Insights on the Provision of Frequency Support by Wind Power and the Impact on Energy Systems

Attya, Ayman; Domínguez‐García, José Luis

doi:10.1109/tste.2017.2759503

Cited by 53 publications

(30 citation statements)

References 20 publications

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“…On the contrary, when the frequency event is severe, the value of f m d does not manipulate the provided support, as the WTG is required to provide all the available support to tackle such deep excursions. The minor impact of f m d on Accelerative deloading method is noticeable, since this method is rotor speed driven, where a slight change in reference speed leads to almost the same responsive power support, therefore the PF is not affected by changing f m d. This also returns to the tight control region of KAcc within 15% of the WTG rotor speed to mitigate potential negative effects on the WTG mechanical components and structure as discussed in [30]. Comparing Figure 9 and Figure 11, there is a clear deterioration in PF; this can be because the system needs support for longer intervals, exhausting the WTG power reserve which mitigates the support capacity.…”

Section: A Impact Of Frequency Threshold To Release the Full Reservementioning

confidence: 99%

A Novel Method to Valorize Frequency Support Procurement by Wind Power Plants

Attya

Domínguez‐García

2020

IEEE Trans. Sustain. Energy

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The provision of frequency support by renewable power is a key challenge to allow higher penetration of renewables. While the research efforts focus on proposing new control methods and market structures to realize and facilitate the provision of frequency services by wind power, less attention is given to financial compensation of proper responses. This paper proposes a comprehensive method to evaluate the net payments to participating wind power plants, including a penalty factor for responses that do not comply with grid codes and market bids. This method integrates frequency data and dynamic response of wind power assets during the events, to evaluate the compliance level under a certain grid code, and calculates the corresponding net payment. The paper demonstrates the method by integrating the worst frequency event in each month from the real recorded data of UK National grid frequency response in 2016. The results obtained show clear diversities between the three examined support methods with clear influence of the incident wind speed. Kinetic energy extraction support method shows a little merit at high wind speeds, while pitch deloading method performs better at the majority of the examined case studies. Index Terms-Wind power plants, ancillary services, frequency stability, grid codes, reserve markets. I. NOMENCLATURE ∆E Energy support during frequency event [MWH] ∆P5, ∆P30 Average power support within 5s and 30s [MW] ∆Pa Actual power support [MW] Aδ Tolerance factor [-] CF Capacity factor [-] CP, CE Power and energy prices [€/MW, €/MWH] DF Deloading ratio [-] flow Frequency violation threshold [Hz] f m d

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Section: A Impact Of Frequency Threshold To Release the Full Reservementioning

confidence: 99%

A Novel Method to Valorize Frequency Support Procurement by Wind Power Plants

Attya

Domínguez‐García

2020

IEEE Trans. Sustain. Energy

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“…(2) The amount of extractable KE is influenced. Accordingly, it is preferable from the KE perspective to run the WT at a slightly higher speed; however this is not the favourite option from WT load and fatigue viewpoint [4].…”

Section: Rotor Speed Deloadingmentioning

confidence: 99%

Provision of Ancillary Services by Wind Power Generators

Attya¹,

Domínguez‐García²

2020

Advances in Modelling and Control of Wind and Hydrogenerators

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The current and future power systems foresee very deep penetration of renewable power plants into the generation mix, which will make the provision of ancillary services by renewables an ultimate necessity. This would be further emphasised when green power stations replace conventional power plants that rely on fossil fuels. In this context, many control methodologies could be applied to the controllers of the green generators to enable the provision of these services, mainly frequency support and voltage regulation. Most of the available models (i.e. in power system simulators) do not include such supplementary controls to provide ancillary services. Hence, this chapter exploits key examples of these controllers that proved to be efficient and widely accepted. In addition, this chapter considers their integration into the conventional controls of green generators, where the focus is on wind energy.

