Application of Bang–Bang Controller to Emulate Primary Frequency Response in DFIGs

Abstract

This article proposes a bang–bang auxiliary frequency control scheme for doubly-fed induction generator (DFIG)-based wind turbines. It results in the DFIGs emulate the primary frequency control of conventional units and, thus, increases the power system frequency stability. Indeed, the suggested hysteresis controller causes to deliver the maximum extractable kinetic energy of DFIGs to the grid and consequently further enhance the power system frequency. This is accomplished using different frequency deviation indices, which determine the size of power mismatch and lead to an appropriate frequency response by the DFIGs. The operational constraints of the DFIGs are taken into account in the design procedure of the controller. The proposed controller implies negligible implementation cost and its parameters must be chosen considering a compromise between the amount of DFIGs’ provided power during the frequency support period and the subsequent wear and tear due to the frequency response. Extensive time domain simulations on an IEEE 9-bus test system verify the efficiency of proposed controller.