Journal articles: 'Hvdc; mtdc'

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Rios, Mario A., and Fredy A. Acero. "Planning multi-terminal direct current grids based graphs theory." International Journal of Electrical and Computer Engineering (IJECE) 11, no. 1 (February 1, 2021): 37. http://dx.doi.org/10.11591/ijece.v11i1.pp37-46.

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Transmission expansion planning in AC power systems is well known and employs a variety of optimization techniques and methodologies that have been used in recent years. By contrast, the planning of HVDC systems is a new matter for the interconnection of large power systems, and the interconnection of renewable sources in power systems. Although the HVDC systems has evolved, the first implementations were made considering only the needs of transmission of large quantities of power to be connected to the bulk AC power system. However, for the future development of HVDC systems, meshed or not, each AC system must be flexible to allow the expansion of these for future conditions. Hence, a first step for planning HVDC grids is the planning and development of multi-terminal direct current (MTDC) systems which will be later transformed in a meshed system. This paper presented a methodology that use graph theory for planning MTDC grids and for the selection of connection buses of the MTDC to an existing HVAC transmission system. The proposed methodology was applied to the Colombian case, where the obtained results permit to migrate the system from a single HVDC line to a MTDC grid.

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Oni, Oluwafemi Emmanuel, Andrew G. Swanson, and Rudiren Pillay Carpanen. "Impact of LCC–HVDC multiterminal on generator rotor angle stability." International Journal of Electrical and Computer Engineering (IJECE) 10, no. 1 (February 1, 2020): 22. http://dx.doi.org/10.11591/ijece.v10i1.pp22-34.

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<span>Multiterminal High Voltage Direct Current (HVDC) transmission utilizing Line Commutated Converter (LCC-HVDC) technology is on the increase in interconnecting a remote generating station to any urban centre via long distance DC lines. This Multiterminal-HVDC (MTDC) system offers a reduced right of way benefits, reduction in transmission losses, as well as robust power controllability with enhanced stability margin. However, utilizing the MTDC system in an AC network bring about a new area of associated fault analysis as well as the effect on the entire AC system during a transient fault condition. This paper analyses the fault current contribution of an MTDC system during transient fault to the rotor angle of a synchronous generator. The results show a high rotor angle swing during a transient fault and the effectiveness of fast power system stabilizer connected to the generator automatic voltage regulator in damping the system oscillations. The MTDC link improved the system performance by providing an alternative path of power transfer and quick system recovery during transient fault thus increasing the rate at which the system oscillations were damped out. This shows great improvement compared to when power was being transmitted via AC lines.</span>

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Jiahui, Wu, Wang Haiyun, Wang Weiqing, and Zhang Qiang. "Three-terminal Hybrid HVDC Transmissions Control Strategies for Bundled Wind-thermal Power Plants." Open Electrical & Electronic Engineering Journal 10, no. 1 (December 30, 2016): 156–65. http://dx.doi.org/10.2174/1874129001610010156.

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This paper evaluates application feasibility of a Hybrid Multi-terminal HVDC system and wind-thermal-bundled plants simulated in DIgSLIENT PowerFactory environment. The proposed hybrid MTDC system consists of two line-communicated converters (LCC), which are connected to both wind farms and thermal power plants, and one voltage source converter (VSC) at the grid side. Control strategies for each converter are designed to handle this system under different disturbance conditions. Simulation results show that the wind power fluctuation can be compensated by the thermal-generated power. Results demonstrate the effectiveness of the proposed control strategies of the hybrid MTDC system compared to a conventional MTDC system. The proposed scheme combines advantages of both LCC and VSC HVDC systems and provides a new way to transmit wind power over long distances to the main grid.

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Xu, Han Ping, Xia Chen, Wang Xiang, and Jin Yu Wen. "Control and Operational Characteristics Research on Multi-Terminal HVDC for Wind Power Transmission." Advanced Materials Research 1092-1093 (March 2015): 248–53. http://dx.doi.org/10.4028/www.scientific.net/amr.1092-1093.248.

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This paper proposed the line-commutated converter based multi-terminal HVDC (LCC-MTDC) combining with the static synchronous compensator (STATCOM) for doubly-fed induction generator (DFIG) based wind farms integration with bulk wind power transmission over long distance. This paper is aimed at the control strategy design and the operational characteristics research of LCC-MTDC for wind power transmission. Then, the control methodologies of the complex integration system are addressed from two aspects: the MTDC and the wind farm. The coordination control strategy is developed to ensure the stable operation of the MTDC system and the wind farm controller is designed to capture the maximum wind power and ensure all the wind power transferred into the MTDC. Simulation results in PSCAD/EMTDC show that LCC-MTDC could achieve desirable operational performances with the control strategy proposed.

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Hwang, Sungchul, Sungyoon Song, Gilsoo Jang, and Minhan Yoon. "An Operation Strategy of the Hybrid Multi-Terminal HVDC for Contingency." Energies 12, no. 11 (May 28, 2019): 2042. http://dx.doi.org/10.3390/en12112042.

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The application of the direct current (DC) transmission is increasing through the interconnection between grids or the renewable energy resource integration. Various types of DC transmission topology are researched, and the hybrid multi-terminal high voltage DC (HVDC), called the “MTDC”, is one of the research subjects. The hybrid multi-terminal HVDC is the MTDC system that is composed with the Line Commutated Converter (LCC) and Voltage Source Converter (VSC). Most hybrid MTDC research has been focused on the connection of the renewable energy generation sources, especially offshore wind farms. However, the DC grid built with a hybrid MTDC was recently proposed due to the development of the converter technology. Therefore, the DC grid is expected to be able to substitute some parts of the transmission grid instead of the alternating current (AC) system, and the operation strategies of the DC grid are still being researched. The DC grid has the advantage of being able to control the power flow, which can even improve the stability of the connected AC system. The dynamic model is required to analyze the improvement of the AC system by the operation strategy of the hybrid MTDC, however, there is no generic model for the system. In this paper, an operation strategy of the hybrid MTDC is proposed to improve the stability of the AC power system by increasing the utilization of parallel AC transmission lines under the contingency condition. Furthermore, studies on the modeling method for a hybrid MTDC analysis were performed. The proposed modeling method and operation strategy were verified in simulations for which a modified IEEE 39 bus test system was used. The improvement of transient stability by the proposed hybrid MTDC system was shown in the simulation results.

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Qin, Boyu, Wansong Liu, Ruowei Zhang, Jialing Liu, and Hengyi Li. "Review on Short-circuit Current Analysis and Suppression Techniques for MMC-HVDC Transmission Systems." Applied Sciences 10, no. 19 (September 27, 2020): 6769. http://dx.doi.org/10.3390/app10196769.

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The modular multilevel converter (MMC) has been widely adopted in high voltage direct current (HVDC) transmission systems due to its significant advantages. MMC-HVDC is developing towards multi-terminal direct current (MTDC) power grid for reliability enhancement. However, there exist a huge amplitude and a steep rise in fault current due to the low impedances of DC lines and MMCs, which threaten the security and reliability of the DC power grids. It is necessary to restrain the DC short circuit current in order to ensure the safe and stable operation of DC power grids. This paper gives a comprehensive review and evaluation of the proposed DC short-circuit current analysis and suppression techniques used in MMC-based MTDC power girds, in terms of MMC modeling, short circuit calculation, and suppression method. In addition, future trends of countermeasures to short circuit current in MMC-based MTDC power grids are also discussed.

