Sainz, L.; Cheah-Mane, M.; Monjo, L.; Liang, Jun; Gomis-Bellmunt, O. IEEE Journal of emerging and selected topics in power electronics Vol. 5, num. 4, p. 1499-1512 DOI: 10.1109/JESTPE.2017.2707533 Data de publicació: 2017-12-01 Article en revista
Resonance instabilities in power systems can be assessed with the positive-net-damping stability criterion. This criterion is a review of the complex torque coefficients method, but it does not provide the frequency of the closed-loop oscillatory modes. This paper presents an alternative approach of the positive-net-damping stability criterion to analyze electrical resonance instability. In this approach, resonance instabilities are identified in feedback systems derived from impedance-based equivalent circuits. The proposed approach is used to characterize the frequency of closed-loop oscillatory modes and identify the physical and control parameters of the system that increase or reduce the damping of these modes. The extension of the proposed approach to study the stability of single-input single-output and multiple-input multiple-output feedback systems is analyzed, and the approach is also compared with other stability methods in the literature. An example of an offshore wind power plant illustrates the theoretical study and compares the proposed approach with different methods to evaluate stability. Time-domain simulations in Power System Computer Aided Design/Electro Magnetic Transient Design and Control (PSCAD/EMTDC) are shown to validate the stability study.
Abstract—This paper analyses the frequency support characteristics of multi-terminal VSC-HVDC (MTDC) schemes using the energy transferred from wind turbine rotating mass and other AC systems. An alternative coordinated control (ACC) scheme, which gives priority to a frequency versus active power droop fitted to onshore VSCs is proposed to: (i) transfer wind turbine recovery power to undisturbed AC grids and (ii) allow correct control operation of MTDC systems during multiple power imbalances on different AC grids. The fast frequency response capability of MTDC systems equipped with the proposed ACC scheme is compared against a coordinated control (CC) scheme, which uses a frequency versus DC voltage droop. The frequency control schemes are demonstrated on an experimental test rig which represents a 3-terminal HVDC system. Also, the MTDC frequency support capability when wind farms do not provide extra power is tested using a 4-terminal HVDC system.
Cheah-Mane, M.; Sainz, L.; Liang, J.; Jenkins, N.; Ugalde , C. IEEE transactions on power systems Vol. 32, num. 6, p. 4579-4589 DOI: 10.1109/TPWRS.2017.2663111 Data de publicació: 2017-11-01 Article en revista
Electrical resonances may compromise the stability of HVDC-connected offshore wind power plants (OWPPs). In particular, an offshore HVDC converter can reduce the damping of an OWPP at low-frequency series resonances, leading to the system instability. The interaction between offshore HVDC converter control and electrical resonances of offshore grids is analyzed in this paper. An impedance-based representation of an OWPP is used to analyze the effect that offshore converters have on the resonant frequency of the offshore grid and on system stability. The positive-net-damping criterion, originally proposed for subsynchronous analysis, has been adapted to determine the stability of the HVDC-connected OWPP. The reformulated criterion enables the net damping of the electrical series resonance to be evaluated and establishes a clear relationship between electrical resonances of the HVDC-connected OWPPs and stability. The criterion is theoretically justified, with analytical expressions for low-frequency series resonances being obtained and stability conditions defined based on the total damping of the OWPP. Examples are used to show the influence that HVDC converter control parameters and the OWPP configuration have on stability. A root locus analysis and time-domain simulations in PSCAD/EMTDC are presented to verify the stability conditions.
Cheah-Mane, M.; Sainz, L.; Eduardo Prieto-Araujo; Gomis-Bellmunt, O. Wind Integration Workshop : International Workshop on Large-Scale Integration of Wind Power into Power Systems as well as on Transmission Networks for Offshore Wind Power Plants Data de presentació: 2017-10-25 Presentació treball a congrés
Sainz, L.; Monjo, L.; Pedra, J.; Cheah-Mane, M.; Liang, Jun; Gomis-Bellmunt, O. IET electric power applications Vol. 11, num. 2, p. 157-168 DOI: 10.1049/iet-epa.2016.0241 Data de publicació: 2017-02-01 Article en revista
Wind turbine harmonic emissions due to power electronics are a well-known power quality concern in wind power plants (WPPs). This problem may be increased by resonances because they amplify harmonic distortion around resonance frequencies. Hence, the resonance phenomenon is widely analysed in the literature. Resonance studies usually consider wind turbines (WTs) as ideal current sources, which can lead to inaccurate results. The study explores the effect of WT converter control on WPP harmonic response. It contributes expressions of WT equivalent harmonic impedance including current control of the grid side converter. This impedance allows WT converter control to be considered in WPP modelling to analyse its effect on harmonic response and resonances. PSCAD and Matlab/Simulink simulations were performed to validate the analytical expressions and illustrate the usefulness of the work in predicting harmonic distortions at WT terminals in actual WPPs.
