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Power-synchronization control (PSC) is a promising control strategy to improve the stability and performance of voltage-source converters (VSCs) in ultra-weak AC grids. However, evaluation of PSC to date has investigated performance only at single controller operating points, rather than holistically varying multiple controller gains. This paper develops a new methodology, based on small-signal eigenvalue analysis, to comprehensively analyze PSC-VSC stability. The maximum active power transfer of PSC is established across a broad range of controller tunings and the two-way and three-way couplings between the power-synchronization control, AC voltage control and high-pass current filter gains are quantified. A new stable tuning region is introduced, which represents the controller parameter space for stable operation. It is shown that PSC can achieve rated power transfer into an AC grid (short circuit ratio(SCR)=1) at multiple controller operating points, but dynamic performance varies significantly within this region. The robustness of this operating region to SCR changes is also investigated. The stability boundary and dynamic performance are validated using control hardware-in-the-loop experiments with a real-time digital simulator. Practical recommendations arising from this work are a set of controller gains that provide stability and good dynamic performance at high power transfer for ultra-weak grid-connected VSCs employing PSC.
Jennifer Frances Morris; Khaled Ahmed; Agusti Egea-Alvarez. Power-Synchronization Control for Ultra-Weak AC Networks: Comprehensive Stability and Dynamic Performance Assessment. IEEE Open Journal of the Industrial Electronics Society 2021, PP, 1 -1.
AMA StyleJennifer Frances Morris, Khaled Ahmed, Agusti Egea-Alvarez. Power-Synchronization Control for Ultra-Weak AC Networks: Comprehensive Stability and Dynamic Performance Assessment. IEEE Open Journal of the Industrial Electronics Society. 2021; PP (99):1-1.
Chicago/Turabian StyleJennifer Frances Morris; Khaled Ahmed; Agusti Egea-Alvarez. 2021. "Power-Synchronization Control for Ultra-Weak AC Networks: Comprehensive Stability and Dynamic Performance Assessment." IEEE Open Journal of the Industrial Electronics Society PP, no. 99: 1-1.
Low-frequency oscillations have been reported in several weak-grids-connected voltage-source-converter(VSC) systems. Although efforts have been devoted to understand the parametric and sensitivity impact of the VSC controller gains, a general formulation of the oscillation mechanism is still missing. Using transfer function dynamic modelling approach, we find that the outer loop active power control's bandwidth mainly determines the oscillation frequency. The PLL introduces a large phase lag around the frequency of the PLL bandwidth in weak grids conditions which decreases the oscillation damping. A simple but effective PI+Clegg integrator (CI) compensator is proposed to replace the standard outer loop active power controller compensating the PLL's phase delay and increase the oscillation damping. The results are verified in a real time digital simulator.
Guanglu Wu; Huadong Sun; Bing Zhao; Shiyun Xu; Xi Zhang; Agusti Egea-Alvarez; Shanshan Wang; Gen Li; Yingbiao Li; Xiaoxin Zhou. Low-Frequency Converter-Driven Oscillations in Weak Grids: Explanation and Damping Improvement. IEEE Transactions on Power Systems 2021, PP, 1 -1.
AMA StyleGuanglu Wu, Huadong Sun, Bing Zhao, Shiyun Xu, Xi Zhang, Agusti Egea-Alvarez, Shanshan Wang, Gen Li, Yingbiao Li, Xiaoxin Zhou. Low-Frequency Converter-Driven Oscillations in Weak Grids: Explanation and Damping Improvement. IEEE Transactions on Power Systems. 2021; PP (99):1-1.
Chicago/Turabian StyleGuanglu Wu; Huadong Sun; Bing Zhao; Shiyun Xu; Xi Zhang; Agusti Egea-Alvarez; Shanshan Wang; Gen Li; Yingbiao Li; Xiaoxin Zhou. 2021. "Low-Frequency Converter-Driven Oscillations in Weak Grids: Explanation and Damping Improvement." IEEE Transactions on Power Systems PP, no. 99: 1-1.
