AC Voltage Control of DC/DC Converters Based on Modular Multilevel Converters in Multi-Terminal High-Voltage Direct Current Transmission Systems

Rui, Li; Fletcher, John

doi:10.3390/en9121064

Cited by 3 publications

(3 citation statements)

References 14 publications

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“…The suppression scheme of flexible DC high-frequency oscillation needs to be based on model construction. The related literature establishes a high-order linear model of converter station, which gradually reveals the influence of control system and its parameters on impedance characteristics [6,7]. Literature [8] simulates the delay link of large link with Pade function, and identifies that the current inner loop, delay size, voltage feedforward link and distributed capacitance of AC transmission line are the key factors leading to the high-frequency resonance of the system through participation factor analysis, while the circulation suppression has little influence on high-frequency oscillation.…”

Section: Introductionmentioning

confidence: 99%

Design of a High Frequency Stability Control Algorithm for Flexible DC Systems

An,

Wei,

Zhao

et al. 2024

J. Phys.: Conf. Ser.

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The suppression scheme of flexible DC high-frequency oscillation needs to be based on model construction. Related literatures have established a high-order linearization model of converter station, gradually revealing the influence of control system and its parameters on impedance characteristics. In order to ensure the full utilization of renewable energy, it is necessary to deeply study the interaction characteristics between multi-terminal VSC-HVDC (Voltage Source Converter based High Voltage Direct Current Transmission) and the receiving power grid, and design a grid-friendly control strategy. In this paper, a VSC-HVDC high-frequency stability control algorithm is established, and a double-ended VSC-HVDC bidirectional VSC stable switching controller is constructed. The switching sequence generated by the controller replaces the control sequence generated by the previous PWM (Pulse width modulation) modulation, so as to weaken the influence of the inner loop current control parameters on the stable operation of the system. The simulation results show that the reactive power fluctuation amplitude of PI control on the inverter side is 0.031 p.u, and the stabilization time is 0.43s. The reactive power fluctuation amplitude of bidirectional VSC stable switching control is less than 0.012 p.u, and the stability time is less than 0.2s. When the single-phase grounding wire is short-circuited, the bidirectional VSC regulator switch has better control performance than the PI regulator switch. Compared with the traditional PI controller, the proposed controller has better stability. The system can quickly enter a stable and non-overshoot operation state, and achieved good control effect.

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Section: Introductionmentioning

confidence: 99%

Design of a High Frequency Stability Control Algorithm for Flexible DC Systems

An,

Wei,

Zhao

et al. 2024

J. Phys.: Conf. Ser.

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“…The works in [32] compare the performance differences between VSC-HVDC and MMC-HVDC in detail from symmetric and asymmetric faults. Reference [33] proposed a multi-terminal MMC-HVDC system, and the control flexibility and reliability were analyzed. Aiming at the problem of the DC side fault of the multi-terminal HVDC system based on MMC, the literature [34] proposed a method to reliably remove the DC fault terminal using a hybrid DC switch.…”

Section: Introductionmentioning

confidence: 99%

Analysis of Fault and Protection Strategy of a Converter Station in MMC-HVDC System

et al. 2022

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With the development of power energy technology, flexible high voltage direct current (HVDC) systems with high control degree of freedom flexibility, power supply to passive systems, small footprint, and other advantages stand out in the field of long-distance large-capacity transmission engineering. HVDC transmission technology based on a modular multilevel converter has been widely used in power grids due to its advantages such as large transmission capacity, less harmonic content, low switching loss, and wide application field. In the modular multilevel converter (MMC)-based HVDC system, the protection strategy of converter station internal faults is directly related to the reliability and security of the power transmission system. Starting from the MMC topological structure, this paper establishes the MMC mathematical model in a synchronous rotation coordinate system by combining the working state of sub-modules and the relationship between each variable of the upper and lower bridge arms of each phase of the MMC. It provides a theoretical basis for the design of the MMC-HVDC control system. The causes of the AC system faults and the internal faults of the converter station in the MMC-HVDC system are analyzed, and the sub-module faults and bridge arm reactor faults in the converter station are studied. The sub-module redundancy protection and bridge arm overcurrent protection strategies are designed for the faults, and the correctness of the scheme is verified by Matlab/Simulink.

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“…To increase the MMC's performance, many research articles have been published. The mathematical modelling, modelling approaches, and semiconductor needs of the MMC in various working situations have been studied in [9][10][11]. Two key priorities associated with the MMC are capacitor voltage balancing and CC suppression, and numerous control systems based on feedback control or the sorting algorithm have been projected and published in [12][13][14].…”

Section: Introductionmentioning

confidence: 99%

Circulating Current Control of Phase-Shifted Carrier-Based Modular Multilevel Converter Fed by Fuel Cell Employing Fuzzy Logic Control Technique

Priya

Ponnambalam

2022

Energies

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The contribution of the modular multilevel converter (MMC) in integrating non-conventional energy sources into the grid is significant; the integration of fuel cells with distributed energy sources is especially prominent as they provide a constant voltage and current for constant load applications. Still, there is a high demand for a high-quality power conditioning unit since there is an occurrence of frequent power spikes. Further, the circulating current (CC) in phase legs is an inherent phenomenon of MMC that must be mitigated. Hence, this article proposed an MMC incorporating a fuzzy logic controller (FLC)-based technique to control the circulating currents. The fuzzy controller effectively reduced the harmonics of the CC in the dc-link system. In addition, phase-shifted carrier (PSC) modulation was employed for the MMC to improve the capacitor voltage balancing to maintain the constant input voltage. Moreover, a mathematical analysis of PSC modulation for MMC was performed to identify the PWM harmonic characteristics of the output voltage and the CC. The performance analysis of the proposed system was tested using the hardware in loop (HIL) simulation with the help of the real-time simulator OP-5700 to verify the feasibility.

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AC Voltage Control of DC/DC Converters Based on Modular Multilevel Converters in Multi-Terminal High-Voltage Direct Current Transmission Systems

Cited by 3 publications

References 14 publications

Design of a High Frequency Stability Control Algorithm for Flexible DC Systems

Design of a High Frequency Stability Control Algorithm for Flexible DC Systems

Analysis of Fault and Protection Strategy of a Converter Station in MMC-HVDC System

Circulating Current Control of Phase-Shifted Carrier-Based Modular Multilevel Converter Fed by Fuel Cell Employing Fuzzy Logic Control Technique

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