Frequency Inertia Response Control of SCESS-DFIG under Fluctuating Wind Speeds Based on Extended State Observers

Abstract

Insufficient frequency regulation capability and system inertia reduction are common problems encountered in a power grid with high wind power penetration, mainly due to the reason that the rotor energy in doubly fed induction generators (DFIGs) is isolated by the grid side converters (GSCs), and also due to the randomness and intermittence of wind power which are not as stable as traditional thermal power sources. In this paper, the frequency inertia response control of a DFIG system under variable wind speeds was investigated. First, a DFIG system topology with rotor-side supercapacitor energy storage system (SCESS-DFIG) was introduced. Then a control strategy for frequency inertia response of SCESS-DFIG power grid under fluctuating wind speed was designed, with two extended state observers (ESOs) which estimate the mechanical power captured by the DFIG and the required inertia response power at the grid frequency drops, respectively. Based on one inconstant wind speed model and the SCESS-DFIG system model adopting the control strategy established, one power grid system consisting of three SCESS-DFIGs with different wind speed trends and a synchronous generator was simulated. The simulation results verified the effectiveness of the SCESS-DFIG system structure and the control strategy proposed.

Power synergistic control between of power‐to‐hydrogen and SCESS‐DFIG considering “source–load” turbulence

“…The typology we employ to reduce the cost of land and converter investment required for the installation of the supercapacitor is shown in box 4 of Figure 1, which uses the DFIG as a common type of wind turbine [23][24][25]. Under this topology, the supercapacitor is distributed inside each fan and is connected to the fan's DC bus in parallel via a DC-DC converter, where energy is exchanged with the grid via a grid side converter (GSC), as shown in Figure 4 [23].…”

An Adaptive Frequency Strategy for Variable Speed Wind Turbines: Application to High Wind Integration Into Power Systems

“…For this reason, frequency control strategies are being developed to effectively integrate Variable Speed Wind Turbines (VSWTs) into the grid, in order to replace conventional power plants by maintaining a secure power system operation [15]. Most of them are based on 'hidden inertia emulation', in order to enhance the inertia response of VSWTs [16,17]. A classification for different control strategies based on principles for inertia emulation concept can be found in [18].…”

Fast Power Reserve Emulation Strategy for VSWT Supporting Frequency Control in Multi-Area Power Systems

“…These new strategies would allow us to integrate Variable Speed Wind Turbines (VSWTs) into these services, replacing conventional power plants by renewables [12] and maintaining a reliable power system operation [13]. Most of the proposed strategies for VSWTs are based on 'hidden inertia emulation', enhancing their inertia response [14][15][16]. According to the specific literature, 'Fast power reserve emulation' has been proposed as a suitable solution.…”