Significant research attention is focused on the stability and control of voltage-source converters (VSCs) in weak ac grids. However, the assessment of VSC control strategies has never been standardized, such that novel solutions proposed in the literature are not objectively evaluated against current best-practice. This paper establishes a comprehensive, standardized assessment framework for grid-connected VSC controllers, which allows objective comparison of novel controllers under development and established methods already in operation. The assessment consists of a tuning stage, time-domain analysis and frequency-domain analysis to form a complete evaluation that can be applied in its full aggregated form or as individual assessment steps. Three VSC controllers, namely vector current control, power-synchronization control and a virtual synchronous machine, are compared in this paper using small-signal models, time-domain simulations and control hardware-in-the-loop Real-Time Digital Simulation (RTDS) experiments to demonstrate the versatility and robustness of the proposed framework for controllers with very different structures.
Jennifer F. Morris; Khaled H. Ahmed; Agustí Egea-Àlvarez. Standardized Assessment Framework for Design and Operation of Weak AC Grid-Connected VSC Controllers. IEEE Access 2021, 9, 95282 -95293.
AMA StyleJennifer F. Morris, Khaled H. Ahmed, Agustí Egea-Àlvarez. Standardized Assessment Framework for Design and Operation of Weak AC Grid-Connected VSC Controllers. IEEE Access. 2021; 9 ():95282-95293.
Chicago/Turabian StyleJennifer F. Morris; Khaled H. Ahmed; Agustí Egea-Àlvarez. 2021. "Standardized Assessment Framework for Design and Operation of Weak AC Grid-Connected VSC Controllers." IEEE Access 9, no. : 95282-95293.
Medium voltage DC (MVDC) networks are attracting more attention amid increased renewables penetration. The reliability of these DC systems is critical, especially following grid contingencies to maintain critical loads supply and provide ancillary services, such as black-start. This paper proposes an innovative energy management system (EMS) to maintain reliable MVDC network operation under prolonged AC grid contingencies. Similar EMS designs in literature tend to focus on limited operating modes and fall short of covering comprehensive elongated blackout considerations. The proposed EMS in this paper aims to preserve the distribution network functionality of the impacted MVDC system through maintaining a constant DC bus voltage, maximizing critical load supply duration, and maintaining the MVDC system black-start readiness. These objectives are achieved through controlling generation units between Maximum Power Point Tracking (MPPT) and Voltage Regulation (VR) modes, and implementing a smart load shedding and restoration algorithm based on network parameters feedback, such as storage State of Change (SoC) and available resources. Practical design considerations for MVDC network participation in AC network black start, and the following grid synchronization steps are presented and tested as part of the EMS. The proposed system is validated through simulations and scaled lab setup experimental scenarios.
Abdulrahman Alassi; Khaled Ahmed; Agustí Egea-Àlvarez; Omar Ellabban. Innovative Energy Management System for MVDC Networks with Black-Start Capabilities. Energies 2021, 14, 2100 .
AMA StyleAbdulrahman Alassi, Khaled Ahmed, Agustí Egea-Àlvarez, Omar Ellabban. Innovative Energy Management System for MVDC Networks with Black-Start Capabilities. Energies. 2021; 14 (8):2100.
Chicago/Turabian StyleAbdulrahman Alassi; Khaled Ahmed; Agustí Egea-Àlvarez; Omar Ellabban. 2021. "Innovative Energy Management System for MVDC Networks with Black-Start Capabilities." Energies 14, no. 8: 2100.
As a result of increasing variability of network impedance, interest in impedance estimation techniques is growing. This review contextualises local impedance estimation techniques by providing a historical prospective on the uses of these techniques, from the early implementations designed to monitor power quality to the latest techniques integrated into converters designed to update the controller with the most recent network information. This is followed by clear and consolidated descriptions, a complete classification and comparison tables of local estimation techniques intended to assist engineers and researchers choose an estimation technique that is suitable to their application. The discussed techniques are then ranked for a range of application priorities such as accuracy, least disruptive to the network, most suitable for wide frequency spectrum estimations and rapidity of estimation. Practical applications of impedance estimation are discussed, such as network characterisation, anti-islanding detection, filter resonance avoidance and controller tuning. To conclude the review, future trends are identified.