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Lee, Chun-Kwon, Gyu-Sub Lee, and Seung-Jin Chang. "Solution to Fault of Multi-Terminal DC Transmission Systems Based on High Temperature Superconducting DC Cables." Energies 14, no. 5 (February 26, 2021): 1292. http://dx.doi.org/10.3390/en14051292.

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In this paper, we developed the small-signal state-space (SS) model of hybrid multi-terminal high-voltage direct-current (HVDC) systems and fault localization method in a failure situation. The multi-terminal HVDC (MTDC) system is composed of two wind farm side voltage-source converters (VSCs) and two grid side line-commutated converters (LCCs). To utilize relative advantages of the conventional line-commutated converter (LCC) and the voltage source converter (VSC) technologies, hybrid multi-terminal high-voltage direct-current (MTDC) technologies have been highlighted in recent years. For the models, grid side LCCs adopt distinct two control methods: master–slave control mode and voltage droop control mode. By utilizing root-locus analysis of the SS models for the hybrid MTDC system, we compare stability and responses of the target system according to control method. Furthermore, the proposed SS models are utilized in time-domain simulation to illustrate difference between master–slave control method and voltage droop control method. However, basic modeling method for hybrid MTDC system considering superconducting DC cables has not been proposed. In addition, when a failure occurs in MTDC system, conventional fault localization method cannot detect the fault location because the MTDC system is a complex form including a branch point. For coping with a failure situation, we propose a fault localization method for MTDC system including branch points. We model the MTDC system based on the actual experimental results and simulate a variety of failure scenarios. We propose the fault localization topology on a branch cable system using reflectometry method. Through the simulation results, we verify the performance of fault localization. In conclusion, guidelines to select control method in implementing hybrid MTDC systems for integrating offshore wind farms and to cope with failure method are provided in this paper.

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Ge, Le, Limin Lu, Xiaodong Yuan, and Yongzhou Yu. "Optimal Operation Strategy of Flexible Interconnected Distribution Network Based on SES-VSC-MTDC." Mathematical Problems in Engineering 2020 (August 24, 2020): 1–14. http://dx.doi.org/10.1155/2020/9732378.

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The increasing integration of renewable energy is challenging the secure operation of the power system. System flexibility or the capability to address the significant power fluctuations from renewable energy is becoming more and more relevant. Self-energy storage-based multiterminal back-to-back VSC-HVDC (SES-VSC-MTDC) technology is first proposed, and it can realize the power regulation on both temporal and spatial dimensions, which helps improve the power supply reliability and the capacity to accommodate renewable energy of the interconnected distribution networks. Then, to address the coordination control problem of the energy storage and back-to-back VSC-HVDC, a comprehensive control strategy of SES-VSC-MTDC is proposed based on the optimal power flow preprocessing and state of charge interval division. Then, the power regulation model and the energy-power regulation timing model of SES-VSC-MTDC are established for different control strategies. Then, we use the primal-dual interior-point method to solve the developed optimal operation model of flexible interconnected distribution network. Finally, a 33-bus system with four interconnected feeders is used to test the effectiveness of the SES-VSC-MTDC technology and its operation control strategy.

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Wang, Kai, Hai Shun Sun, Yu Hua, Yuan Liu, Wei Xing Lin, and Cheng Hao Li. "Research on DC Voltage Control Strategies for Typical Four-Terminal HVDC System." Applied Mechanics and Materials 521 (February 2014): 222–28. http://dx.doi.org/10.4028/www.scientific.net/amm.521.222.

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The continuous development of alternative energy has put forward higher requirement for electricity transmission. To cope with its fluctuation characteristics, high voltage direct current (HVDC) technology has received more attention. Voltage Source Converter (VSC) based Multi-Terminal High Voltage Direct Current (MTDC) represents the future trend of HVDC technology. This paper mainly focuses on the control strategies of a four-terminal VSC based MTDC power transmission system. The operation characteristic of the system was studied, and the proposed two control strategies, master-slave control strategy and DC voltage droop control strategy, were verified through simulations. The latter control strategy was proved to be performing well under various conditions, including converter station disconnection and faults at AC side of the converter.

10

Li, Zhou, Yan He, Ting-Quan Zhang, and Xiao-Ping Zhang. "Universal Power Flow Algorithm for Bipolar Multi-Terminal VSC-HVDC." Energies 13, no. 5 (February 26, 2020): 1053. http://dx.doi.org/10.3390/en13051053.

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An effective and accurate power flow algorithm provides control references for active power dispatch and initial steady state operating points, used for stability analysis, short-circuit calculations, and electromagnetic transient simulations, which is not only a fundamental precondition to analyze the system operating conditions, but also the basis to improve the accuracy of power flow and DC voltage control of the multi-terminal voltage source converter-based high voltage direct current (VSC-HVDC). This paper proposes a nodal voltage-based universal steady-state power flow algorithm for the newly-developed bipolar multi-terminal VSC-HVDC (VSC-MTDC). Firstly, as the positive-pole and negative-pole DC network of the bipolar VSC-MTDC can be operated individually, a bipolar power flow alternating iterative method is proposed here to obtain the positive/negative-pole DC network power flow. Secondly, a series of nodal equivalent methods involving various control strategies are proposed for the universal power flow algorithm. Then the detailed calculation procedure and a general MATLAB(TM) program for the universal power flow algorithm is presented. A typical 4-terminal bipolar VSC-MTDC system was built in the PSCAD/EMTDC to verify the validity of the proposed algorithm, and the results are discussed here. Moreover, the calculation results of more complex bipolar VSC-MTDC systems under different operating conditions, employing the proposed universal power flow algorithm, are presented to illustrate its universality and efficiency.

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Li, Congshan, Pu Zhong, Ping He, Yan Liu, Yan Fang, and Tingyu Sheng. "Comparison of Two Control Strategies for VSC-MTDC with Wind Farm." Recent Advances in Electrical & Electronic Engineering (Formerly Recent Patents on Electrical & Electronic Engineering) 14, no. 7 (December 10, 2021): 744–54. http://dx.doi.org/10.2174/2352096514666210930151744.

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: Two VSC-MTDC control strategies with different combinations of controllers are proposed to eliminate transient fluctuations in the DC voltage stability, resulting from a power imbalance in a VSC-MTDC connected to wind farms. First, an analysis is performed of a topological model of a VSC converter station and a VSC-MTDC, as well as of a mathematical model of a wind turbine. Then, the principles and characteristics of DC voltage slope control, constant active power control, and inner loop current control used in the VSC-MTDC are introduced. Finally, the PSCAD/EMTDC platform is used to establish an electromagnetic transient model of a wind farm connected to a parallel three-terminal VSC-HVDC. An analysis is performed for three cases of single- phase grounding faults on the rectifier and inverter sides of a converter station and of the withdrawal of the converter station on the rectifier side. Next, the fault response characteristics of VSCMTDC are compared and analyzed. The simulation results verify the effectiveness of the two control strategies, both of which enable the system to maintain DC voltage stability and active power balance in the event of a fault. Background: The use of a VSC-MTDC to connect wind power to the grid has attracted considerable attention in recent years. A suitable VSC-MTDC control method can enable the stable operation of a power grid. Objective: The study aims to eliminate transient fluctuations in the DC voltage stability resulting from a power imbalance in a VSC-MTDC connected to a wind farm. Methods: First, the topological structure and a model of a three-terminal VSC-HVDC system connected to wind farms are studied. Second, an analysis is performed of the outer loop DC voltage slope control, constant active power control and inner loop current control of the converter station of a VSC-MTDC. Two different control strategies are proposed for the parallel three-terminal VSCHVDC system: the first is DC voltage slope control for the rectifier station and constant active power control for the inverter station, and the second is DC voltage slope control for the inverter station and constant active power for the rectifier station. Finally, a parallel three-terminal VSC-HVDC model is built based on the PSCAD/EMTDC platform and used to verify the accuracy and effectiveness of the proposed control strategy. Results: The results of simulation analysis of the faults on the rectifier and inverter sides of the system show that both strategies can restore the system to the stable operation. The effectiveness of the proposed control strategy is thus verified. Conclusion: The control strategy proposed in this paper provides a technical reference for designing a VSC-MTDC system for wind farms.

