Quantitative Control Approach for Wind Turbine Generators to Provide Fast Frequency Response with Guarantee of Rotor Security

TL;DR

This paper introduces a quantitative control method for DFIG wind turbines to provide fast frequency response, ensuring rotor safety and operational constraints are maintained without extra protection schemes.

Contribution

A novel control approach that quantifies maximum power surge for fast frequency response while guaranteeing rotor safety and respecting operational limits.

Findings

Effective inertial response achieved

Rotor speed remains within safe limits

Operational constraints are satisfied during response

Abstract

Wind generation is expected to reach substantially higher levels of penetration in the near future. With the converter interface, the rotor inertia of doubly-fed induction generator (DFIG) based wind turbine generator is effectively decoupled from the system, causing a reduction in inertial response. This can be compensated by enabling the DFIG to provide fast frequency response. This paper proposes a quantitative control approach for DFIG to deliver fast frequency response in the inertial response time scale. A supplementary power surge function is added to the active power reference of DFIG. The exact amount of power surge that is available from DFIG-based wind turbine is quantified based on estimation of maximum extractable energy. Moreover, the operational constraints such as rotor limits and converter over-load limit are considered at the same time. Thus, the proposed approach not only provides adequate inertial response but also ensures the rotor speed is kept within a specified operating range. Rotor safety is guaranteed without the need for an additional rotor speed protection scheme.