An Adaptive Frequency Regulation Method With Grid-Friendly Restoration for VSC-HVDC Integrated Offshore Wind Farms

Lu, Zongxiang; Ye, Yida; Qiao, Ying

doi:10.1109/tpwrs.2019.2901986

Cited by 76 publications

(37 citation statements)

References 26 publications

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“…According to the eqns. (17), (18) and parameters in Table 2, the voltage gain-frequency characteristic curve on the condition of f 0 = 6 kHz (f 0 is the corresponding frequency of ω o ) and m = 6 can be expressed as Fig.8, which shows that both Q e and f have impact on voltage gain. Assuming that the onshore MMC regulates the DC voltage of high-voltage side as a constant, and the submodule output voltages are balanced well, and PMSGs connect to the MVDC via diode rectifiers, the input voltage of the MMDC varies following the excitation electromotive force of the wind turbine.…”

Section: Control System a Operating Curve Of The Llc Submodulementioning

confidence: 99%

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A Modular Multiple DC Transformer Based DC Transmission System for PMSG Based Offshore Wind Farm Integration

Yin

2020

IEEE Access

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In this paper, a modular multiple DC (MMDC) transformer based DC transmission system, which is used for permanent magnetic synchronous generator (PMSG) based offshore wind farm grid connection, is proposed. The MMDC transformer is composed of input-parallel output-series (IPOS) DC/DC submodule groups, each of which consists of several input-series output-series (ISOS) LLC resonant converters (i.e., submodules). In the offshore wind farm, the electrical power generated by PMSG is converted to DC power by diode rectifier. Compared with the existing offshore wind farm grid-connection schemes, the proposed system has advantages of fewer conversion stages, higher efficiency and lower cost. The mathematical relationship of the system is studied, and then one kind of control strategy is proposed. Furthermore, a detailed DC transmission system simulation model containing a 160 submodules (LLC resonant converters) based MMDC transformer is built in PSCAD/EMTDC. Finally, a down-scaled experimental prototype of the DC system, which includes 9 submodules, is presented. Both simulation and experimental results validate the feasibility of the proposed DC system and effectiveness of the control strategy. INDEX TERMS Offshore DC wind farm, modular multiple DC transformer, HVDC, input-parallel outputseries, input-series output-series.

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Section: Control System a Operating Curve Of The Llc Submodulementioning

confidence: 99%

“…Thus, according to eqns. (16) and (17), the submodule voltage gain is dependent on the excitation electromotive force of PMSG (e s ). In the meantime, the Q e is also dependent on the input power, see eqn.…”

Section: Control System a Operating Curve Of The Llc Submodulementioning

confidence: 99%

A Modular Multiple DC Transformer Based DC Transmission System for PMSG Based Offshore Wind Farm Integration

Yin

2020

IEEE Access

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“…In addition, with regard to stability control of the power system interconnected with the offshore wind power, most studies concentrate on the rotor-angle stability control [6], the voltage stability control [7], the damping control [8] and the steady state frequency control [9], while few of the work concentrate on the transient frequency stability control. For example, ref.…”

Section: Introductionmentioning

confidence: 99%

“…[8] presents a coordinated damping control through offshore wind farms and onshore VSC-HVDC converters to restrain power oscillation; ref. [9] develops the frequency regulation strategies for offshore wind farms at the device level.…”

Section: Introductionmentioning

confidence: 99%

Transient Frequency Stability Emergency Control for the Power System Interconnected With Offshore Wind Power Through VSC-HVDC

Xue

Zhang

et al. 2020

IEEE Access

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For the power system interconnected with the large-scale offshore wind power through VSC-HVDC, such as SZ power grid, it may be engaged with transient frequency stability and lack of related control due to the randomness, fluctuation and intermittence of the wind. This paper proposes a transient frequency control strategy for the power system interconnected with offshore wind power through VSC-HVDC based on sensitivity. Firstly, the structure of SZ power grid and the calculation method of transient frequency stability index are introduced, and the transient frequency problems existing in SZ power grid are explored. Secondly, the mathematical formulation for the transient frequency control is described, including the objective function and the constraints. Furthermore, a transient frequency emergency control strategy based on special sequence and the sensitivities is proposed, which includes thermal units regulation, wind power regulation, DC modulation and load shedding. Finally, the effectiveness of the proposed control strategy is verified by simulation in SZ power grid. INDEX TERMS Wind power, VSC-HVDC, transient frequency stability, emergency control strategy.

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“…A cascading control strategy is proposed in [25] to minimise the control impacts on wind energy harvesting while providing system frequency support by firstly exerting HVDC capacitors energy and then WT rotor kinetic energy with the aid of communication between the OWF and offshore power system. However, the required real-time remote communication link will increase the total investment and have the problem of communication delays, where OWF cannot provide immediate frequency support after frequency transients, so it is difficult to apply to practical complex systems [16,26].…”

Section: Introductionmentioning

confidence: 99%

Coordinated control of MMC‐HVDC system with offshore wind farm for providing emulated inertia support

Zeng

Liu

Wang

et al. 2020

IET Renewable Power Generation

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With the continuous increase of renewable energy generation and high voltage direct current (HVDC) power transmission, the system inertia is declining, thus resulting in greater risks of frequency instability. To solve this issue, a dc-link inertia control is firstly proposed for a point-to-point modular multilevel converter based HVDC (MMC-HVDC) link, which enables the MMC-HVDC system to provide emulated inertia support by employing the electrostatic energy stored in the dc capacitors. Moreover, in order to maintain reasonable submodule capacitor size as well as provide more emulated inertia support, a virtual capacitor control for MMC-HVDC connected an offshore wind farm (OWF) is proposed. With the virtual capacitor control, the OWF is able to provide a large capacity virtual capacitor in dc side of MMC-HVDC link and supply desired emulated inertia support for onshore power system by utilising the offshore wind turbines' rotor rotational kinetic energy. Furthermore, a procedure for selecting the appropriate virtual capacitor control parameters is proposed. Finally, the performance of the proposed coordinated control is researched in PSCAD/EMTDC, and the simulation results show that the onshore power system inertia is effectively improved with the coordinated control.

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An Adaptive Frequency Regulation Method With Grid-Friendly Restoration for VSC-HVDC Integrated Offshore Wind Farms

Cited by 76 publications

References 26 publications

A Modular Multiple DC Transformer Based DC Transmission System for PMSG Based Offshore Wind Farm Integration

A Modular Multiple DC Transformer Based DC Transmission System for PMSG Based Offshore Wind Farm Integration

Transient Frequency Stability Emergency Control for the Power System Interconnected With Offshore Wind Power Through VSC-HVDC

Coordinated control of MMC‐HVDC system with offshore wind farm for providing emulated inertia support

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