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Samaranayake, Lilantha, Carlos E. Ugalde-Loo, Oluwole D. Adeuyi, John Licari, and Janaka B. Ekanayake. "Multi-Terminal DC Grid with Wind Power Injection." Wind 2, no. 1 (January 7, 2022): 17–36. http://dx.doi.org/10.3390/wind2010002.

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With the development of offshore wind generation, the interest in cross-country connections is also increasing, which requires models to study their complex static and dynamic behaviors. This paper presents the mathematical modeling of an offshore wind farm integrated into a cross-country HVDC network forming a multi-terminal high-voltage DC (MTDC) network. The voltage source converter models were added with the control of active power, reactive power, frequency, and DC link voltages at appropriate nodes in the MTDC, resembling a typical cross-country multi-terminal type of HVDC scenario. The mathematical model for the network together with the controllers were simulated in MATLABTM and experimentally verified using a real-time digital simulator hardware setup. The resulting static and dynamic responses from the hardware setup agreed well with those from simulations of the developed models.

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Oni, Oluwafemi, Andrew Swanson, Rudiren Pillay Carpanen, and Anuoluwapo Aluko. "Implementation of a Multiterminal Line Commutated Converter HVDC Scheme with Auxiliary Controller on South Africa’s 765 kV Corridor." Energies 15, no. 12 (June 14, 2022): 4356. http://dx.doi.org/10.3390/en15124356.

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The deployment of a 765-kV transmission line on Eskom’s South African Grid marks the beginning of a new era in power industries. The integration of renewable energies by independent power producers (IPPs) leads to an infrastructural change in the stability performance of the entire grid. These developments are expected to bring about a multiterminal direct current (MTDC) system for practical implementation on this grid. Therefore, this study focuses on the dynamic response of the South African transmission grid during a system disturbance. In the carrying out of this study, the South African grid was modeled on PSCAD, and its performance was evaluated. The impact of the MTDC link on the grid’s interarea oscillation was also investigated. An additional current order controller for the MTDC link was developed, and its impact on the MTDC power transfer was analyzed. The results show a better system performance and reduced interarea power swings with the inclusion of the MTDC link.

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Bhutta, Muhammad Shoaib, Tang Xuebang, Muhammad Faheem, Fahad M. Almasoudi, Khaled Saleem S. Alatawi, and Huali Guo. "Neuro-Fuzzy Based High-Voltage DC Model to Optimize Frequency Stability of an Offshore Wind Farm." Processes 11, no. 7 (July 9, 2023): 2049. http://dx.doi.org/10.3390/pr11072049.

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Lack of synchronization between high voltage DC systems linking offshore wind farms and the onshore grid is a natural consequence owing to the stochastic nature of wind energy. The poor synchronization results in increased system disturbances, grid contingencies, power loss, and frequency instability. Emphasizing frequency stability analysis, this research investigates a dynamic coordination control technique for a Double Fed Induction Generator (DFIG) consisting of OWFs integrated with a hybrid multi-terminal HVDC (MTDC) system. Line commutated converters (LCC) and voltage source converters (VSC) are used in the suggested control method in order to ensure frequency stability. The adaptive neuro-fuzzy inference approach is used to accurately predict wind speed in order to further improve frequency stability. The proposed HVDC system can integrate multiple distributed OWFs with the onshore grid system, and the control strategy is designed based on this concept. In order to ensure the transient stability of the HVDC system, the DFIG-based OWF is regulated by a rotor side controller (RSC) and a grid side controller (GSC) at the grid side using a STATCOM. The devised HVDC (MTDC) is simulated in MATLAB/SIMULINK, and the performance is evaluated in terms of different parameters, such as frequency, wind power, rotor and stator side current, torque, speed, and power. Experimental results are compared to a conventional optimal power flow (OPF) model to validate the performance.

15

Renedo, Javier, Aurelio García-Cerrada, Luis Rouco, and Lukas Sigrist. "Coordinated Control in VSC-HVDC Multi-Terminal Systems to Improve Transient Stability: The Impact of Communication Latency." Energies 12, no. 19 (September 24, 2019): 3638. http://dx.doi.org/10.3390/en12193638.

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Power transmission is the main purpose of high voltage direct current systems based on voltage source converters (VSC-HVDC). Nevertheless, this type of system can also help to improve transient stability by implementing suitable supplementary controllers. Previous work proposed active- (P) and reactive-power (Q) control strategies in VSC-HVDC multi-terminal systems (VSC-MTDC, for short) to improve transient stability, producing significant improvements. In those strategies, each VSC station of the MTDC system compares its frequency measurement with the average of the frequencies measured by all converter stations of the MTDC system (weighted-average frequency, WAF) in order to modulate its own P and Q injections. Hence, a communication system is required. This paper presents a detailed analysis of the impact of communication latency on the performance of those control strategies. The communication delays have been modelled using a Padé’s approximation and their impact on the performance of the control strategies have been assessed by means of time-domain simulation in PSS/E. The effect of the control strategies on transient stability has been quantified with the critical clearing time (CCT) of a set of faults. Results show that the control strategies analysed present good results for realistic values of communication delays.

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Shinoda, Kosei, Xavier Guillaud, Seddik Bacha, Abdelkrim Benchaib, and Bruno Francois. "Modelling of a VSC-based multi-terminal HVDC network for dynamic stability analysis." COMPEL - The international journal for computation and mathematics in electrical and electronic engineering 36, no. 1 (January 3, 2017): 240–57. http://dx.doi.org/10.1108/compel-01-2016-0019.

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Purpose Self-commuted voltage source converter (VSC) can significantly extend the flexibility and operability of an HVDC system and be used to implement the concept of multi-terminal HVDC (MTDC) grid. To take full advantage of MTDC systems, its overall behaviour must be characterized in quasi static and dynamic states. Based on the numerous literatures, a dedicated two-level VSC model and its local controllers and DC grid voltage regulators are developed for this purpose. Furthermore, the requirement of the system to guarantee all the physical constrains must be well assessed and concrete demonstrations must be provided by numerical simulations. Design/methodology/approach First, a two-level VSC model and its local controllers and DC grid voltage regulators are developed. Then, DC cable models are investigated and their characteristics are assessed in the frequency domain. Those developed models are combined to form a three-terminal HVDC grid system on Matlab/Simulink platform. To analyze the stability of this electrical system, the dynamics of the system against variations of power dispatch are observed. Findings To analyze the stability of this electrical system, the dynamics of the system against variations of power dispatch are observed. The differences in the DC grid voltage dynamics and the power flow of the converter stations coming from the embedded primary controls are analysed, and the technical requirements for both cases are assessed. Originality/value In this paper, the dynamic stability of an MTDC system has been analysed and assessed through an adequate simulation model, including its control scheme and the cable models. The interest of the improved PI model for cables is highlighted.