Mathieu Kervyn De Meerendre; Eduardo Prieto-Araujo; Khaled H. Ahmed; Oriol Gomis-Bellmunt; Lie Xu; Agusti Egea-Alvarez. Review of Local Network Impedance Estimation Techniques. IEEE Access 2020, 8, 213647 -213661.
AMA StyleMathieu Kervyn De Meerendre, Eduardo Prieto-Araujo, Khaled H. Ahmed, Oriol Gomis-Bellmunt, Lie Xu, Agusti Egea-Alvarez. Review of Local Network Impedance Estimation Techniques. IEEE Access. 2020; 8 (99):213647-213661.
Chicago/Turabian StyleMathieu Kervyn De Meerendre; Eduardo Prieto-Araujo; Khaled H. Ahmed; Oriol Gomis-Bellmunt; Lie Xu; Agusti Egea-Alvarez. 2020. "Review of Local Network Impedance Estimation Techniques." IEEE Access 8, no. 99: 213647-213661.
Right-half-plain (RHP) zeros can significantly deteriorate a control system's dynamic performances as it exhibits non-minimum-phase behaviors. In this paper, we investigate the occurrence mechanism of RHP zeros in weak-grid-tied VSCs as well as provide guidance for minimizing their effects. A reduced-order multi-input multi-output (MIMO) transfer function of the weak-grid-tied VSC is firstly obtained. Then, the single-input single-output (SISO) transfer function to study the impact of the RHP zeros on the power response is further derived. The existence of RHP zeros is examined by applying the Routh criterion on the numerator of the SISO open-loop transfer function. We find that RHP zeros can exist either when the VSC works as an inverter or a rectifier. Furthermore, large grid impedance values as well as operation points with high active power values can result in a non-minimum-phase system. It is also shown that RHP zeros limit the minimum PLL bandwidth. Simulation results and RTDS experiments validate the correctness of the analysis and the conclusions obtained.
Guanglu Wu; Bing Zhao; Xi Zhang; Shanshan Wang; Agusti Egea-Alvarez; Yuanyuan Sun; Yingbiao Li; Deyang Guo; Xiaoxin Zhou. Impact of Non-Minimum-Phase Zeros on the Weak-Grid-Tied VSC. IEEE Transactions on Sustainable Energy 2020, 12, 1115 -1126.
AMA StyleGuanglu Wu, Bing Zhao, Xi Zhang, Shanshan Wang, Agusti Egea-Alvarez, Yuanyuan Sun, Yingbiao Li, Deyang Guo, Xiaoxin Zhou. Impact of Non-Minimum-Phase Zeros on the Weak-Grid-Tied VSC. IEEE Transactions on Sustainable Energy. 2020; 12 (2):1115-1126.
Chicago/Turabian StyleGuanglu Wu; Bing Zhao; Xi Zhang; Shanshan Wang; Agusti Egea-Alvarez; Yuanyuan Sun; Yingbiao Li; Deyang Guo; Xiaoxin Zhou. 2020. "Impact of Non-Minimum-Phase Zeros on the Weak-Grid-Tied VSC." IEEE Transactions on Sustainable Energy 12, no. 2: 1115-1126.
This paper studies the dynamic behaviors of weak-grid-tied VSCs with simplified transfer functions, which provides an accurate stability analysis and useful indications for tuning system parameters. A reduced-order multi-input multi-output (MIMO) transfer function that contains four single-input single-output (SISO) transfer functions for the weak-grid-tied VSC is first presented. It is found that the four SISO transfer functions share the same equivalent open-loop transfer function, i.e., the same stability conclusion. The Bode plots of the equivalent open-loop transfer function show that the inner current loop behaves as a band-pass filter whose maximum gain is approximately at the frequency of the PLL's bandwidth. By stability criterion, the harmonic amplification and instability occur when its maximum gain exceeds 0dB caused by high PLL's bandwidth, large grid impedance or high active power. It is also found that the target system is less stable when it works as an inverter than as a rectifier, due to the risk of the local positive feedback in the inverter mode. An effective criterion is further proposed to guide the selection of a proper PLL's bandwidth to ensure the stability of the VSC system. Simulation results validate the correctness of the analysis and the efficacy of the criterion.