Onshore and offshore wind power plants comprising wind turbines equipped with power converters are increasing in number worldwide. Harmonic emissions in power converters distort currents and voltages, leading to power quality problems. Low order resonances in the collector grid can increase the impact of wind turbine emissions. These resonances may also produce electrical instabilities in poorly damped wind power plants. The paper performs frequency scan with Matlab/Simulink simulations and compares low order frequencies of parallel resonances in onshore and offshore wind power plants. It also investigates the influence of wind power plant variables on resonance. Finally, simplified equivalent circuits of wind power plants are proposed to study low order parallel resonances.
VSC-HVDC interconnectors are expected to provide ancillary services to the grids where they are connected. In this paper, frequency containment reserve is implemented in a VSC-HVDC interconnector between Great Britain and Continental Europe and potential interactions are analysed in terms of maximum frequency deviations. The frequency interactions are evaluated in a current scenario and future scenarios that considers an increase of renewable generation and HVDC interconnection.
Sainz, L.; Mesas, J. J.; Monjo, L.; Pedra, J.; Cheah-Mane, M. IEEE International Conference Electric Power Quality and Supply Reliability p. 139-144 DOI: 10.1109/PQ.2016.7724103 Data de presentació: 2016-08-30 Presentació treball a congrés
Wind power plant stability can be affected by the interaction between the wind turbine and the resonances in the collector grid. This paper presents an electrical resonance instability study applied to wind power plants.
The influence of feedforward low pass filter bandwidth and converter filter inductance on wind power plant stability is analyzed with examples. An impedance-based representation of the wind power plant is used to identify the resonances and analyze stability problems. PSCAD/EMTDC time-domain simulations are also shown to validate the stability study.
Wind power plant stability can be affected by the interaction between the wind turbine and the resonances
in the collector grid. This paper presents an electrical resonance instability study applied to wind power plants.
The influence of feedforward low pass filter bandwidth and converter filter inductance on wind power plant stability
is analyzed with examples. An impedance-based representation of the wind power plant is used to identify the
resonances and analyze stability problems. PSCAD/EMTDC time-domain simulations are also shown to validate the
Sainz, L.; Monjo, L.; Mesas, J. J.; Pedra, J.; Cheah-Mane, M. IEEE International Conference Electric Power Quality and Supply Reliability p. 133-138 DOI: 10.1109/PQ.2016.7724102 Data de presentació: 2016-08-30 Presentació treball a congrés
Traction system stability can be affected by the interaction between the traction load and resonances in the railway traction grid. This paper presents an electrical resonance instability study applied to traction systems. The influence of traction section length and converter time delay on traction system stability is analyzed with examples.
An impedance-based representation of the traction system is used to identify the resonances and analyze stability problems. PSCAD/EMTDC time-domain simulations are also shown to validate the stability study.
Traction system stability can be affected by the interaction between the traction load and resonances in
the railway traction grid. This paper presents an electrical resonance instability study applied to traction systems. The
influence of traction section length and converter time delay on traction system stability is analyzed with examples.
An impedance-based representation of the traction system is used to identify the resonances and analyze stability
problems. PSCAD/EMTDC time-domain simulations are also shown to validate the stability study.
Cheah-Mane, M.; Sainz, L.; Liang, J.; Jenkins, N. IEEE Power & Energy Society General Meeting p. 7741889-1-7741889-5 DOI: 10.1109/PESGM.2016.7741889 Data de presentació: 2016-07 Presentació treball a congrés
The stability of an HVDC-connected Offshore Wind Power Plant (OWPP) is compromised if there are interactions between the power converters and the resonances of the offshore grid. This paper analyses the voltage stability of the offshore HVDC converter due to low frequency electrical resonances. An impedance-based representation is used to identify the resonances and study the stability. The effect of the offshore converter control and OWPP parameters is analysed through the root locus of the system. The positive-net-damping criterion is used to determine the stability conditions due to electrical resonances. Also, time-domain simulations in PSCAD/EMTDC are presented to verify the stability conditions.
This chapter first provides a general overview of different offshore wind power plant (OWPP) designs considering the use of both high-voltage alternating current (HVAC) and high-voltage direct current (HVDC) transmission links to deliver the generated power. It then focuses on the conventional AC wind power plants, by introducing some possible wind power plant topologies and briefly describing the required technologies that encompasses the collection grid. The chapter also deals with the description of the electrical design methodology performed in the conventional offshore wind power plants. The methodology focuses on explaining in detail the cable selection process and how the technical assessment of an OWPP is performed, considering only the collection grid area. Finally, the chapter presents a short presentation of future OWPPs based on DC technologies, as well as other proposals for AC wind power plants connected to the onshore grid through an HVDC transmission links
Eduardo Prieto-Araujo; Olivella, P.; Cheah-Mane, M.; R. Villafafila-Robles; Gomis-Bellmunt, O. Renewable and sustainable energy reviews Vol. 50, p. 325-345 DOI: 10.1016/j.rser.2015.04.101 Data de publicació: 2015-10-01 Article en revista
This paper reviews the renewable energy systems emulators proposals for microgrid laboratory testing platforms. Four emulation conceptual levels are identified based on the literature analysis performed. Each of these levels is explained through a microgrid example, detailing its features and possibilities. Finally, an experimental microgrid, built based on emulators, is presented to exemplify the system performance. (C) 2015 Elsevier Ltd. All rights reserved.