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Xu, Yan, Di Feng Shi, and Shao Bo Yan. "Boundary Protection Strategy for the VSC-MTDC under DC Faults." Applied Mechanics and Materials 448-453 (October 2013): 2030–35. http://dx.doi.org/10.4028/www.scientific.net/amm.448-453.2030.

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Multi-terminal HVDC transmission system based on voltage source converter is a promising topology for the integration of the renewable energy sources. The fault characteristics of VSC-MTDC system under DC side faults was analyzed in this paper, as well as the particular requirements for the protection strategy. On the basis of the work metioned above, a four-terminal DC connected transmission system model was built in PSCAD/EMTDC. The boundary protection algorithm was proposed and the wavelet analysis was introduced. The protection scheme for VSC-MTDC transmission lines is based on the attenuation characteristics of line boundary for high frequency transient signals, which constitutes the operation criteria of the boundary protection. The protection scheme puts forward an effective method for the protection selectivity of the VSC-MTDC transmission system.

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Rosero, Ricardo. "Una Revisión Acerca de Tecnologías y Modelación de Enlaces HVDC para Estudios Eléctricos." INNOVATION & DEVELOPMENT IN ENGINEERING AND APPLIED SCIENCES 2, no. 1 (June 4, 2020): 19. http://dx.doi.org/10.53358/ideas.v2i1.363.

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Los sistemas Corriente Continua de Alta Tensión (HVDC), actualmente son muy utilizados a nivel mundial debido a sus ventajas frente a sistemas de transmisión tradicionales. Se realizo una investigación sobre la modelación y simulación estático-dinámica de los sistemas HVDC. Los modelos encontrados se basan en conversores tipo fuente de corriente (LCC), conversores tipo fuente de voltaje (VSC), conversores modulares multinivel (MMC), sistemas multiterminal DC (MTDC) y de alimentación múltiple (multi-infeed HVDC). Las principales simulaciones, son transitorios electromagnéticos (EMT), estado cuasi estacionario (QSS), simulaciones híbridas de fasores dinámicos y transitorios electromecánicos, simulaciones híbridas de transitorios electromagnéticos (EMT) y estabilidad transitoria (TS), fasores dinámicos basado en interfaz (DPIM) para simulaciones híbridas EMT y TS, flujos de potencia HVDC y simulación digital de tiempo real (RTDS), determinando la complejidad de los sistemas HVDC en el modelado, simulación y controles con el objetivo de que enlaces mixtos AC/DC sean factibles técnicamente.

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Zhao, Kun, Qiang Li, Xiao Yang, Li Li, Yu Zou, Yin Zhang, and Cheng Long Dou. "A Power Flow Method for VSC-Multi-Terminal Hybrid System Based on Asynchronous Iteration Algorithm." Applied Mechanics and Materials 672-674 (October 2014): 863–69. http://dx.doi.org/10.4028/www.scientific.net/amm.672-674.863.

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With the continuous development of HVDC technology, the increase in the number of ports in the MTDC system and the increasing complexity of network topology, the deficiency of traditional flow calculation method is becoming clear. In this paper, a power flow calculation method that contains distribution of VSC-MTDC mixed system which based on asynchronous iterative method is put forward. On the basis of the current model converter, by dividing the hybrid system and coordinating calculation of boundary variables, this method achieves the global convergence of the whole system. The shortcomings that numerous converter stations in VSC-MTDC power flow method, slow operations and poor convergence in communication network with large number of nodes, are overcome in this method. Moreover, more control modes in the operation of the converter station are considered. Finally, through the example, the correctness and effectiveness of this method are verified.

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Du, Chuan, Qingzhi Zhang, and Shuai Cao. "A Smart Fault-Tackling Strategy Based on PFTE for AC Three-Phase-to-Ground Faults in the Multi-Terminal HVDC Wind Power Integration System: Further Foundings." Energies 15, no. 3 (January 21, 2022): 768. http://dx.doi.org/10.3390/en15030768.

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This paper describes a smart fault tackling strategy based on power flow transfer entropy (PFTE) for AC three-phase-to-ground (TPG) faults in the multi-terminal HVDC (MTDC) wind power integration system. The fault characteristics and transient energy transfer of different positions and properties are analyzed. Then, a double integral discrimination method based on PFTE is proposed to further distinguish the fault property. Considering the power flow balance, an adaptive coordination strategy of wind farms and energy dissipation resistors is proposed to deal with different AC faults. Finally, a smart fault-tackling strategy based on PFTE for AC three-phase-to-ground (TPG) faults in the MTDC wind power integration system is proposed. Under the proposed smart fault-tackling strategy, the MTDC wind power integration system achieves uninterrupted operation during any AC TPG fault at the receiving end. The experiment results confirm the applicability of the proposed fault-tackling strategy.

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Xi, Yang, Ai Qian, Huang Jiantao, and An Yiran. "Application of Multipoint DC Voltage Control in VSC-MTDC System." Journal of Electrical and Computer Engineering 2013 (2013): 1–7. http://dx.doi.org/10.1155/2013/257387.

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The voltage-source-converter- (VSC-) based multiterminal VSC-HVDC power transmission system (VSC-MTDC) is an ideal approach to connect wind farm with power grid. Analyzing the characteristics of doubly fed induction generators as well as the basic principle and the control strategy of VSC-MTDC, a multiterminal DC voltage control strategy suitable for wind farm connected with VSC-MTDC is proposed. By use of PSCAD/EMTDC, the proposed control strategy is simulated, and simulation results show that using the proposed control strategy the conversion between constant power control mode and constant DC voltage control mode can be automatically implemented; thus the DC voltage stability control and reliable power output of wind farm can be ensured after the fault-caused outage of converter station controlled by constant DC voltage and under other faults. The simulation result shows that the model can fulfill multiterminal power transmission and fast response control.

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Abedin, Tarek, M. Shahadat Hossain Lipu, Mahammad A. Hannan, Pin Jern Ker, Safwan A. Rahman, Chong Tak Yaw, Sieh K. Tiong, and Kashem M. Muttaqi. "Dynamic Modeling of HVDC for Power System Stability Assessment: A Review, Issues, and Recommendations." Energies 14, no. 16 (August 8, 2021): 4829. http://dx.doi.org/10.3390/en14164829.

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High-voltage direct current (HVDC) has received considerable attention due to several advantageous features such as minimum transmission losses, enhanced stability, and control operation. An appropriate model of HVDC is necessary to assess the operating conditions as well as to analyze the transient and steady-state stabilities integrated with the AC networks. Nevertheless, the construction of an HVDC model is challenging due to the high computational cost, which needs huge ranges of modeling experience. Therefore, advanced dynamic modeling of HVDC is necessary to improve stability with minimum power loss. This paper presents a comprehensive review of the various dynamic modeling of the HVDC transmission system. In line with this matter, an in-depth investigation of various HVDC mathematical models is carried out including average-value modeling (AVM), voltage source converter (VSC), and line-commutated converter (LCC). Moreover, numerous stability assessment models of HVDC are outlined with regard to stability improvement models, current-source system stability, HVDC link stability, and steady-state rotor angle stability. In addition, the various control schemes of LCC-HVDC systems and modular multilevel converter- multi-terminal direct current (MMC-MTDC) are highlighted. This paper also identifies the key issues, the problems of the existing HVDC models as well as providing some selective suggestions for future improvement. All the highlighted insights in this review will hopefully lead to increased efforts toward the enhancement of the modeling for the HVDC system.