Guanglu Wu; Huadong Sun; Xi Zhang; Agusti Egea-Alvarez; Bing Zhao; Shiyun Xu; Shanshan Wang; Xiaoxin Zhou. Parameter Design Oriented Analysis of the Current Control Stability of the Weak-Grid-Tied VSC. IEEE Transactions on Power Delivery 2020, 36, 1458 -1470.
AMA StyleGuanglu Wu, Huadong Sun, Xi Zhang, Agusti Egea-Alvarez, Bing Zhao, Shiyun Xu, Shanshan Wang, Xiaoxin Zhou. Parameter Design Oriented Analysis of the Current Control Stability of the Weak-Grid-Tied VSC. IEEE Transactions on Power Delivery. 2020; 36 (3):1458-1470.
Chicago/Turabian StyleGuanglu Wu; Huadong Sun; Xi Zhang; Agusti Egea-Alvarez; Bing Zhao; Shiyun Xu; Shanshan Wang; Xiaoxin Zhou. 2020. "Parameter Design Oriented Analysis of the Current Control Stability of the Weak-Grid-Tied VSC." IEEE Transactions on Power Delivery 36, no. 3: 1458-1470.
This paper provides the result of a techno-economic study of potential energy storage technologies deployable at wind farms to provide short-term ancillary services such as inertia response and frequency support. Two different scenarios are considered including a single energy storage system for the whole wind farm and individual energy storage for each wind turbine (located at either the dc or the ac side of its grid-side converter). Simulations are introduced to check the technical viability of the proposal with different control strategies. Power and energy capability requirements demanded by both specific services are defined for each studied case based on present and future grid code needs. Based on these requirements, the study compares a wide range of energy storage technologies in terms of present-day technical readiness and properties and identifies potential candidate solutions. These are flywheels, supercapacitors, and three chemistries out of the Li-ion battery family. Finally, the results of a techno-economic assessment (mainly based on weight, volume, lifetime, and industry-confirmed costings) detail the advantages and disadvantages of the proposed solutions for the different scenarios under consideration. The main conclusion is that none of the candidates are found to be clearly superior to the others over the whole range of scenarios. Commercially available solutions have to be tailored to the different requirements depending on the amount of inertia, maximum Rate of Change of Frequency and maximum frequency deviation to be allowed.
Hector Beltran; Sam Harrison; Agustí Egea-Àlvarez; Lie Xu. Techno-Economic Assessment of Energy Storage Technologies for Inertia Response and Frequency Support from Wind Farms. Energies 2020, 13, 3421 .
AMA StyleHector Beltran, Sam Harrison, Agustí Egea-Àlvarez, Lie Xu. Techno-Economic Assessment of Energy Storage Technologies for Inertia Response and Frequency Support from Wind Farms. Energies. 2020; 13 (13):3421.
Chicago/Turabian StyleHector Beltran; Sam Harrison; Agustí Egea-Àlvarez; Lie Xu. 2020. "Techno-Economic Assessment of Energy Storage Technologies for Inertia Response and Frequency Support from Wind Farms." Energies 13, no. 13: 3421.
This paper presents a new fast-acting backup protection strategy for future hybrid ac-dc distribution networks. By examining the impedance measured by an ac-connected distance protection relay, a unique characteristic is established for faults occurring on the dc-side of an embedded medium-voltage dc (MVDC) link, interconnecting two 33 kV distribution network sections. Based on the identified impedance characteristic, appropriate settings are developed and deployed on a verified software model of a commercially available distance protection relay. To remain stable for ac-side faults, it is found that the tripping logic of the device must be altered to provide correct time grading between standard, ac, protection zones and the fast-acting dc region, which can identify faults on the dc system within 40 ms. An additional confirmatory check is also employed to reduce the likelihood of mal-operation. The proposed solution is trialled on a test system derived from an actual distribution network, which employs distance protection, and is shown to provide stable operation for both standard ac-side faults and dc-side pole-pole-ground and pole-pole events.
