lightning events
No full textRecently, in many countries have been undergone or are planning links with AC extra-high voltage (EHV) underground cables. Cable lines offer the possibility of a reduced environment impact and for this reason they are often the only alternative for the reinforcement or the expansion of power system accepted by public opinion. The coexistence of overhead and cable line in the so called ¿mixed¿ lines, however, raises several questions regarding their behaviour both in steady state and in transient. The purpose of this work is to investigate the transient behaviour of a mixed overhead-cable EHV line under lightning events, describing the effects of the following overvoltages on the system. The mixed line analyzed is a known case found in literature: the results obtained by the model are assumed as term of comparison with the known case. The model thus validated is used for further analysis, taking into account different configuration of the mixed system. The events subsequent lightning may be different: the study considers the shielding failure and the direct stroke on tower, with the possibility of back flashover along insulators. The analysis, carried out in PSCAD/EMTDC environment, has shown that shielding failure does not represent a critical event to mixed line and back flashover occurs for fast waveshape and high value of peak current
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