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Wang, Zhen, Jialiang Wu, Ruixu Liu, and Yu Shan. "A P-Q Coordination Control Strategy of VSC-HVDC and BESS for LVRT Recovery Performance Enhancement." Electronics 13, no. 4 (February 12, 2024): 741. http://dx.doi.org/10.3390/electronics13040741.

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Voltage source converter (VSC)-based multi-terminal direct current (MTDC) transmission technology has been a research focus, and the low-voltage ride-through (LVRT) and recovery in receiving-end systems is one of the major problems to consider. A coordinated control strategy for a VSC-MTDC system is proposed to improve the frequency and voltage dynamics in the receiving-end system during the LVRT and recovery processes. A battery energy storage system (BESS) plays a significant role in providing frequency and voltage support with its flexible power control capability. During the LVRT process, the BESS can provide reactive current injection and active current absorption to improve system stability in the AC side, and during the recovery process, an adaptive current limitation method is proposed for the BESS converter to dynamically adjust the active and reactive power outputs according to the frequency and voltage deviation severity. Meanwhile, the coordination of the sending-end systems and DC chopper can reduce the power output to avoid DC overvoltage during LVRT, and it can also provide frequency support to the receiving-end system with the DC voltage transmitting frequency information during the recovery process. A simulation was carried out on the MATLAB/Simulink platform, and a three-terminal VSC-MTDC system was used to validate the effectiveness of the proposed strategy.

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Xing, Chao, Mingqun Liu, Junzhen Peng, Yuhong Wang, Chengbo Shang, Zongsheng Zheng, Jianquan Liao, and Shilin Gao. "Frequency Stability Control Strategy for Voltage Source Converter-Based Multi-Terminal DC Transmission System." Energies 17, no. 5 (March 2, 2024): 1195. http://dx.doi.org/10.3390/en17051195.

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The voltage source converter-based multi-terminal DC transmission (VSC-MTDC) system can use additional frequency control to respond to the frequency change of faulty AC system. However, the control coefficient of traditional additional frequency control is mostly fixed, and the control flexibility is insufficient, so it cannot be adjusted adaptively according to the frequency change of the system. Therefore, a frequency control strategy of the VSC-MTDC system based on fuzzy logic control is proposed. Based on the DC voltage slope controller, this strategy introduces an additional frequency controller based on fuzzy logic control, takes the frequency deviation and frequency change rate as the additional controller input, and dynamically adjusts the control quantity through the fuzzy logic control link to realize the adaptive adjustment of the VSC-MTDC system to the AC system’s frequency. Finally, a three-terminal flexible HVDC system is built on the PSCAD/EMTDC simulation platform for simulation verification. The results show that the proposed control strategy can effectively use the flexible DC system to support the frequency of the AC system and significantly improve the frequency stability of the faulty AC system.

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Acero, Fredy A., and Mario A. Rios. "Planning a HVDC South American Pacific Electric Interconnection Based on MTDC." IEEE Latin America Transactions 19, no. 8 (August 2021): 1357–65. http://dx.doi.org/10.1109/tla.2021.9475866.

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Xiao, Liang, Yan Li, Huangqing Xiao, Zheren Zhang, and Zheng Xu. "Electromechanical Transient Modeling of Line Commutated Converter-Modular Multilevel Converter-Based Hybrid Multi-Terminal High Voltage Direct Current Transmission Systems." Energies 11, no. 8 (August 13, 2018): 2102. http://dx.doi.org/10.3390/en11082102.

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A method for electromechanical modeling of line commutated converter (LCC)-modular multilevel converter (MMC)-based hybrid multi-terminal High Voltage Direct Current Transmission (HVDC) systems for large-scale power system transient stability study is proposed. Firstly, the general idea of modeling the LCC-MMC hybrid multi-terminal HVDC system is presented, then the AC-side and DC-side models of the LCC/MMC are established. Different from the conventional first-order DC-side model of the MMC, an improved second-order DC-side model of the MMC is established. Besides considering the firing angle limit of the LCC, a sequential power flow algorithm is proposed for the initialization of LCC-MMC hybrid multi-terminal HVDC system. Lastly, simulations of small scale and large scale power systems embedded with a three-terminal LCC-MMC hybrid HVDC system are performed on the electromechanical simulation platform PSS/E. It is demonstrated that if the firing angle limit is not considered, the accuracy of the power flow solutions will be greatly affected. Steady state calculation and dynamic simulation show that the developed LCC-MMC hybrid MTDC model is accurate enough for electromechanical transient stability studies of large-scale AC/DC system.

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Lee, Jae-In, Van Quan Dao, Minh-Chau Dinh, Seok-ju Lee, Chang Soon Kim, and Minwon Park. "Combined Operation Analysis of a Saturated Iron-Core Superconducting Fault Current Limiter and Circuit Breaker for an HVDC System Protection." Energies 14, no. 23 (November 30, 2021): 7993. http://dx.doi.org/10.3390/en14237993.

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Recently, in order to overcome the difficulties of interrupting fault currents in multi-terminal direct current systems (MTDC), studies combining a saturated iron-core type superconducting current limiter (SFCL) and a direct current circuit breaker (DCCB) have been conducted. However, the effect of inductance change of the SI-SFCL on the interrupting time of the DCCB during fault has not been studied yet. In this paper, the interrupting time delay caused by the dynamic behavior of the inductance change during the fault current blocking process of the SI-SFCL combined with a DCCB was analyzed through experiments and a new fault detection method considering this phenomenon was proposed. After designing and manufacturing the laboratory-scale SI-SFCL and DCCB, a fault current interrupting test was performed and the inductance change pattern of the SI-SFCL was analyzed. Based on the analysis results, a new fault detection technique was proposed to alleviate the interruption time delay that occurs when applying the combined protection system to a MTDC, and its effectiveness was verified through a simulation. These results will be useful for planning protection coordination strategies when introducing a SI-SFCL in combination with a DCCB in actual MTDC systems.

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Wu, Zhi, Jiawei Chu, Wei Gu, Qiang Huang, Liang Chen, and Xiaodong Yuan. "Hybrid Modulated Model Predictive Control in a Modular Multilevel Converter for Multi-Terminal Direct Current Systems." Energies 11, no. 7 (July 17, 2018): 1861. http://dx.doi.org/10.3390/en11071861.

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In this paper a hybrid modulated model predictive control (HM2PC) strategy for modular-multilevel-converter (MMC) multi-terminal direct current (MTDC) systems is proposed for supplying power to passive networks or weak AC systems, with the control objectives of maintaining the DC voltage, voltage stability and power balance of the proposed system. The proposed strategy preserves the desired characteristics of conventional model predictive control method based on finite control set (FCS-MPC) methods, but deals with high switching frequency, circulating current and steady-state error in a superior way by introducing the calculation of the optimal output voltage level in each bridge arm and the specific duty cycle in each Sub-Module (SM), both of which are well-suited for the control of the MMC system. In addition, an improved multi-point DC voltage control strategy based on active power balanced control is proposed for an MMC-MTDC system supplying power to passive networks or weak AC systems, with the control objective of coordinating the power balance between different stations. An MMC-HVDC simulation model including four stations has been established on MATLAB/Simulink (r2014b MathWorks, Natick, MA, USA). Simulations were performed to validate the feasibility of the proposed control strategy under both steady and transient states. The simulation results prove that the strategy can suppress oscillations in the MMC-MTDC system caused by AC side faults, and that the system can continue functioning if any one of the converters are tripped from the MMC-MTDC network.