Lewis C. Hunter; Campbell David Booth; Agusti Egea-Alvarez; Adam Dysko; Stephen J. Finney; Adria Junyent-Ferre. A New Fast-Acting Backup Protection Strategy for Embedded MVDC Links in Future Distribution Networks. IEEE Transactions on Power Delivery 2020, 36, 861 -869.
AMA StyleLewis C. Hunter, Campbell David Booth, Agusti Egea-Alvarez, Adam Dysko, Stephen J. Finney, Adria Junyent-Ferre. A New Fast-Acting Backup Protection Strategy for Embedded MVDC Links in Future Distribution Networks. IEEE Transactions on Power Delivery. 2020; 36 (2):861-869.
Chicago/Turabian StyleLewis C. Hunter; Campbell David Booth; Agusti Egea-Alvarez; Adam Dysko; Stephen J. Finney; Adria Junyent-Ferre. 2020. "A New Fast-Acting Backup Protection Strategy for Embedded MVDC Links in Future Distribution Networks." IEEE Transactions on Power Delivery 36, no. 2: 861-869.
This paper presents a small-signal analysis of different grid side controllers for full power converter wind turbines with inertia response capability. In real wind turbines, the DC link controller, the drivetrain damping controller and the inertial response might present contradictory control actions in a close bandwidth range. This situation might lead to reduced control performance, increased component stress and non-compliance of connection agreements. The paper presents an analysis of the internal wind turbine dynamics by considering different grid-side converter control topologies: standard current control used in the wind industry, standard current control with inertia emulation capabilities and virtual synchronous machines. Comments are made on the similarities between each topology and the negative effects and limits, and possible remedies are discussed. Finally, the conclusion poses that the inclusion of a DC link voltage controller reduces the ability of a converter to respond to external frequency events without energy storage. The degradation increases with the DC link voltage control speed.
Callum Henderson; Dimitrios Vozikis; Derrick Holliday; Xiaoyan Bian; Agustí Egea-Àlvarez. Assessment of Grid-Connected Wind Turbines with an Inertia Response by Considering Internal Dynamics. Energies 2020, 13, 1038 .
AMA StyleCallum Henderson, Dimitrios Vozikis, Derrick Holliday, Xiaoyan Bian, Agustí Egea-Àlvarez. Assessment of Grid-Connected Wind Turbines with an Inertia Response by Considering Internal Dynamics. Energies. 2020; 13 (5):1038.
Chicago/Turabian StyleCallum Henderson; Dimitrios Vozikis; Derrick Holliday; Xiaoyan Bian; Agustí Egea-Àlvarez. 2020. "Assessment of Grid-Connected Wind Turbines with an Inertia Response by Considering Internal Dynamics." Energies 13, no. 5: 1038.
A methodology is presented to derive the small-signal admittance of a converter based control system in the pn-frame. Such a methodology makes use of a set of derived equations which link the qd-frame small-signal admittance data to the corresponding pn-frame small-signal admittance terms. Compared to existing results providing the pn-frame small-signal impedance of a grid connected converter, the presented technique allows a calculation of the pn-frame small-signal admittance (or impedance) when additional elements are present in the controller, as in many practical designs. The presented technique is therefore generic and provides a systematic way to calculate the pn-frame admittance regardless of the used converter control scheme. In the study, the method has been applied to assess how different parts of the controller affect the pn-frame admittance terms and, in particular, the cross-coupling which exists between its positive and negative sequence terms. Thereby, the results of the proposed methodology have been used to study the impact of the negative sequence current compensator on the stability performance of a grid-connected converter. Experimental tests using a real hardware set up are used to support the obtained results.
Gabriele Amico; Agusti Egea-Alvarez; Paul Brogan; Shuo Zhang; Shuo Zang. Small-Signal Converter Admittance in the $pn$-Frame: Systematic Derivation and Analysis of the Cross-Coupling Terms. IEEE Transactions on Energy Conversion 2019, 34, 1829 -1838.
AMA StyleGabriele Amico, Agusti Egea-Alvarez, Paul Brogan, Shuo Zhang, Shuo Zang. Small-Signal Converter Admittance in the $pn$-Frame: Systematic Derivation and Analysis of the Cross-Coupling Terms. IEEE Transactions on Energy Conversion. 2019; 34 (4):1829-1838.
