Enhanced Frequency Control Capabilities from Wind Turbine and Plant

This work is part of the TotalControl-project that has received funding from the European Union’s Horizon 2020 research and innovation program under grant agreement No. 727680.

Background and Motivation

With increasing penetration of wind power in the power system, frequency control problem may arise because of the loss of system inertia due to non-synchronous production through power converters.  The initial, very fast response to a frequency deviation offered by synchronous generators (SGs) cannot be provided by wind turbine generators (WTGs) since they are mechanically decoupled from the power system by power electronics interfaces.  As a result, bigger frequency deviations may occur after sudden loss of generation or load, which increases the risk of frequency instability.

Virtual Synchronous Machine (VSM) control is an approach for controlling converters to emulate the behavior of a SG.  This makes a WTG have the same inertia response and frequency control capability as a SG, which enables wind power integration to have no harm to power system frequency stability.  Besides, for a WTG, VSM can be seen as a more advanced implementation of the synthetic inertia where active power references are not calculated depending on frequency derivative of the grid, but an internal inertia model.

Moreover, frequency control requires the availability of additional power if the rate-of-change-of-frequency (RoCoF) is negative, which is the case after sudden loss of generation.  Therefore, energy storage is a useful supplement, both to provide enough power for the initial inertia response and to supply sufficient energy for subsequent frequency recovery.

The main research questions that the project aims at answering are:

  • Would a VSM type of control improve the capabilities of WTGs and wind power plants (WPPs) to provide frequency control?
  • What is the role of energy storage in enhancing frequency control from WTGs/WPPs?

Project Objectives

To answer the research questions, this project will realize the implementation of VSM control and energy storage to WTGs and WPPs, exploration of their influence on frequency control capability of WTGs and WPPs and optimization of operation and control of the WTG and WPP with VSM and energy storage. The objectives can be formulated as:

  • Frequency control capability of WTG with VSM control
    The effect of VSM control on the frequency control capability of WTG will be investigated.  Different VSM control schemes will be examined for better applicability to Type 4 WTG.
  • Frequency control capability of WTG with VSM control and energy storage
    It will be researched on whether the combination of VSM control and energy storage will improve the frequency control capability of WTG or not.  Also the configuration of energy storage will be optimized for this case.
  • Frequency control capability of WPP with VSM control and energy storage
    It is worth researching on whether there are differences for the frequency control capability of a WPP with variations of implementation of VSM control and energy storage to the WTGs, how much the difference is and how much it can be optimized for a certain scenario.  A optimization algorithm will be considered and utilized to optimize the control parameters.

Contact

Liang Lu
PhD student
DTU Wind Energy
+45 31 96 49 52