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Loku, Fisnik, Patrick Düllmann, Christina Brantl, and Antonello Monti. "Equivalent Impedance Calculation Method for Control Stability Assessment in HVDC Grids." Energies 14, no. 21 (October 21, 2021): 6899. http://dx.doi.org/10.3390/en14216899.

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A major challenge in the development of multi-vendor HVDC networks are converter control interactions. While recent publications have reported interoperability issues such as persistent oscillations for first multi-vendor HVDC setups with AC-side coupling, multi-terminal HVDC networks are expected to face similar challenges. To investigate DC-side control interactions and mitigate possible interoperability issues, several methods based on the converters’ and DC network’s impedances have been proposed in literature. For DC network’s impedance modelling, most methods require detailed knowledge of all converters’ design and controls. However, in multi-vendor HVDC networks, converter control parameters are not expected to be shared due to proprietary reasons. Therefore, to facilitate impedance-based stability analyses in multi-vendor MTDC networks, methods that do not require the disclosure of the existing converter controls are needed. Here, detailed impedance measurements can be applied; however, they are time-consuming and require new measurement for a single configuration change. This paper proposes an equivalent impedance calculation method suitable for multi-vendor DC networks, which for available black-box models or converter impedance characteristics can be modularly applied for various network configurations, including different control settings and operating points, while significantly reducing the required time for obtaining an equivalent DC network impedance.

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Dong, J., Z. Wang, S. Yan, Z. Wang, B. Jiang, C. Zhu, and C. Wang. "Research on DC voltage droop strategy based on optimal DC power flow." Journal of Physics: Conference Series 2226, no. 1 (March 1, 2022): 012014. http://dx.doi.org/10.1088/1742-6596/2226/1/012014.

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Abstract A coordinated control based on the optimal DC power flow for MTDC is proposed to improve the transmission efficiency of multi-terminal HVDC, which adopts hierarchical structure including processing layer and implementation layer. The dcOPF model of optimal DC power flow is established in the solving layer. The minimum of the generation cost is set as the objective function, and the constraints include the line capacity, generator capacity, converter station capacity and power balance. The optimal solution is applied to the executing layer. When disturbs occur in some converter stations, new optimal solution will be re–calculated and updated to the executing layer and reduce the generation cost. The stability of the system will not be affected by communication fault. A four-terminal VSC-MTDC simulation model in the MATLAB/Simulink platform is built in the paper. The simulation results show that the proposed control strategy can minimize the generation cost and the control strategy has the advantages of simple structure and easy implementation.

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Hoffmann, Melanie, Harold R. Chamorro, Marc René Lotz, José M. Maestre, Kumars Rouzbehi, Francisco Gonzalez-Longatt, Michael Kurrat, Lazaro Alvarado-Barrios, and Vijay K. Sood. "Grid Code-Dependent Frequency Control Optimization in Multi-Terminal DC Networks." Energies 13, no. 24 (December 8, 2020): 6485. http://dx.doi.org/10.3390/en13246485.

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The increasing deployment of wind power is reducing inertia in power systems. High-voltage direct current (HVDC) technology can help to improve the stability of AC areas in which a frequency response is required. Moreover, multi-terminal DC (MTDC) networks can be optimized to distribute active power to several AC areas by droop control setting schemes that adjust converter control parameters. To this end, in this paper, particle swarm optimization (PSO) is used to improve the primary frequency response in AC areas considering several grid limitations and constraints. The frequency control uses an optimization process that minimizes the frequency nadir and the settling time in the primary frequency response. Secondly, another layer is proposed for the redistribution of active power among several AC areas, if required, without reserving wind power capacity. This method takes advantage of the MTDC topology and considers the grid code limitations at the same time. Two scenarios are defined to provide grid code-compliant frequency control.

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Ayari, Mohamed, Mohamed Moez Belhaouane, Chaker Jammazi, Naceur Benhadj Braiek, and Xavier Guillaud. "On the Backstepping Approach for VSC-HVDC and VSC-MTDC Transmission Systems." Electric Power Components and Systems 45, no. 5 (March 8, 2017): 520–33. http://dx.doi.org/10.1080/15325008.2017.1289571.

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Yan, Wen-ning, Ke-jun Li, Zhuo-di Wang, Xin-han Meng, and Jianguo Zhao. "Priority Control Strategy of VSC-MTDC System for Integrating Wind Power." Journal of Electrical and Computer Engineering 2015 (2015): 1–10. http://dx.doi.org/10.1155/2015/347350.

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For the obvious advantages in integrating wind power, multiterminal HVDC transmission system (VSC-MTDC) is widely used. The priority control strategy is proposed in this paper considering the penetration rate of wind power for the AC grid. The strategy aims to solve the problems of power allocation and DC voltage control of the DC system. The main advantage of this strategy is that the demands for wind power of different areas can be satisfied and a power reference for the wind power trade can also be provided when wind farms transmit active power to several AC grids through the DC network. The objective is that power is well distributed according to the output power of wind farm with the demand of AC system and satisfactory control performance of DC voltage is obtained.

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Rasheed, Mr Sheik, Mr Ch Pavan Kumar, and Mr M. Mani Shankar. "Design of Full-Bridge Modular Multilevel Converter with Low Energy Storage Requirements for HVdc Transmission System with Fuzzy Inference System." International Journal of Engineering and Advanced Technology 10, no. 2 (December 30, 2020): 132–40. http://dx.doi.org/10.35940/ijeat.b2067.1210220.

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iThis ipaper iproposes ia ihierarchical iFuzzy iInterface iSystem i(FIS) iPredicated icontrol iarchitecture idesigned ifor ian iarbitrary ihigh ivoltage imulti iterminal idc i(MTDC) inetwork. iModular imultilevel iconverter i(MMC)is ia iwell-proved icircuit itopology iin ivoltage-source iconverter-based ihigh ivoltage idirect icurrent i(VSC-HVdc) itransmission isystems. iAs iis iknown, ithe iconventional ihalf-bridge isubmodule i(HBSM)-based iMMC-HVdc iis inot isuitable ifor ioverhead iline itransmission iapplications. iIn iaddition, ihigh ienergy istorage irequirements, ii.e., ilarge icapacitance iis iinevitable. iThe iconventional idesign iof ithe ifull-bridge isubmodule i(FBSM)-based iMMC iusually idoes inot iutilize ithe inegative ivoltage istate iof iFBSM iin inormal ioperation. iConsidering ithe isame idc ivoltage ias iwith ithe iHBSM icase iand iutilizing ithe inegative ivoltage istate iof ithe iFBSM, ithis ipaper ipresents ithe idesign imethod iof ithe ipower itransmission icapability iof ia isingle iFBSM. iMeanwhile, ian ioptimized ienergy istorage icapacitance idesign imethod iof ithe iFBSM iis iproposed. iWith ithis imethod, ithe icapacitance iof iFBSM ican ibe ireduced isignificantly. iThe icorrectness iand ieffectiveness iof ithe iproposed imethod iis iverified iby ithe isimulation iof ia±160kVVSC-HVdc iMMC iand ithe icomparison iresults iof ithe idc ishort ifault iblocking iand iride ithrough icapability iare ialso iprovided.

