Fault‐ride‐through requirements for wind power plants in the ENTSO‐E network code on requirements for generators

Abstract

The need for European Network Codes (NCs) was identified during the course of developing the third legislative package for an internal EU gas and electricity market. The first NC that was initiated by the European Commission covers 'Requirements for Generators' (NC RfG) (ENTSO-E, 2013). After an extensive debate and drafting process across TSOs, DSOs, manufacturers, generation owners, industrial consumers, NRAs and policy makers, ENTSO-E finalised drafting the NC RfG in March 2013 (Further changes, especially with respect to the fault-current injection by wind power plant (WPP) were introduced during the process of transferring NC RfG to a EU Regulation as result of the ongoing discussions between the European Commission and relevant stakeholders. See the remark in Section 3 'Outlook and Conclusion'.). European wind turbine manufacturers represented by EWEA participated strongly in the dialog with ENTSO-E and the stakeholder consultation. A delicate exercise in developing the NC RfG was the appropriate balance between those aspects that need to be defined exhaustively at European level, and the non-exhaustive connection requirements where further specifications are needed at regional level to cover local system needs. Although improvements were seen, significant concerns still remain with the current document, largely focused on the uncertainty from the many non-exhaustive requirements and therefore having to wait for the national Grid Code processes for many parameters. This study explores the need for fault-ride-through capability from a power system security point of view. The requirements stated in the NC RfG, capabilities of WPPs and challenges related to the non-exhaustive requirements of the NC RfG are presented and discussed with the intention to provide technical background information, which may support the national implementation of these requirements.

A Review on Grid-Connected Converter Control for Short-Circuit Power Provision Under Grid Unbalanced Faults

“…However, unnecessary disconnections of power generation subject to grid disturbances impose threats to the security of supply of power systems. Therefore, different national and international codes have defined low-voltage fault-ride-though requirements in form of lower limit of a voltage-against-time profile at the PCC [18], [19], whose parameters of voltage and time vary from country to country [20]- [22]. On the other hand, over-voltage problem can occur in non-faulty phases during grid unbalanced faults, which may also lead to power generation disconnection undesirably [23].…”

“…Therefore, reactive current injection from wind farms is required by TSOs internationally, which is summarized in Table I for several European countries based on [19], [22], [24], [25]. For example, Germany enforces additional reactive current injection in terms of positive-sequence amounting to at least 2% of the rated current for each percent of voltage dip, which should reach 90% of steady-state value within 50 ms. As can be observed from Table I, specific requirements for unbalanced grid faults are lacking as negative-sequenece current could be injected by converters under grid unbalanced faults.…”

A Comparative Study on Controllers for Improving Transient Stability of DFIG Wind Turbines During Large Disturbances

“…The widespread integration of Renewable Energy Systems (RESs) into the existing power systems is raising technical challenges for voltage regulation [32]. Among RESs interconnected into the power systems, the highest share is represented by wind farms, which must ensure reactive power control for ensuring voltage level support.…”

“…In case of mains supply short-circuits, the tasks of RSC and GSC may be changed depending on whether the crowbar protection is triggered or not [32]. If the crowbar is not triggered, the RSC and GSC realizes the objectives as in the conventional scheme [42].…”

Improved LVRT based on coordination control of active crowbar and reactive power for doubly fed induction generators

“…Two of the most important issues refer to frequency and voltage stability [3][4][5]. Along with the permanent magnet synchronous generators (PMSG), the doubly fed induction generators (DFIGs) are mostly used by wind turbines manufacturers.…”