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“…Notice that: i) when ≥ rated the WT inertia is used because the kinetic energy stored in the WT is much, and when < rated it stops using the kinetic energy to prevent the WT shut down. In addition, the 0.7 rated is chosen in order to keep a smooth speed of the WT [10,24].…”

Section: Operation Modes and Transition Conditionsmentioning

confidence: 99%

“…These three methods are described as follows: 1) Virtual inertia is created to respond to frequency drops by using the kinetic energy stored in rotating masses of WTs. In case of variable speed wind turbines (VSWTs), they have more kinetic energy to be converted into electrical energy when the rotor speed of VSWTs is around the rated value [10]- [11]. Rotor inertia control can provide short-time power support along few seconds, and it may need the rotor speed recovery (RSR) control.…”

Section: Introductionmentioning

confidence: 99%

Coordinated Primary and Secondary Frequency Support Between Microgrid and Weak Grid

Xiao

Mingke

et al. 2019

IEEE Trans. Sustain. Energy

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Dispersed wind power connected to the weak grid may cause the frequency instability. In this paper, a hierarchical controller applied to a microgrid (MG), including wind turbines (WT) and battery units (BU), is proposed to provide in a coordinated frequency support to a weak grid by adjusting the tieline active power flow according to the frequency-grid requirements. The coordination between MG local and central controllers provides the following features. (i) In case of required grid-frequency, the MG tie-line power flow will be controlled to be constant in each dispatching time interval. (ii) In case of underfrequency, the coordination between WT virtual inertia and BU controllers will be used to participate in primary frequency regulation (PFR). Then, BU supplies power according to the secondary frequency regulation (SFR) commanded by the maingrid dispatch center. (iii) In case of over-frequency, BU absorbs power to reduce the tie-line active power for PFR purposes. After that, the SFR uses pitch control coordinated with the battery charge control. A stability analysis model is established to deal with several transitions among different operation modes and the interaction between the weak grid impedance and the MG output impedance. Simulation results are presented to validate the proposed approach. Index Terms-Wind/battery microgrids, primary frequency regulation (PFR), secondary frequency regulation (SFR), hierarchical control, central controller, local controller NOMENCLATURE Parameter DescriptionWW Generated wind energy [J] T Scheduling period [min] PWf Forecast output power of WT [W] PT Average wind power [W] B * Reference power of the BU inverter [W] PWT Actual WT output power [W] PWT * WT expected output power [W] Pinertia WT virtual power inertia [W] f Difference between the grid frequency and the rated one [Hz] k PFR factor [-] kd Differential coefficient of the frequency deviation [-] PAGC_MG AGC power scheduling of MG [W] PAGC_g AGC power scheduling of grid[W] CMG Frequency-regulation capacity of the MG [W] are with Tianjin Key Laboratory of Advanced Electrical Engineering and Energy Technology, Tianjin Cg Frequency-regulation capacity of the grid [W] fmin Minimum value of the normal frequency [Hz] fmax Maximum value of the normal frequency[Hz]  WT rotor angle speed [rad/s] rated WT rotor rated angle speed [rad/s]  PMSG rotor position angle[] p Pole pairs number of PMSG[-] Psloss PMSG stator losses[W] isabc PMSG stator current[A] Udc Back-to-back converter dc bus voltage[V] Air density [kg/m 3 ] WT radius[m] Wind energy utilization factor [W‧s 3 /kg‧m 2 ] β * Pitch angle reference of the WT [] β Pitch angle of the WT [] λ Tip speed ratio[-] maximum wind energy utilization factor [W‧s 3 /kg‧m 2 ] Popt WT maximum power [W] sd , sq d-q stator inductances [mH] s Stator resistance [Ω] sd , sq d-q stator voltages [V] Synchronous angular velocity[rad/s] φ Permanent magnet flux of the PMSG [Wb] Te Electromagnetic torque of the PMSG [N‧m] E Kinetic energy stored in the WT [J] J Inertia of the WT and i...

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Insights on the Provision of Frequency Support by Wind Power and the Impact on Energy Systems

Abstract: Index Terms-wind power; ancillary services; HVDC; frequency stability; virtual inertia; load fatigue.

Cited by 53 publications

References 20 publications

A Novel Method to Valorize Frequency Support Procurement by Wind Power Plants

A Novel Method to Valorize Frequency Support Procurement by Wind Power Plants

Provision of Ancillary Services by Wind Power Generators

Coordinated Primary and Secondary Frequency Support Between Microgrid and Weak Grid

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