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Yang, Jie, YaXin Li, BoYi Xiao, Jun Ma, and BoNian Yi. "Simulation Research on Improved Small Signal Model of VSC Converter." Journal of Physics: Conference Series 2355, no. 1 (October 1, 2022): 012056. http://dx.doi.org/10.1088/1742-6596/2355/1/012056.

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Abstract Small signal model is the basis of stability analysis and control design of VSC-HVDC. In this paper, the small signal model of VSC-MTDC applies to Voltage Source Converters (VSC) in different conditions through theoretical analysis and derivation. The model of ac system can be widely used by choosing d-q synchronous reference frame flexible. Then according to voltage source converter (VSC) modulation principle, the converter model is revised through the coupling mechanism between ac and dc of converter. This article has constructed three kinds of improved small signal models applied to different conditions. By comparing of Electromagnetic transient simulation and the small-signal model simulation, the small-signal model has high accuracy.

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Zhang, Zheren, and Zheng Xu. "Short-circuit current calculation and performance requirement of HVDC breakers for MMC-MTDC systems." IEEJ Transactions on Electrical and Electronic Engineering 11, no. 2 (October 20, 2015): 168–77. http://dx.doi.org/10.1002/tee.22203.

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Rodino, Analcísio António, and Rui Esteves Araújo. "A systematic review of Intelligent Fault-Tolerant Protection Scheme for Multi-terminal HVDC Grids." U.Porto Journal of Engineering 9, no. 3 (April 28, 2023): 240–51. http://dx.doi.org/10.24840/2183-6493_009-003_001939.

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Due to the advancement of power electronics devices and control techniques, the modular multilevel converter (MMC) has become the most attractive converter for multiterminal direct current (MTDC) grids thanks to its most relevant features, such as modularity and scalability. Despite their advantages, conventional MMCs face a major challenge with: i) fault-tolerant operation strategy; i) energy losses in conversion; iii) lack of DC fault handling capability. This paper provides a systematic review to identify the gaps in the literature about Intelligent Fault-Tolerant Protection Schemes for multi-terminal HVDC grids. Through the bibliometric analysis, it was possible to identify topics still to be developed within the four main clusters (Offshore wind farms, Wind turbines, Voltage Source Converters, and Wind power). The research topic opens three research paths: the first is the analysis of failures in HVDC (High Voltage Direct Current) grid equipment by the FDD (Fault Detection and Diagnosis) method; the second is failure analysis by the IFDD (Inverse Fault Detection and Diagnosis) method and the third is the possibility of interconnecting the different energy generation zones with different frequencies.

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Jiang, Lingtong, Qing Chen, Wudi Huang, Lei Wang, Yu Zeng, and Pu Zhao. "Pilot Protection Based on Amplitude of Directional Travelling Wave for Voltage Source Converter-High Voltage Direct Current (VSC-HVDC) Transmission Lines." Energies 11, no. 8 (August 3, 2018): 2021. http://dx.doi.org/10.3390/en11082021.

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This paper presents a novel pilot protection scheme of DC cable line in voltage-source-converter (VSC) based multi-terminal DC (MTDC) grids, which utilizes a novel phase-mode transformation to decouple the bipolar DC cable current into six mode and it uses the stationary wavelet transform to extract the modulus maxima of fault initial traveling waves current (FITWC). With accurate amplitude and polarities of the FITWC being collected from the fault-detection devices located at each terminal, the proposed scheme can correctly determine the faulty segment and the faulty pole. In this paper, the ratio of amplitudes between sixth mode forward and backward travelling wave currents is used to judge the faulty segment and the polarity of fifth mode forward travelling wave current is used to identify the faulty pole. A four-terminal VSC-based MTDC grid was built in PSCAD/EMTDC to evaluate the performance of the fault-protection scheme. Simulation results for different cases demonstrate that the proposed protection scheme is robust against noise, and has been tested successfully for fault resistance of up to 400 Ω. Since the scheme merely needs the characteristics of FITWCs, the practical difficulties of detecting subsequent travelling waves are avoided. Moreover, only the state signal is needed to send to the other side in proposed scheme, so low communication speed can satisfy the requirement of relay protection and it does not need the data synchronization seriously.

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Wei, Si Ming, Yi Gong Zhang, Huan Liu, Zhi Qiang Dai, and Xiao Du. "Design and Simulation of Breaking Time Sequence for DC Circuit Breaker with a Current-Limiting Inductance." Applied Mechanics and Materials 556-562 (May 2014): 1959–63. http://dx.doi.org/10.4028/www.scientific.net/amm.556-562.1959.

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It is great significance for development of MTDC (Multi-terminal HVDC) to build DC transmission and distribution grids. However, the relatively low impedance in DC grids makes the fault penetration much faster and deeper .Consequently, fast and reliable DC circuit breaker is needed to isolate faults. Breaking time and other parameters are important for a breaker to achieve its goals. This paper presents a DC circuit breaker with a current-limiting inductance and gets the rising and falling characteristics of fault current. Based on the characteristics, a design method of breaking time sequence will be given, as well as the calculation of current-limiting inductance and the selection principles of arresters. A 10kV DC distribution grid is modeled and simulated by PSCAD/EMTDC to verify that the method can meet the requirements of breaking fault current quickly and reliably.

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Wang, Yuhan, Zhou Li, and Yuanshi Zhang. "A decision-making method for the operation flexibility enhancement of hybrid cascaded MTDC." Frontiers in Energy Research 11 (September 14, 2023). http://dx.doi.org/10.3389/fenrg.2023.1251496.

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To enable the integration of large-scale renewable energy, hybrid HVDC technology, which combines the technical advantages of LCC-HVDC and VSC-HVDC, is being gradually deployed in the power grid nowadays. The operation of the Wu-dong-de Hybrid DC Project and the Jian-su Hybrid cascaded MTDC Project has proved its advantages. However, for the simultaneous application of different converter station technologies in the system, the control strategies become complex. Issuing appropriate control instructions to ensure system stability according to operational requirements is an issue that cannot be ignored in decision-making. Even under abnormal conditions, when the topology changes due to various failure scenarios, reasonable decision-making and precise control instruction definitions are required. To achieve flexible planning of the MTDC system, this paper presents a decision-making method for control strategies of a hybrid cascaded MTDC system, which analyzes the control strategy combinations selected for normal and abnormal conditions of the MTDC system. In addition, a control instruction calculating method and decision-making process for precise control in normal and abnormal control conditions is proposed. Simulation results based on a five-terminal hybrid cascaded MTDC in PSCAD/EMTDC have verified the effectiveness of the proposed method.

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Buigues, G., V. Valverde, D. M. Larruskain, P. Eguía, and E. Torres. "DC protection in modern HVDC networks: VSC-HVDC and MTDC systems." Renewable Energy and Power Quality Journal, May 2016, 300–305. http://dx.doi.org/10.24084/repqj14.299.

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Kumkratug, Prechanon. "Evaluation Transient Stability of Large Scale Power System with Multi-Terminal HVDC." European Journal of Electrical Engineering and Computer Science 4, no. 4 (July 20, 2020). http://dx.doi.org/10.24018/ejece.2020.4.4.226.

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This paper presents the method of evaluating transient stability of large scale power system equipped with multi-terminal high voltage direct current (MTDC). The power system including synchronous machine, transmission network, and HVDC is based on the concepts of stability mode. In addition, various techniques to reduce the simulation time are systematically applied. The proposed method helps us to access the transient stability of the system with MTDC in the much simpler way. The verification of the methods is tested on 20 generators in an IEEE 118-bus system under various cases.