Chicago/Turabian StyleGabriele Amico; Agusti Egea-Alvarez; Paul Brogan; Shuo Zhang; Shuo Zang. 2019. "Small-Signal Converter Admittance in the $pn$-Frame: Systematic Derivation and Analysis of the Cross-Coupling Terms." IEEE Transactions on Energy Conversion 34, no. 4: 1829-1838.
A. Egea-Àlvarez; S. Fekriasl; E. Prieto-Araujo. Improved droop control with DC grid resonance damping capability. 15th IET International Conference on AC and DC Power Transmission (ACDC 2019) 2019, 1 .
AMA StyleA. Egea-Àlvarez, S. Fekriasl, E. Prieto-Araujo. Improved droop control with DC grid resonance damping capability. 15th IET International Conference on AC and DC Power Transmission (ACDC 2019). 2019; ():1.
Chicago/Turabian StyleA. Egea-Àlvarez; S. Fekriasl; E. Prieto-Araujo. 2019. "Improved droop control with DC grid resonance damping capability." 15th IET International Conference on AC and DC Power Transmission (ACDC 2019) , no. : 1.
This article introduces a novel power coordination method for the operation under restricted conditions of offshore wind power plants connected with VSC-HVDC without the use of communications between converter stations. The proposed method consists of the coordination of the Dynamic Braking Resistor (DBR) located in the Grid Side Converter (GSC) and the wind power plant in order to maintain the DC voltage stability. The coordination is achieved by means of two droop controllers, one for the GSC-DBR and another one for the offshore wind power plant. These droop gains are selected to avoid limit cycles using the describing function approach. The proposed power coordination scheme is tested and verified by means of dynamic simulations.Postprint (author's final draft
Agustí Egea-Àlvarez; Mònica Aragüés-Peñalba; Eduardo Prieto-Araujo; Oriol Gomis-Bellmunt. Power reduction coordinated scheme for wind power plants connected with VSC-HVDC. Renewable Energy 2017, 107, 1 -13.
AMA StyleAgustí Egea-Àlvarez, Mònica Aragüés-Peñalba, Eduardo Prieto-Araujo, Oriol Gomis-Bellmunt. Power reduction coordinated scheme for wind power plants connected with VSC-HVDC. Renewable Energy. 2017; 107 ():1-13.
Chicago/Turabian StyleAgustí Egea-Àlvarez; Mònica Aragüés-Peñalba; Eduardo Prieto-Araujo; Oriol Gomis-Bellmunt. 2017. "Power reduction coordinated scheme for wind power plants connected with VSC-HVDC." Renewable Energy 107, no. : 1-13.
This study presents a new sensorless control for small wind turbine clusters with a single power converter with a direct torque control algorithm. The proposed system consists of a wind farm connected to a back-to-back power converter that interfaces the wind farm with the AC grid. The studied wind turbines are based on fixed-speed wind turbines equipped with squirrel cage induction generators with individual pitch control. The presented structure permits to reduce the number of converters and allows to accomplish the grid codes (fault ride through capability and reactive power support). Furthermore, the generated active power can be reduced according to grid operator requirements. The presented control scheme can be applied to wind turbine repowering projects, wind farms connected to a microgrid, even, new small onshore and offshore power plants. The system performance and stability is studied and validated by means of dynamic simulations.
Agustí Egea‐Àlvarez; Mónica Aragüés‐Peñalba; Oriol Gomis‐Bellmunt; Joan Rull‐Duran; Antoni Sudrià‐Andreu. Sensorless control of a power converter for a cluster of small wind turbines. IET Renewable Power Generation 2016, 10, 721 -728.
AMA StyleAgustí Egea‐Àlvarez, Mónica Aragüés‐Peñalba, Oriol Gomis‐Bellmunt, Joan Rull‐Duran, Antoni Sudrià‐Andreu. Sensorless control of a power converter for a cluster of small wind turbines. IET Renewable Power Generation. 2016; 10 (5):721-728.
Chicago/Turabian StyleAgustí Egea‐Àlvarez; Mónica Aragüés‐Peñalba; Oriol Gomis‐Bellmunt; Joan Rull‐Duran; Antoni Sudrià‐Andreu. 2016. "Sensorless control of a power converter for a cluster of small wind turbines." IET Renewable Power Generation 10, no. 5: 721-728.
