Novel Control Approach for a Hybrid Grid-Forming HVDC Offshore Transmission System

Tian, Shangen; Campos‐Gaona, David; Lacerda, Vinícius Albernaz; Torres-Olguin, Raymundo E.; Anaya‐Lara, Olimpo

doi:10.3390/en13071681

Cited by 9 publications

(6 citation statements)

References 18 publications

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“…PSC controllers are proposed for VSC-HVDC applications, especially when connected to the weak grids, as the PSC gird-forming HVDCs can improve voltage stability in the weak grids [30]. Another grid forming control method to control the AC voltage and reduce the harmonics of the HVDC converters is proposed in [145]. The outer loop in this control method consists of an AC voltage controller and a DC-voltage controller to control the power-sharing in the system.…”

Section: B Application Of Grid Forming Inverters In Hvdc Convertersmentioning

confidence: 99%

Grid Forming Inverter Modeling, Control, and Applications

et al. 2021

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This paper surveys current literature on modeling methods, control techniques, protection schemes, applications, and real-world implementations pertaining to grid forming inverters (GFMIs). Electric power systems are increasingly being augmented with inverter-based resources (IBRs). While having a growing share of IBRs, conventional synchronous generator-based voltage and frequency control mechanisms are still prevalent in the power industry. Therefore, IBRs are experiencing a growing demand for mimicking the behavior of synchronous generators, which is not possible with conventional grid following inverters (GFLIs). As a solution, the concept of GFMIs is currently emerging, which is drawing increased attention from academia and the industry. This paper presents a comprehensive review of GFMIs covering recent advancements in control technologies, fault ride-through capabilities, stability enhancement measures, and practical implementations. Moreover, the challenges in adding GFMIs into existing power systems, including a seamless transition from grid-connected mode to the standalone mode and vice versa, are also discussed in detail. Recently commissioned projects in Australia, the UK, and the US are taken as examples to highlight the trend in the power industry in adding GFMIs to address issues related to weak grid scenarios. Research directions in terms of voltage control, frequency control, system strength improvement, and regulatory framework are also discussed. This paper serves as a resource for researchers and power system engineers exploring solutions to the emerging problems with high penetration of IBRs, focusing on GFMIs.INDEX TERMS Current control, fault ride-through, grid forming inverters, power synchronization control, small-signal and transient stability, virtual inertia.

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Section: B Application Of Grid Forming Inverters In Hvdc Convertersmentioning

confidence: 99%

Grid Forming Inverter Modeling, Control, and Applications

et al. 2021

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“…The investment and building difficulty would increase with deeper water depth and longer offshore distance. To overcome these difficulties, a diode rectifier-based HVDC topology is proposed, of which investment can be 30% of the VSC-HVDC as a more economical solution for long-distance offshore wind farms [4,5]. However, there are several technical challenges for the DR-HVDC offshore wind power transmission system.…”

Section: Introductionmentioning

confidence: 99%

Control Strategy for Offshore Wind Farms with DC Collection System Based on Series-Connected Diode Rectifier

Xie

Cheng²,

2022

Sustainability

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The DR-HVDC (Diode rectifier-based HVDC) transmission topology was recently proposed for integration on large offshore wind farms due to its low investment cost and high reliability. To further reduce the investment, a DC collection topology based on the series-connected diode rectifiers (DR) is proposed, where no offshore platform is needed. However, units of series-connected topology (SCU) show coupling issues, such as overvoltage, energy curtailment, and fault isolation. First, the coupling mechanism is analyzed, and a suitable operation mode for SCUs is selected to ensure the safe operation of the DC system. Then, the linear relationship of active power and output DC current and DC voltage of SCUs is analyzed, and a novel coordinate control strategy for DC wind farms is proposed, where an onshore converter adapts a DC current controller and wind turbines adapt a mediate output voltage control strategy. The mediate output voltage control strategy includes a triple loop with power loop, mediate output voltage loop, and current loop. Also, the DC open line fault, DC grounding fault, and AC grounding fault of the onshore grid are investigated, and a protection strategy is proposed. A 160 MW wind farm with a DR-SCU DC collection system is built in PSCAD/EMTDC to verify the validity of the proposed control strategy under unequal wind speeds, DC fault, and onshore AC fault, and the results validate the performance of the proposed strategy.

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“…However, PR-control is not easy to tune, and it is susceptible to parameter variations. The reference [9] provides a simple harmonic current compensation based on PI controllers and synchronous reference frames. Although the PI controller is easy to tune, the response time is longer than the proportional-resonant (PR) controllers since it uses slow digital filtering stages for each harmonic controller.…”

Section: Introductionmentioning

confidence: 99%

Fast Harmonic compensation in hybrid HVDC offshore system

Tian

Campos‐Gaona²,

Pena-Alzola³

et al. 2022

J. Phys.: Conf. Ser.

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Hybrid HVDC systems have been proposed as an alternative for nominal VSC-Based HVDC for offshore applications. Hybrid HVDC systems consist of an offshore power station composed of the connection of high-power diode rectifiers in series with a fractional power VSC-HVDC. This hybrid configuration allows large power transfer from offshore sites, with the added robustness, simplicity and efficiency of uncontrolled rectifiers. In this research, a robust and fast-acting controller, the Two Degrees of Freedom Internal Model controller (2DF-IMC), is used to control the active power filter features of the fractional-power VSC-HVDC system, resulting in a much faster overall THD reduction in the offshore AC currents in dynamic conditions (i.e. time-varying wind power) when compared with standard active power filter controllers. This improvement is the direct consequence of the fast closed-loop dynamics of the 2DF-IMC controller that do not require filtering stages. Additionally, the increased closed-loop response time did not affect the overall robustness of the control system, thanks to the enhanced disturbance rejection capabilities of the 2DF-IMC configuration.

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Novel Control Approach for a Hybrid Grid-Forming HVDC Offshore Transmission System

Cited by 9 publications

References 18 publications

Grid Forming Inverter Modeling, Control, and Applications

Grid Forming Inverter Modeling, Control, and Applications

Control Strategy for Offshore Wind Farms with DC Collection System Based on Series-Connected Diode Rectifier

Fast Harmonic compensation in hybrid HVDC offshore system

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