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Gao, Yang, and Qian Ai. "Multi Point Voltage Control for DFIG wind farms in VSC-MTDC Network." International Journal of Emerging Electric Power Systems 18, no. 2 (April 6, 2017). http://dx.doi.org/10.1515/ijeeps-2016-0174.

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Abstract The development of voltage source converter (VSC) based multi-terminal HVDC network (VSC-MTDC) is emerging as the most adaptive approach to managing high penetration of wind energy in long distance.However, MTDC networks depend on highly controllable devices, which may permit not only transporting power, but also assuring secure and stable operation for AC grids. This paper first presents an overview of different control schemes for VSCs in VSC-MTDC network, then proposes a modification scheme of multi-point DC voltage control for wind farms equipped with doubly fed induction generators (DFIG). Finally, the proposed strategy is verified on PSCAD/EMTDC software, and simulation results show that the state of constant power control and constant DC voltage control can be automatically conversed, thus guarantee the stability of DC voltage and the transmission reliability after the power variation in DFIG wind farms and the operation fault at converter stations.

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Shinoda, Kosei, Jing Dai, Gianni Bakhos, Juan Carlos Gonzalez‐Torres, Abdelkrim Benchaib, and Seddik Bacha. "Design consideration for frequency containment reserve provisions by a multi‐terminal HVDC system." IET Generation, Transmission & Distribution, August 29, 2023. http://dx.doi.org/10.1049/gtd2.12955.

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AbstractFrequency control is considered to be an important function of multi‐terminal HVDC (MTDC) systems. Sharing frequency containment reserves (FCRs) among interconnected AC systems using HVDC technology is particularly attractive in the European context. However, coordination of the contribution between systems with different sizes, quality requirements, and dynamic characteristics requires harmonized rules and well‐defined control strategies. If the controllers are not properly designed, they can lead to disproportional supports, noncompliance with the existing regulation framework, or even degradation of the frequency quality. This paper presents a general analytical methodology for assessing the compliance of MTDC grid control solutions to the essential requirements of the FCR framework, and then examines three different implementation solutions as illustrative examples to validate the method. Through this process, the interaction mechanisms behind each solution are analytically clarified. The performance analyses are then confirmed using load‐frequency models of CE, Nordic, and GB systems coupled with a three‐terminal DC system. It is revealed that, while certain control solutions result in insufficient performance with respect to the desired FCR provision, the newly proposed distributed solution for each pair of converters is the most compliant with the existing framework thanks to the highest degrees of freedom.

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Alavi, Seyed Mohsen, and Reza Ghazi. "A novel control strategy based on a look-up table for optimal operation of MTDC systems in post-contingency conditions." Protection and Control of Modern Power Systems 7, no. 1 (January 28, 2022). http://dx.doi.org/10.1186/s41601-022-00224-3.

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AbstractMulti terminal VSC-HVDC systems are a promising solution to the problem of connecting offshore wind farms to AC grids. Optimal power sharing and appropriate control of DC-link voltages are essential and must be maintained during the operation of VSC-MTDC systems, particularly in post-contingency conditions. The traditional droop control methods cannot satisfy these requirements, and accordingly, this paper proposes a novel centralized control strategy based on a look-up table to ensure optimal power sharing and minimum DC voltage deviation immediately during post-contingency conditions by considering converter limits. It also reduces destructive effects (e.g., frequency deviation) on onshore AC grids and guarantees the stable operation of the entire MTDC system. The proposed look-up table is an array of data that relates operating conditions to optimal droop coefficients and is determined according to N-1 contingency analysis and a linearized system model. Stability constraints and contingencies such as wind power changes, converter outage, and DC line disconnection are considered in its formation procedure. Simulations performed on a 4-terminal VSC-MTDC system in the MATLAB-Simulink environment validate the effectiveness and superiority of the proposed control strategy.

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Khan, Shahid Aziz, Jamshed Ahmed Ansari, Rashid Hussain Chandio, Hafiz Mudassir Munir, Mohammed Alharbi, and Abdulaziz Alkuhayli. "AI based controller optimization for VSC-MTDC grids." Frontiers in Energy Research 10 (September 23, 2022). http://dx.doi.org/10.3389/fenrg.2022.1008099.

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Electric power industry is continually adopting new techniques to improve the reliability and efficiency of the energy system and to cope with the increasing energy demand and the associated technical challenges. In recent years, the maturation of Artificial Intelligence (AI) led researchers to solve various problems in the power system by using AI techniques. Voltage Source Converter is the result of advancements in the field of power electronics and semiconductors technology, which holds a promising future for the realization of smart grid, renewable energy integration, and HVDC transmission system. Usually hit and trial method or the design engineer’s experience is used for the manual tuning of the PI controllers, which cannot yield superior performance. The process becomes more complicated when multiple grids are involved, such as in VSC-based MTDC grids. This research article use a deep learning optimization technique for the tuning of the VSC controllers, which resulted in quick settling time, better slew rate, less undershoot and low overshoot. The deep learning neural network is trained through the Particle Swarm Optimization (PSO) algorithm to produce the best possible tuned or optimally tuned parameters for the controllers. The optimal tuning of the controller will result in an overall better performance of the converter and the grid. A four-layered deep learning neural network and a three-terminal MTDC grid were designed and simulated in MATLAB/SIMULINK environment.

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Zhang, Qian, James D. McCalley, Venkataramana Ajjarapu, Javier Renedo, Marcelo Elizondo, Ahmad Tbaileh, and Nihal Mohan. "Primary Frequency Support through North American Continental HVDC Interconnections with VSC-MTDC Systems." IEEE Transactions on Power Systems, 2020, 1. http://dx.doi.org/10.1109/tpwrs.2020.3013638.

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Kumar, Ancha Satish, and Bibhu Prasad Padhy. "Headroom-based Frequency and DC Voltage Control for Large Disturbances in Multi-Terminal HVDC (MTDC) Grids." IEEE Transactions on Industry Applications, 2024, 1–10. http://dx.doi.org/10.1109/tia.2024.3401671.

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Kinjo, Ryota, Hidehito Matayoshi, Gul Ahmad Ludin, Abdul Motin Howlader, Naomitsu Urasaki, and Tomonobu Senjyu. "Multi-Terminal High Voltage Direct Current Transmission System with DC Resonant Semiconductor Breakers." International Journal of Emerging Electric Power Systems 19, no. 3 (February 27, 2018). http://dx.doi.org/10.1515/ijeeps-2016-0179.

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Abstract:

AbstractIn consideration of the natural environment and depletion of energy resources, the widespread use of electric power system is expected in which the power is generated from sources of renewables such as wind and solar. When these plants are introduced in large scale, the use of broad land is required. Due to low transmission losses and small stability problems, multi-terminal high voltage direct current (MTDC) transmission becomes advantageous as long-distance power transmission system. Since DC current does not incorporate a zero cross point, therefore it’s blocking is difficult. This paper proposes a DC resonant semiconductor breaker which enables rapid fault clearance for self-excited HVDC transmission. This circuit breaker is connected as a semiconductor switch, in parallel with a group of capacitors, and resistors in the DC transmission line. The capacitor is charged to a higher voltage from the DC transmission line. For generating reverse current to allow the zero cross point in the transmission line, the semiconductor switch turns on to open the circuit breaker. After blocking, the inductance of the line is demagnetized by the resistor and fault clearing is achieved. The system except fault point can continue its normal operation.

Journal articles on the topic 'Hvdc; mtdc'

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