This paper presents results from the KIC InnoEnergy project: Generic DC grid off-line and real-time simulation models and tools (Action 2.1, Subtask 2.1.1). The work reported here is focused on the development of a generic voltage source converter (VSC) model and its control schemes. Different test systems were designed and implemented in simulation tools and an experimental platform to verify the proposed generic model. Consistent simulation and emulation performances indicate that the generic model and its control schemes are applicable for VSC-HVDC operation, and thus, they can facilitate further research and development in DC grids.
Luigi Vanfretti; Wei Li; Agustí Egea-Àlvarez; Oriol Gomis-Bellmunt. Generic VSC-based DC Grid EMT modeling, simulation, and validation on a scaled hardware platform. 2015 IEEE Power & Energy Society General Meeting 2015, 1 -5.
AMA StyleLuigi Vanfretti, Wei Li, Agustí Egea-Àlvarez, Oriol Gomis-Bellmunt. Generic VSC-based DC Grid EMT modeling, simulation, and validation on a scaled hardware platform. 2015 IEEE Power & Energy Society General Meeting. 2015; ():1-5.
Chicago/Turabian StyleLuigi Vanfretti; Wei Li; Agustí Egea-Àlvarez; Oriol Gomis-Bellmunt. 2015. "Generic VSC-based DC Grid EMT modeling, simulation, and validation on a scaled hardware platform." 2015 IEEE Power & Energy Society General Meeting , no. : 1-5.
This paper focuses on the droop-based dc voltage control design for multiterminal VSC-HVDC grid systems, considering the ac and the dc system dynamics. The droop control design relies on detailed linearized models of the complete multiterminal grid, including the different system dynamics, such as the dc grid, the ac grid, the ac connection filters, and the converter inner controllers. Based on the derived linear models, classical and modern control techniques are applied to design the different controllers, including a multivariable frequency analysis to design the grid voltage droop control. In combination with the droop control, a dc oscillation damping scheme is proposed in order to improve system performance. The control design is validated through simulations of a three-terminal system.
Eduardo Prieto-Araujo; Agusti Egea; Sajjad Fekriasl; Oriol Gomis-Bellmunt. DC Voltage Droop Control Design for Multiterminal HVDC Systems Considering AC and DC Grid Dynamics. IEEE Transactions on Power Delivery 2015, 31, 575 -585.
AMA StyleEduardo Prieto-Araujo, Agusti Egea, Sajjad Fekriasl, Oriol Gomis-Bellmunt. DC Voltage Droop Control Design for Multiterminal HVDC Systems Considering AC and DC Grid Dynamics. IEEE Transactions on Power Delivery. 2015; 31 (2):575-585.
Chicago/Turabian StyleEduardo Prieto-Araujo; Agusti Egea; Sajjad Fekriasl; Oriol Gomis-Bellmunt. 2015. "DC Voltage Droop Control Design for Multiterminal HVDC Systems Considering AC and DC Grid Dynamics." IEEE Transactions on Power Delivery 31, no. 2: 575-585.
This article introduces a hierarchical power control structure for Multi-terminal High Voltage Direct Current (MT-HVDC) systems. The presented hierarchy is similar to the control structure used in classical AC transmission systems and is divided in primary, secondary and tertiary control actions. The voltage control in the MT-HVDC scheme acts in a way similar to the primary control action of generators in AC systems, while the secondary control action is performed by an outer power control loop. The design of the individual controllers and the interaction between these control loops is discussed in detail. Furthermore, the operational characteristics are described and the main operating points are identified. Scenarios including a power reference change and a grid side converter disconnection have been simulated in order to test and verify the proposed method. The main contribution of the paper is the development of a control methodology, providing a separation of the different control actions in different time domains, similar to what is already in use (and therefore known) within traditional power systems.
Agustí Egea-Alvarez; Jef Beerten; Dirk Van Hertem; Oriol Gomis-Bellmunt. Hierarchical power control of multiterminal HVDC grids. Electric Power Systems Research 2015, 121, 207 -215.