Cheah-Mane, M.; Adeuyi, O.D.; Liang, J.; Jenkins, N. European Conference on Power Electronics and Applications p. 1-9 DOI: 10.1109/EPE.2015.7311714 Data de presentació: 2015-09 Presentació treball a congrés
This paper demonstrates a scaling method for an experimental test rig to represent the steady state operation of different HVDC transmission systems. The method is based on a parameter conversion between the experimental rig and the HVDC system under study. A virtual resistance is added to the DC cable resistance of the experimental test rig in order to achieve the same steady state operation as the real HVDC system. A droop control correction in the VSCs was used to implement the virtual resistance.
A Hardware-in-the-loop set-up formed by laboratory-scale power electronic devices and a Real Time Simulator was used to test this scaling method. Three case studies modelled in PSCAD/EMTDC were used to verify that the results show good agreement.
Adeuyi, O.D.; Cheah-Mane, M.; Liang, J.; Jenkins, N.; Wu, Y.; Li, C.; Wu, X. IEEE Power & Energy Society General Meeting p. 1-5 DOI: 10.1109/PESGM.2015.7286086 Data de presentació: 2015-07 Presentació treball a congrés
Multiterminal HVDC (MTDC) schemes are intended to transfer power from offshore wind farms to land and interconnect the grids of adjacent countries, through Voltage Source Converters (VSC). The modular multilevel converter (MMC) topology of VSCs is a more recent development which has low harmonics, reduced losses and occupies less space.
This paper analyses the frequency support characteristics of MMC-based multiterminal HVDC schemes, using the energy transferred from the capacitance of the MMCs, wind turbine rotating mass and other AC systems. A generic formulation of an equivalent synthetic inertia constant is proposed to determine the energy transferred from the MTDC scheme. A 3-terminal MMCHVDC
system is utilised to study the influence of cell capacitance of the submodules and the proposed synthetic inertia constant of the MTDC system on the frequency support capability of the
MMC capacitors. The time response and energy capability of the different energy sources of the MTDC system are compared
Adeuyi, O.D.; Cheah-Mane, M.; Liang, J.; Livermore, L.; Mu, Q. CSEE Journal of Power and Energy Systems Vol. 1, num. 1, p. 86-94 DOI: 10.17775/CSEEJPES.2015.00011 Data de publicació: 2015-03 Article en revista
This paper is concerned with power reduction control which is used to avoid DC over-voltage for multiterminal HVDC transmission of offshore wind power. Voltages and frequencies of offshore AC wind farm networks are used for transmitting control signals for the power reduction control.
These methods do not require fast communication. Power reduction sharing among the offshore wind farms using the different control signals is analysed. The control systems are also compared against the DC chopper method to prevent a DC overvoltage.
Simulation and experiments are carried out to evaluate the control systems.
Offshore wind power generation is expected to increase in the following years, but there are still some economic and technical challenges to overcome. Because of the difficult access to the offshore facilities, the reduction of maintenance is an essential point. The use of Permanent Magnet Synchronous Generators (PMSG) is considered a suitable option in this wind farm topology to satisfy this purpose. On the other hand, these generators along with full-rated Voltage Source Converters (VSC) are expected to provide ancillary services for the onshore AC grid. Particularly, Inertial Frequency Response is an interesting option considering the stored kinetic energy in the rotor of the wind turbines. Therefore, in this paper a description of the model and control system of a PMSG using full-rated VSC are reviewed and their Inertial Frequency Response capability is presented through two methodologies. At the end, simulation and experimental tests results are shown in order to compare these two different options and analyse their viability.
Cheah-Mane, M.; Eduardo Prieto-Araujo; R. Villafafila-Robles; Sudria, A.; Gomis-Bellmunt, O. Congreso Iberoamericano sobre Microrredes con Generación Distribuida de Renovables p. 1-10 Data de presentació: 2013-09-23 Presentació treball a congrés
This paper presents the use of emulator devices to represent different elements of a microgrid system. In this sense, the emulation concept and its advantages are explained. Each emulator is implemented by means of power converters which receive a determined power reference according to the energy resource that it means. Therefore, connecting a determined number of these emulators into the same system it is possible to create several microgrid configurations, which will be capable of performing different test and obtaining the same result that in a real system. In the end, as an example of the advantages that the emulators are able to offer, an experimental platform is presented.
Prieto-Araujo, E.; Cheah-Mane, M.; R. Villafafila-Robles; Gomis-Bellmunt, O.; Junyent-Ferré, A. European Conference on Power Electronics and Applications DOI: 10.1109/EPE.2013.6634674 Data de presentació: 2013-09-04 Presentació treball a congrés
Junyent, A.; Cheah-Mane, M.; Eduardo Prieto-Araujo; Gomis-Bellmunt, O. European Conference on Power Electronics and Applications p. 1-7 DOI: 10.1109/EPE.2013.6634688 Data de presentació: 2013-09 Presentació treball a congrés