AMA StyleAgustí Egea-Alvarez, Jef Beerten, Dirk Van Hertem, Oriol Gomis-Bellmunt. Hierarchical power control of multiterminal HVDC grids. Electric Power Systems Research. 2015; 121 ():207-215.
Chicago/Turabian StyleAgustí Egea-Alvarez; Jef Beerten; Dirk Van Hertem; Oriol Gomis-Bellmunt. 2015. "Hierarchical power control of multiterminal HVDC grids." Electric Power Systems Research 121, no. : 207-215.
This paper addresses an advanced vector current control for a voltage source converter (VSC) connected to a weak grid. The proposed control methodology permits high-performance regulation of the active power and the voltage for the feasible VSC range of operation. First, the steady state characteristics for a power converter connected to a very weak system with a short circuit ratio (SCR) of 1 are discussed in order to identify the system limits. Then, the conventional vector control (inner loop) and the conventional power/voltage control (outer loop) stability and frequency responses are analyzed. From the analysis of the classic structure, an enhanced outer loop based on a decoupled and gain-scheduling controller is presented and its stability is analyzed. The proposed control is validated by means of dynamic simulations and it is compared with classic vector current control. Simulation results illustrate that the proposed control system could provide a promising approach to tackle the challenging problem of VSC in connection with weak AC grids.
Agusti Egea; Sajjad Fekriasl; Fainan Hassan; Oriol Gomis-Bellmunt. Advanced Vector Control for Voltage Source Converters Connected to Weak Grids. IEEE Transactions on Power Systems 2015, 30, 3072 -3081.
AMA StyleAgusti Egea, Sajjad Fekriasl, Fainan Hassan, Oriol Gomis-Bellmunt. Advanced Vector Control for Voltage Source Converters Connected to Weak Grids. IEEE Transactions on Power Systems. 2015; 30 (6):3072-3081.
Chicago/Turabian StyleAgusti Egea; Sajjad Fekriasl; Fainan Hassan; Oriol Gomis-Bellmunt. 2015. "Advanced Vector Control for Voltage Source Converters Connected to Weak Grids." IEEE Transactions on Power Systems 30, no. 6: 3072-3081.
Inspec keywords: renewable energy sources; reactive power; power capacitors; load flow; power grids; HVDC power transmission Subjects: d.c. transmission; Energy resources; Other power apparatus and electric machines
Agusti Egea; Oriol Gomis-Bellmunt; F. Hassan; C. Barker. Capability curves of a VSC-HVDC connected to a weak AC grid considering stability and power limits. 11th IET International Conference on AC and DC Power Transmission 2015, 053 (5 .) -053 (5 .).
AMA StyleAgusti Egea, Oriol Gomis-Bellmunt, F. Hassan, C. Barker. Capability curves of a VSC-HVDC connected to a weak AC grid considering stability and power limits. 11th IET International Conference on AC and DC Power Transmission. 2015; ():053 (5 .)-053 (5 .).
Chicago/Turabian StyleAgusti Egea; Oriol Gomis-Bellmunt; F. Hassan; C. Barker. 2015. "Capability curves of a VSC-HVDC connected to a weak AC grid considering stability and power limits." 11th IET International Conference on AC and DC Power Transmission , no. : 053 (5 .)-053 (5 .).
Z. Solhjoukhah; A. Egea-Alvarez; O. Gomis-Bellmunt. Voltage Control of Offshore Load Connected to a Multi-Terminal HVDC Transmission System. 11th IET International Conference on AC and DC Power Transmission 2015, 1 .
AMA StyleZ. Solhjoukhah, A. Egea-Alvarez, O. Gomis-Bellmunt. Voltage Control of Offshore Load Connected to a Multi-Terminal HVDC Transmission System. 11th IET International Conference on AC and DC Power Transmission. 2015; ():1.
Chicago/Turabian StyleZ. Solhjoukhah; A. Egea-Alvarez; O. Gomis-Bellmunt. 2015. "Voltage Control of Offshore Load Connected to a Multi-Terminal HVDC Transmission System." 11th IET International Conference on AC and DC Power Transmission , no. : 1.